Sample records for carboxyl functional groups

  1. Structure and function studies on enzymes with a catalytic carboxyl group(s): from ribonuclease T1 to carboxyl peptidases

    PubMed Central

    TAKAHASHI, Kenji

    2013-01-01

    A group of enzymes, mostly hydrolases or certain transferases, utilize one or a few side-chain carboxyl groups of Asp and/or Glu as part of the catalytic machinery at their active sites. This review follows mainly the trail of studies performed by the author and his colleagues on the structure and function of such enzymes, starting from ribonuclease T1, then extending to three major types of carboxyl peptidases including aspartic peptidases, glutamic peptidases and serine-carboxyl peptidases. PMID:23759941

  2. Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term effectiveness of biochar for heavy metal stabilization depends upon biochar’s sorptive property and recalcitrance in soil. To understand the role of carboxyl functional groups on heavy metal stabilization, cottonseed hull biochar and flax shive steam activated biochar having low O/C ratio...

  3. Carboxylic acid functional group analysis using constant neutral loss scanning-mass spectrometry.

    PubMed

    Dron, Julien; Eyglunent, Gregory; Temime-Roussel, Brice; Marchand, Nicolas; Wortham, Henri

    2007-12-12

    The present study describes the development of a new analytical technique for the functional group determination of the carboxylic moiety using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS/MS) operated in the constant neutral loss scanning (CNLS) mode. Carboxylic groups were first derivatized into their corresponding methyl esters by reacting with BF3/methanol mix and the reaction mixture was then directly injected into the APCI chamber. The loss of methanol (m/z = 32 amu) resulting from the fragmentation of the protonated methyl esters was then monitored. Applying this method together with a statistical approach to reference mixtures containing 31 different carboxylic acids at randomly calculated concentrations demonstrated its suitability for quantitative functional group measurements with relative standard deviations below 15% and a detection limit of 0.005 mmol L(-1). Its applicability to environmental matrices was also shown through the determination of carboxylic acid concentrations inside atmospheric aerosol samples. To the best of our knowledge, it is the first time that the tandem mass spectrometry was successfully applied to functional group analysis, offering great perspectives in the characterization of complex mixtures which are prevailing in the field of environmental analysis as well as in the understanding of the chemical processes occurring in these matrices. PMID:18022412

  4. Gas-Phase Reactivity of Carboxylic Acid Functional Groups with Carbodiimides

    PubMed Central

    Prentice, Boone M.; Gilbert, Joshua D.; Stutzman, John R.; Forrest, William P.; McLuckey, Scott A.

    2012-01-01

    Gas-phase modification of carboxylic acid functionalities is performed via ion/ion reactions with carbodiimide reagents [N-cyclohexyl-N?-(2-morpholinoethyl)carbodiimide (CMC) and [3-(3-Ethylcarbodiimide-1-yl)propyl]trimethylaminium (ECPT). Gas-phase ion/ion covalent chemistry requires the formation of a long-lived complex. In this instance, the complex is stabilized by an electrostatic interaction between the fixed charge quaternary ammonium group of the carbodiimide reagent cation and the analyte dianion. Subsequent activation results in characteristic loss of an isocyanate derivative from one side of the carbodiimide functionality, a signature for this covalent chemistry. The resulting amide bond is formed on the analyte at the site of the original carboxylic acid. Reactions involving analytes that do not contain available carboxylic acid groups (e.g., they have been converted to sodium salts) or reagents that do not have the carbodiimide functionality do not undergo a covalent reaction. This chemistry is demonstrated using PAMAM generation 0.5 dendrimer, ethylenediaminetetraacetic acid (EDTA), and the model peptide DGAILDGAILD. This work demonstrates the selective gas-phase covalent modification of carboxylic acid functionalities. PMID:23208744

  5. Carboxyl group (-CO2 H) functionalized coordination polymer nanoparticles as efficient platforms for drug delivery.

    PubMed

    Novio, Fernando; Lorenzo, Julia; Nador, Fabiana; Wnuk, Karolina; Ruiz-Molina, Daniel

    2014-11-17

    Functionalization of nanoparticles can significantly influence their properties and potential applications. Although researchers can now functionalize metal, metal oxide, and organic polymer nanoparticles with a high degree of precision, controlled surface functionalization of nanoscale coordination polymer particles (CPPs) has remained a significant challenge. The lack of methodology is perhaps one of the greatest roadblocks to the advancement of CPPs into high added-value drug delivery applications. Here, we report having achieved this goal through a stepwise formation and functionalization protocol. We fabricated robust nanoparticles with enhanced thermal and colloidal stabilities by incorporation of carboxyl groups and these surface carboxyl groups could be subsequently functionalized through well-known peptide coupling reactions. The set of chemistries that we employed as proof-of-concept enabled a plethora of new functional improvements for the application of CPPs as drug delivery carriers, including enhanced colloidal stabilities and the incorporation of additional functional groups such as polyethylene glycol (PEG) or fluorescent dyes that enabled tracking of their cellular uptake. Finally, we ascertained the cytotoxicity of the new CPP nanoparticles loaded with camptothecin to human breast adenocarcinoma (MCF-7). Efflux measurements show that the encapsulation of camptothecin enhances the potency of the drug 6.5-fold and increases the drug retention within the cell. PMID:25284328

  6. Electronic and optical response of Ru(II) complexes functionalized by methyl, carboxylate groups: joint theoretical and experimental study

    SciTech Connect

    Tretiak, Sergei [Los Alamos National Laboratory

    2008-01-01

    New photovoltaic and photocatalysis applications have been recently proposed based on the hybrid Ru(II)-bipyridine-complex/semiconductor quantum dot systems. In order to attach the complex to the surface of a semiconductor, a linking bridge - a carboxyl group - is added to one or two of the 2,2{prime}-bipyridine ligands. Such changes in the ligand structure, indeed, affect electronic and optical properties and consequently, the charge transfer reactivity of Ru-systems. In this study, we apply both theoretical and experimental approaches to analyze the effects brought by functionalization of bipyridine ligands with the methyl, carboxyl, and carboxilate groups on the electronic structure and optical response of the Ru(II) bipyridine complex. First principle calculations based on density functional theory (DFT) and linear response time dependent density functional theory (TDDFT) are used to simulate the ground and excited-state structures of functionalized Ru-complexes in the gas phase, as well as in acetonitrile solution. In addition, an inelaborate Frenkel exciton model is used to explain the optical activity and splitting patterns of the low-energy excited states. All theoretical results nicely complement experimental absorption spectra of Ru-complexes and contribute to their interpretation. We found that the carboxyl group breaks the degeneracy of two low-energy optically bright excited states and red-shifts the absorption spectrum, while leaves ionization and affinity energies of complexes almost unchanged. Experimental studies show a high probability of deprotonation of the carbboxyl group in the Ru-complexes resulted in a slight blue shift and decrease of intensities of the low energy absorption peaks. Comparison of experimental and theoretical linear response spectra of deprotanated complexes demonstrate strong agreement when acetonitrile solvent is used in simulations. A polar solvent is found to play an important role in calculations of optical spectra: it stabilizes the energy of states localized on the carboxyl or carboxylate groups eliminating artificial charge transport states, which typically appear in TDDFT calculations. Thus, it is validated that the excited-state structure of the functionalized Ru-complexes, specifically in the case of the deprotonated functions, can be accurately modeled by TDDFT with the addition of a dielectric continuum in simulations.

  7. Orthogonal protecting groups for N(alpha)-amino and C-terminal carboxyl functions in solid-phase peptide synthesis.

    PubMed

    Albericio, F

    2000-01-01

    For the controlled synthesis of even the simplest dipeptide, the N(alpha)-amino group of one of the amino acids and the C-terminal carboxyl group of the other should both be blocked with suitable protecting groups. Formation of the desired amide bond can now occur upon activation of the free carboxyl group. After coupling, peptide synthesis can be continued by removal of either of the two protecting groups and coupling with the free C-terminus or N(alpha)-amino group of another protected amino acid. When three functional amino acids are present in the sequence, the side chain of these residues also has to be protected. It is important that there is a high degree of compatibility between the different types of protecting groups such that one type may be removed selectively in the presence of the others. At the end of the synthesis, the protecting groups must be removed to give the desired peptide. Thus, it is clear that the protection scheme adopted is of the utmost importance and makes the difference between success and failure in a given synthesis. Since R. B. Merrifield introduced the solid-phase strategy for the synthesis of peptides, this prerequisite has been readily accepted. This strategy is usually carried out using two main protection schemes: the tert-butoxycarbonyl/benzyl and the 9-flourenylmethoxycarbonyl/tert-butyl methods. However, for the solid-phase preparation of complex or fragile peptides, as well as for the construction of libraries of peptides or small molecules using a combinatorial approach, a range of other protecting groups is also needed. This review summarizes other protecting groups for both the N(alpha)-amino and C-terminal carboxyl functions. PMID:11074410

  8. Cyclopentane-1,3-dione: A Novel Isostere for the Carboxylic Acid Functional Group. Application to the Design of Potent Thromboxane (A2)-Receptor Antagonists

    PubMed Central

    Ballatore, Carlo; Soper, James; Piscitelli, Francesco; James, Michael; Huang, Longchuan; Atasoylu, Onur; Huryn, Donna M.; Trojanowski, John Q.; Lee, Virginia M.-Y.; Brunden, Kurt R.; Smith, Amos B.

    2011-01-01

    Cyclopentane-1,3-diones are known to exhibit pKa values typically in the range of carboxylic acids. To explore the potential of the cyclopentane-1,3-dione unit as a carboxylic acid isostere, the physical-chemical properties of representative congeners were examined and compared with similar derivatives bearing carboxylic acid or tetrazole residues. These studies suggested that cyclopentane-1,3-diones may effectively substitute for the carboxylic acid functional group. To demonstrate the use of the cyclopentane-1,3-dione isostere in drug-design, derivatives of a known thromboxane-A2 prostanoid (TP) receptor antagonist, 3-(3-(2-(4-chlorophenylsulfonamido)ethyl)-phenyl)propanoic acid (12), were synthesized and evaluated in both functional and radioligand-binding assays. A series of mono- and di-substituted cyclopentane-1,3-dione derivatives (41–45) were identified that exhibit nM IC50 and Kd values similar to 12. Collectively, these studies demonstrate that the cyclopentane-1,3-dione moiety comprises a novel isostere of the carboxylic acid functional group. Given the combination of the relatively strong acidity, tunable lipophilicity, and versatility of the structure, the cyclopentane-1,3-dione moiety may constitute a valuable addition to the palette of carboxylic acid isosteres. PMID:21863799

  9. Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells.

    PubMed

    Brennan, Bradley J; Llansola Portolés, Manuel J; Liddell, Paul A; Moore, Thomas A; Moore, Ana L; Gust, Devens

    2013-10-21

    A tetra-arylporphyrin dye was functionalized with three different anchoring groups used to attach molecules to metal oxide surfaces. The physical, photophysical and electrochemical properties of the derivatized porphyrins were studied, and the dyes were then linked to mesoporous TiO2. The anchoring groups were ?-vinyl groups bearing either a carboxylate, a phosphonate or a siloxy moiety. The siloxy linkages were made by treatment of the metal oxide with a silatrane derivative of the porphyrin. The surface binding and lability of the anchored molecules were studied, and dye performance was compared in a dye-sensitized solar cell (DSSC). Transient absorption spectroscopy was used to study charge recombination processes. At comparable surface concentration, the porphyrin showed comparable performance in the DSSC, regardless of the linker. However, the total surface coverage achievable with the carboxylate was about twice that obtainable with the other two linkers, and this led to higher current densities for the carboxylate DSSC. On the other hand, the carboxylate-linked dyes were readily leached from the metal oxide surface under alkaline conditions. The phosphonates were considerably less labile, and the siloxy-linked porphyrins were most resistant to leaching from the surface. The use of silatrane proved to be a practical and convenient way to introduce the siloxy linkages, which can confer greatly increased stability on dye-sensitized electrodes with photoelectrochemical performance comparable to that of the other linkers. PMID:23959453

  10. Ethane-bridged periodic mesoporous organosilicas functionalized with high loadings of carboxylic acid groups: synthesis, bifunctionalization, and fabrication of metal nanoparticles.

    PubMed

    Deka, Juti Rani; Kao, Hsien-Ming; Huang, Shu-Ying; Chang, Wei-Chieh; Ting, Chun-Chiang; Rath, Purna Chandra; Chen, Ching-Shiun

    2014-01-13

    Well-ordered periodic mesoporous organosilicas (PMOs) functionalized with high contents of carboxylic acid (?COOH) groups, up to 85?mol?% based on silica, were synthesized by co-condensation of 1,2-bis(triethoxysilyl)ethane (BTEE) and carboxyethylsilanetriol sodium salt (CES) under acidic conditions by using alkyl poly(oxyethylene) surfactant Brij?76 as a structure-directing agent. A variety of techniques including powder X-ray diffraction (XRD), nitrogen adsorption/desorption, Fourier-transformed infrared (FTIR), transmission electron microscopy (TEM), (13) C- and (29) Si solid-state nuclear magnetic resonance (NMR) were used to characterize the products. The materials thus obtained were used as an effective support to synthesize metal nanoparticles (Ag and Pt) within the channel of 2D hexagonal mesostructure of PMOs. The size and distribution of the nanoparticles were observed to be highly dependent on the interaction between the carboxylic acid functionalized group and the metal precursors. The size of Pt nanoparticles reduced from 3.6 to 2.5?nm and that of Ag nanoparticles reduced from 5.3 to 3.4?nm with the increase in the ?COOH loading from 10 to 50?%. PMID:24338957

  11. Modification of a carboxyl group that appears to cross the permeability barrier in the red blood cell anion transporter

    Microsoft Academic Search

    MICHAEL L. JENNINGS; SHAHLA AL-RHAIYEL

    1988-01-01

    A recently developed method for converting protein carboxyl groups to alcohols has been used to examine the functional role of carboxyl groups in the red blood cell inorganic anion-transport protein (band 3). A major goal of the work was to investigate the carboxyl group that is protonated during the proton- sulfate cotransport that takes place during net chloride-sulfate exchange. Three

  12. Langmuir 1985,1,725-740 725 Acid-Base Behavior of Carboxylic Acid Groups Covalently

    E-print Network

    Deutch, John

    Langmuir 1985,1,725-740 725 Acid-Base Behavior of Carboxylic Acid Groups Covalently Attached: August 7, 1985 Oxidation of polyethylene with chromic acidfsulfuric acid generates a material (PE-C02H) having a high density of carboxylic acid and ketone functionalities in a thin surface layer

  13. Soluble, High Molecular Weight Polysilsesquioxanes with Carboxylate Functionalities

    SciTech Connect

    RAHIMIAN,KAMYAR; LOY,DOUGLAS A.; WHEELER,DAVID R.

    2000-07-14

    Trialkoxysilyl-containing monomers of the type (RO){sub 3}Si(CH{sub 2}){sub 3}C(O)OtBu (R = Me, Et) were prepared by hydrosilation of the corresponding vinylic tert-butyl esters CH{sub 3}CHCH{sub 2}C(O)OtBu. Acid- or base-catalyzed polymerization of the monomers leads to very high molecular weight polymers with relatively narrow polydispersities. The polymerization results in complete condensation of the alkoxy groups while the tert-butyl ester functionality remains fully intact. Partial or full deprotection of the tert-butyl group can easily be achieved to yield the corresponding carboxylic acid polymers. The ester and carboxylic acid functionalities of these new materials allow for their potential use in a variety of applications such as scavenging of heavy metals.

  14. 8, 1000510020, 2008 Carboxyl groups in

    E-print Network

    Boyer, Edmond

    they influence the solubility in water, affect the water activity and surface tension of droplets in the air amounts of water-soluble organic compounds can play an important role in climate change, and they affect on some specific compounds, classes of compounds or functional groups within the water-soluble organic

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

    EPA Science Inventory

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

  16. Characterizations of polyanionic collagen prepared by linking additional carboxylic groups

    Microsoft Academic Search

    R. Sripriya; Ramadhar Kumar; S. Balaji; M. Senthil Kumar; P. K. Sehgal

    2011-01-01

    We have successfully attempted to characterize the polyanionic collagen (PAC) intended for biomaterial and tissue engineering applications. PAC was obtained from type I collagen by chemically linking additional carboxylic groups to the reactive free amino groups. These changes do not affect the ? chains morphology and conformation in collagen. Pure type I collagen obtained from bovine Achilles tendons was allowed

  17. Improved antifouling properties of polyamide nanofiltration membranes by reducing the density of surface carboxyl groups.

    PubMed

    Mo, Yinghui; Tiraferri, Alberto; Yip, Ngai Yin; Adout, Atar; Huang, Xia; Elimelech, Menachem

    2012-12-18

    Carboxyls are inherent functional groups of thin-film composite polyamide nanofiltration (NF) membranes, which may play a role in membrane performance and fouling. Their surface presence is attributed to incomplete reaction of acyl chloride monomers during the membrane active layer synthesis by interfacial polymerization. In order to unravel the effect of carboxyl group density on organic fouling, NF membranes were fabricated by reacting piperazine (PIP) with either isophthaloyl chloride (IPC) or the more commonly used trimesoyl chloride (TMC). Fouling experiments were conducted with alginate as a model hydrophilic organic foulant in a solution, simulating the composition of municipal secondary effluent. Improved antifouling properties were observed for the IPC membrane, which exhibited lower flux decline (40%) and significantly greater fouling reversibility or cleaning efficiency (74%) than the TMC membrane (51% flux decline and 40% cleaning efficiency). Surface characterization revealed that there was a substantial difference in the density of surface carboxyl groups between the IPC and TMC membranes, while other surface properties were comparable. The role of carboxyl groups was elucidated by measurements of foulant-surface intermolecular forces by atomic force microscopy, which showed lower adhesion forces and rupture distances for the IPC membrane compared to TMC membranes in the presence of calcium ions in solution. Our results demonstrated that a decrease in surface carboxyl group density of polyamide membranes fabricated with IPC monomers can prevent calcium bridging with alginate and, thus, improve membrane antifouling properties. PMID:23205860

  18. Group composition of carboxylic acids from West Siberian crude oils

    SciTech Connect

    Zhic'tsov, N.I.; Ershov, V.A.; Samokhvalova, G.I.

    1982-11-01

    Performs mass spectrometric analyses of carboxylic acids from crudes of different geologic ages using an MAT 111 chromatograph/mass spectrometer equipped with systems for direct sample introduction and temperature programming. Explains that as an analytical characteristic for determination of the group composition and molecular weight distribution of the carboxylic, the relative intensities of peaks of the ions (M-15)/sup +/ were selected in the mass spectra of their trimethylsilyl esters (TMSES), obtained at different temperatures of the sample in the ion source. Concludes that the results from an analysis of the group composition of the carboxylic acids in crude oils from 10 deposits of various geological ages indicate that as the metamorphism factor increases, there is a decrease in the content of naphthenic acids in the acid concentrates from the crudes. Offers the possibility that for higher reservoir temperatures and greater depths of occurrence of the oil-enclosing rock, the reducing factor dominates over the oxidizing factor in making up the composition of the petroleum acids.

  19. Carboxylate groups play a major role in antitumor activity of Ganoderma applanatum polysaccharide.

    PubMed

    Sun, Xiaobo; Zhao, Chen; Pan, Wei; Wang, Jinping; Wang, Weijun

    2015-06-01

    In this paper, the structure difference between the polysaccharides isolated from fruit bodies (FGAP) and submerged fermentation system (SGAP) of Ganoderma applanatum was investigated by means of GPC, HPLC and IR, respectively. And their antitumor activities were evaluated against Sarcoma 180 in vivo. The results showed that FGAP and SGAP were typical polysaccharides with different molecular weights, monosaccharide components, and functional groups. Closely related to the distinct structures, FGAP exhibited a better antitumor activity than SGAP. Moreover, since FGAP contained carboxylate groups rather than SGAP, such groups were chemically introduced into SGAP (CSGAP) by carboxymethylation in order to identify their contribution to antitumor activity. The results demonstrated that the inhibition of CSGAP against Sarcoma 180 in vivo was significantly enhanced by comparison to the native SGAP and even higher than that of FGAP, suggesting that the carboxylate groups played a major role in antitumor activity of G. applanatum polysaccharide. PMID:25843860

  20. Modification of carboxyl groups in botulinum neurotoxin types A and E.

    PubMed

    Woody, M A; Herian, A; DasGupta, B R

    1989-01-01

    Effects of chemical modification of carboxyl groups of botulinum neurotoxin serotypes A and E were studied by using a water soluble carbodiimide-nucleophile reaction that is highly specific for modifying carboxyl groups of proteins. In both types A and E, increasing levels of the reagents, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and norleucine methyl ester or glycine methyl ester, at pH 4.8 caused increased loss of toxicity. More glycine could be incorporated than norleucine. Amino acid analysis did not reveal modification of any amino acid residue other than carboxyl groups (possible reaction of sulfhydryl groups was not studied). Loss of one carboxyl group did not severely affect toxicity, but modification of three carboxyl groups caused greater than 95% detoxification in both types. Complete detoxification could not be achieved with any amount of the reagents. Modification of three to five carboxyl groups did not affect serological activity. PMID:2510369

  1. Temperature dependence of C-terminal carboxylic group IR absorptions in the amide I? region

    NASA Astrophysics Data System (ADS)

    Anderson, Benjamin A.; Literati, Alex; Ball, Borden; Kubelka, Jan

    2015-01-01

    Studies of structural changes in peptides and proteins using IR spectroscopy often rely on subtle changes in the amide I? band as a function of temperature. However, these changes can be obscured by the overlap with other absorptions, namely the side-chain and terminal carboxylic groups. The former were the subject of our previous report (Anderson et al., 2014). In this paper we investigate the IR spectra of the asymmetric stretch of ?-carboxylic groups for amino acids representing all major types (Gly, Ala, Val, Leu, Ser, Thr, Asp, Glu, Lys, Asn, His, Trp, Pro) as well as the C-terminal groups of three dipeptides (Gly-Gly, Gly-Ala, Ala-Gly) in D2O at neutral pH. Experimental temperature dependent IR spectra were analyzed by fitting of both symmetric and asymmetric pseudo-Voigt functions. Qualitatively the spectra exhibit shifts to higher frequency, loss in intensity and narrowing with increased temperature, similar to that observed previously for the side-chain carboxylic groups of Asp. The observed dependence of the band parameters (frequency, intensity, width and shape) on temperature is in all cases linear: simple linear regression is therefore used to describe the spectral changes. The spectral parameters vary between individual amino acids and show systematic differences between the free amino acids and dipeptides, particularly in the absolute peak frequencies, but the temperature variations are comparable. The relative variations between the dipeptide spectral parameters are most sensitive to the C-terminal amino acid, and follow the trends observed in the free amino acid spectra. General rules for modeling the ?-carboxylic IR absorption bands in peptides and proteins as the function of temperature are proposed.

  2. Carboxylic Acids as A Traceless Activation Group for Conjugate Additions: A Three-Step Synthesis of ()-Pregabalin

    E-print Network

    MacMillan, David W. C.

    electrode (SCE) in CH3CN).9 We assumed that base-promoted deprotonation of a carboxylic acid substrateCarboxylic Acids as A Traceless Activation Group for Conjugate Additions: A Three-Step Synthesis: The direct application of carboxylic acids as a traceless activation group for radical Michael additions has

  3. Structural environments of carboxyl groups in natural organic molecules from terrestrial systems. Part 1: Infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Hay, Michael B.; Myneni, Satish C. B.

    2007-07-01

    Carboxyls play an important role in the chemistry of natural organic molecules (NOM) in the environment, and their behavior is dependent on local structural environment within the macromolecule. We studied the structural environments of carboxyl groups in dissolved NOM from the Pine Barrens (New Jersey, USA), and IHSS NOM isolates from soils and river waters using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. It is well established that the energies of the asymmetric stretching vibrations of the carboxylate anion (COO -) are sensitive to the structural environment of the carboxyl group. These energies were compiled from previous infrared studies on small organic acids for a wide variety of carboxyl structural environments and compared with the carboxyl spectral features of the NOM samples. We found that the asymmetric stretching peaks for all NOM samples occur within a narrow range centered at 1578 cm -1, suggesting that all NOM samples examined primarily contain very similar carboxyl structures, independent of sample source and isolation techniques employed. The small aliphatic acids containing hydroxyl (e.g., D-lactate, gluconate), ether/ester (methoxyacetate, acetoxyacetate), and carboxylate (malonate) substitutions on the ?-carbon, and the aromatic acids salicylate ( ortho-OH) and furancarboxylate ( O-heterocycle), exhibit strong overlap with the NOM range, indicating that similar structures may be common in NOM. The width of the asymmetric peak suggests that the structural heterogeneity among the predominant carboxyl configurations in NOM is small. Changes in peak area with pH at energies distant from the peak at 1578 cm -1, however, may be indicative of a small fraction of other aromatic carboxyls and aliphatic structures lacking ?-substitution. This information is important in understanding NOM-metal and mineral-surface complexation, and in building appropriate structural and mechanistic models of humic materials.

  4. Enantioselective synthesis of ?-hydroxy carboxylic acids: direct conversion of ?-oxocarboxylic acids to enantiomerically enriched ?-hydroxy carboxylic acids via neighboring group control

    Microsoft Academic Search

    Zhe Wang; Chunlin Zhao; Michael E. Pierce; Joseph M. Fortunak

    1999-01-01

    ?-Oxocarboxylic acids can be reduced to the corresponding ?-hydroxy carboxylic acids employing DIP-Cl™ as a reducing agent. The ?-carboxylic substituent exerts a remarkable neighboring group effect on the reduction. The reaction presumably proceeds in an intramolecular fashion through a `rigid' bicyclic transition state assembly, which produces enantioselectivities approaching 99%.

  5. Measuring the concentration of carboxylic acid groups in torrefied spruce wood.

    PubMed

    Khazraie Shoulaifar, Tooran; Demartini, Nikolai; Ivaska, Ari; Fardim, Pedro; Hupa, Mikko

    2012-11-01

    Torrefaction is moderate thermal treatment (?200-300°C) to improve the energy density, handling and storage properties of biomass fuels. In biomass, carboxylic sites are partially responsible for its hygroscopic. These sites are degraded to varying extents during torrefaction. In this paper, we apply methylene blue sorption and potentiometric titration to measure the concentration of carboxylic acid groups in spruce wood torrefied for 30min at temperatures between 180 and 300°C. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic acid sites. Thus both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction which provides new information to the chemical changes occurring during torrefaction. PMID:22940339

  6. Effect of carboxylic end groups on thermooxidative stability of PET and PBT

    Microsoft Academic Search

    Dimitris N. Bikiaris; George P. Karayannidis

    1999-01-01

    A series of poly(ethylene terephthalate) and of poly(butylene terephthalate) samples containing different amounts of carboxyl end groups were prepared by chain-extension reaction with diepoxides. The effect of the carboxyl content on thermooxidative degradation was studied, using as criteria the induction period of oxidation and the stabilisation coefficient, both obtained by differential scanning calorimetry during isothermal or dynamic heating of the

  7. Polyacetal Carboxylic Acids: a New Group of Antiviral Polyanions

    PubMed Central

    Claes, P.; Billiau, A.; De Clercq, E.; Desmyter, J.; Schonne, E.; Vanderhaeghe, H.; De Somer, P.

