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Sample records for dicarboxylic acids part

  1. Producing dicarboxylic acids using polyketide synthases

    DOEpatents

    Katz, Leonard; Fortman, Jeffrey L.; Keasling, Jay D.

    2015-05-26

    The present invention provides for a polyketide synthase (PKS) capable of synthesizing a dicarboxylic acid (diacid). Such diacids include diketide-diacids and triketide-diacids. The invention includes recombinant nucleic acid encoding the PKS, and host cells comprising the PKS. The invention also includes methods for producing the diacids.

  2. Producing dicarboxylic acids using polyketide synthases

    SciTech Connect

    Katz, Leonard; Fortman, Jeffrey L; Keasling, Jay D

    2013-10-29

    The present invention provides for a polyketide synthase (PKS) capable of synthesizing a dicarboxylic acid (diacid). Such diacids include diketide-diacids and triketide-diacids. The invention includes recombinant nucleic acid encoding the PKS, and host cells comprising the PKS. The invention also includes methods for producing the diacids.

  3. 40 CFR 721.3000 - Dicarboxylic acid monoester.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Dicarboxylic acid monoester. 721.3000... Substances § 721.3000 Dicarboxylic acid monoester. (a) Chemical substance and significant new uses subject to... paragraph (a)(2) of this section: dicarboxylic acid monoester, P-83-255. (2) The significant new uses...

  4. 40 CFR 721.3000 - Dicarboxylic acid monoester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Dicarboxylic acid monoester. 721.3000... Substances § 721.3000 Dicarboxylic acid monoester. (a) Chemical substance and significant new uses subject to... paragraph (a)(2) of this section: dicarboxylic acid monoester, P-83-255. (2) The significant new uses...

  5. DICARBOXYLIC ACID CONCENTRATION TRENDS AND SAMPLING ARTIFACTS

    EPA Science Inventory

    Dicarboxylic acids associated with airborne particulate matter were measured during a summer period in Philadelphia that included multiple air pollution episodes. Samples were collected for two ten hour periods each day using a high volume sampler with two quartz fiber filters in...

  6. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aliphatic dicarboxylic...

  7. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aliphatic dicarboxylic...

  8. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aliphatic dicarboxylic...

  9. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as aliphatic dicarboxylic...

  10. 40 CFR 721.2270 - Aliphatic dicarboxylic acid salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aliphatic dicarboxylic acid salt. 721... Substances § 721.2270 Aliphatic dicarboxylic acid salt. (a) Chemical substance and significant new uses... salt (PMN P-92-1352) is subject to reporting under this section for the significant new uses...

  11. Selective conversion of biorefinery lignin into dicarboxylic acids.

    PubMed

    Ma, Ruoshui; Guo, Mond; Zhang, Xiao

    2014-02-01

    The emerging biomass-to-biofuel conversion industry has created an urgent need for identifying new applications for biorefinery lignin. This paper demonstrates a new route to producing dicarboxylic acids from biorefinery lignin through chalcopyrite-catalyzed oxidation in a highly selective process. Up to 95 % selectivity towards stable dicarboxylic acids was obtained for several types of biorefinery lignin and model compounds under mild, environmentally friendly reaction conditions. The findings from this study paved a new avenue to biorefinery lignin conversions and applications.

  12. Selective Conversion of Biorefinery Lignin into Dicarboxylic Acids

    SciTech Connect

    Ma, Ruoshui; Guo, Mond; Zhang, Xiao

    2014-02-01

    The emerging biomass-to-biofuel conversion industry has created an urgent need for identifying new applications for biorefinery lignin. This paper demonstrates a new route to producing dicarboxylic acids from biorefinery lignin through chalcopyrite-catalyzed oxidation in a highly selective process. Up to 95 % selectivity towards stable dicarboxylic acids was obtained for several types of biorefinery lignin and model compounds under mild, environmentally friendly reaction conditions. The findings from this study paved a new avenue to biorefinery lignin conversions and applications.

  13. Dicarboxylic acids with limited numbers of hydrocarbons stabilize cell membrane and increase osmotic resistance in rat erythrocytes.

    PubMed

    Mineo, Hitoshi; Amita, Nozomi; Kawawake, Megumi; Higuchi, Ayaka

    2013-11-01

    We examined the effect of dicarboxylic acids having 0 to 6 hydrocarbons and their corresponding monocarboxylic or tricarboxylic acids in changing the osmotic fragility (OF) in rat red blood cells (RBCs). Malonic, succinic, glutaric and adipic acids, which are dicarboxylic acids with 1, 2, 3 and 4 straight hydrocarbons located between two carboxylic groups, decreased the OF in a concentration-dependent manner. Other long-chain dicarboxylic acids did not change the OF in rat RBCs. The benzoic acid derivatives, isophthalic and terephthalic acids, but not phthalic acid, decreased the OF in a concentration-dependent manner. Benzene-1,2,3-tricarboxylic acid, but not benzene-1,3,5-tricarboxylic acid, also decreased the OF in rat RBCs. On the other hand, monocarboxylic acids possessing 2 to 7 straight hydrocarbons and benzoic acid increased the OF in rat RBCs. In short-chain dicarboxylic acids, a limited number of hydrocarbons between the two carboxylic groups are thought to form a V- or U-shaped structure and interact with phospholipids in the RBC membrane. In benzene dicarboxylic and tricarboxylic acids, a part of benzene nucleus between the two carboxylic groups is thought to enter the plasma membrane and act on acyl-chain in phospholipids in the RBC membrane. For dicarboxylic and tricarboxylic acids, limited numbers of hydrocarbons in molecules are speculated to enter the RBC membrane with the hydrophilic carboxylic groups remaining outside, stabilizing the structure of the cell membrane and resulting in an increase in osmotic resistance in rat RBCs.

  14. Sonolysis of Short-Chain Organic Dicarboxylic Acid Solutions

    NASA Astrophysics Data System (ADS)

    Naruke, Yukio; Harada, Hisashi

    2011-07-01

    Sonolyses of C4 (carbon number 4) dicarboxylic acids (succinic acid, maleic acid, and fumaric acid) were performed in aqueous solution. They changed one into the other during sonication, affording carbon-number-conserving transformations. Maleic acid and fumaric acid were produced from saccinic acid by dehydrogenation. Furthermore, malic acid and tartaric acid were obtained by hydroxylation. The sonochemical reaction processes are discussed in terms of the time dependences of products and the addition of radical scavengers. In addition, mutual isomerization of fumaric acid and maleic acid was observed during sonication without the use of mediators.

  15. Deprotonated Dicarboxylic Acid Homodimers: Hydrogen Bonds and Atmospheric Implications

    SciTech Connect

    Hou, Gao-Lei; Valiev, Marat; Wang, Xue-Bin

    2016-03-31

    Dicarboxylic acids represent an important class of water-soluble organic compounds found in the atmosphere. In this work we are studying properties of dicarboxylic acid homodimer complexes (HO2(CH2)nCO2-[HO2(CH2)nCO2H], n = 0-12), as potentially important intermediates in aerosol formation processes. Our approach is based on experimental data from negative ion photoelectron spectra of the dimer complexes combined with updated measurements of the corresponding monomer species. These results are analyzed with quantum-mechanical calculations, which provide further information about equilibrium structures, thermochemical parameters associated with the complex formation, and evaporation rates. We find that upon formation of the dimer complexes the electron binding energies increase by 1.3–1.7 eV (30.0–39.2 kcal/mol), indicating increased stability of the dimerized complexes. Calculations indicate that these dimer complexes are characterized by the presence of strong intermolecular hydrogen bonds with high binding energies and are thermodynamically favorable to form with low evaporation rates. Comparison with previously studied HSO4-[HO2(CH2)2CO2H] complex (J. Phys. Chem. Lett. 2013, 4, 779-785) shows that HO2(CH2)2CO2-[HO2(CH2)2CO2H] has very similar thermochemical properties. These results imply that dicarboxylic acids not only can contribute to the heterogeneous complexes formation involving sulfuric acid and dicarboxylic acids, but also can promote the formation of homogenous complexes by involving dicarboxylic acids themselves.

  16. Study on dicarboxylic acids in aerosol samples with capillary electrophoresis.

    PubMed

    Adler, Heidi; Sirén, Heli

    2014-01-01

    The research was performed to study the simultaneous detection of a homologous series of α , ω -dicarboxylic acids (C2-C10), oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, and sebacic acids, with capillary electrophoresis using indirect UV detection. Good separation efficiency in 2,6-pyridinedicarboxylic acid as background electrolyte modified with myristyl trimethyl ammonium bromide was obtained. The dicarboxylic acids were ionised and separated within five minutes. For the study, authentic samples were collected onto dry cellulose membrane filters of a cascade impactor (12 stages) from outdoor spring aerosols in an urban area. Hot water and ultrasonication extraction methods were used to isolate the acids from membrane filters. Due to the low concentrations of acids in the aerosols, the extracts were concentrated with solid-phase extraction (SPE) before determination. The enrichment of the carboxylic acids was between 86 and 134% with sample pretreatment followed by 100-time increase by preparation of the sample to 50  μ L. Inaccuracy was optimised for all the sample processing steps. The aerosols contained dicarboxylic acids C2-C10. Then, mostly they contained C2, C5, and C10. Only one sample contained succinic acid. In the study, the concentrations of the acids in aerosols were lower than 10 ng/m(3).

  17. Effects of monoesters of dicarboxylic acids on jet fuel lubricity

    SciTech Connect

    Kislenko, A.S.; Krylov, I.F.; Sokolova, G.I.; Seregin, V.P.; Skovorodin, G.B.

    1987-01-01

    The authors have prepared monoesters of dicarboxylic acids (DCAs) and aliphatic alcohols to study their effects on jet fuel lubricity. The effects of the synthesized compounds on the lubricity of a hydrotreated jet fuel were evaluated in a KIIGA-2 unit. The monoesters were added to the fuel at a concentration of 0.15 mole/m/sup 3/ and an analysis of the data shows that the monoesters of the DCAs do have significant effects on the fuel lubricity. The lubricity effect of these compounds depends on the molecular structure. It was found that dicarboxylic acids and higher fatty alcohols can be used to prepare effective lubricity additives for hydrotreated jet fuels.

  18. Method for the production of dicarboxylic acids

    DOEpatents

    Nghiem, Nhuan Phu; Donnelly, Mark; Millard, Cynthia S.; Stols, Lucy

    1999-01-01

    The present invention is an economical fermentation method for the production of carboxylic acids comprising the steps of a) inoculating a medium having a carbon source with a carboxylic acid-producing organism; b) incubating the carboxylic acid-producing organism in an aerobic atmosphere to promote rapid growth of the organism thereby increasing the biomass of the organism; c) controllably releasing oxygen to maintain the aerobic atmosphere; d) controllably feeding the organism having increased biomass with a solution containing the carbon source to maintain the concentration of the carbon source within the medium of about 0.5 g/L up to about 1 g/L; e) depriving the aerobic atmosphere of oxygen to produce an anaerobic atmosphere to cause the organism to undergo anaerobic metabolism; f) controllably feeding the organism having increased biomass a solution containing the carbon source to maintain the concentration of the carbon source within the medium of .gtoreq.1 g/L; and g) converting the carbon source to carboxylic acids using the anaerobic metabolism of the organism.

  19. Method for the production of dicarboxylic acids

    DOEpatents

    Nghiem, N.P.; Donnelly, M.; Millard, C.S.; Stols, L.

    1999-02-09

    The present invention is an economical fermentation method for the production of carboxylic acids comprising the steps of (a) inoculating a medium having a carbon source with a carboxylic acid-producing organism; (b) incubating the carboxylic acid-producing organism in an aerobic atmosphere to promote rapid growth of the organism thereby increasing the biomass of the organism; (c) controllably releasing oxygen to maintain the aerobic atmosphere; (d) controllably feeding the organism having increased biomass with a solution containing the carbon source to maintain the concentration of the carbon source within the medium of about 0.5 g/l up to about 1 g/l; (e) depriving the aerobic atmosphere of oxygen to produce an anaerobic atmosphere to cause the organism to undergo anaerobic metabolism; (f) controllably feeding the organism having increased biomass a solution containing the carbon source to maintain the concentration of the carbon source within the medium of {>=}1 g/l; and (g) converting the carbon source to carboxylic acids using the anaerobic metabolism of the organism. 7 figs.

  20. Characterization of the binding sites for dicarboxylic acids on bovine serum albumin.

    PubMed Central

    Tonsgard, J H; Meredith, S C

    1991-01-01

    Dicarboxylic acids are prominent features of several diseases, including Reye's syndrome and inborn errors of mitochondrial and peroxisomal fatty acid oxidation. Moreover, dicarboxylic acids are potentially toxic to cellular processes. Previous studies [Tonsgard, Mendelson & Meredith (1988) J. Clin. Invest. 82, 1567-1573] demonstrated that long-chain dicarboxylic acids have a single high-affinity binding site and between one and three lower-affinity sites on albumin. Medium-chain-length dicarboxylic acids have a single low-affinity site. We further characterized dicarboxylic acid binding to albumin in order to understand the potential effects of drugs and other ligands on dicarboxylic acid binding and toxicity. Progesterone and oleate competitively inhibit octadecanedioic acid binding to the single high-affinity site. Octanoate inhibits binding to the low-affinity sites. Dansylated probes for subdomain 2AB inhibit dodecanedioic acid binding whereas probes for subdomain 3AB do not. In contrast, low concentrations of octadecanedioic acid inhibit the binding of dansylated probes to subdomain 3AB and 2AB. L-Tryptophan, which binds in subdomain 3AB, inhibits hexadecanedioic acid binding but has no effect on dodecanedioic acid. Bilirubin and acetylsalicylic acid, which bind in subdomain 2AB, inhibit the binding of medium-chain and long-chain dicarboxylic acids. Our results suggest that long-chain dicarboxylic acids bind in subdomains 2C, 3AB and 2AB. The single low-affinity binding site for medium-chain dicarboxylic acids is in subdomain 2AB. These studies suggest that dicarboxylic acids are likely to be unbound in disease states and may be potentially toxic. PMID:2064600

  1. Conformations, energies, and intramolecular hydrogen bonds in dicarboxylic acids: implications for the design of synthetic dicarboxylic acid receptors.

    PubMed

    Nguyen, Thanh Ha; Hibbs, David E; Howard, Siân T

    2005-09-01

    The various conformers of the dicarboxylic acids HO2C--(CH2)n--CO2H, n = 1-4, were obtained using density functional methods (DFT), both in the gas phase and in the aqueous phase using a polarized continuum model (PCM). Several new conformers were identified, particularly for the two larger molecules glutaric (n = 3) and adipic acid (n =4). The PCM results show that the stability of most conformers were affected, many becoming unstable in the aqueous phase; and the energy ordering of conformers is also different. The results suggest that conformational preferences could be important in determining the design and stability of appropriate synthetic receptors for glutaric and adipic acid. Geometry changes between gas and aqueous phases were most marked in those conformers containing an intramolecular hydrogen bond. Additional calculations have probed the strength of intramolecular hydrogen bonds in these dicarboxylic acids. In the cases of glutaric and adipic acid, the strength of the intramolecular hydrogen bond were estimated to be around 28-29 kJ/mol, without any vibrational energy correction. The intramolecular hydrogen bond energies in malonic and succinic acid were also estimated from the calculated H-bond distances using an empirical relationship. Intramolecular H-bond redshifts of 170-250 cm(-1) have been estimated from the results of the harmonic frequency analyses.

  2. Properties of an Inducible C4-Dicarboxylic Acid Transport System in Bacillus subtilis

    PubMed Central

    Ghei, Om. K.; Kay, William W.

    1973-01-01

    The transport of the tricarboxylic acid cycle C4-dicarboxylic acids was studied in both the wild-type strain and tricarboxylic acid cycle mutants of Bacillus subtilis. Active transport of malate, fumarate, and succinate was found to be inducible by these dicarboxylic acids or by precursors to them, whereas glucose or closely related metabolites catabolite-repressed their uptake. l-Malate was found to be the best dicarboxylic acid transport inducer in succinic dehydrogenase, fumarase, and malic dehydrogenase mutants. Succinate and fumarate are accumulated over 100-fold in succinic dehydrogenase and fumarase mutants, respectively, whereas mutants lacking malate dehydrogenase were unable to accumulate significant quantities of the C4-dicarboxylic acids. The stereospecificity of this transport system was studied from a comparison of the rates of competitive inhibition of both succinate uptake and efflux in a succinate dehydrogenase mutant by utilizing thirty dicarboxylic acid analogues. The system was specific for the C4-dicarboxylic acids of the tricarboxylic acid cycle, neither citrate nor α-ketoglutarate were effective competitive inhibitors. Of a wide variety of metabolic inhibitors tested, inhibiors of oxidative phosphorylation and of the formation of proton gradients were the most potent inhibitors of transport. From the kinetics of dicarboxylic acid transport (Km approximately 10−4 M for succinate or fumarate in succinic acid dehydrogenase and fumarase mutants) and from the competitive inhibition studies, it was concluded that an inducible dicarboxylic acid transport system mediates the entry of malate, fumarate, or succinate into B. subtilis. Mutants devoid of α-ketoglutarate dehydrogenase were shown to accumulate both α-ketoglutarate and glutamate, and these metabolites subsequently inhibited the transport of all the C4-dicarboxylic acids, suggesting a regulatory role. Images PMID:4633350

  3. Homogeneous vs. heterogeneous nucleation in water-dicarboxylic acid systems

    NASA Astrophysics Data System (ADS)

    Hienola, A. I.; Vehkamäki, H.; Riipinen, I.; Kulmala, M.

    2009-03-01

    Binary heterogeneous nucleation of water-succinic/glutaric/malonic/adipic acid on nanometer-sized particles is investigated within the frame of classical heterogeneous nucleation theory. Homogeneous nucleation is also included for comparison. It is found that the nucleation probabilities depend on the contact angle and on the size of the seed particles. New thermodynamical properties, such as saturation vapor pressure, density and surface tension for all the dicarboxylic acid aqueous solutions are included in the calculations. While the new surface tension and density formulations do not bring any significant difference in the computed nucleation rate for homogeneous nucleation for succinic and glutaric acids, the use of the newly derived equations for the vapor pressure decrease the acid concentrations in gas phase by 3 orders of magnitude. According to our calculations, the binary heterogeneous nucleation of succinic acid-water and glutaric acid-water - although it requires a 3-4 orders of magnitude lower vapor concentrations than the homogeneous nucleation - cannot take place under atmospheric conditions. On the other hand binary homogeneous nucleation of adipic acid-water systems might be possible under conditions occuring in upper boundary layer. However, a more detailed characterization of the interaction between the surface and the molecules of the nucleating vapor should be considered in the future.

  4. Infrared Predissociation Spectroscopy of H_2-TAGGED Dicarboxylic Acid Anions

    NASA Astrophysics Data System (ADS)

    Wolk, Arron B.; Kamrath, Michael Z.; Leavitt, Christopher M.; Johnson, Mark A.

    2011-06-01

    Singly charged dicarboxylic acid anions, studied in depth by Wang et al. offer insight into the role of ring strain and conformation on the formation of intramolecular hydrogen bonds. These shared proton bonds, common in proteins and polymer systems, can be crucial in secondary and tertiary structure formation. By tracking the infrared spectra of dicarboxylic acid anions as charge and aliphatic chain length are varied, the tendency of these anions to form ring-like structures with an internally shared proton can be asssesed. To adapt the time-of-flight mass spectrometry/infrared presdissociation experiment to larger systems with significant latent vibrational energy and negligible vapor pressure, an electrospray ionization (ESI)/cryogenic quadrupole trap ion source has been interfaced to the Yale time of flight mass spectrometer. Infrared predissociation spectroscopy is carried out on a series of carboxylate anions cooled to 10K and H_2-tagged in a cryogenic ion trap, underscoring the power of this technique to vibrationally quench and structurally characterize large (> 20 atoms) gaseous ions. This technique recovers sharp transitions (~6 cm^-^1 FWHM) in the linear single photon absorption regime which greatly facilitates comparison with ab initio calculations. The methodology used to condense H_2 on these ions is described, revealing the benefits of a pulsed trapping gas paired with a time delay before ion extraction. The sensitivity of the perturbed H_2 transition to charge center exposure is probed by varying the charge and aliphatic chain length of carboxylate anions. Finally, the structure of four carboxylate anions are characterized using their predissociation spectra. H. K. Woo, X. B. Wang, K. C. Lau and L. S. Wang J. Chem. Phys. A 110, 7801-7805 2006.

  5. Heterogeneous Reaction of HO2 Radical with Dicarboxylic Acid Particles

    NASA Astrophysics Data System (ADS)

    Taketani, F.; Kanaya, Y.

    2010-12-01

    HOx(OH+ HO2) radical plays a central role in the tropospheric chemistry. Recently, the heterogeneous loss of HO2 by aerosol particles is a potentially important HOx sink in the troposphere suggested from observation study. However, there have been few studies for loss of HO2 by aerosols. In this study, we measured the HO2 uptake coefficients for four dicarboxylic acids (succinic acid, glutaric acid, adipic acid, and pimelic acid) aerosol particles under ambient conditions (760Torr and 296K) using an aerosol flow tube(AFT) coupled with a chemical conversion /laser-induced fluorescence(CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere(-10^8 molecules/cm^3). In this system, the effect of the self-reaction of HO2 in the gas phase can be neglected. HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position dependent profiles of LIF intensity were measured as a function of aerosol concentration at 30% and 70% of relative humilities (RH). Determined HO2 uptake coefficients by succinic acid, glutaric acid, adipic acid, and pimelic acid aerosol particles at 30% RH were 0.05 +/- 0.02, 0.07 +/- 0.03, 0.02 +/- 0.01, and 0.06 +/- 0.03, respectively, while the uptake coefficients by those particles at 70% RH were 0.13 +/- 0.05, 0.13 +/- 0.03, 0.06 +/- 0.01, and 0.11 +/- 0.03, respectively. These results suggest that compositions and relative humidity are significant to the HO2 uptake. We will discuss the potential HO2 loss processes.

  6. Production of dicarboxylic acids from novel unsaturated fatty acids by laccase-catalyzed oxidative cleavage.

    PubMed

    Takeuchi, Michiki; Kishino, Shigenobu; Park, Si-Bum; Kitamura, Nahoko; Watanabe, Hiroko; Saika, Azusa; Hibi, Makoto; Yokozeki, Kenzo; Ogawa, Jun

    2016-06-27

    The establishment of renewable biofuel and chemical production is desirable because of global warming and the exhaustion of petroleum reserves. Sebacic acid (decanedioic acid), the material of 6,10-nylon, is produced from ricinoleic acid, a carbon-neutral material, but the process is not eco-friendly because of its energy requirements. Laccase-catalyzing oxidative cleavage of fatty acid was applied to the production of dicarboxylic acids using hydroxy and oxo fatty acids involved in the saturation metabolism of unsaturated fatty acids in Lactobacillus plantarum as substrates. Hydroxy or oxo fatty acids with a functional group near the carbon-carbon double bond were cleaved at the carbon-carbon double bond, hydroxy group, or carbonyl group by laccase and transformed into dicarboxylic acids. After 8 h, 0.58 mM of sebacic acid was produced from 1.6 mM of 10-oxo-cis-12,cis-15-octadecadienoic acid (αKetoA) with a conversion rate of 35% (mol/mol). This laccase-catalyzed enzymatic process is a promising method to produce dicarboxylic acids from biomass-derived fatty acids.

  7. Condensation of anhydrides or dicarboxylic acids with compounds containing active methylene groups. Part 19: Condensation of phthalic and substituted phthalic anhydrides with benzoylacetic ester

    NASA Technical Reports Server (NTRS)

    Rotberg, Y. T.; Oshkaya, V. P.

    1985-01-01

    Phthalylbenzoylacetic ester and its nitro and halogen derivatives were prepared through condensation of phthalic anhydride, nitrophthalic anhydride, and phthalic halide anhydride with benzoylacetic ester in a solution of acetic anhydride and triethylamine. The condensation of hemipinic acid anhydride proceeds similarly, but under more drastic conditions. Derivatives of indan-1,3-dione are also formed, with a small yield, in the reaction of nitrophthalic anhydrides with benzoylacetic ester in the presence of increased quantities of triethylamine.

  8. Condensation of anhydrides or dicarboxylic acids with compounds containing active methylene groups. Part 1: Condensation of phthalic anhydride with acetoacetic and malonic ester

    NASA Technical Reports Server (NTRS)

    Oshkaya, V. P.; Vanag, G. Y.

    1985-01-01

    Phthalic anhydride was condensed with acetoacetic ester in acetic anhydride and triethylamine solution, and when phthalyl chloride was reacted with sodium acetoacetic ester compounds were formed of the phthalide and indandione series: phthalylacetoacetic ester and a derivative of indan-1,3-dione which after boiling with hydrochloric acid yielded indan-1,3-dione. Phthalylmalonic ester was obtained from phthalic anhydride and malonic ester in the presence of triethylamine.

  9. Yearly trend of dicarboxylic acids in organic aerosols from south of Sweden and source attribution

    NASA Astrophysics Data System (ADS)

    Hyder, Murtaza; Genberg, Johan; Sandahl, Margareta; Swietlicki, Erik; Jönsson, Jan Åke

    2012-09-01

    Seven aliphatic dicarboxylic acids (C3-C9) along with phthalic acid, pinic acid and pinonic acid were determined in 35 aerosol (PM10) samples collected over the year at Vavihill sampling station in south of Sweden. Mixture of dichloromethane and methanol (ratio 1:3) was preferred over water for extraction of samples and extraction was assisted by ultrasonic agitation. Analytes were derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) containing 1% trimethylsilyl chloride and analyzed using gas chromatography/mass spectrometry. Among studied analytes, azelaic acid was found maximum with an average concentration of 6.0 ± 3.6 ng m-3 and minimum concentration was found for pimelic acid (1.06 ± 0.63 ng m-3). A correlation coefficients analysis was used for defining the possible sources of analytes. Higher dicarboxylic acids (C7-C9) showed a strong correlation with each other (correlation coefficients (r) range, 0.96-0.97). Pinic and pinonic acids showed an increase in concentration during summer. Lower carbon number dicarboxylic acids (C3-C6) and phthalic acid were found strongly correlated, but showed a poor correlation with higher carbon number dicarboxylic acids (C7-C9), suggesting a different source for them. Biomass burning, vehicle exhaust, photo-oxidation of volatile organic compounds (natural and anthropogenic emissions) were possible sources for dicarboxylic acids.

  10. Transport of malic acid and other dicarboxylic acids in the yeast Hansenula anomala.

    PubMed

    Côrte-Real, M; Leão, C

    1990-04-01

    DL-Malic acid-grown cells of the yeast Hansenula anomala formed a saturable transport system that mediated accumulative transport of L-malic acid with the following kinetic parameters at pH 5.0: Vmax, 0.20 nmol.s-1.mg (dry weight)-1; Km, 0.076 mM L-malate. Uptake of malic acid was accompanied by proton disappearance from the external medium with rates that followed Michaelis-Menten kinetics as a function of malic acid concentration. Fumaric acid, alpha-ketoglutaric acid, oxaloacetic acid, D-malic acid, and L-malic acid were competitive inhibitors of succinic acid transport, and all induced proton movements that followed Michaelis-Menten kinetics, suggesting that all of these dicarboxylates used the same transport system. Maleic acid, malonic acid, oxalic acid, and L-(+)-tartaric acid, as well as other Krebs cycle acids such as citric and isocitric acids, were not accepted by the malate transport system. Km measurements as a function of pH suggested that the anionic forms of the acids were transported by an accumulative dicarboxylate proton symporter. The accumulation ratio at pH 5.0 was about 40. The malate system was inducible and was subject to glucose repression. Undissociated succinic acid entered the cells slowly by simple diffusion. The permeability of the cells by undissociated acid increased with pH, with the diffusion constant increasing 100-fold between pH 3.0 and 6.0.

  11. Salt and cocrystals of sildenafil with dicarboxylic acids: solubility and pharmacokinetic advantage of the glutarate salt.

    PubMed

    Sanphui, Palash; Tothadi, Srinu; Ganguly, Somnath; Desiraju, Gautam R

    2013-12-02

    Sildenafil is a drug used to treat erectile dysfunction and pulmonary arterial hypertension. Because of poor aqueous solubility of the drug, the citrate salt, with improved solubility and pharmacokinetics, has been marketed. However, the citrate salt requires an hour to reach its peak plasma concentration. Thus, to improve solubility and bioavailability characteristics, cocrystals and salts of the drug have been prepared by treating aliphatic dicarboxylic acids with sildenafil; the N-methylated piperazine of the drug molecule interacts with the carboxyl group of the acid to form a heterosynthon. Salts are formed with oxalic and fumaric acid; salt monoanions are formed with succinic and glutaric acid. Sildenafil forms cocrystals with longer chain dicarboxylic acids such as adipic, pimelic, suberic, and sebacic acids. Auxiliary stabilization via C-H···O interactions is also present in these cocrystals and salts. Solubility experiments of sildenafil cocrystal/salts were carried out in 0.1N HCl aqueous medium and compared with the solubility of the citrate salt. The glutarate salt and pimelic acid cocrystal dissolve faster than the citrate salt in a two hour dissolution experiment. The glutarate salt exhibits improved solubility (3.2-fold) compared to the citrate salt in water. Solubilities of the binary salts follow an inverse correlation with their melting points, while the solubilities of the cocrystals follow solubilities of the coformer. Pharmacokinetic studies on rats showed that the glutarate salt exhibits doubled plasma AUC values in a single dose within an hour compared to the citrate salt. The high solubility of glutaric acid, in part originating from the strained conformation of the molecule and its high permeability, may be the reason for higher plasma levels of the drug.

  12. Dicarboxylic acids generated by thermal alteration of kerogen and humic acids

    NASA Technical Reports Server (NTRS)

    Kawamura, Kimitaka; Kaplan, I. R.

    1987-01-01

    Significant amounts (up to 2 percent of organic geopolymers) of low-molecular-weight (LMW) dicarboxylic acids (C2-C10) have been detected during thermal alteration (270 C, 2 h) of kerogens and humic acids isolated from young or ancient lithified sediments. Their distribution is characterized by the predominance of oxalic acid followed by succinic, fumaric, and methylsuccinic acids. These acids are probably released by the breakdown of macromolecular structures, which have incorporated biogenic organic compounds, including diacids, during early digenesis in sediments. Because of their reactivity, LMW diacids may play geochemically important roles under natural conditions.

  13. Determination of Dicarboxylic Acid Concentrations in Surface Microlayer of Dams in Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Kotani, Y.; Taira, N.; Kamizato, C.; Arakaki, T.

    2008-12-01

    The surface microlayer (SML) is a thin layer that forms the boundary between atmosphere and water body. The SML includes fatty acid, protein and other organic compounds. It is the site across which the atmosphere-water system interacts. It also has unique chemical, physical and biological properties, which are very different from those of the underlying water. We determined concentrations of dicarboxylic acids (oxalic, malic, malonic, succinic, adipic, phthalic, fumaric, and maleic acids) in the SML, and compared with those of underlying bulk water. Dicarboxylic acids are the major organic compounds found in atmospheric aerosols, which can be derived from the wind-blown SML. The sampling sites we chose were dams in Okinawa, Japan. The SML was sampled by using a glass plate method. Concentrations of dicarboxylic acids were determined by using a GC-FID after derivatization. The results showed that the dicarboxylic acid concentrations were 2- 17 times higher than those of the underlying water. We have also found that the concentrations of some of the dicarboxylic acids were lower in the afternoon than those in the morning at the same sampling site.

  14. Determination of malic acid and other C4 dicarboxylic acids in atmospheric aerosol samples.

    PubMed

    Röhrl, Andreas; Lammel, Gerhard

    2002-03-01

    An ion chromatographic method was developed which is able to separate five unsubstituted and hydroxy C4 dicarboxylic acids, succinic, malic, tartaric, maleic and fumaric acid, besides the other unsubstituted C2-C5 dicarboxylic acids, oxalic, malonic and glutaric acids, as well as inorganic ions in samples extracted from atmospheric particulate matter. By the application of this method it was found for both rural and urban sites and for various types of air masses that in the summer-time malic acid is the most prominent C4 diacid (64 ng m(-3) by average), exceeding succinic acid concentration (28 ng m(-3) by average) considerably. In winter-time considerably less, a factor of 4-15, C4 acids occurred and succinic acid was more concentrated than malic acid. Tartaric, fumaric and maleic acids were less concentrated (5.1, 5.0 and 4.5 ng m(-3) by average, respectively). Tartaric acid was observed for the first time in ambient air. The results indicate that in particular anthropogenic sources are important for the precursors of succinic, maleic and fumaric acids. Biogenic sources seem to influence the occurrence of malic acid significantly.

  15. Crystal growth and physical characterization of picolinic acid cocrystallized with dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Somphon, Weenawan; Haller, Kenneth J.

    2013-01-01

    Pharmaceutical cocrystals are multicomponent materials containing an active pharmaceutical ingredient with another component in well-defined stoichiometry within the same unit cell. Such cocrystals are important in drug design, particularly for improving physicochemical properties such as solubility, bioavailability, or chemical stability. Picolinic acid is an endogenous metabolite of tryptophan and is widely used for neuroprotective, immunological, and anti-proliferative effects within the body. In this paper we present cocrystallization experiments of a series of dicarboxylic acids, oxalic acid, succinic acid, DL-tartaric acid, pimelic acid, and phthalic acid, with picolinic acid. Characterization by FT-IR and Raman spectroscopy, DSC and TG/DTG analysis, and X-ray powder diffraction show that new compounds are formed, including a 1:1 picolinium tartrate monohydrate, a 2:1 monohydrate adduct of picolinic acid and oxalic acid, and a 2:1 picolinic acid-succinic acid monohydrate cocrystal.

  16. Performance of AA5052 alloy anode in alkaline ethylene glycol electrolyte with dicarboxylic acids additives for aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, DaPeng; Zhang, DaQuan; Lee, KangYong; Gao, LiXin

    2015-11-01

    Dicarboxylic acid compounds, i.e. succinic acid (SUA), adipic acid (ADA) and sebacic acid (SEA), are used as electrolyte additives in the alkaline ethylene glycol solution for AA5052 aluminium-air batteries. It shows that the addition of dicarboxylic acids lowers the hydrogen gas evolution rate of commercial AA5052 aluminium alloy anode. AA5052 aluminium alloy has wide potential window for electrochemical activity and better discharge performance in alkaline ethylene glycol solution containing dicarboxylic acid additives. ADA has the best inhibition effect for the self-corrosion of AA5052 anode among the three dicarboxylic acid additives. Fourier transform infrared spectroscopy (FT-IR) reveals that dicarboxylic acids and aluminium ions can form coordination complexes. Quantum chemical calculations shows that ADA has a smaller energy gap (ΔE, the energy difference between the lowest unoccupied orbital and the highest occupied orbital), indicating that ADA has the strongest interaction with aluminium ions.

  17. Transport of malic acid and other dicarboxylic acids in the yeast Hansenula anomala.

    PubMed Central

    Côrte-Real, M; Leão, C

    1990-01-01

    DL-Malic acid-grown cells of the yeast Hansenula anomala formed a saturable transport system that mediated accumulative transport of L-malic acid with the following kinetic parameters at pH 5.0: Vmax, 0.20 nmol.s-1.mg (dry weight)-1; Km, 0.076 mM L-malate. Uptake of malic acid was accompanied by proton disappearance from the external medium with rates that followed Michaelis-Menten kinetics as a function of malic acid concentration. Fumaric acid, alpha-ketoglutaric acid, oxaloacetic acid, D-malic acid, and L-malic acid were competitive inhibitors of succinic acid transport, and all induced proton movements that followed Michaelis-Menten kinetics, suggesting that all of these dicarboxylates used the same transport system. Maleic acid, malonic acid, oxalic acid, and L-(+)-tartaric acid, as well as other Krebs cycle acids such as citric and isocitric acids, were not accepted by the malate transport system. Km measurements as a function of pH suggested that the anionic forms of the acids were transported by an accumulative dicarboxylate proton symporter. The accumulation ratio at pH 5.0 was about 40. The malate system was inducible and was subject to glucose repression. Undissociated succinic acid entered the cells slowly by simple diffusion. The permeability of the cells by undissociated acid increased with pH, with the diffusion constant increasing 100-fold between pH 3.0 and 6.0. PMID:2339872

  18. Luminescence study of complexation of europium and dicarboxylic acids

    SciTech Connect

    Barthelemy, P.P.; Choppin, G.R. )

    1989-08-23

    Luminescence lifetime measurements of Eu(III) have been used to study the hdration of Eu(III) when complexed by alkane-dicarboxylate ligands. In its mono(malonate) complex, Eu(III) was found to have 2.3 fewer water molecules than the uncomplexed hydrated cation. In the formation of its 1:1 complexes with succinate, glutartate, and adipate, Eu(III) lost 1.5 molecules of water. When these dicarboxylate ligands reacted with the EuNTA complex to form the 1:1:1 ternary species, the malonate anion replaced 2.2, the succinate 1.5, and the glutarate and adipate 1.0 water molecules (all these values have ca. {plus minus}0.5 uncertainty). These data are discussed in terms of the effect on chelation of increased alkyl chain length. 13 refs., 4 figs., 5 tabs.

  19. Synthesis and structural characterisation of amides from picolinic acid and pyridine-2,6-dicarboxylic acid

    PubMed Central

    Devi, Prarthana; Barry, Sarah M.; Houlihan, Kate M.; Murphy, Michael J.; Turner, Peter; Jensen, Paul; Rutledge, Peter J.

    2015-01-01

    Coupling picolinic acid (pyridine-2-carboxylic acid) and pyridine-2,6-dicarboxylic acid with N-alkylanilines affords a range of mono- and bis-amides in good to moderate yields. These amides are of interest for potential applications in catalysis, coordination chemistry and molecular devices. The reaction of picolinic acid with thionyl chloride to generate the acid chloride in situ leads not only to the N-alkyl-N-phenylpicolinamides as expected but also the corresponding 4-chloro-N-alkyl-N-phenylpicolinamides in the one pot. The two products are readily separated by column chromatography. Chlorinated products are not observed from the corresponding reactions of pyridine-2,6-dicarboxylic acid. X-Ray crystal structures for six of these compounds are described. These structures reveal a general preference for cis amide geometry in which the aromatic groups (N-phenyl and pyridyl) are cis to each other and the pyridine nitrogen anti to the carbonyl oxygen. Variable temperature 1H NMR experiments provide a window on amide bond isomerisation in solution. PMID:25954918

  20. Dicarboxylic acids generated by thermal alteration of kerogen and humic acids.

    PubMed

    Kawamura, K; Kaplan, I R

    1987-01-01

    Significant amounts (up to 2% of organic geopolymers) of low molecular weight (LMW) dicarboxylic acids (C2-C10) have been detected during thermal alteration (270 degrees C, 2 h) of kerogens and humic acids isolated from young or ancient lithified sediments. Their distribution is characterized by predominance of oxalic acid followed by succinic, fumaric and methylsuccinic acids. These acids are probably released by the breakdown of macromolecular structures, which have incorporated biogenic organic compounds, including diacids, during early diagenesis in sediments. Because of their reactivity, LMW diacids may play the following geochemically important roles under natural conditions: (1) the diacids dissolve carbonates and clay minerals to increase porosity and permeability, which enhances migration of oils and gas generated from catagenesis of kerogen dispersed in shale, and (2) the diacids may form organo-metal complexes, which are important for mobilization, transport and accumulation of trace metals in sedimentary basins.

  1. Dehydration polycondensation of dicarboxylic acids and diols using sublimating strong brønsted acids.

    PubMed

    Moyori, Takaya; Tang, Tang; Takasu, Akinori

    2012-05-14

    We investigated catalytic activities of strong brønsted acids for dehydration polycondensations of dicarboxylic acids and diols, which were carried out at low temperature (<100 °C) under reduced pressure (0.3-3 mmHg). Strong Brønsted acids, bis(perfluoroalkanesulfonyl)imide and perfluoroalkanesulfonic acid, showed higher activity than p-toluenesulfonic acid or rare-earth catalysts at 60 °C. In particular, bis(nonafluorobutanesulfonyl)imide (Nf(2)NH) showed the highest activity to synthesize not only aliphatic polyester (M(n) > 19000) but also aromatic polyester (M(n) > 7000). The used Nf(2)NH was sublimated from the reaction flask during polycondensation, and the sublimate, Nf(2)NH, was extra pure so that we can reuse the catalyst without loss of the activity in the dehydration polycondensations.

  2. Isoquercitrin Esters with Mono- or Dicarboxylic Acids: Enzymatic Preparation and Properties

    PubMed Central

    Vavříková, Eva; Langschwager, Fanny; Jezova-Kalachova, Lubica; Křenková, Alena; Mikulová, Barbora; Kuzma, Marek; Křen, Vladimír; Valentová, Kateřina

    2016-01-01

    A series of isoquercitrin (quercetin-3-O-β-d-glucopyranoside) esters with mono- or dicarboxylic acids was designed to modulate hydro- and lipophilicity and biological properties. Esterification of isoquercitrin was accomplished by direct chemoenzymatic reaction using Novozym 435 (lipase from Candida antarctica), which accepted C5- to C12-dicarboxylic acids; the shorter ones, such as oxalic (C2), malonic (C3), succinic (C4) and maleic (C4) acids were not substrates of the lipase. Lipophilicity of monocarboxylic acid derivatives, measured as log P, increased with the chain length. Esters with glutaric and adipic acids exhibited hydrophilicity, and the dodecanedioic acid hemiester was more lipophilic. All derivatives were less able to reduce Folin–Ciocalteau reagent (FCR) and scavenge DPPH (1,1-diphenyl-2-picrylhydrazyl) than isoquercitrin; ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) radical-scavenging activity was comparable. Dodecanoate and palmitate were the least active in FCR and ABTS scavenging; dodecanoate and hemiglutarate were the strongest DPPH scavengers. In contrast, most derivatives were much better inhibitors of microsomal lipoperoxidation than isoquercitrin; butyrate and hexanoate were the most efficient. Anti-lipoperoxidant activity of monocarboxylic derivatives, except acetates, decreased with increasing aliphatic chain. The opposite trend was noted for dicarboxylic acid hemiesters, isoquercitrin hemidodecanedioate being the most active. Overall, IQ butyrate, hexanoate and hemidodecanedioate are the most promising candidates for further studies. PMID:27338349

  3. Isoquercitrin Esters with Mono- or Dicarboxylic Acids: Enzymatic Preparation and Properties.

    PubMed

    Vavříková, Eva; Langschwager, Fanny; Jezova-Kalachova, Lubica; Křenková, Alena; Mikulová, Barbora; Kuzma, Marek; Křen, Vladimír; Valentová, Kateřina

    2016-06-07

    A series of isoquercitrin (quercetin-3-O-β-d-glucopyranoside) esters with mono- or dicarboxylic acids was designed to modulate hydro- and lipophilicity and biological properties. Esterification of isoquercitrin was accomplished by direct chemoenzymatic reaction using Novozym 435 (lipase from Candida antarctica), which accepted C₅- to C12-dicarboxylic acids; the shorter ones, such as oxalic (C₂), malonic (C₃), succinic (C₄) and maleic (C₄) acids were not substrates of the lipase. Lipophilicity of monocarboxylic acid derivatives, measured as log P, increased with the chain length. Esters with glutaric and adipic acids exhibited hydrophilicity, and the dodecanedioic acid hemiester was more lipophilic. All derivatives were less able to reduce Folin-Ciocalteau reagent (FCR) and scavenge DPPH (1,1-diphenyl-2-picrylhydrazyl) than isoquercitrin; ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) radical-scavenging activity was comparable. Dodecanoate and palmitate were the least active in FCR and ABTS scavenging; dodecanoate and hemiglutarate were the strongest DPPH scavengers. In contrast, most derivatives were much better inhibitors of microsomal lipoperoxidation than isoquercitrin; butyrate and hexanoate were the most efficient. Anti-lipoperoxidant activity of monocarboxylic derivatives, except acetates, decreased with increasing aliphatic chain. The opposite trend was noted for dicarboxylic acid hemiesters, isoquercitrin hemidodecanedioate being the most active. Overall, IQ butyrate, hexanoate and hemidodecanedioate are the most promising candidates for further studies.

  4. Defluoridation of water using dicarboxylic acids mediated chitosan-polyaniline/zirconium biopolymeric complex.

    PubMed

    Muthu Prabhu, Subbaiah; Meenakshi, Sankaran

    2016-04-01

    The present investigation describes the preparation of hydrogen bonded chitosan-polyaniline/zirconium biopolymeric matrix by grafting method under dicarboxylic acid medium for the removal of fluoride, first time. Herein, the dicarboxylic acids, oxalic acid, malonic acid, succinic acid were used as medium. The synthesized complex was characterized by usual analytical techniques like FTIR, XRD, SEM and EDAX analysis. From the batch equilibrium experiments, the maximum defluoridation capacity (DC) was found to be 8.713 mg/g at room temperature with the minimum contact time of 24 min at 100mg of the sorbent dosage. The temperature study results of adsorption kinetics showed the adsorption behavior could be better described by the pseudo-second-order equation than pseudo-first-order kinetic model. The adsorption isotherm was well fitted by the Freundlich equation rather than Langmuir and D-R isotherms. The mechanism of fluoride removal was ligand exchange at neutral pH and electrostatic attraction at acidic pH of the medium. Regeneration studies were carried out to identify the best regenerant which makes the process cost-effective. Conclusions of this work demonstrate the potential applicability of the dicarboxylic acid mediated chitosan-polyaniline/zirconium complex as an effective adsorbent for fluoride removal from water.

  5. Distribution of dicarboxylic acids and carbon isotopic compositions in aerosols from 1997 Indonesian forest fires

    NASA Astrophysics Data System (ADS)

    Narukawa, M.; Kawamura, K.; Takeuchi, N.; Nakajima, T.

    Fine aerosol particles collected in Southeast Asia during 1997 Indonesian forest fires were studied for the concentrations of total carbon (TC), water-soluble organic carbon (WSOC) and low molecular weight dicarboxylic acids (C2-C12) as well as carbon isotopic ratios of TC (δ13CTC). TC and WSOC showed a large increase during the heavy forest fire event. At the same period, dicarboxylic acids, dominated by oxalic (C2) followed by succinic (C4) and malonic (C3) acids, also showed a concentration increase. Furthermore, the δ13CTC showed a decrease from ca. -25.5 to -27.5‰ during an intensified forest fire event, suggesting an addition of organic aerosols derived from C3 plants whose δ13C are lighter. These results indicate that the aerosol particles in Southeast Asia were significantly affected by the combustion processes of vegetations during the 1997 Indonesian forest fires that were extensively induced by El Ninõ event.

  6. Bicyclic alpha,omega-dicarboxylic acid derivatives from a colonial tunicate of the family Polyclinidae.

    PubMed

    Bao, Baoquan; Dang, Hung The; Zhang, Ping; Hong, Jongki; Lee, Chong-O; Cho, Hee Young; Jung, Jee H

    2009-11-01

    In the course of our search for bioactive metabolites from a colonial tunicate of the family Polyclinidae, six new (1-6) cyclic fatty acid derivatives were isolated. Their planar structures were established on the basis of NMR and MS spectroscopic analyses. The relative configuration was determined by NOESY experiment. Compounds 1-6 represent a fused bicyclic skeleton possibly derived from alpha,omega-dicarboxylic acids such as eicosanedioic acid or docosanedioic acid via a Diels-Alder type of cyclization. Compounds 1-4 and 6 showed mild cytotoxicity against a panel of five human solid tumor cell lines.

  7. Optical Absorption, Stability and Structure of NpO2+ Complexeswith Dicarboxylic Acids

    SciTech Connect

    Guoxin Tian; Linfeng Rao

    2006-01-04

    Complexation of NpO2+ with oxalic acid (OX),2,2'-oxydiacetic acid (ODA), 2,2'-iminodiacetic acid (IDA) and 2,2'-thiodiacetic acid (TDA), has been studied using spectrophotometry in1 M NaClO4. Both the position and the intensity of the absorption band of NpO2+ at 980 nm are affected by the formation of NpO2+/dicarboxylate complexes, providing useful information on the complexation strength, the coordination mode and the structure of the complexes.

  8. Different geometrical arrangements in carboxylate coordination polymers of flexible dicarboxylic acid

    SciTech Connect

    Deka, Himangshu; Sarma, Rupam; Kumari, Satchi; Khare, Alika; Baruah, Jubaraj B.

    2011-07-15

    Dicarboxylate coordination polymers (1-5) of Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II), respectively, derived from (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid (L{sub 1}H{sub 2}) are synthesized and characterized. Depending on the coordination sites around the metal centers and coordination mode of the ligand, dimensionality of these polymers varies. The dicarboxylates adopt three spatial orientations: in-plane linear coordination, out-of-plane cis coordination and out-of-plane trans coordination mode. Both the cis and trans out-of-plane coordination modes are found to exist only if the ancillary ligand pyridine is coordinated to the metal ion. When the aquoligand coordinates the in-plane linear coordination mode of L{sub 1} predominates. The coordination polymers 4 and 5 show photoluminescence in solution. The dicarboxylate of (5-carboxymethoxy-naphthalen-1-yloxy)-acetic acid (L{sub 2}H{sub 2}) does not form coordination polymer under ambient conditions, but prefers to remain as uncoordinated anion providing hydrophobic confinement to hexa-aquometal(II) cation. Compound 3 crystallizes in P2{sub 1} space group and it shows broadband ultra-violet fluorescence centered at 352.9 nm on focusing 632.8 nm He:Ne laser. - Graphical abstract: Different geometrical arrangements in coordination polymers derived from (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid of metal ions Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) are presented. The (5-carboxymethoxy-naphthalen-1-yloxy)-acetic acid led to hexa-aquo cadmium(II) dicarboxylate. Highlights: > Structural and spectroscopic characterizations of five dicarboxylate coordination polymers of (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid with different metal ions are presented. > Different geometrical arrangements of coordination polymers stabilized in solid state are described. > Photoluminescence properties of the polymers are shown. > NLO property of a copper coordination polymer is described.

  9. B vitamin supplementation reduces excretion of urinary dicarboxylic acids in autistic children.

    PubMed

    Kałużna-Czaplińska, Joanna; Socha, Ewa; Rynkowski, Jacek

    2011-07-01

    Urinary dicarboxylic acids are an important source of information about metabolism and potential problems especially connected with energy production, intestinal dysbiosis, and nutritional individuality in autistic children. A diet rich in vitamins and macroelements is a new idea of intervention in autism. The objective of the present study was to test the hypothesis that vitamin B2, vitamin B6, and magnesium supplementation is effective in reducing the level of dicarboxylic acids in the urine of autistic children. We examined the levels of succinic, adipic, and suberic acids in the urine of autistic children before and after vitamin supplementation. Thirty children with autism received magnesium (daily dose, 200 mg), vitamin B6 (pyridoxine; daily dose, 500 mg), and vitamin B2 (riboflavin; daily dose, 20 mg). The treatment was provided for a period of 3 months. Organic acids were determined using gas chromatography/mass spectrometry. Before supplementation, the levels of succinic, adipic, and suberic acids in the urine of autistic children were 41.47 ± 50.40 μmol/mmol creatinine, 15.61 ± 15.31 μmol/mmol creatinine, 8.02 ± 6.08 μmol/mmol creatinine; and after supplementation, the levels were 9.90 ± 8.26 μmol/mmol creatinine, 2.92 ± 2.41 μmol/mmol creatinine, and 2.57 ± 3.53 μmol/mmol creatinine, respectively. The results suggest that the supplementation reduces the level of dicarboxylic acid in the urine of autistic children.

  10. Aircraft observations of water-soluble dicarboxylic acids in the aerosols over China

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Lin; Kawamura, Kimitaka; Qing Fu, Ping; Boreddy, Suresh K. R.; Watanabe, Tomomi; Hatakeyama, Shiro; Takami, Akinori; Wang, Wei

    2016-05-01

    Vertical profiles of dicarboxylic acids, related organic compounds and secondary organic aerosol (SOA) tracer compounds in particle phase have not yet been simultaneously explored in East Asia, although there is growing evidence that aqueous-phase oxidation of volatile organic compounds may be responsible for the elevated organic aerosols (OA) in the troposphere. Here, we found consistently good correlation of oxalic acid, the most abundant individual organic compounds in aerosols globally, with its precursors as well as biogenic-derived SOA compounds in Chinese tropospheric aerosols by aircraft measurements. Anthropogenically derived dicarboxylic acids (i.e., C5 and C6 diacids) at high altitudes were 4-20 times higher than those from surface measurements and even occasionally dominant over oxalic acid at altitudes higher than 2 km, which is in contrast to the predominance of oxalic acid previously reported globally including the tropospheric and surface aerosols. This indicates an enhancement of tropospheric SOA formation from anthropogenic precursors. Furthermore, oxalic acid-to-sulfate ratio maximized at altitudes of ˜ 2 km, explaining aqueous-phase SOA production that was supported by good correlations with predicted liquid water content, organic carbon and biogenic SOA tracers. These results demonstrate that elevated oxalic acid and related SOA compounds from both the anthropogenic and biogenic sources may substantially contribute to tropospheric OA burden over polluted regions of China, implying aerosol-associated climate effects and intercontinental transport.

  11. Phase diagrams and water activities of aqueous dicarboxylic acid systems of atmospheric importance.

    PubMed

    Beyer, Keith D; Friesen, Katherine; Bothe, Jameson R; Palet, Benjamin

    2008-11-20

    We have studied liquid/solid phase diagrams and water activities of the dicarboxylic acid/water binary systems for maleic, dl-malic, glutaric, and succinc acids using differential scanning calorimetry, infrared (IR) spectroscopy of thin films, and conductivity analysis of saturated solutions. For each binary system we report the measurements of the ice melting envelope, the acid dissolution envelope, and the ice/acid eutectic temperature and composition. Water activities have been determined by using the freezing point depression of ice. Additionally, an irreversible solid/solid phase transition for maleic acid was observed in both DSC and IR studies likely due to the conversion of a meta-stable crystal form of maleic acid to its most stable crystal form. In general we find good agreement with literature values for temperature-dependent acid solubilities.

  12. Hygroscopic Behavior of Multicomponent Aerosols Involving NaCl and Dicarboxylic Acids.

    PubMed

    Peng, Chao; Jing, Bo; Guo, Yu-Cong; Zhang, Yun-Hong; Ge, Mao-Fa

    2016-02-25

    Atmospheric aerosols are usually complex mixtures of inorganic and organic compounds. The hygroscopicity of mixed particles is closely related to their chemical composition and interactions between components, which is still poorly understood. In this study, the hygroscopic properties of submicron particles composed of NaCl and dicarboxylic acids including oxalic acid (OA), malonic acid (MA), and succinic acid (SA) with various mass ratios are investigated with a hygroscopicity tandem differential mobility analyzer (HTDMA) system. Both the Zdanovskii-Stokes-Robinson (ZSR) method and extended aerosol inorganics model (E-AIM) are applied to predict the water uptake behaviors of sodium chloride/dicarboxylic acid mixtures. For NaCl/OA mixed particles, the measured growth factors were significantly lower than predictions from the model methods, indicating a change in particle composition caused by chloride depletion. The hygroscopic growth of NaCl/MA particles was well described by E-AIM, and that of NaCl/SA particles was dependent upon mixing ratio. Compared with model predictions, it was determined that water uptake of the NaCl/OA mixture could be enhanced and could be closer to the predictions by addition of levoglucosan or malonic acid, which retained water even at low relative humidity (RH), leading to inhibition of HCl evaporation during dehydration. These results demonstrate that the coexisting hygroscopic species have a strong influence on the phase state of particles, thus affecting chemical interactions between inorganic and organic compounds as well as the overall hygroscopicity of mixed particles.

  13. Photoelectron spectroscopy of carbonyls: saturated normal dicarboxylic acids

    SciTech Connect

    Chattopadhyay, S.; Meeks, J.L.; Findley, G.L.; McGlynn, S.P.

    1981-04-16

    The ultraviolet photoelectron spectra (UPS) of oxalic, malonic, succinic, glutaric, and adipic acids, and various of their simple derivatives, are presented and discussed. The four lowest-energy ionization events, (I(n/sub +/), I(n/sub -), I (..pi../sub +/), I(..pi../sub -/)), are assigned in all cases. Higher ionization events are not assigned because of molecule-limited resolution in the higher-energy UPS region.

  14. Impacts of biomass burning smoke on the distributions and concentrations of C2-C5 dicarboxylic acids and dicarboxylates in a tropical urban environment

    NASA Astrophysics Data System (ADS)

    Yang, Liming; Nguyen, Duc Minh; Jia, Shiguo; Reid, Jeffrey S.; Yu, Liya E.

    2013-10-01

    Daily ambient PM2.5 was collected during 8 September to 5 October (Julian Days, JDs 252-279), 2008 in Singapore to investigate impacts of transboundary biomass burning smoke on distribution among C2-C5 dicarboxylic acids (DCAs) and corresponding dicarboxylate salts (DCS) in the tropical urban atmosphere. Quantification of DCAs and DCS were performed using solvent and water extraction followed by chromatography analyses via GC-MS and ion chromatography. The averaged PM2.5 and PM10 concentrations from September 19-30 (JDs 263-274) were concurrently elevated by ˜40% due to the transboundary smoke. During this same period, C2-C5 total dicarboxylates (TDCAS, summation of DCAs and DCS), on average, increased more than two times, with C2-TDCAS accounted for in average 80% of the C2-C5 TDCAS. This demonstrates that the transboundary smoke enriched C2-C5 TDCAS more than PM2.5 in the urban environment. In the presence of the transboundary smoke, the averaged concentration ratios of C2-C5 DCS to corresponding DCA were 13.4, 2.9, 1.0, and 1.4 with oxalate salts exhibiting the highest concentration (355.0 ng m-3). The transboundary smoke increased malic acid concentration more than 3.5 times, which is the largest relative increase among the quantified TDCAS. Considering that malic acid is mainly generated through ambient photooxidation, such significant increase in malic acid demonstrates more prominent photooxidation incurred by the smoke.

  15. Optical Properties of Internally Mixed Aerosol Particles Composed of Dicarboxylic Acids and Ammonium Sulfate

    NASA Astrophysics Data System (ADS)

    Freedman, Miriam A.; Hasenkopf, Christa A.; Beaver, Melinda R.; Tolbert, Margaret A.

    2009-10-01

    We have investigated the optical properties of internally mixed aerosol particles composed of dicarboxylic acids and ammonium sulfate using cavity ring-down aerosol extinction spectroscopy at a wavelength of 532 nm. The real refractive indices of these nonabsorbing species were retrieved from the extinction and concentration of the particles using Mie scattering theory. We obtain refractive indices for pure ammonium sulfate and pure dicarboxylic acids that are consistent with literature values, where they exist, to within experimental error. For mixed particles, however, our data deviates significantly from a volume-weighted average of the pure components. Surprisingly, the real refractive indices of internal mixtures of succinic acid and ammonium sulfate are higher than either of the pure components at the highest organic weight fractions. For binary internal mixtures of oxalic or adipic acid with ammonium sulfate, the real refractive indices of the mixtures are approximately the same as ammonium sulfate for all organic weight fractions. Various optical mixing rules for homogeneous and slightly heterogeneous systems fail to explain the experimental real refractive indices. It is likely that complex particle morphologies are responsible for the observed behavior of the mixed particles. Implications of our results for atmospheric modeling and aerosol structure are discussed.

  16. Identification and quantitation of urinary dicarboxylic acids as their dicyclohexyl esters in disease states by gas chromatography mass spectrometry.

    PubMed

    Norman, E J; Berry, H K; Denton, M D

    1979-12-01

    Clinical studies were conducted by gas chromatography mass spectrometry selected ion monitoring of urinary dicarboxylic acids as dicyclohexyl esters. The dicyclohexyl esters of the dicarboxylic acids give characteristic electron impact mass spectra suitable for selected ion monitoring. The mass spectra exhibit a prominent acid + 1H ion and an (acid + 1H)-H2O ion for use as quantitating and confirming ions. The cyclohexyl esters are stable for days at room temperature and have excellent chromatographic properties. Dicarboxylic acid quantitation is performed within one hour using only 50 microliter of unpurified urine. A rapid method specifically for methylmalonic acid quantitation is described which has assisted physicians in the diagnosis of pernicious anemia and methylmalonic aciduria. This procedure is applicable for screening urinary organic acids for detection of inborn errors of metabolism. The detection of a child with elevated medium length dicarboxylic acids in the terminal urine specimen is reported. This condition, previously described as an inborn error, is attributed to a terminal event. Finally, an increase in urinary succinic acid paralleling putrescine levels is described during a response to cancer chemotherapy.

  17. Size distributions of nano/micron dicarboxylic acids and inorganic ions in suburban PM episode and non-episodic aerosol

    NASA Astrophysics Data System (ADS)

    Hsieh, Li-Ying; Kuo, Su-Ching; Chen, Chien-Lung; Tsai, Ying I.

    The distribution of nano/micron dicarboxylic acids and inorganic ions in size-segregated suburban aerosol of southern Taiwan was studied for a PM episode and a non-episodic pollution period, revealing for the first time the distribution of these nanoscale particles in suburban aerosols. Inorganic species, especially nitrate, were present in higher concentrations during the PM episode. A combination of gas-to-nuclei conversion of nitrate particles and accumulation of secondary photochemical products originating from traffic-related emissions was likely a crucial cause of the PM episode. Sulfate, ammonium, and oxalic acid were the dominant anion, cation, and dicarboxylic acid, respectively, accounting for a minimum of 49% of the total anion, cation or dicarboxylic acid mass. Peak concentrations of these species occurred at 0.54 μm in the droplet mode during both non-episodic and PM episode periods, indicating an association with cloud-processed particles. On average, sulfate concentration was 16-17 times that of oxalic acid. Oxalic acid was nevertheless the most abundant dicarboxylic acid during both periods, followed by succinic, malonic, maleic, malic and tartaric acid. The mass median aerodynamic diameter (MMAD) of oxalic acid was 0.77 μm with a bi-modal presence at 0.54 μm and 18 nm during non-episodic pollution and an MMAD of 0.67 μm with mono-modal presence at 0.54 μm in PM episode aerosol. The concomitant formation of malonic acid and oxalic acid was attributed to in-cloud processes. During the PM episode in the 5-100 nm nanoscale range, an oxalic acid/sulfate mass ratio of 40.2-82.3% suggested a stronger formation potential for oxalic acid than for sulfate in the nuclei mode. For total cations (TC), total inorganic anions (TIA) and total dicarboxylic acids (TDA), major contributing particles were in the droplet mode, with least in the nuclei mode. The ratio of TDA to TIA in the nuclei mode increased greatly from 8.40% during the non-episodic pollution

  18. Piezoelectric crystal microbalance measurements of enthalpy of sublimation of C2-C9 dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Dirri, F.; Palomba, E.; Longobardo, A.; Zampetti, E.

    2015-07-01

    We present here a novel experimental setup able to measure the enthalpy of sublimation of a given compound by means of Piezoelectric Crystal Microbalances (PCM). This experiment was performed in the TG-Lab facility in IAPS-INAF, dedicated to the development of TGA sensors for space measurements, such as detection of organic and non-organic volatile species and refractory materials in planetary environments. In order to study physical-chemical processes concerning the Volatile Organic Compounds (VOC) present in atmospheric environments, the setup has been tested on Dicarboxylic acids. Acids with low molecular weight are among the components of organic fraction of particulate matter in the atmosphere, coming from different sources (biogenic and anthropogenic). Considering their relative abundance, it is useful to consider Dicarboxylic acid as "markers" to define the biogenic or anthropogenic origin of the aerosol, thus obtaining some information of the emission sources. In this work, a temperature controlled effusion cell was used to sublimate VOC, creating a molecular flux that was collimated onto a cold PCM. The VOC re-condensed onto the PCM quartz crystal allowing the determination of the deposition rate. From the measurements of deposition rates, it was possible to infer the enthalpy of sublimation of Adipic acid, i.e. Δ Hsub: 141.6 ± 0.8 kJ mol-1, Succinic acid, i.e. 113.3 ± 1.3 kJ mol-1, Oxalic acid, i.e. 62.5 ± 3.1 kJ mol-1 and Azelaic acid, i.e. 124.2 ± 1.2 kJ mol-1 (weight average values). The results obtained are in very good agreement with literature within 10 % for the Adipic, Succinic and Oxalic acid.

  19. Adding value to plant oils and fatty acids: Biological transformation of fatty acids into ω-hydroxycarboxylic, α,ω-dicarboxylic, and ω-aminocarboxylic acids.

    PubMed

    Seo, Joo-Hyun; Lee, Sun-Mee; Lee, Jinwon; Park, Jin-Byung

    2015-12-20

    Not only short chain ω-hydroxycarboxylic acids, α,ω-dicarboxylic acids, and ω-aminocarboxylic acids but also medium to long chain carboxylic acids are widely used as building blocks and intermediates in the chemical, pharmaceutical, and food industries. Thereby, recent achievements in biological production of medium to long chain carboxylic acids are addressed here. ω-Hydroxycarboxylic and α,ω-dicarboxylic acids were synthesized via terminal CH bond oxygenation of fatty acids and/or internal oxidative cleavage of the fatty acid carbon skeletons. ω-Aminocarboxylic acids were enzymatically produced from ω-hydroxycarboxylic acids via ω-oxocarboxylic acids. Productivities and product yields of some of the products are getting close to the industrial requirements for large scale production.

  20. Poly[diaqua(μ(2)-3-carboxypyrazine-2-carboxylato)(μ(2)-pyrazine-2,3-dicarboxylic acid)potassium(I)].

    PubMed

    Tombul, Mustafa; Güven, Kutalmis; Svoboda, Ingrid

    2007-12-15

    The structural unit of the title compound, [K(C(6)H(3)N(2)O(4))(C(6)H(4)N(2)O(4))(H(2)O)(2)](n), consists of one potassium cation, one hydrogen pyrazine-2,3-dicarboxyl-ate anion, one pyrazine-2,3-dicarboxylic acid mol-ecule and two water mol-ecules; this is twice the asymmetric unit, since the potassium cation lies on an inversion centre. Each anion or acid mol-ecule is linked to two potassium cations, while the potassium cation has contacts to four symmetry-equivalent organic ligands, with two different coordination modes towards this cation. In addition, each potassium cation is coordinated by two water O atoms, raising the coordination number to eight. One of the carboxyl groups of the acid retains its H atom, which forms a hydrogen bond to a coordinated water mol-ecule. The other carboxyl group is deprotonated in half of the ligands and protonated in the other half, taking part in a strong O-H⋯O hydrogen bond disordered over an inversion centre. The stabilization of the crystal structure is further assisted by O-H⋯O and O-H⋯N hydrogen bonds in which water acts as the donor.

  1. catena-Poly[[diaqua-rubidium(I)](μ(2)-3-carboxy-pyrazine-2-carboxyl-ato)(μ(2)-pyrazine-2,3-dicarboxylic acid)].

    PubMed

    Tombul, Mustafa; Guven, Kutalmis

    2009-01-23

    The structural unit of the title compound, [Rb(C(6)H(3)N(2)O(4))(C(6)H(4)N(2)O(4))(H(2)O)(2)](n), consists of one rubidium cation, one hydrogen pyrazine-2,3-dicarboxyl-ate anion, one pyrazine-2,3-dicarboxylic acid mol-ecule and two water mol-ecules. This formulation is repeated twice in the asymmetric unit as the rubidium cation lies on an inversion centre. Each anion or acid mol-ecule is linked to two rubidium cations, while the rubidium cation has close contacts to four symmetry-equivalent organic ligands, with two different coordination modes towards this cation. In addition, each rubidium cation is coordinated by two water O atoms, raising the coordination number to eight. One of the carboxyl groups of the acid holds its H atom, which forms a hydrogen bond to a coordinated water mol-ecule. The other carboxyl group is deprotonated in half of the ligands and protonated in the other half, taking part in a strong O-H⋯O hydrogen bond disordered over an inversion centre. The stabil-ization of the crystal structure is further assisted by O-H⋯O and O-H⋯N hydrogen-bonding inter-actions involving the water mol-ecules and carboxyl-ate O atoms.

  2. Ice nucleation in internally mixed ammonium sulfate/dicarboxylic acid particles

    NASA Astrophysics Data System (ADS)

    Wise, Matthew E.; Garland, Rebecca M.; Tolbert, Margaret A.

    2004-10-01

    Recent studies have shown that tropospheric sulfate aerosols commonly contain 50% or more by mass organic species. The influence of these organics on the chemical and physical properties of sulfate aerosols is not fully established. Using an aerosol flow tube technique, we have determined ice nucleation temperatures for particles composed of ammonium sulfate and mixtures of ammonium sulfate with a series of dicarboxylic acids. A calibration curve was developed to allow us to convert the freezing temperatures to a saturation ratio required for ice nucleation. At levels detectable by our experimental technique we find that the freezing temperatures and critical ice saturation ratios of each system were identical, for a given water activity of the solution, even though the solutions contained varying fractions of inorganic and organic components. Further experiments showed that the freezing behavior of pure dicarboxylic acid particles was identical to that of the other systems studied if the water activity was identical. Although the apparent freezing temperatures reported here are substantially warmer than those predicted by the water activity based nucleation theory of T. Koop et al., we find that solution water activity defined the freezing conditions for the systems studied here.

  3. Laboratory study on the hygroscopic behavior of external and internal C2-C4 dicarboxylic acid-NaCl mixtures.

    PubMed

    Ma, Qingxin; Ma, Jinzhu; Liu, Chang; Lai, Chengyue; He, Hong

    2013-09-17

    Atmospheric aerosol is usually found to be a mixture of various inorganic and organic components in field measurements, whereas the effect of this mixing state on the hygroscopicity of aerosol particles has remained unknown. In this study, the hygroscopic behavior of mixtures of C2-C4 dicarboxylic acids and NaCl was investigated. For both externally and internally mixed malonic acid-NaCl and succinic acid-NaCl particles, correlation between water content and chemical composition was observed and the water content of these mixtures at relative humidity (RH) above 80% can be well predicted by the Zdanovskii-Stokes-Robinson (ZSR) method. In contrast, a nonlinear relation between the total water content of the mixtures and the water content of each chemical composition separately was found for oxalic acid-NaCl mixtures. Compared to the values predicted by the ZSR method, the dissolution of oxalic acid in external mixtures resulted in an increase in the total water content, whereas the formation of less hygroscopic disodium oxalate in internal mixtures led to a significant decrease in the total water content. Furthermore, we found that the hygroscopicity of the sodium dicarboxylate plays a critical role in determining the aqueous chemistry of dicarboxylic acid-NaCl mixtures during the humidifying and dehumidifying process. It was also found that the hydration of oxalic acid and the deliquescence of NaCl did not change in external oxalic acid-NaCl mixtures. The deliquescence relative humidity (DRHs) for both malonic acid and NaCl decreased in both external and internal mixtures. These results could help in understanding the conversion processes of dicarboxylic acids to dicarboxylate salts, as well as the substitution of Cl by oxalate in the atmosphere. It was demonstrated that the effect of coexisting components on the hygroscopic behavior of mixed aerosols should not be neglected.

  4. Mass spectrometric and theoretical studies on the decarboxylation of the anionic lithium complexes of the doubly deprotonated dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang

    2012-05-01

    On the basis of the tandem mass spectrometry (MS/MS) technique and density functional theory (DFT) calculations, we have studied the decarboxylation reactions of several anionic lithium complexes of the doubly deprotonated dicarboxylic acids, which include succinic acid, L-malic acid, L-mercaptosuccinic acid, L-aspartic acid and oxaloacetic acid, etc. Tandem mass spectrometry experiments indicate that the decarboxylation reactions of these complexes in the gas phase can all take place. DFT calculations show that the α-substituted groups in the dicarboxylic acids, such as sbnd OH, sbnd NH2 and sbnd SH can advance the decarboxylation of the corresponding anionic lithium complexes. Meanwhile, the decarboxylation generally happens at the carboxylate group that is away from the substituent. This opinion is also supported by the bond angle analyses of the carboxylate groups.

  5. Sutter's Mill dicarboxylic acids as possible tracers of parent-body alteration processes

    NASA Astrophysics Data System (ADS)

    Pizzarello, Sandra; Garvie, Laurence A. J.

    2014-11-01

    Dicarboxylic acids were searched for in three Sutter's Mill (SM) fragments (SM2 collected prerain, SM12, and SM41) and found to occur almost exclusively as linear species of 3- to 14-carbon long. Between these, concentrations were low, with measured quantities typically less than 10 nmole g-1 of meteorite and a maximum of 6.8 nmole g-1 of meteorite for suberic acid in SM12. The SM acids' molecular distribution is consistent with a nonbiological origin and differs from those of CMs, such as Murchison or Murray, and of some stones of the C2-ungrouped Tagish Lake meteorite, where they are abundant and varied. Powder X-ray diffraction of SM12 and SM41 show them to be dominated by clays/amorphous material, with lesser amounts of Fe-sulfides, magnetite, and calcite. Thermal gravimetric (TG) analysis shows mass losses up to 1000 °C of 11.4% (SM12) and 9.4% (SM41). These losses are low compared with other clay-rich carbonaceous chondrites, such as Murchison (14.5%) and Orgueil (21.1%). The TG data are indicative of partially dehydrated clays, in accordance with published work on SM2, for which mineralogical studies suggest asteroidal heating to around 500 °C. In view of these compositional traits and mineralogical features, it is suggested that the dicarboxylic acids observed in the SM fragments we analyzed likely represent a combination of molecular species original to the meteorite as well as secondary products formed during parent-body alteration processes, such as asteroidal heating.

  6. Environmental exposure to the plasticizer 1,2-cyclohexane dicarboxylic acid, diisononyl ester (DINCH) in US adults (2000—2012)

    PubMed Central

    Silva, Manori J.; Jia, Tao; Samandar, Ella; Preau, James L.; Calafat, Antonia M.

    2015-01-01

    1,2-Cyclohexane dicarboxylic acid, diisononyl ester (DINCH) is a complex mixture of nine carbon branched-chain isomers. It has been used in Europe since 2002 as a plasticizer to replace phthalates such as di(2-ethylhexyl)phthalate (DEHP) and diisononyl phthalate (DINP). Urinary concentrations of the oxidative metabolites of DINCH, namely cyclohexane-1,2-dicarboxylic acid-monocarboxy isooctyl ester (MCOCH); cyclohexane-1,2-dicarboxylic acid-mono(oxo-isononyl) ester (MONCH); and cyclohexane-1,2-dicarboxylic acid-mono(hydroxy-isononyl) ester (MHNCH), can potentially be used as DINCH exposure biomarkers. The concentrations of MCOCH, MONCH and MHNCH were measured by online solid phase extraction-high performance liquid chromatography-tandem mass spectrometry in urine collected in 2000 (n=114), 2001 (n=57), 2007 (n=23), 2009 (n=118), 2011 (n=94) and 2012 (n=121) from convenience groups of anonymous U.S. adult volunteers with no known DINCH exposure. None of the DINCH metabolites were detected in samples collected in 2000 and 2001. Only one sample collected in 2007 had measureable concentrations of DINCH metabolites. The detection rate for all three metabolites increased from 2007 to 2012. The presence of oxidative metabolites of DINCH in urine suggests that these oxidative metabolites can be used as DINCH biomarkers for exposure assessment even at environmental exposure levels. PMID:23777640

  7. Hydrogen bonded binary molecular adducts derived from exobidentate N-donor ligand with dicarboxylic acids: Acid⋯imidazole hydrogen-bonding interactions in neutral and ionic heterosynthons

    NASA Astrophysics Data System (ADS)

    Kathalikkattil, Amal Cherian; Damodaran, Subin; Bisht, Kamal Kumar; Suresh, Eringathodi

    2011-01-01

    Four new binary molecular compounds between a flexible exobidentate N-heterocycle and a series of dicarboxylic acids have been synthesized. The N-donor 1,4-bis(imidazol-1-ylmethyl)benzene (bix) was reacted with flexible and rigid dicarboxylic acids viz., cyclohexane-1,4-dicarboxylic acid (H 2chdc), naphthalene-1,4-dicarboxylic acid (H 2npdc) and 1H-pyrazole-3,5-dicarboxylic acid (H 2pzdc), generating four binary molecular complexes. X-ray crystallographic investigation of the molecular adducts revealed the primary intermolecular interactions carboxylic acid⋯amine (via O-H⋯N) as well as carboxylate⋯protonated amine (via N-H +⋯O -) within the binary compounds, generating layered and two-dimensional sheet type H-bonded networks involving secondary weak interactions (C-H⋯O) including the solvent of crystallization. Depending on the differences in p Ka values of the selected base/acid (Δp Ka), diverse H-bonded supramolecular assemblies could be premeditated. This study demonstrates the H-bonding interactions between imidazole/imidazolium cation and carboxylic acid/carboxylate anion in providing sufficient driving force for the directed assembly of binary molecular complexes. In the two-component solid form of hetero synthons involving bix and dicarboxylic acid, only H 2chdc exist as cocrystal with bix, while all the other three compounds crystallized exclusively as salt, in agreement with the Δp Ka values predicted for the formation of salts/cocrystals from the base and acid used in the synthesis of supramolecular solids.

  8. A review of dicarboxylic acids and related compounds in atmospheric aerosols: Molecular distributions, sources and transformation

    NASA Astrophysics Data System (ADS)

    Kawamura, Kimitaka; Bikkina, Srinivas

    2016-03-01

    This review aims to update our understanding on molecular distributions of water-soluble dicarboxylic acids and related compounds in atmospheric aerosols with a focus on their geographical variability, size distribution, sources and formation pathways. In general, molecular distributions of diacids in aerosols from the continental sites and over the open ocean waters are often characterized by the predominance of oxalic acid (C2) followed by malonic acid (C3) and/or succinic acid (C4), while those sampled over the polar regions often follow the order of C4 ≥ C2 and C3. The most abundant and ubiquitous diacid is oxalic acid, which is principally formed via atmospheric oxidation of its higher homologues of long chain diacids and other pollution-derived organic precursors (e.g., olefins and aromatic hydrocarbons). However, its occurrence in marine aerosols is mainly due to the transport from continental outflows (e.g., East Asian outflow during winter/spring to the North Pacific) and/or governed by photochemical/aqueous phase oxidation of biogenic unsaturated fatty acids (e.g., oleic acid) and isoprene emitted from the productive open ocean waters. The long-range atmospheric transport of pollutants from mid latitudes to the Arctic in dark winter facilitates to accumulate the reactants prior to their intense photochemical oxidation during springtime polar sunrise. Furthermore, the relative abundances of C2 in total diacid mass showed similar temporal trends with downward solar irradiation and ambient temperatures, suggesting the significance of atmospheric photochemical oxidation processing. Compound-specific isotopic analyses of oxalic acid showed the highest δ13C among diacids whereas azelaic acid showed the lowest value, corroborating the significance of atmospheric aging of oxalic acid. On the other hand, other diacids gave intermediate values between these two diacids, suggesting that aging of oxalic acid is associated with 13C enrichment.

