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Sample records for enantiomerically pure siderophore

  1. Synthesis of diastereomerically and enantiomerically pure 2,3-disubstituted tetrahydrofurans using a sulfoxonium ylide.

    Science.gov (United States)

    Schomaker, Jennifer M; Pulgam, Veera Reddy; Borhan, Babak

    2004-10-27

    Nucleophilic substitution reactions of 2,3-epoxy alcohols, easily prepared via Sharpless asymmetric epoxidation chemistry, offer access to a wide variety of enantiomerically pure compounds. In this communication, we describe the use of a Payne rearrangement to control regioselectivity in the ring-opening of a series of 2,3-epoxy alcohols with dimethylsulfoxonium methylide to yield diastereomerically and/or enantiomerically pure disubstituted tetrahydrofuran rings. The factors influencing the success and substitution pattern of the THF ring products are discussed, including steric, electronic, and solvent effects.

  2. Synthesis and biological evaluation of enantiomerically pure cyclopropyl analogues of combretastatin A4.

    Science.gov (United States)

    Ty, Nancy; Pontikis, Renée; Chabot, Guy G; Devillers, Emmanuelle; Quentin, Lionel; Bourg, Stéphane; Florent, Jean-Claude

    2013-03-01

    To evaluate the influence of stereochemistry on biological activities of cis-cyclopropyl combretastatin A4 (CA4) analogues, we have prepared several cyclopropyl compounds in their pure enantiomeric forms. The key reactions in our synthesis are the cyclopropanation of a (Z)-alkenylboron compound bearing a chiral auxiliary, and the cross-coupling of both enantiomeric cyclopropyl trifluoroborate salts with aryl and olefinic halides. Three pairs of cis-cyclopropyl CA4 analogues were evaluated for their potential antivascular activities. The diarylcyclopropyl compounds with SR-configuration (-)-1b, (-)-2b and the cyclopropylvinyl enantiomer (+)-3a with RR-configuration were the most potent tubulin polymerization inhibitors. A correlation was noted between anti-tubulin activity and rounding up activity of endothelial cells. The cytotoxic activity on B16 melanoma cells was in the submicromolar range for most compounds, but unlike the anti-tubulin activity, there was no difference in cytotoxic activity between racemic and enantiomerically pure forms for the three series of compounds. Molecular docking studies within the colchicine binding site of tubulin were in good agreement with the tubulin polymerization inhibitory data and confirmed the importance of the configuration of the synthesized cis-cyclopropyl CA4 analogues for potential antivascular activities. Copyright © 2013. Published by Elsevier Ltd.

  3. Synthesis and Absolute Configuration of Enantiomerically Pure Vitamin K3 2,3-Epoxide

    NARCIS (Netherlands)

    Snatzke, Günther; Wijnberg, Hans; Feringa, Bernard; Marsman, Bea G.; Greydanus, Ben; Pluim, Henk

    1980-01-01

    The 2,3-epoxide of vitamin K3 (menadione, 1) has been prepared in enantiomerically pure form, and the absolute configuration has been deduced from the CD spectrum. The compound with the negative Cotton effect between 340 and 400 nm has the 2R,3S configuration.

  4. Production of enantiomerically pure D-Phenylglycine using Pseudomonas aeruginosa 10145 as biocatalyst

    Directory of Open Access Journals (Sweden)

    F. O. M. Alonso

    2008-03-01

    Full Text Available Different bacterial strains were screened to detect nitrilase and/or nitrile hidratase/amidase activities towards benzonitrile, to be used as biocatalyst to produce enantiomerically pure non-proteinogenic amino acids using amino nitriles as starting material. The best biocatalyst found was Pseudomonas aeruginosa 10145, which showed high enzyme activities. Whole cells were used as catalyst for the transformation of 2-phenyl-2-amino-acetonitrile for the corresponding D-phenylglycine. The percentage conversion was followed by chiral HPLC. After 1 hour reaction 18% of 2-phenyl-2-amino-acetonitrile was converted into D-phenylglycine with an enantiomeric excess of over 95%. When an inducer was added to the media, an increase in nitrile hydrolyzing activities was detected, hence leading to total conversion of (R-2-phenyl-2-amino-acetonitrile to the corresponding amino acid in 30 min reaction. The isolated yield of the target product was 50% and its characterization was performed by polarimetry, chiral HPLC, IR-FT spectroscopy and GC-MS.

  5. Chemoenzymatic Dynamic Kinetic Resolution: A Powerful Tool for the Preparation of Enantiomerically Pure Alcohols and Amines

    Science.gov (United States)

    2015-01-01

    Chemoenzymatic dynamic kinetic resolution (DKR) constitutes a convenient and efficient method to access enantiomerically pure alcohol and amine derivatives. This Perspective highlights the work carried out within this field during the past two decades and pinpoints important avenues for future research. First, the Perspective will summarize the more developed area of alcohol DKR, by delineating the way from the earliest proof-of-concept protocols to the current state-of-the-art systems that allows for the highly efficient and selective preparation of a wide range of enantiomerically pure alcohol derivatives. Thereafter, the Perspective will focus on the more challenging DKR of amines, by presenting the currently available homogeneous and heterogeneous methods and their respective limitations. In these two parts, significant attention will be dedicated to the design of efficient racemization methods as an important means of developing milder DKR protocols. In the final part of the Perspective, a brief overview of the research that has been devoted toward improving enzymes as biocatalysts is presented. PMID:25730714

  6. Tris[(6S)-6-hy-droxy-4-epi-shikimic acid] monohydrate: an enanti-omerically pure hy-droxy-lated shikimic acid derived from methyl shikimate.

    Science.gov (United States)

    Griesbeck, Axel G; Miara, Claus; Neudörfl, Jörg-M

    2012-11-01

    The title compound, 3C(7)H(10)O(6)·H(2)O, is the enanti-omerically pure product of a multi-step synthesis from the enanti-omerically pure natural shikimic acid. The asymmetric unit contains three mol-ecules of the acid and one mol-ecule of water. The cyclo-hexene rings of the acids have half-chair conformations. The carboxyl-ate, the four hydroxide groups and the additional water mol-ecule form a complex three-dimensional hydrogen-bonding network.

  7. A new and expeditious synthesis of all enantiomerically pure stereoisomers of rosaprostol, an antiulcer drug

    Directory of Open Access Journals (Sweden)

    Wiesława Perlikowska

    2016-10-01

    Full Text Available Four enantiomerically pure stereoisomers of rosaprostol (1, an antiulcer drug, were efficiently synthesized from the enantiomers of 2-(dimethoxyphosphoryl-3-hexylcyclopentanone (3 as chiral substrates. The latter were obtained by resolution of racemic 3 with (+-(R-1-(1-naphthylethylamine. The conversion of (+-3 into rosaprostol stereoisomer (−-1a was accomplished in four steps in 56% overall yield. According to the same protocol, the second stereoisomer (+-1c was obtained from (−-3 in 55% overall yield. A slightly improved procedure of the last two steps of the transformation of (+-3 into (−-1a allowed an increase in the overall yield to 64%. The remaining two stereoisomers, (−-1b and (+-1d, were obtained from (−-1a and (+-1c in 71 and 68% yield, respectively, by a two-reaction sequence, in which a Mitsunobu inversion of configuration at C-5 was the key step.

  8. One-pot synthesis of enantiomerically pure N-protected allylic amines from N-protected α-amino esters

    Directory of Open Access Journals (Sweden)

    Gastón Silveira-Dorta

    2016-05-01

    Full Text Available An improved protocol for the synthesis of enantiomerically pure allylic amines is reported. N-Protected α-amino esters derived from natural amino acids were submitted to a one-pot tandem reduction–olefination process. The sequential reduction with DIBAL-H at −78 °C and subsequent in situ addition of organophosphorus reagents yielded the corresponding allylic amines without the need to isolate the intermediate aldehyde. This circumvents the problem of instability of the aldehydes. The method tolerates well both Wittig and Horner–Wadsworth–Emmons organophosphorus reagents. A better Z-(diastereoselectivity was observed when compared to the previous one-pot method. The (diastereoselectivity of the process was affected neither by the reaction solvent nor by the amount of DIBAL-H employed. The method is compatible with the presence of free hydroxy groups as shown with serine and threonine derivatives.

  9. Enantiomeric distribution of major chiral volatile organic compounds in juniper-flavored distillates.

    Science.gov (United States)

    Pažitná, Alexandra; Spánik, Ivan

    2014-02-01

    The enantiomeric ratios of chiral volatile organic compounds in juniper-flavored spirits produced by various processing technologies in different EU countries were determined by multidimensional GC using solid-phase microextraction and liquid-liquid extraction as a sample pretreatment procedure. In total, more than 260 compounds were detected in studied spirits from which linalool, α-terpineol, 4-terpineol, linalool oxides, α-pinene, and verbenone were selected for enantiomeric separation. The significant differences in enantiomeric ratio of linalool and cis-linalool oxide allowed us to distinguish between samples produced in Slovakia and the United Kingdom from those produced in Germany, Czech Republic, and Belgium. The pure enantiomer of trans-linalool oxide was found only in samples from Germany. It was shown that the enantiomeric ratio is independent of the sample treatment procedure, and only small differences up to 1% were observed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Hydroxamate siderophores of the ectomycorrhizal fungi Suillus granulatus and S. luteus.

    Science.gov (United States)

    Haselwandter, Kurt; Häninger, Gerlinde; Ganzera, Markus

    2011-02-01

    Despite indications that S. granulatus and S. luteus release iron-chelating compounds, the exact spectrum of ferric hydroxamates synthesized by these two Suillus species remained unclear. Hence the aim of this study was to identify all of the main siderophores produced by these two ectomycorrhizal fungal species under pure culture conditions. By means of HPLC and LC-MS analyses we show that S. granulatus releases cyclic and linear fusigen, ferrichrome, coprogen and triacetylfusarinine C into the nutrient medium, while S. luteus culture filtrates contain cyclic and linear fusigen, ferricrocin and coprogen. All of the different siderophores were identified on basis of reference compounds and their specific MS spectra which were recorded on a high resolution MS in positive electrospray ionisation mode. Initial HPLC separations were performed on a C-18 stationary phase, using an acidic eluent (0.1% formic acid in water and acetonitrile) in gradient mode. The potential of these two ectomycorrhizal fungal species to produce siderophores representing three different groups of hydroxamates is discussed in relation to its ecological significance.

  11. Enantiomeric Mixtures in Natural Product Chemistry: Separation and Absolute Configuration Assignment.

    Science.gov (United States)

    N L Batista, Andrea; M Dos Santos, Fernando; Batista, João M; Cass, Quezia B

    2018-02-23

    Chiral natural product molecules are generally assumed to be biosynthesized in an enantiomerically pure or enriched fashion. Nevertheless, a significant amount of racemates or enantiomerically enriched mixtures has been reported from natural sources. This number is estimated to be even larger since the enantiomeric purity of secondary metabolites is rarely checked in the natural product isolation pipeline. This latter fact may have drastic effects on the evaluation of the biological activity of chiral natural products. A second bottleneck is the determination of their absolute configurations. Despite the widespread use of optical rotation and electronic circular dichroism, most of the stereochemical assignments are based on empirical correlations with similar compounds reported in the literature. As an alternative, the combination of vibrational circular dichroism and quantum chemical calculations has emerged as a powerful and reliable tool for both conformational and configurational analysis of natural products, even for those lacking UV-Vis chromophores. In this review, we aim to provide the reader with a critical overview of the occurrence of enantiomeric mixtures of secondary metabolites in nature as well the best practices for their detection, enantioselective separation using liquid chromatography, and determination of absolute configuration by means of vibrational circular dichroism and density functional theory calculations.

  12. Catecholate siderophores protect bacteria from pyochelin toxicity.

    Directory of Open Access Journals (Sweden)

    Conrado Adler

    Full Text Available Bacteria produce small molecule iron chelators, known as siderophores, to facilitate the acquisition of iron from the environment. The synthesis of more than one siderophore and the production of multiple siderophore uptake systems by a single bacterial species are common place. The selective advantages conferred by the multiplicity of siderophore synthesis remains poorly understood. However, there is growing evidence suggesting that siderophores may have other physiological roles besides their involvement in iron acquisition.Here we provide the first report that pyochelin displays antibiotic activity against some bacterial strains. Observation of differential sensitivity to pyochelin against a panel of bacteria provided the first indications that catecholate siderophores, produced by some bacteria, may have roles other than iron acquisition. A pattern emerged where only those strains able to make catecholate-type siderophores were resistant to pyochelin. We were able to associate pyochelin resistance to catecholate production by showing that pyochelin-resistant Escherichia coli became sensitive when biosynthesis of its catecholate siderophore enterobactin was impaired. As expected, supplementation with enterobactin conferred pyochelin resistance to the entE mutant. We observed that pyochelin-induced growth inhibition was independent of iron availability and was prevented by addition of the reducing agent ascorbic acid or by anaerobic incubation. Addition of pyochelin to E. coli increased the levels of reactive oxygen species (ROS while addition of ascorbic acid or enterobactin reduced them. In contrast, addition of the carboxylate-type siderophore, citrate, did not prevent pyochelin-induced ROS increases and their associated toxicity.We have shown that the catecholate siderophore enterobactin protects E. coli against the toxic effects of pyochelin by reducing ROS. Thus, it appears that catecholate siderophores can behave as protectors of

  13. Microbial siderophores and their potential applications: a review.

    Science.gov (United States)

    Saha, Maumita; Sarkar, Subhasis; Sarkar, Biplab; Sharma, Bipin Kumar; Bhattacharjee, Surajit; Tribedi, Prosun

    2016-03-01

    Siderophores are small organic molecules produced by microorganisms under iron-limiting conditions which enhance the uptake of iron to the microorganisms. In environment, the ferric form of iron is insoluble and inaccessible at physiological pH (7.35-7.40). Under this condition, microorganisms synthesize siderophores which have high affinity for ferric iron. These ferric iron-siderophore complexes are then transported to cytosol. In cytosol, the ferric iron gets reduced into ferrous iron and becomes accessible to microorganism. In recent times, siderophores have drawn much attention due to its potential roles in different fields. Siderophores have application in microbial ecology to enhance the growth of several unculturable microorganisms and can alter the microbial communities. In the field of agriculture, different types of siderophores promote the growth of several plant species and increase their yield by enhancing the Fe uptake to plants. Siderophores acts as a potential biocontrol agent against harmful phyto-pathogens and holds the ability to substitute hazardous pesticides. Heavy-metal-contaminated samples can be detoxified by applying siderophores, which explicate its role in bioremediation. Siderophores can detect the iron content in different environments, exhibiting its role as a biosensor. In the medical field, siderophore uses the "Trojan horse strategy" to form complexes with antibiotics and helps in the selective delivery of antibiotics to the antibiotic-resistant bacteria. Certain iron overload diseases for example sickle cell anemia can be treated with the help of siderophores. Other medical applications of siderophores include antimalarial activity, removal of transuranic elements from the body, and anticancer activity. The aim of this review is to discuss the important roles and applications of siderophores in different sectors including ecology, agriculture, bioremediation, biosensor, and medicine.

  14. The evolution of siderophore production as a competitive trait.

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    Niehus, Rene; Picot, Aurore; Oliveira, Nuno M; Mitri, Sara; Foster, Kevin R

    2017-06-01

    Microbes have the potential to be highly cooperative organisms. The archetype of microbial cooperation is often considered to be the secretion of siderophores, molecules scavenging iron, where cooperation is threatened by "cheater" genotypes that use siderophores without making them. Here, we show that this view neglects a key piece of biology: siderophores are imported by specific receptors that constrain their use by competing strains. We study the effect of this specificity in an ecoevolutionary model, in which we vary siderophore sharing among strains, and compare fully shared siderophores with private siderophores. We show that privatizing siderophores fundamentally alters their evolution. Rather than a canonical cooperative good, siderophores become a competitive trait used to pillage iron from other strains. We also study the physiological regulation of siderophores using in silico long-term evolution. Although shared siderophores evolve to be downregulated in the presence of a competitor, as expected for a cooperative trait, privatized siderophores evolve to be upregulated. We evaluate these predictions using published experimental work, which suggests that some siderophores are upregulated in response to competition akin to competitive traits like antibiotics. Although siderophores can act as a cooperative good for single genotypes, we argue that their role in competition is fundamental to understanding their biology. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  15. Microbial siderophore-based iron assimilation and therapeutic applications.

    Science.gov (United States)

    Li, Kunhua; Chen, Wei-Hung; Bruner, Steven D

    2016-06-01

    Siderophores are structurally diverse, complex natural products that bind metals with extraordinary specificity and affinity. The acquisition of iron is critical for the survival and virulence of many pathogenic microbes and diverse strategies have evolved to synthesize, import and utilize iron. There has been a substantial increase of known siderophore scaffolds isolated and characterized in the past decade and the corresponding biosynthetic gene clusters have provided insight into the varied pathways involved in siderophore biosynthesis, delivery and utilization. Additionally, therapeutic applications of siderophores and related compounds are actively being developed. The study of biosynthetic pathways to natural siderophores augments the understanding of the complex mechanisms of bacterial iron acquisition, and enables a complimentary approach to address virulence through the interruption of siderophore biosynthesis or utilization by targeting the key enzymes to the siderophore pathways.

  16. Siderophore-promoted dissolution of smectite by fluorescent Pseudomonas.

    Science.gov (United States)

    Ferret, Claire; Sterckeman, Thibault; Cornu, Jean-Yves; Gangloff, Sophie; Schalk, Isabelle J; Geoffroy, Valérie A

    2014-10-01

    Siderophores are organic chelators produced by microorganisms to fulfil their iron requirements. Siderophore-promoted dissolution of iron-bearing minerals has been clearly documented for some siderophores, but few studies have addressed metabolizing siderophore-producing bacteria. We investigated iron acquisition from clays by fluorescent Pseudomonads, bacteria that are ubiquitous in the environment. We focused on the interactions between smectite and Pseudomonas aeruginosa, a bacterium producing two structurally different siderophores: pyoverdine and pyochelin. The presence of smectite in iron-limited growth media promoted planktonic growth of P. aeruginosa and biofilm surrounding the smectite aggregates. Chemical analysis of the culture media indicated increases in the dissolved silicon, iron and aluminium concentrations following smectite supplementation. The use of P. aeruginosa mutants unable to produce either one or both of the two siderophores indicated that pyoverdine, the siderophore with the higher affinity for iron, was involved in iron and aluminium solubilization by the wild-type strain. However, in the absence of pyoverdine, pyochelin was also able to solubilize iron but with a twofold lower efficiency. In conclusion, pyoverdine and pyochelin, two structurally different siderophores, can solubilize structural iron from smectite and thereby make it available for bacterial growth.

  17. Pirated Siderophores Promote Sporulation in Bacillus subtilis.

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    Grandchamp, Gabrielle M; Caro, Lews; Shank, Elizabeth A

    2017-05-15

    In microbial communities, bacteria chemically and physically interact with one another. Some of these interactions are mediated by secreted specialized metabolites that act as either intraspecies or interspecies signals to alter gene expression and to change cell physiology. Bacillus subtilis is a well-characterized soil microbe that can differentiate into multiple cell types, including metabolically dormant endospores. We were interested in identifying microbial interactions that affected sporulation in B. subtilis Using a fluorescent transcriptional reporter, we observed that coculturing B. subtilis with Escherichia coli promoted sporulation gene expression via a secreted metabolite. To identify the active compound, we screened the E. coli Keio Collection and identified the sporulation-accelerating cue as the siderophore enterobactin. B. subtilis has multiple iron acquisition systems that are used to take up the B. subtilis- produced siderophore bacillibactin, as well as to pirate exogenous siderophores such as enterobactin. While B. subtilis uses a single substrate binding protein (FeuA) to take up both bacillibactin and enterobactin, we discovered that it requires two distinct genes to sporulate in response to these siderophores (the esterase gene besA for bacillibactin and a putative esterase gene, ybbA , for enterobactin). In addition, we found that siderophores from a variety of other microbial species also promote sporulation in B. subtilis Our results thus demonstrate that siderophores can act not only as bacterial iron acquisition systems but also as interspecies cues that alter cellular development and accelerate sporulation in B. subtilis IMPORTANCE While much is known about the genetic regulation of Bacillus subtilis sporulation, little is understood about how other bacteria influence this process. This work describes an interaction between Escherichia coli and B. subtilis that accelerates sporulation in B. subtilis The interaction is mediated by the E

  18. Plant mechanisms of siderophore-iron utilization

    International Nuclear Information System (INIS)

    Crowley, D.E.

    1986-01-01

    Mechanisms of siderophore iron-utilization by plants were examined to determine whether plants have direct mechanisms for acquiring iron from microbially-produced hydroxamate siderophores or simply take up inorganic iron in equilibrium with the chelate (shuttle mechanism). Experiments were designed to determine whether the monocot plant species, oat (Avena sativa L. cv. Victory) could acquire iron from ferrichrome under hydroponic conditions in which iron uptake was most likely to occur by direct use of the chelating agent. Ten-day-old iron-deficient seedlings, grown in aerated Hoagland's nutrient solution (minus iron) buffered at pH 7.4 with CaCO 3 , were placed in fresh nutrient solution containing 10/sup -7.4/M radioactive 55 FeCl 3 (23.7 mCi/mg) with the synthetic chelate, EDDHA (10π 5 M), ferrichrome (10 -5 M), or with no chelate. After 6 days, shoot content of 55 Fe in shoots of plants provided with ferrichrome was 100-fold greater than that in shoots of plants provided with EDDHA. Therefore iron uptake by oat under these conditions not only indicates direct use of ferrichrome, but also suggest that oat may be better able to acquire iron from siderophores than from synthetic chelates. One possible mechanism for direct use of chelating agents, may involve siderophore binding sites on the plasmalemma of root cortical cells where iron is split from the chelate by enzymatic reduction of ferric to ferrous iron. To demonstrate hypothesized siderophore binding sites on oat roots, experiments examined possible competition for presumed siderophore binding sites by an inert analog of ferrichrome constructed by irreversible chelation with chromium

  19. Inhibition of the Flavin-Dependent Monooxygenase Siderophore A (SidA) Blocks Siderophore Biosynthesis and Aspergillus fumigatus Growth.

    Science.gov (United States)

    Martín Del Campo, Julia S; Vogelaar, Nancy; Tolani, Karishma; Kizjakina, Karina; Harich, Kim; Sobrado, Pablo

    2016-11-18

    Aspergillus fumigatus is an opportunistic fungal pathogen and the most common causative agent of fatal invasive mycoses. The flavin-dependent monooxygenase siderophore A (SidA) catalyzes the oxygen and NADPH dependent hydroxylation of l-ornithine (l-Orn) to N 5 -l-hydroxyornithine in the biosynthetic pathway of hydroxamate-containing siderophores in A. fumigatus. Deletion of the gene that codes for SidA has shown that it is essential in establishing infection in mice models. Here, a fluorescence polarization high-throughput assay was used to screen a 2320 compound library for inhibitors of SidA. Celastrol, a natural quinone methide, was identified as a noncompetitive inhibitor of SidA with a MIC value of 2 μM. Docking experiments suggest that celastrol binds across the NADPH and l-Orn pocket. Celastrol prevents A. fumigatus growth in blood agar. The addition of purified ferric-siderophore abolished the inhibitory effect of celastrol. Thus, celastrol inhibits A. fumigatus growth by blocking siderophore biosynthesis through SidA inhibiton.

  20. Siderophore-based immunization strategy to inhibit growth of enteric pathogens.

    Science.gov (United States)

    Sassone-Corsi, Martina; Chairatana, Phoom; Zheng, Tengfei; Perez-Lopez, Araceli; Edwards, Robert A; George, Michael D; Nolan, Elizabeth M; Raffatellu, Manuela

    2016-11-22

    Infections with Gram-negative pathogens pose a serious threat to public health. This scenario is exacerbated by increases in antibiotic resistance and the limited availability of vaccines and therapeutic tools to combat these infections. Here, we report an immunization approach that targets siderophores, which are small molecules exported by enteric Gram-negative pathogens to acquire iron, an essential nutrient, in the host. Because siderophores are nonimmunogenic, we designed and synthesized conjugates of a native siderophore and the immunogenic carrier protein cholera toxin subunit B (CTB). Mice immunized with the CTB-siderophore conjugate developed anti-siderophore antibodies in the gut mucosa, and when mice were infected with the enteric pathogen Salmonella, they exhibited reduced intestinal colonization and reduced systemic dissemination of the pathogen. Moreover, analysis of the gut microbiota revealed that reduction of Salmonella colonization in the inflamed gut was accompanied by expansion of Lactobacillus spp., which are beneficial commensal organisms that thrive in similar locales as Enterobacteriaceae. Collectively, our results demonstrate that anti-siderophore antibodies inhibit Salmonella colonization. Because siderophore-mediated iron acquisition is a virulence trait shared by many bacterial and fungal pathogens, blocking microbial iron acquisition by siderophore-based immunization or other siderophore-targeted approaches may represent a novel strategy to prevent and ameliorate a broad range of infections.

  1. Siderophore: Structural And Functional Characterisation – A Comprehensive Review

    Directory of Open Access Journals (Sweden)

    Sah Stuti

    2015-09-01

    Full Text Available Plants and microbes have enormous importance in our daily life. Iron is said to be the fourth most abundant element in the earth's crust from soil, still many plants face problem in uptaking iron because it is found in insoluble form, which severely restricts the bioavailability of this metal. In response to this, microorganisms present in soil such as Pseudomonas sp., Enterobacter genera, Bacillus and Rhodococcus produce special iron carriers or iron-binding compounds called as ‘siderphores’ or ‘siderochromes’. This paper is an attempt to review the importance of siderphores in enhancing plants’ iron utilisation strategies, the mode of transport of siderophores along with iron across the memberane and depending on the difference in their chemical structure, functional moiety and their source of isolation of four different types of siderophore (hydroxamates, catecholates, carboxylates and siderophore with mixed ligand. Siderophore and their derivative have large application in agriculture as to increase soil fertility and as biocontrol for fungal pathogen. This review unlike other reviews includes (1 types of siderophore, (2 the structural difference amongst them, (3 siderophore biosynthesis, (4 transport mechanism, (5 the genetics of siderophore and (6 their efficacy in human life.

  2. Microbial production of four biodegradable siderophores under submerged fermentation.

    Science.gov (United States)

    Fazary, Ahmed E; Al-Shihri, Ayed S; Alfaifi, Mohammad Y; Saleh, Kamel A; Alshehri, Mohammed A; Elbehairi, Serag Eldin I; Ju, Yi-Hsu

    2016-07-01

    Four siderophore analogues were isolated and purified from Escherichia coli, Bacillus spp. ST13, and Streptomyces pilosus microorganisms under some specific submerged fermentation conditions. In order to evaluate the highest production of this siderophore analogues through the growth, a rapid spectrophotometric screening semi-quantitative method was used, in which interestingly the analogues were isolated in its own form not its iron chelate. After chromatographic separation, the chemical structures of the isolated and purified siderophores were illustrated using detailed spectroscopic techniques. The biodegradation studies were done on that four novel isolated and purified siderophores following OECD protocols. In addition, the bioactivities of these siderophores and their iron complexes were examined and evaluated. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Synthesis of Enantiomerically Pure 6-Substituted-Piperazine-2-Acetic Acid Esters as Intermediates for Library Production.

    Science.gov (United States)

    Chamakuri, Srinivas; Jain, Prashi; Guduru, Shiva Krishna Reddy; Arney, Joseph Winston; MacKenzie, Kevin; Santini, Conrad; Young, Damian W

    2018-05-11

    Amino acids from the chiral pool have been used to produce a 24-member branch of 2,6-disubstituted piperazine scaffolds suitable for use in compound library production. Each scaffold was obtained as a single absolute stereoisomer in multi-gram quantities. Stereochemistry was confirmed by 2D NMR protocols and enantiomeric purity was determined by chiral HPLC. The scaffolds are intended for use as intermediates in parallel synthesis of small-molecule libraries.

  4. Fungal NRPS-dependent siderophores: From function to prediction

    DEFF Research Database (Denmark)

    Sørensen, Jens Laurids; Knudsen, Michael; Hansen, Frederik Teilfeldt

    2014-01-01

    discuss the function of siderophores in relation to fungal iron uptake mechanisms and their importance for coexistence with host organisms. The chemical nature of the major groups of siderophores and their regulation is described along with the function and architecture of the large multi-domain enzymes...... responsible for siderophore synthesis, namely the non-ribosomal peptide synthetases (NRPSs). Finally, we present the most recent advances in our understanding of the structural biology of fungal NRPSs and discuss opportunities for the development of a fungal NRPS prediction server...

  5. Genetic diversity of siderophore-producing bacteria of tobacco rhizosphere

    OpenAIRE

    Tian, Fang; Ding, Yanqin; Zhu, Hui; Yao, Liangtong; Du, Binghai

    2009-01-01

    The genetic diversity of siderophore-producing bacteria of tobacco rhizosphere was studied by amplified ribosomal DNA restriction analysis (ARDRA), 16S rRNA sequence homology and phylogenetics analysis methods. Studies demonstrated that 85% of the total 354 isolates produced siderophores in iron limited liquid medium. A total of 28 ARDRA patterns were identified among the 299 siderophore-producing bacterial isolates. The 28 ARDRA patterns represented bacteria of 14 different genera belonging ...

  6. Bacterial Siderophores and their Biotechnological applications

    Digital Repository Service at National Institute of Oceanography (India)

    Mohandass, C.

    Siderophores and their Biotechnological applications C. Mohandass Biological Oceanography Division National Institute of Oceanography Dona-paula, Goa.403 004.India. Introduction Siderophore is the Greek phrase for ?iron bearer? and is applied to molecules... the efficiency of the biological carbon pump. Phytoplankton must have developed a sophisticated mechanism to uptake iron. However, little is known about the uptake mechanism. Given the importance of the biological pump in controlling atmospheric CO2, elucidating...

  7. Gas-chromatographic resolution of enantiomeric secondary alcohols. Stereoselective reductive metabolism of ketones in rabbit-liver cytosol.

    Science.gov (United States)

    Gal, J; DeVito, D; Harper, T W

    1981-01-01

    Chiral secondary alcohols were treated with (S)-(-)-1-phenylethyl isocyanate. For each racemic alcohol, the resulting diastereomeric urethane derivatives were resolved on flexible fused-silica capillary GLC columns with retention times of 15 min or less. Derivatization of individual enantiomers showed that the urethane derivatives of (R)-(-)-2-octanol, (R)-(+)-1-phenylethyl alcohol, and (S)-(+)-2,2,2-trifluoro-1-phenylethanol are eluted before the corresponding diastereomers. The procedure is simple and rapid, and is suitable for the determination of the enantiomeric composition of chiral alcohols extracted from biological media. A series of aliphatic alcohols, aryl alkyl carbinols, and arylalkyl alkyl carbinols were resolved with the procedure, and the degree of resolution varied from good to excellent. Eight achiral ketones were incubated, individually, with rabbit-liver 90,000 g supernatant fractions, and the enantiomeric composition of the alcohol metabolites was determined with the GLC procedure. The reductions proceeded with high stereoselectivity to give alcohol products of 90% or greater enantiomeric purity. The reduction of 2-octanone and acetophenone gave predominant alcohols of (S)-configuration, in agreement with the Baumann-Prelog rule. The configuration of the predominant alcohols arising in the reduction of the remainder of the ketones could not be firmly established, but the evidence suggests that they are also of the (S)-configuration. Fluorine or methyl substitution in the ortho position of acetophenone produced an increase in the stereoselectivity, and the alcohol produced from ortho-methylacetophenone was enantiomerically greater than 99% pure.

  8. Spatially resolved NEXAFS spectroscopy of siderophores in biological matrices

    International Nuclear Information System (INIS)

    Thieme, J; Kilcoyne, D; Tyliszczak, T; Haselwandter, K

    2013-01-01

    Iron is an essential nutrient for almost all forms of life. In the presence of oxygen iron is present in its ferric form which precipitates under formation of rather insoluble oxide-hydroxide polymers. Hence the bioavailability of iron is extremely low ( −17 M at pH 7 for Fe 3+ ). Under such conditions almost all microorganisms synthesize siderophores as iron chelating agents, thus solubilizing ferric iron from rather insoluble iron sources. Siderophores form soluble complexes with Fe 3+ . The present study aims at developing a methodology that would allow for the specific detection and localization of such iron chelators in their natural environment. The applicability of spatially resolved NEXAFS spectroscopy in the soft X-ray energy (E < 1 keV) range was evaluated for localization of typical fungal hydroxamate siderophores like ferrichrome or coprogen, which can be present in various biological materials. Results obtained with the scanning transmission X-ray microscopes at beamlines 11.0.2 and 5.3.2 of the ALS have shown characteristic signatures for siderophores. Thus NEXAFS spectroscopy at the carbon K-edge, nitrogen K-edge and iron L-edge with high spatial resolution has proven to be extremely useful for their identification in their natural environment. Spectra of different siderophores as well as spectra and images of biological material containing siderophores are presented

  9. Siderophore-drug complexes: potential medicinal applications of the 'Trojan horse' strategy.

    Science.gov (United States)

    Górska, Agnieszka; Sloderbach, Anna; Marszałł, Michał Piotr

    2014-09-01

    The ability of bacteria to develop resistance to antimicrobial agents poses problems in the treatment of numerous bacterial infections. One method to circumvent permeability-mediated drug resistance involves the employment of the 'Trojan horse' strategy. The Trojan horse concept involves the use of bacterial iron uptake systems to enter and kill bacteria. The siderophore-drug complex is recognized by specific siderophore receptors and is then actively transported across the outer membrane. The recently identified benefits of this strategy have led to the synthesis of a series of siderophore-based antibiotics. Several studies have shown that siderophore-drug conjugates make it possible to design antibiotics with improved cell transport and reduce the frequency of resistance mutants. Growing interest in siderophore-drug conjugates for the treatment of human diseases including iron overload, cancer, and malaria has driven the search for new siderophore-drug complexes. This strategy may have special importance for the development of iron oxide nanoparticle-based therapeutics. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Siderophore production by pathogenic mucorales and uptake of deferoxamine B.

    Science.gov (United States)

    Larcher, Gérald; Dias, Marylène; Razafimandimby, Bienvenue; Bomal, Danielle; Bouchara, Jean-Philippe

    2013-12-01

    Clinical reports have established that mucormycosis, mainly caused by Rhizopus spp., frequently occurs in patients treated with deferoxamine B (DFO, Desferal(®)) which is misappropriated by these fungi. Siderophore production by twenty mucoralean isolates was therefore investigated using a commercial iron-depleted culture medium. Siderophore production was detected for most of the isolates. Our experiments confirmed that feroxamine B (iron chelate of DFO) promoted in vitro growth of Rhizopus arrhizus. Electrophoretic analysis of somatic extracts revealed iron-regulated proteins of 60 and 32 kDa which were lacking in iron-depleted culture conditions. Using a fluorescent derivative of deferoxamine B, we showed by fluorescence microscopy the entry of the siderophore within the fungal cells, thus suggesting a shuttle mechanism encompassing the uptake of the entire siderophore-ion complex into the cell. This useful tool renders possible a better understanding of iron metabolism in Mucorales which could lead to the development of new diagnostic method or new antifungal therapy using siderophores as imaging contrast agents or active drug vectors.

  11. Access to Optically Pure β-Hydroxy Esters via Non-Enzymatic Kinetic Resolution by a Planar-Chiral DMAP Catalyst

    Directory of Open Access Journals (Sweden)

    Alba E. Díazlvarez

    2014-09-01

    Full Text Available The development of new approaches to obtain optically pure β-hydroxy esters is an important area in synthetic organic chemistry since they are precursors of other high value compounds. Herein, the kinetic resolution of racemic β-hydroxy esters using a planar-chiral DMAP derivative catalyst is presented. Following this procedure, a range of aromatic β-hydroxy esters was obtained in excellent selectivities (up to s = 107 and high enantiomeric excess (up to 99% ee. Furthermore, the utility of the present method was demonstrated in the synthesis of (S-3-hydroxy-N-methyl-3-phenylpropanamide, a key intermediate for bioactive molecules such as fluoxetine, tomoxetine or nisoxetine, in its enantiomerically pure form.

  12. AmcA - a putative mitochondrial ornithine transporter supporting fungal siderophore biosynthesis

    Directory of Open Access Journals (Sweden)

    Lukas eSchafferer

    2015-04-01

    Full Text Available Iron is an essential nutrient required for a wide range of cellular processes. The opportunistic fungal pathogen Aspergillus fumigatus employs low-molecular mass iron-specific chelators, termed siderophores, for uptake, storage and intracellular iron distribution, which play a crucial role in the pathogenicity of this fungus. Siderophore biosynthesis depends on coordination with the supply of its precursor ornithine, produced mitochondrially from glutamate or cytosolically via hydrolysis of arginine. In this study, we demonstrate a role of the putative mitochondrial transporter AmcA (AFUA_8G02760 in siderophore biosynthesis of A. fumigatus.Consistent with a role in cellular ornithine handling, AmcA-deficiency resulted in decreased cellular ornithine and arginine contents as well as decreased siderophore production on medium containing glutamine as the sole nitrogen source. In support, arginine and ornithine as nitrogen sources did not impact siderophore biosynthesis due to cytosolic ornithine availability. As revealed by Northern blot analysis, transcript levels of siderophore biosynthetic genes were unresponsive to the cellular ornithine level. In contrast to siderophore production, AmcA deficiency did only mildly decrease the cellular polyamine content, demonstrating cellular prioritization of ornithine use. Nevertheless, AmcA-deficiency increased the susceptibility of A. fumigatus to the polyamine biosynthesis inhibitor eflornithine, most likely due to the decreased ornithine pool. AmcA-deficiency decreased the growth rate particularly on ornithine as the sole nitrogen source during iron starvation and sufficiency, indicating an additional role in the metabolism and fitness of A. fumigatus, possibly in mitochondrial ornithine import. In the Galleria mellonella infection model, AmcA-deficiency did not affect virulence of A. fumigatus, most likely due to the residual siderophore production and arginine availability in this host niche.

  13. Chemical and structural characterization of hydroxamate siderophore produced by marine Vibrio harveyi.

    Science.gov (United States)

    Murugappan, R M; Aravinth, A; Karthikeyan, M

    2011-02-01

    In the present study, 22 different bacteria were isolated from open ocean water from the Gulf of Mannar, India. Of the 22 isolates, 4 were identified as Vibrio spp. (VM1, VM2, VM3 and VM4) and found to produce siderophores (iron-binding chelators) under iron-limited conditions. Different media were found to have an influence on siderophore production. Maximum siderophore production was observed with VM1 isolate in MM9 salts medium at 48 h of incubation. The isolate was confirmed as Vibrio harveyi based on 16S rRNA gene sequencing and phylogenetic analysis. Fourier-transform infrared (FTIR) and (1)H nuclear magnetic resonance (NMR) spectra revealed the hydroxamate nature of the siderophore produced. Further characterization of the siderophore revealed it to be of dihydroxamate nature, forming hexadentate ligands with Fe(III) ions. A narrow shift in ultraviolet (UV)-Vis spectrum was observed on photolysis due to ligand oxidation. Growth-promotion bioassay with Aeromonas hydrophila, Staphylococcus aureus and E. coli confirmed the iron-scavenging property of the siderophore produced by Vibrio harveyi.

  14. Benefits of siderophore release lie in mediating diffusion limitation at low iron solubility

    OpenAIRE

    Leventhal, Gabriel; Schiessl, Konstanze; Ackermann, Martin

    2016-01-01

    Siderophores are chelators released by many bacteria to take up iron. In contrast to iron receptors located at the cell surface, released siderophores are at risk of being lost to environmental sinks. Here, we asked the question whether the release itself is essential for the function of siderophores, which could explain why such a risky strategy is widespread. We developed a reaction-diffusion model to determine the impact of siderophore release on overcoming iron limitation caused by poor s...

  15. Pyoverdine, the Major Siderophore in Pseudomonas aeruginosa, Evades NGAL Recognition

    Directory of Open Access Journals (Sweden)

    Mary E. Peek

    2012-01-01

    Full Text Available Pseudomonas aeruginosa is the most common pathogen that persists in the cystic fibrosis lungs. Bacteria such as P. aeruginosa secrete siderophores (iron-chelating molecules and the host limits bacterial growth by producing neutrophil-gelatinase-associated lipocalin (NGAL that specifically scavenges bacterial siderophores, therefore preventing bacteria from establishing infection. P. aeruginosa produces a major siderophore known as pyoverdine, found to be important for bacterial virulence and biofilm development. We report that pyoverdine did not bind to NGAL, as measured by tryptophan fluorescence quenching, while enterobactin bound to NGAL effectively causing a strong response. The experimental data indicate that pyoverdine evades NGAL recognition. We then employed a molecular modeling approach to simulate the binding of pyoverdine to human NGAL using NGAL’s published crystal structures. The docking of pyoverdine to NGAL predicted nine different docking positions; however, neither apo- nor ferric forms of pyoverdine docked into the ligand-binding site in the calyx of NGAL where siderophores are known to bind. The molecular modeling results offer structural support that pyoverdine does not bind to NGAL, confirming the results obtained in the tryptophan quenching assay. The data suggest that pyoverdine is a stealth siderophore that evades NGAL recognition allowing P. aeruginosa to establish chronic infections in CF lungs.

  16. Siderophore-based microbial adaptations to iron scarcity across the eastern Pacific Ocean

    Science.gov (United States)

    Boiteau, Rene M.; Mende, Daniel R.; Hawco, Nicholas J.; McIlvin, Matthew R.; Fitzsimmons, Jessica N.; Saito, Mak A.; Sedwick, Peter N.; DeLong, Edward F.; Repeta, Daniel J.

    2016-12-01

    Nearly all iron dissolved in the ocean is complexed by strong organic ligands of unknown composition. The effect of ligand composition on microbial iron acquisition is poorly understood, but amendment experiments using model ligands show they can facilitate or impede iron uptake depending on their identity. Here we show that siderophores, organic compounds synthesized by microbes to facilitate iron uptake, are a dynamic component of the marine ligand pool in the eastern tropical Pacific Ocean. Siderophore concentrations in iron-deficient waters averaged 9 pM, up to fivefold higher than in iron-rich coastal and nutrient-depleted oligotrophic waters, and were dominated by amphibactins, amphiphilic siderophores with cell membrane affinity. Phylogenetic analysis of amphibactin biosynthetic genes suggests that the ability to produce amphibactins has transferred horizontally across multiple Gammaproteobacteria, potentially driven by pressures to compete for iron. In coastal and oligotrophic regions of the eastern Pacific Ocean, amphibactins were replaced with lower concentrations (1-2 pM) of hydrophilic ferrioxamine siderophores. Our results suggest that organic ligand composition changes across the surface ocean in response to environmental pressures. Hydrophilic siderophores are predominantly found across regions of the ocean where iron is not expected to be the limiting nutrient for the microbial community at large. However, in regions with intense competition for iron, some microbes optimize iron acquisition by producing siderophores that minimize diffusive losses to the environment. These siderophores affect iron bioavailability and thus may be an important component of the marine iron cycle.

  17. Synthesis of siderophores by strains of Staphylococcus cohnii isolated from various environments.

    Science.gov (United States)

    Szarapińska-Kwaszewska, Jadwiga; Farkas, Lukasz I

    2003-01-01

    Siderophore activity as the feature of microorganisms enabling colonization of human body and the survival in inanimate environment was investigated in 108 strains of Staphylococcus cohnii; S. cohnii ssp. cohnii (50 strains) and S. cohnii ssp. urealyticus (58 strains). Strains were isolated from people, hospital and non-hospital environment. Highest siderophore activity was noted in strains S. cohnii ssp. urealyticus particularly from the inanimate environments origin. In 86% analyzed strains siderophores of hydroxamate class were detected. Larger amounts of these compounds were synthesized in strains S. cohnii ssp. urealyticus. Strains belonging to both subspecies from human origin showed lower activity of siderophores (total pool) and did not produce hydroxamate class chelators or produced very small amounts of these compounds.

  18. The role of fluorescent pseudo monad's siderophore on Zn absorption in wheat by using 65Zn

    International Nuclear Information System (INIS)

    Rasouli Sadaghiani, M. H.; Malakouti, M. J.; Khavazi, K.; Ghannadi Maragheh, M.

    2008-01-01

    The objective of this investigation was to determine the potentials of some indigenous fluorescent Pseudomonads for siderophore production and their effects on 65Z n absorption in 2005. For this purpose, 201 strains of Pseudomonas putida, P. fluorescence, and P. aeruginosa were isolated from different locations representing rhizosphere of wheat (Triticum aestivum L.). The potentials of these strains for siderophore production were evaluated by chrome azo rel-S assay (CAS blue agar) through color change. High siderophore producing super-strains were selected for the extraction of siderophores. These isolates were grown in standard succinate medium for 72 hours at 28 d eg C . The bacterial cells were removed by centrifugation (10000 g for 20 minutes) and the supernatant was filtered through filter membrane (0.22 μ) and used as the source of siderophore source. The evaluations of Zn uptake and translocation were carried out with the complexes of bacterial siderophores and 65Z n compared with the standard siderophore Desferrioxamine in a randomized complete block design with three replications. This experiment was conducted on two wheat genotypes different in Zn-efficiency under hydroponic condition. The results revealed that among the three most effective siderophores producing strains considered, the P. putida produced a siderophore complex that showed efficiencies of 83% compared with the standard siderophore (DFOB) in the uptake of Zn and was statistically in the same group as the control. The effect of bacterial siderophores in the uptake of labeled 65Z n by wheat was significant, indicating that the chemical structures of the siderophores from different strains were different. The effects of wheat variety on 65Z n translocation to shoots was also significant, where the efficient Tabasi variety contained 46% more Zn in shoots than the inefficient Yavarous variety. It was concluded that the siderophore complex from P. putida was the most effective in translocation

  19. Metachelins, mannosylated and N-oxidized coprogen-type siderophores from Metarhizium robertsii

    Science.gov (United States)

    Under iron-depleted culture conditions, the entomopathogenic fungus Metarhizium robertsii (Bischoff, Humber, and Rehner) (= M. anisopliae) produces a complex of extracellular siderophores including novel O-glycosylated and/or N-oxidized coprogen-type compounds as well as the known fungal siderophore...

  20. Characterization of iron uptake from hydroxamate siderophores by Chlorella vulgaris

    International Nuclear Information System (INIS)

    Allnutt, F.C.T.

    1985-01-01

    Iron uptake by Chlorella vulgaris from ferric-hydroxamate siderophores and the possible production of siderophores by these algae was investigated. No production of siderophores or organic acids was observed. Iron from the two hydroxamate siderophores tested, ferrioximine B (Fe 3+ -DFOB) and ferric-rhodotorulate (Fe 3+ -RA), was taken up at the same rate as iron chelated by citrate or caffeate. Two synthetic chelates, Fe 3+ -EDTA and Fe 3+ -EDDHA, provided iron at a slower rate. Iron uptake was inhibited by 50 μM CCCP or 1 mM vanadate. Cyanide (100 μM KCN) or 25 μM antimycin A failed to demonstrate a link between uptake and respiration. Labeled iron ( 55 Fe) was taken up while labeled ligands ([ 14 C] citrate or RA) were not accumulated. Cation competition from Ni 2+ and Co 2+ observed using Fe 3+ -DFOB and Fe 3+ -RA while iron uptake from Fe 3+ -citrate was stimulated. Iron-stress induced iron uptake from the hydroxamate siderophores. Ferric reduction from the ferric-siderophores was investigated with electron paramagnetic resonance (EPR) and bathophenathroline disulfonate (BPDS). Ferric reduction was induced by iron-stress and inhibited by CCCP. A close correlation between iron uptake and ferric reduction was measured by the EPR method. Ferric reduction measured by the BPDS method was greater than that measure by EPR. BPDS reduction was interpreted to indicate a potential for reduction while EPR measures the physiological rate of reduction. BPDS inhibition of iron uptake and ferricyanide interference with reduction indicate that reduction and uptake occur exposed to the external medium. Presumptive evidence using a binding dose response curve for Fe 3+ -DFOB indicated that a receptor may be involved in this mechanism

  1. An enantiomerically pure siderophore type ligand for the diastereoselective 1 : 1 complexation of lanthanide(III ions

    Directory of Open Access Journals (Sweden)

    Markus Albrecht

    2009-12-01

    Full Text Available A facile synthesis of a highly preorganized tripodal enterobactine-type ligand 1a-H3 consisting of a chiral C3-symmetric macrocyclic peptide and three tridentate 2-amido-8-hydroxyquinoline coordinating units is presented. Complex formation with various metal ions (Al3+, Ga3+, Fe3+, La3+ and Eu3+ was investigated by spectrophotometric methods. Only in the case of La3+ and Eu3+ were well defined 1 : 1 complexes formed. On the basis of CD spectroscopy and DFT calculations the configuration at the metal centre of the La3+ complex was determined to show Λ helicity. The coordination compounds [(1aLn] presented should be prototypes for further lanthanide(III complexes with an enterobactine analogue binding situation.

  2. Siderophore production by mycorrhizal sorghum roots under micronutrient deficient condition

    Directory of Open Access Journals (Sweden)

    N. Aliasgharzad

    2009-05-01

    Full Text Available It has widely been accepted that mycorrhizal symbiosis improves micronutrients uptake by most of the plants. In this study, sorghum (Sorghum bicolor L. plants were grown in sterile perlite and were inoculated with either Glomus etunicatum (GE or G.intraradices (GI, while the control set was left un-inoculated. Rorison's nutrient solution with three levels of 0, half and full strength (C0, C0.5 and C1, respectively of Fe, Cu, Zn and Mn was applied to the pots during 85 days of growth period. Chrome azurol-S assay was used for determination of siderophores in root leachates on 45, 65 and 85 days after sowing (DAS. Siderophore production per unit volume of root was higher in mycorrhizal than non-mycorrhizal plants. Both GE and GI were efficient fungi in this respect. Siderophore production was significantly induced at C0 level of the micronutrients. Amount of siderophores produced on 45 and 85 DAS was more than 65 DAS. Mycorrhizal root colonization by GE or GI was not significantly affected by micronutrient levels.

  3. Enantiomerization and enantioselective bioaccumulation of metalaxyl in Tenebrio molitor larvae.

    Science.gov (United States)

    Gao, Yongxin; Wang, Huili; Qin, Fang; Xu, Peng; Lv, Xiaotian; Li, Jianzhong; Guo, Baoyuan

    2014-02-01

    The enantiomerization and enantioselective bioaccumulation of metalaxyl by a single dose of exposure to Tenebrio molitor larvae under laboratory condition were studied by high-performance liquid chromatography tandem mass spectroscopy (HPLC-MS/MS) based on a ChiralcelOD-3R [cellulosetris-tris-(3, 5-dichlorophenyl-carbamate)] column. Exposure of enantiopure R-metalaxyl and S-metalaxyl in Tenebrio molitor larvae exhibited significant enantiomerization, with formation of the R enantiomers from the S enantiomers, and vice versa, which might be attributed to the chiral pesticide catalyzed by a certain enzyme in Tenebrio molitor larvae. Enantiomerization was not observed in wheat bran during the period of 21 d. In addition, bioaccumulation of rac-metalaxyl in Tenebrio molitor larvae was enantioselective with a preferential accumulation of S-metalaxyl. These results showed that enantioselectivity was caused not only by actual degradation and metabolism but also by enantiomerization, which was an important process in the environmental fate and behavior of metalaxyl enantiomers. Copyright © 2013 Wiley Periodicals, Inc.

  4. Mixing and matching siderophore clusters: structure and biosynthesis of serratiochelins from Serratia sp. V4.

    Science.gov (United States)

    Seyedsayamdost, Mohammad R; Cleto, Sara; Carr, Gavin; Vlamakis, Hera; João Vieira, Maria; Kolter, Roberto; Clardy, Jon

    2012-08-22

    Interrogation of the evolutionary history underlying the remarkable structures and biological activities of natural products has been complicated by not knowing the functions they have evolved to fulfill. Siderophores-soluble, low molecular weight compounds-have an easily understood and measured function: acquiring iron from the environment. Bacteria engage in a fierce competition to acquire iron, which rewards the production of siderophores that bind iron tightly and cannot be used or pirated by competitors. The structures and biosyntheses of "odd" siderophores can reveal the evolutionary strategy that led to their creation. We report a new Serratia strain that produces serratiochelin and an analog of serratiochelin. A genetic approach located the serratiochelin gene cluster, and targeted mutations in several genes implicated in serratiochelin biosynthesis were generated. Bioinformatic analyses and mutagenesis results demonstrate that genes from two well-known siderophore clusters, the Escherichia coli enterobactin cluster and the Vibrio cholera vibriobactin cluster, were shuffled to produce a new siderophore biosynthetic pathway. These results highlight how modular siderophore gene clusters can be mixed and matched during evolution to generate structural diversity in siderophores.

  5. A new approach to isolating siderophore-producing actinobacteria.

    Science.gov (United States)

    Nakouti, I; Sihanonth, P; Hobbs, G

    2012-07-01

    This study was conducted to investigate the application of 2,2'-dipyridyl as a new approach to isolating siderophore-producing actinobacteria. Isolation of actinobacteria from soil was conducted by a soil dilution plate technique using starch-casein agar. Iron starvation was fostered by the incorporation of the iron chelator 2,2'-dipyridyl in the isolation medium. Pretreatment of the samples at an elevated temperature (40°C) ensured that the majority of nonsporulating bacteria were excluded. The survivors of this treatment were largely actinobacteria. Of the viable cultures grown in the presence of 2,2'-dipyridyl, more than 78-88% (average of three separate studies) were reported to produce siderophore-like compounds compared to 13-18% (average of three separate studies) when grown on the basic media in the absence of the chelating agent. The most prolific producers as assessed by the chrome azurol sulphate (CAS) assay were further characterized and found to belong to the genus Streptomyces. Selective pressure using 2,2'-dipyridyl as an iron-chelating agent in starch-casein media increased the isolation of siderophore-producing actinobacteria compared to the unamended medium. The study described represents a new approach to the isolation of siderophore-producing actinobacteria using a novel procedure that places a selection on cell population based upon the incorporation of a chelating agent in the medium. © 2012 The Authors. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.

  6. Sideróforos: uma resposta dos microorganismos Siderophores: a microorganism's answer

    Directory of Open Access Journals (Sweden)

    Anna Maria Canavarro Benite

    2002-12-01

    Full Text Available Siderophores (from the Greek: "iron carriers" are defined as relatively low molecular weight, ferric ion specific chelating agents elaborated by microorganisms growing under low iron stress. The role of these compounds is to scavenge iron from the environment and to make this essential chemical element available to the microbial cell. The present paper is a brief presentation of siderophore coordination chemistry with emphasis on those aspects relevant to the transportation of iron (III complexes across biological membranes. Finally, the role of siderophores in infection and their clinical potential as iron scavenging molecules are reviewed.

  7. Genome mining and functional genomics for siderophore production in Aspergillus niger.

    Science.gov (United States)

    Franken, Angelique C W; Lechner, Beatrix E; Werner, Ernst R; Haas, Hubertus; Lokman, B Christien; Ram, Arthur F J; van den Hondel, Cees A M J J; de Weert, Sandra; Punt, Peter J

    2014-11-01

    Iron is an essential metal for many organisms, but the biologically relevant form of iron is scarce because of rapid oxidation resulting in low solubility. Simultaneously, excessive accumulation of iron is toxic. Consequently, iron uptake is a highly controlled process. In most fungal species, siderophores play a central role in iron handling. Siderophores are small iron-specific chelators that can be secreted to scavenge environmental iron or bind intracellular iron with high affinity. A second high-affinity iron uptake mechanism is reductive iron assimilation (RIA). As shown in Aspergillus fumigatus and Aspergillus nidulans, synthesis of siderophores in Aspergilli is predominantly under control of the transcription factors SreA and HapX, which are connected by a negative transcriptional feedback loop. Abolishing this fine-tuned regulation corroborates iron homeostasis, including heme biosynthesis, which could be biotechnologically of interest, e.g. the heterologous production of heme-dependent peroxidases. Aspergillus niger genome inspection identified orthologues of several genes relevant for RIA and siderophore metabolism, as well as sreA and hapX. Interestingly, genes related to synthesis of the common fungal extracellular siderophore triacetylfusarinine C were absent. Reverse-phase high-performance liquid chromatography (HPLC) confirmed the absence of triacetylfusarinine C, and demonstrated that the major secreted siderophores of A. niger are coprogen B and ferrichrome, which is also the dominant intracellular siderophore. In A. niger wild type grown under iron-replete conditions, the expression of genes involved in coprogen biosynthesis and RIA was low in the exponential growth phase but significantly induced during ascospore germination. Deletion of sreA in A. niger resulted in elevated iron uptake and increased cellular ferrichrome accumulation. Increased sensitivity toward phleomycin and high iron concentration reflected the toxic effects of excessive

  8. The influence of substrate on siderophore production by fish spoilage bacteria

    DEFF Research Database (Denmark)

    Gram, Lone

    1996-01-01

    Pseudomonas isolate produced siderophores in all four media whereas the other isolates varied. One isolate was negative in all media except for the M9GC that supported siderophore production for all five Pseudomonas isolates. Neither the hydroxamate nor catechol reaction was found for any of the Pseudomonas...

  9. Bacterial siderophores efficiently provide iron to iron-starved tomato plants in hydroponics culture.

    Science.gov (United States)

    Radzki, W; Gutierrez Mañero, F J; Algar, E; Lucas García, J A; García-Villaraco, A; Ramos Solano, B

    2013-09-01

    Iron is one of the essential elements for a proper plant development. Providing plants with an accessible form of iron is crucial when it is scant or unavailable in soils. Chemical chelates are the only current alternative and are highly stable in soils, therefore, posing a threat to drinking water. The aim of this investigation was to quantify siderophores produced by two bacterial strains and to determine if these bacterial siderophores would palliate chlorotic symptoms of iron-starved tomato plants. For this purpose, siderophore production in MM9 medium by two selected bacterial strains was quantified, and the best was used for biological assay. Bacterial culture media free of bacteria (S) and with bacterial cells (BS), both supplemented with Fe were delivered to 12-week-old plants grown under iron starvation in hydroponic conditions; controls with full Hoagland solution, iron-free Hoagland solution and water were also conducted. Treatments were applied twice along the experiment, with a week in between. At harvest, plant yield, chlorophyll content and nutritional status in leaves were measured. Both the bacterial siderophore treatments significantly increased plant yield, chlorophyll and iron content over the positive controls with full Hoagland solution, indicating that siderophores are effective in providing Fe to the plant, either with or without the presence of bacteria. In summary, siderophores from strain Chryseobacterium C138 are effective in supplying Fe to iron-starved tomato plants by the roots, either with or without the presence of bacteria. Based on the amount of siderophores produced, an effective and economically feasible organic Fe chelator could be developed.

  10. Siderophore-mediated iron trafficking in humans is regulated by iron

    Science.gov (United States)

    Liu, Zhuoming; Lanford, Robert; Mueller, Sebastian; Gerhard, Glenn S.; Luscieti, Sara; Sanchez, Mayka; Devireddy, L.

    2013-01-01

    Siderophores are best known as small iron binding molecules that facilitate microbial iron transport. In our previous study we identified a siderophore-like molecule in mammalian cells and found that its biogenesis is evolutionarily conserved. A member of the short chain dehydrogenase family of reductases, 3-OH butyrate dehydrogenase (BDH2) catalyzes a rate-limiting step in the biogenesis of the mammalian siderophore. We have shown that depletion of the mammalian siderophore by inhibiting expression of bdh2 results in abnormal accumulation of cellular iron and mitochondrial iron deficiency. These observations suggest that the mammalian siderophore is a critical regulator of cellular iron homeostasis and facilitates mitochondrial iron import. By utilizing bioinformatics, we identified an iron-responsive element (IRE; a stem-loop structure that regulates genes expression post-transcriptionally upon binding to iron regulatory proteins or IRPs) in the 3′-untranslated region (3′-UTR) of the human BDH2 (hBDH2) gene. In cultured cells as well as in patient samples we now demonstrate that the IRE confers iron-dependent regulation on hBDH2 and binds IRPs in RNA electrophoretic mobility shift assays. In addition, we show that the hBDH2 IRE associates with IRPs in cells and that abrogation of IRPs by RNAi eliminates the iron-dependent regulation of hBDH2 mRNA. The key physiologic implication is that iron-mediated post-transcriptional regulation of hBDH2 controls mitochondrial iron homeostasis in human cells. These observations provide a new and an unanticipated mechanism by which iron regulates its intracellular trafficking. PMID:22527885

  11. Overcoming antibiotic resistance: Is siderophore Trojan horse conjugation an answer to evolving resistance in microbial pathogens?

    Science.gov (United States)

    Dhusia, Kalyani; Bajpai, Archana; Ramteke, P W

    2018-01-10

    Comparative study of siderophore biosynthesis pathway in pathogens provides potential targets for antibiotics and host drug delivery as a part of computationally feasible microbial therapy. Iron acquisition using siderophore models is an essential and well established model in all microorganisms and microbial infections a known to cause great havoc to both plant and animal. Rapid development of antibiotic resistance in bacterial as well as fungal pathogens has drawn us at a verge where one has to get rid of the traditional way of obstructing pathogen using single or multiple antibiotic/chemical inhibitors or drugs. 'Trojan horse' strategy is an answer to this imperative call where antibiotic are by far sneaked into the pathogenic cell via the siderophore receptors at cell and outer membrane. This antibiotic once gets inside, generates a 'black hole' scenario within the opportunistic pathogens via iron scarcity. For pathogens whose siderophore are not compatible to smuggle drug due to their complex conformation and stiff valence bonds, there is another approach. By means of the siderophore biosynthesis pathways, potential targets for inhibition of these siderophores in pathogenic bacteria could be achieved and thus control pathogenic virulence. Method to design artificial exogenous siderophores for pathogens that would compete and succeed the battle of intake is also covered with this review. These manipulated siderophore would enter pathogenic cell like any other siderophore but will not disperse iron due to which iron inadequacy and hence pathogens control be accomplished. The aim of this review is to offer strategies to overcome the microbial infections/pathogens using siderophore. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Towards high-siderophore-content foods: optimisation of coprogen production in submerged cultures of Penicillium nalgiovense.

    Science.gov (United States)

    Emri, Tamás; Tóth, Viktória; Nagy, Csilla Terézia; Nagy, Gábor; Pócsi, Imre; Gyémánt, Gyöngyi; Antal, Károly; Balla, József; Balla, György; Román, Gyula; Kovács, István; Pócsi, István

    2013-07-01

    Fungal siderophores are likely to possess atheroprotective effects in humans, and therefore studies are needed to develop siderophore-rich food additives or functional foods to increase the siderophore uptake in people prone to cardiovascular diseases. In this study the siderophore contents of mould-ripened cheeses and meat products were analysed and the coprogen production by Penicillium nalgiovense was characterised. High concentrations of hexadentate fungal siderophores were detected in penicillia-ripened Camembert- and Roquefort-type cheeses and also in some sausages. In one sausage fermented by P. nalgiovense, the siderophore content was comparable to those found in cheeses. Penicillium nalgiovense produced high concentrations of coprogen in submerged cultures, which were affected predominantly by the available carbon and nitrogen sources under iron starvation. Considerable coprogen yields were still detectable in the presence of iron when the fermentation medium was supplemented with the iron chelator Na₂-EDTA or when P. nalgiovense was co-cultivated with Saccharomyces cerevisiae. These data may be exploitable in the future development of high-siderophore-content foods and/or food additives. Nevertheless, the use of P. nalgiovense fermentation broths for these purposes may be limited by the instability of coprogen in fermentation media and by the β-lactam production by the fungus. © 2012 Society of Chemical Industry.

  13. Transposon-mediated random gene disruption with moderate halophilic bacteria and its application for halophilic bacterial siderophore analysis.

    Science.gov (United States)

    Matsui, Toru; Nishino, Tomohiko

    2016-12-01

    Analytical conditions using chromo azurol S was validated for quantification of siderophore in aqueous samples, followed by the characterization of siderophore derived from newly isolated moderately halophilic bacteria. Conditions with good linearity between the absorbance and the siderophore concentration were obtained at a siderophore concentration less than 20 µM, in the wavelength range between 630 and 660 nm with developing time for at least 2 h. Of the halophilic bacteria isolated from Tunisian soil, Halomonas sp., namely strain 21a was selected as siderophore producing halophiles. The strain produced siderophore significantly in the absence of iron in minimal medium. Siderophore-deficient mutant, namely IIa10, of the strain 21a was obtained from gene disruptant library constructed using transposon complex by electroporation. Genomic sequence analysis of the mutant IIa10 revealed that the transposon-inserted gene was TonB-dependent receptor. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Enantiomerization and enantioselective bioaccumulation of benalaxyl in Tenebrio molitor larvae from wheat bran.

    Science.gov (United States)

    Gao, Yongxin; Chen, Jinhui; Wang, Huili; Liu, Chen; Lv, Xiaotian; Li, Jianzhong; Guo, Baoyuan

    2013-09-25

    The enantiomerization and enatioselecive bioaccumulation of benalaxyl by dietary exposure to Tenebrio molitor larvae under laboratory conditions were studied by HPLC-MS/MS. Exposure of enantiopure R-benalaxyl and S-benalaxyl in T. molitor larvae revealed significant enantiomerization with formation of the R enantiomers from the S enantiomers, and vice versa. Enantiomerization was not observed in wheat bran during the period of 21 days. For the bioaccumulation experiment, the enantiomer fraction in T. molitor larvae was maintained approximately at 0.6, whereas the enantiomer fraction in wheat bran was maintained at 0.5; in other words, the bioaccumulation of benalaxyl was enantioselective in T. molitor larvae. Mathematical models for a process of uptake, degradation, and enantiomerization were developed, and the rates of uptake, degradation, and enantiomerization of R-benealaxyl and S-benealaxyl were estimated, respectively. The results were that the rate of uptake of R-benalaxyl (kRa = 0.052 h(-1)) was slightly lower than that of S-benalaxyl (kSa = 0.061 h(-1)) from wheat bran; the rate of degradation of R-benalaxyl (kRd = 0.285 h(-1)) was higher than that of S-benalaxyl (kSd = 0.114 h(-1)); and the rate of enantiomerization of R-benalaxyl (kRS = 0.126 h(-1)) was higher than that of S-benalaxyl (kSR = 0.116 h(-1)). It was suggested that enantioselectivtiy was caused not only by actual degradation and metabolism but also by enantiomerization, which was an important process in the environmental fate and behavior of chiral pesticides.

  15. Synthesis, enantiomeric resolution, F-18 labeling and biodistribution of reboxetine analogs: promising radioligands for imaging the norepinephrine transporter with positron emission tomography.

    Science.gov (United States)

    Lin, Kuo-Shyan; Ding, Yu-Shin; Kim, Sung-Won; Kil, Kun-Eek

    2005-05-01

    Racemic and enantiomerically pure ((S,S) and (R,R)) 2-[alpha-(2-(2-[(18)F]fluoroethoxy)phenoxy)benzyl]morpholine ([(18)F]FRB) and its tetradeuterated form [(18)F]FRB-D(4), analogs of the highly selective norepinephrine reuptake inhibitor reboxetine (2-[alpha-(2-ethoxyphenoxy)benzyl]morpholine, RB), have been synthesized for studies of norepinephrine transporter (NET) system with positron emission tomography (PET). The [(18)F]fluorinated precursor, (S,S)/(R,R)-N-tert-butyloxycarbonyl-2-[alpha-(2-hydroxyphenoxy)benzyl]morpholine ((S,S)/(R,R)-N-Boc-desethylRB), was prepared by the N-protection of (S,S)/(R,R)-2-[alpha-(2-hydroxyphenoxy)benzyl]morpholine ((S,S)/(R,R)-desethylRB) with a tert-butyloxycarbonyl (Boc) group followed by enantiomeric resolution with chiral HPLC to provide both (S,S) and (R,R) enantiomers with >99% enantiomeric purity. These compounds were then used for radiosynthesis to prepare enantiomerically pure [(18)F]FRB and [(18)F]FRB-D(4) via the following three-step procedure: (1) formation of 1-bromo-2-[(18)F]fluoroethane ([(18)F]BFE or [(18)F]BFE-D(4)) by nucleophilic displacement of 2-bromoethyl triflate (or D(4) analog) with no-carrier added [(18)F]F(-) in THF; (2) reaction of [(18)F]BFE (or [(18)F]BFE-D(4)) with N-Boc-desethylRB in DMF in the presence of excess base; and (3) deprotection with trifluoroacetic acid. The racemates, (S,S) and (R,R) enantiomers of [(18)F]FRB and [(18)F]FRB-D(4) were obtained in 11-27% (decay corrected to the end of bombardment, EOB) in 120-min synthesis time with a radiochemical purity of >98% and specific activities of 21-48 GBq/micromol (EOB). The results of the whole-body biodistribution studies with (S,S)-[(18)F]FRB-D(4) were similar to those with (S,S)-[(18)F]FRB but showed relatively faster blood clearance and no significant in vivo defluorination. Positron emission tomography studies in baboon brain also showed that (S,S)-[(18)F]FRB-D(4) may be a potentially useful ligand for imaging NET with PET.