    1970-01-01

    Chlorite-oxidized oxypolysaccharides are polyacetal carboxylic acids. They inhibited the cytopathic effect of vesicular stomatitis virus in mouse embryo cell cultures challenged at low input multiplicity. After intraperitoneal injection of these compounds in mice, interferon appeared in the circulation. The compounds also protected mice against lethal mengovirus infection and against the development of experimental pox lesions on the tail. Chlorite-oxidized oxyamylose was antiviral only when at least 64% of the glucopyranose units were oxidized, an observation which suggested a correlation between charge density and antiviral effect. The antiviral activity was also influenced by the molecular weight, as demonstrated by the fact that chlorite-oxidized dextrans which had a high intrinsic viscosity were more active than those with low intrinsic viscosity. PMID:4314553

  8. Electrical and physical characterization of bilayer carboxylic acid-functionalized molecular layers.

    PubMed

    Pookpanratana, Sujitra; Robertson, Joseph W F; Jaye, Cherno; Fischer, Daniel A; Richter, Curt A; Hacker, Christina A

    2013-02-12

    We have used flip chip lamination (FCL) to form monolayer and bilayer molecular junctions of carboxylic acid-containing molecules with Cu atom incorporation. Carboxylic acid-terminated monolayers are self-assembled onto ultrasmooth Au by using thiol chemistry and grafted onto n-type Si. Prior to junction formation, monolayers are physically characterized by using polarized infrared absorption spectroscopy, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy, confirming the molecular quality and functional group termination. FCL was used to form monolayer junctions onto H-terminated Si or bilayer junctions of carboxylic acid monolayers on Au and Si. From the electrical measurements, we find that the current through the junction is attenuated as the effective molecular length within the junction increases, indicating that molecules are electrically active within the junction. We find that the electronic transport through the bilayer junction saturates at very thick effective distances possibly because of another electron-transport mechanism that is not nonresonant tunneling as a result of trapped defects or sequential tunneling. In addition, bilayer junctions are fabricated with and without Cu atoms, and we find that the electron transport is not distinguishably different when Cu atoms are within the bilayer. PMID:23362920

  9. Adsorption of Co(II) by a carboxylate-functionalized polyacrylamide grafted lignocellulosics.

    PubMed

    Shibi, I G; Anirudhan, T S

    2005-02-01

    A new adsorbent (PGBS-COOH) having carboxylate functional group at the chain end was synthesized by graft copolymerization of acrylamide onto banana stalk, BS (Musa Paradisiaca) using ferrous ammonium sulphate/H2O2 redox initiator system. The efficiency of the adsorbent in the removal of cobalt [Co(II)] from water was investigated using batch adsorption technique. The adsorbent exhibits very high adsorption potential for Co(II) and under optimum conditions more than 99% removal was achieved. The maximum adsorption capacity was observed at the pH range 6.5-9.0. The equilibrium isotherm data were analysed using three isotherm models, Langmuir, Freundlich and Scatchard, to determine the best fit equation for the sorption of Co(II) on the PGBS-COOH. A comparative study with a commercial cation exchanger, Ceralite IRC-50, having carboxylate functional group showed that PGBS-COOH is 2.8 times more effective compared to Ceralite IRC-50 at 30 degrees C. Synthetic nuclear power plant coolant water samples were also treated by the adsorbent to demonstrate its efficiency in removing Co(II) from water in the presence of other metal ions. Acid regeneration was tried for several cycles to recover the adsorbed metal ions and also to restore the sorbent to its original state. PMID:15664619

  10. Human Delta1-pyrroline-5-carboxylate synthase: function and regulation.

    PubMed

    Hu, C-A A; Khalil, S; Zhaorigetu, S; Liu, Z; Tyler, M; Wan, G; Valle, D

    2008-11-01

    Mammalian Delta(1)-pyrroline-5-carboxylate synthase (P5CS) is a bifunctional ATP- and NAD(P)H-dependent mitochondrial enzyme that catalyzes the coupled phosphorylation and reduction-conversion of L: -glutamate to P5C, a pivotal step in the biosynthesis of L: -proline, L: -ornithine and L: -arginine. Previously, we reported cloning and characterization of two P5CS transcript variants generated by exon sliding that encode two protein isoforms differing only by a two amino acid-insert at the N-terminus of the gamma-glutamyl kinase active site. The short form (P5CS.short) is highly expressed in the gut and is inhibited by ornithine. In contrast, the long form (P5CS.long) is expressed ubiquitously and is insensitive to ornithine. Interestingly, we found that all the established human cell lines we have studied expressed P5CS.long but not P5CS.short. In addition, expression of P5CS.long can be modulated by hormones: downregulation by hydrocortisone and dexamethasone and upregulation by estradiol, for example. Using a quantitative proteomic approach, we showed that P5CS.long is upregulated by p53 in p53-induced apoptosis in DLD-1 colorectal cancer cells. Functional genomic analysis confirmed that there are two p53-binding consensus sequences in the promoter region and in the intron 1 of the human P5CS gene. Interestingly, overexpression of P5CS by adenoviruses harboring P5CS.long or P5CS.short in various cell types has no effect on cell growth or survival. It would be of importance to further investigate the role of P5CS as a p53 downstream effector and how P5CS.short expression is regulated by hormones and factors of alternative splicing in cells isolated from model animals. PMID:18401542

  11. Quantum chemical investigation of the primary thermal pyrolysis reactions of the sodium carboxylate group in a brown coal model.

    PubMed

    Li, Jian; Zhang, Baisheng; Zhang, Zhiqiang; Yan, Kefeng; Kang, Lixun

    2014-12-01

    The primary pyrolysis mechanisms of the sodium carboxylate group in sodium benzoate-used as a model compound of brown coal-were studied by performing quantum chemical computations using B3LYP and the CBS method. Various possible reaction pathways involving reactions such as unimolecular and bimolecular decarboxylation and decarbonylation, crosslinking, and radical attack in the brown coal matrix were explored. Without the participation of reactive radicals, unimolecular decarboxylation to release CO2 was calculated to be the most energetically favorable primary reaction pathway at the B3LYP/6-311+G (d, p) level of theory, and was also found to be more energetically favorable than decarboxylation of an carboxylic acid group. When CBS-QBS results were included, crosslinking between the sodium carboxylate group and the carboxylic acid and the decarboxylation of the sodium carboxylate group (catalyzed by the phenolic hydroxyl group) were found to be possible; this pathway competes with unimolecular decarboxylation of the sodium carboxylate group. Provided that H and CH3 radicals are present in the brown coal matrix and can access the sodium carboxylate group, accelerated pyrolysis of the sodium carboxylate group becomes feasible, leading to the release of an Na atom or an NaCO2 radical at the B3LYP/6-311+G (d, p) or CBS-QB3 level of theory, respectively. PMID:25451141

  12. General and Practical Carboxyl-Group-Directed Remote C–H Oxygenation Reactions of Arenes

    PubMed Central

    Wang, Yang; Gulevich, Anton V.

    2013-01-01

    Two methods for remote aromatic C–H oxygenation reaction have been developed. Method 1, the Cu-catalyzed oxygenation reaction is highly efficient for cyclization of electron-neutral and electron-rich biaryl carboxylic acids into 3,4-benzocoumarins. Method 2, the K2S2O8-mediated oxygenation reaction, is more general and practical for cyclization of substrates with electron- donating and -withdrawing groups (see scheme). PMID:24150970

  13. Removal of transition metals from dilute aqueous solution by carboxylic acid group containing absorbent polymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new carboxylic acid group containing resin with cation exchange capacity, 12.67 meq/g has been used to remove Cu2+, Co2+ and Ni2+ ions from dilute aqueous solution. The resin has Cu2+, Co2+ and Ni2+ removal capacity, 216 mg/g, 154 mg/g and 180 mg/g, respectively. The selectivity of the resin to ...

  14. Human ? 1 -pyrroline-5-carboxylate synthase: function and regulation

    Microsoft Academic Search

    C.-A. A. Hu; S. Khalil; S. Zhaorigetu; Z. Liu; M. Tyler; G. Wan; D. Valle

    2008-01-01

    Mammalian ?1-pyrroline-5-carboxylate synthase (P5CS) is a bifunctional ATP- and NAD(P)H-dependent mitochondrial enzyme that catalyzes\\u000a the coupled phosphorylation and reduction-conversion of l-glutamate to P5C, a pivotal step in the biosynthesis of l-proline, l-ornithine and l-arginine. Previously, we reported cloning and characterization of two P5CS transcript variants generated by exon sliding\\u000a that encode two protein isoforms differing only by a two amino

  15. Surface functional groups on acid-activated nutshell carbons

    Microsoft Academic Search

    Christopher A. Toles; Wayne E. Marshall; Mitchell M. Johns

    1999-01-01

    Nutshells from agriculturally important nut crops (almond, black walnut, English walnut, macadamia nut and pecan) were converted to granular activated carbon using phosphoric acid activation in nitrogen or air. Surface functional groups (carbonyl, phenols, lactones, carboxyl) were quantified by titration with bases of different ionization potential. The degree of copper uptake was correlated with the presence of various functional groups

  16. Hemocompatibilty of new ionic polyurethanes: influence of carboxylic group insertion modes.

    PubMed

    Poussard, L; Burel, F; Couvercelle, J-P; Merhi, Y; Tabrizian, M; Bunel, C

    2004-08-01

    New segmented polyurethane (PU) anionomers based on hydroxytelechelic polybutadiene (HTPB) were synthesized via two environment-friendly chemical routes. The effects of carboxylic content and ion incorporation mode on the surface properties were investigated by mean of water absorption analysis and static contact angle measurements using water, diiodomethane, formamide and ethylene glycol. Blood compatibility of the PUs was evaluated by in vitro adhesion assay using 111In-radiolabeled platelet rich plasma and 125I-fibrinogen. The morphology of platelet adhesion was also observed by scanning electron microscopy (SEM). Results were compared with a biomedical-grade PU, Pellethane. Insertion of the carboxylic groups on the soft segments (S-alpha series), using thioglycolic acid (TGA), increases surface hydrophilicity, limits water uptake (5%, for an ion content of 3.6 wt%), and reduces platelet adhesion and fibrinogen adsorption on the PUs' surfaces. In contrast, the classical insertion onto the hard segment (H-alpha series), using dimethylolpropionate (DMPA) as chain extender, leads to high water uptake (18%, for an ion content of 3.6 wt%) and promotes platelet and fibrinogen adhesion. SEM analyses of the non-ionic PUs exhibited surfaces with adhered platelets which underwent morphological modification. Similarly, the H-alpha ionic PUs show adherent and activated platelets. On the contrary, no platelet morphology changes were observed on the S-alpha ionic surfaces. In conclusion, insertion of carboxyl groups on the soft segments of PUs reduces their thrombogenicity. PMID:15020121

  17. Snythesis and characterization of the first main group oxo-centered trinuclear carboxylate

    NASA Technical Reports Server (NTRS)

    Duraj, Stan A.

    1994-01-01

    The synthesis and structural characterization of the first main group oxo-centered, trinuclear carboxylato-bridged species is reported, namely (Ga3(mu(sub 3)-O) (mu-O2CC6H5)6 (4-Mepy)3) GaCl4 center dot 4-Mepy (compound 1), where 4-Mepy is 4-methylpyridine. Compound 1 is a main group example of a well-established class of complexes, referred to as 'basic carboxylates' of the general formula (M3(mu(sub 3)-O)(mu-O2CR)6L3)(+), previously observed only for transition metals.

  18. Effects of chemical modification of carboxyl groups on the voltage-clamped nerve fiber of the frog

    Microsoft Academic Search

    Michael Rack; Karl-Heinz Woll

    1984-01-01

    Summary Voltage-clamped single nerve fibers of the frogRana esculenta were treated with the carboxyl group activating reagent N-ethoxy-carbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) in the presence of different primary amines and without added amine. Carboxyl groups form stable amide bonds with primary amines in the presence of EEDQ. EEDQ treatment reduced the sodium current considerably and irreversibly, regardless of the presence of a primary

  19. Amphiphilic copolymers with pendent carboxyl groups for high-efficiency loading and controlled release of doxorubicin.

    PubMed

    Li, You-Mei; Jiang, Tao; Lv, Yin; Wu, Yan; He, Feng; Zhuo, Ren-Xi

    2015-08-01

    In this paper, biodegradable amphiphilic block copolymer based on methoxy poly(ethylene glycol)-b-poly(5-allyloxy-1,3-dioxan-2-one) (mPEG-b-PATMC) was successfully synthesized in bulk using immobilized porcine pancreas lipase (IPPL) as the catalyst. After thiol-ene "click" reactions occur between thiol group of thioglycolic acid and carbon-carbon double bonds of PATMC segments, the pendent carboxyl-modified copolymer mPEG-b-PATMC-g-SCH2COOH was obtained for high-efficiency loading and controlled release of doxorubicin (DOX) to cancer cells. Both the carboxyl-modified and unmodified copolymers could self-assemble to form nano-sized micelles in aqueous solution, while transmission electron microscopy (TEM) observation showed that the micelles dispersed in spherical shape with nano-size before and after DOX loading. Compared with the unmodified copolymer, the pendent carboxyl-modified structure in mPEG-b-PATMC-g-SCH2COOH could markedly enhance the drug-loading capacity and entrapment efficiency via the electrostatic interaction. The in vitro release studies showed more sustained drug release behavior of mPEG-b-PATMC-g-SCH2COOH without an initial burst, which could be further adjusted by the conditions of ionic strength and pH. Confocal laser scanning microscopy (CLSM) indicated efficient cellular uptake of DOX delivered by mPEG-b-PATMC-g-SCH2COOH, while MTT assays also demonstrated potent cytotoxic activity against HeLa cells. PMID:26005931

  20. Detection of a CO and NH3 gas mixture using carboxylic acid-functionalized single-walled carbon nanotubes

    PubMed Central

    2013-01-01

    Carbon nanotubes (CNT) are extremely sensitive to environmental gases. However, detection of mixture gas is still a challenge. Here, we report that 10 ppm of carbon monoxide (CO) and ammonia (NH3) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH3 gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH3 gas. The sensing properties and effect of carboxylic acid group were demonstrated, and C-SWCNT sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective detection method of CO and NH3 mixture gas. PMID:23286690

  1. Synthesis and characterization of a novel carboxyl group containing (co)polyimide with sulfur in the polymer backbone

    PubMed Central

    Mrsevic, Miroslav; Düsselberg, David

    2012-01-01

    Summary Soluble functional (co)polyimides are of great interest in the area of separation processes or optical applications, due to their excellent mechanical-, thermal- and optical properties, their superior processability and the ability to adapt their properties to a wide range of special applications. Therefore, two series of novel (co)polyimides containing fluorinated sulfur- and carboxylic acid groups consisting of 4,4?-(hexafluoroisopropylidene)di(phthalic anhydride) (6FDA), 3,5-diaminobenzoic acid (DABA), 4,4?-diaminodiphenylsulfide (4,4?-SDA) and 3,3?-diaminodiphenylsulfone (3,3?-DDS) were synthesized in a two-step polycondensation reaction. The synthesized copolymers were characterized by using NMR, FTIR, GPC, and DSC. Furthermore, with regard to processing and potential applications, the thermal stability, solubility in common organic solvents, moisture uptake, and transparency were investigated. Compared to commercially available transparent polymers, i.e., polymethylmethacrylate and cycloolefin polymers, the sulfur (co)polyimides containing carboxyl groups showed much higher glass-transition temperatures, comparably low moisture uptake and high transmission at the sodium D-line. Furthermore, good solubility in commonly used organic solvents makes them very attractive as high-performance coating materials. PMID:23015826

  2. Binding properties of solubilized gonadotropin-releasing hormone receptor: role of carboxylic groups

    SciTech Connect

    Hazum, E.

    1987-11-03

    The interaction of /sup 125/I-buserelin, a superactive agonist of gonadotropin-releasing hormone (GnRH), with solubilized GnRH receptor was studied. The highest specific binding of /sup 125/I-buserelin to solubilized GnRH receptor is evident at 4/sup 0/C, and equilibrium is reached after 2 h of incubation. The soluble receptor retained 100% of the original binding activity when kept at 4 or 22/sup 0/C for 60 min. Mono- and divalent cations inhibited, in a concentration-dependent manner, the binding of /sup 125/I-buserelin to solubilized GnRH receptor. Monovalent cations require higher concentrations than divalent cations to inhibit the binding. Since the order of potency with the divalent cations was identical with that of their association constants to dicarboxylic compounds, it is suggested that there are at least two carboxylic groups of the receptor that participate in the binding of the hormone. The carboxyl groups of sialic acid residues are not absolutely required for GnRH binding since the binding of /sup 125/I-buserelin to solubilized GnRH receptor was only slightly affected by pretreatment with neuraminidase and wheat germ agglutinin. The finding that polylysines stimulate luteinizing hormone (LH) release from pituitary cell cultures with the same efficacy as GnRH suggest that simple charge interactions can induce LH release. According to these results, the authors propose that the driving force for the formation of the hormone-receptor complex is an ionic interaction between the positively charged amino acid arginine in position 8 and the carboxyl groups in the binding site.

  3. Preferential interaction of Na+ over K+ with carboxylate-functionalized silver nanoparticles.

    PubMed

    Pokhrel, Lok R; Andersen, Christian P; Rygiewicz, Paul T; Johnson, Mark G

    2014-08-15

    Elucidating mechanistic interactions between monovalent cations (Na(+)/K(+)) and engineered nanoparticle surfaces to alter particle stability in polar media have received little attention. We investigated relative preferential interaction of Na(+) and K(+) with carboxylate-functionalized silver nanoparticles (carboxylate-AgNPs) to determine if interaction preference followed the Hofmeister series (Na(+)>K(+)). We hypothesized that Na(+) will show greater affinity than K(+) to pair with carboxylates on AgNP surfaces, thereby destabilizing the colloidal system. Destabilization upon Na(+) or K(+) interacting with carboxylate-AgNPs was evaluated probing changes in multiple physicochemical characteristics: surface plasmon resonance/optical absorbance, electrical conductivity, pH, hydrodynamic diameter, electrophoretic mobility, surface charge, amount of Na(+)/K(+) directly associated with AgNPs, and Ag(+) dissociation kinetics. We show that Na(+) and K(+) react differently, indicating local Na(+) pairing with carboxylates on AgNP surfaces is kinetically faster and remarkably favored over K(+), thus supporting Hofmeister ordering. Our results suggest that AgNPs may transform into micron-size aggregates upon release into aqueous environments and that the fate of such aggregates may need consideration when assessing environmental risk. PMID:24840275

  4. Novel blue-emitting carboxyl-functionalized poly(arylene ether nitrile)s with excellent thermal

    E-print Network

    Lin, Zhiqun

    Novel blue-emitting carboxyl-functionalized poly(arylene ether nitrile)s with excellent thermal*b A series of novel carboxyl-functionalized poly(arylene ether nitrile)s (CPAENs) were synthesized via(arylene ether)s such as poly(arylene ether sulfone)s, poly(arylene ether ketone)s, poly(arylene ether nitrile

  5. Chemical Derivatization of Peptide Carboxyl Groups for Highly Efficient Electron Transfer Dissociation

    NASA Astrophysics Data System (ADS)

    Frey, Brian L.; Ladror, Daniel T.; Sondalle, Samuel B.; Krusemark, Casey J.; Jue, April L.; Coon, Joshua J.; Smith, Lloyd M.

    2013-11-01

    The carboxyl groups of tryptic peptides were derivatized with a tertiary or quaternary amine labeling reagent to generate more highly charged peptide ions that fragment efficiently by electron transfer dissociation (ETD). All peptide carboxyl groups—aspartic and glutamic acid side-chains as well as C-termini—were derivatized with an average reaction efficiency of 99 %. This nearly complete labeling avoids making complex peptide mixtures even more complex because of partially-labeled products, and it allows the use of static modifications during database searching. Alkyl tertiary amines were found to be the optimal labeling reagent among the four types tested. Charge states are substantially higher for derivatized peptides: a modified tryptic digest of bovine serum albumin (BSA) generates ~90% of its precursor ions with z > 2, compared with less than 40 % for the unmodified sample. The increased charge density of modified peptide ions yields highly efficient ETD fragmentation, leading to many additional peptide identifications and higher sequence coverage (e.g., 70 % for modified versus only 43 % for unmodified BSA). The utility of this labeling strategy was demonstrated on a tryptic digest of ribosomal proteins isolated from yeast cells. Peptide derivatization of this sample produced an increase in the number of identified proteins, a >50 % increase in the sequence coverage of these proteins, and a doubling of the number of peptide spectral matches. This carboxyl derivatization strategy greatly improves proteome coverage obtained from ETD-MS/MS of tryptic digests, and we anticipate that it will also enhance identification and localization of post-translational modifications.

  6. Connecting terminal carboxylate groups in nine-coordinate lanthanide podates: consequences on the thermodynamic, structural, electronic, and photophysical properties.

    PubMed

    Senegas, Jean-Michel; Bernardinelli, Gérald; Imbert, Daniel; Bünzli, Jean-Claude G; Morgantini, Pierre-Yves; Weber, Jacques; Piguet, Claude

    2003-07-28

    The hydrolysis of terminal (t)butyl-ester groups provides the novel nonadentate podand tris[2-[N-methylcarbamoyl-(6-carboxypyridine-2)-ethyl]amine] (L13) which exists as a mixture of slowly interconverting conformers in solution. At pH = 8.0 in water, its deprotonated form [L13 - 3H](3-) reacts with Ln(ClO(4))(3) to give the poorly soluble and stable podates [Ln(L13 - 3H)] (log(beta(110)) = 6.7-7.0, Ln = La-Lu). The isolated complexes [Ln(L13 - 3H)](H(2)O)(7) (Ln = Eu, 8; Tb, 9; Lu, 10) are isostructural, and their crystal structures show Ln(III) to be nine-coordinate in a pseudotricapped trigonal prismatic site defined by the donor atoms of the three helically wrapped tridentate binding units of L13. The Ln-O(carboxamide) bonds are only marginally longer than the Ln-O(carboxylate) bonds in [Ln(L13 - 3H)], thus producing a regular triple helix around Ln(III) which reverses its screw direction within the covalent Me-TREN tripod. High-resolution emission spectroscopy demonstrates that (i) the replacement of terminal carboxamides with carboxylates induces only minor electronic changes for the metallic site, (ii) the solid-state structure is maintained in water, and (iii) the metal in the podate is efficiently protected from interactions with solvent molecules. The absolute quantum yields obtained for [Eu(L13 - 3H)] (Phi(Eu)(tot)= 1.8 x 10(-3)) and [Tb(L13 - 3H)] (Phi(Eu)(tot)= 8.9 x 10(-3)) in water remain modest and strongly contrast with that obtained for the lanthanide luminescence step (Phi(Eu) = 0.28). Detailed photophysical studies assign this discrepancy to the small energy gap between the ligand-centered singlet ((1)pi pi*) and triplet ((3)pi pi*) states which limits the efficiency of the intersystem crossing process. Theoretical TDDFT calculations suggest that the connection of a carboxylate group to the central pyridine ring prevents the sizable stabilization of the triplet state required for an efficient sensitization process. The thermodynamic and electronic origins of the advantages (stability, lanthanide quantum yield) and drawbacks (solubility, sensitization) brought by the "carboxylate effect" in lanthanide complexes are evaluated for programming predetermined properties in functional devices. PMID:12870960

  7. The role played by the amino and carboxyl groups in the formation of the geometric and electronic structure of phenoxy substituted cyclophosphazenes

    NASA Astrophysics Data System (ADS)

    Bobrov, M. F.; Tsirel'Son, V. G.

    2008-12-01

    A quantum-topological analysis of the electron density calculated by the density functional theory method in the B3LYP/6-31G( d,p) approximation was performed to determine and quantitatively characterize four types of noncovalent interactions in mono-and disubstituted 4-aminophenoxy-and 4-carboxyphenoxycyclotriphosphazenes P3N3Cl5OC6H4NH2, P3N3Cl4(OC6H4NH2)2, P3N3Cl5OC6H4COOH, and P3N3Cl4(OC6H4COOH)2. These are C-H…N hydrogen bonds between a nitrogen atom of the phosphazene ring and a hydrogen atom of the benzene ring, C-H…C interactions between a carbon atom of one phenoxy group and a hydrogen atom of the other such group (C-H…? interactions), N-H…N interactions between nitrogen and hydrogen atoms of neighboring amino groups, and C-O…C interactions between oxygen atoms of neighboring carboxyl groups. This system of noncovalent bonding interactions determines the mutual orientation of oxyphenyl fragments. The total energy of interatomic contacts estimated from the local potential energy of electrons at the corresponding critical bond points is larger for the amino than for the carboxyl group. It follows that the amino group has the strongest effect on the mutual orientation of oxyphenyl fragments. The effect of the carboxyl group is weaker.

  8. Functional Group Analysis.

    ERIC Educational Resources Information Center

    Smith, Walter T., Jr.; Patterson, John M.

    1984-01-01

    Literature on analytical methods related to the functional groups of 17 chemical compounds is reviewed. These compounds include acids, acid azides, alcohols, aldehydes, ketones, amino acids, aromatic hydrocarbons, carbodiimides, carbohydrates, ethers, nitro compounds, nitrosamines, organometallic compounds, peroxides, phenols, silicon compounds,…

  9. Surface grafting of carboxylic groups onto thermoplastic polyurethanes to reduce cell adhesion

    NASA Astrophysics Data System (ADS)

    Alves, P.; Ferreira, P.; Kaiser, Jean-Pierre; Salk, Natalie; Bruinink, Arie; de Sousa, Hermínio C.; Gil, M. H.

    2013-10-01

    The interaction of polymers with other materials is an important issue, being their surface properties clearly crucial. For some important polymer applications, their surfaces have to be modified. Surface modification aims to tailor the surface characteristics of a material for a specific application without affecting its bulk properties. Materials can be surface modified by using biological, chemical or physical methods. The aim of this work was to improve the reactivity of the thermoplastic polyurethane (TPU) material (Elastollan®) surface and to make its surface cell repellent by grafting carboxylic groups onto its surface. Two TPU materials were studied: a polyether-based TPU and a polyester-based TPU. The grafting efficiency was evaluated by contact angle measurements and by analytical determination of the COOH groups. Scanning electron microscopy (SEM) of the membranes surface was performed as well as cell adhesion tests. It was proved that the surfaces of the TPUs membranes were successfully modified and that cell adhesion was remarkably reduced.

  10. Introduction of aldehyde vs. carboxylic groups to cellulose nanofibers using laccase/TEMPO mediated oxidation.

    PubMed

    Jaušovec, Darja; Vogrin?i?, Robert; Kokol, Vanja

    2015-02-13

    The chemo-enzymatic modification of cellulose nanofibers (CNFs) using laccase as biocatalysts and TEMPO or 4-Amino-TEMPO as mediators under mild aqueous conditions (pH 5, 30 °C) has been investigated to introduce surface active aldehyde groups. 4-Amino TEMPO turned out to be kinetically 0.5-times (50%) more active mediator, resulting to oxoammonium cation intermediacy generated and its in situ regeneration during the modification of CNFs. Accordingly, beside of around 750 mmol/kg terminally-located aldehydes, originated during CNFs isolation, the reaction resulted to about 140% increase of C6-located aldehydes at optimal conditions, without reducing CNFs crystallinity. While only the C6-aldehydes were wholly transformed into the carboxyls after additional post-treatment using NaOH according to the Cannizzaro reaction, the post-oxidation with air-oxygen in EtOH/water medium or NaClO2 resulted to no- or very small amounts of carboxyls created, respectively, at a simultaneous loss of all C6- and some terminal-aldehydes in the latter due to the formation of highly-resistant hemiacetal covalent linkages with available cellulose hydroxyls. The results indicated a new way of preparing and stabilizing highly reactive C6-aldehydes on cellulose, and their exploitation in the development of new nanocellulose-based materials. PMID:25458275

  11. Synthesis, bifunctionalization, and remarkable adsorption performance of benzene-bridged periodic mesoporous organosilicas functionalized with high loadings of carboxylic acids.

    PubMed

    Wu, Hao-Yiang; Shieh, Fa-Kuen; Kao, Hsien-Ming; Chen, Yi-Wen; Deka, Juti Rani; Liao, Shih-Hsiang; Wu, Kevin C-W

    2013-05-10

    Highly ordered benzene-bridged periodic mesoporous organosilicas (PMOs) that were functionalized with exceptionally high loadings of carboxylic acid groups (COOH), up to 80?mol?% based on silica, have been synthesized and their use as adsorbents for the adsorption of methylene blue (MB), a basic dye pollutant, and for the loading and release of doxorubicin (DOX), an anticancer drug, is demonstrated. These COOH-functionalized benzene-silicas were synthesized by the co-condensation of 1,4-bis(triethoxysilyl) benzene (BTEB) and carboxyethylsilanetriol sodium salt (CES), an organosilane that contained a carboxylic acid group, in the presence of non-ionic oligomeric surfactant Brij?76 in acidic medium. The materials thus obtained were characterized by a variety of techniques, including powder X-ray diffraction (XRD), nitrogen-adsorption/desorption isotherms, TEM, and (13)C and (29)Si solid-state NMR spectroscopy. Owing to the exceptionally high loadings of COOH groups, their high surface areas, and possible ?-?-stacking interactions, these adsorbents have very high adsorption capacities and extremely rapid adsorption rates for MB removal and for the controlled loading/release of DOX, thus manifesting their great potential for environmental and biomedical applications. PMID:23512281

  12. Piperazine and its carboxylic acid derivatives-functionalized mesoporous silica as nanocarriers for gemcitabine: adsorption and release study.

    PubMed

    Bahrami, Zohreh; Badiei, Alireza; Atyabi, Fatemeh; Darabi, Hossein Reza; Mehravi, Bita

    2015-04-01

    Piperazine-functionalized SBA-15 nanorods were synthesized by post grafting method with methyldimethoxysilylpropylpiperazine (MDSP). The carboxylic acid derivatives of piperazine-functionalized SBA-15 nanorods were obtained using two different kinds of precursors (bromoacetic acid and succinic anhydride). The prepared materials were used as nanocarriers for the anticancer drug (gemcitabine). The obtained samples were characterized by SAXS, N2 adsorption-desorption, SEM, TEM, DLS, thermogravimetric analysis, FTIR, Raman and UV spectroscopies. The adsorption and release properties of all samples were investigated. In vitro study included cell toxicity. It was found that the surface functionalization increases the interaction between the carrier and gemcitabine and results in the loading enhancement of the drug. In addition, the adsorption of gemcitabine on the modified mesoporous matrix depends on the type of the introduced functional groups. The carboxylic acid-modified samples have higher loading content, due to the strong interaction with gemcitabine. The maximum content of deposited drug in the modified SBA-15 nanorods is close to 36wt.% that it is related to PC2-SBA-15 sample which obtained using succinic anhydride. The obtained results reveal that the surface functionalization leads toward a significant decrease of the drug release rate without any appreciable cytotoxicity. No significant differences are observed among the drug release rate from the modified samples. PMID:25686928

  13. Renormalization group functional equations.

    SciTech Connect

    Curtright, T. L.; Zachos, C. K. (High Energy Physics); (Univ. of Miami)

    2011-03-16

    Functional conjugation methods are used to analyze the global structure of various renormalization group trajectories and to gain insight into the interplay between continuous and discrete rescaling. With minimal assumptions, the methods produce continuous flows from step-scaling {sigma} functions and lead to exact functional relations for the local flow {beta} functions, whose solutions may have novel, exotic features, including multiple branches. As a result, fixed points of {sigma} are sometimes not true fixed points under continuous changes in scale and zeroes of {beta} do not necessarily signal fixed points of the flow but instead may only indicate turning points of the trajectories.