  9. Effects of coating of dicarboxylic acids on the mass-mobility relationship of soot particles.

    PubMed

    Xue, Huaxin; Khalizov, Alexei F; Wang, Lin; Zheng, Jun; Zhang, Renyi

    2009-04-15

    Atandem differential mobility analyzer (TDMA) and a differential mobility analyzer-aerosol particle mass analyzer (DMA-APM) have been employed to study morphology and hygroscopicity of soot aerosol internally mixed with dicarboxylic acids. The effective densities, fractal dimensions, and dynamic shape factors of soot particles before and after coating with succinic and glutaric acids are determined. Coating of soot with succinic acid results in a significant increase in the particle mobility diameter, mass, and effective density, but these properties recover to their initial values once succinic acid is removed by heating, suggesting that no restructuring of the soot core occurs. This conclusion is also supported from the observation of similar fractal dimensions and dynamic shape factors for fresh and coated/heated soot aggregates. Also, no change is observed when succinic acid-coated aggregates are cycled through elevated relative humidity (5% to 90% to 5% RH) below the succinic acid deliquescence point. When soot is coated with glutaric acid, the particle mass increases, but the mobility diameter shrinks by 10-40%. Cycling the soot aerosol coated with glutaric acid through elevated relative humidity leads to an additional mass increase, indicating that condensed water remains within the coating even at low RH. The fractal dimension of soot particles increases after coating and remains high when glutaric acid is removed by heating. The dynamic shape factor of glutaric acid-coated and heated soot is significantly lower than that of fresh soot, suggesting a significant restructuring of the soot agglomerates by glutaric acid. The results imply that internal mixing of soot aerosol during atmospheric aging leads to changes in hygroscopicity, morphology, and effective density, which likely modify their effects on direct and indirect climate forcing and deposition in the human respiratory system.

  10. Activation of carboxyl group with cyanate: peptide bond formation from dicarboxylic acids.

    PubMed

    Danger, Grégoire; Charlot, Solenne; Boiteau, Laurent; Pascal, Robert

    2012-06-01

    The reaction of cyanate with C-terminal carboxyl groups of peptides in aqueous solution was considered as a potential pathway for the abiotic formation of peptide bonds under the condition of the primitive Earth. The catalytic effect of dicarboxylic acids on cyanate hydrolysis was definitely attributed to intramolecular nucleophilic catalysis by the observation of the 1H-NMR signal of succinic anhydride when reacting succinic acid with KOCN in aqueous solution (pH 2.2-5.5). The formation of amide bonds was noticed when adding amino acids or amino acid derivatives into the solution. The reaction of N-acyl aspartic acid derivatives was observed to proceed similarly and the scope of the cyanate-promoted reaction was analyzed from the standpoint of prebiotic peptide formation. The role of cyanate in activating peptide C-terminus constitutes a proof of principle that intramolecular reactions of adducts of peptides C-terminal carboxyl groups with activating agents represent a pathway for peptide activation in aqueous solution, the relevance of which is discussed in connexion with the issue of the emergence of homochirality.

  11. Effects of dicarboxylic acid coating on the optical properties of soot.

    PubMed

    Xue, Huaxin; Khalizov, Alexei F; Wang, Lin; Zheng, Jun; Zhang, Renyi

    2009-09-28

    Soot is a major component of atmospheric aerosols responsible for absorption of visible solar radiation. Internal mixing of soot with transparent materials can enhance its ability to absorb and scatter light, resulting in a larger role of soot in climate forcing. We have investigated the absorption and scattering of visible light (532 nm) by soot aerosol internally mixed with succinic and glutaric acids using a combination of a cavity ring-down spectrometer and an integrating nephelometer. The measurements were performed for flame-generated soot aerosol with well-characterized morphology and mixing state in the particle size range from 155 to 320 nm. Thin coatings of dicarboxylic acids on soot aggregates (with a mass fraction of 0.1-0.4) enhance significantly light scattering (up to 3.8 fold) and slightly light absorption (less than 1.2 fold). Cycling the coated soot aerosol through high relative humidity (humidified to 90% RH and then dried to 5% RH) promotes further increase in light absorption and scattering for soot internally mixed with glutaric acid, but not for soot mixed with succinic acid. The larger effect of glutaric acid on light absorption and scattering is caused by the irreversible restructuring of soot aggregates induced by the coating material. Our results indicate that the enhancement in the optical properties of soot by transparent coatings is strongly related to the ability of the coating materials to change the morphology of soot aggregates.

  12. Summer and winter variations of dicarboxylic acids, fatty acids and benzoic acid in PM2.5 in Pearl Delta River Region, China

    NASA Astrophysics Data System (ADS)

    Ho, K. F.; Ho, S. S. H.; Lee, S. C.; Kawamura, K.; Zou, S. C.; Cao, J. J.; Xu, H. M.

    2010-11-01

    Ground-based PM2.5 samples collected in Pearl River Delta (PRD) region during winter and summer (from 14 December 2006 to 28 January 2007 in winter and from 4 July 2007 to 9 August 2007 in summer) were analyzed for 30 water-soluble organic species, including dicarboxylic acids, ketocarboxylic acids and dicarbonyls, nine fatty acids, and benzoic acid. Molecular distributions of dicarboxylic acids demonstrated that oxalic acid (C2) was the most abundant species followed by phthalic acid (Ph) in PRD region. The concentrations of total dicarboxylic acids ranged from 99 to 1340 ng m-3, with an average of 438 ± 267 ng m-3 in PRD. The concentrations of total ketocarboxylic acids ranged from 0.6 to 207 ng m-3 (43 ± 48 ng m-3 on average) while the concentrations of total α-dicarbonyls, including glyoxal and methylglyoxal, ranged from 0.2 to 89 ng m-3, with an average of 11 ± 18 ng m-3 in PRD. The total quantified water-soluble organic carbon (TQWOC) accounted for 3.4 ± 2.2% of OC and 14.3 ± 10.3% of water-soluble OC (WSOC). Hexadecanoic acid (C16:0), octadecanoic acid (C18:0) and oleic acid (C18:1) are the three most abundant fatty acids in PRD. The distributions of fatty acids are characterized by a strong even carbon number predominance with a maximum (Cmax) at hexadecanoic acid (C16:0). Ratio of C18:1 to C18:0 acts as an indicator for aerosol aging. In PRD, an average of C18:1/C18:0 ratio was 0.53 ± 0.39, suggesting an enhanced photochemical degradation of unsaturated fatty acid. Seasonal variations of the pollutant concentrations were found in the four sampling cities. Higher concentrations of TQWOC were observed in winter (544 ng m-3) than in summer (318 ng m-3). However, the abundances of TQWOC in OC mass were higher in summer (1.8-12.4%, 5.4% on average) than in winter (1.1-5.7, 2.6% on average), being consistent with enhanced secondary production of dicarboxylic acids in warmer weather. Spatial variations of water-soluble dicarboxylic acids were characterized

  13. Versatile and sustainable synthesis of cyclic imides from dicarboxylic acids and amines by Nb2O5 as a base-tolerant heterogeneous Lewis acid catalyst.

    PubMed

    Ali, Md Ayub; Siddiki, S M A Hakim; Kon, Kenichi; Hasegawa, Junya; Shimizu, Ken-Ichi

    2014-10-27

    Catalytic condensation of dicarboxylics acid and amines without excess amount of activating reagents is the most atom-efficient but unprecedented synthetic method of cyclic imides. Here we present the first general catalytic method, proceeding selectively and efficiently in the presence of a commercial Nb2 O5 as a reusable and base-tolerant heterogeneous Lewis acid catalyst. The method is effective for the direct synthesis of pharmaceutically or industrially important cyclic imides, such as phensuximide, N-hydroxyphthalimide (NHPI), and unsubstituted cyclic imides from dicarboxylic acid or anhydrides with amines, hydroxylamine, or ammonia.

  14. X-ray studies on crystalline complexes involving amino acids and peptides. XLII. Adipic acid complexes of L- and DL-arginine and supramolecular association in arginine-dicarboxylic acid complexes.

    PubMed

    Roy, Siddhartha; Singh, Desh Deepak; Vijayan, M

    2005-02-01

    The adipic acid complexes of DL-arginine and L-arginine are made up of zwitterionic, singularly positively charged arginium ions and doubly negatively charged adipate ions, with a 2:1 stoichiometry. One of the two crystallographically independent arginium ions in the L-arginine complex has a conformation hitherto unobserved in crystal structures containing the amino acid. In the present study the structural data on arginine complexes of saturated dicarboxylic acids with 0-5 C atoms separating the two carboxyl functions are given. In terms of molecular aggregation, formic and acetic acid complexes behave in a similar way to those involving fairly long carboxylic acids such as adipic acid. By and large, the supramolecular assembly in complexes involving dicarboxylic acids with 3 or more C atoms separating the carboxyl groups (glutaric, adipic and pimelic acids), and those involving formic and acetic acids, have common features. The aggregation patterns in complexes involving oxalic, malonic and maleic acids do not share striking features among themselves (except for the mode of hydrogen-bonded dimerization of arginium ions) or with those involving larger dicarboxylic acids. Complexes of succinic acid, the shortest linear dicarboxylic acid, share features with those involving shorter as well as longer dicarboxylic acids. The difference in the behaviour of long and short dicarboxylic acids and the ambiguous behaviour of succinic acid can be broadly related to their lengths.

  15. Piezoelectric crystal microbalance measurements of enthalpy of sublimation of C2-C9 dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Dirri, F.; Palomba, E.; Longobardo, A.; Zampetti, E.

    2016-02-01

    We present here a novel experimental set-up that is able to measure the enthalpy of sublimation of a given compound by means of piezoelectric crystal microbalances (PCMs). The PCM sensors have already been used for space measurements, such as for the detection of organic and non-organic volatile species and refractory materials in planetary environments. In Earth atmospherics applications, PCMs can be also used to obtain some physical-chemical processes concerning the volatile organic compounds (VOCs) present in atmospheric environments. The experimental set-up has been developed and tested on dicarboxylic acids. In this work, a temperature-controlled effusion cell was used to sublimate VOC, creating a molecular flux that was collimated onto a cold PCM. The VOC recondensed onto the PCM quartz crystal, allowing the determination of the deposition rate. From the measurements of deposition rates, it has been possible to infer the enthalpy of sublimation of adipic acid, i.e. ΔHsub : 141.6 ± 0.8 kJ mol-1, succinic acid, i.e. 113.3 ± 1.3 kJ mol-1, oxalic acid, i.e. 62.5 ± 3.1 kJ mol-1, and azelaic acid, i.e. 124.2 ± 1.2 kJ mol-1. The results obtained show an accuracy of 1 % for succinic, adipic, and azelaic acid and within 5 % for oxalic acid and are in very good agreement with previous works (within 6 % for adipic, succinic, and oxalic acid and within 11 % or larger for azelaic acid).

  16. Synthesis, structure and properties of zinc(II) coordination polymers with 9H-carbazole-2,7-dicarboxylic acid

    NASA Astrophysics Data System (ADS)

    Yi, Xiu-Chun; Xi, Fu-Gui; Wang, Kun; Su, Zhao; Gao, En-Qing

    2013-10-01

    From a new dicarboxylate ligand, 9H-carbazole-2,7-dicarboxylic acid (2,7-H2CDC), three Zn(II) metal-organic frameworks were synthesized in the absence or presence of ditopic N-donor ligands. They are formulated as [Zn5(μ3-OH)2(2,7-CDC)4(DEF)2] (1) (DEF=N,N-diethylformamide), [Zn2(2,7-CDC)2(DABCO)(H2O)]·5DMF·H2O (2) (DABCO=1-diaza-bicyclo[2.2.2]octane, DMF=N,N-dimethylformamide), and [Zn2(2,7-CDC)2(bpea)]·3DMA·2 H2O (3) (bpea=1,2-bis(4-pyridyl)ethylane, DMA=N,N-dimethylacetamide). Compounds 1 and 3 display the 3D pcu frameworks. In 1 the unusual pentanuclear [Zn5(μ3-OH)2(COO)8] secondary building units (SBUs) are linked by dicarboxylate ligands. Differently, in 3 the well-known paddle-wheel [Zn2(COO)4] SBUs are linked by dicarboxylate and dipyridyl ligands. Compound 2 shows the rare self-catenated 3D alb-3,6-C2/c net topology based on the dinuclear paddle-wheel SBU and a mononuclear unit. The stability and fluorescent properties of the compounds have been studied.

  17. Synthesis, structure and properties of zinc(II) coordination polymers with 9H-carbazole-2,7-dicarboxylic acid

    SciTech Connect

    Yi, Xiu-Chun; Xi, Fu-Gui; Wang, Kun; Su, Zhao; Gao, En-Qing

    2013-10-15

    From a new dicarboxylate ligand, 9H-carbazole-2,7-dicarboxylic acid (2,7-H{sub 2}CDC), three Zn(II) metal-organic frameworks were synthesized in the absence or presence of ditopic N-donor ligands. They are formulated as [Zn{sub 5}(μ{sub 3}-OH){sub 2}(2,7-CDC){sub 4}(DEF){sub 2}] (1) (DEF=N,N-diethylformamide), [Zn{sub 2}(2,7-CDC){sub 2}(DABCO)(H{sub 2}O)]·5DMF·H{sub 2}O (2) (DABCO=1-diaza-bicyclo[2.2.2]octane, DMF=N,N-dimethylformamide), and [Zn{sub 2}(2,7-CDC){sub 2}(bpea)]·3DMA·2 H{sub 2}O (3) (bpea=1,2-bis(4-pyridyl)ethylane, DMA=N,N-dimethylacetamide). Compounds 1 and 3 display the 3D pcu frameworks. In 1 the unusual pentanuclear [Zn{sub 5}(μ{sub 3}-OH){sub 2}(COO){sub 8}] secondary building units (SBUs) are linked by dicarboxylate ligands. Differently, in 3 the well-known paddle–wheel [Zn{sub 2}(COO){sub 4}] SBUs are linked by dicarboxylate and dipyridyl ligands. Compound 2 shows the rare self-catenated 3D alb-3,6-C2/c net topology based on the dinuclear paddle–wheel SBU and a mononuclear unit. The stability and fluorescent properties of the compounds have been studied. - Graphical abstract: A new dicarboxylate ligand, 9H-carbazole-2,7-dicarboxylic acid, was used to construct Zn(II) metal-organic frameworks, including a novel self-catenated network with the rare 3D alb-3,6-C2/c net and two pcu-type networks based on an unprecedented pentanuclear clusters and the common paddle–wheel units. The compounds show blue fluorescent properties. Display Omitted - Highlights: • MOFs with a new carbazole-based dicarboxylate ligand. • New pentanuclear [Zn{sub 5}(μ{sub 3}-OH){sub 2}(COO){sub 8}] secondary building unit. • The rare self-catenated 3D alb-3,6-C2/c net.

  18. Charge transport through dicarboxylic-acid-terminated alkanes bound to graphene-gold nanogap electrodes

    NASA Astrophysics Data System (ADS)

    Liu, Longlong; Zhang, Qian; Tao, Shuhui; Zhao, Cezhou; Almutib, Eman; Al-Galiby, Qusiy; Bailey, Steven W. D.; Grace, Iain; Lambert, Colin J.; Du, Jun; Yang, Li

    2016-07-01

    Graphene-based electrodes are attractive for single-molecule electronics due to their high stability and conductivity and reduced screening compared with metals. In this paper, we use the STM-based matrix isolation I(s) method to measure the performance of graphene in single-molecule junctions with one graphene electrode and one gold electrode. By measuring the length dependence of the electrical conductance of dicarboxylic-acid-terminated alkanes, we find that the transport is consistent with phase-coherent tunneling, but with an attenuation factor of βN = 0.69 per methyl unit, which is lower than the value measured for Au-molecule-Au junctions. Comparison with density-functional-theory calculations of electron transport through graphene-molecule-Au junctions and Au-molecule-Au junctions reveals that this difference is due to the difference in Fermi energies of the two types of junction, relative to the frontier orbitals of the molecules. For most molecules, their electrical conductance in graphene-molecule-Au junctions is higher than that in Au-molecule-Au junctions, which suggests that graphene offers superior electrode performance, when utilizing carboxylic acid anchor groups.Graphene-based electrodes are attractive for single-molecule electronics due to their high stability and conductivity and reduced screening compared with metals. In this paper, we use the STM-based matrix isolation I(s) method to measure the performance of graphene in single-molecule junctions with one graphene electrode and one gold electrode. By measuring the length dependence of the electrical conductance of dicarboxylic-acid-terminated alkanes, we find that the transport is consistent with phase-coherent tunneling, but with an attenuation factor of βN = 0.69 per methyl unit, which is lower than the value measured for Au-molecule-Au junctions. Comparison with density-functional-theory calculations of electron transport through graphene-molecule-Au junctions and Au

  19. A Dicarboxylic Fatty Acid Derivative of Paclitaxel for Albumin Assisted Drug Delivery

    PubMed Central

    Hackett, Michael J.; Joolakanti, Shyamsunder; Hartranft, Megan E.; Guley, Patrick C.; Cho, Moo J.

    2013-01-01

    Paclitaxel is a potent chemotherapy for many cancers but it suffers from very poor solubility. Consequently the TAXOL formulation uses copious amounts of the surfactant Cremophor EL to solubilize the drug for injection resulting in severe hypersensitivity and neutropenia. In contrast to Cremophor EL, presented is a way to solubilize paclitaxel (PTX) by conjugation of a dicarboxylic fatty acid for specific binding to the ubiquitous protein, serum albumin. The conjugation chemistry was simplified to a single step using the activated anhydride form of 3-pentadecylglutaric (PDG) acid which is reactive to a variety of nucleophiles. The PDG derivative is less cytotoxic than the parent compound and was found to slowly hydrolyze to PTX (~5% over 72 h) in serum, tumor cytosol, and tumor tissue homogenate. When injected intravenously to tumor bearing mice, [3H]-PTX in the TAXOL formulation was cleared rapidly with a half-life of 7 hours. In the case of the PDG derivative of PTX, the drug is quickly distributed and approximately 20% of the injected dose remained in the vasculature experiencing a 23-h half-life. These improvements from modifying PTX with the PDG fatty acid present the opportunity for PDG to become a generic modification for the improvement of many therapeutics. PMID:22674061

  20. Spatial separation of individual substances in effloresced crystals of ternary ammonium sulphate/dicarboxylic acid/water aerosols.

    PubMed

    Treuel, Lennart; Sandmann, Alice; Zellner, Reinhard

    2011-04-18

    This work examines the crystals resulting from the efflorescence of internally mixed aqueous aerosols comprising ammonium sulphate and different dicarboxylic acids. Most studies on the deliquescence of aerosols use previously effloresced aerosols in their experiments. However, during efflorescence a highly supersaturated solution crystallises in a kinetically controlled way unlike the case of thermodynamically controlled crystallisation. Herein the distribution of individual substances within the effloresced crystals is investigated using Raman scanning experiments. The data presented show an intriguingly complex behaviour of these ternary and quarternary aerosols. A spatial separation of substances in the crystals resulting from the efflorescence of previously internally mixed ternary salt/dicarboxylic acid/water aerosol droplets is demonstrated and mechanistic aspects are discussed.

  1. Measuring enthalpy of sublimation of volatiles by means of micro-thermogravimetry: the case of Dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Dirri, F.; Longobardo, A.; Palomba, E.; Zampetti, E.; Biondi, D.; Boccaccini, A.; Saggin, B.; Bearzotti, A.; Macagnano, A.

    2013-09-01

    VISTA (Volatile In Situ Thermogravimetry Analyser) is a thermogravimeter currently under study for the proposed mission MarcoPolo-R [1,2]. In the framework of this project, we developed a set-up to measure the enthalpy of sublimation ΔH of three dicarboxylic acids, i.e. adipic, succinic and oxalic. The obtained results are in good agreement with literature, and this demonstrates the capability of our device to perform this kind of measurements.

  2. Temperature dependences of saturated vapor pressure and the enthalpy of vaporization of n-pentyl esters of dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Portnova, S. V.; Krasnykh, E. L.; Levanova, S. V.

    2016-05-01

    The saturated vapor pressures and enthalpies of vaporization of n-pentyl esters of linear C2-C6 dicarboxylic acids are determined by the transpiration method in the temperature range of 309.2-361.2 K. The dependences of enthalpies of vaporization on the number of carbon atoms in the molecule and on the retention indices have been determined. The predictive capabilities of the existing calculation schemes for estimation of enthalpy of vaporization of the studied compounds have been analyzed.

  3. catena-Poly[[diaqua­rubidium(I)](μ2-3-carboxy­pyrazine-2-carboxyl­ato)(μ2-pyrazine-2,3-dicarboxylic acid)

    PubMed Central

    Tombul, Mustafa; Guven, Kutalmis

    2009-01-01

    The structural unit of the title compound, [Rb(C6H3N2O4)(C6H4N2O4)(H2O)2]n, consists of one rubidium cation, one hydrogen pyrazine-2,3-dicarboxyl­ate anion, one pyrazine-2,3-dicarboxylic acid mol­ecule and two water mol­ecules. This formulation is repeated twice in the asymmetric unit as the rubidium cation lies on an inversion centre. Each anion or acid mol­ecule is linked to two rubidium cations, while the rubidium cation has close contacts to four symmetry-equivalent organic ligands, with two different coordination modes towards this cation. In addition, each rubidium cation is coordinated by two water O atoms, raising the coordination number to eight. One of the carboxyl groups of the acid holds its H atom, which forms a hydrogen bond to a coordinated water mol­ecule. The other carboxyl group is deprotonated in half of the ligands and protonated in the other half, taking part in a strong O—H⋯O hydrogen bond disordered over an inversion centre. The stabil­ization of the crystal structure is further assisted by O—H⋯O and O—H⋯N hydrogen-bonding inter­actions involving the water mol­ecules and carboxyl­ate O atoms. PMID:21581808

  4. Poly[diaqua(μ2-3-carboxypyrazine-2-carboxylato)(μ2-pyrazine-2,3-dicarboxylic acid)potassium(I)

    PubMed Central

    Tombul, Mustafa; Güven, Kutalmis; Svoboda, Ingrid

    2008-01-01

    The structural unit of the title compound, [K(C6H3N2O4)(C6H4N2O4)(H2O)2]n, consists of one potassium cation, one hydrogen pyrazine-2,3-dicarboxyl­ate anion, one pyrazine-2,3-dicarboxylic acid mol­ecule and two water mol­ecules; this is twice the asymmetric unit, since the potassium cation lies on an inversion centre. Each anion or acid mol­ecule is linked to two potassium cations, while the potassium cation has contacts to four symmetry-equivalent organic ligands, with two different coordination modes towards this cation. In addition, each potassium cation is coordinated by two water O atoms, raising the coordination number to eight. One of the carboxyl groups of the acid retains its H atom, which forms a hydrogen bond to a coordinated water mol­ecule. The other carboxyl group is deprotonated in half of the ligands and protonated in the other half, taking part in a strong O—H⋯O hydrogen bond disordered over an inversion centre. The stabilization of the crystal structure is further assisted by O—H⋯O and O—H⋯N hydrogen bonds in which water acts as the donor. PMID:21200587

  5. Effect of aliphatic, monocarboxylic, dicarboxylic, heterocyclic and sulphur-containing amino acids on Leishmania spp. chemotaxis.

    PubMed

    Diaz, E; Zacarias, A K; Pérez, S; Vanegas, O; Köhidai, L; Padrón-Nieves, M; Ponte-Sucre, A

    2015-11-01

    In the sand-fly mid gut, Leishmania promastigotes are exposed to acute changes in nutrients, e.g. amino acids (AAs). These metabolites are the main energy sources for the parasite, crucial for its differentiation and motility. We analysed the migratory behaviour and morphological changes produced by aliphatic, monocarboxylic, dicarboxylic, heterocyclic and sulphur-containing AAs in Leishmania amazonensis and Leishmania braziliensis and demonstrated that L-methionine (10-12 m), L-tryptophan (10-11 m), L-glutamine and L-glutamic acid (10-6 m), induced positive chemotactic responses, while L-alanine (10-7 m), L-methionine (10-11 and 10-7 m), L-tryptophan (10-11 m), L-glutamine (10-12 m) and L-glutamic acid (10-9 m) induced negative chemotactic responses. L-proline and L-cysteine did not change the migratory potential of Leishmania. The flagellum length of L. braziliensis, but not of L. amazonensis, decreased when incubated in hyperosmotic conditions. However, chemo-repellent concentrations of L-alanine (Hypo-/hyper-osmotic conditions) and L-glutamic acid (hypo-osmotic conditions) decreased L. braziliensis flagellum length and L-methionine (10-11 m, hypo-/hyper-osmotic conditions) decreased L. amazonensis flagellum length. This chemotactic responsiveness suggests that Leishmania discriminate between slight concentration differences of small and structurally closely related molecules and indicates that besides their metabolic effects, AAs play key roles linked to sensory mechanisms that might determine the parasite's behaviour.

  6. Chemical modification of zinc hydroxide nitrate and Zn-Al-layered double hydroxide with dicarboxylic acids.

    PubMed

    Arizaga, Gregorio Guadalupe Carbajal; Mangrich, Antonio Salvio; da Costa Gardolinski, José Eduardo Ferreira; Wypych, Fernando

    2008-04-01

    A zinc hydroxide nitrate (ZHN), Zn5(OH)8(NO3)2.2H2O, and a layered double hydroxide (LDH), Zn/Al-NO3 were doped with 0.2 mol% of Cu2+ during alkaline chemical precipitation. Both compounds were intercalated with adipate ((-)OOC(CH2)4COO(-)), azelate ((-)OOC(CH2)7COO(-)), and benzoate (C6H5COO(-)) ions through ion exchange reactions. Solid state 13C nuclear magnetic resonance spectroscopy showed only one signal of carboxylic carbon for adipate and azelate intercalated into LDH, indicating that the carboxylic ends of both acids were equivalent, whereas the signal split when the intercalation was into the ZHN matrix. The electron paramagnetic resonance (EPR) spectrum of copper in octahedral cation sites of LDH layers showed a Hamiltonian parameter ratio g ||/A ||=170 cm and, after intercalation of adipate, the change was not significant: g ||/A ||=174 cm. This result indicates that the carboxylate ions did not coordinate with copper centers. Nonetheless, the intercalation of azelate increased the ratio to g ||/A ||=194 cm, similar to the spectra of ZHN modified with adipate, g ||/A ||=199 cm, and azelate, g ||/A ||=183 and 190 cm, which are associated with the coordination of copper by weak carboxylate anion ligands. Copper occupies octahedral or tetrahedral sites in ZHN layers, and the EPR spectra indicate that the dicarboxylate anions reacted preferentially with octahedral sites, whereas benzoate reacted with both sites.

  7. Isolation of dicarboxylic acid- and glucose-binding proteins from Pseudomonas aeruginosa.

    PubMed Central

    Stinson, M W; Cohen, M A; Merrick, J M

    1976-01-01

    Inducible binding proteins for C4-dicarboxylic acids (DBP) and glucose (GBP) were isolated from Pseudomonas aeruginosa by extraction of exponential-phase cells with 0.2 M MgC12 (pH 8.5) and by an osmotic shock procedure without affecting cell viability. DBP synthesis was induced by growth on aspartate, alpha-ketoglutarate, succinate, fumarate, malate, and malonate but not by growth on acetate, citrate, pyruvate, or glucose. Binding of succinate by DBP was competitively inhibited by 10-fold concentrations of fumarate and malate but not by a variety of related substances. GBP synthesis and transport of methyl alpha-glucoside by whole cells were induced by growth on glucose or pyruvate plus galactose, 2-deoxyglucose, or methyl alpha-glucoside but not by growth on gluconate, succinate, acetate, or pyruvate. The binding of radioactive glucose by GBP was significantly inhibited by 10-fold concentrations of glucose, galactose, and glucose-1-phosphate but not by the other carbohydrates tested. The binding of glucose by GBP or succinate by DBP did not result in any chemical alteration of the substrates. PMID:824281

  8. Creatininium bis­(pyridine-2,6-dicarboxyl­ato)chromate(III) pyridine-2,6-dicarboxylic acid hexa­hydrate

    PubMed Central

    Aghabozorg, Hossein; Derikvand, Zohreh; Olmstead, Marilyn M.; Attar Gharamaleki, Jafar

    2008-01-01

    The title compound, (C4H8N3O)[Cr(C7H3NO4)2]·C7H5NO4·6H2O, was obtained by the reaction of Cr(NO3)3·9H2O with pyridine-2,6-dicarboxylic acid (pydcH2) and creatinine (creat) in aqueous solution (molar ratio 1:2:2). The cation is a protonated creatinine (creatH+) while the anion is a bis-pydc2− CrIII complex. The CrIII is coordinated by four oxygen and two nitro­gen atoms of two (pydc)2– groups and has a disorted octa­hedral coordination environment. The structure also contains a neutral mol­ecule of pydcH2 that is hydrogen bonded to the creatH+ and six mol­ecules of water. Extensive inter­molecular inter­actions, including seventeen classical hydrogen bonds, two weak C—H⋯O bonds, and C—O⋯π stacking inter­actions, with O⋯centroid distances of 3.211 (13) and 3.300 (12) Å, connect the various components in the crystal structure. PMID:21200994

  9. Quantitative analysis of glycerol in dicarboxylic acid-rich cutins provides insights into Arabidopsis cutin structure.

    PubMed

    Yang, Weili; Pollard, Mike; Li-Beisson, Yonghua; Ohlrogge, John

    2016-10-01

    Cutin is an extracellular lipid polymer that contributes to protective cuticle barrier functions against biotic and abiotic stresses in land plants. Glycerol has been reported as a component of cutin, contributing up to 14% by weight of total released monomers. Previous studies using partial hydrolysis of cuticle-enriched preparations established the presence of oligomers with glycerol-aliphatic ester links. Furthermore, glycerol-3-phosphate 2-O-acyltransferases (sn-2-GPATs) are essential for cutin biosynthesis. However, precise roles of glycerol in cutin assembly and structure remain uncertain. Here, a stable isotope-dilution assay was developed for the quantitative analysis of glycerol by GC/MS of triacetin with simultaneous determination of aliphatic monomers. To provide clues about the role of glycerol in dicarboxylic acid (DCA)-rich cutins, this methodology was applied to compare wild-type (WT) Arabidopsis cutin with a series of mutants that are defective in cutin synthesis. The molar ratio of glycerol to total DCAs in WT cutins was 2:1. Even when allowing for a small additional contribution from hydroxy fatty acids, this is a substantially higher glycerol to aliphatic monomer ratio than previously reported for any cutin. Glycerol content was strongly reduced in both stem and leaf cutin from all Arabidopsis mutants analyzed (gpat4/gpat8, att1-2 and lacs2-3). In addition, the molar reduction of glycerol was proportional to the molar reduction of total DCAs. These results suggest "glycerol-DCA-glycerol" may be the dominant motif in DCA-rich cutins. The ramifications and caveats for this hypothesis are presented.

  10. Carboxylic and dicarboxylic acids extracted from crushed magnesium oxide single crystals

    NASA Technical Reports Server (NTRS)

    Freund, F.; Gupta, A. D.; Kumar, D.

    1999-01-01

    Carboxylic and dicarboxylic acids (glycolic, oxalic, malonic and succinic) have been extracted with tetrahydrofuran (THF) and H2O from large synthetic MgO crystals, crushed to a medium fine powder. The extracts were characterized by infrared spectroscopy and 1H-NMR. The THF extracts were derivatized with tert-butyldimethylsilyl (t-BDMS) for GC-MS analysis. A single crystal separated from the extract was used for an x-ray structure analysis, giving the monoclinic unit cell, space group P21/c with ao = 5.543 A, bo = 8.845 A, co = 5.086 A, and beta = 91.9 degrees, consistent with beta-succinic acid, HOOC(CH2)COOH. The amount of extracted acids is estimated to be of the order of 0.1 to 0.5 mg g-1 MgO. The MgO crystals from which these organic acids were extracted grew from the 2860 degrees C hot melt, saturated with CO/CO2 and H2O, thereby incorporating small amounts of the gaseous components to form a solid solution (ss) with MgO. Upon cooling, the ss becomes supersaturated, causing solute carbon and other solute species to segregate not only to the surface but also internally, to dislocations and subgrain boundaries. The organic acids extracted from the MgO crystals after crushing appear to derive from these segregated solutes that formed C-C, C-H and C-O bonds along dislocations and other defects in the MgO structure, leading to entities that can generically be described as (HxCyOz)n-. The processes underlying the formation of these precursors are fundamental in nature and expected to be operational in any minerals, preferentially those with dense structures, that crystallized in H2O-CO2-laden environments. This opens the possibility that common magmatic and metamorphic rocks when weathering at the surface of a tectonically active planet like Earth may be an important source of abiogenically formed complex organic compounds.

  11. Carboxylic and Dicarboxylic Acids Extracted from Crushed Magnesium Oxide Single Crystals

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann; Gupta, Alka D.; Kumar, Devendra; DeVincenzi, Donald (Technical Monitor)

    1998-01-01

    Carboxylic and dicarboxylic acids (glycolic, oxalic, malonic and succinic) have been extracted with tetrahydrofuran (THE) and H2O from large synthetic MgO crystals, crushed to a medium fine powder. The extracts were characterized by infrared spectroscopy and (sup 1)H-NMR (Nuclear Magnetic Resonance). The THF extracts were derivatized with tert-butyldimethylsilyl (t-BDMS) for GC-MS (Gas Chromatography - Mass Spectroscopy) analysis. A single crystal separated from the extract was used for an x-ray structure analysis, giving the monoclinic unit cell, space group P2(sub 1)/c with a(sub o) = 5.543 A, b(sub o) = 8.845 A, c(sub o) = 5.086 A, and beta = 91.9 degrees, consistent with beta-succinic acid, HOOC(CH2)COOH. The amount of extracted acids is estimated to be of the order of 0.1 to 0.5 mg/g MgO. The MgO crystals from which these organic acids were extracted grew from the 2360 C hot melt, saturated with CO/CO2 and H2O, thereby incorporating small amounts of the gaseous components to form a solid solution (ss) with MgO. Upon cooling, the ss becomes supersaturated, causing solute carbon and other solute species to segregate not only to the surface but also internally, to dislocations and subgrain boundaries. The organic acids extracted from the MgO crystals after crushing appear to derive from these segregated solutes that formed C-C, C-H, and C-O bonds along dislocations and other defects in the MgO structure, leading to entities that can generically be described as (HxCyOz)(sup n-). The processes underlying the formation of these precursors are fundamental in nature and expected to be operational in any minerals, preferentially those with dense structures, that crystallized in H2O-CO2-laden environments. This opens the possibility that common magmatic and metamorphic rocks when weathering at the surface of a tectonically active planet like Earth may be an important source of abiogenically formed complex organic compounds.

  12. Summer and winter variations of dicarboxylic acids, fatty acids and benzoic acid in PM2.5 in Pearl Delta River Region, China

    NASA Astrophysics Data System (ADS)

    Ho, K. F.; Ho, S. S. H.; Lee, S. C.; Kawamura, K.; Zou, S. C.; Cao, J. J.; Xu, H. M.

    2011-03-01

    Ground-based PM2.5 samples collected at four different sites in Pearl River Delta region (PRD) during winter and summer (from 14 December 2006 to 28 January 2007 in winter and from 4 July to 9 August 2007 in summer) were analyzed for 30 water-soluble organic species, including dicarboxylic acids, ketocarboxylic acids and dicarbonyls, nine fatty acids, and benzoic acid. Molecular distributions of dicarboxylic acids demonstrated that oxalic acid (C2) was the most abundant species followed by phthalic acid (Ph) in PRD region. The concentrations of total dicarboxylic acids ranged from 99 to 1340 ng m-3, with an average of 438 ± 267 ng m-3 in PRD. The concentrations of total ketocarboxylic acids ranged from 0.6 to 207 ng m-3 (43 ± 48 ng m-3 on average) while the concentrations of total α-dicarbonyls, including glyoxal and methylglyoxal, ranged from 0.2 to 89 ng m-3, with an average of 11 ± 18 ng m-3 in PRD. The total quantified water-soluble compounds (TQWOC) (organic carbon) accounted for 3.4 ± 2.2% of OC and 14.3 ± 10.3% of water-soluble OC (WSOC). Hexadecanoic acid (C16:0), octadecanoic acid (C18:0) and oleic acid (C18:1) were the three most abundant fatty acids in PRD. The distributions of fatty acids were characterized by a strong even carbon number predominance with a maximum (Cmax) at hexadecanoic acid (C16:0). Ratio of C18:1 to C18:0 acts as an indicator for aerosol aging. In PRD, an average of C18:1/C18:0 ratio was 0.53 ± 0.39, suggesting an enhanced photochemical degradation of unsaturated fatty acid. Moreover, the concentrations of benzoic acid ranged from 84 to 306 ng m-3, (165 ± 48 ng m-3 on average), which can be emitted as primary pollutant from motor vehicles exhaust, or formed from photochemical degradation of aromatic hydrocarbons. Seasonal variations of the organic specie concentrations were found in the four sampling cities. Higher concentrations of TQWOC were observed in winter (598 ± 321 ng m-3) than in summer (372 ± 215 ng m-3). However

  13. The evolution of Jen3 proteins and their role in dicarboxylic acid transport in Yarrowia

    PubMed Central

    Dulermo, Rémi; Gamboa-Meléndez, Heber; Michely, Stéphanie; Thevenieau, France; Neuvéglise, Cécile; Nicaud, Jean-Marc

    2015-01-01

    Jen proteins in yeast are involved in the uptake of mono/dicarboxylic acids. The Jen1 subfamily transports lactate and pyruvate, while the Jen2 subfamily transports fumarate, malate, and succinate. Yarrowia lipolytica has six JEN genes: YALI0B19470g, YALI0C15488g, YALI0C21406g, YALI0D20108g, YALI0D24607g, and YALI0E32901g. Through phylogenetic analyses, we found that these genes represent a new subfamily, Jen3 and that these three Jen subfamilies derivate from three putative ancestral genes. Reverse transcription-PCR. revealed that only four YLJEN genes are expressed and they are upregulated in the presence of lactate, pyruvate, fumarate, malate, and/or succinate, suggesting that they are able to transport these substrates. Analysis of deletion mutant strains revealed that Jen3 subfamily proteins transport fumarate, malate, and succinate. We found evidence that YALI0C15488 encodes the main transporter because its deletion was sufficient to strongly reduce or suppress growth in media containing fumarate, malate, or succinate. It appears that the other YLJEN genes play a minor role, with the exception of YALI0E32901g, which is important for malate uptake. However, the overexpression of each YLJEN gene in the sextuple-deletion mutant strain ΔYLjen1-6 revealed that all six genes are functional and have evolved to transport different substrates with varying degrees of efficacy. In addition, we found that YALI0E32901p transported succinate more efficiently in the presence of lactate or fumarate. PMID:25515252

  14. Method of increasing conversion of a fatty acid to its corresponding dicarboxylic acid

    DOEpatents

    Craft, David L.; Wilson, C. Ron; Eirich, Dudley; Zhang, Yeyan

    2004-09-14

    A nucleic acid sequence including a CYP promoter operably linked to nucleic acid encoding a heterologous protein is provided to increase transcription of the nucleic acid. Expression vectors and host cells containing the nucleic acid sequence are also provided. The methods and compositions described herein are especially useful in the production of polycarboxylic acids by yeast cells.

  15. Synthesis, properties and applications of biodegradable polymers derived from diols and dicarboxylic acids: from polyesters to poly(ester amide)s.

    PubMed

    Díaz, Angélica; Katsarava, Ramaz; Puiggalí, Jordi

    2014-04-25

    Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

  16. Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amide)s

    PubMed Central

    Díaz, Angélica; Katsarava, Ramaz; Puiggalí, Jordi

    2014-01-01

    Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed. PMID:24776758

  17. Development of a Δ9-Tetrahydrocannabinol Amino Acid-Dicarboxylate Prodrug With Improved Ocular Bioavailability

    PubMed Central

    Adelli, Goutham R.; Bhagav, Prakash; Taskar, Pranjal; Hingorani, Tushar; Pettaway, Sara; Gul, Waseem; ElSohly, Mahmoud A.; Repka, Michael A.; Majumdar, Soumyajit

    2017-01-01

    Purpose The aim of the present study was to evaluate the utility of the relatively hydrophilic Δ9-tetrahydrocannabinol (THC) prodrugs, mono and di-valine esters (THC-Val and THC-Val-Val) and the amino acid (valine)-dicarboxylic acid (hemisuccinate) ester (THC-Val-HS), with respect to ocular penetration and intraocular pressure (IOP) lowering activity. THC, timolol, and pilocarpine eye drops were used as controls. Methods THC-Val, THC-Val-Val, and THC-Val-HS were synthesized and chemically characterized. Aqueous solubility and in vitro transcorneal permeability of THC and the prodrugs, in the presence of various surfactants and cyclodextrins, were determined. Two formulations were evaluated for therapeutic activity in the α-chymotrypsin induced rabbit glaucoma model, and the results were compared against controls comprising of THC emulsion and marketed timolol maleate and pilocarpine eye drops. Results THC-Val-HS demonstrated markedly improved solubility (96-fold) and in vitro permeability compared to THC. Selected formulations containing THC-Val-HS effectively delivered THC to the anterior segment ocular tissues in the anesthetized rabbits: 62.1 ng/100 μL of aqueous humor (AH) and 51.4 ng/50 mg of iris ciliary bodies (IC) (total THC). The duration and extent of IOP lowering induced by THC-Val-HS was 1 hour longer and 10% greater, respectively, than that obtained with THC and was comparable with the pilocarpine eye drops. Timolol ophthalmic drops, however, exhibited a longer duration of activity. Both THC and THC-Val-HS were detected in the ocular tissues following multiple dosing of THC-Val-HS in conscious animals. The concentration of THC in the iris-ciliary bodies at the 60- and 120-minute time points (53 and 57.4 ng/50 mg) were significantly greater than that of THC-Val-HS (24.2 and 11.3 ng/50 mg). Moreover, at the two time points studied, the concentration of THC was observed to increase or stay relatively constant, whereas THC-Val-HS concentration decreased

  18. Properties of Copolymers of Aspartic Acid and Aliphatic Dicarboxylic Acids Prepared by Reactive Extrusion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aspartic acid may be prepared chemically or by the fermentation of carbohydrates. Currently, low molecular weight polyaspartic acids are prepared commercially by heating aspartic acid at high temperatures (greater than 220 degrees C) for several hours in the solid state. In an effort to develop a ...

  19. Effect of dicarboxylic acid chain length on the self-cleaning property of Nano-TiO2-coated cotton fabrics.

    PubMed

    Khajavi, Ramin; Berendjchi, Amirhosein

    2014-11-12

    In this study, the effect of dicarboxylic acid chain length on the amount of TiO2 nanoparticles (TiO2NPs) adsorption-produced self-cleaning property and washing durability on cotton fabrics were investigated. First, cotton fabric samples were treated with three kinds of dicarboxylic acids--oxalic, succinic, and adipic acids--and then dipped in TiO2NP solution with a certain concentration. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to investigate bonds formation between dicarboxylic acid groups and hydroxyl groups of cellulose, and a scanning electron microscope (SEM) was applied for the analysis of surface morphology in specimens. Drop absorbency time was determined for samples using the AATCC TM 79:2000. Washing stability and the amount absorption of TiO2NPs were determined by weighing and absorption spectrophotometry procedures, and the stain removal evaluation was conducted to assess the self-cleaning property. Results showed that all of the dicarboxylic acids used in this experiment improved the amount of TiO2NPs absorbed onto cotton samples and their durability to washing. In addition, color variation of samples treated with oxalic acid after 180 min of UV irradiation and drop absorbency time for samples treated with succinic acid were significantly increased by about 126 and 600%, respectively. The best durability was obtained from adipic acid, while a better self-cleaning property was obtained from oxalic acid.

  20. Morphology and phase transformations of tin oxide nanostructures synthesized by the hydrothermal method in the presence of dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Zima, Tatyana.; Bataev, Ivan

    2016-11-01

    A new approach to the synthesis of non-stoichiometric tin oxide structures with different morphologies and the phase compositions has been evaluated. The nanostructures were synthesized by hydrothermal treatment of the mixtures of dicarboxylic acids ― aminoterephthalic or oxalic ― with nanocrystalline SnO2 powder, which was obtained via the sol-gel technology. The products were characterized by Raman and IR spectroscopy, SEM, HRTEM, and XRD analysis. It was shown that the controlled addition of a dicarboxylic acid leads not only to a change in the morphology of the nanostructures, but also to SnO2-SnO2/Sn3O4-Sn3O4-SnO phase transformations. A single-phase Sn3O4 in the form of the well-separated hexagonal nanoplates and mixed SnO2/Sn3O4 phases in the form of hierarchical flower-like structures were obtained in the presence of organic additives. The effects of concentration, redox activity of the acids and heat treatment on the basic characteristics of the synthesized tin oxide nanostructures and phase transformations in the synthesized materials are discussed.

  1. Resolution of a Challenge for Solvation Modeling: Calculation of Dicarboxylic Acid Dissociation Constants Using Mixed Discrete-Continuum Solvation Models

    SciTech Connect

    Marenich, Aleksandr; Ding, Wendu; Cramer, Christopher J.; Truhlar, Donald G.

    2012-06-07

    First and second dissociation constants (pKa values) of oxalic acid, malonic acid, and adipic acid were computed by using a number of theoretical protocols based on density functional theory and using both continuum solvation models and mixed discrete-continuum solvation models. We show that fully implicit solvation models (in which the entire solvent is represented by a dielectric continuum) fail badly for dicarboxylic acids with mean unsigned errors averaged over six pKa values) of 2.4-9.0 log units, depending on the particular implicit model used. The use of water-solute clusters and accounting for multiple conformations in solution significantly improve the performance of both generalized Born solvation models and models that solve the nonhomogeneous dielectric Poisson equation for bulk electrostatics. The four most successful models have mean unsigned errors of only 0.6-0.8 log units.

  2. Laboratory photochemical processing of aqueous aerosols: formation and degradation of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Pavuluri, C. M.; Kawamura, K.; Mihalopoulos, N.; Swaminathan, T.

    2015-01-01

    To better understand the photochemical processing of dicarboxylic acids and related polar compounds, we conducted batch UV irradiation experiments on two types of aerosol samples collected from India, which represent anthropogenic (AA) and biogenic aerosols (BA), for time periods of 0.5 to 120 h. The irradiated samples were analyzed for molecular compositions of diacids, oxoacids and α-dicarbonyls. The results show that photochemical degradation of oxalic (C2) and malonic (C3) and other C8-C12 diacids overwhelmed their production in aqueous aerosols whereas succinic acid (C4) and C5-C7 diacids showed a significant increase (ca. 10 times) during the course of irradiation experiments. The photochemical formation of oxoacids and α-dicarbonyls overwhelmed their degradation during the early stages of experiment, except for ω-oxooctanoic acid (ωC8) that showed a similar pattern to that of C4. We also found a gradual decrease in the relative abundance of C2 to total diacids and an increase in the relative abundance of C4 during prolonged experiment. Based on the changes in concentrations and mass ratios of selected species with the irradiation time, we hypothesize that iron-catalyzed photolysis of C2 and C3 diacids dominates their concentrations in Fe-rich atmospheric waters, whereas photochemical formation of C4 diacid (via ωC8) is enhanced with photochemical processing of aqueous aerosols in the atmosphere. This study demonstrates that the ambient aerosols contain abundant precursors that produce diacids, oxoacids and α-dicarbonyls, although some species such as oxalic acid decompose extensively during an early stage of photochemical processing.

  3. Laboratory photochemical processing of aqueous aerosols: formation and degradation of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Pavuluri, C. M.; Kawamura, K.; Mihalopoulos, N.; Swaminathan, T.

    2015-07-01

    To better understand the photochemical processing of dicarboxylic acids and related polar compounds, we conducted batch UV irradiation experiments on two types of aerosol samples collected from India, which represent anthropogenic (AA) and biogenic (BA) aerosols, for time periods of 0.5 to 120 h. The irradiated samples were analyzed for molecular compositions of diacids, oxoacids and α-dicarbonyls. The results show that photochemical degradation of oxalic (C2), malonic (C3) and other C8-C12 diacids overwhelmed their production in aqueous aerosols, whereas succinic acid (C4) and C5-C7 diacids showed a significant increase (ca. 10 times) during the course of irradiation experiments. The photochemical formation of oxoacids and α-dicarbonyls overwhelmed their degradation during the early stages of experiment except for ω-oxooctanoic acid (ωC8), which showed a similar pattern to that of C4. We also found a gradual decrease in the relative abundance of C2 to total diacids and an increase in the relative abundance of C4 during prolonged experiment. Based on the changes in concentrations and mass ratios of selected species with the irradiation time, we hypothesize that iron-catalyzed photolysis of C2 and C3 diacids controls their concentrations in Fe-rich atmospheric waters, whereas photochemical formation of C4 diacid (via ωC8) is enhanced with photochemical processing of aqueous aerosols in the atmosphere. This study demonstrates that the ambient aerosols contain abundant precursors that produce diacids, oxoacids and α-dicarbonyls, although some species such as oxalic acid decompose extensively during an early stage of photochemical processing.

  4. Seasonal and longitudinal distributions of atmospheric water-soluble dicarboxylic acids, oxocarboxylic acids, and α-dicarbonyls over the North Pacific

    NASA Astrophysics Data System (ADS)

    Bikkina, Srinivas; Kawamura, Kimitaka; Imanishi, Katsuya; Boreddy, S. K. R.; Nojiri, Yukihiro

    2015-05-01

    In order to assess the seasonal variability of atmospheric abundances of dicarboxylic acids, oxocarboxylic acids, and α-dicarbonyls over the North Pacific and Sea of Japan, aerosol samples were collected along the longitudinal transacts during six cruises between Canada and Japan. The back trajectory analyses indicate that aerosol samples collected in winter and spring are influenced by the East Asian outflow, whereas summer and fall samples are associated with the pristine maritime air masses. Molecular distributions of water-soluble organics in winter and spring samples show the predominance of oxalic acid (C2) followed by succinic (C4) and malonic acids (C3). In contrast, summer and fall marine aerosols are characterized by the predominance of C3 over C4. Concentrations of dicarboxylic acids were higher over the Sea of Japan than the North Pacific. With a lack of continental outflow, higher concentrations during early summer are ascribed to atmospheric oxidation of organic precursors associated with high biological activity in the North Pacific. This interpretation is further supported by the high abundances of azelaic acid, which is a photochemical oxidation product of biogenic unsaturated fatty acids, over the Bering Sea in early summer when surface waters are characterized by high biological productivity. We found higher ratios of oxalic acid to pyruvic and glyoxylic acids (C2/Pyr and C2/ωC2) and glyoxal and methylglyoxal (C2/Gly and C2/MeGly) in summer and fall than in winter and spring, suggesting a production of C2 from the aqueous-phase oxidation of oceanic isoprene. In this study, dicarboxylic acids account for 0.7-38% of water-soluble organic carbon.

  5. Dicarboxylic acids and water-soluble organic carbon in aerosols in New Delhi, India, in winter: Characteristics and formation processes

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yuzo; Aggarwal, Shankar G.; Singh, Khem; Gupta, Prabhat K.; Kawamura, Kimitaka

    2009-10-01

    Day- and nighttime aerosol samples were collected at an urban site in New Delhi, India, in winter 2006-2007. They were studied for low molecular weight dicarboxylic acids and related compounds, as well as total water-soluble organic carbon (TWSOC). High concentrations of diacids (up to 6.03 μg m-3), TWSOC, and OC were obtained, which are substantially higher than those previously observed at other urban sites in Asia. Daytime TWSOC/OC ratio (37%) was on average higher than that in nighttime (25%). In particular, more water-soluble OC (M-WSOC) to TWSOC ratio in daytime (50%) was twice higher than in nighttime (27%), suggesting that aerosols in New Delhi are photochemically more processed in daytime to result in more water-soluble organic compounds. Oxalic acid (C2) was found as the most abundant dicarboxylic acid, followed by succinic (C4) and malonic (C3) acids. Contributions of C2 to M-WSOC were greater (av. 8%) in nighttime than daytime (av. 3%). Positive correlations of C2 with malic acid (hC4), glyoxylic acid (ωC2), and relative humidity suggest that secondary production of C2 probably in aqueous phase is important in nighttime via the oxidation of both longer-chain diacids and ωC2. C2 also showed a positive correlation with potassium (K+) in nighttime, suggesting that the enhanced C2 concentrations are associated with biomass/biofuel burning. More tight, positive correlation between less water-soluble OC (L-WSOC) and K+ was found in both day- and nighttime, suggesting that L-WSOC, characterized by longer chain and/or higher molecular weight compounds, is significantly influenced by primary emissions from biomass/biofuel burning.

  6. Stable carbon isotopic compositions of low-molecular-weight dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and fatty acids: Implications for atmospheric processing of organic aerosols

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Lin; Kawamura, Kimitaka; Cao, Fang; Lee, Meehye

    2016-04-01

    Stable carbon isotopic compositions (δ13C) were measured for 23 individual organic species including 9 dicarboxylic acids, 7 oxocarboxylic acids, 1 tricarboxylic acid, 2 α-dicarbonyls, and 4 fatty acids in the aerosols from Gosan background site in East Asia. δ13C values of particle phase glyoxal and methylglyoxal are significantly larger than those previously reported for isoprene and other precursors. The values are consistently less negative in oxalic acid (C2, average -14.1‰), glyoxylic acid (-13.8‰), pyruvic acid (-19.4‰), glyoxal (-13.5‰), and methylglyoxal (-18.6‰) compared to other organic species (e.g., palmitic acid, -26.3‰), which can be explained by the kinetic isotope effects during atmospheric oxidation of pre-aged precursors (e.g., isoprene) and the subsequent gas-particle partitioning after the evaporation of clouds or wet aerosols. The δ13C values of C2 is positively correlated with C2 to organic carbon ratio, indicating that photochemical production of C2 is more pronounced than its degradation during long-range atmospheric transport. The isotopic results also suggest that aqueous phase oxidation of glyoxal and methylglyoxal is a major formation process of oxalic acid via the intermediates such as glyoxylic acid and pyruvic acid. This study provides evidence that organic aerosols are intensively photochemically aged in the western North Pacific rim.

  7. Organic and inorganic aerosol compositions in Ulaanbaatar, Mongolia, during the cold winter of 2007 to 2008: Dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Jung, Jinsang; Tsatsral, Batmunkh; Kim, Young J.; Kawamura, Kimitaka

    2010-11-01

    To investigate the distributions and sources of water-soluble organic acids in the Mongolian atmosphere, aerosol samples (PM2.5, n = 34) were collected at an urban site (47.92°N, 106.90°E, ˜1300 m above sea level) in Ulaanbaatar, the capital of Mongolia, during the cold winter. The samples were analyzed for water-soluble dicarboxylic acids (C2-C12) and related compounds (ketocarboxylic acids and α-dicarbonyls), as well as organic carbon (OC), elemental carbon, water-soluble OC, and inorganic ions. Distributions of dicarboxylic acids and related compounds were characterized by a predominance of terephthalic acid (tPh; 130 ± 51 ng m-3, 19% of total detected organic acids) followed by oxalic (107 ± 28 ng m-3, 15%), succinic (63 ± 20 ng m-3, 9%), glyoxylic (55 ± 18 ng m-3, 8%), and phthalic (54 ± 27 ng m-3, 8%) acids. Predominance of terephthalic acid, which has not been reported previously in atmospheric aerosols, was mainly due to uncontrolled burning of plastic bottles and bags in home stoves for heating and waste incineration during the cold winter. This study demonstrated that most of the air pollutants were directly emitted from local sources such as heat and power plants, home stoves, and automobiles. Development of an inversion layer (<700 m above ground level) over the basin of Ulaanbaatar accelerated the accumulation of pollutants, causing severe haze episodes during the winter season.

  8. Stable carbon isotopic compositions of low-molecular-weight dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and fatty acids: implications for atmospheric processing of organic aerosols

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Kawamura, K.; Cao, F.; Lee, M.

    2015-12-01

    Stable carbon isotopic compositions (δ13C) were measured for 23 individual organic species including 9 dicarboxylic acids, 7 oxocarboxylic acids, 1 tricarboxylic acid, 2 α-dicarbonyls and 4 fatty acids in the aerosols from Gosan background site in East Asia. δ13C of particle-phase glyoxal and methylglyoxal are significantly higher than those previously reported for isoprene and other precursors, associated with isotope fractionation during atmospheric oxidation. 13C is consistently more enriched for oxalic acid (C2), glyoxylic acid, pyruvic acid, glyoxal and methylglyoxal compared to other organic compounds identified, which can be explained by the kinetic isotope effects during aqueous-phase processing and the subsequent gas-particle partitioning after clouds or wet aerosols evaporation δ13C of C2 is positively correlated with C2 and organic carbon ratio, indicating that a photochemical production of C2 is more pronounced than its degradation process during long-range transport. The 13C results also suggest that aqueous-phase oxidation of glyoxal and methylglyoxal is major formation process of oxalic acid production via the major intermediates glyoxylic acid and pyruvic acid. This study provides evidence that organic aerosols are intensively photo-chemically aged in this region.

  9. Longitudinal distributions of dicarboxylic acids, ω-oxoacids, pyruvic acid, α-dicarbonyls, and fatty acids in the marine aerosols from the central Pacific including equatorial upwelling

    NASA Astrophysics Data System (ADS)

    Hoque, Mir Md. Mozammal; Kawamura, Kimitaka

    2016-03-01

    Remote marine aerosol samples (total suspended particles) were collected during a cruise in the central Pacific from Japan to Mexico (1°59'N-35°N and 171°54'E-90°58'W). The aerosol samples were analyzed for dicarboxylic acids (C2-C11), ω-oxoacids, pyruvic acid, α-dicarbonyls, and fatty acids as well as organic and elemental carbon, water-soluble organic carbon, and total nitrogen (WSTN). During the study, diacids were the most abundant compound class followed by fatty acids, ω-oxoacids, and α-dicarbonyls. Molecular compositions of diacids showed a predominance of oxalic (C2) acid followed by malonic (C3) and succinic (C4) acids. Oxalic acid comprises 74% of total diacids. This result suggests that photochemical production of oxalic acid is significant over the central Pacific. Spatial distributions of diacids, ω-oxoacids, pyruvic acid, α-dicarbonyls, and fatty acids together with total carbon and WSTN showed higher abundances in the eastern equatorial Pacific where the upwelling of high-nutrient waters followed by high biological productivity is common, indicating that their in situ production is important in the warmer central Pacific through photochemical oxidation from their gaseous and particulate precursors. This study demonstrates that there is a strong linkage in biogeochemical cycles of carbon in the sea-air interface via ocean upwelling, phytoplankton productivity, sea-to-air emissions of organic matter, and formation of secondary organic aerosols in the eastern equatorial Pacific.

  10. Novel one-pot synthesis of dicarboxylic acids mediated alginate-zirconium biopolymeric complex for defluoridation of water.

    PubMed

    Prabhu, Subbaiah Muthu; Meenakshi, Sankaran

    2015-04-20

    The present investigation explains the fluoride removal from aqueous solution using alginate-zirconium complex prepared with respective dicarboxylic acids like oxalic acid (Ox), malonic acid (MA) and succinic acid (SA) as a medium. The complexes viz., alginate-oxalic acid-zirconium (Alg-Ox-Zr), alginate-malonic acid-zirconium (Alg-MA-Zr) and alginate-succinic acid-zirconium (Alg-SA-Zr) were synthesized and studied for fluoride removal. The synthesized complexes were characterized by FTIR, XRD, SEM with EDAX and mapping images. The effects of various operating parameters were optimized. The result showed that the maximum removal of fluoride 9653mgF(-)/kg was achieved by Alg-Ox-Zr complex at acidic pH in an ambient atmospheric condition. Equilibrium data of Alg-Ox-Zr complex was fitted well with Freundlich isotherm. The calculated values of thermodynamic parameters indicated that the fluoride adsorption is spontaneous and endothermic in nature. The mechanism of fluoride removal behind Alg-Ox-Zr complex has been proposed in detail. The suitability of the Alg-Ox-Zr complex has been tested with the field sample collected in a nearby fluoride endemic area.

  11. Photo and Thermal Behavior of New Reinforced Polyamide-nanocomposite Montmorillonite on 2,3-Pyrazin Dicarboxylic Acid

    NASA Astrophysics Data System (ADS)

    Faghihi, Khalil; Samiei, Mojtaba; Hajibeygi, Mohsen

    2012-06-01

    Two new samples of reinforce polyamidemontmorillonite nanocomposites were synthesized by a convenient solution intercalation technique. Polyamide (PA) 3 as a source of polymer matrix was synthesized by the direct polycondensation reaction of pyrazine 2,3-dicarboxylic acid 1 with 4,4'-diamino diphenyl ether 2 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). The resulting nanocomposite films were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that organo-modified clay was dispersed homogeneously in PA matrix. TGA indicated an enhancement of thermal stability of new nanocomposites compared with the pure polymer.

  12. Adducts of hexamethylenetetramine with ferrocenecarboxylic acid and ferrocene-1,1'-dicarboxylic acid: multiple disorder in space groups Fmm2 and Cmcm.

    PubMed

    Zakaria, Choudhury M; Ferguson, George; Lough, Alan J; Glidewell, Christopher

    2003-07-01

    Hexamethylenetetramine, C(6)H(12)N(4), and ferrocenecarboxylic acid, C(11)H(10)FeO(2), form a 1:2 adduct, (I), which is a salt, viz. hexamethylenetetraminium(2+) bis(ferrocenecarboxylate), (C(6)H(14)N(4))[Fe(C(5)H(5))(C(6)H(4)O(2))](2). The dication in (I) is disordered with two orientations at a site of mm2 symmetry in space group Fmm2, while the anion lies across a mirror plane with its unsubstituted cyclopentadienyl ring disordered over two sets of sites. With ferrocene-1,1'-dicarboxylic acid, C(12)H(10)FeO(4), hexamethylenetetramine forms a 1:1 adduct, (II), in which both components are neutral, viz. hexamethylenetetramine-ferrocene-1,1'-dicarboxylic acid (1/1), [Fe(C(6)H(5)O(2))(2)].C(6)H(12)N(4). The amine component in (II) is disordered with two orientations at a site of mm2 symmetry in space group Cmcm, while the acid component is disordered with two orientations at a site of 2/m symmetry. The components in (I) are linked into a finite three-ion aggregate by a single N-H.O hydrogen bond, while the components of (II) are linked into continuous chains by a single O-H.N hydrogen bond.

  13. Seasonal cycle and temperature dependence of pinene oxidation products, dicarboxylic acids and nitrophenols in fine and coarse air particulate matter

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Müller, L.; Winterhalter, R.; Moortgat, G. K.; Hoffmann, T.; Pöschl, U.

    2010-05-01

    Filter samples of fine and coarse air particulate matter (PM) collected over a period of one year in central Europe (Mainz, Germany) were analyzed for water-soluble organic compounds (WSOCs), including the α- and β-pinene oxidation products pinic acid, pinonic acid and 3-methyl-1,2,3-butanetricarboxylic acid (3-MBTCA), as well as a variety of dicarboxylic acids and nitrophenols. Seasonal variations and other characteristic features in fine, coarse, and total PM (TSP) are discussed with regard to aerosol sources and sinks in comparison to data from other studies and regions. The ratios of adipic acid and phthalic acid to azelaic acid indicate that the investigated samples were mainly influenced by biogenic sources. A strong Arrhenius-type correlation was found between the 3-MBTCA concentration and inverse temperature (R2=0.79, n=52, Ea=126±10 kJ mol-1, temperature range 275-300 K). Model calculations suggest that the temperature dependence observed for 3-MBTCA can be explained by enhanced photochemical production due to an increase of hydroxyl radical (OH) concentration with increasing temperature, whereas the influence of gas-particle partitioning appears to play a minor role. The results indicate that the OH-initiated oxidation of pinonic acid is the rate-limiting step in the formation of 3-MBTCA, and that 3-MBTCA may be a suitable tracer for the chemical aging of biogenic secondary organic aerosol (SOA) by OH radicals. An Arrhenius-type temperature dependence was also observed for the concentration of pinic acid (R2=0.60, n=56, Ea=84±9 kJ mol-1); it can be tentatively explained by the temperature dependence of biogenic pinene emission as the rate-limiting step of pinic acid formation.

  14. Seasonal cycle and temperature dependence of pinene oxidation products, dicarboxylic acids and nitrophenols in fine and coarse air particulate matter

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Y.; Müller, L.; Winterhalter, R.; Moortgat, G. K.; Hoffmann, T.; Pöschl, U.

    2010-08-01

    Filter samples of fine and coarse air particulate matter (PM) collected over a period of one year in central Europe (Mainz, Germany) were analyzed for water-soluble organic compounds (WSOCs), including the α- and β-pinene oxidation products pinic acid, pinonic acid and 3-methyl-1,2,3-butanetricarboxylic acid (3-MBTCA), as well as a variety of dicarboxylic acids and nitrophenols. Seasonal variations and other characteristic features in fine, coarse, and total PM (TSP) are discussed with regard to aerosol sources and sinks in comparison to data from other studies and regions. The ratios of adipic acid and phthalic acid to azelaic acid indicate that the investigated aerosol samples were mainly influenced by biogenic sources. A strong Arrhenius-type correlation was found between the 3-MBTCA concentration and inverse temperature (R2 = 0.79, n = 52, Ea = 126 ± 10 kJ mol-1, temperature range 275-300 K). Model calculations suggest that the temperature dependence observed for 3-MBTCA can be explained by enhanced photochemical production due to an increase of hydroxyl radical (OH) concentration with increasing temperature, whereas the influence of gas-particle partitioning appears to play a minor role. The results indicate that the OH-initiated oxidation of pinonic acid is the rate-limiting step in the formation of 3-MBTCA, and that 3-MBTCA may be a suitable tracer for the chemical aging of biogenic secondary organic aerosol (SOA) by OH radicals. An Arrhenius-type temperature dependence was also observed for the concentration of pinic acid (R2 = 0.60, n = 56, Ea = 84 ± 9 kJ mol-1); it can be tentatively explained by the temperature dependence of biogenic pinene emission as the rate-limiting step of pinic acid formation.

  15. Speciation and temporal characterization of dicarboxylic acids in PM 2.5 during a PM episode and a period of non-episodic pollution

    NASA Astrophysics Data System (ADS)

    Hsieh, Li-Ying; Chen, Chien-Lung; Wan, Meng-Wei; Tsai, Cheng-Hsien; Tsai, Ying I.

    PM 2.5 aerosol was collected during a PM episode and a non-episodic pollution period between September and November 2004 in suburban southern Taiwan and dicarboxylic acid and inorganic species content and provenance were investigated. Oxalic acid was the dominant dicarboxylic acid species, followed by succinic acid and malonic acid. Tartaric acid concentrations were the lowest. There was 49.3% more dicarboxylic acid in PM episode aerosol than in non-episodic aerosol. However, daily oxalic acid concentration increased 72.7% in PM episode aerosol, while succinic acid fell 20.9% and malonic acid fell 21.6%, indicating higher conversion of these acids into oxalic acid in PM episode aerosol. Dicarboxylic acid concentrations, particularly oxalic acid, peaked at night during the PM episode, due to accumulation of daytime oxalic acid combined with low wind velocity and low mixing layer height at this time. SO 42-, NO 3- and NH 4+ were the dominant ionic species in both PM episode and non-episodic aerosols. NO 3- concentration increased 106% during the PM episode, while HNO 3, a gaseous precursor of NO 3-, fell 57%, indicating a large conversion of HNO 3 to aerosol phase NO 3- in PM episode aerosol. Backward trajectory data indicate that burning of paddy fields may also contribute to oxalic acid content in PM episode aerosol in the study area, especially during nighttime. Principal component analyses showed that succinic acid, malonic acid and oxalic acid were important factors in both pollution periods and also that there was high correlation between tartaric acid and NO x or HNO 2, indicative of vehicle emissions. The mass ratio of oxalic acid to sulfate in this aerosol was as high as 60.3‰, 35.5% higher than in non-episodic aerosol. Principal component analyses showed that photochemical aerosols contributed by succinic acid, malonic acid and oxalic acid were important factors in both periods. There was high correlation between tartaric acid and NO x or HNO 2

  16. Stable protein device platform based on pyridine dicarboxylic acid-bound cubic-nanostructured mesoporous titania films.

    PubMed

    Kim, Hwajeong; Park, Sung Soo; Seo, Jooyeok; Ha, Chang-Sik; Moon, Cheil; Kim, Youngkyoo

    2013-08-14

    Here we shortly report a protein device platform that is extremely stable in a buffer condition similar to human bodies. The protein device platform was fabricated by covalently attaching cytochrome c (cyt c) protein molecules to organic coupler molecules (pyridine dicarboxylic acid, PDA) that were already covalently bound to an electron-transporting substrate. A cubic nanostructured mesoporous titania film was chosen as an electron-transporting substrate because of its large-sized cubic holes (∼7 nm) and highly crystalline cubic titania walls (∼0.4 nm lattice). Binding of PDA molecules to the mesoporous titania surface was achieved by esterification reaction between carboxylic acid groups (PDA) and hydroxyl groups (titania) in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) mediator, whereas the immobilization of cyt c to the PDA coupler was carried out by the EDC-mediated amidation reaction between carboxylic acid groups (PDA) and amine groups (cyt c). Results showed that the 2,4-position isomer among several PDAs exhibited the highest oxidation and reduction peak currents. The cyt c-immobilized PDA-bound titania substrates showed stable and durable electrochemical performances upon continuous current-voltage cycling for 240 times (the final current change was less than 3%) and could detect superoxide that is a core indicator for various diseases including cancers.

  17. Complexation of Am(III) and Nd(III) by 1,10-Phenanthroline-2,9-Dicarboxylic Acid

    SciTech Connect

    Ogden, Mark D.; Sinkov, Sergey I.; Nilsson, Mikael; Lumetta, Gregg J.; Hancock, Robert D.; Nash, Ken L.

    2013-01-01

    The complexant 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) is a planar tetradentate ligand that is more preorganized for metal complexation than its unconstrained analogue ethylendiiminodiacetic acid (EDDA). Furthermore, the backbone nitrogen atoms of PDA are aromatic, hence are softer than the aliphatic amines of EDDA. It has been hypothesized that PDA will selectively bond to trivalent actinides over lanthanides. In this report, the results of spectrophotometric studies of the complexation of Nd(III) and Am(III) by PDA are reported. Because the complexes are moderately stable, it was necessary to conduct these titrations using competitive equilibrium methods, competitive cation omplexing between PDA and diethylenetriaminepentaacetic acid, and competition between ligand protonation and complex formation. Stability constants and ligand protonation constants were determined at 0.1 mol/L ionic strength and at 0.5 mol/L ionic strength nitrate media at 21 ± 1 C. The stability constants are lower than those predicted from first principles and speciation calculations indicate that Am(III) selectivity over Nd(III) is less than that exhibited by 1,10-phenanthroline.

  18. Syntheses and Antibiotic Evaluation of 2-{[(2R,4R)-4-Carboxy-2-hydroxypyrrolidin-1-yl]carbonyl}benzene-1,5-dicarboxylic Acids and 2-Carbamoylbenzene-1,5-dicarboxylic Acid Analogues

    PubMed Central

    2016-01-01

    Our search for new antibiotics led to the syntheses and biological evaluation of new classes of dicarboxylic acid analogues. The syntheses involve nucleophilic addition of different substituted benzylamine, aniline, alkylamine, and 4-hydroxyl-L-proline with carbamoylbenzoic acid. The results of the antimicrobial activity as indicated by the zone of inhibition (ZOI) showed that Z10 is the most active against Pseudomonas aeruginosa (32 mm) and least active against Candida stellatoidea (27 mm) and Vancomycin Resistant Enterococci (VRE) (27 mm), while Z7 shows the least zone of inhibition (22 mm) against Methicillin Resistant Staphylococcus aureus (MRSA). The minimum inhibition concentration (MIC) determination reveals that Z10 inhibits the growth of tested microbes at a low concentration of 6.25 μg/mL, while Z9 and Z12 inhibits the growth of most microbes at a concentration of 12.5 μg/mL, recording the least MIC. The Minimum Bactericidal/Fungicidal Concentration (MBC/MFC) results revealed that Z10 has the highest bactericidal/fungicidal effect on the test microbes, at a concentration of 12.5 μg/mL, with the exception of Candida stellatoidea and Vancomycin Resistant Enterococci (VRE) with MBC/MFC of 25 μg/mL. The result of this investigation reveals the potential of the target compounds (Z1–3,5,7–12) in the search for new antimicrobial agents. PMID:26981281

  19. Seasonal and rainfall-type variations in inorganic ions and dicarboxylic acids and acidity of wet deposition samples collected from subtropical East Asia

    NASA Astrophysics Data System (ADS)

    Tsai, Ying I.; Hsieh, Li-Ying; Kuo, Su-Ching; Chen, Chien-Lung; Wu, Pei-Ling

    2011-07-01

    Rainfall samples were collected over a period of 3 years and 8 months in subtropical East Asia. They are categorized into different rainfall types and analyzed to assess the ionic composition and its effect on the acidity of wet deposition in southern Taiwan. Only 4% of samples had a pH of <5.0, indicating that the study area is not impacted significantly by acid rain. The volume-weighted mean (VWM) pH by rainfall type was Spring Rain 5.74, Typhoon Rain 5.56, Summer Rain 5.46, Typhoon Outer Circulation (TOC) Rain 5.45, Plum Rain 5.32 and Autumn-Winter Rain 5.29. Dilution effects were important to the equivalent ionic concentration of different rainfall types. HCO 3-, SO 42- and Cl - were detected as major anions whereas NH 4+, Na + and Ca 2+ were major cations. CO 2-derived HCO 3- was the major ionic species in all but Typhoon Rain and Spring Rain, in which the major species were Na + and Cl - and Ca 2+, respectively. Excluding HCO 3-, the major species were NH 4+, Na + and Ca 2+ in Plum Rain, the secondary photochemical products SO 42-, NO 3- and NH 4+ in TOC Rain and Summer Rain, and Na + and Ca 2+ in Autumn-Winter Rain. Calculation of arithmetic means showed that dicarboxylic acids contributed between 0.25% and 0.53% of the total ionic concentration and of these, oxalic acid contributed the least (81.3% of the dicarboxylic acid) to TOC Rain and the most (96.1% of the dicarboxylic acid) to Spring Rain, suggestive of long-range transport in the latter. Differences in wet deposition composition were shown to be a result of differences in local emissions and long-range transport (hence of prevailing wind direction) during the period of rainfall and of the frequency and volume of rain that typifies each rainfall type. Principal component analysis (PCA) further revealed that traffic-related and industrial organic and inorganic pollutants, their secondary photochemical products, sea salts, and dust are important contributors to wet deposition. Moreover, the ratio of

  20. Molecular distributions and isotopic compositions of marine aerosols over the western North Atlantic: Dicarboxylic acids, ketoacids, α-dicarbonyls (glyoxal and methylglyoxal), fatty acids, sugars, and SOA tracers

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Ono, K.; Tachibana, E.; Quinn, P.; Bates, T. S.

    2013-12-01

    Marine aerosols were collected over the western North Atlantic from off the coast of Boston to Bermuda during the WACS (Western Atlantic Climate Study) cruise of R/V Ronald H. Brown in August 2012 using a high volume air sampler and pre-combusted quartz fiber filters. Aerosol filter samples (n=5) were analyzed for OC/EC, major inorganic ions, low molecular weight dicarboxylic acids and various secondary organic aerosol (SOA) tracers using carbon analyzer, ion chromatograph, GC/FID and GC/MS, respectively. Homologous series (C2-C12) of dicarboxylic acids (31-335 ng m-3) were detected with a predominance of oxalic acid. Total carbon and nitrogen and their stable isotope ratios were determined as well as stable carbon isotopic compositions of individual diacids using IRMS. Diacids were found to be the most abundant compound class followed by monoterpene-SOA tracers > isoprene-SOA tracers > sugar compounds > ketoacids > fatty alcohols > fatty acids > α-dicarbonyls > aromatic acids > n-alkanes. The concentrations of these compounds were higher in the coastal site and decreased in the open ocean. However, diacids stayed relatively high even in the remote ocean. Interestingly, contributions of oxalic acid to total aerosol carbon increased from the coast (2.3%) to the remote ocean (5.6%) during long-range atmospheric transport. Stable carbon isotopic composition of oxalic acid increased from the coast (-17.5‰) to open ocean (-12.4‰), suggesting that photochemical aging of organic aerosols occurred during the atmospheric transport over the ocean. Stable carbon isotope ratios of bulk aerosol carbon also increased from the coast near Boston to the open ocean near Bermuda.

  1. The influence of dicarboxylic acids: Oxalic acid and tartaric acid on the compressive strength of glass ionomer cements

    NASA Astrophysics Data System (ADS)

    Permana, Ahmadi Jaya; Setyawati, Harsasi; Hamami, Murwani, Irmina Kris

    2016-03-01

    Glass ionomer cement (GIC) has limitation on the mechanical properties especially compressive strength. The change of compressive strength of GIC by adding oxalic acid and tartaric acid has been investigated. Oxalic acid and tartaric acid was added to the liquid components at concentrations of 0 - 15% (w/w). Powder component of GIC was made from optimum experimental powder glass SiO2-Al2O3-CaF2. GIC was characterized by compressive strength test, SEM-EDX and FTIR. The addition of tartaric acid to GIC has greater improvement than addition of oxalic acid. The addition of tartaric acid at 10 % (w/w) to GIC has greatest value of compressive strength.

  2. Formation of water-soluble dicarboxylic acids, oxoacids and a-dicarbonyls by ozone oxidation of isoprene

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Tachibana, E.; Sakamoto, Y.; Hirokawa, J.

    2014-12-01

    Water-soluble dicarboxylic acids such as oxalic acid (C2) are the dominant organic compound class in atmospheric aerosols. They can act as cloud condensation nuclei and affect on the Earth climate. Diacids can be primary emitted from fossil fuel combustion and biomass burning and secondarily produced by photochemical oxidations of biogenic and anthropogenic hydrocarbons. However, their sources and formation processes are still not well understood. Recently model and observation studies suggested the importance of isoprene as a precursor of oxalic acid. Isoprene is the most abundant BVOC emitted from terrestrial plants and can serve as important precursors of diacids. We conducted a laboratory oxidation of isoprene (2.0 ppm) with ozone (4.3 ppm) in a Teflon bag for 10 to 480 min. The formed particles were collected with quartz fiber filters and analyzed for diacids, oxoacids and a-dicarbonyls employing water extraction and butyl ester derivatization and using GC and GC/MS techniques. Here, we report the analytical results to better understand the formation process of diacids and related compounds from isoprene. We detected homologous series of saturated diacids (C2-C6), unsaturated diacids (maleic and methylmaleic acids), w-oxocarboxylic acids (C2-C9), pyruvic acid, glyoxal and methylglyoxal. We found that oxalic acid (3000-9700 ngm-3) is the most abundant diacid followed by succinic (C4) or malonic (C3) acid. Their concentrations increased with reaction time showing a maximum in 4 hours. Interestingly, C3/C4 ratios increased with time. The second most abundant species after oxalic acid was generally methylglyoxal (3600-9600 ngm-3), except for the 30 min. sample where methylglyoxal was more abundant than oxalic acid. Glyoxylic acid (wC2) was found as the most abundant oxoacid (1600-3800 ngm-3) followed by wC3 and wC4. Although the concentrations of diacids and related compounds are 1-2 orders magnitude higher than those reported in ambient aerosols, this study

  3. Piperazine-2,3-dicarboxylic acid Derivatives as Dual Antagonists of NMDA and GluK1-Containing Kainate Receptors

    PubMed Central

    Irvine, Mark W.; Costa, Blaise M.; Dlaboga, Daniel; Culley, Georgia; Hulse, Richard; Scholefield, Caroline L.; Atlason, Palmi; Fang, Guangyu; Eaves, Richard; Morley, Richard; Mayo-Martin, Maria B.; Amici, Mascia; Bortolotto, Zuner A.; Donaldson, Lucy; Collingridge, Graham L.; Molnár, Elek; Monaghan, Daniel T.; Jane, David E.