  16. Synthesis, enantiomeric resolution, F-18 labeling and biodistribution of reboxetine analogs: promising radioligands for imaging the norepinephrine transporter with positron emission tomography

    International Nuclear Information System (INIS)

    Lin, K.-S.; Ding, Y.-S.; Kim, Sung-Won; Kil, Kun-Eek

    2005-01-01

    Racemic and enantiomerically pure ((S,S) and (R,R)) 2-[α-(2-(2-[ 18 F]fluoroethoxy)phenoxy)benzyl]morpholine ([ 18 F]FRB) and its tetradeuterated form [ 18 F]FRB-D 4 , analogs of the highly selective norepinephrine reuptake inhibitor reboxetine (2-[α-(2-ethoxyphenoxy)benzyl]morpholine, RB), have been synthesized for studies of norepinephrine transporter (NET) system with positron emission tomography (PET). The [ 18 F]fluorinated precursor, (S,S)/(R,R)-N-tert-butyloxycarbonyl-2-[α-(2-hydroxyphenoxy)benzyl] morpholine ((S,S)/(R,R)-N-Boc-desethylRB), was prepared by the N-protection of (S,S)/(R,R)-2-[α-(2-hydroxyphenoxy)benzyl]morpholine ((S,S)/(R,R)-desethylRB) with a tert-butyloxycarbonyl (Boc) group followed by enantiomeric resolution with chiral HPLC to provide both (S,S) and (R,R) enantiomers with >99% enantiomeric purity. These compounds were then used for radiosynthesis to prepare enantiomerically pure [ 18 F]FRB and [ 18 F]FRB-D 4 via the following three-step procedure: (1) formation of 1-bromo-2-[ 18 F]fluoroethane ([ 18 F]BFE or [ 18 F]BFE-D 4 ) by nucleophilic displacement of 2-bromoethyl triflate (or D 4 analog) with no-carrier added [ 18 F]F - in THF; (2) reaction of [ 18 F]BFE (or [ 18 F]BFE-D 4 ) with N-Boc-desethylRB in DMF in the presence of excess base; and (3) deprotection with trifluoroacetic acid. The racemates, (S,S) and (R,R) enantiomers of [ 18 F]FRB and [ 18 F]FRB-D 4 were obtained in 11-27% (decay corrected to the end of bombardment, EOB) in 120-min synthesis time with a radiochemical purity of >98% and specific activities of 21-48 GBq/μmol (EOB). The results of the whole-body biodistribution studies with (S,S)-[ 18 F]FRB-D 4 were similar to those with (S,S)-[ 18 F]FRB but showed relatively faster blood clearance and no significant in vivo defluorination. Positron emission tomography studies in baboon brain also showed that (S,S)-[ 18 F]FRB-D 4 may be a potentially useful ligand for imaging NET with PET

  17. Siderophores: The special ingredient to cyanobacterial blooms

    Science.gov (United States)

    Du, Xue; Creed, Irena; Trick, Charles

    2013-04-01

    Freshwater lakes provide a number of significant ecological services including clean drinking water, habitat for aquatic biota, and economic benefits. The provision of these ecological services, as well as the health of these aquatic systems, is threatened by the excessive growth of algae, specifically, cyanobacteria. Historically, blooms have been linked to eutrophication but recent occurrences indicate that there are less dramatic changes that induce these blooms. Iron is an essential micronutrient required for specific essential metabolic pathways; however, the amount of biologically available iron in naturally occurring lake ranges from saturation to much lower than cell transport affinities. To assist in the modulation of iron availabilities, cyanobacteria in culture produce low molecular weight compounds that function in an iron binding and acquisition system; nevertheless, this has yet to be confirmed in naturally occurring lakes. This project explored the relationship of P, N and in particular, Fe, in the promotion of cyanobacteria harmful algal blooms in 30 natural freshwater lakes located in and around the Elk Island National Park, Alberta. It is hypothesized that cyanobacteria produce and utilize iron chelators called siderophores in low Fe and nitrogen (N) conditions, creating a competitive advantage over other algae in freshwater lakes. Lakes were selected to represent a range of iron availability to explore the nutrient composition of lakes that propagated cyanobacteria harmful algal blooms (cHABs) compared to lakes that did not. Lake water was analyzed for nutrients, microbial composition, siderophore concentration, and toxin concentration. Modifications were made to optimize the Czaky and Arnow tests for hydroxamate- and catecholate-type siderophores, respectively, for field conditions. Preliminary results indicate the presence of iron-binding ligands (0.11-2.34 mg/L) in freshwater lakes characterized by widely ranging Fe regimes (0.04-2.74 mg

  18. Synthesis of enantiomerically pure thiocrown ethers derived from 1,1'-binaphthalene-2,2'-diol

    NARCIS (Netherlands)

    Stock, H. Thijs; Kellogg, Richard M.

    1996-01-01

    Synthetic methodology is given for the preparation of two different types of thiocrown ethers from optically pure 1,1'-binaphthalene-2,2'-diol (10). The conceptually simplest approach starts from optically pure 10 itself, which is alkylated (4 equiv of K2CO3 in DMF at 110 degrees C) with

  19. Hunger for iron: the alternative siderophore iron scavenging systems in highly virulent Yersinia.

    Directory of Open Access Journals (Sweden)

    Alexander eRakin

    2012-11-01

    Full Text Available Low molecular weight siderophores are used by many living organisms to scavenge scarcely available ferric iron. Presence of at least a single siderophore-based iron acquisition system is usually acknowledged as a virulence-associated trait and a prerequisite to become an efficient and successful pathogen. Currently it is assumed that yersiniabactin (Ybt is the solely functional endogenous siderophore iron uptake system in highly virulent Yersinia (Yersinia pestis, Y. pseudotuberculosis and Y. enterocolitica biotype 1B. Genes responsible for biosynthesis, transport and regulation of the yersiniabactin (ybt production are clustered on a mobile genetic element, the High Pathogenicity Island (HPI that is responsible for broad dissemination of the ybt genes in Enterobacteriaceae. However, the ybt gene cluster is absent from nearly half of Y. pseudotuberculosis O3 isolates and epidemic Y. pseudotuberculosis O1 isolates responsible for the Far East Scarlet-like Fever. Several potential siderophore-mediated iron uptake gene clusters are documented in Yersinia genomes, however neither of them have been proven to be functional. It has been suggested that at least two siderophores alternative to Ybt may operate in the highly virulent Yersinia pestis / Y. pseudotuberculosis group, and are referred to as pseudochelin (Pch and yersiniachelin (Ych. Furthermore, most sporadic Y. pseudotuberculosis O1 strains possess gene clusters encoding all three iron scavenging systems. Thus, the Ybt system appears not to be the sole endogenous siderophore iron uptake system in the highly virulent yersiniae and may be efficiently substituted and / or supplemented by alternative iron scavenging systems.

  20. Siderophores mediate reduced and increased uptake of cadmium by Streptomyces tendae F4 and sunflower (Helianthus annuus), respectively.

    Science.gov (United States)

    Dimkpa, C O; Merten, D; Svatos, A; Büchel, G; Kothe, E

    2009-11-01

    As a toxic metal, cadmium (Cd) affects microbial and plant metabolic processes, thereby potentially reducing the efficiency of microbe or plant-mediated remediation of Cd-polluted soil. The role of siderophores produced by Streptomyces tendae F4 in the uptake of Cd by bacteria and plant was investigated to gain insight into the influence of siderophores on Cd availability to micro-organisms and plants. The bacterium was cultured under siderophore-inducing conditions in the presence of Cd. The kinetics of siderophore production and identification of the siderophores and their metal-bound forms were performed using electrospray ionization mass spectrometry. Inductively coupled plasma spectroscopy was used to measure iron (Fe) and Cd contents in the bacterium and in sunflower plant grown in Cd-amended soil. Siderophores significantly reduced the Cd uptake by the bacterium, while supplying it with iron. Bacterial culture filtrates containing three hydroxamate siderophores secreted by S. tendae F4 significantly promoted plant growth and enhanced uptake of Cd and Fe by the plant, relative to the control. Furthermore, application of siderophores caused slightly more Cd, but similar Fe uptake, compared with EDTA. Bioinoculation with Streptomyces caused a dramatic increase in plant Fe content, but resulted only in slight increase in plant Cd content. It is concluded that siderophores can help reduce toxic metal uptake in bacteria, while simultaneously facilitating the uptake of such metals by plants. Also, EDTA is not superior to hydroxamate siderophores in terms of metal solubilization for plant uptake. The study showed that microbial processes could indirectly influence the availability and amount of toxic metals taken up from the rhizosphere of plants. Furthermore, although EDTA is used for chelator-enhanced phytoremediation, microbial siderophores would be ideal for this purpose.

  1. Analysis of enantiomeric and non-enantiomeric monoterpenes in plant emissions using portable dynamic air sampling/solid-phase microextraction (PDAS-SPME) and chiral gas chromatography/mass spectrometry

    Science.gov (United States)

    Yassaa, Noureddine; Williams, Jonathan

    A portable dynamic air sampler (PDAS) using a porous polymer solid-phase microextraction (SPME) fibre has been validated for the determination of biogenic enantiomeric and non-enantiomeric monoterpenes in air. These compounds were adsorbed in the field, and then thermally desorbed at 250 °C in a gas chromatograph injector port connected via a β-cyclodextrin capillary separating column to a mass spectrometer. The optimized method has been applied for investigating the emissions of enantiomeric monoterpenes from Pseudotsuga menziesii (Douglas-fir), Rosmarinus officinalis (Rosemary) and Lavandula lanata (Lavender) which were selected as representative of coniferous trees and aromatic plants, respectively. The enantiomers of α-pinene, sabinene, camphene, δ-3-carene, β-pinene, limonene, β-phellandrene, 4-carene and camphor were successfully determined in the emissions from the three plants. While Douglas-fir showed a strong predominance toward (-)-enantiomers, Rosemary and Lavender demonstrated a large variation in enantiomeric distribution of monoterpenes. The simplicity, rapidity and sensitivity of dynamic sampling with porous polymer coated SPME fibres coupled to chiral capillary gas chromatography/mass spectrometry (GC/MS) makes this method potentially useful for in-field investigations of atmosphere-biosphere interactions and studies of optically explicit atmospheric chemistry.

  2. Interspecies modulation of bacterial development through iron competition and siderophore piracy.

    Science.gov (United States)

    Traxler, Matthew F; Seyedsayamdost, Mohammad R; Clardy, Jon; Kolter, Roberto

    2012-11-01

    While soil-dwelling actinomycetes are renowned for secreting natural products, little is known about the roles of these molecules in mediating actinomycete interactions. In a previous co-culture screen, we found that one actinomycete, Amycolatopsis sp. AA4, inhibited aerial hyphae formation in adjacent colonies of Streptomyces coelicolor. A siderophore, amychelin, mediated this developmental arrest. Here we present genetic evidence that confirms the role of the amc locus in the production of amychelin and in the inhibition of S. coelicolor development. We further characterize the Amycolatopsis sp. AA4 - S. coelicolor interaction by examining expression of developmental and iron acquisition genes over time in co-culture. Manipulation of iron availability and/or growth near Amycolatopsis sp. AA4 led to alterations in expression of the critical developmental gene bldN, and other key downstream genes in the S. coelicolor transcriptional cascade. In Amycolatopsis sp. AA4, siderophore genes were downregulated when grown near S. coelicolor, leading us to find that deferrioxamine E, produced by S. coelicolor, could be readily utilized by Amycolatopsis sp. AA4. Collectively these results suggest that competition for iron via siderophore piracy and species-specific siderophores can alter patterns of gene expression and morphological differentiation during actinomycete interactions. © 2012 Blackwell Publishing Ltd.

  3. Magnitude and Mechanism of Siderophore-Mediated Competition at Low Iron Solubility in the Pseudomonas aeruginosa Pyochelin System

    Directory of Open Access Journals (Sweden)

    Konstanze T. Schiessl

    2017-10-01

    Full Text Available A central question in microbial ecology is whether microbial interactions are predominantly cooperative or competitive. The secretion of siderophores, microbial iron chelators, is a model system for cooperative interactions. However, siderophores have also been shown to mediate competition by sequestering available iron and making it unavailable to competitors. The details of how siderophores mediate competition are not well understood, especially considering the complex distribution of iron phases in the environment. One pertinent question is whether sequestering iron through siderophores can indeed be effective in natural conditions; many natural environments are characterized by large pools of precipitated iron, and it is conceivable that any soluble iron that is sequestered by siderophores is replenished by the dissolution of these precipitated iron sources. Our goal here was to address this issue, and investigate the magnitude and mechanism of siderophore-mediated competition in the presence of precipitated iron. We combined experimental work with thermodynamic modeling, using Pseudomonas aeruginosa as a model system and ferrihydrite precipitates as the iron source with low solubility. Our experiments show that competitive growth inhibition by the siderophore pyochelin is indeed efficient, and that inhibition of a competitor can even have a stronger growth-promoting effect than solubilization of precipitated iron. Based on the results of our thermodynamic models we conclude that the observed inhibition of a competitor is effective because sequestered iron is only very slowly replenished by the dissolution of precipitated iron. Our research highlights the importance of competitive benefits mediated by siderophores, and underlines that the dynamics of siderophore production and uptake in environmental communities could be a signature of competitive, not just cooperative, dynamics.

  4. Magnitude and Mechanism of Siderophore-Mediated Competition at Low Iron Solubility in the Pseudomonas aeruginosa Pyochelin System.

    Science.gov (United States)

    Schiessl, Konstanze T; Janssen, Elisabeth M-L; Kraemer, Stephan M; McNeill, Kristopher; Ackermann, Martin

    2017-01-01

    A central question in microbial ecology is whether microbial interactions are predominantly cooperative or competitive. The secretion of siderophores, microbial iron chelators, is a model system for cooperative interactions. However, siderophores have also been shown to mediate competition by sequestering available iron and making it unavailable to competitors. The details of how siderophores mediate competition are not well understood, especially considering the complex distribution of iron phases in the environment. One pertinent question is whether sequestering iron through siderophores can indeed be effective in natural conditions; many natural environments are characterized by large pools of precipitated iron, and it is conceivable that any soluble iron that is sequestered by siderophores is replenished by the dissolution of these precipitated iron sources. Our goal here was to address this issue, and investigate the magnitude and mechanism of siderophore-mediated competition in the presence of precipitated iron. We combined experimental work with thermodynamic modeling, using Pseudomonas aeruginosa as a model system and ferrihydrite precipitates as the iron source with low solubility. Our experiments show that competitive growth inhibition by the siderophore pyochelin is indeed efficient, and that inhibition of a competitor can even have a stronger growth-promoting effect than solubilization of precipitated iron. Based on the results of our thermodynamic models we conclude that the observed inhibition of a competitor is effective because sequestered iron is only very slowly replenished by the dissolution of precipitated iron. Our research highlights the importance of competitive benefits mediated by siderophores, and underlines that the dynamics of siderophore production and uptake in environmental communities could be a signature of competitive, not just cooperative, dynamics.

  5. Identification and structural characterization of serobactins, a suite of lipopeptide siderophores produced by the grass endophyte Herbaspirillum seropedicae.

    Science.gov (United States)

    Rosconi, Federico; Davyt, Danilo; Martínez, Verónica; Martínez, Marcela; Abin-Carriquiry, Juan Andrés; Zane, Hannah; Butler, Alison; de Souza, Emanuel M; Fabiano, Elena

    2013-03-01

    Herbaspirillum seropedicae Z67 is a diazotrophic endophyte able to colonize the interior of many economically relevant crops such as rice, wheat, corn and sorghum. Structures of siderophores produced by bacterial endophytes have not yet been elucidated. The aim of this work was to identify and characterize the siderophores produced by this bacterium. In a screening for mutants unable to produce siderophores we found a mutant that had a transposon insertion in a non-ribosomal peptide synthase (NRPS) gene coding for a putative siderophore biosynthetic enzyme. The chemical structure of the siderophore was predicted using computational genomic tools. The predicted structure was confirmed by chemical analysis. We found that siderophores produced by H. seropedicae Z67 are a suite of amphiphilic lipopeptides, named serobactin A, B and C, which vary by the length of the fatty acid chain. We also demonstrated the biological activity of serobactins as nutritional iron sources for H. seropedicae. These are the first structurally described siderophores produced by endophytic bacteria. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  6. Catecholate-siderophore produced by As-resistant bacterium effectively dissolved FeAsO_4 and promoted Pteris vittata growth

    International Nuclear Information System (INIS)

    Liu, Xue; Yang, Guang-Mei; Guan, Dong-Xing; Ghosh, Piyasa; Ma, Lena Q.

    2015-01-01

    The impact of siderophore produced by arsenic-resistant bacterium Pseudomonas PG12 on FeAsO_4 dissolution and plant growth were examined. Arsenic-hyperaccumulator Pteris vittata was grown for 7 d in 0.2-strength Fe-free Hoagland solution containing FeAsO_4 mineral and PG12-siderophore or fungal-siderophore desferrioxamine B (DFOB). Standard siderophore assays indicated that PG12-siderophore was catecholate-type. PG12-siderophore was more effective in promoting FeAsO_4 dissolution, and Fe and As plant uptake than DFOB. Media soluble Fe and As in PG12 treatment were 34.6 and 3.07 μM, 1.6- and 1.4-fold of that in DFOB. Plant Fe content increased from 2.93 to 6.24 g kg"−"1 in the roots and As content increased from 14.3 to 78.5 mg kg"−"1 in the fronds. Besides, P. vittata in PG12 treatment showed 2.6-times greater biomass than DFOB. While P. vittata fronds in PG12 treatment were dominated by AsIII, those in DFOB treatment were dominated by AsV (61–77%). This study showed that siderophore-producing arsenic-resistant rhizobacteria may have potential in enhancing phytoremediation of arsenic-contaminated soils. - Graphical abstract: As-induced root exudate phytate enhanced FeAsO_4 dissolution, and As uptake and plant growth of Pteris vittata. Display Omitted - Highlights: • Arsenic-resistant rhizobacterium Pseudomonas PG12 was from rhizosphere of As-hyperaccumulator Pteris vittata. • PG12 was effective in producing catecholate-type siderophore with high affinity with Fe. • PG12-produced siderophore increased Fe and As uptake and growth in P. vittata. - Siderophores produced by arsenic-resistant bacteria were effective in solubilizing FeAsO_4 mineral and enhancing plant growth of As-hyperaccumulator Pteris vittata.

  7. Siderophores as iron storage compounds in the yeasts Rhodotorula minuta and Ustilago sphaerogena detected by in vivo Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Matzanke, B.F.; Winkelmann, G.; Bill, E.; Trautwein, A.X.

    1990-01-01

    In the yeasts Rhodotorula minuta and Ustilago sphaerogena siderophores represent the main intracellular iron pool. We suggest a ferritin substituting function of these siderophores in addition to their role as iron transport agents. In Rhodotorula transport and storage siderophore is the same compound whereas in Ustilago the iron-storage siderophore is ferrichrome. Besides siderophores, merely two iron metabolites can be observed. Other iron-requiring compounds are at least one order of magnitude less abundant in these yeasts. The ferrous metabolite has been detected in many other microbial systems and seems to be of general occurence and importance. (orig.)

  8. Distinct Siderophores Contribute to Iron Cycling in the Mesopelagic at Station ALOHA

    Directory of Open Access Journals (Sweden)

    Randelle M. Bundy

    2018-03-01

    Full Text Available The distribution of dissolved iron (Fe, total organic Fe-binding ligands, and siderophores were measured between the surface and 400 m at Station ALOHA, a long term ecological study site in the North Pacific Subtropical Gyre. Dissolved Fe concentrations were low throughout the water column and strong organic Fe-binding ligands exceeded dissolved Fe at all depths; varying from 0.9 nmol L−1 in the surface to 1.6 nmol L−1 below 150 m. Although Fe does not appear to limit microbial production, we nevertheless found siderophores at nearly all depths, indicating some populations of microbes were responding to Fe stress. Ferrioxamine siderophores were most abundant in the upper water column, with concentrations between 0.1 and 2 pmol L−1, while a suite of amphibactins were found below 200 m with concentrations between 0.8 and 11 pmol L−1. The distinct vertical distribution of ferrioxamines and amphibactins may indicate disparate strategies for acquiring Fe from dust in the upper water column and recycled organic matter in the lower water column. Amphibactins were found to have conditional stability constants (log KFeL1,Fe′cond ranging from 12.0 to 12.5, while ferrioxamines had much stronger conditional stability constants ranging from 14.0 to 14.4, within the range of observed L1 ligands by voltammetry. We used our data to calculate equilibrium Fe speciation at Station ALOHA to compare the relative concentration of inorganic and siderophore complexed Fe. The results indicate that the concentration of Fe bound to siderophores was up to two orders of magnitude higher than inorganic Fe, suggesting that even if less bioavailable, siderophores were nevertheless a viable pathway for Fe acquisition by microbes at our study site. Finally, we observed rapid production of ferrioxamine E by particle-associated bacteria during incubation of freshly collected sinking organic matter. Fe-limitation may therefore be a factor in regulating carbon metabolism

  9. Variation in siderophore biosynthetic gene distribution and production across environmental and faecal populations of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Laura J Searle

    Full Text Available Iron is essential for Escherichia coli growth and survival in the host and the external environment, but its availability is generally low due to the poor solubility of its ferric form in aqueous environments and the presence of iron-withholding proteins in the host. Most E. coli can increase access to iron by excreting siderophores such as enterobactin, which have a very strong affinity for Fe3+. A smaller proportion of isolates can generate up to 3 additional siderophores linked with pathogenesis; aerobactin, salmochelin, and yersiniabactin. However, non-pathogenic E. coli are also able to synthesise these virulence-associated siderophores. This raises questions about their role in the ecology of E. coli, beyond virulence, and whether specific siderophores might be linked with persistence in the external environment. Under the assumption that selection favours phenotypes that confer a fitness advantage, we compared siderophore production and gene distribution in E. coli isolated either from agricultural plants or the faeces of healthy mammals. This population-level comparison has revealed that under iron limiting growth conditions plant-associated isolates produced lower amounts of siderophores than faecal isolates. Additionally, multiplex PCR showed that environmental isolates were less likely to contain loci associated with aerobactin and yersiniabactin synthesis. Although aerobactin was linked with strong siderophore excretion, a significant difference in production was still observed between plant and faecal isolates when the analysis was restricted to strains only able to synthesise enterobactin. This finding suggests that the regulatory response to iron limitation may be an important trait associated with adaptation to the non-host environment. Our findings are consistent with the hypothesis that the ability to produce multiple siderophores facilitates E. coli gut colonisation and plays an important role in E. coli commensalism.

  10. Synthesis, enantiomeric resolution, F-18 labeling and biodistribution of reboxetine analogs: promising radioligands for imaging the norepinephrine transporter with positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, K.-S. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Ding, Y.-S. [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)]. E-mail: ding@bnl.gov; Kim, Sung-Won [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Kil, Kun-Eek [Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2005-05-01

    Racemic and enantiomerically pure ((S,S) and (R,R)) 2-[{alpha}-(2-(2-[{sup 18}F]fluoroethoxy)phenoxy)benzyl]morpholine ([{sup 18}F]FRB) and its tetradeuterated form [{sup 18}F]FRB-D{sub 4}, analogs of the highly selective norepinephrine reuptake inhibitor reboxetine (2-[{alpha}-(2-ethoxyphenoxy)benzyl]morpholine, RB), have been synthesized for studies of norepinephrine transporter (NET) system with positron emission tomography (PET). The [{sup 18}F]fluorinated precursor, (S,S)/(R,R)-N-tert-butyloxycarbonyl-2-[{alpha}-(2-hydroxyphenoxy)benzyl] morpholine ((S,S)/(R,R)-N-Boc-desethylRB), was prepared by the N-protection of (S,S)/(R,R)-2-[{alpha}-(2-hydroxyphenoxy)benzyl]morpholine ((S,S)/(R,R)-desethylRB) with a tert-butyloxycarbonyl (Boc) group followed by enantiomeric resolution with chiral HPLC to provide both (S,S) and (R,R) enantiomers with >99% enantiomeric purity. These compounds were then used for radiosynthesis to prepare enantiomerically pure [{sup 18}F]FRB and [{sup 18}F]FRB-D{sub 4} via the following three-step procedure: (1) formation of 1-bromo-2-[{sup 18}F]fluoroethane ([{sup 18}F]BFE or [{sup 18}F]BFE-D{sub 4}) by nucleophilic displacement of 2-bromoethyl triflate (or D{sub 4} analog) with no-carrier added [{sup 18}F]F{sup -} in THF; (2) reaction of [{sup 18}F]BFE (or [{sup 18}F]BFE-D{sub 4}) with N-Boc-desethylRB in DMF in the presence of excess base; and (3) deprotection with trifluoroacetic acid. The racemates, (S,S) and (R,R) enantiomers of [{sup 18}F]FRB and [{sup 18}F]FRB-D{sub 4} were obtained in 11-27% (decay corrected to the end of bombardment, EOB) in 120-min synthesis time with a radiochemical purity of >98% and specific activities of 21-48 GBq/{mu}mol (EOB). The results of the whole-body biodistribution studies with (S,S)-[{sup 18}F]FRB-D{sub 4} were similar to those with (S,S)-[{sup 18}F]FRB but showed relatively faster blood clearance and no significant in vivo defluorination. Positron emission tomography studies in baboon brain also

  11. Accumulation of rare earth elements by siderophore- forming ...

    Indian Academy of Sciences (India)

    2012-01-08

    Jan 8, 2012 ... siderophore and low-molecular-weight organic acids were found to be present in experiments with ... isms are often good producers of oxalic acid/oxalate, a ..... hydrothermal sediments in the Guaymas Basin: evidence for.

  12. In vitro and in vivo evaluation of selected 68Ga-siderophores for infection imaging

    International Nuclear Information System (INIS)

    Petrik, Milos; Haas, Hubertus; Schrettl, Markus; Helbok, Anna; Blatzer, Michael; Decristoforo, Clemens

    2012-01-01

    Introduction: Siderophores are low-molecular-mass iron chelators serving as iron transporters for almost all bacteria, fungi and some plants. Iron is an essential element for majority of organisms and plays an important role in virulence of pathogenic organisms. 68 Ga is a positron emitter with complexing properties comparable to those of Fe(III) and readily available from a generator. Initial studies with 68 Ga-triacetylfusarinine C (TAFC) showed excellent targeting properties in a rat infection model. We report here on the in vitro and in vivo evaluation of other siderophores radiolabelled with 68 Ga as potential radiopharmaceuticals for infection imaging. Methods: 68 Ga labelling was performed using acetate buffer. Stability, log P and protein binding values were determined. In vitro uptake was tested using iron-deficient and iron-sufficient Aspergillus fumigatus (A.f.) cultures. Biodistribution of 68 Ga-siderophores was studied in Balb/c mice. Results: Significant differences among studied siderophores were observed in labelling efficiency, stability and protein binding. Uptake in A.f. cultures was highly dependent on iron load and type of the siderophore. In mice, 68 Ga-TAFC and 68 Ga-ferrioxamine E (FOXE) showed rapid renal excretion and low blood values even at a short period after injection; in contrast, 68 Ga-ferricrocin and 68 Ga-ferrichrome revealed high retention in blood and 68 Ga-fusarinine C showed very high kidney retention. Conclusions: Some of the studied siderophores bind 68 Ga with high affinity and stability, especially 68 Ga-TAFC and 68 Ga-FOXE. Low values of protein binding, high and specific uptake in A.f., and excellent in vivo biodistribution make them favourable agents for Aspergillus infection imaging.

  13. Laboratory and field measurements of enantiomeric monoterpene emissions as a function of chemotype, light and temperature

    Science.gov (United States)

    Song, W.; Staudt, M.; Bourgeois, I.; Williams, J.

    2014-03-01

    Plants emit significant amounts of monoterpenes into the earth's atmosphere, where they react rapidly to form a multitude of gas phase species and particles. Many monoterpenes exist in mirror-image forms or enantiomers. In this study the enantiomeric monoterpene profile for several representative plants (Quercus ilex L., Rosmarinus officinalis L., and Pinus halepensis Mill.) was investigated as a function of chemotype, light and temperature both in the laboratory and in the field. Analysis of enantiomeric monoterpenes from 19 Quercus ilex individuals from Southern France and Spain revealed four regiospecific chemotypes (genetically fixed emission patterns). In agreement with previous work, only Quercus ilex emissions increased strongly with light. However, for all three plant species no consistent enantiomeric variation was observed as a function of light, and the enantiomeric ratio of α-pinene was found to vary by less than 20% from 100 and 1000 μmol m-2 s-1 PAR (photosynthetically active radiation). The rate of monoterpene emission increased with temperature from all three plant species, but little variation in the enantiomeric distribution of α-pinene was observed with temperature. There was more enantiomeric variability between individuals of the same species than could be induced by either light or temperature. Field measurements of α-pinene enantiomer mixing ratios in the air, taken at a Quercus ilex forest in Southern France, and several other previously reported field enantiomeric ratio diel cycle profiles are compared. All show smoothly varying diel cycles (some positive and some negative) even over changing wind directions. This is surprising in comparison with variations of enantiomeric emission patterns shown by individuals of the same species.

  14. Siderophores as iron storage compounds in the yeasts Rhodotorula minuta and Ustilago sphaerogena detected by in vivo Mössbauer spectroscopy

    Science.gov (United States)

    Matzanke, B. F.; Bill, E.; Trautwein, A. X.; Winkelmann, G.

    1990-07-01

    In the yeasts Rhodotorula minuta and Ustilago sphaerogena siderophores represent the main intracellular iron pool. We suggest a ferritin substituting function of these siderophores in addition to their role as iron transport agents. In Rhodotorula transport and storage siderophore is the same compound whereas in Ustilago the iron-storage siderophore is ferrichrome. Besides siderophores, merely two iron metabolites can be observed. Other iron-requiring compounds are at least one order of magnitude less abundant in these yeasts. The ferrous metabolite has been detected in many other microbial systems and seems to be of general occurence and importance.

  15. Enantiomeric Distribution of Some Linalool Containing Essential Oils and Their Biological Activities

    Directory of Open Access Journals (Sweden)

    K. Hüsnü Can Başer

    2010-10-01

    Full Text Available The enantiomeric composition of linalool was determined in 42 essential oils using chiral columns. Essential oils were analyzed by multidimentional gas chromatography-mass spectrometry using a non-chiral and chiral FSC columns combination with modified g -cyclodextrine (Lipodex E as the chiral stationary phase without previous isolation of the compound from the mixture. The essential oils of Achillea, Ballota, Calamintha, Micromeria, Hedychium, Tanacetum, Coriandrum, Xanthoxylum, Ocimum, Thymus, Lavandula, Elettaria, Cinnamomum, Salvia, Origanum, Satureja, Nepeta, Stachys were used as source material for enantiomeric separation of linalool. Enantiomeric distribution of linalool showed (--linalool was much more common than the (+-linalool in the essential oils in this study. (-- and (+-linalool enantiomers were evaluated for antimicrobial, antifungal and antimalarial activities. Both enantiomers demonstrated approximately 50% growth inhibition of Botrytis cinerea at 48 hrs.

  16. Uranium extraction by complexation with siderophores

    Science.gov (United States)

    Bahamonde Castro, Cristina

    One of the major concerns of energy production is the environmental impact associated with the extraction of natural resources. Nuclear energy fuel is obtained from uranium, an abundant and naturally occurring element in the environment, but the currently used techniques for uranium extraction leave either a significant fingerprint (open pit mines) or a chemical residue that alters the pH of the environment (acid or alkali leaching). It is therefore clear that a new and greener approach to uranium extraction is needed. Bioleaching is one potential alternative. In bioleaching, complexants naturally produced from fungi or bacteria may be used to extract the uranium. In the following research, the siderophore enterobactin, which is naturally produced by bacteria to extract and solubilize iron from the environment, is evaluated to determine its potential for complexing with uranium. To determine whether enterobactin could be used for uranium extraction, its acid dissociation and its binding strength with the metal of interest must be determined. Due to the complexity of working with radioactive materials, lanthanides were used as analogs for uranium. In addition, polyprotic acids were used as structural and chemical analogs for the siderophore during method development. To evaluate the acid dissociation of enterobactin and the subsequent binding constants with lanthanides, three different analytical techniques were studied including: potentiometric titration, UltraViolet Visible (UV-Vis) spectrophotometry and Isothermal Titration Calorimetry (ITC). After evaluation of three techniques, a combination of ITC and potentiometric titrations was deemed to be the most viable way for studying the siderophore of interest. The results obtained from these studies corroborate the ideal pH range for enterobactin complexation to the lanthanide of interest and pave the way for determining the strength of complexation relative to other naturally occurring metals. Ultimately, this

  17. Enantiomerization and stereoselectivity in bioaccumulation of furalaxyl in Tenebrio molitor larvae.

    Science.gov (United States)

    Yin, Jing; Gao, Yongxin; Zhu, Feilong; Hao, Weiyu; Xu, Qi; Wang, Huili; Guo, Baoyuan

    2017-11-01

    Furalaxyl is a chiral pesticide and widely used in modern agriculture as racemate mixture. The enantiomerization and enantioselecive bioaccumulation by a single dose of furalaxyl to Tenebrio molitor larvae under laboratory conditions were studied using a high-performance liquid chromatography tandem mass spectroscopy method based on a ChiralPAK IC column. Our results showed that a significant enantiomerization (interconversion between R-enantiomer and S-enantiomer) was observed in Tenebrio molitor larvae under R- or S-furalaxyl exposure. Though the two furalaxyl enantiomers exhibited low-capacity of bioaccumulation in Tenebrio molitor larvae, bioaccumulation of rac-furalaxyl was enantioselective with a preferential accumulation of S-furalaxyl at 10mg/kg dosage exposure. In addition, enantiomerization and enantioselective degradation of the two enantiomers was not observed in wheat bran. These results showed that enantioselectivtiy of furalaxyl enantiomers was an important process combined with degradation, metabolism and enatiomerization in organisms. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Production and Characterization of Desmalonichrome Relative Binding Affinity for Uranyl Ions in Relation to Other Siderophores

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Kai-For; Dai, Ziyu; Wunschel, David S.

    2016-06-24

    Siderophores are Fe binding secondary metabolites that have been investigated for their uranium binding properties. Much of the previous work has focused on characterizing hydroxamate types of siderophores, such as desferrioxamine B, for their uranyl binding affinity. Carboxylate forms of these metabolites hold potential to be more efficient chelators of uranyl, yet they have not been widely studied and are more difficult to obtain. Desmalonichrome is a carboxylate siderophore which is not commercially available and so was obtained from the ascomycete fungus Fusarium oxysporum cultivated under Fe depleted conditions. The relative affinity for uranyl binding of desmalonichrome was investigated using a competitive analysis of binding affinities between uranyl acetate and different concentrations of iron(III) chloride using electrospray ionization mass spectrometry (ESI-MS). In addition to desmalonichrome, three other siderophores, including two hydroxamates (desferrioxamine B and desferrichrome) and one carboxylate (desferrichrome A) were studied to understand their relative affinities for the uranyl ion at two pH values. The binding affinities of hydroxymate siderophores to uranyl ion were found to decrease to a greater degree at lower pH as the concentration of Fe (III) ion increases. On the other hand, lowering pH has little impact on the binding affinities between carboxylate siderophores and uranyl ion. Desmalonichrome was shown to have the greatest relative affinity for uranyl at any pH and Fe(III) concentration. These results suggest that acidic functional groups in the ligands are critical for strong chelation with uranium at lower pH.

  19. Characterization of microbial siderophores by mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Pluháček, Tomáš; Lemr, Karel; Ghosh, D.; Milde, D.; Novák, Jiří; Havlíček, Vladimír

    2016-01-01

    Roč. 35, č. 1 (2016), s. 35-47 ISSN 0277-7037 R&D Projects: GA MŠk(CZ) LD13038; GA ČR(CZ) GAP206/12/1150; GA MŠk(CZ) LO1509 Institutional support: RVO:61388971 Keywords : iron * siderophores * mass spectrometry Subject RIV: CE - Biochemistry Impact factor: 9.373, year: 2016

  20. Investigation of the mechanism of iron acquisition by the marine bacterium Alteromonas luteoviolaceus: Characterization of siderophore production

    International Nuclear Information System (INIS)

    Reid, R.T.; Butler, A.

    1991-01-01

    Iron availability in the ocean ranges from one to four orders of magnitude below typical growth requirements of bacteria. The discrepancy between Fe availability and requirements raises questions about the mechanisms that marine bacteria use to sequester Fe 3+ . Surprisingly little is known about the siderophores produced by marine bacteria. Growth conditions of an open-ocean bacterial isolate, Alteromonas luteoviolaceus, were investigated to determine the conditions which enhance siderophore production. Methods to isolate and purify the siderophores were determined. The siderophores produced by A. luteoviolaceus were partially characterized by mass spectral analysis, amino acid analysis, qualitative analytical tests, chemical degradation, and nuclear magnetic resonance. A new set of outer membrane proteins was also produced when the bacterium was grown under Fe-limited conditions

  1. Enantiomeric behaviour of albendazole and fenbendazole sulfoxides in domestic animals: pharmacological implications.

    Science.gov (United States)

    Capece, Bettencourt P S; Virkel, Guillermo L; Lanusse, Carlos E

    2009-09-01

    Albendazole and fenbendazole are methylcarbamate benzimidazole anthelmintics extensively used to control gastrointestinal parasites in domestic animals. These parent compounds are metabolised to albendazole sulfoxide and fenbendazole sulfoxide (oxfendazole), respectively. Both sulfoxide derivatives are anthelmintically active and are manufactured for use in animals. They metabolites have an asymmetric centre on their chemical structures and two enantiomeric forms of each sulfoxide have been identified in plasma, tissues of parasite location and within target helminths. Both the flavin-monooxygenase and cytochrome P450 systems are involved in the enantioselective biotransformation of these anthelmintic compounds in ruminant species. A relevant progress on the understanding of the relationship among enantioselective metabolism and systemic availability of each enantiomeric form has been achieved. This article reviews the current knowledge on the pharmacological implications of the enantiomeric behaviour of albendazole sulfoxide and oxfendazole in domestic animals.

  2. Adsorption of hydroxamate siderophores and EDTA on goethite in the presence of the surfactant sodium dodecyl sulfate

    Directory of Open Access Journals (Sweden)

    Xu Jide

    2009-06-01

    Full Text Available Abstract Siderophore-promoted iron acquisition by microorganisms usually occurs in the presence of other organic molecules, including biosurfactants. We have investigated the influence of the anionic surfactant sodium dodecyl sulfate (SDS on the adsorption of the siderophores DFOB (cationic and DFOD (neutral and the ligand EDTA (anionic onto goethite (α-FeOOH at pH 6. We also studied the adsorption of the corresponding 1:1 Fe(III-ligand complexes, which are products of the dissolution process. Adsorption of the two free siderophores increased in a similar fashion with increasing SDS concentration, despite their difference in molecule charge. In contrast, SDS had little effect on the adsorption of EDTA. Adsorption of the Fe-DFOB and Fe-DFOD complexes also increased with increasing SDS concentrations, while adsorption of Fe-EDTA decreased. Our results suggest that hydrophobic interactions between adsorbed surfactants and siderophores are more important than electrostatic interactions. However, for strongly hydrophilic molecules, such as EDTA and its iron complex, the influence of SDS on their adsorption seems to depend on their tendency to form inner-sphere or outer-sphere surface complexes. Our results demonstrate that surfactants have a strong influence on the adsorption of siderophores to Fe oxides, which has important implications for siderophore-promoted dissolution of iron oxides and biological iron acquisition.

  3. Characterization of rhizobacteria associated to maize crop in IAA, siderophores and salicylic acid metabolite production

    Directory of Open Access Journals (Sweden)

    Annia Hernández

    2004-01-01

    Full Text Available It has been demonstrated that rhizobacteria are able to produce metabolites having agricultural interest, including salicylic acid, the siderophores and phytohormones. Indol acetic acid (IAA is the most well-known and studied auxin, playing a governing role in culture growth. The object of this work was to characterise rhizobacteria associated with the maize crop in terms of producing IAA, siderophores and salicylic acid metabolites. Burkholderia cepacia and Pseudomonas fluorescens strains previously isolated from maize Francisco variety rhizosphere were used. Colorimetric and chromatographic techniques for detecting these metabolites were studied; multi-variable analysis of hierarchic conglomerate and complete ligament were used for selecting the best strains for producing metabolites of interest. These results demonstrated that all rhizobacteria strains studied produced IAA, siderophores and salicylic acid metabolites. Burkholderia cepacia MBf21, MBp1, MBp2, MBf22, MBp3, MBf20, MBf 15 and Pseudomonas fluorescens MPp4strains have presented the greatest production of these metabolites, showing that these strains could be used in promoting vegetal growth in economically important cultures. Key words: Pseudomonas fluorescens, Burkholderia cepacia, IAA, siderophore, salicylic acid.

  4. Actinobacteria phylogenomics, selective isolation from an iron oligotrophic environment and siderophore functional characterization, unveil new desferrioxamine traits.

    Science.gov (United States)

    Cruz-Morales, Pablo; Ramos-Aboites, Hilda E; Licona-Cassani, Cuauhtémoc; Selem-Mójica, Nelly; Mejía-Ponce, Paulina M; Souza-Saldívar, Valeria; Barona-Gómez, Francisco

    2017-09-01

    Desferrioxamines are hydroxamate siderophores widely conserved in both aquatic and soil-dwelling Actinobacteria. While the genetic and enzymatic bases of siderophore biosynthesis and their transport in model families of this phylum are well understood, evolutionary studies are lacking. Here, we perform a comprehensive desferrioxamine-centric (des genes) phylogenomic analysis, which includes the genomes of six novel strains isolated from an iron and phosphorous depleted oasis in the Chihuahuan desert of Mexico. Our analyses reveal previously unnoticed desferrioxamine evolutionary patterns, involving both biosynthetic and transport genes, likely to be related to desferrioxamines chemical diversity. The identified patterns were used to postulate experimentally testable hypotheses after phenotypic characterization, including profiling of siderophores production and growth stimulation of co-cultures under iron deficiency. Based in our results, we propose a novel des gene, which we term desG, as responsible for incorporation of phenylacetyl moieties during biosynthesis of previously reported arylated desferrioxamines. Moreover, a genomic-based classification of the siderophore-binding proteins responsible for specific and generalist siderophore assimilation is postulated. This report provides a much-needed evolutionary framework, with specific insights supported by experimental data, to direct the future ecological and functional analysis of desferrioxamines in the environment. © FEMS 2017.

  5. Potential of siderophore-producing bacteria for improving heavy metal phytoextraction.

    Science.gov (United States)

    Rajkumar, Mani; Ae, Noriharu; Prasad, Majeti Narasimha Vara; Freitas, Helena

    2010-03-01

    Phytoremediation holds promise for in situ treatment of heavy metal contaminated soils. Recently, the benefits of combining siderophore-producing bacteria (SPB) with plants for metal removal from contaminated soils have been demonstrated. Metal-resistant SPB play an important role in the successful survival and growth of plants in contaminated soils by alleviating the metal toxicity and supplying the plant with nutrients, particularly iron. Furthermore, bacterial siderophores are able to bind metals other than iron and thus enhance their bioavailability in the rhizosphere of plants. Overall, an increase in plant growth and metal uptake will further enhance the effectiveness of phytoremediation processes. Here, we highlight the diversity and ecology of metal resistant SPB and discuss their potential role in phytoremediation of heavy metals.

  6. Preliminary X-ray diffraction analysis of YqjH from Escherichia coli: a putative cytoplasmic ferri-siderophore reductase.

    Science.gov (United States)

    Bamford, Vicki A; Armour, Maria; Mitchell, Sue A; Cartron, Michaël; Andrews, Simon C; Watson, Kimberly A

    2008-09-01

    YqjH is a cytoplasmic FAD-containing protein from Escherichia coli; based on homology to ViuB of Vibrio cholerae, it potentially acts as a ferri-siderophore reductase. This work describes its overexpression, purification, crystallization and structure solution at 3.0 A resolution. YqjH shares high sequence similarity with a number of known siderophore-interacting proteins and its structure was solved by molecular replacement using the siderophore-interacting protein from Shewanella putrefaciens as the search model. The YqjH structure resembles those of other members of the NAD(P)H:flavin oxidoreductase superfamily.

  7. Scavenging Iron: A Novel Mechanism of Plant Immunity Activation by Microbial Siderophores1[C][W

    Science.gov (United States)

    Aznar, Aude; Chen, Nicolas W.G.; Rigault, Martine; Riache, Nassima; Joseph, Delphine; Desmaële, Didier; Mouille, Grégory; Boutet, Stéphanie; Soubigou-Taconnat, Ludivine; Renou, Jean-Pierre; Thomine, Sébastien; Expert, Dominique; Dellagi, Alia

    2014-01-01

    Siderophores are specific ferric iron chelators synthesized by virtually all microorganisms in response to iron deficiency. We have previously shown that they promote infection by the phytopathogenic enterobacteria Dickeya dadantii and Erwinia amylovora. Siderophores also have the ability to activate plant immunity. We have used complete Arabidopsis transcriptome microarrays to investigate the global transcriptional modifications in roots and leaves of Arabidopsis (Arabidopsis thaliana) plants after leaf treatment with the siderophore deferrioxamine (DFO). Physiological relevance of these transcriptional modifications was validated experimentally. Immunity and heavy-metal homeostasis were the major processes affected by DFO. These two physiological responses could be activated by a synthetic iron chelator ethylenediamine-di(o-hydroxyphenylacetic) acid, indicating that siderophores eliciting activities rely on their strong iron-chelating capacity. DFO was able to protect Arabidopsis against the pathogenic bacterium Pseudomonas syringae pv tomato DC3000. Siderophore treatment caused local modifications of iron distribution in leaf cells visible by ferrocyanide and diaminobenzidine-H2O2 staining. Metal quantifications showed that DFO causes a transient iron and zinc uptake at the root level, which is presumably mediated by the metal transporter iron regulated transporter1 (IRT1). Defense gene expression and callose deposition in response to DFO were compromised in an irt1 mutant. Consistently, plant susceptibility to D. dadantii was increased in the irt1 mutant. Our work shows that iron scavenging is a unique mechanism of immunity activation in plants. It highlights the strong relationship between heavy-metal homeostasis and immunity. PMID:24501001

  8. Fast mass spectrometry-based enantiomeric excess determination of proteinogenic amino acids.

    Science.gov (United States)

    Fleischer, Heidi; Thurow, Kerstin

    2013-03-01

    A rapid determination of the enantiomeric excess of proteinogenic amino acids is of great importance in various fields of chemical and biologic research and industries. Owing to their different biologic effects, enantiomers are interesting research subjects in drug development for the design of new and more efficient pharmaceuticals. Usually, the enantiomeric composition of amino acids is determined by conventional analytical methods such as liquid or gas chromatography or capillary electrophoresis. These analytical techniques do not fulfill the requirements of high-throughput screening due to their relative long analysis times. The method presented allows a fast analysis of chiral amino acids without previous time consuming chromatographic separation. The analytical measurements base on parallel kinetic resolution with pseudoenantiomeric mass tagged auxiliaries and were carried out by mass spectrometry with electrospray ionization. All 19 chiral proteinogenic amino acids were tested and Pro, Ser, Trp, His, and Glu were selected as model substrates for verification measurements. The enantiomeric excesses of amino acids with non-polar and aliphatic side chains as well as Trp and Phe (aromatic side chains) were determined with maximum deviations of the expected value less than or equal to 10ee%. Ser, Cys, His, Glu, and Asp were determined with deviations lower or equal to 14ee% and the enantiomeric excess of Tyr were calculated with 17ee% deviation. The total screening process is fully automated from the sample pretreatment to the data processing. The method presented enables fast measurement times about 1.38 min per sample and is applicable in the scope of high-throughput screenings.

  9. Activity of siderophores against drug-resistant Gram-positive and Gram-negative bacteria

    Directory of Open Access Journals (Sweden)

    Gokarn K

    2018-01-01

    Full Text Available Karuna Gokarn,1,2 Ramprasad B Pal1 1Department of Microbiology, Sir Hurkisondas Nurrotumdas Medical Research Society, 2Caius Research Laboratory, St Xavier’s College, Mumbai, India Abstract: Infections by drug-resistant bacteria are life-threatening. As iron is a vital element for the growth of bacteria, iron-chelating agents (siderophores can be used to arrest their multiplication. Exogenous siderophores – exochelin-MS and deferoxamine-B – were evaluated for their inhibitory activity against methicillin-resistant Staphylococcus aureus and metallo-β-lactamase producers – Pseudomonas aeruginosa and Acinetobacter baumannii – by disc diffusion, micro-broth dilution, and turbidimetric growth assays. The drug-resistant isolates were inhibited by the synergistic activity of siderophores and antibiotics. Minimum inhibitory concentration of exochelin-MS+ampicillin for different isolates was between 0.05 and 0.5 mg/mL. Minimum inhibitory concentration of deferoxamine-B+ampicillin was 1.0 mg/mL and greater. Iron-chelation therapy could provide a complementary approach to overcome drug resistance in pathogenic bacteria. Keywords: iron-chelation, xenosiderophores, exochelin MS, deferoxamine B

  10. The role of siderophores in metal homeostasis of members of the genus Burkholderia.

    Science.gov (United States)

    Mathew, Anugraha; Jenul, Christian; Carlier, Aurelien L; Eberl, Leo

    2016-02-01

    Although members of the genus Burkholderia can utilize a high-affinity iron uptake system to sustain growth under iron-limiting conditions, many strains also produce siderophores, suggesting that they may serve alternative functions. Here we demonstrate that the two Burkholderia siderophores pyochelin and ornibactin can protect the cells from metal toxicity and thus play an alternative role in metal homeostasis. We also demonstrate that metals such as copper and zinc induce the production of ornibactin. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. A search for glomuferrin: a potential siderophore of arbuscular mycorrhizal fungi of the genus Glomus.

    Science.gov (United States)

    Winkelmann, Günther

    2017-08-01

    Most fungi are known to synthesize siderophores under iron limitation. However, arbuscular mycorrhizal fungi (AM fungi) have so far not been reported to produce siderophores, although their metabolism is iron-dependent. In an approach to isolate siderophores from AM fungi, we have grown plants of Tagetes patula nana in the presence of spores from AM fungi of the genus Glomus (G. etunicatum, G. mossae & unidentified Glomus sp.) symbiotically under iron limitation and sterile conditions. A siderophore was isolated from infected roots after 2-3 weeks of growth in pots containing low-iron sand with Hoagland solution. HPLC analysis of the root cell lysate revealed a peak at a retention time of 6.7 min which showed iron-binding properties in a chrome azurol S test. The compound was isolated by preparative HPLC and the structure was determined by high resolution electrospray FTICR-MS and GC/MS analysis of the hydrolysis products. From an observed absolute mass to charge ratio (m/z) of 401.11925 [M+H] + with a relative mass error of ∆ = 0.47 ppm an elemental composition of C 16 H 21 N 2 O 10 [M+H] + was derived, suggesting a molecular weight of 400 Da for glomuferrin. Corresponnding ion masses of m/z 423.10 and m/z 439.06 were asigned to the Na-adduct and K-adduct respectively. A mass of 455.03836 confirmed an Fe- complex with an elemental composition of C 16 H 19 N 2 O 10 Fe (∆ = 0.15 ppm). GC/MS analysis of the HCl lysate (6 N HCL, 12 h) revealed 1,4 butanediamine. Thus the proposed structure of the isolated siderophore from Glomus species consisted of 1,4 butanediamine amidically linked to two dehydrated citrate residues, similar to the previously identified bis-amidorhizoferrin. Thus, the isolated siderophore (glomuferrin) is a member of the rhizoferrin family previously isolated from fungi of the Mucorales (Zygomycetes).

  12. Pathogenicity of Vibrio anguillarum serogroup O1 strains compared to plasmids, outer membrane protein profiles and siderophore production

    DEFF Research Database (Denmark)

    Pedersen, K.; Gram, Lone; Austin, D.A.

    1997-01-01

    The virulence of 18 strains of Vibrio anguillarum serogroup 01 was compared to plasmid content, expression of siderophores and outer membrane proteins. All strains, irrespective of plasmid content, produced siderophores and inducible outer membrane proteins under iron-limited conditions. Only str...

  13. Potential of Bacillus spp produces siderophores insuppressing thewilt disease of banana plants

    Science.gov (United States)

    Kesaulya, H.; Hasinu, J. V.; Tuhumury, G. NC

    2018-01-01

    In nature, different types of siderophore such as hydroxymate, catecholets and carboxylate, are produced by different bacteria. Bacillus spp were isolated from potato rhizospheric soil can produce siderophore of both catecholets and salicylate type with different concentrations. Various strains of Bacillus spp were tested for pathogen inhibition capability in a dual culture manner. The test results showed the ability of inhibition of pathogen isolated from banana wilt disease. From the result tested were found Bacillus niabensis Strain PT-32-1, Bacillus subtilis Strain SWI16b, Bacillus subtilis Strain HPC21, Bacillus mojavensis Strain JCEN3, and Bacillus subtilis Strain HPC24 showed different capabilities in suppressing pathogen.

  14. Pseudochelin A, a siderophore of Pseudoalteromonas piscicida S2040

    DEFF Research Database (Denmark)

    Sonnenschein, Eva; Stierhof, Marc; Goralczyk, Stephan

    2017-01-01

    techniques including 2D NMR and MS/MS fragmentation data. In bioassays selected fractions of the crude extract of S2040 inhibited the opportunistic pathogen Pseudomonas aeruginosa. Pseudochelin A displayed siderophore activity in the chrome azurol S assay at concentrations higher than 50 μM, and showed weak...

  15. Siderophore-dependent iron uptake systems as gates for antibiotic Trojan horse strategies against Pseudomonas aeruginosa.

    Science.gov (United States)

    Mislin, Gaëtan L A; Schalk, Isabelle J

    2014-03-01

    Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen responsible for nosocomial infections. The prevalence of antibiotic-resistant P. aeruginosa strains is increasing, necessitating the urgent development of new strategies to improve the control of this pathogen. Its bacterial envelope constitutes of an outer and an inner membrane enclosing the periplasm. This structure plays a key role in the resistance of the pathogen, by decreasing the penetration and the biological impact of many antibiotics. However, this barrier may also be seen as the "Achilles heel" of the bacterium as some of its functions provide opportunities for breaching bacterial defenses. Siderophore-dependent iron uptake systems act as gates in the bacterial envelope and could be used in a "Trojan horse" strategy, in which the conjugation of an antibiotic to a siderophore could significantly increase the biological activity of the antibiotic, by enhancing its transport into the bacterium. In this review, we provide an overview of the various siderophore-antibiotic conjugates that have been developed for use against P. aeruginosa and show that an accurate knowledge of the structural and functional features of the proteins involved in this transmembrane transport is required for the design and synthesis of effective siderophore-antibiotic Trojan horse conjugates.

  16. 2,2′,3,5′,6-PENTACHLOROBIPHENYL (PCB 95) AND ITS HYDROXYLATED METABOLITES ARE ENANTIOMERICALLY ENRICHED IN FEMALE MICE

    Science.gov (United States)

    Kania-Korwel, Izabela; Barnhart, Christopher D.; Stamou, Marianna; Truong, Kim M.; El-Komy, Mohammed H.M.E.; Lein, Pamela J.; Veng-Pedersen, Peter; Lehmler, Hans-Joachim

    2012-01-01

    Epidemiological and laboratory studies link polychlorinated biphenyls and their metabolites to adverse neurodevelopmental outcomes. Several neurotoxic PCB congeners are chiral and undergo enantiomeric enrichment in mammalian species, which may modulate PCB developmental neurotoxicity. This study measures levels and enantiomeric enrichment of PCB 95 and its hydroxylated metabolites (OH-PCBs) in adult female C57Bl/6 mice following subchronic exposure to racemic PCB 95. Tissue levels of PCB 95 and OH-PCBs increased with increasing dose. Dose-dependent enantiomeric enrichment of PCB 95 was observed in brain and other tissues. OH-PCBs also displayed enantiomeric enrichment in blood and liver, but were not detected in adipose and brain. In light of data suggesting enantioselective effects of chiral PCBs on molecular targets linked to PCB developmental neurotoxicity, our observations highlight the importance of accounting for PCB and OH-PCB enantiomeric enrichment in the assessment of PCB developmental neurotoxicity. PMID:22974126

  17. A highly conserved basidiomycete peptide synthetase produces a trimeric hydroxamate siderophore.

    Science.gov (United States)

    Brandenburger, Eileen; Gressler, Markus; Leonhardt, Robin; Lackner, Gerald; Habel, Andreas; Hertweck, Christian; Brock, Matthias; Hoffmeister, Dirk

    2017-08-25

    The model white-rot basidiomycete Ceriporiopsis ( Gelatoporia ) subvermispora B encodes putative natural product biosynthesis genes. Among them is the gene for the seven-domain nonribosomal peptide synthetase CsNPS2. It is a member of the as-yet uncharacterized fungal type VI siderophore synthetase family which is highly conserved and widely distributed among the basidiomycetes. These enzymes include only one adenylation (A) domain, i.e., one complete peptide synthetase module and two thiolation/condensation (T-C) di-domain partial modules which, together, constitute an AT 1 C 1 T 2 C 2 T 3 C 3 domain setup. The full-length CsNPS2 enzyme (274.5 kDa) was heterologously produced as polyhistidine fusion in Aspergillus niger as soluble and active protein. N 5 -acetyl- N 5 -hydroxy-l-ornithine (l-AHO) and N 5 - cis -anhydromevalonyl- N 5 -hydroxy-l-ornithine (l-AMHO) were accepted as substrates, as assessed in vitro using the substrate-dependent [ 32 P]ATP-pyrophosphate radioisotope exchange assay. Full-length holo -CsNPS2 catalyzed amide bond formation between three l-AHO molecules to release the linear l-AHO trimer, called basidioferrin, as product in vitro , which was verified by LC-HRESIMS. Phylogenetic analyses suggest that type VI family siderophore synthetases are widespread in mushrooms and have evolved in a common ancestor of basidiomycetes. Importance : The basidiomycete nonribosomal peptide synthetase CsNPS2 represents a member of a widely distributed but previously uninvestigated class (type VI) of fungal siderophore synthetases. Genes orthologous to CsNPS2 are highly conserved across various phylogenetic clades of the basidiomycetes. Hence, our work serves as a broadly applicable model for siderophore biosynthesis and iron metabolism in higher fungi. Also, our results on the amino acid substrate preference of CsNPS2 supports further understanding of the substrate selectivity of fungal adenylation domains. Methodologically, this report highlights the

  18. Iron Homeostasis in Mycobacterium tuberculosis: Mechanistic Insights into Siderophore-Mediated Iron Uptake

    Science.gov (United States)

    2016-01-01

    Mycobacterium tuberculosis requires iron for normal growth but faces a limitation of the metal ion due to its low solubility at biological pH and the withholding of iron by the mammalian host. The pathogen expresses the Fe3+-specific siderophores mycobactin and carboxymycobactin to chelate the metal ion from insoluble iron and the host proteins transferrin, lactoferrin, and ferritin. Siderophore-mediated iron uptake is essential for the survival of M. tuberculosis, as knockout mutants, which were defective in siderophore synthesis or uptake, failed to survive in low-iron medium and inside macrophages. But as excess iron is toxic due to its catalytic role in the generation of free radicals, regulation of iron uptake is necessary to maintain optimal levels of intracellular iron. The focus of this review is to present a comprehensive overview of iron homeostasis in M. tuberculosis that is discussed in the context of mycobactin biosynthesis, transport of iron across the mycobacterial cell envelope, and storage of excess iron. The clinical significance of the serum iron status and the expression of the iron-regulated protein HupB in tuberculosis (TB) patients is presented here, highlighting the potential of HupB as a marker, notably in extrapulmonary TB cases. PMID:27402628

  19. Validation of a capillary electrophoresis method for the enantiomeric purity testing of ropivacaine, a new local anaesthetic compound

    NARCIS (Netherlands)

    Sänger-Van De Griend, C. E.; Gröningsson, K.

    A capillary electrophoresis method for the determination of the enantiomeric purity of ropivacaine, a new local anaesthetic compound developed by Astra Pain Control AB, has been validated. The method showed the required limit of quantitation of 0.1%, enantiomeric impurity and proved to be robust.

  20. Production of the catechol type siderophore bacillibactin by the honey bee pathogen Paenibacillus larvae.

    Science.gov (United States)

    Hertlein, Gillian; Müller, Sebastian; Garcia-Gonzalez, Eva; Poppinga, Lena; Süssmuth, Roderich D; Genersch, Elke

    2014-01-01

    The Gram-positive bacterium Paenibacillus larvae is the etiological agent of American Foulbrood. This bacterial infection of honey bee brood is a notifiable epizootic posing a serious threat to global honey bee health because not only individual larvae but also entire colonies succumb to the disease. In the recent past considerable progress has been made in elucidating molecular aspects of host pathogen interactions during pathogenesis of P. larvae infections. Especially the sequencing and annotation of the complete genome of P. larvae was a major step forward and revealed the existence of several giant gene clusters coding for non-ribosomal peptide synthetases which might act as putative virulence factors. We here present the detailed analysis of one of these clusters which we demonstrated to be responsible for the biosynthesis of bacillibactin, a P. larvae siderophore. We first established culture conditions allowing the growth of P. larvae under iron-limited conditions and triggering siderophore production by P. larvae. Using a gene disruption strategy we linked siderophore production to the expression of an uninterrupted bacillibactin gene cluster. In silico analysis predicted the structure of a trimeric trithreonyl lactone (DHB-Gly-Thr)3 similar to the structure of bacillibactin produced by several Bacillus species. Mass spectrometric analysis unambiguously confirmed that the siderophore produced by P. larvae is identical to bacillibactin. Exposure bioassays demonstrated that P. larvae bacillibactin is not required for full virulence of P. larvae in laboratory exposure bioassays. This observation is consistent with results obtained for bacillibactin in other pathogenic bacteria.

  1. Structure and Function of the PiuA and PirA Siderophore-Drug Receptors from Pseudomonas aeruginosa and Acinetobacter baumannii.

    Science.gov (United States)

    Moynié, Lucile; Luscher, Alexandre; Rolo, Dora; Pletzer, Daniel; Tortajada, Antoni; Weingart, Helge; Braun, Yvonne; Page, Malcolm G P; Naismith, James H; Köhler, Thilo

    2017-04-01

    The outer membrane of Gram-negative bacteria presents an efficient barrier to the permeation of antimicrobial molecules. One strategy pursued to circumvent this obstacle is to hijack transport systems for essential nutrients, such as iron. BAL30072 and MC-1 are two monobactams conjugated to a dihydroxypyridone siderophore that are active against Pseudomonas aeruginosa and Acinetobacter baumannii Here, we investigated the mechanism of action of these molecules in A. baumannii We identified two novel TonB-dependent receptors, termed Ab -PiuA and Ab -PirA, that are required for the antimicrobial activity of both agents. Deletion of either piuA or pirA in A. baumannii resulted in 4- to 8-fold-decreased susceptibility, while their overexpression in the heterologous host P. aeruginosa increased susceptibility to the two siderophore-drug conjugates by 4- to 32-fold. The crystal structures of PiuA and PirA from A. baumannii and their orthologues from P. aeruginosa were determined. The structures revealed similar architectures; however, structural differences between PirA and PiuA point to potential differences between their cognate siderophore ligands. Spontaneous mutants, selected upon exposure to BAL30072, harbored frameshift mutations in either the ExbD3 or the TonB3 protein of A. baumannii , forming the cytoplasmic-membrane complex providing the energy for the siderophore translocation process. The results of this study provide insight for the rational design of novel siderophore-drug conjugates against problematic Gram-negative pathogens. Copyright © 2017 American Society for Microbiology.

  2. The Aspergillus fumigatus siderophore biosynthetic gene sidA, encoding L-ornithine N5-oxygenase, is required for virulence.

    Science.gov (United States)

    Hissen, Anna H T; Wan, Adrian N C; Warwas, Mark L; Pinto, Linda J; Moore, Margo M

    2005-09-01

    Aspergillus fumigatus is the leading cause of invasive mold infection and is a serious problem in immunocompromised populations worldwide. We have previously shown that survival of A. fumigatus in serum may be related to secretion of siderophores. In this study, we identified and characterized the sidA gene of A. fumigatus, which encodes l-ornithine N(5)-oxygenase, the first committed step in hydroxamate siderophore biosynthesis. A. fumigatus sidA codes for a protein of 501 amino acids with significant homology to other fungal l-ornithine N(5)-oxygenases. A stable DeltasidA strain was created by deletion of A. fumigatus sidA. This strain was unable to synthesize the siderophores N',N",N'''-triacetylfusarinine C (TAF) and ferricrocin. Growth of the DeltasidA strain was the same as that of the wild type in rich media; however, the DeltasidA strain was unable to grow in low-iron defined media or media containing 10% human serum unless supplemented with TAF or ferricrocin. No significant differences in ferric reduction activities were observed between the parental strain and the DeltasidA strain, indicating that blocking siderophore secretion did not result in upregulation of this pathway. Unlike the parental strain, the DeltasidA strain was unable to remove iron from human transferrin. A rescued strain (DeltasidA + sidA) was constructed; it produced siderophores and had the same growth as the wild type on iron-limited media. Unlike the wild-type and rescued strains, the DeltasidA strain was avirulent in a mouse model of invasive aspergillosis, indicating that sidA is necessary for A. fumigatus virulence.

  3. Synthesis of prostanoids; enantiomeric purity of alcohols by a 31P NMR technique

    International Nuclear Information System (INIS)

    Penning, T.D.

    1985-01-01

    The enone, 2,2-diemthyl-3aβ, 6aβ-dihydro-4H-cyclopenta-1,3-dioxol-4-one, has been synthesized in six steps from cyclopentadiene, resolved using sulfoximine chemistry, and converted into (-)-prostaglandin E 2 methyl ester in three steps. Introduction of the optically pure omega side-chain using a conjugate addition of a stabilized organocopper reagent, followed by direct alkylation of the enolate with the α side-chain allylic iodide in the presence of hexamethylphosphoramide, afforded a trans, vicinally disubstituted cyclopentanone. Deprotection of the C-15 alcohol, followed by aluminum amalgam reduction of the C-10/oxygen bond, provided (-)-PGE 2 methyl ester in 47% overall yield from the enone. In an extension of previously described work, 2-chloro-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholidine 2-sulfide, prepared from l-ephedrine and thiophosphoryl chloride, was used to determine the enantiomeric excess of chiral alcohols in conjunction with 31 P NMR. Chiral primary and secondary alcohols added quantitatively to the phospholidine to give diastereomers which could be analyzed by 31 P NMR and HPLC. A number of other phosphorus heterocycles were also explored as potential chiral derivatizing reagents

  4. Unsaturated macrocyclic dihydroxamic acid siderophores produced by Shewanella putrefaciens using precursor-directed biosynthesis.