  14. Renormalization group functional equations

    SciTech Connect

    Curtright, Thomas L. [CERN, CH-1211 Geneva 23 (Switzerland); Department of Physics, University of Miami, Coral Gables, Florida 33124-8046 (United States); Zachos, Cosmas K. [High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439-4815 (United States)

    2011-03-15

    Functional conjugation methods are used to analyze the global structure of various renormalization group trajectories and to gain insight into the interplay between continuous and discrete rescaling. With minimal assumptions, the methods produce continuous flows from step-scaling {sigma} functions and lead to exact functional relations for the local flow {beta} functions, whose solutions may have novel, exotic features, including multiple branches. As a result, fixed points of {sigma} are sometimes not true fixed points under continuous changes in scale and zeroes of {beta} do not necessarily signal fixed points of the flow but instead may only indicate turning points of the trajectories.

  15. Electrochemical properties of polyolefin nonwoven fabric modified with carboxylic acid group for battery separator

    NASA Astrophysics Data System (ADS)

    Choi, Seong-Ho; Kang, Hae-Jeong; Ryu, Eun-Nyoung; Lee, Kwang-Pill

    2001-01-01

    Carboxylic acid group was introduced by radiation-induced grafting of acrylic acid (AAc) onto polyolefine nonwoven fabric (PNF), wherein the PNF comprises at least about 60% of a polyethylene having a melting temperature at ˜132°C and no more than about 40% of a second polypropylene having a lower melting temperature at ˜162°C, for a battery separator. The AAc-grafted PNF was characterized by XPS, SEM, DSC, TGA and porosimeter. The wetting speed, electrolyte retention, electrical resistance, and tensile strength were evaluated after grafting of AAc. It was found that the wetting speed, electrolyte retention, thickness, and ion-exchange capacity increased, whereas the electrical resistance decreased with increasing grafting yield. The tensile strength decreased with increasing grafting yield, whereas the elongation decreased with increasing grafting yield.

  16. Redox-neutral palladium-catalyzed C-h functionalization to form isoindolinones with carboxylic acids or anhydrides as readily available starting materials.

    PubMed

    Liang, Hong-Wen; Ding, Wei; Jiang, Kun; Shuai, Li; Yuan, Yi; Wei, Ye; Chen, Ying-Chun

    2015-06-01

    An operationally simple, Pd-catalyzed C-H functionalization is described for the synthesis of important and useful isoindolinones from readily available carboxamides and carboxylic acids or anhydrides. The reactions proceed efficiently with a broad range of substrates under redox-neutral reaction conditions and tolerate a diversity of functional groups. The mechanistic investigation suggests that the reactions involve C-H activation, nucleophilic addition, ?-O elimination, and dehydration steps. PMID:25978091

  17. Neocarzinostatin: effect of modification of side chain amino and carboxyl groups on chemical and biological properties.

    PubMed

    Samy, T S

    1977-12-13

    The antitumor protein neocarzinostatin (NCS), isolated from Streptomyces carzinostaticus, is a single chain polypeptide with 109 amino acid residues. Complete acylation of the amino groups (alanine-1 and lysine-20) was observed when NCS was allowed to react with 3-(4-hydroxyphenyl)-propionic acid N-hydroxysuccinimide ester at pH 8.5. Since the ensuing bis[(alanine-1, lysine-20)-3-(4-hydroxyphenyl)]-propionamide NCS was fully active in antibacterial potency and in the inhibition of growth of leukemic (CCRF-CEM) cells in vitro, it appears that the two amino groups in the protein are not essential for biological activity. Radiolabeled NCS was prepared by using a tritiated or 125I-labeled acylating agent. Since the CD spectra of native and bis(alanine-1, lysine-20)-amino modified NCS were indistinguishable, there is presumably no change in the native conformation of the protein due to acylation. Reaction of NCS with ammonium chloride in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide at pH 4.75 converted all the 10 carboxyl groups into carboxamides and produced a protein derivative of basic character. This modification caused a change in the native conformation of the protein accompanied by a loss in biological inhibitory activities. PMID:144523

  18. Facile one-step coating approach to magnetic submicron particles with poly(ethylene glycol) coats and abundant accessible carboxyl groups

    PubMed Central

    Long, Gaobo; Yang, Xiao-lan; Zhang, Yi; Pu, Jun; Liu, Lin; Liu, Hong-bo; Li, Yuan-li; Liao, Fei

    2013-01-01

    Purpose Magnetic submicron particles (MSPs) are pivotal biomaterials for magnetic separations in bioanalyses, but their preparation remains a technical challenge. In this report, a facile one-step coating approach to MSPs suitable for magnetic separations was investigated. Methods Polyethylene glycol) (PEG) was derived into PEG-bis-(maleic monoester) and maleic monoester-PEG-succinic monoester as the monomers. Magnetofluids were prepared via chemical co-precipitation and dispersion with the monomers. MSPs were prepared via one-step coating of magnetofluids in a water-in-oil microemulsion system of aerosol-OT and heptane by radical co-polymerization of such monomers. Results The resulting MSPs contained abundant carboxyl groups, exhibited negligible nonspecific adsorption of common substances and excellent suspension stability, appeared as irregular particles by electronic microscopy, and had submicron sizes of broad distribution by laser scattering. Saturation magnetizations and average particle sizes were affected mainly by the quantities of monomers used for coating magnetofluids, and steric hindrance around carboxyl groups was alleviated by the use of longer monomers of one polymerizable bond for coating. After optimizations, MSPs bearing saturation magnetizations over 46 emu/g, average sizes of 0.32 ?m, and titrated carboxyl groups of about 0.21 mmol/g were obtained. After the activation of carboxyl groups on MSPs into N-hydroxysuccinimide ester, biotin was immobilized on MSPs and the resulting biotin-functionalized MSPs isolated the conjugate of streptavidin and alkaline phosphatase at about 2.1 mg/g MSPs; streptavidin was immobilized at about 10 mg/g MSPs and retained 81% ± 18% (n = 5) of the specific activity of the free form. Conclusion The facile approach effectively prepares MSPs for magnetic separations. PMID:23589687

  19. Transition metal chemistry of main group hydrazides. Part 3:{sup 1} carboxylate appended phosphorus hydrazides as novel functionalized chelating systems. Synthesis and characterization of new cyclometallaphosphohydrazides. X-ray structure of a Palladium(II) representative

    SciTech Connect

    Singh, P.R.; Jimenez, H.; Barnes, C.L. [Missouri Univ. Research Reactor, Columbia, MO (United States); Katti, K.V. [Univ. of Missour, Columbia, MO (United States)]|[Missouri Univ. Research Reactor, Columbia, MO (United States); Volkert, W.A. [Missouri Univ. Research Reactor, Columbia, MO (United States)]|[Univ. of Missouri, Columbia, MO (United States)

    1994-02-16

    The synthesis of new bifunctional chelating agents (BFCAs) based on the phosphorus hydrazide ligand family for potential {sup 109}Pd labeling of tumor-localizing biomolecules such as proteins/peptides is described. The new BFCAs were achieved in good yields (75-90%) by the reaction of the phosphorus hydrazide PhP(S)(NMeNH{sub 2}){sub 2} (1) with functionalized aldehydes to yield the Schiff-base products with the following chemical compositions as air-stable crystalline solids: PhP(S)(NMeNH{sub 2})(NMeNCHC{sub 6}H{sub 4}COOH), 2; PhP(S)(NMeNCHC{sub 6}H{sub 4}COOH){sub 2}, 3; PhP(S)(NMeNH{sub 2})(NMeNCHC{sub 6}H{sub 4}CH=CHCOOH), 4; PhP(S)(NMeNCHC{sub 6}H{sub 4}CH-CHCOOH){sub 2}, 5. The reactions of three of the new phosphorus hydrazides (2-4) with PdCl{sub 2}(PhCN){sub 2} resulted in the new Pd(II) metallacycles PhP(S)(NMeNH{sub 2})(NMeNCHC{sub 6}H{sub 4}COOH){center_dot}PdCl{sub 2}, 6; PhP(S)(NMeNCHC{sub 6}H{sub 4}COOH){sub 2}{center_dot}PdCl{sub 2}, 7; and PhP(S)(NMeNH{sub 2})(NMeNCHC{sub 6}H{sub 4}CH=CHCOOH){center_dot}PdCl{sub 2}, 8. The reactivity of 6 toward n-butylamine has been evaluated as a model for the preparation of new bioconjugates. The structural elucidation of all the new compounds has been carried out by analytical and complete NMR ({sup 1}H, {sup 31}P) and IR spectroscopic data. As a representative example, the X-ray structure of one of the Pd(II) complexes, 8, has been determined.

  20. Information for proteomics: ESI-MS titration by sodium ions gives the number of carboxylate groups in peptides

    NASA Astrophysics Data System (ADS)

    Timofeev, Oleg; Zhu, Mei M.; Gross, Michael L.

    2004-02-01

    We studied the electrospray ionization (ESI) of various peptides containing amino acids with acidic side chains to test whether the pattern of molecular ion peaks provides information on the number of acidic side chains. When we increased the concentration of sodium salt in the ESI solution containing a peptide, a characteristic pattern arose, and it represents the various sodium salts of carboxylic acid and an additional sodium ion to add charge to the species. Both C-terminal and side chain carboxylic acid groups readily form sodium carboxylates. After reaching full substitution of all acidic hydrogens for sodium ions, further increases in the concentration of sodium cations do not lead to the attachment of additional sodium atoms. This effect allows counting of acid residues in a peptide. This information is easily acquired and may be an appropriate supplement to exact mass measurements and partial sequence data that are currently used in proteomic database searches.

  1. Molecular level computational studies of polyethylene and polyacrylonitrile composites containing single walled carbon nanotubes: effect of carboxylic acid functionalization on nanotube-polymer interfacial properties

    PubMed Central

    Haghighatpanah, Shayesteh; Bohlén, Martin; Bolton, Kim

    2014-01-01

    Molecular dynamics (MD) and molecular mechanics (MM) methods have been used to investigate additive-polymer interfacial properties in single walled carbon nanotube (SWNT)—polyethylene and SWNT—polyacrylonitrile composites. Properties such as the interfacial shear stress and bonding energy are similar for the two composites. In contrast, functionalizing the SWNT with carboxylic acid groups leads to an increase in these properties, with a larger increase for the polar polyacrylonitrile composite. Increasing the percentage of carbon atoms that were functionalized from 1 to 5% also leads to an increase in the interfacial properties. In addition, the interfacial properties depend on the location of the functional groups on the SWNT wall. PMID:25229056

  2. Porphyrin-sensitized solar cells: effect of carboxyl anchor group orientation on the cell performance.

    PubMed

    Hart, Aaron S; Chandra, B K C; Gobeze, Habtom B; Sequeira, Lindsey R; D'Souza, Francis

    2013-06-12

    The effect of the orientation of the porphyrin sensitizer onto the TiO2 surface on the performance of dye-sensitized solar cells (DSSCs) is reported. Free-base and zinc porphyrins bearing a carboxyl anchoring group at the para, meta, or ortho positions of one of the meso-phenyl rings were synthesized for application in Grätzel-type photoelectrochemical cells. The remainder of the meso-phenyl rings was substituted with alkyl chains of different length to visualize any aggregation effects. Absorption and fluorescence studies were performed to characterize and observe spectral coverage of the thirteen newly synthesized porphyrin derivatives. Photoelectrochemical studies were performed after immobilization of porphyrins onto nanocrystalline TiO2 and compared with DSSC constructed using N719 dye as reference. The performance of DSSCs with the porphyrin anchoring at the para or meta position were found to greatly exceed those with the anchoring group in the ortho position. Additionally, cells constructed using zinc porphyrin derivatives outperformed the free-base porphyrin analogs. Better dye regeneration efficiency for the zinc porphyrin derivatives compared to their free-base porphyrin analogs, and for the meta and para derivatives over the ortho derivatives was evaluated from electrochemical impedance spectroscopy studies. Femtosecond transient absorption spectroscopy studies were performed to probe the kinetics of charge injection and charge recombination with respect to the orientation of porphyrin macrocycle on TiO2 surface. The ortho porphyrin derivative with an almost flat orientation to the TiO2 surface revealed fast charge recombination and suggested occurrence of through-space charge transfer. The overall structure-performance trends observed for the present porphyrin DSSCs have been rationalized based on spectral, electrochemical, electrochemical impedance spectroscopy, and transient spectroscopy results. PMID:23647324

  3. Self-oriented glucose-modified infrared sensor for the detection of compounds bearing carboxylic acid groups.

    PubMed

    Cheng, Ming-Liang; Yang, Jyisy

    2008-01-01

    To explore the interactions of self-oriented glucose toward organic species, we prepared a glucose-modified infrared (IR) chemical sensor and examined its performance in the detection of compounds bearing carboxylic acid functional groups. Using a two-layer modification method, we chemically bonded glucose to the surface of an IR sensing element. The immobilized glucose moieties exhibited the ability to assemble into a chemical form similar to that of the cyclodextrins (CDs) such that they could trap targeted molecules. This modified sensing phase displayed an analysis capability similar to that of CDs, but without the problems encountered attempting to maintain the activity of the latter. From a systematic examination of three classes of structural analogs of acids, we found that the behavior of the glucose-modified sensing phase was similar to that of a CD-modified sensing phase. In terms of quantitative detection, we obtained an average regression coefficient of approximately 0.996 for the analytical signals of the examined compounds at concentrations less than 20 mg/L. The linearity of the standard curves was related to the detection time: the shorter the detection time, the greater the linearity. Defined as three times the noise level, we obtained detection limits of a few hundred parts per billion (microg/L) for the determination of high-polarity compounds using our glucose-modified sensing phase. PMID:18230206

  4. Chemical reduction of carboxyl groups in heparin abolishes its vasodilatory activity.

    PubMed

    Paredes-Gamero, Edgar J; Medeiros, Valquíria P; Lima, Marcelo A; Accardo, Camila M; Farias, Eduardo H C; Sassaki, Guilherme I; Campana, Patricia T; Miranda, Antonio; Ferreira, Alice T; Tersariol, Ivarne L S; Nader, Helena B

    2012-04-01

    Previous studies have shown that heparin induces vascular relaxation via integrin-dependent nitric oxide (NO)-mediated activation of the muscarinic receptor. The aim of this study was to identify the structural features of heparin that are necessary for the induction of vasodilatation. To address this issue, we tested heparin from various sources for their vasodilatation activities in the rat aorta ring. Structural and chemical characteristics of heparin, such as its molecular weight and substitution pattern, did not show a direct correlation with the vasodilation activity. Principal component analysis (PCA) of circular dichroism (CD), (1)H-nuclear magnetic resonance (NMR) and vasodilation activity measurements confirmed that there is no direct relationship between the physico-chemical nature and vasodilation activity of the tested heparin samples. To further understand these observations, unfractionated heparin (UFH) from bovine intestinal mucosa, which showed the highest relaxation effect, was chemically modified. Interestingly, non-specific O- and N-desulfation of heparin reduced its anticoagulant, antithrombotic, and antihemostatic activities, but had no effect on its ability to induce vasodilation. On the other hand, chemical reduction of the carboxyl groups abolished heparin-induced vasodilation and reduced the affinity of heparin toward the extracellular matrix (ECM). In addition, dextran and dextran sulfate (linear non-sulfated and highly sulfated polysaccharides, respectively) did not induce significant relaxation, showing that the vasodilation activity of polysaccharides is neither charge-dependent nor backbone unspecific. Our results suggest that desulfated heparin molecules may be used as vasoactive agents due to their low side effects. PMID:22134887

  5. Whittaker functions on metaplectic groups

    E-print Network

    McNamara, Peter James

    2010-01-01

    The theory of Whittaker functions is of crucial importance in the classical study of automorphic forms on adele groups. Motivated by the appearance of Whittaker functions for covers of reductive groups in the theory of ...

  6. Cluster functional renormalization group

    NASA Astrophysics Data System (ADS)

    Reuther, Johannes; Thomale, Ronny

    2014-01-01

    Functional renormalization group (FRG) has become a diverse and powerful tool to derive effective low-energy scattering vertices of interacting many-body systems. Starting from a free expansion point of the action, the flow of the RG parameter ? allows us to trace the evolution of the effective one- and two-particle vertices towards low energies by taking into account the vertex corrections between all parquet channels in an unbiased fashion. In this work, we generalize the expansion point at which the diagrammatic resummation procedure is initiated from a free UV limit to a cluster product state. We formulate a cluster FRG scheme where the noninteracting building blocks (i.e., decoupled spin clusters) are treated exactly, and the intercluster couplings are addressed via RG. As a benchmark study, we apply our cluster FRG scheme to the spin-1/2 bilayer Heisenberg model (BHM) on a square lattice where the neighboring sites in the two layers form the individual two-site clusters. Comparing with existing numerical evidence for the BHM, we obtain reasonable findings for the spin susceptibility, the spin-triplet excitation energy, and quasiparticle weight even in coupling regimes close to antiferromagnetic order. The concept of cluster FRG promises applications to a large class of interacting electron systems.

  7. ATR-FTIR Spectroscopic Evidence for Biomolecular Phosphorus and Carboxyl Groups Facilitating Bacterial Adhesion to Iron Oxides

    PubMed Central

    Parikh, Sanjai J.; Mukome, Fungai N.D.; Zhang, Xiaoming

    2014-01-01

    Attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy has been used to probe the binding of bacteria to hematite (?-Fe2O3) and goethite (?-FeOOH). In situ ATR-FTIR experiments with bacteria (Pseudomonas putida, P. aeruginosa, Escherichia coli), mixed amino acids, polypeptide extracts, deoxyribonucleic acid (DNA), and a suite of model compounds were conducted. These compounds represent carboxyl, catecholate, amide, and phosphate groups present in siderophores, amino acids, polysaccharides, phospholipids, and DNA. Due in part to the ubiquitous presence of carboxyl groups in biomolecules, numerous IR peaks corresponding to outer-sphere or unbound (1400 cm?1) and inner-sphere (1310-1320 cm?1) coordinated carboxyl groups are noted following reaction of bacteria and biomolecules with ?-Fe2O3 and ?-FeOOH. However, the data also reveal that the presence of low-level amounts (i.e., 0.45-0.79%) of biomolecular phosphorous groups result in strong IR bands at ~1043 cm?1, corresponding to inner-sphere Fe-O-P bonds, underscoring the importance of bacteria associated P-containing groups in biomolecule and cell adhesion. Spectral comparisons also reveal slightly greater P-O-Fe contributions for bacteria (Pseudomonad, E. coli) deposited on ?-FeOOH, as compared to ?-Fe2O3. This data demonstrates that slight differences in bacterial adhesion to Fe oxides can be attributed to bacterial species and Fe-oxide minerals. However, more importantly, the strong binding affinity of phosphate in all bacteria samples to both Fe-oxides results in the formation of inner-sphere Fe-O-P bonds, signifying the critical role of biomolecular P in the initiation of bacterial adhesion. PMID:24859052

  8. Functional pendent groups affecting chemisorption and adherent properties of polyelectrolyte-zinc phosphate composite conversion coatings

    SciTech Connect

    Sugama, T.; Kukacka, L.E.; Carciello, N.

    1986-04-01

    The ability of polyelectrolyte macromolecules to suppress the crystal growth of zinc phosphate (Zn.Ph) conversion coatings depends primarily on the species of the functional pendent groups. The extent of chemisorption of carboxylic and sulfonic acid groups on the crystal faces was considerably higher than that for amide groups. The internal diffusion of polyelectrolyte on the Zn.Ph crystal acted significantly to improve the mechanical properties and alkaline resistance of the crystal coatings. The reaction products formed by chemical interactions between the urethane groups in the polyurethane topcoat and the carboxylic acid groups in the Zn.Ph composite precoat played an essential role in developing the interfacial adhesive forces.

  9. Synthesis and herbicidal activity of isoindoline-1,3-dione substituted benzoxazinone derivatives containing a carboxylic ester group.

    PubMed

    Huang, Ming-Zhi; Luo, Fei-Xian; Mo, Hong-Bo; Ren, Ye-Guo; Wang, Xiao-Guang; Ou, Xiao-Ming; Lei, Man-Xiang; Liu, Ai-Ping; Huang, Lu; Xu, Man-Cai

    2009-10-28

    A carboxylic ester group was introduced to three series of isoindolinedione substituted benzoxazinone derivatives. Some of these analogues exhibited good herbicidal activities, and the injury symptoms against weeds included leaf cupping, crinkling, bronzing, and necrosis, typical of protox inhibitor herbicides. Structurally, they were classified as Chemical Group A (4-carboxylic ester group-6-isoindolinyl-benzoxazinones), B (4-carboxylic ester group-7-isoindolinyl-benzoxazinones), and C (4-carboxylic ester group-6- tetrahydroisoindolinyl-benzoxazinones). All of the tested compounds were structurally confirmed by (1)H NMR, IR, mass spectroscopy, and elemental analysis. Preliminary bioassay data of these three classes of compounds showed that, in general, the order of the herbicidal effectiveness is C > A > B. Several of the lead compounds, for example, C10 (methyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-1H-isoindol-2(3H)-yl)-7-fluoro-2-methyl-3-oxo-2H-benzo[b][1,4] oxazin-4(3H)-yl) propano-ate), C12 (ethyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-1H-isoindol-2(3H)-yl)-7-fluoro-2- methyl-3-oxo-2H-benzo[b][1,4]oxazin-4(3H)-yl) propanoate), and C13 (ethyl 2-(6-(1,3-dioxo-4,5,6,7-tetrahydro-1H-isoindol-2(3H)-yl)-7-fluoro-2-methyl-3-oxo-2H-benzo-[b][1,4]oxazin-4(3H)-yl) butanoate), exhibited greater than 80% control at 75 g a.i./ha in both pre- and postemergence treatments against dicotyledonous weeds, such as Abutilon theophrasti Medic, Chenopodium album L., and Amaranthus ascendens L., and monocotyledon weeds, such as Digitaria sanguinalis L., Echinochloa crus-galli L., and Setaria viridis L. On the basis of advanced screening tests and crop selectivity, compounds C10, C12, and C13 are safer to crops than flumioxazin. Compounds C10, C12, and C13 are potent to develop as pre-emergent herbicides used in peanut, soybean, maize, and cotton fields. PMID:19772294

  10. Oxidation of linoleyl alcohol by potato tuber lipoxygenase: possible mechanism and the role of carboxylic group in substrate binding.

    PubMed

    Butovich, I A; Lukyanova, S M; Reddy, C C

    1998-08-19

    We have studied the aerobic oxidation of linoleyl alcohol (LAL) by potato tuber lipoxygenase in the presence of 0.02% (w/v) non-ionic detergent Lubrol PX (and its analog C12E10) and 0.1 mM sodium dodecyl sulfate to investigate the role of carboxylic group in substrate binding. While the enzyme displayed a comparable affinity toward LA and LAL, the rate of LAL oxidation was approximately one-fourth of that of linoleic acid. The pH-profile of the reaction suggests that the rate of LAL oxidation is controlled by two ionizable groups with pKa values of 5.3 and 7.5, with optimal pH being 6.4+/-0.1. Since LAL is not ionizable at this pH, we conclude that the rate of the reaction is controlled by two ionogenic groups of the enzyme. The primary dioxygenation product(s) of LAL had a maximal absorbance at 233+/-1 nm. The products have been isolated, catalytically hydrogenated with H2 over Pd on carbon, and analyzed by GC-MS. Two major equimolar products were found to be 9- and 13-hydroxystearyl alcohols, indicating that 9- and 13-hydroperoxylinoleyl alcohols are the primary dioxygenation products. Based on these results we propose that the carboxyl group of polyunsaturated fatty acid may not be involved in substrate binding of potato tuber lipoxygenase. PMID:9712698

  11. Solution Phase Parallel Synthesis of 4-Aminophenyl Ethers Using a Carboxyl-Functionalized Ionic Liquid as Support

    Microsoft Academic Search

    Yanqing Peng; Fengping Yi; Gonghua Song; Ying Zhang

    2005-01-01

    Summary. A small sortiment of 4-aminophenyl ether derivatives was constructed with good yields and purities via Williamson reaction using the carboxyl-functionalized ionic liquid [cmmim][BF4] as soluble support. The recovered ionic liquid could be reused for several times with similar capacity.

  12. Expression of a functional jasmonic acid carboxyl methyltransferase is negatively correlated with strawberry fruit development.

    PubMed

    Preuß, Anja; Augustin, Christiane; Figueroa, Carlos R; Hoffmann, Thomas; Valpuesta, Victoriano; Sevilla, José F; Schwab, Wilfried

    2014-09-15

    The volatile metabolite methyl jasmonate (MeJA) plays an important role in intra- and interplant communication and is involved in diverse biological processes. In this study, we report the cloning and functional characterization of a S-adenosyl-l-methionine:jasmonic acid carboxyl methyltransferase (JMT) from Fragaria vesca and Fragaria×ananassa. Biochemical assays and comprehensive transcript analyses showed that JMT has been erroneously annotated as gene fusion with a carboxyl methyltransferase (CMT) (gene15184) in the first published genome sequence of F. vesca. Recombinant FvJMT catalyzed the formation of MeJA with KM value of 22.3?M while FvCMT and the fusion protein were almost inactive. Activity of JMT with benzoic acid and salicylic acid as substrates was less than 1.5% of that with JA. Leucine at position 245, an amino acid missing in other JMT sequences is essential for activity of FvJMT. In accordance with MeJA levels, JMT transcript levels decreased steadily during strawberry fruit ripening, as did the expression levels of JA biosynthesis and regulatory genes. It appears that CMT has originated by a recent duplication of JMT and lost its enzymatic activity toward JA. In the newest version of the strawberry genome sequence (June 2014) CMT and JMT are annotated as separate genes in accordance with differential temporal and spatial expression patterns of both genes in Fragaria sp. In conclusion, MeJA, the inactive derivative of JA, is probably involved in early steps of fruit development by modulating the levels of the active plant hormone JA. PMID:25046752

  13. Regulating bioactivity of Cu2+ bis-1,10-phenanthroline artificial metallonucleases with sterically functionalized pendant carboxylates.