    2011-01-01

    Competitive N-methyl-D-aspartate receptor (NMDAR) antagonists bind to the GluN2 subunit, of which there are four types (GluN2A-D). We report that some N1-substituted derivatives of cis-piperazine-2,3-dicarboxylic acid display improved relative affinity for GluN2C and GluN2D versus GluN2A and GluN2B. These derivatives also display subtype-selectivity among the more distantly related kainate receptor family. Compounds 18i and (−)-4 were the most potent kainate receptor antagonists and 18i was selective for GluK1 versus GluK2, GluK3 and AMPA receptors. Modeling studies revealed structural features required for activity at GluK1 subunits and suggested that S674 was vital for antagonist activity. Consistent with this hypothesis, replacing the equivalent residue in GluK3 (alanine) with a serine imparts 18i antagonist activity. Antagonists with dual GluN2D and GluK1 antagonist activity may have beneficial effects in various neurological disorders. Consistent with this idea, antagonist 18i (30 mg/Kg i.p.) showed antinociceptive effects in an animal model of mild nerve injury. PMID:22111545

  4. Role of cationic amino acids in the Na+/dicarboxylate co-transporter NaDC-1.

    PubMed Central

    Pajor, A M; Kahn, E S; Gangula, R

    2000-01-01

    The role of cationic amino acids in the Na(+)/dicarboxylate co-transporter NaDC-1 was investigated by site-directed mutagenesis and subsequent expression of mutant transporters in Xenopus oocytes. Of the ten residues chosen for mutagenesis, eight (Lys-34, Lys-107, Arg-108, Lys-333, Lys-390, Arg-368, Lys-414 and Arg-541) were found to be non-essential for function or targeting. Only two conserved residues, Lys-84 (at the cytoplasmic end of helix 3) and Arg-349 (at the extracellular end of helix 7), were found to be important for transport. Both mutant transporters were expressed at the plasma membrane. The mutation of Lys-84 to Ala resulted in an increased K(m) for succinate of 1.8 mM, compared with 0.3 mM in the wild-type NaDC-1. The R349A mutant had Na(+) and citrate kinetics that were similar to those of the wild type. However, succinate handling in the R349A mutant was altered, with evidence of inhibition at high succinate concentrations. In conclusion, charge neutralization of Lys-84 and Arg-349 in NaDC-1 affects succinate handling, suggesting that these residues might have roles in substrate binding. PMID:10970779

  5. Application of novel catalytic-ceramic-filler in a coupled system for long-chain dicarboxylic acids manufacturing wastewater treatment.

    PubMed

    Wu, Suqing; Qi, Yuanfeng; Fan, Chunzhen; He, Shengbing; Dai, Bibo; Huang, Jungchen; Zhou, Weili; Gao, Lei

    2016-02-01

    To gain systematic technology for long-chain dicarboxylic acids (LDCA) manufacturing wastewater treatment, catalytic micro-electrolysis (CME) coupling with adsorption-biodegradation sludge (AB) process was studied. Firstly, novel catalytic-ceramic-filler was prepared from scrap iron, clay and copper sulfate solution and packed in the CME reactor. To remove residual n-alkane and LDCA, the CME reactor was utilized for LDCA wastewater pretreatment. The results revealed that about 94% of n-alkane, 98% of LDCA and 84% of chemical oxygen demand (COD) were removed by the aerated CME reactor at the optimum hydraulic retention time (HRT) of 3.0 h. In this process, catalysis from Cu and montmorillonites played an important role in improving the contaminants removal. Secondly, to remove residual COD in the wastewater, AB process was designed for the secondary biological treatment, about 90% of the influent COD could be removed by biosorption, bio-flocculation and biodegradation effects. Finally, the effluent COD (about 150 mg L(-1)) discharged from the coupled CME-AB system met the requirement of the national discharged standard (COD ≤ 300 mg L(-1)). All of these results suggest that the coupled CME-AB system is a promising technology due to its high-efficient performance, and has the potential to be applied for the real LDCA wastewater treatment.

  6. [Raman spectra and structure analysis of 2,6-pyridine dicarboxylic acid in different states and single Bacillus spore].

    PubMed

    Huang, Rong-shao; Huang, Xi; Xu, Lan-lan; Li, Yong-qing; Huang, Shu-shi

    2011-03-01

    The Raman spectra of 2,6-pyridine dicarboxylic acid (DPA) and their calcium salts(Ca-DPA) in different states and the Ca-DPA in a single bacterial spore have been recorded by laser tweezers Raman system (LTRS) and the spectra have been assigned. Raman spectra of different states of DPA and Ca-DPA are different evidently. Analysis leading to differences in the structure of spectrum may be due to that the Raman spectra of DPA crystalline reflected more precise characteristics information compared to DPA powder, in which the laser can penetrate through DPA crystalline and the Raman scatter from the crystalline interior is greater than that from DPA powder. The second reason is that DPA powder and Ca-DPA crystalline contain water molecules, and the intermolecular hydrogen bonding in the crystals of these molecules is extensive. The presence of calcium ions would affect the pyridine ring so that both sides of the carboxyl pyridine ring have a certain geometric deformation and the hydroxy carboxylic was damaged. The DPA2-anion is principal in Ca-DPA and the DPA solution. The calcium ion affects the stability of the pyridine ring structure in the Ca-DPA solution. The result from the spectra also showed that the DPA in single spores present Ca-DPA crystal state.

  7. Specific chiral sensing of amino acids using induced circularly polarized luminescence of bis(diimine)dicarboxylic acid europium(III) complexes.

    PubMed

    Okutani, Kazuhiro; Nozaki, Koichi; Iwamura, Munetaka

    2014-06-02

    The circularly polarized luminescence (CPL) from [Eu(pda)2](-) (pda = 1,10-phenanthroline-2,9-dicarboxylic acid) and [Eu(bda)2](-) (bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) in aqueous solutions containing various amino acids was investigated. The europium(III) complexes exhibited bright-red luminescence assignable to the f-f transition of the Eu(III) ion when irradiated with UV light. Although the luminescence was not circularly polarized in the solid state or in aqueous solutions, in accordance with the achiral crystal structure, the complexes exhibited detectable induced CPL (iCPL) in aqueous solutions containing chiral amino acids. In the presence of L-pyrrolidonecarboxylic acid, both [Eu(pda)2](-) and [Eu(bda)2](-) showed similar iCPL intensity (glum ∼ 0.03 for the (5)D0 → (7)F1 transition at 1 mol·dm(-3) of the amino acid). On the other hand, in the presence of L-histidine or L-arginine, [Eu(pda)2](-) exhibited intense CPL (glum ∼ 0.08 for the (5)D0 → (7)F1 transition at 0.10 mol·dm(-3) of the amino acid), whereas quite weak CPL was observed for [Eu(bda)2](-) under the same conditions (glum < 0.01). On the basis of analysis of the iCPL intensities in the presence of 12 amino acids, [Eu(pda)2](-) was found to be a good chiral CPL probe with high sensitivity (about 10(-2) mol·dm(-3)) and high selectivity for L-histidine at pH 3 and for L-arginine at pH 7. The mechanism of iCPL was evaluated by analysis of the fine structures in the luminescence spectra and the amino acid concentration dependence of glum. For the [Eu(pda)2](-)-histidine/arginine systems, the europium(III) complexes possess coordination structures similar to that in the crystal with slight distortion to form a chiral structure due to specific interaction with two zwitterionic amino acids. This mechanism was in stark contrast to that of the europium(III) complex-pyrrolidonecarboxylic acid system in which one amino acid coordinates to the Eu(III) ion to yield an achiral coordination

  8. Key Process Conditions for Production of C4 Dicarboxylic Acids in Bioreactor Batch Cultures of an Engineered Saccharomyces cerevisiae Strain▿

    PubMed Central

    Zelle, Rintze M.; de Hulster, Erik; Kloezen, Wendy; Pronk, Jack T.; van Maris, Antonius J. A.

    2010-01-01

    A recent effort to improve malic acid production by Saccharomyces cerevisiae by means of metabolic engineering resulted in a strain that produced up to 59 g liter−1 of malate at a yield of 0.42 mol (mol glucose)−1 in calcium carbonate-buffered shake flask cultures. With shake flasks, process parameters that are important for scaling up this process cannot be controlled independently. In this study, growth and product formation by the engineered strain were studied in bioreactors in order to separately analyze the effects of pH, calcium, and carbon dioxide and oxygen availability. A near-neutral pH, which in shake flasks was achieved by adding CaCO3, was required for efficient C4 dicarboxylic acid production. Increased calcium concentrations, a side effect of CaCO3 dissolution, had a small positive effect on malate formation. Carbon dioxide enrichment of the sparging gas (up to 15% [vol/vol]) improved production of both malate and succinate. At higher concentrations, succinate titers further increased, reaching 0.29 mol (mol glucose)−1, whereas malate formation strongly decreased. Although fully aerobic conditions could be achieved, it was found that moderate oxygen limitation benefitted malate production. In conclusion, malic acid production with the engineered S. cerevisiae strain could be successfully transferred from shake flasks to 1-liter batch bioreactors by simultaneous optimization of four process parameters (pH and concentrations of CO2, calcium, and O2). Under optimized conditions, a malate yield of 0.48 ± 0.01 mol (mol glucose)−1 was obtained in bioreactors, a 19% increase over yields in shake flask experiments. PMID:20008165

  9. Biothermodynamic characterization of monocarboxylic and dicarboxylic aliphatic acids binding to human serum albumin: a flow microcalorimetric study.

    PubMed

    Aki, H; Yamamoto, M

    1993-02-01

    Thermodynamic parameters have been evaluated for the binding of unbranched monocarboyxlic aliphatic acids (MCAs) of 4 to 16 carbons (MC4 to MC16) and dicarboxylic aliphatic acids (DCAs) of 4 to 16 carbons (DC4 to DC16) to human serum albumin (HSA) on the basis of microcalorimetric measurement at pH 7.4 and 37 degrees C by computer-fitting to single- and two-class binding models. Long-chain MCAs (MC10 to MC16) and DCAs (DC14 and DC16) had the first class of binding sites with high affinity (large binding constant) of 10(5) to 10(6) M-1 and the second class with lower affinity and high capacity (large numbers of binding sites). Short- or medium-chain MCAs and DCAs bound to HSA at some low affinity binding sites. The binding constants of MCAs were ten times larger than those of DCAs. All the relationships between the thermodynamic parameters and alkyl-chain length of the acids showed clear-cut inflections in their plots around eight or nine methylene units. The free energy change of the first class of binding sites (- delta G1) became more negative with an increment of -1.0 kJ mol-1 CH2(-1) as the alkyl-chain length increased, but there were steep rises between MC9 and MC11 with -2.90 kJ mol-1 CH2(-1) and between DC9 and DC12 with -2.02 kJ mol-1 CH2(-1). The enthalpy change (- delta H) increased at the rate of -7.4 kJ mol-1 CH2(-1) to the maximum at MC9 and DC10, then decreased due to hydrophobicity of the alkyl-chains. From compensation analyses (delta H vs. delta S and delta G), HSA binding sites were characterized into three groups.

  10. High abundances of water-soluble dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls in the mountaintop aerosols over the North China Plain during wheat burning season

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Tachibana, E.; Okuzawa, K.; Aggarwal, S. G.; Kanaya, Y.; Wang, Z. F.

    2013-08-01

    Aerosol (TSP) samples were collected at the summit of Mount Tai (elevation: 1534 m a.s.l., 36.25° N, 117.10° E) located in the North China Plain using a high-volume air sampler and pre-combusted quartz filters. Sampling was conducted on day/night or 3 h basis in the period from 29 May to 28 June 2006 during the field burning of wheat straw residue and the post-burning season. The filter samples were analyzed for low-molecular-weight dicarboxylic acids, ketoacids and α-dicarbonyls using capillary gas chromatography (GC) and GC-MS employing water extraction and butyl ester derivatization. Molecular distributions of dicarboxylic acids (C2-C11, 220-6070 ng m-3) were characterized by a predominance of oxalic (C2) acid (105-3920 ng m-3) followed by succinic (C4) or malonic (C3) acid. Unsaturated aliphatic diacids, including maleic (M), isomaleic (iM) and fumaric (F) acids, were also detected together with aromatic diacids (phthalic, isophthalic and terephthalic acids). ω-oxocarboxylic acids (C2-C9, 24-610 ng m-3) were detected as the second most abundant compound class with the predominance of glyoxylic acid (11-360 ng m-3), followed by α-ketoacid (pyruvic acid, 3-140 ng m-3) and α-dicarbonyls (glyoxal, 1-230 ng m-3 and methylglyoxal, 2-120 ng m-3). We found that these levels (>6000 ng m-3 for diacids) are several times higher than those reported in Chinese megacities at ground levels. The concentrations of diacids increased from late May to early June, showing a maximum on 7 June, and then significantly decreased during the period 8-11 June, when the wind direction shifted from southerly to northerly. Similar temporal trends were found for ketocarboxylic acids and α-dicarbonyls as well as total carbon (TC) and water-soluble organic carbon (WSOC). The temporal variations of water-soluble organics were interpreted by the direct emission from the field burning of agricultural wastes (wheat straw) in the North China Plain and the subsequent photochemical oxidation of

  11. Engineering rTCA pathway and C4-dicarboxylate transporter for L-malic acid production.

    PubMed

    Chen, Xiulai; Wang, Yuancai; Dong, Xiaoxiang; Hu, Guipeng; Liu, Liming

    2017-02-22

    L-Malic acid is an important component of a vast array of food additives, antioxidants, disincrustants, pharmaceuticals, and cosmetics. Here, we presented a pathway optimization strategy and a transporter modification approach to reconstruct the L-malic acid biosynthesis pathway and transport system, respectively. First, pyruvate carboxylase (pyc) and malate dehydrogenase (mdh) from Aspergillus flavus and Rhizopus oryzae were combinatorially overexpressed to construct the reductive tricarboxylic acid (rTCA) pathway for L-malic acid biosynthesis. Second, the L-malic acid transporter (Spmae) from Schizosaccharomyces pombe was engineered by removing the ubiquitination motification to enhance the L-malic acid efflux system. Finally, the L-malic acid pathway was optimized by controlling gene expression levels, and the final L-malic acid concentration, yield, and productivity were up to 30.25 g L(-1), 0.30 g g(-1), and 0.32 g L(-1) h(-1) in the resulting strain W4209 with CaCO3 as a neutralizing agent, respectively. In addition, these corresponding parameters of pyruvic acid remained at 30.75 g L(-1), 0.31 g g(-1), and 0.32 g L(-1) h(-1), respectively. The metabolic engineering strategy used here will be useful for efficient production of L-malic acid and other chemicals.

  12. Water-soluble organic carbon, dicarboxylic acids, ketoacids, and α-dicarbonyls in the tropical Indian aerosols

    NASA Astrophysics Data System (ADS)

    Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.

    2010-06-01

    Tropical aerosol (PM10) samples (n = 49) collected from southeast coast of India were studied for water-soluble dicarboxylic acids (C2-C12), ketocarboxylic acids (C2-C9), and α-dicarbonyls (glyoxal and methylglyoxal), together with analyses of total carbon (TC) and water-soluble organic carbon (WSOC). Their distributions were characterized by a predominance of oxalic acid followed by terephthalic (t-Ph), malonic, and succinic acids. Total concentrations of diacids (227-1030 ng m-3), ketoacids (16-105 ng m-3), and dicarbonyls (4-23 ng m-3) are comparative to those from other Asian megacities such as Tokyo and Hong Kong. t-Ph acid was found as the second most abundant diacid in the Chennai aerosols. This feature has not been reported previously in atmospheric aerosols. t-Ph acid is most likely derived from the field burning of plastics. Water-soluble diacids were found to contribute 0.4%-3% of TC and 4%-11% of WSOC. Based on molecular distributions and backward air mass trajectories, we found that diacids and related compounds in coastal South Indian aerosols are influenced by South Asian and Indian Ocean monsoons. Organic aerosols are also suggested to be significantly transported long distances from North India and the Middle East in early winter and from Southeast Asia in late winter, but some originate from photochemical reactions over the Bay of Bengal. In contrast, the Arabian Sea, Indian Ocean, and South Indian continent are suggested as major source regions in summer. We also found daytime maxima of most diacids, except for C9 and t-Ph acids, which showed nighttime maxima in summer. Emissions from marine and terrestrial plants, combined with land/sea breezes and in situ photochemical oxidation, are suggested especially in summer as an important factor that controls the composition of water-soluble organic aerosols over the southeast coast of India. Regional emissions from anthropogenic sources are also important in megacity Chennai, but their influence is

  13. High-level production of ethylmalonyl-CoA pathway-derived dicarboxylic acids by Methylobacterium extorquens under cobalt-deficient conditions and by polyhydroxybutyrate negative strains.

    PubMed

    Sonntag, Frank; Müller, Jonas E N; Kiefer, Patrick; Vorholt, Julia A; Schrader, Jens; Buchhaupt, Markus

    2015-04-01

    Bio-based production of dicarboxylic acids is an emerging research field with remarkable progress during the last decades. The recently established synthesis of the ethylmalonyl-CoA pathway (EMCP)-derived dicarboxylic acids, mesaconic acid and (2S)-methylsuccinic acid, from the alternative carbon source methanol (Sonntag et al., Appl Microbiol Biotechnol 98:4533-4544, 2014) gave a proof of concept for the sustainable production of hitherto biotechnologically inaccessible monomers. In this study, substantial optimizations of the process by different approaches are presented. Abolishment of mesaconic and (2S)-methylsuccinic acid reuptake from culture supernatant and a productivity increase were achieved by 30-fold decreased sodium ion availability in culture medium. Undesired flux from EMCP into polyhydroxybutyrate (PHB) cycle was hindered by the knockout of polyhydroxyalkanoate synthase phaC which was concomitant with 5-fold increased product concentrations. However, frequently occurring suppressors of strain ΔphaC lost their beneficial properties probably due to redirected channeling of acetyl-CoA. Pool sizes of the product precursors were increased by exploiting the presence of two cobalt-dependent mutases in the EMCP: Fine-tuned growth-limiting cobalt concentrations led to 16-fold accumulation of mesaconyl- and (2S)-methylsuccinyl-CoA which in turn resulted in 6-fold increased concentrations of mesaconic and (2S)-methylsuccinic acids, with a combined titer of 0.65 g/l, representing a yield of 0.17 g/g methanol. This work represents an important step toward an industrially relevant production of ethylmalonyl-CoA pathway-derived dicarboxylic acids and the generation of a stable PHB synthesis negative Methylobacterium extorquens strain.

  14. Field Observation of Heterogeneous Formation of Dicarboxylic acids, Keto-carboxylic acids, α-Dicarbonyls and Nitrate in Xi'an, China during Asian dust storm periods

    NASA Astrophysics Data System (ADS)

    Wang, G.; Wang, J.; Ren, Y.; Li, J.

    2015-12-01

    To understand the formation mechanism of secondary organic aerosols (SOA) on dust surfaces, this study investigated the concentrations and compositions of dicarboxylic acids (C2-C11), keto-carboxylic acids (C3-C7), α-dicarbonyls and inorganic ions in size-segregated aerosols (9-stages) collected in Xi'an, China during the nondust storm and dust storm periods of 2009 and 2011. During the events the ambient particulate dicarboxylic acids were 932-2240 ng m-3, which are comparable and even higher than those in nondust periods. Molecular compositions of the above SOA are similar to those in nondust periods with oxalic acid being the leading species. In the presence of the dust storms, all the above mentioned SOA species in Xi'an were predominantly enriched on the coarse particles (>2.1μm), and oxalic acid well correlated with NO3- (R2=0.72, p<0.001) rather than SO42-.This phenomenon differs greatly from the SOA in any other nondust period that is characterized by an enrichment of oxalic acid in fine particles and a strong correlation of oxalic acid with SO42-. Our results further demonstrate that NO3- in the dust periods in Xi'an was mostly derived from secondary oxidation, whereas SO42- during the events was largely derived from surface soil of Gobi deserts. We propose a formation pathway to explain these observations, in which nitric acid and/or nitrogen oxides react with dust to produce Ca(NO3)2 and form a liquid phase on the surface of dust aerosols via water vapor-absorption of Ca(NO3)2, followed by a partitioning of the gas-phase water-soluble organic precursors (e.g.,glyoxal and methylglyoxal) into the aqueous-phase and a subsequent oxidation into oxalic acid. To the best of our knowledge, we found for the first time the enrichment of glyoxal and methylglyoxal on dust surface. Our data suggest an important role of nitrate in the heterogeneous formation process of SOA on the surface of Asian dust.

  15. Diurnal variations of total carbon, dicarboxylic acids, ketoacids and α-dicarbonyls in aerosols in the northern vicinity of Beijing

    NASA Astrophysics Data System (ADS)

    He, N.; Kawamura, K.; Okuzawa, K.; Kanaya, Y.; Wang, Z. F.

    2013-06-01

    Aerosol samples (TSP, n=58) were collected on day- and night-time basis at Mangshan in the north of Beijing, China in autumn 2007 to better understand the status of air quality and the influence of urban pollutants in the northern vicinity of Beijing. The samples were analyzed for aerosol mass, total carbon (TC), low molecular weight α, ω-dicarboxylic acids (C2-C12), ketoacids (ωC2-ωC9, pyruvic acid), α-dicarbonyls (glyoxal and methylglyoxal), as well as aromatic (phthalic, iso- and tere-phthalic) diacids. Aerosol mass and TC concentrations are higher in daytime than in nighttime. TC/aerosol mass ratios in this study are lower than those reported in megacities in East Asia, but higher than those reported in marine aerosols. Molecular distributions of diacids demonstrated that oxalic (C2) acid was the most abundant species, comprising 38-77% of total diacids, followed by succinic (C4) and malonic (C3) acids. For most compounds, the concentrations were higher in daytime than nighttime, indicating that diacids are produced in daytime by photochemical oxidation of organic precursors emitted from anthropogenic sources in Beijing during the transport to Mangshan area by the northward wind. However, we found that C2 concentrations are higher in nighttime than in daytime. A positive correlation of C2 to glyoxylic acid (ωC2) was obtained at night when relative humidity increased up to 100%, suggesting that aqueous phase production of C2 occurs in nighttime via the oxidation of ωC2. Depletion of C2 by photolysis of Fe-oxalato complexes might be another reason for the lower concentrations of C2 in daytime samples. High phthalic acid/C4 ratios in the aerosol samples suggest that automobile combustion and coal burning products are important sources, which are subjected to photochemical oxidation during the atmospheric transport of urban aerosols from Beijing. In contrast, higher concentrations of methylglyoxal in nighttime than daytime may suggest that isoprene emitted

  16. Pretreatment of solid carbonaceous material with dicarboxylic aromatic acids to prevent scale formation

    SciTech Connect

    Brunson, R.J.

    1982-06-01

    Scale formation during the liquefaction of lower ranking coals and similar carbonaceous materials is significantly reduced and/or prevented by pretreatment with a pretreating agent selected from the group consisting of phthalic acid, phthalic anhydride, pyromellitic acid and pyromellitic anhydride. The pretreatment is believed to convert the scale-forming components to the corresponding phthalate and/or pyromellitate prior to liquefaction. The pretreatment is accomplished at a total pressure within the range from about 1 to about 2 atmospheres. Temperature during pretreatment will generally be within the range from about 5 to about 80/sup 0/ C.

  17. Pretreatment of solid carbonaceous material with dicarboxylic aromatic acids to prevent scale formation

    SciTech Connect

    Brunson, Roy J.

    1982-01-01

    Scale formation during the liquefaction of lower ranking coals and similar carbonaceous materials is significantly reduced and/or prevented by pretreatment with a pretreating agent selected from the group consisting of phthalic acid, phthalic anhydride, pyromellitic acid and pyromellitic anhydride. The pretreatment is believed to convert the scale-forming components to the corresponding phthalate and/or pyromellitate prior to liquefaction. The pretreatment is accomplished at a total pressure within the range from about 1 to about 2 atmospheres. Temperature during pretreatment will generally be within the range from about 5.degree. to about 80.degree. C.

  18. Latitudinal distributions of atmospheric dicarboxylic acids, oxocarboxylic acids, and α-dicarbonyls over the western North Pacific: Sources and formation pathways

    NASA Astrophysics Data System (ADS)

    Bikkina, Srinivas; Kawamura, Kimitaka; Miyazaki, Yuzo

    2015-05-01

    The present study aims to assess the molecular distributions of water-soluble dicarboxylic acids (diacids: C2-C12), oxocarboxylic acids (C2-C9), and α-dicarbonyls (glyoxal and methylglyoxal) in aerosols collected over the western North Pacific (WNP) during a summer cruise (August to September 2008). The measured water-soluble organics show pronounced latitudinal distributions with higher concentrations in the region of 30°N-45°N (average 63 ng m-3) than 10°N-30°N (18 ng m-3). Mass fraction of oxalic acid (C2) in total aliphatic diacids (ΣC2-C12) showed higher values (72 ± 10%) in lower latitude (10°N-30°N) than that (56 ± 16%) in higher latitude (30°N-45°N), suggesting a photochemical production of C2 due to an increased insolation over the tropical WNP. A similar trend was found in other diagnostic ratios such as oxalic to succinic (C2/C4) and oxalic to glyoxylic acid (C2/ωC2), which further corroborate an enhanced photochemical aging over the WNP. In addition, relative abundances of oxalic acid in total diacids showed a marked increase as a function of ambient temperature, supporting their photochemical production. Constantly low concentration ratios of adipic and phthalic acids relative to azelaic acid suggest a small contribution of anthropogenic sources and an importance of oceanic sources during the study period. Significant production of C2 through oxidation of biogenic volatile organic compounds emitted from the sea surface is also noteworthy, as inferred from the strong linear correlations among water-soluble organic carbon, methanesulphonic acid, and oxalic acid. Sea-to-air emission of unsaturated fatty acids also contributes to formation of diacids over the WNP.

  19. Concentrations of higher dicarboxylic acids C5-C13 in fresh snow samples collected at the High Alpine Research Station Jungfraujoch during CLACE 5 and 6

    NASA Astrophysics Data System (ADS)

    Winterhalter, R.; Kippenberger, M.; Williams, J.; Fries, E.; Sieg, K.; Moortgat, G. K.

    2009-03-01

    Samples of freshly fallen snow were collected at the high alpine research station Jungfraujoch (Switzerland) in February and March 2006 and 2007, during the Cloud and Aerosol Characterization Experiments (CLACE) 5 and 6. In this study a new technique has been developed and demonstrated for the measurement of organic acids in fresh snow. The melted snow samples were subjected to solid phase extraction and resulting solutions analysed for organic acids by HPLC-MS-TOF using negative electrospray ionization. A series of linear dicarboxylic acids from C5 to C13 and phthalic acid, were identified and quantified. In several samples the biogenic acid pinonic acid was also observed. In fresh snow the median concentration of the most abundant acid, adipic acid, was 0.69 μg L-1 in 2006 and 0.70 μg L-1 in 2007. Glutaric acid was the second most abundant dicarboxylic acid found with median values of 0.46 μg L-1 in 2006 and 0.61 μg L-1 in 2007, while the aromatic acid phthalic acid showed a median concentration of 0.34 μg L-1 in 2006 and 0.45 μg L-1 in 2007. The concentrations in the samples from various snowfall events varied significantly, and were found to be dependent on the back trajectory of the air mass arriving at Jungfraujoch. Air masses of marine origin showed the lowest concentrations of acids whereas the highest concentrations were measured when the air mass was strongly influenced by boundary layer air.

  20. Partial crystallization and deliquescence of particles containing ammonium sulfate and dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Ling, Tsz Yan; Chan, Chak K.

    2008-07-01

    The partial crystallization and deliquescence of ammonium sulfate (AS) particles internally mixed with malonic acid (MA), glutaric acid (GA), and succinic acid (SA) were studied. Hygroscopic properties, elastic light scattering, and Raman spectra were measured during water uptake and evaporation of single particles suspended in an electrodynamic balance. AS/MA particles remained partially crystallized at RHs as low as 16%, while AS/GA and AS/SA particles became completely dry at about 30-36% RH and below. Partial deliquescence was observed at intermediate RHs of <10% to 79%, 70% to 80%, and 80% to >90% for the AS/MA, AS/GA, and AS/SA particles, respectively. Solid inclusions in various amounts were in equilibrium with the aqueous solutions. The Raman spectra show solid inclusions of both AS and MA in AS/MA particles, suggesting the heterogeneous crystallization of MA on solid AS. AS was found to deliquesce first at 76% RH in the AS/GA system, followed by GA at 78% RH. In the SA/AS system, AS was observed to dissolve at 80% RH, while SA remained as solid for RH as high as 90%. Comparisons to the thermodynamic model E-AIM demonstrated the necessity to correctly predict the solid phase during partial deliquescence for accurate water content estimation. The Raman spectra also revealed the formation of metastable forms of organic acids upon crystallization from supersaturated droplets of AS/GA and AS/SA. Transformation of metastable solids to stable forms was observed before water uptake in the AS/GA particles, while the SA in AS/SA particles transformed in the presence of water.

  1. Cyclohexane-1,2-dicarboxylic acid diisononyl ester and metabolite effects on rat epididymal stromal vascular fraction differentiation of adipose tissue

    SciTech Connect

    Campioli, Enrico; Duong, Tam B.; Deschamps, François; Papadopoulos, Vassilios

    2015-07-15

    Plastics are generally mixed with additives like plasticizers to enhance their flexibility, pliability, and elasticity proprieties. Plasticizers are easily released into the environment and are absorbed mainly through ingestion, dermal contact, and inhalation. One of the main classes of plasticizers, phthalates, has been associated with endocrine and reproductive diseases. In 2002, 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) was introduced in the market for use in plastic materials and articles intended to come into contact with food, and it received final approval from the European Food Safety Authority in 2006. At present, there is limited knowledge about the safety and potential metabolic and endocrine-disrupting properties of DINCH and its metabolites. The purpose of this study was to evaluate the biological effects of DINCH and its active metabolites, cyclohexane-1,2-dicarboxylic acid (CHDA) and cyclohexane-1,2-dicarboxylic acid mono isononyl ester (MINCH), on rat primary stromal vascular fraction (SVF) of adipose tissue. DINCH and its metabolite, CHDA, were not able to directly affect SVF differentiation. However, exposure of SVF to 50 μM and 100 μM concentrations of MINCH affected the expression of Cebpa and Fabp4, thus inducing SVF preadipocytes to accumulate lipids and fully differentiate into mature adipocytes. The effect of MINCH was blocked by the specific peroxisome proliferator-activated receptor (PPAR)-α antagonist, GW6471. Taken together, these results suggest that MINCH is a potent PPAR-α agonist and a metabolic disruptor, capable of inducing SVF preadipocyte differentiation, that may interfere with the endocrine system in mammals. - Highlights: • DINCH and CHDA did not affect the adipogenesis of the SVF. • MINCH affected the adipogenesis of the SVF. • MINCH effect was blocked by the specific PPAR-α antagonist GW6471. • MINCH exerted a similar effect as MEHP on SVF adipogenesis. • DINCH/MINCH are potential metabolic

  2. Neurochemical, pharmacological, and developmental studies on cerebellar receptors for dicarboxylic amino acids

    SciTech Connect

    Sharif, N.A.; Roberts, P.J.

    1984-01-01

    Specific binding of L-(/sup 3/H)glutamate ((/sup 3/H)Glu) and L(/sup 3/H)Asp) to cerebellar membranes represented a time-, temperature-, pH- and protein-dependent interaction which was both saturable and reversible. Binding sites for both radioligands appeared maximally enriched in synaptosomal fractions isolated by gradient centrifugation. Kinetically derived dissociation constant (K/sub off//K/sub on/ . K/sub d/) for (/sup 3/H)Glu binding to this fraction indicated high-affinity (433 nM). Competition experiments employing analogs of excitatory amino acids, including new antagonists, helped identify binding sites for (/sup 3/H)Glu and (/sup 3/H)Asp as receptors with differential pharmacological specificities. Membrane freezing reduced numbers of both receptor types, but binding activity could be recovered partially by incubation at 37 degrees C. Glu receptors exhibited a pronounced deleterious sensitivity to thiol modifying reagents and L-Glu (50-1000 microM) provided protection against these compounds during co-incubation with cerebellar membranes. It is suggested that cold storage may induce partially reversible receptor inactivation by promoting sulfhydryl group/bond modification. Rat cerebellar glutamatergic function (endogenous Glu content, Glu uptake and receptor sites) exhibited an apparent ontogenetic peak between days 8-12 postpartum with a plateauing profile from day 30 to adulthood. The accelerated development (days 8-12) coincides with the first demonstrable Glu release and kainic acid neurotoxicity, as described previously.

  3. Engineering Escherichia coli for Conversion of Glucose to Medium-Chain ω-Hydroxy Fatty Acids and α,ω-Dicarboxylic Acids.

    PubMed

    Bowen, Christopher H; Bonin, Jeff; Kogler, Anna; Barba-Ostria, Carlos; Zhang, Fuzhong

    2016-03-18

    In search of sustainable approaches to plastics production, many efforts have been made to engineer microbial conversions of renewable feedstock to short-chain (C2-C8) bifunctional polymer precursors (e.g., succinic acid, cadaverine, 1,4-butanediol). Less attention has been given to medium-chain (C12-C14) monomers such as ω-hydroxy fatty acids (ω-OHFAs) and α,ω-dicarboxylic acids (α,ω-DCAs), which are precursors to high performance polyesters and polyamides. Here we engineer a complete microbial conversion of glucose to C12 and C14 ω-OHFAs and α,ω-DCAs, with precise control of product chain length. Using an expanded bioinformatics approach, we screen a wide range of enzymes across phyla to identify combinations that yield complete conversion of intermediates to product α,ω-DCAs. Finally, through optimization of culture conditions, we enhance production titer of C12 α,ω-DCA to nearly 600 mg/L. Our results indicate potential for this microbial factory to enable commercially relevant, renewable production of C12 α,ω-DCA-a valuable precursor to the high-performance plastic, nylon-6,12.

  4. AgtA, the Dicarboxylic Amino Acid Transporter of Aspergillus nidulans, Is Concertedly Down-Regulated by Exquisite Sensitivity to Nitrogen Metabolite Repression and Ammonium-Elicited Endocytosis▿ †

    PubMed Central

    Apostolaki, Angeliki; Erpapazoglou, Zoi; Harispe, Laura; Billini, Maria; Kafasla, Panagiota; Kizis, Dimosthenis; Peñalva, Miguel Angel; Scazzocchio, Claudio; Sophianopoulou, Vicky

    2009-01-01

    We identified agtA, a gene that encodes the specific dicarboxylic amino acid transporter of Aspergillus nidulans. The deletion of the gene resulted in loss of utilization of aspartate as a nitrogen source and of aspartate uptake, while not completely abolishing glutamate utilization. Kinetic constants showed that AgtA is a high-affinity dicarboxylic amino acid transporter and are in agreement with those determined for a cognate transporter activity identified previously. The gene is extremely sensitive to nitrogen metabolite repression, depends on AreA for its expression, and is seemingly independent from specific induction. We showed that the localization of AgtA in the plasma membrane necessitates the ShrA protein and that an active process elicited by ammonium results in internalization and targeting of AgtA to the vacuole, followed by degradation. Thus, nitrogen metabolite repression and ammonium-promoted vacuolar degradation act in concert to downregulate dicarboxylic amino acid transport activity. PMID:19168757

  5. Dicarboxylic acids, ω-oxocarboxylic acids, α-dicarbonyls, WSOC, OC, EC, and inorganic ions in wintertime size-segregated aerosols from central India: Sources and formation processes.

    PubMed

    Deshmukh, Dhananjay K; Kawamura, Kimitaka; Deb, Manas K

    2016-10-01

    The size distributions of aerosols can provide evidences for their sources and formation processes in the atmosphere. Size-segregated aerosols (9-sizes) were collected in urban site (Raipur: 21.2°N and 82.3°E) in central India during winter of 2012-2013. The samples were analyzed for dicarboxylic acids (C2-C12), ω-oxocarboxylic acids (ωC2-ωC9), pyruvic acid and α-dicarbonyls (C2-C3) as well as elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC) and inorganic ions. Diacids showed a predominance of oxalic acid (C2) followed by succinic and azelaic acid whereas ω-oxoacids exhibited a predominance of glyoxylic acid and glyoxal was more abundant than methylglyoxal in all the sizes. Diacids, ω-oxoacids and α-dicarbonyls showed bimodal size distribution with peaks in fine and coarse modes. High correlations of fine mode diacids and related compounds with potassium and levoglucosan suggest that they were presumably due to a substantial contribution of primary emission from biomass burning and secondary production from biomass burning derived precursors. High correlations of C2 with higher carbon number diacids (C3-C9) suggest that they have similar sources and C2 may be produced via the decay of its higher homologous diacids in fine mode. Considerable portions of diacids and related compounds in coarse mode suggest that they were associated with mineral dust particles by their adsorption and photooxidation of anthropogenic and biogenic precursors via heterogeneous reaction on dust surface. This study demonstrates that biomass burning and dust particles are two major factors to control the size distribution of diacids and related compounds in the urban aerosols from central India.

  6. Stable carbon isotopic compositions of total carbon, dicarboxylic acids and glyoxylic acid in the tropical Indian aerosols: Implications for sources and photochemical processing of organic aerosols

    NASA Astrophysics Data System (ADS)

    Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.; Tachibana, Eri

    2011-09-01

    The tropical Indian aerosols (PM10) collected on day- and nighttime bases in winter and summer, 2007 from Chennai (13.04°N; 80.17°E) were studied for stable carbon isotopic compositions (δ13C) of total carbon (TC), individual dicarboxylic acids (C2-C9) and glyoxylic acid (ωC2). δ13C values of TC ranged from -23.9‰ to -25.9‰ (-25.0 ± 0.6‰; n = 49). Oxalic (C2) (-17.1 ± 2.5‰), malonic (C3) (-20.8 ± 1.8‰), succinic (C4) (-22.5 ± 1.5‰) and adipic (C6) (-20.6 ± 4.1‰) acids and ωC2 acid (-22.4 ± 5.5‰) were found to be more enriched with 13C compared to TC. In contrast, suberic (C8) (-29.4 ± 1.8‰), phthalic (Ph) (-30.1 ± 3.5‰) and azelaic (C9) (-28.4 ± 5.8‰) acids showed smaller δ13C values than TC. Based on comparisons of δ13C values of TC in Chennai aerosols to those (-24.7 ± 2.2‰) found in unburned cow-dung samples collected from Chennai and isotopic signatures of the particles emitted from point sources, we found that biofuel/biomass burning are the major sources of carbonaceous aerosols in South and Southeast Asia. The decrease in δ13C values of C9 diacid by about 5‰ from winter to summer suggests that tropical plant emissions also significantly contribute to organic aerosol in this region. Significant increase in δ13C values from C4 to C2 diacids in Chennai aerosols could be attributed for their photochemical processing in the tropical atmosphere during long-range transport from source regions.

  7. Water-soluble dicarboxylic acids and ω-oxocarboxylic acids in size-segregated aerosols over northern Japan during spring: sources and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, Dhananjay Kumar; Kawamura, Kimitaka; Kobayashi, Minoru; Gowda, Divyavani

    2016-04-01

    Seven sets (AF01-AF07) of size-segregated aerosol (12-sizes) samples were collected using a Micro-Orifice Uniform Deposit Impactor (MOUDI) in Sapporo, Japan during the spring of 2001 to understand the sources and atmospheric processes of water-soluble organic aerosols in the outflow region of Asian dusts. The samples were analyzed for dicarboxylic acids (C2-C12) and ω-oxocarboxylic acids as well as inorganic ions. The molecular distribution of diacids showed the predominance of oxalic acid (C2) followed by malonic and succinic acids whereas ω-oxoacids showed the predominance of glyoxylic acid (ωC2) in size-segregated aerosols. SO42- and NH4+ are enriched in submicron mode whereas NO3- and Ca2+ are in supermicron mode. Most of diacids and ω-oxoacids are enriched in supermicron mode in the samples (AF01-AF03) influenced by the long-range transport of mineral dusts whereas enhanced presence in submicron mode was observed in other sample sets. The strong correlations of C2 with Ca2+ (r = 0.95-0.99) and NO3- (r = 0.96-0.98) in supermicron mode in the samples AF01-AF03 suggest the adsorption or production of C2 diacid via heterogeneous reaction on the surface of mineral dust during long-range atmospheric transport. The preferential enrichment of diacids and ω-oxoacids in mineral dust has important implications for the solubility and cloud nucleation properties of the dominant fraction of water-soluble organic aerosols. This study demonstrates that biofuel and biomass burning and mineral dust originated in East Asia are two major factors to control the size distribution of diacids and related compounds over northern Japan.

  8. Surface enhanced Raman scattering of 2,2‧-biphenyl dicarboxylic acid on silver surfaces: Structure and orientation upon adsorption

    NASA Astrophysics Data System (ADS)

    Eom, So Young; Lee, Yu Ran; Kwon, Chan Ho; Kim, Hong Lae

    2016-07-01

    The SERS spectrum of 2,2‧-biphenyl dicarboxylic acid (22-BPDC) adsorbed on Ag nanoparticles has been measured and the observed bands are identified and assigned referred to the ordinary Raman spectrum and to the previously measured SERS spectrum of 4,4‧-biphenyl dicarboxylic acid (44-BPDC). [J. Mol. Struct. 1050, 2013, 128] As in the case of 44-BPDC, quantum chemical density functional theory calculations have also been performed to figure out structures and to calculate vibrational wavenumbers and eigenvectors in 22-BPDC. The observed SERS spectra could successfully be simulated from the models for adsorption of 22-BPDC to Ag and three Ag atom clusters. As opposed to 44-BPDC adsorbed flat on the Ag surfaces through both the COO-Ag and phenyl π-electron-metal interactions, the two phenyl rings remain twisted in 22-BPDC upon adsorption on the Ag surfaces with less π-electron-metal interaction because of small space allowances for the two closely located carboxyl groups compared to 44-BPDC.

  9. Synthesis, characterization and biological activities of metal(II) dipicolinate complexes derived from pyridine-2,6-dicarboxylic acid and 2-(piperazin-1-yl)ethanol

    NASA Astrophysics Data System (ADS)

    Büyükkıdan, Nurgün; Yenikaya, Cengiz; İlkimen, Halil; Karahan, Ceyda; Darcan, Cihan; Korkmaz, Tülin; Süzen, Yasemin

    2015-12-01

    The new water-soluble and air stable compounds (H2ppz)[Co(dipic)2]·6H2O (1), (H2ppz)[Ni(dipic)2]·6H2O (2) and (H2ppz)[Zn(dipic)2]·6H2O (3) were prepared by the reaction of corresponding metal(II) acetates and a proton transfer salt, (H2ppz) (Hdipic)2, (4) of pyridine-2,6-dicarboxylic acid (H2dipic) and 2-(piperazin-1-yl)ethanol (ppz). The compounds 1-3 were characterized by elemental, IR, UV-vis. thermal analyses, magnetic measurement and single crystal X-ray diffraction studies. The molecular structures of the title compounds consist of one 1-(2-hydroxyethyl)piperazine-1,4-diium (H2ppz+2) cation, one bis(pyridine-2,6-dicarboxylate)metal(II) [M(dipic)2]2- anion, and six uncoordinated water molecules. In compounds 1-3 the metal ions coordinate to two oxygen and one nitrogen atoms of two pyridine-2,6-dicarboxylate molecules forming an octahedral environment. Antimicrobial activities against Gram (-) wild type (Escherichia coli and Pseudomonas aeruginosa), Gram (+) wild type (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus and Bacillus subtilis) and clinical isolate (Morganella morganii, Proteus vulgaris and Enterobacter aeruginosa) were also studied. The results were reported, discussed and compared with the corresponding starting materials ((H2ppz) (Hdipic)2 (4), H2dipic and ppz). MIC (Minimal Inhibition Concentration) values of the newly synthesized compounds were determined as 4000 μg/ml (except B. subtilis and clinical isolate E. aeruginosa, >4000 μg/ml).

  10. C4-Dicarboxylate Utilization in Aerobic and Anaerobic Growth.

    PubMed

    Unden, Gottfried; Strecker, Alexander; Kleefeld, Alexandra; Kim, Ok Bin

    2016-06-01

    C4-dicarboxylates and the C4-dicarboxylic amino acid l-aspartate support aerobic and anaerobic growth of Escherichia coli and related bacteria. In aerobic growth, succinate, fumarate, D- and L-malate, L-aspartate, and L-tartrate are metabolized by the citric acid cycle and associated reactions. Because of the interruption of the citric acid cycle under anaerobic conditions, anaerobic metabolism of C4-dicarboxylates depends on fumarate reduction to succinate (fumarate respiration). In some related bacteria (e.g., Klebsiella), utilization of C4-dicarboxylates, such as tartrate, is independent of fumarate respiration and uses a Na+-dependent membrane-bound oxaloacetate decarboxylase. Uptake of the C4-dicarboxylates into the bacteria (and anaerobic export of succinate) is achieved under aerobic and anaerobic conditions by different sets of secondary transporters. Expression of the genes for C4-dicarboxylate metabolism is induced in the presence of external C4-dicarboxylates by the membrane-bound DcuS-DcuR two-component system. Noncommon C4-dicarboxylates like l-tartrate or D-malate are perceived by cytoplasmic one-component sensors/transcriptional regulators. This article describes the pathways of aerobic and anaerobic C4-dicarboxylate metabolism and their regulation. The citric acid cycle, fumarate respiration, and fumarate reductase are covered in other articles and discussed here only in the context of C4-dicarboxylate metabolism. Recent aspects of C4-dicarboxylate metabolism like transport, sensing, and regulation will be treated in more detail. This article is an updated version of an article published in 2004 in EcoSal Plus. The update includes new literature, but, in particular, the sections on the metabolism of noncommon C4-dicarboxylates and their regulation, on the DcuS-DcuR regulatory system, and on succinate production by engineered E. coli are largely revised or new.

  11. Dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls, fatty acids and benzoic acid in PM2.5 aerosol collected during CAREBeijing-2007: an effect of traffic restriction on air quality

    NASA Astrophysics Data System (ADS)

    Ho, K. F.; Huang, R.-J.; Kawamura, K.; Tachibana, E.; Lee, S. C.; Ho, S. S. H.; Zhu, T.; Tian, L.

    2014-06-01

    Thirty water-soluble organic species, including dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls, fatty acids, and benzoic acid were determined as well as organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) in PM2.5 samples collected during the Campaign of Air Quality Research in Beijing 2007 (CAREBeijing-2007) in the urban and suburban areas of Beijing. The objective of this study is to identify the influence of traffic emissions and regional transport to the atmosphere in Beijing during summer. PM2.5 samples collected with or without traffic restriction in Beijing are selected to evaluate the effectiveness of local traffic restriction measure on air pollution reduction. The average concentrations of the total quantified bifunctional organic compounds (TQBOC), total fatty acids and benzoic acid during the entire sampling period were 1184 ± 241 ng m-3, 597 ± 159 ng m-3 and 1496 ± 511ng m-3 in PKU, and 1050 ± 303 ng m-3, 475 ± 114 ng m-3 and 1278 ± 372 ng m-3 in Yufa. Oxalic acid (C2) was found as the most abundant dicarboxylic acid at PKU and Yufa, followed by phthalic acid (Ph). A strong even carbon number predominance with the highest level at palmitic acid (C16:0), followed by stearic acid (C18:0) was found for fatty acids. According to the back trajectories modeling results, the air masses were found to originate mainly from northeast, passing over southeast or south of Beijing (heavily populated, urbanized and industrialized areas), during heavier pollution events, whereas they are mainly from north or northwest sector (mountain areas without serious anthropogenic pollution sources) during cleaner events. The data with wind only from the same sector (minimizing the difference from regional contribution) but with and without traffic restriction in Beijing were analyzed to evaluate the effectiveness of local traffic restriction measure on the reduction of local air pollution in Beijing. The results suggested that the

  12. Dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls, fatty acids and benzoic acid in PM2.5 aerosol collected during CAREBeijing-2007: an effect of traffic restriction on air quality

    NASA Astrophysics Data System (ADS)

    Ho, K. F.; Huang, R.-J.; Kawamura, K.; Tachibana, E.; Lee, S. C.; Ho, S. S. H.; Zhu, T.; Tian, L.

    2015-03-01

    Thirty water-soluble organic species, including dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls, fatty acids and benzoic acid were determined as well as organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) in PM2.5 samples collected during the Campaign of Air Quality Research in Beijing 2007 (CAREBeijing-2007) in the urban and suburban areas of Beijing. The objective of this study is to identify the influence of traffic emissions and regional transport to the atmosphere in Beijing during summer. PM2.5 samples collected with or without traffic restriction in Beijing are selected to evaluate the effectiveness of local traffic restriction measures on air pollution reduction. The average concentrations of the total quantified bifunctional organic compounds (TQBOCs), total fatty acids and benzoic acid during the entire sampling period were 1184±241, 597±159 and 1496±511 ng m-3 in Peking University (PKU), and 1050±303, 475±114 and 1278±372 ng m-3 in Yufa, Beijing. Oxalic acid (C2) was found as the most abundant dicarboxylic acid at PKU and Yufa followed by phthalic acid (Ph). A strong even carbon number predominance with the highest level at stearic acid (C18:0), followed by palmitic acid (C16:0) was found for fatty acids. According to the back trajectories modeling results, the air masses were found to originate mainly from the northeast, passing over the southeast or south of Beijing (heavily populated, urbanized and industrialized areas), during heavier pollution events, whereas they are mainly from the north or northwest sector (mountain areas without serious anthropogenic pollution sources) during less pollution events. The data with wind only from the same sector (minimizing the difference from regional contribution) but with and without traffic restriction in Beijing were analyzed to evaluate the effectiveness of local traffic restriction measures on the reduction of local air pollution in Beijing. The results suggested

  13. Complexation behavior of trivalent actinides and lanthanides with 1,10-phenanthroline-2,9-dicarboxylic acid based ligands: insight from density functional theory.

    PubMed

    Manna, Debashree; Ghanty, Tapan K

    2012-08-21

    We have investigated the complexation behavior of preorganized 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) based ligands with trivalent lanthanides and actinides using density functional theory with various GGA type exchange-correlation functionals and different basis sets. New ligands have been designed from PDA through functionalization with soft donor atoms such as sulfur, resulting in mono-thio-dicarboxylic acids (TCA/TCA1) and di-thio-dicarboxylic acid (THIO). It has been found that selectivity in terms of complexation energy of actinides over lanthanides is the maximum with TCA1 where the metal-ligand binding is through the O atoms. This unusual feature where a softer actinide metal ion is bonded strongly with hard donor oxygen atoms has been explained using the popular chemical concepts, viz., Pearson's Hard-Soft-Acid-Base (HSAB) principle and the frontier orbital theory of chemical reactivity as proposed by Fukui. Detailed analysis within the framework of the HSAB principle indicates that the presence of softer nitrogen atoms in the phenanthroline moiety (which also act as donors to the metal ion) has a profound influence in changing the soft nature of the actinide ion, which in turn binds with the hard oxygen atoms in a stronger way as compared to the valence isoelectronic lanthanide ion. Also, the trends in the variation of calculated values of the metal-ligand bond distances and the corresponding complex formation energies have been rationalized using the Fukui reactivity indices corresponding to the metal ions and the donor sites. All the calculations have also been done in the presence of solvent. The "intra-ligand synergistic effect" demonstrated here for PDA or TCA1 with soft and hard donor centers might be very important in designing new ligands for selective extraction of various metal ions in a competitive environment. However, for TCA and THIO ligands with only soft donor centers, "intra-ligand synergism" may not be very efficient although

  14. Copper(II)-lanthanide(III) coordination polymers constructed from pyridine-2,5-dicarboxylic acid: Preparation, crystal structure and photoluminescence

    SciTech Connect

    Xia Zhengqiang; Wei Qing; Chen Sanping; Feng Xinming; Xie Gang; Qiao Chengfang; Zhang Guochun; Gao Shengli

    2013-01-15

    A series of 3d-4f heterometallic coordination polymers, formulated as {l_brace} [Cu{sub 3}Ln{sub 2}(pydc){sub 6}(H{sub 2}O){sub 12}]{center_dot}4H{sub 2}O{r_brace} {sub n} [Ln=Tb (1), Eu (2), Dy (3), Ho (4), Lu (5)], {l_brace} [CuNd{sub 2}(pydc){sub 4}(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O{r_brace} {sub n} (6) and {l_brace} [Cu{sub 3}Pr{sub 2}(pydc){sub 6}(H{sub 2}O){sub 13}]{center_dot}4H{sub 2}O{r_brace} {sub n} (7) (where H{sub 2}pydc=pyridine-2,5-dicarboxylic acid), have been hydrothermally prepared by reactions of H{sub 2}pydc ligand with lanthanide ions in the presence of Cu(II) ion. X-ray crystal structure analysis reveals that these compounds exhibit rich structural chemistry. 1-5 are isomorphous and present a two-dimensional network constructed from Ln{sub 2}Cu{sub 2}L{sub 2}(H{sub 2}O){sub 2} SBU rings and CuL{sub 2}(H{sub 2}O) building blocks. In 6, two-dimensional ladder-like layers based on Nd(III) belts and CuL{sub 2}O{sub 2} units are assembled by H{sub 2}pydc ligands into a three-dimensional open framework. Polymer 7 displays a two-dimensional wave-like layer structure containing two distinct ring units, in which a new coordination mode of the pydc{sup 2-} ligand is observed. The results indicate that the coordination flexibility of the pydc{sup 2-} ligand and lanthanide contraction effect play cooperative roles in the formation of coordination polymers with different polymeric architectures. Compounds 1-2 exhibit intense green and red luminescence emission characteristics of Tb(III) and Eu(III), respectively. Furthermore, elemental analyses (EA), infrared spectra (IR) and thermogravimetric analyses (TGA) of these compounds were also studied. - Graphical abstract: Seven 3d-4f heterometallic coordination polymers were synthesized by reactions of H{sub 2}pydc with lanthanide metal ions in the presence of Cu{sup 2+}, the effects of Cu{sup 2+} on the structures and photoluminescent properties of Ln-pydc{sup 2-} systems were investigated. Highlights

  15. Distributions of low molecular weight dicarboxylic acids, ketoacids and α-dicarbonyls in the marine aerosols collected over the Arctic Ocean during late summer

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Ono, K.; Tachibana, E.; Charriére, B.; Sempéré, R.

    2012-11-01

    Oxalic and other small dicarboxylic acids have been reported as important water-soluble organic constituents of atmospheric aerosols from different environments. Their molecular distributions are generally characterized by the predominance of oxalic acid (C2) followed by malonic (C3) and/or succinic (C4) acids. In this study, we collected marine aerosols from the Arctic Ocean during late summer in 2009 when sea ice was retreating. The marine aerosols were analyzed for the molecular distributions of dicarboxylic acids as well as ketocarboxylic acids and α-dicarbonyls to better understand the source of water-soluble organics and their photochemical processes in the high Arctic marine atmosphere. We found that diacids are more abundant than ketoacids and α-dicarbonyls, but their concentrations are generally low (< 30 ng m-3), except for one sample (up to 70 ng m-3) that was collected near the mouth of Mackenzie River during clear sky condition. Although the molecular compositions of diacids are in general characterized by the predominance of oxalic acid, a depletion of C2 was found in two samples in which C4 became the most abundant. Similar depletion of oxalic acid has previously been reported in the Arctic aerosols collected at Alert after polar sunrise and in the summer aerosols from the coast of Antarctica. Because the marine aerosols that showed a depletion of C2 were collected under the overcast and/or foggy conditions, we suggest that a photochemical decomposition of oxalic acid may have occurred in aqueous phase of aerosols over the Arctic Ocean via the photo dissociation of oxalate-Fe (III) complex. We also determined stable carbon isotopic compositions (δ13C) of bulk aerosol carbon and individual diacids. The δ13C of bulk aerosols showed -26.5‰ (range: -29.7 to -24.7‰, suggesting that marine aerosol carbon is derived from both terrestrial and marine organic materials. In contrast, oxalic acid showed much larger δ13C values (average: -20.9‰, range

  16. Distributions of low molecular weight dicarboxylic acids, ketoacids and α-dicarbonyls in the marine aerosols collected over the Arctic Ocean during late summer

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Ono, K.; Tachibana, E.; Charriére, B.; Sempéré, R.

    2012-08-01

    Oxalic and other small dicarboxylic acids have been reported as important water-soluble organic constituents of atmospheric aerosols from different environments. Their molecular distributions are generally characterized by the predominance of oxalic acid (C2) followed by malonic (C3) and/or succinic (C4) acids. In this study, we collected marine aerosols from the Arctic Ocean during late summer in 2009 when sea ice is retreated. The marine aerosols were analyzed for the molecular distributions of dicarboxylic acids as well as ketocarboxylic acids and α-dicarbonyls to better understand the source of water-soluble organics and their photochemical processes in the high Arctic marine atmosphere. We found that diacids are more abundant than ketoacids and α-dicarbonyls, but their concentrations are generally low (< 30 ng m-3), except for one sample (up to 70 ng m-3) that was collected near the mouth of Mackenzie River during clear sky condition. Although the molecular compositions of diacids are in general characterized by the predominance of oxalic acid, a depletion of C2 was found in two samples in which C4 became the most abundant. Similar depletion of oxalic acid has previously been reported in the Arctic aerosols collected at Alert after polar sunrise and in the summer aerosols from the coastal Antarctica. Because the marine aerosols that showed a depletion of C2 were observed under the overcast and/or foggy conditions, we suggest that a photochemical decomposition of oxalic acid may have occurred in aqueous phase of aerosols over the Arctic Ocean via the photo dissociation of oxalate-Fe (III) complex. We also determined stable carbon isotopic compositions (δ13C) of bulk aerosol carbon and individual diacids. The δ13C of bulk aerosols showed -26.5‰ (range: -29.7‰ to -24.7‰), suggesting that marine aerosol carbon is derived from both terrestrial and marine organic materials. In contrast, oxalic acid showed much larger δ13C values (average: -20.9‰, range

  17. 2,3-Pyridine dicarboxylic acid functionalized gold nanoparticles: Insight into experimental conditions for Cr(3+) sensing.

    PubMed

    Shaikh, Ruqaya; Memon, Najma; Solangi, Amber R; Shaikh, Huma I; Agheem, Muhammad Hassan; Ali, Syed Abid; Shah, Muhammad Raza; Kandhro, Aftab

    2017-02-15

    Selectivity of gold nanoparticles (AuNPs) depends upon surface functionality; small changes in structure or concentration bring significant changes in the behavior of AuNPs. In this study, citrate-capped AuNPs were functionalized with ortho-dicarboxylate substituted pyridine (2,3-PDCA) and detailed studies on experimental conditions were carried out to check the stability of AuNPs and response for Cr(3+). Stability of PDCA-AuNPs was found sensitive to the pH, ionic strength of buffer and its type. Capping behavior of PDCA on C-AuNPs was examined by FTIR spectroscopy. Surface morphology and size of synthesized AuNPs were confirmed by AFM, XRD, and DLS techniques where particles were found 11nm in size, monodisperse and spherical in shape. Interaction of stabilized AuNPs was tested with various metal ions; where Cr(3+) induced the changes in localized surface plasmon band (LSPR) of PDCA-AuNPs which leads to a color change from wine red to violet blue. The phenomenon is explained as cooperative effect of citrate and pyridine nitrogen on surface of AuNPs in contrary to meta-dicarboxylate substituted pyridine derivatives. Further, under optimized and controlled conditions Cr(3+) shows linear response with decrease in absorbance at LSPR intensity of AuNPs (518nm). Moreover, to demonstrate the applicability of method, Cr(3+) was determined in the presence of Cr (VI) which shows 96% recovery.

  18. 2,3-Pyridine dicarboxylic acid functionalized gold nanoparticles: Insight into experimental conditions for Cr3 + sensing

    NASA Astrophysics Data System (ADS)

    Shaikh, Ruqaya; Memon, Najma; Solangi, Amber R.; Shaikh, Huma I.; Agheem, Muhammad Hassan; Ali, Syed Abid; Shah, Muhammad Raza; Kandhro, Aftab

    2017-02-01

    Selectivity of gold nanoparticles (AuNPs) depends upon surface functionality; small changes in structure or concentration bring significant changes in the behavior of AuNPs. In this study, citrate-capped AuNPs were functionalized with ortho-dicarboxylate substituted pyridine (2,3-PDCA) and detailed studies on experimental conditions were carried out to check the stability of AuNPs and response for Cr3 +. Stability of PDCA-AuNPs was found sensitive to the pH, ionic strength of buffer and its type. Capping behavior of PDCA on C-AuNPs was examined by FTIR spectroscopy. Surface morphology and size of synthesized AuNPs were confirmed by AFM, XRD, and DLS techniques where particles were found 11 nm in size, monodisperse and spherical in shape. Interaction of stabilized AuNPs was tested with various metal ions; where Cr3 + induced the changes in localized surface plasmon band (LSPR) of PDCA-AuNPs which leads to a color change from wine red to violet blue. The phenomenon is explained as cooperative effect of citrate and pyridine nitrogen on surface of AuNPs in contrary to meta-dicarboxylate substituted pyridine derivatives. Further, under optimized and controlled conditions Cr3 + shows linear response with decrease in absorbance at LSPR intensity of AuNPs (518 nm). Moreover, to demonstrate the applicability of method, Cr3 + was determined in the presence of Cr (VI) which shows 96% recovery.

  19. Fluorescence and co-fluorescence of Tb(3+) and Eu(3+) in acetonitrile using 2,6-pyridine dicarboxylic acid as ligand.

    PubMed

    Maji, S; Kumar, Satendra; Sankaran, K

    2015-01-25

    Fluorescence from Tb(3+) and Eu(3+) complexed with 2,6-pyridine dicarboxylic acid (PDA) has been studied using acetonitrile (MeCN) as solvent. The enhancement in fluorescence intensity because of non-aqueous environment provided by the MeCN is less significant, where as fluorescence enhancement of more than two orders of magnitude has been observed with the addition of La(3+); a process known as co-fluorescence in MeCN. The present study demonstrates for the first time co-fluorescence of Tb(3+) and Eu(3+) with excitation through the absorption of PDA. Intermolecular energy transfer is believed to be responsible for co-fluorescence enhancement and it becomes possible as the quenching due to water at the secondary coordination spheres of Tb(3+) and Eu(3+) is reduced when MeCN is used as solvent.

  20. Fluorescence and co-fluorescence of Tb3+ and Eu3+ in acetonitrile using 2,6-pyridine dicarboxylic acid as ligand

    NASA Astrophysics Data System (ADS)

    Maji, S.; Kumar, Satendra; Sankaran, K.

    2015-01-01

    Fluorescence from Tb3+ and Eu3+ complexed with 2,6-pyridine dicarboxylic acid (PDA) has been studied using acetonitrile (MeCN) as solvent. The enhancement in fluorescence intensity because of non-aqueous environment provided by the MeCN is less significant, where as fluorescence enhancement of more than two orders of magnitude has been observed with the addition of La3+; a process known as co-fluorescence in MeCN. The present study demonstrates for the first time co-fluorescence of Tb3+ and Eu3+ with excitation through the absorption of PDA. Intermolecular energy transfer is believed to be responsible for co-fluorescence enhancement and it becomes possible as the quenching due to water at the secondary coordination spheres of Tb3+ and Eu3+ is reduced when MeCN is used as solvent.

  1. Limits of detections for the determination of mono- and dicarboxylic acids using gas and liquid chromatographic methods coupled with mass spectrometry

    PubMed Central

    Št’ávová, Jana; Beránek, Josef; Nelson, Eric P.; Diep, Bonnie A.; Kubátová, Alena

    2011-01-01

    The chromatographic separation and instrumental limits of detection (LODs) were obtained for a broad range of C1-C18 monocarboxylic (MCAs) and C2-C14 dicarboxylic acids (DCAs) employing either chemical derivatization followed by gas chromatography-mass spectrometry and flame ionization detection (GC-MS/FID) or direct analysis with liquid chromatography high resolution MS and tandem MS (LC-MS). Suitability, efficiency and stability of reaction products for several derivatization agents used for esterification (BF3/butanol), and trimethysilylation, including trimethylsilyl-N-N-dimethylcarbamate (TMSDMC) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) were evaluated. The lowest limits of detection for the majority of compounds below 10 pg (with the exception of acetic acid) were obtained for derivatization with BF3/butanol followed by GC-MS in the total ion current (TIC) mode. Further improvements were achieved when applying either selected ion monitoring (SIM), which decreased the LODs to 1–4 pg or a combination of SIM and TIC (SITI) (2–5 pg). GC-FID provided LODs comparable to those obtained by GC-MS TIC. Both trimethylsilylation (followed by GC-MS) and direct LC-MS/MS analysis yielded LODs of 5– 40 pg for most of the acids. For volatile acids the LODs were higher, e.g., 25 and 590 ng for TMSDMC and BSTFA derivatized formic acid, respectively whereas the LC-MS methods did not allow for the analysis of formic acid at all. PMID:21185238

  2. A 3D POM-MOF composite based on Ni(ΙΙ) ion and 2,2‧-bipyridyl-3,3‧-dicarboxylic acid: Crystal structure and proton conductivity

    NASA Astrophysics Data System (ADS)

    Wei, Meilin; Wang, Xiaoxiang; Sun, Jingjing; Duan, Xianying

    2013-06-01

    We have succeeded in constructing a 3D POM-MOF, {H[Ni(Hbpdc)(H2O)2]2[PW12O40]·8H2O}n (H2bpdc=2,2'-bipyridyl-3,3'-dicarboxylic acid), by the controllable self-assembly of H2bpdc, Keggin-anions and Ni2+ ions based on the electrostatic and coordination interactions. Interestingly, Hbpdc- as polydentate organic ligands and Keggin-anion as polydentate inorganic ligands are covalently linked transition-metal nickel at the same time. The title complex represents a new example of introducing the metal N-heterocyclic multi-carboxylic acid frameworks into POMs chemistry. Based on Keggin-anions being immobilized as part of the metal N-heterocyclic multi-carboxylic acid framework, the title complex realizes four approaches in the 1D hydrophilic channel used to engender proton conductivity in MOFs. Its water adsorption isotherm at room temperature and pressure shows that the water content in it was 31 cm3 g-1 at the maximum allowable humidity, corresponding to 3.7 water molecules per unit formula. It exhibits good proton conductivities (10-4-10-3 S cm-1) at 100 °C in the relative humidity range 35-98%. The corresponding activation energy (Ea) of conductivity was estimated to be 1.01 eV.

  3. Highly Preorganized Ligand 1,10-Phenanthroline-2,9-dicarboxylic Acid for the Selective Recovery of Uranium from Seawater in the Presence of Competing Vanadium Species

    SciTech Connect

    Lashley, Mark A.; Ivanov, Alexander S.; Bryantsev, Vyacheslav S.; Dai, Sheng; Hancock, Robert D.

    2016-09-30

    Studies of the complexation of new promising ligands with uranyl (UO22+) and other seawater cations can aid the development of more efficient, selective, and robust sorbents for the recovery of uranium from seawater. Here, we propose that the ligand design principles based on structural preorganization can be successfully applied to obtain a dramatic enhancement in UO22+ ion binding affinity and selectivity. This concept is exemplified through the investigation of the com-plexes of UO22+, VO2+, and VO2+ with the highly preorganized ligand PDA (1,10-phenanthroline-2,9-dicarboxylic acid) using a combination of fluores-cence and absorbance techniques, along with den-sity functional theory (DFT) calculations. Moreover, the measured stability constant value, log K1, of 16.5 for the UO22+/PDA complex is very high compared to uranyl complexes with other dicarboxylic ligands. Moreover, PDA exhibits strong selectivity for uranyl over vanadium ions, since the determined sta-bility constant values of the PDA complexes of the vanadium ions are quite low (V(IV) log K1 = 7.4, V(V) = 7.3). Finally, the structures of the corresponding UO22+, VO2+, and VO2+ complexes with PDA were identified by systematic DFT calculations, and helped to interpret the stronger binding affinity for uranium over the vanadium ions. Due to its high chemical stability, selectivity, and structural preor-ganization for UO22+ complexation, PDA is a very promising candidate that can be potentially used in the development of novel adsorbent materials for the selective extraction of uranium from sea-water.

  4. Highly Preorganized Ligand 1,10-Phenanthroline-2,9-dicarboxylic Acid for the Selective Recovery of Uranium from Seawater in the Presence of Competing Vanadium Species

    DOE PAGES

    Lashley, Mark A.; Ivanov, Alexander S.; Bryantsev, Vyacheslav S.; ...

    2016-09-30

    Studies of the complexation of new promising ligands with uranyl (UO22+) and other seawater cations can aid the development of more efficient, selective, and robust sorbents for the recovery of uranium from seawater. Here, we propose that the ligand design principles based on structural preorganization can be successfully applied to obtain a dramatic enhancement in UO22+ ion binding affinity and selectivity. This concept is exemplified through the investigation of the com-plexes of UO22+, VO2+, and VO2+ with the highly preorganized ligand PDA (1,10-phenanthroline-2,9-dicarboxylic acid) using a combination of fluores-cence and absorbance techniques, along with den-sity functional theory (DFT) calculations. Moreover,more » the measured stability constant value, log K1, of 16.5 for the UO22+/PDA complex is very high compared to uranyl complexes with other dicarboxylic ligands. Moreover, PDA exhibits strong selectivity for uranyl over vanadium ions, since the determined sta-bility constant values of the PDA complexes of the vanadium ions are quite low (V(IV) log K1 = 7.4, V(V) = 7.3). Finally, the structures of the corresponding UO22+, VO2+, and VO2+ complexes with PDA were identified by systematic DFT calculations, and helped to interpret the stronger binding affinity for uranium over the vanadium ions. Due to its high chemical stability, selectivity, and structural preor-ganization for UO22+ complexation, PDA is a very promising candidate that can be potentially used in the development of novel adsorbent materials for the selective extraction of uranium from sea-water.« less

  5. Study of supramolecular frameworks having aliphatic dicarboxylic acids, N,N‧-bis(salicyl)ethylenediamine and N,N‧-bis(salicyl)butylenediamine

    NASA Astrophysics Data System (ADS)

    Goel, Nidhi; Kumar, Naresh

    2014-08-01

    The reaction of bases (L1 and L2) (where L1 = N,N‧-bis(salicyl)ethylenediamine, L2 = N,N‧-bis(salicyl)butylenediamine) with dicarboxylic acids [adipic acid (1,6-Hexanedioic acid, AA), pimelic acid (1,7-Heptanedioic acid, PA) and suberic acid (1,8-Octanedioic acid, SUA] yielded the corresponding six new ionic salts viz., [1/2L1H+ṡ1/2AA-ṡ1/2AA] (1), [2 × 1/2L1H+ṡPA2-ṡCHCl3] (2) [1/2L1H+ṡ1/2SUA-] (3), [1/2L2H+ṡ1/2AA-ṡ2CH3OH] (4), [1/2L2H+ṡ1/2PA-] (5) and [1/2L2H+ṡ1/2SUA-] (6), respectively. Theses salts were characterized by elemental analysis, FT-IR, NMR, X-ray crystallography, and theoretically by means of Gaussian 09. The X-ray crystallographic studies revealed that the proton transfer occurred from acid to base. It also demonstrated that different type of hydrogen bond interactions between cations and anions were responsible for the supramolecular frameworks. The optimized structures of these salts were calculated in terms of the density functional theory. The curve fitting analysis between experimental and simulated data of structural parameters was done, and found statistically close. The orientation of molecules was remained same in both the gas and solid phases. The thermal studies of these salts were investigated by TG-DTG.

  6. Spatio-temporal distributions of dicarboxylic acids, ω-oxocarboxylic acids, pyruvic acid, α-dicarbonyls and fatty acids in the marine aerosols from the North and South Pacific

    NASA Astrophysics Data System (ADS)

    Hoque, Mir Md. Mozammal; Kawamura, Kimitaka; Uematsu, Mitsuo

    2017-03-01

    Aerosol samples (TSP) were collected during a cruise in the North (3°05‧N-34°02‧N) and South (6°59‧S-25°46‧S) Pacific to investigate the spatio-temporal distributions of water-soluble dicarboxylic acids and related compounds. The molecular distributions of diacids were characterized by the predominance of oxalic (C2) acid followed by malonic (C3) and then succinic (C4) acid. However, we found a predominance of C4 over C3 in the aerosol sample that was collected in the western North Pacific Rim with a heavy influence from continental air masses. Atmospheric abundances of short chain diacids (C2-C4) are 2-3 times higher in the North Pacific than in the South Pacific. During the cruise, abundances of C2 in the western North Pacific are 5 times higher than those in the rest of the samples collected. Moreover, the aerosol samples collected in the western North Pacific demonstrated that glyoxylic (ωC2) acid and methylglyoxal (MeGly) were dominant together with C2. We found a strong correlation between C2 and ωC2 (r = 0.87) and C2 and MeGly (r = 0.97) in the western North Pacific aerosols but the correlations are significantly weak in the samples from the central North Pacific and Southern Ocean. Diacids were found to account for 1.6 to 14% of organic carbon with higher values in the western North Pacific. These results, together with 7-day backward air mass trajectories, indicate that ωC2 and MeGly are both originated from the photochemical oxidation of continent-derived organic precursors including isoprene, which can serve as precursors for the production of C2 during long-range atmospheric transport.

  7. Bio-inspired nitrile hydration by peptidic ligands based on L-cysteine, L-methionine or L-penicillamine and pyridine-2,6-dicarboxylic acid.

    PubMed

    Byrne, Cillian; Houlihan, Kate M; Devi, Prarthana; Jensen, Paul; Rutledge, Peter J

    2014-12-12

    Nitrile hydratase (NHase, EC 4.2.1.84) is a metalloenzyme which catalyses the conversion of nitriles to amides. The high efficiency and broad substrate range of NHase have led to the successful application of this enzyme as a biocatalyst in the industrial syntheses of acrylamide and nicotinamide and in the bioremediation of nitrile waste. Crystal structures of both cobalt(III)- and iron(III)-dependent NHases reveal an unusual metal binding motif made up from six sequential amino acids and comprising two amide nitrogens from the peptide backbone and three cysteine-derived sulfur ligands, each at a different oxidation state (thiolate, sulfenate and sulfinate). Based on the active site geometry revealed by these crystal structures, we have designed a series of small-molecule ligands which integrate essential features of the NHase metal binding motif into a readily accessible peptide environment. We report the synthesis of ligands based on a pyridine-2,6-dicarboxylic acid scaffold and L-cysteine, L-S-methylcysteine, L-methionine or L-penicillamine. These ligands have been combined with cobalt(III) and iron(III) and tested as catalysts for biomimetic nitrile hydration. The highest levels of activity are observed with the L-penicillamine ligand which, in combination with cobalt(III), converts acetonitrile to acetamide at 1.25 turnovers and benzonitrile to benzamide at 1.20 turnovers.

  8. Synthesis, structure-activity relationships, and in vitro antibacterial and antifungal activity evaluations of novel pyrazole carboxylic and dicarboxylic acid derivatives.

    PubMed

    Mert, Samet; Kasımoğulları, Rahmi; İça, Tuba; Çolak, Ferdağ; Altun, Ahmet; Ok, Salim

    2014-05-06

    A series of pyrazole-3-carboxylic acid and pyrazole-3,4-dicarboxylic acid derivatives were synthesized, the structures were confirmed by their NMR ((1)H and (13)C) and FT-IR spectra, and elemental analyses. The antibacterial and antifungal activities of the compounds against five bacterial and five fungal pathogens were screened using modified agar well diffusion assay. Most of the molecules have inhibitory effects on both standard and clinical Candida albicans strains. However, only the molecules 8, 10, 21, and 22 demonstrate some inhibitory effects on Candida parapsilosis, Candida tropicalis, and Candida glabrata strains. The structure-antifungal activity relationships of the compounds on the C. albicans strains were investigated by electron-conformational method. The pharmacophores and antipharmacophores responsible for the inhibition and non-inhibition of the C. albicans strains were obtained by electronic and geometrical characteristics of the reactive fragments of the molecules. These fragments along with the associated parameters can be used in designing the future more potent antifungal agents. It has been shown that both the positions of electronegative atoms like F and O in the pyrazole substituents and the amount of the associated charges on such atoms are crucial in regulating the strength of antifungal activity for the C. albicans strain.

  9. Three Pb{sup II} coordination polymers based on 2-(pyridin-2-yl)-1H-imidazole-4,5-dicarboxylic acid: Syntheses, crystal structures, and fluorescent properties

    SciTech Connect

    Yu, Xiao-Yang; Xin, Rui; Gao, Wei-Ping; Wang, Na; Zhang, Xiao; Yang, Yan-Yan; Qu, Xiao-Shu

    2013-08-15

    Three lead coordination polymers, [PbCl(C{sub 10}H{sub 6}N{sub 3}O{sub 4})(H{sub 2}O)·H{sub 2}O]{sub n} (1), [Pb(C{sub 10}H{sub 6}N{sub 3}O{sub 4}){sub 2}(H{sub 2}O)]{sub n} (2) and [Pb{sub 3}(C{sub 10}H{sub 5}N{sub 3}O{sub 4}){sub 3}]{sub n} (3) (C{sub 10}H{sub 7}N{sub 3}O{sub 4}=2-(pyridin-2-yl)-1H-imidazole-4,5-dicarboxylic acid), have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. In 1, Cl anions connected neighboring wave-like 2D layers, which are constructed with left- and right-handed helical chains, into a 3D network structure with a (6{sup 3})(6{sup 5}·8) topology. In 2, Pb cations are linked into a 3D 6{sup 6} network with left- and right-handed helixes by μ{sub 2}-bridging C{sub 10}H{sub 6}N{sub 3}O{sub 4}{sup −} ligands. In 3, C{sub 10}H{sub 5}N{sub 3}O{sub 4}{sup 2−} ligands link Pb{sub 6}O{sub 12} clusters into a 3D (4{sup 12}·6{sup 3}) network. Their fluorescent properties were also investigated. - Graphical abstract: Three 3D lead compounds based on 2-(pyridin-2-yl)-1H-imidazole-4,5-dicarboxylic acid have been hydrothermally synthesized. Four new coordination modes of the organic ligand are first reported. Display Omitted - Highlights: • Three new Pb(II) complexes have been synthesized and characterized. • Left- and right-handed helical chains can be found in the 3D networks of 1 and 2. • Pb{sub 6}O{sub 12} clusters are connected into (4{sup 12}·6{sup 3}) network in 3.

  10. Identification of keto- and hydroxy-dicarboxylic acids in remote marine aerosols from the western North Pacific: GC and GC/TOF-MS measurements

    NASA Astrophysics Data System (ADS)

    Vani, D.; Kawamura, K.; Tachibana, E.; Boreddy, S. K. R.