    Science.gov (United States)

    Soe, Cho Z; Codd, Rachel

    2014-04-18

    To acquire iron essential for growth, the bacterium Shewanella putrefaciens produces the macrocyclic dihydroxamic acid putrebactin (pbH2; [M + H(+)](+), m/zcalc 373.2) as its native siderophore. The assembly of pbH2 requires endogenous 1,4-diaminobutane (DB), which is produced from the ornithine decarboxylase (ODC)-catalyzed decarboxylation of l-ornithine. In this work, levels of endogenous DB were attenuated in S. putrefaciens cultures by augmenting the medium with the ODC inhibitor 1,4-diamino-2-butanone (DBO). The presence in the medium of DBO together with alternative exogenous non-native diamine substrates, (15)N2-1,4-diaminobutane ((15)N2-DB) or 1,4-diamino-2(E)-butene (E-DBE), resulted in the respective biosynthesis of (15)N-labeled pbH2 ((15)N4-pbH2; [M + H(+)](+), m/zcalc 377.2, m/zobs 377.2) or the unsaturated pbH2 variant, named here: E,E-putrebactene (E,E-pbeH2; [M + H(+)](+), m/zcalc 369.2, m/zobs 369.2). In the latter system, remaining endogenous DB resulted in the parallel biosynthesis of the monounsaturated DB-E-DBE hybrid, E-putrebactene (E-pbxH2; [M + H(+)](+), m/zcalc 371.2, m/zobs 371.2). These are the first identified unsaturated macrocyclic dihydroxamic acid siderophores. LC-MS measurements showed 1:1 complexes formed between Fe(III) and pbH2 ([Fe(pb)](+); [M](+), m/zcalc 426.1, m/zobs 426.2), (15)N4-pbH2 ([Fe((15)N4-pb)](+); [M](+), m/zcalc 430.1, m/zobs 430.1), E,E-pbeH2 ([Fe(E,E-pbe)](+); [M](+), m/zcalc 422.1, m/zobs 422.0), or E-pbxH2 ([Fe(E-pbx)](+); [M](+), m/zcalc 424.1, m/zobs 424.2). The order of the gain in siderophore-mediated Fe(III) solubility, as defined by the difference in retention time between the free ligand and the Fe(III)-loaded complex, was pbH2 (ΔtR = 8.77 min) > E-pbxH2 (ΔtR = 6.95 min) > E,E-pbeH2 (ΔtR = 6.16 min), which suggests one possible reason why nature has selected for saturated rather than unsaturated siderophores as Fe(III) solubilization agents. The potential to conduct multiple types of ex situ chemical

  5. Synthesis of enantiomerically enriched drug precursors and an insect pheromone via reduction of ketones using commercially available carbonyl reductase screening kit "Chiralscreen® OH".

    Science.gov (United States)

    Nagai, Toshiya; Sakurai, Saki; Natori, Naoki; Hataoka, Manaka; Kinoshita, Takako; Inoue, Hiroyoshi; Hanaya, Kengo; Shoji, Mitsuru; Sugai, Takeshi

    2018-04-01

    Commercially available "Chiralscreen® OH" starter kit containing five types of carbonyl reductases (E001, E007, E031, E039, and E078) was used for the reduction of several aromatic and aliphatic ketones to obtain enantiomerically enriched drug precursors and an insect pheromone. Almost stereochemically pure secondary alcohols, used in the synthesis of drugs such as (R)-rasagiline mesylate, (S)-rivastigmine, (R)-chlorphenesin carbamate, and (R)-mexiletine, and the insect pheromone (4S,5R)-sitophilure, were conveniently obtained. The enzymes worked well with ketones containing at least one non-bulky substituent at the carbonyl group. The diverse stereochemical preference of the above five carbonyl reductases was clarified. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Use of a macrocyclic antibiotic as the chiral selector for enantiomeric separations by TLC

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, D.W.; Zhou, Y. (Univ. of Missouri, Rolla, MO (United States). Dept. of Chemistry)

    1994-01-01

    The macrocyclic antibiotic, vancomycin, was used as a chiral mobile phase additive for the thin layer chromatographic (TLC) resolution of 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatized amino acids, racemic drugs and dansyl-amino acids. Excellent separations were achieved for most of these compounds in the reversed phase mode. Both the nature of the stationary phase and the composition of the mobile phase strongly influenced enantiomeric resolution. The best results were obtained using diphenyl stationary phases. Acetonitrile was the organic modifier that produced the most effective separations with the shortest development times. It is highly likely that macrocyclic antibiotics will play a major role in future enantiomeric separations.

  7. Stereoselectivity in the salt-cocrystal products formed by phenylglycinol or phenylglycine with their respective sodium or hydrochloride salts.

    Science.gov (United States)

    Brittain, Harry G

    2013-01-01

    The salt and stereoselective cocrystal phenomena associated with 2-phenylglycinol and 2-phenylglycine have been studied using X-ray powder diffraction and differential scanning calorimetry. The chiral identities of the free acids and their sodium salts, or the free bases and their chloride salts, were found to play a determining role as to whether a salt-cocrystal product could or could not be formed. In particular, when cocrystallization of an enantiomerically pure basic or zwitterionic substance with its enantiomerically pure acid addition salt was attempted, a salt-cocrystal was only obtained when the absolute configuration of the two reactants is opposite. On the other hand, it has been found that no stereoselectivity in salt-cocrystal formation existed in the cocrystallization of an enantiomerically pure acidic or zwitterionic substance with its enantiomerically pure base addition salt. Copyright © 2012 Wiley Periodicals, Inc.

  8. Enantiomeric profiling of chiral illicit drugs in a pan-European study

    NARCIS (Netherlands)

    Castrignanò, E.; Yang, Z.; Bade, R.; Baz-Lomba, J.A.; Castiglioni, S.; Causanilles, A.; Covaci, A.; Gracia-Lor, E.; Hernández, F.; Kinyua, J.; McCall, A.-K.; van Nuijs, A.L.N.; Ort, C.; Plósz, B.G.; Ramin, P.; Rousis, N.I.; Ryu, Y.; Thomas, K.V.; de Voogt, P.; Zuccato, E.; Kasprzyk-Hordern, B.

    2018-01-01

    The aim of this paper is to present the first study on spatial and temporal variation in the enantiomeric profile of chiral drugs in eight European cities. Wastewater-based epidemiology (WBE) and enantioselective analysis were combined to evaluate trends in illicit drug use in the context of their

  9. Genetic diversity of siderophore-producing bacteria of tobacco rhizosphere Diversidade genética de bactérias de rizosfera de tabaco produtoras de sideróforos

    OpenAIRE

    Fang Tian; Yanqin Ding; Hui Zhu; Liangtong Yao; Binghai Du

    2009-01-01

    The genetic diversity of siderophore-producing bacteria of tobacco rhizosphere was studied by amplified ribosomal DNA restriction analysis (ARDRA), 16S rRNA sequence homology and phylogenetics analysis methods. Studies demonstrated that 85% of the total 354 isolates produced siderophores in iron limited liquid medium. A total of 28 ARDRA patterns were identified among the 299 siderophore-producing bacterial isolates. The 28 ARDRA patterns represented bacteria of 14 different genera belonging ...

  10. Preclinical evaluation of two 68Ga-siderophores as potential radiopharmaceuticals for Aspergillus fumigatus infection imaging

    International Nuclear Information System (INIS)

    Petrik, Milos; Franssen, Gerben M.; Laverman, Peter; Haas, Hubertus; Schrettl, Markus; Hoertnagl, Caroline; Lass-Floerl, Cornelia; Helbok, Anna; Decristoforo, Clemens

    2012-01-01

    Invasive pulmonary aspergillosis is mainly caused by Aspergillus fumigatus, and is one of the major causes of morbidity and mortality in immunocompromised patients. The mortality associated with invasive pulmonary aspergillosis remains high, mainly due to the difficulties and limitations in diagnosis. We have shown that siderophores can be labelled with 68 Ga and can be used for PET imaging of A. fumigatus infection in rats. Here we report on the further evaluation of the most promising 68 Ga-siderophore candidates, triacetylfusarinine (TAFC) and ferrioxamine E (FOXE). Siderophores were labelled with 68 Ga using acetate buffer. Log P, protein binding and stability values were determined. Uptake by A. fumigatus was studied in vitro in cultures with high and low iron loads. In vivo biodistribution was determined in normal mice and an infection model was established using neutropenic rats inoculated with A. fumigatus. Static and dynamic μPET imaging was performed and correlated with CT images, and lung infection was evaluated ex vivo. 68 Ga-siderophores were labelled with high radiochemical purity and specific activity. 68 Ga-TAFC and 68 Ga-FOXE showed high uptake by A. fumigatus in iron-deficient cultures. In normal mice, 68 Ga-TAFC and 68 Ga-FOXE showed rapid renal excretion with high metabolic stability. In the rat infection model focal lung uptake was detected by μPET with both compounds and increased with severity of the infection, correlating with abnormal CT images. 68 Ga-TAFC and 68 Ga-FOXE displayed excellent in vitro stability and high uptake by A. fumigatus. Both compounds showed excellent pharmacokinetics, highly selective accumulation in infected lung tissue and good correlation with severity of disease in a rat infection model, which makes them promising agents for A. fumigatus infection imaging. (orig.)

  11. Plant growth enhancing effects by a siderophore-producing endophytic streptomycete isolated from a Thai jasmine rice plant (Oryza sativa L. cv. KDML105).

    Science.gov (United States)

    Rungin, Siriwan; Indananda, Chantra; Suttiviriya, Pavinee; Kruasuwan, Worarat; Jaemsaeng, Ratchaniwan; Thamchaipenet, Arinthip

    2012-10-01

    An endophytic Streptomyces sp. GMKU 3100 isolated from roots of a Thai jasmine rice plant (Oryza sativa L. cv. KDML105) showed the highest siderophore production on CAS agar while phosphate solubilization and IAA production were not detected. A mutant of Streptomyces sp. GMKU 3100 deficient in just one of the plant growth promoting traits, siderophore production, was generated by inactivation of a desD-like gene encoding a key enzyme controlling the final step of siderophore biosynthesis. Pot culture experiments revealed that rice and mungbean plants inoculated with the wild type gave the best enhancement of plant growth and significantly increased root and shoot biomass and lengths compared with untreated controls and siderophore-deficient mutant treatments. Application of the wild type in the presence or absence of ferric citrate significantly promoted plant growth of both plants. The siderophore-deficient mutant clearly showed the effect of this important trait involved in plant-microbe interaction in enhancement of growth in rice and mungbean plants supplied with sequestered iron. Our results highlight the value of a substantial understanding of the relationship of the plant growth promoting properties of endophytic actinomycetes to the plants. Endophytic actinomycetes, therefore, can be applied as potentially safe and environmentally friendly biofertilizers in agriculture.

  12. Enantiomeric separation of iridium (III) complexes using HPLC chiral stationary phases based on amylose derivatives

    International Nuclear Information System (INIS)

    Kim, Hee Eun; Seo, Na Hyeon; Hyun, Myung Ho

    2016-01-01

    Cyclometalated iridium (III) complexes formed with three identical cyclometalating (C-N) ligands (homoleptic) or formed with two cyclometalating (C-N) ligands and one ancillary (LX) ligand (heteroleptic) have been known as highly phosphorescent materials and, thus, they have been utilized as efficient phosphorescent dopants in organic light emitting diodes (OLEDs) 1–3 or as effective phosphorescent chemosensors. 4–7 Cylometalated iridium (III) complexes are chiral compounds consisting of lambda (Λ, left-handed) and delta (Δ, right-handed) isomers. Racemic cyclometa- lated iridium (III) complexes emit light with no net polarization, but optically active cyclometalated iridium (III) complexes emit circularly polarized light. 8,9 Circularly polarized light can be used in various fields including highly efficient three dimensional electronic devices, photo nic devices for optical data storage, biological assays, and others. 8,9 In order to obtain optically active cylometalated iridium (III) complexes and to determine the enantiomeric composition of optically active cylometalated iridium (III) complexes, liquid chromatogr aphic enantiomer separation method on chiral stationary phases (CSPs) has been used. For example, Okamoto and coworkers first reported the high performance liquid chromatographic (HPLC) direct enantiomeric separation of two homoleptic cylometalated iridium (III) complexes on immobilized amylose tris(3,5- dimethylphenylcarbamate) (Chiralpak IA), coated cellulose tris(3,5-dimethylphenylcarbamate) (Chiralc el OD), and coated cellulose tris(4-methylbenzoate) (Chiralce l OJ). 10 Supercritical fluid chromatography (SFC) was also used by Bernhard and coworkers for the enantiomeric separation of cylometalated iridium (III) complexes on coated amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H). 8 However, the general use of the HPLC method for the direct enantiomeric separation of homoleptic

  13. Enantiomeric separation of iridium (III) complexes using HPLC chiral stationary phases based on amylose derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hee Eun; Seo, Na Hyeon; Hyun, Myung Ho [Dept. of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan (Korea, Republic of)

    2016-12-15

    Cyclometalated iridium (III) complexes formed with three identical cyclometalating (C-N) ligands (homoleptic) or formed with two cyclometalating (C-N) ligands and one ancillary (LX) ligand (heteroleptic) have been known as highly phosphorescent materials and, thus, they have been utilized as efficient phosphorescent dopants in organic light emitting diodes (OLEDs) 1–3 or as effective phosphorescent chemosensors. 4–7 Cylometalated iridium (III) complexes are chiral compounds consisting of lambda (Λ, left-handed) and delta (Δ, right-handed) isomers. Racemic cyclometa- lated iridium (III) complexes emit light with no net polarization, but optically active cyclometalated iridium (III) complexes emit circularly polarized light. 8,9 Circularly polarized light can be used in various fields including highly efficient three dimensional electronic devices, photo nic devices for optical data storage, biological assays, and others. 8,9 In order to obtain optically active cylometalated iridium (III) complexes and to determine the enantiomeric composition of optically active cylometalated iridium (III) complexes, liquid chromatogr aphic enantiomer separation method on chiral stationary phases (CSPs) has been used. For example, Okamoto and coworkers first reported the high performance liquid chromatographic (HPLC) direct enantiomeric separation of two homoleptic cylometalated iridium (III) complexes on immobilized amylose tris(3,5- dimethylphenylcarbamate) (Chiralpak IA), coated cellulose tris(3,5-dimethylphenylcarbamate) (Chiralc el OD), and coated cellulose tris(4-methylbenzoate) (Chiralce l OJ). 10 Supercritical fluid chromatography (SFC) was also used by Bernhard and coworkers for the enantiomeric separation of cylometalated iridium (III) complexes on coated amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H). 8 However, the general use of the HPLC method for the direct enantiomeric separation of homoleptic.

  14. Vicinal Diboronates in High Enantiomeric Purity through Tandem Site-Selective NHC–Cu-Catalyzed Boron-Copper Additions to Terminal Alkynes

    Science.gov (United States)

    Lee, Yunmi; Jang, Hwanjong; Hoveyda, Amir H.

    2009-01-01

    A Cu-catalyzed protocol for conversion of terminal alkynes to enantiomerically enriched diboronates is reported. In a single vessel, a site-selective hydroboration of an alkyne leads to the corresponding terminal vinylboronate, which undergoes a second site-selective and enantioselective hydroboration. Reactions proceed in the presence of two equivalents of commercially available bis(pinacolato)diboron [B2(pin)2] and 5–7.5 mol % of a chiral bidentate imidazolinium salt, affording diboronates in 60–93% yield and up to 97.5:2.5 enantiomeric ratio (er). The enantiomerically enriched products can be functionalized to afford an assortment of versatile organic molecules. Enynes are converted to unsaturated diboronates with high chemo- (>98% reaction of alkyne; <2% at alkene) and enantioselectivity (e.g., 94.5:5.5 er). PMID:19968273

  15. Characterization of siderophore produced by Pseudomonas syringae BAF.1 and its inhibitory effects on spore germination and mycelium morphology of Fusarium oxysporum.

    Science.gov (United States)

    Yu, Sumei; Teng, Chunying; Liang, Jinsong; Song, Tao; Dong, Liying; Bai, Xin; Jin, Yu; Qu, Juanjuan

    2017-11-01

    In this study, an antagonistic bacterium against Fusarium oxysporum was identified and designated as Pseudomonas syringae strain BAF.1 on the basis of 16S rDNA sequence analysis and physiological-biochemical characteristics. It produced catechol-species siderophore at a molecular weight of 488.59 Da and a maximum amount of 55.27 μg/ml with glucose as a carbon source and asparagine as a nitrogen source at a C/N ratio of 10:1, 30°C and pH 7. The siderophore exhibited prominent antagonistic activity against Fusarium oxysporum with a maximum inhibition rate of 95.24% and had also suppressive effects on other kinds of 11 phytopathogenic fungi in the absence of FeCl 3 ·6H 2 O. Spore germination was completely inhibited by 50 μl of the siderophorecontaining solution, and the ultrastructures of mycelia and spores were also considerably suppressed by siderophore treatment as established by electron microscopy observation. These results indicate that the siderophore produced by Pseudomonas syringae BAF.1 could be potentially used for biocontrol of pathogenic Fusarium oxysporum.

  16. Radioactive and stable metal bioaccumulation, crystalline compound and siderophore detection in Clavariadelphus truncatus

    International Nuclear Information System (INIS)

    Gaso, M.I.; Segovia, N.; Morton, O.; Lopez, J.L.; Machuca, A.; Hernandez, E.

    2007-01-01

    137 Cs and 40 K activity concentrations and stable elements have been measured in Clavariadelphus truncatus collected in Mexico. Iron-chelating compounds of siderophore-type was also studied in the species. 137 Cs and 40 K were determined in soil and mushroom samples with HpGe gamma-ray spectrometry. Macro- and micro-elemental concentrations were determined by XRF and ICP-MS. Siderophore detection was obtained with a colorimetric assay and X-ray diffraction analysis was performed using a Siemens D5000 diffractometer. 137 Cs geometric mean concentration in C. truncatus was 26 times higher as compared with other Mexican edible mushroom species, while 40 K showed stability. Soil-C. truncatus concentration ratio for 137 Cs and other micro-elements such as Cs, Rb and Pb were also higher than other Mexican edible species. The 137 Cs committed effective dose due to the ingestion of C. truncatus was 8 x 10 -6 Sv year -1 . The main crystalline structure found in C. truncatus was D-Mannitol

  17. Siderophore biosynthesis coordinately modulated the virulence-associated interactive metabolome of uropathogenic Escherichia coli and human urine.

    Science.gov (United States)

    Su, Qiao; Guan, Tianbing; Lv, Haitao

    2016-04-14

    Uropathogenic Escherichia coli (UPEC) growth in women's bladders during urinary tract infection (UTI) incurs substantial chemical exchange, termed the "interactive metabolome", which primarily accounts for the metabolic costs (utilized metabolome) and metabolic donations (excreted metabolome) between UPEC and human urine. Here, we attempted to identify the individualized interactive metabolome between UPEC and human urine. We were able to distinguish UPEC from non-UPEC by employing a combination of metabolomics and genetics. Our results revealed that the interactive metabolome between UPEC and human urine was markedly different from that between non-UPEC and human urine, and that UPEC triggered much stronger perturbations in the interactive metabolome in human urine. Furthermore, siderophore biosynthesis coordinately modulated the individualized interactive metabolome, which we found to be a critical component of UPEC virulence. The individualized virulence-associated interactive metabolome contained 31 different metabolites and 17 central metabolic pathways that were annotated to host these different metabolites, including energetic metabolism, amino acid metabolism, and gut microbe metabolism. Changes in the activities of these pathways mechanistically pinpointed the virulent capability of siderophore biosynthesis. Together, our findings provide novel insights into UPEC virulence, and we propose that siderophores are potential targets for further discovery of drugs to treat UPEC-induced UTI.

  18. Crystallization and X-ray diffraction analysis of salicylate synthase, a chorismate-utilizing enyme involved in siderophore biosynthesis

    International Nuclear Information System (INIS)

    Parsons, James F.; Shi, Katherine; Calabrese, Kelly; Ladner, Jane E.

    2006-01-01

    Salicylate synthase, which catalyzes the first step in the synthesis of the siderophore yersiniabactin, has been crystallized. Diffraction data have been collected to 2.5 Å. Bacteria have evolved elaborate schemes that help them thrive in environments where free iron is severely limited. Siderophores such as yersiniabactin are small iron-scavenging molecules that are deployed by bacteria during iron starvation. Several studies have linked siderophore production and virulence. Yersiniabactin, produced by several Enterobacteriaceae, is derived from the key metabolic intermediate chorismic acid via its conversion to salicylate by salicylate synthase. Crystals of salicylate synthase from the uropathogen Escherichia coli CFT073 have been grown by vapour diffusion using polyethylene glycol as the precipitant. The monoclinic (P2 1 ) crystals diffract to 2.5 Å. The unit-cell parameters are a = 57.27, b = 164.07, c = 59.04 Å, β = 108.8°. The solvent content of the crystals is 54% and there are two molecules of the 434-amino-acid protein in the asymmetric unit. It is anticipated that the structure will reveal key details about the reaction mechanism and the evolution of salicylate synthase

  19. Crystallization and X-ray diffraction analysis of salicylate synthase, a chorismate-utilizing enyme involved in siderophore biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, James F., E-mail: parsonsj@umbi.umd.edu; Shi, Katherine; Calabrese, Kelly [Center for Advanced Research in Biotechnology, The University of Maryland Biotechnology Institute, 9600 Gudelsky Drive, Rockville, MD 20850 (United States); Ladner, Jane E. [Center for Advanced Research in Biotechnology, The University of Maryland Biotechnology Institute, 9600 Gudelsky Drive, Rockville, MD 20850 (United States); National Institute of Standards and Technology (United States)

    2006-03-01

    Salicylate synthase, which catalyzes the first step in the synthesis of the siderophore yersiniabactin, has been crystallized. Diffraction data have been collected to 2.5 Å. Bacteria have evolved elaborate schemes that help them thrive in environments where free iron is severely limited. Siderophores such as yersiniabactin are small iron-scavenging molecules that are deployed by bacteria during iron starvation. Several studies have linked siderophore production and virulence. Yersiniabactin, produced by several Enterobacteriaceae, is derived from the key metabolic intermediate chorismic acid via its conversion to salicylate by salicylate synthase. Crystals of salicylate synthase from the uropathogen Escherichia coli CFT073 have been grown by vapour diffusion using polyethylene glycol as the precipitant. The monoclinic (P2{sub 1}) crystals diffract to 2.5 Å. The unit-cell parameters are a = 57.27, b = 164.07, c = 59.04 Å, β = 108.8°. The solvent content of the crystals is 54% and there are two molecules of the 434-amino-acid protein in the asymmetric unit. It is anticipated that the structure will reveal key details about the reaction mechanism and the evolution of salicylate synthase.

  20. Siderophore-mediated iron dissolution from nontronites is controlled by mineral cristallochemistry

    Directory of Open Access Journals (Sweden)

    Damien eParrello

    2016-03-01

    Full Text Available Bacteria living in oxic environments experience iron deficiency due to limited solubility and slow dissolution kinetics of iron-bearing minerals. To cope with iron deprivation, aerobic bacteria have evolved various strategies, including release of siderophores or other organic acids that scavenge external Fe(III and deliver it to the cells. This research investigated the role of siderophores produced by Pseudomonas aeruginosa in the acquisition of Fe(III from two iron-bearing colloidal nontronites (NAu-1 and NAu-2, comparing differences in bioavailability related with site occupancy and distribution of Fe(III in the two lattices. To avoid both the direct contact of the mineral colloids with the bacterial cells and the uncontrolled particle aggregation, nontronite suspensions were homogenously dispersed in a porous silica gel before the dissolution experiments. A multiparametric approach coupling UV-vis spectroscopy and spectral decomposition algorithm was implemented to monitor simultaneously the solubilisation of Fe and the production of pyoverdine in microplate-based batch experiments. Both nontronites released Fe in a particle concentration-dependent manner when incubated with the wild-type P. aeruginosa strain, however iron released from NAu-2 was substantially greater than from NAu-1. The profile of organic acids produced in both cases was similar and may not account for the difference in the iron dissolution efficiency. In contrast, a pyoverdine-deficient mutant was unable to mobilise Fe(III from either nontronite, whereas iron dissolution occurred in abiotic experiments conducted with purified pyoverdine. Overall, our data provide evidence that P. aeruginosa indirectly mobilise Fe from nontronites primarily through the production of pyoverdine. The structural Fe present on the edges of Nau-2 rather than Nau-1 particles appears to be more bio-accessible, indicating that the distribution of Fe, in the tetrahedron and/or in the octahedron

  1. Vesicles to concentrate iron in low-Iron media: An attempt to mimic marine siderophores

    Czech Academy of Sciences Publication Activity Database

    Bednárová, Lucie; Brandel, J.; d'Hardemare, A. d. M.; Bednár, J.; Serratrice, G.; Pierre, J. L.

    2008-01-01

    Roč. 14, č. 12 (2008), s. 3680-3686 ISSN 0947-6539 Institutional research plan: CEZ:AV0Z40550506 Keywords : iron * marine siderophore mimics * micelles * self-assembly * vesicles Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.454, year: 2008

  2. Anisotropy Spectra for Enantiomeric Differentiation of Biomolecular Building Blocks

    DEFF Research Database (Denmark)

    Evans, Amanda C.; Meinert, Cornelia; Bredehoft, Jan H.

    2013-01-01

    All biopolymers are composed of homochiral building blocks, and both D-sugars and L-amino acids uniquely constitute life on Earth. These monomers were originally enantiomerically differentiated under prebiotic conditions. Particular progress has recently been made in support of the photochemical...... light. This chapter will: (1) present the theory and configuration of anisotropy spectroscopy; (2) explain experimentally recorded anisotropy spectra of selected chiral biomolecules such as amino acids; and (3) discuss the relevance of these spectra for the investigation of the origin of the molecular...

  3. [Studies on origin of illicit methamphetamine. I. The relationship of enantiomeric compositions between methamphetamine and its raw material (ephedrine)].

    Science.gov (United States)

    Kikura, R; Shimamine, M; Nakahara, Y; Terao, T

    1992-01-01

    In order to elucidate the relationship of enantiomeric compositions between methamphetamine (MA) and its raw materials, ephedrine (EP) enantiomers, commercial EP samples and MA samples prepared from them were analyzed by HPLC using GITC-prelabeling. The GITC derivatives were separated on ODS column using methanol-water-acetic acid (45:54:1) at a flow rate of 1.2 ml/min for EP and tetrahydrofuran-water-acetic acid (29:70:1) at a flow rate of 1 ml/min for MA. The chromatographic conditions resulted in such a good separation of four EP and two MA enantiomers that 1/1000 enantiomeric impurities could be detected and discriminated from the major enantiomer with good reproducibility. Moreover, it was demonstrated that the asymmetric center at alpha-position of amino group was entirely retained throughout the reductive reaction of the EP samples, and that the MA samples inherited the enantiomeric character from the EP samples used. This method was applied to discriminative analysis of MA samples seized in Japan.

  4. Radioactive and stable metal bioaccumulation, crystalline compound and siderophore detection in Clavariadelphus truncatus

    Energy Technology Data Exchange (ETDEWEB)

    Gaso, M.I. [ININ, Ap. Post. 18-1027, C.P. 11801, Mexico D.F. (Mexico)], E-mail: migp@nuclear.inin.mx; Segovia, N. [Instituto de Geofisica, UNAM, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico)], E-mail: nurina@terra.com.mx; Morton, O. [Instituto de Geofisica, UNAM, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico)], E-mail: omorton@geofisica.unam.mx; Lopez, J.L. [Instituto de Geografia, UNAM, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico)], E-mail: jlc@servidor.unam.mx; Machuca, A. [Departmento Forestal, Universidad de Concepcion, Los Angeles (Chile)], E-mail: angmachu@udec.cl; Hernandez, E. [Instituto de Geofisica, UNAM, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico)], E-mail: aeliza@geofisica.unam.mx

    2007-09-15

    {sup 137}Cs and {sup 40}K activity concentrations and stable elements have been measured in Clavariadelphus truncatus collected in Mexico. Iron-chelating compounds of siderophore-type was also studied in the species. {sup 137}Cs and {sup 40}K were determined in soil and mushroom samples with HpGe gamma-ray spectrometry. Macro- and micro-elemental concentrations were determined by XRF and ICP-MS. Siderophore detection was obtained with a colorimetric assay and X-ray diffraction analysis was performed using a Siemens D5000 diffractometer. {sup 137}Cs geometric mean concentration in C. truncatus was 26 times higher as compared with other Mexican edible mushroom species, while {sup 40}K showed stability. Soil-C. truncatus concentration ratio for {sup 137}Cs and other micro-elements such as Cs, Rb and Pb were also higher than other Mexican edible species. The {sup 137}Cs committed effective dose due to the ingestion of C. truncatus was 8 x 10{sup -6} Sv year{sup -1}. The main crystalline structure found in C. truncatus was D-Mannitol.

  5. The Asymmetry is Derived from Mechanical Interlocking of Achiral Axle and Achiral Ring Components –Syntheses and Properties of Optically Pure [2]Rotaxanes–

    Directory of Open Access Journals (Sweden)

    Keiji Hirose

    2018-01-01

    Full Text Available Rotaxanes consisting of achiral axle and achiral ring components can possess supramolecular chirality due to their unique geometrical architectures. To synthesize such chiral rotaxanes, we adapted a prerotaxane method based on aminolysis of a metacyclophane type prerotaxane that had planar chirality, which is composed of an achiral stopper unit and a crown ether type ring component. The prerotaxanes were well resolved using chiral HPLC into a pair of enantiomerically pure prerotaxanes, which were transferred into corresponding chiral rotaxanes, respectively. Obtained chiral rotaxanes were revealed to have considerable enantioselectivity.

  6. Phase associations and potential selective extraction methods for selected high-tech metals from ferromanganese nodules and crusts with siderophores

    International Nuclear Information System (INIS)

    Mohwinkel, Dennis; Kleint, Charlotte; Koschinsky, Andrea

    2014-01-01

    Highlights: • Phase associations of metals in marine Fe–Mn nodules and crusts were determined. • Selective leaching experiments with siderophore desferrioxamine B were conducted. • Siderophores selectively mobilize high-tech metals associated with Fe carrier phases. • Base metal liberation including Fe and Mn is limited. • Siderophores have promising potential for application in ore processing industries. - Abstract: Deep-sea ferromanganese deposits contain a wide range of economically important metals. Ferromanganese crusts and nodules represent an important future resource, since they not only contain base metals such as Mn, Ni, Co, Cu and Zn, but are also enriched in critical or rare high-technology elements such as Li, Mo, Nb, W, the rare earth elements and yttrium (REY). These metals could be extracted from nodules and crusts as a by-product to the base metal production. However, there are no proper separation techniques available that selectively extract certain metals out of the carrier phases. By sequential leaching, we demonstrated that, except for Li, which is present in an easily soluble form, all other high-tech metals enriched in ferromanganese nodules and crusts are largely associated with the Fe-oxyhydroxide phases and only to subordinate extents with Mn-oxide phases. Based on this fact, we conducted selective leaching experiments with the Fe-specific organic ligand desferrioxamine-B, a naturally occurring and ubiquitous siderophore. We showed by leaching of ferromanganese nodules and crusts with desferrioxamine-B that a significant and selective extraction of high-tech metals such as Li, Mo, Zr, Hf and Ta is possible, while other elements like Fe and the base metals Mn, Ni, Cu, Co and Zn are not extracted to large extents. The set of selectively extracted elements can be extended to Nb and W if Mn and carbonate phases are stripped from the bulk nodule or crust prior to the siderophore leach by e.g. a sequential leaching technique. This

  7. Homochiral Acyl Isocyanates as Diagnostic NMR Probes for the Enantiomeric Purity of Chiral Alcohols

    Directory of Open Access Journals (Sweden)

    Gregory H. P. Roos

    2000-12-01

    Full Text Available The first reported acyl and sulfonylisocyanates were developed and tested in reactions with chiral alcohols to afford diastereomeric carbamates. NMR analysis of these investigates the chemical shift discrimination that would allow these activated isocyanates to be used as diagnostic probes of enantiomeric purity.

  8. Chiral recognition and determination of enantiomeric excess by mass spectrometry: A review

    International Nuclear Information System (INIS)

    Yu, Xiangying; Yao, Zhong-Ping

    2017-01-01

    Chiral analysis is of great importance to fundamental and applied research in chemical, biological and pharmaceutical sciences. Due to the superiority of mass spectrometry (MS) over other analytical methods in terms of speed, specificity and sensitivity, chiral analysis by MS has attracted much interest in recent years. Chiral analysis by MS typically involves introduction of a chiral selector to form diastereomers with analyte enantiomers, and comparison of the behaviors of diastereomers in MS. Chiral differentiation can be achieved by comparing the relative abundances of diastereomers, the thermodynamic or kinetic constants of ion-molecule reactions of diastereomers in the gas phase, the dissociation of diastereomers in MS/MS, or the mobility of diastereomers in ion mobility mass spectrometry. In this review, chiral recognition and determination of enantiomeric excess by these chiral MS methods were summarized, and the prospects of chiral analysis by MS were discussed. - Highlights: • Both chiral recognition and determination of enantiomeric excess by mass spectrometry are systematically reviewed. • Classification is based on the behavioral differences of diastereomers formed between chiral analytes and chiral selectors. • Development of ion mobility mass spectrometry for chiral differentiation is covered. • Various methods are highlighted and compared.

  9. Chiral recognition and determination of enantiomeric excess by mass spectrometry: A review

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiangying [College of Pharmacy, Jinan University, Guangzhou 510632, Guangdong (China); State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation) and Shenzhen Key Laboratory of Food Biological Safety Control, Shenzhen Research Institute of Hong Kong Polytechnic University, Shenzhen 518057 (China); Yao, Zhong-Ping, E-mail: zhongping.yao@polyu.edu.hk [State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation) and Shenzhen Key Laboratory of Food Biological Safety Control, Shenzhen Research Institute of Hong Kong Polytechnic University, Shenzhen 518057 (China); Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules (Yanbian University), Ministry of Education, Yanji 133002, Jilin (China); State Key Laboratory of Chirosciences, Food Safety and Technology Research Centre and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region (China)

    2017-05-22

    Chiral analysis is of great importance to fundamental and applied research in chemical, biological and pharmaceutical sciences. Due to the superiority of mass spectrometry (MS) over other analytical methods in terms of speed, specificity and sensitivity, chiral analysis by MS has attracted much interest in recent years. Chiral analysis by MS typically involves introduction of a chiral selector to form diastereomers with analyte enantiomers, and comparison of the behaviors of diastereomers in MS. Chiral differentiation can be achieved by comparing the relative abundances of diastereomers, the thermodynamic or kinetic constants of ion-molecule reactions of diastereomers in the gas phase, the dissociation of diastereomers in MS/MS, or the mobility of diastereomers in ion mobility mass spectrometry. In this review, chiral recognition and determination of enantiomeric excess by these chiral MS methods were summarized, and the prospects of chiral analysis by MS were discussed. - Highlights: • Both chiral recognition and determination of enantiomeric excess by mass spectrometry are systematically reviewed. • Classification is based on the behavioral differences of diastereomers formed between chiral analytes and chiral selectors. • Development of ion mobility mass spectrometry for chiral differentiation is covered. • Various methods are highlighted and compared.

  10. Enantiomeric ratios as an indicator of exposure processes for persistent pollutants in human placentas

    DEFF Research Database (Denmark)

    Shen, Heqing; Virtanen, H E; Main, Katharina M

    2006-01-01

    The enantiomeric ratios (ER) of alpha-HCH and o,p'-DDT ((+)-isomer concentration/(-)-isomer concentration) and o,p'-DDD (first eluting enantiomer/second enantiomer) were investigated in 112 human placentas from Finnish boys collected 1997-2001. Both o,p'-DDD and alpha-HCH showed changes in their ER...

  11. Reversed-Phase UHPLC Enantiomeric Separation of Rasagiline Salts Using a Chiralpak® AGP Column

    Directory of Open Access Journals (Sweden)

    Nagarajan Balaji

    2017-07-01

    Full Text Available We report the first rapid ultra-high performance liquid chromatographic (UHPLC enantiomeric reversed-phase separation of rasagiline mesylate and its tartrate salts using a Chiralpak® AGP column (50 mm × 2.1 mm, 5 μm as a stationary phase. This method was developed as an alternative to the usage of previously reported normal-phase chiral LC columns for isomer separation. Our method is based on an isocratic approach using a mixture of ammonium acetate and isopropyl alcohol (90:10, v/v as the mobile phase (0.6 mL/min flow rate. The detection limit (at a detection wavelength of 210 nm and quantification limit for the rasagiline enantiomers were 0.06 and 0.2 μg/mL, respectively. This method is compatible with the UHPLC-MS technique. The successful separation of rasagiline and its enantiomer was confirmed by determining the corresponding specific optical rotation values. Our method will be applicable for detecting rasagiline enantiomers during the control of manufacturing processes, and for use in rapid analysis for quality control in pharmaceutical industry to obtain optically pure pharmaceutical substances. This method was validated in terms of its precision, limit of detection, limit of quantification, linearity, accuracy, robustness, ruggedness, specificity, forced degradation, and solution stability, according to International Council on Harmonization Validation Guidelines Q2 (R1.

  12. Siderophore-mediated oxidation of Ce and fractionation of HREE by Mn (hydr)oxide-coprecipitation and sorption on MnO2: Experimental evidence for negative Ce-anomalies in abiogenic manganese precipitates

    Science.gov (United States)

    Krämer, Dennis; Tepe, Nathalie; Bau, Michael

    2014-05-01

    We conducted experiments with Rare Earths and Yttrium (REY), where the REY were sorbed on synthetic manganese dioxide as well as on coprecipitating manganese (hydr)oxide in the presence and absence of the siderophore desferrioxamine-B (DFOB). Siderophores are a group of globally abundant biogenic complexing agents which are excreted by plants and bacteria to enhance the bioavailability of Fe in oxic environments. The model siderophore used in this study, DFOB, is a hydroxamate siderophore occurring in almost all environmental settings with concentrations in the nanomolar to millimolar range and is one of the most thoroughly studied siderophores. In the absence of siderophores and other organic ligands, trivalent Ce is usually surface-oxidized to tetravalent Ce during sorption onto manganese (hydr)oxides. Such Mn precipitates, therefore, often show positive Ce anomalies, whereas the ambient solutions exhibit negative Ce anomalies (Ohta and Kawabe, 2001). In marked contrast, however, REY sorption in the presence of DFOB produces negative Ce anomalies in the Mn precipitates and a distinct and characteristic positive Ce anomaly in the residual siderophore-bearing solution. Furthermore, the heavy REY with ionic radii larger than the radius of Sm are also almost completely prevented from sorption onto the Mn solid phases. Sorption of REY onto Mn (hydr)oxides in the presence of DFOB creates a distinct and pronounced fractionation of Ce and the heavy REY from the light and middle REY. Apart from Ce, which is oxidized in solution by the siderophore, the distribution of the other REY mimics the stability constants for multi-dentate complexes of REY with DFOB, as determined by Christenson & Schijf (2011). Heavier REY are forming stronger complexes (and are hence better "protected" from sorption) than light REY, excluding Ce. Preferential partitioning of Ce into the liquid phase during the precipitation of Mn (hydr)oxides has only rarely been described for natural Mn (hydr

  13. Stereocomplex micelle from nonlinear enantiomeric copolymers efficiently transports antineoplastic drug

    Science.gov (United States)

    Wang, Jixue; Shen, Kexin; Xu, Weiguo; Ding, Jianxun; Wang, Xiaoqing; Liu, Tongjun; Wang, Chunxi; Chen, Xuesi

    2015-05-01

    Nanoscale polymeric micelles have attracted more and more attention as a promising nanocarrier for controlled delivery of antineoplastic drugs. Herein, the doxorubicin (DOX)-loaded poly(D-lactide)-based micelle (PDM/DOX), poly(L-lactide)-based micelle (PLM/DOX), and stereocomplex micelle (SCM/DOX) from the equimolar mixture of the enantiomeric four-armed poly(ethylene glycol)-polylactide (PEG-PLA) copolymers were successfully fabricated. In phosphate-buffered saline (PBS) at pH 7.4, SCM/DOX exhibited the smallest hydrodynamic diameter ( D h) of 90 ± 4.2 nm and the slowest DOX release compared with PDM/DOX and PLM/DOX. Moreover, PDM/DOX, PLM/DOX, and SCM/DOX exhibited almost stable D hs of around 115, 105, and 90 nm at above normal physiological condition, respectively, which endowed them with great potential in controlled drug delivery. The intracellular DOX fluorescence intensity after the incubation with the laden micelles was different degrees weaker than that incubated with free DOX · HCl within 12 h, probably due to the slow DOX release from micelles. As the incubation time reached to 24 h, all the cells incubated with the laden micelles, especially SCM/DOX, demonstrated a stronger intracellular DOX fluorescence intensity than free DOX · HCl-cultured ones. More importantly, all the DOX-loaded micelles, especially SCM/DOX, exhibited potent antineoplastic efficacy in vitro, excellent serum albumin-tolerance stability, and satisfactory hemocompatibility. These encouraging data indicated that the loading micelles from nonlinear enantiomeric copolymers, especially SCM/DOX, might be promising in clinical systemic chemotherapy through intravenous injection.

  14. Synthesis of optically pure deuterium-labelled nicotine, nornicotine and cotinine

    International Nuclear Information System (INIS)

    Jacob, P. III; Benowitz, N.L.; Shulgin, A.T.; California Univ., San Francisco

    1988-01-01

    We describe methods for the synthesis of enantiomerically pure (S)-nicotine-3',3'-d 2 , (S)-nornicotine-3',3-d 2 , and (S)-cotinine-4',4'-d 2 . The key intermediate was 5-bromomyosmine, which underwent base catalyzed exchange with deuterium oxide to give 5-bromomyosmine-3',3'- d 2 with >99% incorporation of label. This intermediate was reduced to (±)-5-bromo-nornicotine-3',3'-d 2 with sodium borohydride, resolved, and converted to (S)-nornicotine-3',3'-d(sub)2 by reductive debromination with hydrogen and a palladium catalyst. Reductive alkylation with formaldehyde and sodium borohydride provided (S)-nicotine-3',3'-d 2 , which was converted to (S)-cotinine-4',4'-d 2 by reaction with bromine followed by zinc reduction. The deuterium label is located at positions that are not attacked in the major routes of mammalian metabolism of these alkaloids. Syntheses of tetradeuterated analogs of nicotine and cotinine and a pentadeuterated analog of nicotine, in which additional deuterium atoms are incorporated in the methyl groups, are also reported. (author)

  15. Enantiomeric profiling of a chemically diverse mixture of chiral pharmaceuticals in urban water

    International Nuclear Information System (INIS)

    Evans, S.; Bagnall, J.; Kasprzyk-Hordern, B.

    2017-01-01

    Due to concerns regarding the release of pharmaceuticals into the environment and the understudied impact of stereochemistry of pharmaceuticals on their fate and biological potency, we focussed in this paper on stereoselective transformation pathways of selected chiral pharmaceuticals (16 pairs) at both microcosm (receiving waters and activated sludge wastewater treatment simulating microcosms) and macrocosm (wastewater treatment plant (WWTP) utilising activated sludge technology and receiving waters) scales in order to test the hypothesis that biodegradation of chiral drugs is stereoselective. Our monitoring programme of a full scale activated sludge WWTP and receiving environment revealed that several chiral drugs, those being marketed mostly as racemates, are present in wastewater and receiving waters enriched with one enantiomeric form (e.g. fluoxetine, mirtazapine, salbutamol, MDMA). This is most likely due to biological metabolic processes occurring in humans and other organisms. Both activated sludge and receiving waters simulating microcosms confirmed our hypothesis that chiral drugs are subject to stereoselective microbial degradation. It led, in this research, to preferential degradation of S-(+)-enantiomers of amphetamines, R-(+)-enantiomers of beta-blockers and S-(+)-enantiomers of antidepressants. In the case of three parent compound – metabolite pairs (venlafaxine – desmethylvenlafaxine, citalopram – desmethylcitalopram and MDMA - MDA), while parent compounds showed higher resistance to both microbial metabolism and photodegradation, their desmethyl metabolites showed much higher degradation rate both in terms of stereoselective metabolic and non-stereoselective photochemical processes. It is also worth noting that metabolites tend to be, as expected, enriched with enantiomers of opposite configuration to their parent compounds, which might have significant toxicological consequences when evaluating the metabolic residues of chiral pollutants

  16. Positionally isomeric organic gelators: structure-gelation study, racemic versus enantiomeric gelators, and solvation effects.

    Science.gov (United States)

    Caplar, Vesna; Frkanec, Leo; Sijaković Vujicić, Natasa; Zinić, Mladen

    2010-03-08

    Low molecular weight gelator molecules consisting of aliphatic acid, amino acid (phenylglycine), and omega-aminoaliphatic acid units have been designed. By varying the number of methylene units in the aliphatic and omega-aminoaliphatic acid chains, as defined by descriptors m and n, respectively, a series of positionally isomeric gelators having different positions of the peptidic hydrogen-bonding unit within the gelator molecule has been obtained. The gelation properties of the positional isomers have been determined in relation to a defined set of twenty solvents of different structure and polarity and analyzed in terms of gelator versatility (G(ver)) and effectiveness (G(eff)). The results of gelation tests have shown that simple synthetic optimizations of a "lead gelator molecule" by variation of m and n, end-group polarity (carboxylic acid versus sodium carboxylate), and stereochemistry (racemate versus optically pure form) allowed the identification of gelators with tremendously improved versatility (G(ver)) and effectiveness (G(eff)). Dramatic differences in G(eff) values of up to 70 times could be observed between pure racemate/enantiomer pairs of some gelators, which were manifested even in the gelation of very similar solvents such as isomeric xylenes. The combined results of spectroscopic ((1)H NMR, FTIR), electron microscopy (TEM), and X-ray diffraction studies suggest similar organization of the positionally isomeric gelators at the molecular level, comprising parallel beta-sheet hydrogen-bonded primary assemblies that form inversed bilayers at a higher organizational level. Differential scanning calorimetry (DSC) studies of selected enantiomer/racemate gelator pairs and their o- and p-xylene gels revealed the simultaneous presence of different polymorphs in the racemate gels. The increased gelation effectiveness of the racemate compared to that of the single enantiomer is most likely a consequence of its spontaneous resolution into enantiomeric

  17. In Vitro and In Vivo Comparison of Selected Ga-68 and Zr-89 Labelled Siderophores

    Czech Academy of Sciences Publication Activity Database

    Petřík, M.; Zhai, C.; Nový, Z.; Urbánek, Lubor; Haas, H.; Decristoforo, C.

    2016-01-01

    Roč. 18, č. 3 (2016), s. 344-352 ISSN 1536-1632 R&D Projects: GA MŠk(CZ) LO1304; GA MŠk(CZ) LO1204; GA TA ČR(CZ) TE01020028 Institutional support: RVO:61389030 Keywords : Siderophores * Gallium-68 * Zirconium-89 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.466, year: 2016

  18. Enantiomeric metabolic interactions and stereoselective human methadone metabolism.

    Science.gov (United States)

    Totah, Rheem A; Allen, Kyle E; Sheffels, Pamela; Whittington, Dale; Kharasch, Evan D

    2007-04-01

    Methadone is administered as a racemate, although opioid activity resides in the R-enantiomer. Methadone disposition is stereoselective, with considerable unexplained variability in clearance and plasma R/S ratios. N-Demethylation of methadone in vitro is predominantly mediated by cytochrome P450 CYP3A4 and CYP2B6 and somewhat by CYP2C19. This investigation evaluated stereoselectivity, models, and kinetic parameters for methadone N-demethylation by recombinant CYP2B6, CYP3A4, and CYP2C19, and the potential for interactions between enantiomers during racemate metabolism. CYP2B6 metabolism was stereoselective. CYP2C19 was less active, and stereoselectivity was opposite that for CYP2B6. CYP3A4 was not stereoselective. With all three isoforms, enantiomer N-dealkylation rates in the racemate were lower than those of (R)-(6-dimethyamino-4,4-diphenyl-heptan-3-one) hydrochloride (R-methadone) or (S)-(6-dimethyamino-4,4-diphenyl-heptan-3-one) hydrochloride (S-methadone) alone, suggesting an enantiomeric interaction and mutual metabolic inhibition. For CYP2B6, the interaction between enantiomers was stereoselective, with S-methadone as a more potent inhibitor of R-methadone N-demethylation than R-of S-methadone. In contrast, enantiomer interactions were not stereoselective with CYP2C19 or CYP3A4. For all three cytochromes P450, methadone N-demethylation was best described by two-site enzyme models with competitive inhibition. There were minor model differences between cytochromes P450 to account for stereoselectivity of metabolism and enantiomeric interactions. Changes in plasma R/S methadone ratios observed after rifampin or troleandomycin pretreatment in humans in vivo were successfully predicted by CYP2B6- but not CYP3A4-catalyzed methadone N-demethylation. CYP2B6 is a predominant catalyst of stereoselective methadone metabolism in vitro. In vivo, CYP2B6 may be a major determinant of methadone metabolism and disposition, and CYP2B6 activity and stereoselective metabolic

  19. Synthesis of radiolabeled racemic and enantiomeric antiarrhythmic agents

    Energy Technology Data Exchange (ETDEWEB)

    Stolle, W.T.; Stelzer, L.S.; Hester, J.B.; Perricone, S.C.; Hsi, R.S.P. (Upjohn Co., Kalamazoo, MI (United States))

    1994-10-01

    Ibutilide fumarate, racemic N-[4-[4-(ethyl-n-heptylamino)-hydroxybutyl]phenyl]methanesulfonamide hemifumarate, and artilide, the R-(+)-enantiomer of N-[4-[4-(ethyl-n-heptylamino)-hydroxybutyl]phenyl]methanesulfonamide hemifumerate, are under clinical investigation as Class III antiarrhythmic agents. For conducting drug disposition studies, we synthesized carbon-14 labeled ibutilide, as well as its two enantiomeric forms. In addition, high specific activity tritium labeled ibutilide was also prepared to facilitate development of a radioimmunoassay and for studying receptor site characteristics of this agent. Results of metabolism studies with [[sup 14]C]ibutilide led us to prepare tritium labeled artilide, which is more readily accessible than the C-14 labeled drug. The optical antipode of artilide was also labeled with tritium for comparative drug disposition investigations on the two enantiomers. (author).

  20. Siderophores of Stenotrophomonas maltophilia: detection and determination of their chemical nature Sideróforos de Stenotrophomonas maltophilia: detección y determinación de su naturaleza química

    Directory of Open Access Journals (Sweden)

    Carlos A. García

    2012-09-01

    Full Text Available Stenotrophomonas maltophilia is an emerging nosocomial pathogen. Despite the broad spectrum of syndromes associated with S. maltophilia infections, little is known about its virulence factors, including siderophore production. The aims of this work were to detect S. maltophilia siderophores and to determine their chemical nature. We studied 31 S. maltophilia isolates from device-associated infections, recovered over the period 2006-2011 at Hospital de Clínicas José de San Martin, Buenos Aires, Argentina, and the strain K279a, whose genome has been fully sequenced. The production of siderophores was screened by the chrome azurol S (CAS agar assay, previously modified to detect siderophores in this species. When grown on modified CAS agar plates, all the clinical isolates and K279a were CAS-positive for siderophore production. In order to determine the chemical nature of siderophores, the Csáky (hydroxamate-type and Arnow (catechol-type assays were used. All S. maltophilia isolates produced catechol-type siderophores, but hydroxamate-type siderophores were not detected.Stenotrophomonas maltophilia es un patógeno nosocomial emergente. A pesar de la variedad de infecciones que produce, poco se conoce acerca de sus factores de virulencia, incluida la producción de sideróforos. Nuestros objetivos fueron detectar sideróforos de S. maltophilia y determinar su naturaleza química. Se estudiaron 31 aislamientos provenientes de infecciones asociadas al uso de dispositivos médicos y la cepa K279a, cuyo genoma ha sido completamente secuenciado. Los aislamientos provenientes de infecciones se obtuvieron de pacientes asistidos en el Hospital de Clínicas José de San Martín (Buenos Aires, Argentina en el período 2006- 2011. Como método de tamizaje se empleó la técnica chrome azurol S (CAS en placa, luego de implementar una modificación para detectar sideróforos en esta especie. Dicha modificación permitió detectar la producción de sider

  1. Siderophores, the answer for micro to nanosized asbestos fibre related health hazard

    Science.gov (United States)

    Bhattacharya, Shabori; Ledwani, Lalita; John, P. J.

    2016-04-01

    Recent studies on the potential toxicity of High Aspect Ratio Nanoparticles (HARN) has yet once again reinforced the health hazard imposed by asbestos fibres ranging from nano to micro size. Asbestos a naturally occurring fibrous mineral declared a Group I definite carcinogen by IARC (International Agency for Research on Cancer), a unit of WHO in the year 1987, has been extensively used since World War II to the near past for various commercial products. According to the most recent World Health Organization (WHO) estimates, asbestos-related diseases, resulting from exposure at workplace claims more than 107000 lives every year worldwide. The various types of toxic effects induced by asbestos in humans include - i) inflammation and fibrogenesis of lung, ii) mesothelioma iii) asbestosis and iv) bronchogenic carcinoma. The stability of asbestos in natural environment and its biological aggressiveness is related to their fibrous structure and dimensions. The actual risk associated with the exposure to nanosized asbestos, which is still unknown and escapes most regulations worldwide, has been shown in various toxicity assessment studies conducted on various animal models.In an effort to reduce the size of asbestos and therby its toxicity by limiting its biopersistence, oxalic acid treatment of asbestos coupled to power ultrasound treatment was carried out. The nanosized particles formed were still found to retain their hazardous effect. Similar were the results obtained on strong acid treatment of asbestos as well. A probable solution to the asbestos toxicity problem therefore envisaged was bioremediation. This involved the secretion of iron chelating molecules termed siderophores by microbes, which are of significance due to their ability to form very stable and soluble complexes with iron. Iron in asbestos composition is a major factor responsible for its carcinogenicity, removal or extraction of which would prove to be an effective answer to the worldwide problem

  2. HSCCC separation and enantiomeric distribution of key volatile constituents of Piper claussenianum (Miq.) C. DC. (Piperaceae).

    Science.gov (United States)

    Marques, André M; Fingolo, Catharina E; Kaplan, Maria Auxiliadora C

    2017-11-01

    High Speed Countercurrent Chromatography (HSCCC) technique was used for the preparative isolation of the major leishmanicidal compounds from the essential oils of Piper claussenianum species in Brazil. The essential oils from inflorescences of P. claussenianum were analyzed by GC-FID and GC-MS. The enantiomeric ratio of the major constituents of the P. claussenianum essential oils were determined using a Rt-DEXsm chiral capillary column by GC-FID analysis. It was found an enantiomeric excess of (+)-(E)-nerolidol in the leaves, and (+)-linalool and (+)-(E)-nerolidol in the inflorescences essential oil. The major volatile terpenes alcohols were isolated in preparative scale from inflorescences: linalool (320.0 mg) and nerolidol (95.0 mg) in high purity level. The HSCCC, a support-free liquid-liquid partition chromatographic technique, proved to be an effective and useful method for fast isolation and purification of hydrophobic and similarly structured bioactive components from essential oils of Piper species. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Enantioselectivity of a recombinant epoxide hydrolase from Agrobacterium radiobacter

    NARCIS (Netherlands)

    Lutje Spelberg, Jeffrey H.; Rink, Rick; Kellogg, Richard M.; Janssen, Dick B.

    1998-01-01

    The recombinant epoxide hydrolase from Agrobacterium radiobacter AD1 was used to obtain enantiomerically pure epoxides by means of a kinetic resolution. Epoxides such as styrene oxide and various derivatives thereof and phenyl glycidyl ether were obtained in high enantiomeric excess and in

  4. Detection of siderophores in endophytic bacteria Methylobacterium spp. associated with Xylella fastidiosa subsp. pauca Detecção de sideróforos nas bactérias endofíticas Methylobacterium spp. associadas com Xylella fastidiosa subsp. pauca

    OpenAIRE

    Paulo Teixeira Lacava; Maria Estela Silva-Stenico; Welington Luiz Araújo; Ana Valéria Colnaghi Simionato; Emanuel Carrilho; Siu Mui Tsai; João Lúcio Azevedo

    2008-01-01

    The objective of this work was to study the production of siderophores by endophytic bacteria Methylobacterium spp., which occupy the same ecological niche as Xylella fastidiosa subsp. pauca (Xfp) in citrus plants. The siderophore production of Methylobacterium strains was tested according to chromeazurol agar assay test (CAS), Csáky test (hydroxamate-type) and Arnow test (catechol-type). In addition, the ability of Xfp to use siderophores, in vitro, produced by endophytic bacteria as source ...

  5. Enantiomeric determination of amino compounds with high sensitivity using the chiral reagents (+)- and (-)-1-(9-anthryl)-2-propyl chloroformate.

    Science.gov (United States)

    Thorsén, G; Engström, A; Josefsson, B

    1997-10-31

    New chiral precolumn reagents, (+)- and (-)-1-(9-anthryl)-2-propyl chloroformate (APOC), are introduced for the chiral separation of amino acids and small peptides in capillary electrophoresis. Chiral separation of 17 amino acids and four small peptides as their diastereomeric 1-(9-anthryl)-2-propyl carbamate derivatives have been achieved by micellar electrokinetic chromatography. The detection limit for the derivatives is in the femtomole range with UV detection and in the attomole range with laser-induced fluorescence (LIF) detection. LIF detection was used to determine the enantiomeric excess of four APOC-derivatised peptides. The use of the new, anthracene-based reagents in conjunction with argon ion LIF makes enantiomeric determinations at ppm levels feasible. In this paper determinations below promille levels are performed without overloading the separation system.

  6. Treatment of Oral Biofilms by a D-Enantiomeric Peptide.

    Science.gov (United States)

    Zhang, Tian; Wang, Zhejun; Hancock, Robert E W; de la Fuente-Núñez, César; Haapasalo, Markus

    2016-01-01

    Almost all dental diseases are caused by biofilms that consist of multispecies communities. DJK-5, which is a short D-enantiomeric, protease-resistant peptide with broad-spectrum anti-biofilm activity, was tested for its effect on oral multispecies biofilms. Peptide DJK-5 at 10 μg/mL effectively prevented the growth of these microbes in culture media in a time-dependent manner. In addition to the prevention of growth, peptide DJK-5 completely killed both Streptococcus mutans and Enterococcus faecalis suspended from biofilms after 30 minutes of incubation in liquid culture media. DJK-5 also led to the effective killing of microbes in plaque biofilm. The proportion of bacterial cells killed by 10 μg/mL of DJK-5 was similar after 1 and 3 days, both exceeding 85%. DJK-5 was able to significantly prevent biofilm formation over 3 days (P = 0.000). After 72 hours of exposure, DJK-5 significantly reduced and almost completely prevented plaque biofilm production by more than 90% of biovolume compared to untreated controls (P = 0.000). The proportion of dead biofilm bacteria at the 10 μg/mL DJK-5 concentration was similar for 1- and 3-day-old biofilms, whereby >86% of the bacteria were killed. DJK-5 was also able to kill >79% and >85% of bacteria, respectively, after one-time and three brief treatments of 3-day-old biofilms. The combination of DJK-5 and chlorhexidine showed the best bacterial killing among all treatments, with ~83% and >88% of bacterial cells killed after 1 and 3 minutes, respectively. No significant difference was found in the percentage of biofilm killing amongst three donor plaque samples after DJK-5 treatment. In particular, DJK-5 showed strong performance in inhibiting biofilm development and eradicating pre-formed oral biofilms compared to L-enantiomeric peptide 1018. DJK-5 was very effective against oral biofilms when used alone or combined with chlorhexidine, and may be a promising agent for use in oral anti-biofilm strategies in the future.

  7. Amino Acid Enantiomeric Ratios in Biogeochemistry: Complications and Opportunities

    Science.gov (United States)

    McDonald, G. D.; Sun, H. J.; Tsapin, A. I.

    2003-12-01

    Amino acid enantiomeric ratios have been used for many years as an indicator of the process of racemization, and thus as a method to determine the age of biological samples such as bones, shells, and teeth. Dating biological samples by this method relies on an accurate knowledge of the environmental temperatures the sample has experienced, and the racemization kinetic parameters in the sample matrix. In some environments, where an independent dating method such as radiocarbon is available, the observed amino acid D/L ratios are found to be either higher or lower than those expected due to racemization alone. The observed D/L ratios in these cases can be clues to biogeochemical processes operating in addition to, or in place of, chemical racemization. In Siberian permafrost (Brinton et al. 2002, Astrobiology 2, 77) we have found D/L ratios lower than expected, which we have interpreted as evidence for low-level D-amino acid metabolism and recycling in microorganisms previously thought to be metabolically dormant. In microbially-colonized Antarctic Dry Valley sandstones (McDonald and Sun 2002, Eos Trans. AGU 83, Fall Meet. Suppl., Abstract B11A-0720) we have found D/L ratios higher than can be accounted for by racemization alone, most likely due to the accumulation of D-amino-acid-containing peptidoglycan material from multiple bacterial generations. D/L profiles in polar ices and in ice-covered lakes (Tsapin et al. 2002, Astrobiology 2, 632) can be used to indicate the sources and histories of water or ice samples. Multiple biological and biogeochemical processes may complicate the interpretation of amino acid enantiomeric excesses in both terrestrial and extraterrestrial samples; however, amino acid racemization remains a useful tool in biogeochemistry and astrobiology. With a good knowledge of the environmental history of samples, amino acid D/L profiles can be used as a window into processes such as molecular repair and biomass turnover that are difficult to

  8. Selected Ga-68-siderophores versus Ga-68-colloid and Ga-68-citrate: biodistribution and small animal imaging in mice

    Czech Academy of Sciences Publication Activity Database

    Petřík, M.; Vlčková, A.; Nový, Z.; Urbánek, Lubor; Haas, H.; Decristoforo, C.

    2015-01-01

    Roč. 159, č. 1 (2015), s. 60-66 ISSN 1213-8118 R&D Projects: GA MŠk(CZ) LO1304 Institutional support: RVO:61389030 Keywords : gallium-68 * siderophores * colloid Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 0.924, year: 2015

  9. Batch-processing of imaging or liquid-chromatography mass spectrometry datasets and De Novo sequencing of polyketide siderophores

    Czech Academy of Sciences Publication Activity Database

    Novák, Jiří; Sokolová, Lucie; Lemr, Karel; Pluháček, Tomáš; Palyzová, Andrea; Havlíček, Vladimír

    2017-01-01

    Roč. 1865, č. 7 (2017), s. 768-775 ISSN 1570-9639 R&D Projects: GA ČR(CZ) GA16-20229S; GA MŠk(CZ) LO1509 Institutional support: RVO:61388971 Keywords : Mass spectrometry imaging * De novo sequencing * Siderophores Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.773, year: 2016

  10. Prokaryotic Selectivity, Anti-endotoxic Activity and Protease Stability of Diastereomeric and Enantiomeric Analogs of Human Antimicrobial Peptide LL-37

    International Nuclear Information System (INIS)

    Nan, Yong Hai; Lee, Bongju; Shin, Song Yub

    2012-01-01

    LL-37 is the only antimicrobial peptide (AMP) of the human cathelicidin family. In addition to potent antimicrobial activity, LL-37 is known to have the potential to inhibit lipolysaccharide (LPS)-induced endotoxic effects. To provide the stability to proteolytic digestion and increase prokaryotic selectivity and/or anti-endotoxic activity of two Lys/Trp-substituted 19-meric anti-microbial peptides (a4-W1 and a4-W2) designed from IG-19 (residues 13-31 of LL-37), we synthesized the diastereomeric peptides (a4-W1-D and a4-W2-D) with D-amino acid substitution at positions 3, 7, 10, 13 and 17 of a4-W1 and a4-W2, respectively and the enantiomeric peptides (a4-W1-E and a4-W2-E) composed D-amino acids. The diastereomeric peptides exhibited the best prokaryotic selectivity and effective protease stability, but no or less anti-endotoxic activity. In contrast, the enantiomeric peptides had not only prokaryotic selectivity and anti-endotoxic activity but also protease stability. Our results suggest that the hydrophobicity and α-helicity of the peptide is important for anti-endotoxic activity. In particular, the enantiomeric peptides showed potent anti-endotoxic and LPS-neutralizing activities comparable to that of LL-37. Taken together, both a4-W1-E and a4-W2-E holds promise as a template for the development of peptide antibiotics for the treatment of endotoxic shock and sepsis

  11. Prokaryotic Selectivity, Anti-endotoxic Activity and Protease Stability of Diastereomeric and Enantiomeric Analogs of Human Antimicrobial Peptide LL-37

    Energy Technology Data Exchange (ETDEWEB)

    Nan, Yong Hai; Lee, Bongju; Shin, Song Yub [Chosun Univ., Gwangju (Korea, Republic of)

    2012-09-15

    LL-37 is the only antimicrobial peptide (AMP) of the human cathelicidin family. In addition to potent antimicrobial activity, LL-37 is known to have the potential to inhibit lipolysaccharide (LPS)-induced endotoxic effects. To provide the stability to proteolytic digestion and increase prokaryotic selectivity and/or anti-endotoxic activity of two Lys/Trp-substituted 19-meric anti-microbial peptides (a4-W1 and a4-W2) designed from IG-19 (residues 13-31 of LL-37), we synthesized the diastereomeric peptides (a4-W1-D and a4-W2-D) with D-amino acid substitution at positions 3, 7, 10, 13 and 17 of a4-W1 and a4-W2, respectively and the enantiomeric peptides (a4-W1-E and a4-W2-E) composed D-amino acids. The diastereomeric peptides exhibited the best prokaryotic selectivity and effective protease stability, but no or less anti-endotoxic activity. In contrast, the enantiomeric peptides had not only prokaryotic selectivity and anti-endotoxic activity but also protease stability. Our results suggest that the hydrophobicity and α-helicity of the peptide is important for anti-endotoxic activity. In particular, the enantiomeric peptides showed potent anti-endotoxic and LPS-neutralizing activities comparable to that of LL-37. Taken together, both a4-W1-E and a4-W2-E holds promise as a template for the development of peptide antibiotics for the treatment of endotoxic shock and sepsis.

  12. Synthesis of enantiomerically pure (R)- and (S)-2-sulfanylpropanoic acids (‘thiolactic acid’) from ethyl (S)-lactate using pig liver esterase

    NARCIS (Netherlands)

    Hof, Robert P.; Kellogg, Richard M.

    1995-01-01

    The methanesulfonates of optically pure ethyl (S)-lactate or ethyl (R)-2-chloropropanoate 5, obtained with inversion of configuration from ethyl (S)-lactate on treatment with SOCl2, can be substituted by caesium thiolates with inversion of configuration to yield (R) and (S) ethyl

  13. Disappearing Enantiomorphs: Single Handedness in Racemate Crystals.

    Science.gov (United States)

    Parschau, Manfred; Ernst, Karl-Heinz

    2015-11-23

    Although crystallization is the most important method for the separation of enantiomers of chiral molecules in the chemical industry, the chiral recognition involved in this process is poorly understood at the molecular level. We report on the initial steps in the formation of layered racemate crystals from a racemic mixture, as observed by STM at submolecular resolution. Grown on a copper single-crystal surface, the chiral hydrocarbon heptahelicene formed chiral racemic lattice structures within the first layer. In the second layer, enantiomerically pure domains were observed, underneath which the first layer contained exclusively the other enantiomer. Hence, the system changed from a 2D racemate into a 3D racemate with enantiomerically pure layers after exceeding monolayer-saturation coverage. A chiral bias in form of a small enantiomeric excess suppressed the crystallization of one double-layer enantiomorph so that the pure minor enantiomer crystallized only in the second layer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. The impact of siderophore secretion by pseudomonas stutzeri to chelating cu metal in solution culture

    International Nuclear Information System (INIS)

    Azmat, R.

    2014-01-01

    This article discuss the interaction of siderophores (which are low molecular weight, secreted metabolites) of microorganisms (Pseudomonas stutzeri) separately and simultaneously with Cu metal in the solution culture on the roots of 4d old seedlings of Vigna radiata. Naturally occurring bacteria play an important role in plant growth due to the release of pigment. It is a coloring compound (siderophore) showed high chemical oxygen demand (COD), lowers the pressure of oxygen. This lowers the nutrient uptake by the roots due to which reduced plant growth with metabolic disorder was observed in the whole plant. A wide range of phenomena from simple to complex interactions was observed between microorganisms and Cu metal in relation with plant root growth such as adsorption, oxidation/reduction of pigment, solubilization. Results showed that microbial strain showed a significant effect on weight of root in aqueous culture whereas nutrient medium support the root growth. Biochemical analysis reflects that lipids were main target of both abiotic and biotic stress that may utilizes to overcome the stress due to which protein contents were seemed to be unaffected at highest concentration of metal or it may also be related with the degradation of lipids due to the biotic and abiotic stress. (author)

  15. Efficient Synthesis of β-Aryl-γ-lactams and Their Resolution with (S-Naproxen: Preparation of (R- and (S-Baclofen

    Directory of Open Access Journals (Sweden)

    Iris J. Montoya-Balbás

    2015-12-01

    Full Text Available An efficient synthesis of enantiomerically-pure β-aryl-γ-lactams is described. The principal feature of this synthesis is the practical resolution of β-aryl-γ-lactams with (S-Naproxen. The procedure is based on the Michael addition of nitromethane to benzylidenemalonates, which was easily obtained, followed by the reduction of the γ-nitroester in the presence of Raney nickel and the subsequent saponification/decarboxylation reaction. The utility of this methodology was highlighted by the preparation of enantiomerically-pure (R- and (S-Baclofen hydrochloride.