    PubMed

    Prisecaru, Andreea; McKee, Vickie; Howe, Orla; Rochford, Garret; McCann, Malachy; Colleran, John; Pour, Milan; Barron, Niall; Gathergood, Nicholas; Kellett, Andrew

    2013-11-14

    The synthetic chemical nuclease, [Cu(1,10-phenanthroline)2](2+), has stimulated research within metallonuclease development and in the area of cytotoxic metallodrug design. Our analysis reveals, however, that this agent is "promiscuous" as it binds both dsDNA and protein biomolecules, without specificity, and induces general toxicity to a diversity of cell lineages. Here, we describe the synthesis and characterization of small-molecule metallonucleases containing the redox-active cation, [Cu(RCOO)(1,10-phen)2](+), where 1,10-phen = 1,10-phenanthroline and R = -H, -CH3, -C2H5, -CH(CH3)2, and -C(CH3)3. The presence of coordinated carboxylate groups in the complex cation functions to enhance dsDNA recognition, reduce serum albumin binding, and offer control of toxicity toward human cancer cells, Gram positive and negative bacteria, and fungal pathogens. The induction of genomic dsDNA breaks (DSBs) were identified in ovarian adenocarcinoma cells using immunodetection of ?-H2AX. Formate, acetate, and pivalate functionalized complexes induced DSBs in a higher percentage of cells compared with [Cu(1,10-phen)2](2+), which supports the importance of inner-sphere modification toward enhancing targeted biological application. PMID:24131470

  14. Analysis of carboxyl tail function in the skeletal muscle Cl- channel hClC-1.

    PubMed

    Ma, Linlin; Rychkov, Grigori Y; Hughes, Bernard P; Bretag, Allan H

    2008-07-01

    Human ClC-1 (skeletal muscle Cl- channel) has a long cytoplasmic C-tail (carboxyl tail), containing two CBS (cystathionine beta-synthase) domains, which is very important for channel function. We have now investigated its significance further, using deletion and alanine-scanning mutagenesis, split channels, GST (glutathione transferase)-pull-down and whole-cell patch-clamping. In tagged split-channel experiments, we have demonstrated strong binding between an N-terminal membrane-resident fragment (terminating mid-C-tail at Ser(720) and containing CBS1) and its complement (containing CBS2). This interaction is not affected by deletion of some sequences, suggested previously to be important, particularly in channel gating. Contact between CBS1 and CBS2, however, may make a major contribution to assembly of functional channels from such co-expressed complements, although the possibility that C-tail fragments could, in addition, bind to other parts of the membrane-resident component has not been eliminated. We now show such an interaction between a membrane-resident component terminating at Ser(720) (but with CBS1 deleted) and a complete C-tail beginning at Leu(598). Channel function is rescued in patch-clamped HEK-293T (human embryonic kidney) cells co-expressing these same fragments. From our own results and those of others, we conclude that the CBS1-CBS2 interaction is not sufficient, in itself, for channel assembly, but rather that this might normally assist in bringing some part of the CBS2/C-tail region into appropriate proximity with the membrane-resident portion of the protein. Previously conflicting and anomalous results can now be explained by an hypothesis that, for split channels to be functional, at least one membrane-resident component must include a plasma membrane trafficking signal between Leu(665) and Lys(680). PMID:18321245

  15. Differences in the length of the carboxyl terminus mediate functional properties of neurokinin-1 receptor

    Microsoft Academic Search

    Jian-Ping Lai; Saien Lai; Florin Tuluc; Morris F. Tansky; Laurie E. Kilpatrick; Susan E. Leeman; Steven D. Douglas

    2008-01-01

    The neurokinin-1 receptor (NK1R) has two naturally occurring forms that differ in the length of the carboxyl terminus: a full-length receptor consisting of 407 aa and a truncated receptor consisting of 311 aa. We examined whether there are differential signaling properties attributable to the carboxyl terminus of this receptor by using stably transfected human embryonic kidney (HEK293) cell lines that

  16. Synthesis and evaluation of novel dental monomer with branched carboxyl acid group

    PubMed Central

    Song, Linyong; Ye, Qiang; Ge, Xueping; Misra, Anil; Laurence, Jennifer S.; Berrie, Cynthia L.; Spencer, Paulette

    2014-01-01

    To enhance the water miscibility and increase the mechanical properties of dentin adhesives, a new glycerol-based monomer with vinyl and carboxylic acid, 4-((1,3-bis(-methacryloyloxy)propan-2-yl)oxy)-2-methylene-4-oxobutanoic acid (BMPMOB), was synthesized and characterized. Dentin adhesive formulations containing 2-hydroxyethyl methacrylate (HEMA), 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (BisGMA), and BMPMOB were characterized with regard to real-time photopolymerization behavior, water sorption, dynamic mechanical analysis, and microscale three-dimensional internal morphologies and compared with HEMA/BisGMA controls. The experimental adhesive copolymers showed higher glass transition temperature and rubbery moduli, as well as improved water miscibility compared to the controls. The enhanced properties of the adhesive copolymers indicated that BMPMOB is a promising comonomer for dental restorative materials. PMID:24596134

  17. DNA damage in human skin keratinocytes caused by multiwalled carbon nanotubes with carboxylate functionalization.

    PubMed

    McShan, Danielle; Yu, Hongtao

    2014-07-01

    Water-soluble carbon nanotubes have been found to be one of the most promising nanomaterials in biological- and biomedical-based applications. However, there have been major concerns on their ability to cause cellular and DNA damages upon exposure. In this work, we explore the toxic effects of three multiwalled carbon nanotubes (MWCNTs: nonpurified, purified and carboxylate-functionalized) on human skin keratinocytes (HaCaT). Cytotoxicity tests using the conventional thiazolyl blue tetrazolium bromide (MTT) and the water-soluble tetrazolium (WST-1) assays for 0.5 or 24 h exposure to 20 ?g/mL of MWCNTs show that all three caused minimum cytotoxicity that is generally not statistically significant. Assessment of direct and oxidative DNA damages using both alkaline Comet assay and formamidopyrimidine DNA glycosylase-modified Comet assay reveals that the treatment with 20 ?g/mL of MWCNTs does not cause significant direct DNA damages, but causes great amount of oxidative DNA damages in HaCaT cells. The oxidative DNA damage reaches the maximum amount at 4 h of incubation in Dulbecco's minimum essential medium, but decreases to the minimum at 8 and 24 h of incubation, indicating repair of the oxidative damages by the intrinsic DNA repair mechanism of the cells. PMID:23012341

  18. G?q Protein Carboxyl Terminus Imitation Polypeptide GCIP-27 Improves Cardiac Function in Chronic Heart Failure Rats

    PubMed Central

    Lu, Xiao Lan; Tong, Yang Fei; Liu, Ya; Xu, Ya Li; Yang, Hua; Zhang, Guo Yuan; Li, Xiao-Hui; Zhang, Hai-Gang

    2015-01-01

    Background G?q protein carboxyl terminus imitation polypeptide (GCIP)-27 has been shown to alleviate pathological cardiomyocyte hypertrophy induced by various factors. Pathological cardiac hypertrophy increases the morbidity and mortality of cardiovascular diseases while it compensates for poor heart function. This study was designed to investigate the effects of GCIP-27 on heart function in rats with heart failure induced by doxorubicin. Methods and Results Forty-eight rats were randomly divided into the following six groups receiving vehicle (control), doxorubicin (Dox), losartan (6 mg/kg, i.g.) and three doses of GCIP-27 (10, 30, 90 ?g/kg; i.p., bid), respectively. Heart failure was induced by Dox, which was administered at a 20 mg/kg cumulative dose. After 10 weeks of treatment, we observed that GCIP-27 (30, 90 ?g/kg) significantly increased ejection fraction, fraction shortening, stroke volume and sarcoplasmic reticulum Ca2+ ATPase activity of Dox-treated hearts. Additionally, GCIP-27 decreased myocardial injury, heart weight index and left ventricular weight index, fibrosis and serum cardiac troponin-I concentration in Dox-treated mice. Immunohistochemistry, western blotting and real-time PCR experiments indicated that GCIP-27 (10–90 ?g/kg) could markedly upregulate the protein expression of myocardial ?-myosin heavy chain (MHC), Bcl-2, protein kinase C (PKC) ? and phosphorylated extracellular signal-regulated kinase (p-ERK) 1/2 as well as the mRNA expression of ?-MHC, but downregulated the expression of ?-MHC, Bax and PKC ?II, and the mRNA expression levels of ?-MHC in Dox-treated mice. It was also found that GCIP-27 (30, 90 ?g/L) decreased cell size and protein content of cardiomyocytes significantly in vitro by comparison of Dox group. Conclusions GCIP-27 could effectively ameliorate heart failure development induced by Dox. PKC–ERK1/2 signaling might represent the underlying mechanism of the beneficial effects of GCIP-27. PMID:25822412

  19. Chemoselective Functionalization of Carboxylic Acid and Phenol Containing Natural Products and the Development and Use of a Nucleophile Catalyzed Michael Aldol Lactonization Process

    E-print Network

    McFarlin, Rae

    2013-05-02

    probes for mechanism of action studies. Herein, we describe a strategy to functionalize carboxylic acid and phenol containing natural products. This methodology relies on the in situ generation of diazoalkanes to form the corresponding carbonyl esters...

  20. Polymethyl methacrylate-co-methacrylic acid coatings with controllable concentration of surface carboxyl groups: A novel approach in fabrication of polymeric platforms for potential bio-diagnostic devices

    NASA Astrophysics Data System (ADS)

    Hosseini, Samira; Ibrahim, Fatimah; Djordjevic, Ivan; Koole, Leo H.

    2014-05-01

    The generally accepted strategy in development of bio-diagnostic devices is to immobilize proteins on polymeric surfaces as a part of detection process for diseases and viruses through antibody/antigen coupling. In that perspective, polymer surface properties such as concentration of functional groups must be closely controlled in order to preserve the protein activity. In order to improve the surface characteristics of transparent polymethacrylate plastics that are used for diagnostic devices, we have developed an effective fabrication procedure of polymethylmetacrylate-co-metacrylic acid (PMMA-co-MAA) coatings with controlled number of surface carboxyl groups. The polymers were processed effectively with the spin-coating technique and the detailed control over surface properties is here by demonstrated through the variation of a single synthesis reaction parameter. The chemical structure of synthesized and processed co-polymers has been investigated with nuclear magnetic resonance spectroscopy (NMR) and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-ToF-MS). The surface morphology of polymer coatings have been analyzed with atomic force microscopy (AFM) and scanning electron microscopy (SEM). We demonstrate that the surface morphology and the concentration of surface -COOH groups (determined with UV-vis surface titration) on the processed PMMA-co-MAA coatings can be precisely controlled by variation of initial molar ratio of reactants in the free-radical polymerization reaction. The wettability of developed polymer surfaces also varies with macromolecular structure.

  1. Functional groups modulate the sensitivity and electron transfer kinetics of neurochemicals at carbon nanotube modified microelectrodes

    PubMed Central

    Jacobs, Christopher B.; Vickrey, Trisha L.; Venton, B. Jill

    2014-01-01

    The surface properties of carbon based electrodes are critically important for the detection of biomolecules and can modulate electrostatic interactions, adsorption and electrocatalysis. Carbon nanotube (CNT) modified electrodes have previously been shown to have increased oxidative sensitivity and reduced overpotential for catecholamine neurotransmitters, but the effect of surface functionalities on these properties has not been characterized. In this study, we modified carbon-fiber microelectrodes (CFMEs) with three differently functionalized single-wall carbon nanotubes and measured their response to serotonin, dopamine, and ascorbic acid using fast-scan cyclic voltammetry. Both carboxylic acid functionalized and amide functionalized CNTs increased the oxidative current of CFMEs by approximately 2–6 fold for the cationic neurotransmitters serotonin and dopamine, but octadecylamine functionalized CNTs resulted in no significant signal change. Similarly, electron transfer was faster for both amide and carboxylic acid functionalized CNT modified electrodes but slower for octadecylamine CNT modified electrodes. Oxidation of ascorbic acid was only increased with carboxylic acid functionalized CNTs although all CNT-modified electrodes showed a trend towards increased reversibility for ascorbic acid. Carboxylic acid-CNT modified disk electrodes were then tested for detection of serotonin in the ventral nerve cord of a Drosophila melanogaster larva, and the increase in sensitivity was maintained in biological tissue. The functional groups of CNTs therefore modulate the electrochemical properties, and the increase in sensitivity from CNT modification facilitates measurements in biological samples. PMID:21373669

  2. Impact of polyacrylamide with different contents of carboxyl groups on the chromium (III) oxide adsorption properties in aqueous solution.

    PubMed

    Wi?niewska, Ma?gorzata; Chibowski, Stanis?aw; Urban, Teresa

    2015-02-11

    The main goal of experiments was determination of solution pH and contents of anionic groups in polyacrylamide (PAM) macromolecules on the stability mechanism of chromium (III) oxide suspension. The spectrophotometry, potentiometric titration, microelectrophoresis, viscosimetry and turbidimetry were applied. They enabled determination of polymer adsorbed amount, surface and diffusion charges of solid particles with and without PAM, thickness of polymer adsorption layer, macromolecule dimensions in the solution and stability of the Cr2O3 - polymer systems, respectively. It was found that adsorption of anionic PAM decreases and thickness of polymeric adsorption layer increases with the increasing pH. Slightly higher adsorption was obtained for the PAM samples containing a greater number of carboxyl groups. At pH 3 and 9 insignificant deterioration of stability conditions of Cr2O3 particle covered with polyacrylamide was observed (neutralization of solid positive charge by the adsorbed polymeric chains (pH 3) and single polymeric bridges formation (pH 9)). The electrosteric repulsion between the solid particles covered with PAM layers at pH 6, is the main reason for significant improvement of Cr2O3 suspension stability in the polymer presence. PMID:25464324

  3. Interaction between carboxyl-functionalized carbon black nanoparticles and porous media

    NASA Astrophysics Data System (ADS)

    Kim, Song-Bae; Kang, Jin-Kyu; Yi, In-Geol

    2015-04-01

    Carbon nanomaterials, such as carbon nanotubes, fullerene, and graphene, have received considerable attention due to their unique physical and chemical characteristics, leading to mass production and widespread application in industrial, commercial, and environmental fields. During their life cycle from production to disposal, however, carbon nanomaterials are inevitably released into water and soil environments, which have resulted in concern about their health and environmental impacts. Carbon black is a nano-sized amorphous carbon powder that typically contains 90-99% elemental carbon. It can be produced from incomplete combustion of hydrocarbons in petroleum and coal. Carbon black is widely used in chemical and industrial products or applications such as ink pigments, coating plastics, the rubber industry, and composite reinforcements. Even though carbon black is strongly hydrophobic and tends to aggregate in water, it can be dispersed in aqueous media through surface functionalization or surfactant use. The aim of this study was therefore to investigate the transport behavior of carboxyl-functionalized carbon black nanoparticles (CBNPs) in porous media. Column experiments were performed for potassium chloride (KCl), a conservative tracer, and CBNPs under saturated flow conditions. Column experiments was conducted in duplicate using quartz sand, iron oxide-coated sand (IOCS), and aluminum oxide-coated sand (AOCS) to examine the effect of metal (Fe, Al) oxide presence on the transport of CBNPs. Breakthrough curves (BTCs) of CBNPs and chloride were obtained by monitoring effluent, and then mass recovery was quantified from these curves. Additionally, interaction energy profiles for CBNP-porous media were calculated using DLVO theory for sphere-plate geometry. The BTCs of chloride had relative peak concentrations ranging from 0.895 to 0.990. Transport parameters (pore-water velocity v, hydrodynamic dispersion coefficient D) obtained by the model fit from the tracer BTCs were 0.274±0.007 cm min-1 and 0.102±0.025 cm2 min-1, respectively. Mass recoveries of chloride were in the range of 94.7 to 101.9%, indicating that chloride behaved as a conservative tracer and that the column experiments were successful. The BTCs of CBNPs had different relative peak concentrations depending on the porous media used in the experiments. In quartz sand, the relative peak concentration was 0.768±0.005. The mass recovery of CBNPs in quartz sand was 83.1±2.7%, whereas no breakthrough of CBNPs (mass recovery = 0 %) was observed in IOCS or AOCS at the same flow rate, indicating that all CBNPs were retained in the IOCS and AOCS columns under the experimental conditions. These results indicate that metal (Fe, Al) oxides can play a significant role in the attachment of CBNPs to porous media. For the given solution conditions, both CBNPs and quartz sand were negatively charged with zeta potentials of -31.8±0.1 and -39.0±0.6 mV, respectively. Therefore, the electrostatic interactions between CBNPs and quartz sand were repulsive. Meanwhile, both IOCS and ACOS were positively charged with zeta potentials of 10.1±1.3 and 39.9±1.9 mV, respectively, such that the interaction between CBNPs and metal oxide-coated sands was electrostatically attractive, resulting in enhancement of CBNP attachment to the coated sands. Interaction energy profiles for CBNP-porous media were calculated using DLVO theory for sphere-plate geometry. Interaction energy profiles demonstrated that the interaction energy for CBNP-quartz sand was repulsive with a primary maximum (energy barrier) of 63.2 KBT, whereas the interaction energies for CBNP-IOCS and CBNP-AOCS were attractive with no energy barriers. Acknowledgement This research was supported by the National Institute of Environmental Research, Korea Ministry of Environment, in 2014.

  4. Synthesis, Aqueous Reactivity, and Biological Evaluation of Carboxylic Acid Ester-Functionalized Platinum–Acridine Hybrid Anticancer Agents

    PubMed Central

    Graham, Leigh A.; Suryadi, Jimmy; West, Tiffany K.; Kucera, Gregory L.; Bierbach, Ulrich

    2012-01-01

    The synthesis of platinum–acridine hybrid agents containing carboxylic acid ester groups is described. The most active derivatives and the unmodified parent compounds showed up to 6-fold higher activity in ovarian cancer (OVCAR-3) and breast cancer (MCF-7, MDA-MB-23) cell lines than cisplatin. Inhibition of cell proliferation at nanomolar concentrations was observed in pancreatic (PANC-1) and non-small cell lung cancer cells (NSCLC, NCI-H460) of 80- and 150-fold, respectively. Introduction of the ester groups did not affect the cytotoxic properties of the hybrids, which form the same monofunctional–intercalative DNA adducts as the parent compounds, as demonstrated in a plasmid unwinding assay. In-line high-performance liquid chromatography and electrospray mass spectrometry (LC-ESMS) shows that the ester moieties undergo platinum-mediated hydrolysis in a chloride concentration-dependent manner to form carboxylate chelates. Potential applications of the chloride-sensitive ester hydrolysis as a self-immolative release mechanism for tumor-selective delivery of platinum–acridines are discussed. PMID:22871158

  5. Adsorption of Cu(II) to ferrihydrite and ferrihydrite-bacteria composites: Importance of the carboxyl group for Cu mobility in natural environments

    NASA Astrophysics Data System (ADS)

    Moon, Ellen M.; Peacock, Caroline L.

    2012-09-01

    Bacterially associated iron (hydr)oxide composites are widespread in natural environments, and by analogy with isolated iron (hydr)oxides and bacteria, are important scavengers of dissolved trace-metals. We precipitated ferrihydrite via rapid Fe(III) hydrolysis in the absence and presence of the non-Fe metabolising, Gram-positive bacterium Bacillus subtilis, commonly found in natural waters, soils and sediments. We combined XRD, SEM, BET and Fe K-edge EXAFS to examine the mineralogy, morphology and crystallinity of the ferrihydrite composites. We find that the mineral fraction of the composites is unaltered in primary mineralogy, morphology and crystallinity compared to pure ferrihydrite. We then measured the adsorption of Cu to ferrihydrite and the ferrihydrite-B. subtilis composites as a function of pH and the ferrihydrite:bacteria mass ratio of the composites, and used EXAFS to determine the molecular mechanisms of Cu adsorption. We determine directly for the first time that Cu uptake by ferrihydrite-B. subtilis composites is the result of adsorption to both the ferrihydrite and B. subtilis fractions. Adsorption of Cu by the B. subtilis fraction results in significant Cu uptake in the low pH regime (pH ˜4, ˜20% of [Cu]total) and significantly enhanced Cu uptake in the mid pH regime. This composite sorption behaviour is in stark contrast to pure ferrihydrite, where Cu adsorption is negligible at low pH. Overall, for composites dominated by either ferrihydrite or B. subtilis, the bacterial fraction is exclusively responsible for Cu adsorption at low pH while the ferrihydrite fraction is predominantly responsible for adsorption at high pH. Furthermore, with an increased mass ratio of bacteria, the dominance of Cu adsorption to the bacterial fraction persists into the mid pH regime and extends significantly into the upper pH region. As such, the distribution of the total adsorbed Cu between the composite fractions is a function of both pH and the ferrihydrite:bacteria mass ratio of the composite. EXAFS shows that Cu adsorbs to ferrihydrite as an inner-sphere, (CuO4Hn)n - 6 bidentate edge-sharing complex; and to ferrihydrite composites as an inner-sphere, (CuO5Hn)n - 8 monodentate complex with carboxyl surface functional groups present on the bacterial fraction plus the bidentate edge-sharing complex on the ferrihydrite fraction. Our new results combined with previous work on Cu sorption to bacteria, humic substances and iron (hydr)oxides coated with humics, demonstrate the universal importance of the carboxyl moiety for Cu sorption and mobility in natural environments. Taken together these results show that Cu-carboxyl binding is the predominant mechanism by which Cu interacts with abiotic and biotic organic matter, and provides a ubiquitous control on Cu fate and mobility in natural waters, soils and sediments. Our results indicate that in environments where a significant proportion of iron (hydr)oxides are intimately intermixed with an organic fraction, we must consider Cu sequestration by these composites in addition to pure mineral phases.

  6. Synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotubes and carbon fiber for improved electro-activated polymeric shape-memory nanocomposite

    NASA Astrophysics Data System (ADS)

    Lu, Haibao; Min Huang, Wei

    2013-06-01

    The present work studies the synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotube (CNT) and carbon fiber on the electrical property and electro-activated recovery behavior of shape memory polymer (SMP) nanocomposites. The combination of CNT and carbon fiber results in improved electrical conductivity in the SMP nanocomposites. Carboxylic acid-functionalized CNTs are grafted onto the carbon fibers and then self-assembled by deposition to significantly enhance the reliability of the bonding between carbon fiber and SMP via van der Waals and covalent crosslink. Furthermore, the self-assembled carboxylic acid-functionalized CNTs and carbon fibers enable the SMP nanocomposites for Joule heating triggered shape recovery.

  7. Geometric, electronic and magnetic structures of S = 19/2 and S = 20/2 thiophene-2-carboxylate functionalized Mn12 single molecule magnets.

    PubMed

    Rodriguez, Jorge H; Ziegler, Christopher J

    2015-01-01

    The geometric and magnetic structures of two structurally related, but magnetically inequivalent, single molecule magnets (SMMs) have been computationally characterized. The first SMM, with formula [Mn12O12(O2CC4H3S)16(H2O)2](-1) (I), has a half-integer spin (S(I) = 19/2) due to ferrimagnetic ordering. The second SMM, with formula Mn12O12(O2CC4H3S)16(H2O)4 (II), has an integer spin (S(II) = 20/2) and its geometric structure has been computationally predicted. Both SMMs include thiophene-2-carboxylate functional groups for potential use in molecular electronics. To determine structural and electronic differences between both SMMs, spin polarized density functional theory was applied to I and II. Hydrogen bonding of two and four Mn-bound water molecules in I and II, respectively, to thiophene-2-carboxylate oxygen atoms and inner cubane oxygen atoms is essential for structural stabilization of both complexes. The one-electron-reduction of I is concomitant with a structural asymmetry within its cubane whereby two ions, of nominal Mn(4+)(Si = 3/2) character, are inequivalent to the other two and acquire an incipient Mn(3+)(Si = 4/2) character. The geometric asymmetry in I provides an extra, albeit small, contribution to its zero field splitting and anisotropy barrier to spin reversal. Thus, despite its lower spin state, the anisotropy barrier of I is only slightly lower than that of II. PMID:25360814

  8. Sorption of heavy metal ions onto carboxylate chitosan derivatives--a mini-review.

    PubMed

    Boamah, Peter Osei; Huang, Yan; Hua, Mingqing; Zhang, Qi; Wu, Jingbo; Onumah, Jacqueline; Sam-Amoah, Livingstone K; Boamah, Paul Osei

    2015-06-01

    Chitosan is of importance for the elimination of heavy metals due to their outstanding characteristics such as the presence of NH2 and -OH functional groups, non-toxicity, low cost and, large available quantities. Modifying a chitosan structure with -COOH group improves it in terms of solubility at pH ?7 without affecting the aforementioned characteristics. Chitosan modified with a carboxylic group possess carboxyl, amino and hydroxyl multifunctional groups which are good for elimination of metal ions. The focal point of this mini-review will be on the preparation and characterization of some carboxylate chitosan derivatives as a sorbent for heavy metal sorption. PMID:25791666

  9. Molecular modeling of the dimeric structure of human lipoprotein lipase and functional studies of the carboxyl-terminal domain.

    PubMed

    Kobayashi, Yoko; Nakajima, Toshiaki; Inoue, Ituro

    2002-09-01

    Lipoprotein lipase (LPL) plays a key role in lipid metabolism. Molecular modeling of dimeric LPL was carried out using insight ii based upon the crystal structures of human, porcine, and horse pancreatic lipase. The dimeric model reveals a saddle-shaped structure and the key heparin-binding residues in the amino-terminal domain located on the top of this saddle. The models of two dimeric conformations - a closed, inactive form and an open, active form - differ with respect to how surface-loop positions affect substrate access to the catalytic site. In the closed form, the surface loop covers the catalytic site, which becomes inaccessible to solvent. Large conformational changes in the open form, especially in the loop and carboxyl-terminal domain, allow substrate access to the active site. To dissect the structure-function relationships of the LPL carboxyl-terminal domain, several residues predicted by the model structure to be essential for the functions of heparin binding and substrate recognition were mutagenized. Arg405 plays an important role in heparin binding in the active dimer. Lys413/Lys414 or Lys414 regulates heparin affinity in both monomeric and dimeric forms. To evaluate the prediction that LPL forms a homodimer in a 'head-to-tail' orientation, two inactive LPL mutants - a catalytic site mutant (S132T) and a substrate-recognition mutant (W390A/W393A/W394A) - were cotransfected into COS7 cells. Lipase activity could be recovered only when heterodimerization occurred in a head-to-tail orientation. After cotransfection, 50% of the wild-type lipase activity was recovered, indicating that lipase activity is determined by the interaction between the catalytic site on one subunit and the substrate-recognition site on the other. PMID:12230584

  10. The central role of ketones in reversible and irreversible hydrothermal organic functional group transformations

    NASA Astrophysics Data System (ADS)

    Yang, Ziming; Gould, Ian R.; Williams, Lynda B.; Hartnett, Hilairy E.; Shock, Everett L.

    2012-12-01

    Studies of hydrothermal reactions involving organic compounds suggest complex, possibly reversible, reaction pathways that link functional groups from reduced alkanes all the way to oxidized carboxylic acids. Ketones represent a critical functional group because they occupy a central position in the reaction pathway, at the point where Csbnd C bond cleavage is required for the formation of the more oxidized carboxylic acids. The mechanisms for the critical bond cleavage reactions in ketones, and how they compete with other reactions are the focus of this experimental study. We studied a model ketone, dibenzylketone (DBK), in H2O at 300 °C and 70 MPa for up to 528 h. Product analysis was performed as a function of time at low DBK conversions to reveal the primary reaction pathways. Reversible interconversion between ketone, alcohol, alkene and alkane functional groups is observed in addition to formation of radical coupling products derived from irreversible Csbnd C and Csbnd H homolytic bond cleavage. The product distributions are time-dependent but the bond cleavage products dominate. The major products that accumulate at longer reaction times are toluene and larger, dehydrogenated structures that are initially formed by radical coupling. The hydrogen atoms generated by dehydrogenation of the coupling products are predominantly consumed in the formation of toluene. Even though bond cleavage products dominate, no carboxylic acids were observed on the timescale of the reactions under the chosen experimental conditions.

  11. 2-(4-Carb­oxy­piperidinium-1-yl)pyridine-3-carboxyl­ate

    PubMed Central

    Fan, Ping; Ge, Chunhua; Sun, Mingjun; Li, Weiwei; Shang, Runshan

    2012-01-01

    The title compound, C12H14N2O4, crystallizes as a zwitterion. A negative charge is delocalized in the deprotonated carboxyl group attached to the pyridine ring. The piperidine N atom accepts a proton and the ring is transformed into a piperidinium cation. There is an intra­molecular N—H?O hydrogen bond between the protonated NH and a carboxyl­ate O atom. In the crystal, an O—H?O hydrogen bond between the carboxyl group and the carboxyl­ate O atom of another mol­ecule generates a helix along the b axis. PMID:22412757

  12. 2-(4-Carb-oxy-piperidinium-1-yl)pyridine-3-carboxyl-ate.

    PubMed

    Fan, Ping; Ge, Chunhua; Sun, Mingjun; Li, Weiwei; Shang, Runshan

    2012-03-01

    The title compound, C(12)H(14)N(2)O(4), crystallizes as a zwitterion. A negative charge is delocalized in the deprotonated carboxyl group attached to the pyridine ring. The piperidine N atom accepts a proton and the ring is transformed into a piperidinium cation. There is an intra-molecular N-H?O hydrogen bond between the protonated NH and a carboxyl-ate O atom. In the crystal, an O-H?O hydrogen bond between the carboxyl group and the carboxyl-ate O atom of another mol-ecule generates a helix along the b axis. PMID:22412757

  13. Factors determining the pKa values of the ionizable groups in proteins: their intrinsic pKas and the effects of hydrogen bonding on buried carboxyl groups 

    E-print Network

    Thurlkill, Richard Lee

    2007-04-25

    A goal of the modern protein chemist is the design of novel proteins with specific activities or functions. One hurdle to overcome is the ability to accurately predict the pKas of ionizable groups upon their burial in the ...

  14. Macroevolutionary trends of atomic composition and related functional group proportion in eukaryotic and prokaryotic proteins.

    PubMed

    Zhang, Yu-Juan; Yang, Chun-Lin; Hao, You-Jin; Li, Ying; Chen, Bin; Wen, Jian-Fan

    2014-01-25

    To fully explore the trends of atomic composition during the macroevolution from prokaryote to eukaryote, five atoms (oxygen, sulfur, nitrogen, carbon, hydrogen) and related functional groups in prokaryotic and eukaryotic proteins were surveyed and compared. Genome-wide analysis showed that eukaryotic proteins have more oxygen, sulfur and nitrogen atoms than prokaryotes do. Clusters of Orthologous Groups (COG) analysis revealed that oxygen, sulfur, carbon and hydrogen frequencies are higher in eukaryotic proteins than in their prokaryotic orthologs. Furthermore, functional group analysis demonstrated that eukaryotic proteins tend to have higher proportions of sulfhydryl, hydroxyl and acylamino, but lower of sulfide and carboxyl. Taken together, an apparent trend of increase was observed for oxygen and sulfur atoms in the macroevolution; the variation of oxygen and sulfur compositions and their related functional groups in macroevolution made eukaryotic proteins carry more useful functional groups. These results will be helpful for better understanding the functional significances of atomic composition evolution. PMID:24262937

  15. Double D-?-A dye linked by 2,2'-bipyridine dicarboxylic acid: influence of para- and meta-substituted carboxyl anchoring group.