    2015-12-01

    Dicarboxylic acids (diacids) are dominant components of organic aerosols in the atmosphere. They contribute significantly to the total aerosol mass and have a serious impacts on global climate changes. However, studies on keto- and hydroxy-diacids in marine aerosols are limited. Compare to diacids, keto- and hydroxy-diacids are more hygroscopic due to the additional polar groups (OH and CO) and, hence, acts as cloud condensation nuclei (CCN). Molecular characterization of these compounds provides insight into organic aerosols sources and transformation pathways. We collected marine aerosols from remote Chichijima Island in the western North Pacific from December 2010 to November 2011 and studied for water-soluble keto- and hydroxy-diacids. Carboxyl groups were derivatized to dibutyl esters with 14% boron trifluoride/n-butanol, whereas hydroxyl groups were derivatized to trimethylsilyl ethers using N,O-Bis (trimethylsilyl) trifluoroacetamide (BSTFA). After two-step derivatization, samples were injected to GC, GC/MS and GC/TOF-MS. In the GC chromatogram, we detected several new peaks after BSTFA derivatization of dibutyl ester fraction. Based on mass spectral interpretation, we found these peaks as homologues series of hydroxy-diacids and keto-diacids. Some of these hydroxy-diacids have been individually reported in literature in the laboratory photo-oxidation experiments and forest environments samples. But, there are no evidences to prove their sources and formation mechanism in the atmosphere. Here, we report for the first time homologous series of hydroxy-diacids (hC3di-hC6di) and keto-diacid (oxaloacetic acid, enol and keto forms) in remote marine atmosphere. Molecular distributions of hydroxy-diacids generally showed the predominance of malic acid followed by tartronic acid. Both hydroxy- and keto-diacids show significant positive correlation with oxalic acid and SO42-, suggesting that they are generated in the atmosphere and play an important role in the

  11. Cadmium and zinc chain and cluster-based layered coordination polymers prepared from flexible-arm aromatic ortho-dicarboxylic acids and 4-pyridylnicotinamide

    NASA Astrophysics Data System (ADS)

    Kraft, Peter E.; Uebler, Jacob W.; LaDuca, Robert L.

    2013-04-01

    Hydrothermal reaction of a d10-metal nitrate salt, a flexible-arm aromatic ortho-dicarboxylic acid, and 4-pyridylnicotinamide (4-pna) afforded four new crystalline coordination polymers, which were characterized by single-crystal X-ray diffraction. [Cd(Hhmph)(nic)(H2O)2]n (1, hmph = homophthalate, nic = nicotinate) is a 1-D coordination polymer chain compound whose nic ligands were generated in situ via 4-pna hydrolysis. Addition of base and a shorter reaction duration afforded [Cd(hmph)(4-pna)]n (2), which has dinuclear [Cd2(hmph)2] dimers linked into a 1-D ladder polymer via 4-pna ligands. A similar chain structure, albeit with a different hmph binding mode, is seen in [Zn(hmph)(4-pna)]n (3). {[Zn2(phda)2(4-pna)2(H2O)]ṡH2O}n (4, phda = 1,2-phenylenediacetate) has both anti-syn bridged [Zn2(OCO)2] ring dimers and [Zn2(OCO)4] paddlewheel dimers, linked into a layered coordination polymer by dipodal 4-pna ligands. Luminescent properties of these new materials are also presented.

  12. Cytotoxic Activity of Bioactive Compound 1, 2- Benzene Dicarboxylic Acid, Mono 2- Ethylhexyl Ester Extracted from a Marine Derived Streptomyces sp. VITSJK8.

    PubMed

    Krishnan, Kannabiran; Mani, Abirami; Jasmine, Subashini

    2014-01-01

    Marine Streptomyces are prolific producers of majority of bioactive secondary metabolites which are used in pharmaceutical industry as effective drugs against life threatening diseases. The cytotoxic activity of the pure compound 1, 2- benzene dicarboxylic acid, mono 2- ethylhexyl ester (DMEHE) from marine derived actinomycete Streptomyces sp. VITSJK8 was investigated against mouse embryonic fibroblast (NIH 3T3) and human keratinocyte (HaCaT) normal cell lines, human hepatocellular liver carcinoma (HepG 2) and human breast adenocarcinoma (MCF-7) cell lines by using MTT assay. The compound DMEHE exhibited IC 50 values of 42, 100, 250 and 500 µg/ ml against HepG2, MCF-7, HaCaT and NIH 3T3 cell lines, respectively. The effect of DMEHE on the growth of cancer cell lines was expressed as the % of viability. Cell viability was recorded as 67.7%, 78.14%, 82.23% and 96. 11% in HepG2, MCF-7, HaCaT and NIH 3T3 cells, respectively. The results of the study conclude that the bioactive compound isolated from the potential isolate Streptomyces sp. VITSJK8 exhibited cytotoxic activity against HepG2 and MCF- 7 cancer cell lines and low toxicity against normal HaCaT and NIH 3T3 cell lines.

  13. Structures and standard molar enthalpies of formation of a series of Ln(III)-Cu(II) heteronuclear compounds with pyrazine-2,3-dicarboxylic acid

    NASA Astrophysics Data System (ADS)

    Yang, Qi; Xie, Gang; Wei, Qing; Chen, Sanping; Gao, Shengli

    2014-07-01

    Fifteen lanthanide-copper heteronuclear compounds, formulated as [CuLn2(pzdc)4(H2O)6]·xH2O (1-6(x=2), 8(x=3), 9-10(x=4); [CuLn2(pzdc)4(H2O)4]·xH2O (7, 12-13, 15(x=4), 14(x=5), 11(x=8) (Ln(III)=La(1); Ce(2); Pr(3); Nd(4); Sm(5); Eu(6); Gd(7); Tb(8); Dy(9); Ho(10); Er(11); Tm(12); Yb(13); Lu(14); Y(15); H2pzdc (C6H4N2O4)=pyrazine-2,3-dicarboxylic acid) have been hydrothermally synthesized. All compounds were characterized by element analysis, IR spectroscopy, single-crystal X-ray diffraction and thermal analysis. X-ray diffraction analyses confirm that all compounds are isostructural and feature a 3D brick-like framework structure with {4.62}2{42.62.82}{63}2{65.8}2 topology. Using 1 mol cm-3 HCl(aq) as calorimetric solvent, with an isoperibol solution-reaction calorimeter, the standard molar enthalpies of formation of all compounds were determined by a designed thermochemical cycle. In addition, solid state luminescence properties of compounds 5, 6, 8 and 9 were studied in the solid state.

  14. Cytotoxic Activity of Bioactive Compound 1, 2- Benzene Dicarboxylic Acid, Mono 2- Ethylhexyl Ester Extracted from a Marine Derived Streptomyces sp. VITSJK8

    PubMed Central

    Krishnan, Kannabiran; Mani, Abirami; Jasmine, Subashini

    2014-01-01

    Marine Streptomyces are prolific producers of majority of bioactive secondary metabolites which are used in pharmaceutical industry as effective drugs against life threatening diseases. The cytotoxic activity of the pure compound 1, 2- benzene dicarboxylic acid, mono 2- ethylhexyl ester (DMEHE) from marine derived actinomycete Streptomyces sp. VITSJK8 was investigated against mouse embryonic fibroblast (NIH 3T3) and human keratinocyte (HaCaT) normal cell lines, human hepatocellular liver carcinoma (HepG 2) and human breast adenocarcinoma (MCF-7) cell lines by using MTT assay. The compound DMEHE exhibited IC 50 values of 42, 100, 250 and 500 µg/ ml against HepG2, MCF-7, HaCaT and NIH 3T3 cell lines, respectively. The effect of DMEHE on the growth of cancer cell lines was expressed as the % of viability. Cell viability was recorded as 67.7%, 78.14%, 82.23% and 96. 11% in HepG2, MCF-7, HaCaT and NIH 3T3 cells, respectively. The results of the study conclude that the bioactive compound isolated from the potential isolate Streptomyces sp. VITSJK8 exhibited cytotoxic activity against HepG2 and MCF- 7 cancer cell lines and low toxicity against normal HaCaT and NIH 3T3 cell lines. PMID:25635251

  15. Comparison of dicarboxylic acids and related compounds in aerosol samples collected in Xi'an, China during haze and clean periods

    NASA Astrophysics Data System (ADS)

    Cheng, Chunlei; Wang, Gehui; Zhou, Bianhong; Meng, Jingjing; Li, Jianjun; Cao, Junji; Xiao, Shun

    2013-12-01

    PM10 aerosols from Xi'an, a mega city of China in winter and summer, 2009 were measured for secondary organic aerosols (SOA) (i.e., dicarboxylic acids (DCA), keto-carboxylic acids, and α-dicarbonyls), water-soluble organic (WSOC) and inorganic carbon (WSIC), elemental carbon (EC) and organic carbon (OC). Molecular compositions of SOA on haze and clean days in both seasons were compared to investigate their sources and formation mechanisms. DCA in the samples were 1843 ± 810 ng m-3 in winter and 1259 ± 781 ng m-3 in summer, respectively, which is similar and even higher than those measured in 2003. Oxalic acid (C2, 1162 ± 570 ng m-3 in winter and 1907 ± 707 ng m-3 in summer) is the predominant species of DCA, followed by t-phthalic (tPh) in winter and phthalic (Ph) in summer. Such a molecular composition is different from those in other Asian cities where succinic acid (C4) or malonic acid (C3) is the second highest species, which is mostly due to significant emissions from household combustion of coal and open burning of waste material in Xi'an. Mass ratios of C2/diacids, diacids/WSOC, WSOC/OC and individual diacid-C/WSOC are higher on the haze days than on the clean days in both seasons, suggesting an enhanced SOA production under the haze condition. We also found that the haze samples are acidic while the clean samples are almost neutral. Such a difference in particle acidity is consistent with the enhanced SOA production, because acid-catalysis is an important aqueous-phase formation pathway of SOA. Gly/mGly mass ratio showed higher values on haze days than on clean day in both seasons. We comprehensively investigated the ratio in literature and found a consistent pattern. Based on our observation results and those documented data we proposed for the first time that concentration ratio of Gly/mGly can be taken as an indicator of aerosol ageing.

  16. Dicarboxylic acid anhydride condensation with compounds containing active methylene groups. 4: Some 4-nitrophthalic anhydride condensation reactions

    NASA Technical Reports Server (NTRS)

    Oskaja, V.; Rotberg, J.

    1985-01-01

    By 4-nitrophthalic anhydride condensation with acetoacetate in acetic anhydride and triethylamine solution with subsequent breakdown of the intermediate condensation product, 5-nitroindanedione-1,3 was obtained. A 4-nitrophthalic anhydride with acetic anhydride, according to reaction conditions, may yield two products: in the presence of potassium acetate and at high temperatures 4-(or 5-)-nitro-2-acetylbenzoic acid is formed: in the presence of triethylamine and at room temperature 5-( or 6-)-nitrophthalic acetic acid is isolated. A 4-nitrophthalic anhydride and malonic acid in pyridine solution according to temperature yield either 5-( or 6-)-nitrophthalic acetic acid or 4-(or 5-)-nitro-2-acetylbenzoic acid.

  17. Unique (3,8)-connected lanthanide arenedisulfonate metal-organic frameworks containing benzimidazole-5,6-dicarboxylic acid co-ligand: Syntheses, structures and luminescence

    SciTech Connect

    Sun, Yan-Qiong; Liu, Qi; Zhong, Jie-Cen; Pan, Qun-Feng; Chen, Yi-Ping

    2013-10-15

    Two isostructural 3D lanthanide arenedisulfonate metal-organic frameworks (MOFs) [Ln(Hbidc)(nds){sub 0.5}(H{sub 2}O)]{sub n}(Ln=Eu(1), La(2)) have been successfully synthesized by the hydrothermal reaction of lanthanide oxide with 2,6-naphthalenedisulfonate sodium (Na{sub 2}nds) and an auxiliary ligand, 1H-benzimidazole-5,6-dicarboxylic acid (H{sub 3}bidc). The two complexes are both constructed from 2D [Ln(Hbidc)]{sup +} double layers pillared by nds{sup 2−} ligands to generate 3D (3, 8)-connected open-framework structures with 1D long narrow channels running along the a axis. From topological point of view, the 3D framework is a (3, 8)-connected tfz-d net. The weak interactions including N–H⋯O, O–H⋯O hydrogen bonds and π–π stacking are observed in 1. The 2D IR correlation spectroscopy was applied to study the molecular interactions induced by thermal perturbation. The emission spectra of 1 exhibit the characteristic transition of {sup 5}D{sub 0}→{sup 7}F{sub J}(J=0–4) of Eu(III). - Graphical abstract: Two isostructural 3D (3,8)-connected lanthanide arenedisulfonates were hydrothermally synthesized. The 2D IR correlation spectroscopy was applied to study the molecular interactions induced by thermal perturbation. Display Omitted - Highlights: • The first lanthanide arenedisulfonates incorporating fused-ring aromatic carboxylic acid. • Three-dimensional (3,8)-connected framework with tfz-d network topology. • The emission spectra of 1 exhibit the characteristic transition of {sup 5}D{sub 0}→{sup 7}F{sub J} (J=0–4) of Eu(III). • The 2D IR correlation spectroscopy was applied to study the molecular interactions.

  18. Furan-based benzene mono- and dicarboxylic acid derivatives as multiple inhibitors of the bacterial Mur ligases (MurC-MurF): experimental and computational characterization

    NASA Astrophysics Data System (ADS)

    Perdih, Andrej; Hrast, Martina; Pureber, Kaja; Barreteau, Hélène; Grdadolnik, Simona Golič; Kocjan, Darko; Gobec, Stanislav; Solmajer, Tom; Wolber, Gerhard

    2015-06-01

    Bacterial resistance to the available antibiotic agents underlines an urgent need for the discovery of novel antibacterial agents. Members of the bacterial Mur ligase family MurC-MurF involved in the intracellular stages of the bacterial peptidoglycan biosynthesis have recently emerged as a collection of attractive targets for novel antibacterial drug design. In this study, we have first extended the knowledge of the class of furan-based benzene-1,3-dicarboxylic acid derivatives by first showing a multiple MurC-MurF ligase inhibition for representatives of the extended series of this class. Steady-state kinetics studies on the MurD enzyme were performed for compound 1, suggesting a competitive inhibition with respect to ATP. To the best of our knowledge, compound 1 represents the first ATP-competitive MurD inhibitor reported to date with concurrent multiple inhibition of all four Mur ligases (MurC-MurF). Subsequent molecular dynamic (MD) simulations coupled with interaction energy calculations were performed for two alternative in silico models of compound 1 in the UMA/ d-Glu- and ATP-binding sites of MurD, identifying binding in the ATP-binding site as energetically more favorable in comparison to the UMA/ d-Glu-binding site, which was in agreement with steady-state kinetic data. In the final stage, based on the obtained MD data novel furan-based benzene monocarboxylic acid derivatives 8- 11, exhibiting multiple Mur ligase (MurC-MurF) inhibition with predominantly superior ligase inhibition over the original series, were discovered and for compound 10 it was shown to possess promising antibacterial activity against S. aureus. These compounds represent novel leads that could by further optimization pave the way to novel antibacterial agents.

  19. Seven hexamethylenetetramine (HMTA) complexes with mono- and dicarboxylic acids: analysis of packing modes of HMTA complexes in the literature.

    PubMed

    Lemmerer, Andreas

    2011-04-01

    The crystal structures of seven hexamethylenetetramine (HMTA) complexes, or co-crystals, with carboxylic acid donor molecules are reported to explain the link between the molecular structure of HMTA and the crystal structure of the co-crystals, i.e. the dimension and shape of their hydrogen-bonded assembly. A comprehensive and detailed literature survey of HMTA complexes (38), be they neutral co-crystals or salts, with molecules containing carboxylic acid and phenol functional groups reveals that in general two N acceptors are used for strong O-H···N interactions. Owing to the relative arrangement of two of the four N atoms, the most common type of assembly features one-dimensional zigzag chains. Weak interactions of the C-H···N type are formed by N atoms not involved in strong interactions. These chains also form the basis of two-dimensional assemblies. These one- and two-dimensional assemblies feature either two or three functional groups. If only one functional group is on the donor molecule, then wing or V-shaped zero-dimensional assemblies are formed, which can be considered to be the building blocks for one- and two-dimensional assemblies. In general, the HMTA molecules form two-dimensional layers which are stabilized by weak hydrogen bonds. Co-crystals with cyclohexylcarboxylic acid (I), 4-fluorobenzoic acid (II), 4-methylbenzoic acid (III) and cinnamic acid (IV) all feature the V-shaped zero-dimensional assemblies. Co-crystals with cis-1,4-cyclohexyldicarboxylic acid (VI) and trans-1,4-cyclohexylcarboxylic acid (VII) feature the zigzag chains and can be structurally derived from co-crystal (I). Co-crystal (V), with 4-nitrobenzoic acid, has solvent water included and features hydrogen bonding to all four N atoms of the HMTA molecule.

  20. Novel heteroleptic lanthanide organic frameworks containing pyridine-2,5-dicarboxylic acid and in situ generated piperazine-2,5-dicarboxylic acid from piperazine: Hydrothermal synthesis and luminescent properties

    SciTech Connect

    Ay, Burak; Yildiz, Emel; Kani, İbrahim

    2016-01-15

    Two novel 3D lanthanide metal-organic frameworks [Ln(pydc)(pip){sub 1/2}(H{sub 2}O] (Ln=Ce (1) and Pr (2), H{sub 2}pydc=2,5-pyridinedicarboxylic acid, H{sub 2}pip=2,5-piperazinedicarboxylic acid have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffractions (PXRD), and single-crystal X-ray diffractions. Field emission scanning electron microscopy (FESEM) was used for morphological analysis. Complexes are isostructural and feature interesting 3D frameworks. Both compounds crystallize in the monoclinic system, space group P2{sub 1}/c. Structural analyses of 1 and 2 show that Ln{sup 3+} ions connect with each other through H{sub 2}pydc and H{sub 2}pip. To the best of our knowledge, they are the first heteroleptic lanthanide polymers obtained through in situ 2,5-piperazinedicarboxylic acid syntheses. Moreover, thermal and luminescent properties of the compounds have been investigated. - Graphical abstract: Two novel 3D lanthanide metal-organic frameworks have been synthesized under hydrothermal conditions. Luminescent properties of the compounds in different temperatures have been also investigated. - Highlights: • New cerium and praseodymium coordination polymers based on N-O-bifunctional ligands have been synthesized In situ hydrothermal decarboxylation. • 2,5-pyridinedicarboxylic acid and piperazine were used as ligands. • In situ hydrothermal decarboxylation and formation of ligands were observed.

  1. Poly[μ-aqua-diaqua-(μ(2)-pyrazine-2,3-dicarboxyl-ato)dilithium(I)].

    PubMed

    Tombul, Mustafa; Guven, Kutalmis

    2009-11-28

    The asymmetric unit of the title compound, [Li(2)(C(6)H(2)N(2)O(4))(H(2)O)(3)](n), consists of two independent Li(+) cations, one pyrazine-2,3-dicarboxyl-ate dianion and three water mol-ecules. One of the Li(+) cations has a distorted tetra-hedral geometry, coordinated by one of the carboxyl-ate O atoms of the pyrazine-2,3-dicarboxyl-ate ligand and three O atoms from three water mol-ecules, whereas the other Li(+) cation has a distorted trigonal-bipyramidal geometry, coordinated by a carboxyl-ate O atom of a symmetry-related pyrazine-2,3-dicarboxyl-ate ligand, two water mol-ecules and a chelating pyrazine-2,3-dicarboxyl-ate ligand (by utilizing both N and O atoms) of an adjacent mol-ecule. The synthesis of a hydrated polymeric dinuclear lithium complex formed with two pyrazine-2,3-dicarboxylic acid ligands has been reported previously [Tombul et al. (2008a ▶). Acta Cryst. E64, m491-m492]. By comparision to the complex reported here, the dinuclear complex formed with two pyrazine-2,3-dicarboxylic acid ligands differs in the coordination geometry of both Li atoms. The crystal structure further features O-H⋯O and O-H⋯N hydrogen-bonding inter-actions involving the water mol-ecules and carboxyl-ate O atoms.

  2. Molecular distribution, seasonal variation, chemical transformation and sources of dicarboxylic acids and related compounds in atmospheric aerosols at remote marine Gosan site, Jeju Island

    NASA Astrophysics Data System (ADS)

    Kundu, S.; Kawamura, K.; Lee, M.

    2009-12-01

    : A homologous series of C2-C12 α, ω-dicarboxylic acids, ω-oxocarboxylic acids (C2-C9), pyruvic acid and α-dicarbonyls (C2-C3) were detected in atmospheric aerosols collected between April 2003 and April 2004 from remote marine Gosan site (33°29‧ N, 126°16‧ E) located in Jeju Island, South Korea. They were determined using a GC-FID and GC/MS. Total diacid concentration ranged from 130 to 1911 ng m-3 (av. 642 ng m-3), whereas total oxoacid concentration ranged from 7 to 155 ng m-3 (av. 43 ng m-3), and pyruvic acid and α-dicarbonyls ranged from 0.5 to 15 ng m-3 (av. 5 ng m-3) and 2-108 ng m-3 (av. 17.3 ng m-3), respectively. Oxalic (C2) acid was the most abundant in all seasons followed by malonic (C3) or succinic (C4) acid, and phthalic (Ph) acid. The concentration of diacids decreased with an increase in carbon number except for azelaic (C9) acid, which was more abundant than suberic (C8) acid. Glyoxylic acid was predominant ω-oxoacid contributing to 92% of total ω-oxoacid. Total diacids, oxoacids and dicarbonyls showed maximum concentrations in spring and occasionally in winter, while minimum concentrations were observed in summer. Air mass trajectory analysis suggests that either spring or winter maxima can be explained by strong continental outflow associated with cold front passages, while summer minima are associated with warm southerly flows, which transport clean marine air from low latitudes to Jeju Island. The comparison between total diacid concentration level of this study and other study results of urban and remote sites of East Asia reveals that Gosan site is more heavily influenced by the continental outflow from China. The seasonal variation of malonic/succinic (C3/C4), malic/succinic (hC4/C4), fumaric/maleic (F/M), oxalic/pyruvic (C2/Py) and oxalic/Glyoxal (C2/Gly) ratios showed maxima in summer due to an enhanced photo-production and degradation of diacids and related compounds. Throughout all seasons C3/C4 ratio at Gosan site, located

  3. The mae1 gene of Schizosaccharomyces pombe encodes a permease for malate and other C4 dicarboxylic acids.

    PubMed

    Grobler, J; Bauer, F; Subden, R E; Van Vuuren, H J

    1995-12-01

    The mae1 gene of the yeast Schizosaccharomyces pombe was identified on the basis of its ability to complement a mutant defective in the transport of malic acid. Analysis of the DNA sequence revealed an open reading frame of 1314 base pairs, encoding a polypeptide of 438 amino acids with a predicted molecular weight of 49 kDa. A hydropathy profile of the predicted amino acid sequence revealed a protein with ten membrane-spanning or associated domains and hydrophilic N- and C- termini. The predicted secondary structure of the protein in similar to models proposed for other integral membrane proteins from both prokaryotes and eukaryotes. The S. pombe mae1 gene encodes a single mRNA of 1.5 kb. The mea1 gene is expressed constitutively and is not subject to catabolite repression as was previously reported for the malate permease systems of Candida utilis and Hansenula anomala. The mae1 gene was mapped 2842 bp 5' to the MFml gene on chromosome I. Transport assays revealed that the mae1 gene encodes a permease involved in the uptake of L-malate, succinate and malonic acid.

  4. Cyclo-hexane-1,4-dicarb-oxy-lic acid-pyridinium-4-olate (1/1).

    PubMed

    Cruz-Enríquez, Adriana; Peinado-Guevara, Hector J; Reyes-Marquez, Viviana; Höpfl, Herbert; Campos-Gaxiola, José J

    2013-04-01

    In the title adduct, C5H5NO·C8H12O4, the heterocycle exists in its zwitterionic form. The cyclo-hexane ring exhibits a chair conformation with the carb-oxy-lic acid groups in equatorial and axial orientations. In the crystal, mol-ecules are linked through charge-assisted O-H⋯O(-), N(+)-H⋯O(-) and N(+)-H⋯O hydrogen bonds, and an additional series of C-H⋯O contacts, giving a pleated two-dimensional hydrogen-bonded network parallel to (-204).

  5. Two novel metal-organic frameworks based on linear dicarboxylic acid and 5-(4-pyridyl)tetrazole

    SciTech Connect

    Ren, Guo-Jian; Liu, Yan-Qing; Liu, Sui-Jun

    2015-12-15

    Two isomorphic metal-organic frameworks, [Co{sub 2}(4-Ptz){sub 2}(BDC)(DMA)]{sub n} (1) and [Co{sub 2}(4-Ptz){sub 2}(2-NH{sub 2}-BDC)(DMA)]{sub n} (2) (4-Ptz=5-(4-Pyridyl)tetrazole, H{sub 2}BDC=Terephthalic Acid, 2-NH{sub 2}-H{sub 2}BDC=2-Aminoterephthalic Acid, DMA=N,N-dimethylacetamide), have been successfully constructed through solvothermal reactions. Crystallographic data analysis reveals a binuclear Co(II) cluster-based structure for 1 and 2, which were constructed by bridging two neighboring Co(II) ions with teterazole rings of 4-Ptz ligand together with one DMA oxygen atom. Simplifying Co{sub 2} cluster as a 6-connecting node, complexes 1 and 2 reveal bcu-6 net. The CO{sub 2} adsorption isotherms measurement at 273 K manifests higher adsorption quantities for 2 (33.8 cm{sup 3}/g) than 1 (26.2 cm{sup 3}/g), which was attributed to the introduction of NH{sub 2}-group in 2. - Graphical abstract: Two mix-ligand based metal-organic frameworks were successfully constructed through solvothermal reaction. The two isomorphic complexes featured a topology of bcu-6 compared with 8-connected bcu net. Compound 2 with NH{sub 2}-function ligand showed improved CO{sub 2} adsorption. - Highlights: • Two novel MOFs have been synthesized by the strategy of mixed ligand. • Two isomorphic complexes featured a topology of bcu-6 compared with bcu net. • Compound 2 with NH{sub 2}-function ligand showed improved CO{sub 2} adsorption.

  6. A 3D POM–MOF composite based on Ni(ΙΙ) ion and 2,2´-bipyridyl-3,3´-dicarboxylic acid: Crystal structure and proton conductivity

    SciTech Connect

    Wei, Meilin; Wang, Xiaoxiang; Sun, Jingjing; Duan, Xianying

    2013-06-01

    We have succeeded in constructing a 3D POM–MOF, (H[Ni(Hbpdc)(H₂O)₂]₂[PW₁₂O₄₀]·8H₂O)n (H₂bpdc=2,2´-bipyridyl-3,3´-dicarboxylic acid), by the controllable self-assembly of H₂bpdc, Keggin-anions and Ni²⁺ ions based on the electrostatic and coordination interactions. Interestingly, Hbpdc⁻ as polydentate organic ligands and Keggin-anion as polydentate inorganic ligands are covalently linked transition-metal nickel at the same time. The title complex represents a new example of introducing the metal N-heterocyclic multi-carboxylic acid frameworks into POMs chemistry. Based on Keggin-anions being immobilized as part of the metal N-heterocyclic multi-carboxylic acid framework, the title complex realizes four approaches in the 1D hydrophilic channel used to engender proton conductivity in MOFs. Its water adsorption isotherm at room temperature and pressure shows that the water content in it was 31 cm³ g⁻¹ at the maximum allowable humidity, corresponding to 3.7 water molecules per unit formula. It exhibits good proton conductivities (10⁻⁴–10⁻³ S cm⁻¹) at 100 °C in the relative humidity range 35–98%. The corresponding activation energy (E{sub a}) of conductivity was estimated to be 1.01 eV. - Graphical abstract: A POM–MOF composite constructed by Keggin-type polyanion, Ni²⁺ and H₂bpdc shows good proton conductivities of 10⁻⁴–10⁻³ S cm⁻¹ at 100 °C under 35–98% RH. - Highlights: • A POM–MOF was constructed by combining metal N-heterocyclic multi-carboxylic acid framework and Keggin anion. • It opens a pathway for design and synthesis of multifunctional hybrid materials based on two building units. • Three types of potential proton-carriers have been assembled in the 1D hydrophilic channels of the POM–MOF. • It achieved such proton conductivities as 10⁻⁴–10⁻³ S cm⁻¹ at 100 °C in the RH range 35–98%.

  7. Two new coordination polymers constructed by naphthalene-1,4-dicarboxylic acid and 2,4-diamino-6-methyl-triazine

    SciTech Connect

    Li, Yamin; Xiao, Changyu; Zhang, Xudong; Xu, Yanhui; Li, Junrui; Lun, Huijie; Chen, Qi

    2013-08-15

    Two new transition metal coordination complexes, ([MnO(nda)](H{sub 2}dmt)(H{sub 2}O)){sub n} (1), [Ag{sub 5}(nda){sub 2.5}(dmt)]{sub n} (2), (H{sub 2}nda=naphthalene-1,4-dicarboxylic acid, dmt=2,4-diamine-6-methyl-1,3,5-triazine) have been hydrothermally synthesized by the reactions of H{sub 2}nda and dmt with the homologous MnCl{sub 2}·4H{sub 2}O and AgNO{sub 3}, respectively, and characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis, thermogravimetric analysis (TGA). The compound 1 exhibits a 3D network comprising 1D metal chain (MnO(CO{sub 2}){sub 2}){sub n} connected by the ligand nda{sup 2−}, featuring a four-connected uninodal diamond -like topology. In compound 2, it is firstly observed that decanuclear silver units as secondary building units to construct 3D network by the ligands dmt and nda{sup 2−}, with a rare 2-nodal (3,8)-connected tfz-d topology ((4{sup 3}){sub 2}(4{sup 6}.6{sup 18}.8{sup 4})). The interactions within each Mn(II)—Mn(II) pair of compound 1 are antiferromagnetic (g=2.07, J=−1.42(1) cm{sup −1}, zj′=−0.73(2) cm{sup −1}). In addition, compound 2 exhibits photoluminescent property at about 472 nm (λ{sub ex}=394 nm). - Graphical abstract: Two new transition metal coordination complexes 1–2 have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis thermogravimetric analysis (TGA). Highlights: • The compound 1 exhibits a 3D network with four-connected uninodal diamond-like topology. • The first 3D network of 2 with a rare tfz-d topology consists of decanuclear silver clusters as secondary building units. • The magnetic measurement indicates the compound 1 shows antiferromagnetic interactions. • The photoluminescent property of 2 has been measured.

  8. The Flögel-three-component reaction with dicarboxylic acids – an approach to bis(β-alkoxy-β-ketoenamides) for the synthesis of complex pyridine and pyrimidine derivatives

    PubMed Central

    Bera, Mrinal K; Domínguez, Moisés; Hommes, Paul

    2014-01-01

    Summary An extension of the substrate scope of the Flögel-three-component reaction of lithiated alkoxyallenes, nitriles and carboxylic acids is presented. The use of dicarboxylic acids allowed the preparation of symmetrical bis(β-ketoenamides) from simple starting materials in moderate yields. Cyclocondensations of these enamides to 4-hydroxypyridine derivatives or to functionalized pyrimidines efficiently provided symmetrically and unsymmetrically substituted fairly complex (hetero)aromatic compounds containing up to six conjugated aryl and hetaryl groups. In addition, subsequent functionalizations of the obtained heterocycles by palladium-catalyzed couplings or by oxidations are reported. We also describe the simple synthesis of a structurally interesting macrocyclic bispyrimidine derivative incorporating a 17-membered ring, whose configuration was elucidated by DFT calculations and by subsequent reactions. PMID:24605160

  9. Biocatalytic ammonolysis of (5S)-4,5-dihydro-1H-pyrrole-1,5-dicarboxylic acid, 1-(1,1-dimethylethyl)-5-ethyl ester: preparation of an intermediate to the dipeptidyl peptidase IV inhibitor Saxagliptin.

    PubMed

    Gill, Iqbal; Patel, Ramesh

    2006-02-01

    An efficient biocatalytic method has been developed for the conversion of (5S)-4,5-dihydro-1H-pyrrole-1,5-dicarboxylic acid, 1-(1,1-dimethylethyl)-5-ethyl ester (1) into the corresponding amide (5S)-5-aminocarbonyl-4,5-dihydro-1H-pyrrole-1-carboxylic acid, 1-(1,1-dimethylethyl)ester (2), which is a critical intermediate in the synthesis of the dipeptidyl peptidase IV (DPP4) inhibitor Saxagliptin (3). Candida antartica lipase B mediates ammonolysis of the ester with ammonium carbamate as ammonia donor to yield up to 71% of the amide. The inclusion of Ascarite and calcium chloride as adsorbents for carbon dioxide and ethanol byproducts, respectively, increases the yield to 98%, thereby offering an efficient and practical alternative to chemical routes which yield 57-64%.

  10. Dipeptides as effective prodrugs of the unnatural amino acid (+)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (LY354740), a selective group II metabotropic glutamate receptor agonist.

    PubMed

    Bueno, Ana Belén; Collado, Iván; de Dios, Alfonso; Domínguez, Carmen; Martín, José Alfredo; Martín, Luisa M; Martínez-Grau, María Angeles; Montero, Carlos; Pedregal, Concepción; Catlow, John; Coffey, D Scott; Clay, Michael P; Dantzig, Anne H; Lindstrom, Terry; Monn, James A; Jiang, Haiyan; Schoepp, Darryle D; Stratford, Robert E; Tabas, Linda B; Tizzano, Joseph P; Wright, Rebecca A; Herin, Marc F

    2005-08-11

    (+)-2-Aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (1), also known as LY354740, is a highly potent and selective agonist for group II metabotropic glutamate receptors (mGlu receptors 2 and 3) tested in clinical trials. It has been shown to block anxiety in the fear-potentiated startle model. Its relatively low bioavailability in different animal species drove the need for an effective prodrug form that would produce a therapeutic response at lower doses for the treatment of anxiety disorders. We have investigated the increase of intestinal absorption of this compound by targeting the human peptide transporter hPepT1 for active transport of di- and tripeptides derived from 1. We have found that oral administration of an N dipeptide derivative of 1 (12a) in rats shows up to an 8-fold increase in drug absorption and a 300-fold increase in potency in the fear-potentiated startle model in rats when compared with the parent drug 1.

  11. Self-assembly in solvates of 2,4-diamino-6-(4-methyl- phenyl)-1,3,5-triazine and in its molecular adducts with some aliphatic dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Nandy, Purnendu; Nayak, Amrita; Biswas, Sharmita Nandy; Pedireddi, V. R.

    2016-03-01

    Solid state structures of 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine, 1, in the form of methanol and dimethylsulfoxide (DMSO) solvates, as well as supramolecular assemblies of 1 with various aliphatic dicarboxylic acids, oxalic (a), malonic (b), succinic (c), glutaric (d) and adipic (e) have been reported. Analysis of the assemblies has been carried out by single crystal X-ray diffraction and thermal methods. Triazine 1 yields anhydrous molecular adducts with acids a-d, upon co-crystallization either from CH3OH and DMSO solvents. However acid e gives anhydrous adduct from DMSO solvent, while it gives a methanol adduct from CH3OH. Structure determination reveals that molecular adducts 1a, 1d and 1e are in a 2:1 ratio of 1 and the corresponding acid. However the ratio is 1:1, in 1b, perhaps due to the involvement of one of the acid groups in the intramolecular hydrogen bonding and in adduct 1c the ratio observed is 3:2. Structural features in all these assemblies have been rationalised in terms of various recognition patterns formed between the acceptor and donor groups. A noteworthy feature is that -COOH groups in acid a establish interaction with 1 through amino groups, while such interactions are observed to be through hetero -N atoms in case of the acids b-e.

  12. Role of the reaction intermediates in determining PHIP (parahydrogen induced polarization) effect in the hydrogenation of acetylene dicarboxylic acid with the complex [Rh (dppb)]{sup +} (dppb: 1,4-bis(diphenylphosphino)butane)

    SciTech Connect

    Reineri, F.; Aime, S.; Gobetto, R.; Nervi, C.

    2014-03-07

    This study deals with the parahydrogenation of the symmetric substrate acetylene dicarboxylic acid catalyzed by a Rh(I) complex bearing the chelating diphosphine dppb (1,4-bis(diphenylphosphino)butane). The two magnetically equivalent protons of the product yield a hyperpolarized emission signal in the {sup 1}H-NMR spectrum. Their polarization intensity varies upon changing the reaction solvent from methanol to acetone. A detailed analysis of the hydrogenation pathway is carried out by means of density functional theory calculations to assess the structure of hydrogenation intermediates and their stability in the two solvents. The observed polarization effects have been accounted on the basis of the obtained structures. Insights into the lifetime of a short-lived reaction intermediate are also obtained.

  13. Role of the reaction intermediates in determining PHIP (parahydrogen induced polarization) effect in the hydrogenation of acetylene dicarboxylic acid with the complex [Rh (dppb)]+ (dppb: 1,4-bis(diphenylphosphino)butane).

    PubMed

    Reineri, F; Aime, S; Gobetto, R; Nervi, C

    2014-03-07

    This study deals with the parahydrogenation of the symmetric substrate acetylene dicarboxylic acid catalyzed by a Rh(I) complex bearing the chelating diphosphine dppb (1,4-bis(diphenylphosphino)butane). The two magnetically equivalent protons of the product yield a hyperpolarized emission signal in the (1)H-NMR spectrum. Their polarization intensity varies upon changing the reaction solvent from methanol to acetone. A detailed analysis of the hydrogenation pathway is carried out by means of density functional theory calculations to assess the structure of hydrogenation intermediates and their stability in the two solvents. The observed polarization effects have been accounted on the basis of the obtained structures. Insights into the lifetime of a short-lived reaction intermediate are also obtained.

  14. Synthesis and Pharmacological Characterization of C4-(Thiotriazolyl)-substituted-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylates. Identification of (1R,2S,4R,5R,6R)-2-Amino-4-(1H-1,2,4-triazol-3-ylsulfanyl)bicyclo[3.1.0]hexane-2,6-dicarboxylic Acid (LY2812223), a Highly Potent, Functionally Selective mGlu2 Receptor Agonist.

    PubMed

    Monn, James A; Prieto, Lourdes; Taboada, Lorena; Hao, Junliang; Reinhard, Matthew R; Henry, Steven S; Beadle, Christopher D; Walton, Lesley; Man, Teresa; Rudyk, Helene; Clark, Barry; Tupper, David; Baker, S Richard; Lamas, Carlos; Montero, Carlos; Marcos, Alicia; Blanco, Jaime; Bures, Mark; Clawson, David K; Atwell, Shane; Lu, Frances; Wang, Jing; Russell, Marijane; Heinz, Beverly A; Wang, Xushan; Carter, Joan H; Getman, Brian G; Catlow, John T; Swanson, Steven; Johnson, Bryan G; Shaw, David B; McKinzie, David L

    2015-09-24

    Identification of orthosteric mGlu(2/3) receptor agonists capable of discriminating between individual mGlu2 and mGlu3 subtypes has been highly challenging owing to the glutamate-site sequence homology between these proteins. Herein we detail the preparation and characterization of a series of molecules related to (1S,2S,5R,6S)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate 1 (LY354740) bearing C4-thiotriazole substituents. On the basis of second messenger responses in cells expressing other recombinant human mGlu2/3 subtypes, a number of high potency and efficacy mGlu2 receptor agonists exhibiting low potency mGlu3 partial agonist/antagonist activity were identified. From this, (1R,2S,4R,5R,6R)-2-amino-4-(1H-1,2,4-triazol-3-ylsulfanyl)bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 14a (LY2812223) was further characterized. Cocrystallization of 14a with the amino terminal domains of hmGlu2 and hmGlu3 combined with site-directed mutation studies has clarified the underlying molecular basis of this unique pharmacology. Evaluation of 14a in a rat model responsive to mGlu2 receptor activation coupled with a measure of central drug disposition provides evidence that this molecule engages and activates central mGlu2 receptors in vivo.

  15. CYP86B1 Is Required for Very Long Chain ω-Hydroxyacid and α,ω-Dicarboxylic Acid Synthesis in Root and Seed Suberin Polyester1[W][OA

    PubMed Central

    Compagnon, Vincent; Diehl, Patrik; Benveniste, Irène; Meyer, Denise; Schaller, Hubert; Schreiber, Lukas; Franke, Rochus; Pinot, Franck

    2009-01-01

    Suberin composition of various plants including Arabidopsis (Arabidopsis thaliana) has shown the presence of very long chain fatty acid derivatives C20 in addition to the C16 and C18 series. Phylogenetic studies and plant genome mining have led to the identification of putative aliphatic hydroxylases belonging to the CYP86B subfamily of cytochrome P450 monooxygenases. In Arabidopsis, this subfamily is represented by CYP86B1 and CYP86B2, which share about 45% identity with CYP86A1, a fatty acid ω-hydroxylase implicated in root suberin monomer synthesis. Here, we show that CYP86B1 is located to the endoplasmic reticulum and is highly expressed in roots. Indeed, CYP86B1 promoter-driven β-glucuronidase expression indicated strong reporter activities at known sites of suberin production such as the endodermis. These observations, together with the fact that proteins of the CYP86B type are widespread among plant species, suggested a role of CYP86B1 in suberin biogenesis. To investigate the involvement of CYP86B1 in suberin biogenesis, we characterized an allelic series of cyp86B1 mutants of which two strong alleles were knockouts and two weak ones were RNA interference-silenced lines. These root aliphatic plant hydroxylase lines had a root and a seed coat aliphatic polyester composition in which C22- and C24-hydroxyacids and α,ω-dicarboxylic acids were strongly reduced. However, these changes did not affect seed coat permeability and ion content in leaves. The presumed precursors, C22 and C24 fatty acids, accumulated in the suberin polyester. These results demonstrate that CYP86B1 is a very long chain fatty acid hydroxylase specifically involved in polyester monomer biosynthesis during the course of plant development. PMID:19525321

  16. A new three-dimensional silver(I) coordination framework with a diamondoid topology constructed from 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid.

    PubMed

    Deng, Zhi-He; Peng, Zhen-Jian; Huang, Jun

    2013-05-01

    The title compound, poly[[μ4-5-carboxy-4-carboxylato-2-(pyridin-4-yl)-1H-imidazol-1-ido]disilver(I)], [Ag2(C10H5N3O4)]n, was synthesized by reacting silver nitrate with 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid (H3PyIDC) under hydrothermal conditions. The asymmetric unit contains two crystallographically independent Ag(I) cations and one unique HPyIDC(2-) anion. Both Ag(I) cations are three-coordinated in distorted T-shaped coordination geometries. One Ag(I) cation is coordinated by one N and two O atoms from two HPyIDC(2-) anions, while the other is bonded to one O and two N atoms from two HPyIDC(2-) anions. It is interesting to note that the HPyIDC(2-) group acts as a μ4-bridging ligand to link the Ag(I) cations into a three-dimensional framework, which can be simplified as a diamondoid topology. The thermal stability and photoluminescent properties of the title compound have also been studied.

  17. Molecular structure, vibrational spectroscopic (FT-IR, FT-Raman), UV-vis spectra, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis, thermodynamic properties of benzophenone 2,4-dicarboxylic acid by ab initio HF and density functional method.

    PubMed

    Chaitanya, K

    2012-02-01

    The FT-IR (4000-450 cm(-1)) and FT-Raman spectra (3500-100 cm(-1)) of benzophenone 2,4-dicarboxylic acid (2,4-BDA) have been recorded in the condensed state. Density functional theory calculation with B3LYP/6-31G(d,p) basis set have been used to determine ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities, Raman activities and bonding features of the title compounds. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of 2,4-BDA is calculated using HF/6-31G(d,p) method on the finite-field approach. The stability of molecule has been analyzed by using NBO analysis. The calculated first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. The calculated HOMO and LUMO energies show that charge transfer occurs within these molecules. Mulliken population analysis on atomic charges is also calculated. Because of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated. Finally, the UV-vis spectra and electronic absorption properties were explained and illustrated from the frontier molecular orbitals.

  18. Isolation of phenazine 1,6-di-carboxylic acid from Pseudomonas aeruginosa strain HRW.1-S3 and its role in biofilm-mediated crude oil degradation and cytotoxicity against bacterial and cancer cells.

    PubMed

    Dasgupta, Debdeep; Kumar, Abhinash; Mukhopadhyay, Balaram; Sengupta, Tapas K

    2015-10-01

    Pseudomonas sp. has long been known for production of a wide range of secondary metabolites during late exponential and stationary phases of growth. Phenazine derivatives constitute a large group of secondary metabolites produced by microorganisms including Pseudomonas sp. Phenazine 1,6-di-carboxylic acid (PDC) is one of such metabolites and has been debated for its origin from Pseudomonas sp. The present study describes purification and characterization of PDC isolated from culture of a natural isolate of Pseudomonas sp. HRW.1-S3 while grown in presence of crude oil as sole carbon source. The isolated PDC was tested for its effect on biofilm formation by another environmental isolate of Pseudomonas sp. DSW.1-S4 which lacks the ability to produce any phenazine compound. PDC showed profound effect on both planktonic as well as biofilm mode of growth of DSW.1-S4 at concentrations between 5 and 20 μM. Interestingly, PDC showed substantial cytotoxicity against three cancer cell lines and against both Gram-positive and Gram-negative bacteria. Thus, the present study not only opens an avenue to understand interspecific cooperation between Pseudomonas species which may lead its applicability in bioremediation, but also it signifies the scope of future investigation on PDC for its therapeutic applications.

  19. Syntheses, structures, luminescent and photocatalytic properties of two Zn(II) coordination polymers assembled with mixed bridging N-donors and 2-(4-carboxyphenyl)-4,5-imidazole dicarboxylic acid ligand

    NASA Astrophysics Data System (ADS)

    Yuan, Gang; Shao, Kui-Zhan; Hao, Xiang-Rong; Zhan, Pei-Ying; Su, Zhong-Min

    2017-04-01

    Two new Zn(II) coordination polymers with the formulas of {[Zn3(HCpIDC)2(4,4‧-bipy)(H2O)]·4H2O}n (1) and {[Zn2(CpIDC)(BIMB)]·H2O}n (2) [H4CpIDC = 2-(4-carboxyphenyl)-4,5-imidazole dicarboxylic acid, 4,4‧-bipy = 4,4‧-bipyridine, and BIMB = 1,4-bis(1-imidazolyl)benzene] have been successfully synthesized. Both complexes 1 and 2 feature 3D frameworks in which the IDC groups of HCpIDC3- and CpIDC4- ligands link metal nodes leading to infinite 21 helical chains. The HCpIDC3- and CpIDC4- anions exhibit two coordination modes (μ4-kN,O: kN‧,O‧: kO″,O‴: kO″″ and μ5-kN,O: kN‧,O‧: kO″,O‴: kO″″: kO) in different coordination environments. Further structural analyses show that 1 and 2 are topologically bimodal 4-connected net and trinodal (3,4,6)-connected net, respectively. As is expected, two complexes with good thermal stability displayed strong fluorescence emissions in the solid state at the room temperature. Moreover, complex 1 has some extent of photocatalytic activities for RhB.

  20. Mechanisms for the transport of alpha,omega-dicarboxylates through the mitochondrial inner membrane.

    PubMed

    Liu, G; Hinch, B; Beavis, A D

    1996-10-11

    alpha,omega-Dicarboxylates have antibacterial properties, have been used in the treatment of hyperpigmentary disorders, are active against various melanoma cell lines, and can also undergo beta-oxidation. Little, however, is known about their transport. In this paper, we examine the mitochondrial transport of alpha, omega-dicarboxylates ranging from oxalate (DC2) to sebacate (DC10). DC2-DC10 are transported by the inner membrane anion channel (IMAC). DC6-DC10 are also transported by an electroneutral mechanism that appears to reflect transport of the acid through the lipid bilayer. At 37 degrees C and pH 7.0, DC10 is transported very rapidly at 3 micromol/min.mg, and respiring mitochondria swell in the K+ salts of these acids. This transport mechanism is probably the major pathway by which the longer dicarboxylates enter cells, bacteria, and mitochondria. We also demonstrate that DC5-DC10 can also be transported by an electroneutral mechanism mediated by tributyltin, a potent inhibitor of IMAC. The mechanism appears to involve electroneutral exchange of a TBT-dicarboxylate-H complex for TBT-OH. Finally, we present evidence that of all the dicarboxylates tested only DC2-DC4 can be transported by the classical dicarboxylate carrier.

  1. Mössbauer spectroscopy of 151 europium dicarboxylates

    NASA Astrophysics Data System (ADS)

    Wynter, C. I.; Ryan, D. H.; Trichtchenko, Olga; Voyer, C. J.; Brown, D. E.; Sobel, S. G.; Haigney, A. L.; May, Leopold; Hillery, B. R.; Gajbhiye, N. S.

    2008-07-01

    We have previously reported the stability of europium oxalate compared to ammonium europium bis-salen and europium benzoate. We now extend the dicoarboxylic acid chain of the oxalate by introducing additional-CH2-groups in the dicarboxylate ligands by using malonate, succinate, glutarate and adipate. Additionally, we have examined the effect of alterations in the succinate dianion by introducing functional groups such as [C = C]in the case of the maleide and-OH group in the case of the malide. This study is an attempt to further characterize these compounds. Infrared spectra were used to characterize bridging and chelating dicarboxylates while Mössbauer spectroscopy measurements were used to gain better insight into the structure of heterocyclic “cages” containing two Eu3 + ions and two dianions.

  2. Novel nanorose-like Ce(III)-doped and undoped Cu(II)-biphenyl-4,4-dicarboxylic acid (Cu(II)-BPDCA) MOSs as visible light photocatalysts: synthesis, characterization, photodegradation of toxic dyes and optimization.

    PubMed

    Mousavinia, S E; Hajati, S; Ghaedi, M; Dashtian, K

    2016-04-28

    A novel nanorose-like metal organic system (MOS) based on Cu(II) and biphenyl-4,4-dicarboxylic acid (Cu-BPDCA) was hydrothermally synthesized and characterized via EDS, FE-SEM, XRD, DRS and FT-IR analysis. This novel nanomaterial was found to be of narrow energy band gap (1.24 eV) and thus it was applied as a photocatalyst driven by visible light for the degradation of the rose bengal (RB) and eosin Y (EY) dyes. For further improvement in the photocatalytic performance of Cu-BPDCA, it was doped with a trace amount of Ce(III) in a simple way followed by characterization. The achieved improvement is due to the formation of a large number of O2⁻˙ and ˙OH radicals compared to the case of undoped Cu-BPDCA. The influence of important variables such as initial dye concentration, photocatalyst dosage and time of irradiation on the photocatalytic degradation efficiency was studied and optimized using central composite design. The optimum condition for the photodegradation of RB was found to be 40 min, 4.0 mg L(-1) and 0.015 g, corresponding to the irradiation time, RB concentration and photocatalyst mass, respectively. The photodegradation of EY was optimized at 4.0, 76 min, 5.9 mg L(-1) and 0.015 g corresponding to the pH, irradiation time, EY concentration and photocatalyst mass, respectively. At these optimum conditions, the photocatalytic degradation percentages of RB and EY with a desirability of 0.95 and 1.0 were found to be 78.90% and 67.63%, respectively. Kinetics study showed that the Langmuir-Hinshelwood kinetics model suitably fits the experimental data. From the Langmuir-Hinshelwood kinetics model, a significantly high photodegradation to surface adsorption ratio was obtained which is the great advantage of this work in addition to applying visible light.

  3. Metabolic profile of mephedrone: Identification of nor-mephedrone conjugates with dicarboxylic acids as a new type of xenobiotic phase II metabolites.

    PubMed

    Linhart, Igor; Himl, Michal; Židková, Monika; Balíková, Marie; Lhotková, Eva; Páleníček, Tomáš

    2016-01-05

    Metabolic profile of mephedrone (4-methylmethcathinone, 4-MMC), a frequently abused recreational drug, was determined in rats in vivo. The urine of rats dosed with a subcutaneous bolus dose of 20mg 4-MMC/kg was analysed by LC/MS. Ten phase I and five phase II metabolites were identified by comparison of their retention times and MS(2) spectra with those of authentic reference standards and/or with the MS(2) spectra of previously identified metabolites. The main metabolic pathway was N-demethylation leading to normephedrone (4-methylcathinone, 4-MC) which was further conjugated with succinic, glutaric and adipic acid. Other phase I metabolic pathways included oxidation of the 4-methyl group, carbonyl reduction leading to dihydro-metabolites and ω-oxidation at the position 3'. Five of the metabolites detected, namely, 4-carboxynormephedrone (4-carboxycathinone, 4-CC), 4-carboxydihydronormephedrone (4-carboxynorephedrine, 4-CNE), hydroxytolyldihydro-normephedrone (4-hydroxymethylnorephedrine, 4-OH-MNE) and conjugates of 4-MC with glutaric and adipic acid, have not been reported as yet. The last two conjugates represent a novel, hitherto unexploited, type of phase II metabolites in mammals together with an analogous succinic acid conjugate of 4-MC identified by Pozo et al. (2015). These conjugates might be potentially of great importance in the metabolism of other psychoactive amines.

  4. Three-dimensional hydrogen-bonded structures in the hydrated proton-transfer salts of isonipecotamide with the dicarboxylic oxalic and adipic acid homologues.

    PubMed

    Smith, Graham; Wermuth, Urs D

    2013-10-01

    The structures of the 1:1 hydrated proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with oxalic acid, 4-carbamoylpiperidinium hydrogen oxalate dihydrate, C6H13N2O(+)·C2HO4(-)·2H2O, (I), and with adipic acid, bis(4-carbamoylpiperidinium) adipate dihydrate, 2C6H13N2O(+)·C6H8O4(2-)·2H2O, (II), are three-dimensional hydrogen-bonded constructs involving several different types of enlarged water-bridged cyclic associations. In the structure of (I), the oxalate monoanions give head-to-tail carboxylic acid O-H···O(carboxyl) hydrogen-bonding interactions, forming C(5) chain substructures which extend along a. The isonipecotamide cations also give parallel chain substructures through amide N-H···O hydrogen bonds, the chains being linked across b and down c by alternating water bridges involving both carboxyl and amide O-atom acceptors and amide and piperidinium N-H···O(carboxyl) hydrogen bonds, generating cyclic R4(3)(10) and R3(2)(11) motifs. In the structure of (II), the asymmetric unit comprises a piperidinium cation, half an adipate dianion, which lies across a crystallographic inversion centre, and a solvent water molecule. In the crystal structure, the two inversion-related cations are interlinked through the two water molecules, which act as acceptors in dual amide N-H···O(water) hydrogen bonds, to give a cyclic R4(2)(8) association which is conjoined with an R4(4)(12) motif. Further N-H···O(water), water O-H···O(amide) and piperidinium N-H···O(carboxyl) hydrogen bonds give the overall three-dimensional structure. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. The presence of solvent water molecules in these structures is largely responsible for the non-occurrence of the common hydrogen-bonded amide-amide dimer, promoting instead various expanded cyclic hydrogen-bonding motifs.

  5. Citrate sensing by the C4-dicarboxylate/citrate sensor kinase DcuS of Escherichia coli: binding site and conversion of DcuS to a C4-dicarboxylate- or citrate-specific sensor.

    PubMed

    Krämer, J; Fischer, J D; Zientz, E; Vijayan, V; Griesinger, C; Lupas, A; Unden, G

    2007-06-01

    The histidine protein kinase DcuS of Escherichia coli senses C(4)-dicarboxylates and citrate by a periplasmic domain. The closely related sensor kinase CitA binds citrate, but no C(4)-dicarboxylates, by a homologous periplasmic domain. CitA is known to bind the three carboxylate and the hydroxyl groups of citrate by sites C1, C2, C3, and H. DcuS requires the same sites for C(4)-dicarboxylate sensing, but only C2 and C3 are highly conserved. It is shown here that sensing of citrate by DcuS required the same sites. Binding of citrate to DcuS, therefore, was similar to binding of C(4)-dicarboxylates but different from that of citrate binding in CitA. DcuS could be converted to a C(4)-dicarboxylate-specific sensor (DcuS(DC)) by mutating residues of sites C1 and C3 or of some DcuS-subtype specific residues. Mutations around site C1 aimed at increasing the size and accessibility of the site converted DcuS to a citrate-specific sensor (DcuS(Cit)). DcuS(DC) and DcuS(Cit) had complementary effector specificities and responded either to C(4)-dicarboxylates or to citrate and mesaconate. The results imply that DcuS binds citrate (similar to the C(4)-dicarboxylates) via the C(4)-dicarboxylate part of the molecule. Sites C2 and C3 are essential for binding of two carboxylic groups of citrate or of C(4)-dicarboxylates; sites C1 and H are required for other essential purposes.

  6. Solvent effects on interfacial electron transfer from Ru(4,4'-dicarboxylic acid-2,2'-bipyridine)2(NCS)2 to nanoparticulate TiO2: spectroscopy and solar photoconversion.

    PubMed

    Pollard, Jennifer A; Zhang, Dongshe; Downing, Jonathan A; Knorr, Fritz J; McHale, Jeanne L

    2005-12-22

    Resonance Raman spectra are reported for Ru(4,4'-dicarboxylic acid-2,2'-bipyridine)2(NCS)2 (commonly called "N3") in ethanol solution and adsorbed on nanoparticulate colloidal TiO2 in ethanol (EtOH) and in acetonitrile (ACN), at wavelengths within the visible absorption band of the dye. Raman cross sections of free N3 in EtOH are found to be similar to those of N3 adsorbed on colloidal TiO2 in EtOH, and are generally lower than those of N3 on TiO2 in ACN. Strong electronic coupling mediated by surface states results in red-shifted absorption spectra and enhanced Raman signals for N3 adsorbed on nanocolloidal TiO2 in ACN compared to EtOH. In contrast, the absorption spectrum of N3 on nanocrystalline TiO2 in contact with solvent is similar for ACN and EtOH. Wavelength-dependent depolarization ratios for N3 Raman bands of both free and adsorbed N3 reveal resonance enhancement via two or more excited electronic states. Luminescence spectra of N3 adsorbed on nanocrystalline films of TiO2 and ZrO2 in contact with solvent reveal that the quantum yield of electron injection phi(ET) into TiO2 decreases in the order ACN > EtOH > DMSO. Dye-sensitized solar cells were fabricated with N3 adsorbed on nanocrystalline films of TiO2 in contact with ACN, EtOH, and DMSO solutions containing LiI/LiI3 electrolyte. Photoconversion efficiencies eta were found to be 2.6% in ACN, 1.3% in DMSO, and 0.84% in EtOH. Higher short circuit currents are found in cells using ACN, while the maximum voltage is found to be largest in DMSO. It is concluded that the increased photocurrent and quantum yield of interfacial electron transfer in acetonitrile as compared to ethanol and DMSO is primarily the result of faster electron injection of N3 when adsorbed on TiO2 in the presence of ACN as opposed to EtOH or DMSO.

  7. 3-D silver(I)-lanthanide(III) heterometallic-organic frameworks constructed from 2,2'-bipyridine-3,3'-dicarboxylic acid: synthesis, structure, photoluminescence, and their remarkable thermostability.

    PubMed

    Zhou, Yunshan; Li, Xiaomin; Zhang, Lijuan; Guo, Yan; Shi, Zonghai

    2014-04-07

    A new family of silver(I)-lanthanide(III) heterometallic-organic frameworks having the formula [AgLn(bpdc)2] (Ln = Eu (1), Tb (2), Sm (3), Dy (4), Y (5), Yb (6), Er (7), Ho (8); H2bpdc = 2,2'-bipyridine-3,3'-dicarboxylic acid), each of which crystallizes in the monoclinic space group C2/c with Z = 4, has been hydrothermally synthesized. The compounds were characterized by means of IR, elemental analysis, thermogravimetric-differential thermal analysis, and powder X-ray diffraction (XRD), wherein compounds 1, 2, and 4-8 were structurally characterized. The powder XRD and single-crystal structures of the title compounds indicate that all the compounds are isostructural and feature a three-dimensional (3-D) open framework. In the structures of the compounds, bpdc(2-) ligands link Ln(3+) through their carboxylic groups, resulting in the formation of a one-dimensional {Ln(bpdc)2}n infinite chain along the c direction. The adjacent chains are then connected to each other through the coordination interaction between Ag(+) and the pyridyl N atoms of bpdc(2-) ligands from the chains, resulting in a 3-D (2,4,6)-connected open framework with (4(11)·6(4))(4(3)·8(2)·10)(8)2 topology. The compounds show remarkable good thermally stability up to 370 °C because neither aquo ligands nor lattice water molecules exist in the composition of the compounds. The photoluminescent properties of compounds 1 and 2 were studied in detail. The energy level of the triplet states of the ligand H2bpdc 21,505 cm(-1) (465 nm) was determined based on the 77 K emission spectrum of the compound [Gd2(bpdc)3(phen)2(H2O)2]·6H2O 9. The (5)D0 and (5)D4 emission lifetimes (1.58 and 1.76 ms) and the overall quantum yields (21% and 22%) were determined for the compounds 1 and 2, respectively.

  8. Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

    PubMed Central

    Bassanini, Ivan; Hult, Karl

    2015-01-01

    Summary Dicarboxylic acids and their derivatives (esters and anhydrides) have been used as acylating agents in lipase-catalyzed reactions in organic solvents. The synthetic outcomes have been dimeric or hybrid derivatives of bioactive natural compounds as well as functionalized polyesters. PMID:26664578

  9. Caffeoylquinic Acids from the Aerial Parts of Chrysanthemum coronarium L.

    PubMed Central

    Wan, Chunpeng; Li, Shanshan; Liu, Lin; Chen, Chuying; Fan, Shuying

    2017-01-01

    To elucidate the chemical compositions of the aerial parts of Chrysanthemum coronarium L., the ethanol extracts of Ch. coronarium L. were firstly isolated by the MCI-gel resin column. The caffeoylquinic acid-rich fractions were further purified by various chromatographic columns including silica gel, Sephadex LH-20, and semi-preparative HPLC to yield the compounds. The purified compounds were characterized by 1H-Nuclear Magnetic Resonance (1H-NMR), 13C-NMR, and high resolution electrospray ionisation mass spectral (HR-ESI-MS) spectroscopy. Seven caffeoylquinic acid (CQA) compounds were isolated from this plant. Their structures were clarified by spectrometric methods and identified as 3-O-caffeoylquinic acid (1), 5-O-caffeoylquinic acid (2), 4-O-caffeoylquinic acid (3), 3,4-di-O-caffeoylquinic acid (4), 1,5-di-O-caffeoylquinic acid (5), 3,5-di-O-caffeoylquinic acid (6), and 4,5-di-O-caffeoylquinic acid (7). Caffeoylquinic acids were the major constituents present in the aerial parts of Ch. coronarium L. All of the isolates except for compounds 2 and 6 were reported for the first time from this species. Moreover, compounds 3–5, and 7 were identified from the Chrysanthemum genus for the first time. PMID:28218654

  10. Aqueous Phase Photo-Oxidation of Succinic Acid: Changes in Hygroscopic Properties and Reaction Products

    NASA Astrophysics Data System (ADS)

    Hudson, P. K.; Ninokawa, A.; Hofstra, J.; de Lijser, P.

    2013-12-01

    Atmospheric aerosol particles have been identified as important factors in understanding climate change. The extent to which aerosols affect climate is determined, in part, by hygroscopic properties which can change as a result of atmospheric processing. Dicarboxylic acids, components of atmospheric aerosol, have a wide range of hygroscopic properties and can undergo oxidation and photolysis reactions in the atmosphere. In this study, the hygroscopic properties of succinic acid aerosol, a non-hygroscopic four carbon dicarboxylic acid, were measured with a humidified tandem differential mobility analyzer (HTDMA) and compared to reaction products resulting from the aqueous phase photo-oxidation reaction of hydrogen peroxide and succinic acid. Reaction products were determined and quantified using gas chromatography-flame ionization detection (GC-FID) and GC-mass spectrometry (GC-MS) as a function of hydrogen peroxide:succinic acid concentration ratio and photolysis time. Although reaction products include larger non-hygroscopic dicarboxylic acids (e.g. adipic acid) and smaller hygroscopic dicarboxylic acids (e.g. malonic and oxalic acids), comparison of hygroscopic growth curves to Zdanovskii-Stokes-Robinson (ZSR) predictions suggests that the hygroscopic properties of many of the product mixtures are largely independent of the hygroscopicity of the individual components. This study provides a framework for future investigations to fully understand and predict the role of chemical reactions in altering atmospheric conditions that affect climate.

  11. Clinical applications of urinary organic acids. Part 2. Dysbiosis markers.

    PubMed

    Lord, Richard S; Bralley, J Alexander

    2008-12-01

    Part 1 of this series focused on urinary organic acids as markers of detoxification; part 2 focuses on dysbiosis markers. Intestinal microbial growth is accompanied by the release of products of their metabolism that may be absorbed and excreted in urine. Several organic acids are known to be specific products of bacterial metabolic action on dietary polyphenols or unassimilated amino acids or carbohydrates. Associated gastrointestinal or neurological symptoms may result from irritation of the intestinal mucosa or systemic distribution of absorbed neurotoxic products. Detection of abnormally elevated levels of these products is a useful diagnostic tool for patients with gastrointestinal or toxicological symptoms. Test profiles of urinary organic acids associated with microbial overgrowth can include benzoate, hippurate, phenylacetate, phenylpropionate, cresol, hydroxybenzoate, hydroxyphenylacetate, hydroxyphenylpropionate and 3,4-dihydroxyphenylpropionate, indican, tricarballylate, D-lactate, and D-arabinitol. Effective treatments for the associated microbial overgrowths may be directed at reducing microbial populations, introducing favorable microbes, and restoring intestinal mucosal integrity.

  12. Dicarboxylic acids, oxoacids, benzoic acid, α-dicarbonyls, WSOC, OC, and ions in spring aerosols from Okinawa Island in the western North Pacific Rim: size distributions and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, D. K.; Kawamura, K.; Lazaar, M.; Kunwar, B.; Boreddy, S. K. R.

    2015-09-01

    Size-segregated aerosols (9-stages from < 0.43 to > 11.3 μm in diameter) were collected at Cape Hedo, Okinawa in spring 2008 and analyzed for water-soluble diacids (C2-C12), ω-oxoacids (ωC2-ωC9), pyruvic acid, benzoic acid and α-dicarbonyls (C2-C3) as well as water-soluble organic carbon (WSOC), organic carbon (OC) and major ions. In all the size-segregated aerosols, oxalic acid (C2) was found as the most abundant species followed by malonic and succinic acids whereas glyoxylic acid (ωC2) was the dominant oxoacid and glyoxal (Gly) was more abundant than methylglyoxal. Diacids (C2-C5), ωC2 and Gly as well as WSOC and OC peaked at 0.65-1.1 μm in fine mode whereas azelaic (C9) and 9-oxononanoic (ωC9) acids peaked at 3.3-4.7 μm in coarse mode. Sulfate and ammonium are enriched in fine mode whereas sodium and chloride are in coarse mode. These results imply that water-soluble species in the marine aerosols could act as cloud condensation nuclei (CCN) to develop the cloud cover over the western North Pacific Rim. The organic species are likely produced by a combination of gas-phase photooxidation, and aerosol-phase or in-cloud processing during long-range transport. The coarse mode peaks of malonic and succinic acids were obtained in the samples with marine air masses, suggesting that they may be associated with the reaction on sea salt particles. Bimodal size distributions of longer-chain diacid (C9) and oxoacid (ωC9) with a major peak in the coarse mode suggest their production by photooxidation of biogenic unsaturated fatty acids via heterogeneous reactions on sea salt particles.

  13. Dicarboxylic acids, oxoacids, benzoic acid, α-dicarbonyls, WSOC, OC, and ions in spring aerosols from Okinawa Island in the western North Pacific Rim: size distributions and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, Dhananjay K.; Kawamura, Kimitaka; Lazaar, Manuel; Kunwar, Bhagawati; Boreddy, Suresh K. R.

    2016-04-01

    Size-segregated aerosols (nine stages from < 0.43 to > 11.3 µm in diameter) were collected at Cape Hedo, Okinawa, in spring 2008 and analyzed for water-soluble diacids (C2-C12), ω-oxoacids (ωC2-ωC9), pyruvic acid, benzoic acid, and α-dicarbonyls (C2-C3) as well as water-soluble organic carbon (WSOC), organic carbon (OC), and major ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-, and MSA-). In all the size-segregated aerosols, oxalic acid (C2) was found to be the most abundant species, followed by malonic and succinic acids, whereas glyoxylic acid (ωC2) was the dominant oxoacid and glyoxal (Gly) was more abundant than methylglyoxal. Diacids (C2-C5), ωC2, and Gly as well as WSOC and OC peaked at fine mode (0.65-1.1 µm) whereas azelaic (C9) and 9-oxononanoic (ωC9) acids peaked at coarse mode (3.3-4.7 µm). Sulfate and ammonium were enriched in fine mode, whereas sodium and chloride were in coarse mode. Strong correlations of C2-C5 diacids, ωC2 and Gly with sulfate were observed in fine mode (r = 0.86-0.99), indicating a commonality in their secondary formation. Their significant correlations with liquid water content in fine mode (r = 0.82-0.95) further suggest an importance of the aqueous-phase production in Okinawa aerosols. They may also have been directly emitted from biomass burning in fine mode as supported by strong correlations with potassium (r = 0.85-0.96), which is a tracer of biomass burning. Bimodal size distributions of longer-chain diacid (C9) and oxoacid (ωC9) with a major peak in the coarse mode suggest that they were emitted from the sea surface microlayers and/or produced by heterogeneous oxidation of biogenic unsaturated fatty acids on sea salt particles.

  14. Determinants of substrate and cation transport in the human Na+/dicarboxylate cotransporter NaDC3.

    PubMed

    Schlessinger, Avner; Sun, Nina N; Colas, Claire; Pajor, Ana M

    2014-06-13

    Metabolic intermediates, such as succinate and citrate, regulate important processes ranging from energy metabolism to fatty acid synthesis. Cytosolic concentrations of these metabolites are controlled, in part, by members of the SLC13 gene family. The molecular mechanism underlying Na(+)-coupled di- and tricarboxylate transport by this family is understood poorly. The human Na(+)/dicarboxylate cotransporter NaDC3 (SLC13A3) is found in various tissues, including the kidney, liver, and brain. In addition to citric acid cycle intermediates such as α-ketoglutarate and succinate, NaDC3 transports other compounds into cells, including N-acetyl aspartate, mercaptosuccinate, and glutathione, in keeping with its dual roles in cell nutrition and detoxification. In this study, we construct a homology structural model of NaDC3 on the basis of the structure of the Vibrio cholerae homolog vcINDY. Our computations are followed by experimental testing of the predicted NaDC3 structure and mode of interaction with various substrates. The results of this study show that the substrate and cation binding domains of NaDC3 are composed of residues in the opposing hairpin loops and unwound portions of adjacent helices. Furthermore, these results provide a possible explanation for the differential substrate specificity among dicarboxylate transporters that underpin their diverse biological roles in metabolism and detoxification. The structural model of NaDC3 provides a framework for understanding substrate selectivity and the Na(+)-coupled anion transport mechanism by the human SLC13 family and other key solute carrier transporters.

  15. Poly[μ-aqua-diaqua­(μ2-pyrazine-2,3-dicarboxyl­ato)dilithium(I)

    PubMed Central

    Tombul, Mustafa; Guven, Kutalmis

    2009-01-01

    The asymmetric unit of the title compound, [Li2(C6H2N2O4)(H2O)3]n, consists of two independent Li+ cations, one pyrazine-2,3-dicarboxyl­ate dianion and three water mol­ecules. One of the Li+ cations has a distorted tetra­hedral geometry, coordinated by one of the carboxyl­ate O atoms of the pyrazine-2,3-dicarboxyl­ate ligand and three O atoms from three water mol­ecules, whereas the other Li+ cation has a distorted trigonal-bipyramidal geometry, coordinated by a carboxyl­ate O atom of a symmetry-related pyrazine-2,3-dicarboxyl­ate ligand, two water mol­ecules and a chelating pyrazine-2,3-dicarboxyl­ate ligand (by utilizing both N and O atoms) of an adjacent mol­ecule. The synthesis of a hydrated polymeric dinuclear lithium complex formed with two pyrazine-2,3-dicarboxylic acid ligands has been reported previously [Tombul et al. (2008a ▶). Acta Cryst. E64, m491–m492]. By comparision to the complex reported here, the dinuclear complex formed with two pyrazine-2,3-dicarboxylic acid ligands differs in the coordination geometry of both Li atoms. The crystal structure further features O—H⋯O and O—H⋯N hydrogen-bonding inter­actions involving the water mol­ecules and carboxyl­ate O atoms. PMID:21578706

  16. New soft porous frameworks based on lambda-zirconium phosphate and aliphatic dicarboxylates: Synthesis and structural characterization

    NASA Astrophysics Data System (ADS)

    Alhendawi, Hussein; Brunet, Ernesto; Juanes, Olga; Hammouda, Huda; Idhair, Salem; Rodríguez Payán, Elena; de Victoria Rodríguez, María

    2015-11-01

    New dicarboxylate-functionalized pillared materials with a general formula of λ-ZrPO4(OH)1-x(OOC(CH2)nCOO)x/2(dmso) (n=6, 8 and 10) have been prepared by post-synthesis modification of the inorganic layers of λ-zirconium phosphate (λ-ZrP), where the superficial Chloride monovalent anionic ligands of λ-layer are partially exchanged with the divalent anionic ligands of a series of long-chain aliphatic dicarboxylic acids, namely octanedioic acid, decanedioic acid and dodecanedioic acid. The synthesized materials are characterized by X-ray diffractometry, FT-IR spectrophotometry, elemental and thermogravimetric analyses. The X-ray diffraction patterns show that the obtained solid phases are pure. Furthermore, the interlayer distance of λ-ZrP systematically increases from 1.02 to 1.59 nm as a result of the incorporation of the mentioned acids inside the interlayer gallery.

  17. Identification of a third secondary carrier (DcuC) for anaerobic C4-dicarboxylate transport in Escherichia coli: roles of the three Dcu carriers in uptake and exchange.

    PubMed Central

    Zientz, E; Six, S; Unden, G

    1996-01-01

    In Escherichia coli, two carriers (DcuA and DcuB) for the transport of C4 dicarboxylates in anaerobic growth were known. Here a novel gene dcuC was identified encoding a secondary carrier (DcuC) for C4 dicarboxylates which is functional in anaerobic growth. The dcuC gene is located at min 14.1 of the E. coli map in the counterclockwise orientation. The dcuC gene combines two open reading frames found in other strains of E. coli K-12. The gene product (DcuC) is responsible for the transport of C4 dicarboxylates in DcuA-DcuB-deficient cells. The triple mutant (dcuA dcuB dcuC) is completely devoid of C4-dicarboxylate transport (exchange and uptake) during anaerobic growth, and the bacteria are no longer capable of growth by fumarate respiration. DcuC, however, is not required for C4-dicarboxylate uptake in aerobic growth. The dcuC gene encodes a putative protein of 461 amino acid residues with properties typical for secondary procaryotic carriers. DcuC shows sequence similarity to the two major anaerobic C4-dicarboxylate carriers DcuA and DcuB. Mutants producing only DcuA, DcuB, or DcuC were prepared. In the mutants, DcuA, DcuB, and DcuC were each able to operate in the exchange and uptake mode. PMID:8955408

  18. Molecular and functional analysis of SDCT2, a novel rat sodium-dependent dicarboxylate transporter

    PubMed Central

    Chen, Xiangmei; Tsukaguchi, Hiroyasu; Chen, Xing-Zhen; Berger, Urs V.; Hediger, Matthias A.

    1999-01-01

    Kidney proximal tubule cells take up Krebs cycle intermediates for metabolic purposes and for secretion of organic anions through dicarboxylate/organic anion exchange. Alteration in reabsorption of citrate is closely related to renal stone formation. The presence of distinct types of sodium-coupled dicarboxylate transporters has been postulated on either side of the polarized epithelial membrane in the kidney proximal tubule. Using a PCR-based approach, we isolated a novel member of the sodium-dependent dicarboxylate/sulfate transporter called SDCT2. SDCT2 is a 600–amino acid residue protein that has 47–48% amino acid identity to SDCT1 and NaDC-1, previously identified in kidney and intestine. Northern analysis gave a single band of 3.3 kb for SDCT2 in kidney, liver, and brain. In situ hybridization revealed that SDCT2 is prominently expressed in kidney proximal tubule S3 segments and in perivenous hepatocytes, consistent with the sites of high-affinity dicarboxylate transport identified based on vesicle studies. A signal was also detected in the meningeal layers of the brain. SDCT2 expressed in Xenopus oocytes mediated sodium-dependent transport of di- and tricarboxylates with substrate preference for succinate rather than citrate, but excluding monocarboxylates. SDCT2, unlike SDCT1, displayed a unique pH dependence for succinate transport (optimal pH 7.5–8.5) and showed a high affinity for dimethylsuccinate, two features characteristic of basolateral transport. These data help to interpret the mechanisms of renal citrate transport, their alteration in pathophysiological conditions, and their role in the elimination of organic anions and therapeutic drugs. PMID:10207168

  19. Binuclear biologically active Co(II) complexes with octazamacrocycle and aliphatic dicarboxylates

    NASA Astrophysics Data System (ADS)

    Tanasković, S. B.; Vučković, G.; Antonijević-Nikolić, M.; Stanojković, T.; Gojgić-Cvijović, G.

    2012-12-01

    Four new cationic Co(II) complexes with N,N',N'',N'''-tetrakis (2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and dianion of one the aliphatic dicarboxylic acids: butanedioic acid (succinic) acid = succH2, pentanedioic (glutaric) acid = gluH2, hexanedioic acid (adipic) acid = adipH2 or decanedioic acid (sebacic) acid = sebH2 of general formula [Co2(L)(tpmc)](ClO4)2ṡxY, L2- = succ, x = 1, Y = H2O; L = glu, x = 1, Y = H2O; L = adip, x = 1.5, Y = H2O; L = seb, x = 1, Y = CH3CN were isolated. The composition and charge are proposed based on elemental analyses (C, H, N) and electrical conductivity measurements. UV-Vis and FTIR spectral data and magnetic moments were in accordance with high-spin Co(II) state. It is proposed that in all complexes Co(II) is hexa-coordinated out of cyclam ring and that both carboxylic groups from dicarboxylate bridge participate in coordination. Oxygens from one group are most likely bonded to the same Co(II) ion thus forming a four-membered ring. The in vitro antibacterial/antiproliferative activities of the complexes were in some cases enhanced compared with the simple Co(II) salt and free ligands, tested as controls.

  20. Preparation, characterisation and study of in vitro biologically active azamacrocyclic Cu(II) dicarboxylate complexes

    NASA Astrophysics Data System (ADS)

    Antonijević-Nikolić, Mirjana; Antić-Stanković, Jelena; Tanasković, Sladjana B.; Korabik, Maria J.; Gojgić-Cvijović, Gordana; Vučković, Gordana

    2013-12-01

    New cationic Cu(II) complexes with N, N‧, N″, N″‧-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and aliphatic dicarboxylic acids: pentanedioic (glutaric acid = glutH2), hexanedioic acid (adipic acid = adipH2) and decanedioic acid (sebacic acid = sebH2) of general formula [Cu4(L)(tpmc)2](ClO4)6·xH2O, L = glut, x = 2; L = adip, x = 7; L = seb, x = 6 were isolated. Their composition and charges are proposed based on elemental analyses and molar conductivity measurements. By the comparison of their UV-Vis, reflectance, FTIR and EPR spectral data, CV and SQUID magnetic measurements, with those for the complex with butanedioic acid (succinic acid = succH2) of known molecular structure and analysis of LC/MS spectra, geometry with two [Cu2tpmc]4+ units bridged by dicarboxylate dianion engaging all oxygens is proposed. Within units, Cu(II) ions are also bridged with N portion of cyclam ring. All four complexes were screened to in vitro antimicrobial and cytotoxic activity along with free primary and secondary ligands, Cu(II) salt and solvent controls. Detected antibacterial and cytotoxic activity for the complexes was enhanced in most cases than the corresponding controls.