  16. Crystallization and preliminary X-ray crystallographic analysis of MbtI, a protein essential for siderophore biosynthesis in Mycobacterium tuberculosis

    International Nuclear Information System (INIS)

    Harrison, Anthony J.; Ramsay, Rochelle J.; Baker, Edward N.; Lott, J. Shaun

    2004-01-01

    MbtI, the putative isochorismate synthase essential for siderophore biosynthesis in M. tuberculosis, has been crystallized. Diffraction data have been collected to 1.8 Å resolution. Mycobacterium tuberculosis, the causative agent of tuberculosis, depends on the secretion of salicylate-based siderophores called mycobactins for the acquisition of extracellular iron, which is essential for the growth and virulence of the bacterium. The protein MbtI is thought to be the isochorismate synthase enzyme responsible for the conversion of chorismate to isochorismate, the first step in the salicylate production required for mycobactin biosynthesis. MbtI has been overexpressed in Escherichia coli, purified and crystallized. The crystals diffract to a maximum resolution of 1.8 Å. They belong to space group P2 1 2 1 2 1 , with unit-cell parameters a = 51.8, b = 163.4, c = 194.9 Å, consistent with the presence of either two, three or four molecules in the asymmetric unit

  17. Siderophores of Stenotrophomonas maltophilia: detection and determination of their chemical nature Sideróforos de Stenotrophomonas maltophilia: detección y determinación de su naturaleza química

    OpenAIRE

    Carlos A. García; Beatriz Passerini De Rossi; Eliana Alcaraz; Carlos Vay; Mirta Franco

    2012-01-01

    Stenotrophomonas maltophilia is an emerging nosocomial pathogen. Despite the broad spectrum of syndromes associated with S. maltophilia infections, little is known about its virulence factors, including siderophore production. The aims of this work were to detect S. maltophilia siderophores and to determine their chemical nature. We studied 31 S. maltophilia isolates from device-associated infections, recovered over the period 2006-2011 at Hospital de Clínicas José de San Martin, Buenos Aires...

  18. Oxidative mobilization of cerium and uranium and enhanced release of "immobile" high field strength elements from igneous rocks in the presence of the biogenic siderophore desferrioxamine B

    Science.gov (United States)

    Kraemer, Dennis; Kopf, Sebastian; Bau, Michael

    2015-09-01

    Polyvalent trace elements such as the high field strength elements (HFSE) are commonly considered rather immobile during low-temperature water-rock interaction. Hence, they have become diagnostic tools that are widely applied in geochemical studies. We present results of batch leaching experiments focused on the mobilization of certain HFSE (Y, Zr, Hf, Th, U and rare earth elements) from mafic, intermediate and felsic igneous rocks in the presence and absence, respectively, of the siderophore desferrioxamine B (DFOB). Our data show that DFOB strongly enhances the mobility of these trace elements during low-temperature water-rock interaction. The presence of DFOB produces two distinct features in the Rare Earths and Yttrium (REY) patterns of leaching solutions, regardless of the mineralogical and chemical composition or the texture of the rock type studied. Bulk rock-normalized REY patterns of leaching solutions with DFOB show (i) a very distinct positive Ce anomaly and (ii) depletion of La and other light REY relative to the middle REY, with a concave downward pattern between La and Sm. These features are not observed in experiments with hydrochloric acid, acetic acid or deionized water. In DFOB-bearing leaching solutions Ce and U are decoupled from and selectively enriched relative to light REY and Th, respectively, due to oxidation to Ce(IV) and U(VI). Oxidation of Ce3+ and U4+ is promoted by the significantly higher stability of the Ce(IV) and U(VI) DFOB complexes as compared to the Ce(III) and U(IV) DFOB complexes. This is similar to the relationship between the Ce(IV)- and Ce(III)-pentacarbonate complexes that cause positive Ce anomalies in alkaline lakes. However, while formation of Ce(IV) carbonate complexes is confined to alkaline environments, Ce(IV) DFOB complexes may produce positive Ce anomalies even in mildly acidic and near-neutral natural waters. Siderophore-promoted dissolution processes also significantly enhance mobility of other 'immobile' HFSE

  19. Physiological and molecular genetic evaluation of the dechlorination agent, pyridine-2,6-bis(monothiocarboxylic acid) (PDTC) as a secondary siderophore of Pseudomonas.

    Science.gov (United States)

    Lewis, Thomas A; Leach, Lynne; Morales, Sergio; Austin, Paula R; Hartwell, Hadley J; Kaplan, Benjamin; Forker, Cynthia; Meyer, Jean-Marie

    2004-02-01

    The bacterial metabolite and transition metal chelator pyridine-2,6-dithiocarboxylic acid (PDTC), promotes a novel and effective means of dechlorination of the toxic and carcinogenic pollutant, carbon tetrachloride. Pyridine-2,6-dithiocarboxylic acid has been presumed to act as a siderophore in the Pseudomonas strains known to produce it. To explore further the physiological function of PDTC production, we have examined its regulation, the phenotype of PDTC-negative (pdt) mutants, and envelope proteins associated with PDTC in P. putida strain DSM 3601. Aspects of the regulation of PDTC production and outer membrane protein composition were consistent with siderophore function. Pyridine-2,6-dithiocarboxylic acid production was coordinated with production of the well-characterized siderophore pyoverdine; exogenously added pyoverdine led to decreased PDTC production, and added PDTC led to decreased pyoverdine production. Positive regulation of a chromosomal pdtI-xylE transcriptional fusion, and of a 66 kDa outer membrane protein (IROMP), was seen in response to exogenous PDTC. Tests with transition metal chelators indicated that PDTC could provide a benefit under conditions of metal limitation; the loss of PDTC biosynthetic capacity caused by a pdtI transposon insertion resulted in increased sensitivity to 1,10-phenanthroline, a chelator that has high affinity for a range of divalent transition metals (e.g. Fe(2+), Cu(2+), Zn(2+)). Exogenously added PDTC could also suppress a phenotype of pyoverdine-negative (Pvd-) mutants, that of sensitivity to EDDHA, a chelator with higher affinity and specificity for Fe(3+). Measurement of 59Fe incorporation showed uptake from 59Fe:PDTC by DSM 3601 grown in low-iron medium, but not by cells grown in high iron medium, or by the pdtI mutant, which did not show expression of the 66 kDa envelope protein. These data verified a siderophore function for PDTC, and have implicated it in the uptake of transition metals in addition to iron.

  20. Occurrence of organochlorine pesticides (OCPs) and their enantiomeric signatures, and concentrations of polybrominated diphenyl ethers (PBDEs) in the Adelie penguin food web, Antarctica

    International Nuclear Information System (INIS)

    Corsolini, Simonetta; Covaci, Adrian; Ademollo, Nicoletta; Focardi, Silvano; Schepens, Paul

    2006-01-01

    Concentrations and enantiomeric signatures of organochlorine pesticides were determined in Antarctic krill, emerald rockcod and Adelie penguin from the Ross Sea, Antarctica. HCB and DDTs were prevalent contaminants in penguin eggs. The highest concentrations of ΣHCHs (1.35 ± 0.72 ng/g) were found in the rockcod muscle, where γ-HCH (1.23 ± 0.67 ng/g) was the principal isomer. The ratio γ-HCH/α-HCH was evaluated. Enantioselective gas chromatography was used for the evaluation of enantiomeric fractions (EFs) for α-HCH and oxychlordane. An increase of 14% in the (+)α-HCH enantiomer was found from krill through penguin, suggesting the enantioselective biotrasformation increased proportionately with trophic level. Polybrominated diphenyl ethers (PBDEs) were measured and their concentrations were 5.6 ± 1.12, 5.81 ± 2.32, 4.57 ± 0.17 and 3.06 ± 3.27 ng/g lipids in krill, rockcod muscle, rockcod homogenate and penguin eggs, respectively. The detection of BDE28, BDE47, BDE99 and BDE100 in Antarctic organisms confirmed their global transport and distribution; the detection of lower brominated congeners suggested a potential long-range transport. - Enantiomeric signature and accumulation of polybrominated diphenyl ethers in the Adelie Penguin food chain are discussed

  1. SYNTHESIS OF ENANTIOMERICALLY PURE (R)-2-SULFANYLPROPANOIC AND (S)-2-SULFANYLPROPANOIC ACIDS (THIOLACTIC ACID) FROM ETHYL (S)-LACTATE USING PIG-LIVER ESTERASE

    NARCIS (Netherlands)

    HOF, RP; KELLOGG, RM

    1995-01-01

    The methanesulfonates of optically pure ethyl (S)-lactate or ethyl (R)-2-chloropropanoate 5, obtained with inversion of configuration from ethyl (S)-lactate on treatment with SOCl2, can be substituted by caesium thiolates with inversion of configuration to yield (R) and (S) ethyl

  2. Magnesium interference and different efficiencies of diastereoisomeric cluster formation in phenylalanine enantiomeric discrimination by the kinetic method

    Czech Academy of Sciences Publication Activity Database

    Ranc, V.; Havlíček, Vladimír; Bednář, P.; Lemr, Karel

    2009-01-01

    Roč. 280, 1-3 (2009), s. 213-217 ISSN 1387-3806 R&D Projects: GA MŠk LC07017; GA ČR GA203/07/0765 Grant - others:XE(XE) EC: MKTD-CT-2004-014407 Institutional research plan: CEZ:AV0Z50200510 Keywords : enantiomeric dicrimination * kinetic method * mass spectrometry Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.117, year: 2009

  3. Enantioselective degradation and enantiomerization of indoxacarb in soil.

    Science.gov (United States)

    Sun, Dali; Pang, Junxiao; Qiu, Jing; Li, Li; Liu, Chenglan; Jiao, Bining

    2013-11-27

    In this study, the enantioselective degradation and enantiomerizaton of indoxacarb were investigated in two soils under nonsterilized and sterilized conditions using a chiral OD-RH column on a reversed-phase HPLC. Under nonsterilized conditions, the degradation of indoxacarb in two soils was enantioselective. In acidic soil, the half-lives of R-(-)- and S-(+)-indoxacarb were 10.43 and 14.00 days, respectively. Acidic soil was preferential to the degradation of R-(-)-indoxacarb. In alkaline soil, the half-lives of R-(-)- and S-(+)-indoxacarb were 12.14 and 4.88 days, respectively. S-(+)-Indoxacarb was preferentially degraded. Under sterilized conditions, approximately 5-10% of the initial concentration degraded after 75 days of incubation in acidic soil, whereas in alkaline soil, approximately half of the initial concentration degraded due to chemical hydrolysis under alkaline conditions. Enantiomerization was also discovered in acidic and alkaline soils. The results showed that mutual transformation existed between two enantiomers and that S-(+)-indoxacarb had a significantly higher inversion rate to R-(-)-indoxacarb than its antipode.

  4. Mitophagy confers resistance to siderophore-mediated killing by Pseudomonas aeruginosa.

    Science.gov (United States)

    Kirienko, Natalia V; Ausubel, Frederick M; Ruvkun, Gary

    2015-02-10

    In the arms race of bacterial pathogenesis, bacteria produce an array of toxins and virulence factors that disrupt core host processes. Hosts mitigate the ensuing damage by responding with immune countermeasures. The iron-binding siderophore pyoverdin is a key virulence mediator of the human pathogen Pseudomonas aeruginosa, but its pathogenic mechanism has not been established. Here we demonstrate that pyoverdin enters Caenorhabditis elegans and that it is sufficient to mediate host killing. Moreover, we show that iron chelation disrupts mitochondrial homeostasis and triggers mitophagy both in C. elegans and mammalian cells. Finally, we show that mitophagy provides protection both against the extracellular pathogen P. aeruginosa and to treatment with a xenobiotic chelator, phenanthroline, in C. elegans. Although autophagic machinery has been shown to target intracellular bacteria for degradation (a process known as xenophagy), our report establishes a role for authentic mitochondrial autophagy in the innate immune defense against P. aeruginosa.

  5. Detection of siderophores in endophytic bacteria Methylobacterium spp. associated with Xylella fastidiosa subsp. pauca Detecção de sideróforos nas bactérias endofíticas Methylobacterium spp. associadas com Xylella fastidiosa subsp. pauca

    Directory of Open Access Journals (Sweden)

    Paulo Teixeira Lacava

    2008-04-01

    Full Text Available The objective of this work was to study the production of siderophores by endophytic bacteria Methylobacterium spp., which occupy the same ecological niche as Xylella fastidiosa subsp. pauca (Xfp in citrus plants. The siderophore production of Methylobacterium strains was tested according to chromeazurol agar assay test (CAS, Csáky test (hydroxamate-type and Arnow test (catechol-type. In addition, the ability of Xfp to use siderophores, in vitro, produced by endophytic bacteria as source of iron, was evaluated. All 37 strains of Methylobacterium spp. tested were CAS-positive for siderophore production. Methylobacterium spp. produced hydroxamate-type, but not catechol-type siderophores. In vitro growth of Xfp was stimulated by the presence of supernatant siderophores of endophytic Methylobacterium mesophilicum.O objetivo deste trabalho foi estudar a produção de sideróforos pelas bactérias endofíticas Methylobacterium spp., que ocupam o mesmo nicho ecológico que Xylella fastidiosa subsp. pauca (Xfp, em plantas cítricas. A produção de sideróforos, pelas linhagens de Methylobacterium, foi testada por meio do ensaio de cromoazarol-ágar (chromeazurol agar assay-CAS, teste de Csáky (tipo hidroxamato e do teste de Arnow (tipo catecol. Além disso, a habilidade de Xfp em utilizar sideróforos produzidos por bactérias endofíticas, como fonte de ferro, in vitro, foi avaliada. Todas as 37 linhagens de Methylobacterium spp. testadas foram positivas para a produção de sideróforos, pelo teste CAS-ágar. Methylobacterium spp. foram capazes de produzir sideróforos do tipo hidroxamato, mas não do tipo catecol. O crescimento in vitro de Xfp foi estimulado pela presença de sideróforos no sobrenadante de Methylobacterium mesophilicum endofítica.

  6. Synthesis and optical properties of enantiomeric cinchonidine/cinchonine-terpyridine derivatives and their metal complexes

    International Nuclear Information System (INIS)

    Wang, Hui-Ting; Wu, Wen-Jie; Liu, Jiang; Chen, Meng; Qian, Dong-Jin; Zhang, Li; Liu, Minghua

    2016-01-01

    We report here the synthesis and spectroscopic properties of two enantiomeric chiral tridentate ligands (TPyCCD and TPyCCN) composed of terpyridine (TPy) and cinchonidine (CCD) or cinchonine (CCN) substituent, as well as their metal complexes with Zn 2+ , Fe 2+ , Eu 3+ , and Tb 3+ ions. For the pure ligands, the fluorescent emission intensity increased as their concentrations increased in the dilute solutions, but they decreased when the concentrations were greater than 6.9×10 −6 mol/l due to concentration quenching. No significant influence on ligand luminescence was observed for the Zn 2+ /Fe 2+ –TPyCCD and –TPyCCN metal complexes. Their lanthanide (Eu 3+ and Tb 3+ ) complexes displayed both ligand and lanthanide ion emissions, suggesting that the excited energy of both ligands could be transferred to the central Eu 3+ and Tb 3+ ions. Mirror-image circular dichroism spectra were recorded, with several signals centered at about 230, 250–270, 296, and 320 nm; the first ones corresponded to the chiral CCD and CCN substituents, while the latter ones corresponded to the TPy substituent and the metal–TPy (M-TPy) coordination units. It is suggested that the chirality of TPy and the metal complexes was induced by the coexisting chiral CCD and CCN substituents. In addition, due to formation of the metal complexes, the relative intensity of the chiral signals of M–TPy coordination units was enhanced at about 320 nm. - Highlights: • Cinchona alkaloid-terpyridine derivatives and metal complexes were prepared. • Cinchona alkaloid-terpyridine derivatives gave off luminescence at 362 nm. • Ligand excited energy could efficiently transferred to lanthanide ions. • Chirality of terpyridine and metal complexes was induced.

  7. Reducing the concentration to 0.4% enantiomeric excess hyperbaric levobupivacaine (s75: r25) provides unilateral spinal anesthesia. Study with different volumes.

    Science.gov (United States)

    Imbelloni, Luiz Eduardo; Gouveia, Marildo A; Carneiro, Antonio Fernando; Grigorio, Renata

    2012-01-01

    Unilateral spinal anesthesia may be obtained with hypobaric or hyperbaric solution. The objective of this study was to compare different doses of enantiomeric excess hyperbaric levobupivacaine to achieve unilateral spinal anesthesia. One hundred and twenty patients were randomized to receive 4 mg, 6 mg or 8 mg of 0.4% enantiomeric excess levobupivacaine. The solutions were administered at the L3-L4, with the patient in a lateral position and kept at this position according to dose administration for 5, 10 or 15 minutes. Sensory block (pinprick) and motor block (scale 0-3) were compared between the operated and contralateral sides. The onset of analgesia was rapid and comparable between groups. Sensory block was significantly higher in the operated than in nonoperated limb at all times of evaluation. Increasing the dose by 1 mL (2mg) corresponded to an increase of two segments in the mode for the operated side. In the operated side, motor block (MB = 3) of patients occurred in 31 (77.5%) with 4 mg, 38 (95%) with 6 mg, and 40 (100%) with 8 mg. There was a positive correlation between increased dose, blockade duration, and hypotension. All patients were satisfied with the technique used. Spinal anesthesia with different volumes of enantiomeric excess hyperbaric bupivacaine (S75: R25) provided a 78% incidence of unilateral spinal block, with the smallest dose used (4 mg) the most efficient. Copyright © 2012 Elsevier Editora Ltda. All rights reserved.

  8. Isolation of Notoamide S and Enantiomeric 6-epi-Stephacidin A from the Fungus Aspergillus amoenus: Biogenetic Implications

    DEFF Research Database (Denmark)

    Kato, Hikaru; Nakahara, Takashi; Sugimoto, Kayo

    2015-01-01

    Notoamide S has been hypothesized to be a key biosynthetic intermediate for characteristic metabolites stephacidin A, notoamide B, and versicolamide B in Aspergillus sp. but has not yet been isolated. The isolation of notoamide S and an enantiomeric mixture of 6-epi-stephacidin A enriched with th...

  9. Enantiomeric profiling of chiral illicit drugs in a pan-European study

    DEFF Research Database (Denmark)

    Castrignanò, Erika; Yang, Zhugen; Bade, Richard

    2018-01-01

    The aim of this paper is to present the first study on spatial and temporal variation in the enantiomeric profile of chiral drugs in eight European cities. Wastewater-based epidemiology (WBE) and enantioselective analysis were combined to evaluate trends in illicit drug use in the context....... High loads of racemic methamphetamine were detected in Oslo (EF = 0.49 ± 0.02). This is in contrast to other European cities where S-(+)-methamphetamine was the predominant enantiomer. This indicates different methods of methamphetamine synthesis and/or trafficking routes in Oslo, compared...... with the other cities tested. An enrichment of MDMA with the R-(−)-enantiomer was observed in European wastewaters indicating MDMA consumption rather than disposal of unused drug. MDA's chiral signature indicated its enrichment with the S-(+)-enantiomer, which confirms its origin from MDMA metabolism in humans...

  10. Study of Substituted Ester Formation in Red Wine by the Development of a New Method for Quantitative Determination and Enantiomeric Separation of Their Corresponding Acids.

    Science.gov (United States)

    Lytra, Georgia; Franc, Celine; Cameleyre, Margaux; Barbe, Jean-Christophe

    2017-06-21

    A new method was developed for quantifying substituted acids including, where applicable, their various unexplored enantiomeric forms. A new step was added to acids' usual quantification methods, consisting of extraction, derivatization to methyl esters, and gas chromatography analysis: preliminary extraction was performed at basic pH to eliminate ethyl esters, thus avoiding their transesterification during derivatization. Quantitation and enantiomeric distribution of some substituted esters and their corresponding acids were established in 31 commercial Bordeaux red wines from 0 to 20 years old. A strong positive correlation was observed between the age of wine and levels of ethyl 2-methylpropanoate, ethyl 3-methylbutanoate, ethyl 2-methylbutanoate, ethyl (3R)-3-hydroxybutanoate, both enantiomeric forms of ethyl 2-hydroxy-3-methylbutanoate, and ethyl (2S)-2-hydroxy-4-methylpentanoate, but not ethyl (3S)-3-hydroxybutanoate. However, the standard deviations of average concentrations for the corresponding substituted acids were so large that only few correlations between concentrations and age were observed. Concentrations of (2S)-2-hydroxy-3-methylbutanoic acid and (2S)-2-hydroxy-4-methylpentanoic acid increased slightly over time, while (2R)-2-hydroxy-4-methylpentanoic acid levels decreased slightly with the age. Variations in the ratio of substituted ethyl esters to their corresponding acids over time detected thanks to these analytical advances suggested that, in general, acids were continuously esterified during aging.

  11. Determination of the Absolute Enantiomeric Excess of the Carbon Nanotube Ensemble by Symmetry Breaking Using the Optical Titration Method.

    Science.gov (United States)

    Sim, Jinsook; Kim, Somin; Jang, Myungsu; Park, Minsuk; Oh, Hyunkyu; Ju, Sang-Yong

    2017-10-17

    Symmetry breaking of single-walled carbon nanotubes (SWNTs) has profound effects on their optoelectronic properties that are essential for fundamental study and applications. Here, we show that isomeric SWNTs that exhibit identical photoluminescence (PL) undergo symmetry breaking by flavin mononucleotide (FMN) and exhibit dual PLs and different binding affinities (K a ). Increasing the FMN concentration leads to systematic PL shifts of SWNTs according to structural modality and handedness due to symmetry breaking. Density gradient ultracentrifugation using a FMN-SWNT dispersion displays PL shifts and different densities according to SWNT handedness. Using the optical titration method to determine the PL-based K a of SWNTs against an achiral surfactant as a titrant, left- and right-handed SWNTs display two-step PL inflection corresponding to respective K a values with FMN, which leads to the determination of the enantiomeric excess (ee) of the SWNT ensemble that was confirmed by circular dichroism measurement. Decreasing the FMN concentration for the SWNT dispersion leads to enantiomeric selection of SWNTs. The titration-based ee determination of the widely used sodium cholate-based SWNT dispersion was also demonstrated by using FMN as a cosurfactant.

  12. Enantiomeric Separation of 1-(Benzofuran-2-yl)alkylamines on Chiral Stationary Phases Based on Chiral Crown Ethers

    International Nuclear Information System (INIS)

    Park, Soohyun; Kim, Sang Jun; Hyun, Myung Ho

    2012-01-01

    Optically active chiral amines are important as building blocks for pharmaceuticals and as scaffolds for chiral ligands and, consequently, many efforts have been devoted to the development of efficient methods for their preparation. For example, reduction of amine precursors with chiral catalysts, enzymatic kinetic resolution or dynamic kinetic resolution of racemic amines and the direct amination of ketones with transaminases have been developed as the efficient methods for the preparation of optically active chiral amines. During the process of developing or utilizing optically active chiral amines, the methods for the determination of their enantiomeric composition are essential. Among various methods, liquid chromatographic resolution of enantiomers on chiral stationary phases (CSPs) have been known to be one of the most accurate and economic means for the determination of the enantiomeric composition of optically active chiral compounds. Especially, CSPs based on chiral crown ethers have been successfully used for the resolution of racemic primary amines. For example, CSPs based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (CSP 1, Figure 1) or (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6 (CSP 2 and CSP 3, Figure 1) have been known to be quite effective for the resolution of cyclic and non-cyclic amines, various fluoroquinolone antibacterials containing a primary amino group, tocainide (antiarrhythmic agent) and its analogues, aryl-a-amino ketones and 3-amino-1,4-benzodiazepin-2-ones

  13. Limitations in determining enantiomeric excess of alcohols by 31 P-NMR of the phosphonate derivatives

    International Nuclear Information System (INIS)

    Laverde Junior, Antonio; Conceicao, Jelson J.A. da; Pilli, Ronaldo A.; Marsaioli, Anita J.; Miranda, Domingos S. de; Schirmer, Heiko; Meijere, Armin de

    1999-01-01

    The use of diastereomeric alcohol dialkyl-phosphonate derivatives to determine the enantiomeric excesses via 31 P-NMR signal ratios of anisochronous meso and threo isomers was successfully applied to secondary alcohols (Feringa's method). Expansion of the methodology to primary alcohols processing the hydroxyl groups tethered to the stereogenic centers by two or more methylene groups proved the method to be inefficient. The comparison between the coupled and decoupled spectra is important in order to identify the signals corresponding to the dialkyl-phosphonates. Nevertheless the methodology should be applied whenever the amount of the alcohol and its structure are not the limiting factors. (author)

  14. Chiral Analysis of Pesticides and Drugs of Environmental Concern: Biodegradation and Enantiomeric Fraction

    Directory of Open Access Journals (Sweden)

    Alexandra S. Maia

    2017-09-01

    Full Text Available The importance of stereochemistry for medicinal chemistry and pharmacology is well recognized and the dissimilar behavior of enantiomers is fully documented. Regarding the environment, the significance is equivalent since enantiomers of chiral organic pollutants can also differ in biodegradation processes and fate, as well as in ecotoxicity. This review comprises designed biodegradation studies of several chiral drugs and pesticides followed by enantioselective analytical methodologies to accurately measure the enantiomeric fraction (EF. The enantioselective monitoring of microcosms and laboratory-scale experiments with different environmental matrices is herein reported. Thus, this review focuses on the importance of evaluating the EF variation during biodegradation studies of chiral pharmaceuticals, drugs of abuse, and agrochemicals and has implications for the understanding of the environmental fate of chiral pollutants.

  15. Development of Chiral LC-MS Methods for small Molecules and Their Applications in the Analysis of Enantiomeric Composition and Pharmacokinetic Studies

    Energy Technology Data Exchange (ETDEWEB)

    Desai, Meera Jay [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    The purpose of this research was to develop sensitive LC-MS methods for enantiomeric separation and detection, and then apply these methods for determination of enantiomeric composition and for the study of pharmacokinetic and pharmacodynamic properties of a chiral nutraceutical. Our first study, evaluated the use of reverse phase and polar organic mode for chiral LC-API/MS method development. Reverse phase methods containing high water were found to decrease ionization efficiency in electrospray, while polar organic methods offered good compatibility and low limits of detection with ESI. The use of lower flow rates dramatically increased the sensitivity by an order of magnitude. Additionally, for rapid chiral screening, the coupled Chirobiotic column afforded great applicability for LC-MS method development. Our second study, continued with chiral LC-MS method development in this case for the normal phase mode. Ethoxynonafluorobutane, a fluorocarbon with low flammability and no flashpoint, was used as a substitute solvent for hexane/heptane mobile phases for LC-APCI/MS. Comparable chromatographic resolutions and selectivities were found using ENFB substituted mobile phase systems, although, peak efficiencies were significantly diminished. Limits of detection were either comparable or better for ENFB-MS over heptane-PDA detection. The miscibility of ENFB with a variety of commonly used organic modifiers provided for flexibility in method development. For APCI, lower flow rates did not increase sensitivity as significantly as was previously found for ESI-MS detection. The chiral analysis of native amino acids was evaluated using both APCI and ESI sources. For free amino acids and small peptides, APCI was found to have better sensitivities over ESI at high flow rates. For larger peptides, however, sensitivity was greatly improved with the use of electrospray. Additionally, sensitivity was enhanced with the use of non-volatile additives, This optimized method was then

  16. A putative siderophore-interacting protein from the marine bacterium Shewanella frigidimarina NCIMB 400: cloning, expression, purification, crystallization and X-ray diffraction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Trindade, Inês B.; Fonseca, Bruno M. [Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras (Portugal); Matias, Pedro M. [Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras (Portugal); Instituto de Biologia Experimental e Tecnológica (iBET), Apartado 12, 2780-901 Oeiras (Portugal); Louro, Ricardo O.; Moe, Elin, E-mail: elinmoe@itqb.unl.pt [Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras (Portugal)

    2016-08-09

    The gene encoding a putative siderophore-interacting protein from the marine bacterium S. frigidimarina was successfully cloned, followed by expression and purification of the gene product. Optimized crystals diffracted to 1.35 Å resolution and preliminary crystallographic analysis is promising with respect to structure determination and increased insight into the poorly understood molecular mechanisms underlying iron acquisition. Siderophore-binding proteins (SIPs) perform a key role in iron acquisition in multiple organisms. In the genome of the marine bacterium Shewanella frigidimarina NCIMB 400, the gene tagged as SFRI-RS12295 encodes a protein from this family. Here, the cloning, expression, purification and crystallization of this protein are reported, together with its preliminary X-ray crystallographic analysis to 1.35 Å resolution. The SIP crystals belonged to the monoclinic space group P2{sub 1}, with unit-cell parameters a = 48.04, b = 78.31, c = 67.71 Å, α = 90, β = 99.94, γ = 90°, and are predicted to contain two molecules per asymmetric unit. Structure determination by molecular replacement and the use of previously determined ∼2 Å resolution SIP structures with ∼30% sequence identity as templates are ongoing.

  17. A full evaluation for the enantiomeric impacts of lactofen and its metabolites on aquatic macrophyte Lemna minor.

    Science.gov (United States)

    Wang, Fang; Liu, Donghui; Qu, Han; Chen, Li; Zhou, Zhiqiang; Wang, Peng

    2016-09-15

    Pesticide pollution of surface water represents a considerable danger for the aquatic plants which play very crucial roles in aquatic system such as oxygen production, nutrient cycling, water quality controlling and sediment stabilization. In this work, the toxic effects of the chiral herbicide lactofen and its three metabolites (desethyl lactofen, acifluorfene and amino acifluorfene) to the aquatic plant Lemna minor (L. minor) on enantiomeric level were evaluated. The influences on growth rate, fresh weight, content of photosynthetic pigment, protein and malondialdehyde (MDA) and the activities of antioxidant defense enzymes (catalase (CAT) and superoxide dismutase (SOD)) were measured after 7 days of exposure. L. minor growth was inhibited in the order of (S)-desethyl lactofen > racemic-desethyl lactofen > (R)-desethyl lactofen > racemic-lactofen > (S)-lactofen > (R)-lactofen > acifluorfene > amino acifluorfene, and the IC50 (7d) values showed desethyl lactofen was the most powerful compound which was about twice as toxic as lactofen. The contents of chlorophylls (Chl) and carotenoids (Car) were significantly reduced by the chemicals, while, the levels of protein, MDA and the activity of CAT and SOD enzymes increased in most cases. The obtained results revealed that lactofen and its metabolites had an undesirable effect on L. minor, in terms of physiological and biochemical aspects. Besides, enantioselective toxicity of lactofen and desethyl lactofen to L. minor was observed. The S-enantiomer of desethyl lactofen was more toxic than the corresponding R-enantiomer. Furthermore, racemic lactofen was more toxic than the individual enantiomers. The side effects of pesticide metabolites and the enantioselectivity should be considered in developing optically pure products and risk assessment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Synthesis of carbon-11 labelled (R)-carnitine

    International Nuclear Information System (INIS)

    Holschbach, M.; Hamkens, W.; Roden, W.; Feinendegen, L.E.

    1991-01-01

    A route to 11 C-labelled (R)-carnitine, based on the methylation of the dimethyl derivative is described. Furthermore, a five-step synthesis for the enantiomerically pure precursor is outlined. (author)

  19. The interplay between siderophore secretion and coupled iron and copper transport in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Nicolaisen, Kerstin; Hahn, Alexander; Valdebenito, Marianne; Moslavac, Suncana; Samborski, Anastazia; Maldener, Iris; Wilken, Corinna; Valladares, Ana; Flores, Enrique; Hantke, Klaus; Schleiff, Enrico

    2010-11-01

    Iron uptake is essential for Gram-negative bacteria including cyanobacteria. In cyanobacteria, however, the iron demand is higher than in proteobacteria due to the function of iron as a cofactor in photosynthesis and nitrogen fixation, but our understanding of iron uptake by cyanobacteria stands behind the knowledge in proteobacteria. Here, two genes involved in this process in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 were identified. ORF all4025 encodes SchE, a putative cytoplasmic membrane-localized transporter involved in TolC-dependent siderophore secretion. Inactivation of schE resulted in an enhanced sensitivity to high metal concentrations and decreased secretion of hydroxamate-type siderophores. ORF all4026 encodes a predicted outer membrane-localized TonB-dependent iron transporter, IacT. Inactivation of iacT resulted in decreased sensitivity to elevated iron and copper levels. Expression of iacT from the artificial trc promoter (P(trc)) resulted in sensitization against tested metals. Further analysis showed that iron and copper effects are synergistic because a decreased supply of iron induced a significant decrease of copper levels in the iacT insertion mutant but an increase of those levels in the strain carrying P(trc)-iacT. Our results unravel a link between iron and copper homeostasis in Anabaena sp. PCC 7120. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Solid-to-solid oxidation of a vanadium(IV) to a vanadium(V) compound: chemisty of a sulfur-containing siderophore.

    Science.gov (United States)

    Chatterjee, Pabitra B; Crans, Debbie C

    2012-09-03

    Visible light facilitates a solid-to-solid photochemical aerobic oxidation of a hunter-green microcrystalline oxidovanadium(IV) compound (1) to form a black powder of cis-dioxidovanadium(V) (2) at ambient temperature. The siderophore ligand pyridine-2,6-bis(thiocarboxylic acid), H(2)L, is secreted by a microorganism from the Pseudomonas genus. This irreversible transformation of a metal monooxo to a metal dioxo complex in the solid state in the absence of solvent is unprecedented. It serves as a proof-of-concept reaction for green chemistry occurring in solid matrixes.

  1. Analysis of hydroxamate siderophores in soil solution using liquid chromatography with mass spectrometry and tandem mass spectrometry with on-line sample preconcentration.

    Science.gov (United States)

    Olofsson, Madelen A; Bylund, Dan

    2015-10-01

    A liquid chromatography with electrospray ionization mass spectrometry method was developed to quantitatively and qualitatively analyze 13 hydroxamate siderophores (ferrichrome, ferrirubin, ferrirhodin, ferrichrysin, ferricrocin, ferrioxamine B, D1 , E and G, neocoprogen I and II, coprogen and triacetylfusarinine C). Samples were preconcentrated on-line by a switch-valve setup prior to analyte separation on a Kinetex C18 column. Gradient elution was performed using a mixture of an ammonium formate buffer and acetonitrile. Total analysis time including column conditioning was 20.5 min. Analytes were fragmented by applying collision-induced dissociation, enabling structural identification by tandem mass spectrometry. Limit of detection values for the selected ion monitoring method ranged from 71 pM to 1.5 nM with corresponding values of two to nine times higher for the multiple reaction monitoring method. The liquid chromatography with mass spectrometry method resulted in a robust and sensitive quantification of hydroxamate siderophores as indicated by retention time stability, linearity, sensitivity, precision and recovery. The analytical error of the methods, assessed through random-order, duplicate analysis of soil samples extracted with a mixture of 10 mM phosphate buffer and methanol, appears negligible in relation to between-sample variations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. The resolution of acyclic P-stereogenic phosphine oxides via the formation of diastereomeric complexes: A case study on ethyl-(2-methylphenyl)-phenylphosphine oxide.

    Science.gov (United States)

    Bagi, Péter; Varga, Bence; Szilágyi, András; Karaghiosoff, Konstantin; Czugler, Mátyás; Fogassy, Elemér; Keglevich, György

    2018-04-01

    As an example of acyclic P-chiral phosphine oxides, the resolution of ethyl-(2-methylphenyl)-phenylphosphine oxide was elaborated with TADDOL derivatives, or with calcium salts of the tartaric acid derivatives. Besides the study on the resolving agents, several purification methods were developed in order to prepare enantiopure ethyl-(2-methylphenyl)-phenylphosphine oxide. It was found that the title phosphine oxide is a racemic crystal-forming compound, and the recrystallization of the enantiomeric mixtures could be used for the preparation of pure enantiomers. According to our best method, the (R)-ethyl-(2-methylphenyl)-phenylphosphine oxide could be obtained with an enantiomeric excess of 99% and in a yield of 47%. Complete racemization of the enantiomerically enriched phosphine oxide could be accomplished via the formation of a chlorophosphonium salt. Characterization of the crystal structures of the enantiopure phosphine oxide was complemented with that of the diastereomeric intermediate. X-ray analysis revealed the main nonbonding interactions responsible for enantiomeric recognition. © 2018 Wiley Periodicals, Inc.

  3. Improved Syntheses and Expanded Analyses of the Enantiomerically Enriched Chiral Cobalt Complexes Co(en)[subscript 3]I[subscript 3] and Co(diNOsar)Br[subscript 3

    Science.gov (United States)

    McClellan, Michael J.; Cass, Marion E.

    2015-01-01

    This communication is a collection of additions and modifications to two previously published classic inorganic synthesis laboratory experiments. The experimental protocol for the synthesis and isolation of enantiomerically enriched ?- (or ?-)Co(en)[subscript 3]I[subscript 3] has been modified to increase reproducibility, yield, and enantiomeric…

  4. Reductive decarboxylation of bicyclic prolinic systems: a new approach to the enantioselective synthesis of the Geissman-Waiss lactone. X-ray structure determination of a key lactone intermediate

    Directory of Open Access Journals (Sweden)

    Ambrósio João Carlos L.

    2003-01-01

    Full Text Available Two concise and enantioselective syntheses of the necine base precursors (1R,5R-N-Cbz and N-Boc-2-oxa-6-azabicyclo[3.3.0]octan-3-ones (Geissman-Waiss lactones were carried out from two enantiomerically pure endocyclic five-membered enecarbamates with overall yields of 23% and 26%, respectively. The synthetic strategy made use of a highly effective and stereoselective [2+2]cycloaddition of enantiomerically pure endocyclic enecarbamates with dichloroketene, as well as an efficient decarboxylation step of a bicyclic alpha-amino acid employing Boger's acyl selenide protocol employing tributyltin hydride. Interesting aspects concerning the regiochemical outcome of Baeyer-Villiger oxidations of bicyclic cyclobutanones are also reported, in which the usual stereoelectronic bias of Baeyer-Villiger oxidation seems to be counterbalanced by steric effects on the putative Criegee intermediate.

  5. Controlling the stereochemistry and regularity of butanethiol self-assembled monolayers on Au(111)

    DEFF Research Database (Denmark)

    Yan, Jiawei; Ouyang, Runhai; Jensen, Palle Skovhus

    2014-01-01

    The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest unsubstitu......The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest...... when R is achiral, while adatom binding leads to rectangular plane groups that suppress long-range expression of chirality. Binding as RS• also inhibits the pitting intrinsically associated with adatom binding, desirably producing more regularly structured SAMs....

  6. Understanding the effect of amino acids based biostimulant by an enantiomeric analysis of their active principles and a proteomic profiling approach

    OpenAIRE

    Sierras, Núria; Botta-Català, Anna; Staasing, L.; Martínez Esteso, María José; Bru-Martinez, Roque

    2016-01-01

    Plant biostimulants are products that contain multiple compounds and claim to activate a wide range of plant responses. Amino acid based products are one example of biostimulants with a complex composition and different product characteristics depending on their sources and production processes. Amino acid biostimulants are obtained mainly by chemical or enzymatic protein hydrolysis and the type of hydrolysis determine the content of free amino acids and their enantiomeric purity. While L-ami...

  7. Synthesis and Utilization of Trialkylammonium-Substituted Cyclodextrins as Water-Soluble Chiral NMR Solvating Agents for Anionic Compounds.

    Science.gov (United States)

    Dowey, Alison E; Puentes, Cira Mollings; Carey-Hatch, Mira; Sandridge, Keyana L; Krishna, Nikhil B; Wenzel, Thomas J

    2016-04-01

    Cationic trialkylammonium-substituted α-, β-, and γ-cyclodextrins containing trimethyl-, triethyl-, and tri-n-propylammonium substituent groups were synthesized and analyzed for utility as water-soluble chiral nuclear magnetic resonance (NMR) solvating agents. Racemic and enantiomerically pure (3-chloro-2-hydroxypropyl)trimethyl-, triethyl-, and tri-n-propyl ammonium chloride were synthesized from the corresponding trialkyl amine hydrochloride and either racemic or enantiomerically pure epichlorohydrin. The ammonium salts were then reacted with α-, β-, and γ-cyclodextrins at basic pH to provide the corresponding randomly substituted cationic cyclodextrins. The (1) H NMR spectra of a range of anionic, aromatic compounds was recorded with the cationic cyclodextrins. Cyclodextrins with a single stereochemistry at the hydroxy group on the (2-hydroxypropyl)trialkylammonium chloride substituent were often but not always more effective than the corresponding cyclodextrin in which the C-2 position was racemic. In several cases, the larger triethyl or tri-n-propyl derivatives were more effective than the corresponding trimethyl derivative at causing enantiomeric differentiation. None of the cyclodextrin derivatives were consistently the most effective for all of the anionic compounds studied. © 2016 Wiley Periodicals, Inc.

  8. An Extraordinary Accumulation of (-)-Pinoresinol in Cell-Free Extracts of Forsythia intermedia: Evidence for Enantiospecific Reduction of (+)-Pinoresinol

    Science.gov (United States)

    Katayama, Takeshi; Davin, Laurence B.; Lewis, Norman G.

    1992-01-01

    Stereoselective and enantiospecific transformation mechanisms in lignan biogenesis are only now yielding to scientific inquiry: it has been shown that soluble cell-free preparations from Forsythia intermedia catalysis the formation of the enantiomerically pure lignan, (-)-secoisolariciresinol, when incubated with coniferyl alcohol in the presence of NAD(P)H and H2O2. Surprisingly, (-)-pinoresinol also accumulates in this soluble cell-free assay mixture in greater than 96% enantiomeric excess, even though it is not the naturally occurring antipode present in Forsythia sp. But these soluble cell-free preparations do not engender stereoselective coupling; instead, racemic pinoresinols are first formed, catalysed by an H2O2-dependent peroxidase reaction. An enantiospecific NAD(P)H reductase then converts (+)- pinoresinol, and not the (-)-antipode, into (-)-secoisolariciresinol. Stereoselective syntheis of(+)-pinoresinol from E-coniferyl alcohol is, however, catalysed by an insoluble enzyme preparation in F. suspensa, obtained following removal of readily soluble and ionically bound enzymes; no exogenously supplied cofactors were required other than oxygen, although the reaction was stimulated by NAD-malate addition. Thus, the overall biochemical pathway to enantiomerically pure (-)-secoisolariciresinol has been delineated.

  9. Composition and Enantiomeric Analysis of the Essential Oil of the Fruits and the Leaves of Pistacia vera from Greece

    OpenAIRE

    Anastasia Tsokou; Katerina Georgopoulou; Eleni Melliou; Prokopios Magiatis; Eugenia Tsitsa

    2007-01-01

    The essential oils of the fruits and the leaves of pistachio (Pistacia vera L.) were analyzed by GC and GC/MS. Fresh unripe pistachio fruits were richer in essential oil (0.5 %, w/w) than the leaves (0.1 %, w/w). Twenty one compounds were identified in the essential oil of the fruits and the major components were (+)-α-pinene (54.6 %) and terpinolene (31.2 %). The enantiomeric ratio of the major constituents of the essential oil of the fruits was determined using chiral GC/MS and it was fo...

  10. Functional characterization of salt-tolerant microbial esterase WDEst17 and its use in the generation of optically pure ethyl (R)-3-hydroxybutyrate.

    Science.gov (United States)

    Wang, Yilong; Xu, Yongkai; Zhang, Yun; Sun, Aijun; Hu, Yunfeng

    2018-06-01

    The two enantiomers of ethyl 3-hydroxybutyrate are important intermediates for the synthesis of a great variety of valuable chiral drugs. The preparation of chiral drug intermediates through kinetic resolution reactions catalyzed by esterases/lipases has been demonstrated to be an efficient and environmentally friendly method. We previously functionally characterized microbial esterase PHE21 and used PHE21 as a biocatalyst to generate optically pure ethyl (S)-3-hydroxybutyrate. Herein, we also functionally characterized one novel salt-tolerant microbial esterase WDEst17 from the genome of Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085. Esterase WDEst17 was further developed as an efficient biocatalyst to generate (R)-3-hydroxybutyrate, an important chiral drug intermediate, with the enantiomeric excess being 99% and the conversion rate being 65.05%, respectively, after process optimization. Notably, the enantio-selectivity of esterase WDEst17 was opposite than that of esterase PHE21. The identification of esterases WDEst17 and PHE21 through genome mining of microorganisms provides useful biocatalysts for the preparation of valuable chiral drug intermediates. © 2018 Wiley Periodicals, Inc.

  11. Diastereoselectivity in scalemic tartrate/titanium epoxidations.

    Science.gov (United States)

    Brown, J M; Leppard, S J; Oakes, J; Thornthwaite, D

    2000-06-01

    Nonlinearity in the diastereoselectivity of epoxidation of allylic alcohols with mixtures of titanium isopropoxide, tertbutyl hydroperoxide, and diethyl tartrate was observed. Racemic and enantiomerically pure alcohols E-2-methyl-4-hexen-3-ol and E-1-methoxy-5-(O-tertbutyldimethylsilyloxy)-2-penten-4-ol were prepared. Epoxidation reactions were carried out with Ti(OPri)4 and ButOOH accompanied by diethyl tartrate of varying enantiomeric purity. The simplest explanation of these results is that a dimeric epoxidation reagent is involved, with significantly different reactivity for the homochiral and racemic forms. Copyright 2000 Wiley-Liss, Inc.

  12. Rehabilitation of pure alexia

    DEFF Research Database (Denmark)

    Starrfelt, Randi; Ólafsdóttir, Rannveig Rós; Arendt, Ida-Marie

    2013-01-01

    that pure alexia was an easy target for rehabilitation efforts. We review the literature on rehabilitation of pure alexia from 1990 to the present, and find that patients differ widely on several dimensions like alexia severity, and associated deficits. Many patients reported to have pure alexia......-designed and controlled studies of rehabilitation of pure alexia....

  13. Helix-helix inversion of an optically-inactive π-conjugated foldamer triggered by concentration changes of a single enantiomeric guest leading to a change in the helical stability.

    Science.gov (United States)

    Liu, Lijia; Ousaka, Naoki; Horie, Miki; Mamiya, Fumihiko; Yashima, Eiji

    2016-09-27

    A preferred-handed helicity induced in an optically-inactive poly(phenyleneethynylene)-based foldamer bearing carboxylic acid pendants upon complexation with a single enantiomeric diamine was subsequently inverted into the opposite helix upon further addition of the diamine, accompanied by a remarkable change in the stability of the helices.

  14. Two Genomic Regions Involved in Catechol Siderophore Production by Erwinia carotovora

    Science.gov (United States)

    Bull, Carolee T.; Ishimaru, Carol A.; Loper, Joyce E.

    1994-01-01

    Two regions involved in catechol biosynthesis (cbs) of Erwinia carotovora W3C105 were cloned by functional complementation of Escherichia coli mutants that were deficient in the biosynthesis of the catechol siderophore enterobactin (ent). A 4.3-kb region of genomic DNA of E. carotovora complemented the entB402 mutation of E. coli. A second genomic region of 12.8 kb complemented entD, entC147, entE405, and entA403 mutations of E. coli. Although functions encoded by catechol biosynthesis genes (cbsA, cbsB, cbsC, cbsD, and cbsE) of E. carotovora were interchangeable with those encoded by corresponding enterobactin biosynthesis genes (entA, entB, entC, entD, and entE), only cbsE hybridized to its functional counterpart (entE) in E. coli. The cbsEA region of E. carotovora W3C105 hybridized to genomic DNA of 21 diverse strains of E. carotovora but did not hybridize to that of a chrysobactin-producing strain of Erwinia chrysanthemi. Strains of E. carotovora fell into nine groups on the basis of sizes of restriction fragments that hybridized to the cbsEA region, indicating that catechol biosynthesis genes were highly polymorphic among strains of E. carotovora. PMID:16349193

  15. The "racemic approach" in the evaluation of the enantiomeric NorA efflux pump inhibition activity of 2-phenylquinoline derivatives.

    Science.gov (United States)

    Carotti, Andrea; Ianni, Federica; Sabatini, Stefano; Di Michele, Alessandro; Sardella, Roccaldo; Kaatz, Glenn W; Lindner, Wolfgang; Cecchetti, Violetta; Natalini, Benedetto

    2016-09-10

    Among the mechanisms adopted by bacteria, efflux pumps (EPs) have been recognized as being significantly involved in contributing to resistance to commonly used antibacterial agents. However, little is known about their three-dimensional structures or the steric requirements for their inhibition. Lack of such knowledge includes NorA, one of the most studied Staphylococcus aureus EPs. In the present study, the use of two commercialized Cinchona alkaloid-based zwitterionic chiral stationary phases allowed the enantioseparation of four 2-((2-(4-propoxyphenyl)quinolin-4-yl)oxy)alkylamines 1-4 previously found to be potent S. aureus NorA efflux pump inhibitors when tested as racemates. In the identified optimal polar-ionic conditions (MeOH/THF/H2O-49/49/2 (v/v/v)+25mM formic acid, 12.5mM diethylamine), repeated consecutive injections of 1 allowed the isolation of sufficient amount of its enantiomers (2.6mg and 2.8mg, for (R)-1 and (S)-1, respectively) and then to evaluate their ability to inhibit the S. aureus NorA efflux pump. The biological evaluation highlighted the main contribution of the (R)-1 enantiomer to both the EtBr efflux inhibition and synergistic effect with against SA-1199B (norA+/A116E GrlA) respect to the racemate activity. The comparison between the experimental electronic circular dichroism and the time-dependent density functional theory calculations spectra of the two isolated enantiomeric fractions allowed for all compounds a clear and easy assignment of the enantiomeric elution order. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. PHENYLSULFONYL-SUBSTITUTED 5-ALKOXY-2(5H)-FURANONES - A NEW CLASS OF HIGHLY REACTIVE CHIRAL DIENOPHILES

    NARCIS (Netherlands)

    DEJONG, JC; VANDENBERG, KJ; FERINGA, BL; van Leusen, A.M.

    1991-01-01

    The synthesis of enantiomerically pure (5S)-5-(d-menthyloxy)-4-(phenylsulfonyl)-2(5H)-furanone (4) and the application of 4 as efficient dienophile in Diels-Alder reactions under mild conditions with enantioselectivities > 98% e.e. are described.

  17. Complex regulation of AprA metalloprotease in Pseudomonas fluorescens M114: evidence for the involvement of iron, the ECF sigma factor, PbrA and pseudobactin M114 siderophore.

    Science.gov (United States)

    Maunsell, Bláithín; Adams, Claire; O'Gara, Fergal

    2006-01-01

    In the soil bacterium Pseudomonas fluorescens M114, extracellular proteolytic activity and fluorescent siderophore (pseudobactin M114) production were previously shown to be co-ordinately negatively regulated in response to environmental iron levels. An iron-starvation extracytoplasmic function sigma factor, PbrA, required for the transcription of siderophore biosynthetic genes, was also implicated in M114 protease regulation. The current study centred on the characterization and genetic regulation of the gene(s) responsible for protease production in M114. A serralysin-type metalloprotease gene, aprA, was identified and found to encode the major, if not only, extracellular protease produced by this strain. The expression of aprA and its protein product were found to be subject to complex regulation. Transcription analysis confirmed that PbrA was required for full aprA transcription under low iron conditions, while the ferric uptake regulator, Fur, was implicated in aprA repression under high iron conditions. Interestingly, the iron regulation of AprA was dependent on culture conditions, with PbrA-independent AprA-mediated proteolytic activity observed on skim milk agar supplemented with yeast extract, when supplied with iron or purified pseudobactin M114. These effects were not observed on skim milk agar without yeast extract. PbrA-independent aprA expression was also observed from a truncated transcriptional fusion when grown in sucrose asparagine tryptone broth supplied with iron or purified pseudobactin M114. Thus, experimental evidence suggested that iron mediated its effects via transcriptional activation by PbrA under low iron conditions, while an as-yet-unidentified sigma factor(s) may be required for the PbrA-independent aprA expression and AprA proteolytic activity induced by siderophore and iron.

  18. (S)-1-Aminoindane : synthesis by chirality transfer using (R)-phenylglycine amide as chiral auxiliary

    NARCIS (Netherlands)

    Uiterweerd, Patrick G.H.; Sluis, Marcel van der; Kaptein, Bernard; Lange, Ben de; Kellogg, Richard M.; Broxterman, Quirinus B.

    2003-01-01

    A practical asymmetric synthesis of nearly enantiomerically pure (S)-1-aminoindane has been developed. The key step involves the diastereoselective heterogeneous metal-catalyzed reduction of the ketimine of 1-indanone with the chiral auxiliary (R)-phenylglycine amide. The selectivity of the

  19. Relevance and bio-catalytic strategies for the kinetic resolution of ketoprofen towards dexketoprofen.

    Science.gov (United States)

    Toledo, María Victoria; Briand, Laura Estefanía

    2017-11-10

    This review presents the most relevant investigations concerning the biocatalytic kinetic resolution of racemic ketoprofen to dexketoprofen for the last 22 years. The advantages related to the administration of the dex-enantiomer in terms of human health, the so called "chiral switch" in the pharmaceutical industry and the sustainability of biotransformations have been the driving forces to develop innovative technology to obtain dexketoprofen. In particular, the kinetic resolution of racemic ketoprofen through enantiomeric esterification and hydrolysis using lipases as biocatalysts are thoroughly revised and commented upon. In this context, the biocatalysts, acyl-acceptors (alcohols), reaction conditions, conversion, enantiomeric excess, and enantiomeric ratio among others are discussed. Moreover, the investigations concerning scaling up processes in order to obtain an optically pure enantiomer of the profen are presented. Finally, some guidelines about perspectives of the technology and research opportunities are given.

  20. Color Spectrum Properties of Pure and Non-Pure LATEX in Discriminating Rubber Clone Series

    International Nuclear Information System (INIS)

    Noor Aishah Khairuzzaman; Hadzli Hashim; Nina Korlina Madzhi; Noor Ezan Abdullah; Faridatul Aima Ismail; Ahmad Faiz Sampian; Azhana Fatnin Che Will

    2015-01-01

    A study of color spectrum properties for pure and non-pure latex in discriminating rubber clone series has been presented in this paper. There were five types of clones from the same series being used as samples in this study named RRIM2002, RRIM2007, RRIM2008, RRIM2014, and RRIM3001. The main objective is to identify the significant color spectrum (RGB) from pure and non-pure latex that can discriminate rubber clone series. The significant information of color spectrum properties for pure and non-pure latex is determined by using spectrometer and Statistical Package for the Social Science (SPSS). Visible light spectrum (VIS) is used as a radiation light of the spectrometer to emit light to the surface of the latex sample. By using SPSS software, the further numerical analysis of color spectrum properties is being conducted. As the conclusion, blue color spectrum for non-pure is able to discriminate for all rubber clone series whereas only certain color spectrum can differentiate several clone series for pure latex. (author)

  1. Tandem Rh-Catalyzed Oxidative C-H Olefination and Cyclization of Enantiomerically Enriched Benzo-1,3-Sulfamidates: Stereoselective Synthesis of trans-1,3-Disubstituted Isoindolines.

    Science.gov (United States)

    Achary, Raghavendra; Jung, In-A; Lee, Hyeon-Kyu

    2018-04-06

    A tandem process, involving Rh(III)-catalyzed oxidative C-H olefination of enantiomerically enriched 4-aryl-benzo-1,3-sulfamidates and subsequent intramolecular aza-Michael cyclization has been developed. The reaction produces trans-benzosulfamidate-fused-1,3-disubstituted isoindolines as major products, in which the configurational integrity of the stereogenic center in the starting material is preserved. Further transformations of the benzosulfamidate-fused-1,3-disubstituted isoindolines are described.

  2. Chiral Synthons in Pesticide Syntheses

    NARCIS (Netherlands)

    Feringa, Bernard

    1988-01-01

    The use of chiral synthons in the preparation of enantiomerically pure pesticides is described in this chapter. Several routes to chiral synthons based on asymmetric synthesis or on natural products are illustrated. Important sources of chiral building blocks are reviewed. Furthermore the

  3. Enantiomeric switching of chiral metamaterial for terahertz polarization modulation employing vertically deformable MEMS spirals

    Science.gov (United States)

    Kan, Tetsuo; Isozaki, Akihiro; Kanda, Natsuki; Nemoto, Natsuki; Konishi, Kuniaki; Takahashi, Hidetoshi; Kuwata-Gonokami, Makoto; Matsumoto, Kiyoshi; Shimoyama, Isao

    2015-10-01

    Active modulation of the polarization states of terahertz light is indispensable for polarization-sensitive spectroscopy, having important applications such as non-contact Hall measurements, vibrational circular dichroism measurements and anisotropy imaging. In the terahertz region, the lack of a polarization modulator similar to a photoelastic modulator in the visible range hampers expansion of such spectroscopy. A terahertz chiral metamaterial has a huge optical activity unavailable in nature; nevertheless, its modulation is still challenging. Here we demonstrate a handedness-switchable chiral metamaterial for polarization modulation employing vertically deformable Micro Electro Mechanical Systems. Vertical deformation of a planar spiral by a pneumatic force creates a three-dimensional spiral. Enantiomeric switching is realized by selecting the deformation direction, where the polarity of the optical activity is altered while maintaining the spectral shape. A polarization rotation as high as 28° is experimentally observed, thus providing a practical and compact polarization modulator for the terahertz range.

  4. Equilibrium Fe isotope fractionation between inorganic aqueous Fe(III) and the siderophore complex, Fe(III)-desferrioxamine B

    DEFF Research Database (Denmark)

    Dideriksen, Knud; Baker, Joel A.; Stipp, Susan Louise Svane

    2008-01-01

    be controlled by isotope fractionation between the free and complexed iron.We have determined the equilibrium Fe isotope fractionation induced by organic ligand activity in experiments with solutions having co-existing inorganic Fe(III) species and siderophore complexes, Fedesferrioxamine B (at pH 2). The two......-type fractionation during precipitation, this experiment yielded an isotope fractionation factor of a56Fesolution-solid=1.00027. Calculations based on these results indicate that isotopic re-equilibration is unlikely to significantly affect our determined equilibrium Fe isotope fractionation between inorganically...... and organically complexed Fe. To determine the equilibrium Fe isotope fractionation between inorganically and organically bound Fe(III), experiments with variable proportions of inorganic Fe were carried out at 25 °C. Irrespective of the proportion of inorganic Fe, equilibrium fractionation factors were within...

  5. Enantiomeric fraction and isomeric composition to assess sources of DDT residues in soils.

    Science.gov (United States)

    Bosch, Carme; Grimalt, Joan O; Fernández, Pilar

    2015-11-01

    Chiral pesticides such as o,p'-DDT can undergo enantioselective microbial degradation in soil. Hence, the enantiomeric fraction (EF) of o,p'-DDT was used as an approach to assess potential recent inputs of DDT in the lower part of the Ebro River basin (NE Spain), a region heavily impacted by agricultural and industrial activities, including a dicofol production and a chloro-alkali plants. The EFs of five out of nineteen soils were not different from the racemic value (0.505±0.010), confirming that the Ebro River and some of its tributaries, Segre and Cinca rivers, transported fresh DDT residues despite its ban in Spain during the 90 s. o,p'-DDT/p,p'-DDT ratios in soils suggest that recent use of technical DDT and/or DDT-contaminated dicofol may be responsible for the fresh DDT inputs in the Segre River, while in the Ebro River, they indicate a dominant contribution of technical DDT, likely related to the residues accumulated by the chloro-alkali plant discharges. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Sixth form pure mathematics

    CERN Document Server

    Plumpton, C

    1968-01-01

    Sixth Form Pure Mathematics, Volume 1, Second Edition, is the first of a series of volumes on Pure Mathematics and Theoretical Mechanics for Sixth Form students whose aim is entrance into British and Commonwealth Universities or Technical Colleges. A knowledge of Pure Mathematics up to G.C.E. O-level is assumed and the subject is developed by a concentric treatment in which each new topic is used to illustrate ideas already treated. The major topics of Algebra, Calculus, Coordinate Geometry, and Trigonometry are developed together. This volume covers most of the Pure Mathematics required for t

  7. Direct detection of fungal siderophores on bats with white-nose syndrome via fluorescence microscopy-guided ambient ionization mass spectrometry.

    Science.gov (United States)

    Mascuch, Samantha J; Moree, Wilna J; Hsu, Cheng-Chih; Turner, Gregory G; Cheng, Tina L; Blehert, David S; Kilpatrick, A Marm; Frick, Winifred F; Meehan, Michael J; Dorrestein, Pieter C; Gerwick, Lena

    2015-01-01

    White-nose syndrome (WNS) caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection.

  8. Non-critical pure spinor superstrings

    International Nuclear Information System (INIS)

    Adam, Ido; Grassi, Pietro Antonio; Mazzucato, Luca; Oz, Yaron; Yankielowicz, Shimon

    2007-01-01

    We construct non-critical pure spinor superstrings in two, four and six dimensions. We find explicitly the map between the RNS variables and the pure spinor ones in the linear dilaton background. The RNS variables map onto a patch of the pure spinor space and the holomorphic top form on the pure spinor space is an essential ingredient of the mapping. A basic feature of the map is the requirement of doubling the superspace, which we analyze in detail. We study the structure of the non-critical pure spinor space, which is different from the ten-dimensional one, and its quantum anomalies. We compute the pure spinor lowest lying BRST cohomology and find an agreement with the RNS spectra. The analysis is generalized to curved backgrounds and we construct as an example the non-critical pure spinor type IIA superstring on AdS 4 with RR 4-form flux

  9. Genetic diversity of siderophore-producing bacteria of tobacco rhizosphere Diversidade genética de bactérias de rizosfera de tabaco produtoras de sideróforos

    Directory of Open Access Journals (Sweden)

    Fang Tian

    2009-06-01

    Full Text Available The genetic diversity of siderophore-producing bacteria of tobacco rhizosphere was studied by amplified ribosomal DNA restriction analysis (ARDRA, 16S rRNA sequence homology and phylogenetics analysis methods. Studies demonstrated that 85% of the total 354 isolates produced siderophores in iron limited liquid medium. A total of 28 ARDRA patterns were identified among the 299 siderophore-producing bacterial isolates. The 28 ARDRA patterns represented bacteria of 14 different genera belonging to six bacterial divisions, namely ?-, ?-, ?-Proteobacteria, Sphingobacteria, Bacilli,and Actinobacteria. Especially, ?-Proteobacteria consisting of Pseudomonas, Enterobacter, Serratia, Pantoea, Erwinia and Stenotrophomonasgenus encountered 18 different ARDRA groups. Results also showed a greater siderophore-producing bacterial diversity than previous researches. For example, Sphingobacterium (isolates G-2-21-1 and G-2-27-2, Pseudomonas poae (isolate G-2-1-1, Enterobacter endosymbiont (isolates G-2-10-2 and N-5-10, Delftia acidovorans (isolate G-1-15, and Achromobacter xylosoxidans (isolates N-46-11HH and N-5-20 were reported to be able to producesiderophores under low-iron conditions for the first time. Gram-negative isolates were more frequently encountered, with more than 95% total frequency. For Gram-positive bacteria, the Bacillus and Rhodococcus were the only two genera, with 1.7% total frequency. Furthermore, the Pseudomonas and Enterobacter were dominant in this environment, with 44.5% and 24.7% total frequency, respectively. It was also found that 75 percent of the isolates that had the high percentages of siderophore units (% between 40 and 60 belonged to Pseudomonas. Pseudomonas sp. G-229-21 screened out in this study may have potential to apply to low-iron soil to prevent plant soil-borne fungal pathogen diseases.A diversidade genética de bactérias de rizosfera de tabaco produtoras de sideróforos foi estudada por meio da técnica de análise de

  10. Effect of Siderophore on Iron Availability in a Diatom and a Dinoflagellate Species: Contrasting Response in Associated Bacteria

    Directory of Open Access Journals (Sweden)

    Nicolas Sanchez

    2018-04-01

    Full Text Available Organic ligands play a key role controlling trace metal bioavailability in the world's oceans, yet the species-specific requirements determining whether certain iron forms can be metabolized largely remain unclear. Siderophores are considered relevant within the pool of ligands keeping iron soluble. We used desferrioxamine B (DFB to study the siderophore's effect on cultures of Skeletonema costatum and Alexandrium catenella. The experimental approach used semi-continuous additions of iron(II and DFB over time, reaching final concentrations of 1 and 10 nM Fe and 10–10,000 nM DFB. The negative effect of DFB on growth in S. costatum was evident and sharp until day 9 for treatments above 500 nM. Delayed growth occurred at 10,000 nM, reaching ~80% of cell density in Controls under both iron conditions. Alexandrium catenella exhibited a less severe negative effect of DFB on growth, only significant at 10,000 nM, while growth was enhanced at lowest DFB. Total bacterial abundance in diatom and dinoflagellate cultures presented inverse trends. While negatively correlated to DFB in diatom cultures, bacteria showed highest abundances in high DFB treatments in dinoflagellate cultures. Delayed growth exhibited in S. costatum at the highest DFB, indicates that favorable changes for Fe uptake occurred over time, suggesting the involvement of other mechanisms facilitating the diatom cell membrane reduction. Overall, unaffected growth in A. catenella suggests that this species can use FeDFB and therefore has the capacity to access strongly complexed Fe sources. Contrasting responses in the bacterial community associated with each species highlight the complexity of these interactions, while suggesting that for A. catenella it may represent an advantage for acquiring Fe. These results demonstrated the capacity for different uptake strategies among phytoplankton species of different functional groups and underlines the necessity to broaden the study of iron

  11. Enantioseparation of linear and cyclic chiral bis(phenethyl)amines by means of cyclodextrin-modified capillary electrophoresis.

    Science.gov (United States)

    Wedig, M; Thunhorst, M; Laug, S; Decker, M; Lehmann, J; Holzgrabe, U

    2001-09-01

    For two years drugs introduced to the market have had- to be enantiomerically pure. Rapid and cheap methods of high reproducibility must, therefore, be available for evaluation of enantiomeric purity. Within the framework of a larger project dealing with chiral recognition of phenethylamines by means of native and derivatized cyclodextrins it was intended to find capillary electrophoresis methods suitable for separation of the enantiomers of chiral bis(phenethyl)amines and their corresponding cyclic analogues, within 10 min, using small amounts of a chiral selector, to save time and money. Heptakis(2,3-O-diacetyl-6-sulfato)beta-CD was found to be the most promising candidate most often fulfilling these requirements.

  12. Direct detection of fungal siderophores on bats with white-nose syndrome via fluorescence microscopy-guided ambient ionization mass spectrometry

    Science.gov (United States)

    Mascuch, Samantha J.; Moree, Wilna J.; Cheng-Chih Hsu, Cheng-Chih; Turner, Gregory G.; Cheng, Tina L.; Blehert, David S.; Kilpatrick, A. Marm; Frick, Winifred F.; Meehan, Michael J.; Dorrestein, Pieter C.; Gerwick, Lena

    2015-01-01

    White-nose syndrome (WNS) caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection.

  13. Direct detection of fungal siderophores on bats with white-nose syndrome via fluorescence microscopy-guided ambient ionization mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Samantha J Mascuch

    Full Text Available White-nose syndrome (WNS caused by the pathogenic fungus Pseudogymnoascus destructans is decimating the populations of several hibernating North American bat species. Little is known about the molecular interplay between pathogen and host in this disease. Fluorescence microscopy ambient ionization mass spectrometry was used to generate metabolic profiles from the wings of both healthy and diseased bats of the genus Myotis. Fungal siderophores, molecules that scavenge iron from the environment, were detected on the wings of bats with WNS, but not on healthy bats. This work is among the first examples in which microbial molecules are directly detected from an infected host and highlights the ability of atmospheric ionization methodologies to provide direct molecular insight into infection.