    PubMed

    Ganesan, Paramaguru; Chandiran, Aravind Kumar; Gao, Peng; Rajalingam, Renganathan; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

    2015-04-01

    Starting from 2,2'-bipyridine dicarboxylic acid, two new (D-?-A)2 sensitizers, including m-DA with the carboxyl anchoring group substituted meta to the donor-bridge moiety and p-DA with a para-substituted anchoring group, were synthesized in order to evaluate the impact of the position of the anchoring group on the optical, electrochemical, and photovoltaic properties of dye-sensitized solar cells. p-DA exhibits red-shifted absorption behavior compared to m-DA, owing to the more efficiently extended ?-conjugation with para substitution. Both m-DA and p-DA are adsorbed on the mesoporous TiO2 surface by using both of their carboxylic acid groups in a bianchoring mode, which is confirmed through attenuated total reflectance FTIR analysis. Red-shifted absorption of p-DA assists the achievement of a red-shifted incident photon-to-electron conversion efficiency and a higher short-circuit current density than m-DA. The photogenerated electron lifetime in TiO2 is also found to be higher for para substituted p-DA than the meta-substituted m-DA, which results in a higher open-circuit voltage. All of the results suggest that dicarboxyl-2,2'-bipyridine can be used as an acceptor for metal-free organic sensitizers. However, the anchoring segments should be adjusted to the favorable position of the corresponding donor-bridge moieties for better conjugation. PMID:25656067

  16. Study on the pore structure and oxygen-containing functional groups devoting to the hydrophilic force of dewatered lignite

    NASA Astrophysics Data System (ADS)

    Zhang, Yanli; Jing, Xiaoxia; Jing, Kaige; Chang, Liping; Bao, Weiren

    2015-01-01

    In order to explore the water-holding capacity of dewatered lignite and the contribution of pore structure and oxygen-containing functional groups to it, a kind of typical Chinese lignite was dried under the atmosphere of nitrogen for different temperatures and times, and then was subjected to a process of moisture re-adsorption at the temperature of 25 °C and relative humidity of 75%. Nitrogen adsorption and chemical titration methods were used to examine the pore structure parameters and amounts of oxygen-containing functional groups, respectively. The results indicate that the porous structure and oxygen-containing functional groups in lignite are two main factors influencing the hydrophilicity of dewatered coal, and their contributions are varied with the change of drying conditions. The change of water-holding capacity of pore structure is primarily attributed to the shrinkage or collapse of macro- and mesoporous and it decreases with the increase of drying temperature. The oxygen-containing functional groups mainly include phenolic hydroxyl, carbonyl, carboxyl and methoxyl groups, and the order of their hydrophilicity is: carboxyl group > phenolic hydroxyl group > carbonyl group > methoxyl group. Moreover, the water-holding capacity for the same kind of oxygen-containing functional groups in dewatered coal obtained at different temperature is not a fixed one, their hydrophilic forces decrease with the increase of drying temperature. For the coal samples dried for 60 min under different temperature, the contribution of pore structure and oxygen-containing functional groups to the equilibrium moisture content (EMC) of dewatered lignite is: pore structure > phenolic hydroxyl group > carboxyl group > carbonyl group > methoxyl group. The contribution of total oxygen-containing functional groups to the EMC at below 280 °C is more obvious, and that of pore structure is the principal factor thereafter.

  17. Identifying organic aerosol sources by comparing functional group composition in chamber and atmospheric particles

    PubMed Central

    Russell, Lynn M.; Bahadur, Ranjit; Ziemann, Paul J.

    2011-01-01

    Measurements of submicron particles by Fourier transform infrared spectroscopy in 14 campaigns in North America, Asia, South America, and Europe were used to identify characteristic organic functional group compositions of fuel combustion, terrestrial vegetation, and ocean bubble bursting sources, each of which often accounts for more than a third of organic mass (OM), and some of which is secondary organic aerosol (SOA) from gas-phase precursors. The majority of the OM consists of alkane, carboxylic acid, hydroxyl, and carbonyl groups. The organic functional groups formed from combustion and vegetation emissions are similar to the secondary products identified in chamber studies. The near absence of carbonyl groups in the observed SOA associated with combustion is consistent with alkane rather than aromatic precursors, and the absence of organonitrate groups can be explained by their hydrolysis in humid ambient conditions. The remote forest observations have ratios of carboxylic acid, organic hydroxyl, and nonacid carbonyl groups similar to those observed for isoprene and monoterpene chamber studies, but in biogenic aerosols transported downwind of urban areas the formation of esters replaces the acid and hydroxyl groups and leaves only nonacid carbonyl groups. The carbonyl groups in SOA associated with vegetation emissions provides striking evidence for the mechanism of esterification as the pathway for possible oligomerization reactions in the atmosphere. Forest fires include biogenic emissions that produce SOA with organic components similar to isoprene and monoterpene chamber studies, also resulting in nonacid carbonyl groups in SOA. PMID:21317360

  18. An experimental and density functional study on conformational and spectroscopic analysis of 5-methoxyindole-2-carboxylic acid.

    PubMed

    Cinar, Mehmet; Karabacak, Mehmet; Asiri, Abdullah M

    2015-02-25

    In this article, a brief conformational and spectroscopic characterization of 5-methoxyindole-2-carboxylic acid (5-MeOICA) via experimental techniques and applications of quantum chemical methods is presented. The conformational analysis of the studied molecule was determined theoretically using density functional computations for ground state, and compared with previously reported experimental findings. The vibrational transitions were examined by measured FT-IR and FT-Raman spectroscopic data, and also results obtained from B3LYP and CAM-B3LYP functionals in combination with 6-311++G(d,p) basis set. The recorded proton and carbon NMR spectra in DMSO solution were analyzed to obtain the exact conformation. Due to intermolecular hydrogen bondings, NMR calculations were performed for the dimeric form of 5-MeOICA and so chemical shifts of those protons were predicted more accurately. Finally, electronic properties of steady compound were identified by a comparative study of UV absorption spectra in ethanol and water solution and TD-DFT calculations. PMID:25255480

  19. Spherical functions on the de Sitter group

    NASA Astrophysics Data System (ADS)

    Varlamov, V. V.

    2007-01-01

    Matrix elements and spherical functions of irreducible representations of the de Sitter group are studied on the various homogeneous spaces of this group. It is shown that a universal covering of the de Sitter group gives rise to quaternion Euler angles. An explicit form of Casimir and Laplace-Beltrami operators on the homogeneous spaces is given. Different expressions of the matrix elements and spherical functions are given in terms of multiple hypergeometric functions both for finite-dimensional and unitary representations of the principal series of the de Sitter group. Applications of the functions obtained to the hydrogen atom problem are considered.

  20. A comprehensive classification and nomenclature of carboxyl–carboxyl(ate) supramolecular motifs and related catemers: implications for biomolecular systems

    PubMed Central

    D’Ascenzo, Luigi; Auffinger, Pascal

    2015-01-01

    Carboxyl and carboxylate groups form important supramolecular motifs (synthons). Besides carboxyl cyclic dimers, carboxyl and carboxylate groups can associate through a single hydrogen bond. Carboxylic groups can further form polymeric-like catemer chains within crystals. To date, no exhaustive classification of these motifs has been established. In this work, 17 association types were identified (13 carboxyl–carboxyl and 4 carboxyl–carboxylate motifs) by taking into account the syn and anti carboxyl conformers, as well as the syn and anti lone pairs of the O atoms. From these data, a simple rule was derived stating that only eight distinct catemer motifs involving repetitive combinations of syn and anti carboxyl groups can be formed. Examples extracted from the Cambridge Structural Database (CSD) for all identified dimers and catemers are presented, as well as statistical data related to their occurrence and conformational preferences. The inter-carboxyl(ate) and carboxyl(ate)–water hydrogen-bond properties are described, stressing the occurrence of very short (strong) hydrogen bonds. The precise characterization and classification of these supramolecular motifs should be of interest in crystal engineering, pharmaceutical and also biomolecular sciences, where similar motifs occur in the form of pairs of Asp/Glu amino acids or motifs involving ligands bearing carboxyl(ate) groups. Hence, we present data emphasizing how the analysis of hydrogen-containing small molecules of high resolution can help understand structural aspects of larger and more complex biomolecular systems of lower resolution. PMID:25827369

  1. A CuII coordination polymer based on incorporated carboxylate and sulfonate groups: Synthesis, crystal structure, and magnetic properties

    NASA Astrophysics Data System (ADS)

    Han, Yinfeng; Zheng, Zebao; Wang, Chang'an; Sun, Jiafeng; Li, Xiaoyan; Zhang, Jianping; Xiao, Jing; He, Guofang; Li, Liqing

    2015-01-01

    A CuII coordination polymer, [Cu(sbpc)(phen)(H2O)]?H2O 1, has been synthesized and characterized structurally and magnetically (H2sbpc = 4-sulfobiphenyl-4?-carboxylic acid, phen = 1,10-phenanthroline). Single-crystal structural analysis shows that 1 consists of dinuclear [Cu2(CO2)2] units bridged via sbpc2- to afford a 1-D chain, which then extends into the 3-D coordination polymer supramolecular network by O-H⋯O hydrogen bonds and ?⋯? interactions. Magnetic measurements indicate that complex 1 exhibits weak antiferromagnetic coupling.

  2. Factors determining the pKa values of the ionizable groups in proteins: their intrinsic pKas and the effects of hydrogen bonding on buried carboxyl groups

    E-print Network

    Thurlkill, Richard Lee

    2007-04-25

    that is not well understood is the effect of hydrogen bonds. The side chain carboxyl of Asp33 in RNase Sa is buried, forms 3 intramolecular hydrogen bonds, and has a pKa of 2.4 in the folded protein. One of these hydrogen bonds is to the side chain hydroxyl of Thr...

  3. Analytical methodology for determination of organic aerosol functional group distributions.

    PubMed

    Kalafut-Pettibone, Alicia J; McGivern, W Sean

    2013-04-01

    Secondary organic aerosol (SOA) particles result from the condensation of oxidized volatile organic compounds (VOC) and consist of a complex mixture that is not conducive to complete compositional analysis. We present a simple methodology for determining the quantities of aldehydes and ketones, alcohols, and carboxylic acids in such samples via derivatization and high-performance liquid chromatography (HPLC) with ultraviolet-visible absorption detection and tandem mass spectrometry (MS/MS). Useful concentration ranges are presented with an examination of the specificity of these compounds in multiply substituted systems. Such data are valuable in modeling the formation of laboratory-generated aerosols and in identifying point sources of field-collected aerosol samples. Calibration curves on standard samples, MS/MS transitions, including collisionally induced dissociation (CID) products, and a quantitative examination of the specificity of the derivatization reagents toward multiple functional groups are presented for a series of aliphatic standard samples. These methods are then applied to filter extracts from SOA derived from 1-iodooctane photolysis at 254 nm to demonstrate the methodology on a complex system. Ultimately, this methodology enables the measurement of variations in the chemical nature of the oxygen within an SOA particle, providing a distribution of functional group concentrations. PMID:23461576

  4. FTIR Analysis of Functional Groups in Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Shokri, S. M.; McKenzie, G.; Dransfield, T. J.

    2012-12-01

    Secondary organic aerosols (SOA) are suspensions of particulate matter composed of compounds formed from chemical reactions of organic species in the atmosphere. Atmospheric particulate matter can have impacts on climate, the environment and human health. Standardized techniques to analyze the characteristics and composition of complex secondary organic aerosols are necessary to further investigate the formation of SOA and provide a better understanding of the reaction pathways of organic species in the atmosphere. While Aerosol Mass Spectrometry (AMS) can provide detailed information about the elemental composition of a sample, it reveals little about the chemical moieties which make up the particles. This work probes aerosol particles deposited on Teflon filters using FTIR, based on the protocols of Russell, et al. (Journal of Geophysical Research - Atmospheres, 114, 2009) and the spectral fitting algorithm of Takahama, et al (submitted, 2012). To validate the necessary calibration curves for the analysis of complex samples, primary aerosols of key compounds (e.g., citric acid, ammonium sulfate, sodium benzoate) were generated, and the accumulated masses of the aerosol samples were related to their IR absorption intensity. These validated calibration curves were then used to classify and quantify functional groups in SOA samples generated in chamber studies by MIT's Kroll group. The fitting algorithm currently quantifies the following functionalities: alcohols, alkanes, alkenes, amines, aromatics, carbonyls and carboxylic acids.

  5. Cinoxacin complexes with divalent metal ions. Spectroscopic characterization. Crystal structure of a new dinuclear Cd(II) complex having two chelate-bridging carboxylate groups. Antibacterial studies.

    PubMed

    Ruíz, M; Perelló, L; Server-Carrió, J; Ortiz, R; García-Granda, S; Díaz, M R; Cantón, E

    1998-03-01

    Several cinoxacin (HCx) complexes with divalent metal ions have been prepared and characterized by spectroscopic techniques. The crystal structure of [Cd2(Cx)4(H2O)2].10H2O has been determined by X-ray diffraction. The complex is triclinic, space group P1 with unit-cell dimensions: a = 10.412(2), b = 11.119(2), c = 13.143(6)A, chi== 76.78(4) degrees, beta = 74.59(3) degrees, gamma = 77.12(3) degrees, V = 1406.0(8) A3. In this complex each cadmium atom is heptacoordinated: the metal environment is formed by two Oketo and two Ocarbox atoms from two different cinoxacinate monoanions, two carboxylate oxygen atoms from a third cinoxacinate ligand and by one water oxygen atom on the seventh position. Two of the cinoxacinate ions act as tridentate chelate and bridging ligands and the other one as a bidentate chelate ligand. In the bridging monoanions the carboxylate group is behaving as a chelate ligand. All the complexes were screened for their activity against several bacteria, showing activity similar to that of cinoxacin. Additionally, the number of bacteria killed after 3 h of incubation with cinoxacin, [Cu(Cx)2].2H2O and [Co(Cx)3]Na.10H2O complexes was determined against E. coli ATCC 25922; the copper compound presents paradoxical effect which has been described and related to the mechanism of action of quinolones. PMID:9654749

  6. Liapunov functions Nonlinear dynamics reading group

    E-print Network

    Daunizeau, Jean

    Liapunov functions revisited Nonlinear dynamics reading group Maria Joao 1st October, 2009 #12;Nonlinear dynamics reading group I. Introduction Non-linear dynamical system: Autonomous: Non;Nonlinear dynamics reading group I. Introduction Good place to start: (1) determine equilibrium points (2

  7. Quantitative evaluation of interaction force between functional groups in protein and polymer brush surfaces.

    PubMed

    Sakata, Sho; Inoue, Yuuki; Ishihara, Kazuhiko

    2014-03-18

    To understand interactions between polymer surfaces and different functional groups in proteins, interaction forces were quantitatively evaluated by force-versus-distance curve measurements using atomic force microscopy with a functional-group-functionalized cantilever. Various polymer brush surfaces were systematically prepared by surface-initiated atom transfer radical polymerization as well-defined model surfaces to understand protein adsorption behavior. The polymer brush layers consisted of phosphorylcholine groups (zwitterionic/hydrophilic), trimethylammonium groups (cationic/hydrophilic), sulfonate groups (anionic/hydrophilic), hydroxyl groups (nonionic/hydrophilic), and n-butyl groups (nonionic/hydrophobic) in their side chains. The interaction forces between these polymer brush surfaces and different functional groups (carboxyl groups, amino groups, and methyl groups, which are typical functional groups existing in proteins) were quantitatively evaluated by force-versus-distance curve measurements using atomic force microscopy with a functional-group-functionalized cantilever. Furthermore, the amount of adsorbed protein on the polymer brush surfaces was quantified by surface plasmon resonance using albumin with a negative net charge and lysozyme with a positive net charge under physiological conditions. The amount of proteins adsorbed on the polymer brush surfaces corresponded to the interaction forces generated between the functional groups on the cantilever and the polymer brush surfaces. The weakest interaction force and least amount of protein adsorbed were observed in the case of the polymer brush surface with phosphorylcholine groups in the side chain. On the other hand, positive and negative surfaces generated strong forces against the oppositely charged functional groups. In addition, they showed significant adsorption with albumin and lysozyme, respectively. These results indicated that the interaction force at the functional group level might be a suitable parameter for understanding protein adsorption. PMID:24564418

  8. Boolean Functions, Invariance Groups and Parallel Complexity

    Microsoft Academic Search

    Peter Clote; Evangelos Kranakis

    1989-01-01

    The authors study the invariance groups S(f) of Boolean functions f?Bn on n variables. They give necessary and sufficient conditions for a general permutation group to be of the form S(f), for some f ?Bn. This leads to an almost optimal algorithm for deciding the representability of an arbitrary permutation group. For cyclic groups G⩽ Sn, an NC-algorithm is given

  9. Water Soluble Metallo-Phthalocyanines: The Role of the Functional Groups on the Spectral and Photophysical Properties

    Microsoft Academic Search

    Vera T. Verdree; Serhii Pakhomov; Guifa Su; Michael W. Allen; Amber C. Countryman; Robert P. Hammer; Steven A. Soper

    2007-01-01

    Strategies are reported that produce symmetrical metal-free and metallo-phthalocyanine dyes, Pc and MPc, respectively, containing\\u000a various numbers of water solubilizing carboxylic acid groups on their periphery that provide a dual role by also serving as\\u000a functional groups to covalently link primary amine-containing targets to these dyes. In order to induce water compatibility\\u000a and to minimize the degree of aggregation, the

  10. A NCS mediated oxidative C-H bond functionalization: direct esterification between a C(sp(3))-H bond and carboxylic acids.

    PubMed

    Zheng, Yang; Mao, Jincheng; Rong, Guangwei; Xu, Xinfang

    2015-05-12

    A transition metal free oxidative C-H bond functionalization/esterification of ?-alkoxy alkanes with acids is described in this report. This method is effectively mediated by NCS instead of traditional oxidants, like TBHP or its derivatives, and directly generates the esterification products in moderate to high yield under mild conditions. This tranformation constitutes a practical and general approach toward various ?-acyloxy ethers with broad substrate generality; alkyl-, aryl-, alkenyl- and alkynyl-carboxylic acids are all well tolerated. PMID:25921733

  11. High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO3 nanocomposites and rare earth metal complexes: Preparation and characterization

    NASA Astrophysics Data System (ADS)

    Cao, X. T.; Showkat, A. M.; Wang, Z.; Lim, K. T.

    2015-03-01

    Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb3+) was synthesized by a combination of surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, Friedel-Crafts alkylation reaction and coordinate chemistry. Initially, a modification of surface of BTO was conducted by an exchange process with S-benzyl S'-trimethoxysilylpropyltrithiocarbonate to create macro-initiator for polymerization of styrene. Subsequently, aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-COOH) was generated by substitution reaction between 4-(Chloromethyl) benzoic acid and PSt chains. The coordination of the nanohybrids with Tb3+ ions afforded fluorescent Tb3+ tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb3+) complexes. Structure, morphology, and fluorescence properties of nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR and SEM analyses confirmed the formation of BTO-g-PSt-Tb3+nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb3+ complexes were investigated by fluorescence spectroscopy.

  12. ERGODIC PROPERTIES OF FUNCTION GROUPS URSULA HAMENST

    E-print Network

    Hamenstädt, Ursula

    ERGODIC PROPERTIES OF FUNCTION GROUPS URSULA HAMENST  ADT Abstract. Let #26; PSL(2; C by Sonderforschungsbereich 256. 1 #12; 2 URSULA HAMENST  ADT with the algebraic topology. Thus a sequence of representations

  13. Four super water-stable lanthanide-organic frameworks with active uncoordinated carboxylic and pyridyl groups for selective luminescence sensing of Fe(3.).

    PubMed

    Liang, Yu-Tong; Yang, Guo-Ping; Liu, Bo; Yan, Yang-Tian; Xi, Zheng-Ping; Wang, Yao-Yu

    2015-07-14

    Four super water-stable isostructural lanthanide-organic frameworks, [Ln(HL)(H2O)2]n·2H2O (1-Ln) (Ln = Eu, Tb, Nd and Sm), have been successfully synthesized under hydrothermal conditions with 3,5-di(2,4-dicarboxylphenyl)pyridine (H4L) and Ln(NO3)3·6H2O. 1-Ln shows a novel 2D layered structure with uncoordinated carboxylic and pyridyl groups pointing to the interior of interlayer channels. The luminescent properties of 1-Eu in the solid state and one steeped in aqueous solution have been measured, which show excellent luminescence and good luminescent stability in water. Next 1-Eu was chosen as a probe for sensing different metal ions. Consequently, 1-Eu exhibits a highly selective response to Fe(3+) through the luminescence quenching effect in aqueous solutions. The probable mechanisms of the quenching effects have been investigated in detail. PMID:26133017

  14. Carboxyl Group Footprinting Mass Spectrometry and Molecular Dynamics Identify Key Interactions in the HER2-HER3 Receptor Tyrosine Kinase Interface* ?

    PubMed Central

    Collier, Timothy S.; Diraviyam, Karthikeyan; Monsey, John; Shen, Wei; Sept, David; Bose, Ron

    2013-01-01

    The HER2 receptor tyrosine kinase is a driver oncogene in many human cancers, including breast and gastric cancer. Under physiologic levels of expression, HER2 heterodimerizes with other members of the EGF receptor/HER/ErbB family, and the HER2-HER3 dimer forms one of the most potent oncogenic receptor pairs. Previous structural biology studies have individually crystallized the kinase domains of HER2 and HER3, but the HER2-HER3 kinase domain heterodimer structure has yet to be solved. Using a reconstituted membrane system to form HER2-HER3 kinase domain heterodimers and carboxyl group footprinting mass spectrometry, we observed that HER2 and HER3 kinase domains preferentially form asymmetric heterodimers with HER3 and HER2 monomers occupying the donor and acceptor kinase positions, respectively. Conformational changes in the HER2 activation loop, as measured by changes in carboxyl group labeling, required both dimerization and nucleotide binding but did not require activation loop phosphorylation at Tyr-877. Molecular dynamics simulations on HER2-HER3 kinase dimers identify specific inter- and intramolecular interactions and were in good agreement with MS measurements. Specifically, several intermolecular ionic interactions between HER2 Lys-716-HER3 Glu-909, HER2 Glu-717-HER3 Lys-907, and HER2 Asp-871-HER3 Arg-948 were identified by molecular dynamics. We also evaluated the effect of the cancer-associated mutations HER2 D769H/D769Y, HER3 E909G, and HER3 R948K (also numbered HER3 E928G and R967K) on kinase activity in the context of this new structural model. This study provides valuable insights into the EGF receptor/HER/ErbB kinase structure and interactions, which can guide the design of future therapies. PMID:23843458

  15. Carboxylic acid functionalization prevents the translocation of multi-walled carbon nanotubes at predicted environmentally relevant concentrations into targeted organs of nematode Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Nouara, Abdelli; Wu, Qiuli; Li, Yinxia; Tang, Meng; Wang, Haifang; Zhao, Yuliang; Wang, Dayong

    2013-06-01

    Carboxyl (-COOH) surface modified multi-walled carbon nanotubes (MWCNTs-COOH) can be used for targeted delivery of drugs and imaging. However, whether MWCNTs-COOH at environmentally relevant concentrations exert certain toxic effects on multicellular organisms and the underlying mechanisms are still largely unclear. In the present study, we applied the nematode Caenorhabditis elegans to evaluate the properties of MWCNTs-COOH at environmentally relevant concentrations by comparing the effects of MWCNTs and MWCNTs-COOH exposure on C. elegans from L1-larvae to adult at concentrations of 0.001-1000 ?g L-1. Exposure to MWCNTs could potentially damage the intestine (primary targeted organ) at concentrations greater than 0.1 ?g L-1 and functions of neurons and reproductive organ (secondary targeted organs) at concentrations greater than 0.001 ?g L-1. Carboxyl modification prevented the toxicity of MWCNTs on the primary and the secondary targeted organs at concentrations less than 100 ?g L-1, suggesting that carboxyl modification can effectively prevent the adverse effects of MWCNTs at environmentally relevant concentrations. After exposure, MWCNTs-COOH (1 mg L-1) were translocated into the spermatheca and embryos in the body through the primary targeted organs. However, MWCNTs-COOH (10 ?g L-1) were not observed in spermatheca and embryos in the body of nematodes. Moreover, relatively high concentrations of MWCNTs-COOH exposed nematodes might have a hyper-permeable intestinal barrier, whereas MWCNTs-COOH at environmentally relevant concentrations effectively sustained the normally permeable state for the intestinal barrier. Therefore, we elucidated the cellular basis of carboxyl modification to prevent toxicity of MWCNTs at environmentally relevant concentrations. Our data highlights the key role of biological barriers in the primary targeted organs to block toxicity formation from MWCNTs, which will be useful for the design of effective prevention strategies against MWCNTs toxicity.Carboxyl (-COOH) surface modified multi-walled carbon nanotubes (MWCNTs-COOH) can be used for targeted delivery of drugs and imaging. However, whether MWCNTs-COOH at environmentally relevant concentrations exert certain toxic effects on multicellular organisms and the underlying mechanisms are still largely unclear. In the present study, we applied the nematode Caenorhabditis elegans to evaluate the properties of MWCNTs-COOH at environmentally relevant concentrations by comparing the effects of MWCNTs and MWCNTs-COOH exposure on C. elegans from L1-larvae to adult at concentrations of 0.001-1000 ?g L-1. Exposure to MWCNTs could potentially damage the intestine (primary targeted organ) at concentrations greater than 0.1 ?g L-1 and functions of neurons and reproductive organ (secondary targeted organs) at concentrations greater than 0.001 ?g L-1. Carboxyl modification prevented the toxicity of MWCNTs on the primary and the secondary targeted organs at concentrations less than 100 ?g L-1, suggesting that carboxyl modification can effectively prevent the adverse effects of MWCNTs at environmentally relevant concentrations. After exposure, MWCNTs-COOH (1 mg L-1) were translocated into the spermatheca and embryos in the body through the primary targeted organs. However, MWCNTs-COOH (10 ?g L-1) were not observed in spermatheca and embryos in the body of nematodes. Moreover, relatively high concentrations of MWCNTs-COOH exposed nematodes might have a hyper-permeable intestinal barrier, whereas MWCNTs-COOH at environmentally relevant concentrations effectively sustained the normally permeable state for the intestinal barrier. Therefore, we elucidated the cellular basis of carboxyl modification to prevent toxicity of MWCNTs at environmentally relevant concentrations. Our data highlights the key role of biological barriers in the primary targeted organs to block toxicity formation from MWCNTs, which will be useful for the design of effective prevention strategies against MWCNTs toxicity. Electronic supplementary information (ESI) available. See DOI: 10

  16. Di-iron-carboxylate proteins.

    PubMed

    Nordlund, P; Eklund, H

    1995-12-01

    Di-iron centers bridged by carboxylate residues and oxide/hydroxide groups have so far been seen in four classes of proteins involved in dioxygen chemistry or phosphoryl transfer reactions. The dinuclear iron centers in these proteins are coordinated by histidines and additional carboxylate ligands. Recent structural data on some of these enzymes, combined with spectroscopic and kinetic data, can now serve as a base for detailed mechanistic suggestions. The di-iron sites in the major class of hydroxylase-oxidase enzymes, which contains ribonucleotide reductase and methane monooxygenase, show significant flexibility in the geometry of their coordination of three or more carboxylate groups. This flexibility, combined with a relatively low coordination number, and a buried environment suitable for reactive oxygen chemistry, explains their efficient harnessing of the oxidation power of molecular oxygen. PMID:8749363

  17. FT-IR quantification of the carbonyl functional group in aqueous-phase secondary organic aerosol from phenols

    NASA Astrophysics Data System (ADS)

    George, Kathryn M.; Ruthenburg, Travis C.; Smith, Jeremy; Yu, Lu; Zhang, Qi; Anastasio, Cort; Dillner, Ann M.

    2015-01-01

    Recent findings suggest that secondary organic aerosols (SOA) formed from aqueous-phase reactions of some organic species, including phenols, contribute significantly to particulate mass in the atmosphere. In this study, we employ a Fourier transform infrared (FT-IR) spectroscopic technique to identify and quantify the functional group makeup of phenolic SOA. Solutions containing an oxidant (hydroxyl radical or 3,4-dimethoxybenzaldehyde) and either one phenol (phenol, guaiacol, or syringol) or a mixture of phenols mimicking softwood or hardwood emissions were illuminated to make SOA, atomized, and collected on a filter. We produced laboratory standards of relevant organic compounds in order to develop calibrations for four functional groups: carbonyls (Cdbnd O), saturated C-H, unsaturated C-H and O-H. We analyzed the SOA samples with transmission FT-IR to identify and determine the amounts of the four functional groups. The carbonyl functional group accounts for 3-12% of the SOA sample mass in single phenolic SOA samples and 9-14% of the SOA sample mass in mixture samples. No carbonyl functional groups are present in the initial reactants. Varying amounts of each of the other functional groups are observed. Comparing carbonyls measured by FT-IR (which could include aldehydes, ketones, esters, and carboxylic acids) with eight small carboxylic acids measured by ion chromatography indicates that the acids only account for an average of 20% of the total carbonyl reported by FT-IR.