  1. Dicarboxylic aciduria during ketotic phases in various types of glycogen storage disease.

    PubMed

    Pettersen, J E; Winsnes, A

    1981-01-01

    Urine samples were collected before and after a starvation period of 14-16 h from patients with glycogen storage disease, one with type III (amylo-1,6-glucosidase deficiency), four with type VIII (phosphorylase-b-kinase deficiency), and one with an unclassified type. The excretion of adipic, suberic, and 3-hydroxybutyric acid was measured by combined gas chromatography-mass spectrometry. The tendency towards ketosis seemed to decline with age in the patients with type VIII. In the non-ketotic patients no excess amounts of dicarboxylic acids were excreted. Therefore, glycogen storage disease per se seems to have no direct relationship to the excretion of adipic or suberic acid. A positive correlation was, however, found between the urinary excretion of on one side 3-hydroxybutyric and on the other adipic (correlation coefficient (Kendall's tau) +0.64, P less than 0.002 (one-sided test)) or suberic (+0.61, P less than 0.003) acid. The two dicarboxylic acids are most probably formed from long-chain monocarboxylic acids by omega- and beta-oxidation. It is speculated that succinyl-CoA formed by this pathway may counteract the tendency to ketosis in patients with glycogen storage disease.

  2. Differential effects of the substrate inhibitor l-trans-pyrrolidine-2,4-dicarboxylate (PDC) and the non-substrate inhibitor DL-threo-beta-benzyloxyaspartate (DL-TBOA) of glutamate transporters on neuronal damage and extracellular amino acid levels in rat brain in vivo.

    PubMed

    Montiel, T; Camacho, A; Estrada-Sánchez, A M; Massieu, L

    2005-01-01

    The extracellular concentration of glutamate is highly regulated by transporter proteins, due to its neurotoxic properties. Dysfunction or reverse activation of these transporters is related to the extracellular accumulation of excitatory amino acids and neuronal damage associated with ischemia and hypoglycemia. We have investigated by microdialysis the effects of the substrate and the non-substrate inhibitors of glutamate transporters, l-trans-2,4-pyrrolidine dicarboxylate (PDC) and DL-threo-beta-benzyloxyaspartate (DL-TBOA), respectively, on the extracellular levels of amino acids in the rat hippocampus in vivo. In addition, we have studied the effect of both inhibitors on neuronal damage after direct administration into the hippocampus and striatum. Electroencephalographic activity was recorded after the intrahippocampal infusion of DL-TBOA or PDC. Microdialysis administration of 500 microM DL-TBOA into the hippocampus increased 3.4- and nine-fold the extracellular levels of aspartate and glutamate, respectively. Upon stereotaxic administration it induced neuronal damage dose-dependently in CA1 and dentate gyrus, and convulsive behavior. Electroencephalographic recording showed the appearance of limbic seizures in the hippocampus after DL-TBOA infusion. In the striatum it also induced dose-dependent neuronal damage. These effects were prevented by the i.p. administration of the glutamate receptor antagonists (+)-5-methyl-10,11-dihydroxy-5H-dibenzo(a,d)cyclohepten-5,10-iminemaleate and 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)-quinoxaline. In contrast to dl-TBOA, PDC (500 microM) induced a more discrete elevation of excitatory amino acids levels (2.6- and three-fold in aspartate and glutamate, respectively), no neuronal damage or behavioral changes, and no alterations in electroencephalographic activity. The differential results obtained with DL-TBOA and PDC might be attributed to their distinct effects on the extracellular concentration of amino acids. Results

  3. Functional characterization of a Na+-dependent dicarboxylate transporter from Vibrio cholerae

    PubMed Central

    Mulligan, Christopher; Fitzgerald, Gabriel A.; Wang, Da-Neng

    2014-01-01

    The SLC13 transporter family, whose members play key physiological roles in the regulation of fatty acid synthesis, adiposity, insulin resistance, and other processes, catalyzes the transport of Krebs cycle intermediates and sulfate across the plasma membrane of mammalian cells. SLC13 transporters are part of the divalent anion:Na+ symporter (DASS) family that includes several well-characterized bacterial members. Despite sharing significant sequence similarity, the functional characteristics of DASS family members differ with regard to their substrate and coupling ion dependence. The publication of a high resolution structure of dimer VcINDY, a bacterial DASS family member, provides crucial structural insight into this transporter family. However, marrying this structural insight to the current functional understanding of this family also demands a comprehensive analysis of the transporter’s functional properties. To this end, we purified VcINDY, reconstituted it into liposomes, and determined its basic functional characteristics. Our data demonstrate that VcINDY is a high affinity, Na+-dependent transporter with a preference for C4- and C5-dicarboxylates. Transport of the model substrate, succinate, is highly pH dependent, consistent with VcINDY strongly preferring the substrate’s dianionic form. VcINDY transport is electrogenic with succinate coupled to the transport of three or more Na+ ions. In contrast to succinate, citrate, bound in the VcINDY crystal structure (in an inward-facing conformation), seems to interact only weakly with the transporter in vitro. These transport properties together provide a functional framework for future experimental and computational examinations of the VcINDY transport mechanism. PMID:24821967

  4. Polar organic marker compounds in atmospheric aerosol in the Po Valley during the Supersito campaigns - Part 1: Low molecular weight carboxylic acids in cold seasons

    NASA Astrophysics Data System (ADS)

    Pietrogrande, Maria Chiara; Bacco, Dimitri; Visentin, Marco; Ferrari, Silvia; Poluzzi, Vanes

    2014-04-01

    In the framework of the “Supersito” project, three intensive experimental campaigns were conducted in the Po Valley (Northern Italy) in cold seasons, such as late autumn, pre-winter and deep-winter, over three years from 2011 to 2013. As a part of a study on polar marker compounds, including carboxylic acids, sugar derivatives and lignin phenols, the present study reports a detailed discussion on the atmospheric concentrations of 14 low molecular weight carboxylic acids, mainly dicarboxylic and oxo-hydroxy carboxylic acids, as relevant markers of primary and secondary organic aerosols. PM2.5 samples were collected in two monitoring sites, representing urban and rural background stations. The total quantities of carboxylic acids were 262, 167 and 249 ng m-3 at the urban site and 308, 115, 248 ng m-3 at the rural site in pre-winter, fall and deep-winter, respectively. These high concentrations can be explained by the large human emission sources in the urbanized region, combined with the stagnant atmospheric conditions during the cold seasons that accumulate the organic precursors and accelerate the secondary atmospheric reactions. The distribution profiles of the investigated markers suggest the dominant contributions of primary anthropogenic sources, such as traffic, domestic heating and biomass burning. These results are confirmed by comparison with additional emission tracers, such as anhydro-saccharides for biomass burning and fatty acids originated from different anthropogenic sources. In addition, some secondary constituents were detected in both sites, as produced by in situ photo-chemical reactions from both biogenic (e.g. pinonic acid) and anthropogenic precursors (e.g. phthalic and adipic acids). The impact of different sources from human activities was elucidated by investigating the week pattern of carboxylic and fatty acid concentrations. The weekly trends of analytes during the warmer campaign (fall 2012; mean temperature: 12 °C) may be related to

  5. Hydrogen-bonding adducts of benzenepolycarboxylic acids with N,N-dimethylformamide: benzene-1,4-dicarboxylic acid N,N-dimethylformamide disolvate, benzene-1,2,4,5-tetracarboxylic acid N,N-dimethylformamide tetrasolvate and benzene-1,2,3-tricarboxylic acid N,N-dimethylformamide disolvate monohydrate.

    PubMed

    Dale, Sophie H; Elsegood, Mark R J

    2004-06-01

    The N,N-dimethylformamide (DMF) solvates of terephthalic acid, H(2)TA.2DMF (C(8)H(6)O(6).2C(3)H(7)NO), pyromellitic acid, H(4)PMA.4DMF (C(10)H(6)O(8).4C(3)H(7)NO), and hemimellitic acid, H(3)HMA.2DMF.H(2)O (C(9)H(6)O(6).2C(3)H(7)NO.H(2)O), are reported. The DMF solvate of terephthalic acid is centrosymmetric, containing one complete formula unit in the asymmetric unit. Both carboxylic acid groups hydrogen bond to a DMF molecule via an R(2)(2)(7) O-H.O/C-H.O motif. Discrete H(2)TA.2DMF units are observed. The DMF solvate of pyromellitic acid is centrosymmetric and the asymmetric unit contains half a formula unit. One of the unique carboxylic acid groups forms an R(2)(2)(7) motif with a DMF molecule, while the other forms a linear O-H.O hydrogen bond to the second unique DMF molecule. Discrete H(4)PMA.4DMF units are observed. The DMF solvate of hemimellitic acid is non-centrosymmetric and includes a molecule of water per formula unit. Both DMF molecules form an R(2)(2)(7) motif with the two outer carboxylic acid groups of HMA. A one-dimensional ladder structure is formed via hydrogen bonding between the central carboxylic acid group and the water molecules. The carboxylic acid R(2)(2)(8) head-to-tail motif is not observed in any of these examples. The inclusion of DMF thereby has the effect of limiting the dimensionality of the structures.

  6. SnapShot: Nucleic acid immune sensors, part 2.

    PubMed

    Hornung, Veit

    2014-12-18

    The innate immune system has evolved sensors that can detect specific molecular fingerprints of non-self RNA or DNA. At the same time, some receptors respond to nucleic acids of both exogenous and endogenous origin, yet they are spatially segregated from endogenous nucleic acids. This SnapShot schematizes families and individual members of nucleic acid sensors with a focus on their ligands and the signaling pathways they employ.

  7. Tuning structural dimensionalities of two new luminescent Cd(II) compounds: Different dicarboxylate coligands

    NASA Astrophysics Data System (ADS)

    Cao, Xiulian; Xing, Guang'en; Zhang, Yan

    2016-11-01

    Two new Cd(II) compounds, namely [Cd (tdc)(HPPA)]n·n (H2O) (1) and [Cd3 (obb)2(PPA)2(H2O)3]n (2) (H2tdc = 2,5-thiophenedicarboxylic acid, HPPA = pipemidic acid, H2oba = 4,4‧-oxybis (benzoate)), have been synthesized by incorporating pipemidic acid with Cd(II) ions and dicarboxylate coligands. Structural analyses reveal that compound 1 is a 1D chain structure, and further extended into a 2D supramolecular layered framework via intermolecular π…π and hydrogen bonding interactions, and compound 2 features a 3-fold interpenetrated 3D framework with 4-connected dia topology. HPPA ligand displays two different coordination modes in these two compounds. In addition, the thermal stabilities and luminescent properties of compounds 1 and 2 were also investigated in the solid state at room temperature.

  8. Diethyl 2,3-dihydro-thieno[3,4-b]-1,4-dioxine-5,7-dicarboxyl-ate.

    PubMed

    Ono, Katsuhiko; Tomura, Masaaki; Saito, Katsuhiro

    2008-01-18

    The title compound, C(12)H(14)O(6)S, is a dicarboxylic acid diethyl ester of 3,4-ethyl-enedioxy-thio-phene, which is a component of electrically conductive poly(3,4-ethyl-enedioxy-thio-phene) (PEDOT). The ethyl-ene group is disordered over two sites with occupancy factors 0.64 and 0.36. Both the carbonyl groups are coplanar with the thio-phene ring. The mol-ecules form centrosymmetric dimers with an R(2) (2)(12) coupling by inter-molecular C-H⋯O hydrogen bonds [3.333 (5) Å] at the ethoxy-carbonyl groups. The dimer units are arranged to form a ribbon-like mol-ecular sheet.

  9. Haloacetic acids in the aquatic environment. Part I: macrophyte toxicity.

    PubMed

    Hanson, Mark L; Solomon, Keith R

    2004-08-01

    Haloacetic acids (HAAs) are contaminants of aquatic ecosystems with numerous sources, both anthropogenic and natural. The toxicity of HAAs to aquatic plants is generally uncharacterized. Laboratory tests were conducted with three macrophytes (Lemna gibba, Myriophyllum sibiricum and Myriophyllum spicatum) to assess the toxicity of five HAAs. Myriophyllum spp. has been proposed as required test species for pesticide registration in North America, but few studies have been conducted under standard test conditions. The HAAs in the present experiments were monochloroacetic acid (MCA), dichloroacetic acid (DCA), trichloroacetic acid (TCA), trifluoroacetic acid (TFA) and chlorodifluoroacetic acid (CDFA). MCA was the most toxic to Myriophyllum spp. with EC50 values ranging from 8 to 12.4 mg/l depending on the endpoint, followed by DCA (EC50 range 62-722.5 mg/l), TCA (EC50 range 49.5-1702.6 mg/l), CDFA (EC50 range 105.3 to >10,000 mg/l) and with TFA (EC50 range 222.1 to 10,000 mg/l) the least toxic. Generally, L. gibba was less sensitive to HAA toxicity than Myriophyllum spp., with the difference in toxicity between them approximately threefold. The range of toxicity within Myriophyllum spp. was normally less than twofold. Statistically, plant length and node number were the most sensitive endpoints as they had the lowest observed coefficients of variation, but they were not the most sensitive to HAA toxicity. Toxicological sensitivity of endpoints varied depending on the measure of effect chosen and the HAA, with morphological endpoints usually an order of magnitude more sensitive than pigments for all plant species. Overall, mass and root measures tended to be the most sensitive indicators of HAA toxicity. The data from this paper were subsequently used in an ecological risk assessment for HAAs and aquatic plants. The assessment found HAAs to be of low risk to aquatic macrophytes and the results are described in the second manuscript of this series.

  10. Divergent layer topologies in divalent metal aliphatic dicarboxylate coordination polymers containing 3-pyridylmethylnicotinamide

    NASA Astrophysics Data System (ADS)

    White, Charmaine L.; Torres Salgado, Maria D.; Mizzi, Jessica E.; LaDuca, Robert L.

    2015-12-01

    Hydrothermal reaction of the requisite metal salt, an aliphatic dicarboxylic acid, and the hydrogen-bonding capable dipyridylamide ligand 3-pyridylmethylnicotinamide (3-pmna) resulted in four coordination polymers whose connectedness and layer topology depend on the metal coordination environment and dicarboxylate binding mode. These new crystalline phases were characterized by single crystal X-ray diffraction. [Cu(ox)(3-pmna)]n (1, ox = oxalate) manifests stacked 3-connected (6,3) herringbone layer motifs. {[Cd(mal)(3-pmna)(H2O)]·3H2O}n (2, mal = malonate) shows a 4-connected (4,4) grid topology with entrained water molecule trimeric chains in the interlamellar regions. {[Cd2(suc)2(3-pmna)(H2O)2]·3H2O}n (3, suc = succinate) possesses {Cd2O2} dimer-based [Cd(suc)]n layers pillared by 3-pmna ligands into a 5-connected sandwich motif with 4862 topology. {[Cd(glu)(3-pmna)(H2O)]·3H2O}n (4, glu = glutarate) manifests a rippled (4,4) grid topology. Luminescent behavior in the cadmium complexes is ascribed to intra-ligand molecular orbital transitions. Thermal decomposition behavior is also discussed herein.

  11. Application of optically active chiral bis(imidazolium) salts as potential receptors of chiral dicarboxylate salts of biological relevance.

    PubMed

    González-Mendoza, Laura; Escorihuela, Jorge; Altava, Belén; Burguete, M Isabel; Luis, Santiago V

    2015-05-21

    A family of chiral bis(imidazolium) salts derived from natural amino acids has been synthesized by a simple synthetic approach and the corresponding bis(trifluoromethylsulfonyl)imide salts have been shown to be room temperature chiral ionic liquids (RTCILs). The structures and self-assembling properties of the resulting salts have been studied by (1)HNMR, ATR-FTIR, DSC, SEM and theoretical calculations. Moreover, these receptors have been applied to the enantiomeric recognition of dicarboxylic amino acids. The supramolecular complexes formed have been studied by (1)HNMR titration experiments, ATR-FTIR and DSC.

  12. Synthesis, structures and properties of a series of manganese coordination complexes constructed from dicarboxylic fluorene derivatives

    SciTech Connect

    Li Xing; Zhao Xiuhua; Bing Yue; Zha Meiqin; Xie Hongzhen; Guo Zhiyong

    2013-01-15

    Assembly reactions of 9,9-diethylfluorene-2,7-dicarboxylic acid (H{sub 2}DFDC) and Mn(CH{sub 3}COO){sub 2}{center_dot}4H{sub 2}O or MnCl{sub 2}{center_dot}4H{sub 2}O by tuning of various secondary ligands such as 2,2 Prime -bipyridine (2,2 Prime -bpy), 4,4 Prime -bipyridine (4,4 Prime -bpy) or 1,3-bis(4-pyridyl)propane) (bpp), gave rise to four complexes {l_brace} [Mn{sub 2}(DFDC){sub 2}(DMF){sub 2}]{center_dot}H{sub 2}O{r_brace} {sub n} (1), [Mn(DFDC)(2,2 Prime -bpy)]{sub n} (2), {l_brace} [Mn{sub 2}(DFDC){sub 2}(4,4 Prime -bpy){sub 2}]{center_dot}2CH{sub 3}OH{r_brace} {sub n} (3), and {l_brace} [Mn{sub 4}(DFDC){sub 4}(bpp){sub 2}(CH{sub 3}OH){sub 3} (H{sub 2}O){sub 3}]{center_dot}3(CH{sub 3}OH){center_dot}3(H{sub 2}O){r_brace} {sub n} (4). Single crystal X-ray diffraction analysis reveal that complex 1 is three dimensional structure with rhombic channels filled by guest water molecules; 2 presents a close-packed structure with high thermal stability; 3 exhibits a three dimensional framework with micro-porous channels filled by guest methanol molecules and 4 is a two-dimensional structure. The photoluminescent properties of 1-4 have been studied, respectively, showing that the Mn(II) ions, accessorial organic ligands or crystal structures exert important influences on the photoluminescence emissions of H{sub 2}DFDC ligands. Thermogravimetric analysis show that the complexes have remarkably high thermal stability. Magnetic susceptibility measurements have been finished and discussed for the complexes. - Graphical abstract: Assembly of 9,9-diethylfluorene-2,7-dicarboxylic acid and Mn(II) salts by tuning of various accessorial ligands resulted in four manganese complexes with different topological frameworks. Highlights: Black-Right-Pointing-Pointer Four manganese complexes based on 9,9-diethylfluorene-2,7-dicarboxylic acid were obtained. Black-Right-Pointing-Pointer The complexes were structurally characterized by single-crystal X-ray diffraction. Black

  13. Studies of the acidic components of the Colorado Green River formation oil shale-Mass spectrometric identification of the methyl esters of extractable acids.

    NASA Technical Reports Server (NTRS)

    Haug, P.; Schnoes, H. K.; Burlingame, A. L.

    1971-01-01

    Study of solvent extractable acidic constituents of oil shale from the Colorado Green River Formation. Identification of individual components is based on gas chromatographic and mass spectrometric data obtained for their respective methyl esters. Normal acids, isoprenoidal acids, alpha, omega-dicarboxylic acids, mono-alpha-methyl dicarboxylic acids and methyl ketoacids were identified. In addition, the presence of monocyclic, benzoic, phenylalkanoic and naphthyl-carboxylic acids, as well as cycloaromatic acids, is demonstrated by partial identification.

  14. 40 CFR 721.3000 - Dicarboxylic acid monoester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CAUSE REPRODUCTIVE EFFECTS. —Do not get in eye, on skin, or clothing. —Do not breathe (vapor, mist.... —Discard contaminated leather shoes. —Wash thoroughly after handling, and before eating, drinking,...

  15. 40 CFR 721.3000 - Dicarboxylic acid monoester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CAUSE REPRODUCTIVE EFFECTS. —Do not get in eye, on skin, or clothing. —Do not breathe (vapor, mist.... —Discard contaminated leather shoes. —Wash thoroughly after handling, and before eating, drinking,...

  16. 40 CFR 721.3000 - Dicarboxylic acid monoester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CAUSE REPRODUCTIVE EFFECTS. —Do not get in eye, on skin, or clothing. —Do not breathe (vapor, mist.... —Discard contaminated leather shoes. —Wash thoroughly after handling, and before eating, drinking,...

  17. 40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL... Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113...

  18. 40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL... Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113...

  19. 40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL...—Alternate Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113...

  20. 40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL...—Alternate Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113...

  1. 40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL... BPT, BAT, BCT LIMITATIONS AND NEW SOURCE PERFORMANCE STANDARDS Pt. 434, App. A Appendix A to Part...

  2. Aerosol volatility and enthalpy of sublimation of carboxylic acids.

    PubMed

    Salo, Kent; Jonsson, Asa M; Andersson, Patrik U; Hallquist, Mattias

    2010-04-08

    The enthalpy of sublimation has been determined for nine carboxylic acids, two cyclic (pinonic and pinic acid) and seven straight-chain dicarboxylic acids (C(4) to C(10)). The enthalpy of sublimation was determined from volatility measurements of nano aerosol particles using a volatility tandem differential mobility analyzer (VTDMA) set-up. Compared to the previous use of a VTDMA, this novel method gives enthalpy of sublimation determined over an extended temperature range (DeltaT approximately 40 K). The determined enthalpy of sublimation for the straight-chain dicarboxylic acids ranged from 96 to 161 kJ mol(-1), and the calculated vapor pressures at 298 K are in the range of 10(-6)-10(-3) Pa. These values indicate that dicarboxylic acids can take part in gas-to-particle partitioning at ambient conditions and may contribute to atmospheric nucleation, even though homogeneous nucleation is unlikely. To obtain consistent results, some experimental complications in producing nanosized crystalline aerosol particles were addressed. It was demonstrated that pinonic acid "used as received" needed a further purification step before being suspended as a nanoparticle aerosol. Furthermore, it was noted from distinct differences in thermal properties that aerosols generated from pimelic acid solutions gave two types of particles. These two types were attributed to crystalline and amorphous configurations, and based on measured thermal properties, the enthalpy of vaporization was 127 kJ mol(-1) and that of sublimation was 161 kJ mol(-1). This paper describes a new method that is complementary to other similar methods and provides an extension of existing experimental data on physical properties of atmospherically relevant compounds.

  3. Fatty acid facts, Part I. Essential fatty acids as treatment for depression, or food for mood?

    PubMed

    Pawels, E K J; Volterrani, D

    2008-10-01

    The epidemic character of depressive disorders has prompted further research into dietary habits that could make an etiological contribution. One clear change in the diet of the population in developed countries has been the replacement of omega-3 polyunsaturated fatty acids by saturated fats and trans-fats as well as by omega-6 polyunsaturated fatty acids. Omega-3 and omega-6 fatty acids are essential fatty acids, and the members of the -3 and -6 series are crucial for human health. In biochemical processes there is a competition between these two series. A higher dietary intake of omega-6 results in the excessive incorporation of these molecules in the cell membrane with numerous pathological consequences, presumably due to the formation of proinflammatory eicosanoids. Members of the omega-3 family and their derivatives modulate the inflammatory action. Essential fatty acids play a major role in brain development and brain functioning. The omega-3 series members docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) provide fluidity to the cell membrane, facilitating certain processes including neurotransmission and ion channel flow. It is thought that omega-3 deficiency during the fetal and postnatal period may have a long-term effect at various levels. Epidemiological studies have demonstrated a positive association between omega-3 deficits and mood disorders. As for treatment, there is convincing evidence that add-on omega-3 fatty acids to standard antidepressant pharmacotherapy results in improved mood. There is no evidence that fatty acid monotherapy has a mood-elevating effect, with a possible exception for childhood depression. There are indications that omega-3 has a prophylactic effect on perinatal depression and has a negative effect on natural killer cell activity and T-lymphocyte function. These observations need further study in view of the popularity of self-medication.

  4. Metabolism: Part II. The Tricarboxylic Acid (TCA), Citric Acid, or Krebs Cycle.

    ERIC Educational Resources Information Center

    Bodner, George M.

    1986-01-01

    Differentiates the tricarboxylic acid (TCA) cycle (or Krebs cycle) from glycolysis, and describes the bridge between the two as being the conversion of pyruvate into acetyl coenzyme A. Discusses the eight steps in the TCA cycle, the results of isotopic labeling experiments, and the net effects of the TCA cycle. (TW)

  5. Magnetic coupling in a hybrid Mn(ii) acetylene dicarboxylate.

    PubMed

    Hendon, Christopher H; Pradaux-Caggiano, Fabienne; Hatcher, Lauren E; Gee, William J; Wilson, Chick C; Butler, Keith T; Carbery, David R; Walsh, Aron; Melot, Brent C

    2016-12-07

    The design of ligands that mediate through-bond long range super-exchange in metal-organic hybrid materials would expand chemical space beyond the commonly observed short range, low temperature magnetic ordering. Here we examine acetylene dicarboxylate as a potential ligand that could install long range magnetic ordering due to its spatially continuous frontier orbitals. Using a known Mn(ii)-containing coordination polymer we compute and measure the electronic structure and magnetic ordering. In this case, the latter is weak owing to the sub-optimal ligand coordination geometry, with a critical temperature of 2.5 K.

  6. Solvothermal synthesis and structure of 3D frameworks of Nd(III) and Y(III) with thiophene-2,5-dicarboxylate and N,N‧-diethylformamide

    NASA Astrophysics Data System (ADS)

    Sharma, Swati; Yawer, Mohd; Kariem, Mukaddus; Sheikh, Haq Nawaz

    2016-08-01

    Two new 3D MOFs [Nd2(TDA)3(DEF)2(H2O)]n (1) and [Y4(TDA)6(DEF)4]n (2) [Thiophene-2,5-dicarboxylic acid (H2TDA) and N,N‧-diethylformamide (DEF)] were synthesized by solvothermal method. They were characterized by elemental analyses, infrared spectroscopy and single crystal X-ray diffraction studies. The two MOFs (1) and (2) belong to the monoclinic system with space group P21/n and C 2 respectively. Structural characterizations by single-crystal X-ray crystallography reveal that 1 and 2 adopt three-dimensional frameworks constructed by cross-linking of rod shaped infinite chain secondary building unit (SBU) by thiophene-2,5-dicarboxylates as linker. These frameworks feature rhomboidal channels, inside which coordinated DEF/H2O solvent molecules are located. DEF plays pivotal role in reaction and design of MOFs. Thermogravimetric analysis shows that both MOFs are thermally robust.

  7. Identification and Functional Characterization of a Tonoplast Dicarboxylate Transporter in Tomato (Solanum lycopersicum)

    PubMed Central

    Liu, Ruiling; Li, Boqiang; Qin, Guozheng; Zhang, Zhanquan; Tian, Shiping

    2017-01-01

    Acidity plays an important role in flavor and overall organoleptic quality of fruit and is mainly due to the presence of organic acids. Understanding the molecular basis of organic acid metabolism is thus of primary importance for fruit quality improvement. Here, we cloned a putative tonoplast dicarboxylate transporter gene (SlTDT) from tomato, and submitted it to the NCBI database (GenBank accession number: KC733165). SlTDT protein contained 13 putative transmembrane domains in silico analysis. Confocal microscopic study using green fluorescent fusion proteins revealed that SlTDT was localized on tonoplast. The expression patterns of SlTDT in tomato were analyzed by RT-qPCR. The results indicated that SlTDT expressed in leaves, roots, flowers and fruits at different ripening stages, suggesting SlTDT may be associated with the development of different tissues. To further explore the function of SlTDT, we constructed both overexpression and RNAi vectors and obtained transgenic tomato plants by agrobacterium-mediated method. Gas chromatography-mass spectrometer (GC-MS) analysis showed that overexpression of SlTDT significantly increased malate content, and reduced citrate content in tomato fruit. By contrast, repression of SlTDT in tomato reduced malate content of and increased citrate content. These results indicated that SlTDT played an important role in remobilization of malate and citrate in fruit vacuoles. PMID:28261242

  8. Identification and Functional Characterization of a Tonoplast Dicarboxylate Transporter in Tomato (Solanum lycopersicum).

    PubMed

    Liu, Ruiling; Li, Boqiang; Qin, Guozheng; Zhang, Zhanquan; Tian, Shiping

    2017-01-01

    Acidity plays an important role in flavor and overall organoleptic quality of fruit and is mainly due to the presence of organic acids. Understanding the molecular basis of organic acid metabolism is thus of primary importance for fruit quality improvement. Here, we cloned a putative tonoplast dicarboxylate transporter gene (SlTDT) from tomato, and submitted it to the NCBI database (GenBank accession number: KC733165). SlTDT protein contained 13 putative transmembrane domains in silico analysis. Confocal microscopic study using green fluorescent fusion proteins revealed that SlTDT was localized on tonoplast. The expression patterns of SlTDT in tomato were analyzed by RT-qPCR. The results indicated that SlTDT expressed in leaves, roots, flowers and fruits at different ripening stages, suggesting SlTDT may be associated with the development of different tissues. To further explore the function of SlTDT, we constructed both overexpression and RNAi vectors and obtained transgenic tomato plants by agrobacterium-mediated method. Gas chromatography-mass spectrometer (GC-MS) analysis showed that overexpression of SlTDT significantly increased malate content, and reduced citrate content in tomato fruit. By contrast, repression of SlTDT in tomato reduced malate content of and increased citrate content. These results indicated that SlTDT played an important role in remobilization of malate and citrate in fruit vacuoles.

  9. Organic acids tunably catalyze carbonic acid decomposition.

    PubMed

    Kumar, Manoj; Busch, Daryle H; Subramaniam, Bala; Thompson, Ward H

    2014-07-10

    Density functional theory calculations predict that the gas-phase decomposition of carbonic acid, a high-energy, 1,3-hydrogen atom transfer reaction, can be catalyzed by a monocarboxylic acid or a dicarboxylic acid, including carbonic acid itself. Carboxylic acids are found to be more effective catalysts than water. Among the carboxylic acids, the monocarboxylic acids outperform the dicarboxylic ones wherein the presence of an intramolecular hydrogen bond hampers the hydrogen transfer. Further, the calculations reveal a direct correlation between the catalytic activity of a monocarboxylic acid and its pKa, in contrast to prior assumptions about carboxylic-acid-catalyzed hydrogen-transfer reactions. The catalytic efficacy of a dicarboxylic acid, on the other hand, is significantly affected by the strength of an intramolecular hydrogen bond. Transition-state theory estimates indicate that effective rate constants for the acid-catalyzed decomposition are four orders-of-magnitude larger than those for the water-catalyzed reaction. These results offer new insights into the determinants of general acid catalysis with potentially broad implications.

  10. Conjugated fatty acids increase energy expenditure in part by increasing voluntary movement in mice.

    PubMed

    Park, Yooheon; Park, Yeonhwa

    2012-07-15

    Conjugated linoleic acid (CLA) and conjugated nonadecadienoic acid (CNA) have been previously shown to effectively reduce body fat. However, it is not clear if these effects persist with extended feeding, including potential mechanisms of increased energy expenditure. Thus the current investigation was conducted to determine the influence of dietary conjugated fatty acids on non-exercise form of voluntary movement and lipid and glucose metabolisms for 4-12 week feeding of male mice. CLA and CNA significantly reduced body weight and fat mass by increasing energy expenditure, in part by increasing voluntary movement. CLA and CNA significantly reduced serum leptin and tumour necrosis factor-α, while modulating the mRNA levels of genes associated with lipid and glucose metabolisms. The current results of increased physical activity along with modulation of lipid and glucose metabolisms by conjugated fatty acids will help contribute to future applications of these toward controlling obesity.

  11. Atmospheric oxalic acid and related secondary organic aerosols in Qinghai Lake, a continental background site in Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Meng, Jingjing; Wang, Gehui; Li, Jianjun; Cheng, Chunlei; Cao, Junji

    2013-11-01

    Summertime PM2.5 aerosols collected from Qinghai Lake (3200 m a.s.l.), a remote continental site in the northeastern part of Tibetan Plateau, were analyzed for dicarboxylic acids (C2-C11), ketocarboxylic acids and α-dicarbonyals. Oxalic acid (C2) is the dominant dicarboxylic acid in the samples, followed by malonic, succinic and azelaic acids. Total dicarboxylic acids (231 ± 119 ng m-3), ketocarboxylic acids (8.4 ± 4.3 ng m-3), and α-dicarbonyls (2.7 ± 2.1 ng m-3) at the Tibetan background site are 2-5 times less than those detected in lowland areas such as 14 Chinese megacities. Compared to those in other urban and marine areas enhancements in relative abundances of C2/total diacids and diacids-C/WSOC of the PM2.5 samples suggest that organic aerosols in the region are more oxidized due to strong solar radiation. Molecular compositions and air mass trajectories demonstrate that the above secondary organic aerosols in the Qinghai Lake atmosphere are largely derived from long-range transport. Ratios of oxalic acid, glyoxal and methylglyoxal to levoglucosan in PM2.5 aerosols emitted from household burning of yak dung, a major energy source for Tibetan in the region, are 30-400 times lower than those in the ambient air, which further indicates that primary emission from biomass burning is a negligible source of atmospheric oxalic acid and α-dicarbonyls at this background site.

  12. Isolation and Identification of Ferulic Acid From Aerial Parts of Kelussia odoratissima Mozaff.

    PubMed Central

    Sajjadi, Seyed Ebrahim; Shokoohinia, Yalda; Moayedi, Narjess-Sadat

    2012-01-01

    Background Kelussia odoratissima Mozaff. is one of the newest genera of Umbelliferae which is represented by only one species. This sweet-smelling, self-growing monotypic medicinal plant is endemic to a restricted area in west of Iran and is locally called Karafse-koohi. The aerial parts of the plant are commonly used as a popular garnish and a sedative medicinal plant. There are several reports concerning antioxidant, anti-inflammatory, anxiolytic and hypolipidemic activities of aerial parts of K. odoratissima. Objectives The current research aimed to evaluate some phenolic contents of the plant for the first time .It is confirmed that secondary metabolites and especially phenolic compounds have important role in the biological activities of the plant. Available information indicates that phenolic contents of K. odoratissima have not been the subject of any investigation Material and Methods Aerial parts of K. odoratissima were extracted with acetone by maceration method. Normal and reversed phase vacuum liquid chromatography used to fractionate the extract. 1H-NMR, 13CNMR, EI-Mass and IR spectra were used to elucidate isolated compound. Results The phenolic acid isolated compound was identified as 4-hydroxy-3-methoxycinnamic acid (ferulic acid). Conclusions Compared with previous reported antioxidant and anti-inflammatory properties of ferulic acid, a chemical-biological relation can be postulated. PMID:24624175

  13. Costs of jasmonic acid induced defense in aboveground and belowground parts of corn (Zea mays L.).

    PubMed

    Feng, Yuanjiao; Wang, Jianwu; Luo, Shiming; Fan, Huizhi; Jin, Qiong

    2012-08-01

    Costs of jasmonic acid (JA) induced plant defense have gained increasing attention. In this study, JA was applied continuously to the aboveground (AG) or belowground (BG) parts, or AG plus BG parts of corn (Zea mays L.) to investigate whether JA exposure in one part of the plant would affect defense responses in another part, and whether or not JA induced defense would incur allocation costs. The results indicated that continuous JA application to AG parts systemically affected the quantities of defense chemicals in the roots, and vice versa. Quantities of DIMBOA and total amounts of phenolic compounds in leaves or roots generally increased 2 or 4 wk after the JA treatment to different plant parts. In the first 2 wk after application, the increase of defense chemicals in leaves and roots was accompanied by a significant decrease of root length, root surface area, and root biomass. Four weeks after the JA application, however, no such costs for the increase of defense chemicals in leaves and roots were detected. Instead, shoot biomass and root biomass increased. The results suggest that JA as a defense signal can be transferred from AG parts to BG parts of corn, and vice versa. Costs for induced defense elicited by continuous JA application were found in the early 2 wk, while distinct benefits were observed later, i.e., 4 wk after JA treatment.

  14. [The content of phenolic acids in the edible parts of selected varieties of apples].

    PubMed

    Malik, Agnieszka; Kiczorowska, Bozena; Zdyb, Justyna

    2009-01-01

    Fruits and vegetables are essential sources of many nutritive substances which are necessary for normal function of the organism. One of the mostly consumed fruits in many European countries, including Poland is apples. The prohealthy properties of apples are associated with the contents of polyphenolic compounds, thus including in parts phenolic acids which have antioxidant properties. The concentration of these compounds depends on many factors such as variety climate and soil conditions, maturity as well as agro technical operations. The aim of this investigation was to compare the concentrations of phenolic acids and epicatechin in the varieties of apple Champion and Jonica, which were collected from different orchards around Lublin. The phenolic compounds were assayed using a Symmetry column carrier RP-C18 (Waters) integrated with a high pressure liquid chromatography apparatus. The dominant phenolic acids found in the Champion variety was chlorogenic acid, whereas in the Jonica variety, chlorogenic and homovanilic acids were the dominate once. The highest concentrations of chlorogenic acid was detected in the pulp of an apple (Jonica variety) collected from the orchards around the cities of Puławy and Lublin, whereas homovanilic acid was the highest in the other samples collected from the orchards in the vicinity of Stryjno and Góry Markuszowskie. Among the Jonica and Champion varieties of apples collected from various orchards in the vicinity of Lublin, the highest content of epicatechin (13,12 mg/kg) was found in the pulps of Champions variety collected in Puławy. In general, the Champion variety was the best source of phenolic acids and epicatechin compared to the Jonica variety independent of the harvest zone.

  15. Gas chromatography-mass spectrometry profile of urinary organic acids of Wistar rats orally treated with ozonized unsaturated triglycerides and ozonized sunflower oil.

    PubMed

    Jardines, Daniel; Correa, Teresa; Ledea, Oscar; Zamora, Zullyt; Rosado, Aristides; Molerio, Jesús

    2003-01-15

    The main products in the ozonolysis of unsaturated triglycerides or vegetable oils are peroxides, aldehydes, Criegee ozonides and carboxylic acids. Some of these compounds are present in different concentrations in the biological fluids. The aim of this work is to study, using gas chromatography-mass spectrometry (GC-MS), the organic acid excretion in urine of rats orally treated with ozonized sunflower oil (OSO), ozonized triolein or ozonized trilinolein. Oral administration of OSO to Wistar rats has produced changes in the urinary content of dicarboxylic organic acids. Among others heptanedioic (pimelic acid) and nonanedioic acids (azelaic acid) were the major increased dicarboxylic acids found. The urinary dicarboxylic acid profiles of rats which received ozonized triolein only showed an increase in heptanedioic and nonanedioic acids. However, when ozonized trilinolein is applied, the profile is similar to that obtained when OSO is administered. A biochemical mechanism is proposed to explain the formation of dicarboxylic acids from ozonated unsaturated triglycerides.

  16. Effect of acid pretreatment on different parts of corn stalk for second generation ethanol production.

    PubMed

    Li, Ping; Cai, Di; Luo, Zhangfeng; Qin, Peiyong; Chen, Changjing; Wang, Yong; Zhang, Changwei; Wang, Zheng; Tan, Tianwei

    2016-04-01

    In this study, the effects of different parts of corn stalk, including stem, leaf, flower, cob and husk on second generation ethanol production were evaluated. FTIR, XRD and SEM were performed to investigate the effect of dilute acid pretreatment. The bagasse obtained after pretreatment were further hydrolyzed by cellulase and used as the substrate for ethanol fermentation. As results, hemicelluloses fractions in different parts of corn stalk were dramatically removed and the solid fractions showed vivid compositions and crystallinities. Compared with other parts of corn stalk, the cob had higher sugar content and better enzymatic digestibility. The highest glucose yield of 94.2% and ethanol production of 24.0 g L(-1) were achieved when the cob was used as feedstock, while the glucose yield and the ethanol production were only 86.0% and 17.1 g L(-1) in the case of flower.

  17. An approach to the design of molecular solids. The ureylenedicarboxylic acids

    SciTech Connect

    Zhao, Xinqi; Chang, Yuhloo; Fowler, F.W.; Lauher, J.W. )

    1990-08-29

    The crystal structures of a series of ureylenedicarboxylic acids have been determined as part of a project directed toward the design of molecular solids. The ureylenedicarboxylic acids were chosen for study because they were predicted to form a two-dimensional hydrogen-bonded network. This two-dimensional network is the result of two orthogonal linear arrays of self-complementary hydrogen-bonded functionalities, the dicarboxylic acids and N,N{prime}-disubstituted ureas, being present in the same molecule. The simplest molecules of the series, 2,2{prime}-ureylenediacetic acid (1), 3,3{prime}-ureylenedipropionic acid (2), and 4,4{prime}-ureylenedibutyric acid (3) as well as the simplest ureylene derived from a dipeptide, N,N{prime}-carbonylbisglycylglycine (4) were synthesized and studied by using x-ray crystallographic techniques. Each molecule was found to crystallize to give the predicted solid-state structure.

  18. A partly folded state of acidic fibroblast growth factor at low pH.

    PubMed

    Sanz, J M; Giménez-Gallego, G

    1997-06-01

    Acid denaturation of acidic fibroblast growth factor (aFGF) at low ionic strength was monitored by far-ultraviolet circular dichroism and intrinsic fluorescence. The two spectroscopic probes displayed non-coincident transitions, which suggested the accumulation of partly folded species around pH 4.0. Although under these conditions the fluorescence of aFGF resembled that of the unfolded form of the protein, far-ultraviolet circular dichroism and proton nuclear magnetic resonance spectra indicated the presence of persistent secondary and tertiary structure. Moreover, at pH 4.0, aFGF showed cooperative thermal denaturation and interacted weakly with the hydrophobic probe N-phenyl-1-naphthylamine, showing a relatively high level of structure that did not fit into the classical molten globule category. This intermediate is also capable of interacting with liposomes and might represent a membrane translocation-competent form.

  19. Methanolysis on extracted sapfrom inner and outer part of core oil palm trunk using phosphomolybdic acid and aluminium sulphate

    NASA Astrophysics Data System (ADS)

    Jahar, Noorhasmiera Abu; Mostapha, Marhaini; Wong, Jia Chye; Jaafar, Sharifah Nabihah Syed; Pua, Grace; Zakaria, Sarani; Chia, Chin Hua

    2016-11-01

    Concentration of extracted free sugar in the oil palm trunk from inner and outer part was analysed using High Performance Liquid Chromatography (HPLC). The highest sugar concentration was glucose and total sugar content was higher in the inner part than the outer part. The methanolysis reaction of extracted sapfrom inner and outer part of core oil palm trunk using phosphomolybdic acid and aluminium sulphate was done using methanol as solvent, 2.5 h and at 160°C. In this reaction, conversion of total sugar produced high concentrations of pentanoic acid, 4-oxo-, methyl ester and low 5-hydroxymethylfurfural using aluminium sulphate as catalyst.

  20. Carbon honeycomb grids for advanced lead-acid batteries. Part III: Technology scale-up

    NASA Astrophysics Data System (ADS)

    Kirchev, A.; Serra, L.; Dumenil, S.; Brichard, G.; Alias, M.; Jammet, B.; Vinit, L.

    2015-12-01

    The carbon honeycomb grid technology employs new carbon/carbon composites with ordered 3D structure instead of the classic lead-acid battery current collectors. The technology is laboratory scaled up from small size grids corresponding to electrodes with a capacity of 3 Ah to current collectors suitable for assembly of lead-acid batteries covering the majority of the typical lead-acid battery applications. Two series of 150 grids each (one positive and one negative) are manufactured using low-cost lab-scale equipment. They are further subjected to pasting with active materials and the resulting battery plates are assembled in 12 V AGM-VLRA battery mono-blocks for laboratory testing and outdoor demonstration in electric scooter replacing its original VRLAB pack. The obtained results demonstrate that the technology can replace successfully the state of the art negative grids with considerable benefits. The use of the carbon honeycomb grids as positive plate current collectors is limited by the anodic corrosion of the entire structure attacking both the carbon/carbon composite part and the electroplated lead-tin alloy coating.

  1. Solid state 19F NMR parameters of fluorine-labeled amino acids. Part I: Aromatic substituents

    NASA Astrophysics Data System (ADS)

    Dürr, Ulrich H. N.; Grage, Stephan L.; Witter, Raiker; Ulrich, Anne S.

    2008-03-01

    Structural parameters of peptides and proteins in biomembranes can be directly measured by solid state NMR of selectively labeled amino acids. The 19F nucleus is a promising label to overcome the low sensitivity of 2H, 13C or 15N, and to serve as a background-free reporter group in biological compounds. To make the advantages of solid state 19F NMR fully available for structural studies of polypeptides, we have systematically measured the chemical shift anisotropies and relaxation properties of the most relevant aromatic and aliphatic 19F-labeled amino acids. In this first part of two consecutive contributions, six different 19F-substituents on representative aromatic side chains were characterized as polycrystalline powders by static and MAS experiments. The data are also compared with results on the same amino acids incorporated in synthetic peptides. The spectra show a wide variety of lineshapes, from which the principal values of the CSA tensors were extracted. In addition, temperature-dependent T1 and T2 relaxation times were determined by 19F NMR in the solid state, and isotropic chemical shifts and scalar couplings were obtained in solution.

  2. Coligand-regulated assembly, fluorescence, and magnetic properties of Co(II) and Cd(II) complexes with a non-coplanar dicarboxylate

    SciTech Connect

    Xin, Ling-Yun; Liu, Guang-Zhen; Ma, Lu-Fang; Wang, Li-Ya

    2013-10-15

    A non-coplanar dicarboxylate ndca (H{sub 2}ndca=5-norbornene-2,3-dicarboxylic acid), combining with various dipyridyl-typed tectons, constructs six Cd(II)/Co(II) coordination polymers under hydrothermal conditions, namely [Co(ndca)(H{sub 2}O)]{sub n} (1), ([Co(ndca)(bpe)(H{sub 2}O)]·H{sub 2}O){sub n} (2), [Co(ndca)(bpa){sub 0.5}(H{sub 2}O)]{sub n} (3), [Cd(ndca)(bpe)(H{sub 2}O)]{sub n} (4), ([Cd(ndca)(bpa)(H{sub 2}O)]·0.5H{sub 2}O){sub n} (5), and ([Cd(ndca)(bpp) (H{sub 2}O)]·H{sub 2}O){sub n} (6) (bpe=1,2-di(4-pyridyl)ethylene, bpa=1,2-bi(4-pyridyl)ethane, and bpp=1,3-bis(4-pyridyl)propane). All these compounds contain various metal(II)–carboxylate motifs, including carboxylate binuclear (2, 4, 5), carboxylate chain (1, 6) and carboxylate layer (3), which are further extended by dipyridyl-typed coligands to afford a vast diversity of the structures with 2D pyknotic layers (1, 6), 2D open layer (5), 2D→3D interpenetrated networks (2,4), and 3D pillared-layer framework (3), respectively. In addition, fluorescent spectra of Cd(II) complexes and magnetic properties of Co(II) complexes are also given. - Graphical abstract: Six various cadmium(II)/cobalt(II)–organic frameworks were constructed by 5-norbornene-2,3-dicarboxylic acid and different bis(pyridine) rod-like tectons, and Cd (II) complexes exhibit blue–violet emissions, whereas Co (II) complexes show antiferromagnetic behaviours. Display Omitted.

  3. Measurements of oxalic acid, oxalates, malonic acid, and malonates in atmospheric particulates.

    PubMed

    Yang, Liming; Yu, Liya E

    2008-12-15

    This study systematically examined effects of analytical approaches on resultant concentrations of oxalic acid, oxalates, malonic acid, and malonates. Results demonstrated that employing separate water extraction and THF extraction is required to properly quantify dicarboxylic acids vs dicarboxylates using IC or GC-MS. Applications of the recommended methods to analyze PM2.5 collected in Singapore showed that concentrations of oxalate ranged from 361.4 to 481.4 ng m(-3), which were 10-14.7 times higher than that of oxalic acid. Unlike that of oxalates, malonate concentrations (10.5-23.4 ng m(-3)) were no more than half of malonic acid concentration (43.8-53.9 ng m(-3)) in PM2.5. Concentration ratios of oxalate-to-oxalic acid and malonate-to-malonic acid obtained from this work were applied to reported literature data; as a first approximation, in urban environments similar to that in Singapore, quantifiable oxalic acid, oxalates, malonic acid, and malonates in PM2.5 could range from 7.6 to 68.0, 82.2 to 732.8, 6.3 to 150, and 1.3 to 60 ng m(-3), respectively. Because photooxidation properties and hygroscopicity of dicarboxylic acids can substantially differ from that of dicarboxylates, more studies are needed to quantify ambient oxalic acid and malonic acid vs oxalates and malonates.

  4. 40 CFR 174.507 - Nucleic acids that are part of a plant-incorporated protectant; exemption from the requirement of...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Nucleic acids that are part of a plant... PLANT-INCORPORATED PROTECTANTS Tolerances and Tolerance Exemptions § 174.507 Nucleic acids that are part... nucleic acids that are part of a plant-incorporated protectant are exempt from the requirement of...

  5. 40 CFR 174.507 - Nucleic acids that are part of a plant-incorporated protectant; exemption from the requirement of...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Nucleic acids that are part of a plant... PLANT-INCORPORATED PROTECTANTS Tolerances and Tolerance Exemptions § 174.507 Nucleic acids that are part... nucleic acids that are part of a plant-incorporated protectant are exempt from the requirement of...

  6. 40 CFR 174.507 - Nucleic acids that are part of a plant-incorporated protectant; exemption from the requirement of...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Nucleic acids that are part of a plant... PLANT-INCORPORATED PROTECTANTS Tolerances and Tolerance Exemptions § 174.507 Nucleic acids that are part... nucleic acids that are part of a plant-incorporated protectant are exempt from the requirement of...

  7. 40 CFR 174.507 - Nucleic acids that are part of a plant-incorporated protectant; exemption from the requirement of...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Nucleic acids that are part of a plant... PLANT-INCORPORATED PROTECTANTS Tolerances and Tolerance Exemptions § 174.507 Nucleic acids that are part... nucleic acids that are part of a plant-incorporated protectant are exempt from the requirement of...

  8. 40 CFR 174.507 - Nucleic acids that are part of a plant-incorporated protectant; exemption from the requirement of...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Nucleic acids that are part of a plant... PLANT-INCORPORATED PROTECTANTS Tolerances and Tolerance Exemptions § 174.507 Nucleic acids that are part... nucleic acids that are part of a plant-incorporated protectant are exempt from the requirement of...

  9. Effect of Heat Sealing Temperature on Mechanical Properties and Molecular Structure at Heat-Sealed Parts of Polylactic Acid Film —Part II

    NASA Astrophysics Data System (ADS)

    Hashimoto, Yumi; Hashimoto, Yasuo; Tsujii, Tetsuya; Morimoto, Mitsuhiko; Kotaki, Masaya; Hamada, Hiroyuki

    Actual failure accidents of plastic bags often occur at the pin-hole and/or the crack, and also the edge that is just outside of the heat-sealed part becomes the failure initiation point. In this study, fracture mechanics tests and tear tests were performed to understand the resistance of heat-sealed parts and edge parts to introduced cracks. The fracture resistance and tear strength of the edge part was lower than that of the heat-sealed part, which was more obvious at higher heat sealing temperature. The optimum heat sealing temperature to obtain the balanced properties of heat-sealed polylactic acid (PLA) films was found to be 130°C.

  10. Lead-acid batteries in micro-hybrid applications. Part II. Test proposal

    NASA Astrophysics Data System (ADS)

    Schaeck, S.; Stoermer, A. O.; Albers, J.; Weirather-Koestner, D.; Kabza, H.

    In the first part of this work [1] selected key parameters for applying lead-acid (LA) batteries in micro-hybrid power systems (MHPS) were investigated. Main results are integrated in an accelerated, comprehensive test proposal presented here. The test proposal aims at a realistic representation of the pSoC operation regime, which is described in Refs. [1,6]. The test is designed to be sensitive with respect to dynamic charge acceptance (DCA) at partially discharged state (critical for regenerative braking) and the internal resistance at high-rate discharge (critical for idling stop applications). First results are presented for up-to-date valve-regulated LA batteries with absorbent glass mat (AGM) separators. The batteries are close to the limits of the first proposal of pass/fail-criteria. Also flooded batteries were tested; the first out of ten units failed already.

  11. A dicarboxylate/4-hydroxybutyrate autotrophic carbon assimilation cycle in the hyperthermophilic Archaeum Ignicoccus hospitalis.

    PubMed

    Huber, Harald; Gallenberger, Martin; Jahn, Ulrike; Eylert, Eva; Berg, Ivan A; Kockelkorn, Daniel; Eisenreich, Wolfgang; Fuchs, Georg

    2008-06-03

    Ignicoccus hospitalis is an anaerobic, autotrophic, hyperthermophilic Archaeum that serves as a host for the symbiotic/parasitic Archaeum Nanoarchaeum equitans. It uses a yet unsolved autotrophic CO(2) fixation pathway that starts from acetyl-CoA (CoA), which is reductively carboxylated to pyruvate. Pyruvate is converted to phosphoenol-pyruvate (PEP), from which glucogenesis as well as oxaloacetate formation branch off. Here, we present the complete metabolic cycle by which the primary CO(2) acceptor molecule acetyl-CoA is regenerated. Oxaloacetate is reduced to succinyl-CoA by an incomplete reductive citric acid cycle lacking 2-oxoglutarate dehydrogenase or synthase. Succinyl-CoA is reduced to 4-hydroxybutyrate, which is then activated to the CoA thioester. By using the radical enzyme 4-hydroxybutyryl-CoA dehydratase, 4-hydroxybutyryl-CoA is dehydrated to crotonyl-CoA. Finally, beta-oxidation of crotonyl-CoA leads to two molecules of acetyl-CoA. Thus, the cyclic pathway forms an extra molecule of acetyl-CoA, with pyruvate synthase and PEP carboxylase as the carboxylating enzymes. The proposal is based on in vitro transformation of 4-hydroxybutyrate, detection of all enzyme activities, and in vivo-labeling experiments using [1-(14)C]4-hydroxybutyrate, [1,4-(13)C(2)], [U-(13)C(4)]succinate, or [1-(13)C]pyruvate as tracers. The pathway is termed the dicarboxylate/4-hydroxybutyrate cycle. It combines anaerobic metabolic modules to a straightforward and efficient CO(2) fixation mechanism.

  12. Manipulating the Rate-Limiting Step in Water Oxidation Catalysis by Ruthenium Bipyridine–Dicarboxylate Complexes

    DOE PAGES

    Shaffer, David W.; Xie, Yan; Szalda, David J.; ...

    2016-11-01

    In order to gain a deeper mechanistic understanding of water oxidation by [(bda)Ru(L)2] catalysts (bdaH2 = [2,2'-bipyridine]-6,6'-dicarboxylic acid; L = pyridine-type ligand), a series of modified catalysts with one and two trifluoromethyl groups in the 4 position of the bda2– ligand was synthesized and studied using stopped-flow kinetics. The additional $-$CF3 groups increased the oxidation potentials for the catalysts and enhanced the rate of electrocatalytic water oxidation at low pH. Stopped-flow measurements of cerium(IV)-driven water oxidation at pH 1 revealed two distinct kinetic regimes depending on catalyst concentration. At relatively high catalyst concentration (ca. ≥10–4 M), the rate-determining step (RDS)more » was a proton-coupled oxidation of the catalyst by cerium(IV) with direct kinetic isotope effects (KIE > 1). At low catalyst concentration (ca. ≤10–6 M), the RDS was a bimolecular step with kH/kD ≈ 0.8. The results support a catalytic mechanism involving coupling of two catalyst molecules. The rate constants for both RDSs were determined for all six catalysts studied. The presence of $-$CF3 groups had inverse effects on the two steps, with the oxidation step being fastest for the unsubstituted complexes and the bimolecular step being faster for the most electron-deficient complexes. Finally, though the axial ligands studied here did not significantly affect the oxidation potentials of the catalysts, the nature of the ligand was found to be important not only in the bimolecular step but also in facilitating electron transfer from the metal center to the sacrificial oxidant.« less

  13. Manipulating the Rate-Limiting Step in Water Oxidation Catalysis by Ruthenium Bipyridine–Dicarboxylate Complexes

    SciTech Connect

    Shaffer, David W.; Xie, Yan; Szalda, David J.; Concepcion, Javier J.

    2016-11-01

    In order to gain a deeper mechanistic understanding of water oxidation by [(bda)Ru(L)2] catalysts (bdaH2 = [2,2'-bipyridine]-6,6'-dicarboxylic acid; L = pyridine-type ligand), a series of modified catalysts with one and two trifluoromethyl groups in the 4 position of the bda2– ligand was synthesized and studied using stopped-flow kinetics. The additional $-$CF3 groups increased the oxidation potentials for the catalysts and enhanced the rate of electrocatalytic water oxidation at low pH. Stopped-flow measurements of cerium(IV)-driven water oxidation at pH 1 revealed two distinct kinetic regimes depending on catalyst concentration. At relatively high catalyst concentration (ca. ≥10–4 M), the rate-determining step (RDS) was a proton-coupled oxidation of the catalyst by cerium(IV) with direct kinetic isotope effects (KIE > 1). At low catalyst concentration (ca. ≤10–6 M), the RDS was a bimolecular step with kH/kD ≈ 0.8. The results support a catalytic mechanism involving coupling of two catalyst molecules. The rate constants for both RDSs were determined for all six catalysts studied. The presence of $-$CF3 groups had inverse effects on the two steps, with the oxidation step being fastest for the unsubstituted complexes and the bimolecular step being faster for the most electron-deficient complexes. Finally, though the axial ligands studied here did not significantly affect the oxidation potentials of the catalysts, the nature of the ligand was found to be important not only in the bimolecular step but also in facilitating electron transfer from the metal center to the sacrificial oxidant.

  14. Examining the Amine Functionalization in Dicarboxylates: Photoelectron Spectroscopy and Theoretical Studies of Aspartate and Glutamate

    SciTech Connect

    Deng, Shihu; Hou, Gao-Lei; Kong, Xiangyu; Valiev, Marat; Wang, Xue B.

    2014-06-30

    Aspartate (Asp2-) and Glutamate (Glu2-), two doubly charged conjugate bases of the corresponding amino acids were investigated using low temperature negative ion photoelectron spectroscopy (NIPES) and ab-initio calculations. The effect of amine functionalization was studied by a direct comparison to the parent dicarboxylate species (-CO2–(CH2)n–CO2-, DCn2-) -- succinate (DC22-) and propionate (DC32-). Experimentally the addition of amine group for n = 2 case (DC22-, Asp2-) significantly improves the stability of the resultant Asp2- dianionic species, albeit that NIPES shows only a small increase in adiabatic electron detachment energy (ADE) (+0.05eV). In contrast, for n = 3 (DC32-, Glu2-), much larger ADE increase is observed (+0.15eV). Similar results are obtained through ab-initio calculations. The latter indicates that increased stability of Asp2- can be attributed to the lowering of the energy of singlet dianion state due to hydrogen bonding effects. The effect of the amino group on the doublet monoanion state is more complicated, and results in the weakening of the binding of the adjacent carboxylate group due to electronic structure resonance effects. This conclusion is confirmed by the analysis of NIPES results that show enhanced production of near zero kinetic energy electrons observed experimentally for amine-functionalized species.

  15. Two three-dimensional silver(I) coordination architectures with pyridine-3,5-dicarboxylate: Luminescence and structural dependence on preparing conditions

    SciTech Connect

    Xie Yabo; Gao Qian; Zhang Chaoyan; Sun Jihong

    2009-07-15

    The hydrothermal reactions of pyridine-3,5-dicarboxylic acid (H{sub 2}pydc) with AgNO{sub 3} in the mixed solvent of acetonitrile and water with different ratios lead to the formation of two three-dimensional network complexes, [Ag{sub 5}(pydc){sub 2}(CN)]{sub n} (1) and {l_brace}[Ag{sub 4}(pydc){sub 2}]CH{sub 3}CN{r_brace}{sub n} (2), which have been characterized by IR, single-crystal X-ray diffraction and thermogravimetric analyses. It has been demonstrated that the ratio of acetonitrile and water have great effect on the structures of products. The high ratio of acetonitrile and water is favorable for the formation of complex 1, while the low volume ratio is propitious to complex 2. The luminescent properties of complex 1 and 2 have been further investigated, and show that the luminescence intensity of 2 is much stronger than that of 1 probably due to the direct metal-metal interactions and a larger HOMO-LUMO gap in complex 2. - Graphical abstract: Hydrothermal reactions of pyridine-3,5-dicarboxylic acid (H{sub 2}pydc) with AgNO{sub 3} at different preparing conditions lead to the formations of two three-dimensional network complexes. The luminescent properties have also been investigated.

  16. Two three-dimensional coordination polymers of lead(II) with iminodiacetate and naphthalene-dicarboxylate anions: Synthesis, characterization and luminescence behavior

    SciTech Connect

    Hazari, Debdoot; Jana, Swapan Kumar; Fleck, Michel; Zangrando, Ennio; Dalai, Sudipta

    2014-11-15

    Two lead(II) compounds [Pb{sub 3}(idiac){sub 3}(phen){sub 2}(H{sub 2}O)]·2(H{sub 2}O) (1) and [Pb(ndc)]{sub n} (2), where H{sub 2}idiac=iminodiacetic acid, phen=1,10-phenanthroline and H{sub 2}ndc=naphthalene-2,6-dicarboxylic acid, have been synthesized and structurally characterized. Single crystal X-ray diffraction analysis showed that compound 1 is a discrete trinuclear complex (of two-fold symmetry) which evolves to a supramolecular 3D network via π–π interactions, while in compound 2 the naphthalene dicarboxylate anion act as a linker to form a three dimensional architecture, where the anion adopts a bis-(bidentate bridging) coordination mode connecting four Pb(II) centers. The photoluminescence property of the two complexes has been studied. - graphical abstract: Two new topologically different 1D coordination polymers formed by Pb{sub 4} clusters have been synthesized and characterized by x-ray analysis. The luminescence and thermal properties have been studied. - Highlights: • 1 is a trinuclear complex of Pb(II) growing to 3D network via weak interactions. • In 1, layers of (4,4) rhomboidal topology are identified. • In 2, the ndc anion adopts interesting bis-(bidentate bridging) coordination. • In 2, network is reinforced by C–H…π-ring interactions between the ndc rings.

  17. Senescence of aerial parts is impeded by exogenous gibberellic acid in herbaceous perennial Paris polyphylla.

    PubMed

    Yu, Kun; Wei, Jianrong; Ma, Qing; Yu, Dan; Li, Jiaru

    2009-05-15

    The effects of gibberellin A(3) (GA(3)) on natural senescence and the relationship between gibberellins (GAs), abscisic acid (ABA), and senescence are not fully understood. For example, it is still unclear whether GA and ABA act antagonistically. There are only few reports on senescence-related changes in physiological parameters of herbaceous perennials. This study was designed to investigate the effects of exogenous GA(3) on the senescence of aerial parts in a herbaceous perennial species, Paris polyphylla, and to test the hypothesis that GA and ABA display antagonistic effects in this process. Physiological changes associated with senescence, in particular of the hormonal and oxidative metabolisms, were also investigated. GA(3) was sprayed on mature leaves at weekly intervals, which significantly impeded senescence of aerial parts and slowed the decline of pigments and total soluble protein. Treated plants suffered less oxidative stress as revealed by reduced lipid peroxidation, a lower hydrogen peroxide level and modified activities of superoxide dismutase, peroxidase, ascorbate peroxidase, and their respective isozyme profiles. In GA(3) treated plants GA(4)+GA(7) (GAs) levels increased progressively and became significantly higher than those of control plants, whereas ABA increased in controls. When plants were treated with GA-synthesis inhibitor paclobutrazol (PCB), GAs decreased, ABA increased, and senescence was promoted. Application of a mixture of GA(3) and PCB restored the accumulation of GAs, reduced ABA, and ultimately senescence was delayed. These results suggest that GA and ABA play antagonistic roles in the senescence of aerial parts in P. polyphylla, and this process is associated with oxidative stress and regulated by endogenous hormones and extrinsic factors. Possible mechanisms that control this GA(3)-mediated inhibition of senescence are discussed.

  18. Simultaneous quantification of acylcarnitine isomers containing dicarboxylic acylcarnitines in human serum and urine by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

    PubMed

    Maeda, Yasuhiro; Ito, Tetsuya; Suzuki, Atsuko; Kurono, Yukihisa; Ueta, Akihito; Yokoi, Kyoko; Sumi, Satoshi; Togari, Hajime; Sugiyama, Naruji

    2007-01-01

    Tandem mass spectrometry (MS/MS) has become a prominent method for screening newborns for diseases such as organic acidemia and fatty acid oxidation defects, although current methods cannot separate acylcarnitine isomers. Accurate determination of dicarboxylic acylcarnitines such as methylmalonylcarnitine and glutarylcarnitine has not been carried out, because obtaining standards of these acylcarnitines is difficult. We attempted the individual determinations of acylcarnitines with isomers and dicarboxylic acylcarnitines by applying high-performance liquid chromatography (HPLC). Chromatographic separation was performed by gradient elution using a mixture of 0.08% aqueous ion-pairing agent and acetonitrile as the mobile phase. Mass transitions of m/z 161.8-->84.8 for carnitine and m/z 164.8-->84.8 for deuterated carnitine were monitored in positive ion electrospray ionization mode. One carnitine and 16 acylcarnitines were quantified. The limit of quantitation (LOQ) was 0.1 micromol/L for methylmalonylcarnitine and 0.05 micromol/L for the other acylcarnitines. Intra-day and inter-day coefficients of variance (CVs) were <8.3% and <8.8%, respectively, for all acylcarnitines in serum, and both were <9.2% in urine. Mean recoveries were >90% for all acylcarnitines. Human samples were quantified by this method. After addition of deuterated acylcarnitines as internal standards, acylcarnitines in serum or urine were extracted using a solid-phase extraction cartridge. In healthy adult individuals, isobutyryl-, 2-methylbutyryl- and isovalerylcarnitine were detected in serum and urine. Dicarboxylic acylcarnitines were detected in urine. High concentrations of methylmalonylcarnitine and propionylcarnitine were found in both the serum and the urine of a patient with methylmalonic acidemia. The described HPLC/MS/MS method could separate most acylcarnitine isomers and quantify them, potentially allowing detailed diagnoses and follow-up treatment for those diseases.

  19. Kinetic modeling of hardwood prehydrolysis. Part II. Xylan removal by dilute hydrochloric acid prehydrolysis

    SciTech Connect

    Connor, A.H.; Libkie, K.; Springer, E.L.

    1986-06-01

    A study was made of the kinetics of xylan hemicellulose removal with 0.10 M HCl at 120 degrees C from quaking aspen (Populus tremuloides), paper birch (Betula papyrifera), American elm (Ulmus americana), red maple (Acer rubrum), and southern red oak (Quercus falcata). The mathematical model developed in Part I to describe the kinetics of xylan removal by water prehydrolysis of these species could be used to model xylan removal with dilute hydrochloric acid. Xylan removal could thus be modelled as the sum of two parallel first-order reactions - one fast and one slow. However, unlike the case with water prehydrolysis where the rate constants for the fast and slow reaction processes could be correlated with each other, they could not be correlated for HCl prehydrolysis. Instead, these constant values determined for each species clustered about average values for all the species as a whole. A single set of parameters determined from a nonlinear least squares fit of the experimental prehydrolysis data for all the species as a whole to the model could be used to describe the course of xylan removal from all the species. The fact that one set of parameters could be used suggests that the same reactions are taking place on prehydrolysis and the chemical structure and physical morphology of the xylan hemicellulose were essentially the same in the species studied and probably in all temperate hardwood species. The model thus provides a good approximation of xylan removal from any temperate hardwood with dilute hydrochloric acid at the reaction conditions studied. 20 references.

  20. Lead-acid batteries in micro-hybrid applications. Part I. Selected key parameters

    NASA Astrophysics Data System (ADS)

    Schaeck, S.; Stoermer, A. O.; Kaiser, F.; Koehler, L.; Albers, J.; Kabza, H.

    Micro-hybrid electric vehicles were launched by BMW in March 2007. These are equipped with brake energy regeneration (BER) and the automatic start and stop function (ASSF) of the internal combustion engine. These functions are based on common 14 V series components and lead-acid (LA) batteries. The novelty is given by the intelligent onboard energy management, which upgrades the conventional electric system to the micro-hybrid power system (MHPS). In part I of this publication the key factors for the operation of LA batteries in the MHPS are discussed. Especially for BER one is high dynamic charge acceptance (DCA) for effective boost charging. Vehicle rest time is identified as a particular negative parameter for DCA. It can be refreshed by regular fully charging at elevated charge voltage. Thus, the batteries have to be outstandingly robust against overcharge and water loss. This can be accomplished for valve-regulated lead-acid (VRLA) batteries at least if they are mounted in the trunk. ASSF goes along with frequent high-rate loads for warm cranking. The internal resistance determines the drop of the power net voltage during cranking and is preferably low for reasons of power net stability even after years of operation. Investigations have to be done with aged 90 Ah VRLA-absorbent glass mat (AGM) batteries. Battery operation at partial state-of-charge gives a higher risk of deep discharging (overdischarging). Subsequent re-charging then is likely to lead to the formation of micro-short circuits in the absorbent glass mat separator.

  1. Reaction of β-enaminones and acetylene dicarboxylates: synthesis of substituted 1,2-dihydropyridinones.

    PubMed

    Nagaraju, Vemu; Purnachander, Dalovai; Mangina, N S V M Rao; Suresh, Surisetti; Sridhar, Balasubramanian; Karunakar, Galla V

    2015-03-14

    Synthesis of substituted 1,2-dihydropyridinones is described in a one pot reaction of β-enaminones and acetylene dicarboxylates where new C-C and C-N bonds were formed. The title compounds were obtained in moderate to good yields.

  2. Photochemical Formation of Fe(II) in the Aqueous Solutions of Fe(III)- Dicarboxylates

    NASA Astrophysics Data System (ADS)

    Okada, K.; Arakaki, T.

    2007-12-01

    Although there have been many studies reporting the photochemical formation of Fe(II) in various aqueous-phase such as rain, cloud waters, seawater and aerosols, the detailed formation mechanisms are not well understood. To better understand the mechanisms of Fe(II) formation, we attempted to determine the molar absorptivity and the quantum yield of Fe(II) photoformation for individual Fe(III)-dicarboxylate species. The concentrations of Fe(II) and total dissolved Fe were measured by a Ferrozine-HPLC method. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of chemical species in the solutions of Fe(III)-dicarboxylate complexes. The molar absorptivity and the product of the quantum yield and the molar absorptivity of Fe(III)- dicarboxylate complex can be analysed by UV-VIS spectrophotometer and photochemical experiments, and these experimental data were combined with the calculated equilibrium Fe(III) speciation to determine individual molar absorptivity and quantum yield of Fe(II) photoformation for a specific Fe(III)-dicarboxylate complex. Preliminary results, using an oxalate whose quantum yield has been previously reported, indicate that this approach gives lower quantum yield values in air saturated solutions than previously reported.

  3. Aerobic growth of campylobacter in media supplemented with C3-monocarboxylates and C4-dicarboxylates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experiments were conducted to examine aerobic growth of Campylobacter spp. in media supplemented with C4-dicarboxylates (fumarate, succinate, or malate) and C3-monocarboxylates (pyruvate or lactate). Basal broth media composed of tryptose, yeast extract, and a mineral-vitamin solution was supplement...

  4. Analysis of peroxytrifluoroacetic acid oxidation products from Victorian brown coal

    SciTech Connect

    Verheyen, T.V.; Johns, R.B.

    1983-08-01

    A method is described for the detailed quantitative structural identification of the components present in the oxidation product mixtures of a highly aliphatic brown coal. The results showed them to be predominantly long chain diols, hydroxy acids, dicarboxylic acids and short chain polycarboxylic acids.

  5. Coligand-regulated assembly, fluorescence, and magnetic properties of Co(II) and Cd(II) complexes with a non-coplanar dicarboxylate

    NASA Astrophysics Data System (ADS)

    Xin, Ling-Yun; Liu, Guang-Zhen; Ma, Lu-Fang; Wang, Li-Ya

    2013-10-01

    A non-coplanar dicarboxylate ndca (H2ndca=5-norbornene-2,3-dicarboxylic acid), combining with various dipyridyl-typed tectons, constructs six Cd(II)/Co(II) coordination polymers under hydrothermal conditions, namely [Co(ndca)(H2O)]n (1), {[Co(ndca)(bpe)(H2O)]·H2O}n (2), [Co(ndca)(bpa)0.5(H2O)]n (3), [Cd(ndca)(bpe)(H2O)]n (4), {[Cd(ndca)(bpa)(H2O)]·0.5H2O}n (5), and {[Cd(ndca)(bpp) (H2O)]·H2O}n (6) (bpe=1,2-di(4-pyridyl)ethylene, bpa=1,2-bi(4-pyridyl)ethane, and bpp=1,3-bis(4-pyridyl)propane). All these compounds contain various metal(II)-carboxylate motifs, including carboxylate binuclear (2, 4, 5), carboxylate chain (1, 6) and carboxylate layer (3), which are further extended by dipyridyl-typed coligands to afford a vast diversity of the structures with 2D pyknotic layers (1, 6), 2D open layer (5), 2D→3D interpenetrated networks (2,4), and 3D pillared-layer framework (3), respectively. In addition, fluorescent spectra of Cd(II) complexes and magnetic properties of Co(II) complexes are also given.

  6. Two Ag(I) coordination polymers derived from melamine and dicarboxylates: Syntheses, crystal structures and thermal stabilities

    NASA Astrophysics Data System (ADS)

    Li, Yun-Hua; Sun, Di; Luo, Geng-Geng; Liu, Fu-Jing; Hao, Hong-Jun; Wen, Yi-Mei; Zhao, Yang; Huang, Rong-Bin; Zheng, Lan-Sun

    2011-08-01

    Two mixed-ligand Ag(I) coordination polymers (CPs), [(NH 4)Ag 3(MA) 2(suc) 2] n ( 1), [Ag 2(MA) 2(adip)·CH 3OH·H 2O] n ( 2), (where MA = melamine, H 2suc = succinic acid, H 2adip = adipic acid) have been synthesized and structurally characterized by element analysis, IR and X-ray single-crystal diffraction. The CP 1 is a three-dimensional (3D) framework in which the MA acts as a tridentate ligand and suc 2- anion shows three types of coordination modes. Each Ag(I) ion acts as a 4-connected node to generate three- and six-membered cycles, as a result, the network can be simplified to be an overall multi-layered Kagomé topology. The CP 2 is a 2D single-layer structure constructed by tridentate MA ligands and adip 2- anions. The adjacent single-layers are inter-linked to form a double-layer 2D structure through the Ag⋯Ag interactions. Two CPs structurally vary from 2D sheet to 3D framework, which indicates that the different dicarboxylates and coordination modes of MA ligand have significant influence on the final structures. Moreover, the thermal stabilities of them were also discussed.

  7. Complexation of NpO2+ with N-methyl-iminodiacetic Acid: in Comparison with Iminodiacetic and Dipicolinic Acids

    SciTech Connect

    Tian, Guoxin; Rao, Linfeng

    2010-10-01

    Complexation of Np(V) with N-methyl-iminodiacetic acid (MIDA) in 1 M NaClO{sub 4} solution was studied with multiple techniques including potentiometry, spectrophotometry, and microcalorimetry. The 1:2 complex, NpO{sub 2}(MIDA){sub 2}{sup 3-} was identified for the first time in aqueous solution. The correlation between its optical absorption properties and symmetry was discussed, in comparison with Np(V) complexes with two structurally related nitrilo-dicarboxylic acids, iminodiacetic acid (IDA) and dipicolinic acid (DPA). The order of the binding strength (DPA > MIDA > IDA) is explained by the difference in the structural and electronic properties of the ligands. In general, the nitrilo-dicarboxylates form stronger complexes with Np(V) than oxy-dicarboxylates due to a much more favorable enthalpy of complexation.

  8. Amino and fatty acids in carbonaceous meteorites

    NASA Technical Reports Server (NTRS)

    Kvenvolden, K. A.

    1974-01-01

    Analyses of two carbonaceous meteorites have provided much of the latest evidence which seems to support Oparin's theory on the origin of life. The meteorites involved are the Murray meteorite, which fell in 1950, and the Murchison meteorite, which fell in 1969. The amino acids in the two meteorites are similar in composition. Eight of the twenty amino acids found belong to amino acids present in proteins. A number of monocarboxylic and dicarboxylic fatty acids were also found in the meteorites.

  9. Mechanism of hydrodenitrogenation (Part 4) infrared spectroscopy of acidic molybdena catalysts

    SciTech Connect

    Miranda, R.

    1990-01-01

    Mo oxide catalysts supported over a complete series of silica-aluminas have been characterized in the oxidic and reduced states, by means of total acidity measurements and by infrared spectroscopy. Ammonia chemisorption was used to titrate the total acidity of the catalysts, and IR absorption of adsorbed pyridine to distinguish Bronsted from Lewis acid sites. The formation of new acidity upon deposition of molybdena on silica-alumina supports was then explained on the basis of a simple surface model. The new acidity is of both Lewis and Bronsted type, the preponderance of one over the other depending on support composition, as well as loading and state of oxidation of Mo. High-alumina supports and low Mo loading favor dispersed Mo species, in particular bidentate and monodentate di-oxo Mo species. The latter is responsible for the new Bronsted acidity. Coordinative unsaturation of polymolybdates is responsible for the new Lewis acidity, which is increased upon reduction of Mo. High-silica supports favor monodentate species (high Bronsted acidity) up to 4 wt % MoO{sub 3}. Beyond that, polymolybdates species and Lewis acidity predominate. 7 refs., 4 figs.

  10. Mechanism of carboxylic acid photooxidation in atmospheric aqueous phase: Formation, fate and reactivity

    NASA Astrophysics Data System (ADS)

    Charbouillot, Tiffany; Gorini, Sophie; Voyard, Guillaume; Parazols, Marius; Brigante, Marcello; Deguillaume, Laurent; Delort, Anne-Marie; Mailhot, Gilles

    2012-09-01

    In the first part of the work, we investigated the reactivity toward photogenerated hydroxyl radicals (rad OH) of seven monocarboxylic acids and six dicarboxylic acids found in natural cloud water. This leads to the proposition of a schematic degradation pathway linking glutaric acid (C5) to complete mineralization into CO2. We report a detailed mechanism on the succinic acid reactivity toward rad OH leading to the formation of malonic, glyoxylic and consequently oxalic acids and a comparison with reported pathways proposed by the CAPRAM (Chemical Aqueous Phase RAdical Mechanism) is discussed. We also investigated the photooxidation of formic acid under atmospherically relevant conditions leading to the possible formation of oxalic acid via radical mediated recombination. The second part focuses on the polychromatic irradiation (closed to solar irradiation) of a collected cloud aqueous phase showing that irradiation of cloud water leads to the formation of both formic and acetic acids. Carboxylic acid formation increases in the presence of photogenerated hydroxyl radicals from hydrogen peroxide, showing that photooxidation could play a key role in the formation of carboxylic acids under atmospherically relevant conditions.

  11. Putrescine production via the ornithine decarboxylation pathway improves the acid stress survival of Lactobacillus brevis and is part of a horizontally transferred acid resistance locus.