  14. Mixtures of maximally entangled pure states

    Energy Technology Data Exchange (ETDEWEB)

    Flores, M.M., E-mail: mflores@nip.up.edu.ph; Galapon, E.A., E-mail: eric.galapon@gmail.com

    2016-09-15

    We study the conditions when mixtures of maximally entangled pure states remain entangled. We found that the resulting mixed state remains entangled when the number of entangled pure states to be mixed is less than or equal to the dimension of the pure states. For the latter case of mixing a number of pure states equal to their dimension, we found that the mixed state is entangled provided that the entangled pure states to be mixed are not equally weighted. We also found that one can restrict the set of pure states that one can mix from in order to ensure that the resulting mixed state is genuinely entangled. Also, we demonstrate how these results could be applied as a way to detect entanglement in mixtures of the entangled pure states with noise.

  15. Synthetic Studies on Highly Functionalized {gamma} - Lactam Natural Products, PI-091 and Epolactaene; Takannosei {gamma}-rakutamugata tennen yuki kagobutsu, PI-091 no zengosei oyobi eporakutaen no gosei kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Shiraki, Ryota.; Tadano, Kin`ichi. [Keio University, Kanagawa (Japan). Department of Applied Chemistry

    1999-01-10

    From the aspect of their unique structures and important biological activities, highly functionalizd {gamma} -lactam naural products have attracted much atention to synthetic chemist in recent years. On the other hand, the usefulness of carbohydrae-derived enantiomerically pure building blocks to enantioselective synthesis of complex natural products has been ell recognized. In this paper, we describe the synthesis of two highly functionalized ganma-lactam natural products, PI-091 and epolactaene, in enantiomerically pure form. PI-091 and epolactaene, in enantiomerically pure form. PI-091 was isolated from pacilomyces sp. F-3430 by the group of Taisho Pharmaceutical Co. in 1990, and exhibits a platelet aggregation inhibitory activity against rabbit platelet in vitro. We started our total synthesis of PI-091 from D-glucose. In the early stag of this synthesis, all carbons in PI-091 were asembled by featuring an aldol carbon-elongation. Then an intramolecular ketalization and successive dehydration ave a 2,4-alkylated furan, which was transformed to a ganma-lactam skeletonby the photochemical singlet oxygen addition to the furan derivative, followed by a ganma-lactone-ganma-lactam transformation. The absolute structure of PI-091 was determined through the present synthesis. Epolactaene was isolated by Osada etal. from the culture broth of Penicillium sp. BM1689-P in 1995. It shows the neurite outgrowth ctivity of a human neuroblastoma cell line, SH-SY5Y cells. Owing tothe similarity of their structures between PI-091 and epolactaene, we planned tosynthesize epolactaene using the similar synthtic pathway employed to the total synthesis of PI-091. The synthetic achievements on these novel antibiotics are described herein. (author)

  16. Studies on the Diels-Alder adduct from cyclopentadiene and p-benzoquinone: Biotransformation, enantiomeric excess and absolute configuration

    Directory of Open Access Journals (Sweden)

    Felipe Camargo Braga

    2012-06-01

    Full Text Available The use of microorganisms or isolated enzymes in synthetic routes has been extensively used by industry and academic research. A great advantage of biotransformation in a synthetic route is highly regio- and enatiosselective control, which can be achieved through microbial catalyzed reaction. Biotransformation is one of the most efficient methods in a production of high purity optical compounds and development of efficient routes for target molecules. Biotransformation by Mucor ramosissimus of enedione 1 gave the keto-alcohol (--2 with enantiomeric excess (ee>99,9% (determined by 1H NMR with [(+-Eu(hfc]3 and their epimer (--3. Determination of the absolute configuration of epimer (--3 was accomplished by controlled reaction and measuring of optical rotation (scheme 1. The fungus M. ramosissimus is a promising species to perform desymmetrization of diketones with high enantioselectivity.

  17. Asymmetric 1,3-Dipolar Cycloadditions to 5-(R)-Menthyloxy-2(5H)-Furanone

    NARCIS (Netherlands)

    Rispens, Minze T.; Keller, Erik; Lange, Ben de; Zijlstra, Robert W.J.; Feringa, Bernard

    Various diazo compounds, nitrile oxides, nitrones and azomethine ylides were examined in 1,3-dipolar cycloadditions to enantiomerically pure 5-(R)-menthyloxy-2(5H)-furanone 1a. Pyrazoline 9 was obtained in 100% c.y. as a mixture of 2 diastereoisomers in ratios up to 72 : 28, whereas pyrazoline 16

  18. Enantiomeric analogues of SCH 23390 as new probes for behavioral interactions between D-1 and D-2 dopaminergic function

    International Nuclear Information System (INIS)

    Waddington, J.L.; Mashurano, M.; Molloy, A.G.; O'Boyle, K.M.

    1986-01-01

    The purposes of this article are to describe the properties of some newer selective D 1 agents, and to characterize behavioral responses to a D 1 agonist in the intact adult rat. R- and S-SKandF 83566 and other new 1-phenyl-1H-3-benzazephines as selective D 1 agents are discussed. The displacement of 3 H-SCH 23390 from human brain D 1 receptors, in comparison with displacement of 3 H-piflutixol and 3 H-spiperone is shown. Enantiomeric induction of grooming and other behaviors by R- and S-SKandF 38393 is examined. Sections are also devoted to pharmacological characterization of behavioral responses to SKandF 38393 and to D 1 : D 2 receptor systems and the regulation of dopaminergic behaviors

  19. Asimetric synthesis of alpha-phenyl amino acids; Sintesis asimetrica de alfa-fenilaminoacidos

    Energy Technology Data Exchange (ETDEWEB)

    Caltiviela, C.; Diaz de Villegas, M.D.; Galvez, J.A.; Lapena, Y. [Departamento de Quimica Organica, Universidad de Zaragoza, Zaragoza (Spain)

    1994-12-31

    A new synthetic strategy to obtain alpha-phenyl amino acids in enantiomerically pure form is described. The new route is based on the highly diastereoselective alkylation of (1S,2R,4R)-10-dicyclohexylsulfamoylisobornyl 2-phenylcianoacetate and subsequent curtis type rearrangement of the alkylated compound with total retention of configuration. 17 refs

  20. A metal-free general procedure for oxidation of secondary amines to nitrones.

    Science.gov (United States)

    Gella, Carolina; Ferrer, Eric; Alibés, Ramon; Busqué, Félíx; de March, Pedro; Figueredo, Marta; Font, Josep

    2009-08-21

    An efficient and metal-free protocol for direct oxidation of secondary amines to nitrones has been developed, using Oxone in a biphasic basic medium as the sole oxidant. The method is general and tolerant with other functional groups or existing stereogenic centers, providing rapid access to enantiomerically pure compounds in good yields.

  1. Enantiomeric determination of DOPA in dietary supplements containing Mucuna pruriens by liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Hasegawa, Takashi; Takahashi, Kazunaga; Fukiwake, Tomohide; Saijo, Masaaki; Motoki, Yuji

    2013-01-01

    We developed a simple and rapid liquid chromatography/mass spectrometry (LC/MS) method for the enantiomeric determination of DOPA in dietary supplements containing Mucuna pruriens. L- and D-DOPA were ultrasonically extracted with 1% formic acid aqueous solution. The isolated extracts were analyzed by LC/MS using a Crownpak CR (-) column at 30℃. The mass spectrometer was operated in the positive mode of electrospray ionization, and the mobile phase was aqueous formic acid (pH 2.0). L-DOPA-ring-d3 was used as an internal standard. The method was validated for a dietary supplement spiked with L- and D-DOPA at 50 and 500 μg/g, respectively, and the recoveries of the DOPA enantiomers were between 97.5% and 101.3%. Relative standard deviation values of repeatability and intermediate precision were less than 7%. The method was applied to 14 dietary supplements. L-DOPA was detected in these supplements in the range of 0.88-12.8 mg/unit. D-DOPA was not detected.

  2. 2-Methylbutyl acetate in wines: Enantiomeric distribution and sensory impact on red wine fruity aroma.

    Science.gov (United States)

    Cameleyre, Margaux; Lytra, Georgia; Tempere, Sophie; Barbe, Jean-Christophe

    2017-12-15

    Enantiomers of 2-methylbutyl acetate were assayed in red and white commercial wines from various vintages and origins, using chiral gas chromatography (γ-cyclodextrin), revealing the exclusive presence of the S-enantiomeric form. Results also confirmed that (S)-2-methylbutyl acetate levels were generally higher in red than white wines of the same age, and that acetate levels increased gradually during ageing. Olfactory threshold of (S)-2-methylbutyl acetate was evaluated at 313µg/L in dilute alcohol solution (12% v/v) and 1083µg/L in a fruity aromatic reconstitution, reflecting its presence in wines at subthreshold concentrations. At concentrations considerably lower than its olfactory threshold, 2-methylbutyl acetate was associated with blackberry-fruit and banana notes. It was also revealed that, even at subthreshold concentrations, this compound had a modification on the perception of fruity aromas in the matrices studied. Sensory profiles highlighted, for the first time, its specific contribution to black-, fresh-, and jammy-fruit notes, despite its subthreshold concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Perspectives on the Pure-Tone Audiogram.

    Science.gov (United States)

    Musiek, Frank E; Shinn, Jennifer; Chermak, Gail D; Bamiou, Doris-Eva

    The pure-tone audiogram, though fundamental to audiology, presents limitations, especially in the case of central auditory involvement. Advances in auditory neuroscience underscore the considerably larger role of the central auditory nervous system (CANS) in hearing and related disorders. Given the availability of behavioral audiological tests and electrophysiological procedures that can provide better insights as to the function of the various components of the auditory system, this perspective piece reviews the limitations of the pure-tone audiogram and notes some of the advantages of other tests and procedures used in tandem with the pure-tone threshold measurement. To review and synthesize the literature regarding the utility and limitations of the pure-tone audiogram in determining dysfunction of peripheral sensory and neural systems, as well as the CANS, and to identify other tests and procedures that can supplement pure-tone thresholds and provide enhanced diagnostic insight, especially regarding problems of the central auditory system. A systematic review and synthesis of the literature. The authors independently searched and reviewed literature (journal articles, book chapters) pertaining to the limitations of the pure-tone audiogram. The pure-tone audiogram provides information as to hearing sensitivity across a selected frequency range. Normal or near-normal pure-tone thresholds sometimes are observed despite cochlear damage. There are a surprising number of patients with acoustic neuromas who have essentially normal pure-tone thresholds. In cases of central deafness, depressed pure-tone thresholds may not accurately reflect the status of the peripheral auditory system. Listening difficulties are seen in the presence of normal pure-tone thresholds. Suprathreshold procedures and a variety of other tests can provide information regarding other and often more central functions of the auditory system. The audiogram is a primary tool for determining type

  4. Generalized pure Lovelock gravity

    Science.gov (United States)

    Concha, Patrick; Rodríguez, Evelyn

    2017-11-01

    We present a generalization of the n-dimensional (pure) Lovelock Gravity theory based on an enlarged Lorentz symmetry. In particular, we propose an alternative way to introduce a cosmological term. Interestingly, we show that the usual pure Lovelock gravity is recovered in a matter-free configuration. The five and six-dimensional cases are explicitly studied.

  5. Enantiomeric separation of complex organic molecules produced from irradiation of interstellar/circumstellar ice analogs

    Science.gov (United States)

    Nuevo, M.; Meierhenrich, U. J.; D'Hendecourt, L.; Muñoz Caro, G. M.; Dartois, E.; Deboffle, D.; Thiemann, W. H.-P.; Bredehöft, J.-H.; Nahon, L.

    Irradiation of interstellar/circumstellar ice analogs by ultraviolet (UV) light followed by warm up in the laboratory leads to the formation of complex organic molecules, stable at room temperature. Hydrolysis of the room temperature residue releases amino acids, the building blocks of proteins. These amino acids exist in two different forms (L and D), but proteins encountered in living beings consist exclusively of L enantiomers. The origin of this property, called homochirality, is still unknown. Amino acids can be detected and quantified by chemical techniques such as chiral gas chromatography coupled with mass spectrometry (GC-MS). Enantiomers of chiral organics are also known to interact selectively with circularly polarized light (CPL), leading to a selective production or destruction of the final compounds. This paper describes how we settled an experiment where amino acids are formed by irradiation of interstellar/circumstellar ice analogs with ultraviolet (UV) CPL, produced by a synchrotron radiation beamline, which allowed us to quantify the effect of such polarized light on the production of amino acids. These results can be compared to the enantiomeric excesses measured in primitive meteorites such as Murchison.

  6. Generalized pure Lovelock gravity

    Directory of Open Access Journals (Sweden)

    Patrick Concha

    2017-11-01

    Full Text Available We present a generalization of the n-dimensional (pure Lovelock Gravity theory based on an enlarged Lorentz symmetry. In particular, we propose an alternative way to introduce a cosmological term. Interestingly, we show that the usual pure Lovelock gravity is recovered in a matter-free configuration. The five and six-dimensional cases are explicitly studied.

  7. Musical notation reading in pure alexia

    DEFF Research Database (Denmark)

    Starrfelt, Randi; Wong, Yetta K.

    2017-01-01

    Pure alexia (PA) is an acquired reading disorder following lesions to left ventral temporo-occipital cortex. Patients with PA read slowly but correctly, and show an abnormal effect of word length on RTs. However, it is unclear how pure alexia may affect musical notation reading. We report a pure...

  8. Siderophore cheating and cheating resistance shape competition for iron in soil and freshwater Pseudomonas communities.

    Science.gov (United States)

    Butaitė, Elena; Baumgartner, Michael; Wyder, Stefan; Kümmerli, Rolf

    2017-09-04

    All social organisms experience dilemmas between cooperators performing group-beneficial actions and cheats selfishly exploiting these actions. Although bacteria have become model organisms to study social dilemmas in laboratory systems, we know little about their relevance in natural communities. Here, we show that social interactions mediated by a single shareable compound necessary for growth (the iron-scavenging pyoverdine) have important consequences for competitive dynamics in soil and pond communities of Pseudomonas bacteria. We find that pyoverdine non- and low-producers co-occur in many natural communities. While non-producers have genes coding for multiple pyoverdine receptors and are able to exploit compatible heterologous pyoverdines from other community members, producers differ in the pyoverdine types they secrete, offering protection against exploitation from non-producers with incompatible receptors. Our findings indicate that there is both selection for cheating and cheating resistance, which could drive antagonistic co-evolution and diversification in natural bacterial communities.Lab strains of Pseudomonas are model systems for the evolution of cooperation over public goods (iron-scavenging siderophores). Here, Butaitė et al. add ecological and evolutionary insight into this system by showing that cheating and resistance to cheating both shape competition for iron in natural Pseudomonas communities.

  9. Direct resolution and quantitative analysis of flurbiprofen enantiomers using microcrystalline cellulose triacetate plates: applications to the enantiomeric purity control and optical isomer determination in widely consumed drugs.

    Science.gov (United States)

    Del Bubba, M; Checchini, L; Ciofi, L; Furlanetto, S; Lepri, L

    2014-01-01

    Flurbiprofen enantiomers have very different pharmacological properties, since the (S)-(+) form has a much higher anti-inflammatory activity than the (R)-(-) isomer, the latter being responsible for very undesirable side effects, such as gastrointestinal irritation. Based on the different biological properties of flurbiprofen enantiomers, the development of chiral chromatographic methods for the control of the enantiomeric purity is a very important topic. In this study the separation of flurbiprofen enantiomers was achieved using for the first time noncommercial MCTA layers with polyvinyl alcohol as binder, which gives to these plates a mechanical stability equivalent to that of marketed ones. Baseline resolution (α = 1.31; RS = 2.0) was obtained with ethanol-acetic acid solution (pH 3.0 ± 0.1; 60:40, v/v) as eluent and a migration distance of about 14.5 cm. Under these experimental conditions, the thin-layer chromatography determination of the enantiomeric purity of the pharmacologically active (S)-(+)-flurbiprofen in the presence of 1% of the undesired (R)-(-) form was demonstrated. Moreover, the quantitative analysis of flurbiprofen enantiomers was achieved, obtaining quantification limits and detection limits of 50 and 25 ng of each enantiomer applied to the plate, respectively. The method was succesfully applied to the enantiomer determination in widely consumed drugs, obtaining results consistent with the flurbiprofen content declared in the drug facts. Copyright © 2013 John Wiley & Sons, Ltd.

  10. Enantiomeric excesses induced in amino acids by ultraviolet circularly polarized light irradiation of extraterrestrial ice analogs: A possible source of asymmetry for prebiotic chemistry

    International Nuclear Information System (INIS)

    Modica, Paola; De Marcellus, Pierre; D'Hendecourt, Louis Le Sergeant; Meinert, Cornelia; Meierhenrich, Uwe J.; Nahon, Laurent

    2014-01-01

    The discovery of meteoritic amino acids with enantiomeric excesses of the L-form (ee L ) has suggested that extraterrestrial organic materials may have contributed to prebiotic chemistry and directed the initial occurrence of the ee L that further led to homochirality of amino acids on Earth. A proposed mechanism for the origin of ee L in meteorites involves an asymmetric photochemistry of extraterrestrial ices by UV circularly polarized light (CPL). We have performed the asymmetric synthesis of amino acids on achiral extraterrestrial ice analogs by VUV CPL, investigating the chiral asymmetry transfer at two different evolutionary stages at which the analogs were irradiated (regular ices and/or organic residues) and at two different photon energies (6.6 and 10.2 eV). We identify 16 distinct amino acids and precisely measure the L-enantiomeric excesses using the enantioselective GC × GC-TOFMS technique in five of them: α-alanine, 2,3-diaminopropionic acid, 2-aminobutyric acid, valine, and norvaline, with values ranging from ee L = –0.20% ± 0.14% to ee L = –2.54% ± 0.28%. The sign of the induced ee L depends on the helicity and the energy of CPL, but not on the evolutionary stage of the samples, and is the same for all five considered amino acids. Our results support an astrophysical scenario in which the solar system was formed in a high-mass star-forming region where icy grains were irradiated during the protoplanetary phase by an external source of CPL of a given helicity and a dominant energy, inducing a stereo-specific photochemistry.

  11. Absolute configuration and enantiomeric composition of partially resolved mandelic, atrolactic and lactic acids by {sup 1}H NMR of their (S)-2-methylbutyl esters

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Francisco A. da C.; Mendes, Maricleide P. de L.; Fonseca, Neuracy C. da, E-mail: fandrade@ufba.br [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Instituto de Quimica. Departamento de Quimica Organica

    2013-06-15

    The mandelic, atrolactic and lactic acid esters of the (S)-2-methyl-1-butanol were examined as diastereomeric derivatives for the stereochemical analysis of the mentioned acids by {sup 1}H nuclear magnetic resonance (NMR) at 300 MHz. The diastereomeric esters showed distinctive signals in the methylenic absorption range (O-CH{sub 2}-CH) of the alcoholic moieties. By spectral analysis at this region, absolute configurations were attributed, chemical shifts of the correspondent pro-(R) and pro-(S) hydrogens from the methylene group of the alcohol moiety were assigned and enantiomeric compositions were determined for the original partially resolved acids. (author)

  12. Pure homology of algebraic varieties

    OpenAIRE

    Weber, Andrzej

    2003-01-01

    We show that for a complete complex algebraic variety the pure component of homology coincides with the image of intersection homology. Therefore pure homology is topologically invariant. To obtain slightly more general results we introduce "image homology" for noncomplete varieties.

  13. Analysis of pure maple syrup consumers

    Science.gov (United States)

    Paul E. Sendak

    1974-01-01

    Virtually all of the pure maple syrup productim in the United States is in the northern states of Maine, Massachusetts, Michigan, New Hampshire, New York, Ohio, Pennsylvania, Vermont, and Wisconsin. Pure maple syrup users living in the maple production area and users living in other areas of the United States were asked a series of questions about their use of pure...

  14. Hammond Postulate Mirroring Enables Enantiomeric Enrichment of Phosphorus Compounds via Two Thermodynamically Interconnected Sequential Stereoselective Processes.

    Science.gov (United States)

    Rajendran, Kamalraj V; Nikitin, Kirill V; Gilheany, Declan G

    2015-07-29

    The dynamic resolution of tertiary phosphines and phosphine oxides was monitored by NMR spectroscopy. It was found that the stereoselectivity is set during the formation of the diastereomeric alkoxyphosphonium salts (DAPS), such that their initial diastereomeric excess (de) limits the final enantiomeric excess (ee) of any phosphorus products derived from them. However, (31)P NMR monitoring of the spontaneous thermal decomposition of the DAPS shows consistent diastereomeric self-enrichment, indicating a higher rate constant for decomposition of the minor diastereomer. This crucial observation was confirmed by reductive trapping of the unreacted enriched DAPS with lithium tri-sec-butylborohydride (commercially distributed as L-Selectride reagent) at different time intervals after the start of reaction, which gives progressively higher ee of the phosphine product with time. It is proposed that the Hammond postulate operates for both formation and decomposition of DAPS intermediate so that the lower rate of formation and faster subsequent collapse of the minor isomer are thermodynamically linked. This kinetic enhancement of kinetic resolution furnishes up to 97% ee product.

  15. Membrane-bound alcohol dehydrogenase is essential for glyceric acid production in Acetobacter tropicalis.

    Science.gov (United States)

    Habe, Hiroshi; Sato, Shun; Fukuoka, Tokuma; Kitamoto, Dai; Yakushi, Toshiharu; Matsushita, Kazunobu; Sakaki, Keiji

    2011-01-01

    Acetobacter tropicalis NBRC16470 can produce highly enantiomerically pure D-glyceric acid (D-GA; >99 % enantiomeric excess) from glycerol. To investigate whether membrane-bound alcohol dehydrogenase (mADH) is involved in GA production in A. tropicalis, we amplified part of the gene encoding mADH subunit I (adhA) using polymerase chain reaction and constructed an adhA-disrupted mutant of A. tropicalis (ΔadhA). Because ΔadhA did not produce GA, we confirmed that mADH is essential for the conversion of glycerol to GA. We also cloned and sequenced the entire region corresponding to adhA and adhB, which encodes mADH subunit II. The sequences showed high identities (84-86 %) with the equivalent mADH subunits from other Acetobacter spp.

  16. Fundamentals of the Pure Spinor Formalism

    CERN Document Server

    Hoogeveen, Joost

    2010-01-01

    This thesis presents recent developments within the pure spinor formalism, which has simplified amplitude computations in perturbative string theory, especially when spacetime fermions are involved. Firstly the worldsheet action of both the minimal and the non-minimal pure spinor formalism is derived from first principles, i.e. from an action with two dimensional diffeomorphism and Weyl invariance. Secondly the decoupling of unphysical states in the minimal pure spinor formalism is proved

  17. Comparative in vitro biocompatibility of nickel-titanium, pure nickel, pure titanium, and stainless steel: genotoxicity and atomic absorption evaluation.

    Science.gov (United States)

    Assad, M; Lemieux, N; Rivard, C H; Yahia, L H

    1999-01-01

    The genotoxicity level of nickel-titanium (NiTi) was compared to that of its pure constituents, pure nickel (Ni) and pure titanium (Ti) powders, and also to 316L stainless steel (316L SS) as clinical reference material. In order to do so, a dynamic in vitro semiphysiological extraction was performed with all metals using agitation and ISO requirements. Peripheral blood lymphocytes were then cultured in the presence of all material extracts, and their comparative genotoxicity levels were assessed using electron microscopy-in situ end-labeling (EM-ISEL) coupled to immunogold staining. Cellular chromatin exposition to pure Ni and 316L SS demonstrated a significantly stronger gold binding than exposition to NiTi, pure Ti, or the untreated control. In parallel, graphite furnace atomic absorption spectrophotometry (AAS) was also performed on all extraction media. The release of Ni atoms took the following decreasing distribution for the different resulting semiphysiological solutions: pure Ni, 316L SS, NiTi, Ti, and controls. Ti elements were detected after elution of pure titanium only. Both pure titanium and nickel-titanium specimens obtained a relative in vitro biocompatibility. Therefore, this quantitative in vitro study provides optimistic results for the eventual use of nickel-titanium alloys as surgical implant materials.

  18. Concurrence classes for general pure multipartite states

    International Nuclear Information System (INIS)

    Heydari, Hoshang

    2005-01-01

    We propose concurrence classes for general pure multipartite states based on an orthogonal complement of a positive operator-valued measure on quantum phase. In particular, we construct W m class, GHZ m , and GHZ m-1 class concurrences for general pure m-partite states. We give explicit expressions for W 3 and GHZ 3 class concurrences for general pure three-partite states and for W 4 , GHZ 4 and GHZ 3 class concurrences for general pure four-partite states

  19. Microbial Synthesis of the Forskolin Precursor Manoyl Oxide in an Enantiomerically Pure Form

    DEFF Research Database (Denmark)

    Nielsen, Morten Thrane; Ranberg, Johan Andersen; Christensen, Ulla

    2014-01-01

    to cultivate. This may result in insufficient and unreliable supply leading to fluctuating and high sales prices. Hence, substantial efforts and resources have been invested in developing sustainable and reliable supply routes based on microbial cell factories. Here, we report microbial synthesis of (13R...

  20. Ti(IV) and the Siderophore Desferrioxamine B: A Tight Complex Has Biological and Environmental Implications.

    Science.gov (United States)

    Jones, Kayleigh E; Batchler, Kathleen L; Zalouk, Célia; Valentine, Ann M

    2017-02-06

    The siderophore desferrioxamine B (DFOB) binds Ti(IV) tightly and precludes its hydrolytic precipitation under biologically and environmentally relevant conditions. This interaction of DFOB with Ti(IV) is investigated by using spectro-potentiometric and spectro-photometric titrations, mass spectrometry, isothermal titration calorimetry (ITC), and computational modeling. The data from pH 2-10 suggest two one-proton equilibria among three species, with one species predominating below pH 3.5, a second from pH 3.5 to 8, and a third above pH 8. The latter species is prone to slow hydrolytic precipitation. Electrospray mass spectrometry allowed the detection of [Ti(IV) (HDFOB)] 2+ and [Ti(DFOB)] + ; these species were assigned as the pH UV/vis-monitored competition with ethylenediaminetetraacetic acid (EDTA). Taking into consideration the available binding constant of Ti(IV) and EDTA, the data reveal values of log β 111 = 41.7, log β 110 = 38.1, and log β 11-1 = 30.1. The former value was supported by ITC, with the transfer of Ti(IV) from EDTA to DFOB determined to be both enthalpically and entropically favorable. Computational methods yielded a model of Ti-DFOB. The physiological and environmental implications of this tight interaction and the potential role of DFOB in solubilizing Ti(IV) are discussed.

  1. Polarized ensembles of random pure states

    Science.gov (United States)

    Deelan Cunden, Fabio; Facchi, Paolo; Florio, Giuseppe

    2013-08-01

    A new family of polarized ensembles of random pure states is presented. These ensembles are obtained by linear superposition of two random pure states with suitable distributions, and are quite manageable. We will use the obtained results for two purposes: on the one hand we will be able to derive an efficient strategy for sampling states from isopurity manifolds. On the other, we will characterize the deviation of a pure quantum state from separability under the influence of noise.

  2. Composition and Enantiomeric Analysis of the Essential Oil of the Fruits and the Leaves of Pistacia vera from Greece

    Directory of Open Access Journals (Sweden)

    Anastasia Tsokou

    2007-06-01

    Full Text Available The essential oils of the fruits and the leaves of pistachio (Pistacia vera L. were analyzed by GC and GC/MS. Fresh unripe pistachio fruits were richer in essential oil (0.5 %, w/w than the leaves (0.1 %, w/w. Twenty one compounds were identified in the essential oil of the fruits and the major components were (+-α-pinene (54.6 % and terpinolene (31.2 %. The enantiomeric ratio of the major constituents of the essential oil of the fruits was determined using chiral GC/MS and it was found that the (+/(--α-pinene ratio was 99.5:0.5, (+/(--limonene 80:20, (+/(--β-pinene 96:4, and (+/(--α-terpineol 0:100. Thirty three compounds were identified in the essential oil of the leaves and the major components were found to be α-pinene (30.0 %, terpinolene (17.6 % and bornyl acetate (11.3 %.

  3. Simultaneous determination of diastereoisomeric and enantiomeric impurities in SSS-octahydroindole-2-carboxylic acid by chiral high-performance liquid chromatography with pre-column derivatization.

    Science.gov (United States)

    Wang, Jin Zhao; Zeng, Su; Hu, Gong Yun; Wang, Dan Hua

    2009-04-10

    SSS-Octahydroindole-2-carboxylic acid (SSS-Oic) is a key intermediate used in the synthesis of some angiotensin-converting enzyme (ACE) inhibitors. The separation of diastereoisomers and enantiomers of Oic was performed using a pre-column derivatization chiral HPLC method. Phenyl isothiocyanate (PITC) was used as the derivatization reagent. Three PITC derivatives of Oic stereoisomers were separated on an Ultron ES-OVM chiral column (150 mm x 4.6 mm, 5 microm). Derivatization conditions such as reaction temperature, reaction time and derivatization reagent concentration were investigated. The chromatographic conditions for separation of the three PITC-Oic derivatives were optimized. The method was successfully applied in the diastereoisomeric and enantiomeric purity test of SSS-Oic.

  4. Polarized ensembles of random pure states

    International Nuclear Information System (INIS)

    Cunden, Fabio Deelan; Facchi, Paolo; Florio, Giuseppe

    2013-01-01

    A new family of polarized ensembles of random pure states is presented. These ensembles are obtained by linear superposition of two random pure states with suitable distributions, and are quite manageable. We will use the obtained results for two purposes: on the one hand we will be able to derive an efficient strategy for sampling states from isopurity manifolds. On the other, we will characterize the deviation of a pure quantum state from separability under the influence of noise. (paper)

  5. Stability of the Cadmium Complex with the Bacterial Trihydroxamate Siderophore Desferrioxamine B at Seawater Ionic Strength

    Science.gov (United States)

    Christenson, E. A.; Schijf, J.

    2010-12-01

    The divalent transition metal cadmium occurs in seawater at ultra-trace levels. In the open ocean, dissolved Cd(II) displays a nutrient-like profile characterized by a strong gradient from low picomolar concentrations in surface waters to a mid-depth maximum of around 1 nM. Its vertical distribution is highly correlated with that of dissolved phosphate, seemingly at odds with the general perception that Cd is a very toxic element. On the other hand, in Zn-depleted waters Cd(II) has been found to replace Zn(II) or Co(II) in a functional, albeit less efficient form of carbonic anhydrase, a key enzyme enabling the assimilation of bicarbonate into organic matter. Considering these opposing roles, it is likely that phytoplankton regulates the toxicity and/or bioavailability of Cd(II) through the production of certain strong organic ligands, as it has been shown to do for example in the case of Cu(II). Siderophores are a fascinating class of organic ligands excreted by microorganisms to facilitate the acquisition of micronutrient Fe(III), preciously scarce due to its extremely low solubility in seawater. The linear trihydroxamic acid desferrioxamine B (DFOB) is naturally present in open ocean surface waters at picomolar concentrations and, because of its use as a pharmaceutical agent in the treatment of human iron overload disorders, the only purified siderophore commercially available in practicable quantities. The optimal spacing of three bidentate O-bearing functional groups along a flexible carbon frame allows the molecule to wrap around the Fe3+ ion in a polydentate heterocyclic structure that perfectly matches its ionic radius and preferred coordination. Despite its resultant exceptional affinity and selectivity for Fe3+ (β ~ 1031), DFOB also forms very stable complexes with an array of differently sized and charged cations. The only previous report on the stability constant of the Cd(II)-DFOB complex, dating from 1963, proposes a values of 108 at 0.1 M ionic

  6. Tensor modes in pure natural inflation

    Science.gov (United States)

    Nomura, Yasunori; Yamazaki, Masahito

    2018-05-01

    We study tensor modes in pure natural inflation [1], a recently-proposed inflationary model in which an axionic inflaton couples to pure Yang-Mills gauge fields. We find that the tensor-to-scalar ratio r is naturally bounded from below. This bound originates from the finiteness of the number of metastable branches of vacua in pure Yang-Mills theories. Details of the model can be probed by future cosmic microwave background experiments and improved lattice gauge theory calculations of the θ-angle dependence of the vacuum energy.

  7. Method of producing vegetable puree

    DEFF Research Database (Denmark)

    2004-01-01

    A process for producing a vegetable puree, comprising the sequential steps of: a)crushing, chopping or slicing the vegetable into pieces of 1 to 30 mm; b) blanching the vegetable pieces at a temperature of 60 to 90°C; c) contacted the blanched vegetable pieces with a macerating enzyme activity; d......) blending the macerated vegetable pieces and obtaining a puree....

  8. ActionScript Developer's Guide to PureMVC

    CERN Document Server

    Hall, Cliff

    2011-01-01

    Gain hands-on experience with PureMVC, the popular open source framework for developing maintainable applications with a Model-View-Controller architecture. In this concise guide, PureMVC creator Cliff Hall teaches the fundamentals of PureMVC development by walking you through the construction of a complete non-trivial Adobe AIR application. Through clear explanations and numerous ActionScript code examples, you'll learn best practices for using the framework's classes in your day-to-day work. Discover how PureMVC enables you to focus on the purpose and scope of your application, while the f

  9. Microbial Stereoselective One-Step Conversion of Diols to Chiral Lactones in Yeast Cultures

    Directory of Open Access Journals (Sweden)

    Filip Boratyński

    2015-12-01

    Full Text Available It has been shown that whole cells of different strains of yeast catalyze stereoselective oxidation of meso diols to the corresponding chiral lactones. Among screening-scale experiments, Candida pelliculosa ZP22 was selected as the most effective biocatalyst for the oxidation of monocyclic diols 3a–b with respect to the ratio of high conversion to stereoselectivity. This strain was used in the preparative oxidation, affording enantiomerically-enriched isomers of lactones: (+-(3aR,7aS-cis-hexahydro-1(3H -isobenzofuranone (2a and (+-(3aS,4,7,7aR-cis-tetrahydro-1(3H-isobenzofuranone (2b. Scaling up the culture growth, as well as biotransformation conditions has been successfully accomplished. Among more bulky substrates, bicyclic diol 3d was totally converted into enantiomerically-pure exo-bridged (+-(3aR,4S,7R,7aS-cis-tetrahydro-4,7-methanoisobenzofuran -1(3H-one (2d by Yarrovia lipolytica AR71. Microbial oxidation of diol 3f by Candida sake AM908 and Rhodotorula rubra AM4 afforded optically-pure cis-3-butylhexahydro-1(3H -isobenzofuranone (2f, however with low conversion.

  10. Occurrence of Chiral Bioactive Compounds in the Aquatic Environment: A Review

    Directory of Open Access Journals (Sweden)

    Cláudia Ribeiro

    2017-10-01

    Full Text Available In recent decades, the presence of micropollutants in the environment has been extensively studied due to their high frequency of occurrence, persistence and possible adverse effects to exposed organisms. Concerning chiral micropollutants in the environment, enantiomers are frequently ignored and enantiomeric composition often neglected. However, enantioselective toxicity is well recognized, highlighting the need to include enantioselectivity in environmental risk assessment. Additionally, the information about enantiomeric fraction (EF is crucial since it gives insights about: (i environmental fate (i.e., occurrence, distribution, removal processes and (biodegradation; (ii illicit discharges; (iii consumption pattern (e.g., illicit drugs, pharmaceuticals used as recreational drugs, illicit use of pesticides; and (iv enantioselective toxicological effects. Thus, the purpose of this paper is to provide a comprehensive review about the enantioselective occurrence of chiral bioactive compounds in aquatic environmental matrices. These include pharmaceuticals, illicit drugs, pesticides, polychlorinated biphenyls (PCBs and polycyclic musks (PCMs. Most frequently analytical methods used for separation of enantiomers were liquid chromatography and gas chromatography methodologies using both indirect (enantiomerically pure derivatizing reagents and direct methods (chiral stationary phases. The occurrence of these chiral micropollutants in the environment is reviewed and future challenges are outlined.

  11. Využití B-H karbonátů v organokatalytických transformacích

    OpenAIRE

    Tichá, Iveta

    2014-01-01

    This diploma thesis is focused on the preparation of enantiomerically pure compounds based on organocatalytic allylic substitution using Baylis-Hillman carbonates. As selected substrates for the allylic substitution were chosen α-azidoketones such as azidoacetophenone, 2-azido-1-indanone and then heterocyclic compounds (N-phenylrhodanine and its derivate) belonging to the pharmaceutical privileged compounds. Other substrate for allylic substitution was allylmalononitrile. In addition, this th...

  12. Synthesis of 2',3'-dideoxy-3'-C-(hydroxymethyl)-4'-thiopentofuranosyl nucleosides as potential antiviral agent.

    Science.gov (United States)

    Ichikawa, E; Yamamura, S; Kato, K

    1999-04-19

    1-O-Acetyl-2,3-dideoxy-3-C-(hydroxymethyl)-4-thiofuranose derivative was synthesized from (S,S)-1,4-bis(benzyloxy)-2,3-epoxybutane derived from (+)-diethyl L-tartrate and the enantiomerically pure (E)-5-(2-bromovinyl)-1-[2',3'-dideoxy-3'-C-(hydroxymethyl)-beta-D-4'- thiopentofuranosyl]uracil 4 was obtained via coupling of silylated uracil followed by palladium-mediated coupling of methyl acrylate.

  13. Pure robotic retrocaval ureter repair

    Directory of Open Access Journals (Sweden)

    Ashok k. Hemal

    2008-12-01

    Full Text Available PURPOSE: To demonstrate the feasibility of pure robotic retrocaval ureter repair. MATERIALS AND METHODS: A 33 year old female presented with right loin pain and obstruction on intravenous urography with the classical "fish-hook" appearance. She was counseled on the various methods of repair and elected to have a robot assisted repair. The following steps are performed during a pure robotic retrocaval ureter repair. The patient is placed in a modified flank position, pneumoperitoneum created and ports inserted. The colon is mobilized to expose the retroperitoneal structures: inferior vena cava, right gonadal vein, right ureter, and duodenum. The renal pelvis and ureter are mobilized and the renal pelvis transected. The ureter is transposed anterior to the inferior vena cava and a pyelopyelostomy is performed over a JJ stent. RESULTS: This patient was discharged on postoperative day 3. The catheter and drain tube were removed on day 1. Her JJ stent was removed at 6 weeks postoperatively. The postoperative intravenous urography at 3 months confirmed normal drainage of contrast medium. CONCLUSION: Pure robotic retrocaval ureter is a feasible procedure; however, there does not appear to be any great advantage over pure laparoscopy, apart from the ergonomic ease for the surgeon as well the simpler intracorporeal suturing.

  14. Biosynthetic Tailoring of Microcin E492m: Post-Translational Modification Affords an Antibacterial Siderophore-Peptide Conjugate

    Science.gov (United States)

    Nolan, Elizabeth M.; Fischbach, Michael A.; Koglin, Alexander; Walsh, Christopher T.

    2008-01-01

    The present work reveals that four proteins, MceCDIJ, encoded by the MccE492 gene cluster are responsible for the remarkable post-translational tailoring of Microcin E492 (MccE492), an 84-residue protein toxin secreted by Klebsiella pneumonaie RYC492 that targets neighboring gram-negative species. This modification results in attachment of a linearized and monoglycosylated derivative of enterobactin, a nonribosomal peptide and iron scavenger (siderophore), to the MccE492m C-terminus. MceC and MceD derivatize enterobactin by C-glycosylation at the C5 position of a N-(2,3-dihydroxybenzoyl) serine (DHB-Ser) moiety and regiospecific hydrolysis of an ester linkage in the trilactone scaffold, respectively. MceI and MceJ form a protein complex that attaches C-glycosylated enterobactins to the C-terminal serine residue of both aC10 model peptide and full-length MccE492. In the enzymatic product, the terminal serine residue is covalently attached to the C4′ oxygen of the glucose moiety. Non-enzymatic and base-catalyzed migration of the peptide to the C6′ position affords the C6′ glycosyl ester linkage observed in the mature toxin, MccE492m, isolated from bacterial cultures. PMID:17973380

  15. Characterizing commercial pureed foods: sensory, nutritional, and textural analysis.

    Science.gov (United States)

    Ettinger, Laurel; Keller, Heather H; Duizer, Lisa M

    2014-01-01

    Dysphagia (swallowing impairment) is a common consequence of stroke and degenerative diseases such as Parkinson's and Alzheimer's. Limited research is available on pureed foods, specifically the qualities of commercial products. Because research has linked pureed foods, specifically in-house pureed products, to malnutrition due to inferior sensory and nutritional qualities, commercial purees also need to be investigated. Proprietary research on sensory attributes of commercial foods is available; however direct comparisons of commercial pureed foods have never been reported. Descriptive sensory analysis as well as nutritional and texture analysis of commercially pureed prepared products was performed using a trained descriptive analysis panel. The pureed foods tested included four brands of carrots, of turkey, and two of bread. Each commercial puree was analyzed for fat (Soxhlet), protein (Dumas), carbohydrate (proximate analysis), fiber (total fiber), and sodium content (Quantab titrator strips). The purees were also texturally compared with a line spread test and a back extrusion test. Differences were found in the purees for sensory attributes as well as nutritional and textural properties. Findings suggest that implementation of standards is required to reduce variability between products, specifically regarding the textural components of the products. This would ensure all commercial products available in Canada meet standards established as being considered safe for swallowing.

  16. Vacuum evaporation of pure metals

    OpenAIRE

    Safarian, Jafar; Engh, Thorvald Abel

    2013-01-01

    Theories on the evaporation of pure substances are reviewed and applied to study vacuum evaporation of pure metals. It is shown that there is good agreement between different theories for weak evaporation, whereas there are differences under intensive evaporation conditions. For weak evaporation, the evaporation coefficient in Hertz-Knudsen equation is 1.66. Vapor velocity as a function of the pressure is calculated applying several theories. If a condensing surface is less than one collision...

  17. Bioaccumulation and enantiomeric profiling of organochlorine pesticides and persistent organic pollutants in the killer whale (Orcinus orca) from British and Irish waters

    International Nuclear Information System (INIS)

    McHugh, Brendan; Law, Robin J.; Allchin, Colin R.; Rogan, Emer; Murphy, Sinead; Foley, M. Barry; Glynn, Denise; McGovern, Evin

    2007-01-01

    Concentrations and enantiomeric profiles for a range of organochlorine compounds are reported in blubber samples from a number of individual killer whales (Orcinus orca) from British and Irish waters. Elevated contaminant levels and enriched isotopic ratios were determined in one individual whale sampled in the Scottish Western Isles compared to the others suggesting marine mammal based dietary influences. The potential application of isotopic ratios to model contaminant uptake, enantioselective enrichment and accumulation is demonstrated. Data are presented which provide information on enantioselective enrichment factors (EFs) for o,p'-DDT, α-HCH and toxaphene congeners CHB26 and CHB 50. This dataset further improves the current database on reported levels of a number of contaminants and provides additional background information on potential metabolic processes in killer whales from British and Irish waters

  18. Bioaccumulation and enantiomeric profiling of organochlorine pesticides and persistent organic pollutants in the killer whale (Orcinus orca) from British and Irish waters

    Energy Technology Data Exchange (ETDEWEB)

    McHugh, Brendan [Marine Institute, Rinville, Oranmore, Galway (Ireland)], E-mail: brendan.mchugh@marine.ie; Law, Robin J.; Allchin, Colin R. [Centre for Environment, Fisheries and Aquaculture Science, Cefas Burnham Laboratory, Remembrance Avenue, Burnham on Crouch, Essex CM0 8HA (United Kingdom); Rogan, Emer [Department of Zoology, University College Cork (Ireland); Murphy, Sinead [Department of Zoology, University College Cork (Ireland); Sea Mammal Research Unit, Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife KY16 8LB (United Kingdom); Foley, M. Barry [Dublin Institute of Technology, Kevin Street, Dublin 8 (Ireland); Glynn, Denise; McGovern, Evin [Marine Institute, Rinville, Oranmore, Galway (Ireland)

    2007-11-15

    Concentrations and enantiomeric profiles for a range of organochlorine compounds are reported in blubber samples from a number of individual killer whales (Orcinus orca) from British and Irish waters. Elevated contaminant levels and enriched isotopic ratios were determined in one individual whale sampled in the Scottish Western Isles compared to the others suggesting marine mammal based dietary influences. The potential application of isotopic ratios to model contaminant uptake, enantioselective enrichment and accumulation is demonstrated. Data are presented which provide information on enantioselective enrichment factors (EFs) for o,p'-DDT, {alpha}-HCH and toxaphene congeners CHB26 and CHB 50. This dataset further improves the current database on reported levels of a number of contaminants and provides additional background information on potential metabolic processes in killer whales from British and Irish waters.

  19. Pure natural inflation

    Science.gov (United States)

    Nomura, Yasunori; Watari, Taizan; Yamazaki, Masahito

    2018-01-01

    We point out that a simple inflationary model in which the axionic inflaton couples to a pure Yang-Mills theory may give the scalar spectral index (ns) and tensor-to-scalar ratio (r) in complete agreement with the current observational data.

  20. Conformal pure radiation with parallel rays

    International Nuclear Information System (INIS)

    Leistner, Thomas; Paweł Nurowski

    2012-01-01

    We define pure radiation metrics with parallel rays to be n-dimensional pseudo-Riemannian metrics that admit a parallel null line bundle K and whose Ricci tensor vanishes on vectors that are orthogonal to K. We give necessary conditions in terms of the Weyl, Cotton and Bach tensors for a pseudo-Riemannian metric to be conformal to a pure radiation metric with parallel rays. Then, we derive conditions in terms of the tractor calculus that are equivalent to the existence of a pure radiation metric with parallel rays in a conformal class. We also give analogous results for n-dimensional pseudo-Riemannian pp-waves. (paper)

  1. Pure spinor partition function and the massive superstring spectrum

    International Nuclear Information System (INIS)

    Aisaka, Yuri; Arroyo, E. Aldo; Berkovits, Nathan; Nekrasov, Nikita

    2008-01-01

    We explicitly compute up to the fifth mass-level the partition function of ten-dimensional pure spinor worldsheet variables including the spin dependence. After adding the contribution from the (x μ , θ α , p α ) matter variables, we reproduce the massive superstring spectrum. Even though pure spinor variables are bosonic, the pure spinor partition function contains fermionic states which first appear at the second mass-level. These fermionic states come from functions which are not globally defined in pure spinor space, and are related to the b ghost in the pure spinor formalism. This result clarifies the proper definition of the Hilbert space for pure spinor variables.

  2. Testing effects in mixed- versus pure-list designs.

    Science.gov (United States)

    Rowland, Christopher A; Littrell-Baez, Megan K; Sensenig, Amanda E; DeLosh, Edward L

    2014-08-01

    In the present study, we investigated the role of list composition in the testing effect. Across three experiments, participants learned items through study and initial testing or study and restudy. List composition was manipulated, such that tested and restudied items appeared either intermixed in the same lists (mixed lists) or in separate lists (pure lists). In Experiment 1, half of the participants received mixed lists and half received pure lists. In Experiment 2, all participants were given both mixed and pure lists. Experiment 3 followed Erlebacher's (Psychological Bulletin, 84, 212-219, 1977) method, such that mixed lists, pure tested lists, and pure restudied lists were given to independent groups. Across all three experiments, the final recall results revealed significant testing effects for both mixed and pure lists, with no reliable difference in the magnitude of the testing advantage across list designs. This finding suggests that the testing effect is not subject to a key boundary condition-list design-that impacts other memory phenomena, including the generation effect.

  3. Tractable Quantification of Entanglement for Multipartite Pure States

    International Nuclear Information System (INIS)

    Nian-Quan, Jiang; Yu-Jian, Wang; Yi-Zhuang, Zheng; Gen-Chang, Cai

    2008-01-01

    We present kth-order entanglement measure and global kth-order entanglement measure for multipartite pure states, and extend Bennett's measure of partial entropy for bipartite pure states to a multipartite case. These measures are computable and can effectively classify and quantify the entanglement of multipartite pure states. (general)

  4. Gate-Driven Pure Spin Current in Graphene

    Science.gov (United States)

    Lin, Xiaoyang; Su, Li; Si, Zhizhong; Zhang, Youguang; Bournel, Arnaud; Zhang, Yue; Klein, Jacques-Olivier; Fert, Albert; Zhao, Weisheng

    2017-09-01

    The manipulation of spin current is a promising solution for low-power devices beyond CMOS. However, conventional methods, such as spin-transfer torque or spin-orbit torque for magnetic tunnel junctions, suffer from large power consumption due to frequent spin-charge conversions. An important challenge is, thus, to realize long-distance transport of pure spin current, together with efficient manipulation. Here, the mechanism of gate-driven pure spin current in graphene is presented. Such a mechanism relies on the electrical gating of carrier-density-dependent conductivity and spin-diffusion length in graphene. The gate-driven feature is adopted to realize the pure spin-current demultiplexing operation, which enables gate-controllable distribution of the pure spin current into graphene branches. Compared with the Elliott-Yafet spin-relaxation mechanism, the D'yakonov-Perel spin-relaxation mechanism results in more appreciable demultiplexing performance. The feature of the pure spin-current demultiplexing operation will allow a number of logic functions to be cascaded without spin-charge conversions and open a route for future ultra-low-power devices.

  5. Pure natural inflation

    Directory of Open Access Journals (Sweden)

    Yasunori Nomura

    2018-01-01

    Full Text Available We point out that a simple inflationary model in which the axionic inflaton couples to a pure Yang–Mills theory may give the scalar spectral index (ns and tensor-to-scalar ratio (r in complete agreement with the current observational data.

  6. Pure chiral optical fibres.

    Science.gov (United States)

    Poladian, L; Straton, M; Docherty, A; Argyros, A

    2011-01-17

    We investigate the properties of optical fibres made from chiral materials, in which a contrast in optical activity forms the waveguide, rather than a contrast in the refractive index; we refer to such structures as pure chiral fibres. We present a mathematical formulation for solving the modes of circularly symmetric examples of such fibres and examine the guidance and polarisation properties of pure chiral step-index, Bragg and photonic crystal fibre designs. Their behaviour is shown to differ for left- and right-hand circular polarisation, allowing circular polarisations to be isolated and/or guided by different mechanisms, as well as differing from equivalent non-chiral fibres. The strength of optical activity required in each case is quantified.

  7. Adsorption of Th(IV) and Pu(IV) on the surface of Pseudomonas fluorescens and Bacillus subtilis in the presence of desferrioxamine siderophore

    International Nuclear Information System (INIS)

    Yoshida, Takahiro; Ozaki, Takuo; Ohnuki, Toshihiko; Francis, Arokiasamy J.

    2005-01-01

    Adsorption of Th(IV) and Pu(IV) on a Gram-negative bacterium Pseudomonas fluorescens and a Gram-positive bacterium Bacillus subtilis in the presence of siderophore desferrioxamine B (DFO) was studied. Thorium(IV) and Pu(IV) were dissociated from DFO during adsorption on the cells. Thorium(IV) adsorption on bacterial cells in the presence of DFO was larger than that of Pu(IV) because of the smaller stability of the Th(IV)-DFO complex than that of the Pu(IV)-DFO complex. On the other hand, adsorption of Pu(IV) was larger than that of Fe(III), wherein the stability of the Pu(IV)- and Fe(III)-DFO complex is comparable. P. fluorescens showed a higher affinity for Th(IV) and Pu(IV) than B. subtilis, though potentiometric titration of bacterial cells indicated that surfaces of P. fluorescens and B. subtilis cells showed similar proton binding properties. (author)

  8. Enantiopure vs. Racemic Naphthalimide End-Capped Helicenic Non-Fullerene Electron Acceptors: Impact on Organic Photovoltaics Performance

    OpenAIRE

    Josse , Pierre; Favereau , Ludovic; Shen , Chengshuo; Dabos-Seignon , Sylvie; Blanchard , Philippe; Cabanetos , Clement; Crassous , Jeanne

    2017-01-01

    International audience; Impact of the enantiopurity on organic photovoltaics (OPV) performance was investigated through the synthesis of racemic and enantiomerically pure naphthalimide end-capped helicenes and their application as non-fullerene molecular electron acceptors in OPV devices. A very strong increase of the device performance was observed by simply switching from the racemic to the enantiopure forms of these π-helical non-fullerene acceptors with power conversion efficiencies jumpi...

  9. Asymetrická organokatalytická syntéza organických sloučenin z α,β-nenasycených aldehydů

    OpenAIRE

    Kamlar, Martin

    2010-01-01

    With regard to a fast development in the field of fluoroorganic chemisty, the intention of this diploma thesis is focused to utilize of organocatalysis by secondary amines as catalysts for preparation enantiomerically pure compounds containing fluorine atom in its structure. The preparation of these subsances is realized by way of nucleofilic addition to α,β- unsaturated aldehydes using suitable fluorine containing nuclephilic agent 1-(fluoronitromethylsulphonyl)benzene, to get appropriate 1,...

  10. How pH Modulates the Reactivity and Selectivity of a Siderophore-Associated Flavin Monooxygenase

    Science.gov (United States)

    2015-01-01

    Flavin-containing monooxygenases (FMOs) catalyze the oxygenation of diverse organic molecules using O2, NADPH, and the flavin adenine dinucleotide (FAD) cofactor. The fungal FMO SidA initiates peptidic siderophore biosynthesis via the highly selective hydroxylation of l-ornithine, while the related amino acid l-lysine is a potent effector of reaction uncoupling to generate H2O2. We hypothesized that protonation states could critically influence both substrate-selective hydroxylation and H2O2 release, and therefore undertook a study of SidA’s pH-dependent reaction kinetics. Consistent with other FMOs that stabilize a C4a-OO(H) intermediate, SidA’s reductive half reaction is pH independent. The rate constant for the formation of the reactive C4a-OO(H) intermediate from reduced SidA and O2 is likewise independent of pH. However, the rate constants for C4a-OO(H) reactions, either to eliminate H2O2 or to hydroxylate l-Orn, were strongly pH-dependent and influenced by the nature of the bound amino acid. Solvent kinetic isotope effects of 6.6 ± 0.3 and 1.9 ± 0.2 were measured for the C4a-OOH/H2O2 conversion in the presence and absence of l-Lys, respectively. A model is proposed in which l-Lys accelerates H2O2 release via an acid–base mechanism and where side-chain position determines whether H2O2 or the hydroxylation product is observed. PMID:24490904

  11. On the importance of PURE - Public Understanding of Renewable Energy

    Energy Technology Data Exchange (ETDEWEB)

    Broman, Lars; Kandpal, Tara C.

    2013-09-15

    Public understanding of science (PUS) is a central concept among science communicators. Public understanding of renewable energy (PURE) is proposed as an important sub-concept of PUS. The aim of this paper is to interest and invite renewable energy scientists to join a PURE research project. Four separate important questions for a PURE research project can be identified: (A) Is PURE important? (B) Which issues of PURE are the most important ones, according to renewable energy scientists? (C) What understanding of renewable energy has the general public today, worldwide? (D) How to achieve PURE?.

  12. Bi-orderings on pure braided Thompson's groups

    OpenAIRE

    Burillo, Jose; Gonzalez-Meneses, Juan

    2006-01-01

    In this paper it is proved that the pure braided Thompson’s group BF admits a bi-order, analog to the bi-order of the pure braid groups. Ministerio de Educación y Ciencia Fondo Europeo de Desarrollo Regional

  13. Isotopically pure single crystal epitaxial diamond films and their preparation

    International Nuclear Information System (INIS)

    Banholzer, W.F.; Anthony, T.R.; Williams, D.M.

    1992-01-01

    The present invention is directed to the production of single crystal diamond consisting of isotopically pure carbon-12 or carbon-13. In the present invention, isotopically pure single crystal diamond is grown on a single crystal substrate directly from isotopically pure carbon-12 or carbon-13. One method for forming isotopically pure single crystal diamond comprises the steps of placing in a reaction chamber a single substrate heated to an elevated diamond forming temperature. Another method for forming isotopically pure single crystal diamond comprises diffusing isotopically pure carbon-12 or carbon-13 through a metallic catalyst under high pressure to a region containing a single crystal substrate to form an isotopically pure single crystal diamond layer on said single crystal substrate

  14. High-Throughput Assay for Enantiomeric Excess Determination in 1,2- and 1,3-Diols and Direct Asymmetric Reaction Screening.

    Science.gov (United States)

    Shcherbakova, Elena G; Brega, Valentina; Lynch, Vincent M; James, Tony D; Anzenbacher, Pavel

    2017-07-26

    A simple and efficient method for determination of the yield, enantiomeric/diasteriomeric excess (ee/de), and absolute configuration of crude chiral diols without the need of work-up and product isolation in a high throughput setting is described. This approach utilizes a self-assembled iminoboronate ester formed as a product by dynamic covalent self-assembly of a chiral diol with an enantiopure fluorescent amine such as tryptophan methyl ester or tryptophanol and 2-formylphenylboronic acid. The resulting diastereomeric boronates display different photophysical properties and allow for fluorescence-based ee determination of molecules containing a 1,2- or 1,3-diol moiety. This method has been utilized for the screening of ee in a number of chiral diols including atorvastatin, a statin used for the treatment of hypercholesterolemia. Noyori asymmetric hydrogenation of benzil was performed in a highly parallel fashion with errors products from the parallel asymmetric synthesis in real time and in a high-throughput screening (HTS) fashion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. PSYCHE Pure Shift NMR Spectroscopy.

    Science.gov (United States)

    Foroozandeh, Mohammadali; Morris, Gareth; Nilsson, Mathias

    2018-03-13

    Broadband homodecoupling techniques in NMR, also known as "pure shift" methods, aim to enhance spectral resolution by suppressing the effects of homonuclear coupling interactions to turn multiplet signals into singlets. Such techniques typically work by selecting a subset of "active" nuclear spins to observe, and selectively inverting the remaining, "passive", spins to reverse the effects of coupling. Pure Shift Yielded by Chirp Excitation (PSYCHE) is one such method; it is relatively recent, but has already been successfully implemented in a range of different NMR experiments. Paradoxically, PSYCHE is one of the trickiest of pure shift NMR techniques to understand but one of the easiest to use. Here we offer some insights into theoretical and practical aspects of the method, and into the effects and importance of the experimental parameters. Some recent improvements that enhance the spectral purity of PSYCHE spectra will be presented, and some experimental frameworks including examples in 1D and 2D NMR spectroscopy, for the implementation of PSYCHE will be introduced. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Texture and Microtexture of Pure (6N and Commercially Pure Aluminum after Deformation by Extrusion with Forward-Backward Rotating Die (Kobo

    Directory of Open Access Journals (Sweden)

    Bieda M.

    2016-03-01

    Full Text Available Pure aluminium (6N and commercially pure aluminium (99.7 was deformed by KOBO method. Microstructure and texture of both materials after deformation was analyzed by means of scanning and transmission electron microscopy. Advanced methods of crystallographic orientations measurements like Electron Backscatter Diffraction - EBSD (SEM and microdiffraction (TEM was used. Grain size distribution and misorientation between grains in cross and longitudinal sections of the samples were analyzed. Differences in size and homogeneity of the grains were observed in both materials. Pure aluminium was characterized by larger grain size in both sections of extruded material. Whereas commercially pure aluminium reveals smaller grain size and more homogeneous and stable microstructure.

  17. Stereospecific Winding of Polycyclic Aromatic Hydrocarbons into Trinacria Propellers.

    Science.gov (United States)

    Mosca, Dario; Stopin, Antoine; Wouters, Johan; Demitri, Nicola; Bonifazi, Davide

    2017-11-02

    The stereospecific trimerization of enantiomerically pure binaphthols with hexakis(bromomethyl)benzene gives access in one step to enantiomerically pure molecular propellers, in which three binaphthyl rings are held together with dioxecine rings. X-ray diffraction analysis revealed that three out the six naphthyl moieties are folded in a (EF) 3 -type arrangement held by three intramolecular C-H⋅⋅⋅π interactions. This slips outward the three remaining naphthyl rings in a blade-like fashion, just like in three-folded propeller components. This peculiar conformation shows striking similarity to the mythological Sicilian symbol of Trinacria, from which the name "trinacria propeller" derives. The propeller conformation is also preserved in chlorinated solutions, as displayed by the presence of a peak at 4.7 ppm typical of an aromatic proton resonance engaged in a C-H⋅⋅⋅π interaction. The denaturation of the propeller-like conformation is obtained at high temperature, corresponding to activation energy for the ring inversion of ca. 18.2 kcal mol -1 . Notably, halide-functionalized molecular propellers exposing I-atoms at the leading and trailing edges could be prepared stereo- and regiospecifically by choosing the relevant iodo-bearing BINOL derivative. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Lectures on the theory of pure motives

    CERN Document Server

    Murre, Jacob P; A, Chris

    2013-01-01

    The theory of motives was created by Grothendieck in the 1960s as he searched for a universal cohomology theory for algebraic varieties. The theory of pure motives is well established as far as the construction is concerned. Pure motives are expected to have a number of additional properties predicted by Grothendieck's standard conjectures, but these conjectures remain wide open. The theory for mixed motives is still incomplete. This book deals primarily with the theory of pure motives. The exposition begins with the fundamentals: Grothendieck's construction of the category of pure motives and examples. Next, the standard conjectures and the famous theorem of Jannsen on the category of the numerical motives are discussed. Following this, the important theory of finite dimensionality is covered. The concept of Chow-K�nneth decomposition is introduced, with discussion of the known results and the related conjectures, in particular the conjectures of Bloch-Beilinson type. We finish with a chapter on relative m...

  19. Pure energy solutions - pure tomorrows

    International Nuclear Information System (INIS)

    Allison, J.

    2006-01-01

    HTC is an energy technology company whose mandate is to deliver 'Carbon Clear Solutions' to address the pending challenges the energy sector is facing in meeting the environmental impact of Greenhouse Gas emissions, and energy security. HTC will speak on its comprehensive suite of technologies including hydrogen production, CO 2 capture and CO 2 sequestration. HTC has patented technologies that produce H 2 from a broad variety of feedstocks such as Natural gas, Diesel, Gasoline, Bio-fuels i.e. ethanol, methanol and Coal Gasification. HTC Hydrogen reformation systems are unique in their method of delivering pure Hydrogen. Dry Reformation Reactor - New catalyst system designed to eliminate contamination problems (i.e. coking) while at the same time operate at a low temperature. Water Gas Shift Reactor - Plus - improved and redesigned catalyst that improves operating temperature and hydrogen production efficiency. Two stage catalyst reactor that provides near balance of the endothermic and exothermic reaction temperatures for efficient energy balance

  20. Pure γ-families

    International Nuclear Information System (INIS)

    Dunaevskii, A.M.

    1977-01-01

    The subject of this work are pure gamma families consisting of the gamma quanta produced in the early stages of cosmic cascades. The criteria of selecting these families from the all measured families are presented. The characteristics of these families are given and some conclusions about the mechanism of the nuclear-electromagnetic cascades are extracted. (S.B.)

  1. Pure spinor integration from the collating formula

    International Nuclear Information System (INIS)

    Grassi, P.A.; Sommovigo, L.

    2011-01-01

    We use the technique developed by Becchi and Imbimbo to construct a well-defined BRST-invariant path integral formulation of pure spinor amplitudes. The space of pure spinors can be viewed from the algebraic geometry point of view as a collection of open sets where the constraints can be solved and a set of free and independent variables can be defined. On the intersections of those open sets, the functional measure jumps and one has to add boundary terms to construct a well-defined path integral. The result is the definition of the pure spinor integration measure constructed in terms of differential forms on each single patch.

  2. Fully automated one-pot radiosynthesis of O-(2-[{sup 18}F]fluoroethyl)-L-tyrosine on the TracerLab FX{sub FN} module

    Energy Technology Data Exchange (ETDEWEB)

    Bourdier, Thomas, E-mail: bts@ansto.gov.au [LifeSciences, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Sydney (Australia); Greguric, Ivan [LifeSciences, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Sydney (Australia); Roselt, Peter [Centre for Molecular Imaging, Peter MacCallum Cancer Centre, 12 St Andrew' s Place, East Melbourne, VIC, 3002 (Australia); Jackson, Tim; Faragalla, Jane; Katsifis, Andrew [LifeSciences, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Sydney (Australia)

    2011-07-15

    Introduction: An efficient fully automated method for the radiosynthesis of enantiomerically pure O-(2-[{sup 18}F]fluoroethyl)-L-tyrosine ([{sup 18}F]FET) using the GE TracerLab FX{sub FN} synthesis module via the O-(2-tosyloxyethyl)-N-trityl-L-tyrosine tert-butylester precursor has been developed. Methods: The radiolabelling of [{sup 18}F]FET involved a classical [{sup 18}F]fluoride nucleophilic substitution performed in acetonitrile using potassium carbonate and Kryptofix 222, followed by acid hydrolysis using 2N hydrochloric acid. Results: [{sup 18}F]FET was produced in 35{+-}5% (n=22) yield non-decay-corrected (55{+-}5% decay-corrected) and with radiochemical and enantiomeric purity of >99% with a specific activity of >90 GBq/{mu}mol after 63 min of radiosynthesis including HPLC purification and formulation. Conclusion: The automated radiosynthesis provides high and reproducible yields suitable for routine clinical use.

  3. NMR-based Enantiodifferentiation of Chiral trans-2-Phenylcyclopropane Derivatives Using a Chiral Lanthanide Shift Reagent

    International Nuclear Information System (INIS)

    Cho, Nam Sook; Kim, Hyun Sook; Song, Mi Sook

    2011-01-01

    In contrast with optical methods, there is no need to characterize the pure enantiomers. Instead, the NMR method makes use of chiral reagents that convert a mixture of enantiomers into a mixture of diastereomeric complexes. Integration of the resulting NMR spectra yields a direct measurement of enantiomeric purity as long as there is a sufficiently large difference between the chemical shifts of the two diastereoisomeric complexes to produce baseline-resolved peaks. Absolute enantiomeric configurations can also be determined using this method. Chiral lanthanide shift reagents have been used since the 1970s to form addition complexes with various compounds through interactions with electron donor sites. Lanthanide-induced, pseudo-contact shifts (LIS) are a function of the distance, r, between the nuclei under observation and the lanthanide center, and the angle, θ, between the line connecting the metal ion with the observed nucleus and the line representing the CLSR magnetic axis

  4. Stereo-specific synthesis of (13r)-manoyl oxide

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a method for manufacturing enantiomerically pure (13R)-manoyl oxide, said method comprising the steps of contacting geranylgeranyl diphosphate (GGPP) with a class II diterpene synthase to obtain labd-13-en-8,15-diol diphosphate (LPP), and then contacting the LPP...... with a class I diterpene synthase to obtain (13R)-manoyl oxide. The invention further relates to (13R)-manoyl oxide obtained by the method of the invention....

  5. Enantioselective synthesis of (+-polyzonimine, defensive monoterpene alkaloid produced by a milliped Polyzonium rosalbum, and determination of its S absolute configuration by Its conversion to (4S,5R,6S-(+-nitropolyzonamine

    Directory of Open Access Journals (Sweden)

    Takagi Yasuyo

    2000-01-01

    Full Text Available Asymmetric Michael addition of the enamine derived from 2,2-dimethylcyclopentanecarbox-aldehyde and (S-prolinol methyl ether to nitroethylene afforded the adduct of 75-76% ee, which finally yielded enantiomerically pure (+-polyzonimine, a nitrogen-containing spirocyclic compound isolated from the defensive glands of a milliped, Polyzonium rosalbum. By converting (+-polyzonimine into (4S,5R,6S-(+-nitropolyzonamine, the hitherto uncertain absolute configuration of the former was established as S.

  6. Enantioselective synthesis of C{sub 9}-C{sub 1}3 fragment of erythromycin B; Sintesis enantioselectiva del fragmento C{sub 9}-C{sub 1}3 de la eritromicina B

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, E.; Carretero, J.C. [Departamento de Quimica Organica, Universidad Autonoma, Madrid (Spain)

    1994-12-31

    A stereo controlled synthesis of the enantiomerically pure C{sub 9}-C{sub 1}3 fragment of erythromycin B is described. The process takes place in 15 steps from (R)-phenylsulfonyl p-tolylsulfinyl methane and butyraldehyde (16% overall yield). The key steps, corresponding to the formation of the chiral centers, are based on the iterative synthesis of gamma-hydroxivinylsulfones and further syb-sterereoselective addition of MeLi to their protected derivatives. 8 refs.