  18. A Mononuclear Carboxylate-Rich Oxoiron(IV) Complex: a Structural and Functional Mimic of TauD Intermediate ‘J’

    PubMed Central

    McDonald, Aidan R.; Guo, Yisong; Vu, Van V.; Bominaar, Emile L.; Münck, Eckard; Que, Lawrence

    2012-01-01

    The pentadentate ligand nBu-P2DA (2(b), nBu-P2DA = N-(1?,1?-bis(2-pyridyl)pentyl)iminodiacetate) was designed to bind an iron center in a carboxylate-rich environment similar to that found in the active sites of TauD and other ?-ketoglutarate-dependent mononuclear non-heme iron enzymes. The iron(II) complex nBu4N[FeII(Cl)(nBu-P2DA)] (3(b)-Cl) was synthesized and crystallographically characterized to have a 2-pyridine-2-carboxylate donor set in the plane perpendicular to the Fe-Cl bond. Reaction of 3(b)-Cl with N-heterocyclic amines such as pyridine or imidazole yielded the N-heterocyclic amine adducts [FeII(N)(nBu-P2DA)]. These adducts in turn reacted with oxo-transfer reagents at ?95 °C to afford a short-lived oxoiron(IV) complex [FeIV(O)(nBu-P2DA)] (5(b)) in yields as high as 90% depending on the heterocycle used. Complex 5(b) exhibits near-IR absorption features (?max = 770 nm) and Mossbauer parameters (? = 0.04 mm/s; ?EQ = 1.13 mm/s; D = 27±2 cm?1) characteristic of an S = 1 oxoiron(IV) species. Direct evidence for an Fe=O bond of 1.66 Å was found from EXAFS analysis. DFT calculations on 5(b) in its S =1 spin state afforded a geometry-optimized structure consistent with the EXAFS data. They further demonstrated that the replacement of two pyridine donors in [FeIV(O)(N4Py)]2+ (N4Py = N,N-(bis(2-pyridyl)methyl)N-bis(2-pyridylmethyl)amine) with carboxylate donors in 5(b) decreased the energy gap between the ground S = 1 and the excited S = 2 states, reflecting the weaker equatorial ligand field of 5(b) and accounting for its larger D value. Complex 5(b) reacted readily with dihydrotoluene, methyldiphenylphosphine and ferrocene at ?60 °C, and in all cases was approximately a 5-fold more reactive oxidant than [FeIV(O)(N4Py)]2+. The reactivity differences between these two complexes may arise from a combination of electronic and steric factors. Carboxylate-rich 5(b) represents the closest structural mimic reported thus far of the oxoiron(IV) intermediate (‘J’) found in TauD and provides us with vital insights into the role carboxylate ligands play in modulating the spectroscopic and reactivity properties of the non-heme oxoiron(IV) moiety. PMID:23267430

  19. Carboxylate binding modes in zinc proteins: A theoretical study

    PubMed Central

    Ryde, U

    1999-01-01

    The relative energies of different coordination modes (bidentate, monodentate, syn, and anti) of a carboxylate group bound to a zinc ion have been studied by the density functional method B3LYP with large basis sets on realistic models of the active site of several zinc proteins. In positively charged four-coordinate complexes, the mono- and bidentate coordination modes have almost the same energy (within 10 kJ/mol). However, if there are negatively charged ligands other than the carboxylate group, the monodentate binding mode is favored. In general, the energy difference between monodentate and bidentate coordination is small, 4-24 kJ/mol, and it is determined more by hydrogen-bond interactions with other ligands or second-sphere groups than by the zinc-carboxylate interaction. Similarly, the activation energy for the conversion between the two coordination modes is small, approximately 6 kJ/mol, indicating a very flat Zn-O potential surface. The energy difference between syn and anti binding modes of the monodentate carboxylate group is larger, 70-100 kJ/mol, but this figure again strongly depends on interactions with second-sphere molecules. Our results also indicate that the pK(a) of the zinc-bound water ligand in carboxypeptidase and thermolysin is 8-9. PMID:10545376

  20. A water-soluble carboxylic-functionalized chemosensor for detecting Al(3+) in aqueous media and living cells: Experimental and theoretical studies.

    PubMed

    Jun Lee, Jae; Jin Park, Gyeong; Sung Kim, Yong; Young Lee, Sun; Ji Lee, Hyun; Noh, Insup; Kim, Cheal

    2015-07-15

    A new water-soluble carboxylic-functionalized chemosensor 1 was designed and synthesized. 1 exhibited the selective fluorescence enhancement toward aluminum ions with a 1:1 complexation stoichiometry in aqueous solution. The detection limit (24nM) of 1 for Al(3+) is about two order lower than the WHO guideline (7.41?M) for the drinking water. 1 was successfully applied to living cells and real samples for detecting Al(3+). Moreover, the sensing mechanism originated from the inhibited excited-state intramolecular proton transfer (ESIPT) process and the chelation-enhanced fluorescence (CHEF) effect, as supported by theoretical calculations. PMID:25747507

  1. Department and function: Group Leader, Clinical Immunology

    E-print Network

    Manstein, Dietmar J.

    Department and function: Group Leader, Clinical Immunology Education: 1981-1986 Biology in Hannover Positions: 1987-recent Scientist in the Division of Clinical Immunology, MHH 1992 PhD in Biology, MHH 2003 Habilitation in Immunology, MHH Major research interests: Analysis of Natural Killer (NK) cell subpopulations

  2. Carboxyl-terminal domain of MUC16 imparts tumorigenic and metastatic functions through nuclear translocation of JAK2 to pancreatic cancer cells

    PubMed Central

    Das, Srustidhar; Lakshmanan, Imayavaramban; Majhi, Prabin D.; Smith, Lynette M.; Wagner, Kay-Uwe; Batra, Surinder K.

    2015-01-01

    MUC16 (CA125) is a type-I transmembrane glycoprotein that is up-regulated in multiple cancers including pancreatic cancer (PC). However, the existence and role of carboxyl-terminal MUC16 generated following its cleavage in PC is unknown. Our previous study using a systematic dual-epitope tagged domain deletion approach of carboxyl-terminal MUC16 has demonstrated the generation of a 17-kDa cleaved MUC16 (MUC16-Cter). Here, we demonstrate the functional significance of MUC16-Cter in PC using the dual-epitope tagged version (N-terminal FLAG- and C-terminal HA-tag) of 114 carboxyl-terminal residues of MUC16 (F114HA). In vitro analyses using F114HA transfected MiaPaCa-2 and T3M4 cells showed enhanced proliferation, motility and increased accumulation of cells in the G2/M phase with apoptosis resistance, a feature associated with cancer stem cells (CSCs). This was supported by enrichment of ALDH+ CSCs along with enhanced drug-resistance. Mechanistically, we demonstrate a novel function of MUC16-Cter that promotes nuclear translocation of JAK2 resulting in phosphorylation of Histone-3 up-regulating stemness-specific genes LMO2 and NANOG. Jak2 dependence was demonstrated using Jak2+/+ and Jak2?/? cells. Using eGFP-Luciferase labeled cells, we demonstrate enhanced tumorigenic and metastatic potential of MUC16-Cter in vivo. Taken together, we demonstrate that MUC16-Cter mediated enrichment of CSCs is partly responsible for tumorigenic, metastatic and drug-resistant properties of PC cells. PMID:25691062

  3. Transport of carboxyl-functionalized carbon black nanoparticles in saturated porous media: Column experiments and model analyses.

    PubMed

    Kang, Jin-Kyu; Yi, In-Geol; Park, Jeong-Ann; Kim, Song-Bae; Kim, Hyunjung; Han, Yosep; Kim, Pil-Je; Eom, Ig-Chun; Jo, Eunhye

    2015-01-01

    The aim of this study was to investigate the transport behavior of carboxyl-functionalized carbon black nanoparticles (CBNPs) in porous media including quartz sand, iron oxide-coated sand (IOCS), and aluminum oxide-coated sand (AOCS). Two sets of column experiments were performed under saturated flow conditions for potassium chloride (KCl), a conservative tracer, and CBNPs. Breakthrough curves were analyzed to obtain mass recovery and one-dimensional transport model parameters. The first set of experiments was conducted to examine the effects of metal (Fe, Al) oxides and flow rate (0.25 and 0.5mLmin(-1)) on the transport of CBNPs suspended in deionized water. The results showed that the mass recovery of CBNPs in quartz sand (flow rate=0.5mLmin(-1)) was 83.1%, whereas no breakthrough of CBNPs (mass recovery=0%) was observed in IOCS and AOCS at the same flow rate, indicating that metal (Fe, Al) oxides can play a significant role in the attachment of CBNPs to porous media. In addition, the mass recovery of CBNPs in quartz sand decreased to 76.1% as the flow rate decreased to 0.25mLmin(-1). Interaction energy profiles for CBNP-porous media were calculated using DLVO theory for sphere-plate geometry, demonstrating that the interaction energy for CBNP-quartz sand was repulsive, whereas the interaction energies for CBNP-IOCS and CBNP-AOCS were attractive with no energy barriers. The second set of experiments was conducted in quartz sand to observe the effect of ionic strength (NaCl=0.1 and 1.0mM; CaCl2=0.01 and 0.1mM) and pH (pH=4.5 and 5.4) on the transport of CBNPs suspended in electrolyte. The results showed that the mass recoveries of CBNPs in NaCl=0.1 and 1.0mM were 65.3 and 6.4%, respectively. The mass recoveries of CBNPs in CaCl2=0.01 and 0.1mM were 81.6 and 6.3%, respectively. These results demonstrated that CBNP attachment to quartz sand can be enhanced by increasing the electrolyte concentration. Interaction energy profiles demonstrated that the interaction energy profile for CBNP-quartz sand was compressed and that the energy barrier decreased as the electrolyte concentration increased. Furthermore, the mass recovery of CBNPs in the presence of divalent ions (CaCl2=0.1mM) was far lower than that in the presence of monovalent ions (NaCl=0.1mM), demonstrating a much stronger effect of Ca(2+) than Na(+) on CBNP transport. Mass recovery of CBNPs at pH4.5 was 55.6%, which was lower than that (83.1%) at pH5.4, indicating that CBNP attachment to quartz sand can be enhanced by decreasing the pH. The sticking efficiencies (?) calculated from the mass recovery by colloid filtration theory were in the range from 2.1×10(-2) to 4.5×10(-1), which were far greater than the values (2.56×10(-6)-3.33×10(-2)) of theoretical sticking efficiencies (?theory) calculated from the DLVO energy by the Maxwell model. PMID:25977994

  4. Palladium-catalyzed regioselective decarboxylative alkylation of arenes and heteroarenes with aliphatic carboxylic acids.

    PubMed

    Premi, Chanchal; Dixit, Ankit; Jain, Nidhi

    2015-06-01

    An unprecedented Pd(OAc)2-catalyzed decarboxylative alkylation of unactivated arenes, with aliphatic carboxylic acids as inexpensive alkyl sources, is reported. The alkylation, controlled by the directing group, is regioselective, shows high functional group tolerance, and provides mild access to alkylated indolines, 2-phenylpyridines, and azobenzenes under solvent-free conditions in moderate to high yields. PMID:25997514

  5. Understanding pyrroline-5-carboxylate synthetase deficiency: clinical, molecular, functional, and expression studies, structure-based analysis, and novel therapy with arginine.

    PubMed

    Martinelli, Diego; Häberle, Johannes; Rubio, Vicente; Giunta, Cecilia; Hausser, Ingrid; Carrozzo, Rosalba; Gougeard, Nadine; Marco-Marín, Clara; Goffredo, Bianca M; Meschini, Maria Chiara; Bevivino, Elsa; Boenzi, Sara; Colafati, Giovanna Stefania; Brancati, Francesco; Baumgartner, Matthias R; Dionisi-Vici, Carlo

    2012-09-01

    ?(1)-Pyrroline-5-carboxylate synthetase (P5CS) catalyzes the first two steps of ornithine/proline biosynthesis. P5CS deficiency has been reported in three families, with patients presenting with cutis/joint laxity, cataracts, and neurodevelopmental delay. Only one family exhibited metabolic changes consistent with P5CS deficiency (low proline/ornithine/citrulline/arginine; fasting hyperammonemia). Here we report a new P5CS-deficient patient presenting the complete clinical/metabolic phenotype and carrying p.G93R and p.T299I substitutions in the ?-glutamyl kinase (?GK) component of P5CS. The effects of these substitutions are (1) tested in mutagenesis/functional studies with E.coli ?GK, (2) rationalized by structural modelling, and (3) reflected in decreased P5CS protein in patient fibroblasts (shown by immunofluorescence). Using optical/electron microscopy on skin biopsy, we show collagen/elastin fiber alterations that may contribute to connective tissue laxity and are compatible with our angio-MRI finding of kinky brain vessels in the patient. MR spectroscopy revealed decreased brain creatine, which normalized after sustained arginine supplementation, with improvement of neurodevelopmental and metabolic parameters, suggesting a pathogenic role of brain creatine decrease and the value of arginine therapy. Morphological and functional studies of fibroblast mitochondria show that P5CS deficiency is not associated with the mitochondrial alterations observed in ?(1)-pyrroline-5-carboxylate reductase deficiency (another proline biosynthesis defect presenting cutis laxa and neurological alterations). PMID:22170564

  6. Structural and biochemical study on the inhibitory activity of derivatives of 5-nitro-furan-2-carboxylic acid for RNase H function of HIV-1 reverse transcriptase.

    PubMed

    Yanagita, Hiroshi; Urano, Emiko; Matsumoto, Kishow; Ichikawa, Reiko; Takaesu, Yoshihisa; Ogata, Masakazu; Murakami, Tsutomu; Wu, Hongui; Chiba, Joe; Komano, Jun; Hoshino, Tyuji

    2011-01-15

    Rapid emergence of drug-resistant variants is one of the most serious problems in chemotherapy for HIV-1 infectious diseases. Inhibitors acting on a target not addressed by approved drugs are of great importance to suppress drug-resistant viruses. HIV-1 reverse transcriptase has two enzymatic functions, DNA polymerase and RNase H activities. The RNase H activity is an attractive target for a new class of antiviral drugs. On the basis of the hit chemicals found in our previous screening with 20,000 small molecular-weight compounds, we synthesized derivatives of 5-nitro-furan-2-carboxylic acid. Inhibition of RNase H enzymatic activity was measured in a biochemical assay with real-time monitoring of florescence emission from the digested RNA substrate. Several derivatives showed higher inhibitory activities that those of the hit chemicals. Modulation of the 5-nitro-furan-2-carboxylic moiety resulted in a drastic decrease in inhibitory potency. In contrast, many derivatives with modulation of other parts retained inhibitory activities to varying degrees. These findings suggest the binding mode of active derivatives, in which three oxygen atoms aligned in a straight form at the nitro-furan moiety are coordinated to two divalent metal ions located at RNase H reaction site. Hence, the nitro-furan-carboxylic moiety is one of the critical scaffolds for RNase H inhibition. Of note, the RNase H inhibitory potency of a derivative was improved by 18-fold compared with that of the original hit compound, and no significant cytotoxicity was observed for most of the derivatives showing inhibitory activity. Since there is still much room for modification of the compounds at the part opposite the nitro-furan moiety, further chemical conversion will lead to improvement of compound potency and specificity. PMID:21193314

  7. Synthesis and properties of radiopaque polymer hydrogels: polyion complexes of copolymers of acrylamide derivatives having triiodophenyl and carboxyl groups and p-styrene sulfonate and polyallylamine

    NASA Astrophysics Data System (ADS)

    Okamura, M.; Uehara, H.; Yamanobe, T.; Komoto, T.; Hosoi, S.; Kumazaki, T.

    2000-10-01

    In order to pursue a possibility of application of radiopaque polymer hydrogels to vascular embolization, studies were done on synthesis of iodine-containing copolyanions and properties of their hydrogels with polycation via formation of polyion complexes. Acrylamide derivatives having triiodophenyl and carboxyl groups were synthesized and copolymerized with sodium styrene sulfonate at various molar ratios of initiator to monomer and temperatures. Hydrogels were prepared by mixing aqueous solutions of the obtained radiopaque copolyanions and polyallylamine. Embolization was examined by injection of these hydrogels into vein of a removed porcine kidney as a preliminary test for transcatheter arterial embolization (TAE) for hepatocellular carcinoma. It was found that the hydrogels prepared from the copolycation obtained under particular conditions give high X-ray contrasts of the vein and remained there, though copolycations with low molecular weights had a tendency to drain through the capillaries to the peripheral tissues. It is therefore concluded that the hydrogels examined in the present study are promising for vascular embolization.

  8. Monodisperse carboxyl-functionalized poly(ethylene glycol)-coated magnetic poly(glycidyl methacrylate) microspheres: application to the immunocapture of ?-amyloid peptides.

    PubMed

    Horák, Daniel; Hlídková, Helena; Hiraoui, Mohamed; Taverna, Myriam; Proks, Vladimír; Mázl Chánová, Eliška; Smadja, Claire; Ku?erová, Zdenka

    2014-11-01

    Identification and evaluation of small changes in ?-amyloid peptide (A?) levels in cerebrospinal fluid is of crucial importance for early detection of Alzheimer's disease. Microfluidic detection methods enable effective preconcentration of A? using magnetic microparticles coated with A? antibodies. Poly(glycidyl methacrylate) microspheres are coated with ?-amino-?-methoxy-PEG5000 /?-amino-?-Boc-NH-PEG5000 Boc groups deprotected and NH2 succinylated to introduce carboxyl groups. Capillary electrophoresis with laser-induced fluorescence detection confirms the efficient capture of A? 1-40 peptides on the microspheres with immobilized monoclonal anti-A? 6E10. The capture specificity is confirmed by comparing A? 1-40 levels on the anti-IgG-immobilized particles used as a control. PMID:25142028

  9. Effects of chemical functional groups on elemental mercury adsorption on carbonaceous surfaces.

    PubMed

    Liu, Jing; Cheney, Marcos A; Wu, Fan; Li, Meng

    2011-02-15

    A systematic theoretical study using density functional theory is performed to provide molecular-level understanding of the effects of chemical functional groups on mercury adsorption on carbonaceous surfaces. The zigzag and armchair edges were used in modeling the carbonaceous surfaces to simulate different adsorption sites. The edge atoms on the upper side of the models are unsaturated to simulate active sites. All calculations (optimizations, energies, and frequencies) were made at B3PW91 density functional theory level, using RCEP60VDZ basis set for mercury and 6-31G(d) pople basis set for other atoms. The results indicate that the embedding of halogen atom can increase the activity of its neighboring site which in turn increases the adsorption capacity of the carbonaceous surface for Hg(0). The adsorption belongs to chemisorptions, which is in good agreement with the experimental results. For the effects of oxygen functional groups, lactone, carbonyl and semiquinone favor Hg(0) adsorption because they increase the neighboring site's activity for mercury adsorption. On the contrary, phenol and carboxyl functional groups show a physisorption of Hg(0), and reduce Hg capture. This result can explain the seemingly conflicting experimental results reported in the literature concerning the influence of oxygen functional groups on mercury adsorption on carbonaceous surface. PMID:21144653

  10. Copper-catalyzed formal C - H carboxylation of aromatic compounds with carbon dioxide through arylaluminum intermediates.

    PubMed

    Ueno, Atsushi; Takimoto, Masanori; O, Wylie W N; Nishiura, Masayoshi; Ikariya, Takao; Hou, Zhaomin

    2015-04-01

    The C - H bond carboxylation of various aromatic compounds with CO2 was achieved by the deprotonative alumination with a mixed alkyl amido lithium aluminate compound iBu3 Al(TMP)Li followed by the NHC-copper-catalyzed carboxylation of the resulting arylaluminum species, which afforded the corresponding carboxylation products in high yield and high selectivity. In addition to benzene derivatives, heteroarenes such as benzofuran, benzothiophene, and indole derivatives are also suitable substrates. Functional groups such as Cl, Br, I, vinyl, amide, and CN could survive the reaction conditions. Some key reaction intermediates such as the copper aryl and isobutyl complexes and their carboxylation products were isolated and structurally characterized by X-ray crystallographic analyses, thus offering important information on the reaction mechanism. PMID:25491488

  11. Functional group composition of organic aerosol from combustion emissions and secondary processes at two contrasted urban environments

    NASA Astrophysics Data System (ADS)

    El Haddad, Imad; Marchand, Nicolas; D'Anna, Barbara; Jaffrezo, Jean Luc; Wortham, Henri

    2013-08-01

    The quantification of major functional groups in atmospheric organic aerosol (OA) provides a constraint on the types of compounds emitted and formed in atmospheric conditions. This paper presents functional group composition of organic aerosol from two contrasted urban environments: Marseille during summer and Grenoble during winter. Functional groups were determined using a tandem mass spectrometry approach, enabling the quantification of carboxylic (RCOOH), carbonyl (RCOR?), and nitro (RNO2) functional groups. Using a multiple regression analysis, absolute concentrations of functional groups were combined with those of organic carbon derived from different sources in order to infer the functional group contents of different organic aerosol fractions. These fractions include fossil fuel combustion emissions, biomass burning emissions and secondary organic aerosol (SOA). Results clearly highlight the differences between functional group fingerprints of primary and secondary OA fractions. OA emitted from primary sources is found to be moderately functionalized, as about 20 carbons per 1000 bear one of the functional groups determined here, whereas SOA is much more functionalized, as in average 94 carbons per 1000 bear a functional group under study. Aging processes appear to increase both RCOOH and RCOR? functional group contents by nearly one order of magnitude. Conversely, RNO2 content is found to decrease with photochemical processes. Finally, our results also suggest that other functional groups significantly contribute to biomass smoke and SOA. In particular, for SOA, the overall oxygen content, assessed using aerosol mass spectrometer measurements by an O:C ratio of 0.63, is significantly higher than the apparent O:C* ratio of 0.17 estimated based on functional groups measured here. A thorough examination of our data suggests that this remaining unexplained oxygen content can be most probably assigned to alcohol (ROH), organic peroxides (ROOH), organonitrates (RONO2) and/or organosulfates (ROSO3H).

  12. The synthesis of 13alpha-androsta-5,16-diene derivatives with carboxylic acid, ester and carboxamido functionalities at position-17 via palladium-catalyzed carbonylation.

    PubMed

    Acs, Péter; Takács, Attila; Szilágyi, Antal; Wölfling, János; Schneider, Gyula; Kollár, László

    2009-01-01

    17-Alkoxycarbonyl- and 17-carboxamido-3beta-hydroxy-13alpha-androsta-5,16-diene derivatives were synthetized in high yields in the palladium-catalyzed carbonylation reactions of the corresponding 3beta-hydroxy-17-iodo-13alpha-androsta-5,16-diene. This substrate with a 17-iodo-16-ene functionality was obtained from the 17-keto derivative via its 17-hydrazone, which was treated with iodine in the presence of a base (1,1,3,3-tetramethylguanidine). 17-Carboxamides were obtained by chemoselective aminocarbonylation through the use of amines, including amino acid esters, as N-nucleophiles. The 17-methoxycarbonyl-16-ene derivative was synthetized by using methanol as O-nucleophile. The parent compound of this series, the 17-carboxylic acid derivative, was formed in the presence of water via hydroxycarbonylation. PMID:19152802

  13. Molecular cloning of cDNA encoding a drosophila ryanodine receptor and functional studies of the carboxyl-terminal calcium release channel.

    PubMed Central

    Xu, X; Bhat, M B; Nishi, M; Takeshima, H; Ma, J

    2000-01-01

    Ryanodine is a plant alkaloid that was originally used as an insecticide. To study the function and regulation of the ryanodine receptor (RyR) from insect cells, we have cloned the entire cDNA sequence of RyR from the fruit fly Drosophila melanogaster. The primary sequence of the Drosophila RyR contains 5134 amino acids, which shares approximately 45% identity with RyRs from mammalian cells, with a large cytoplasmic domain at the amino-terminal end and a small transmembrane domain at the carboxyl-terminal end. To characterize the Ca(2+) release channel activity of the cloned Drosophila RyR, we expressed both full-length and a deletion mutant of Drosophila RyR lacking amino acids 277-3650 (Drosophila RyR-C) in Chinese hamster ovary cells. For subcellular localization of the expressed Drosophila RyR and Drosophila RyR-C proteins, green fluorescent protein (GFP)-Drosophila RyR and GFP-Drosophila RyR-C fusion constructs were generated. Confocal microscopic imaging identified GFP-Drosophila RyR and GFP-Drosophila RyR-C on the endoplasmic reticulum membranes of transfected cells. Upon reconstitution into the lipid bilayer membrane, Drosophila RyR-C formed a large conductance cation-selective channel, which was sensitive to modulation by ryanodine. Opening of the Drosophila RyR-C channel required the presence of microM concentration of Ca(2+) in the cytosolic solution, but the channel was insensitive to inhibition by Ca(2+) at concentrations as high as 20 mM. Our data are consistent with our previous observation with the mammalian RyR that the conduction pore of the calcium release channel resides within the carboxyl-terminal end of the protein and further demonstrate that structural and functional features are essentially shared by mammalian and insect RyRs. PMID:10692315

  14. Peptide coupling between amino acids and the carboxylic acid of a functionalized chlorido-gold(I)-phosphane.

    PubMed

    Kriechbaum, Margit; List, Manuela; Himmelsbach, Markus; Redhammer, Günther J; Monkowius, Uwe

    2014-10-01

    We have developed a protocol for the direct coupling between methyl ester protected amino acids and the chlorido-gold(I)-phosphane (p-HOOC(C6H4)PPh2)AuCl. By applying the EDC·HCl/NHS strategy (EDC·HCl = N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide hydrochloride, NHS = N-hydroxysuccinimide), the methyl esters of l-phenylalanine, glycine, l-leucine, l-alanine, and l-methionine are coupled with the carboxylic acid of the gold complex in moderate to good yields (62-88%). All amino acid tagged gold complexes were characterized by (1)H and (13)C NMR spectroscopy and high-resolution mass spectrometry. As corroborated by measurement of the angle of optical rotation, no racemization occurred during the reaction. The molecular structure of the leucine derivative was determined by single-crystal X-ray diffraction. In the course of developing an efficient coupling protocol, the acyl chlorides (p-Cl(O)C(C6H4)PPh2)AuX (X = Cl, Br) were also prepared and characterized. PMID:25203269

  15. Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN

    E-print Network

    Jasperse, Craig P.

    Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN A. Solubility Tests: Water, Na the formula weight. #12;Carboxylic Acid Unknowns and Titration 91 Note: Do your titration once, and check

  16. Photochemical and antimicrobial properties of silver nanoparticle-encapsulated chitosan functionalized with photoactive groups.

    PubMed

    Mathew, Thomas V; Kuriakose, Sunny

    2013-10-01

    Chitosan was functionalized with 4-((E)-2-(3-hydroxynaphthalen-2-yl)diazen-1-yl)benzoic acid by the coupling of the hydroxyl functional groups of chitosan with carboxylic acid group of the dye by DCC coupling method. The silver nanoparticles were prepared by sol-gel method of nanoparticle synthesis. Silver nanoparticle-encapsulated functionalized chitosan was prepared by the phase transfer method. The products were characterized by FTIR, UV-Vis, fluorescence and NMR spectroscopic methods and by SEM and TEM analysis. The photochemical properties of silver nanoparticle-encapsulated chitosan functionalized with 4-((E)-2-(3-hydroxynaphthalen-2-yl)diazen-1-yl)benzoic acid was studied in detail. The light-fastening properties of the chromophoric system was enhanced when attached to chitosan, and it can be further improved by the encapsulation of silver nanoparticles. The antibacterial analysis of silver nanoparticle-encapsulated functionalized chitosan was carried out against Staphylococcus aureus and Escherichia coli and against fungal species such as Aspergillus flavus and Aspergillus terreus. This study showed that silver nanoparticles-encapsulated functionalized chitosan can be used for antibacterial and antifungal applications. PMID:23910360

  17. Weyl Group Symmetric Functions Representation Theory of Lie Algebras

    E-print Network

    Ram, Arun

    of symmetric functions in the spirit of Macdonald's book [Mac] for Weyl groups other than the symmetric group of the classical symmetric function theory. See [Mac] Chapter 1 for a complete treatment. Fix a positive integer n

  18. Functional group diversity increases with modularity in complex food webs.

    PubMed

    Montoya, D; Yallop, M L; Memmott, J

    2015-01-01

    Biodiversity increases the ability of ecosystems to provide multiple functions. Most studies report a positive relationship between species richness and the number of ecosystem functions. However, it is not known whether the number of functional groups is related to the structure of the underlying species interaction network. Here we present food web data from 115 salt marsh islands and show that network structure is associated with the number of functional groups present. Functional group diversity is heterogeneously distributed across spatial scales, with some islands hosting more functional groups than others. Functional groups form modules within the community so that food webs with more modular architectures have more functional group diversity. Further, in communities with different interaction types, modularity can be seen as the multifunctional equivalent of trophic complementarity. Collectively, these findings reveal spatial heterogeneity in the number of functional groups that emerges from patterns in the structure of the food web. PMID:26059871

  19. Functional group diversity increases with modularity in complex food webs

    PubMed Central

    Montoya, D.; Yallop, M.L.; Memmott, J.

    2015-01-01

    Biodiversity increases the ability of ecosystems to provide multiple functions. Most studies report a positive relationship between species richness and the number of ecosystem functions. However, it is not known whether the number of functional groups is related to the structure of the underlying species interaction network. Here we present food web data from 115 salt marsh islands and show that network structure is associated with the number of functional groups present. Functional group diversity is heterogeneously distributed across spatial scales, with some islands hosting more functional groups than others. Functional groups form modules within the community so that food webs with more modular architectures have more functional group diversity. Further, in communities with different interaction types, modularity can be seen as the multifunctional equivalent of trophic complementarity. Collectively, these findings reveal spatial heterogeneity in the number of functional groups that emerges from patterns in the structure of the food web. PMID:26059871

  20. The carboxyl-terminal region of Crtac1B/LOTUS acts as a functional domain in endogenous antagonism to Nogo receptor-1.