    PubMed

    Romano, Andrea; Ladero, Victor; Alvarez, Miguel A; Lucas, Patrick M

    2014-04-03

    Decarboxylation pathways are widespread among lactic acid bacteria; their physiological role is related to acid resistance through the regulation of the intracellular pH and to the production of metabolic energy via the generation of a proton motive force and its conversion into ATP. These pathways include, among others, biogenic amine (BA) production pathways. BA accumulation in foodstuffs is a health risk; thus, the study of the factors involved in their production is of major concern. The analysis of several lactic acid bacterial strains isolated from different environments, including fermented foods and beverages, revealed that the genes encoding these pathways are clustered on the chromosome, which suggests that these genes are part of a genetic hotspot related to acid stress resistance. Further attention was devoted to the ornithine decarboxylase pathway, which affords putrescine from ornithine. Studies were performed on three lactic acid bacteria belonging to different species. The ODC pathway was always shown to be involved in cytosolic pH alkalinisation and acid shock survival, which were observed to occur with a concomitant increase in putrescine production.

  12. Poly[piperazinediium [[aqua­bismuth­ate(III)]-di-μ-pyridine-2,6-dicarboxyl­ato-bis­muthate(III)-di-μ-pyridine-2,6-dicarboxyl­ato] monohydrate

    PubMed Central

    Aghabozorg, Hossein; Nemati, Andya; Derikvand, Zohreh; Ghadermazi, Mohammad

    2008-01-01

    The title compound, {(C4H12N2)[Bi2(C7H3NO4)4(H2O)]·H2O}n or {(pipzH2)[Bi2(pydc)4(H2O)]·H2O}n, where pydcH2 is pyridine-2,6-dicarboxylic acid and pipz is piperazine, was obtained by reaction of Bi(NO3)3·5H2O with (pipzH2)(pydc­H)2·3H2O in a 1:2 molar ratio in aqueous solution. There are two independent BiIII atoms in the structure, one of which is eight-coordinate with a distorted bicapped trigonal-prismatic geometry, and another which is nine-coordinate with a distorted tricapped trigonal-prismatic geometry. The carboxyl­ate groups of the (pydc)2− ligands link dinuclear [Bi2(C7H3NO4)4(H2O)]2− units into one-dimensional coordin­ation polymers. The pipzH2 2+ cations (site symmetry ) and non-coordinated water mol­ecules lie between these polymers, forming N—H⋯O and O—H⋯O hydrogen bonds to the O atoms of the carboxylate groups. PMID:21201329

  13. Tetracene dicarboxylic imide and its disulfide: synthesis of ambipolar organic semiconductors for organic photovoltaic cells.

    PubMed

    Okamoto, Toshihiro; Suzuki, Tsuyoshi; Tanaka, Hideyuki; Hashizume, Daisuke; Matsuo, Yutaka

    2012-01-02

    We have designed and synthesized a new donor/acceptor-type tetracene derivative by the introduction of dicarboxylic imide and disulfide groups as electron-withdrawing and -donating units, respectively. The prepared compounds, tetracene dicarboxylic imide (TI) and its disulfide (TIDS) have high chemical and electrochemical stability as well as long-wavelength absorptions of up to 886 nm in the thin films. The crystal packing structure of TIDS molecules features face-to-face π-stacking, derived from dipole-dipole interactions. Notably, TIDS exhibited ambipolar properties of both electron-donating and -accepting natures in p-n and p-i-n heterojunction organic thin-film photovoltaic devices. Accordingly, TI and TIDS are expected to be promising compounds for designing new organic semiconductors.

  14. Characterisation of calamansi (Citrus microcarpa). Part I: volatiles, aromatic profiles and phenolic acids in the peel.

    PubMed

    Cheong, Mun Wai; Chong, Zhi Soon; Liu, Shao Quan; Zhou, Weibiao; Curran, Philip; Bin Yu

    2012-09-15

    Volatile compounds in the peel of calamansi (Citrus microcarpa) from Malaysia, the Philippines and Vietnam were extracted with dichloromethane and hexane, and then analysed by gas chromatography-mass spectroscopy/flame ionisation detector. Seventy-nine compounds representing >98% of the volatiles were identified. Across the three geographical sources, a relatively small proportion of potent oxygenated compounds was significantly different, exemplified by the highest amount of methyl N-methylanthranilate in Malaysian calamansi peel. Principal component analysis and canonical discriminant analysis were applied to interpret the complex volatile compounds in the calamansi peel extracts, and to verify the discrimination among the different origins. In addition, four common hydroxycinnamic acids (caffeic, p-coumaric, ferulic and sinapic acids) were determined in the methanolic extracts of calamansi peel using ultra-fast liquid chromatography coupled to photodiode array detector. The Philippines calamansi peel contained the highest amount of total phenolic acids. In addition, p-Coumaric acid was the dominant free phenolic acids, whereas ferulic acid was the main bound phenolic acid.

  15. Function and Regulation of the C4-Dicarboxylate Transporters in Campylobacter jejuni

    PubMed Central

    Wösten, Marc M. S. M.; van de Lest, Chris H. A.; van Dijk, Linda; van Putten, Jos P. M.

    2017-01-01

    C4-dicarboxylates are important molecules for the human pathogen C.jejuni, as they are used as carbon and electron acceptor molecules, as sugars cannot be utilized by this microaerophilic organism. Based on the genome analysis, C. jejuni may possess five different C4–dicarboxylate transporters: DctA, DcuA, DcuB, and two homologs of DcuC. Here, we investigated the regulation and function of various C4–dicarboxylate transporters in C. jejuni. Transcription of the dctA and dcuC homologs is constitutive, while dcuA and dcuB are both directly regulated by the two-component RacR/RacS system in response to limited oxygen availability and the presence of nitrate. The DctA transporter is the only C4-dicarboxylate transporter to allow C. jejuni to grow on C4-carbon sources such as aspartate, fumarate, and succinate at high oxygen levels (10% O2) and is indispensable for the uptake of succinate from the medium under these conditions. Both DcuA and DcuB can sequester aspartate from the medium under low-oxygen conditions (0.3% O2). However, under these conditions, DcuB is the only transporter to secrete succinate to the environment. Under low-oxygen conditions, nitrate prevents the secretion of succinate to the environment and was able to overrule the phenotype of the C4-transporter mutants, indicating that the activity of the aspartate–fumarate–succinate pathway in C. jejuni is strongly reduced by the addition of nitrate in the medium. PMID:28223978

  16. C4-dicarboxylates sensing mechanism revealed by the crystal structures of DctB sensor domain.

    PubMed

    Zhou, Yan-Feng; Nan, Beiyan; Nan, Jie; Ma, Qingjun; Panjikar, Santosh; Liang, Yu-He; Wang, Yiping; Su, Xiao-Dong

    2008-10-31

    C(4)-dicarboxylates are the major carbon and energy sources during the symbiotic growth of rhizobia. Responses to C(4)-dicarboxylates depend on typical two-component systems (TCS) consisting of a transmembrane sensor histidine kinase and a cytoplasmic response regulator. The DctB-DctD system is the first identified TCS for C(4)-dicarboxylates sensing. Direct ligand binding to the sensor domain of DctB is believed to be the first step of the sensing events. In this report, the water-soluble periplasmic sensor domain of Sinorhizobium meliloti DctB (DctBp) was studied, and three crystal structures were solved: the apo protein, a complex with C(4) succinate, and a complex with C(3) malonate. Different from the two structurally known CitA family of carboxylate sensor proteins CitA and DcuS, the structure of DctBp consists of two tandem Per-Arnt-Sim (PAS) domains and one N-terminal helical region. Only the membrane-distal PAS domain was found to bind the ligands, whereas the proximal PAS domain was empty. Comparison of DctB, CitA, and DcuS suggests a detailed stereochemistry of C(4)-dicarboxylates ligand perception. The structures of the different ligand binding states of DctBp also revealed a series of conformational changes initiated upon ligand binding and propagated to the N-terminal domain responsible for dimerization, providing insights into understanding the detailed mechanism of the signal transduction of TCS histidine kinases.

  17. Diacridinium trans-diaqua­bis(pyrazine-2,3-dicarboxyl­ato)cobaltate(II) hexa­hydrate

    PubMed Central

    Aghabozorg, Hossein; Attar Gharamaleki, Jafar; Parvizi, Mahdieh; Derikvand, Zohreh

    2010-01-01

    The title compound, (C13H10N)2[Co(C6H2N2O4)2(H2O)2]·6H2O, consists of mononuclear trans-[Co(pz-2,3-dc)2(H2O)2]2− complex anions, (acrH)+ cations and uncoordinated water mol­ecules (acr is acridine and pz-2,3-dcH2 is pyrazine-2,3-dicarboxylic acid). The CoII atom, which lies on a crystallographic center of symmetry, has a slightly distorted octa­hedral coordination environment, with two N and two O atoms from the (pz-2,3-dc)2− ligands in the equatorial plane and with two water mol­ecules in axial positions. In the crystal, the components are held together by two distinct N—H⋯O and C—H⋯O hydrogen bonds with R 2 2(8) graph-sets. The coordinated and uncoordinated water mol­ecules are also involved in O—H⋯O hydrogen bonds, which lead to the formation of layers with R 3 3(12) graph-set motifs. Extensive π–π stacking inter­actions between parallel aromatic rings of the acridinium ions, with distances ranging from 3.533 (1) to 3.613 (1) Å, occur in the structure. PMID:21579976

  18. Structure modulation of manganese coordination polymers consisting of 1,4-naphthalene dicarboxylate and 1,10-phenanthroline.

    PubMed

    Lou, Yongbing; Wang, Jingjing; Tao, Yinhua; Chen, Jinxi; Mishima, Akio; Ohba, Masaaki

    2014-06-14

    Three new manganese coordination polymers, {[Mn2(1,4-NDC)2(phen)2](H2O)}n (1), [Mn2(1,4-NDC)2(phen)(H2O)]n (2) and {[Mn4(1,4-NDC)4(phen)4](DMF)2}n (3) (1,4-H2NDC = 1,4-naphthalene dicarboxylic acid; phen = 1,10-phenanthroline; DMF = N,N-dimethylformamide), have been synthesized solvo/hydrothermally. 1,4-NDC(2-) ligands adopt different coordination modes under different solvents and concentrations which promotes different crystal structure formation. X-ray crystal structural data reveal that compounds 1, 2 and 3 crystallize in monoclinic space groups C2/c, P21/c and C2/c, respectively. Compound 1 has Mn2 dimers connected by 1,4-NDC(2-) linkers, packing into a 2D structure in a grid pattern. Compound 2 has a three-dimensional (3D) structure which is constructed by Mn2 dimers and 1,4-NDC(2-) linkers. Each MnO4N2 node of compound 3 is linked to another by 1,4-NDC(2-) ligands to form a two-dimensional (2D) structure. Variable-temperature magnetic susceptibilities of compounds 1-3 exhibit overall weak antiferromagnetic coupling between the adjacent Mn(II) ions.

  19. A series of novel 1D coordination polymers constructed from metal?quinolone complex fragments linked by aromatic dicarboxylate ligands

    NASA Astrophysics Data System (ADS)

    He, Jiang-Hong; Xiao, Dong-Rong; Yan, Shi-Wei; Sun, Dian-Zhen; Chen, Hai-Yan; Wang, Xin; Yang, Juan; Ye, Zhong-Li; Yuan, Ruo; Wang, En-Bo

    2012-08-01

    Self-assembly of quinolones with metal salts in the presence of aromatic dicarboxylate ligands affords a series of novel 1D metal-quinolone complexes, namely [Mn(Hppa)(oba)]·3H2O (1), [Co(Hppa)(oba)]·3.25H2O (2), [Zn(Hppa)(sdba)]·1.5H2O (3), [Mn(Hcf)(bpda)(H2O)]·2H2O (4), [Mn(Hppa)2(bpdc)] (5) and [Mn(Hlome)2(bpdc)]·4H2O (6) (Hppa = Pipemidic acid, Hcf = ciprofloxacin, Hlome = lomefloxacin). The structures of compounds 1-3 consist of novel polymeric chains spanning two different directions, which display an intriguing 1D → 3D inclined polycatenation of supramolecular ladders. Compound 4 exhibits a chain compound formed from the interconnection of [Mn2(Hcf)2(μ-CO2)2] dimers with bpda ligands. Compounds 5 and 6 are similar chain compounds constructed from [Mn(Hppa)2] (or [Mn(Hlome)2]) fragments linked by bpdc ligands. The magnetic properties of 4 have been studied, which indicate the existence of antiferromagnetic interactions. Furthermore, the luminescent properties of compound 3 are discussed.

  20. Specificity and regulation of the dicarboxylate carrier on the peribacteroid membrane of soybean nodules.

    PubMed

    Ou Yang, L J; Udvardi, M K; Day, D A

    1990-10-01

    Malate and succinate were taken up rapidly by isolated, intact peribacteroid units (PBUs) from soybean (Glycine max (L.) Merr.) root nodules and inhibited each other in a competitive manner. Malonate uptake was slower and was severely inhibited by equimolar malate in the reaction medium. The apparent Km for malonate uptake was higher than that for malate and succinate uptake. Malate uptake by PBUs was inhibited by (in diminishing order of severity) oxaloacetate, fumarate, succinate, phthalonate and oxoglutarate. Malonate and butylmalonate inhibited only slightly and pyruvate,isocitrate and glutamate not at all. Of these compounds, only oxaloacetate, fumarate and succinate inhibited malate uptake by free bacteroids. Malate uptake by PBUs was inhibited severely by the uncoupler carbonylcyanidem-chlorophenyl hydrazone and the respiratory poison KCN, and was stimulated by ATP. We conclude that the peribacteroid membrane contains a dicarboxylate transport system which is distinct from that on the bacteroid membrane and other plant membranes. This system can catalyse the rapid uptake of a range of dicarboxylates into PBUs, with malate and succinate preferred substrates, and is likely to play an important role in symbiotic nitrogen fixation. Energization of both the bacteroid and peribacteroid membranes controls the rate of dicarboxylate transport into peribacteroid units.

  1. In situ hydrothermal syntheses, structures and photoluminescent properties of four novel metal-organic frameworks constructed by lanthanide (Ln=Ce(III), Pr(III), Eu(III)) and Cu(I) metals with flexible dicarboxylate acids and piperazine-based ligands

    SciTech Connect

    Ay, Burak; Karaca, Serkan; Yildiz, Emel; Lopez, Valerie; Nanao, Max H.; Zubieta, Jon

    2016-01-15

    Four novel metal-organic frameworks,[Cu{sub 2}Cl{sub 2}(pyrz)]{sub n} (1) and (H{sub 2}pip){sub n}[Ln{sub 2}(pydc){sub 4}(H{sub 2}O){sub 2}]{sub n} (Ln=Ce (2), Pr (3) and Eu (4), H{sub 2}pzdc=2,3-pyrazinedicarboxylic acid, pyrz=pyrazine, H{sub 2}pydc=2,6-pyridinedicarboxylic acid, H{sub 2}pip=piperazine) have been synthesized under hydrothermal conditions and characterized by the elemental analysis, ICP, Far IR (FIR), FT-IR spectra, TGA, single crystal X-ray diffraction analysis and powder X-ray diffraction (PXRD). Compound 1 is two-dimensional containing Cl-Cu-Cl sites, while the lanthanide complexes contain one-dimensional infinite Ln–O-Ln chains. All the complexes show high thermal stability. The complexes 1–3 exhibit luminescence emission bands at 584, 598 and 614 nm at room temperature when excited at 300 nm. Complex 4 exhibits bright red solid-state phosphorescence upon exposure to UV radiation at room temperature. - Graphical abstract: Four novel metal-organic frameworks have been synthesized under hydrothermal conditions. Thermal and luminescent properties of the compounds have been investigated.

  2. In situ hydrothermal syntheses, structures and photoluminescent properties of four novel metal-organic frameworks constructed by lanthanide (Ln=Ce(III), Pr(III), Eu(III)) and Cu(I) metals with flexible dicarboxylate acids and piperazine-based ligands

    NASA Astrophysics Data System (ADS)

    Ay, Burak; Karaca, Serkan; Yildiz, Emel; Lopez, Valerie; Nanao, Max H.; Zubieta, Jon

    2016-01-01

    Four novel metal-organic frameworks,[Cu2Cl2(pyrz)]n (1) and (H2pip)n[Ln2(pydc)4(H2O)2]n (Ln=Ce (2), Pr (3) and Eu (4), H2pzdc=2,3-pyrazinedicarboxylic acid, pyrz=pyrazine, H2pydc=2,6-pyridinedicarboxylic acid, H2pip=piperazine) have been synthesized under hydrothermal conditions and characterized by the elemental analysis, ICP, Far IR (FIR), FT-IR spectra, TGA, single crystal X-ray diffraction analysis and powder X-ray diffraction (PXRD). Compound 1 is two-dimensional containing Cl-Cu-Cl sites, while the lanthanide complexes contain one-dimensional infinite Ln-O-Ln chains. All the complexes show high thermal stability. The complexes 1-3 exhibit luminescence emission bands at 584, 598 and 614 nm at room temperature when excited at 300 nm. Complex 4 exhibits bright red solid-state phosphorescence upon exposure to UV radiation at room temperature.

  3. Haloacetic acids in the aquatic environment. Part II: ecological risk assessment.

    PubMed

    Hanson, Mark L; Solomon, Keith R

    2004-08-01

    Haloacetic acids (HAAs) are environmental contaminants found in aquatic ecosystems throughout the world as a result of both anthropogenic and natural production. The ecological risk posed by these compounds to organisms in freshwater environments, with a specific focus on aquatic macrophytes, was characterized. The plants evaluated were Lemna gibba, Myriophyllum spicatum and M. sibiricum and the HAAs screened were monochloroacetic acid (MCA), dichloroacetic acid (DCA), trichloroacetic acid (TCA), trifluoroacetic acid (TFA) and chlorodifluoroacetic acid (CDFA). Laboratory toxicity data formed the basis of the risk assessment, but field studies were also utilized. The estimated risk was calculated using hazard quotients (HQ), as well as effect measure distributions (EMD) in a modified probabilistic ecological risk assessment. EMDs were used to estimate HAA thresholds of toxicity for use in HQ assessments. This threshold was found to be a more sensitive measure of low toxicity than the no observed effect concentrations (NOEC) or the effective concentration (EC10). Using both deterministic and probabilistic methods, it was found that HAAs do not pose a significant risk to freshwater macrophytes at current environmental concentrations in Canada, Europe or Africa for both single compound and mixture exposures. Still, HAAs are generally found as mixtures and their potential interactions are not fully understood, rendering this phase of the assessment uncertain and justifying further effects characterization. TCA in some environments poses a slight risk to phytoplankton and future concentrations of TFA and CDFA are likely to increase due to their recalcitrant nature, warranting continued environmental surveillance of HAAs.

  4. Silver-catalyzed protodecarboxylation of heteroaromatic carboxylic acids.

    PubMed

    Lu, Pengfei; Sanchez, Carolina; Cornella, Josep; Larrosa, Igor

    2009-12-17

    A simple and highly efficient protodecarboxylation procedure for a variety of heteroaromatic carboxylic acids catalyzed by Ag(2)CO(3) and AcOH in DMSO is described. This methodology can also perform the selective monoprotodecarboxylation of several aromatic dicarboxylic acids.

  5. Production of itaconic acid from pentose sugars by Aspergillus terreus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Itaconic acid (IA), an unsaturated 5-carbon dicarboxylic acid, is a building block platform chemical that is currently produced industrially with glucose by fermentation with Aspergillus terreus (A. terreus). However, lignocellulosic biomass has the potential to serve as a low cost source of sugars ...

  6. Molar Absorptivity and Concentration-Dependent Quantum Yield of Fe(II) Photo-Formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Complexes

    NASA Astrophysics Data System (ADS)

    Hitomi, Y.; Arakaki, T.

    2009-12-01

    Redox cycles of iron in the aquatic environment affect formation of reactive oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be important sources of photo-formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. We initiated a study to characterize Fe(II) photo-formation from Fe(III)-dicarboxylates with the concentration ranges that are relevant to the natural aquatic environment. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species. The molar absorptivity of Fe(III)-dicarboxylate species was obtained by UV-VIS spectrophotometer, and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained from photochemical experiments. These experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. We used initial concentrations of less than 10 micromolar Fe(III) to study the photochemical formation of Fe(II). Dicarboxylate compounds studied include oxalate, malonate, succinate, malate, and phthalate. We report molar absorptivity and concentration-dependent quantum yields of Fe(II) photo-formation of individual Fe(III)-dicarboxylates.

  7. Tailored design of ruthenium molecular catalysts with 2,2'-bypyridine-6,6'-dicarboxylate and pyrazole based ligands for water oxidation.

    PubMed

    Daniel, Quentin; Wang, Lei; Duan, Lele; Li, Fusheng; Sun, Licheng

    2016-10-07

    With the incorporation of pyrazole and DMSO as axial ligands, a series of tailor-designed Ru water oxidation catalysts [Ru(bda)(DMSO)(L)] (H2bda = 2,2'-bypyridine-6,6'-dicarboxylic acid; DMSO = dimethyl sulfoxide; L = pyrazole, A-1; 4-Br-3-methyl pyrazole, B-1) and [Ru(bda)(L)2] (L = pyrazole, A-2; 4-Br-3-methyl pyrazole, B-2) have been generated in situ from their corresponding precursors [Ru(κ3(O,N,N)-bda)(DMSO)x(L)3-x] which are in a zwitterionic form with an extra pyrazole based ligand in the equatorial position. Formation of the active catalyst has been investigated under pH 1.0 conditions. Electrochemistry and water oxidation activity of these catalysts were investigated. By fine tuning of the catalyst structure, the turnover frequency was increased up to 500 s(-1) and the stability over 6000 turnovers.

  8. Studies on antioxidant activity, volatile compound and fatty acid composition of different parts of Glycyrrhiza echinata L.

    PubMed Central

    Çakmak, Yavuz Selim; Aktumsek, Abdurrahman; Duran, Ahmet

    2012-01-01

    The essential oil compound, fatty acid composition and the in vitro antioxidant activity of the root and aerial of Glycyrrhiza echinata L., a medicinal plant growing in Turkey, have been studied. The antioxidant capacity tests were designed to evaluate the antioxidant activities of methanol extracts. Total phenolic and flavonoid concentrations of each extract were also determined by using both Folin-Ciocalteu reagent and aluminum chloride. The aerial part was found to possess the highest total phenolic content (146.30 ± 4.58 mg GAE/g) and total antioxidant capacity (175.33 ± 3.98 mg AE/g). The essential oil from root and aerial parts was analyzed by gas chromatography mass spectroscopy (GC-MS) systems. The major components identified were n-hexadecanoic acid, hexahydro farnesyl acetone, α-caryophyllen, hexanal and phytol. In fatty acid profiles of plant, palmitic, stearic, oleic and linoleic acid were detected as the main components. The results of this study have shown that the extracts G. echinata are suitable as a natural antioxidant and food supplement source for pharmacological and food industries due to their beneficial chemical composition and antioxidant capacity. PMID:27418901

  9. Characterization of microcrystalline cellulose prepared from lignocellulosic materials. Part I. Acid catalyzed hydrolysis.

    PubMed

    Adel, Abeer M; Abd El-Wahab, Zeinab H; Ibrahim, Atef A; Al-Shemy, Mona T

    2010-06-01

    Rice hulls (RH) and bean hulls (BH) were subjected to prehydrolysis treatments, to define the optimum conditions for producing a high percentage of hydrolyzed hemicellulose with a small or moderate degradation of the cellulosic portion. The hydrolysis experiments were performed using hydrochloric and sulfuric acids in concentrations ranging from (0.5 to 5)% (w/w) at 120 degrees C for 90 min and 10% consistency. The effects of different temperatures (80 to 120 degrees C) and time (30 to 120 min) on acid hydrolysis of lignocellulosic materials were recorded. It was found that, the optimum condition to hydrolyze the lignocellulosic materials (RH) and (BH) are 2% (w/w) of mineral acid at 120 degrees C for 90 min and 10% consistency. The cellulose crystallinity index in the different types of lignocellulosic materials with and without acid treatment, were increased from 0.32 to 0.46 in case of RH and from 0.43 to 0.61 in case of BH. Due to the lignin depolymerization during the pretreatment process, the relative absorbency of the methoxyl group and the aromatic rings bands were lowered for the pretreated than the untreated lignocellulosic materials. Also, the band at 1730 cm(-1) which is attributed to carbonyl groups of uronic acids was lowered due the hemicellulose hydrolysis.

  10. Chemical composition and antibacterial properties of essential oil and fatty acids of different parts of Ligularia persica Boiss

    PubMed Central

    Mohadjerani, Maryam; Hosseinzadeh, Rahman; Hosseini, Maryam

    2016-01-01

    Objective: The objective of this research was to investigate the chemical composition and antibacterial activities of the fatty acids and essential oil from various parts of Ligularia persica Boiss (L. persica) growing wild in north of Iran. Materials and Methods: Essential oils were extracted by using Clevenger-type apparatus. Antibacterial activity was tested on two Gram-positive and two Gram-negative bacteria by using micro dilution method. Results: GC and GC∕MS analysis of the oils resulted in detection of 94%, 96%, 93%, 99% of the total essential oil of flowers, stems, roots and leaves, respectively. The main components of flowers oil were cis-ocimene (15.4%), β-myrcene (4.4%), β-ocimene (3.9%), and γ-terpinene (5.0%). The major constituents of stems oil were β-phellandrene (5.4%), β-cymene (7.0%), valencene (3.9%). The main compounds of root oil were fukinanolid (17.0%), α-phellandrene (11.5%) and Β-selinene (5.0%) and in the case of leaves oil were cis-ocimene (4.8%), β-ocimene (4.9%), and linolenic acid methyl ester (4.7%). An analysis by GC-FID and GC-MS on the fatty-acid composition of the different parts of L. persica showed that major components were linoleic acid (11.3-31.6%), linolenic acid (4.7-21.8%) and palmitic acid (7.2-23.2%). Saturated fatty acids were found in lower amounts than unsaturated ones. The least minimum inhibition concentration (MIC) of the L. persica was 7.16 μg/ml against Pseudomonas aeruginosa. Conclusion: Our study indicated that the essential oil from L. persica stems and flowers showed high inhibitory effect on the Gram negative bacteria. The results also showed that fatty acids from the stems and leaves contained a high amount of poly-unsaturated fatty acids (PUFAs). PMID:27462560

  11. An Investigation of the Acid Rock Drainage Generation from the Road Cut Slope in the Middle Part of South Korea

    NASA Astrophysics Data System (ADS)

    Ji, S.; Cheong, Y.; Yim, G.

    2006-05-01

    To examine the Acid Rock Drainage (ARD) generation from the road cut slope, a prediction study including Acid-Base Accounting (ABA) test and Net Acid Generation (NAG) test was performed for road cut rock samples (20 samples) at the new construction site of a highway in the middle part of South Korea. This slope is composed of slate and phyllite. It was a pit wall which was operated as a quarry which produced materials for roofing. pH1:2 and EC1:2 measurements were performed to evaluate free hydrogen ion contents and salts in samples. ABA test was performed to estimate the balance of the acid generating minerals (mainly pyrite) and the acid neutralizing minerals (mainly carbonates) in rock samples. Total sulfur was analyzed by sulfur analyzer, and then the maximum potential acidity (MPA, kg H2SO4/t) was calculated. X-ray diffraction (XRD) analysis was performed to identify the mineral composition of rock samples. Acid neutralizing capacity (ANC) test, after the Sobek et al. (1978), was performed to estimate the amount of acid originated from the oxidation of sulfide minerals. NAPP (Net Acid Producing Potential) was calculated by total sulfur (MPA) and ANC. NAG test was performed with grounded samples and 15 % hydrogen peroxide, and then NAG was analyzed by measuring pH (NAGpH) of the mixed solution. pH1:2 and EC1:2 ranged from 2.95 to 7.23 and 17.1 to 3070.0 ¥ìS/cm, respectively. MPA of samples was ranged from 0.0 to 79.9 kg H2SO4/t. From the XRD analysis pyrite was found at the most samples. In the sample from highly weathered dike, goethite was found. Results of the ANC tests indicated that the value of ANC reached up to 59.36 kg H2SO4/t. Rock samples could be classified as Potential Acid Forming rock (PAF) and Non- Acid Forming rock (NAF) by plotting NAPP versus NAGpH. In this study 17 samples were classified as PAF rock. It means that this slope would generate ARD when they reacted with rain. Two samples were grouped as NAF. By application this ARD prediction

  12. Carboxylic acid accelerated formation of diesters

    DOEpatents

    Tustin, Gerald Charles; Dickson, Todd Jay

    1998-01-01

    This invention pertains to accelerating the rate of formation of 1,1-dicarboxylic esters from the reaction of an aldehyde with a carboxylic acid anhydride or a ketene in the presence of a non-iodide containing a strong Bronsted acid catalyst by the addition of a carboxylic acid at about one bar pressure and between about 0.degree. and 80.degree. C. in the substantial absence of a hydrogenation or carbonylation catalyst.

  13. Heat-induced formation of mepiquat by decarboxylation of pipecolic acid and its betaine derivative. Part 1: Model system studies.

    PubMed

    Yuan, Yuan; Tarres, Adrienne; Bessaire, Thomas; Stadler, Richard H; Delatour, Thierry

    2017-07-15

    This study describes, for the first time, the role of pipecolic acid betaine and pipecolic acid, naturally present in some foods, in the formation of the plant growth regulator N,N-dimethylpiperidinium (mepiquat) under dry thermal conditions. The formation of mepiquat and intermediate compounds was investigated in model systems using high performance liquid chromatography-quadrupole/time-of-flight mass spectrometry. Mepiquat is released with a yield of up to 0.66mol% after thermal treatment (>150°C) of pipecolic acid betaine. Similar conversion rates are attained with the congener piperidine-2-carboxylic acid (dl-pipecolic acid), albeit in the presence of alkylating agents, such as choline, glycine betaine or trigonelline, that are fairly widespread in food crops. These new pathways to mepiquat indicate that the occurrence of low levels of this thermally induced compound is probably more widespread in processed foods than initially suspected (see Part 2 of this study on the occurrence of mepiquat in selected foodstuffs).

  14. Metabolic engineering of Rhizopus oryzae: Effects of overexpressing pyc and pepc genes on fumaric acid biosynthesis from glucose

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumaric acid, a dicarboxylic acid used as a food acidulant and in manufacturing synthetic resins, can be produced from glucose in fermentation by Rhizopus oryzae. However, the fumaric acid yield is limited by the co-production of ethanol and other byproducts. To increase fumaric acid production, ove...

  15. Fatty acid facts, Part III: Cardiovascular disease, or, a fish diet is not fishy.

    PubMed

    Pauwels, Ernest K J; Kostkiewicz, Magdalena

    2008-12-01

    Preclinical and clinical studies have demonstrated that omega-3 polyunsaturated fatty acids (n-3 PUFAs) play a significant role in the prevention of cardiovascular disease. These fatty acids are called essential fatty acids as they fulfil essential functions and the mammalian cell cannot synthesize them de novo. Dietary sources of n-3 PUFAs include fish oils rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The clinical relevance of these molecules is derived from the incorporation of EPA and DHA into cell membranes. The presence of EPA/DHA alters the physical characteristics of the membrane. Both these altered physicochemical membrane properties and the presence of n-3 PUFAs released by the action of phospholipid lipases (resulting in antiinflammatory eicosanoids) improve biological functions such as signal transduction, ion channelling and ligand binding to nuclear receptors. EPA/DHA also reduce or quench gene expression of cyclooxygenase-2 and other enzymes, thereby diminishing the formation of proinflammatory molecules. Increased EPA/DHA concentration also gives rise to antiinflammatory lipid mediators, called lipoxins, resolvins and protectins. Another important function of n-3 PUFAs is scavenging of free radicals, which diminishes inflammatory response and oxidation of lipoprotein particles, notably low density lipoproteins. The interplay of these molecular processes has distinct cardioprotective effects, which involve actions on lipid metabolism, lipoprotein particle size, blood pressure, vascular function, coagulation potential, inflammatory response, atheroma formation and antiarrhythmic. In view of these actions, fish oil preparations and/or intake of oily fish are recommended as primary and secondary prevention of cardiovascular disease and sudden cardiac death. Large, ongoing trials will further elucidate the presumed favorable effects of EPA/DHA in heart failure and diabetes. This review provides a summary of the physiological

  16. Emerging biotechnologies for production of itaconic acid and its applications as a platform chemical

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recently, itaconic acid (IA), an unsaturated C5-dicarboxylic acid, has attracted much attention as a biobased building block chemical. It is produced industrially (> 80 g L**-1) from glucose by fermentation with Aspergillus terreus. The titer is low compared with citric acid production (> 200 g L**-...

  17. Hydrometallurgical process for zinc recovery from electric arc furnace dust (EAFD): part I: Characterization and leaching by diluted sulphuric acid.

    PubMed

    Oustadakis, P; Tsakiridis, P E; Katsiapi, A; Agatzini-Leonardou, S

    2010-07-15

    The present paper is the first of a series of two articles dealing with the development of an integrated process for the recovery of zinc from electric arc furnace dust (EAFD), a hazardous industrial waste generated in the collection of particulate material during steelmaking process via electric arc furnace. Part I presents the EAFD characterization and its leaching process by diluted sulphuric acid, whereas Part II deals with the purification of the leach liquor and the recovery of zinc by solvent extraction/electrowinning. The characterization of the examined electric arc furnace dust was carried out by using granulometry analysis, chemical analysis, X-ray diffraction (XRD), thermogravimetric/differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The leaching process was based on the Zn extraction with diluted sulphuric acid from EAFD under atmospheric conditions and without using any preliminary treatment. Statistical design and analysis of experiments were used, in order to determine the main effects and interactions of the leaching process factors, which were: acid normality, temperature and solid to liquid ratio. The zinc recovery efficiency on the basis of EAFD weight reached 80%. X-ray diffraction and scanning electron microscopy were used for the characterization of the leached residues.

  18. Carbon honeycomb grids for advanced lead-acid batteries. Part I: Proof of concept

    NASA Astrophysics Data System (ADS)

    Kirchev, Angel; Kircheva, Nina; Perrin, Marion

    2011-10-01

    The carbon honeycomb grid is proposed as innovative solution for high energy density lead acid battery. The proof of concept is demonstrated, developing grids suitable for the small capacity, scale of valve-regulated lead acid batteries with 2.5-3 Ah plates. The manufacturing of the grids, includes fast, known and simple processes which can be rescaled for mass production with a minimum, investment costs. The most critical process of green composite carbonisation by heating in inert, atmosphere from 200 to 1000 °C takes about 5 h, guaranteeing the low cost of the grids. An AGM-VRLA, cell with prototype positive plate based on the lead-2% tin electroplated carbon honeycomb grid and, conventional negative plates is cycled demonstrating 191 deep cycles. The impedance spectroscopy, measurements indicate the grid performance remains acceptable despite the evolution of the corrosion, processes during the cycling.

  19. A flash-photolysis electron spin resonance study of radicals formed from carboxylic acids; exchange effects in spin-polarized radicals

    NASA Astrophysics Data System (ADS)

    McLauchlan, K. A.; Ritchie, A. J. D.

    The time-integration spectroscopy (TIS) technique has been applied to the study of transient radicals created by flash photolysis of solutions of benzene-1,2,4,5-tetracarboxylic acid (pyromellitic acid), benzene-1,2,-dicarboxylic acid (phthalic acid) and benzene-1,4-dicarboxylic acid (terephthalic acid). In these systems electron transfer, proton transfer and rotational isomerism all affect the spin-polarized spectra observed. The exchange processes are analysed theoretically, in the case of proton exchange for the first time in the polarized situation, and it is shown that the two different exchange processes can be simply differentiated in the time-dependent TIS spectra.

  20. Anti-MRSA cephems. Part 3: additional C-7 acid derivatives.

    PubMed

    Springer, Dane M; Luh, Bing Yu; Goodrich, Jason T; Bronson, Joanne J

    2003-01-17

    Twenty-seven novel cephalosporin derivatives with activity against methicillin-resistant Staphylococcus aureus (MRSA) are described. The compounds contain novel acid moieties at C-7 that were synthesized using nucleophilic aromatic substitution reactions and Stille couplings. The most interesting compound (6) displayed an MIC(90) against MRSA of 3.7 microg/mL, and an average PD(50) of 3.9 mg/kg.

  1. Anti-MRSA cephems. Part 2: C-7 cinnamic acid derivatives.

    PubMed

    Springer, Dane M; Luh, Bing Yu; Goodrich, Jason; Bronson, Joanne J

    2003-01-17

    Forty-five novel cephalosporin derivatives with activity against methicillin-resistant Staphylococcus aureus (MRSA) are described. The compounds contain novel cinnamic acid moieties at C-7 that were synthesized using a key Heck reaction followed by nucleophilic aromatic substitution reactions. The most active compound (41) displayed an MIC(90) against MRSA of 1.0 microg/mL, and a PD(50) of 0.8 mg/kg. Compound 14 was found to be very safe in a mouse model of acute toxicity.

  2. Poly(lactic acid)/natural rubber/cellulose nanocrystal bionanocomposites part I. Processing and morphology.

    PubMed

    Bitinis, Natacha; Verdejo, Raquel; Bras, Julien; Fortunati, Elena; Kenny, Jose Maria; Torre, Luigi; López-Manchado, Miguel Angel

    2013-07-25

    PLA/NR/cellulose nanowhisker composites were prepared using three types of cellulose nanocrystals (CNC), i.e. unmodified CNC obtained from acid hydrolysis of microcrystalline cellulose and two surface modified CNC. The two modification reactions, consisting on the grafting of long alkyl chains and of PLA chains onto the cellulose nanocrystals were carried out in order to facilitate the incorporation of the nanocrystals in the PLA/NR blend. A novel processing method was optimized combining solvent casting and extrusion in order to obtain a homogeneous dispersion of the nanofillers in the blend. The CNC modifications determined their location in the PLA/NR blend and influenced its morphology.

  3. Copper(ii) complexes of macrocyclic and open-chain pseudopeptidic ligands: synthesis, characterization and interaction with dicarboxylates.

    PubMed

    Faggi, Enrico; Gavara, Raquel; Bolte, Michael; Fajarí, Lluís; Juliá, Luís; Rodríguez, Laura; Alfonso, Ignacio

    2015-07-28

    Mono- and dinuclear Cu(ii) complexes were prepared with pseudopeptidic open chain and macrocyclic ligands, respectively. They were characterized by UV-vis spectroscopy, EPR, HRMS and X-ray diffraction. The Cu(ii) cation is coordinated by two amines and two deprotonated amides, in a slightly distorted square planar coordination geometry. The complexes interact with several substituted dicarboxylates, as shown by UV-vis titrations and EPR experiments. The interaction of both mono- and dinuclear complexes with very similar dicarboxylates of biological interest (malate and aspartate) resulted in strikingly different outcomes: in the first case a ternary complex [ligand...metal...dicarboxylate] was obtained almost quantitatively, while in the latter, the Cu(ii) displacement to form Cu(Asp)2 was predominant.

  4. Phospholipid fatty acid analysis as part of the Yucca Mountain Project. Final report

    SciTech Connect

    Ringelberg, D.B.; White, D.C.

    1996-09-01

    In support of the Yucca Mountain subsurface microbial characterization project phospholipid fatty acid (PLFA) analyses for viable microbial biomass, community composition and nutritional status were performed. Results showed a positive correlation between a decrease in viable biomass and increase in depth with the lowest biomass values being obtained from the Topopah Spring geologic horizon. A plot of the ratio of non-viable (diglyceride fatty acids) to viable (PLFA) cells also showed the lowest values to derive from the Topopah Spring horizon. Estimations of microbial community composition, made from the patterns of PLFA recovered from the sediment samples, revealed similarities between samples collected within the same geologic horizons: Tiva Canyon, Pre-Pah Canyon and Topopah Spring. Results indicated the presence of mixed communities composed of gram positive, gram negative, actinomycete and obligate anaerobic bacteria. Culturable organisms, recovered from similar sediments, were representative of the same bacterial classifications although gram positive bacterial isolates typically outnumbered gram negative isolates. Within the gram negative bacterial community, corroborative indicators of physiological stress were apparent in the Topopah Spring horizon.

  5. Kappa-opioid receptor-selective dicarboxylic ester-derived salvinorin A ligands.

    PubMed

    Polepally, Prabhakar R; White, Kate; Vardy, Eyal; Roth, Bryan L; Ferreira, Daneel; Zjawiony, Jordan K

    2013-05-15

    Salvinorin A, the active ingredient of the hallucinogenic plant Salvia divinorum is the most potent known naturally occurring hallucinogen and is a selective κ-opioid receptor agonist. To better understand the ligand-receptor interactions, a series of dicarboxylic ester-type of salvinorin A derivatives were synthesized and evaluated for their binding affinity at κ-, δ- and μ-opioid receptors. Most of the analogues show high affinity to the κ-opioid receptor. Methyl malonyl derivative 4 shows the highest binding affinity (Ki=2nM), analogues 5, 7, and 14 exhibit significant affinity for the κ-receptor (Ki=21, 36 and 39nM).

  6. Kappa-Opioid Receptor-Selective Dicarboxylic Ester-Derived Salvinorin A Ligands

    PubMed Central

    Polepally, Prabhakar R.; White, Kate; Vardy, Eyal; Roth, Bryan L.; Ferreira, Daneel; Zjawiony, Jordan K.

    2013-01-01

    Salvinorin A, the active ingredient of the hallucinogenic plant Salvia divinorum is the most potent known naturally occurring hallucinogen and is a selective κ-opioid receptor agonist. To better understand the ligand-receptor interactions, a series of dicarboxylic ester-type of salvinorin A derivatives were synthesized and evaluated for their binding affinity at κ, δ, and μ-opioid receptors. Most of the analogues show high affinity to the κ-opioid receptor. Methyl malonyl derivative 4 shows the highest binding affinity (Ki = 2 nM), analogues 5, 7, and 14 exhibit significant affinity for the κ-receptor (Ki = 21, 36 and 39 nM). PMID:23587424

  7. Practical Synthesis of Axially Chiral Dicarboxylates via Pd-Catalyzed External-CO-Free Carbonylation.

    PubMed

    Konishi, Hideyuki; Hoshino, Fumika; Manabe, Kei

    2016-10-01

    We have developed a safe and practical synthetic method for preparing axially chiral diphenyl dicarboxylates using Pd-catalyzed external-CO-free carbonylation with phenyl formate as a CO surrogate. Optimized conditions consisted of axially chiral [1,1'-binaphthalene]-2,2'-diyl ditriflate and its congeners, each easily prepared from commercially available enantiomerically pure diols, Pd(OAc)2, 1,3-bis(diphenylphosphino)propane, ethyldiisopropylamine, and no solvent. To demonstrate the potential utility of these products, this method was conducted on gram-scale and the phenyl ester products were converted to other useful compounds, and both processes were carried out without difficulty.

  8. XRD, IR and XAFS studies of cobalt complexes having amino pyrazole dicarboxylate (APD) as ligand

    NASA Astrophysics Data System (ADS)

    Mishra, Ashutosh; Jain, Garima; Patil, H.

    2014-09-01

    X-ray absorption fine structure spectroscopic (XAFS) studies have been done on two cobalt complexes using APD (diethyl 4-amino-1-phenyl-1H-pyrazole-3,5 dicarboxylate) as ligand. The X-ray absorption spectra of the complexes have been recorded on beam line of synchrotron at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore (India). The X-ray diffraction of the samples has also been carried out. FTIR studies of two samples were also reported in the present communication.

  9. [Biosynthesis of adipic acid].

    PubMed

    Han, Li; Chen, Wujiu; Yuan, Fei; Zhang, Yuanyuan; Wang, Qinhong; Ma, Yanhe

    2013-10-01

    Adipic acid is a six-carbon dicarboxylic acid, mainly for the production of polymers such as nylon, chemical fiber and engineering plastics. Its annual demand is close to 3 million tons worldwide. Currently, the industrial production of adipic acid is based on the oxidation of aromatics from non-renewable petroleum resources by chemo-catalytic processes. It is heavily polluted and unsustainable, and the possible alternative method for adipic acid production should be developed. In the past years, with the development of synthetic biology and metabolic engineering, green and clean biotechnological methods for adipic acid production attracted more attention. In this study, the research advances of adipic acid and its precursor production are reviewed, followed by addressing the perspective of the possible new pathways for adipic acid production.

  10. Poly(lactic acid)/natural rubber/cellulose nanocrystal bionanocomposites. Part II: properties evaluation.

    PubMed

    Bitinis, Natacha; Fortunati, Elena; Verdejo, Raquel; Bras, Julien; Kenny, Jose Maria; Torre, Luigi; López-Manchado, Miguel Angel

    2013-07-25

    The crystallization, mechanical and biodegradation properties of poly(lactic acid)/natural rubber/cellulose nanocrystals (CNC) bionanocomposites were evaluated. Three types of CNC were used in this study, one unmodified (CNC), long alkyl chain grafted CNC (C18-g-CNC) and PLA grafted CNC (PLA-g-CNC). The CNC modifications determined the affinity of the nanocrystals toward the polymers and reflected on the ultimate properties. Interestingly, PLA-g-CNC acted as a nucleating agent for the PLA matrix in the bio-based PLA/NR blend. Good mechanical properties were reported, as the bionanocomposites maintained a high elongation at break for a concentration up to 3 wt.% of cellulose nanocrystals. Moreover, the disintegration study confirmed that the materials completely disintegrated after one month in compost.

  11. Organic Analysis in the Miller Range 090657 CR2 Chondrite: Part 2 Amino Acid Analyses

    NASA Technical Reports Server (NTRS)

    Burton, A. S.; Cao, T.; Nakamura-Messenger, K.; Berger, E. L.; Messenger, S.; Clemett, S. J.; Aponte, J. C.; Elsila, J. E.

    2016-01-01

    Primitive carbonaceous chondrites contain a wide variety of organic material, ranging from soluble discrete molecules to insoluble, unstructured kerogen-like components, as well as structured nano-globules of macromolecular carbon. The relationship between the soluble organic molecules, macromolecular organic material, and host minerals are poorly understood. Due to the differences in extractability of soluble and insoluble organic materials, the analysis methods for each differ and are often performed independently. The combination of soluble and insoluble analyses, when performed concurrently, can provide a wider understanding of spatial distribution, and elemental, structural and isotopic composition of organic material in primitive meteorites. Using macroscale extraction and analysis techniques in combination with in situ microscale observation, we have been studying both insoluble and soluble organic material in the primitive CR2 chondrite Miller Range (MIL) 090657. In accompanying abstracts (Cao et al. and Messenger et al.) we discuss insoluble organic material in the samples. By performing the consortium studies, we aim to improve our understanding of the relationship between the meteorite minerals and the soluble and insoluble organic phases and to delineate which species formed within the meteorite and those that formed in nebular or presolar environments. In this abstract, we present the results of amino acid analyses of MIL 090657 by ultra performance liquid chromatography with fluorescence detection and quadrupole-time of flight mass spectrometry. Amino acids are of interest because they are essential to life on Earth, and because they are present in sufficient structural, enantiomeric and isotopic diversity to allow insights into early solar system chemical processes. Furthermore, these are among the most isotopically anomalous species, yet at least some fraction are thought to have formed by aqueously-mediated processes during parent body alteration.

  12. High temperature abatement of acid gases from waste incineration. Part II: Comparative life cycle assessment study

    SciTech Connect

    Biganzoli, Laura; Racanella, Gaia; Marras, Roberto; Rigamonti, Lucia

    2015-01-15

    Highlights: • Two scenarios of acid gases removal in WTE plants were compared in an LCA study. • A detailed inventory based on primary data has been reported for the production of the new dolomitic sorbent. • Results show that the comparison between the two scenarios does not show systematic differences. • The potential impacts are reduced only if there is an increase in the energy efficiency of the WTE plant. - Abstract: The performances of a new dolomitic sorbent, named Depurcal®MG, to be directly injected at high temperature in the combustion chamber of Waste-To-Energy (WTE) plants as a preliminary stage of deacidification, were experimentally tested during full-scale commercial operation. Results of the experimentations were promising, and have been extensively described in Biganzoli et al. (2014). This paper reports the Life Cycle Assessment (LCA) study performed to compare the traditional operation of the plants, based on the sole sodium bicarbonate feeding at low temperature, with the new one, where the dolomitic sorbent is injected at high temperature. In the latter the sodium bicarbonate is still used, but at lower rate because of the decreased load of acid gases entering the flue gas treatment line. The major goal of the LCA was to make sure that a burden shifting was not taking place somewhere in the life cycle stages, as it might be the case when a new material is used in substitution of another one. According to the comparative approach, only the processes which differ between the two operational modes were included in the system boundaries. They are the production of the two reactants and the treatment of the corresponding solid residues arising from the neutralisation of acid gases. The additional CO{sub 2} emission at the stack of the WTE plant due to the activation of the sodium bicarbonate was also included in the calculation. Data used in the modelling of the foreground system are primary, derived from the experimental tests described in

  13. Unusual fatty acid compositions of the hyperthermophilic archaeon Pyrococcus furiosus and the bacterium Thermotoga maritima.

    PubMed Central

    Carballeira, N M; Reyes, M; Sostre, A; Huang, H; Verhagen, M F; Adams, M W

    1997-01-01

    The fatty acid compositions of the hyperthermophilic microorganisms Thermotoga maritima and Pyrococcus furiosus were studied and compared. A total of 37 different fatty acids were identified in T. maritima, including the novel 13,14-dimethyloctacosanedioic acid. In contrast, a total of 18 different fatty acids were characterized, as minor components, in P. furiosus, and these included saturated, monounsaturated, and dicarboxylic acids. This is the first report of fatty acids from an archaeon. PMID:9098079

  14. Carbon honeycomb grids for advanced lead-acid batteries. Part II: Operation of the negative plates

    NASA Astrophysics Data System (ADS)

    Kirchev, A.; Dumenil, S.; Alias, M.; Christin, R.; de Mascarel, A.; Perrin, M.

    2015-04-01

    The article presents the recent progress in the carbon honeycomb grid technology for valve-regulated lead-acid batteries with absorptive glass-mat separators (AGM-VRLAB). The work is focused on the development of negative current collectors using industrial grade composite honeycomb precursors. The developed model AGM-VRLA cells comprised of one prototype honeycomb negative electrode and two conventional traction positive counter-electrodes show high utilisation of the negative active material and long cycle life both in high-rate partial state of charge (HRPSoC) cycling mode and in deep cycling mode. The analysis of the results from the cycle-life tests and the tear-down analysis indicate that the benefits delivered by the novel grids can be related to the low mesh size of the grid, low γ-coefficient, as well as the use of milled carbon fibre additive. The combination of the three, results in the reversibility of the negative active material sulfation process when the electrolyte concentration in the cells is lower than the one traditionally used in the AGM-VRLAB technology. The negative plates show no signs of irreversible degradation after more than 900 cycles in deep cycling mode and more than 2000 capacity turnovers (equivalent cycles) in HRPSoC cycling mode.

  15. Heterogeneous formation of polar stratospheric clouds - Part 1: Nucleation of nitric acid trihydrate (NAT)

    NASA Astrophysics Data System (ADS)

    Hoyle, C. R.; Engel, I.; Luo, B. P.; Pitts, M. C.; Poole, L. R.; Grooß, J.-U.; Peter, T.

    2013-03-01

    Satellite based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarisation (CALIOP) observation points. Comparing the optical properties of the modelled NAT with these observations enabled the thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM). The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed PSCs very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

  16. Heterogeneous formation of polar stratospheric clouds - Part 1: Nucleation of nitric acid trihydrate (NAT)

    NASA Astrophysics Data System (ADS)

    Hoyle, C. R.; Engel, I.; Luo, B. P.; Pitts, M. C.; Poole, L. R.; Grooß, J.-U.; Peter, T.

    2013-09-01

    Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) observation points. Comparing the optical properties of the modelled NAT with these observations enabled a thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM). The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed polar stratospheric clouds (PSCs) very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

  17. In vivo evaluation of polysialic acid as part of tissue-engineered nerve transplants.

    PubMed

    Haastert-Talini, Kirsten; Schaper-Rinkel, Janett; Schmitte, Ruth; Bastian, Rode; Mühlenhoff, Martina; Schwarzer, David; Draeger, Gerald; Su, Yi; Scheper, Thomas; Gerardy-Schahn, Rita; Grothe, Claudia

    2010-10-01

    With the aim to develop new biomaterials for peripheral nerve grafts, the current study used bioidentical polysialic acid (polySia) as complement in synthetic conduits. polySia provides an important guidance cue during nervous system development and regeneration. First in vivo results on the use of cell-free and Schwann cell-containing synthetic peripheral nerve grafts complemented with soluble exogenous K1-polySia are presented. Reconstructing 10 mm rat sciatic nerve gaps, K1-polySia complementation significantly improved structural nerve regeneration in comparison to cell-free and K1-polySia-free grafts. Subsequently, long nerve gaps (13 mm) were reconstructed by Schwann cell transplants plus K1-polySia and compared to nerve autotransplantation. Structural but also functional regeneration could be observed using K1-polySia transplants; however, autotransplantation was still significantly more successful. Overall, the current study demonstrates that exogenous K1-polySia has no negative but rather regeneration promoting effects. This is important novel evidence on the applicability of exogenous polySia in vivo. Further studies are required to develop solid three-dimensional polySia-based scaffolds for nerve tissue engineering. Biocompatible and assessable biodegrading materials will ensure long-lasting presence of polySia to allow its applicability and prolonged efficacy in the slow regenerating scenario of human peripheral nerve reconstruction.

  18. Heterogeneous Formation of Polar Stratospheric Clouds- Part 1: Nucleation of Nitric Acid Trihydrate (NAT)

    NASA Technical Reports Server (NTRS)

    Hoyle, C. R.; Engel, I.; Luo, B. P.; Pitts, M. C.; Poole, L. R.; Grooss, J.-U.; Peter, T.

    2013-01-01

    Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) observation points. Comparing the optical properties of the modelled NAT with these observations enabled a thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM). The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed polar stratospheric clouds (PSCs) very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

  19. Syntheses and some features of five new cyclohexane-1,3-dicarboxylates with multiple stereogenic centers

    NASA Astrophysics Data System (ADS)

    Ismiyev, Arif M.; Maharramov, Abel M.; Aliyeva, Rafiga A.; Askerov, Rizvan K.; Mahmudov, Kamran T.; Kopylovich, Maximilian N.; Naïli, Houcine; Pombeiro, Armando J. L.

    2013-01-01

    The condensation of diethyl 4-hydroxy-4-methyl-6-oxo-2-(4-substitutedphenyl)-cyclohexane-1,3-dicarboxylates and N'-(2-chloropropyl)ethane-1,2-diamine leads to diethyl 1-(2-chloropropyl)-9-hydroxy-9-methyl-7-phenyl-1,4-diazaspiro[4.5]decane-6,8-dicarboxylate (2) and its para-substituted methyl (1), chloro (3), bromo (4), and nitro (5) derivatives with a new stereogenic center, which were fully characterized by elemental analysis, ESI-MS, IR, 1H and 13C NMR spectroscopies and X-ray single-crystal analysis (for 2). The condensation reaction is regioselective, only cyclohexanone carbonyl moiety undergoes the transformation, leaving the β-keto ester carbonyls unreacted. Withing the compounds 1-5, the increase in the Hammett's σp, related normal σpn, inductive σI, negative σp- and positive σp+ polar conjugation and Taft's σpo substituent constants generally leads to the corresponding drift of δOsbnd H and δNsbnd H NMR chemical shifts to lower field.

  20. Two- and three-dimensional networks of gadolinium(III) with dicarboxylate ligands: synthesis, crystal structure, and magnetic properties.

    PubMed

    Cañadillas-Delgado, Laura; Pasan, Jorge; Fabelo, Oscar; Hernandez-Molina, María; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

    2006-12-25

    Four gadolinium(III) complexes with dicarboxylate ligands of formulas [Gd2(mal)3(H2O)5]n.2nH2O (1), [Gd2(mal)3(H2O)6]n (2), [NaGd(mal)(ox)(H2O)3]n (3), and [Gd2(ox)3(H2O)6]n.2.5nH2O (4) (mal = malonate; ox = oxalate) have been prepared, and their magnetic properties have been investigated as a function of the temperature. The structures of 1-3 have been determined by X-ray diffraction methods. The crystal structure of 4 was already known, and it is made of hexagonal layers of Gd atoms that are bridged by bis-bidentate oxalate. Compound 1 is isostructural with the europium(III) malonate complex [Eu2(mal)3(H2O)5]n.2nH2O,1 whose structure was reported elsewhere. The Gd atoms in 1 define a two-dimensional network where a terminal bidentate and bridging bidentate/bis-monodentate and tris-bidentate coordination modes of malonate occur. Compound 2 has a three-dimensional structure with a structural phase transition at 226 K, which involves a change of the space group from I2/a to Ia. Although its structure at room temperature was already known, that below 226 K was not. Pairs of Gd atoms with a double oxo-carboxylate bridge occur in both phases, and the main differences between both structures deal with the Gd environment and the H-bond pattern. 3 is also a three-dimensional compound, and it was obtained by reacting Gd(III) ions with malonic acid in a silica gel medium. Oxalic acid results as an oxidized product of the malonic acid, and single crystals of the heteroleptic complex were produced. The Gd atoms in 3 are connected through bis-bidentate oxalate and carboxylate-malonate bridges in the anti-anti and anti-syn coordination modes. Compounds 1 and 2 exhibit weak but significant ferromagnetic couplings between the Gd(III) ions through the single (1) and double (2) oxo-carboxylate bridges, whereas antiferromagnetic interactions across the bis-bidentate oxalate account for the overall antiferromagnetic behavior observed in 3 and 4.

  1. Tribological properties of boric acid and boric-acid-forming surfaces: Part 2, Formation and self-lubrication mechanisms of boric acid films on boron- and boric-oxide-containing surfaces

    SciTech Connect

    Erdemir, A.; Fenske, G.R.; Erck, R.A.; Nichols, F.A.; Busch, D.

    1990-01-01

    This paper describes the formation and self-lubricating mechanisms of boric acid films on boron- and boric oxide-containing surfaces. As reported in part I, boric acid, owing to a layered triclinic crystal structure and weak interlayer bonds, enjoys an unusual lubrication capability. RF-magnetron sputtering and vacuum evaporation techniques were used to produce thin coatings of boron and boric oxides on steel substrates. The results of tribological experiments indicate that the room temperature friction coefficient of tribosystems that include boron and/or boric oxide coatings ranges from 0.05 to 0.07, depending on the coating type. Laser-Raman spectroscopy of these surfaces revealed that this low friction is associated with a thin boric acid film that forms on the surfaces of these coatings. The fabrication and potential importance of boric acid and boric acid-forming surfaces for practical applications are enumerated. Surface engineering of tribomaterials, such as these demonstrated in this paper, is suggested as a new lubrication concept for use in present and future tribological industries. 16 refs.

  2. Site-Specifically Labeled Immunoconjugates for Molecular Imaging—Part 2: Peptide Tags and Unnatural Amino Acids

    PubMed Central

    Adumeau, Pierre; Sharma, Sai Kiran; Brent, Colleen; Zeglis, Brian M.

    2016-01-01

    Molecular imaging using radioisotope- or fluorophore-labeled antibodies is increasingly becoming a critical component of modern precision medicine. Yet despite this promise, the vast majority of these immunoconjugates are synthesized via the random coupling of amine-reactive bifunctional probes to lysines within the antibody, a process that can result in heterogeneous and poorly defined constructs with suboptimal pharmacological properties. In an effort to circumvent these issues, the last 5 years have played witness to a great deal of research focused on the creation of effective strategies for the site-specific attachment of payloads to antibodies. These chemoselective modification methods yield immunoconjugates that are more homogenous and better defined than constructs created using traditional synthetic approaches. Moreover, site-specifically labeled immunoconjugates have also been shown to exhibit superior in vivo behavior compared to their randomly modified cousins. The over-arching goal of this two-part review is to provide a broad yet detailed account of the various site-specific bioconjugation approaches that have been used to create immunoconjugates for positron emission tomography (PET), single photon emission computed tomography (SPECT), and fluorescence imaging. In Part 1, we covered site-specific bioconjugation techniques based on the modification of cysteine residues and the chemoenzymatic manipulation of glycans. In Part 2, we will detail two families of bioconjugation approaches that leverage biochemical tools to achieve site-specificity. First, we will discuss modification methods that employ peptide tags either as sites for enzyme-catalyzed ligations or as radiometal coordination architectures. And second, we will examine bioconjugation strategies predicated on the incorporation of unnatural or non-canonical amino acids into antibodies via genetic engineering. Finally, we will compare the advantages and disadvantages of the modification

  3. CitA (citrate) and DcuS (C4-dicarboxylate) sensor kinases in thermophilic Geobacillus kaustophilus and Geobacillus thermodenitrificans.

    PubMed

    Graf, Sabrina; Broll, Constanze; Wissig, Juliane; Strecker, Alexander; Parowatkin, Maria; Unden, Gottfried

    2016-01-01

    The thermophilic Geobacillus thermodenitrificans and Geobacillus kaustophilus are able to use citrate or C4-dicarboxylates like fumarate or succinate as the substrates for growth. The genomes of the sequenced Geobacillus strains (nine strains) each encoded a two-component system of the CitA family. The sensor kinase of G. thermodenitrificans (termed CitAGt) was able to replace CitA of Escherichia coli (CitAEc) in a heterologous complementation assay restoring expression of the CitAEc-dependent citC-lacZ reporter gene and anaerobic growth on citrate. Complementation was specific for citrate. The sensor kinase of G. kaustophilus (termed DcuSGk) was able to replace DcuSEc of E. coli. It responded in the heterologous expression system to C4-dicarboxylates and to citrate, suggesting that DcuSGk is, like DcuSEc, a C4-dicarboxylate sensor with a side-activity for citrate. DcuSGk, unlike the homologous DctS from Bacillus subtilis, required no binding protein for function in the complementation assay. Thus, the thermophilic G. thermodenitrificans and G. kaustophilus contain citrate and C4-dicarboxylate sensor kinases of the CitA and DcuS type, respectively, and retain function and substrate specificity under mesophilic growth conditions in E. coli.

  4. Molar Absorptivity and Quantum Yield of Fe(II) Photo-formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Comlexes

    NASA Astrophysics Data System (ADS)

    Hitomi, Y.; Arakaki, T.

    2009-04-01

    Fe(III)/Fe(II) cycle in the environment affects formation of active oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be an important source of photo-chemically formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species in the aqueous solutions of Fe(III)-dicarboxylate complexes. The molar absorptivity and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained by UV-VIS spectrophotometer and photochemical experiments, and these experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. Dicarboxylate compounds studied were oxalate, malonate, succinate, malate, and phthalate.

  5. Model Prediction of Sulfuric Acid in the Tropical/Subtropical Cirrus Clouds as a Part of CRYSTAL-FACE Mission

    NASA Astrophysics Data System (ADS)

    Kanawade, V.; Tripathi, S. N.

    2005-12-01

    Recent studies show that new particle formation takes place in the cirrus clouds, however, it has not been examined how the formation of new particle occur. Recent experiments, in cirrus clouds, provide in-situ data for particles of diameter 4-6 nm; unfortunately, simultaneous measurement of precursor gases e.g. SO2 and/or H2SO4 concentration is not available. This hinders model prediction of the newly formed particles. In-situ measurements of ultrafine particles, diameter 4 to 6 nm, carried out during 23 July 2002 (WB-57 mission), as a part of CRYSTAL-FACE mission, over Florida, were used for prediction of sulfuric acid and consequently SO2 concentration in the tropical/subtropical cirrus clouds. Using aerosol microphysical model, driven by parameterized binary homogenous nucleation [Vehkamaki et al., 2002] and ion induced nucleation [Modgil et al., 2005] (one at a time), and in-situ measured environmental conditions i.e. temperature, relative humidity and ultrafine particle number concentration, we have calculated likely source strength of sulfuric acid, which is used to infer the dominating nucleation mechanism for ultrafine particles. Model results, for particles diameter 4 to 6 nm, show that the binary homogenous nucleation rates are ~6 fold higher than the ion induced nucleation rates, suggesting that the binary homogenous nucleation mechanism is likely to dominate over ion induced nucleation mechanism in the tropical/subtropical cirrus clouds. The binary homogenous nucleation model and ion induced nucleation model, respectively, predicts sulfuric acid concentrations in the range 2-8 105 molecules cm-3 (SO2=0.3-0.75 ppbv) and 7.5 105 106 molecules cm-3 (SO2=1-3 ppbv),. About 75% of the model simulations show reasonable agreement between predicted and observed particles of diameter from 6 to 9 nm and 4 to 9 nm. Refrences Modgil, M. S. et al., A parameterization of ion-induced nucleation of sulfuric acid and water for atmospheric conditions, J. Geophys. Res

  6. Defensive strategies in Geranium sylvaticum, Part 2: Roles of water-soluble tannins, flavonoids and phenolic acids against natural enemies.

    PubMed

    Tuominen, Anu

    2013-11-01

    Geranium sylvaticum is a common herbaceous plant in Fennoscandia, which has a unique phenolic composition. Ellagitannins, proanthocyanidins, galloylglucoses, gallotannins, galloyl quinic acids and flavonoids possess variable distribution in its different organs. These phenolic compounds are thought to have an important role in plant-herbivore interactions. The aim of this study was to quantify these different water-soluble phenolic compounds and measure the biological activity of the eight organs of G. sylvaticum. Compounds were characterized and quantified using HPLC-DAD/MS, in addition, total proanthocyanidins were determined by BuOH-HCl assay and total phenolics by the Folin-Ciocalteau method. Two in vitro biological activity measurements were used: the prooxidant activity was measured by the browning assay and antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Organ extracts were fractionated using column chromatography on Sephadex LH-20 and the activities of fractions was similarly measured to evaluate which polyphenol groups contributed the most to the biological activity of each organ. The data on the activity of fractions were examined by multivariate data analysis. The water-soluble extracts of leaves and pistils, which contained over 30% of the dry weight as ellagitannins, showed the highest pro-oxidant activity among the organ extracts. Fraction analysis revealed that flavonoids and galloyl quinic acids also exhibited high pro-oxidant activity. In contrast, the most antioxidant active organ extracts were those of the main roots and hairy roots that contained high amounts of proanthocyanidins in addition to ellagitannins. Analysis of the fractions showed that especially ellagitannins and galloyl quinic acids have high antioxidant activity. We conclude that G. sylvaticum allocates a significant amount of tannins in those plant parts that are important to the fitness of the plant and susceptible to natural enemies, i

  7. Supramolecular assemblies of 4,7-phenanthroline with various aromatic polycarboxylic acids

    NASA Astrophysics Data System (ADS)

    Biswas, Sharmita Nandy; Nandy, Purnendu

    2016-10-01

    Five molecular complexes 1a-1e, of 4,7-phenanthroline (1) with various aromatic polycarboxylic acids such as benzene-1,3-dicarboxylic acid (a), pyridine-2,6-dicarboxylic acid (b), pyridine-2,5-dicarboxylic acid (c), benzene-1,2,3,4,5-pentacarboxylic acid (d) and 1,2,3,4,5,6-benzenehexacarboxylic acid (e) have been prepared and characterized by single crystal X-ray diffraction and thermogravimetric analyses. The analysis shows that all the assemblies crystallized as hydrates, except complex, 1c, formed between 1 and pyridine-2,5-dicarboxylic acid. Single crystal X-ray data reveals that the packing patterns of all the molecular complexes have been directed by strong hydrogen bonding O-H⋯O/O-H⋯N/N+-H⋯O- and weak hydrogen bonding C-H⋯O interactions. All the hydrated assemblies aggregate through the formation of cyclic networks as basic recognition pattern. Further, we observed that water molecules play significant role for production of supramolecular assemblies.

  8. Carbonization and oxidation of metal-organic frameworks based on 1,4-naphthalene dicarboxylates.

    PubMed

    Chen, Jiun-Jen; Chen, Ya-Ting; Senthil Raja, Duraisamy; Kang, Yu-Hao; Tseng, Pen-Chang; Lin, Chia-Her

    2015-10-01

    Three new isostructural metal-organic frameworks (MOFs), [V(OH)(NDC)] (1), [Cr(OH)(NDC)] (2), and [Ga(OH)(NDC)] (3) have been synthesized hydrothermally using 1,4-naphthalene dicarboxylate (NDC) as the linker. These MOFs (1, 2 and 3) have been used as a template for the synthesis of metal-oxide-inserted nanoporous carbon materials. The newly synthesized MOFs and the resulting porous carbon hybrid functional materials have been characterized using powder x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopic analysis. Results show that compounds 2 and 3 form their respective metal oxide nanoparticles on the surface of the carbon materials during carbonization at 800 °C. The gas sorption properties of the new MOFs and their corresponding carbon frameworks have been reported.

  9. Penetration of biomass-burning emissions from South Asia through the Himalayas: new insights from atmospheric organic acids

    PubMed Central

    Cong, Zhiyuan; Kawamura, Kimitaka; Kang, Shichang; Fu, Pingqing

    2015-01-01

    High levels of carbonaceous aerosol exist over South Asia, the area adjacent to the Himalayas and Tibetan Plateau. Little is known about if they can be transported across the Himalayas, and as far inland as the Tibetan Plateau. As important constituents of aerosols, organic acids have been recognized as unique fingerprints to identify the atmospheric process. Here we measured dicarboxylic acids and related compounds in aerosols on the northern slope of Mt. Everest (Qomolangma, 4276 m a.s.l.). Strong positive correlations were observed for dicarboxylic acids with biomass burning tracers, levoglucosan and K+, demonstrating that this area was evidently affected by biomass burning. The seasonal variation pattern of dicarboxylic acids is consistent with OC and EC, being characterized by a pronounced maximum in the pre-monsoon season. Molecular distributions of dicarboxylic acids and related compounds (malonic acid/succinic acid, maleic acid/fumaric acid) further support this finding. We suggest that the local meteorological conditions and regional atmospheric flow process could facilitate the penetration of the carbonaceous aerosols from South Asia throughout the Himalayas. With the consideration of the darkening force of carbonaceous aerosols, our finding has important implication for this climate-sensitive area, where the glacier melting supplies water for billions of people downstream. PMID:25854556

  10. Penetration of biomass-burning emissions from South Asia through the Himalayas: new insights from atmospheric organic acids.

    PubMed

    Cong, Zhiyuan; Kawamura, Kimitaka; Kang, Shichang; Fu, Pingqing

    2015-04-09

    High levels of carbonaceous aerosol exist over South Asia, the area adjacent to the Himalayas and Tibetan Plateau. Little is known about if they can be transported across the Himalayas, and as far inland as the Tibetan Plateau. As important constituents of aerosols, organic acids have been recognized as unique fingerprints to identify the atmospheric process. Here we measured dicarboxylic acids and related compounds in aerosols on the northern slope of Mt. Everest (Qomolangma, 4276 m a.s.l.). Strong positive correlations were observed for dicarboxylic acids with biomass burning tracers, levoglucosan and K(+), demonstrating that this area was evidently affected by biomass burning. The seasonal variation pattern of dicarboxylic acids is consistent with OC and EC, being characterized by a pronounced maximum in the pre-monsoon season. Molecular distributions of dicarboxylic acids and related compounds (malonic acid/succinic acid, maleic acid/fumaric acid) further support this finding. We suggest that the local meteorological conditions and regional atmospheric flow process could facilitate the penetration of the carbonaceous aerosols from South Asia throughout the Himalayas. With the consideration of the darkening force of carbonaceous aerosols, our finding has important implication for this climate-sensitive area, where the glacier melting supplies water for billions of people downstream.

  11. 2D→3D polycatenated and 3D→3D interpenetrated metal–organic frameworks constructed from thiophene-2,5-dicarboxylate and rigid bis(imidazole) ligands

    SciTech Connect

    Erer, Hakan; Yeşilel, Okan Zafer; Arıcı, Mürsel; Keskin, Seda; Büyükgüngör, Orhan

    2014-02-15

    Hydrothermal reactions of rigid 1,4-bis(imidazol-1-yl)benzene (dib) and 1,4-bis(imidazol-1-yl)-2,5-dimethylbenzene (dimb) with deprotonated thiophene-2,5-dicarboxylic acid (H{sub 2}tdc) in the presence of Zn(II) and Cd(II) salts in H{sub 2}O produced three new metal–organic frameworks, namely, [Zn(µ-tdc)(H{sub 2}O)(µ-dib)]{sub n} (1), [Cd(µ-tdc)(H{sub 2}O)(µ-dib)]{sub n} (2), and ([Cd{sub 2}(µ{sub 3}-tdc){sub 2}(µ-dimb){sub 2}]·(H{sub 2}O)){sub n}(3). These MOFs were characterized by FT-IR spectroscopy, elemental, thermal (TG, DTA, DTG and DSC), and single-crystal X-ray diffraction analyses. Isomorphous complexes 1 and 2 reveal polycatenated 2D+2D→3D framework based on an undulated (4,4)-sql layer. Complex 3 exhibits a new 4-fold interpenetrating 3D framework with the point symbol of 6{sup 6}. Molecular simulations were used to assess the potentials of the complexes for H{sub 2} storage application. Moreover, these coordination polymers exhibit blue fluorescent emission bands in the solid state at room temperature. - Graphical abstract: In this study, hydrothermal reactions of rigid 1,4-bis(imidazol-1-yl)benzene (dib) and 1,4-bis(imidazol-1-yl)-2,5-dimethylbenzene (dimb) with deprotonated thiophene-2,5-dicarboxylic acid (H{sub 2}tdc) in the presence of Zn(II) and Cd(II) salts in H{sub 2}O produced three new metal–organic frameworks. Isomorphous complexes 1 and 2 reveal polycatenated 2D+2D→3D framework based on an undulated (4,4)-sql layer. Complex 3 exhibits a new 4-fold interpenetrating 3D framework with the point symbol of 6{sup 6}. Molecular simulations were used to assess the potentials of the complexes for H{sub 2} storage application. These coordination polymers exhibit blue fluorescent emission bands in the solid state at room temperature. Display Omitted - Highlights: • Complexes 1 and 2 display polycatenated 2D+2D→3D framework. • Complex 3 exhibits a new 4-fold interpenetrating 3D framework. • Complex 1 adsorbs the highest amount of

  12. Di- versus Trinuclear Copper(II) Cryptate for the Uptake of Dicarboxylate Anions.

    PubMed

    Esteves, Catarina V; Mateus, Pedro; André, Vânia; Bandeira, Nuno A G; Calhorda, Maria José; Ferreira, Liliana P; Delgado, Rita

    2016-07-18

    Searching for receptors selective for the binding of dicarboxylate anions, the copper(II) complexes of the known ditopic octaazacryptand (t2pN8), derived from bistren [tren = tris(2-aminoethyl)amine] linked by p-xylyl spacers, were re-examined, with the expectation of observing a selective binding of oxalate or malonate by bridging the two copper centers of the [Cu2(t2pN8)(H2O)2](4+) receptor. Solution studies involving the supramolecular species formed by the receptor and oxalate (oxa(2-)), malonate (mal(2-)), and succinate (suc(2-)) anions are reported. The determined association constants revealed the unexpected formation of a 3:1:1 Cu/t2pN8/anion stoichiometry for the cascade species with oxa(2-) and mal(2-), and the single crystal X-ray structural characterization confirmed the presence of tricopper(II) complexes, with an unusual binding mode for the dicarboxylate anions. Each of the two copper atoms binds four nitrogen donor atoms of the t2pN8 cryptand and one additional hydroxide group, which bridges to the third copper. The square planar environment of this one is complete with two oxygen atoms from the oxalate (or the malonate). The two copper centers bound to the tren heads are ∼6.5 Å apart, each one at about 3.5 Å from the third Cu center. These studies were complemented by SQUID magnetization measurements and DFT calculations. The magnetic susceptibility measurements of the oxalate cascade complex showed a strong magnetic coupling (J = - 210 cm(-1)) between the Cu centers at a short distance (3.5 Å), while the coupling between the two equivalent Cu atoms (∼6.5 Å) was only -70 cm(-1). This result was well reproduced by DFT calculations.

  13. [Compositions of organic acids in PM10 emission sources in Xiamen urban atmosphere].

    PubMed

    Yang, Bing-Yu; Huang, Xing-Xing; Zheng, An; Liu, Bi-Lian; Wu, Shui-Ping

    2013-01-01

    The possible organic acid emission sources in PM10 in Xiamen urban atmosphere such as cooking, biomass burning, vehicle exhaust and soil/dust were obtained using a re-suspension test chamber. A total of 15 organic acids including dicarboxylic acids, fatty acids and aromatic acids were determined using GC/MS after derivatization with BF3/n-butanol. The results showed that the highest total concentration of 15 organic acids (53%) was found in cooking emission and the average concentration of the sum of linoleic acid and oleic acid was 24% +/- 14%. However, oxalic acid was the most abundant species followed by phthalic acid in gasoline vehicle exhaust. The ratios of adipic to azelaic acid in gasoline combustion emissions were significantly higher than those in other emission sources, which can be used to qualitatively differentiate anthropogenic and biological source of dicarboxylic acids in atmospheric samples. The ratios of malonic to succinic acid in source emissions (except gasoline generator emissions) were lower (0.07-0.44) than ambient PM10 samples (0.61-3.93), which can be used to qualitatively differentiate the primary source and the secondary source of dicarboxylic acids in urban PM10.

  14. Zn(II) coordination polymers with flexible V-shaped dicarboxylate ligand: Syntheses, helical structures and properties

    SciTech Connect

    Li, Lin; Liu, Chong-Bo; Yang, Gao-Shan; Xiong, Zhi-Qiang; Liu, Hong; Wen, Hui-Liang

    2015-11-15

    Hydrothermal reactions of 2,2′-[hexafluoroisopropylidenebis(p-phenyleneoxy)]diacetic acid (H{sub 2}L) and zinc ions in the presence of N-donor ancillary ligands afford four novel coordination polymers, namely, [Zn{sub 2}(μ{sub 2}-OH)(μ{sub 4}-O){sub 0.5}(L)]·0.5H{sub 2}O (1), [Zn(L)(2,2′-bipy)(H{sub 2}O)] (2), [Zn{sub 3}(L){sub 3}(phen){sub 2}]·H{sub 2}O (3) and [Zn{sub 2}(L){sub 2}(4,4′-bipy)] (4) (2,2′-bipy=2,2′-bipyridine; 4,4′-bipy=4,4′-bipyridine; phen=1,10-phenanthroline). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses. Complex 1 shows a 3-D clover framework consisting of [Zn{sub 4}(µ{sub 4}-O)(µ{sub 2}-OH){sub 2}]{sup 4+} clusters, and exhibits a novel (3,8)-connected topological net with the Schläfli symbol of {3·4·5}{sub 2}{3"4·4"4·5"2·6"6·7"1"0·8"2}, and contains double-stranded and two kinds of meso-helices. 2 displays a helical chain structure, which is further extended via hydrogen bonds into a 3-D supramolecular structure with meso-helix chains. 3 displays a 2-D {4"4·6"2} parallelogram structure, which is further extended via hydrogen bonds into a 3-D supramolecular structure with single-stranded helical chains. 4 shows a 2-D {4"4·6"2} square structure with left- and right-handed helical chains. Moreover, the luminescent properties of 1–4 have been investigated. - Graphical abstract: Four new Zn(II) coordination polymers with helical structures based on flexible V-shaped dicarboxylate ligand have been synthesized and structurally characterized. Photoluminescent properties have been investigated. - Highlights: • Four novel Zn(II) coordination polymers with V-shaped ligand were characterized. • Complexes 1–4 show diverse intriguing helical characters. • Fluorescence properties of complexes 1–4 were investigated.