  7. Lipase-catalyzed highly enantioselective kinetic resolution of boron-containing chiral alcohols.

    Science.gov (United States)

    Andrade, Leandro H; Barcellos, Thiago

    2009-07-16

    The first application of enzymes as catalysts to obtain optically pure boron compounds is described. The kinetic resolution of boron-containing chiral alcohols via enantioselective transesterification catalyzed by lipases was studied. Aromatic, allylic, and aliphatic secondary alcohols containing a boronate ester or boronic acid group were resolved by lipase from Candida antartica (CALB), and excellent E values (E > 200) and high enantiomeric excesses (up to >99%) of both remaining substrates and acetylated product were obtained.

  8. Chemical Composition, Enantiomeric Distribution, and Antifungal Activity of the Oleoresin Essential Oil of Protium amazonicum from Ecuador.

    Science.gov (United States)

    Satyal, Prabodh; Powers, Chelsea N; Parducci V, Rafael; McFeeters, Robert L; Setzer, William N

    2017-09-23

    Background: Protium species (Burseraceae) have been used in the treatment of various diseases and conditions such as ulcers and wounds. Methods: The essential oil from the oleoresin of Protium amazonicum was obtained by hydrodistillation and analyzed by GC-MS, GC-FID, and chiral GC-MS. P. amazonicum oleoresin oil was screened for antifungal activity against Candida albicans , Aspergillus niger , and Cryptococcus neoformans . Results: A total of 54 components representing 99.6% of the composition were identified in the oil. The essential oil was dominated by δ-3-carene (47.9%) with lesser quantities of other monoterpenoids α-pinene (4.0%), p -cymene (4.1%), limonene (5.1%), α-terpineol (5.5%) and p -cymen-8-ol (4.8%). Chiral GC-MS revealed most of the monoterpenoids to have a majority of levo enantiomers present with the exceptions of limonene and α-terpineol, which showed a dextro majority. P. amazonicum oleoresin oil showed promising activity against Cryptococcus neoformans , with MIC = 156 μg/mL. Conclusions: This account is the first reporting of both the chemical composition and enantiomeric distribution of the oleoresin essential oil of P. amazonicum from Ecuador. The oil was dominated by (-)-δ-3-carene, and this compound, along with other monoterpenoids, likely accounts for the observed antifungal activity of the oil.

  9. Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp

    DEFF Research Database (Denmark)

    Bell, Ian H.; Wronski, Jorrit; Quoilin, Sylvain

    2014-01-01

    property correlations described here have been implemented into CoolProp, an open-source thermophysical property library. This library is written in C++, with wrappers available for the majority of programming languages and platforms of technical interest. As of publication, 110 pure and pseudo-pure fluids...... are included in the library, as well as properties of 40 incompressible fluids and humid air. The source code for the CoolProp library is included as an electronic annex....

  10. Nigeria Journal of Pure and Applied Physics

    African Journals Online (AJOL)

    Nigeria Journal of Pure and Applied Physics publishes papers of the highest quality and significance in specific areas of physics, pure and applied, as listed below. The journal content reflects core physics disciplines, but is also open to a broad range of topics whose central theme falls within the bounds of physics.

  11. Refurbishment of JMTR pure water facility

    International Nuclear Information System (INIS)

    Asano, Norikazu; Hanakawa, Hiroki; Kusunoki, Hidehiko; Satou, Shinichi

    2012-05-01

    In the refurbishment of JMTR, facilities were classified into which (1) were all updated, (2) were partly updated, and (3) were continuance used by the considerations of the maintenance history, the change parts availability and the latest technology. The JMTR pure water facility was classified into all updated facility based on the consideration. The Update construction was conducted in between FY2007 and FY2008. The refurbishment of JMTR pure water facility is summarized in this report. (author)

  12. Archives: Bayero Journal of Pure and Applied Sciences

    African Journals Online (AJOL)

    Items 1 - 20 of 20 ... Archives: Bayero Journal of Pure and Applied Sciences. Journal Home > Archives: Bayero Journal of Pure and Applied Sciences. Log in or Register to get access to full text downloads.

  13. Archives: Nigeria Journal of Pure and Applied Physics

    African Journals Online (AJOL)

    Items 1 - 6 of 6 ... Archives: Nigeria Journal of Pure and Applied Physics. Journal Home > Archives: Nigeria Journal of Pure and Applied Physics. Log in or Register to get access to full text downloads.

  14. Thermomechanical characterization of pure polycrystalline tantalum

    International Nuclear Information System (INIS)

    Rittel, D.; Bhattacharyya, A.; Poon, B.; Zhao, J.; Ravichandran, G.

    2007-01-01

    The thermomechanical behavior of pure polycrystalline tantalum has been characterized over a wide range of strain rates, using the recently developed shear compression specimen [D. Rittel, S. Lee, G. Ravichandran, Experimental Mechanics 42 (2002) 58-64]. Dynamic experiments were carried out using a split Hopkinson pressure bar, and the specimen's temperature was monitored throughout the tests using an infrared radiometer. The results of the mechanical tests confirm previous results on pure Ta. Specifically, in addition to its significant strain rate sensitivity, it was observed that pure Ta exhibits very little strain hardening at high strain rates. The measured temperature rise in the specimen's gauge was compared to theoretical predictions which assume a total conversion of the mechanical energy into heat (β = 1) [G.I. Taylor, H. Quinney, Proceedings of the Royal Society of London, vol. A, 1934, pp. 307-326], and an excellent agreement was obtained. This result confirms the previous result of Kapoor and Nemat-Nasser [R. Kapoor, S. Nemat-Nasser, Mech. Mater. 27 (1998) 1-12], while a different experimental approach was adopted here. The assumption that β = 1 is found to be justified in this specific case by the lack of dynamic strain hardening of pure Ta. However, this assumption should be limited to non-hardening materials, to reflect the fact that strain hardening implies that part of the mechanical energy is stored into the material's microstructure

  15. Pure transvaginal excision of mesh erosion involving the bladder.

    Science.gov (United States)

    Firoozi, Farzeen; Goldman, Howard B

    2013-06-01

    We present a pure transvaginal approach to the removal of eroded mesh involving the bladder secondary to placement of transvaginal mesh for management of pelvic organ prolapse (POP) using a mesh kit. Although technically challenging, we demonstrate the feasibility of a purely transvaginal approach, avoiding a potentially more morbid transabdominal approach. The video presents the surgical technique of pure transvaginal excision of mesh erosion involving the bladder after mesh placement using a prolapse kit was performed. This video shows that purely transvaginal removal of mesh erosion involving the bladder can be done safely and is feasible.

  16. Comparison of hydrogen storage properties of pure Mg and milled ...

    Indian Academy of Sciences (India)

    Administrator

    increase the hydriding and dehydriding rates, pure Mg was ground under hydrogen atmosphere (reactive .... Hydrogen storage properties of pure Mg and milled pure Mg. 833. Figure 3. ... elongated and flat shapes via collisions with the steel.

  17. Homochiral drugs: a demanding tendency of the pharmaceutical industry.

    Science.gov (United States)

    Núñez, María C; García-Rubiño, M Eugenia; Conejo-García, Ana; Cruz-López, Olga; Kimatrai, María; Gallo, Miguel A; Espinosa, Antonio; Campos, Joaquín M

    2009-01-01

    The issue of drug chirality is now a major theme in the design and development of new drugs, underpinned by a new understanding of the role of molecular recognition in many pharmacologically relevant events. In general, three methods are utilized for the production of a chiral drug: the chiral pool, separation of racemates, and asymmetric synthesis. Although the use of chiral drugs predates modern medicine, only since the 1980's has there been a significant increase in the development of chiral pharmaceutical drugs. An important commercial reason is that as patents on racemic drugs expire, pharmaceutical companies have the opportunity to extend patent coverage through development of the chiral switch enantiomers with desired bioactivity. Stimulated by the new policy statements issued by the regulatory agencies, the pharmaceutical industry has systematically begun to develop chiral drugs in enantiometrically enriched pure forms. This new trend has caused a tremendous change in the industrial small- and large-scale production to enantiomerically pure drugs, leading to the revisiting and updating of old technologies, and to the development of new methodologies of their large-scale preparation (as the use of stereoselective syntheses and biocatalyzed reactions). The final decision whether a given chiral drug will be marketed in an enantiomerically pure form, or as a racemic mixture of both enantiomers, will be made weighing all the medical, financial and social proficiencies of one or other form. The kinetic, pharmacological and toxicological properties of individual enantiomers need to be characterized, independently of a final decision.

  18. Pure Science and Applied Science

    Directory of Open Access Journals (Sweden)

    Robert J. Aumann

    2011-01-01

    Full Text Available (Excerpt The name of my talk is Pure Science and Applied Science, and the idea I would like to sell to you today is that there is no such thing as “pure” or “applied” science. In other words, there is such a thing as science, but there is no difference between pure and applied science. Science is one entity and cannot be separated into different categories. In order to back that up, I would like to tell you a little story. As an undergraduate, I studied mathematics at City College in New York. At that time, what was called Pure Mathematics was in vogue, and the more prominent mathematicians were a little contemptuous of any kind of application. A very famous, prominent mathematician in the first half of the previous century by the name of G. H. Hardy, who was in a branch of mathematics called number theory, said that the only thing he regretted was that he unwittingly did some important work in mathematical genetics that eventually turned out to have some application. … Such was the atmosphere in the late ’40s of the previous century and, being a young man and impressionable, I was swept up in this atmosphere.

  19. Enantiomeric Profiling of Chiral Pharmacologically Active Compounds in the Environment with the Usage of Chiral Liquid Chromatography 
Coupled with Tandem Mass Spectrometry

    Science.gov (United States)

    Camacho-Muñoz, Dolores; Petrie, Bruce; Castrignanò, Erika; Kasprzyk-Hordern, Barbara

    2016-01-01

    The issue of drug chirality is attracting increasing attention among the scientific community. The phenomenon of chirality has been overlooked in environmental research (environmental occurrence, fate and toxicity) despite the great impact that chiral pharmacologically active compounds (cPACs) can provoke on ecosystems. The aim of this paper is to introduce the topic of chirality and its implications in environmental contamination. Special attention has been paid to the most recent advances in chiral analysis based on liquid chromatography coupled with mass spectrometry and the most popular protein based chiral stationary phases. Several groups of cPACs of environmental relevance, such as illicit drugs, human and veterinary medicines were discussed. The increase in the number of papers published in the area of chiral environmental analysis indicates that researchers are actively pursuing new opportunities to provide better understanding of environmental impacts resulting from the enantiomerism of cPACs. PMID:27713682

  20. AdS pure spinor superstring in constant backgrounds

    International Nuclear Information System (INIS)

    Chandia, Osvaldo; Bevilaqua, L. Ibiapina; Vallilo, Brenno Carlini

    2014-01-01

    In this paper we study the pure spinor formulation of the superstring in AdS_5×S"5 around point particle solutions of the classical equations of motion. As a particular example we quantize the pure spinor string in the BMN background

  1. Graph Theory to Pure Mathematics: Some Illustrative Examples

    Indian Academy of Sciences (India)

    Graph Theory to Pure Mathematics: Some. Illustrative Examples v Yegnanarayanan is a. Professor of Mathematics at MNM Jain Engineering. College, Chennai. His research interests include graph theory and its applications to both pure maths and theoretical computer science. Keywords. Graph theory, matching theory,.

  2. Expander graphs in pure and applied mathematics

    OpenAIRE

    Lubotzky, Alexander

    2012-01-01

    Expander graphs are highly connected sparse finite graphs. They play an important role in computer science as basic building blocks for network constructions, error correcting codes, algorithms and more. In recent years they have started to play an increasing role also in pure mathematics: number theory, group theory, geometry and more. This expository article describes their constructions and various applications in pure and applied mathematics.

  3. Stereoselective synthesis of highly substituted bicyclic γ-lactones using homoaldol addition of 1-(1-cycloalkenyl)methyl carbamates

    DEFF Research Database (Denmark)

    Özlügedik, M.; Kristensen, Jesper Langgaard; Reuber, J.

    2004-01-01

    Stereoselective addition of aldehydes 4 to metallated 1-(1-cycloalkenyl) methyl N,N-diisopropylcarbamates 1 gave cyclic homoaldol adducts 6. By applying the (-)-sparteine method, enantiomerically enriched products were obtained. These were oxidatively cyclized to diastereomerically pure ¿-lactones...... 8 via the ¿-lactol ethers 7. After deprotonation of ¿-lactones 8 with lithium hexamethyldisilazide, a further substitution was achieved. By trapping the lactone enolates 11 with ß-naphthylmethyl bromide, single diastereomers of ¿-lactones 12 were produced....

  4. Pure odd-order oscillators with constant excitation

    Science.gov (United States)

    Cveticanin, L.

    2011-02-01

    In this paper the excited vibrations of a truly nonlinear oscillator are analyzed. The excitation is assumed to be constant and the nonlinearity is pure (without a linear term). The mathematical model is a second-order nonhomogeneous differential equation with strong nonlinear term. Using the first integral, the exact value of period of vibration i.e., angular frequency of oscillator described with a pure nonlinear differential equation with constant excitation is analytically obtained. The closed form solution has the form of gamma function. The period of vibration depends on the value of excitation and of the order and coefficient of the nonlinear term. For the case of pure odd-order-oscillators the approximate solution of differential equation is obtained in the form of trigonometric function. The solution is based on the exact value of period of vibration. For the case when additional small perturbation of the pure oscillator acts, the so called 'Cveticanin's averaging method' for a truly nonlinear oscillator is applied. Two special cases are considered: one, when the additional term is a function of distance, and the second, when damping acts. To prove the correctness of the method the obtained results are compared with those for the linear oscillator. Example of pure cubic oscillator with constant excitation and linear damping is widely discussed. Comparing the analytically obtained results with exact numerical ones it is concluded that they are in a good agreement. The investigations reported in the paper are of special interest for those who are dealing with the problem of vibration reduction in the oscillator with constant excitation and pure nonlinear restoring force the examples of which can be found in various scientific and engineering systems. For example, such mechanical systems are seats in vehicles, supports for machines, cutting machines with periodical motion of the cutting tools, presses, etc. The examples can be find in electronics

  5. AdS pure spinor superstring in constant backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Chandia, Osvaldo [Departamento de Ciencias, Facultad de Artes Liberales, Universidad Adolfo Ibáñez,Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez,Diagonal Las Torres 2640, Peñalolén, Santiago (Chile); Bevilaqua, L. Ibiapina [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte,Caixa Postal 1524, 59072-970, Natal, RN (Brazil); Vallilo, Brenno Carlini [Facultad de Ciencias Exactas, Departamento de Ciencias Físicas, Universidad Andres Bello,Republica 220, Santiago (Chile)

    2014-06-05

    In this paper we study the pure spinor formulation of the superstring in AdS{sub 5}×S{sup 5} around point particle solutions of the classical equations of motion. As a particular example we quantize the pure spinor string in the BMN background.

  6. Similarities and differences between learning abilities, "pure" learning disabilities, "pure" ADHD and comorbid ADHD with learning disabilities.

    Science.gov (United States)

    Mangina, Constantine A; Beuzeron-Mangina, Helen

    2009-08-01

    This research pursues the crucial question of the differentiation of preadolescents with "Pure" ADHD, comorbid ADHD with learning disabilities, "Pure" learning disabilities and age-matched normal controls. For this purpose, Topographic Mapping of Event-Related Brain Potentials (ERPs) to a Memory Workload Paradigm with visually presented words, Bilateral Electrodermal Activity during cognitive workload and Mangina-Test performance were used. The analysis of Topographic distribution of amplitudes revealed that normal preadolescents were significantly different from "Pure" ADHD (Plearning disabilities (Plearning disabilities (Plearning disabilities have shown a marked reduction of prefrontal and frontal negativities (N450). As for the "Pure" Learning Disabled preadolescents, very small positivities (P450) in prefrontal and frontal regions were obtained as compared to the other pathological groups. Bilateral Electrodermal Activity during cognitive workload revealed a significant main effect for groups (P<0.00001), Left versus Right (P=0.0029) and sessions (P=0.0136). A significant main effect for the Mangina-Test performance which separated the four groups was found (P<0.000001). Overall, these data support the existence of clear differences and similarities between the pathological preadolescent groups as opposed to age-matched normal controls. The psychophysiological differentiation of these groups, provides distinct biological markers which integrate central, autonomic and neuropsychometric variables by targeting the key features of these pathologies for diagnosis and intervention strategies and by providing knowledge for the understanding of normal neurocognitive processes and functions.

  7. Corrosion of pure magnesium under thin electrolyte layers

    International Nuclear Information System (INIS)

    Zhang Tao; Chen Chongmu; Shao Yawei; Meng Guozhe; Wang Fuhui; Li Xiaogang; Dong Chaofang

    2008-01-01

    The corrosion behavior of pure magnesium was investigated by means of cathodic polarization curve, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) under aerated and deaerated thin electrolyte layers (TEL) with various thicknesses. Based on shot noise theory and stochastic theory, the EN results were quantitatively analyzed by using the Weibull and Gumbel distribution function, respectively. The results show that the cathodic process of pure magnesium under thin electrolyte layer was dominated by hydrogen reduction. With the decreasing of thin electrolyte layer thickness, cathodic process was retarded slightly while the anodic process was inhibited significantly, which indicated that both the cathodic and anodic process were inhibited in the presence of oxygen. The absence of oxygen decreased the corrosion resistance of pure magnesium in case of thin electrolyte layer. The corrosion was more localized under thin electrolyte layer than that in bulk solution. The results also demonstrate that there exist two kinds of effects for thin electrolyte layer on the corrosion behavior of pure magnesium: (1) the rate of pit initiation was evidently retarded compared to that in bulk solution; (2) the probability of pit growth oppositely increased. The corrosion model of pure magnesium under thin electrolyte layer was suggested in the paper

  8. Engineering arbitrary pure and mixed quantum states

    International Nuclear Information System (INIS)

    Pechen, Alexander

    2011-01-01

    Controlled manipulation by atomic- and molecular-scale quantum systems has attracted a lot of research attention in recent years. A fundamental problem is to provide deterministic methods for controlled engineering of arbitrary quantum states. This work proposes a deterministic method for engineering arbitrary pure and mixed states of a wide class of quantum systems. The method exploits a special combination of incoherent and coherent controls (incoherent and coherent radiation) and has two properties which are specifically important for manipulating by quantum systems: it realizes the strongest possible degree of their state control, complete density matrix controllability, meaning the ability to steer arbitrary pure and mixed initial states into any desired pure or mixed final state, and it is all-to-one, such that each particular control transfers all initial system states into one target state.

  9. Enantioselective hydrolysis of racemic styrene oxide and its substituted derivatives using newly-isolated Sphingopyxis sp. exhibiting a novel epoxide hydrolase activity.

    Science.gov (United States)

    Woo, Jung-Hee; Lee, Eun Yeol

    2014-02-01

    (S)-Styrene oxide, (S)-2-chlorostyrene oxide (CSO), (S)-3-CSO and (S)-4-CSO with 99.9 %ee were obtained with a yield of 20.6, 39.3, 28.7 and 26.8 % from 4 mM corresponding racemic substrates using 10 mg cells of a newly-isolated Sphingopyxis sp. at pH 8.0 and 25 °C in 1 ml 100 mM Tris/HCl buffer after 420, 100, 120 and 55 min, respectively. For racemic 2CSO, well-known for one of the racemates that is difficult to obtained in enantiomerically pure form, (S)-2-CSO with 99.9 %ee, 39.3 % yield (theoretical yield 50 %) and enantiomeric ratio of 42.1 was obtained. The newly-isolated strain can thus be used as whole-cell biocatalyst in the production of various (S)-CSO with a chlorine group at different positions.

  10. Complex windmill transformation producing new purely magnetic fluids

    International Nuclear Information System (INIS)

    Lozanovski, C; Wylleman, L

    2011-01-01

    Minimal complex windmill transformations of G 2 IB(ii) spacetimes (admitting a two-dimensional Abelian group of motions of the so-called Wainwright B(ii) class) are defined and the compatibility with a purely magnetic Weyl tensor is investigated. It is shown that the transformed spacetimes cannot be perfect fluids or purely magnetic Einstein spaces. We then determine which purely magnetic perfect fluids (PMpfs) can be windmill-transformed into purely magnetic anisotropic fluids (PMafs). Assuming separation of variables, complete integration produces two, algebraically general, G 2 I-B(ii) PMpfs: a solution with zero 4-acceleration vector and spatial energy-density gradient, previously found by the authors, and a new solution in terms of Kummer's functions, where these vectors are aligned and non-zero. The associated windmill PMafs are rotating but non-expanding. Finally, an attempt to relate the spacetimes to each other by a simple procedure leads to a G 2 I-B(ii) one-parameter PMaf generalization of the previously found metric.

  11. Purely leptonic currents

    International Nuclear Information System (INIS)

    Gourdin, M.

    1976-01-01

    In most gauge theories weak neutral currents appear as a natural consequence of the models, but the specific properties are not predicted in a general way. In purely leptonic interactions the structure of these currents can be tested without making assumptions about the weak couplings of the hadrons. The influence of neutral currents appearing in the process e + e - → μ + μ - can be measured using the polarization of the outgoing myons. (BJ) [de

  12. Language as Pure Potential

    Science.gov (United States)

    Park, Joseph Sung-Yul

    2016-01-01

    Language occupies a crucial position in neoliberalism, due to the reimagination of language as commodified skill. This paper studies the role of language ideology in this transformation by identifying a particular ideology that facilitates this process, namely the ideology which views language as pure potential. Neoliberalism treats language as a…

  13. Dahlbeck and Pure Ontology

    Science.gov (United States)

    Mackenzie, Jim

    2016-01-01

    This article responds to Johan Dahlbeck's "Towards a pure ontology: Children's bodies and morality" ["Educational Philosophy and Theory," vol. 46 (1), 2014, pp. 8-23 (EJ1026561)]. His arguments from Nietzsche and Spinoza do not carry the weight he supposes, and the conclusions he draws from them about pedagogy would be…

  14. Chapter 12. Pure Tap Water Hydraulic Systems and Applications

    DEFF Research Database (Denmark)

    Conrad, Finn; Adelstorp, Anders

    1997-01-01

    Presentation of developed a modern pure tap water hydraulic components (Nessie), systems and industrial applications.......Presentation of developed a modern pure tap water hydraulic components (Nessie), systems and industrial applications....

  15. Production of pure metals

    Science.gov (United States)

    Philipp, W. H.; Marsik, S. J.; May, C. E. (Inventor)

    1974-01-01

    A process for depositing elements by irradiating liquids is reported. Ultra pure elements are precipitated from aqueous solutions or suspensions of compounds. A solution of a salt of a metal to be prepared is irradiated, and the insoluble reaction product settles out. Some chemical compounds may also be prepared in this manner.

  16. Entropy balance in pure interactions of open quantum systems

    International Nuclear Information System (INIS)

    Urigu, R.

    1989-01-01

    Processes are considered in which a statistical ensemble w of quantum systems is split into ensembles, or channels (w i ), conditional to the occurrence, with respective probabilities (p i w ), of associated macroscopic effects. These processes are described here by a family of operations T i : w → p i w w iT , which remarkably generalize the usual state reductions of the nondestructive measurements. In a previous work it was proved that the microscopic entropy of the given open system decreases or at most remains constant if all the T i are pure operations, i.e., they transform pure states into pure states; it is proved here that the increase in entropy of the external world, computed as S Tm (w) = - Σ i p i w lg p i w , is sufficient to compensate for such an entropy decrease whenever the T i are all pure operations of the first kind, whereas whenever some T i is pure of the second kind (or nonpure, too), the total entropy, computed as above, may decrease

  17. Design and synthesis of enantiomerically enriched, radiolabeled MK-801 analogs as potential radiotracers for imaging and autoradiographic studies of the NMDA receptor-ion channel complex

    International Nuclear Information System (INIS)

    Eng, W.S.; Burns, H.D.; Gibson, R.E.; Ransom, R.W.; Thorpe, H.; Fioravanit, C.; Britcher, S.F.; Magill, C.A.; Solomon, H.F.; Dannals, R.F.; Wilson, A.A.; Ravert, H.T.; Wagner, H.N.

    1989-01-01

    MK-801 is a potent, non-competitive antagonist for the N-methyl-D-asspartate (NMDA) receptor-ion channel complex. This complex is though to be involved in nerve cell damage in stroke patients when excess calcium is released through the activated channel. A thorough understanding of drug interactions with the NMDA receptor complex could lead to improved therapy for reducing hypoxic-ischemic neuronal injuries in stroke patients. Based on the results of extensive structure-activity studies, the authors have developed several enantiomerically enriched, radiolabeled analogs of MK-801, including: 3-1231-MK-801 for Single Photon Emission Computed tomography (SPECT); 3-1251-MK-801 for in-vivo and in-vitro autoradiography; 8-11C-MeO-MK-801 for Positron Emission Tomography (PET). Details of the synthesis of these radiotracers and their application to both in-vitro and in-vivo studies are described

  18. Molecular recognition and self-assembly special feature: A general protocol for creating high-throughput screening assays for reaction yield and enantiomeric excess applied to hydrobenzoin.

    Science.gov (United States)

    Shabbir, Shagufta H; Regan, Clinton J; Anslyn, Eric V

    2009-06-30

    A general approach to high-throughput screening of enantiomeric excess (ee) and concentration was developed by using indicator displacement assays (IDAs), and the protocol was then applied to the vicinal diol hydrobenzoin. The method involves the sequential utilization of what we define herein as screening, training, and analysis plates. Several enantioselective boronic acid-based receptors were screened by using 96-well plates, both for their ability to discriminate the enantiomers of hydrobenzoin and to find their optimal pairing with indicators resulting in the largest optical responses. The best receptor/indicator combination was then used to train an artificial neural network to determine concentration and ee. To prove the practicality of the developed protocol, analysis plates were created containing true unknown samples of hydrobenzoin generated by established Sharpless asymmetric dihydroxylation reactions, and the best ligand was correctly identified.

  19. Ammonia lyases and aminomutases as biocatalysts for the synthesis of α-amino and β-amino acids.

    Science.gov (United States)

    Turner, Nicholas J

    2011-04-01

    Ammonia lyases catalyse the reversible addition of ammonia to cinnamic acid (1: R=H) and p-hydroxycinnamic (1: R=OH) to generate L-phenylalanine (2: R=H) and L-tyrosine (2: R=OH) respectively (Figure 1a). Both phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) are widely distributed in plants, fungi and prokaryotes. Recently there has been interest in the use of these enzymes for the synthesis of a broader range of L-arylalanines. Aminomutases catalyse a related reaction, namely the interconversion of α-amino acids to β-amino acids (Figure 1b). In the case of L-phenylalanine, this reaction is catalysed by phenylalanine aminomutase (PAM) and proceeds stereospecifically via the intermediate cinnamic acid to generate β-Phe 3. Ammonia lyases and aminomutases are related in sequence and structure and share the same active site cofactor 4-methylideneimidazole-5-one (MIO). There is currently interest in the possibility of using these biocatalysts to prepare a wide range of enantiomerically pure l-configured α-amino and β-amino acids. Recent reviews have focused on the mechanism of these MIO containing enzymes. The aim of this review is to review recent progress in the application of ammonia lyase and aminomutase enzymes to prepare enantiomerically pure α-amino and β-amino acids. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Complete genome sequence of N2-fixing model strain Klebsiella sp. nov. M5al, which produces plant cell wall-degrading enzymes and siderophores

    Directory of Open Access Journals (Sweden)

    Zhili Yu

    2018-03-01

    Full Text Available The bacterial strain M5al is a model strain for studying the molecular genetics of N2-fixation and molecular engineering of microbial production of platform chemicals 1,3-propanediol and 2,3-butanediol. Here, we present the complete genome sequence of the strain M5al, which belongs to a novel species closely related to Klebsiella michiganensis. M5al secretes plant cell wall-degrading enzymes and colonizes rice roots but does not cause soft rot disease. M5al also produces siderophores and contains the gene clusters for synthesis and transport of yersiniabactin which is a critical virulence factor for Klebsiella pathogens in causing human disease. We propose that the model strain M5al can be genetically modified to study bacterial N2-fixation in association with non-legume plants and production of 1,3-propanediol and 2,3-butanediol through degradation of plant cell wall biomass.

  1. Acorenone B: AChE and BChE Inhibitor as a Major Compound of the Essential Oil Distilled from the Ecuadorian Species Niphogeton dissecta (Benth. J.F. Macbr

    Directory of Open Access Journals (Sweden)

    James Calva

    2017-10-01

    Full Text Available This study investigated the chemical composition, physical proprieties, biological activity, and enantiomeric analysis of the essential oil from the aerial parts of Niphogeton dissecta (culantrillo del cerro from Ecuador, obtained by steam distillation. The qualitative and quantitative analysis of the essential oil was realized by gas chromatographic and spectroscopic techniques (GC-MS and GC-FID. Acorenone B was identified by GC-MS and NMR experiments. The enantiomeric distribution of some constituents has been assessed by enantio-GC through the use of a chiral cyclodextrin-based capillary column. We identified 41 components that accounted for 96.46% of the total analyzed, the major components were acorenone B (41.01% and (E-β-ocimene (29.64%. The enantiomeric ratio of (+/(−-β-pinene was 86.9:13.1, while the one of (+/(−-sabinene was 80.9:19.1. The essential oil showed a weak inhibitory activity, expressed as Minimal Inhibitory Concentration (MIC, against Enterococcus faecalis (MIC 10 mg/mL and Staphylococcus aureus (MIC 5 mg/mL. Furthermore, it inhibited butyrylcholinesterase with an IC50 value of 11.5 μg/mL. Pure acorenone B showed inhibitory activity against both acetylcholinesterase and butyrylcholinesterase, with IC50 values of 40.8 μg/mL and 10.9 μg/mL, respectively.

  2. Nigeria Journal of Pure and Applied Physics: Journal Sponsorship

    African Journals Online (AJOL)

    Nigeria Journal of Pure and Applied Physics: Journal Sponsorship. Journal Home > About the Journal > Nigeria Journal of Pure and Applied Physics: Journal Sponsorship. Log in or Register to get access to full text downloads.

  3. Nigeria Journal of Pure and Applied Physics: Site Map

    African Journals Online (AJOL)

    Nigeria Journal of Pure and Applied Physics: Site Map. Journal Home > About the Journal > Nigeria Journal of Pure and Applied Physics: Site Map. Log in or Register to get access to full text downloads.

  4. Seasonal characteristics and current sources of OCPs and PCBs and enantiomeric signatures of chiral OCPs in the atmosphere of Vietnam.

    Science.gov (United States)

    Wang, Weitao; Wang, Yinghui; Zhang, Ruijie; Wang, Shaopeng; Wei, Chaoshuai; Chaemfa, Chakra; Li, Jun; Zhang, Gan; Yu, Kefu

    2016-01-15

    Passive air samplers (PAS) were deployed concurrently at 15 locations (nine urban sites and six rural sites) in Vietnam and exposed for approximately 6 weeks from June 26, 2012 to August 26, 2012 and from December 8, 2012 to February 8, 2013. The concentration, composition and enantiomeric signatures of the target compound and Air Mass Backward Trajectories of the 15 sampling sites are presented and discussed in this study. Relatively clean air mass from ocean and similar concentrations and composition of POPs between the south and north of Vietnam indicate that local emissions is most likely the major source of POPs in Vietnam. Technical DDT and technical HCH were widely used in Vietnam and corresponding quantitative data suggests the sporadic use. The preferential degradation of (+)-α-HCH was found in all sampling sites, which could be a regional characteristic of Vietnam. High trans-/cis-chlordane (TC/CC) ratios indicate the current use of technical chlordane for termite control. PCA estimated that main source of PCBs present in the atmosphere of Vietnam was uncontrolled discarded e-waste. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Black hole attractors and pure spinors

    International Nuclear Information System (INIS)

    Hsu, Jonathan P.; Maloney, Alexander; Tomasiello, Alessandro

    2006-01-01

    We construct black hole attractor solutions for a wide class of N = 2 compactifications. The analysis is carried out in ten dimensions and makes crucial use of pure spinor techniques. This formalism can accommodate non-Kaehler manifolds as well as compactifications with flux, in addition to the usual Calabi-Yau case. At the attractor point, the charges fix the moduli according to Σf k = Im(CΦ), where Φ is a pure spinor of odd (even) chirality in IIB (A). For IIB on a Calabi-Yau, Φ = Ω and the equation reduces to the usual one. Methods in generalized complex geometry can be used to study solutions to the attractor equation

  6. Black Hole Attractors and Pure Spinors

    International Nuclear Information System (INIS)

    Hsu, Jonathan P.; Maloney, Alexander; Tomasiello, Alessandro

    2006-01-01

    We construct black hole attractor solutions for a wide class of N = 2 compactifications. The analysis is carried out in ten dimensions and makes crucial use of pure spinor techniques. This formalism can accommodate non-Kaehler manifolds as well as compactifications with flux, in addition to the usual Calabi-Yau case. At the attractor point, the charges fix the moduli according to Σf k = Im(CΦ), where Φ is a pure spinor of odd (even) chirality in IIB (A). For IIB on a Calabi-Yau, Φ = (Omega) and the equation reduces to the usual one. Methods in generalized complex geometry can be used to study solutions to the attractor equation

  7. Pure Air`s Bailly scrubber: A four-year retrospective

    Energy Technology Data Exchange (ETDEWEB)

    Manavi, G.B.; Vymazal, D.C. [Pure Air, Allentown, PA (United States); Sarkus, T.A. [Dept. of Energy, Pittsburgh, PA (United States)

    1997-12-31

    Pure Air`s Advanced Flue Gas Desulfurization (AFGD) Clean Coal Project has completed four highly successful years of operation at NIPSCO`s Bailly Station. As part of their program, Pure Air has concluded a six-part study of system performance. This paper summarizes the results of the demonstration program, including AFGD performance on coals ranging from 2.0--2.4% sulfur. The paper highlights novel aspects of the Bailly facility, including pulverized limestone injection, air rotary sparger for oxidation, wastewater evaporation system and the production of PowerChip{reg_sign} gypsum. Operations and maintenance which have led to the facility`s notable 99.47% availability record are also discussed. A project company, Pure Air on the Lake Limited Partnership, owns the AFGD facility. Pure Air was the turn key contractor and Air Products and Chemicals, Inc. is the operator of the AFGD system.

  8. Shunting arc plasma source for pure carbon ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y. [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2012-02-15

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm{sup 2} at the peak of the pulse.

  9. Shunting arc plasma source for pure carbon ion beam.

    Science.gov (United States)

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse.

  10. Corrosion of pure OFHC-copper in simulated repository conditions

    International Nuclear Information System (INIS)

    Aaltonen, P.

    1990-04-01

    The research program 'Corrosion of pure OFHC-copper in simulated repository conditions' was planned to provide an experimental evaluation with respect to the theoretical calculations and forecasts made for the corrosion behaviour of pure copper in bentonite groundwater environments at temperatures between 20-80 deg C. The aim of this study in the first place is to evaluate the effects of groundwater composition, bentonite and temperature on the equilibrium and possible corrosion reactions between pure copper and the simulated repository environment. The progress report includes the results obtained after 36 months exposure time

  11. Pure Electric and Pure Magnetic Resonances in Near-Infrared Metal Double-Triangle Metamaterial Arrays

    International Nuclear Information System (INIS)

    Cao Zhi-Shen; Pan Jian; Chen Zhuo; Zhan Peng; Min Nai-Ben; Wang Zhen-Lin

    2011-01-01

    We experimentally and numerically investigate the optical properties of metamaterial arrays composed of double partially-overlapped metallic nanotriangles fabricated by an angle-resolved nanosphere lithography. We demonstrate that each double-triangle can be viewed as an artificial magnetic element analogous to the conventional metal split-ring-resonator. It is shown that under normal-incidence conditions, individual double-triangle can exhibit a strong local magnetic resonance, but the collective response of the metamaterial arrays is purely electric because magnetic resonances of the two double-triangles in a unit cell having opposite openings are out of phase. For oblique incidences the metamaterial arrays are shown to support a pure magnetic response at the same frequency band. Therefore, switchable electric and magnetic resonances are achieved in double-triangle arrays. Moreover, both the electric and magnetic resonances are shown to allow for a tunability over a large spectral range down to near-infrared. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  12. Superposing pure quantum states with partial prior information

    Science.gov (United States)

    Dogra, Shruti; Thomas, George; Ghosh, Sibasish; Suter, Dieter

    2018-05-01

    The principle of superposition is an intriguing feature of quantum mechanics, which is regularly exploited in many different circumstances. A recent work [M. Oszmaniec et al., Phys. Rev. Lett. 116, 110403 (2016), 10.1103/PhysRevLett.116.110403] shows that the fundamentals of quantum mechanics restrict the process of superimposing two unknown pure states, even though it is possible to superimpose two quantum states with partial prior knowledge. The prior knowledge imposes geometrical constraints on the choice of input states. We discuss an experimentally feasible protocol to superimpose multiple pure states of a d -dimensional quantum system and carry out an explicit experimental realization for two single-qubit pure states with partial prior information on a two-qubit NMR quantum information processor.

  13. Minimal covariant observables identifying all pure states

    Energy Technology Data Exchange (ETDEWEB)

    Carmeli, Claudio, E-mail: claudio.carmeli@gmail.com [D.I.M.E., Università di Genova, Via Cadorna 2, I-17100 Savona (Italy); I.N.F.N., Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Heinosaari, Teiko, E-mail: teiko.heinosaari@utu.fi [Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku (Finland); Toigo, Alessandro, E-mail: alessandro.toigo@polimi.it [Dipartimento di Matematica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); I.N.F.N., Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy)

    2013-09-02

    It has been recently shown by Heinosaari, Mazzarella and Wolf (2013) [1] that an observable that identifies all pure states of a d-dimensional quantum system has minimally 4d−4 outcomes or slightly less (the exact number depending on d). However, no simple construction of this type of minimal observable is known. We investigate covariant observables that identify all pure states and have minimal number of outcomes. It is shown that the existence of this kind of observables depends on the dimension of the Hilbert space.

  14. Critical opalescence in the pure Coulomb system

    Science.gov (United States)

    Bobrov, V. B.; Trigger, S. A.

    2011-04-01

    Based on the dielectric formalism and quantum field theory methods, the phenomenon of critical opalescence is explained for light scattering in pure matter as a two-component electron-nuclear system with Coulomb interaction. A similar phenomenon is shown to occur in the case of neutron scattering in pure substances as well. The obtained results are valid for quantum case and arbitrary strong Coulomb interaction. Thus, the relations between structure factors derived for the electron-nuclear system are the exact result of the quantum statistical mechanics.

  15. In vitro corrosion, cytotoxicity and hemocompatibility of bulk nanocrystalline pure iron

    International Nuclear Information System (INIS)

    Nie, F L; Zheng, Y F; Wei, S C; Hu, C; Yang, G

    2010-01-01

    Bulk nanocrystalline pure iron rods were fabricated by the equal channel angular pressure (ECAP) technique up to eight passes. The microstructure and grain size distribution, natural immersion and electrochemical corrosion in simulated body fluid, cellular responses and hemocompatibility were investigated in this study. The results indicate that nanocrystalline pure iron after severe plastic deformation (SPD) would sustain durable span duration and exhibit much stronger corrosion resistance than that of the microcrystalline pure iron. The interaction of different cell lines reveals that the nanocrystalline pure iron stimulates better proliferation of fibroblast cells and preferable promotion of endothelialization, while inhibits effectively the viability of vascular smooth muscle cells (VSMCs). The burst of red cells and adhesion of the platelets were also substantially suppressed on contact with the nanocrystalline pure iron in blood circulation. A clear size-dependent behavior from the grain nature deduced by the gradual refinement microstructures was given and well-behaved in vitro biocompatibility of nanocrystalline pure iron was concluded.

  16. Compact objects in pure Lovelock theory

    Science.gov (United States)

    Dadhich, Naresh; Hansraj, Sudan; Chilambwe, Brian

    For static fluid interiors of compact objects in pure Lovelock gravity (involving only one Nth order term in the equation), we establish similarity in solutions for the critical odd and even d = 2N + 1, 2N + 2 dimensions. It turns out that in critical odd d = 2N + 1 dimensions, there cannot exist any bound distribution with a finite radius, while in critical even d = 2N + 2 dimensions, all solutions have similar behavior. For exhibition of similarity, we would compare star solutions for N = 1, 2 in d = 4 Einstein and d = 6 in Gauss-Bonnet theory, respectively. We also obtain the pure Lovelock analogue of the Finch-Skea model.

  17. Spatial distributions and enantiomeric signatures of DDT and its metabolites in tree bark from agricultural regions across China.

    Science.gov (United States)

    Niu, Lili; Xu, Chao; Zhang, Chunlong; Zhou, Yuting; Zhu, Siyu; Liu, Weiping

    2017-10-01

    Tree bark is considered as an effective passive sampler for estimating the atmospheric status of pollutants. In this study, we conducted a national scale tree bark sampling campaign across China. Concentration profiles revealed that Eastern China, especially the Jing-Jin-Ji region (including Hebei Province, Beijing and Tianjin) was a hot spot of bark DDT pollution. The enantioselective accumulation of o,p'-DDT was observed in most of the samples and 68% of them showed a preferential depletion of (+)-o,p'-DDT. These results suggest that DDTs in rural bark are likely from combined sources including historical technical DDTs and fresh dicofol usage. The tree bulk DDT levels were found to correlate with soil DDT concentrations, socioeconomy and PM 2.5 of the sampling sites. It thus becomes evident that the reemission from soils and subsequent atmospheric deposition were the major pathways leading to the accumulation of DDTs in bark. Based on a previously established bark-air partitioning model, the concentrations of DDTs in the air were estimated from measured concentrations in tree bark, and the results were comparable to those obtained by the use of passive sampling with polyurethane foam (PUF) disks. Our results demonstrate the feasibility of delineating the spatial variations in atmospheric concentration and tracing sources of DDTs by integrating the use of tree bark with enantiomeric analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. On pure spinor formalism for quantum superstring and spinor moving frame

    International Nuclear Information System (INIS)

    Bandos, Igor A

    2013-01-01

    The D = 10 pure spinor constraint can be solved in terms of spinor moving frame variables v -α q and eight-component complex null vector Λ + q , Λ + q Λ + q =0, which can be related to the κ-symmetry ghost. Using this and similar solutions for the conjugate pure spinor and other elements of the non-minimal pure spinor formalism, we present a (hopefully useful) reformulation of the measure of the pure spinor path integral for superstring in terms of products of Cartan forms corresponding to the coset of 10D Lorentz group and to the coset of complex orthogonal group SO(8, C). Our study suggests a possible complete reformulation of the pure spinor superstring in terms of new irreducible set of variable. (paper)

  19. Cohomology in the Pure Spinor Formalism for the Superstring

    International Nuclear Information System (INIS)

    Berkovits, Nathan

    2000-01-01

    A manifestly super-Poincare covariant formalism for the superstring has recently been constructed using a pure spinor variable. Unlike the covariant Green-Schwarz formalism, this new formalism is easily quantized with a BRST operator and tree-level scattering amplitudes have been evaluated in a manifestly covariant manner. In this paper, the cohomology of the BRST operator in the pure spinor formalism is shown to give the usual light-cone Green-Schwarz spectrum. Although the BRST operator does not directly involve the Virasoro constraint, this constraint emerges after expressing the pure spinor variable in terms of SO(8) variables. (author)

  20. Properties and distribution of pure GA-sequences of mammalian genomes.

    Directory of Open Access Journals (Sweden)

    Guenter Albrecht-Buehler

    Full Text Available The article describes DNA sequences of mammalian genomes that are longer than 50 bases, but consist exclusively of G's and A's ('pure GA-sequences'. Although their frequency of incidence should be 10(-16 or smaller, the chromosomes of human, chimpanzee, dog, cat, rat, and mouse contained many tens of thousands of them ubiquitously located along the chromosomes with a species-dependent density, reaching sizes of up to 1300 [b]. With the exception of a small number of poly-A-, poly-G-, poly-GA-, and poly-GAAA-sequences (combined <0.5%, all pure GA-sequences of the mammals tested were unique individuals, contained several repeated short GA-containing motifs, and shared a common hexa-nucleotide spectrum. At most 2% of the human GA-sequences were transcribed into mRNAs; all others were not coding for proteins. Although this could have made them less subject to natural selection, they contained many [corrected] times fewer point mutations than one should expect from the genome at large. As to the presence of other sequences with similarly restricted base contents, there were approximately as many pure TC-sequences as pure GA-sequences, but many fewer pure AC-, TA, and TG-sequences. There were practically no pure GC-sequences. The functions of pure GA-sequences are not known. Supported by a number of observations related to heat shock phenomena, the article speculates that they serve as genomic sign posts which may help guide polymerases and transcription factors to their proper targets, and/or as spatial linkers that help generate the 3-dimensional organization of chromatin.

  1. The effect of pure state structure on nonequilibrium dynamics

    International Nuclear Information System (INIS)

    Newman, C M; Stein, D L

    2008-01-01

    Motivated by short-range Ising spin glasses, we review some rigorous results and their consequences for the relation between the number/nature of equilibrium pure states and nonequilibrium dynamics. Two of the consequences for spin glass dynamics following an instantaneous deep quench to a temperature with broken spin flip symmetry are: (1) almost all initial configurations lie on the boundary between the basins of attraction of multiple pure states; (2) unless there are uncountably many pure states with almost all pairs having zero overlap, there can be no equilibration to a pure state as time t → ∞. We discuss the relevance of these results to the difficulty of equilibration of spin glasses. We also review some results concerning the 'nature versus nurture' problem of whether the large-t behavior of both ferromagnets and spin glasses following a deep quench is determined more by the initial configuration (nature) or by the dynamics realization (nurture)

  2. Visual processing in pure alexia

    DEFF Research Database (Denmark)

    Starrfelt, Randi; Habekost, Thomas; Gerlach, Christian

    2010-01-01

    affected. His visual apprehension span was markedly reduced for letters and digits. His reduced visual processing capacity was also evident when reporting letters from words. In an object decision task with fragmented pictures, NN's performance was abnormal. Thus, even in a pure alexic patient with intact...

  3. Electron Acoustic Waves in Pure Ion Plasmas

    Science.gov (United States)

    Anderegg, F.; Driscoll, C. F.; Dubin, D. H. E.; O'Neil, T. M.

    2009-11-01

    Electron Acoustic Waves (EAW) are the low frequency branch of electrostatic plasma waves. These waves exist in neutralized plasmas, pure electron plasmas and in pure ion plasmasfootnotetextF. Anderegg et al., PRL 102, 095001 (2009) and PoP 16, 055705 (2009). (where the name is deceptive). Here, we observe standing mθ= 0 mz= 1 EAWs in a pure ion plasma column. At small amplitude, the EAWs have a phase velocity vph ˜1.4 v, and the frequencies are in close agreement with theory. At moderate amplitudes, waves can be excited over a broad range of frequencies, with observed phase velocities in the range of 1.4 v vph diagnostic shows that particles slower than vph oscillate in phase with the wave, while particles moving faster than vph oscillate 180^o out of phase with the wave. From a fluid perspective, this gives an unusual negative dynamical compressibility. That is, the wave pressure oscillations are 180^o out of phase from the density oscillations, almost fully canceling the electrostatic restoring force, giving the low and malleable frequency.

  4. Laser-induced generation of pure tensile stresses

    International Nuclear Information System (INIS)

    Niemz, M.H.; Lin, C.P.; Pitsillides, C.; Cui, J.; Doukas, A.G.; Deutsch, T.F.

    1997-01-01

    While short compressive stresses can readily be produced by laser ablation, the generation of pure tensile stresses is more difficult. We demonstrate that a 90 degree prism made of polyethylene can serve to produce short and pure tensile stresses. A compressive wave is generated by ablating a thin layer of strongly absorbing ink on one surface of the prism with a Q-switched frequency-doubled Nd:YAG laser. The compressive wave driven into the prism is reflected as a tensile wave by the polyethylene-air interface at its long surface. The low acoustic impedance of polyethylene makes it ideal for coupling tensile stresses into liquids. In water, tensile stresses up to -200bars with a rise time of the order of 20 ns and a duration of 100 ns are achieved. The tensile strength of water is determined for pure tensile stresses lasting for 100 ns only. The technique has potential application in studying the initiation of cavitation in liquids and in comparing the effect of compressive and tensile stress transients on biological media. copyright 1997 American Institute of Physics

  5. Development of [11C]/[3H]THK-5351 – A potential novel carbon-11 tau imaging PET radioligand

    International Nuclear Information System (INIS)

    Stepanov, Vladimir; Svedberg, Marie; Jia, Zhisheng; Krasikova, Raisa; Lemoine, Laetitia; Okamura, Nobujuki; Furumoto, Shozo; Mitsios, Nicholas; Mulder, Jan; Långström, Bengt; Nordberg, Agneta; Halldin, Christer

    2017-01-01

    Introduction: Due to the rise in the number of patients with dementia the imperative for finding new diagnostic and treatment options becomes ever more pressing. While significant progress has been made in PET imaging of Aβ aggregates both in vitro and in vivo, options for imaging tau protein aggregates selectively are still limited. Based on the work previously published by researchers from the Tohoku University, Japan, that resulted in the development of [ 18 F]THK-5351, we have undertaken an effort to develop a carbon-11 version of the identical structure - [ 11 C]THK-5351. In parallel, THK-5351 was also labeled with tritium ([ 3 H]THK-5351) for use in in vitro autoradiography (ARG). Methods: The carbon-11 labeling was performed starting with di-protected enantiomeric pure precursor - tert-butyl 5-(6-((2S)-3-fluoro-2-(tetrahydro-2H-pyran-2-yloxy)propoxy)quinolin-2-yl) pyridin-2-yl carbamate, which was reacted with [ 11 C]MeI, using DMF as the solvent and NaH as base, followed by deprotection with trifluoroacetic acid/water mixture, resulting in enantiomerically pure carbon-11 radioligand, [ 11 C]THK-5351 - (S)-1-fluoro-3-(2-(6-([ 11 C]methylamino)pyridin-3-yl)quinolin-6-yloxy) propan-2-ol. Tritium labeling and purification of [ 3 H]THK-5351 were undertaken using similar approach, resulting in [ 3 H]THK-5351 with RCP >99.8% and specific radioactivity of 1.3 GBq/μmol. Results: [ 11 C]THK-5351 was produced in good yield (1900 ± 355 MBq), specific radioactivity (SRA) (361 ± 119 GBq/μmol at EOS + 20 min) and radiochemical purity (RCP) (>99.8%), with enantiomeric purity of 98.7%. [ 3 H]THK-5351 was evaluated for ARG of tau binding in post-mortem human brain tissue using cortical sections from one AD patient and one control subject. [ 3 H]THK-5351 binding density was higher in the AD patient compared to the control subject, the binding was displaced by unlabeled THK-5351 confirming specific [ 3 H]THK-5351 binding.

  6. Pure spinor formalism as an N = 2 topological string

    International Nuclear Information System (INIS)

    Berkovits, Nathan

    2005-01-01

    Following suggestions of Nekrasov and Siegel, a non-minimal set of fields are added to the pure spinor formalism for the superstring. Twisted c-circumflex = 3 N = 2 generators are then constructed where the pure spinor BRST operator is the fermionic spin-one generator, and the formalism is interpreted as a critical topological string. Three applications of this topological string theory include the super-Poincare covariant computation of multiloop superstring amplitudes without picture-changing operators, the construction of a cubic open superstring field theory without contact-term problems, and a new four-dimensional version of the pure spinor formalism which computes F-terms in the spacetime action

  7. Pure soliton solutions of some nonlinear partial differential equations

    International Nuclear Information System (INIS)

    Fuchssteiner, B.

    1977-01-01

    A general approach is given to obtain the system of ordinary differential equations which determines the pure soliton solutions for the class of generalized Korteweg-de Vries equations. This approach also leads to a system of ordinary differential equations for the pure soliton solutions of the sine-Gordon equation. (orig.) [de

  8. Pure Surface Texture Mapping Technology and it's Application for Mirror Image

    Directory of Open Access Journals (Sweden)

    Wei Feng Wang

    2013-02-01

    Full Text Available Based on the study of pure surface texture mapping technology, pure texture surface rendering method is proposed. The method is combined pure surface texture rendering and view mirror, real-time rendering has an index of refraction, reflection, and the flow of water ripple effect. Through the experimental verification of the validity of the algorithm.

  9. Nigeria Journal of Pure and Applied Physics: About this journal

    African Journals Online (AJOL)

    Nigeria Journal of Pure and Applied Physics: About this journal. Journal Home > Nigeria Journal of Pure and Applied Physics: About this journal. Log in or Register to get access to full text downloads.

  10. Mechanism of iron uptake by the pathogenic yeast, Candida albicans

    International Nuclear Information System (INIS)

    Ismail, A.

    1986-01-01

    C. albicans requires iron for growth and phenotypic development. When deprived of iron, mycelium and bud formation was suppressed. Survival of the organism was also reduced under iron-limiting conditions. The combination of elevated temperature and iron-deprivation further reduced phenotypic development and survival of the yeast. The combination of elevated temperature and iron starvation resulted in a decrease in both the growth rate and siderophore production. However, with time, the cells were able to show partial recovery in the growth rate which occurred concomitantly with an increase in siderophore production. In order for siderophores to be utilized, ferri-siderophore receptors must be produced. The receptor was shown to be located in the plasma membrane of the yeast. Scatchard analysis of the binding of ferri-siderophores to plasma membrane receptors showed an increase in receptor affinity and number of binding sites in iron-starved cells when compared to control cells. Autoradiograms of the 58 Fe-siderophore-protein complex following SDS-PAGE separation of candidal proteins revealed the presence of a ferri-siderophore receptor of approximately 10,000 daltons. C. albicans strains which lacked the ability to synthesize phenolate siderophore maintained a phenolate receptor and bound candidal phenolate siderophore better than non-candidal phenolate siderophores

  11. Pure type systems with subtyping

    NARCIS (Netherlands)

    Zwanenburg, J.; Girard, J.-Y.

    1999-01-01

    We extend the framework of Pure Type Systems with subtyping, as found in F = ¿ . This leads to a concise description of many existing systems with subtyping, and also to some new interesting systems. We develop the meta-theory for this framework, including Subject Reduction and Minimal Typing. The

  12. How Low Can You Go: Spatial Frequency Sensitivity in Pure Alexia

    DEFF Research Database (Denmark)

    Starrfelt, Randi; Nielsen, S.; Habekost, T.

    Objective: Pure alexia is a seemingly selective deficit in reading, follow- ing focal lesions to the posterior left hemisphere. The hallmark feature of pure alexia is a word length effect in single word reading, where reaction times may increase with hundreds of milliseconds per additional letter...... in a word. Other language functions, including writing, are intact. It has been suggested that pure alexia is caused by a general deficit in visual processing, one that affects reading disproportionally compared to other visual stimuli. The most concrete hypothesis to date suggests that pure alexia...... is caused by a lack of sensitivity to particular spatial frequencies (e.g., Fiset et al., 2006), and that this results in the characteristic word length effect, as well as effects of letter confusability on reading times. Participants and Methods: We have tested this hypothesis in a patient with pure alexia...

  13. Research on the Applicable Method of Valuation of Pure Electric Used vehicles

    Science.gov (United States)

    Cai, yun; Tan, zhengping; Wang, yidong; Mao, pan

    2018-03-01

    With the rapid growth in the ownership of pure electric vehicles, the research on the valuation of used electric vehicles has become the key to the development of the pure electric used vehicle market. The paper analyzed the application of the three value assessment methods, current market price method, capitalized earning method and replacement cost method, in pure electric used vehicles, and draws a conclusion that the replacement cost method is more suitable for pure electric used car. At the same time, the article also conducted a parametric correction exploration research, aiming at the characteristics of pure electric vehicles and replacement cost of the constituent factors. Through the analysis of the applicability parameters of physical devaluation, functional devaluation and economic devaluation, the revised replacement cost method can be used for the valuation of purely used electric vehicles for private use.

  14. Quasinormal modes in pure de Sitter spacetimes

    International Nuclear Information System (INIS)

    Du Daping; Wang Bin; Su Ruheng

    2004-01-01

    We have studied scalar perturbations as well as fermion perturbations in pure de Sitter spacetimes. For scalar perturbations we have shown that well-defined quasinormal modes in d-dimensions can exist provided that the mass of scalar field m>(d-1/2l). The quasinormal modes of fermion perturbations in three and four dimensional cases have also been investigated. We found that different from other dimensional cases, in the three dimensional pure de Sitter spacetime there is no quasinormal mode for the s-wave. This interesting difference caused by the spacial dimensions is true for both scalar and fermion perturbations

  15. Microbial mobilization of cesium from illite: Role of organic acids and siderophores

    Science.gov (United States)

    Hazotte, Alice; Peron, Olivier; Abdelouas, Abdesselam; Lebeau, Thierry

    2015-04-01

    Understanding the behavior of cesium (Cs) in soils and geological formations is interesting in the context of nuclear accidents and nuclear waste disposals. Indeed, this radionuclide with a 30-years half-life can contaminate crops and more generally the food chain. Cs with properties similar to potassium is known to be strongly accumulated in the clays of upper soil horizons. While excavation of contaminated soil cannot be feasible for the whole contaminated surfaces (huge volumes to be cleaned-up), in situ methods could provide a sustainable and low cost solution. Phytoextraction is one of a few solutions for in situ remediation of soils contaminated by trace elements and it preserves the quality of agricultural soils. However, many improvements are still needed to enhance phytoextraction effectiveness. The combination of bioaugmentation (soil inoculation with exogenous microorganisms) with phytoextraction is likely to increase the bioaccessibility of radionuclides and their accumulation in plants. The role of bacteria on soil-pollutants can be direct (direct metal complexation) and/or indirect (weathering of clays adsorbing Cs). This study aims to provide more specifically a mechanistic understanding of the bacterial mobilization of Cs from soil with the prospect of soil bioremediation. Bacterial metabolites of Pseudomonas fluorescens (ATCC 17400) were supplied to illite spiked with 0.1 and 1 mM of Cs. Purified siderophores including pyoverdine from P. fluorescens, or the whole metabolites from the bacterial culture supernatant were compared to low molecular weight organic acids (LMWOA) (citric and oxalic acids) at 0.04 mM, or synthetic chelants, i.e., acetohydroxamic acid (AHA) and desferrioxamine mesylate (DFOM) ranging from 50 µM up to 250 µM. The release of Cs and the structural alteration of illite (release of Al, Fe and Si) were monitored. When compared to the control, no release of Cs from illite was observed with LMWOA. On the contrary, a slight release

  16. Nigeria Journal of Pure and Applied Physics: Editorial Policies

    African Journals Online (AJOL)

    Focus and Scope. Nigeria Journal of Pure and Applied Physics publishes papers of the highest quality and significance in specific areas of physics, pure and applied, as listed below. The journal content reflects core physics disciplines, but is also open to a broad range of topics whose central theme falls within the bounds ...

  17. Production of tomato puree: an alternative to conservation of locally ...

    African Journals Online (AJOL)

    Mo

    suggest a mean of conservation of the surplus of production by processing tomato into puree. The most produced local ... processing into puree on industrial scale. The main .... functions contributing to the reaction of non-enzymatic browning ...

  18. a Chiral Tagging Strategy for Determining Absolute Configuration and Enantiomeric Excess by Molecular Rotational Spectroscopy

    Science.gov (United States)

    Evangelisti, Luca; Caminati, Walther; Patterson, David; Thomas, Javix; Xu, Yunjie; West, Channing; Pate, Brooks

    2017-06-01

    The introduction of three wave mixing rotational spectroscopy by Patterson, Schnell, and Doyle [1,2] has expanded applications of molecular rotational spectroscopy into the field of chiral analysis. Chiral analysis of a molecule is the quantitative measurement of the relative abundances of all stereoisomers of the molecule and these include both diastereomers (with distinct molecular rotational spectra) and enantiomers (with equivalent molecular rotational spectra). This work adapts a common strategy in chiral analysis of enantiomers to molecular rotational spectroscopy. A "chiral tag" is attached to the molecule of interest by making a weakly bound complex in a pulsed jet expansion. When this tag molecule is enantiopure, it will create diastereomeric complexes with the two enantiomers of the molecule being analyzed and these can be differentiated by molecule rotational spectroscopy. Identifying the structure of this complex, with knowledge of the absolute configuration of the tag, establishes the absolute configuration of the molecule of interest. Furthermore, the diastereomer complex spectra can be used to determine the enantiomeric excess of the sample. The ability to perform chiral analysis will be illustrated by a study of solketal using propylene oxide as the tag. The possibility of using current methods of quantum chemistry to assign a specific structure to the chiral tag complex will be discussed. Finally, chiral tag rotational spectroscopy offers a "gold standard" method for determining the absolute configuration of the molecule through determination of the substitution structure of the complex. When this measurement is possible, rotational spectroscopy can deliver a quantitative three dimensional structure of the molecule with correct stereochemistry as the analysis output. [1] David Patterson, Melanie Schnell, John M. Doyle, Nature 497, 475 (2013). [2] David Patterson, John M. Doyle, Phys. Rev. Lett. 111, 023008 (2013).

  19. ORF Alignment: NC_002927 [GENIUS II[Archive

    Lifescience Database Archive (English)

    Full Text Available NC_002927 gi|33603734 >1kmoA 3 661 60 754 2e-50 ... ref|NP_891294.1| exogenous ferric... siderophore receptor [Bordetella bronchiseptica ... RB50] gb|AAB51774.1| exogenous ferric siderophor...e ... receptor emb|CAE35124.1| exogenous ferric siderophore ... receptor [Bordetella bronchise

  20. International Standardization of Pure Beta Emitters

    International Nuclear Information System (INIS)

    Los Arcos, Jose Maria; Rodriguez, Leonor

    2006-01-01

    The paper describes the traditional methods of standardization of Pure Beta Emitters, their principal characteristics, advantage and drawbacks. It does comparisons between two metrological LSC methods: Triple to double coincidence ratio (TDCR) method and the CIEMAT/NIST method and presents the result obtained with several Key Comparisons serving as practical test of both methods. Both of them represent the siferrit of methods of standardization of pure (and mixed decay) radionuclides. ESIR WG of CCRI(II) is to implement a reference exchange system for the permanent equivalence of β, α and electron capture nuclides, similar to traditional SIR gamma. ESIR project is currently testing a new XAN scintillator and operational tests of the whole system at BIPM are expected by the end of 2006 (test restricted to ESIR NMI members)

  1. Square-root measurement for pure states

    International Nuclear Information System (INIS)

    Huang Siendong

    2005-01-01

    Square-root measurement is a very useful suboptimal measurement in many applications. It was shown that the square-root measurement minimizes the squared error for pure states. In this paper, the least squared error problem is reformulated and a new proof is provided. It is found that the least squared error depends only on the average density operator of the input states. The properties of the least squared error are then discussed, and it is shown that if the input pure states are uniformly distributed, the average probability of error has an upper bound depending on the least squared error, the rank of the average density operator, and the number of the input states. The aforementioned properties help explain why the square-root measurement can be effective in decoding processes

  2. Purely Functional Structured Programming

    OpenAIRE

    Obua, Steven

    2010-01-01

    The idea of functional programming has played a big role in shaping today's landscape of mainstream programming languages. Another concept that dominates the current programming style is Dijkstra's structured programming. Both concepts have been successfully married, for example in the programming language Scala. This paper proposes how the same can be achieved for structured programming and PURELY functional programming via the notion of LINEAR SCOPE. One advantage of this proposal is that m...

  3. DEVELOPMENT OF VEGETABLE PUREES AND DRINKS BY LACTIC ACID FERMENTATION

    Directory of Open Access Journals (Sweden)

    At. Kraevska

    2014-03-01

    Full Text Available The object of this work was to investigate the possibility for development of vegetable purees and drinks by lactic acid fermentation. It was found that by the direct lactic acid fermentation of Lb.plantarum strain 226/1 the vitamin composition of vegetable purees is preserved and the biological value is increased. Drinks, prepared from fermented vegetable purees were remarkable with the pleasant lactic acid taste, the sucrose-acid composition was stable and balanced and they can be used both in the rational and in the dietary nutrition.

  4. Towards chiral distributions of dopants in microporous frameworks: helicoidal supramolecular arrangement of (1R,2S)-ephedrine and transfer of chirality.

    Science.gov (United States)

    Gómez-Hortigüela, Luis; Álvaro-Muñoz, Teresa; Bernardo-Maestro, Beatriz; Pérez-Pariente, Joaquín

    2015-01-07

    A molecular-mechanics computational study is performed in order to analyze the arrangement of (1R,2S)-(-)-ephedrine molecules within the 12-MR channels of the AFI aluminophosphate microporous framework and the influence on the spatial distribution of dopants embedded in the tetrahedral network. Results showed that ephedrine molecules arrange exclusively as dimers by π-π stacking of the aromatic rings within the AFI channels. Interestingly, the asymmetric nature of ephedrine and the presence of H-bond-forming groups (NH2 and OH) involve a preferential orientation where consecutive dimers within the channels are rotated by an angle of +30°; this is driven by the establishment of inter-dimer H-bonds. This preferential orientation leads to the development of a supramolecular enantiomerically-pure helicoidal (chiral) arrangement of ephedrine dimers. In addition, the computational results demonstrate that the particular molecular structure of ephedrine imparts a strong trend to attract negative charges to the vicinity of the NH2(+) positively-charged groups. Hence divalent dopants such as Mg, whose replacement by trivalent Al in the aluminophosphate network involves the generation of a negative charge, will tend to locate close to the NH2(+) molecular groups, suggesting that an imprinting of the organic arrangement to the spatial distribution of dopants would be feasible. Combined with the trend of ephedrine to arrange in a helicoidal fashion, an enantiomerically-pure helicoidal distribution of dopants would be expected, thus inducing a new type of chirality in microporous materials.

  5. Enantiomeric high-performance liquid chromatography resolution and absolute configuration of 6β-benzoyloxy-3α-tropanol.

    Science.gov (United States)

    Muñoz, Marcelo A; González, Natalia; Joseph-Nathan, Pedro

    2016-07-01

    The absolute configuration of the naturally occurring isomers of 6β-benzoyloxy-3α-tropanol (1) has been established by the combined use of chiral high-performance liquid chromatography with electronic circular dichroism detection and optical rotation detection. For this purpose (±)-1, prepared in two steps from racemic 6-hydroxytropinone (4), was subjected to chiral high-performance liquid chromatography with electronic circular dichroism and optical rotation detection allowing the online measurement of both chiroptical properties for each enantiomer, which in turn were compared with the corresponding values obtained from density functional theory calculations. In an independent approach, preparative high-performance liquid chromatography separation using an automatic fraction collector, yielded an enantiopure sample of OR (+)-1 whose vibrational circular dichroism spectrum allowed its absolute configuration assignment when the bands in the 1100-950 cm(-1) region were compared with those of the enantiomers of esters derived from 3α,6β-tropanediol. In addition, an enantiomerically enriched sample of 4, instead of OR (±)-4, was used for the same transformation sequence, whose high-performance liquid chromatography follow-up allowed their spectroscopic correlation. All evidences lead to the OR (+)-(1S,3R,5S,6R) and OR (-)-(1R,3S,5R,6S) absolute configurations, from where it follows that samples of 1 isolated from Knightia strobilina and Erythroxylum zambesiacum have the OR (+)-(1S,3R,5S,6R) absolute configuration, while the sample obtained from E. rotundifolium has the OR (-)-(1R,3S,5R,6S) absolute configuration. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Microstructures and mechanical properties of pure Mg processed by rotary swaging

    International Nuclear Information System (INIS)

    Gan, W.M.; Huang, Y.D.; Wang, R.; Wang, G.F.; Srinivasan, A.; Brokmeier, H.-G.; Schell, N.; Kainer, K.U.; Hort, N.

    2014-01-01

    Highlights: • Grain size of pure Mg can be effectively reduced by rotary swaging processing. • The dominated texture of the swaged pure Mg was a basal fibre. • Twinning and non-basal plane sliding accommodated the swaging process. • Gradient texture distribution was observed through the rod diameter. • There existed a slight shear deformation on the surface of the swaged rod. - Abstract: Microstructures and tensile properties of commercial pure magnesium processed by rotary swaging (RS) technique were investigated. Bulk and gradient textures in the RS processed Mg were characterised by neutron and synchrotron diffractions, respectively. Grains of the pure Mg were gradually refined with increase in the RS passes, which largely contributed to an increase in the tensile yield strength. A dominated basal fibre texture was observed in the RS processed pure Mg. Accommodated twinning deformation was also observed. Both the optical observations and texture analyses through the diameter of the swaged rod showed a gradient evolution in microstructure

  7. Topological M Theory from Pure Spinor Formalism

    CERN Document Server

    Grassi, P A; Grassi, Pietro Antonio; Vanhove, Pierre

    2005-01-01

    We construct multiloop superparticle amplitudes in 11d using the pure spinor formalism. We explain how this construction reduces to the superparticle limit of the multiloop pure spinor superstring amplitudes prescription. We then argue that this construction points to some evidence for the existence of a topological M theory based on a relation between the ghost number of the full-fledged supersymmetric critical models and the dimension of the spacetime for topological models. In particular, we show that the extensions at higher orders of the previous results for the tree and one-loop level expansion for the superparticle in 11 dimensions is related to a topological model in 7 dimensions.