    PubMed

    Kurihara, Yuji; Arie, Yuko; Iketani, Masumi; Ito, Hiromu; Nishiyama, Kuniyuki; Sato, Yasufumi; Nakamura, Fumio; Mizuki, Nobuhisa; Goshima, Yoshio; Takei, Kohtaro

    2012-02-10

    Myelin-derived axon growth inhibitors, such as Nogo, bind to Nogo receptor-1 (NgR1) and thereby limit the action of axonal regeneration after injury in the adult central nervous system. Recently, we have found that cartilage acidic protein-1B (Crtac1B)/lateral olfactory tract usher substance (LOTUS) binds to NgR1 and functions as an endogenous NgR1 antagonist. To examine the functional domain of LOTUS in the antagonism to NgR1, analysis using the deletion mutants of LOTUS was performed and revealed that the carboxyl-terminal region (UA/EC domain) of LOTUS bound to NgR1. The UA/EC fragment of LOTUS overexpressed together with NgR1 in COS7 cells abolished the binding of Nogo66 to NgR1. Overexpression of the UA/EC fragment in cultured chick dorsal root ganglion neurons suppressed Nogo66-induced growth cone collapse. These findings suggest that the UA/EC region is a functional domain of LOTUS serving for an antagonistic action to NgR1. PMID:22281491

  1. Complexation of cadmium to sulfur and oxygen functional groups in an organic soil

    NASA Astrophysics Data System (ADS)

    Karlsson, Torbjörn; Elgh-Dalgren, Kristin; Björn, Erik; Skyllberg, Ulf

    2007-02-01

    Cadmium (Cd) is a toxic trace element and due to human activities soils and waters are contaminated by Cd both on a local and global scale. It is widely accepted that chemical interactions with functional groups of natural organic matter (NOM) is vital for the bioavailability and mobility of trace elements. In this study the binding strength of cadmium (Cd) to soil organic matter (SOM) was determined in an organic (49% organic C) soil as a function of reaction time, pH and Cd concentration. In experiments conducted at native Cd concentrations in soil (0.23 ?g g -1 dry soil), halides (Cl, Br) were used as competing ligands to functional groups in SOM. The concentration of Cd in the aqueous phase was determined by isotope-dilution (ID) inductively-coupled-plasma-mass-spectrometry (ICP-MS), and the activity of Cd 2+ was calculated from the well-established Cd-halide constants. At higher Cd loading (500-54,000 ?g g -1), the Cd 2+ activity was directly determined by an ion-selective electrode (ISE). On the basis of results from extended X-ray absorption fine structure (EXAFS) spectroscopy, a model with one thiolate group (RS -) was used to describe the complexation (Cd 2+ + RS - ? CdSR +; log KCdSR) at native Cd concentrations. The concentration of thiols (RSH; 0.047 mol kg -1 C) was independently determined by X-ray absorption near-edge structure (XANES) spectroscopy. Log KCdSR values of 11.2-11.6 (p Ka for RSH = 9.96), determined in the pH range 3.1-4.6, compare favorably with stability constants for the association between Cd and well-defined thiolates like glutathione. In the concentration range 500-54,000 ?g Cd g -1, a model consisting of one thiolate and one carboxylate (RCOO -) gave the best fit to data, indicating an increasing role for RCOOH groups as RSH groups become saturated. The determined log KCdOOCR of 3.2 (Cd 2+ + RCOO - ? CdOOCR +; log KCdOOCR; p Ka for RCOOH = 4.5) is in accordance with stability constants determined for the association between Cd and well-defined carboxylates. Given a concentration of reduced sulfur groups of 0.2% or higher in NOM, we conclude that the complexation to organic RSH groups may control the speciation of Cd in soils, and most likely also in surface waters, with a total concentration less than 5 mg Cd g -1 organic C.

  2. Preconversion catalytic deoxygenation of phenolic functional groups. Quarterly report, January 1--March 30, 1996

    SciTech Connect

    Kubiak, C.P.

    1996-12-31

    Over the course of the studies on catalytic deoxygenation of phenolic residues in coal by carbon monoxide, the author performed preliminary investigations into the removal of other heteroatom groups. This report describes the attempted carbonylation of phenyl amido complexes. These studies resulted in the surprisingly facile formation of amidines. The amidine group is the nitrogen analog of carboxylic acids and esters. This functional group combines the properties of an azomethane-like C=N double bond with an amide-like C-N single bond. This group, like the related allyl (C-C-C), aza-allyl (C-N-C), and carboxylato (O-C-O) groups, form a number of transition metal derivatives, with both early and late transition metals. Various bonding modes of the amidino group have been reported. However, most isolated complexes have the amidino ligand as a chelating ligand or bridging two metals. This is due to the preference of amidines to bond via the nitrogen lone pairs, in contrast to the {eta}3 bonding observed in metal-allyl complexes. The experimental section of the paper describes the synthesis of platinum complexes, X-ray diffraction data for one Pt complex, and its reaction with carbon monoxide. Results are presented on the crystal and molecular structure of a platinum complex.

  3. Synthesis of hollow polymer microspheres with movable polyelectrolyte core and functional groups on the shell-layer

    Microsoft Academic Search

    Min Ji; Bin Liu; Xinlin Yang; Junyou Wang

    2009-01-01

    Hollow polymer microspheres with movable quaternary pyridinium polyelectrolyte (PE) cores and various functional groups on the shell-layers, such as hydroxyl, amide, and carboxyl, were prepared by the selectively etching of mid-silica layer with hydrofluoric acid from the corresponding poly(ethyleneglycol dimethacrylate-co-methacrylic acid)@poly(ethyleneglycol dimethacrylate- co-4-vinylpyridinium benzylchloride)\\/silica\\/polymer (P(EGDMA-co-MAA) @P(EGDMA-co-VPyBzCl)\\/SiO2\\/polymer) tetra-layer microspheres. The tetra-layer hybrid microspheres were synthesized by a multi-stage reaction process, which included

  4. Isolation and characterization of a ?1-pyrroline-5-carboxylate synthetase (NtP5CS) from Nitraria tangutorum Bobr. and functional comparison with its Arabidopsis homologue.

    PubMed

    Zheng, Linlin; Dang, Zhenhua; Li, Haoyu; Zhang, Huirong; Wu, Shubiao; Wang, Yingchun

    2014-01-01

    Several functional and regulatory proteins play important roles in controlling plant stress tolerance. Proline (Pro) is one of the most accumulated osmolytes correlated with tolerance to stresses. ?(1)-Pyrroline-5-carboxylate synthetase (P5CS) is a rate-limiting enzyme in Pro biosynthesis. In the present study, we isolated the cDNA for a P5CS gene (NtP5CS) from the halophyte Nitraria tangutorum. Phylogenetic analysis and subcellular localization analysis of NtP5CS-GFP protein in onion cells showed that NtP5CS was a new P5CS gene and was involved in Pro synthesis in N. tangutorum. Expression of the NtP5CS gene was induced by salt stress, dehydration, and high and low temperatures. Escherichia coli overexpressing AtP5CS or NtP5CS exhibited better growth in all treatments, including high salinity, high alkalinity, dehydration, osmotic, heat and cold stresses. Additionally, NtP5CS recombinant E. coli cells grew better than did AtP5CS recombinant cells in response to abiotic stresses. Our data demonstrate that the P5CS from a halophytic species functions more efficiently than its homologue from a glycophytic species in improving the stress tolerance of E. coli. PMID:24338163

  5. Rapid determination of memantine in human plasma by using nanoring carboxyl-functionalized paramagnetic molecularly imprinted polymer d-?-SPE and UFLC-MS/MS.

    PubMed

    Qiu, Hai-Wen; Xia, Lei; Gong, Li-Min; Ruan, Lie-Min; Zhao, Yong-Gang

    2015-06-01

    A novel, simple, and sensitive method based on the use of dispersive micro-solid-phase extraction (d-?-SPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) for the determination of memantine (ME) was developed and validated over the linearity range 0.05-10.0?µg/L with 100??L of human plasma using memantine-D6 (ME-D6) as the internal standard. The novel nanoring carboxyl-functionalized paramagnetic molecularly imprinted polymer (NR-CF-Mag-MIP) was synthesized by ultrasound-assisted suspension polymerization, using ME as a template molecule, methacrylic acid as a functional monomer, and divinylbenzene as a cross-linking agent. The NR-CF-Mag-MIP was used as the d-?-SPE sorbent to extract ME from human plasma samples. The obtained results demonstrated the higher extraction capacity of NR-CF-Mag-MIP with recoveries between 97.6 and 101%. The limits of quantification (LOQs) for ME was 0.015?µg/L. Validation results on linearity, specificity, accuracy, precision, and stability, as well as on application to the analysis of samples taken up to 480?h after oral administration of 20?mg (two 10?mg capsules) of ME in healthy volunteers demonstrated the applicability to bioequivalence studies. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25209851

  6. Immunocompatibility properties of lipid–polymer hybrid nanoparticles with heterogeneous surface functional groups

    Microsoft Academic Search

    Carolina Salvador-Morales; Liangfang Zhang; Robert Langer; Omid C. Farokhzad

    2009-01-01

    Here we report the immunological characterization of lipid–polymer hybrid nanoparticles (NPs) and propose a method to control the levels of complement activation induced by these NPs. This method consists of the highly specific modification of the NP surface with methoxyl, carboxyl, and amine groups. Hybrid NPs with methoxyl surface groups induced the lowest complement activation, whereas the NPs with amine

  7. MICROBIAL TRANSFORMATION OF ESTERS OF CHLORINATED CARBOXYLIC ACIDS

    EPA Science Inventory

    Two groups of compounds were selected for microbial transformation studies. In the first group were carboxylic acid esters having a fixed aromatic moiety and an increasing length of the alkyl component. Ethyl esters of chlorine-substituted carboxylic acids were in the second grou...

  8. Acid-base titrations of functional groups on the surface of the thermophilic bacterium Anoxybacillus flavithermus: comparing a chemical equilibrium model with ATR-IR spectroscopic data.

    PubMed

    Heinrich, Hannah T M; Bremer, Phil J; Daughney, Christopher J; McQuillan, A James

    2007-02-27

    Acid-base functional groups at the surface of Anoxybacillus flavithermus (AF) were assigned from the modeling of batch titration data of bacterial suspensions and compared with those determined from in situ infrared spectroscopic titration analysis. The computer program FITMOD was used to generate a two-site Donnan model (site 1: pKa = 3.26, wet concn = 2.46 x 10(-4) mol g(-1); site 2: pKa = 6.12, wet concn = 6.55 x 10(-5) mol g(-1)), which was able to describe data for whole exponential phase cells from both batch acid-base titrations at 0.01 M ionic strength and electrophoretic mobility measurements over a range of different pH values and ionic strengths. In agreement with information on the composition of bacterial cell walls and a considerable body of modeling literature, site 1 of the model was assigned to carboxyl groups, and site 2 was assigned to amino groups. pH difference IR spectra acquired by in situ attenuated total reflection infrared (ATR-IR) spectroscopy confirmed the presence of carboxyl groups. The spectra appear to show a carboxyl pKa in the 3.3-4.0 range. Further peaks were assigned to phosphodiester groups, which deprotonated at slightly lower pH. The presence of amino groups could not be confirmed or discounted by IR spectroscopy, but a positively charged group corresponding to site 2 was implicated by electrophoretic mobility data. Carboxyl group speciation over a pH range of 2.3-10.3 at two different ionic strengths was further compared to modeling predictions. While model predictions were strongly influenced by the ionic strength change, pH difference IR data showed no significant change. This meant that modeling predictions agreed reasonably well with the IR data for 0.5 M ionic strength but not for 0.01 M ionic strength. PMID:17243732

  9. Functional complementation of truncated human skeletal-muscle chloride channel (hClC-1) using carboxyl tail fragments

    PubMed Central

    Wu, Weiping; Rychkov, Grigori Y.; Hughes, Bernard P.; Bretag, Allan H.

    2005-01-01

    Crystal structures of bacterial CLC (voltage-gated chloride channel family) proteins suggest the arrangement of permeation pores and possible gates in the transmembrane region of eukaryotic CLC channels. For the extensive cytoplasmic tails of eukaryotic CLC family members, however, there are no equivalent structural predictions. Truncations of cytoplasmic tails in different places or point mutations result in loss of function or altered gating of several members of the CLC family, suggesting functional importance. In the present study, we show that deletion of the terminal 100 amino acids (N889X) in human ClC-1 (skeletal-muscle chloride channel) has minor consequences, whereas truncation by 110 or more amino acids (from Q879X) destroys channel function. Use of the split channel strategy, co-injecting mRNAs and expressing various complementary constructs in Xenopus oocytes, confirms the importance of the Gln879–Arg888 sequence. A split between the two CBS (cystathionine ?-synthase) domains (CBS1 and CBS2) gives normal function (e.g. G721X plus its complement), whereas a partial complementation, eliminating the CBS1 domain, eliminates function. Surprisingly, function is retained even when the region Gly721–Ala862 (between CBS1 and CBS2, and including most of the CBS2 domain) is omitted from the complementation. Furthermore, even shorter peptides from the CBS2-immediate post-CBS2 region are sufficient for functional complementation. We have found that just 26 amino acids from Leu863 to Arg888 are necessary since channel function is restored by co-expressing this peptide with the otherwise inactive truncation, G721X. PMID:16321142

  10. Hierarchical Grouping to Optimize an Objective Function

    Microsoft Academic Search

    Joe H. Ward Jr

    1963-01-01

    A procedure for forming hierarchical groups of mutually exclusive subsets, each of which has members that are maximally similar with respect to specified characteristics, is suggested for use in large-scale (n > 100) studies when a precise optimal solution for a specified number of groups is not practical. Given n sets, this procedure permits their reduction to n ? 1

  11. Functional renormalization group approach to the sine-Gordon model

    E-print Network

    S. Nagy; I. Nandori; J. Polonyi; K. Sailer

    2009-04-23

    The renormalization group flow is presented for the two-dimensional sine-Gordon model within the framework of the functional renormalization group method by including the wave-function renormalization constant. The Kosterlitz-Thouless-Berezinski type phase structure is recovered as the interpolating scaling law between two competing IR attractive area of the global renormalization group flow.

  12. The Inhibitory Effect of Kakkonto, Japanese Traditional (Kampo) Medicine, on Brain Penetration of Oseltamivir Carboxylate in Mice with Reduced Blood-Brain Barrier Function

    PubMed Central

    Ohara, Kousuke; Oshima, Shinji; Fukuda, Nanami; Ochiai, Yumiko; Maruyama, Ayumi; Kanamuro, Aki; Negishi, Akio; Honma, Seiichi; Ohshima, Shigeru; Akimoto, Masayuki; Takenaka, Shingo; Kobayashi, Daisuke

    2015-01-01

    Oseltamivir phosphate (OP) is used to treat influenza virus infections. However, its use may result in central nervous system (CNS) adverse effects. In Japan, OP is used with Kampo formulations to improve clinical effectiveness. We evaluated the potential for using Kampo formulations to reduce CNS adverse effects by quantifying the CNS distribution of oseltamivir and its active metabolite oseltamivir carboxylate (OC) when administered with maoto and kakkonto. We administered lipopolysaccharide (LPS) by intraperitoneal injection to C57BL/6 mice to reduce blood-brain barrier function. Saline, maoto, and kakkonto were administered orally at the same time as LPS. OP was orally administered 4 hours after the last LPS injection and the migration of oseltamivir and OC was examined. Additionally, we examined the brain distribution of OC following intravenous administration. Changes in OC concentrations in the brain suggest that, in comparison to LPS-treated control mice, both Kampo formulations increased plasma levels of OC, thereby enhancing its therapeutic effect. Additionally, our findings suggest kakkonto may not only improve the therapeutic effect of oseltamivir but also reduce the risk of CNS-based adverse effects. Considering these findings, it should be noted that administration of kakkonto during periods of inflammation has led to increased OAT3 expression. PMID:25788966

  13. The inhibitory effect of kakkonto, Japanese traditional (kampo) medicine, on brain penetration of oseltamivir carboxylate in mice with reduced blood-brain barrier function.

    PubMed

    Ohara, Kousuke; Oshima, Shinji; Fukuda, Nanami; Ochiai, Yumiko; Maruyama, Ayumi; Kanamuro, Aki; Negishi, Akio; Honma, Seiichi; Ohshima, Shigeru; Akimoto, Masayuki; Takenaka, Shingo; Kobayashi, Daisuke

    2015-01-01

    Oseltamivir phosphate (OP) is used to treat influenza virus infections. However, its use may result in central nervous system (CNS) adverse effects. In Japan, OP is used with Kampo formulations to improve clinical effectiveness. We evaluated the potential for using Kampo formulations to reduce CNS adverse effects by quantifying the CNS distribution of oseltamivir and its active metabolite oseltamivir carboxylate (OC) when administered with maoto and kakkonto. We administered lipopolysaccharide (LPS) by intraperitoneal injection to C57BL/6 mice to reduce blood-brain barrier function. Saline, maoto, and kakkonto were administered orally at the same time as LPS. OP was orally administered 4 hours after the last LPS injection and the migration of oseltamivir and OC was examined. Additionally, we examined the brain distribution of OC following intravenous administration. Changes in OC concentrations in the brain suggest that, in comparison to LPS-treated control mice, both Kampo formulations increased plasma levels of OC, thereby enhancing its therapeutic effect. Additionally, our findings suggest kakkonto may not only improve the therapeutic effect of oseltamivir but also reduce the risk of CNS-based adverse effects. Considering these findings, it should be noted that administration of kakkonto during periods of inflammation has led to increased OAT3 expression. PMID:25788966

  14. Simultaneous determination of endocrine disrupting compounds bisphenol F and bisphenol AF using carboxyl functionalized multi-walled carbon nanotubes modified electrode.

    PubMed

    Yang, Jichun; Wang, Xin; Zhang, Danfeng; Wang, Lingling; Li, Qi; Zhang, Lei

    2014-12-01

    A novel, simple and selective electrochemical method was developed for simultaneous determination of bisphenol F (BPF) and bisphenol AF (BPAF) in aqueous media (phosphate buffer solution, pH 6.0) on carboxyl functionalized multi-walled carbon nanotubes modified glassy carbon electrode (MWCNT-COOH/GCE) using differential pulse voltammetry (DPV). In DPV, MWCNT-COOH/GCE could separate the oxidation peak potentials of BPF and BPAF present in the same solution though, at the bare GCE, the peak potentials were indistinguishable. The results showed that the electrochemical sensor exhibited excellent electrocatalytic activity towards the oxidation of the two analytes. The peak current in DPV of BPF and BPAF increased linearly with their concentration in the ranges of 0.6-1.6 mmol/L BPF and 0.6-1.6 mmol/L BPAF. The detection limits were 0.1243 mmol/L and 0.1742 mmol/L (S/N=3) correspondingly. The modified electrode was successfully used to simultaneously determine BPF and BPAF in real samples. PMID:25159400

  15. Using the Renormalization Group to Classify Boolean Functions

    Microsoft Academic Search

    S. N. Coppersmith

    2008-01-01

    This paper argues that the renormalization group technique used to characterize phase transitions in condensed matter systems can be used to classify Boolean functions. A renormalization group transformation is presented that maps an arbitrary Boolean function of N Boolean variables to one of N-1 variables. Applying this transformation to a generic Boolean function (one whose output for each input is

  16. Breaking the Carboxyl Rule

    PubMed Central

    Balashov, Sergei P.; Petrovskaya, Lada E.; Imasheva, Eleonora S.; Lukashev, Evgeniy P.; Dioumaev, Andrei K.; Wang, Jennifer M.; Sychev, Sergey V.; Dolgikh, Dmitriy A.; Rubin, Andrei B.; Kirpichnikov, Mikhail P.; Lanyi, Janos K.

    2013-01-01

    A lysine instead of the usual carboxyl group is in place of the internal proton donor to the retinal Schiff base in the light-driven proton pump of Exiguobacterium sibiricum (ESR). The involvement of this lysine in proton transfer is indicated by the finding that its substitution with alanine or other residues slows reprotonation of the Schiff base (decay of the M intermediate) by more than 2 orders of magnitude. In these mutants, the rate constant of the M decay linearly decreases with a decrease in proton concentration, as expected if reprotonation is limited by the uptake of a proton from the bulk. In wild type ESR, M decay is biphasic, and the rate constants are nearly pH-independent between pH 6 and 9. Proton uptake occurs after M formation but before M decay, which is especially evident in D2O and at high pH. Proton uptake is biphasic; the amplitude of the fast phase decreases with a pKa of 8.5 ± 0.3, which reflects the pKa of the donor during proton uptake. Similarly, the fraction of the faster component of M decay decreases and the slower one increases, with a pKa of 8.1 ± 0.2. The data therefore suggest that the reprotonation of the Schiff base in ESR is preceded by transient protonation of an initially unprotonated donor, which is probably the ?-amino group of Lys-96 or a water molecule in its vicinity, and it facilitates proton delivery from the bulk to the reaction center of the protein. PMID:23696649

  17. Identification and characterization of carboxyl esterases of gill chamber-associated microbiota in the deep-sea shrimp Rimicaris exoculata by using functional metagenomics.

    PubMed

    Alcaide, María; Tchigvintsev, Anatoli; Martínez-Martínez, Mónica; Popovic, Ana; Reva, Oleg N; Lafraya, Álvaro; Bargiela, Rafael; Nechitaylo, Taras Y; Matesanz, Ruth; Cambon-Bonavita, Marie-Anne; Jebbar, Mohamed; Yakimov, Michail M; Savchenko, Alexei; Golyshina, Olga V; Yakunin, Alexander F; Golyshin, Peter N; Ferrer, Manuel

    2015-03-01

    The shrimp Rimicaris exoculata dominates the fauna in deep-sea hydrothermal vent sites along the Mid-Atlantic Ridge (depth, 2,320 m). Here, we identified and biochemically characterized three carboxyl esterases from microbial communities inhabiting the R. exoculata gill that were isolated by naive screens of a gill chamber metagenomic library. These proteins exhibit low to moderate identity to known esterase sequences (?52%) and to each other (11.9 to 63.7%) and appear to have originated from unknown species or from genera of Proteobacteria related to Thiothrix/Leucothrix (MGS-RG1/RG2) and to the Rhodobacteraceae group (MGS-RG3). A library of 131 esters and 31 additional esterase/lipase preparations was used to evaluate the activity profiles of these enzymes. All 3 of these enzymes had greater esterase than lipase activity and exhibited specific activities with ester substrates (?356 U mg(-1)) in the range of similar enzymes. MGS-RG3 was inhibited by salts and pressure and had a low optimal temperature (30°C), and its substrate profile clustered within a group of low-activity and substrate-restricted marine enzymes. In contrast, MGS-RG1 and MGS-RG2 were most active at 45 to 50°C and were salt activated and barotolerant. They also exhibited wider substrate profiles that were close to those of highly active promiscuous enzymes from a marine hydrothermal vent (MGS-RG2) and from a cold brackish lake (MGS-RG1). The data presented are discussed in the context of promoting the examination of enzyme activities of taxa found in habitats that have been neglected for enzyme prospecting; the enzymes found in these taxa may reflect distinct habitat-specific adaptations and may constitute new sources of rare reaction specificities. PMID:25595762

  18. Chemoselective Boron-Catalyzed Nucleophilic Activation of Carboxylic Acids for Mannich-Type Reactions.

    PubMed

    Morita, Yuya; Yamamoto, Tomohiro; Nagai, Hideoki; Shimizu, Yohei; Kanai, Motomu

    2015-06-10

    The carboxyl group (COOH) is an omnipresent functional group in organic molecules, and its direct catalytic activation represents an attractive synthetic method. Herein, we describe the first example of a direct catalytic nucleophilic activation of carboxylic acids with BH3·SMe2, after which the acids are able to act as carbon nucleophiles, i.e. enolates, in Mannich-type reactions. This reaction proceeds with a mild organic base (DBU) and exhibits high levels of functional group tolerance. The boron catalyst is highly chemoselective toward the COOH group, even in the presence of other carbonyl moieties, such as amides, esters, or ketones. Furthermore, this catalytic method can be extended to highly enantioselective Mannich-type reactions by using a (R)-3,3'-I2-BINOL-substituted boron catalyst. PMID:26011419

  19. Understanding biocatalyst inhibition by carboxylic acids

    PubMed Central

    Jarboe, Laura R.; Royce, Liam A.; Liu, Ping

    2013-01-01

    Carboxylic acids are an attractive biorenewable chemical in terms of their flexibility and usage as precursors for a variety of industrial chemicals. It has been demonstrated that such carboxylic acids can be fermentatively produced using engineered microbes, such as Escherichia coli and Saccharomyces cerevisiae. However, like many other attractive biorenewable fuels and chemicals, carboxylic acids become inhibitory to these microbes at concentrations below the desired yield and titer. In fact, their potency as microbial inhibitors is highlighted by the fact that many of these carboxylic acids are routinely used as food preservatives. This review highlights the current knowledge regarding the impact that saturated, straight-chain carboxylic acids, such as hexanoic, octanoic, decanoic, and lauric acids can have on E. coli and S. cerevisiae, with the goal of identifying metabolic engineering strategies to increase robustness. Key effects of these carboxylic acids include damage to the cell membrane and a decrease of the microbial internal pH. Certain changes in cell membrane properties, such as composition, fluidity, integrity, and hydrophobicity, and intracellular pH are often associated with increased tolerance. The availability of appropriate exporters, such as Pdr12, can also increase tolerance. The effect on metabolic processes, such as maintaining appropriate respiratory function, regulation of Lrp activity and inhibition of production of key metabolites such as methionine, are also considered. Understanding the mechanisms of biocatalyst inhibition by these desirable products can aid in the engineering of robust strains with improved industrial performance. PMID:24027566

  20. Microwave-assisted liquid-phase synthesis of methyl 6-amino-5-cyano-4-aryl-2-methyl-4 H-pyran-3-carboxylate using functional ionic liquid as soluble support

    Microsoft Academic Search

    Fengping Yi; Yanqing Peng; Gonghua Song

    2005-01-01

    A microwave-assisted liquid-phase synthesis of methyl 6-amino-5-cyano-4-aryl-2-methyl-4H-pyran-3-carboxylate was developed using functional ionic liquid as soluble support. IL-bound acetoacetate was treated with arylidenemalononitriles to give supported 4H-pyran derivatives. After cleavage, the target compounds were obtained in good yields and high purities without chromatographic purification.

  1. Water-enhanced solubility of carboxylic acids in organic solvents and its applications to extraction processes

    SciTech Connect

    Starr, J.N.; King, C.J.

    1991-11-01

    The solubilities of carboxylic acids in certain organic solvents increase remarkably with an increasing amount of water in the organic phase. This phenomenon leads to a novel extract regeneration process in which the co-extracted water is selectively removed from an extract, and the carboxylic acid precipitates. This approach is potentially advantageous compared to other regeneration processes because it removes a minor component of the extract in order to achieve a large recovery of acid from the extract. Carboxylic acids of interest include adipic acid, fumaric acid, and succinic acid because of their low to moderate solubilities in organic solvents. Solvents were screened for an increase in acid solubility with increased water concentration in the organic phase. Most Lewis-base solvents were found to exhibit this increased solubility phenomena. Solvents that have a carbonyl functional group showed a very large increase in acid solubility. 71 refs., 52 figs., 38 tabs.

  2. Bent functions on a finite nonabelian group Laurent Poinsot

    E-print Network

    Paris-Sud XI, Université de

    Bent functions on a finite nonabelian group Laurent Poinsot Universit´e du Sud Toulon-Var Institut´edex, France poinsot@univ-tln.fr Abstract. We introduce the notion of a bent function on a finite non- abelian to the corresponding properties of traditional abelian bent functions. Keywords. Bent functions, finite nonabelian

  3. Functionalized adamantane tectons used in the design of mixed-ligand copper(II) 1,2,4-triazolyl/carboxylate metal-organic frameworks.

    PubMed

    Senchyk, Ganna A; Lysenko, Andrey B; Krautscheid, Harald; Rusanov, Eduard B; Chernega, Alexander N; Krämer, Karl W; Liu, Shi-Xia; Decurtins, Silvio; Domasevitch, Konstantin V

    2013-01-18

    Bistriazoles, 1,3-bis(1,2,4-triazol-4-yl)propane (tr(2)pr) and 1,3-bis(1,2,4-triazol-4-yl)adamantane (tr(2)ad), were examined in combination with the rigid tetratopic 1,3,5,7-adamantanetetracarboxylic acid (H(4)-adtc) platform for the construction of neutral heteroleptic copper(II) metal-organic frameworks. Two coordination polymers, [{Cu(4)(OH)(2)(H(2)O)(2)}{Cu(4)(OH)(2)}(tr(2)pr)(2)(H-adtc)(4)]·2H(2)O (1) and [Cu(4)(OH)(2)(tr(2)ad)(2)(H-adtc)(2)(H(2)O)(2)]·3H(2)O (2), were synthesized and structurally characterized. In complexes 1 and 2, the N(1),N(2)-1,2,4-triazolyl (tr) and ?(3)-OH(-) groups serve as complementary bridges between adjacent metal centers supporting the tetranuclear dihydroxo clusters. The structure of 1 represents a unique association of two different kinds of centrosymmetrical {Cu(4)(OH)(2)} units in a tight 3D framework, while in compound 2, another configuration type of acentric tetranuclear metal clusters is organized in a layered 3,6-hexagonal motif. In both cases, the {Cu(4)(OH)(2)} secondary building block and trideprotonated carboxylate H-adtc(3-) can be viewed as covalently bound six- and three-connected nodes that define the net topology. The tr ligands, showing ?(3)- or ?(4)-binding patterns, introduce additional integrating links between the neighboring {Cu(4)(OH)(2)} fragments. A variable-temperature magnetic susceptibility study of 2 demonstrates strong antiferromagnetic intracluster coupling (J(1) = -109 cm(-1) and J(2) = -21 cm(-1)), which combines for the bulk phase with a weak antiferromagnetic intercluster interaction (zj = -2.5 cm(-1)). PMID:23294097

  4. Modeling the antisymmetric and symmetric stretching vibrational modes of aqueous carboxylate anions.

    PubMed

    Sutton, Catherine C R; Franks, George V; da Silva, Gabriel

    2015-01-01

    The infrared spectra of six aqueous carboxylate anions have been calculated at the M05-2X/cc-pVTZ level of theory with the SMD solvent model, and validated against experimental data from the literature over the region of 1700 cm(-1) to 1250 cm(-1); this region corresponds to the stretching modes of the carboxylate group, and is often interrogated when probing bonding of carboxylates to other species and surfaces. The anions studied here were formate, acetate, oxalate, succinate, glutarate and citrate. For the lowest energy conformer of each anion, the carboxylate moiety antisymmetric stretching peak was predicted with a mean signed error of only 4 cm(-1) using the SMD solvent model, while the symmetric peak was slightly overestimated. Performing calculations in vacuum and scaling was found to generally over-predict the antisymmetric vibrational frequencies and under predict the symmetric peak. Different conformers of the same anion were found to have only slightly different spectra in the studied region and the inclusion of explicit water molecules was not found to significantly change the calculated spectra when the implicit solvent model is used. Overall, the use of density functional theory in conjunction with an implicit solvent model was found to result in infra-red spectra that are the best reproduction of the features found experimentally for the aqueous carboxylate ions in the important 1700 cm(-1) to 1250 cm(-1) region. The development of validated model chemistries for simulating the stretching modes of aqueous carboxylate ions will be valuable for future studies that investigate how carboxylate anions complex with multivalent metal cations and related species in solution. PMID:25048288

  5. Modeling the antisymmetric and symmetric stretching vibrational modes of aqueous carboxylate anions

    NASA Astrophysics Data System (ADS)

    Sutton, Catherine C. R.; Franks, George V.; da Silva, Gabriel

    2015-01-01

    The infrared spectra of six aqueous carboxylate anions have been calculated at the M05-2X/cc-pVTZ level of theory with the SMD solvent model, and validated against experimental data from the literature over the region of 1700 cm-1 to 1250 cm-1; this region corresponds to the stretching modes of the carboxylate group, and is often interrogated when probing bonding of carboxylates to other species and surfaces. The anions studied here were formate, acetate, oxalate, succinate, glutarate and citrate. For the lowest energy conformer of each anion, the carboxylate moiety antisymmetric stretching peak was predicted with a mean signed error of only 4 cm-1 using the SMD solvent model, while the symmetric peak was slightly overestimated. Performing calculations in vacuum and scaling was found to generally over-predict the antisymmetric vibrational frequencies and under predict the symmetric peak. Different conformers of the same anion were found to have only slightly different spectra in the studied region and the inclusion of explicit water molecules was not found to significantly change the calculated spectra when the implicit solvent model is used. Overall, the use of density functional theory in conjunction with an implicit solvent model was found to result in infra-red spectra that are the best reproduction of the features found experimentally for the aqueous carboxylate ions in the important 1700 cm-1 to 1250 cm-1 region. The development of validated model chemistries for simulating the stretching modes of aqueous carboxylate ions will be valuable for future studies that investigate how carboxylate anions complex with multivalent metal cations and related species in solution.