  15. Four novel frameworks built by imidazole-based dicarboxylate ligands: hydro(solvo)thermal synthesis, crystal structures, and properties.

    PubMed

    Zhang, Fuwei; Li, Zifeng; Ge, Tiezhu; Yao, Hongchang; Li, Gang; Lu, Huijie; Zhu, Yanyan

    2010-04-19

    Four novel complexes, {[Ni(4)(HEIDC)(4)(H(2)O)(8)].2H(2)O} (1), {[Mn(HEIDC)(4,4'-bipy)(0.5)(H(2)O)].H(2)O}(n) (2), [Mn(6)(EIDC)(4)(py)(H(2)O)(4)](n) (3), and {[Cd(2)(EIDC)(H(2)EIDC)(4,4'-bipy)(1.5)].H(2)O}(n) (4) (H(3)EIDC = 2-ethyl-1H-imidazole-4,5-dicarboxylic acid, 4,4'-bipy = 4,4'-bipyridine, and py = pyridine) have been hydro(solvo)thermally synthesized by fine control over synthetic conditions, such as solvent and pH value, and structurally characterized. It is shown through single-crystal X-ray diffractions that the ligands H(3)EIDC can be either singly, doubly, or triply deprotonated and can coordinate to Ni(II), Mn(II) or Cd(II) ions in mu(2) or mu(3) modes. Compound 1 is a zero-dimensional (0D) symmetrical tetranuclear molecular square. Compound 2 exhibits a two-dimensional (2D) sheet, in which alternate left- and right-handed helical chains are bridged by 4,4'-bipy linkages. Compound 3 assumes a 2D honeycomb-like sheet built up from mu(3)-EIDC(3-) and Mn(II) atoms. Compound 4 possesses a novel three-dimensional (3D) structure constructed from 2D layer motifs joined by mu(2)-HEIDC(2-) and 4,4'-bipy bridges. The thermal properties of complexes 1-4 have been determined as well. Also, it is discovered that there exists antiferromagnetic coupling between the Ni(II) or Mn(II) ions in 1 or 2 (3); the best fittings to the experimental magnetic susceptibilities gave J = -10.83 cm(-1) and g = 2.19 for 1, and J = -0.025 cm(-1), zJ' = -0.02 cm(-1) and g = 2.0 for 2.

  16. Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part I. Regeneration of Amine-Carboxylic Acid Extracts

    SciTech Connect

    Poole, L.J.; King, C.J.

    1990-03-01

    Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO{sub 2} and H{sub 2}S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, succinic acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility of lactic acid and the tendency of the acid to self-associate. The separate recovery of ammonia and acid gases from sour waters can be achieved by combining steam-stripping of the acid gases with simultaneous removal of ammonia by extraction with a liquid cation exchanger. The use of di-2,4,4-trimethylpentyl phosphinic acid as the liquid cation exchanger is explored in this work. Batch extraction experiments were carried out to measure the equilibrium distribution ratio of ammonia between an aqueous buffer solution and an organic solution of the phosphinic acid (0.2N) in Norpar 12. The concentration

  17. Structural modulation and luminescent properties of four CdII coordination architectures based on 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole and flexible/rigid dicarboxylate ligands

    NASA Astrophysics Data System (ADS)

    Xia, Liang; Dong, Wen-Wen; Ye, Xiao; Zhao, Jun; Li, Dong-Sheng

    2016-10-01

    To systematically investigate the influence of the flexible or rigid auxiliary ligands on the structures and properties of transition metal compounds, we synthesized four new d10 coordination polymers (CPs) from 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole (4-Hpzpt) and flexible/rigid dicarboxylate ligands, [Cd(4-pzpt)2]n (1), [Cd3(4-pzpt)2(suc)2]n (2), [Cd2(4-Hpzpt)(nbc)2(H2O)]n (3) and {[Cd2(4-pzpt)2(tfbdc)(H2O)4]·H2O}n (4) (H2suc=1,2-ethanedicarboxylic acid, H2nbc=hthalene-1,4-dicarboxylic acid, H2tfbdc =2,3,5,6-tetrafluoroterephthalic acid). Single crystal X-ray analysis indicates that compound 1 shows a 44-sql layer, which is extended to a 3D network via nonclassical C-H…N hydrogen bonds. Compound 2 possesses a 6-connected pcu-4120.63 net composed of trinuclear CdII-clusters. Compound 3 represents a rare 3D (3,4,4,5)-connected topology with a Schläfli symbol of (4·6·7)(4·53·72)(53·6·7·9)(42·55·6·72). Compound 4 exhibits a 2D+2D→2D parallel interpenetrated 63-hcb network. The adjacent 2D networks are interdigitated with each other to form the resulting 3D supramolecular architecture through classical O-H…N and O-H…O hydrogen bonds. Structural diversities indicate that the nature of flexible/rigid-dicarboxlates plays crucial roles in modulating structures of these compounds. Moreover, the luminescent properties of them have been briefly investigated.

  18. Assembly and property research on seven 0D–3D complexes derived from imidazole dicarboxylate and 1,2-bi(pyridin-4-yl)ethene

    SciTech Connect

    Mu, Bao; Li, Qian; Lv, Lei; Yang, Dan-Dan; Wang, Qing; Huang, Ru-Dan

    2015-03-15

    The hydrothermal reaction of transition metals, 1H-imidazole-4,5-dicarboxylic acid (H{sub 3}ImDC) and 1,2-bi(pyridin-4-yl)ethene (bpe) affords a series of new complexes, namely, [Mn(HImDC)(bpe)(H{sub 2}O)] (1), [M(H{sub 2}ImDC){sub 2}(H{sub 2}O){sub 2}]·(bpe) (M=Fe(2), Co(3), Zn(4), Cd(6)), [Zn{sub 3}(ImDC){sub 2}(bpe)(H{sub 2}O)]·3H{sub 2}O (5) and [Cd(H{sub 2}ImDC)(bpe)] (7), which are characterized by elemental analyses, IR, TG, XRPD and single crystal X-ray diffraction. Complex 1 exhibits a one dimensional (1D) zigzag chain with two types of irregular rings, and the 1D chains are linked to form a three dimensional (3D) supramolecular framework by the hydrogen bonding interactions (O–H∙∙∙O and O–H∙∙∙N). Complexes 2–4 and 6 are isomorphous, and they display the mononuclear structures. In these complexes, the O–H∙∙∙O and O–H∙∙∙N hydrogen bonds play an important role in sustaining the whole 3D supramolecular frameworks. Complex 5 shows a (3,3)-connected 3D framework with (10{sup 3}) topology, and the lattice water molecules as guest molecules exist in the 3D framework. Complex 7 is a wave-like two dimensional (2D) structure, in which the adjacent 1D chains point at the opposite directions. Moreover, the fluorescent properties of complexes 1–7 and the magnetic property of 1 have been investigated. The water vapor adsorption for complex 5 has been researched at 298 K. - Graphical abstract: Seven new complexes based on different structural characteristics have been hydrothermally synthesized by the mixed ligands. The fluorescent properties, the magnetic property and the water vapor adsorption have been investigated. - Highlights: • The semi-rigid ligand with C=C bonds and imidazole dicarboxylates with some advantages have been used. • A series of new complexes with different structural characteristics have been discussed in detail. • The fluorescent properties, the magnetic property and the water vapor adsorption have been

  19. Uptake of 4-chloro-2-methylphenoxyacetic acid (MCPA) from the apical membrane of Caco-2 cells by the monocarboxylic acid transporter

    SciTech Connect

    Kimura, Osamu; Tsukagoshi, Kensuke; Endo, Tetsuya

    2008-03-15

    The cellular uptake mechanism of 4-chloro-2-methylphenoxyacetic acid (MCPA), a phenoxyacetic acid derivative, was investigated using Caco-2 epithelial cells. The cells were incubated with 50 {mu}M MCPA at pH 6.0 and 37 deg. C, and the uptake of MCPA from the apical membranes was measured. The uptake of MCPA was significantly decreased by incubation at low temperature (4 {sup o}C) and markedly increased by lowering the extracellular pH. Pretreatment with a protonophore, carbonylcyanide-p-(trifluoromethoxy)phenylhydrazone (25 {mu}M), or metabolic inhibitors, 2,4-dinitrophenol (1 mM) and sodium azide (10 mM), significantly decreased the uptake of MCPA by 53%, 45% and 48%, respectively. Coincubation of MCPA with 10 mM L-lactic acid or {alpha}-cyano-4-hydroxycinnamate, which is a substrate or an inhibitor of the monocarboxylic acid transporters (MCTs), significantly decreased the uptake of MCPA by 31% and 20%, respectively, and coincubation with benzoic acid profoundly decreased the uptake by 68%. In contrast, coincubation with succinic acid (a dicarboxylic acid) did not affect the uptake. Kinetic analysis of initial MCPA uptake suggested that MCPA is taken up via a carrier-mediated process [K{sub m} = 1.37 {+-} 0.15 mM, V{sub max} = 115 {+-} 6 nmol (mg protein){sup -1} (3 min){sup -1}]. Lineweaver-Burk plots show that benzoic acid competitively inhibits the uptake of MCPA with a K{sub i} value of 4.68 {+-} 1.76 mM. A trans-stimulation effect on MCPA uptake was found in cells preloaded with benzoic acid. These results suggest that the uptake of MCPA from the apical membrane of Caco-2 cells is mainly mediated by common MCTs along with benzoic acid but also in part by L-lactic acid.

  20. The thermal stability of organic acids in sedimentary basins

    SciTech Connect

    Crossey, L.J. )

    1991-03-01

    Water-soluble organic compounds in subsurface brines directly affect the evolution of porosity and permeability during sedimentary diagenesis. Recent examination of the aqueous thermal degradation of oxalic acid (a naturally occurring dicarboxylic acid) and its anions has implications for the thermal stability of dicarboxylic acids under sedimentary basin conditions. Because the thermal stability of these compounds is pH-dependent, consideration of the dissociation behavior of carboxylic acids as a function of temperature is essential for estimating the longevity of difunctional carboxylic acids. Results of burial history models suggest that dicarboxylic acid species may be long-lived in formation waters. Comparison with other experimental studies of carboxylic acids and their anion indicates that acetate stability is greater than formate stability, which is greater than oxalate stability, which is greater than gallate and malonate stability. In addition to the implications of natural systems, the aqueous degradation behavior is critical in evaluating other types of experimental results; notably mineral dissolution studies performed at elevated temperatures in the presence of organic materials and hydrous pyrolysis experiments involving kerogens.

  1. Syntheses, structures and properties of three metal-organic complexes containing 2,2‧-dipyridyl-5,5‧-dicarboxylate ligands

    NASA Astrophysics Data System (ADS)

    Liu, Jiancai; Zhang, Yudong; Shang, Sensen; Li, Yanzhou; Chen, Lijuan; Zhao, Junwei

    2015-01-01

    Three new metal-organic complexes Cu[Hbpdc]2 (1), [Ni(bpdc)(H2O)]·H2O (2) and [Ni(H2bpdc)(H2O)2]SO4 (3) (H2bpdc=2,2‧-bipyridyl-5,5‧-dicarboxylic acid) have been hydrothermally prepared and structurally characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. 1 is a 3-D supramolecular architecture formed by hydrogen bonding interactions between carboxyl O atoms and strong face-to-face π⋯π stacking interactions between bipyridyl rings of Hbpdc- ligands, 2 exhibits an intriguing 2-D sheet constructed from [Ni(bpdc)(H2O)] units and 3 displays an infinite 1-D chain built by {[Ni(H2bpdc)(H2O)2]2+} fragments through SO42-. Moreover, thermogravimetric (TG) and derivative thermogravimetric (DTG) analyses of 3 have been conducted and the TG curve shows two-stage weight loss between 300 and 950 K and the corresponding apparent activation energies are calculated by Ozawa-Flynn-Wall (OFW) method and Friedman method. The most probable kinetic model function of the dehydration reaction of 3 has been estimated by Coats-Redfern integral method and Achar-Bridly-Sharp differential method.

  2. Highly sensitive optical sensor that detects Hg2+ and Cu2+ by immobilizing dicarboxylate 1,5-diphenyl-3-thiocarbazone on surface functionalized PVA microspheres

    NASA Astrophysics Data System (ADS)

    Bai, Xue; Gu, Haixin; Hua, Zulin; Dai, Zhangyan; Yang, Bei; Li, Yulong

    2015-11-01

    A novel optical sensor to detect Hg2+ and Cu2+ is prepared by immobilizing a synthesized dicarboxylate 1,5-diphenyl-3-thiocarbazone (DDT) group on functionalized polyvinyl alcohol (PVA) microspheres. This optical sensor is successfully fabricated by extensive characterization with Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Its colorimetric properties, selectivity, sensitivity, and reversibility are investigated as well. In this sensing system, DDT-PVA selectively recognized multiple heavy metal ions, as indicated by the changes in color from orange to scarlet for Hg2+ and from orange to gray for Cu2+. In particular, this optical sensor exhibits the most apparent color changes at pH levels of 12 and 2. Hence, Hg2+ and Cu2+ can be detected in aqueous solution at minimum detection limits of 0.053 and 0.132 μM, respectively, with a UV-vis spectrometer. Furthermore, the sensor can be regenerated by ethylene diamine tetraacetic acid and reused several times. Therefore, the optical sensor can detect Hg2+ because of its selectivity, sensitivity, and reversibility.

  3. Palladium Complexes with the Tridentate Dianionic Ligand Pyridine-2,6-dicarboxylate, dipic. Crystal Structure of [Pd(dipic)(PBu(3))](2).

    PubMed

    Espinet, Pablo; Miguel, Jesús A.; García-Granda, Santiago; Miguel, Daniel

    1996-04-10

    The reactions of [Pd(acac)(2)] or [Pd(OAc)(2)](3) with pyridine-2,6-dicarboxylic acid (H(2)dipic) in acetonitrile afford [Pd(dipic)(NCMe)] in high yield. This complex has been used as starting material in the preparation of a variety of neutral an anionic complexes. The dipicolinate anion behaves as a tridentate ligand in all cases, but two modes of coordination are found, depending on the ligand: as a pincer ligand O,N,O-bonded to the same palladium, giving mononuclear complexes, and as an O,N-chelate N,O'-bridging ligand in dinuclear complexes. An X-ray determination of the structure of a dimer, [Pd(dipic)(PBu(3))](2) (monoclinic, space group P2(1)/n, a = 18.144(4) Å, b = 13.191(2) Å, c = 19.571(3) Å, beta = 113.45(2) degrees, Z = 4, R = 0.050, R(w) = 0.054) shows that the ligand is coordinated to one palladium in a eta(2)-N,O chelate fashion and one oxygen atom of the other carboxylate group makes a bridge to the other palladium atom, in a novel bonding mode for the dipic ligand.

  4. Lanthanide-Potassium Biphenyl-3,3'-disulfonyl-4,4'-dicarboxylate Frameworks: Gas Sorption, Proton Conductivity, and Luminescent Sensing of Metal Ions.

    PubMed

    Zhou, Li-Juan; Deng, Wei-Hua; Wang, Yu-Ling; Xu, Gang; Yin, Shun-Gao; Liu, Qing-Yan

    2016-06-20

    A novel sulfonate-carboxylate ligand of biphenyl-3,3'-disulfonyl-4,4'-dicarboxylic acid (H4-BPDSDC) and its lanthanide-organic frameworks {[LnK(BPDSDC)(DMF)(H2O)]·x(solvent)}n (JXNU-2, where JXNU denotes Jiangxi Normal University, DMF indicates dimethylformamide, and Ln = Sm(3+), Eu(3+), and Pr(3+)) were synthesized and structurally characterized. The three isomorphous lanthanide compounds feature three-dimensional frameworks constructed from one-dimensional (1D) rod-shaped heterometallic Ln-K secondary building units and are an illustration of a Kagome-like lattice with large 1D hexagonal channels and small 1D trigonal channels. The porous material of the representive JXNU-2(Sm) has an affinity to quadrupolar molecules such as CO2 and C2H2. In addition, the JXNU-2(Sm) compound exhibits humidity- and temperature-dependent proton conductivity with a large value of 1.11 × 10(-3) S cm(-1) at 80 °C and 98% relative humidity. The hydrophilic sulfonate group on the surface of channels facilitates enrichment of the solvate water molecules in the channels, which enhances the proton conductivity of this material. Moreover, the JXNU-2(Eu) material with the characteristic bright red color shows the potential for recognition of K(+) and Fe(3+) ions. The enhancing Eu(3+) luminescence with the K(+) ion and quenching Eu(3+) luminescence with the Fe(3+) ion can be associated with the functional groups of the organic ligand.

  5. Oxidant and acid aerosol exposure in healthy subjects and subjects with asthma. Part 1. Effects of oxidants, combined with sulfuric or nitric acid, on the pulmonary function of adolescents with asthma. Part 2. Effects of sequential sulfuric acid and ozone exposures on the pulmonary function of healthy subjects and subjects with asthma. Research report, February 1989-April 1994

    SciTech Connect

    Koenig, J.Q.; Covert, D.S.; Pierson, W.E.; Hanley, Q.S.; Rebolledo, V.

    1994-11-01

    The study investigated the pulmonary effects of acid summer haze in a controlled laboratory setting. Of 28 adolescent subjects with allergic asthma, exercise-induced bronchospasm, and a positive response to a standardized methacholine challenge enrolled in the study, 22 completed the study. For two consecutive days each subject inhaled each of four test atmospheres by mouthpiece. The order of exposure to the four test atmospheres was assigned via a random protocol; air, oxidants (0.12 parts per million (ppm) ozone plus 0.30 ppm nitrogen dioxide), oxidants plus sulfuric acid at 70 micro/m3 of air, or oxidants plus 0.05 ppm nitric acid. Exposure to each of the different atmospheres was separated by at least one week. A postexposure methacholine challenge was performed on Day 3.

  6. By-products of electrochemical synthesis of suberic acid

    SciTech Connect

    Shirobokova, O.I.; Adamov, A.A.; Freidlin, G.N.; Antonenko, N.S.; Grudtsyn, Yu.D.

    1988-05-10

    By-products of the electrochemical synthesis of dimethyl suberate from glutaric anhydride were studied. This is isolated by thermal dehydration of a mixture of lower dicarboxylic acids that are wastes from the production of adipic acid. To isolate the by-products, they used the methods of vacuum rectification and preparative gas-liquid chromatography, and for their identification, PMR, IR spectroscopy, gas-liquid chromatography, and other known physicochemical methods of investigation.

  7. Food Waste Fermentation to Fumaric Acid by Rhizopus arrhizus RH7-13.

    PubMed

    Liu, Huan; Ma, Jingyuan; Wang, Meng; Wang, Weinan; Deng, Li; Nie, Kaili; Yue, Xuemin; Wang, Fang; Tan, Tianwei

    2016-12-01

    Fumaric acid as a four-carbon unsaturated dicarboxylic acid is widely used in the food and chemical industries. Food waste (FW), rich in carbohydrates and protein, is a promising potential feedstock for renewable bio-based chemicals. In this research, we investigated the capability of Rhizopus arrhizus RH7-13 in producing fumaric acid from FW. The liquid fraction of the FW (L-FW) was proven to be the best seed culture medium in our research. When it was however used to be fermentation medium, the yield of fumaric acid reached 32.68 g/L, at a volumetric production of 0.34 g/L h. The solid fraction of FW mixed with water (S-FW) could also be used as fermentation medium when a certain amount of glucose was added, and the yield of fumaric acid reached 31.26 g/L. The results indicated that both fractions of FW could be well utilized in fermentation process and it could replace a part of common carbon, nitrogen, and nutrient. The process has an application potential since reducing the costs of raw materials.

  8. Synthesis and biological activity of the calcium modulator (R) and (S)-3-methyl 5-pentyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate.

    PubMed

    Zhang, Bang-le; He, Wei; Shi, Xin; Huan, Meng-Lei; Huang, Qiu-Ju; Zhou, Si-Yuan

    2010-02-01

    An efficient total synthesis of (R) and (S)-3-methyl 5-pentyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate in high optical purities is reported. The useful step is the resolution of racemic 2, 6-dimethyl-5-methoxycarbonyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3-carboxylic acid by using commercially available Cinchona alkaloids cinchonidine and quinidine as the resolving agents. Under the optimum conditions, the optical purities for R- and S-enantiomers are extremely high (ee>99.5%). The further dihydropyridine receptor binding activity assay shows that the S-enantiomer is more potent than R-enantiomer both in rat cardiac (approximately 19 times) and cerebral cortex membrane (12 times).

  9. Synthesis and structural characterization of homochiral 2D coordination polymers of zinc and copper with conformationally flexible ditopic imidazolium-based dicarboxylate ligands.

    PubMed

    Nicasio, Antonio I; Montilla, Francisco; Álvarez, Eleuterio; Colodrero, Rosario P; Galindo, Agustín

    2017-01-03

    Different novel coordination polymers containing zinc, 1-4, and copper, 5-8, metals, connected via chiral imidazolium-based dicarboxylate ligands, [L(R)](-), were isolated by reaction between zinc acetate or copper acetate and enantiomerically pure HL(R) compounds. They were characterised and structurally identified by X-ray diffraction methods (single crystal and powder). These compounds are two-dimensional homochiral coordination polymers, [M(L(R))2]n, in which the metal ions are coordinated by the two carboxylate groups of [L(R)](-) anions in a general bridging monodentate μ(2)-κ(1)-O(1),κ(1)-O(3) fashion that afforded tetrahedral metal coordination environments for zinc, 1-4, and square planar for copper, 5-8, complexes. In all the compounds the 3D supramolecular architecture is constructed by non-covalent interactions between the hydrophobic parts (R groups) of the homochiral 2D coordination polymers and, in some cases, by weak C-HO non-classical hydrogen bonds that provided, in general, a dense crystal packing. DFT calculations on the [L(R)](-) anions confirmed their conformational flexibility as ditopic linkers and this fact makes possible the formation of different coordination polymers for four-coordinated metal centers. Preliminary studies on the Zn-catalyzed synthesis of chiral α-aminophosphonates were carried out and, unfortunately, no enantioselectivity was observed in these reactions.

  10. Sensing by the membrane-bound sensor kinase DcuS: exogenous versus endogenous sensing of C(4)-dicarboxylates in bacteria.

    PubMed

    Scheu, Patrick D; Kim, Ok Bin; Griesinger, Christian; Unden, Gottfried

    2010-09-01

    Bacteria are able to grow at the expense of both common (succinate, L-malate, fumarate and aspartate) and uncommon (L-tartrate and D-malate) C(4)-dicarboxylates, which are components of central metabolism. Two types of sensors/regulators responding to the C(4)-dicarboxylates function in Escherichia coli, Bacillus, Lactobacillus and related bacteria. The first type represents membrane-integral two-component systems, while the second includes cytoplasmic LysR-type transcriptional regulators. The difference in location and substrate specificity allows the exogenous induction of metabolic genes by common C(4)-dicarboxylates, and endogenous induction by uncommon C(4)-dicarboxylates. The two-component sensors, DcuS and CitA, are composed of an extracellular Per-Arnt-Sim (PAS) domain, two transmembrane helices, a cytoplasmic PAS and the kinase domain. The structures of the extracellular PAS domains of DcuS and CitA have been determined in the ligand-bound and the apo form. Binding of the ligand results in closing and compaction of the binding site, and the structural change gives rise to piston-type movement of the adjacent membrane-spanning helix-2, and signal transmission to the cytoplasmic side. For DcuS, a membrane-embedded construct has been developed that suggests (by experimentation and modeling) that plasticity of the cytoplasmic PAS domain is central to signal transduction from the membrane to the kinase. Sensor kinase DcuS of E. coli requires the C(4)-dicarboxylate transporters DctA or DcuB as co-sensors for function under aerobic and anaerobic conditions, respectively. DcuB contains a regulatory site that controls the function of DcuS and is independent from the transport region. Therefore, DcuS senses C(4)-dicarboxylates in two independent modes, responding to the effector concentration and the metabolic flux of extracellular C(4)-dicarboxylates.

  11. Synthesis, Structural Characterization, and Thermochemistry of Zinc Hydrogen Pyridine 2,6-Dicarboxylate

    NASA Astrophysics Data System (ADS)

    Zhong, Wen-Wen; Di, You-Ying; Yang, Wei-Wei

    2012-12-01

    Zinc hydrogen pyridine 2,6-dicarboxylate trihydrate (Zn(HDPC)2 · 3H2O) was synthesized. The composition and crystal structure of the complex were determined by chemical analysis, elemental analysis, and X-ray crystallography. Low-temperature heat capacities of the complex were measured with a small sample automated adiabatic calorimeter over the temperature range from 78 K to 379 K. The experimental heat capacities of the complex were fitted by the least-squares method, and a polynomial equation of experimental molar heat capacities versus reduced temperature was obtained. The smoothed molar heat capacities and thermodynamic functions of the complex relative to the standard reference temperature 298.15 K were calculated based on the fitted polynomial equation. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured by an isoperibol solution-reaction calorimeter. The enthalpy change of the synthesis reaction of the titled compound was calculated to be -(15.95 ± 0.43) kJ · mol-1. Eventually, the standard molar enthalpy of formation of the title complex was derived to be -(2582.60 ± 3.02) kJ · mol-1 by the Hess thermochemical cycle. In addition, the reliability of the designed thermochemical cycle was verified by UV-Vis spectroscopy.

  12. Photochemical cycling of iron mediated by dicarboxylates: special effect of malonate.

    PubMed

    Wang, Zhaohui; Chen, Xi; Ji, Hongwei; Ma, Wanhong; Chen, Chuncheng; Zhao, Jincai

    2010-01-01

    Photochemical redox cycling of iron coupled with oxidation of malonate (Mal) ligand has been investigated under conditions that are representative of atmospheric waters. Malonate exhibited significantly different characteristics from oxalate and other dicarboxylates (or monocarboxylates). Both strong chelating ability with Fe(III) and strong molar absorptivities, but much low efficiency of Fe(II) formation (Phi(Fe(II)) = 0.0022 +/- 0.0009, 300-366 nm) were observed for Fe(III)-Mal complexes (FMCs). Fe(III) speciation calculation indicated that Mal is capable of mediating the proportion between two photoactive species of Fe(III)-OH complexes and FMCs by changing the Mal concentration. Spin-trapping electron spin resonance (ESR) experiments proved the formation of both the (.)CH(2)COOH and (.)OH radicals at lower total Mal concentration ([Mal](T)), but only (.)CH(2)COOH at higher concentrations of malonate, providing strong evidence for competition between malonate and OH(-) and subsequent different photoreaction pathways. Once FMCs dominate the Fe(III) speciation, both photoproduction and photocatalyzed oxidation of Fe(II) will be greatly decelerated. There exists an induction period for both formation and decay of Fe(II) until Fe(III)(OH)(2+) species become the prevailing Fe(III) forms over FMCs as Mal ligand is depleted. A quenching mechanism of Mal in the Fe(II) photoproduction is proposed. The present study is meaningful to advance our understanding of iron cycling in acidified carbon-rich atmospheric waters.

  13. Flotation selectivity of novel alkyl dicarboxylate reagents for apatite-calcite separation.

    PubMed

    Karlkvist, Tommy; Patra, Anuttam; Rao, Kota Hanumantha; Bordes, Romain; Holmberg, Krister

    2015-05-01

    The investigation aims to demonstrate the conceptual thoughts behind developing mineral specific reagents for use in flotation of calcium containing ores. For this purpose, a series of dicarboxylate-based surfactants with varying distance between the carboxylate groups (one, two or three methylene groups) was synthesized. A surfactant with the same alkyl chain length but with only one carboxylate group was also synthesized and evaluated. The adsorption behavior of these new reagents on pure apatite and pure calcite surfaces was studied using Hallimond tube flotation, FTIR and ζ potential measurements. The relation between the adsorption behavior of a given surfactant at a specific mineral surface and its molecular structure over a range of concentrations and pH values, as well as the region of maximum recovery, was established. It was found that one of the reagents, with a specific distance between the carboxylate groups, was much more selective for a particular mineral surface than the other homologues. For example, out of the four compounds synthesized, only the one where the carboxylate groups were separated by a single methylene group floated apatite but not calcite, whereas calcite was efficiently floated with the monocarboxylic reagent, but not with the other reagents synthesized. This selective adsorption of a given surfactant to a particular mineral surface relative to other mineral surfaces as evidenced in the flotation studies was substantiated by ζ potential and infra-red spectroscopy data.

  14. Changes in total nitrogen and amino acid composition of New Zealand Undaria pinnatifida with growth, location and plant parts.

    PubMed

    Zhou, April Yongdong; Robertson, John; Hamid, Nazimah; Ma, Qianli; Lu, Jun

    2015-11-01

    Undaria pinnatifida is known as unwanted organism in New Zealand. However, Wakame is a traditional food made of U. pinnatifida, which is now cultured extensively in East Asia. Therefore, it is important to examine this introduced alga as a potential source of dietary protein for human consumption in New Zealand. This study determined total nitrogen content and amino acid profile of New Zealand U. pinnatifida harvested from the Marlborough Sounds on a monthly basis from June to November 2011. Total average nitrogen content and crude protein content was 21.02 mg/g dry weight and 13.1% of dry weight, respectively. The three most abundant amino acids that contributed to flavour (glutamic acid, aspartic acid and alanine) were present and the most abundant essential amino acids were arginine, leucine, lysine and valine. The results showed that the amino acid content in blades from the exposed farm was significantly higher (P < 0.05) than the others. Sporophyll maturation of U. pinnatifida in New Zealand influenced protein content and amino acid composition. Sporophyll, considered as a waste product by many, was found to be a potentially good source of protein.

  15. Fluorescent sensing and electrocatalytic properties of three Zn(II)/Co(II) coordination complexes containing two different dicarboxylates and two various bis(pyridyl)-bis(amide) ligands

    NASA Astrophysics Data System (ADS)

    Lin, Hongyan; Rong, Xing; Liu, Guocheng; Wang, Xiang; Wang, Xiuli; Duan, Surui

    2016-09-01

    Three new transition metal(II) coordination complexes constructed from two different dicarboxylates (1,3-H2BDC = 1,3-benzenedicarboxylic acid, 1,4-H2NDC = 1,4-naphthalenedicarboxylic acid) and two bis(pyridyl)-bis(amide) ligands (3-bpcd = N,N‧-bis(3-pyridyl)cyclohexane-1,4-dicarboxamide, 3-bpod = N,N‧-bis(3-pyridyl)octandiamide), [Zn(1,3-BDC)(3-bpcd)0.5(H2O)]·H2O (1), [Zn(1,3-BDC)(3-bpod)0.5(H2O)] (2) and [Co(1,4-NDC)(3-bpod)1.5(H2O)] (3) have been synthesized in the hydrothermal environments and structurally characterized by IR, TG and single crystal X-ray diffraction. Complexes 1 and 2 possess the similar 1D ladder-like chain based on [Zn(1,3-BDC)]n zigzag chain and the bidentate ligands 3-bpcd/or 3-bpod. Complex 3 shows a 2D layered structure with a 5-connected {410} topology, which consists of 1D linear [Co(1,4-NDC)]n chain and [Co(3-bpod)1.5]n chain with alternating arrangement of 3-bpod ligands and Co2(3-bpod)2 dinuclear loops. The adjacent 1D chains for 1-2 or the 2D layers for 3 are further extended into 2D or 3D supramolecular frameworks through the hydrogen bonding interactions. Additionally, the solid state fluorescent properties for the title complexes 1-3, the fluorescent sensing behaviors of complexes 1-2 and the electrochemical behaviour of complex 3 have been investigated.

  16. Polymerization of beta-amino acids in aqueous solution

    NASA Technical Reports Server (NTRS)

    Liu, R.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1998-01-01

    We have compared carbonyl diimidazole (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as activating agents for the oligomerization of negatively-charged alpha- and beta-amino acids in homogeneous aqueous solution. alpha-Amino acids can be oligomerized efficiently using CDI, but not by EDAC. beta-Amino acids can be oligomerized efficiently using EDAC, but not by CDI. Aspartic acid, an alpha- and beta-dicarboxylic acid is oligomerized efficiently by both reagents. These results are explained in terms of the mechanisms of the reactions, and their relevance to prebiotic chemistry is discussed.

  17. Azelaic acid.

    PubMed

    Nazzaro-Porro, M

    1987-12-01

    This review is an update on the literature accumulated over the past 10 years following the original observation that azelaic acid, a naturally occurring and nontoxic C9 dicarboxylic acid, possesses significant biologic properties and a potential as a therapeutic agent. These studies have shown that azelaic acid is a reversible inhibitor of tyrosinase and other oxidoreductases in vitro and that it inhibits mitochondrial respiration. It can also inhibit anaerobic glycolysis. Both in vitro and in vivo it has an antimicrobial effect on both aerobic and anaerobic (Propionibacterium acnes) microorganisms. In tissue culture it exerts a dose- and time-dependent cytotoxic effect on malignant melanocytes, associated with mitochondrial damage and inhibition of deoxyribonucleic acid (DNA) synthesis. Tumoral cell lines not containing tyrosinase are equally affected. Normal cells in culture exposed to the same concentrations of the diacid that are toxic for tumoral cells are in general not damaged. Radioactive azelaic acid has been shown to penetrate tumoral cells at a higher level than normal cells of the corresponding line. Topically applied (a 20% cream), it has been shown to be of therapeutic value in skin disorders of different etiologies. Its beneficial effect on various forms of acne (comedogenic, papulopustular, nodulocystic) has been clearly demonstrated. Particularly important is its action on abnormal melanocytes, which has led to the possibility of obtaining good results on melasma and highly durable therapeutic responses on lentigo maligna. It is also capable of causing regression of cutaneous malignant melanoma, but its role in melanoma therapy remains to be investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Effects of lipids and oleic acid on biomass development in anaerobic fixed-bed reactors. Part II: Oleic acid toxicity and biodegradability.

    PubMed

    Alves, M M; Vieira, J A; Pereira, R M; Pereira, M A; Mota, M

    2001-01-01

    Oleic acid toxicity and biodegradability were followed during long-term operation of two similar anaerobic fixed-bed units. When treating an oleate based effluent, the sludge from the bioreactor that was acclimated with lipids during the first operation period, showed a higher tolerance to oleic acid toxicity (IC50 = 137 mg/l) compared with the sludge fed with a non-fat substrate (IC50 = 80 mg/l). This sludge showed also the highest biodegradation capacity of oleic acid, achieving maximum methane production rates between 33 and 46 mlCH4(STP)/gVS.day and maximum percentages of methanization between 85 and 98% for the range of concentrations between 500 and 900 mg oleate/l. When oleate was the sole carbon source fed to both digesters, the biomass became encapsulated with organic matter, possibly oleate or an intermediate of its degradation, e.g. stearate that was degraded at a maximum rate of 99 mlCH4(STP)/gVS.day. This suggests the possibility of using adsorption-degradation cycles for the treatment of LCFA based effluents. Both tolerance to toxicity and biodegradability of oleic acid were improved by acclimatization with lipids or oleate below a threshold concentration.

  19. Studies of the pulse charge of lead-acid batteries for PV applications. Part III. Electrolyte concentration effects on the electrochemical performance of the positive plate

    NASA Astrophysics Data System (ADS)

    Kirchev, A.; Delaille, A.; Karoui, F.; Perrin, M.; Lemaire, E.; Mattera, F.

    2008-05-01

    In the third part of this work the effects of the sulphuric acid concentration on the positive plate discharge capacity, impedance and oxygen overvoltage are discussed. It has been found that the full discharge capacity of the positive plate is available down to electrolyte concentrations of 3 mol l-1 (s.g. 1.18 g ml-1). At further acid dilution, capacity of the positive plate declines, keeping the utilization of the sulphuric acid about 50%. Decreasing the acid concentration, the oxygen overvoltage decreases with a factor of 12-18 mV M-1, excluding the effect of the equilibrium potential of the oxygen electrode as a function of pH. The capacitance of the electrical double layer decrease linearly with the dilution of the sulphuric acid suggesting strong adsorption effects. This suggestion has been confirmed from the measurements of potential of the zero charge of the positive plate, which increases from 1.11 to 1.34 V vs. Ag/Ag2SO4 in the region 1.11-4.60 M H2SO4. From the measurement of the time constant of the electronic transfer through the gel part of the lead dioxide (Tgel) as a function of the acid concentration and the applied potential, a change in the mechanism of the lead dioxide hydration has been estimated-below 1 M H2SO4Tgel increases sharply, showing sharp increases of the extent of the hydration. The dilution of the electrolyte increases substantially the value of average double layer current in the beginning of the charge. During the pulse overcharge at the employed frequency of 1 Hz, the average double layer current is equal to the pulse amplitude, suggesting that the maximal efficiency of the pulse charge is reached.

  20. Extraction of benzene and naphthalene carboxylic acids using quaternary ammonium salts as a model study for the separation of coal oxidation products

    SciTech Connect

    Kawamura, K.; Nagano, H.; Okuwaki, A.

    2005-07-01

    The ion-pair solvent extraction of benzene- and naphthalene-carboxylic acids has been investigated as a model study for the separation of coal oxidation products, which are formed by treatment with alkaline solutions at high temperatures. It was possible that benzene- and naphthalene-dicarboxylic acids are extracted into several types of organic solvents with quaternary ammonium ions. The extraction equilibrium constants (K{sub ex}) for benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1-naphthoic acid, 2-naphthoic acid, 2,3-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid into chloroform were determined at 20{sup o}C. The difference of K{sub ex} among the aromatic acids was sufficiently large for designing a separation method for these aromatic acids. It was unexpected that the extraction of dicarboxylic acids was slower than that of monocarboxylic acids, although the ion-pair formation of aromatic carboxylate ion with quaternary ammonium ion is normally considered as a diffusion control reaction in aqueous phase. Thus, this fact suggests that the phase transfer of the ion-pair from aqueous to organic phase is the rate-determining step. Liner-free-energy relationship was observed for the monocarboxylic acids using different quaternary ammonium salts while that was ambiguous for the dicarboxylic acids. This is due to the steric influence of the counter ions for the magnitude of K{sub ex}.

  1. Tunable Keplerate Type-Cluster "Mo132 " Cavity with Dicarboxylate Anions.

    PubMed

    Lai, Thanh-Loan; Awada, Mouhamad; Floquet, Sébastien; Roch-Marchal, Catherine; Watfa, Nancy; Marrot, Jérôme; Haouas, Mohamed; Taulelle, Francis; Cadot, Emmanuel

    2015-09-14

    The internal functionalization of the Keplerate-type capsule Mo132 has been carried out by ligand exchange leading to the formation of glutarate and succinate containing species isolated as ammonium or dimethylammonium salts. Solution NMR analysis is consistent with asymmetric inner dicarboxylate ions containing one carboxylato group grafted onto the inner side of the spheroidal inorganic shell while the second hangs toward the center of the cavity. Such a disposition has been confirmed by the single-crystal X-ray diffraction analysis of the glutarate containing {Mo132 } species. A detailed NMR solution study of the ligand-exchange process allowed determining the binding constant KL of acetate (AcO(-) ), succinate (HSucc(-) ) or glutarate (HGlu(-) ) ligands at the 30 inner coordinating sites, which vary such as K AcO -

  2. Alteration of organic matter during infaunal polychaete gut passage and links to sediment organic geochemistry. Part I: Amino acids

    NASA Astrophysics Data System (ADS)

    Woulds, Clare; Middelburg, Jack J.; Cowie, Greg L.

    2012-01-01

    Of the factors which control the quantity and composition of organic matter (OM) buried in marine sediments, the links between infaunal ingestion and gut passage and sediment geochemistry have received relatively little attention. This study aimed to use feeding experiments and novel isotope tracing techniques to quantify amino acid net accumulation and loss during polychaete gut passage, and to link this to patterns of selective preservation and decay in sediments. Microcosms containing either Arenicolamarina or Hediste (formerly Nereis) diversicolor were constructed from defaunated sediment and filtered estuarine water, and maintained under natural temperature and light conditions. They were fed with 13C-labelled diatoms daily for 8 days, and animals were transferred into fresh, un-labelled sediment after ∼20 days. Samples of fauna, microcosm sediment and faecal matter were collected after 8, ∼20 and ∼40 days, and analysed for their bulk isotopic signatures and 13C-labelled amino acid compositions. Bulk isotopic data showed that, consistent with their feeding modes, Hediste assimilated added 13C more quickly, and attained a higher labelling level than Arenicola. Both species retained the added 13C in their biomass even after removal from the food. A principal component analysis of 13C-labelled amino acid mole percentages showed clear differences in composition between the algae, faunal tissues, and sediment plus faecal matter. Further, the two species of polychaete showed different compositions in their tissues. The amino acids phenylalanine, valine, leucine, iso-leucine, threonine and proline showed net accumulation in polychaete tissues. Serine, methionine, lysine, aspartic and glutamic acids and tyrosine were rapidly lost through metabolism, consistent with their presence in easily digestible cell components (as opposed to cell walls which offer physical protection). All sample types (polychaete tissues, sediments and faecal matter) were enriched in

  3. Development of a New Antileishmanial Aziridine-2,3-Dicarboxylate-Based Inhibitor with High Selectivity for Parasite Cysteine Proteases

    PubMed Central

    Schad, Caroline; Baum, Ulrike; Frank, Benjamin; Dietzel, Uwe; Mattern, Felix; Gomes, Carlos; Ponte-Sucre, Alicia; Moll, Heidrun

    2015-01-01

    Leishmaniasis is one of the major neglected tropical diseases of the world. Druggable targets are the parasite cysteine proteases (CPs) of clan CA, family C1 (CAC1). In previous studies, we identified two peptidomimetic compounds, the aziridine-2,3-dicarboxylate compounds 13b and 13e, in a series of inhibitors of the cathepsin L (CL) subfamily of the papain clan CAC1. Both displayed antileishmanial activity in vitro while not showing cytotoxicity against host cells. In further investigations, the mode of action was characterized in Leishmania major. It was demonstrated that aziridines 13b and 13e mainly inhibited the parasitic cathepsin B (CB)-like CPC enzyme and, additionally, mammalian CL. Although these compounds induced cell death of Leishmania promastigotes and amastigotes in vitro, the induction of a proleishmanial T helper type 2 (Th2) response caused by host CL inhibition was observed in vivo. Therefore, we describe here the synthesis of a new library of more selective peptidomimetic aziridine-2,3-dicarboxylates discriminating between host and parasite CPs. The new compounds are based on 13b and 13e as lead structures. One of the most promising compounds of this series is compound s9, showing selective inhibition of the parasite CPs LmaCatB (a CB-like enzyme of L. major; also named L. major CPC) and LmCPB2.8 (a CL-like enzyme of Leishmania mexicana) while not affecting mammalian CL and CB. It displayed excellent leishmanicidal activities against L. major promastigotes (50% inhibitory concentration [IC50] = 37.4 μM) and amastigotes (IC50 = 2.3 μM). In summary, we demonstrate a new selective aziridine-2,3-dicarboxylate, compound s9, which might be a good candidate for future in vivo studies. PMID:26596939

  4. Water-deficit impact on fatty acid and essential oil composition and antioxidant activities of cumin (Cuminum cyminum L.) aerial parts.

    PubMed

    Bettaieb, Iness; Knioua, Sana; Hamrouni, Ibtissem; Limam, Ferid; Marzouk, Brahim

    2011-01-12

    This study is designed to examine the effect of water deficit on growth, fatty acid and essential oil composition, and antioxidant activities of Cuminum cyminum aerial part extracts. Plants were treated with different levels of water deficit: control (C), moderate water deficit (MWD), and severe water deficit (SWD). Plant growth (height, fresh and dry matter weights) as well as yield components were significantly increased under moderate water deficit and conversely reduced at severe level. Total fatty acid content decreased significantly with severity of constraint. Drought reduced considerably the proportions of major fatty acids and the unsaturated to saturated fatty acid ratio. The essential oil yield was 0.14% (based on the dry weight); it increased by 2.21-fold at MWD but decreased by 42.8% under SWD in comparison to the control. Drought results in the modification of the essential oil chemotype from 1-phenyl-1-butanol to 1-phenyl-1,2-ethanediol. Antioxidant activities of the acetone extracts were determined by two complementary test systems, namely, DPPH and β-carotene/linoleic acid. The highest activity was exhibited by moderately stressed plants and was reduced significantly under SWD. In control plants, the total phenolic amount was 10.23 mg GAE/g DW, which increased by 1.5-fold under MWD and decreased by 42% under SWD.

  5. Renal handling of terephthalic acid

    SciTech Connect

    Tremaine, L.M.; Quebbemann, A.J.

    1985-01-01

    By use of the Sperber in vivo chicken preparation method, infusion of radiolabeled terephthalic acid ((/sup 14/C)TPA) into the renal portal circulation revealed a first-pass excretion of the unchanged compound into the urine. This model was utilized further to characterize the excretory transport of (/sup 14/C)TPA and provide information on the structural specificity in the secretion of dicarboxylic acids. At an infusion rate of 0.4 nmol/min. 60% of the (/sup 14/C)TPA which reached the kidney was directly excreted. An infusion rate of 3 or 6 mumol/min resulted in complete removal of (/sup 14/C)TPA by the kidney. These results indicate that TPA is both actively secreted and actively reabsorbed when infused at 0.4 nmol/min and that active reabsorption is saturated with the infusion of TPA at higher concentrations. The secretory process was saturated with the infusion of TPA at 40 mumol/mn. The excretory transport of TPA was inhibited by the infusion of probenecid, salicylate, and m-hydroxybenzoic acid, indicating that these organic acids share the same organic anion excretory transport process. m-Hydroxybenzoic acid did not alter the simultaneously measured excretory transport of p-aminohippuric acid (PAH), suggesting that there are different systems involved in the secretion of TPA and PAH. The structural specificity for renal secretion of dicarboxylic acids was revealed by the use of o-phthalic acid and m-phthalic acid as possible inhibitors of TPA secretion.

  6. Compliance with revised acid rain monitoring requirements for gas and oil fired units: Appendix D and E of Part 75

    SciTech Connect

    Sheppard, M.; Culligan, K.

    1995-12-31

    EPA`s CEM rule (40 CFR Part 75) implements the monitoring provisions of Title IV of the Clean Air Act Amendments of 1990. In most cases Part 75 requires utilities to monitor sulfur dioxide (SO{sub 2}), nitrogen oxide (NO{sub x}) and carbon dioxide emissions (CO{sub 2}), and volumetric flow and opacity using Continuous Emissions Monitoring Systems (CEMS). Appendix D and E of 40 CFR Part 75 provide alternatives to using Continuous Emissions Monitoring Systems (CEMS) to comply with the monitoring requirements of Title IV of the Clean Air Act. EPA is considering a number of changes to Part 75, including significant changes to Appendix D and E. Part 75 was originally promulgated on January 11, 1993. Due to both experience gained in the implementation of Phase 1 and the early implementation of Phase 2 and petitions filed by several groups, EPA has prepared a number of changes to Part 75. This paper discusses what EPA anticipates these changes will be and how EPA anticipates that these changes will affect the regulated community. In addition, it discusses EPA`s expectations for certification applications for units using Appendix D and E.

  7. Rapid radiosynthesis of [11C] and [14C]azelaic, suberic, and sebacic acids for in vivo mechanistic studies of systemic acquired resistance in plants

    SciTech Connect

    Best M.; Fowler J.; Best, M.; Gifford, A.N.; Kim, S.W.; Babst, B.; Piel, M.; Roesch, F.; Fowler, J.S.

    2011-11-25

    A recent report that the aliphatic dicarboxylic acid, azelaic acid (1,9-nonanedioic acid) but not related acids, suberic acid (1,8-octanedioic acid) or sebacic (1,10-decanedioic acid) acid induces systemic acquired resistance to invading pathogens in plants stimulated the development of a rapid method for labeling these dicarboxylic acids with {sup 11}C and {sup 14}C for in vivo mechanistic studies in whole plants. {sup 11}C-labeling was performed by reaction of ammonium [{sup 11}C]cyanide with the corresponding bromonitrile precursor followed by hydrolysis with aqueous sodium hydroxide solution. Total synthesis time was 60 min. Median decay-corrected radiochemical yield for [{sup 11}C]azelaic acid was 40% relative to trapped [{sup 11}C]cyanide, and specific activity was 15 GBq/{micro}mol. Yields for [{sup 11}C]suberic and sebacic acids were similar. The {sup 14}C-labeled version of azelaic acid was prepared from potassium [{sup 14}C]cyanide in 45% overall radiochemical yield. Radiolabeling procedures were verified using {sup 13}C-labeling coupled with {sup 13}C-NMR and liquid chromatography-mass spectrometry analysis. The {sup 11}C and {sup 14}C-labeled azelaic acid and related dicarboxylic acids are expected to be of value in understanding the mode-of-action, transport, and fate of this putative signaling molecule in plants.

  8. Multiwavelength spectrophotometric determination of acid dissociation constants part V: microconstants and tautomeric ratios of diprotic amphoteric drugs.

    PubMed

    Takács-Novák, K; Tam, K Y

    2000-01-01

    The acid-base equilibria of several diprotic amphoteric drugs, namely, niflumic acid, norfloxacin, piroxicam, pyridoxine and 2-methyl-4-oxo-3H-quinazoline-3-acetic acid have been characterized in terms of microconstants and tautomeric ratios. A multiwavelength spectrophotometric (WApH) titration method for determination of acid dissociation constants (pKa values) of ionizable compounds developed previously was applied for this purpose. Microspeciation was investigated by three approaches: (1) selective monitoring of ionizable group by spectrophotometry, (2) deductive method and (3) k(z) method for determination of tautomeric ratio from co-solvent mixtures. The formulation for (3) has been derived and found to invoke fewer assumptions than a reported procedure (K. Takács-Novák, A. Avdeef, K.J Box, B. Podányi, G. Szász, J. Pharm. Biomed. Anal., 12 (1994) 1369-1377). It has been shown that the WApH technique, for such types of ampholytes, is able to deduce the microconstants and tautomeric ratios which are in good agreement with literature data.

  9. Molecular complexes of alprazolam with carboxylic acids, boric acid, boronic acids, and phenols. Evaluation of supramolecular heterosynthons mediated by a triazole ring.

    PubMed

    Varughese, Sunil; Azim, Yasser; Desiraju, Gautam R

    2010-09-01

    A series of molecular complexes, both co-crystals and salts, of a triazole drug-alprazolam-with carboxylic acids, boric acid, boronic acids, and phenols have been analyzed with respect to heterosynthons present in the crystal structures. In all cases, the triazole ring behaves as an efficient hydrogen bond acceptor with the acidic coformers. The hydrogen bond patterns exhibited with aromatic carboxylic acids were found to depend on the nature and position of the substituents. Being a strong acid, 2,6-dihydroxybenzoic acid forms a salt with alprazolam. With aliphatic dicarboxylic acids alprazolam forms hydrates and the water molecules play a central role in synthon formation and crystal packing. The triazole ring makes two distinct heterosynthons in the molecular complex with boric acid. Boronic acids and phenols form consistent hydrogen bond patterns, and these are seemingly independent of the substitutional effects. Boronic acids form noncentrosymmetric cyclic synthons, while phenols form O--H...N hydrogen bonds with the triazole ring.

  10. Poly[[dodeca-aqua-bis-(μ(3)-pyridine-2,6-dicarboxyl-ato)tetra-kis-(μ(2)-pyridine-2,6-dicarboxyl-ato)tri-calciumdieuropium(III)] 10.5-hydrate].

    PubMed

    Shi, Fengjuan; Deng, Jiguang; Dai, Hongxing

    2012-05-01

    In the title compound, {[Ca(3)Eu(2)(C(7)H(3)NO(4))(6)(H(2)O)(12)]·10.5H(2)O}(n), the Eu(III) ion is nine-coordinated by three tridentate pyridine-2,6-dicarboxyl-ate (PDA) ligands, forming a [Eu(PDA)(3)](3-) building block. The Ca(2+) ions adopt two types of coordination geometries. One Ca(2+) ion, lying on a twofold rotation axis, is eight-coordinated by four carboxyl-ate O atoms from four PDA ligands and four water mol-ecules, and the other two Ca(2+) ions, each lying on an inversion center, are six-coordinated by two carboxyl-ate O atoms from two PDA ligands and four water mol-ecules. The carboxyl-ate groups bridge the Eu(III) and Ca(2+) ions into a three-dimensional porous framework, with channels extending along [010] and [001] in which lattice water mol-ecules are located. Two of the lattice water mol-ecules are disordered over two sets of sites with equal occupancy and one water mol-ecule is 0.25-occupied. Numerous O-H⋯O hydrogen bonds involving the water mol-ecules and carboxyl-ate O atoms are present.

  11. Assignment of the gene coding for the human high-affinity glutamate transporter EAAC1 to 9p24: Potential role in dicarboxylic aminoaciduria and neurodegenerative disorders

    SciTech Connect

    Smith, C.P.; Kanai, Y.; Stelzner, M.; Hediger, M.A.; Weremowicz, S.; Morton, C.C. )

    1994-03-15

    Functional defects of high-affinity glutamate transporters have been implicated in the pathophysiology of neurodegenerative diseases such as amyotrophic lateral sclerosis. In small intestine and kidney, in which the high-affinity glutamate transporter mediates net absorption of glutamate and aspartate across epithelial cells, an inborn error of glutamate transport is thought to cause dicarboxylic aminoaciduria. This disorder is characterized by increased urinary excretion of glutamate and aspartate and is, in general, associated with neurologic and developmental abnormalities. Recently, the authors isolated a cDNA encoding a high-affinity glutamate transporter (EAAC1) that also transports aspartate but not other amino acids. EAAC1 is ubiquitously expressed throughout the body, particularly in brain (neurons), intestine, and kidney. Here, the authors present mapping of the chromosome location of EAAC1 using Southern analysis of a panel of human/rodent somatic cell hybrids and fluorescence in situ hybridization (FISH). Southern analysis of EcoRI-digested DNA gave bands at 6.5, 5.6, 5.1, and 1.2 kb for human genomic DNA; 7.5 kb for mouse genomic DNA; and 7.3, 3.2, and 1 kb for hamster genomic DNA. All four human EAAC1-specific bands were observed in the lane corresponding to the human/Chinese hamster hybrid containing chromosome 9 but not in lanes corresponding to any other hybrid. Because the human/Chinese hamster hybrid is the only one retaining chromosome 9, this result unambiguously assigns human EAAC1 to chromosome 9. For precise chromosome assignment of the human EAAC1 gene, they employed FISH. Map position of the EAAC1 probe was assigned by visual inspection of the fluorescent signal on the DAPI-stained metaphase chromosomes. The human EAAC1 gene was assigned to 9p24.

  12. Assembly and property research on seven 0D-3D complexes derived from imidazole dicarboxylate and 1,2-bi(pyridin-4-yl)ethene

    NASA Astrophysics Data System (ADS)

    Mu, Bao; Li, Qian; Lv, Lei; Yang, Dan-Dan; Wang, Qing; Huang, Ru-Dan

    2015-03-01

    The hydrothermal reaction of transition metals, 1H-imidazole-4,5-dicarboxylic acid (H3ImDC) and 1,2-bi(pyridin-4-yl)ethene (bpe) affords a series of new complexes, namely, [Mn(HImDC)(bpe)(H2O)] (1), [M(H2ImDC)2(H2O)2]·(bpe) (M=Fe(2), Co(3), Zn(4), Cd(6)), [Zn3(ImDC)2(bpe)(H2O)]·3H2O (5) and [Cd(H2ImDC)(bpe)] (7), which are characterized by elemental analyses, IR, TG, XRPD and single crystal X-ray diffraction. Complex 1 exhibits a one dimensional (1D) zigzag chain with two types of irregular rings, and the 1D chains are linked to form a three dimensional (3D) supramolecular framework by the hydrogen bonding interactions (O-H•••O and O-H•••N). Complexes 2-4 and 6 are isomorphous, and they display the mononuclear structures. In these complexes, the O-H•••O and O-H•••N hydrogen bonds play an important role in sustaining the whole 3D supramolecular frameworks. Complex 5 shows a (3,3)-connected 3D framework with (103) topology, and the lattice water molecules as guest molecules exist in the 3D framework. Complex 7 is a wave-like two dimensional (2D) structure, in which the adjacent 1D chains point at the opposite directions. Moreover, the fluorescent properties of complexes 1-7 and the magnetic property of 1 have been investigated. The water vapor adsorption for complex 5 has been researched at 298 K.

  13. Unravelling the effects of mobile phase additives in supercritical fluid chromatography. Part I: Polarity and acidity of the mobile phase.

    PubMed

    West, Caroline; Melin, Jodie; Ansouri, Hassna; Mengue Metogo, Maïly

    2017-04-07

    The mobile phases employed in current supercritical fluid chromatography (SFC) are usually composed of a mixture of pressurized carbon dioxide and a co-solvent. The co-solvent is most often an alcohol and may contain a third component in small proportions, called an additive (acid, base or salt). The polarity of such mobile phase compositions is here re-evaluated with a solvatochromic dye (Nile Red), particularly to assess the contribution of additives. It appears that additives, when employed in usual concentration range (0.1% or 20mM) do not modify the polarity in the immediate environment of the probe. In addition, the combination of carbon dioxide and an alcohol is known to form alkoxylcarbonic acid, supposedly conferring some acidic character to SFC mobile phases. Direct measurements of the apparent pH are impossible, but colour indicators of pH can be used to define the range of apparent pH provided by carbon dioxide-alcohol mixtures, with or without additives. Five colour indicators (Thymol Blue, Bromocresol Green, Methyl Red, Bromocresol Purple, and Bromothymol Blue) were selected to provide a wide range of aqueous pKa values (from 1.7 to 8.9). UV-vis absorption spectra measured in liquid phases of controlled pH were compared to those measured with a diode-array detector employed in SFC, with the help of chemometric methods. Based on these observations, it is concluded that the apparent pH range in carbon dioxide-methanol mobile phases is close to 5. Increasing the proportion of methanol (in the course of a gradient elution for instance) causes decreasing apparent pH. Strong acids can further decrease the apparent pH below 1.7; strong bases have little influence on the apparent pH, probably because, in this range of concentrations, they are titrated by alkoxylcarbonic acid or form ion pairs with alkoxycarbonate. However, bases and salts could stabilize the acidity in the course of gradient runs.

  14. Stable carbon isotopic compositions of organic acids in total suspended particles and dusts from Guangzhou, China

    NASA Astrophysics Data System (ADS)

    Ma, Shexia; Peng, Ping'an; Song, Jianzhong; Zhao, Jinping; He, Lulu; Sheng, Guoying; Fu, Jiamo

    2010-10-01

    Stable carbon isotopic compositions of individual organic acids were determined in total suspended particles and dusts from Guangzhou. The δ 13C values of high molecular weight n-alkanoic acids (C 20-C 28) varied from -34.1‰ to -32.4‰ and tended to be heavier in summer and lighter in winter. These δ 13C values indicate that high molecular weight n-alkanoic acids were derived mainly from emission by C 3 plants. Reduced biological synthesis of high molecular weight n-alkanoic acids in winter may be the reason for the light carbon isotopic composition. The δ 13C values of low molecular weight n-alkanoic acids (C 10-C 18) changed from -31.7‰ to -30.3‰ and exhibited a reverse seasonal trend, i.e., heavier in winter and lighter in summer. Slightly heavier δ 13C values of low molecular weight n-alkanoic acids than those of high molecular weight n-alkanoic acids suggested that they may be emitted from blended sources, e.g., anthropogenic sources and vegetation waxes. Lighter δ 13C values in summer may be attributed to relatively low anthropogenic sources and high botanic sources in summer. Dicarboxylic acids and aromatic acids have been proposed as secondary products from photochemical degradation. The average δ 13C values of dicarboxylic acids and aromatic acids were heavier, and ranged from -25.2‰ to -22.9‰ and from -30.0‰ to -27.6‰, respectively. Both dicarboxylic acids and aromatic acids displayed the same temporal variations in the δ 13C values, i.e., negative δ 13C in the summer samples and positive in the winter samples, which may be controlled by photochemical reactions; they are generally severe in winter in Guangzhou under the monsoon weather system. The heaviest δ 13C values were observed in dicarboxylic acids, indicating that dicarboxylic acids were formed by fast and more complete oxidation reactions. These results indicate that the stable carbon isotopic composition of organic acids may provide important information about sources and

  15. New cloud chamber experiments on the heterogeneous ice nucleation ability of oxalic acid in the deposition nucleation and immersion freezing modes

    NASA Astrophysics Data System (ADS)

    Moehler, O.; Wagner, R.; Saathoff, H.; Schnaiter, M.; Leisner, T.

    2010-12-01

    Dicarboxylic acids are ubiquitous components of the water-soluble organic fraction of the tropospheric aerosol. Their contribution to the total particulate organic carbon typically ranges from 1 - 3 wt% in urban and semi-urban areas to up to 10 wt% in remote marine atmospheres [1,2]. Oxalic acid, malonic acid, and succinic acid are usually the most abundant species, partly comprising more than 80% of the total diacid mass concentrations [3]. Several recent studies have addressed the ice nucleation potential of solid low-molecular weight dicarboxylic acids. On the one hand, the dicarboxylic acids can act as deposition mode ice nuclei provided that they are directly exposed to an ice supersaturated environment, e.g. in form of a coating layer that was formed by physical and chemical processing on prevalent particulates such as mineral dust and soot. At typical tropospheric relative humidities, diacids of low water solubility like oxalic and succinic acid may, on the other hand, also be present as solids that are immersed in aqueous inorganic and/or organic solution droplets [4,5]. These embedded crystals can act as ice nuclei in the immersion mode. Here we present new results from recent experiments at the aerosol and cloud chamber facility of the Karlsruhe Institute of Technology. The ice nucleation ability of aqueous and crystalline oxalic acid aerosol particles was investigated at expansion cooling conditions in the temperature range between 244 and 228 K [6]. Oxalic acid dihydrate particles with diameters between 0.03 to 0.8 μm, that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets, showed a high deposition mode ice activity at temperatures around 244 K. The ice onset humidity was below 110 % with respect to ice, and the ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles

  16. Defensive strategies in Geranium sylvaticum. Part 1: organ-specific distribution of water-soluble tannins, flavonoids and phenolic acids.

    PubMed

    Tuominen, Anu; Toivonen, Eija; Mutikainen, Pia; Salminen, Juha-Pekka

    2013-11-01

    A combination of high-resolution mass spectrometry and modern HPLC column technology, assisted by diode array detection, was used for accurate characterization of water-soluble polyphenolic compounds in the pistils, stamens, petals, sepals, stems, leaves, roots and seeds of Geranium sylvaticum. The organs contained a large variety of polyphenols, five types of tannins (ellagitannins, proanthocyanidins, gallotannins, galloyl glucoses and galloyl quinic acids) as well as flavonoids and simple phenolic acids. In all, 59 compounds were identified. Geraniin and other ellagitannins dominated in all the green photosynthetic organs. The other organs seem to produce distinctive polyphenol groups: pistils accumulated gallotannins; petals acetylglucose derivatives of galloylglucoses; stamens kaempferol glycosides, and seeds and roots accumulated proanthocyanidins. The intra-plant distribution of the different polyphenol groups may reflect the different functions and importance of various types of tannins as the defensive chemicals against herbivory.

  17. Oxidative degradation of organic acids conjugated with sulfite oxidation in flue-gas desulfurization. Final report, June 1984-June 1986

    SciTech Connect

    Lee, Y.J.; Rochelle, G.T.

    1988-02-01

    This report gives results of a study of organic acid-degradation conjugated with sulfite oxidation under flue-gas desulfurization (FGD) conditions. The oxidative degradation constant, k12, is defined as the ratio of organic-acid degradation rate and sulfite oxidation-rate times the ratio of the concentrations of dissolved S(IV) and organic acid. It is not significantly affected by pH or dissolved oxygen in the absence of Mn or Fe. However, k12 is increased by certain transition metals such as Fe, Co, and Ni and is decreased by Mn and halides. Lower dissolved S(IV) magnifies these effects. A free-radical mechanism was proposed to describe the kinetics. Hydroxy and sulfonated carboxylic acids degrade approximately three times slower than saturated dicarboxylic acids; while maleic acid, an unsaturated dicarboxylic acid, degraded an order of magnitude faster. A wide spectrum of degradation products of adipic acid were found, including carbon dioxide (the major product), smaller dicarboxylic acids, monocarboxylic acids, other carbonyl compounds, and hydrocarbons.

  18. Oxidative degradation of organic acid conjugated with sulfite oxidation in flue gas desulfurization: products, kinetics and mechanism

    SciTech Connect

    Lee, Y.J.; Rochelle, G.T.

    1987-03-01

    Organic acid degradation conjugated with sulfite oxidation has been studied under flue gas desulfurization (FGD) conditions. The oxidative degradation constant k/sub 12/ is defined as the ratio of organic acid degradation rate and sulfite oxidation rate times the ratio of the concentration of dissolved S(IV) and organic acid. It is not significantly affected by pH or dissolved oxygen in the absence of manganese or iron. However, k/sub 12/ is increased by certain transition metals such as Fe, Co, and Ni and is decreased by Mn and halides. Lower dissolved S(IV) magnifies these effects. A free radical mechanism was proposed to describe the kinetics. Hydroxy and sulfonated carboxylic acids degrade approximately 3 times slower than saturated dicarboxylic acids, while maleic acid, an unsaturated dicarboxylic acid, degraded an order of magnitude factor. A wide spectrum of degradation products of adipic acid were found, including carbon dioxide - the major product - smaller dicarboxylic acids, monocarboxylic acids, other carbonyl compounds, and hydrocarbons. 30 references, 7 figures, 7 tables.

  19. Application of high throughput pretreatment and co-hydrolysis system to thermochemical pretreatment. Part 1: dilute acid.

    PubMed

    Gao, Xiadi; Kumar, Rajeev; DeMartini, Jaclyn D; Li, Hongjia; Wyman, Charles E

    2013-03-01

    Because conventional approaches for evaluating sugar release from the coupled operations of pretreatment and enzymatic hydrolysis are extremely time and material intensive, high throughput (HT) pretreatment and enzymatic hydrolysis systems have become vital for screening large numbers of lignocellulosic biomass samples to identify feedstocks and/or processing conditions that significantly improve performance and lower costs. Because dilute acid pretreatment offers many important advantages in rendering biomass highly susceptible to subsequent enzymatic hydrolysis, a high throughput pretreatment and co-hydrolysis (HTPH) approach was extended to employ dilute acid as a tool to screen for enhanced performance. First, a single-step neutralization and buffering method was developed to allow effective enzymatic hydrolysis of the whole pretreated slurry. Switchgrass and poplar were then pretreated with 0.5% and 1% acid loadings at a 5% solids concentration, the resulting slurry conditioned with the buffering approach, and the entire mixture enzymatically hydrolyzed. The resulting sugar yields demonstrated that single-step neutralizing and buffering was capable of adjusting the pH as needed for enzymatic saccharification, as well as overcoming enzyme inhibition by compounds released in pretreatment. In addition, the effects of pretreatment conditions and biomass types on susceptibility of pretreated substrates to enzymatic conversion were clearly discernible, demonstrating the method to be a useful extension of HTPH systems.

  20. High temperature abatement of acid gases from waste incineration. Part I: experimental tests in full scale plants.

    PubMed

    Biganzoli, Laura; Racanella, Gaia; Rigamonti, Lucia; Marras, Roberto; Grosso, Mario

    2015-02-01

    In recent years, several waste-to-energy plants in Italy have experienced an increase of the concentration of acid gases (HCl, SO2 and HF) in the raw gas. This is likely an indirect effect of the progressive decrease of the amount of treated municipal waste, which is partially replaced by commercial waste. The latter is characterised by a higher variability of its chemical composition because of the different origins, with possible increase of the load of halogen elements such as chlorine (Cl) and fluorine (F), as well as of sulphur (S). A new dolomitic sorbent was then tested in four waste-to-energy plants during standard operation as a pre-cleaning stage, to be directly injected at high temperature in the combustion chamber. For a sorbent injection of about 6 kg per tonne of waste, the decrease of acid gases concentration downstream the boiler was in the range of 7-37% (mean 23%) for HCl, 34-95% (mean 71%) for SO2 and 39-80% (mean 63%) for HF. This pre-abatement of acid gases allowed to decrease the feeding rate of the traditional low temperature sorbent (sodium bicarbonate in all four plants) by about 30%. Furthermore, it was observed by the plant operators that the sorbent helps to keep the boiler surfaces cleaner, with a possible reduction of the fouling phenomena and a consequent increase of the specific energy production. A preliminary quantitative estimate was carried out in one of the four plants.

  1. Vascular effects of the Mediterranean diet-part II: role of omega-3 fatty acids and olive oil polyphenols.

    PubMed

    Scoditti, Egeria; Capurso, Cristiano; Capurso, Antonio; Massaro, Marika

    2014-12-01

    The lower occurrence of cardiovascular disease and cancer in populations around the Mediterranean basin as detected in the 1950s was correctly attributed to the peculiar dietary habits of those populations. Essentially, until the mid-20th century, typical Mediterranean diets were rich in fruits, vegetables, legumes, whole-wheat bread, nuts, fish, and, as a common culinary trait, the routine use of extra-virgin olive oil. Nowadays, the regular adoption of such dietary patterns is still thought to result in healthful benefits. Such patterns ensure the assumption of molecules with antioxidant and anti-inflammatory actions, among which ω-3 polyunsaturated fatty acids (PUFAs), ω-9 monounsaturated fatty acids (oleic acid), and phenolic compounds. The aim of this review is to provide an update of the vasculo-protective pathways mediated by ω-3 PUFAs and polyphenols in the context of the modern Mediterranean dietary habits, including the possible cross-talk and synergy between these typical components. This review complements a parallel one focusing on the role of dietary nitrates and alimentary fats.

  2. Ascorbic acid partly antagonizes resveratrol mediated heme oxygenase-1 but not paraoxonase-1 induction in cultured hepatocytes - role of the redox-regulated transcription factor Nrf2

    PubMed Central

    2011-01-01

    Background Both resveratrol and vitamin C (ascorbic acid) are frequently used in complementary and alternative medicine. However, little is known about the underlying mechanisms for potential health benefits of resveratrol and its interactions with ascorbic acid. Methods The antioxidant enzymes heme oxygenase-1 and paraoxonase-1 were analysed for their mRNA and protein levels in HUH7 liver cells treated with 10 and 25 μmol/l resveratrol in the absence and presence of 100 and 1000 μmol/l ascorbic acid. Additionally the transactivation of the transcription factor Nrf2 and paraoxonase-1 were determined by reporter gene assays. Results Here, we demonstrate that resveratrol induces the antioxidant enzymes heme oxygenase-1 and paraoxonase-1 in cultured hepatocytes. Heme oxygenase-1 induction by resveratrol was accompanied by an increase in Nrf2 transactivation. Resveratrol mediated Nrf2 transactivation as well as heme oxygenase-1 induction were partly antagonized by 1000 μmol/l ascorbic acid. Conclusions Unlike heme oxygenase-1 (which is highly regulated by Nrf2) paraoxonase-1 (which exhibits fewer ARE/Nrf2 binding sites in its promoter) induction by resveratrol was not counteracted by ascorbic acid. Addition of resveratrol to the cell culture medium produced relatively low levels of hydrogen peroxide which may be a positive hormetic redox-signal for Nrf2 dependent gene expression thereby driving heme oxygenase-1 induction. However, high concentrations of ascorbic acid manifold increased hydrogen peroxide production in the cell culture medium which may be a stress signal thereby disrupting the Nrf2 signalling pathway. PMID:21199573

  3. Ferromagnetic interactions through triple hydrogen bonds in the coordination polymers of alpha,alpha'-dihydroxy-bibenzyl-4,4'-dicarboxylate.

    PubMed

    Ma, Yu; Cheng, Ai-Ling; Gao, En-Qing

    2010-04-14

    Three transition metal coordination polymers with alpha,alpha'-dihydroxy-bibenzyl-4,4'-dicarboxylate (L) were synthesized, and structurally and magnetically characterized. The three compounds, formulated as [M(L)(H(2)O)(4)].2H(2)O (M = Co(ii), Mn(ii) and Ni(ii)), are isomorphic and consist of one-dimensional coordination chains formed by the dicarboxylate ligand bridging the metal ions using monodentate carboxylate groups. Intriguingly, the [M(COO)(2)(H(2)O)(4)] spheres from different coordination chains are linked through triple O-H...O bridges to give the rare hydrogen bonded chains with [M(O-H...O)(3)M] helicate motifs, which represent good systems suitable for investigating the exchange coupling through hydrogen bonding. Magnetic studies on Ni(ii) and Co(ii) compounds reveal that the triple hydrogen bonding bridge transmits ferromagnetic coupling, with J = 3.46 cm(-1) for the Ni(ii) compound and J = 1.12 cm(-1) for the Co(ii) compound.

  4. Monitoring the formation of carbide crystal phases during the thermal decomposition of 3d transition metal dicarboxylate complexes

    SciTech Connect

    Huba, ZJ; Carpenter, EE

    2014-06-06

    Single molecule precursors can help to simplify the synthesis of complex alloys by minimizing the amount of necessary starting reagents. However, single molecule precursors are time consuming to prepare with very few being commercially available. In this study, a simple precipitation method is used to prepare Fe, Co, and Ni fumarate and succinate complexes. These complexes were then thermally decomposed in an inert atmosphere to test their efficiency as single molecule precursors for the formation of metal carbide phases. Elevated temperature X-ray diffraction was used to identify the crystal phases produced upon decomposition of the metal dicarboxylate complexes. Thermogravimetric analysis coupled with an infrared detector was used to identify the developed gaseous decomposition products. All complexes tested showed a reduction from the starting M2+ oxidation state to the M oxidation state, upon decomposition. Also, each complex tested showed CO2 and H2O as gaseous decomposition products. Nickel succinate, iron succinate, and iron fumarate complexes were found to form carbide phases upon decomposition. This proves that transition metal dicarboxylate salts can be employed as efficient single molecule precursors for the formation of metal carbide crystal phases.

  5. Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases. Part 3: Michael addition reactions and miscellaneous transformations.

    PubMed

    Aceña, José Luis; Sorochinsky, Alexander E; Soloshonok, Vadim

    2014-09-01

    The major goal of this review is a critical discussion of the literature data on asymmetric synthesis of α-amino acids via Michael addition reactions involving Ni(II)-complexes of amino acids. The material covered is divided into two conceptually different groups dealing with applications of: (a) Ni(II)-complexes of glycine as C-nucleophiles and (b) Ni(II)-complexes of dehydroalanine as Michael acceptors. The first group is significantly larger and consequently subdivided into four chapters based on the source of stereocontrolling element. Thus, a chiral auxiliary can be used as a part of nucleophilic glycine Ni(II) complex, Michael acceptor or both, leading to the conditions of matching vs. mismatching stereochemical preferences. The particular focus of the review is made on the practical aspects of the methodology under discussion and mechanistic considerations.

  6. Dicarboxylate-controlled three Zn(II) coordination polymers incorporating flexible 1,2-bis(imidazol-1‧-yl)ethane ligand: Syntheses, structures, thermal stabilities and photoluminescent properties

    NASA Astrophysics Data System (ADS)

    Hao, Hong-Jun; Sun, Di; Liu, Fu-Jing; Huang, Rong-Bin; Zheng, Lan-Sun

    2012-03-01

    Three mixed-ligand Zn(II) coordination polymers (CPs) of the formula {[Zn2(bime)2(adip)2]ṡ(H2O)5}n (1), {[Zn(bime)(ipa)]ṡ(H2O)3}n (2), {[Zn(bime)(tpa)]ṡ(H2O)ṡ(CH3OH)}n (3) (bime = 1,2-bis(imidazol-1'-yl)ethane, H2adip = adipic acid, H2ipa = isophthalic acid and H2tpa = terephthalic acid) were synthesized. All CPs have been characterized by element analysis, powder X-ray diffraction (PXRD), IR and X-ray single-crystal diffraction. Complexes 1 and 2 exhibit similar wavy two-dimensional (2D) sheets with 44-sql topology. Compared to 1, complex 2 contains a larger window owing to the different conformation of bime ligand. In both 1 and 2, we observed 1D water chain filling in the 44-sql net. In 3, the bime acts as a bidentate ligand and the tpa adopts a μ2-η1,η1 coordinated mode which links the Zn(II) ions to form a 2D 63-hcb net. The results suggest that the dicarboxylates play crucial roles in the formation of the different structures. In addition, the thermal stabilities and the photoluminescence properties of them were also investigated.

  7. Discrete hexamer water clusters and 2D water layer trapped in three luminescent Ag/tetramethylpyrazine/benzene-dicarboxylate hosts: 1D chain, 2D layer and 3D network

    NASA Astrophysics Data System (ADS)

    Mei, Hong-Xin; Zhang, Ting; Huang, Hua-Qi; Huang, Rong-Bin; Zheng, Lan-Sun

    2016-03-01

    Three mix-ligand Ag(I) coordination compounds, namely, {[Ag10(tpyz) 5(L1) 5(H2 O)2].(H2 O)4}n (1, tpyz = 2,3,4,5-tetramethylpyrazine, H2 L1 = phthalic acid), [Ag4(tpyz) 2(L2) 2(H2 O)].(H2 O)5}n (2, H2 L2 = isophthalic acid) {[Ag2(tpyz) 2(L3) (H2 O)4].(H2 O)8}n (3, H2 L3 = terephthalic acid), have been synthesized and characterized by elemental analysis, IR, PXRD and X-ray single-crystal diffraction. 1 exhibits a 2D layer which can be simplified as a (4,4) net. 2 is a 3D network which can be simplified as a (3,3)-connected 2-nodal net with a point symbol of {102.12}{102}. 3 consists of linear [Ag(tpyz) (H2 O)2]n chain. Of particular interest, discrete hexamer water clusters were observed in 1 and 2, while a 2D L10(6) water layer exists in 3. The results suggest that the benzene dicarboxylates play pivotal roles in the formation of the different host architectures as well as different water aggregations. Moreover, thermogravimetric analysis (TGA) and emissive behaviors of these compounds were investigated.

  8. Computational study on the acidic constants of chiral Brønsted acids in dimethyl sulfoxide.

    PubMed

    Yang, Chen; Xue, Xiao-Song; Li, Xin; Cheng, Jin-Pei

    2014-05-16

    The pK(a) values of a series of chiral Brønsted acids, including N-triflylphosphoramides, bis(sulfonyl)imides, bis(sulfuryl)imides, dicarboxylic acids, sulfonic acids, and N-phosphinyl phosphoramides, were predicted by using the SMD/M06-2x/6-311++G(2df,2p)//B3LYP/6-31+G(d) method in DMSO. The results revealed that the calculated pKa values ranged from -9.06 to 12.18 for different types of acids. The influence of acidic strength on reactivity and stereoselectivity was discussed using the calculated acidity data. Given that the choice of catalyst with appropriate acidity is the primary condition, several new catalyst candidates were designed by calculating corresponding pK(a) values of parent acids.

  9. Chemical constituents of Malagasy liverworts, part II: mastigophoric acid methyl ester of biogenetic interest from Mastigophora diclados (Lepicoleaceae Subf. Mastigophoroideae).

    PubMed

    Harinantenaina, Liva; Asakawa, Yoshinori

    2004-11-01

    In the course of our chemotaxonomic study of the liverworts growing in Madagascar, mastigophoric acid methyl ester, along with eleven known compounds were isolated from Mastigophora diclados. Isolated metabolites showed that the Malagasy Mastigophora is more related to the samples from Borneo and Japan than to the Taiwanese or Malaysian ones. The biosynthesis of the herbertane type sesquiterpenoids from Mastigophora diclados is suggested to be similar to those found in the genus Herbertus. The herbertane-type sesquiterpenoids were screened for Staphylococcus aureus strain inhibition.