  8. Crystal structure of pure ZrO2 nanopowders

    International Nuclear Information System (INIS)

    Lamas, D.G.; Rosso, A.M.; Anzorena, M. Suarez; Fernandez, A.; Bellino, M.G.; Cabezas, M.D.; Walsoee de Reca, N.E.; Craievich, A.F.

    2006-01-01

    The crystal structure of pure (undoped) zirconia nanopowders synthesized by different wet-chemical routes has been investigated by synchrotron X-ray diffraction. Whereas some previous authors reported the retention of the cubic phase in similar materials, we demonstrate here that pure zirconia nanopowders with average crystallite sizes ranging from 5 to 10 nm exhibit the tetragonal phase. In addition, our results suggest that a tetragonal-to-cubic transition for decreasing crystallite size could eventually occur at a very small critical crystallite size

  9. Scattering of massive open strings in pure spinor

    International Nuclear Information System (INIS)

    Park, I.Y.

    2011-01-01

    In Park (2008) , it was proposed that the D-brane geometry could be produced by open string quantum effects. In an effort to verify the proposal, we consider scattering amplitudes involving massive open superstrings. The main goal of this paper is to set the ground for two-loop 'renormalization' of an oriented open superstring on a D-brane and to strengthen our skill in the pure spinor formulation of a superstring, an effective tool for multi-loop string diagrams. We start by reviewing scattering amplitudes of massless states in the 2D component method of the NSR formulation. A few examples of massive string scattering are worked out. The NSR results are then reproduced in the pure spinor formulation. We compute the amplitudes using the unintegrated form of the massive vertex operator constructed by Berkovits and Chandia (2002) . We point out that it may be possible to discover new Riemann type identities involving Jacobi θ-functions by comparing a NSR computation and the corresponding pure spinor computation.

  10. Graphical calculus for Gaussian pure states

    International Nuclear Information System (INIS)

    Menicucci, Nicolas C.; Flammia, Steven T.; Loock, Peter van

    2011-01-01

    We provide a unified graphical calculus for all Gaussian pure states, including graph transformation rules for all local and semilocal Gaussian unitary operations, as well as local quadrature measurements. We then use this graphical calculus to analyze continuous-variable (CV) cluster states, the essential resource for one-way quantum computing with CV systems. Current graphical approaches to CV cluster states are only valid in the unphysical limit of infinite squeezing, and the associated graph transformation rules only apply when the initial and final states are of this form. Our formalism applies to all Gaussian pure states and subsumes these rules in a natural way. In addition, the term 'CV graph state' currently has several inequivalent definitions in use. Using this formalism we provide a single unifying definition that encompasses all of them. We provide many examples of how the formalism may be used in the context of CV cluster states: defining the 'closest' CV cluster state to a given Gaussian pure state and quantifying the error in the approximation due to finite squeezing; analyzing the optimality of certain methods of generating CV cluster states; drawing connections between this graphical formalism and bosonic Hamiltonians with Gaussian ground states, including those useful for CV one-way quantum computing; and deriving a graphical measure of bipartite entanglement for certain classes of CV cluster states. We mention other possible applications of this formalism and conclude with a brief note on fault tolerance in CV one-way quantum computing.

  11. Homoconjugation vs. Exciton Coupling in Chiral α,β-Unsaturated Bicyclo[3.3.1]nonane Dinitrile and Carboxylic Acids

    Directory of Open Access Journals (Sweden)

    Gintautas Bagdžiūnas

    2014-07-01

    Full Text Available The chiroptical properties of enantiomerically pure bicyclo[3.3.1]nona-2,6-diene-2,6-dicarbonitrile and related acids were studied by circular dichroism spectroscopy and theoretical computations. A consideration of the molecular structure of the synthesized difunctional compounds revealed that chromophores are predisposed to transannular through-space interaction due to a favourable conformation of the bicyclic skeleton and a rather small interchromophoric distance. Evidence for non-exciton-type coupling between the two acrylonitrile and acrylate moieties in 3 and 4, respectively, was obtained by chiroptical spectroscopy and DFT calculations.

  12. Essential oils of Mentha pulegium and Mentha rotundifolia from Uruguay

    Directory of Open Access Journals (Sweden)

    Lorenzo Daniel

    2002-01-01

    Full Text Available Essential oils obtained by hydrodistillation from leaves of Mentha pulegium L. and Mentha rotundifolia (L. Huds. from Uruguay were analysed by GC-FID and GC-MS. Oxygen-containing monoterpenes were the main group of constituents in both oils. Pulegone, isomenthone and menthone were the major components in the oil of M. pulegium, whereas piperitenone oxide and (Z-sabinene hydrate were the major ones in M. rotundifolia. Enantiomerically pure (--menthone, (+-isomenthone, (+-isomenthol, (--menthol and (+-pulegone were detected by multidimensional gas chromatography in the case of M. pulegium oil.

  13. Synthesis of 6-Substituted 2-Pyrones Starting from Renewable Resources: Total Synthesis of Sibirinone, (E)-6-(Pent-1-en-1-yl)-2H-pyran-2-one, and (E)-6-(Hept-1-en-1-yl)-2H-pyran-2-one.

    Science.gov (United States)

    Dobler, Daniel; Reiser, Oliver

    2016-11-04

    An atom-economic reaction sequence to 6-substituted 2-pyrones was developed starting from furfuryl alcohol, a renewable resource made from bran or bagasse, and aldehydes, utilizing a thermal rearrangement of cyclopentadienone epoxides as key step. Derivatives bearing a hydroxyalkyl side chain could be enzymatically resolved, providing access to enantiomerically pure 2-pyrones, or converted to alkenyl-substituted 2-pyrones such as naturally occurring sibirinone, (E)-6-(pent-1-en-1-yl)-2H-pyran-2-one, and (E)-6-(hept-1-en-1-yl)-2H-pyran-2-one.

  14. The Pseudomonas aeruginosa pirA gene encodes a second receptor for ferrienterobactin and synthetic catecholate analogues.

    Science.gov (United States)

    Ghysels, Bart; Ochsner, Urs; Möllman, Ute; Heinisch, Lothar; Vasil, Michael; Cornelis, Pierre; Matthijs, Sandra

    2005-05-15

    Actively secreted iron chelating agents termed siderophores play an important role in the virulence and rhizosphere competence of fluorescent pseudomonads, including Pseudomonas aeruginosa which secretes a high affinity siderophore, pyoverdine, and the low affinity siderophore, pyochelin. Uptake of the iron-siderophore complexes is an active process that requires specific outer membrane located receptors, which are dependent of the inner membrane-associated protein TonB and two other inner membrane proteins, ExbB and ExbC. P. aeruginosa is also capable of using a remarkable variety of heterologous siderophores as sources of iron, apparently by expressing their cognate receptors. Illustrative of this feature are the 32 (of which 28 putative) siderophore receptor genes observed in the P. aeruginosa PAO1 genome. However, except for a few (pyoverdine, pyochelin, enterobactin), the vast majority of P. aeruginosa siderophore receptor genes still remain to be characterized. Ten synthetic iron chelators of catecholate type stimulated growth of a pyoverdine/pyochelin deficient P. aeruginosa PAO1 mutant under condition of severe iron limitation. Null mutants of the 32 putative TonB-dependent siderophore receptor encoding genes engineered in the same genetic background were screened for obvious deficiencies in uptake of the synthetic siderophores, but none showed decreased growth stimulation in the presence of the different siderophores. However, a double knock-out mutant of ferrienterobactin receptor encoding gene pfeA (PA 2688) and pirA (PA0931) failed to be stimulated by 4 of the tested synthetic catecholate siderophores whose chemical structures resemble enterobactin. Ferric-enterobactin also failed to stimulate growth of the double pfeA-pirA mutant although, like its synthetic analogues, it stimulated growth of the corresponding single mutants. Hence, we confirmed that pirA represents a second P. aeruginosa ferric-enterobactin receptor. The example of these two

  15. UV-induced lethal sectoring and pure mutant clones in yeast.

    Science.gov (United States)

    Hannan, M A; Duck, P; Nasim, A

    1976-08-01

    The induction of lethal sectoring and pure mutant clones by ultraviolet light has been studied in a homogeneous G1 population of Saccharomyces cerevisiae grown in a normal growth medium. At the lowest UV dose of 250 ergs, which corresponds to a shoulder in the survival curve, all mutants appeared as pure clones. At higher doses the frequency of mosaic mutants progressively increased. These results indicate a relationship between the highest frequency of complete mutants and the maximum repair activity. In addition, the frequency of lethal sectoring at all doses tested was too low to account for the origin of pure mutant clones.

  16. AKUMULASI TIMBAL (PB DAN STRUKTUR STOMATA DAUN PURING (CODIAEUM VARIEGATUM LAM. BLUME

    Directory of Open Access Journals (Sweden)

    Susi Sulistiana

    2016-12-01

    Full Text Available Tanaman mempunyai kemampuan untuk mengatasi atau mengeliminir pencemaran udara yang terjadi di kota, salah satunya adalah tanaman puring. Stomata adalah salah satu organ tumbuhan yang digunakan untuk berinteraksi dengan lingkungannya. Fungsi utama stomata adalah sebagai tempat pertukaran gas, seperti CO2 yang diperlukan oleh tumbuhan dalam proses fotosintesis. Namun, stomata juga bertindak sebagai salah satu jalur masuknya polutan khususnya polutan yang berasal dari udara. Untuk mempertegas pengaruh akumulasi timbal terhadap daun tanaman puring secara morfologi yang telah dilakukan oleh Sulistiana dan Setijorini tahun 2014, perlu dilakukan penelitian lanjutan dengan melakukan pengamatan anatomi daun terutama struktur stomata daun tanaman puring. Penelitian bertujuan membandingkan struktur stomata antar kultivar puring dan membuktikan adanya hubungan antara akumulasi timbal (Pb dengan struktur stomata daun dari beberapa kultivar puring. Bahan penelitian yang digunakan adalah daun segar dari 13 kultivar tanaman puring yang ditanam di Perumahan Batan Indah, Kecamatan Kademangan, Tangerang Selatan. Pengamatan struktur stomata daun dilakukan dengan cara pembuatan preparat paradermal Parameter yang diamati dalam penelitian meliputi jumlah stomata, jumlah sel epidermis, panjang stomata, lebar stomata, indeks stomata, dan kerapatan stomata. Hasil yang diperoleh adanya korelasi positif antara kadar Pb dan struktur stomata daun kultivar puring melalui parameter-paramater yang diamati terutama jumlah stomata, lebar stomata, indeks stomata, dan kerapatan stomata.

  17. Synthesis, iron(III) complexation properties, molecular dynamics simulations and P. aeruginosa siderophore-like activity of two pyoverdine analogs.

    Science.gov (United States)

    Antonietti, Viviane; Boudesocque, Stéphanie; Dupont, Laurent; Farvacques, Natacha; Cézard, Christine; Da Nascimento, Sophie; Raimbert, Jean-François; Socrier, Larissa; Robin, Thierry-Johann; Morandat, Sandrine; El Kirat, Karim; Mullié, Catherine; Sonnet, Pascal

    2017-09-08

    P. aeruginosa ranks among the top five organisms causing nosocomial infections. Among the many novel strategies for developing new therapeutics against infection, targeting iron uptake mechanism seems promising as P. aeruginosa needs iron for its growth and survival. To scavenge iron, the bacterium produces siderophores possessing a very high affinity towards Fe(III) ions such as pyoverdines. In this work, we decided to study two pyoverdine analogs, aPvd2 and aPvd3, structurally close to the endogen pyoverdine. The pFe constants calculated with the values of formation showed a high affinity of aPvd3 towards Fe(III). Molecular dynamics calculations demonstrated that aPvd3-Fe forms with Fe(III) stable 1:1 complexes in water, whereas aPvd2 does not. Only aPvd3 is able to increase the bacterial growth and represents thus an alternative to pyoverdine for iron acquisition by the bacterium. The aPvd2-3 interaction studies with a lipid membrane indicated that they were unable to interact and to cross the plasma membrane of bacteria by passive diffusion. Consequently, the penetration of aPvd3 is ruled by a transport membrane protein. These results showed that aPvd3 may be used to inhibit pyoverdine uptake or to promote the accumulation and release of antibiotics into the cell following a Trojan horse strategy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  18. Asymmetric aminolytic kinetic resolution of racemic epoxides using recyclable chiral polymeric Co(III)-salen complexes: a protocol for total utilization of racemic epoxide in the synthesis of (R)-Naftopidil and (S)-Propranolol.

    Science.gov (United States)

    Kumar, Manish; Kureshy, Rukhsana I; Shah, Arpan K; Das, Anjan; Khan, Noor-ul H; Abdi, Sayed H R; Bajaj, Hari C

    2013-09-20

    Chiral polymeric Co(III) salen complexes with chiral ((R)/(S)-BINOL, diethyl tartrate) and achiral (piperazine and trigol) linkers with varying stereogenic centers were synthesized for the first time and used as catalysts for aminolytic kinetic resolution (AKR) of a variety of terminal epoxides and glycidyl ethers to get enantio-pure epoxides (ee, 99%) and N-protected β-amino alcohols (ee, 99%) with quantitative yield in 16 h at RT under optimized reaction conditions. This protocol was also used for the synthesis of two enantiomerically pure drug molecules (R)-Naftopidil (α1-blocker) and (S)-Propranolol (β-blocker) as a key step via AKR of single racemic naphthylglycidyl ether with Boc-protected isoproylamine with 100% epoxide utilization at 1 g level. The catalyst 1 was successfully recycled for a number of times.

  19. Transport mechanism of lipid covered saquinavir pure drug nanoparticles in intestinal epithelium

    DEFF Research Database (Denmark)

    Xia, Dengning; He, Yuan; Li, Qiuxia

    2018-01-01

    are transported. To improve cellular uptake and transport of pure nanodrug in cells, here, a lipid covered saquinavir (SQV) pure drug NP (Lipo@nanodrug) was designed by modifying a pure SQV NP (nanodrug) with a phospholipid bilayer. We studied their endocytosis, intracellular trafficking mechanism using Caco-2...... their intracellular processing, helping to improve drug transport across intestinal epithelium. To our knowledge, this is the first presentation of the novel phospholipid bilayer covered SQV pure drug NP design, and a mechanistic study on intracellular trafficking in in vitro cell models has been described......Pure drug nanoparticles (NPs) represent a promising formulation for improved drug solubility and controlled dissolution velocity. However, limited absorption by the intestinal epithelium remains challenge to their clinical application, and little is known about how these NPs within the cells...

  20. Quality by design in the chiral separation strategy for the determination of enantiomeric impurities: development of a capillary electrophoresis method based on dual cyclodextrin systems for the analysis of levosulpiride.

    Science.gov (United States)

    Orlandini, S; Pasquini, B; Del Bubba, M; Pinzauti, S; Furlanetto, S

    2015-02-06

    Quality by design (QbD) concepts, in accordance with International Conference on Harmonisation Pharmaceutical Development guideline Q8(R2), represent an innovative strategy for the development of analytical methods. In this paper QbD principles have been comprehensively applied in the set-up of a capillary electrophoresis method aimed to quantify enantiomeric impurities. The test compound was the chiral drug substance levosulpiride (S-SUL) and the developed method was intended to be used for routine analysis of the pharmaceutical product. The target of analytical QbD approach is to establish a design space (DS) of critical process parameters (CPPs) where the critical quality attributes (CQAs) of the method have been assured to fulfil the desired requirements with a selected probability. QbD can improve the understanding of the enantioseparation process, including both the electrophoretic behavior of enantiomers and their separation, therefore enabling its control. The CQAs were represented by enantioresolution and analysis time. The scouting phase made it possible to select a separation system made by sulfated-β-cyclodextrin and a neutral cyclodextrin, operating in reverse polarity mode. The type of neutral cyclodextrin was included among other CPPs, both instrumental and related to background electrolyte composition, which were evaluated in a screening phase by an asymmetric screening matrix. Response surface methodology was carried out by a Doehlert design and allowed the contour plots to be drawn, highlighting significant interactions between some of the CPPs. DS was defined by applying Monte-Carlo simulations, and corresponded to the following intervals: sulfated-β-cyclodextrin concentration, 9-12 mM; methyl-β-cyclodextrin concentration, 29-38 mM; Britton-Robinson buffer pH, 3.24-3.50; voltage, 12-14 kV. Robustness of the method was examined by a Plackett-Burman matrix and the obtained results, together with system repeatability data, led to define a method

  1. Scattering equations, supergravity integrands, and pure spinors

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, Tim; Casali, Eduardo [Department of Applied Mathematics & Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2015-05-25

    The tree-level S-matrix of type II supergravity can be computed in scattering equation form by correlators in a worldsheet theory analogous to a chiral, infinite tension limit of the pure spinor formalism. By defining a non-minimal version of this theory, we give a prescription for computing correlators on higher genus worldsheets which manifest space-time supersymmetry. These correlators are conjectured to provide the loop integrands of supergravity scattering amplitudes, supported on the scattering equations. We give non-trivial evidence in support of this conjecture at genus one and two with four external states. Throughout, we find a close correspondence with the pure spinor formalism of superstring theory, particularly regarding regulators and zero-mode counting.

  2. Scattering equations, supergravity integrands, and pure spinors

    International Nuclear Information System (INIS)

    Adamo, Tim; Casali, Eduardo

    2015-01-01

    The tree-level S-matrix of type II supergravity can be computed in scattering equation form by correlators in a worldsheet theory analogous to a chiral, infinite tension limit of the pure spinor formalism. By defining a non-minimal version of this theory, we give a prescription for computing correlators on higher genus worldsheets which manifest space-time supersymmetry. These correlators are conjectured to provide the loop integrands of supergravity scattering amplitudes, supported on the scattering equations. We give non-trivial evidence in support of this conjecture at genus one and two with four external states. Throughout, we find a close correspondence with the pure spinor formalism of superstring theory, particularly regarding regulators and zero-mode counting.

  3. Entanglement measure for general pure multipartite quantum states

    International Nuclear Information System (INIS)

    Heydari, Hoshang; Bjoerk, Gunnar

    2004-01-01

    We propose an explicit formula for a measure of entanglement of pure multipartite quantum states. We discuss the mathematical structure of the measure and give a brief explanation of its physical motivation. We apply the measure on some pure, tripartite, qubit states and demonstrate that, in general, the entanglement can depend on what actions are performed on the various subsystems, and specifically if the parties in possession of the subsystems cooperate or not. We also give some simple but illustrative examples of the entanglement of four-qubit and m-qubit states

  4. Pure spinors, free differential algebras, and the supermembrane

    International Nuclear Information System (INIS)

    Fre, Pietro; Grassi, Pietro Antonio

    2007-01-01

    The Lagrangian formalism for the supermembrane in any 11d supergravity background is constructed in the pure spinor framework. Our gauge-fixed action is manifestly BRST, supersymmetric, and 3d Lorentz invariant. The relation between the Free Differential Algebras (FDA) underlying 11d supergravity and the BRST symmetry of the membrane action is exploited. The 'gauge-fixing' has a natural interpretation as the variation of the Chevalley cohomology class needed for the extension of 11d super-Poincare superalgebra to M-theory FDA. We study the solution of the pure spinor constraints in full detail

  5. Type I supergravity effective action from pure spinor formalism

    International Nuclear Information System (INIS)

    Alencar, Geova

    2009-01-01

    Using the pure spinor formalism, we compute the tree-level correlation functions for three strings, one closed and two open, in N = 1 D = 10 superspace. Expanding the superfields in components, the respective terms of the effective action for the type I supergravity are obtained. All terms found agree with the effective action known in the literature. This result gives one more consistency test for the pure spinor formalism.

  6. Endoscopic Endonasal Surgery for Purely Intrathird Ventricle Craniopharyngioma.

    Science.gov (United States)

    Nishioka, Hiroshi; Fukuhara, Noriaki; Yamaguchi-Okada, Mitsuo; Yamada, Shozo

    2016-07-01

    Extended endoscopic transsphenoidal surgery (EETS) is a safe and effective treatment for many suprasellar craniopharyngiomas, including those with third-ventricle involvement. Craniopharyngioma entirely within the third ventricle (purely intraventricular type), however, is generally regarded unsuitable for treatment with EETS. Three patients underwent total removal of a purely intraventricular craniopharyngioma with inferior extension via EETS by direct incision of the bulging, stretched ventricular floor and fine dissection from the ventricular wall. In 2 patients with an anteriorly displaced chiasm, the space between the chiasm and pituitary stalk created a wide corridor to the ventricle, whereas in the third case, in which the infrachiasmal space was somewhat narrowed, partial sacrifice of the pituitary gland was necessary to obtain sufficient space. Despite preservation of the stalk in 2 patients, hypopituitarism and diabetes insipidus developed after surgery. There was no other complication including obesity. Selected patients with purely intraventricular craniopharyngioma can be treated effectively and safely with EETS. Those with inferior extension in the interpeduncular fossa and anterior displacement of the chiasm may be suitable candidates. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Pure state condition for the semi-classical Wigner function

    International Nuclear Information System (INIS)

    Ozorio de Almeida, A.M.

    1982-01-01

    The Wigner function W(p,q) is a symmetrized Fourier transform of the density matrix e(q 1 ,q 2 ), representing quantum-mechanical states or their statistical mixture in phase space. Identification of these two alternatives in the case of density matrices depends on the projection identity e 2 = e; its Wigner correspondence is the pure state condition. This criterion is applied to the Wigner functions botained from standard semiclassical wave functions, determining as pure states those whose classical invariant tori satisfy the generalized Bohr-Sommerfeld conditions. Superpositions of eigenstates are then examined and it is found that the Wigner function corresponding to Gaussian random wave functions are smoothed out in the manner of mixedstate Wigner functions. Attention is also given to the pure-state condition in the case where an angular coordinate is used. (orig.)

  8. Solution thermodynamics of valnemulin hydrogen fumarate in different pure solvents

    International Nuclear Information System (INIS)

    Ouyang, Jinbo; Wang, Jingkang; Huang, Xin; Bao, Ying; Wang, Yongli; Yin, Qiuxiang; Liu, Ailing; Li, Xudong; Hao, Hongxun

    2015-01-01

    Highlights: • The solubility of valnemulin hydrogen fumarate in five pure solvents was experimentally determined. • The solubility data were correlated by Wilson model, NRTL model and UNIQUAC model. • Mixing thermodynamic properties of valnemulin hydrogen fumarate in five pure solvents were calculated. - Abstract: Solubility of valnemulin hydrogen fumarate in five pure solvents was determined within temperature range of (278.15 to 323.15) K by a gravimetric method. The results show that the solubility of valnemulin hydrogen fumarate in tested pure solvents increases with the increasing temperature. The solubility values were correlated by the Wilson model, NRTL model and UNIQUAC model. The UNIQUAC volume parameter, area parameter, and Wilson liquid molar volume parameter of valnemulin hydrogen fumarate were estimated by the group contribution method. It was found that the correlated results are in good agreement with the experimental results. Furthermore, the mixing thermodynamic properties of valnemulin hydrogen fumarate in solutions, including the mixing Gibbs energy, the mixing enthalpy and entropy, were determined by using the Wilson model and the experimental solubility results.

  9. Solubility of salicylic acid in pure alcohols at different temperatures

    International Nuclear Information System (INIS)

    Lim, Junhyuk; Jang, Sunghyun; Cho, Hye Kyoung; Shin, Moon Sam; Kim, Hwayong

    2013-01-01

    Highlights: ► Solubility data of salicylic acid in pure alkanols were measured. ► The experimental data were correlated with NRTL, UNIQUAC and Wilson models. ► The data are fit well with all three models for the six pure alcohols studied. ► Adjustable interaction parameters were suggested. - Abstract: This work focused on the experimental measurements and the numerical calculations of the solubility of salicylic acid in various alcohols. The solubility of salicylic acid in pure alcohols was determined using a (solid + liquid) equilibrium measurement apparatus at temperatures ranging from (278.15 to 318.15) K. Also, the melting temperature and fusion enthalpy of salicylic acid were determined by a differential scanning calorimeter (TA instrument Q100). The experimental results were correlated with the equation for solubility of a solid in a liquid with the nonrandom two liquid (NRTL), universal quasi-chemical (UNIQUAC) and Wilson models for liquid phase activity coefficients to validate the quality of the data taken. Adjustable interaction parameters were also provided. The experimental data fit appropriately with all three models for the pure alcohols studied.

  10. Thermodynamic equilibrium of hydroxyacetic acid in pure and binary solvent systems

    International Nuclear Information System (INIS)

    Huang, Qiaoyin; Xie, Chuang; Li, Yang; Su, Nannan; Lou, Yajing; Hu, Xiaoxue; Wang, Yongli; Bao, Ying; Hou, Baohong

    2017-01-01

    Highlights: • Solubility of hydroxyacetic acid in mono-solvents and binary solvent mixtures was measured. • Modified Apelblat, NRTL and Wilson model were used to correlate the solubility data in pure solvents. • CNIBS/R-K and Jouyban-Acree model were used to correlate the solubility in binary solvent mixtures. • The mixing properties were calculated based on the NRTL model. - Abstract: The solubility of hydroxyacetic acid in five pure organic solvents and two binary solvent mixtures were experimentally measured from 273.15 K to 313.15 K at atmospheric pressure (p = 0.1 MPa) by using a dynamic method. The order of solubility in pure organic solvents is ethanol > isopropanol > n-butanol > acetonitrile > ethyl acetate within the investigated temperature range, except for temperature lower than 278 K where the solubility of HA in ethyl acetate is slightly larger than that in acetonitrile. Furthermore, the solubility data in pure solvents were correlated with the modified Apelblat model, NRTL model, and Wilson model and that in the binary solvents mixtures were fitted to the CNIBS/R-K model and Jouyban-Acree model. Finally, the mixing thermodynamic properties of hydroxyacetic acid in pure and binary solvent systems were calculated and discussed.

  11. Global Journal of Pure and Applied Sciences

    African Journals Online (AJOL)

    Global Journal of Pure and Applied Sciences is a multi-disciplinary specialist journal ... research in Biological Science, Agricultural Sciences, Chemical Sciences, ... Comparative study of the physicochemical and bacteriological qualities of ...

  12. High-power pure blue laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, M.; Ohizumi, Y.; Hoshina, Y.; Tanaka, T.; Yabuki, Y.; Goto, S.; Ikeda, M. [Development Center, Sony Shiroishi Semiconductor Inc., Miyagi (Japan); Funato, K. [Materials Laboratories, Sony Corporation, Kanagawa (Japan); Tomiya, S. [Materials Analysis Laboratory, Sony Corporation, Kanagawa (Japan)

    2007-06-15

    We successfully developed high-power and long-lived pure blue laser diodes (LDs) having an emission wavelength of 440-450 nm. The pure-blue LDs were grown by metalorganic chemical vapor deposition (MOCVD) on GaN substrates. The dislocation density was successfully reduced to {proportional_to}10{sup 6} cm{sup -2} by optimizing the MOCVD growth conditions and the active layer structure. The vertical layer structure was designed to have an absorption loss of 4.9 cm{sup -1} and an internal quantum efficiency of 91%. We also reduced the operating current density to 6 kA/cm{sup 2} under 750 mW continuous-wave operation at 35 C by optimizing the stripe width to 12 {mu}m and the cavity length to 2000 {mu}m. The half lifetimes in constant current mode are estimated to be longer than 10000 h. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Pure spinors, free differential algebras, and the supermembrane

    Energy Technology Data Exchange (ETDEWEB)

    Fre, Pietro [Dipartimento di Fisica Teorica, Universita di Torino, and INFN-Sezione di Torino, Via P. Giuria 1, I-10125 Turin (Italy); Grassi, Pietro Antonio [Centro Studi e Ricerche E. Fermi, Compendio Viminale, I-00184 Rome (Italy) and DISTA, Universita del Piemonte Orientale, and INFN-Sezione di Torino, Via Bellini 25/G, Alessandria 15100 (Italy) and CERN, Theory Unit, CH-1211 Geneva 23 (Switzerland)]. E-mail: pgrassi@insti.physics.sunysb.edu

    2007-02-12

    The Lagrangian formalism for the supermembrane in any 11d supergravity background is constructed in the pure spinor framework. Our gauge-fixed action is manifestly BRST, supersymmetric, and 3d Lorentz invariant. The relation between the Free Differential Algebras (FDA) underlying 11d supergravity and the BRST symmetry of the membrane action is exploited. The 'gauge-fixing' has a natural interpretation as the variation of the Chevalley cohomology class needed for the extension of 11d super-Poincare superalgebra to M-theory FDA. We study the solution of the pure spinor constraints in full detail.

  14. Probing photo-ionization: experiments on positive streamers in pure gases and mixtures

    International Nuclear Information System (INIS)

    Nijdam, S; Van de Wetering, F M J H; Blanc, R; Van Veldhuizen, E M; Ebert, U

    2010-01-01

    Positive streamers are thought to propagate by photo-ionization; the parameters of photo-ionization depend on the nitrogen : oxygen ratio. Therefore we study streamers in nitrogen with 20%, 0.2% and 0.01% oxygen and in pure nitrogen as well as in pure oxygen and argon. Our new experimental set-up guarantees contamination of the pure gases to be well below 1 ppm. Streamers in oxygen are difficult to measure as they emit considerably less light in the sensitivity range of our fast ICCD camera than the other gases. Streamers in pure nitrogen and in all nitrogen-oxygen mixtures look generally similar, but become somewhat thinner and branch more with decreasing oxygen content. In pure nitrogen the streamers can branch so much that they resemble feathers. This feature is even more pronounced in pure argon, with approximately 10 2 hair tips cm -3 in the feathers at 200 mbar; this density can be interpreted as the free electron density creating avalanches towards the streamer stem. It is remarkable that the streamer velocity is essentially the same for similar voltage and pressure in all nitrogen-oxygen mixtures as well as in pure nitrogen, while the oxygen concentration and therefore the photo-ionization lengths vary by more than five orders of magnitude. Streamers in argon have essentially the same velocity as well. The physical similarity of streamers at different pressures is confirmed in all gases; the minimal diameters are smaller than in earlier measurements.

  15. Probing photo-ionization: experiments on positive streamers in pure gases and mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Nijdam, S; Van de Wetering, F M J H; Blanc, R; Van Veldhuizen, E M; Ebert, U, E-mail: s.nijdam@tue.n [Eindhoven University of Technology, Department Applied Physics, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2010-04-14

    Positive streamers are thought to propagate by photo-ionization; the parameters of photo-ionization depend on the nitrogen : oxygen ratio. Therefore we study streamers in nitrogen with 20%, 0.2% and 0.01% oxygen and in pure nitrogen as well as in pure oxygen and argon. Our new experimental set-up guarantees contamination of the pure gases to be well below 1 ppm. Streamers in oxygen are difficult to measure as they emit considerably less light in the sensitivity range of our fast ICCD camera than the other gases. Streamers in pure nitrogen and in all nitrogen-oxygen mixtures look generally similar, but become somewhat thinner and branch more with decreasing oxygen content. In pure nitrogen the streamers can branch so much that they resemble feathers. This feature is even more pronounced in pure argon, with approximately 10{sup 2} hair tips cm{sup -3} in the feathers at 200 mbar; this density can be interpreted as the free electron density creating avalanches towards the streamer stem. It is remarkable that the streamer velocity is essentially the same for similar voltage and pressure in all nitrogen-oxygen mixtures as well as in pure nitrogen, while the oxygen concentration and therefore the photo-ionization lengths vary by more than five orders of magnitude. Streamers in argon have essentially the same velocity as well. The physical similarity of streamers at different pressures is confirmed in all gases; the minimal diameters are smaller than in earlier measurements.

  16. Mathematical Model for Multicomponent Adsorption Equilibria Using Only Pure Component Data

    DEFF Research Database (Denmark)

    Marcussen, Lis

    2000-01-01

    A mathematical model for nonideal adsorption equilibria in multicomponent mixtures is developed. It is applied with good results for pure substances and for prediction of strongly nonideal multicomponent equilibria using only pure component data. The model accounts for adsorbent...

  17. Enantiomeric separation of some demethylated analogues of clofibric acid by capillary zone electrophoresis and nano-liquid chromatography.

    Science.gov (United States)

    Fantacuzzi, Marialuigia; Bettoni, Giancarlo; D'Orazio, Giovanni; Fanali, Salvatore

    2006-03-01

    The enantiomeric separation of some demethylated analogues of clofibric acid, namely 2-(6-chloro-benzothiazol-2-ylsulfanyl)-, 2-(6-methoxy-benzothiazol-2-ylsulfanyl)-, 2-(quinolin-2-yloxy)-, 2-(6-chloro-quinolin-2-yloxy)-, 2-(7-chloro-quinolin-4-yloxy)-propionic acid (compounds A-E, respectively), has been studied by CZE and nano-LC using for the first technique two beta-CD derivatives and vancomycin added to the BGE and vancomycin-modified silica particles for the second one, with the aim to find the optimum experimental conditions for the baseline resolution. The type and the concentration of the chiral selector added to the BGE, the buffer pH, the type of organic modifier and its concentration, the capillary temperature and the applied voltage played a very important role in the enantioresolution of the analysed compounds. The use of 6-monodeoxy-6-monoamino-beta-CD allowed to achieve baseline resolution of four of five clofibric acid derivatives in less than 10 min while heptakis-(2,3,6-tri-O-methyl)-beta-CD partially resolved the same compounds in their enantiomers. Employing vancomycin as the chiral selector in CZE, the counter-current partial filling method was chosen achieving baseline resolution of four analytes. All the studied compounds were enantioresolved employing a capillary column packed with vancomycin stationary phase by nano-LC, and the resolution was strongly influenced by the concentration of the organic modifier and by the pH of the mobile phase. The best results were achieved at pH 4.5 in presence of 60% of methanol (MeOH). However, longer analysis times were observed in the experiments carried out by nano-LC.

  18. Alteration of Diastereoisomeric and Enantiomeric Profiles of Hexabromocyclododecanes (HBCDs) in Adult Chicken Tissues, Eggs, and Hatchling Chickens.

    Science.gov (United States)

    Zheng, Xiaobo; Qiao, Lin; Sun, Runxia; Luo, Xiaojun; Zheng, Jing; Xie, Qilai; Sun, Yuxin; Mai, Bixian

    2017-05-16

    The concentrations and enantiomer fractions (EFs) of α-, β-, and γ-hexabromocyclododecanes (HBCDs) were measured in chicken diet sources (soil and chicken feed), home-raised adult chicken (Gallus domesticus) tissues, eggs during incubation, and hatchling chicken tissues. HBCD concentrations were not detected-0.69 ng/g dry weight (dw) and 25.6-48.4 ng/g dw in chicken feed and soil, respectively. HBCDs were detected in all adult chicken tissues, except the brain, at median levels of 13.1-44.0 ng/g lipid weight (lw). The proportions of α-HBCD in total HBCDs increased from 51% in soil to more than 87% in adult chicken tissues. The accumulation ratios (ARs) of α-HBCD from diet to adult chicken tissues were 4.27 for liver, 11.2 for fat, and 7.64-12.9 for other tissues, respectively. The AR and carry-over rate (COR) of α-HBCD from diet to eggs were 22.4 and 0.226, respectively. The concentrations of α-HBCD in hatchling chicken liver (median: 35.4 ng/g lw) were significantly lower than those in hatchling chicken pectoral muscle (median: 130 ng/g lw). The EFs of α-HBCD decreased from soil to adult chicken tissues and from eggs to hatchling chicken liver. Meanwhile, the EFs of γ-HBCD increased from soil to adult chicken tissues. These results indicate the preferential enrichment of (-)-α-HBCD and (+)-γ-HBCD in chickens. The alteration of diastereoisomeric and enantiomeric patterns of HBCDs might be influenced by the different absorption and elimination rates of the six HBCD enantiomers as well as variations in HBCD metabolism in chickens.

  19. General entanglement-assisted transformation for bipartite pure quantum states

    Science.gov (United States)

    Song, Wei; Huang, Yan; Nai-LeLiu; Chen, Zeng-Bing

    2007-01-01

    We introduce the general catalysts for pure entanglement transformations under local operations and classical communications in such a way that we disregard the profit and loss of entanglement of the catalysts per se. As such, the possibilities of pure entanglement transformations are greatly expanded. We also design an efficient algorithm to detect whether a k × k general catalyst exists for a given entanglement transformation. This algorithm can also be exploited to witness the existence of standard catalysts.

  20. The neuroanatomy of pure apraxia of speech in stroke.

    Science.gov (United States)

    Graff-Radford, Jonathan; Jones, David T; Strand, Edythe A; Rabinstein, Alejandro A; Duffy, Joseph R; Josephs, Keith A

    2014-02-01

    The left insula or Broca's area have been proposed as the neuroanatomical correlate for apraxia of speech (AOS) based on studies of patients with both AOS and aphasia due to stroke. Studies of neurodegenerative AOS suggest the premotor area and the supplementary motor areas as the anatomical correlates. The study objective was to determine the common infarction area in patients with pure AOS due to stroke. Patients with AOS and no or equivocal aphasia due to ischemic stroke were identified through a pre-existing database. Seven subjects were identified. Five had pure AOS, and two had equivocal aphasia. MRI lesion analysis revealed maximal overlap spanning the left premotor and motor cortices. While both neurodegenerative AOS and stroke induced pure AOS involve the premotor cortex, further studies are needed to establish whether stroke-induced AOS and neurodegenerative AOS share a common anatomic substrate. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Pure Gravities via Color-Kinematics Duality for Fundamental Matter

    CERN Document Server

    Johansson, Henrik

    2015-01-01

    We give a prescription for the computation of loop-level scattering amplitudes in pure Einstein gravity, and four-dimensional pure supergravities, using the color-kinematics duality. Amplitudes are constructed using double copies of pure (super-)Yang-Mills parts and additional contributions from double copies of fundamental matter, which are treated as ghosts. The opposite-statistics states cancel the unwanted dilaton and axion in the bosonic theory, as well as the extra matter supermultiplets in supergravities. As a spinoff, we obtain a prescription for obtaining amplitudes in supergravities with arbitrary non-self-interacting matter. As a prerequisite, we extend the color-kinematics duality from the adjoint to the fundamental representation of the gauge group. We explain the numerator relations that the fundamental kinematic Lie algebra should satisfy. We give nontrivial evidence supporting our construction using explicit tree and loop amplitudes, as well as more general arguments.

  2. Visibility in a pure model of golden spiral phyllotaxis.

    Science.gov (United States)

    Herrmann, Burghard

    2018-07-01

    This paper considers the geometry of plants with golden spiral phyllotaxis, i.e. growing leaf by leaf on a spiral with golden divergence angle, via the simplest mathematical model, a cylinder with regular arrangement of points on its surface. As is well-known, Fibonacci numbers appear by means of the order of parastichies. This fact is shown to be a straightforward application of logical consequences to a particular model with respect to pure visibility. This notion is very similar to that of contact parastichies. The 3-D cylindrical model of golden spiral phyllotaxis abstracts from the form of leaves and identifies them with points. Pure visibility is specified in the 2-D representation so that common sense parastichies can be scrutinized. The main Theorem states that the orders of the purely most visible parastichies are Fibonacci numbers. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Perceptions of the Pure Pallet Program

    National Research Council Canada - National Science Library

    Dye, Michael T

    2006-01-01

    .... Recommendations center on educating personnel on the importance of suboptimization avoidance and making the warfighter the most important customer. This research also serves as a formal source of information from which to form conclusions and make judgments on how well Air Force personnel are implementing the pure pallet program.

  4. Heat engine driven by purely quantum information.

    Science.gov (United States)

    Park, Jung Jun; Kim, Kang-Hwan; Sagawa, Takahiro; Kim, Sang Wook

    2013-12-06

    The key question of this Letter is whether work can be extracted from a heat engine by using purely quantum mechanical information. If the answer is yes, what is its mathematical formula? First, by using a bipartite memory we show that the work extractable from a heat engine is bounded not only by the free energy change and the sum of the entropy change of an individual memory but also by the change of quantum mutual information contained inside the memory. We then find that the engine can be driven by purely quantum information, expressed as the so-called quantum discord, forming a part of the quantum mutual information. To confirm it, as a physical example we present the Szilard engine containing a diatomic molecule with a semipermeable wall.

  5. Effect of Bound Entanglement on the Convertibility of Pure States

    International Nuclear Information System (INIS)

    Ishizaka, Satoshi

    2004-01-01

    I show that bound entanglement strongly influences the quantum entanglement processing of pure states: If N distant parties share appropriate bound entangled states with positive partial transpose, all N-partite pure entangled states become inter-convertible by stochastic local operations and classical communication (SLOCC) at the single copy level. This implies that the Schmidt rank of a bipartite pure entangled state can be increased, and that two incomparable tripartite entanglement of the GHZ and W type can be inter-converted by the assistance of bound entanglement. Further, I propose the simplest experimental scheme for the demonstration of the corresponding bound-entanglement-assisted SLOCC. This scheme does not need quantum gates and is feasible for the current experimental technology of linear optics

  6. Purely non-local Hamiltonian formalism, Kohno connections and ∨-systems

    International Nuclear Information System (INIS)

    Arsie, Alessandro; Lorenzoni, Paolo

    2014-01-01

    In this paper, we extend purely non-local Hamiltonian formalism to a class of Riemannian F-manifolds, without assumptions on the semisimplicity of the product ○ or on the flatness of the connection ∇. In the flat case, we show that the recurrence relations for the principal hierarchy can be re-interpreted using a local and purely non-local Hamiltonian operators and in this case they split into two Lenard-Magri chains, one involving the even terms, the other involving the odd terms. Furthermore, we give an elementary proof that the Kohno property and the ∨-system condition are equivalent under suitable assumptions and we show how to associate a purely non-local Hamiltonian structure to any ∨-system, including degenerate ones

  7. Regional cerebral blood flow in pure dysarthria. A 3D-SSP study

    International Nuclear Information System (INIS)

    Okamoto, Kensho; Kamogawa, Kenji; Okuda, Bungo; Kawabata, Keita; Tachibana, Hisao

    2007-01-01

    Pure dysarthria from brain infarction is a rare condition, and its pathophysiology remains unclear. To clarify the underlying mechanism of pure dysarthria, we investigated the lesion sites and regional cerebral blood flow in patients with pure dysarthria. We examined 18 consecutive patients with pure dysarthria (9 men and 9 women; mean age, 71 years) who underwent MRI and cerebral blood flow studies. To visualize the regional cerebral blood flow, we generated Z score images using the three-dimensional stereotactic surface projection (3D-SSP) method with single-photon emission computed tomography (SPECT) and N-isopropyl-p [ 123 I]iodoamphetamine. Data on the brain surface perfusion extracted by the 3D-SSP analysis were compared between the pure dysarthria (PD) patients and 9 control subjects. MRI revealed multiple lacunar infarctions involving the internal capsule and/or corona radiata in 11 patients, left internal capsule-corona radiata infarction in 4 patients, and pontine infarction in 3 patients. SPECT with 3D-SSP demonstrated bilateral frontal cortical hypoperfusion in all patients, particularly in the anterior opercular region. Based on intergroup comparisons, the PD group exhibited pronounced cortical hypoperfusion in the opercular and medial frontal regions, left more than right. In conclusion, pure dysarthria is considered to originate from frontal cortical hypoperfusion, mainly in the anterior opercular and medial frontal regions, which is probably due to interruption of the corticosubcortical neural networks relevant to speech expression and articulation. In addition, it is suggested that left hemispheric lesions may make a greater contribution to the development of pure dysarthria than do right ones. (author)

  8. Preparation of pure phenols from tars

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J

    1929-06-18

    A process is disclosed for preparing pure phenols from brown coal and shale tar, characterized in that the alkaline extract obtained from the tar is oxidized and concurrently the alkaline solution is separated from the existing impurities by heating with steam at high temperature, which finally reaches at least 150/sup 0/C.

  9. Controlled synthesis of phase-pure zeolitic imidazolate framework Co-ZIF-9

    NARCIS (Netherlands)

    Öztürk, Z.; Hofmann, J.P.; Lutz, M.; Mazaj, M.; Zabukovec Logar, N.; Weckhuysen, B.M.

    2015-01-01

    The synthesis of phase-pure Co-ZIF-9, an important cobalt-based zeolitic imidazolate framework, could be achieved by modification of the reported synthesis procedure through pH adjustment of the starting synthesis mixture. The phase-pure Co-ZIF-9 material obtained has been characterized by a

  10. Pure endmember extraction using robust kernel archetypoid analysis for hyperspectral imagery

    Science.gov (United States)

    Sun, Weiwei; Yang, Gang; Wu, Ke; Li, Weiyue; Zhang, Dianfa

    2017-09-01

    A robust kernel archetypoid analysis (RKADA) method is proposed to extract pure endmembers from hyperspectral imagery (HSI). The RKADA assumes that each pixel is a sparse linear mixture of all endmembers and each endmember corresponds to a real pixel in the image scene. First, it improves the re8gular archetypal analysis with a new binary sparse constraint, and the adoption of the kernel function constructs the principal convex hull in an infinite Hilbert space and enlarges the divergences between pairwise pixels. Second, the RKADA transfers the pure endmember extraction problem into an optimization problem by minimizing residual errors with the Huber loss function. The Huber loss function reduces the effects from big noises and outliers in the convergence procedure of RKADA and enhances the robustness of the optimization function. Third, the random kernel sinks for fast kernel matrix approximation and the two-stage algorithm for optimizing initial pure endmembers are utilized to improve its computational efficiency in realistic implementations of RKADA, respectively. The optimization equation of RKADA is solved by using the block coordinate descend scheme and the desired pure endmembers are finally obtained. Six state-of-the-art pure endmember extraction methods are employed to make comparisons with the RKADA on both synthetic and real Cuprite HSI datasets, including three geometrical algorithms vertex component analysis (VCA), alternative volume maximization (AVMAX) and orthogonal subspace projection (OSP), and three matrix factorization algorithms the preconditioning for successive projection algorithm (PreSPA), hierarchical clustering based on rank-two nonnegative matrix factorization (H2NMF) and self-dictionary multiple measurement vector (SDMMV). Experimental results show that the RKADA outperforms all the six methods in terms of spectral angle distance (SAD) and root-mean-square-error (RMSE). Moreover, the RKADA has short computational times in offline

  11. Chiral Drug Analysis in Forensic Chemistry: An Overview

    Directory of Open Access Journals (Sweden)

    Cláudia Ribeiro

    2018-01-01

    Full Text Available Many substances of forensic interest are chiral and available either as racemates or pure enantiomers. Application of chiral analysis in biological samples can be useful for the determination of legal or illicit drugs consumption or interpretation of unexpected toxicological effects. Chiral substances can also be found in environmental samples and revealed to be useful for determination of community drug usage (sewage epidemiology, identification of illicit drug manufacturing locations, illegal discharge of sewage and in environmental risk assessment. Thus, the purpose of this paper is to provide an overview of the application of chiral analysis in biological and environmental samples and their relevance in the forensic field. Most frequently analytical methods used to quantify the enantiomers are liquid and gas chromatography using both indirect, with enantiomerically pure derivatizing reagents, and direct methods recurring to chiral stationary phases.

  12. Multimedia programming with pure data

    CERN Document Server

    Chung, Bryan

    2013-01-01

    A quick and comprehensive tutorial book for media designers to jump-start interactive multimedia production with computer graphics, digital audio, digital video, and interactivity, using the Pure Data graphical programming environment.An introductory book on multimedia programming for media artists/designers who like to work on interactivity in their projects, digital art/design students who like to learn the first multimedia programming technique, and audio-visual performers who like to customize their performance sets

  13. On the question of pure or applied research in developing countries

    International Nuclear Information System (INIS)

    Sioshansi, P.; Lodhi, A.S.; Payrovan, H.

    1977-01-01

    One particular approach to the question of pure versus applied research is discussed in this article. It is pointed out how a modest applied research project has been initiated in this laboratory and how this line of work has subsequently developed to include pure research in related areas

  14. chemf: A purely functional chemistry toolkit.

    Science.gov (United States)

    Höck, Stefan; Riedl, Rainer

    2012-12-20

    Although programming in a type-safe and referentially transparent style offers several advantages over working with mutable data structures and side effects, this style of programming has not seen much use in chemistry-related software. Since functional programming languages were designed with referential transparency in mind, these languages offer a lot of support when writing immutable data structures and side-effects free code. We therefore started implementing our own toolkit based on the above programming paradigms in a modern, versatile programming language. We present our initial results with functional programming in chemistry by first describing an immutable data structure for molecular graphs together with a couple of simple algorithms to calculate basic molecular properties before writing a complete SMILES parser in accordance with the OpenSMILES specification. Along the way we show how to deal with input validation, error handling, bulk operations, and parallelization in a purely functional way. At the end we also analyze and improve our algorithms and data structures in terms of performance and compare it to existing toolkits both object-oriented and purely functional. All code was written in Scala, a modern multi-paradigm programming language with a strong support for functional programming and a highly sophisticated type system. We have successfully made the first important steps towards a purely functional chemistry toolkit. The data structures and algorithms presented in this article perform well while at the same time they can be safely used in parallelized applications, such as computer aided drug design experiments, without further adjustments. This stands in contrast to existing object-oriented toolkits where thread safety of data structures and algorithms is a deliberate design decision that can be hard to implement. Finally, the level of type-safety achieved by Scala highly increased the reliability of our code as well as the productivity of

  15. Eco-Cities: Possible or Purely Utopian?

    Science.gov (United States)

    2009-12-01

    00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Eco-Cities: Possible or Purely Utopian? 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...2005, Disney modified their building plans for Hong Kong Disneyland by shifting the angle of the front gate by twelve degrees in order to abide by

  16. Critical current of pure SNS junctions

    International Nuclear Information System (INIS)

    Golub, A.A.; Bezzub, O.P.

    1982-01-01

    Boundary conditions at the superconductor-normal metal interface are determined, taking into account the differences in the effective masses and the density of states of the metals constituting the transition and assumed to be pure. The potential barrier of the interface is chosen to be zero. The critical current of the junction is calculated [ru

  17. Critical opalescence in the pure Coulomb system

    Energy Technology Data Exchange (ETDEWEB)

    Bobrov, V.B., E-mail: vic5907@mail.r [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaia St., 13, Bd. 2. Moscow 125412 (Russian Federation); Trigger, S.A., E-mail: satron@mail.r [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaia St., 13, Bd. 2. Moscow 125412 (Russian Federation); Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany)

    2011-04-18

    Highlights: The review of the critical opalescence problem is presented. Light scattering in a two-component electron-nuclear system is studied. The exact relations between the structure factors and compressibility are found. The obtained relations are valid for strong interaction for the Coulomb systems. The experimental verification of these relations is possible for various elements. - Abstract: Based on the dielectric formalism and quantum field theory methods, the phenomenon of critical opalescence is explained for light scattering in pure matter as a two-component electron-nuclear system with Coulomb interaction. A similar phenomenon is shown to occur in the case of neutron scattering in pure substances as well. The obtained results are valid for quantum case and arbitrary strong Coulomb interaction. Thus, the relations between structure factors derived for the electron-nuclear system are the exact result of the quantum statistical mechanics.

  18. (Invited) Pure Dopant Deposition of B and Ga for Ultrashallow Junctions in Si-based Devices

    NARCIS (Netherlands)

    Nanver, L.K.; Sammak, A.; Mohammadi, V.; Mok, K.R.C.; Qi, L.; Sakic, A.; Golshani, N.; Darakhshandeh, J.; Scholtes, T.M.L.; De Boer, W.B.

    2012-01-01

    Envisioning wide future relevance, work is reviewed here on the pure dopant deposition of boron (PureB), gallium (PureGa) and the combination of the two (PureGaB), as used in the fabrication of nanometer shallow p+n Si and/or Ge diodes. Focus is placed on the special properties that have put these

  19. Transgastric pure-NOTES peritoneoscopy and endoscopic ultrasonography for staging of gastrointestinal cancers

    DEFF Research Database (Denmark)

    Donatsky, Anders Meller; Vilmann, Peter; Meisner, Søren

    2012-01-01

    BACKGROUND: Human natural orifice transluminal endoscopic surgery (NOTES) has mainly been based on simultaneous laparoscopic assistance (hybrid NOTES), forgoing the theoretical benefits of the NOTES technique. This is due to a lack of NOTES-specific instruments and endoscopes, making pure-NOTES...... procedures difficult and time consuming. An area where pure NOTES could be adopted at its present stage of development is minimally invasive staging of gastrointestinal (GI) cancer. The aim of this study is to evaluate the feasibility of combining transgastric (TG) pure-NOTES peritoneoscopy...... and intraperitoneal endoscopic ultrasonography (ip-EUS) with intraluminal EUS (il-EUS) for peritoneal evaluation. METHODS: This was a feasibility and survival study where il-EUS followed by ip-EUS and peritoneoscopy was performed in 10 pigs subjected to TG pure NOTES. A score was given with regard to achieved...

  20. Enantiospecific Synthesis of Trisubstituted Butyrolactone Natural Products and Their Analogs.

    Science.gov (United States)

    Sibi, Mukund P.; Lu, Jianliang; Talbacka, Chelsy L.

    1996-11-01

    A general methodology for the synthesis of highly substituted butyrolactones in enantiomerically pure form has been developed. The application of this process in a highly efficient synthesis of lactone natural products blastmycinone (1), NFX-2 (2), antimycinone (3), and NFX-4 (4) and two lipid metabolites (5, 6) are described. Additionally, the total synthesis of 5-epi-blastmycinone (22), 5-epi-NFX-2 (21b), 5-epi-NFX-4 (21c), and lipid metabolite analogs (19, 20) are also described. The overall yields for the target molecules are the highest reported so far in the literature.

  1. Facile syntheses of isotope-labeled chiral octahydroindole-2-carboxylic acid and its N-methyl analog

    International Nuclear Information System (INIS)

    Yinsheng Zhang

    2012-01-01

    We have synthesized deuterium and carbon-14 labeled enantiomerically pure octahydroindole-2-carboxylic acid (PD0140417), N-methyl octahydroindole-2-carboxylic acid (PD0348183) and their racemic analogs (PD0108405 and PD0338055). [ring-U- 14 C]PD0140417 was prepared from [ring-U- 14 C]benzoic acid in a seven-step synthesis in 6.2% overall radiochemical yield. [ 14 C]PD0348183 was prepared from [ 14 C]BaCO 3 in a five-step synthesis in 16% radiochemical yield. Additionally, [D]PD0108405 and [D]PD0338055 were synthesized by direct platinum-catalyzed hydrogenation with deuterium gas. (author)

  2. The b ghost of the pure spinor formalism is nilpotent

    Energy Technology Data Exchange (ETDEWEB)

    Chandia, Osvaldo, E-mail: osvaldo.chandia@uai.c [Departamento de Ciencias, Facultad de Artes Liberales and Facultad de Ingenieria y Ciencias, Universidad Adolfo Ibanez, Santiago (Chile)

    2011-01-10

    The ghost for world-sheet reparametrization invariance is not a fundamental field in the pure spinor formalism. It is written as a combination of pure spinor variables which have conformal dimension two and such that it commutes with the BRST operator to give the world-sheet stress tensor. We show that the ghost variable defined in this way is nilpotent since the OPE of b with itself does not have singularities.

  3. Model answers in pure mathematics for a-level students

    CERN Document Server

    Pratt, GA; Schofield, C W

    1967-01-01

    Model Answers in Pure Mathematics for A-Level Students provides a set of solutions that indicate what is required and expected in an Advanced Level examination in Pure Mathematics. This book serves as a guide to the length of answer required, layout of the solution, and methods of selecting the best approach to any particular type of math problem. This compilation intends to supplement, not replace, the normal textbook and provides a varied selection of questions for practice in addition to the worked solutions. The subjects covered in this text include algebra, trigonometry, coordinate geomet

  4. Bayero Journal of Pure and Applied Sciences

    African Journals Online (AJOL)

    The Journal's scope is wide in that it reported findings in the areas of pure and ... Physics, Medical Sciences and Zoology form part of the contents of the Journal. Scientists in the academia, research institutes and industries are therefore ...

  5. Purely Magnetic Silent Universes do not Exist

    Science.gov (United States)

    Vu, K. T.; Carminati, J.

    2008-09-01

    We present a new Maple package called STeM (Symbolic Tetrad Manipulation). Using STeM, we outline, using a formalism which is a hybrid of the NP and Orthonormal ones, the proof of the nonexistence of purely magnetic silent universes.

  6. Pure General Gauge Mediation for Early LHC Searches

    CERN Document Server

    Abel, Steven; Jaeckel, Joerg; Khoze, Valentin V

    2010-01-01

    We present benchmark points for Pure General Gauge Mediation (GGM) models specifically optimised for early LHC searches. The pure GGM set-up is as defined in our previous paper arXiv:0910.2674: namely we adopt the minimal set-up in which B_mu is generated only through gauge interactions, and as a result tan beta is a prediction rather than an input. The only input parameters are messenger masses together with two independent scales which generate gaugino and scalar masses. The parameter space favoured by current experimental data includes an interesting region with light gluinos (m_g 2 cross-sections. This data in SLHA format can be found at http://www.ippp.dur.ac.uk/~SUSY

  7. Lattice modes of the chirally pure and racemic phases of tyrosine crystals

    Energy Technology Data Exchange (ETDEWEB)

    Belyanchikov, M. A. [Moscow Institute of Physics and Technology (Russian Federation); Gorelik, V. S., E-mail: gorelik@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Gorshunov, B. P. [Moscow Institute of Physics and Technology (Russian Federation); Pyatyshev, A. Yu., E-mail: jb-valensia@mail.ru [Bauman Moscow State Technical University (Russian Federation)

    2017-01-15

    High-Q librational modes have been found to be present in the infrared absorption and Raman spectra of chirally pure L-tyrosine. Such modes can serve as terahertz radiation detectors and generators in chirally pure biostructures.

  8. Simultaneous enantioselective separation of polychlorinated biphenyls and their methyl sulfone metabolites by heart-cut MDGC: determination of enantiomeric fractions in fish oils and cow liver samples.

    Science.gov (United States)

    Pérez-Fernández, Virginia; Castro-Puyana, María; González, María José; Marina, María Luisa; García, María Ángeles; Gómara, Belén

    2012-07-01

    The potential of three capillary columns based on β-cyclodextrin (i.e., Chirasil-Dex, BGB-172, and BGB-176SE) has been studied for the simultaneous enantiomeric separation of polychlorinated biphenyls (PCBs) and methylsulfonyl metabolites of PCBs (MeSO(2)-PCBs) employing a heart-cut multidimensional gas chromatographic system (heart-cut MDGC). Among the columns studied, the BGB-176SE capillary column provided the best results, allowing the simultaneous enantioselective resolution of six MeSO(2)-PCBs and six chiral PCBs; the Chirasil-Dex column did not resolve any of the studied MeSO(2)-PCBs; and a poor resolution was obtained for three MeSO(2)-PCBs when the BGB-172 column was employed. The developed method was successfully applied to two fish oil and one cow liver samples commercially available, which showed different enantioselective pattern. PCBs 91 and 176 presented a clear enrichment of the second eluted atropisomer in codfish oil, whereas in fish oil sample, slight enrichment of the first eluted atropisomer of CB45 and the second eluted atropisomer of CB136 were observed. © 2012 Wiley Periodicals, Inc.

  9. Pure sociology and social geometry as an example of formal sociological theory

    Directory of Open Access Journals (Sweden)

    Škorić Marko

    2012-01-01

    Full Text Available This paper analyzes pure sociology and social geometry of Donald Black as an example of formal sociological theory. Starting with the importance of formal and analytical theory in sociology, we present the bold theoretical strategy and/or the paradigm of the sociology of behavior of social life. The examples of pure sociology and social geometry concerning law, violence and homosexuality are presented as well. A review and critique of pure sociology as a scientific formal theory is offered in the end.

  10. Pure drug nanoparticles in tablets: what are the dissolution limitations?

    International Nuclear Information System (INIS)

    Heng, Desmond; Ogawa, Keiko; Cutler, David J.; Chan, Hak-Kim; Raper, Judy A.; Ye Lin; Yun, Jimmy

    2010-01-01

    There has been increasing interests for drug companies to incorporate drug nanoparticles into their existing formulations. However, technical knowledge in this area is still in its infancy and more study needs to be done to stimulate growth in this fledging field. There is a need to scrutinize the performance of pure drug nanoparticles in tablets, particularly relating formulation variables to their dissolution performance. Application of the pure form, synthesized without the use of surfactants or stabilizers, is often preferred to maximize drug loading and also to minimize toxicity. Cefuroxime axetil, a poorly water-soluble cephalosporin antibiotic, was used as the model drug in the formulation development. Drug release rate, tablet disintegration time, tensile strength and energy of failure were predominantly influenced by the amount of super-disintegrant, amount of surfactant, compression force and diluent species, respectively. The compression rate had minimal impact on the responses. The main hurdle confronting the effective use of pure drug nanoparticles in tablets is the difficulty in controlling aggregation in solution, which could potentially be aggravated by the tabletting process. Through the use of elevated levels of surfactants (8 w/w% sodium dodecyl sulphate), drug release from the nanoparticle preparation was enhanced from 58.0 ± 2.7% to 72.3 ± 0.7% in 10 min. Hence, it is recommended that physical formulations for pure drug nanoparticles be focused on the particle de-aggregation step in solution, if much higher rates are to be desired. In conclusion, even though pure drug nanoparticles could be easily synthesized, limitations from aggregation may need to be overcome, before successful application in tablets can be fully realized.

  11. Pure drug nanoparticles in tablets: what are the dissolution limitations?

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Desmond [Institute of Chemical and Engineering Sciences (Singapore); Ogawa, Keiko [Nitto Denko Co. Ltd., Medical Division (Japan); Cutler, David J.; Chan, Hak-Kim, E-mail: kimc@pharm.usyd.edu.a [University of Sydney, Advanced Drug Delivery Group, Faculty of Pharmacy, A15 (Australia); Raper, Judy A. [University of Wollongong, Vice Chancellor' s Unit (Australia); Ye Lin [University of Sydney, School of Aerospace, Mechanical and Mechatronic Engineering (Australia); Yun, Jimmy [Nanomaterials Technology Pty. Ltd. (Singapore)

    2010-06-15

    There has been increasing interests for drug companies to incorporate drug nanoparticles into their existing formulations. However, technical knowledge in this area is still in its infancy and more study needs to be done to stimulate growth in this fledging field. There is a need to scrutinize the performance of pure drug nanoparticles in tablets, particularly relating formulation variables to their dissolution performance. Application of the pure form, synthesized without the use of surfactants or stabilizers, is often preferred to maximize drug loading and also to minimize toxicity. Cefuroxime axetil, a poorly water-soluble cephalosporin antibiotic, was used as the model drug in the formulation development. Drug release rate, tablet disintegration time, tensile strength and energy of failure were predominantly influenced by the amount of super-disintegrant, amount of surfactant, compression force and diluent species, respectively. The compression rate had minimal impact on the responses. The main hurdle confronting the effective use of pure drug nanoparticles in tablets is the difficulty in controlling aggregation in solution, which could potentially be aggravated by the tabletting process. Through the use of elevated levels of surfactants (8 w/w% sodium dodecyl sulphate), drug release from the nanoparticle preparation was enhanced from 58.0 {+-} 2.7% to 72.3 {+-} 0.7% in 10 min. Hence, it is recommended that physical formulations for pure drug nanoparticles be focused on the particle de-aggregation step in solution, if much higher rates are to be desired. In conclusion, even though pure drug nanoparticles could be easily synthesized, limitations from aggregation may need to be overcome, before successful application in tablets can be fully realized.

  12. Pure drug nanoparticles in tablets: what are the dissolution limitations?

    Science.gov (United States)

    Heng, Desmond; Ogawa, Keiko; Cutler, David J.; Chan, Hak-Kim; Raper, Judy A.; Ye, Lin; Yun, Jimmy

    2010-06-01

    There has been increasing interests for drug companies to incorporate drug nanoparticles into their existing formulations. However, technical knowledge in this area is still in its infancy and more study needs to be done to stimulate growth in this fledging field. There is a need to scrutinize the performance of pure drug nanoparticles in tablets, particularly relating formulation variables to their dissolution performance. Application of the pure form, synthesized without the use of surfactants or stabilizers, is often preferred to maximize drug loading and also to minimize toxicity. Cefuroxime axetil, a poorly water-soluble cephalosporin antibiotic, was used as the model drug in the formulation development. Drug release rate, tablet disintegration time, tensile strength and energy of failure were predominantly influenced by the amount of super-disintegrant, amount of surfactant, compression force and diluent species, respectively. The compression rate had minimal impact on the responses. The main hurdle confronting the effective use of pure drug nanoparticles in tablets is the difficulty in controlling aggregation in solution, which could potentially be aggravated by the tabletting process. Through the use of elevated levels of surfactants (8 w/w% sodium dodecyl sulphate), drug release from the nanoparticle preparation was enhanced from 58.0 ± 2.7% to 72.3 ± 0.7% in 10 min. Hence, it is recommended that physical formulations for pure drug nanoparticles be focused on the particle de-aggregation step in solution, if much higher rates are to be desired. In conclusion, even though pure drug nanoparticles could be easily synthesized, limitations from aggregation may need to be overcome, before successful application in tablets can be fully realized.

  13. Tribological Properties of Surface-Textured and Plasma-Nitrided Pure Titanium Under Oil Lubrication Condition

    Science.gov (United States)

    Zhang, Baosen; Dong, Qiangsheng; Ba, Zhixin; Wang, Zhangzhong; Shi, Hancheng; Xue, Yanting

    2018-01-01

    Plasma nitriding was conducted as post-treatment for surface texture on pure titanium to obtain a continuous nitriding layer. Supersonic fine particles bombarding (SFPB) was carried out to prepare surface texture. The surface morphologies and chemical composition were analyzed using scanning electron microscope and energy disperse spectroscopy. The microstructures of modified layers were characterized by transmission electron microscope. The tribological properties of surface-textured and duplex-treated pure titanium under oil lubrication condition were systematically investigated in the ball-on-plate reciprocating mode. The effects of applied load and sliding velocity on the tribological behavior were analyzed. The results show that after duplex treatments, the grains size in modified layer becomes slightly larger, and hardness is obviously improved. Wear resistance of duplex-treated pure titanium is significantly improved referenced to untreated and surface-textured pure titanium, which is 3.22 times as much as untreated pure titanium and 2.15 times of that for surface-textured pure titanium, respectively.

  14. Evaluation of drug incorporation into hair segments and nails by enantiomeric analysis following controlled single MDMA intakes.

    Science.gov (United States)

    Madry, Milena M; Steuer, Andrea E; Hysek, Cédric M; Liechti, Matthias E; Baumgartner, Markus R; Kraemer, Thomas

    2016-01-01

    Incorporation rates of the enantiomers of 3,4-methylenedioxymethamphetamine (MDMA) and its metabolite 3,4-methylenedioxyamphetamine (MDA) into hair and nails were investigated after controlled administration. Fifteen subjects without MDMA use received two doses of 125 mg of MDMA. Hair, nail scrapings, and nail clippings were collected 9-77 days after the last administration (median 20 days). Hair samples were analyzed in segments of 1- to 2-cm length. After chiral derivatization with N-(2,4-dinitro-5-fluorophenyl)-L-valinamide, MDMA and MDA diastereomers were analyzed by liquid chromatography-tandem mass spectrometry. Highest concentrations in hair segments corresponded to the time of MDMA intake. They ranged from 101 to 3200 pg/mg and 71 to 860 pg/mg for R- and S-MDMA, and from 3.2 to 116 pg/mg and 4.4 to 108 pg/mg for R- and S-MDA, respectively. MDMA and MDA concentrations in nail scrapings and clippings were significantly lower than in hair samples. There was no significant difference between enantiomeric ratios of R/S-MDMA and R/S-MDA in hair and nail samples (medians 2.2-2.4 for MDMA and 0.85-0.95 for MDA). Metabolite ratios of MDA to MDMA were in the same range in hair and nail samples (medians 0.044-0.055). Our study demonstrates that administration of two representative doses of MDMA was detected in the hair segments corresponding to the time of intake based on average hair growth rates. MDMA was detected in all nail samples regardless of time passed after intake. Comparable R/S ratios in hair and nail samples may indicate that incorporation mechanisms into both matrices are comparable.

  15. Enantiomeric quantification of (S)-(+)-methamphetamine in urine by an immunoaffinity column and liquid chromatography-electrospray-mass spectrometry

    International Nuclear Information System (INIS)

    Lua, Ahai C.; Sutono, Yenny; Chou, T.-Y.

    2006-01-01

    A method using an immunoaffinity column (IAC) and liquid chromatography-electrospray ionization mass spectrometry (LC/MS) for on-line detecting the presence of MA in the effluent was developed for the quantitative and enantiomeric determination of (S)-(+)-methamphetamine (D-MA) in urine. The IAC was made in our laboratory and utilized in the LC/MS to simultaneously extract and separate enantiomers of MA from urine samples. An aqueous ammonium acetate buffer was used as the mobile phase. Urine samples were spiked with racemic deuterated methamphetamine (MA-d 14 ) as internal standard (IS), filtered through a membrane, and injected into the LC/MS without any further pre-treatment. Protonated molecular ion of MA and MA-d 14 (m/z 150 and 164) were isolated and further fragmented, the respective product ions, m/z 119 and 130, were collected for quantitative determination. This is an improvement of our previous method (A.C. Lua, Tsong-Yung Chou, J. Chromatogr. A 967 (2002) 191). In the previous method, MA was separated with HPLC, the efflux was fractionated and each fraction was either determined with an immunoassay or GC/MS. Monitoring of MA in the efflux is tedious and time consuming. Urine samples spiked with different concentrations of D-MA were measured by this method. A linear relationship exists in the 150-1050 ng/mL range, and the detection limit (defined as signal-to-noise ratio 3) of D-MA was determined to be 18 ng/mL. The linearity of the method for D-MA can be described by the equation (Y = 1.415 x 10 -3 X + 0.034, correlation coefficient: r 2 = 0.999). Within run, accuracy and precision (n = 6, relative error: -7.2 to +4.0% and relative standard deviation: 3.8-9.3%) of the method are fairly good

  16. Enantiomeric quantification of (S)-(+)-methamphetamine in urine by an immunoaffinity column and liquid chromatography-electrospray-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lua, Ahai C. [Department of Laboratory Medicine and Biotechnology and Graduate Institute of Medical Biotechnology, Tzu Chi University, 701, Chung Yang Road Section 3, Hualien, 970, Taiwan (China); Sutono, Yenny [Department of Laboratory Medicine and Biotechnology and Graduate Institute of Medical Biotechnology, Tzu Chi University, 701, Chung Yang Road Section 3, Hualien, 970, Taiwan (China); Chou, T.-Y. [Department of Laboratory Medicine and Biotechnology and Graduate Institute of Medical Biotechnology, Tzu Chi University, 701, Chung Yang Road Section 3, Hualien, 970, Taiwan (China)]. E-mail: cty@mail.tcu.edu.tw

    2006-08-18

    A method using an immunoaffinity column (IAC) and liquid chromatography-electrospray ionization mass spectrometry (LC/MS) for on-line detecting the presence of MA in the effluent was developed for the quantitative and enantiomeric determination of (S)-(+)-methamphetamine (D-MA) in urine. The IAC was made in our laboratory and utilized in the LC/MS to simultaneously extract and separate enantiomers of MA from urine samples. An aqueous ammonium acetate buffer was used as the mobile phase. Urine samples were spiked with racemic deuterated methamphetamine (MA-d{sub 14}) as internal standard (IS), filtered through a membrane, and injected into the LC/MS without any further pre-treatment. Protonated molecular ion of MA and MA-d{sub 14} (m/z 150 and 164) were isolated and further fragmented, the respective product ions, m/z 119 and 130, were collected for quantitative determination. This is an improvement of our previous method (A.C. Lua, Tsong-Yung Chou, J. Chromatogr. A 967 (2002) 191). In the previous method, MA was separated with HPLC, the efflux was fractionated and each fraction was either determined with an immunoassay or GC/MS. Monitoring of MA in the efflux is tedious and time consuming. Urine samples spiked with different concentrations of D-MA were measured by this method. A linear relationship exists in the 150-1050 ng/mL range, and the detection limit (defined as signal-to-noise ratio 3) of D-MA was determined to be 18 ng/mL. The linearity of the method for D-MA can be described by the equation (Y = 1.415 x 10{sup -3} X + 0.034, correlation coefficient: r {sup 2} = 0.999). Within run, accuracy and precision (n = 6, relative error: -7.2 to +4.0% and relative standard deviation: 3.8-9.3%) of the method are fairly good.

  17. In vitro degradation of pure Mg in response to glucose

    Science.gov (United States)

    Zeng, Rong-Chang; Li, Xiao-Ting; Li, Shuo-Qi; Zhang, Fen; Han, En-Hou

    2015-08-01

    Magnesium and its alloys are promising biodegradable biomaterials but are still challenging to be used in person with high levels of blood glucose or diabetes. To date, the influence of glucose on magnesium degradation has not yet been elucidated, this issue requires more attention. Herein, we present pure Mg exhibiting different corrosion responses to saline and Hank’s solutions with different glucose contents, and the degradation mechanism of pure Mg in the saline solution with glucose in comparison with mannitol as a control. On one hand, the corrosion rate of pure Mg increases with the glucose concentration in saline solutions. Glucose rapidly transforms into gluconic acid, which attacks the oxides of the metal and decreases the pH of the solution; it also promotes the absorption of chloride ions on the Mg surface and consequently accelerates corrosion. On the other hand, better corrosion resistance is obtained with increasing glucose content in Hank’s solution due to the fact that glucose coordinates Ca2+ ions in Hank’s solution and thus improves the formation of Ca-P compounds on the pure Mg surface. This finding will open up new avenues for research on the biodegradation of bio-Mg materials in general, which could yield many new and interesting results.

  18. Engineering an enantioselective amine oxidase for the synthesis of pharmaceutical building blocks and alkaloid natural products.

    Science.gov (United States)

    Ghislieri, Diego; Green, Anthony P; Pontini, Marta; Willies, Simon C; Rowles, Ian; Frank, Annika; Grogan, Gideon; Turner, Nicholas J

    2013-07-24

    The development of cost-effective and sustainable catalytic methods for the production of enantiomerically pure chiral amines is a key challenge facing the pharmaceutical and fine chemical industries. This challenge is highlighted by the estimate that 40-45% of drug candidates contain a chiral amine, fueling a demand for broadly applicable synthetic methods that deliver target structures in high yield and enantiomeric excess. Herein we describe the development and application of a "toolbox" of monoamine oxidase variants from Aspergillus niger (MAO-N) which display remarkable substrate scope and tolerance for sterically demanding motifs, including a new variant, which exhibits high activity and enantioselectivity toward substrates containing the aminodiphenylmethane (benzhydrylamine) template. By combining rational structure-guided engineering with high-throughput screening, it has been possible to expand the substrate scope of MAO-N to accommodate amine substrates containing bulky aryl substituents. These engineered MAO-N biocatalysts have been applied in deracemization reactions for the efficient asymmetric synthesis of the generic active pharmaceutical ingredients Solifenacin and Levocetirizine as well as the natural products (R)-coniine, (R)-eleagnine, and (R)-leptaflorine. We also report a novel MAO-N mediated asymmetric oxidative Pictet-Spengler approach to the synthesis of (R)-harmicine.

  19. Synthesis of 14C-labelled α-methyl tyrosine

    International Nuclear Information System (INIS)

    Rajagopal, S.; Venkatachalam, T.K.; Conway, T.; Diksic, M.

    1992-01-01

    A new route for the preparation of radioactively labelled α-methyl L-tyrosine is described. The labelling at the α position has been successfully achieved with 14 C-, 11 C- (very preliminary, unpublished), and 3 H-labelled methyl iodide. A detailed report on 14 C-labelling at the α position and the hydrolysis of 4-methoxy α-methyl phenylalanine is presented. The alkylation proceeds via the methylation of the carbanion of N-benzylidene 4-methoxy phenylalanine methyl ester 2. Hydrolysis of 4-O methyl tyrosine to tyrosine by HBr and HI were analysed and used in the optimization of the hydrolysis conditions of 4. Enantiomeric purity of the isolated L-isomer has been found to be 99% as judged by HPLC. Pseudo first-order rate constant for the hydrolysis of 14 C-labelled α-methyl 4-methoxy phenyl alanine methyl ester was determined. Preliminary findings of the 3 H- and 11 C-radiolabelled α-methyl tyrosine (methyl labelled) are also mentioned. For the first time it was shown that α-methyl D,L-tyrosine can be separated into enantiomerically pure α-methyl D- and L-tyrosine using a CHIRALPAK WH column. (author)

  20. Excitation of coherent propagating spin waves by pure spin currents.

    Science.gov (United States)

    Demidov, Vladislav E; Urazhdin, Sergei; Liu, Ronghua; Divinskiy, Boris; Telegin, Andrey; Demokritov, Sergej O

    2016-01-28

    Utilization of pure spin currents not accompanied by the flow of electrical charge provides unprecedented opportunities for the emerging technologies based on the electron's spin degree of freedom, such as spintronics and magnonics. It was recently shown that pure spin currents can be used to excite coherent magnetization dynamics in magnetic nanostructures. However, because of the intrinsic nonlinear self-localization effects, magnetic auto-oscillations in the demonstrated devices were spatially confined, preventing their applications as sources of propagating spin waves in magnonic circuits using these waves as signal carriers. Here, we experimentally demonstrate efficient excitation and directional propagation of coherent spin waves generated by pure spin current. We show that this can be achieved by using the nonlocal spin injection mechanism, which enables flexible design of magnetic nanosystems and allows one to efficiently control their dynamic characteristics.

  1. Too Little, Too Late: Reduced Visual Span and Speed Characterize Pure Alexia

    Science.gov (United States)

    Habekost, Thomas; Leff, Alexander P.

    2009-01-01

    Whether normal word reading includes a stage of visual processing selectively dedicated to word or letter recognition is highly debated. Characterizing pure alexia, a seemingly selective disorder of reading, has been central to this debate. Two main theories claim either that 1) Pure alexia is caused by damage to a reading specific brain region in the left fusiform gyrus or 2) Pure alexia results from a general visual impairment that may particularly affect simultaneous processing of multiple items. We tested these competing theories in 4 patients with pure alexia using sensitive psychophysical measures and mathematical modeling. Recognition of single letters and digits in the central visual field was impaired in all patients. Visual apprehension span was also reduced for both letters and digits in all patients. The only cortical region lesioned across all 4 patients was the left fusiform gyrus, indicating that this region subserves a function broader than letter or word identification. We suggest that a seemingly pure disorder of reading can arise due to a general reduction of visual speed and span, and explain why this has a disproportionate impact on word reading while recognition of other visual stimuli are less obviously affected. PMID:19366870

  2. Optical characterization of pure vegetable oils and their biodiesels using Raman spectroscopy

    Science.gov (United States)

    Firdous, S.; Anwar, S.; Waheed, A.; Maraj, M.

    2016-04-01

    Great concern regarding energy resources and environmental polution has increased interest in the study of alternative sources of energy. Biodiesels as an alternative fuel provide a suitable diesel oil substitute for internal combustion engines. The Raman spectra of pure biodiesels of soybean oil, olive oil, coconut oil, animal fats, and petroleum diesel are optically characterized for quality and biofuel as an alternative fuel. The most significant spectral differences are observed in the frequency range around 1457 cm-1 for pure petroleum diesel, 1427 for fats biodiesel, 1670 cm-1 for pure soybean oil, 1461 cm-1 for soybean oil based biodiesel, 1670 cm-1 for pure olive oil, 1666 cm-1 for olive oil based biodiesel, 1461 cm-1 for pure coconut oil, and 1460 cm-1 for coconut oil based biodiesel, which is used for the analysis of the phase composition of oils. A diode pump solid-state laser with a 532 nm wavelength is used as an illuminating light. It is demonstrated that the peak positions and relative intensities of the vibrations of the oils can be used to identify the biodiesel quality for being used as biofuel.

  3. Mechanistic insights into a novel exporter-importer system of Mycobacterium tuberculosis unravel its role in trafficking of iron.

    Directory of Open Access Journals (Sweden)

    Aisha Farhana

    2008-05-01

    Full Text Available Elucidation of the basic mechanistic and biochemical principles underlying siderophore mediated iron uptake in mycobacteria is crucial for targeting this principal survival strategy vis-à-vis virulence determinants of the pathogen. Although, an understanding of siderophore biosynthesis is known, the mechanism of their secretion and uptake still remains elusive.Here, we demonstrate an interplay among three iron regulated Mycobacterium tuberculosis (M.tb proteins, namely, Rv1348 (IrtA, Rv1349 (IrtB and Rv2895c in export and import of M.tb siderophores across the membrane and the consequent iron uptake. IrtA, interestingly, has a fused N-terminal substrate binding domain (SBD, representing an atypical subset of ABC transporters, unlike IrtB that harbors only the permease and ATPase domain. SBD selectively binds to non-ferrated siderophores whereas Rv2895c exhibits relatively higher affinity towards ferrated siderophores. An interaction between the permease domain of IrtB and Rv2895c is evident from GST pull-down assay. In vitro liposome reconstitution experiments further demonstrate that IrtA is indeed a siderophore exporter and the two-component IrtB-Rv2895c system is an importer of ferrated siderophores. Knockout of msmeg_6554, the irtA homologue in Mycobacterium smegmatis, resulted in an impaired M.tb siderophore export that is restored upon complementation with M.tb irtA.Our data suggest the interplay of three proteins, namely IrtA, IrtB and Rv2895c in synergizing the balance of siderophores and thus iron inside the mycobacterial cell.

  4. Pure states of general quantum-mechanical systems as Kaehler bundles

    International Nuclear Information System (INIS)

    Abbati, M.C.; Cirelli, R.; Lanzavecchia, P.; Mania, A.

    1984-01-01

    Pure states of general quantum systems in the Csup(*)-algebraic approach are endowed with a structure both of Kaehler manifold and of projective bundle with uniformity on the total space. The former structure gives a geometric interpretation of transition probabilities and Wigner theorem. The latter is a finer structure which determines Csup(*)-algebras up to sup(*)-isomorphisms. Pure states of Csup(*)-algebras with continuous trace among projective bundles with uniformity are characterized

  5. Purely temporal figure-ground segregation.

    Science.gov (United States)

    Kandil, F I; Fahle, M

    2001-05-01

    Visual figure-ground segregation is achieved by exploiting differences in features such as luminance, colour, motion or presentation time between a figure and its surround. Here we determine the shortest delay times required for figure-ground segregation based on purely temporal features. Previous studies usually employed stimulus onset asynchronies between figure- and ground-containing possible artefacts based on apparent motion cues or on luminance differences. Our stimuli systematically avoid these artefacts by constantly showing 20 x 20 'colons' that flip by 90 degrees around their midpoints at constant time intervals. Colons constituting the background flip in-phase whereas those constituting the target flip with a phase delay. We tested the impact of frequency modulation and phase reduction on target detection. Younger subjects performed well above chance even at temporal delays as short as 13 ms, whilst older subjects required up to three times longer delays in some conditions. Figure-ground segregation can rely on purely temporal delays down to around 10 ms even in the absence of luminance and motion artefacts, indicating a temporal precision of cortical information processing almost an order of magnitude lower than the one required for some models of feature binding in the visual cortex [e.g. Singer, W. (1999), Curr. Opin. Neurobiol., 9, 189-194]. Hence, in our experiment, observers are unable to use temporal stimulus features with the precision required for these models.

  6. Assessing the microstructural and rheological changes induced by food additives on potato puree.

    Science.gov (United States)

    Dankar, Iman; Haddarah, Amira; El Omar, Fawaz; Sepulcre, Francesc; Pujolà, Montserrat

    2018-02-01

    The effects of agar, alginate, lecithin and glycerol on the rheological properties of commercial potato puree were investigated and interpreted in terms of starch microstructural changes, and the applicability of the Cox-Merz rule was evaluated. Each additive was applied separately at two concentrations (0.5 and 1%). Microscopic observations revealed more swollen starch aggregations in lecithin and glycerol compared with those of potato puree and agar, consequently affecting the rheological properties of potato puree. All samples exhibited shear thinning non-Newtonian behaviour. Rheological measurements were strongly concentration dependent. At 0.5% concentration, additives exerted decreases in all the rheological properties of potato puree in the order of glycerol>alginate>lecithin>agar, while at 1% concentration, the order changed to glycerol>lecithin>alginate, whereas 1% agar behaved differently, increasing all rheological values. This study also showed that agar and alginate in addition to potato puree could be valuable and advantageous for further technological processes, such as 3D printing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Critical opalescence in the pure Coulomb system

    International Nuclear Information System (INIS)

    Bobrov, V.B.; Trigger, S.A.

    2011-01-01

    Highlights: → The review of the critical opalescence problem is presented. → Light scattering in a two-component electron-nuclear system is studied. → The exact relations between the structure factors and compressibility are found. → The obtained relations are valid for strong interaction for the Coulomb systems. → The experimental verification of these relations is possible for various elements. - Abstract: Based on the dielectric formalism and quantum field theory methods, the phenomenon of critical opalescence is explained for light scattering in pure matter as a two-component electron-nuclear system with Coulomb interaction. A similar phenomenon is shown to occur in the case of neutron scattering in pure substances as well. The obtained results are valid for quantum case and arbitrary strong Coulomb interaction. Thus, the relations between structure factors derived for the electron-nuclear system are the exact result of the quantum statistical mechanics.

  8. Investigations on the properties of pure and rare earth modified bismuth ferrite ceramics

    International Nuclear Information System (INIS)

    Kazhugasalamoorthy, S.; Jegatheesan, P.; Mohandoss, R.; Giridharan, N.V.; Karthikeyan, B.; Joseyphus, R. Justin; Dhanuskodi, S.

    2010-01-01

    Pure BiFeO 3 (BFO) and La-modified BiFeO 3 (Bi 1-x La x FeO 3 with x = 0.2 and 0.4) ceramic powders were synthesized at relatively low temperature by ferrioxalate precursor method. Pure compositions did not yield phase pure powders and contain secondary phases. At the same time, La-modification at different concentration levels in BFO promoted the formation of perovskite phase with the elimination of secondary phases and phase pure ceramic powders were obtained for the composition Bi 1-x La x FeO 3 with x = 0.4. Further, the effect of lanthanum substitution on the morphology, electrical and magnetic properties was also investigated.

  9. Relativistic stars with purely toroidal magnetic fields

    International Nuclear Information System (INIS)

    Kiuchi, Kenta; Yoshida, Shijun

    2008-01-01

    We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The basic equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal magnetic fields are derived for the first time. To solve these basic equations numerically, we extend the Cook-Shapiro-Teukolsky scheme for calculating relativistic rotating stars containing no magnetic field to incorporate the effects of the purely toroidal magnetic fields. By using the numerical scheme, we then calculate a large number of the equilibrium configurations for a particular distribution of the magnetic field in order to explore the equilibrium properties. We also construct the equilibrium sequences of the constant baryon mass and/or the constant magnetic flux, which model the evolution of an isolated neutron star as it loses angular momentum via the gravitational waves. Important properties of the equilibrium configurations of the magnetized stars obtained in this study are summarized as follows: (1) For the nonrotating stars, the matter distribution of the stars is prolately distorted due to the toroidal magnetic fields. (2) For the rapidly rotating stars, the shape of the stellar surface becomes oblate because of the centrifugal force. But, the matter distribution deep inside the star is sufficiently prolate for the mean matter distribution of the star to be prolate. (3) The stronger toroidal magnetic fields lead to the mass shedding of the stars at the lower angular velocity. (4) For some equilibrium sequences of the constant baryon mass and magnetic flux, the stars can spin up as they lose angular momentum.

  10. Fourier-transform ghost imaging with pure far-field correlated thermal light

    International Nuclear Information System (INIS)

    Liu Honglin; Shen Xia; Han Shensheng; Zhu Daming

    2007-01-01

    Pure far-field correlated thermal light beams are created with phase grating, and Fourier-transform ghost imaging depending only on the far-field correlation is demonstrated experimentally. Theoretical analysis and the results of experimental investigation of this pure far-field correlated thermal light are presented. Applications which may be exploited with this imaging scheme are discussed

  11. Is word recognition crowded in pure alexia?

    DEFF Research Database (Denmark)

    Sand, Katrine; Habekost, Thomas; Petersen, Anders

    2017-01-01

    Pure alexia is a selective deficit in reading, which arises following damage to the left ventral occipito-temporal cortex. Crowding, the inability to recognise objects in a clutter, has recently been hypothesised to be the underlying deficit of apperceptive visual agnosia1. Crowding normally occurs...

  12. Angels and demons are among us: assessing individual differences in belief in pure evil and belief in pure good.

    Science.gov (United States)

    Webster, Russell J; Saucier, Donald A

    2013-11-01

    We conducted five studies to demonstrate that individuals' beliefs in pure evil (BPE) and in pure good (BPG) are valid and important psychological constructs. First, these studies together demonstrated that BPE and BPG are reliable, unitary, and stable constructs each composed of eight theoretically interdependent dimensions. Second, these studies showed that across a wide variety of different measures, higher BPE consistently related to greater intergroup aggression (e.g., supporting the death penalty and preemptive military aggression) and less intergroup prosociality (e.g., opposing criminal rehabilitation, proracial policies, and beneficial social programs), while higher BPG consistently related to less intergroup aggression (e.g., opposing proviolent foreign relations and torture) and greater intergroup prosociality (e.g., supporting criminal rehabilitation and support for diplomacy). In sum, these studies evidence that BPE and BPG relate to aggressive and prosocial orientations toward others and have strong potential to advance current theories on prejudice, aggression, and prosociality.

  13. An apparatus for preparing isotopically pure He4

    International Nuclear Information System (INIS)

    McClintock, P.V.E.

    1978-01-01

    A cryostat has been constructed for extracting pure He 4 from He II of natural isotopic composition by means of a heat flush technique. It is shown that the method is in principle capable of yielding He 4 which is entirely devoid of He 3 isotopic impurities. A secondary heat flush, operated in conjunction with a conical heat exchanger of novel design, was used to place an experimental lower bound of 2 x 10 15 on the He 4 /He 3 ratio of the product, a standard sufficient for all present or projected applications requiring isotopically pure He 4 . The apparatus produces 2 000 1 (at standard temperature and pressure) of He 4 per thermal cycle. The design of future purifiers is discussed. (author)

  14. Anodic oxidation of InP in pure water

    International Nuclear Information System (INIS)

    Robach, Y.; Joseph, J.; Bergignat, E.; Hollinger, G.

    1989-01-01

    It is shown that thin InP native oxide films can be grown by anodization of InP in pure water. An interfacial phosphorus-rich In(PO 3 ) 3 -like condensed phosphate is obtained this way. This condensed phosphate has good passivating properties and can be used in electronic device technology. The chemical composition of these native oxides was found similar to that of an anodic oxide grown in an anodization in glycol and water (AGW) electrolyte. From the similarity between the two depth profiles observed in pure water and AGW electrolyte, they can conclude that dissolution phenomena do not seem to play a major role. The oxide growth seems to be controlled by the drift of ionic species under the electric field

  15. Bayero Journal of Pure and Applied Sciences: Submissions

    African Journals Online (AJOL)

    Bayero Journal of Pure and Applied Sciences (BAJOPAS) is an international journal that publishes original research and critical reviews in broad areas of ... Technology, Mathematical Sciences, Microbiology, Physics and Medical Sciences.

  16. pupyMPI - MPI implemented in pure Python

    DEFF Research Database (Denmark)

    Bromer, Rune; Hantho, Frederik; Vinter, Brian

    2011-01-01

    As distributed memory systems have become common, the de facto standard for communication is still the Message Passing Interface (MPI). pupyMPI is a pure Python implementation of a broad subset of the MPI 1.3 specifications that allows Python programmers to utilize multiple CPUs with datatypes...

  17. Revival of pure titanium for dynamically loaded porous implants using additive manufacturing.

    Science.gov (United States)

    Wauthle, Ruben; Ahmadi, Seyed Mohammad; Amin Yavari, Saber; Mulier, Michiel; Zadpoor, Amir Abbas; Weinans, Harrie; Van Humbeeck, Jan; Kruth, Jean-Pierre; Schrooten, Jan

    2015-09-01

    Additive manufacturing techniques are getting more and more established as reliable methods for producing porous metal implants thanks to the almost full geometrical and mechanical control of the designed porous biomaterial. Today, Ti6Al4V ELI is still the most widely used material for porous implants, and none or little interest goes to pure titanium for use in orthopedic or load-bearing implants. Given the special mechanical behavior of cellular structures and the material properties inherent to the additive manufacturing of metals, the aim of this study is to investigate the properties of selective laser melted pure unalloyed titanium porous structures. Therefore, the static and dynamic compressive properties of pure titanium structures are determined and compared to previously reported results for identical structures made from Ti6Al4V ELI and tantalum. The results show that porous Ti6Al4V ELI still remains the strongest material for statically loaded applications, whereas pure titanium has a mechanical behavior similar to tantalum and is the material of choice for cyclically loaded porous implants. These findings are considered to be important for future implant developments since it announces a potential revival of the use of pure titanium for additively manufactured porous implants. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Optical characterization of pure vegetable oils and their biodiesels using Raman spectroscopy

    International Nuclear Information System (INIS)

    Firdous, S; Anwar, S; Waheed, A; Maraj, M

    2016-01-01

    Great concern regarding energy resources and environmental polution has increased interest in the study of alternative sources of energy. Biodiesels as an alternative fuel provide a suitable diesel oil substitute for internal combustion engines. The Raman spectra of pure biodiesels of soybean oil, olive oil, coconut oil, animal fats, and petroleum diesel are optically characterized for quality and biofuel as an alternative fuel. The most significant spectral differences are observed in the frequency range around 1457 cm −1 for pure petroleum diesel, 1427 for fats biodiesel, 1670 cm −1 for pure soybean oil, 1461 cm −1 for soybean oil based biodiesel, 1670 cm −1 for pure olive oil, 1666 cm −1 for olive oil based biodiesel, 1461 cm −1 for pure coconut oil, and 1460 cm −1 for coconut oil based biodiesel, which is used for the analysis of the phase composition of oils. A diode pump solid-state laser with a 532 nm wavelength is used as an illuminating light. It is demonstrated that the peak positions and relative intensities of the vibrations of the oils can be used to identify the biodiesel quality for being used as biofuel. (paper)

  19. Use of HPLC for the detection of iron chelators in cultures of bacteria, fungi, and algae

    International Nuclear Information System (INIS)

    Boyer, G.L.; Speirs, R.J.; Morse, P.D.

    1990-01-01

    Iron is essential for the growth of living cells. To meet biochemical needs, microorganisms, including algae, produce high affinity chelators termed siderophores. These compounds solubilize Fe and increase its bioavailability. We have developed a new method to study siderophore formation in cultured and natural environments. Based on the fact siderophores tightly bind 55-Fe, the radioactive complexes can be separated by HPLC using an inert PRP-1 column and detected by scintillation counting. This method cleanly resolves several known siderophores, including ferrichrome A, ferrichrome, desferal, and rhodotorulic acid. The optimization of the method and its use for analysis of siderophore formation in bacteria (E. coli, and Bacillus megaterium), fungi (Ustilago sphaerogena), and cyanobacteria (Anabaena flos-aqua UTEX 1444 and Anabaena sp. ATCC 27898) will be presented

  20. Modeling the adsorption of mixed gases based on pure gas adsorption properties

    NARCIS (Netherlands)

    Tzabar, N.; Holland, H. J.; Vermeer, C. H.; Ter Brake, H. J.M.

    2015-01-01

    Sorption-based Joule-Thomson (JT) cryocoolers usually operate with pure gases. A sorption-based compressor has many benefits; however, it is limited by the pressure ratios it can provide. Using a mixed-refrigerant (MR) instead of a pure refrigerant in JT cryocoolers allows working at much lower

  1. Canonical form of three-fermion pure-states with six single particle states

    International Nuclear Information System (INIS)

    Chen, Lin; Ž Ðoković, Dragomir; Grassl, Markus; Zeng, Bei

    2014-01-01

    We construct a canonical form for pure states in ∧ 3 (C 6 ), the three-fermion system with six single particle states, under local unitary (LU) transformations, i.e., the unitary group U(6). We also construct a minimal set of generators of the algebra of polynomial U(6)-invariants on ∧ 3 (C 6 ). It turns out that this algebra is isomorphic to the algebra of polynomial LU-invariants of three-qubits which are additionally invariant under qubit permutations. As a consequence of this surprising fact, we deduce that there is a one-to-one correspondence between the U(6)-orbits of pure three-fermion states in ∧ 3 (C 6 ) and the LU orbits of pure three-qubit states when qubit permutations are allowed. As an important byproduct, we obtain a new canonical form for pure three-qubit states under LU transformations U(2) × U(2) × U(2) (no qubit permutations allowed)

  2. Proton irradiation studies on pure Ti and Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Dutta Gupta, A. [Variable Energy Cyclotron Centre, HBNI, 1/AF Bidhannagar, Kolkata (India); Mukherjee, P., E-mail: paramita@vecc.gov.in [Variable Energy Cyclotron Centre, HBNI, 1/AF Bidhannagar, Kolkata (India); Gayathri, N.; Bhattacharyya, P.; Bhattacharya, M. [Variable Energy Cyclotron Centre, HBNI, 1/AF Bidhannagar, Kolkata (India); Sarkar, Apu [Materials Group, Bhabha Atomic Research Centre, Mumbai (India); Sen, S. [Mechanical Engineering, Jadavpur University, Kolkata (India); Mitra, M.K. [Metallurgical and Materials Engineering, Jadavpur University, Kolkata (India)

    2016-11-15

    Post irradiated microstructural characterisation of pure Ti and Ti-6Al-4V has been done as a function of dose using different model based techniques of X-ray diffraction line profile analysis. There is a systematic change of domain size for both the materials with dose but the microstrain within the domain remains almost unaltered. The domain size appears to be lower for pure Ti at all doses as compared to Ti-6Al-4V alloy. XRD peaks became highly asymmetric particularly at a dose of 5 × 10{sup 21} p/m{sup 2} for Ti-6Al-4V samples which is not observed for pure Ti at the same dose. This may be attributed to the segregation of alloying elements as a result of irradiation. Microhardness values increases with dose for pure Ti and then saturates at higher doses whereas microhardness values are found to decrease at higher doses for Ti-6Al-4V.

  3. Effect of Equal-Channel Angular Pressing on Pitting Corrosion of Pure Aluminum

    Directory of Open Access Journals (Sweden)

    Injoon Son

    2012-01-01

    Full Text Available The effect of equal-channel angular pressing (ECAP on the pitting corrosion of pure Al was investigated using electrochemical techniques in solutions containing 0.1 m mol·dm−3 of Na2SO4 and 8.46 mol·dm−3 of NaCl (300 ppm Cl− and followed by surface analysis. The potential for pitting corrosion of pure Al was clearly shifted in the noble direction by the ECAP process indicating that this process improves resistance to pitting corrosion. The time dependence of corrosion potential and the anodic potential at 1 A·m−2 revealed that the rate of formation of Al oxide films increased due to a decrease in the grain size of the Al after ECAP. Since there exists a negligible amount of impurity precipitates in pure Al, the improvement in pitting corrosion resistance of pure Al by ECAP appears to be attributable to an increase in the rate of formation of Al oxide films.

  4. [Effects of laser welding on bond of porcelain fused cast pure titanium].

    Science.gov (United States)

    Zhu, Juan-fang; He, Hui-ming; Gao, Bo; Wang, Zhong-yi

    2006-04-01

    To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium. Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison. No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement. Laser welding does not affect low-fusing porcelain fused to pure titanium.

  5. Investigations in Pure Mathematics: A Constructivist Perspective.

    Science.gov (United States)

    Hirst, Keith; Shiu, Christine

    1995-01-01

    Discusses an investigative, constructivist approach in the context of undergraduate mathematics, with particular reference to pure mathematics, general aims and objectives, assessment strategies, and problems of supervision that affect tutors and lecturers using this approach. Gives students' views on their experiences in this mode of working. (19…

  6. Enantiomeric separation of type I and type II pyrethroid insecticides with different chiral stationary phases by reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Zhang, Ping; Yu, Qian; He, Xiulong; Qian, Kun; Xiao, Wei; Xu, Zhifeng; Li, Tian; He, Lin

    2018-04-01

    The enantiomeric separation of type I (bifenthrin, BF) and type II (lambda-cyhalothrin, LCT) pyrethroid insecticides on Lux Cellulose-1, Lux Cellulose-3, and Chiralpak IC chiral columns was investigated by reversed-phase high-performance liquid chromatography. Methanol/water or acetonitrile/water was used as mobile phase at a flow rate of 0.8 mL/min. The effects of chiral stationary phase, mobile phase composition, column temperature, and thermodynamic parameters on enantiomer separation were carefully studied. Bifenthrin got a partial separation on Lux Cellulose-1 column and baseline separation on Lux Cellulose-3 column, while LCT enantiomers could be completely separated on both Lux Cellulose-1 and Lux Cellulose-3 columns. Chiralpak IC provided no separation ability for both BF and LCT. Retention factor (k) and selectivity factor (α) decreased with the column temperature increasing from 10°C to 40°C for both BF and LCT enantiomers. Thermodynamic parameters including ∆H and ∆S were also calculated, and the maximum R s were not always obtained at lowest temperature. Furthermore, the quantitative analysis methods for BF and LCT enantiomers in soil and water were also established. Such results provide a new approach for pyrethroid separation under reversed-phase condition and contribute to environmental risk assessment of pyrethroids at enantiomer level. © 2017 Wiley Periodicals, Inc.

  7. Pure Neutron Matter Constraints and Nuclear Symmetry Energy

    International Nuclear Information System (INIS)

    Fattoyev, F J; Newton, W G; Xu, Jun; Li, Bao-An

    2013-01-01

    In this review, we will discuss the results of our recent work [1] to study the general optimization of the pure isovector parameters of the popular relativistic mean-field (RMF) and Skyrme-Hartree-Fock (SHF) nuclear energy-density functionals (EDFs), using constraints on the pure neutron matter (PNM) equation of state (EoS) from recent ab initio calculations. By using RMF and SHF parameterizations that give equivalent predictions for ground-state properties of doubly magic nuclei and properties of symmetric nuclear matter (SNM) and PNM, we found that such optimization leads to broadly consistent symmetry energy J and its slope parameter L at saturation density within a tight range of α(J) sym , (b) the symmetry energy at supra-saturation densities, and (c) the radius of neutron stars.

  8. Analysis of pure and malachite green doped polysulfone sample using FT-IR technique

    Science.gov (United States)

    Nayak, Rashmi J.; Khare, P. K.; Nayak, J. G.

    2018-05-01

    The sample of pure and malachite green doped Polysulfone in the form of foil was prepared by isothermal immersion technique. For the preparation of pure sample 4 gm of Polysulfone was dissolved in 50 ml of Dimethyl farmamide (DMF) solvent, while for the preparation of doped sample 10 mg, 50 mg and 100 mg Malachite Green was mixed with 4 gm of Polysulfone respectively. For the study of structural characterization of these pure and doped sample, Fourier Transform Infra-Red Spectroscopy (FT-IR) technique was used. This study shows that the intensity of transmittance decreases as the ratio of doping increases in pure polysulfone. The reduction in intensity of transmittance is clearly apparent in the present case more over the bands were broader which indicates towards charge transfer interaction between the donar and acceptor molecule.

  9. Relation between catalyst-assisted transformation and multiple-copy transformation for bipartite pure states

    International Nuclear Information System (INIS)

    Feng Yuan; Duan Runyao; Ying Mingsheng

    2006-01-01

    We show that in some cases, catalyst-assisted entanglement transformation cannot be implemented by multiple-copy transformation for pure states. This fact, together with the result we obtained in R. Y. Duan, Y. Feng, X. Li, and M. S. Ying, Phys. Rev. A 71, 042319 (2005), namely that the latter can be completely implemented by the former, indicates that catalyst-assisted transformation is strictly more powerful than multiple-copy transformation. For the purely probabilistic setting we find, however, these two kinds of transformations are geometrically equivalent in the sense that the sets of pure states that can be converted into a given pure state with maximal probabilities not less than a given value have the same closure, regardless of whether catalyst-assisted transformation or multiple-copy transformation is used

  10. Probabilistic teleportation of an arbitrary pure state of two atoms

    Institute of Scientific and Technical Information of China (English)

    Yang Zhen-Biao; Wu Huai-Zhi; Su Wan-Jun

    2007-01-01

    In the context of microwave cavity QED, this paper proposes a new scheme for teleportation of an arbitrary pure state of two atoms. The scheme is very different from the previous ones which achieve the integrated state measurement,it deals in a probabilistic but simplified way. In the scheme, no additional atoms are involved and thus only two atoms are required to be detected. The scheme can also be used for the teleportation of arbitrary pure states of many atoms or two-mode cavities.

  11. Generalized Gödel universes in higher dimensions and pure Lovelock gravity

    Science.gov (United States)

    Dadhich, Naresh; Molina, Alfred; Pons, Josep M.

    2017-10-01

    The Gödel universe is a homogeneous rotating dust with negative Λ which is a direct product of a three-dimensional pure rotation metric with a line. We would generalize it to higher dimensions for Einstein and pure Lovelock gravity with only one N th-order term. For higher-dimensional generalization, we have to include more rotations in the metric, and hence we shall begin with the corresponding pure rotation odd (d =2 n +1 )-dimensional metric involving n rotations, which eventually can be extended by a direct product with a line or a space of constant curvature for yielding a higher-dimensional Gödel universe. The considerations of n rotations and also of constant curvature spaces is a new line of generalization and is being considered for the first time.

  12. Computer Solution to the Game of Pure Strategy

    Directory of Open Access Journals (Sweden)

    Laurent Bartholdi

    2012-11-01

    Full Text Available We numerically solve the classical "Game of Pure Strategy" using linear programming. We notice an intricate even-odd behaviour in the results of our computations that seems to encourage odd or maximal bids.

  13. Assessment of semen quality in pure and crossbred Jersey bulls

    Science.gov (United States)

    Kumar, Umesh; Gawande, Ajay P.; Sahatpure, Sunil K.; Patil, Manoj S.; Lakde, Chetan K.; Bonde, Sachin W.; Borkar, Pradnyankur L.; Poharkar, Ajay J.; Ramteke, Baldeo R.

    2015-01-01

    Aim: To compare the seminal attributes of neat, pre-freeze (at equilibration), and post-freeze (24 h after freezing) semen in pure and crossbred Jersey bulls. Materials and Methods: Total 36 ejaculates (3 ejaculates from each bull) were collected from 6 pure Jersey and 6 crossbred Jersey bulls and evaluated for various seminal attributes during neat, pre-freeze, and post-freeze semen. Results: The mean (±standard error [SE]) values of neat semen characteristics in pure and crossbred Jersey bulls were recorded such as volume (ml), color, consistency, mass activity (scale: 0-5), and sperm concentration (millions/ml). The extended semen was further investigated at pre-freeze and post-freeze stages and the mean (±SE) values recorded at neat, pre-freeze, and post-freeze semen were compared between pure and crossbred Jersey bulls; sperm motility (80.55±1.70%, 62.77±1.35%, 46.11±1.43% vs. 80.00±1.80%, 65.00±1.66%, 47.22±1.08%), live sperm count (83.63±1.08%, 71.72±1.09%, 58.67±1.02% vs. 80.00±1.08%, 67.91±1.20%, 51.63±0.97%), total abnormal sperm count (8.38±0.32%, 12.30±0.39%, 16.75±0.42% vs. 9.00±0.45%, 12.19±0.48%, 18.11±0.64%), hypo-osmotic swelling (HOS) reacted spermatozoa (71.88±0.77%, 62.05±0.80%, 47.27±1.05% vs. 72.77±1.02%, 62.11±0.89%, 45.94±1.33%), acrosome integrity (89.05±0.83%, 81.33±0.71%, 71.94±0.86% vs. 86.55±0.57%, 78.66±0.42%, 69.38±0.53%), and DNA integrity (99.88±0.07%, 100, 99.66±0.11% vs. 99.94±0.05%, 100, 99.44±0.18%,). The volume, color, consistency, sperm concentration, and initial motility in pure and crossbred Jersey bulls did not differ significantly (p>0.05). The mass activity was significantly (p0.05) was observed in abnormal sperm; HOS reacted spermatozoa and DNA integrity percentage among breeds. Conclusion: It may be concluded that the quality of pure Jersey bull semen was comparatively better than the crossbred Jersey bulls. PMID:27047028

  14. Acceptability of Musa Balbisiana (Saba Banana Puree in Two Treatments in Making Ice Cream

    Directory of Open Access Journals (Sweden)

    Mario A. De Castro Jr.

    2016-11-01

    Full Text Available Musa Balbisiana or Saba is a variety of banana fruit that is nutritious and readily available in the market the whole year round. This experimental study aimed to determine the acceptability of the ice cream made from Saba banana puree in two treatments (treatment 1- cooked puree and treatment 2- uncooked puree. Data gathered were described and analyzed using a special Analysis of Variance. The sensory characteristics of the ice cream in two treatments were compared with one another based on the 9-point hedonic scale utilized by trained panelist in the education sector in secondary, tertiary and graduate school level that specialized in food related discipline such as Food Technology, Food Service Management, Technology and Livelihood Education- Food Trades and Hotel and Restaurant Management. Results indicated that in treatment 1( cooked puree the taste and texture of the ice cream were liked extremely however its color was rated liked very much, while in treatment 2 (uncooked puree the texture and color were rated liked moderately while its taste was rated liked very much. A comparison of the sensory characteristics between the two treatments revealed that there is a significant difference in terms of taste, texture and color and overall acceptability of the Saba banana ice cream. It is then recommended that in preparing Saba banana puree using treatment 1 (cooking method, the fruit should be subjected in numerous sieving process using a fine mesh siever or sifter to produce good quality puree texture.

  15. Do all pure entangled states violate Bell's inequalities for correlation functions?

    Science.gov (United States)

    Zukowski, Marek; Brukner, Caslav; Laskowski, Wiesław; Wieśniak, Marcin

    2002-05-27

    Any pure entangled state of two particles violates a Bell inequality for two-particle correlation functions (Gisin's theorem). We show that there exist pure entangled N>2 qubit states that do not violate any Bell inequality for N particle correlation functions for experiments involving two dichotomic observables per local measuring station. We also find that Mermin-Ardehali-Belinskii-Klyshko inequalities may not always be optimal for refutation of local realistic description.

  16. 76 FR 69284 - Pure Magnesium From China

    Science.gov (United States)

    2011-11-08

    ... China Determination On the basis of the record \\1\\ developed in the subject five-year review, the United... China would be likely to lead to continuation or recurrence of material injury to an industry in the...), entitled Pure Magnesium from China: Investigation No. 731-TA-696 (Third Review). Issued: November 2, 2011...

  17. Development and evaluation of 'Pure Rush': An online serious game for drug education.

    Science.gov (United States)

    Stapinski, Lexine A; Reda, Bill; Newton, Nicola C; Lawler, Siobhan; Rodriguez, Daniel; Chapman, Catherine; Teesson, Maree

    2018-04-01

    Learning is most effective when it is active, enjoyable and incorporates feedback. Past research demonstrates that serious games are prime candidates to utilise these principles, however the potential benefits of this approach for delivering drug education are yet to be examined in Australia, a country where drug education in schools is mandatory. The serious game 'Pure Rush' was developed across three stages. First, formative consultation was conducted with 115 students (67% male, aged 15-17 years), followed by feasibility and acceptability testing of a prototype of the game (n = 25, 68% male). In the final stage, 281 students (62% female, aged 13-16 years) were randomly allocated to receive a lesson involving Pure Rush or an active control lesson. The lessons were compared in terms of learning outcomes, lesson engagement and future intentions to use illicit drugs. Students enjoyed playing Pure Rush, found the game age-appropriate and the information useful to them. Both the Pure Rush and the active control were associated with significant knowledge increase from pre to post-test. Among females, multi-level mixed-effects regression showed knowledge gain was greater in the Pure Rush condition compared to control (β = 2.36, 95% confidence interval 0.36-4.38). There was no evidence of between condition differences in lesson engagement or future intentions to use illicit drugs. Pure Rush is an innovative online drug education game that is well received by students and feasible to implement in schools. [Stapinski LA, Reda B, Newton NC, Lawler S, Rodriguez D, Chapman C, Teesson M. Development and evaluation of 'Pure Rush': An online serious game for drug education. Drug Alcohol Rev 2017]. © 2017 Australasian Professional Society on Alcohol and other Drugs.

  18. Enantiomeric and Diastereomeric Self-Assembled Multivalent (SAMul) Nanostructures - Understanding the Effects of Chirality on Binding to Polyanionic Heparin and DNA.

    Science.gov (United States)

    Thornalley, Kiri; Laurini, Erik; Pricl, Sabrina; Smith, David K

    2018-05-15

    A family of four self-assembling lipopeptides containing Ala-Lys peptides attached to a C16 aliphatic chain was synthesised. These compounds form two enantiomeric pairs that bear a diastereomeric relationship to one another (C16-L-Ala-L-Lys/C16-D-Ala-D-Lys) and (C16-D-Ala-L-Lys/C16-L-Ala-D-Lys). These diastereomeric pairs have very different critical micelle concentrations (CMCs), with LL/DD < DL/LD suggesting more effective assembly of the former. The self-assembled multivalent (SAMul) systems bind biological polyanions as result of the cationic lysine groups on their surfaces. Polyanion binding was investigated using dye displacement assays and isothermal calorimetry (ITC). On heparin binding, there was no significant enantioselectivity, but there was a binding preference for the diastereomeric assemblies with lower CMCs. Conversely, on binding DNA, there was a significant enantioselective preference for systems displaying D-lysine ligands, with a further slight preference for attachment to L-alanine, with the CMC being irrelevant. Binding to adaptive, ill-defined heparin has a large favourable entropic term, suggesting it depends primarily on the cationic SAMul nanostructure maximising surface contact with heparin, which can adapt, displacing solvent and other ions. Conversely, binding to well-defined, shape-persistent DNA has a larger favourable enthalpic term, and combined with the enantioselectivity, this allows us to suggest that its SAMul binding is based on optimised individual electrostatic interactions at the molecular level, with a preference for binding to D-lysine. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Controlled Remote State Preparation via General Pure Three-Qubit State

    Directory of Open Access Journals (Sweden)

    Yuebo Zha

    2015-07-01

    Full Text Available The protocols for controlled remote state preparation of a single qubit and a general two-qubit state are presented in this paper. The general pure three-qubit states are chosen as shared quantum channel, which are not Local operations and classical communication (LOCC equivalent to the mostly used GHz state. This is the first time that general pure three-qubit states have been introduced to complete remote state preparation. The probability of successful preparation is presented. Moreover, in some special cases, the successful probability could reach a unit value.

  20. Anodic polarization behavior of pure copper in carbonate solutions

    International Nuclear Information System (INIS)

    Kawasaki, Manabu; Taniguchi, Naoki; Naitou, Morimasa

    2008-03-01

    Copper is one of the candidate materials for overpacks. The redox condition at the early stage of the post closure will be oxidizing. In order to understand the influence of environmental factors on the corrosion behavior of copper in such oxidizing environment, anodic polarization tests were performed in carbonate aqueous solution with varying the concentration of representative chemical species in groundwater. As the results of potentiodynamic and potentiostatic tests, anodic polarization behavior of pure copper was summarized as follows; Carbonate ion and bicarbonate ion promoted the passivation of pure copper, and suppressed the initiation of film breakdown. Chloride ion promoted both the active dissolution and initiation of film breakdown of pure copper. The influence of sulfate ion and pH was small, but the action of sulfate ion to the pure copper was similar to that of chloride ion, and the increase of pH was likely to promote the passivation and suppress the initiation of film breakdown. The film breakdown potential, Eb, was represented as a function of the ratio of aggressive ion and inhibiting ion such as [Cl - ]/[HCO 3 - ], [SO 4 2- ]/[HCO 3 - ]. When the ratio exceeds a certain value, the anodic polarization curve becomes active dissolution type so that no macroscopic film breakdown can not be occurred. The lower limit of Eb in passive type region was estimated to be about -200 mV vs. SCE. As the results of potentio static tests, the corrosion form near the Eb was uniform dissolution over the surface, but pitting corrosion and non-uniform corrosion occurred according to the condition of the test solution. Neither pitting corrosion nor non-uniform corrosion occurred at the potential below Eb in every test cases. (author)

  1. Modeling pure culture heterotrophic production of polyhydroxybutyrate (PHB).

    Science.gov (United States)

    Mozumder, Md Salatul Islam; Goormachtigh, Laurens; Garcia-Gonzalez, Linsey; De Wever, Heleen; Volcke, Eveline I P

    2014-03-01

    In this contribution a mechanistic model describing the production of polyhydroxybutyrate (PHB) through pure-culture fermentation was developed, calibrated and validated for two different substrates, namely glucose and waste glycerol. In both cases, non-growth-associated PHB production was triggered by applying nitrogen limitation. The occurrence of some growth-associated PHB production besides non-growth-associated PHB production was demonstrated, although it is inhibited in the presence of nitrogen. Other phenomena observed experimentally and described by the model included biomass growth on PHB and non-linear product inhibition of PHB production. The accumulated impurities from the waste substrate negatively affected the obtained maximum PHB content. Overall, the developed mathematical model provided an accurate prediction of the dynamic behavior of heterotrophic biomass growth and PHB production in a two-phase pure culture system. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Split-Hopkinson pressure bar tests on pure tantalum

    International Nuclear Information System (INIS)

    Dick, Richard D.; Armstrong, Ronald W.; Williams, John D.

    1998-01-01

    Pure tantalum (Ta) was loaded in compression by a split-Hopkinson pressure bar (SHPB) to strain rates from 450 to 6350 s -1 . The results are compared with SHPB data for commercial Ta and with predictions from the constitutive model for Ta developed by Zerilli and Armstrong (Z-A). The main conclusions are: (1) the flow stress versus log strain rate agree with the Z-A constitutive model and other reported data, (2) uniform strain exponents computed on a true stress-strain basis for pure Ta are somewhat greater than those determined from SHPB data for commercial Ta, and (3) in both cases the uniform strain exponents versus log strain rate are in good agreement with predictions from the Z-A constitutive model for strain rates above 1500 s -1 without a clear indication of dislocation generation

  3. Improving quality of an innovative pea puree by high hydrostatic pressure.

    Science.gov (United States)

    Klug, Tâmmila Venzke; Martínez-Sánchez, Ascensión; Gómez, Perla A; Collado, Elena; Aguayo, Encarna; Artés, Francisco; Artés-Hernández, Francisco

    2017-10-01

    The food industry is continuously innovating to fulfill consumer demand for new, healthy, ready-to-eat products. Pea purees could satisfy this trend by increasing the intake of legumes, which are an important source of nutrients. Moreover, sensorial properties like viscosity could be improved by high hydrostatic pressure (HHP). In this study the effect of a boiling treatment (10 min) followed by HHP at 550 kPa (0, 5 or 10 min) on the rheological properties, associated with enzymatic activity and particle size, as well as on the microbial and sensory quality of a pea-based puree stored for 36 days at 5 °C, has been assessed. The particle size of pea puree decreased after all processing treatments, but increased during storage in HHP-treated samples. Conversely, boiling treatment showed an increase in polygalacturonase activity at the end of the storage period, with a decrease in particle size, viscosity and stability. However, 5 min of 550 kPa HHP showed the highest mean particle size, mean surface diameter and viscosity regarding the remaining treatments. The microbial load remained low during storage. HHP treatment can be used by the food industry to improve the rheological properties, viscosity and stability of pea purees. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  4. Tuning the magnetic properties of pure hafnium by high pressure torsion

    International Nuclear Information System (INIS)

    Cepeda-Jiménez, C.M.; Beltrán, J.I.; Hernando, A.; García, M.A.; Ynduráin, F.; Zhilyaev, A.; Pérez-Prado, M.T.

    2017-01-01

    This work demonstrates that room temperature (RT) ferromagnetism might be triggered in pure hafnium (Hf), a classic paramagnet, by severe plastic deformation (SPD) via high pressure torsion (HPT). The origin of this phenomenon is elucidated by a combined approach including density functional theory (DFT) calculations and transmission electron microscopy (TEM). In particular, it is shown that the elastic lattice distorsions induced in pure Hf as a consequence of grain refinement down to the nanocrystalline regime by HPT lead to the development of a new monoclinic crystalline structure that exhibits a spontaneous magnetization at RT. DFT calculations are utilized to prove that local stretching of the original pure Hf hexagonal close packed (hcp) lattice along specific pyramidal directions, due to the presence of internal stresses in the deformed nanostructure, may give rise to the emergence of the monoclinic phase, which is endowed with a net magnetic moment. An excellent agreement is found between DFT calculations and experimental TEM observations, which provide a first evidence of the presence of the pure Hf monoclinic crystal lattice. This work shows that SPD may constitute a viable, yet widely unexplored, strategy to tune the magnetic properties and, in particular, to induce RT ferromagnetism in bulk non-magnetic metals.

  5. Analysis of corneal topography in patients with pure microphthalmia in Eastern China.

    Science.gov (United States)

    Hu, Pei-Hong; Gao, Gui-Ping; Yu, Yao; Pei, Chong-Gang; Zhou, Qiong; Huang, Xin; Zhang, Ying; Shao, Yi

    2015-12-01

    To determine the typical corneal changes in pure microphthalmia using a corneal topography system and identify characteristics that may assist in early diagnosis. Patients with pure microphthalmia and healthy control subjects underwent corneal topography analysis (Orbscan IIZ® Corneal Topography System; Bausch and Lomb, Bridgewater, NJ, USA) to determine degree of corneal astigmatism (mean A), simulation of corneal astigmatism (sim A), mean keratometry (mean K), simulated keratometry (sim K), irregularities in the 3 - and 5-mm zone, and mean thickness of nine distinct corneal regions. Patients with pure microphthalmia (n = 12) had significantly higher mean K, sim K, mean A, sim A, 3.0 mm irregularity and 5.0 mm irregularity, and exhibited significantly more false keratoconus than controls (n = 12). There was a significant between-group difference in the morphology of the anterior corneal surface and the central curvature of the cornea. Changes in corneal morphology observed in this study could be useful in borderline situations to confirm the diagnosis of pure microphthalmia. © The Author(s) 2015.

  6. Purely geometric path integral for spin-foams

    International Nuclear Information System (INIS)

    Shirazi, Atousa Chaharsough; Engle, Jonathan

    2014-01-01

    Spin-foams are a proposal for defining the dynamics of loop quantum gravity via path integral. In order for a path integral to be at least formally equivalent to the corresponding canonical quantization, at each point in the space of histories it is important that the integrand have not only the correct phase—a topic of recent focus in spin-foams—but also the correct modulus, usually referred to as the measure factor. The correct measure factor descends from the Liouville measure on the reduced phase space, and its calculation is a task of canonical analysis. The covariant formulation of gravity from which spin-foams are derived is the Plebanski–Holst formulation, in which the basic variables are a Lorentz connection and a Lorentz-algebra valued 2-form, called the Plebanski 2-form. However, in the final spin-foam sum, one usually sums over only spins and intertwiners, which label eigenstates of the Plebanski 2-form alone. The spin-foam sum is therefore a discretized version of a Plebanski–Holst path integral in which only the Plebanski 2-form appears, and in which the connection degrees of freedom have been integrated out. We call this a purely geometric Plebanski–Holst path integral. In prior work in which one of the authors was involved, the measure factor for the Plebanski–Holst path integral with both connection and 2-form variables was calculated. Before one discretizes this measure and incorporates it into a spin-foam sum, however, one must integrate out the connection in order to obtain the purely geometric version of the path integral. To calculate this purely geometric path integral is the principal task of the present paper, and it is done in two independent ways. Background independence of the resulting path integral is discussed in the final section, and gauge-fixing is discussed in appendix B. (paper)

  7. Quantum entanglement as an aspect of pure spinor geometry

    International Nuclear Information System (INIS)

    Kiosses, V

    2014-01-01

    Relying on the mathematical analogy of the pure states of a two-qubit system with four-component Dirac spinors, we provide an alternative consideration of quantum entanglement using the mathematical formulation of Cartan's pure spinors. A result of our analysis is that the Cartan equation of a two-qubit state is entanglement sensitive in the same way that the Dirac equation for fermions is mass sensitive. The Cartan equation for unentangled qubits is reduced to a pair of Cartan equations for single qubits as the Dirac equation for massless fermions separates into two Weyl equations. Finally, we establish a correspondence between the separability condition in qubit geometry and the separability condition in spinor geometry. (paper)

  8. Effect of microcrystallization on pitting corrosion of pure aluminium

    International Nuclear Information System (INIS)

    Meng Guozhe; Wei Liyan; Zhang Tao; Shao Yawei; Wang Fuhui; Dong Chaofang; Li Xiaogang

    2009-01-01

    A microcrystalline aluminium film with grain size of about 400 nm was prepared by magnetron sputtering technique. Its corrosion behaviour was investigated in NaCl containing acidic solution by means of potentiodynamic polarization curves and electrochemical noise (EN). The polarization results indicated that the corrosion potential of the sample shifted towards more positive direction, while its corrosion current density decreased compared with that of pure coarse-grain Al. The EN analysis based on stochastic model demonstrated that there existed two kinds of effect of microcrystallization on the pitting behaviour of pure aluminium: (1) the rate of pit initiation is accelerated, (2) the pit growth process was impeded. This leads to the enhancement of pitting resistance for the microcrystallized aluminium.

  9. Biocorrosion properties and blood and cell compatibility of pure iron as a biodegradable biomaterial.

    Science.gov (United States)

    Zhang, Erlin; Chen, Haiyan; Shen, Feng

    2010-07-01

    Biocorrosion properties and blood- and cell compatibility of pure iron were studied in comparison with 316L stainless steel and Mg-Mn-Zn magnesium alloy to reveal the possibility of pure iron as a biodegradable biomaterial. Both electrochemical and weight loss tests showed that pure iron showed a relatively high corrosion rate at the first several days and then decreased to a low level during the following immersion due to the formation of phosphates on the surface. However, the corrosion of pure iron did not cause significant increase in pH value to the solution. In comparison with 316L and Mg-Mn-Zn alloy, the pure iron exhibited biodegradable property in a moderate corrosion rate. Pure iron possessed similar dynamic blood clotting time, prothrombin time and plasma recalcification time to 316L and Mg-Mn-Zn alloy, but a lower hemolysis ratio and a significant lower number density of adhered platelets. MTT results revealed that the extract except the one with 25% 24 h extract actually displayed toxicity to cells and the toxicity increased with the increasing of the iron ion concentration and the incubation time. It was thought there should be an iron ion concentration threshold in the effect of iron ion on the cell toxicity.

  10. Pure subrings of the rings Zχ

    International Nuclear Information System (INIS)

    Tsarev, Andrei V

    2009-01-01

    Pure subrings of finite rank in the Z-adic completion of the ring of integers and in its homomorphic images are considered. Certain properties of these rings are studied (existence of an identity element, decomposability into a direct sum of essentially indecomposable ideals, condition for embeddability into a csp-ring, etc.). Additive groups of these rings and conditions under which these rings are subrings of algebraic number fields are described. Bibliography: 12 titles.

  11. Yttrium implantation effects on extra low carbon steel and pure iron

    Energy Technology Data Exchange (ETDEWEB)

    Caudron, E.; Buscail, H. [Clermont-Ferrand-2 Univ., Le Puy en Velay (France). Lab. Vellave d`Elaboration; Jacob, Y.P.; Stroosnijder, M.F. [Institute for Advanced Materials, Joint Research Center, The European Commission, 21020, Ispra (Vatican City State, Holy See) (Italy); Josse-Courty, C. [Laboratoire de Recherche sur la Reactivite des Solides, UMR 56-13 CNRS, UFR Sciences et Techniques, 9 Avenue A. Savary, B.P. 400, 21011, Dijon Cedex (France)

    1999-05-25

    Extra low carbon steel and pure electrolytic iron samples were yttrium implanted using ion implantation technique. Compositions and structures of pure iron and steel samples were investigated before and after yttrium implantation by several analytical and structural techniques (RBS, SIMS, RHEED and XRD) to observe the yttrium implantation depth profiles in the samples. This paper shows the different effects of yttrium implantations (compositions and structures) according to the implanted sample nature. (orig.) 23 refs.

  12. Magnetization oscillations and waves driven by pure spin currents

    Energy Technology Data Exchange (ETDEWEB)

    Demidov, V.E. [Institute for Applied Physics and Center for Nanotechnology, University of Muenster, Corrensstrasse 2-4, 48149 Muenster (Germany); Urazhdin, S. [Department of Physics, Emory University, Atlanta, GA 30322 (United States); Loubens, G. de [SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette (France); Klein, O. [INAC-SPINTEC, CEA/CNRS and Univ. Grenoble Alpes, 38000 Grenoble (France); Cros, V.; Anane, A. [Unité Mixte de Physique CNRS, Thales, Univ. Paris Sud, Université Paris-Saclay, 91767 Palaiseau (France); Demokritov, S.O., E-mail: demokrit@uni-muenster.de [Institute for Applied Physics and Center for Nanotechnology, University of Muenster, Corrensstrasse 2-4, 48149 Muenster (Germany); Institute of Metal Physics, Ural Division of RAS, Yekaterinburg 620041 (Russian Federation)

    2017-02-23

    Recent advances in the studies of pure spin currents–flows of angular momentum (spin) not accompanied by the electric currents–have opened new horizons for the emerging technologies based on the electron’s spin degree of freedom, such as spintronics and magnonics. The main advantage of pure spin current, as compared to the spin-polarized electric current, is the possibility to exert spin transfer torque on the magnetization in thin magnetic films without the electrical current flow through the material. In addition to minimizing Joule heating and electromigration effects, this enables the implementation of spin torque devices based on the low-loss insulating magnetic materials, and offers an unprecedented geometric flexibility. Here we review the recent experimental achievements in investigations of magnetization oscillations excited by pure spin currents in different nanomagnetic systems based on metallic and insulating magnetic materials. We discuss the spectral properties of spin-current nano-oscillators, and relate them to the spatial characteristics of the excited dynamic magnetic modes determined by the spatially-resolved measurements. We also show that these systems support locking of the oscillations to external microwave signals, as well as their mutual synchronization, and can be used as efficient nanoscale sources of propagating spin waves.

  13. Pure water syndrome: Bacteriological quality of Sachet- packed ...

    African Journals Online (AJOL)

    Pure water syndrome: Bacteriological quality of Sachet- packed drinking water ... of fecal contamination and inadequate water treatment or no treatment at all. ... of hygiene criteria were present in the range of 98 and 106 cfu/100ml of water ...

  14. Changes in carotenoids during processing and storage of pumpkin puree.

    Science.gov (United States)

    Provesi, João Gustavo; Dias, Carolinne Odebrecht; Amante, Edna Regina

    2011-09-01

    Changes in the contents of carotenoids and their true retentions (% TR) during the production of puree of Cucurbita moschata 'Menina Brasileira' and of Cucurbita maxima 'Exposição' pumpkins and the stability of such compounds during 180days of storage were monitored by liquid chromatography coupled with a photodiode array detector. Cooking caused higher losses than commercial sterilisation. High losses of xanthophylls such as lutein and violaxanthin were noted during processing and storage of pumpkin puree. Such losses show the low stability of these compounds. The major carotenoids, pro-vitamin A carotenes, namely, α-carotene and all-trans-β-carotene for C. moschata 'Menina Brasileira' and all-trans-β-carotene for C. maxima 'Exposição' obtained high retentions (>75%) after processing. A slight degree of isomerisation of β-carotene was noted in the puree samples, but with low concentrations of cis-isomers. Storage for 180days did not significantly affect (P⩽0.05) the concentrations of these carotenoids. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Investigation on the Enhanced Oxidation of Ferritic/Martensitic Steel P92 in Pure Steam

    Directory of Open Access Journals (Sweden)

    Juntao Yuan

    2014-04-01

    Full Text Available Oxidation of ferritic/martensitic steel P92 was investigated in pure oxygen and in pure steam at 600–800 °C by thermogravimetric analysis (TGA, optical microscopy (OM, scanning electron microscopy (SEM, and X-ray diffraction (XRD. The results showed that the oxidation of P92 was significantly enhanced and multilayer scale with an outer iron oxides layer formed in pure steam. At 700 °C, the gas switch markedly influenced the scaling kinetics and scale microstructure. It was supposed that the higher affinity of iron to steam would be attributed to the enhanced oxidation of P92 in pure steam, and the much easier transport of hydroxyl would account for the significant difference induced by gas switch.

  16. Deformation and recrystallization textures in commercially pure aluminum

    DEFF Research Database (Denmark)

    Hansen, Niels; Juul Jensen, Dorte

    1986-01-01

    The deformation and recrystallization textures of commercially pure aluminum (99.6 pct) containing large intermetallic particles (FeAl3) are measured by neutron diffraction, and the orientation distribution functions (ODF’s) are calculated. Sample parameters are the initial grain size (50 and 350...

  17. Covariant map between Ramond-Neveu-Schwarz and pure spinor formalisms for the superstring

    International Nuclear Information System (INIS)

    Berkovits, Nathan

    2014-01-01

    A covariant map between the Ramond-Neveu-Schwarz (RNS) and pure spinor formalisms for the superstring is found which transforms the RNS and pure spinor BRST operators into each other. The key ingredient is a dynamical twisting of the ten spin-half RNS fermions into five spin-one and five spin-zero fermions using bosonic pure spinors that parameterize an SO(10)/U(5) coset. The map relates massless vertex operators in the two formalisms, and gives a new description of Ramond states which does not require spin fields. An argument is proposed for relating the amplitude prescriptions in the two formalisms

  18. Quadratic Plus Linear Operators which Preserve Pure States of Quantum Systems: Small Dimensions

    International Nuclear Information System (INIS)

    Saburov, Mansoor

    2014-01-01

    A mathematical formalism of quantum mechanics says that a pure state of a quantum system corresponds to a vector of norm 1 and an observable is a self-adjoint operator on the space of states. It is of interest to describe all linear or nonlinear operators which preserve the pure states of the system. In the linear case, it is nothing more than isometries of Hilbert spaces. In the nonlinear case, this problem was open. In this paper, in the small dimensional spaces, we shall describe all quadratic plus linear operators which preserve pure states of the quantum system

  19. Accelerated Generation of Selfed Pure Line Plants for Gene Identification and Crop Breeding

    Directory of Open Access Journals (Sweden)

    Guijun Yan

    2017-10-01

    Full Text Available Production of pure lines is an important step in biological studies and breeding of many crop plants. The major types of pure lines for biological studies and breeding include doubled haploid (DH lines, recombinant inbred lines (RILs, and near isogenic lines (NILs. DH lines can be produced through microspore and megaspore culture followed by chromosome doubling while RILs and NILs can be produced through introgressions or repeated selfing of hybrids. DH approach was developed as a quicker method than conventional method to produce pure lines. However, its drawbacks of genotype-dependency and only a single chance of recombination limited its wider application. A recently developed fast generation cycling system (FGCS achieved similar times to those of DH for the production of selfed pure lines but is more versatile as it is much less genotype-dependent than DH technology and does not restrict recombination to a single event. The advantages and disadvantages of the technologies and their produced pure line populations for different purposes of biological research and breeding are discussed. The development of a concept of complete in vitro meiosis and mitosis system is also proposed. This could integrate with the recently developed technologies of single cell genomic sequencing and genome wide selection, leading to a complete laboratory based pre-breeding scheme.

  20. Strength tests of thin-walled elliptic duralumin cylinders in pure bending and in combined pure bending and torsion

    Science.gov (United States)

    Lundquist, Eugene E; Stowell, Elbridge Z

    1942-01-01

    An analysis is presented of the results of tests made by the Massachusetts Institute of Technology and by the National Advisory Committee for Aeronautics on an investigation of the strength of thin-walled circular and elliptic cylinders in pure bending and in combined torsion and bending. In each of the loading conditions, the bending moments were applied in the plane of the major axis of the ellipse.