  10. Surface functionalization of bioactive glasses with natural molecules of biological significance, Part I: Gallic acid as model molecule

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Ferraris, Sara; Prenesti, Enrico; Verné, Enrica

    2013-12-01

    Gallic acid (3,4,5-trihydroxybenzoic acid, GA) and its derivatives are a group of biomolecules (polyphenols) obtained from plants. They have effects which are potentially beneficial to heath, for example they are antioxidant, anticarcinogenic and antibacterial, as recently investigated in many fields such as medicine, food and plant sciences. The main drawbacks of these molecules are both low stability and bioavailability. In this research work the opportunity to graft GA to bioactive glasses is investigated, in order to deliver the undamaged biological molecule into the body, using the biomaterial surfaces as a localized carrier. GA was considered for functionalization since it is a good model molecule for polyphenols and presents several interesting biological activities, like antibacterial, antioxidant and anticarcinogenic properties. Two different silica based bioactive glasses (SCNA and CEL2), with different reactivity, were employed as substrates. UV photometry combined with the Folin&Ciocalteu reagent was adopted to test the concentration of GA in uptake solution after functionalization. This test verified how much GA consumption occurred with surface modification and it was also used on solid samples to test the presence of GA on functionalized glasses. XPS and SEM-EDS techniques were employed to characterize the modification of material surface properties and functional group composition before and after functionalization.

  11. Fatty acids, coumarins and polyphenolic compounds of Ficus carica L. cv. Dottato: variation of bioactive compounds and biological activity of aerial parts.

    PubMed

    Marrelli, Mariangela; Statti, Giancarlo A; Tundis, Rosa; Menichini, Francesco; Conforti, Filomena

    2014-01-01

    Leaves, bark and woody part of Ficus carica L. cultivar Dottato collected in different months were examined to assess their chemical composition, antioxidant activity and phototoxicity on C32 human melanoma cells after UVA irradiation. The phytochemical investigation revealed different composition in the coumarin, fatty acid, polyphenol and flavonoid content. The second harvest of leaves and the first harvest of the bark possessed the highest antiradical activity with IC50 values of 64.00 ± 0.59 and 67.00 ± 1.09 μg/mL, respectively. Harvest III of leaves showed the best inhibition of lipid peroxidation (IC50 = 1.48 ± 0.04 μg/mL). Leaf samples of F. carica showed also the best antiproliferative activity in comparison with bark and woody part of F. carica.

  12. An enhanced procedure for measuring organic acids and methyl esters in PM2.5

    NASA Astrophysics Data System (ADS)

    Liu, F.; Duan, F.; He, K.; Ma, Y.; Rahn, K. A.; Zhang, Q.

    2015-03-01

    We have developed an enhanced analytical procedure to measure organic acids and methyl esters in fine aerosol with much greater specificity and sensitivity than previously available. This capability is important because of these species and their low concentrations, even in highly polluted atmospheres like Beijing, China. The procedure first separates the acids and esters from the other organic compounds with anion-exchange solid- phase extraction (SPE), then, quantifies them by gas chromatography coupled with mass spectrometry. This allows us to accurately quantify the C4-C11 dicarboxylic and the C8-C30 monocarboxylic acids. Then the acids are separated from the esters on an aminopropyl SPE cartridge, whose weak retention isolates and enriches the acids from esters prevents the fatty acids and dimethyl phthalate from being overestimated. The resulting correlations between the aliphatic acids and fatty acid methyl esters (FAMEs) suggest that FAMEs had sources similar to those of the carboxylic acids, or were formed by esterifying carboxylic acids, or that aliphatic acids were formed by hydrolyzing FAMEs. In all, 17 aromatic acids were identified and quantified using this procedure coupled with gas chromatography-tandem mass spectrometry, including the five polycyclic aromatic hydrocarbon (PAH) acids 2-naphthoic, biphenyl-4-carboxylic, 9-oxo-9H-fluorene-1-carboxylic, biphenyl-4,4´-dicarboxylic, and phenanthrene-1-carboxylic acid, plus 1,8-naphthalic anhydride. Correlations between the PAH-acids and the dicarboxylic and aromatic acids indicated that the first three acids and 1,8-naphthalic anhydride were mainly secondary, the last two mainly primary.

  13. Assembly of Cerium(III) 2,2'-Bipyridine-5,5'-dicarboxylate-based Metal–Organic Frameworks by Solvent Tuning

    SciTech Connect

    Ayhan, Ozan; Malaestean, Iurie L.; Ellern, Arkady; van Leusen, Jan; Baca, Svetlana G.; Kögerler, Paul

    2014-07-02

    Two cerium(III) 2,2'-bipyridine-5,5'-dicarboxylate-based 3D coordination networks highlight the ability of CeIII ions to adopt different coordination environments upon subtle changes to the reaction conditions, producing metal-organic frameworks that integrate varying crystal solvent contents.

  14. Site-specific ligation of anthracene-1,8-dicarboxylates to an Mn12 core: a route to the controlled functionalisation of single-molecule magnets.

    PubMed

    Pacchioni, Mirko; Cornia, Andrea; Fabretti, Antonio C; Zobbi, Laura; Bonacchi, Daniele; Caneschi, Andrea; Chastanet, Guillaume; Gatteschi, Dante; Sessoli, Roberta

    2004-11-21

    A novel single-molecule magnet of the Mn12 family, [Mn12O12(O2CC6H5)8(L)4(H2O)4].8CH2Cl2, has been synthesised by site-specific ligand exchange using a tailor-made dicarboxylate (L2-), which leads to selective occupation of axial binding sites.

  15. Rat liver microsomal lipid peroxidation produced during the oxidative metabolism of ethacrynic acid.

    PubMed

    Yamamoto, K; Masubuchi, Y; Narimatsu, S; Kobayashi, S; Horie, T

    2001-04-01

    Thiobarbituric acid reactive substances (TBARS) were produced in rat liver microsomal suspension incubated with ethacrynic acid (loop diuretic drug) and NADPH. Two oxidative metabolites of ethacrynic acid with dicarboxylic acid and hydroxylated ethyl group, respectively, were formed in the reaction mixture. The oxidative metabolism of ethacrynic acid was inhibited by cytochrome P450 inhibitors. The formation of TBARS was remarkably depressed by inhibitors like diethyldithiocarbamate and disulfiram. These results indicate that lipid peroxidation occurred in rat liver microsomes through the oxidative metabolism of ethacrynic acid.

  16. An Inorganic Microsphere Composite for the Selective Removal of Cesium 137 from Acidic Nuclear Waste Solutions - Parts 1 and 2

    SciTech Connect

    T. J. Tranter; T. A. Vereschchagina; V. Utgikar

    2009-03-01

    A new inorganic ion exchange composite for removing radioactive cesium from acidic waste streams has been developed. The new material consists of ammonium molybdophosphate, (NH4)3P(Mo3O10)4•3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP-C), which are produced as a by-product from coal combustion. The selective cesium exchange capacity of this inorganic composite was evaluated in bench-scale column tests using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Total cesium loading on the columns at saturation agreed very well with equilibrium values predicted from isotherm experiments performed previously. A numerical algorithm for solving the governing partial differential equations (PDE) for cesium uptake was developed using the intraparticle mass transfer coefficient obtained from previous batch kinetic experiments. Solutions to the governing equations were generated to obtain the cesium concentration at the column effluent as a function of throughput volume using the same conditions as those used for the actual column experiments. The numerical solutions of the PDE fit the column break through data quite well for all the experimental conditions in the study. The model should therefore provide a reliable prediction of column performance at larger scales. A new inorganic ion exchange composite consisting of ammonium molybdophosphate, (NH4)3P(Mo3O10)4•3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP-C) has been developed. Two different batches of the sorbent were produced resulting in 20% and 25% AMP loading for two and three loading cycles, respectively. The selective cesium exchange capacity of this inorganic composite was evaluated using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Equilibrium isotherms obtained from these experiments

  17. Organic matter in sediment layers of an acidic mining lake as assessed by lipid analysis. Part II: Neutral lipids.

    PubMed

    Poerschmann, Juergen; Koschorreck, Matthias; Górecki, Tadeusz

    2017-02-01

    Natural neutralization of acidic mining lakes is often limited by organic matter. The knowledge of the sources and degradability of organic matter is crucial for understanding alkalinity generation in these lakes. Sediments collected at different depths (surface sediment layer from 0 to 1 cm and deep sediment layer from 4 to 5cm) from an acidic mining lake were studied in order to characterize sedimentary organic matter based on neutral signature markers. Samples were exhaustively extracted, subjected to pre-chromatographic derivatizations and analyzed by GC/MS. Herein, molecular distributions of diagnostic alkanes/alkenes, terpenes/terpenoids, polycyclic aromatic hydrocarbons, aliphatic alcohols and ketones, sterols, and hopanes/hopanoids were addressed. Characterization of the contribution of natural vs. anthropogenic sources to the sedimentary organic matter in these extreme environments was then possible based on these distributions. With the exception of polycyclic aromatic hydrocarbons, combined concentrations across all marker classes proved higher in the surface sediment layer as compared to those in the deep sediment layer. Alkane and aliphatic alcohol distributions pointed to predominantly allochthonous over autochthonous contribution to sedimentary organic matter. Sterol patterns were dominated by phytosterols of terrestrial plants including stigmasterol and β-sitosterol. Hopanoid markers with the ββ-biohopanoid "biological" configuration were more abundant in the surface sediment layer, which pointed to higher bacterial activity. The pattern of polycyclic aromatic hydrocarbons pointed to prevailing anthropogenic input. Pyrolytic makers were likely to due to atmospheric deposition from a nearby former coal combustion facility. The combined analysis of the array of biomarkers provided new insights into the sources and transformations of organic matter in lake sediments.

  18. An enhanced procedure for measuring organic acids and methyl esters in PM2.5

    NASA Astrophysics Data System (ADS)

    Liu, F.; Duan, F. K.; He, K. B.; Ma, Y. L.; Rahn, K. A.; Zhang, Q.

    2015-11-01

    A solid-phase extraction (SPE) pretreatment procedure allowing organic acids to be separated from methyl esters in fine aerosol has been developed. The procedure first separates the organic acids from fatty acid methyl esters (FAMEs) and other nonacid organic compounds by aminopropyl-based SPE cartridge and then quantifies them by gas chromatography/mass spectrometry. The procedure prevents the fatty acids and dimethyl phthalate from being overestimated, and so allows us to accurately quantify the C4-C11 dicarboxylic acids (DCAs) and the C8-C30 monocarboxylic acids (MCAs). Results for the extraction of DCAs, MCAs, and AMAs in eluate and FAMEs in effluate by SAX and NH2 SPE cartridges exhibited that the NH2 SPE cartridge gave higher extraction efficiency than the SAX cartridge. The recoveries of analytes ranged from 67.5 to 111.3 %, and the RSD ranged from 0.7 to 10.9 %. The resulting correlations between the aliphatic acids and FAMEs suggest that the FAMEs had sources similar to those of the carboxylic acids, or were formed by esterifying carboxylic acids, or that aliphatic acids were formed by hydrolyzing FAMEs. Through extraction and cleanup using this procedure, 17 aromatic acids in eluate were identified and quantified by gas chromatography/tandem mass spectrometry, including five polycyclic aromatic hydrocarbon (PAH): acids 2-naphthoic, biphenyl-4-carboxylic, 9-oxo-9H-fluorene-1-carboxylic, biphenyl-4,4´-dicarboxylic, and phenanthrene-1-carboxylic acid, plus 1,8-naphthalic anhydride. Correlations between the PAH acids and the dicarboxylic and aromatic acids suggested that the first three acids and 1,8-naphthalic anhydride were secondary atmospheric photochemistry products and the last two mainly primary.

  19. Citric acid production from partly deproteinized whey under non-sterile culture conditions using immobilized cells of lactose-positive and cold-adapted Yarrowia lipolytica B9.

    PubMed

    Arslan, Nazli Pinar; Aydogan, Mehmet Nuri; Taskin, Mesut

    2016-08-10

    The present study was performed to produce citric acid (CA) from partly deproteinized cheese whey (DPCW) under non-sterile culture conditions using immobilized cells of the cold-adapted and lactose-positive yeast Yarrowia lipolytica B9. DPCW was prepared using the temperature treatment of 90°C for 15min. Sodium alginate was used as entrapping agent for cell immobilization. Optimum conditions for the maximum CA production (33.3g/L) in non-sterile DPCW medium were the temperature of 20°C, pH 5.5, additional lactose concentration of 20g/L, sodium alginate concentration of 2%, number of 150 beads/100mL and incubation time of 120h. Similarly, maximum citric acid/isocitric acid (CA/ICA) ratio (6.79) could be reached under these optimal conditions. Additional nitrogen and phosphorus sources decreased CA concentration and CA/ICA ratio. Immobilized cells were reused in three continuous reaction cycles without any loss in the maximum CA concentration. The unique combination of low pH and temperature values as well as cell immobilization procedure could prevent undesired microbial contaminants during CA production. This is the first work on CA production by cold-adapted microorganisms under non-sterile culture conditions. Besides, CA production using a lactose-positive strain of the yeast Y. lipolytica was investigated for the first time in the present study.

  20. Part 2. Comparison of emergency washing solutions in 70% hydrofluoric acid-burned human skin in an established ex vivo explants model

    PubMed Central

    Burgher, François; Mathieu, Laurence; Lati, Elian; Gasser, Philippe; Peno-Mazzarino, Laurent; Blomet, Joël; Hall, Alan H; Maibach, Howard I

    2011-01-01

    Background: Hydrofluoric acid (HF) is a small and partially dissociated acid (pKa 3.2), able to deeply penetrate into human skin in addition to the corrosiveness of the hydrogen ion (H+) and the toxicity of the fluoride ion (F-). However, there has been a lack of experimental studies to objectively characterize the results of human HF skin exposure decontamination. Methodology/principal findings: A previously established experimental method using a human skin explants ex vivo model (Part 1. Experimental 70% hydrofluoric acid (HF) burns: Histological observations in an established human skin explants ex vivo model) described the lesions that appeared following 70% HF penetration. Within 5min, 70% HF penetrates to the dermis. Using the same experimental conditions, a comparison study of two different washing protocols was performed: water + topical calcium gluconate (CaG) versus Hexafluorine®. In these conditions, washing for 15min with running tap water followed by topical CaG ointment only delayed burn onset, while severe tissue damage appeared later. In contrast, after washing with Hexafluorine® over 10 min, no histological lesions developed. These results are in accordance with the results of accidental human industrial case reports. Conclusion/significance: Amphoteric and hypertonic Hexafluorine® can deactivate H+ and chelate F- ions. Based on these results, it should be considered as a promising first-aid decontamination solution to prevent or minimize significant local and systemic consequences of concentrated HF skin exposures. PMID:21083510

  1. Sequential Mixed Cultures: From Syngas to Malic Acid.

    PubMed

    Oswald, Florian; Dörsam, Stefan; Veith, Nicolas; Zwick, Michaela; Neumann, Anke; Ochsenreither, Katrin; Syldatk, Christoph

    2016-01-01

    Synthesis gas (syngas) fermentation using acetogenic bacteria is an approach for production of bulk chemicals like acetate, ethanol, butanol, or 2,3-butandiol avoiding the fuel vs. food debate by using carbon monoxide, carbon dioxide, and hydrogen from gasification of biomass or industrial waste gases. Suffering from energetic limitations, yields of C4-molecules produced by syngas fermentation are quite low compared with ABE fermentation using sugars as a substrate. On the other hand, fungal production of malic acid has high yields of product per gram metabolized substrate but is currently limited to sugar containing substrates. In this study, it was possible to show that Aspergilus oryzae is able to produce malic acid using acetate as sole carbon source which is a main product of acetogenic syngas fermentation. Bioreactor cultivations were conducted in 2.5 L stirred tank reactors. During the syngas fermentation part of the sequential mixed culture, Clostridium ljungdahlii was grown in modified Tanner medium and sparged with 20 mL/min of artificial syngas mimicking a composition of clean syngas from entrained bed gasification of straw (32.5 vol-% CO, 32.5 vol-% H2, 16 vol-% CO2, and 19 vol-% N2) using a microsparger. Syngas consumption was monitored via automated gas chromatographic measurement of the off-gas. For the fungal fermentation part gas sparging was switched to 0.6 L/min of air and a standard sparger. Ammonia content of medium for syngas fermentation was reduced to 0.33 g/L NH4Cl to meet the requirements for fungal production of dicarboxylic acids. Malic acid production performance of A. oryzae in organic acid production medium and syngas medium with acetate as sole carbon source was verified and gave YP∕S values of 0.28 g/g and 0.37 g/g respectively. Growth and acetate formation of C. ljungdahlii during syngas fermentation were not affected by the reduced ammonia content and 66 % of the consumed syngas was converted to acetate. The overall conversion

  2. Sequential Mixed Cultures: From Syngas to Malic Acid

    PubMed Central

    Oswald, Florian; Dörsam, Stefan; Veith, Nicolas; Zwick, Michaela; Neumann, Anke; Ochsenreither, Katrin; Syldatk, Christoph

    2016-01-01

    Synthesis gas (syngas) fermentation using acetogenic bacteria is an approach for production of bulk chemicals like acetate, ethanol, butanol, or 2,3-butandiol avoiding the fuel vs. food debate by using carbon monoxide, carbon dioxide, and hydrogen from gasification of biomass or industrial waste gases. Suffering from energetic limitations, yields of C4-molecules produced by syngas fermentation are quite low compared with ABE fermentation using sugars as a substrate. On the other hand, fungal production of malic acid has high yields of product per gram metabolized substrate but is currently limited to sugar containing substrates. In this study, it was possible to show that Aspergilus oryzae is able to produce malic acid using acetate as sole carbon source which is a main product of acetogenic syngas fermentation. Bioreactor cultivations were conducted in 2.5 L stirred tank reactors. During the syngas fermentation part of the sequential mixed culture, Clostridium ljungdahlii was grown in modified Tanner medium and sparged with 20 mL/min of artificial syngas mimicking a composition of clean syngas from entrained bed gasification of straw (32.5 vol-% CO, 32.5 vol-% H2, 16 vol-% CO2, and 19 vol-% N2) using a microsparger. Syngas consumption was monitored via automated gas chromatographic measurement of the off-gas. For the fungal fermentation part gas sparging was switched to 0.6 L/min of air and a standard sparger. Ammonia content of medium for syngas fermentation was reduced to 0.33 g/L NH4Cl to meet the requirements for fungal production of dicarboxylic acids. Malic acid production performance of A. oryzae in organic acid production medium and syngas medium with acetate as sole carbon source was verified and gave YP∕S values of 0.28 g/g and 0.37 g/g respectively. Growth and acetate formation of C. ljungdahlii during syngas fermentation were not affected by the reduced ammonia content and 66 % of the consumed syngas was converted to acetate. The overall conversion

  3. Antioxidant capacity and amino acid analysis of Caralluma adscendens (Roxb.) Haw var. fimbriata (wall.) Grav. & Mayur. aerial parts.

    PubMed

    Maheshu, Vellingiri; Priyadarsini, Deivamarudhachalam Teepica; Sasikumar, Jagathala Mahalingam

    2014-10-01

    Caralluma adscendens (Roxb.) Haw var. fimbriata (wall.) Grav. & Mayur. is a traditional food consumed as vegetable or pickle in arid regions of India and eaten during famines. In Indian traditional medicine, the plant is used to treat diabetes, inflammation and etc. The aim of this study was to evaluate the antioxidant properties (DPPH, TEAC, TAA, FRAP, OH˙ and NO˙ radical scavenging activities) of the different extracts from aerial parts. The levels of total phenolics and flavonoids of the extracts were also determined. The extracts were found to have different levels of antioxidant properties in the test models used. Methanol and water extracts had good total phenolic and flavonoid contents showed potent antioxidant and free radical scavenging activities. The antioxidant activity was correlated well with the amount of total phenolics present in the extracts. The extracts and its components may be used as an additive in food preparations and nutraceuticals.

  4. IUPAC-NIST Solubility Data Series. 90. Hydroxybenzoic Acid Derivatives in Binary, Ternary, and Multicomponent Systems. Part I. Hydroxybenzoic Acids, Hydroxybenzoates, and Hydroxybenzoic Acid Salts in Water and Aqueous Systems

    NASA Astrophysics Data System (ADS)

    Goto, Rensuke; Fukuda, Hiroshi; Königsberger, Erich; Königsberger, Lan-Chi

    2011-03-01

    The solubility data for well-defined binary, ternary, and multicomponent systems of solid-liquid type are reviewed. One component, which is 2-, 3-, and 4-hydroxybenzoic acids, 4-hydroxybenzoate alkyl esters (parabens), or hydroxybenzoic acid salts, is in the solid state at room temperature and another component is liquid water, meaning that all of the systems are aqueous solutions. The ternary or multicomponent systems include organic substances of various classes (hydrocarbons of several structural types, halogenated hydrocarbons, alcohols, acids, ethers, esters, amides, and surfactants) or inorganic substances. Systems reported in the primary literature from 1898 through 2000 are compiled. For seven systems, sufficient binary data for hydroxybenzoic acids or parabens in water are available to allow critical evaluation. Almost all data are expressed as mass and mole fractions as well as the originally reported units, while some data are expressed as molar concentration.

  5. Rational assembly of Pb(II)/Cd(II)/Mn(II) coordination polymers based on flexible V-shaped dicarboxylate ligand: Syntheses, helical structures and properties

    SciTech Connect

    Yang, Gao-Shan; Liu, Chong-Bo; Liu, Hong; Robbins, Julianne; Zhang, Z. John; Yin, Hong-Shan; Wen, Hui-Liang; Wang, Yu-Hua

    2015-05-15

    Six new coordination polymers, namely, [Pb(L)(H{sub 2}O)] (1), [Pb(L)(phen)] (2), [Pb{sub 2}(L){sub 2}(4,4′-bipy){sub 0.5}] (3), [Cd(L)(phen)] (4), [Cd(L)(4,4′-bipy)]·H{sub 2}O (5) and [Mn(L)(4,4′-bipy)]·H{sub 2}O (6) have been synthesized by the hydrothermal reaction of 2,2′-[hexafluoroisopropylidenebis(p-phenyleneoxy)]diacetic acid (H{sub 2}L) with Pb(II)/Cd(II)/Mn(II) in the presence of ancillary ligands 4,4′-bipyridine (4,4′-bipy) or 1,10-phenanthroline (phen). Complexes 1 and 4–6 exhibit 2-D structures, and complexes 2–3 display 3-D frameworks, of which L{sup 2−} ligands join metal ions to single-stranded helical chains of 1, 3–6 and double-stranded helical chains of 2. Complexes 2 and 3 also contain double-stranded Metal–O helices. Topology analysis reveals that complexes 1 and 4 both represent 4-connected sql net, 2 represents 6-connected pcu net, 3 exhibits a novel (3,12)-connected net, while 5 and 6 display (3,5)-connected gek1 net. The six complexes exhibit two kinds of inorganic–organic connectivities: I{sup 0}O{sup 2} for 1, 4–6, and I{sup 1}O{sup 2} for 2–3. The photoluminescent properties of 4–5 and the magnetic properties of 6 have been investigated. - Graphical abstract: Six new Pb(II)/Cd(II)/Mn(II) coordination polymers with helical structures based on flexible V-shaped dicarboxylate ligand have been synthesized and structurally characterized. Photoluminescent and magnetic properties have been investigated. - Highlights: • Six novel M(II) coordination polymers with 2,2′-[hexafluoroisopropylidenebis(p-phenyleneoxy)]diacetic acid and N-donor ligands. • Complexes 1–6 show diverse intriguing helical characters. • The luminescent properties of complexes 1–5 were investigated. • Complex 6 shows antiferromagnetic coupling.

  6. Studies of single aerosol particles containing malonic acid, glutaric acid, and their mixtures with sodium chloride. II. Liquid-state vapor pressures of the acids.

    PubMed

    Pope, Francis D; Tong, Hai-Jie; Dennis-Smither, Ben J; Griffiths, Paul T; Clegg, Simon L; Reid, Jonathan P; Cox, R Anthony

    2010-09-23

    The vapor pressures of two dicarboxylic acids, malonic acid and glutaric acid, are determined by the measurement of the evaporation rate of the dicarboxylic acids from single levitated particles. Two laboratory methods were used to isolate single particles, an electrodynamic balance and optical tweezers (glutaric acid only). The declining sizes of individual aerosol particles over time were followed using elastic Mie scattering or cavity enhanced Raman scattering. Experiments were conducted over the temperature range of 280-304 K and a range of relative humidities. The subcooled liquid vapor pressures of malonic and glutaric acid at 298.15 K were found to be 6.7(-1.2)(+2.6) x 10(-4) and 11.2(-4.7)(+9.6) x 10(-4) Pa, respectively, and the standard enthalpies of vaporization were respectively 141.9 ± 19.9 and 100.8 ± 23.9 kJ mol(-1). The vapor pressures of both glutaric acid and malonic acid in single particles composed of mixed inorganic/organic composition were found to be independent of salt concentration within the uncertainty of the measurements. Results are compared with previous laboratory determinations and theoretical predictions.

  7. Seasonal distributions of low molecular weight dicarboxylic acids in the remote marine aerosols and their stable carbon isotopic composition

    NASA Astrophysics Data System (ADS)

    Kay, J. E.; L'Ecuyer, T. S.; Gettelman, A.

    2011-12-01

    Arctic Ocean satellite observations (A-train, CERES-EBAF) are combined to create a cloud and radiation climatology for the early 21st century. The climatology exposes large geographic, seasonal, and interannual variability in cloud forcing but on average, Arctic Ocean clouds warm the surface by 10 W/m2 and reduce incoming top-of-atmosphere (TOA) radiation by 12 W/m2. During the early 21st century, summer Arctic TOA albedo decreases can be explained by sea ice loss but are unrelated to summer cloud trends that are statistically insignificant. In contrast, both sea ice variability and cloud variability contribute to interannual variability in summer shortwave radiative fluxes. In summary, the observations show that while cloud variability influences absorbed shortwave radiation variability, there is no summer cloud trend affecting summer absorbed shortwave radiation (Kay and L'Ecuyer 2013 JGR). Implications of these findings for Arctic shortwave climate feedbacks and model evaluation are discussed.

  8. 4-Hydr-oxy-1-oxo-1,2-dihydro-phthalazine-6,7-dicarboxylic acid dihydrate.

    PubMed

    Liang, Ling-Ling; Zhao, Jian-She; Ng, Seik Weng

    2008-06-07

    In the crystal structure of the title compound, C(10)H(6)N(2)O(6)·2H(2)O, the OH and NH groups each serve as a hydrogen-bond donor to one acceptor site whereas the water mol-ecules each serve as a hydrogen-bond donor to two acceptor sites. The hydrogen-bonding scheme gives rise to a three-dimensional network.

  9. Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids

    EPA Science Inventory

    In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+). However, most atmospheric chemistry...

  10. Spatio-temporal trends and monitoring design of perfluoroalkyl acids in the eggs of gull (Larid) species from across Canada and parts of the United States.

    PubMed

    Gewurtz, Sarah B; Martin, Pamela A; Letcher, Robert J; Burgess, Neil M; Champoux, Louise; Elliott, John E; Weseloh, D V Chip

    2016-09-15

    A large spatial dataset of perfluoroalkyl acid (PFAA) concentrations in eggs of herring gulls (Larus argentatus or congeneric species) collected from late April to early June between 2009 and 2014 from 28 colonies across Canada and parts of the Unites States was used to evaluate location-specific patterns in chemical concentrations and to generate hypotheses on the major sources affecting PFAA distributions. The highly bioaccumulative perfluorooctane sulfonic acid (PFOS) as well as other perfluoroalkyl sulfonic acids (PFSAs) showed the greatest concentrations in eggs from the lower Great Lakes of southern Ontario as well as from the St. Lawrence River. Despite the 2000 to 2002 phase-out of PFOS and related C8 chemistry by the major manufacturer at the time, ongoing losses from consumer products during use and disposal in urban/industrial locations continue to be major sources to the environment and are influencing the spatial trends of PFOS in Canada. In comparison to PFOS, perfluoroalkyl carboxylic acids (PFCAs) were not as concentrated in eggs in close proximity to urbanized/industrialized centers, but had surprisingly elevated levels in relatively remote regions such as Great Slave Lake, NT and East Bay in Hudson Bay, NU. The present results support the hypothesis that atmospheric transport and degradation of precursor chemicals, such as the fluorotelomer alcohols 8:2 FTOH and 10:2 FTOH, are influencing the spatial trends of PFCAs in Canada. A power analysis conducted on a representative urbanized/industrialized colony in the Toronto Harbour, ON, and a relatively remote colony in Lake Superior, emphasized the importance of consistent and long-term data collection in order to detect the anticipated changes in PFAA concentrations in Canadian gull eggs.

  11. Poly[di-μ-aqua-μ4-(pyrazine-2,5-dicarboxyl­ato)-dilithium(I)

    PubMed Central

    Starosta, Wojciech; Leciejewicz, Janusz

    2011-01-01

    In the title coordination polymer, [Li2(C6H2N2O2)(H2O)2]n the pyrazine-2,5-dicarboxyl­ate dianionic ligand bridges two symmetry-independent Li+ ions using both its N,O-chelating sites. The carboxyl­ate O atom of one of them also bridges to another Li+ ion, while the second O atom of this group is bonded to another Li+ ion. Two symmetry-independent water O atoms participate also in the bridging system, which gives rise to a polymeric three-dimensional framework. Both Li+ ions show distorted trigonal–bipyramidal LiNO4 coordination geometries, with the N atom in an axial site in both cases. The packing is consolidated by O—H⋯O hydrogen bonds, which occur between water mol­ecules as donors and carboxyl­ate O atoms as acceptors. PMID:21522570

  12. Differences among Branded Hyaluronic Acids in Italy, Part 1: Data from In Vitro and Animal Studies and Instructions for Use

    PubMed Central

    Migliore, A.; Bizzi, E.; De Lucia, O.; Delle Sedie, A.; Bentivegna, M.; Mahmoud, Asmaa; Foti, C.

    2016-01-01

    BACKGROUND The use of hyaluronic acid (HA) for intra-articular (IA) injection is widespread around the world for patients affected by osteoarthritis. AIM The aim of this study is to identify scientific evidence from in vitro and in vivo studies supporting the use of IA HAs marketed in Italy. We also evaluated the accuracy of indications and contraindications reported in the leaflets of such HAs compared with the available scientific evidence. MATERIALS AND METHODS An extensive literature search was performed to identify all in vitro and in vivo model studies reporting on the effects of various HAs marketed in Italy for IA use. Data reported in the leaflets of different HA-based products for IA use were extracted and analyzed alongside evidence from in vitro and in vivo model studies. RESULTS Nine in vitro studies and 11 studies on animal models were examined. Comparing results with what is reported in the leaflets of HAs marketed in Italy, it was observed that many branded formulations are introduced in the market without any reporting of basic scientific evidence. Only 12.82% and 17.95% of branded products had been shown to be effective with scientific evidence from in vitro and in vivo studies, respectively. The rationale of use of these products is based on their nature, as if a class effect existed such that all HAs would yield similar effects. CONCLUSIONS Data on HAs deriving from in vitro and in vivo studies are scarce and relate to only a small percentage of products marketed in Italy. Many indications and contraindications are arbitrarily reported in Italian HA leaflets without the support of scientific evidence. Larger and brand-specific studies are necessary and should be reported in the leaflets to guide clinicians in making an appropriate choice regarding HA-based IA therapy. PMID:27257398

  13. Syntheses, structures and magnetic properties of four coordination polymers based on nitrobenzene dicarboxylate and various N-donor coligands

    NASA Astrophysics Data System (ADS)

    Li, Gui-Lian; Yin, Wei-Dong; Liu, Guang-Zhen; Ma, Lu-Fang; Wang, Li-Ya

    2014-12-01

    Four new coordination polymers {[Ni(4-Nbdc)(bpa)(H2O)]}n (1), {[Co(4-Nbdc)(bpp) (H2O)]}n (2), {[Ni(4-Nbdc)(bpp)(H2O)]·H2O}n (3), and {[Mn2(3-Nbdc)2(bib)3]·2H2O}n (4) (4-Nbdc=4-nitrobenzene-1,2-dicarboxylate, 3-Nbdc=3-nitrobenzene-1,2-dicarboxylate, bpa=1,2-bi(4-pyridyl)ethane, bpp=1,3-bis(4-pyridyl)propane, and bib=1,4-bis(1-imidazoly)benzene), were synthesized by hydrothermal reactions, and characterized by single-crystal X-ray diffractions, elemental analysis, FT-IR, PXRD, TGA and magnetic analysis. Complexes 1 and 2 display quasi-trapezoidal chain and brick-wall layer, and both of them contain metal-carboxylate binuclear units. Complexes 3 and 4 exhibit three-dimensional frameworks with the (66) dia topology and (44.610.8)(44.62) fsc topology, and both of them contain metal-carboxylate chains. The carboxyl groups with syn-anti coordination mode mediate effectively the weak ferromagnetic coupling interaction within Ni(II)-carboxylate binuclear in 1 (J=1.27 cm-1) and Ni(II)-carboxylate chain in 3 (J=1.44 cm-1), respectively, and the carboxyl groups with anti-anti coordination mode leads to the classic antiferromagnetic coupling interaction within Mn(II)-carboxylate chain in 4 (J=-0.77 cm-1).

  14. Integrated engineering of β-oxidation reversal and ω-oxidation pathways for the synthesis of medium chain ω-functionalized carboxylic acids.

    PubMed

    Clomburg, James M; Blankschien, Matthew D; Vick, Jacob E; Chou, Alexander; Kim, Seohyoung; Gonzalez, Ramon

    2015-03-01

    An engineered reversal of the β-oxidation cycle was exploited to demonstrate its utility for the synthesis of medium chain (6-10-carbons) ω-hydroxyacids and dicarboxylic acids from glycerol as the only carbon source. A redesigned β-oxidation reversal facilitated the production of medium chain carboxylic acids, which were converted to ω-hydroxyacids and dicarboxylic acids by the action of an engineered ω-oxidation pathway. The selection of a key thiolase (bktB) and thioesterase (ydiI) in combination with previously established core β-oxidation reversal enzymes, as well as the development of chromosomal expression systems for the independent control of pathway enzymes, enabled the generation of C6-C10 carboxylic acids and provided a platform for vector based independent expression of ω-functionalization enzymes. Using this approach, the expression of the Pseudomonas putida alkane monooxygenase system, encoded by alkBGT, in combination with all β-oxidation reversal enzymes resulted in the production of 6-hydroxyhexanoic acid, 8-hydroxyoctanoic acid, and 10-hydroxydecanoic acid. Following identification and characterization of potential alcohol and aldehyde dehydrogenases, chnD and chnE from Acinetobacter sp. strain SE19 were expressed in conjunction with alkBGT to demonstrate the synthesis of the C6-C10 dicarboxylic acids, adipic acid, suberic acid, and sebacic acid. The potential of a β-oxidation cycle with ω-oxidation termination pathways was further demonstrated through the production of greater than 0.8 g/L C6-C10 ω-hydroxyacids or about 0.5 g/L dicarboxylic acids of the same chain lengths from glycerol (an unrelated carbon source) using minimal media.

  15. Production of polymalic acid and malic acid by Aureobasidium pullulans fermentation and acid hydrolysis.

    PubMed

    Zou, Xiang; Zhou, Yipin; Yang, Shang-Tian

    2013-08-01

    Malic acid is a dicarboxylic acid widely used in the food industry and also a potential C4 platform chemical that can be produced from biomass. However, microbial fermentation for direct malic acid production is limited by low product yield, titer, and productivity due to end-product inhibition. In this work, a novel process for malic acid production from polymalic acid (PMA) fermentation followed by acid hydrolysis was developed. First, a PMA-producing Aureobasidium pullulans strain ZX-10 was screened and isolated. This microbe produced PMA as the major fermentation product at a high-titer equivalent to 87.6 g/L of malic acid and high-productivity of 0.61 g/L h in free-cell fermentation in a stirred-tank bioreactor. Fed-batch fermentations with cells immobilized in a fibrous-bed bioreactor (FBB) achieved the highest product titer of 144.2 g/L and productivity of 0.74 g/L h. The fermentation produced PMA was purified by adsorption with IRA-900 anion-exchange resins, achieving a ∼100% purity and a high recovery rate of 84%. Pure malic acid was then produced from PMA by hydrolysis with 2 M sulfuric acid at 85°C, which followed the first-order reaction kinetics. This process provides an efficient and economical way for PMA and malic acid production, and is promising for industrial application.

  16. Simultaneous Ultra Performance Liquid Chromatography Determination and Antioxidant Activity of Linarin, Luteolin, Chlorogenic Acid and Apigenin in Different Parts of Compositae Species.

    PubMed

    Hwang, Seung Hwan; Paek, Ji Hun; Lim, Soon Sung

    2016-11-23

    Linarin (LA), luteolin (LE), chlorogenic acid (CA) and apigenin (AP) are four major flavonoids with various promising bioactivities found in Compositae (COP) species. A reliable, reproducible and accurate method for the simultaneous and quantitative determination of these four major flavonoids by Ultra Performance Liquid Chromatography (UPLC) analysis was developed. This method should be appropriate for the quality assurance of COP. The UPLC separation was carried out using an octadecylsilane (ODS) Hypersil (2.1 mm × 250 mm, 1.9 μm) and a mobile phase composed of acetonitrile and 0.1% formic acid in water at a flow rate 0.44 mL/min and ultraviolet (UV) detection 254 nm. Gradient elution was employed. The method was precise, with relative standard deviation below 3.0% and showed excellent linearity (R² > 0.999). The recoveries for the four flavonoids in COP were between 95.49%-106.23%. The average contents of LA, LE, CA and AP in different parts (flower, leave and stem) of COP were between 0.64-1.47 g/100 g, 0.66-0.89 g/100 g, 0.32-0.52 g/100 g and 0.16-0.18 g/100 g, respectively. The method was accurate and reproducible and it can provide a quantitative basis for quality control of COP.

  17. Benefits and risks of fish consumption Part II. RIBEPEIX, a computer program to optimize the balance between the intake of omega-3 fatty acids and chemical contaminants.

    PubMed

    Domingo, José L; Bocio, Ana; Martí-Cid, Roser; Llobet, Juan M

    2007-02-12

    In recent years, and based on the importance of fish as a part of a healthy diet, there has been a notable promotion of fish and seafood consumption. However, a number of recent studies have shown that fish may be a potential source of exposure to chemical pollutants, some of them with well known adverse effects on human health. Recently, we determined in 14 edible marine species the concentrations of eicosapentaenoic acid (EPA) and docosohexaenoic acid (DHA), as well as those of a number of chemical contaminants: Cd, Hg, Pb, polychlorinated dibenzo-p-dioxins and furans, polychlorinated biphenyls, hexachlorobenzene, polycyclic aromatic hydrocarbons, polychlorinated naphthalenes, polybrominated diphenylethers and polychlorinated diphenylethers. To quantitative establish the intake of these pollutants (risks) versus that of EPA+DHA (benefits), we designed a simple computer program, RIBEPEIX. The concentrations of EPA, DHA, and the chemical pollutants were introduced into the program. We here present how RIBEPEIX may be used as an easy tool to optimize fish consumption: most suitable species, frequency of consumption, and size of meals. RIBEPEIX can be useful not only for professionals (cardiologists, general physicians, nutritionists, toxicologists, etc.), but also for the general population. It is available at: .

  18. Superoxide anions produced by inflammatory cells play an important part in the pathogenesis of acid and pepsin induced oesophagitis in rabbits.

    PubMed Central

    Naya, M J; Pereboom, D; Ortego, J; Alda, J O; Lanas, A

    1997-01-01

    BACKGROUND: Reactive oxygen metabolites have been associated with gastrointestinal injury. OBJECTIVE: To investigate whether mucosal reactive oxygen metabolites are involved in acid and pepsin induced oesophagitis, and if so, which specific metabolites. METHODS: The effects of free radical scavengers and the anti-inflammatory drug ketotifen on rabbit oesophagitis induced by acidified pepsin were studied. Isolated oesophageal cells were obtained before and after oesophageal injury and the generation of superoxide anion and hydrogen peroxide was analysed by flow cytometry. The presence of inflammatory cells was determined by indirect immunofluorescence with a mouse antirabbit CD11b antibody. RESULTS: Of the free radical scavengers tested, superoxide dismutase, which reacts with the superoxide anion, significantly reduced oesophagitis, whereas catalase, which reacts with hydrogen peroxide, had only a mild effect and dimethylsulphoxide had no effect. Ketotifen significantly reduced the inflammation and also prevented the induction of oesophagitis. Isolated cells obtained from the oesophageal mucosa after acidified pepsin exposure generated increased amounts of superoxide anions, which were mainly produced by CD11b positive cells. CONCLUSIONS: Reactive oxygen metabolites, especially superoxide anion, produced by inflammatory cells play a significant part in the genesis of oesophagitis induced by acid and pepsin in rabbits and might be a target for future medical therapy. Images PMID:9071927

  19. Seasonal and spatial changes of free and bound organic acids in total suspended particles in Guangzhou, China

    NASA Astrophysics Data System (ADS)

    Ma, Shexia; Peng, Ping'an; Song, Jianzhong; Bi, Xinhui; Zhao, Jinping; He, Lulu; Sheng, Guoying; Fu, Jiamo

    2010-12-01

    The concentrations and compositions of free and bound organic acids in total suspended particles from typical urban, suburban and forest park sites of Guangzhou were determined in this study. The free form of organic acids (solvent extractable) in aerosols in Guangzhou varied with site and season. The suburban samples contained the highest contents of alkanoic, alkenoic and dicarboxylic acids. These findings were consistent with a higher supply of hydrocarbons and NOx in the suburban area. However, concentrations of aromatic acids were similar in the urban, suburban and forest park sites. Generally, winter season samples of the acids from anthropogenic sources contained more organic acids than summer season samples due to stronger removal by wet deposition in the summer. For the acids from botanic sources, the summer season samples were higher. In addition to the free acids, bound acids (solvent non-extractable) mainly formed by esterification of free acids were also found in the samples. In general, bound acids were higher than free acids. Esterification is mainly controlled by the pKa of organic acids and the atmospheric pH value. This explains why aromatic and dicarboxylic acids occur mainly as bound forms and why the samples from urban sites contained high levels of bound acids as the pH of rain water can reach 4.53. Concentrations of alkanoic and alkenoic acids in the aerosols of Guangzhou were much higher than those in the other areas studied.

  20. Oxidative degradation of organic acids conjugated with sulfite oxidation in flue gas desulfurization

    SciTech Connect

    Lee, Y.I.

    1986-01-01

    Organic acid degradation conjugated with sulfite oxidation has been studied under flue gas desulfurization (EGD) conditions. The oxidative degradation constant, k/sub 12/, is defined as the ratio of organic acid degradation rate and sulfite oxidation rate after being normalized by the concentrations of organic acid and dissolved S(IV). K/sub 12/, not significantly affected by pH or dissolved oxygen, is around 10/sup -3/ in the absence of manganese or iron. However, k/sub 12/ is increased by certain transition metals such as Co, Ni, and Fe and is decreased by Mn and halides. Lower dissolved S(IV) magnified these effects. No k/sub 12/ greater than 4 x 10/sup -3/ or smaller than 0.1 x 10/sup -3/ has been observed. A free radical mechanism was proposed to describe the kinetics: (1) sulfate free radical is the major radical responsible to the degradation of organic acid; (2) ferrous generates sulfate radical by reacting with monoxypersulfate to enhance k/sub 12/; (3) manganous consumes sulfate radical to decrease k/sub 12/; (4) dissolved S(IV) competes with ferrous for monoxypersulfate and with manganous for sulfate radical to demonstrate the effects of dissolved S(IV) on k/sub 12/. Hydroxy and sulfonated carboxylic acids degrade approximately three times slower than saturated dicarboxylic acids; while maleic acid, an unsaturated dicarboxylic acid, degraded an order of magnitude faster. A wide spectrum of degradation products of adipic acid were found, including carbon dioxide - the major product, glutaric semialdehyde - the major retained product with low manganese, glutaric acid and valeric acids - the major retained product with high manganese, lower molecular weight mono- and dicarboxylic acids, other carbonyl compounds, and hydrocarbons.

  1. Ultrasound-mediated synthesis of 4-substituted 1,4-dihydropyridine-3,5-dicarboxylates catalyzed by 1-carboxymethyl-3-methylimidazolium tetrafluoroborate under solvent free condition.

    PubMed

    He, Jing-Yu; Jia, Hui-Zhen; Yao, Qing-Guo; Liu, Si-Jie; Yue, Hong-Kun; Yu, Hong-Wei; Hu, Rui-Sheng

    2015-01-01

    4-Substituted 1,4-dihydropyridine-3,5-dicarboxylates (4) have been synthesized by the solvent-free reaction of aldehyde, methyl propiolate and ammonium carbonate catalyzed by ionic liquid 1-carboxymethyl-3-methylimidazolium tetrafluoroborate under ultrasonic irradiation. The effects of changes in the ultrasonic power, temperature, catalysts and reactants on the synthesis of 4-substituted 1,4-dihydropyridine-3,5-dicarboxylates (4) are discussed. With the optimized reaction conditions, various aldehydes were used to synthesize 1,4-dihydropyridines (4) under the influence of ultrasound irradiation. Compared with the conventional thermal methods, the remarkable advantages of this method are the simple experimental procedure, shorter reaction time (2-10min) and high yield of product (76-95%). Furthermore, the green catalytic system can be recycled specific times without significantly decreasing the yields and reaction rates.

  2. Evaluation of sampling methods for measuring exposure to volatile inorganic acids in workplace air. Part 1: sampling hydrochloric acid (HCl) and nitric acid (HNO₃) from a test gas atmosphere.

    PubMed

    Howe, Alan; Musgrove, Darren; Breuer, Dietmar; Gusbeth, Krista; Moritz, Andreas; Demange, Martine; Oury, Véronique; Rousset, Davy; Dorotte, Michel

    2011-08-01

    Historically, workplace exposure to the volatile inorganic acids hydrochloric acid (HCl) and nitric acid (HNO(3)) has been determined mostly by collection on silica gel sorbent tubes and analysis of the corresponding anions by ion chromatography (IC). However, HCl and HNO(3) can be present in workplace air in the form of mist as well as vapor, so it is important to sample the inhalable fraction of airborne particles. As sorbent tubes exhibit a low sampling efficiency for inhalable particles, a more suitable method was required. This is the first of two articles on "Evaluation of Sampling Methods for Measuring Exposure to Volatile Inorganic Acids in Workplace Air" and describes collaborative sampling exercises carried out to evaluate an alternative method for sampling HCl and HNO(3) using sodium carbonate-impregnated filters. The second article describes sampling capacity and breakthrough tests. The method was found to perform well and a quartz fiber filter impregnated with 500 μL of 1 M Na(2)CO(3) (10% (m/v) Na(2)CO(3)) was found to have sufficient sampling capacity for use in workplace air measurement. A pre-filter is required to remove particulate chlorides and nitrates that when present would otherwise result in a positive interference. A GSP sampler fitted with a plastic cone, a closed face cassette, or a plastic IOM sampler were all found to be suitable for mounting the pre-filter and sampling filter(s), but care has to be taken with the IOM sampler to ensure that the sampler is tightly closed to avoid leaks. HCl and HNO(3) can react with co-sampled particulate matter on the pre-filter, e.g., zinc oxide, leading to low results, and stronger acids can react with particulate chlorides and nitrates removed by the pre-filter to liberate HCl and HNO(3), which are subsequently collected on the sampling filter, leading to high results. However, although there is this potential for both positive and negative interferences in the measurement, these are unavoidable

  3. Enhanced concentrations of citric acid in spring aerosols collected at the Gosan background site in East Asia

    NASA Astrophysics Data System (ADS)

    Jung, Jinsang; Kawamura, Kimitaka

    2011-09-01

    In order to investigate water-soluble dicarboxylic acids and related compounds in the aerosol samples under the Asian continent outflow, total suspended particle (TSP) samples ( n = 32) were collected at the Gosan site in Jeju Island over 2-5 days integration during 23 March-1 June 2007 and 16-24 April 2008. The samples were analyzed for water-soluble dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls using a capillary gas chromatography technique. We found elevated concentrations of atmospheric citric acid (range: 20-320 ng m -3) in the TSP samples during mid- to late April of 2007 and 2008. To specify the sources of citric acid, dicarboxylic acids and related compounds were measured in the pollen sample collected at the Gosan site (Pollen_Gosan), authentic pollen samples from Japanese cedar ( Cryptomeria) (Pollen_cedar) and Japanese cypress ( Chamaecyparis obtusa) (Pollen_cypress), and tangerine fruit produced from Jeju Island. Citric acid (2790 ng in unit mg of pollen mass) was found as most abundant species in the Pollen_Gosan, followed by oxalic acid (2390 ng mg -1). Although citric acid was not detected in the Pollen_cedar and Pollen_cypress as major species, it was found as a dominant species in the tangerine juice while malic acid was detected as major species in the tangerine peel, followed by oxalic and citric acids. Since Japanese cedar trees are planted around tangerine farms to prevent strong winds from the Pacific Ocean, citric acid that may be directly emitted from tangerine is likely adsorbed on pollens emitted from Japanese cedar and then transported to the Gosan site. Much lower malic/citric acid ratios obtained under cloudy condition than clear condition suggest that malic acid may rapidly decompose to lower molecular weight compounds such as oxalic and malonic acids (

  4. Syntheses, structures and magnetic properties of four coordination polymers based on nitrobenzene dicarboxylate and various N-donor coligands

    SciTech Connect

    Li, Gui-Lian; Yin, Wei-Dong; Liu, Guang-Zhen; Ma, Lu-Fang; Wang, Li-Ya

    2014-12-15

    Four new coordination polymers ([Ni(4-Nbdc)(bpa)(H{sub 2}O)]){sub n} (1), ([Co(4-Nbdc)(bpp) (H{sub 2}O)]){sub n} (2), ([Ni(4-Nbdc)(bpp)(H{sub 2}O)]·H{sub 2}O){sub n} (3), and ([Mn{sub 2}(3-Nbdc){sub 2}(bib){sub 3}]·2H{sub 2}O){sub n} (4) (4-Nbdc=4-nitrobenzene-1,2-dicarboxylate, 3-Nbdc=3-nitrobenzene-1,2-dicarboxylate, bpa=1,2-bi(4-pyridyl)ethane, bpp=1,3-bis(4-pyridyl)propane, and bib=1,4-bis(1-imidazoly)benzene), were synthesized by hydrothermal reactions, and characterized by single-crystal X-ray diffractions, elemental analysis, FT-IR, PXRD, TGA and magnetic analysis. Complexes 1 and 2 display quasi-trapezoidal chain and brick-wall layer, and both of them contain metal–carboxylate binuclear units. Complexes 3 and 4 exhibit three-dimensional frameworks with the (6{sup 6}) dia topology and (4{sup 4}.6{sup 10}.8)(4{sup 4}.6{sup 2}) fsc topology, and both of them contain metal–carboxylate chains. The carboxyl groups with syn-anti coordination mode mediate effectively the weak ferromagnetic coupling interaction within Ni(II)–carboxylate binuclear in 1 (J=1.27 cm{sup −1}) and Ni(II)–carboxylate chain in 3 (J=1.44 cm{sup −1}), respectively, and the carboxyl groups with anti-anti coordination mode leads to the classic antiferromagnetic coupling interaction within Mn(II)–carboxylate chain in 4 (J=−0.77 cm{sup −1}). - Highlights: • Four novel coordination polymers were hydrothermally synthesized. • 1 is 1D quasi-trapezoidal chain and 2 is brick-wall layer both with dinuclear units. • 3 and 4 show 3D frameworks both with 1D metal–carboxylate chains. • 1 and 3 exhibit ferromagnetic coupling, while 4 shows antiferromagnetic coupling.

  5. Metabolic engineering strategies to bio-adipic acid production.

    PubMed

    Kruyer, Nicholas S; Peralta-Yahya, Pamela

    2017-03-30

    Adipic acid is the most industrially important dicarboxylic acid as it is a key monomer in the synthesis of nylon. Today, adipic acid is obtained via a chemical process that relies on petrochemical precursors and releases large quantities of greenhouse gases. In the last two years, significant progress has been made in engineering microbes for the production of adipic acid and its immediate precursors, muconic acid and glucaric acid. Not only have the microbial substrates expanded beyond glucose and glycerol to include lignin monomers and hemicellulose components, but the number of microbial chassis now goes further than Escherichia coli and Saccharomyces cerevisiae to include microbes proficient in aromatic degradation, cellulose secretion and degradation of multiple carbon sources. Here, we review the metabolic engineering and nascent protein engineering strategies undertaken in each of these chassis to convert different feedstocks to adipic, muconic and glucaric acid. We also highlight near term prospects and challenges for each of the metabolic routes discussed.

  6. Leucine-induced activation of translational initiation is partly regulated by the branched-chain {alpha}-keto acid dehydrogenase complex in C2C12 cells

    SciTech Connect

    Nakai, Naoya . E-mail: nakai@hss.osaka-u.ac.jp; Shimomura, Yoshiharu; Tamura, Tomohiro; Tamura, Noriko; Hamada, Koichiro; Kawano, Fuminori; Ohira, Yoshinobu

    2006-05-19

    Branched-chain amino acid leucine has been shown to activate the translational regulators through the mammalian target of rapamycin. However, the leucine's effects are self-limiting because leucine promotes its own disposal by an oxidative pathway. The irreversible and rate-limiting step in the leucine oxidation pathway is catalyzed by the branched-chain {alpha}-keto acid dehydrogenase (BCKDH) complex. The complex contains E1 ({alpha}2{beta}2), E2, and E3 subunits, and its activity is abolished by phosphorylation of the E1{alpha} subunit by BCKDH kinase. The relationship between the activity of BCKDH complex and leucine-mediated activation of the protein translation was investigated using the technique of RNA interference. The activity of BCKDH complex in C2C12 cell was modulated by transfection of small interfering RNA (siRNA) for BCKDH E2 subunit or BCKDH kinase. Transfection of siRNAs decreased the mRNA expression and protein amount of corresponding gene. Suppression of either E2 subunit or kinase produced opposite effects on the cell proliferation and the activation of translational regulators by leucine. Suppression of BCKDH kinase for 48 h resulted in decreasing cell proliferation. In contrast, E2 suppression led to increased amount of total cellular protein. The phosphorylation of p70 S6 kinase by leucine was increased in E2-siRNA transfected C2C12 cells, whereas the leucine's effect was diminished in kinase-siRNA transfected cells. These results suggest that the activation of the translational regulators by leucine was partly regulated by the activity of BCKDH complex.

  7. Benefits and risks of fish consumption Part I. A quantitative analysis of the intake of omega-3 fatty acids and chemical contaminants.

    PubMed

    Domingo, José L; Bocio, Ana; Falcó, Gemma; Llobet, Juan M

    2007-02-12

    In recent years, and based on the importance of fish as a part of a healthy diet, there has been a notable promotion of fish consumption. However, the balance between health benefits and risks, due to the intake of chemical contaminants, is not well characterized. In the present study, edible samples of 14 marine species were analyzed for the concentrations of omega-3 fatty acids, as well as a number of metals and organic pollutants. Daily intakes were specifically determined for a standard adult of 70kg, and compared with the tolerable/admissible intakes of the pollutants, if available. Salmon, mackerel, and red mullet were the species showing the highest content of omega-3 fatty acids. The daily intakes of cadmium, lead, and mercury through fish consumption were 1.1, 2.0, and 9.9microg, respectively. Dioxins and furans plus dioxin-like polychlorinated biphenyls (PCBs) intake was 38.0pg WHO-TEQ/day, whereas those of polybrominated diphenyl ethers (PBDEs), polychlorinated diphenyl ethers (PCDEs), polychlorinated naphthalenes (PCNs) and hexachlorobenzene (HCB) were 20.8, 39.4, 1.53, and 1.50ng/day, respectively. In turn, the total intake of 16 analyzed polycyclic aromatic hydrocarbons (PAHs) was 268ng/day. The monthly fish consumption limits for human health endpoints based on the intake of these chemical contaminants were calculated for a 70 years exposure. In general terms, most marine species here analyzed should not mean adverse health effects for the consumers. However, the type of fish, the frequency of consumption, and the meal size are essential issues for the balance of the health benefits and risks of regular fish consumption.

  8. Boosting one-step conversion of cyclohexane to adipic acid by NO2 and VPO composite catalysts.

    PubMed

    Jian, Jian; You, Kuiyi; Duan, Xuezhi; Gao, Hongxu; Luo, Qing; Deng, Renjie; Liu, Pingle; Ai, Qiuhong; Luo, He'an

    2016-02-25

    We demonstrate VPO composites as efficient catalysts for highly selective oxidation of cyclohexane to adipic acid with NO2. In particular, the Ni-Al-VPO composite catalyst exhibits the striking conversion of cyclohexane (60.6%) and exceptionally high selectivity towards adipic acid (85.0%). Moreover, N2O is an environmentally harmful gas, and its yield in the present process is only 0.03 t/t adipic acid, which is far below that obtained using the industrial method (0.3 t/t adipic acid). This work provides a new strategy for the one-step synthesis of dicarboxylic acids from cycloalkanes.

  9. Fluorescent derivatization of aromatic carboxylic acids with horseradish peroxidase in the presence of excess hydrogen peroxide.

    PubMed

    Odo, Junichi; Inoguchi, Masahiko; Aoki, Hiroyuki; Sogawa, Yuto; Nishimura, Masahiro

    2015-01-01

    The fluorescent derivatization of aromatic carboxylic acids by the catalytic activity of horseradish peroxidase (HRP) in the presence of excess H2O2 was investigated. Four monocarboxylic acids, nine dicarboxylic acids, and two tricarboxylic acids, all of which are non- or weakly fluorescent, were effectively converted into fluorescent compounds using this new method. This technique was further developed for the fluorometric determination of trace amounts of terephthalic acid (3c) and lutidinic acid (2b), and linear calibration curves for concentrations between 2.5 and 20.0 nmol of terephthalic acid (3c) and 1.0 and 10.0 nmol of lutidinic acid (2b) were demonstrated. Compound III, an intermediate of HRP, played an essential role in this process. Additionally, lactoperoxidase and manganese peroxidase, peroxidases similar to HRP, showed successful fluorescent derivatization of nicotinic acid (1b), lutidinic acid (2b), and hemimellitic acid (4a) in the presence of excess H2O2.

  10. Solvent-mediated folding of dicarboxylate dianions: aliphatic chain length dependence and origin of the IR intensity quenching.

    PubMed

    Wanko, Marius; Wende, Torsten; Montes Saralegui, Marta; Jiang, Ling; Rubio, Angel; Asmis, Knut R

    2013-12-21

    We combine infrared photodissociation spectroscopy with quantum chemical calculations to characterize the hydration behavior of microsolvated dicarboxylate dianions, (CH2)m(COO(-))2·(H2O)n, as a function of the aliphatic chain length m. We find evidence for solvent-mediated folding transitions, signaled by the intensity quenching of the symmetric carboxylate stretching modes, for all three species studied (m = 2, 4, 8). The number of water molecules required to induce folding increases monotonically with the chain length and is n = 9-12, n = 13, and n = 18-19 for succinate (m = 2), adipate (m = 4), and sebacate (m = 8), respectively. In the special case of succinate, the structural transition is complicated by the possibility of bridging water molecules that bind to both carboxylates with merely minimal chain deformation. On the basis of vibrational calculations on a set of model systems, we identify the factors responsible for intensity quenching. In particular, we find that the effect of hydrogen bonds on the carboxylate stretching mode intensities is strongly orientation dependent.

  11. Self-assembly of amphiphilic liquid crystal polymers obtained from a cyclopropane-1,1-dicarboxylate bearing a cholesteryl mesogen.

    PubMed

    Jia, Lin; Liu, Ming; Di Cicco, Aurélie; Albouy, Pierre-Antoine; Brissault, Blandine; Penelle, Jacques; Boileau, Sylvie; Barbier, Valessa; Li, Min-Hui

    2012-07-31

    We study the self-assembly of a new family of amphiphilic liquid crystal (LC) copolymers synthesized by the anionic ring-opening polymerization of a new cholesterol-based LC monomer, 4-(cholesteryl)butyl ethyl cyclopropane-1,1-dicarboxylate. Using the t-BuP(4) phosphazene base and thiophenol or a poly(ethylene glycol) (PEG) functionalized with thiol group to generate in situ the initiator during the polymerization, LC homopolymer and amphiphilic copolymers with narrow molecular weight distributions were obtained. The self-assemblies of the LC monomer, homopolymer, and block copolymers in bulk and in solution were studied by small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and transmission electron microscopy (TEM). All polymers exhibit in bulk an interdigitated smectic A (SmA(d)) phase with a lamellar period of 4.6 nm. The amphiphilic copolymers self-organize in solution into vesicles with wavy membrane and nanoribbons with twisted and folded structures, depending on concentration and size of LC hydrophobic block. These new morphologies will help the comprehension of the fascinating organization of thermotropic mesophase in lyotropic structures.

  12. Lignan dicarboxylates and terpenoids from the flower buds of Cananga odorata and their inhibitory effects on melanogenesis.

    PubMed

    Matsumoto, Takahiro; Nakamura, Seikou; Nakashima, Souichi; Fujimoto, Katsuyoshi; Yoshikawa, Masayuki; Ohta, Tomoe; Ogawa, Keiko; Matsuda, Hisashi

    2014-04-25

    The methanolic extract from the flower buds of Cananga odorata showed an inhibitory effect on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extract, two new lignan dicarboxylates, canangalignans I and II, three new terpenoids, canangaterpenes I, II, and III, and eight known compounds were isolated. The structures of these compounds were elucidated on the basis of chemical/physicochemical evidence. Several mono- and sesquiterpene analogues significantly inhibited melanogenesis. In particular, canangaterpene I and (3R,3aR,8aS)-3-isopropyl-8a-methyl-8-oxo-1,2,3,3a,6,7,8,8a-octahydroazulene-5-carbaldehyde exhibited a potent inhibitory effect on melanogenesis [inhibition (%): 34.7±4.2 (p<0.01), 45.5±5.7 (p<0.01) at 1 μM, respectively] without inducing cytotoxicity. Moreover, the biological effect of these compounds was much stronger than that of the reference compound, arbutin. Thus, these isolated terpenoid derivatives may be promising therapeutic agents for the treatment of several skin disorders.

  13. One-step green synthesis of non-hazardous dicarboxyl cellulose flocculant and its flocculation activity evaluation.

    PubMed

    Zhu, Hangcheng; Zhang, Yong; Yang, Xiaogang; Liu, Hongyi; Shao, Lan; Zhang, Xiumei; Yao, Juming

    2015-10-15

    The waste management of used flocculants is a thorny issue in the field of wastewater treatment. To natural cellulose based flocculants, utilization of hazardous cellulose solvent and simplification of synthetic procedure are the two urgent problems needing to be further improved. In this work, a series of natural dicarboxyl cellulose flocculants (DCCs) were one-step synthesized via Schiff-base route. The cellulose solvent (NaOH/Urea solution) was utilized during the synthesis process. The full-biodegradable flocculants avoid causing secondary pollution to environment. The chemical structure and solution property of the DCC products were characterized by FT-IR, (1)H NMR, (13)C NMR, TGA, FESEM, charge density and ζ-potential. Kaolin suspension and effluent from paper mill were selected to evaluate the flocculation activity of the DCCs. Their flocculation performance was compared with that of commercial cationic polyacrylamide and poly aluminium chloride flocculants. The positive results showed that the NaOH/Urea solvent effectively promoted the dialdehyde cellulose (DAC) conversion to DCC in the one-step synthesis reaction. The DCCs with the carboxylate content more than 1 mmol/g exhibited steady flocculation performance to kaolin suspension in the broad pH range from 4 to 10. Its flocculation capacity to the effluent from paper mill also showed excellent.

  14. Simple dialkyl pyrazole-3,5-dicarboxylates show in vitro and in vivo activity against disease-causing trypanosomatids.

    PubMed

    Reviriego, Felipe; Olmo, Francisco; Navarro, Pilar; Marín, Clotilde; Ramírez-Macías, Inmaculada; García-España, Enrique; Albelda, María Teresa; Gutiérrez-Sánchez, Ramón; Sánchez-Moreno, Manuel; Arán, Vicente J

    2017-04-03

    The synthesis and antiprotozoal activity of some simple dialkyl pyrazole-3,5-dicarboxylates (compounds 2-6) and their sodium salts (pyrazolates) (compounds 7-9) against Trypanosoma cruzi, Leishmania infantum and Leishmania braziliensis are reported. In most cases the studied compounds showed, especially against the clinically significant amastigote forms, in vitro activities higher than those of the reference drugs (benznidazole for T. cruzi and glucantime for Leishmania spp.); furthermore, the low non-specific cytotoxicities against Vero cells and macrophages shown by these compounds led to good selectivity indexes, which are 8-72 times higher for T. cruzi amastigotes and 15-113 times higher for Leishmania spp. amastigotes than those of the respective reference drugs. The high efficiency of diethyl ester 3 and its sodium salt 8 against the mentioned protozoa was confirmed by further in vitro assays on infection rates and by an additional in vivo study in a murine model of acute and chronic Chagas disease. The inhibitory capacity of compounds 3 and 8 on the essential iron superoxide dismutase of the aforementioned parasites may be related to the observed anti-trypanosomatid activity. The low acute toxicity of compounds 3 and 8 in mice is also reported in this article.

  15. Preparation and optimization of superabsorbent hydrogel micromatrices based on poly(acrylic acid), partly sodium salt-g-poly(ethylene oxide) for modified release of indomethacin.

    PubMed

    Yuksel, Nilufer; Beba, Leyla

    2009-06-01

    The purpose of this study was to prepare modified-release dosage of indomethacin (IND) in the form of micromatrices based on a superabsorbent hydrogel (SAH), poly(acrylic acid), partly sodium salt-g-poly(ethylene oxide) (PAAc-Na-g-PEO). A soaking procedure was used for the preparation of drug-loaded hydrogel micromatrices. The amount of IND, volume of drug-loading solution, and amount of PAAc-Na-g-PEO granules used for preparing micromatrices were the independent factors. The dependent factors were the measured responses from micromatrices, that is, percent recovery, percent entrapment efficiency, and the time at which 63.2% of the drug was released (T(d), minutes). A three-factor, three-level full factorial design (33) was created to optimize formulations. Nonlinear regression analysis indicated a good correlation between the measured responses and the independent factors. Optimum responses were obtained from medium levels of IND and SAH and low level of drug-loading solution. Differential scanning calorimetry, X-ray diffraction analysis, and scanning electron micrography indicated that IND crystals are physically adsorbed into the pores and irregular spaces of the hydrogel.

  16. Selection of background electrolyte for CZE analysis by a chemometric approach. Part I. Separation of a mixture of acidic non-steroidal anti-inflammatory drugs.

    PubMed

    Furlanetto, Sandra; Lanteri, Silvia; Orlandini, Serena; Gotti, Roberto; Giannini, Iacopo; Pinzauti, Sergio

    2007-03-12

    This paper is the first part of the presentation of a chemometric approach for the rapid selection of a suitable background electrolyte (BGE) in CZE analysis of small drug molecules. The strategy is based on principal component analysis and experimental design. In this first section, the approach is applied to the analysis of a mixture of six arylpropionic anti-inflammatory drugs. Initially, 222 possible aqueous background electrolytes (objects) were characterized using as descriptors pH, conductivity, ionic strength and relative viscosity. In order to allow the dissociation of the acidic analytes, this original data set was reduced to 154 background electrolytes with pH values higher than or equal to 5. Principal component analysis made it possible to graphically represent the new set of objects, described by the four variables, in a two-dimensional space. Among these electrolytes, Kennard-Stone algorithm selected ten objects to be tested by CZE, covering homogeneously principal component space. CZE analyses were carried out with the selected electrolytes, and 0.1 M borax was identified as the most suitable one for the specified application. Finally, the characteristics of the analysis were finely tuned by means of a response surface study, which allowed the best conditions to be determined: borax concentration, 0.09 M; methanol, 6% (v/v); temperature, 24 degrees C, voltage, 20 kV. Applying these conditions, a baseline resolution among the six compounds was obtained in less than 10 min.

  17. Toward biotechnological production of adipic acid and precursors from biorenewables.

    PubMed

    Polen, Tino; Spelberg, Markus; Bott, Michael

    2013-08-20

    Adipic acid is the most important commercial aliphatic dicarboxylic acid in the chemical industry and is primarily used for the production of nylon-6,6 polyamide. The current adipic acid market volume is about 2.6 million tons/y and the average annual demand growth rate forecast to stay at 3-3.5% worldwide. Hitherto, the industrial production of adipic acid is carried out by petroleum-based chemo-catalytic processes from non-renewable fossil fuels. However, in the past years, efforts were made to find alternative routes for adipic acid production from renewable carbon sources by biotechnological processes. Here we review the approaches and the progress made toward bio-based production of adipic acid.

  18. [Effect of graded dietary protein rations on the amino acid content of crude protein in various parts of the gastrointestinal tract and blood fractions of laying hens].

    PubMed

    Gruhn, K; Wiefel, P

    1985-03-01

    Four groups of four colostomized laying hens each received rations only consisting of wheat, vitamins plus a mineral mixture and a graded daily feed supply of 110 g, 88 g, 66 g and 44 g. The determination of amino acids from faeces was carried out after hydrolysis from a 6-day sampling period from the 16 laying hybrids. At the end of the experiment the animals were slaughtered. The corpuscular fractions of the blood, the contents of crop and stomach as well as of the intestines were also hydrolysed and the amino acid content in the crude protein was determined. In addition, the content of free amino acids in the blood plasma was determined. The content of amino acids in the protein of the corpuscular blood fractions remained uninfluenced by the decreasing amino acid and energy supply. The content of free basic amino acids in the blood plasma decreased with the decreasing supply with amino acids and energy, whereas the content of free amino acids with branched chains and hydroxylized ones increased. The content of glutamic acid in the contents of crop and stomach changed considerably in comparison with feed protein. The amino acid values of the crude protein in the contents of the intestines and in faeces to a large extent differ considerably from those of the wheat fed and are approximate values of body protein. Deficient supply with amino acids and energy did not influence the apparent digestibility of the amino acids.

  19. Structure based identification of inhibitors for the SLC13 family of Na+/dicarboxylate cotransporters

    PubMed Central

    Colas, Claire; Pajor, Ana M.; Schlessinger, Avner

    2016-01-01

    In mammals, citric acid cycle intermediates play a key role in regulating various metabolic processes, such as fatty acid synthesis and glycolysis. Members of the sodium dependent SLC13 transporter family mediate the transport of di and tricarboxylates into cells. SLC13 members have been implicated in lifespan extension and resistance to high fat diets, thus, they are emerging drug targets for aging and metabolic disorders. We previously characterized key structural determinants of substrate and cation binding for the human NaDC3/SLC13A3 transporter using a homology model. Here, we combine computational modeling and virtual screening with functional and biochemical testing, to identify 9 previously unknown inhibitors for multiple members of the SLC13 family from human and mouse. Our results reveal previously unknown substrate selectivity determinants for the SLC13 family, including key residues that mediate ligand binding and transport, as well as promiscuous and specific SLC13 small molecule ligands. The newly discovered ligands can serve as chemical tools to further characterize the SLC13 family or as lead molecules for future development of potent inhibitors for the treatment of metabolic diseases and aging. Our results improve our understanding of the structural components that are important for substrate specificity in this physiologically important family as well as in other structurally related transport systems. PMID:26176240

  20. Asymmetric synthesis of enantiomerically and diastereoisomerically enriched 4-[F or Br]-substituted glutamic acids.

    PubMed

    Belokon, Yuri N; Maleev, Victor I; Savel'eva, Tatiana F; Moskalenko, Margarita A; Pripadchev, Dmitri A; Khrustalev, Victor N; Saghiyan, Ashot S

    2010-11-01

    A novel simple synthetic protocol for the preparation of both (2S,4R)- and (2S,4S)-FGlu, applying Michael addition of methyl α-fluoroacrylate to a NiII complex of glycine Schiff base with BPB, was elaborated. In addition, same reaction of mentioned complex with ethyl α-bromoacrylate leads to the NiII complex of the Schiff base of BPB with (2S,4R)-4-bromo-glutamic acid monoester, that can be transformed into the corresponding complexes of 1-aminocyclopropane-1,2-dicarboxylic acid. The decomposition of the diastereoisomerically pure complexes leads to corresponding enantiomerically enriched (ee>98%) amino acids.

  1. State estimation of an acid gas removal (AGR) plant as part of an integrated gasification combined cycle (IGCC) plant with CO2 capture

    SciTech Connect

    Paul, P.; Bhattacharyya, D.; Turton, R.; Zitney, S.

    2012-01-01

    An accurate estimation of process state variables not only can increase the effectiveness and reliability of process measurement technology, but can also enhance plant efficiency, improve control system performance, and increase plant availability. Future integrated gasification combined cycle (IGCC) power plants with CO2 capture will have to satisfy stricter operational and environmental constraints. To operate the IGCC plant without violating stringent environmental emission standards requires accurate estimation of the relevant process state variables, outputs, and disturbances. Unfortunately, a number of these process variables cannot be measured at all, while some of them can be measured, but with low precision, low reliability, or low signal-to-noise ratio. As a result, accurate estimation of the process variables is of great importance to avoid the inherent difficulties associated with the inaccuracy of the data. Motivated by this, the current paper focuses on the state estimation of an acid gas removal (AGR) process as part of an IGCC plant with CO2 capture. This process has extensive heat and mass integration and therefore is very suitable for testing the efficiency of the designed estimators in the presence of complex interactions between process variables. The traditional Kalman filter (KF) (Kalman, 1960) algorithm has been used as a state estimator which resembles that of a predictor-corrector algorithm for solving numerical problems. In traditional KF implementation, good guesses for the process noise covariance matrix (Q) and the measurement noise covariance matrix (R) are required to obtain satisfactory filter performance. However, in the real world, these matrices are unknown and it is difficult to generate good guesses for them. In this paper, use of an adaptive KF will be presented that adapts Q and R at every time step of the algorithm. Results show that very accurate estimations of the desired process states, outputs or disturbances can be

  2. Nanoparticles of Ag with a Pt and Pd rich surface supported on carbon as a new catalyst for the oxygen electroreduction reaction (ORR) in acid electrolytes: Part 2

    NASA Astrophysics Data System (ADS)

    Pech-Pech, I. E.; Gervasio, Dominic F.; Pérez-Robles, J. F.

    2015-02-01

    In the first part of this work, the feasibility of developing a catalyst with high activity for the oxygen electroreduction reaction (ORR) in acid media and with low Pt loading was demonstrated by over coating a silver (Ag) nanoparticle with a shell of platinum (Pt) and palladium (Pd) [7]. The results show that best activity is not directly related to a higher PtPd loading on the surface of the Ag. The best catalyst in a series of this type of catalyst is found with Ag@Pt0.3Pd0.3/C which gives a specific activity for oxygen reduction, jk (in units of mA cm-2 of real area), of 0.07 mA cm-2 at 0.85 V vs. NHE, as compared to 0.04 mA cm-2 when with a commercial Pt on carbon catalyst (Pt20/C) is used in an identical electrode except for the catalyst. The mass activity, jm (in units of mA μg-1 of Pt), for Ag@Pt0.3Pd0.3/C is 0.04 mA μg-1 of Pt at 0.85 V vs. NHE, whereas that for the Pt20/C gives 0.02 mA μg-1 of Pt, showing Ag@Pt0.3Pd0.3/C is a lower-cost catalyst, because using a Ag core and Pd with Pt in the shell gives the highest catalytic activity using less Pt.

  3. Relationship between adipic acid concentration and the core symptoms of autism spectrum disorders.

    PubMed

    Puig-Alcaraz, Carmen; Fuentes-Albero, Milagros; Cauli, Omar

    2016-08-30

    Dicarboxylic acids are an important source of information about metabolism and potential physiopathological alterations in children with autism spectrum disorders (ASDs). We measured the concentration between dicarboxylic adipic and suberic acids in children with an ASD and typically-developing (TD) children and analyzed any relationships between the severity of the core symptoms of ASDs and other clinical features (drugs, supplements, drugs, or diet). The core symptoms of autism were evaluated using the DSM-IV criteria, and adipic acid and suberic acid were measured in urine samples. Overall, no increase in the concentration of adipic acid in children with ASDs compared to TD children, however when considering vitamin B supplementation in ASD there were significantly increased level of urinary adipic acid in children with an ASD not taking vitamin B supplementation compared to supplemented children or to TD children. No significant difference were observed in suberic acid. Interestingly, the increase in adipic acid concentration was significantly and indirectly correlated with the severity of the deficit in socialization and communication skills in children with an ASD. Therefore, therapeutic treatments aimed at decreasing adipic acid concentration might not be beneficial for treating the core symptoms of ASDs.

  4. Dinuclear Calcium Complexes with Intramolecularly NH.O Hydrogen-Bonded Dicarboxylate Ligands.

    PubMed

    Ueyama, Norikazu; Takeda, Jiro; Yamada, Yusuke; Onoda, Akira; Okamura Ta, Taka-aki; Nakamura, Akira

    1999-02-08

    A novel dinuclear calcium complex, [Ca(2){(2-OCO-3-CH(3)C(6)H(3)NHCO)(2)C(CH(3))(2)}(2)(CH(3)OH)(6)] (1), was synthesized as a structural model of 8-coordinated Ca(II) ions in the double calcium-binding site of thermolysin. The complex has four NH.O hydrogen bonds between the amide NH and the carboxylate oxygen anion. Two types of bridging coordination of the carboxylate ligand to Ca(II) were found in 1. The amide NH forms a strong NH.O hydrogen bond with the anionic oxygen of the two carboxylate oxygens. A ligand-exchange reaction between the dinuclear calcium complex and eight equimolar amounts of 2,4,6-trimethylbenzoic acid or 2-CH(3)-6-t-BuCONHC(6)H(3)COOH indicates that the NH.O hydrogen bond prevents the dissociation of the Ca-O bond.

  5. Microwave-assisted melt reaction method for the intercalation of carboxylic acid anions into layered double hydroxides.

    PubMed

    Rosa, Roberto; Leonelli, Cristina; Villa, Carla; Priarone, Giulia

    2013-01-01

    Carboxylic acid anions intercalated layered double hydroxides are currently gaining increasing interest due to their potential applications in pharmaceutical field for controlled drug release in novel tunable drug delivery systems. In this work different aliphatic carboxylic acid anions were intercalated into the interlayers of commercial as well as synthetically prepared layered double hydroxides, through a novel microwave mediated melt reaction approach. The volumetric nature of microwave dielectric heating was exploited in order to rapidly heat the intimate mixture of the lamellar inorganic precursor and the appropriate organic acid, at the melting temperature of the particular mono- or dicarboxylic acid used, reaching the intercalation in approximately two hours treatment.

  6. Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part II. Recovery of Ammonia from Sour Waters

    SciTech Connect

    Poole, L.J.; King, C.J.

    1990-03-01

    Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO{sub 2} and H{sub 2}S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, SUCCiOlC acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility of lactic acid and the tendency of the acid to self-associate. The separate recovery of ammonia and acid gases from sour waters can be achieved by combining steam-stripping of the acid gases with simultaneous removal of ammonia by ext