  6. The Carboxyl Tail of Alpha-Actinin-4 Regulates Its Susceptibility to m-Calpain and thus Functions in Cell Migration and Spreading

    PubMed Central

    Shao, Hanshuang; Travers, Tim; Camacho, Carlos; Wells, Alan

    2013-01-01

    Alpha-actinin-4 links the cytoskeleton to sites of adhesion and has been shown to be modulated to enable cell migration. Such focal adhesions must be labile to accomplish migration, with this detachment occurring at least in part via m-calpain activation (Glading et al., 2002, Glading et al., 2001, Xie et al., 1998). In this study, we report that alpha-actinin-4 is initially cleaved by m-calpain between tyrosine 13 and glycine. Removal of the first 13 amino acids does not affect alpha-actinin-4 binding to actin filaments and its localization within fibroblasts but drives cell migration with less persistence. Binding of phosphoinositides PI(4,5)P2, PI(3,4,5)P3 and PI(3,4)P2 to alpha-actinin-4, as well as binding of alpha-actinin-4 to actin filaments all inhibit m-calpain cleavage of ACTN4 between tyrosine 13 and glycine 14. Interestingly, the carboxyl terminus of alpha-actinin-4 including its calcium binding motifs, is inhibitory for a secondary cleavage of alpha-actinin-4 between lysine 283 and valine 284.The minimal length of inhibitory domain is mapped to the last 11 amino acids of alpha-actinin-4. The C-terminal tail of alpha-actinin-4 is essential for maintaining its normal actin binding activity and localization within cytoplasm and also its colocalization with actin in the lamellipodia of locomoting fibroblasts. Live cell imaging reveals that the 1–890 fragment fails to rescue neither the basal or growth factor-stimulated migration nor the revert the spread area of fibroblasts to the level of NR6WT. These findings suggest that the C-terminal tail of alpha-actinin-4 is essential for its function in cell migration and adhesion to substratum. PMID:23466492

  7. COMBINATORICS AND SPHERICAL FUNCTIONS ON THE HEISENBERG GROUP

    E-print Network

    Benson, Chal

    COMBINATORICS AND SPHERICAL FUNCTIONS ON THE HEISENBERG GROUP CHAL BENSON AND GAIL RATCLIFF the action of K on a Heisenberg group H = V Ã? R. Contents 1. Introduction 1 2. Spherical functions. BENSON AND G. RATCLIFF of (finite-dimensional) K-irreducible subspaces. Here is a countably infinite in

  8. COMBINATORICS AND SPHERICAL FUNCTIONS ON THE HEISENBERG GROUP

    E-print Network

    Benson, Chal

    COMBINATORICS AND SPHERICAL FUNCTIONS ON THE HEISENBERG GROUP CHAL BENSON AND GAIL RATCLIFF \\Theta R. Contents 1. Introduction 1 2. Spherical functions on the Heisenberg group 5 3. Generalized. 1 #12; 2 C. BENSON AND G. RATCLIFF of (finite­dimensional) K­irreducible subspaces. Here \\Lambda

  9. Detection of Differential Item Functioning in Multiple Groups.

    ERIC Educational Resources Information Center

    Kim, Seock-Ho; And Others

    Detection of differential item functioning (DIF) is most often done between two groups of examinees under item response theory. It is sometimes important, however, to determine whether DIF is present in more than two groups. A method is presented for the detection of DIF in multiple groups. The method, the Q(sub j) statistic, is closely related to…

  10. Functional Analytic Psychotherapy for Interpersonal Process Groups: A Behavioral Application

    ERIC Educational Resources Information Center

    Hoekstra, Renee

    2008-01-01

    This paper is an adaptation of Kohlenberg and Tsai's work, Functional Analytical Psychotherapy (1991), or FAP, to group psychotherapy. This author applied a behavioral rationale for interpersonal process groups by illustrating key points with a hypothetical client. Suggestions are also provided for starting groups, identifying goals, educating…

  11. Silver-mediated decarboxylative C-S cross-coupling of aliphatic carboxylic acids under mild conditions.

    PubMed

    Wang, Peng-Fei; Wang, Xiao-Qing; Dai, Jian-Jun; Feng, Yi-Si; Xu, Hua-Jian

    2014-09-01

    A silver-mediated decarboxylative C-S cross-coupling reaction of aliphatic carboxylic acid is described. This reaction occurs smoothly under mild conditions and shows good tolerance of functional groups. It provides an alternative approach for the synthesis of alkyl aryl sulfides. PMID:25153507

  12. Using the Renormalization Group to Classify Boolean Functions

    Microsoft Academic Search

    S. N. Coppersmith

    2008-01-01

    This paper argues that the renormalization group technique used to characterize phase transitions in condensed matter systems\\u000a can be used to classify Boolean functions. A renormalization group transformation is presented that maps an arbitrary Boolean\\u000a function of N Boolean variables to one of N?1 variables. Applying this transformation to a generic Boolean function (one whose output for each input is chosen

  13. A role for coenzyme M (2-mercaptoethanesulfonic acid) in a bacterial pathway of aliphatic epoxide carboxylation

    PubMed Central

    Allen, Jeffrey R.; Clark, Daniel D.; Krum, Jonathan G.; Ensign, Scott A.

    1999-01-01

    The bacterial metabolism of short-chain aliphatic alkenes occurs via oxidation to epoxyalkanes followed by carboxylation to ?-ketoacids. Epoxyalkane carboxylation requires four enzymes (components I–IV), NADPH, NAD+, and a previously unidentified nucleophilic thiol. In the present work, coenzyme M (2-mercaptoethanesulfonic acid), a compound previously found only in the methanogenic Archaea where it serves as a methyl group carrier and activator, has been identified as the thiol and central cofactor of aliphatic epoxide carboxylation in the Gram-negative bacterium Xanthobacter strain Py2. Component I catalyzed the addition of coenzyme M to epoxypropane to form a ?-hydroxythioether, 2-(2-hydroxypropylthio)ethanesulfonate. Components III and IV catalyzed the NAD+-dependent stereoselective dehydrogenation of R- and S-enantiomers of 2-(2-hydroxypropylthio)ethanesulfonate to form 2-(2-ketopropylthio)ethanesulfonate. Component II catalyzed the NADPH-dependent cleavage and carboxylation of the ?-ketothioether to form acetoacetate and coenzyme M. These findings evince a newfound versatility for coenzyme M as a carrier and activator of alkyl groups longer in chain-length than methane, a function for coenzyme M in a catabolic pathway of hydrocarbon oxidation, and the presence of coenzyme M in the bacterial domain of the phylogenetic tree. These results serve to unify bacterial and Archaeal metabolism further and showcase diverse biological functions for an elegantly simple organic molecule. PMID:10411892

  14. Carboxylic acid sorption regeneration process

    DOEpatents

    King, C.J.; Poole, L.J.

    1995-05-02

    Carboxylic acids are sorbed from aqueous feedstocks into an organic liquid phase or onto a solid adsorbent. The acids are freed from the sorbent phase by treating it with aqueous alkylamine thus forming an alkylammonium carboxylate which is dewatered and decomposed to the desired carboxylic acid and the alkylamine. 10 figs.

  15. Nitric Acid Dehydration Using Perfluoro Carboxylate and Mixed Sulfonate/Carboxylate Membranes

    SciTech Connect

    R.L. Ames

    2004-09-01

    Perfluoro ionomer membranes are tetrafluoro ethylene-based materials with microheterogeneous structures consisting of a hydrophobic polymer backbone and a hydrophilic side-chain cluster region. Due to the ionomer cluster morphology, these films exhibit unique transport properties. Recent investigations with perfluoro sulfonate and perfluoro sulfonate/carboxylate composite polymers have demonstrated their value in the dehydration of nitric acid and they show potential as an alternative to conventional, energy intensive unit operations in the concentration of acid feeds. As a result, investigations were conducted to determine the feasibility of using pure perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films for the dehydration of nitric acid because of the speculation of improved water selectivity of the carboxylate pendant chain. During the first phase of these investigations the effort was focused on generating a thin, solution cast perfluoro carboxylate ionomer film, to evaluate the general, chemical and physical characteristics of the polymer, and to assess the material's aqueous transport performance (flux and nitrate separation efficiencies) in pervaporation and high-pressure environments. Results demonstrated that generating robust solution-cast films was difficult yet a number of membranes survived high trans-membrane pressures up to 700 psig. General characterization of the solution cast product showed reduced ion exchange capacities when compared with thicker, ''as received'' perfluoro carboxylate and similar sulfonate films. Small angle x-ray scattering analysis results suggested that the solution cast carboxylate films contained a small fraction of sulfonate terminated side-chains. Aqueous transport experimentation showed that permeate fluxes for both pure water and nitric acid were approximately two orders of magnitude smaller for the carboxylate solution cast membranes when compared to their sulfonate counterparts of similar thickness (Nafion{trademark} 111). Additionally, nitric acid separation efficiencies ({alpha}) were approximately one order of magnitude higher for the carboxylate solution cast films when compared to Nafion{trademark} 111. The second phase of our work included the generation of thin carboxylate films made by the chemical synthesis perfluoro sulfonate and mixed sulfonate/carboxylate polymers from a perfluoro sulfonyl fluoride precursor, the characterization of the newly generated material, and a study of the transport characteristics of these membranes. Transport studies consisted of the dehydration of nitric acid feeds by pervaporation. In addition, the initial hypothesis was expanded to include demonstration that transmembrane flux and separation efficiencies are a function of the ratio between sulfonate and carboxylate terminated side chains of the perfluoro ionomer. Investigations demonstrated the ability to generate in- house films with varying sulfonate/carboxylate concentrations from commercially available perfluoro sulfonyl fluoride material, and showed that the converted films could be characterized using Fourier transform infrared (FTIR) and x-ray fluorescence (XRF) spectroscopy. Finally, the mixed films where subjected to nitric acid dehydration transport tests and a relationship was found to exist between sulfonate/carboxylate pendant chain ratio and both flux and water separation capability. In summary, experimental results confirmed that, when compared to Nafion 111{trademark}, the mixed film's bulk fluxes decrease by approximately three orders of magnitude and the water separation factor increases by as much as two orders of magnitude as the carboxylate side-chain content was increased from 0 (pure sulfonate film) to 53 mole%, supporting the hypothesis given for this effort. It was observed that the water selectivity improved for both the solution cast perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films when judged against similar perfluoro sulfonate materials. Of great benefit was that during the investigation a number of research tools w

  16. Discovering herbal functional groups of traditional Chinese medicine.

    PubMed

    He, Ping; Deng, Ke; Liu, Zhihai; Liu, Delin; Liu, Jun S; Geng, Zhi

    2012-03-30

    For the traditional Chinese medicine (TCM), a prescription for a patient often contains several herbs. Some herbs are often used together in prescriptions, and these herbs can be considered as a functional group. In this paper, we propose an approach for discovering herbal functional groups from a large set of prescriptions recorded in TCM books. These functional groups are allowed to overlap with each other. Our approach is validated with a simulation study and applied to a data set containing thousands of TCM prescriptions. PMID:21413055

  17. Extending the GC-SAFT-VR approach to associating functional groups: Alcohols, aldehydes, amines and carboxylic acids

    Microsoft Academic Search

    M. Carolina dos Ramos; Jessica D. Haley; Joel R. Westwood; Clare McCabe

    2011-01-01

    The statistical associating fluid theory is a widely used molecular-based equation of state that has been successfully applied to study a broad range of fluid systems. It provides a framework in which the effects of molecular shape and interactions on the thermodynamics and phase behavior of fluids can be separated and quantified. In the original approach, molecules were modeled as

  18. Intracellular localization of a group II chaperonin indicates a membrane-related function

    NASA Technical Reports Server (NTRS)

    Trent, Jonathan D.; Kagawa, Hiromi K.; Paavola, Chad D.; McMillan, R. Andrew; Howard, Jeanie; Jahnke, Linda; Lavin, Colleen; Embaye, Tsegereda; Henze, Christopher E.

    2003-01-01

    Chaperonins are protein complexes that are believed to function as part of a protein folding system in the cytoplasm of the cell. We observed, however, that the group II chaperonins known as rosettasomes in the hyperthermophilic archaeon Sulfolobus shibatae, are not cytoplasmic but membrane associated. This association was observed in cultures grown at 60 degrees C and 76 degrees C or heat-shocked at 85 degrees C by using immunofluorescence microscopy and in thick sections of rapidly frozen cells grown at 76 degrees C by using immunogold electron microscopy. We observed that increased abundance of rosettasomes after heat shock correlated with decreased membrane permeability at lethal temperature (92 degrees C). This change in permeability was not seen in cells heat-shocked in the presence of the amino acid analogue azetidine 2-carboxylic acid, indicating functional protein synthesis influences permeability. Azetidine experiments also indicated that observed heat-induced changes in lipid composition in S. shibatae could not account for changes in membrane permeability. Rosettasomes purified from cultures grown at 60 degrees C and 76 degrees C or heat-shocked at 85 degrees C bind to liposomes made from either the bipolar tetraether lipids of Sulfolobus or a variety of artificial lipid mixtures. The presence of rosettasomes did not significantly change the transition temperature of liposomes, as indicated by differential scanning calorimetry, or the proton permeability of liposomes, as indicated by pyranine fluorescence. We propose that these group II chaperonins function as a structural element in the natural membrane based on their intracellular location, the correlation between their functional abundance and membrane permeability, and their potential distribution on the membrane surface.

  19. Immunocompatibility properties of lipid-polymer hybrid nanoparticles with heterogeneous surface functional groups.

    PubMed

    Salvador-Morales, Carolina; Zhang, Liangfang; Langer, Robert; Farokhzad, Omid C

    2009-04-01

    Here we report the immunological characterization of lipid-polymer hybrid nanoparticles (NPs) and propose a method to control the levels of complement activation induced by these NPs. This method consists of the highly specific modification of the NP surface with methoxyl, carboxyl, and amine groups. Hybrid NPs with methoxyl surface groups induced the lowest complement activation, whereas the NPs with amine surface groups induced the highest activation. All possible combinations among carboxyl, amine, and methoxyl groups also activated the complement system to a certain extent. All types of NPs activated the complement system primarily via the alternative pathway rather than the lectin pathway. The classical pathway was activated to a very small extent by the NPs with carboxyl and amine surface groups. Human serum and plasma protein binding studies showed that these NPs had different protein binding patterns. Studies of both complement activation and coagulation activation suggested that NPs with methoxyl surface groups might be an ideal candidate for drug delivery applications, since they are not likely to cause any immunological adverse reaction in the human body. PMID:19167749

  20. Surface etching of methacrylic microparticles via basic hydrolysis and introduction of functional groups for click chemistry.

    PubMed

    Speyerer, Christian; Borchers, Kirsten; Hirth, Thomas; Tovar, Günter E M; Weber, Achim

    2013-05-01

    Controlled basic hydrolysis of poly(methyl methacrylate-co-ethylene glycol dimethacrylate) P(MMA-co-EGDMA) microparticles with a diameter d50=6 ?m led to high densities of carboxylic groups at the particles' surface of up to 1.288 ?eq g(-1) (equivalent to 1.277 ?mol m(-2)). The microparticles' core has not been altered by this surface activation procedure as seen by fluorescent staining. The kinetics of the hydrolysis reaction was investigated via electrophoretic light scattering and particle charge detection employing polycation titration under shear condition. The activated microparticle's surface was subsequently exploited in carbodiimide-mediated coupling reactions using a variety of molecular reactants, that is, 11-azido-3,6,9-trioxaundecan-1-amine, cysteamine, propargylamine, and fluoresceinamine, thus enabling the introduction of chemically reactive moieties such as azides, thiols, and alkynes. Fluorescent staining of the particles' surface successfully demonstrated the versatile applications of surface functionalized microparticles via copper-catalyzed huisgen cycloaddition. Carrying on this two-step procedure in a controlled manner provides an excellent way for relatively simple but highly effective surface functionalization. PMID:23481515

  1. Department and function: Group Leader, Laboratory of Molecular Immunology; Clinical

    E-print Network

    Manstein, Dietmar J.

    Department and function: Group Leader, Laboratory of Molecular Immunology; Clinical Immunology in Immunology, Hannover Medical School Positions: 1994-1996: Research Associate, Dept. of Clinical Immunology, Hannover Medical School 1994: Visiting Scientist, Dept. of Immunology, University of Utrecht

  2. Analysis of Functional Groups by Solubility and Infrared Analysis.

    ERIC Educational Resources Information Center

    Turek, William N.

    1984-01-01

    An experiment which introduces students to infrared spectroscopy and the solubility behavior of various organic compounds is described. The experiment also serves to integrate some of the basic chemical reactions of functional groups with their spectral properties. (JN)

  3. Vanishing Beta Function curves from the Functional Renormalisation Group

    E-print Network

    P. Mati

    2015-01-26

    In this paper we will discuss the derivation of the so called Vanishing Beta Function curves which can be used to explore the fixed point structure of the theory under consideration. This can be applied to the O($N$) symmetric theories essentially for arbitrary dimensions ($D$) and field component ($N$). We will show the restoration of the Mermin-Wagner theorem for theories defined in $D\\leq2$ and the presence of the Wilson Fisher fixed point in $24$. Interestingly, one needs to make an excursion to the complex plane to see the triviality of the four dimensional O($N$) theories. The large $N$ analysis shows a new fixed point candidate in $4G. P. Vacca in: "Are there scaling solutions in the O($N$)-models for large $N$ in $D > 4$?".

  4. SPACES OF BOUNDED SPHERICAL FUNCTIONS ON HEISENBERG GROUPS: PART I

    E-print Network

    Benson, Chal

    SPACES OF BOUNDED SPHERICAL FUNCTIONS ON HEISENBERG GROUPS: PART I CHAL BENSON AND GAIL RATCLIFF hermitian vector space V . Letting K act on the associ- ated Heisenberg group HV = V Ã? R yields a Gelfand. Primary 43A90; Secondary 20G05, 43A75. 1 #12;2 C. BENSON AND G. RATCLIFF finite dimensional complex vector

  5. The Eisentein group and the pseudo hyperbolic functions

    E-print Network

    G. Dattoli; M. Migliorati; P. E. Ricci

    2010-10-08

    We review the teory of the pseudo-iperbolic functions on the basis of an algebraic point of view which employs the Eisenstein group. We frame the teory within the general context of the number decomposition and discuss the importance of these functions in the theory of the generalized Fourier transforms

  6. Generalized functions asymptotically homogeneous along special transformation groups

    SciTech Connect

    Drozhzhinov, Yurii N; Zav'yalov, Boris I [Steklov Mathematical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2009-06-30

    Distributions having (quasi)asymptotics in the asymptotic scale of regularly varying functions along special groups of transformation of independent variables are said to be asymptotically homogeneous along these transformation groups. In particular, all 'quasihomogeneous' distributions have this property. A complete description of asymptotically homogeneous distributions along a transformation group determined by a vector a element of R{sub +}{sup n} is obtained, including in the case of critical orders. Special distribution spaces are introduced and investigated to this end. The results obtained are used for the analysis of singularities of holomorphic functions in the tube domains over coordinate sectors. Bibliography: 10 titles.

  7. The Luminosity Function of Galaxies in Elliptical- dominated Groups: Clues on the Nature of Fossil Groups

    NASA Astrophysics Data System (ADS)

    de Oliveira, R. L.; de Oliveira, C. M.; Dupke, R.; Sodré, L.; Cypriano, E.

    2010-10-01

    We have started a study of luminosity functions of Fossil Group candidates in order to characterize the faint-end of their galaxy distribution. Here we report on results of nine of them from SDSS observations.

  8. Noncovalent catch and release of carboxylates in water.

    PubMed

    Beck, Christie L; Winter, Arthur H

    2014-04-01

    Association constants of a bis-(acetylguanidinium)ferrocene dication to various (di)carboxylates were determined through UV-vis titrations. Association constant values greater than 10(4) M(-1) were determined for both phthalate and maleate carboxylates to the bis-(acetylguanidinium)ferrocene salt in pure water. Density functional theory computations of the binding enthalpy of the rigid carboxylates for these complexes agree well with the experimentally determined association constants. Catch and release competitive binding experiments were done by NMR for the cation-carboxylate ion-pair complexes with cucurbit[7]uril, and they show dissociation of the ion-pair complex upon addition of cucurbit[7]uril and release of the free (di)carboxylate. PMID:24605882

  9. Mixture of a molybdenum carboxylate and a molybdenum dithiophosphate or a molybdenum dithiocarbamate for use in a hydrovisbreaking process

    SciTech Connect

    Howell, J.A.; Kukes, S.G.

    1987-11-10

    A molybdenum is described containing mixture selected from the group consisting of a mixture comprising a molybdenum dithiophosphate and a molybdenum carboxylate and a mixture comprising a molybdenum dithiocarbamate and a molybdenum carboxylate.

  10. Single or functionalized fullerenes interacting with heme group

    SciTech Connect

    Costa, Wallison Chaves; Diniz, Eduardo Moraes, E-mail: eduardo.diniz@ufma.br [Departamento de Física, Universidade Federal do Maranhão, Avenida dos Portugueses, 1966, CEP 65080-805, São Luís - MA (Brazil)

    2014-09-15

    The heme group is responsible for iron transportation through the bloodstream, where iron participates in redox reactions, electron transfer, gases detection etc. The efficiency of such processes can be reduced if the whole heme molecule or even the iron is somehow altered from its original oxidation state, which can be caused by interactions with nanoparticles as fullerenes. To verify how such particles alter the geometry and electronic structure of heme molecule, here we report first principles calculations based on density functional theory of heme group interacting with single C{sub 60} fullerene or with C{sub 60} functionalized with small functional groups (?CH{sub 3}, ?COOH, ?NH{sub 2}, ?OH). The calculations shown that the system heme + nanoparticle has a different spin state in comparison with heme group if the fullerene is functionalized. Also a functional group can provide a stronger binding between nanoparticle and heme molecule or inhibit the chemical bonding in comparison with single fullerene results. In addition heme molecule loses electrons to the nanoparticles and some systems exhibited a geometry distortion in heme group, depending on the binding energy. Furthermore, one find that such nanoparticles induce a formation of spin up states in heme group. Moreover, there exist modifications in density of states near the Fermi energy. Although of such changes in heme electronic structure and geometry, the iron atom remains in the heme group with the same oxidation state, so that processes that involve the iron might not be affected, only those that depend on the whole heme molecule.

  11. Using the Renormalization Group to Classify Boolean Functions

    NASA Astrophysics Data System (ADS)

    Coppersmith, S. N.

    2008-03-01

    This paper argues that the renormalization group technique used to characterize phase transitions in condensed matter systems can be used to classify Boolean functions. A renormalization group transformation is presented that maps an arbitrary Boolean function of N Boolean variables to one of N-1 variables. Applying this transformation to a generic Boolean function (one whose output for each input is chosen randomly and independently to be one or zero with equal probability) yields another generic Boolean function. Moreover, applying the transformation to some other functions known to be non-generic, such as Boolean functions that can be written as polynomials of degree ? with ? ? N and functions that depend on composite variables such as the arithmetic sum of the inputs, yields non-generic results. One can thus define different phases of Boolean functions as classes of functions with different types of behavior upon repeated application of the renormalization transformation. Possible relationships between different phases of Boolean functions and computational complexity classes studied in computer science are discussed.

  12. Discretization of four types of Weyl group orbit functions

    NASA Astrophysics Data System (ADS)

    Hrivnák, Ji?í

    2013-11-01

    The discrete Fourier calculus of the four families of special functions, called C-, S-, Ss- and Sl -functions, is summarized. Functions from each of the four families of special functions are discretely orthogonal over a certain finite set of points. The generalizations of discrete cosine and sine transforms of one variable — the discrete Ss- and Sl-transforms of the group F4 — are considered in detail required for their exploitation in discrete Fourier spectral methods. The continuous interpolations, induced by the discrete expansions, are presented.

  13. 1-(5,5-Di­meth­oxy­pent­yl)-3-methyl­imidazolium-2-carboxyl­ate

    PubMed Central

    Walter, Olaf

    2013-01-01

    The title compound, C12H20N2O4, represents one example of a zwitterionic imidazolium salt with a carboxyl­ate group at the 2-position of the imidazolium ring. The dihedral angle between the heterocyclic ring and the carboxyl­ate group is 31.3?(1)°. The side chain linking the N atom of the ring and the methine C atom has a gauche–anti–anti conformation [torsion angles = ?60.3?(2), ?175.7?(2) and 178.7?(2)°, respectively]. In the crystal, mol­ecules are linked by short C—H?O hydrogen bonds involving the C—H groups in the aromatic ring to generate (001) sheets. PMID:24454062

  14. STUDY OF THE NEAR INFRARED-MEDIATED HEATING OF DISPERSIONS OF PROTEIN-COATED PRISTINE AND CARBOXYLATED SINGLE-WALLED CARBON NANOTUBES

    PubMed Central

    Sheardy, Alex T.; Taylor, Jeremy J.; Chilek, Jennifer L.; Li, Synyoung; Wang, Ruhung; Draper, Rockford K.; Pantano, Paul

    2013-01-01

    Previously, we demonstrated the selective NIR-mediated ablation of tumor cells in vitro using pristine single-walled carbon nanotubes (SWNTs) with adsorbed tumor-targeting ligands and carboxylated SWNTs with covalently-attached ligands. The covalent approach is advantageous in ensuring that protein ligands remain associated with the NIR-absorbing SWNTs in biological matrices and the noncovalent approach has the advantage of enabling SWNT functionalization without perturbation of the SWNT lattice and photothermal properties. Herein, we compare the ability of moderately-carboxylated (~4 at.% carboxylic acid groups) and pristine SWNT materials to absorb 808 nm radiation and convert it to heat. Under conditions of a constant 808 nm laser power density, the approach involved measuring the temperature of aqueous dispersions of protein-coated SWNTs as a function of the irradiation time. Nearly identical temperature profiles were observed for dispersions of moderately-carboxylated and pristine SWNTs possessing matched 808 nm optical densities and equivalent concentrations of carbonaceous species (i.e., SWNTs and amorphous carbon impurities). The results indicate that the amount of carbonaceous species in purified dispersions of protein-coated SWNTs is more important for converting absorbed 808 nm radiation into heat than whether or not the SWNTs were moderately carboxylated, and that moderately-carboxylated SWNTs could be the SWNT-material of choice for the targeted photothermal ablation of tumor cells. PMID:23645950

  15. A functional renormalization group equation for foliated spacetimes

    NASA Astrophysics Data System (ADS)

    Rechenberger, Stefan; Saueressig, Frank

    2013-03-01

    We derive an exact functional renormalization group equation for the projectable version of Ho?ava-Lifshitz gravity. The flow equation encodes the gravitational degrees of freedom in terms of the lapse function, shift vector and spatial metric and is manifestly invariant under background foliation-preserving diffeomorphisms. Its relation to similar flow equations for gravity in the metric formalism is discussed in detail, and we argue that the space of action functionals, invariant under the full diffeomorphism group, forms a subspace of the latter invariant under renormalization group transformations. As a first application we study the RG flow of the Newton constant and the cosmological constant in the ADM formalism. In particular we show that the non-Gaussian fixed point found in the metric formulation is qualitatively unaffected by the change of variables and persists also for Lorentzian signature metrics.

  16. Characterization of Oxygen Containing Functional Groups on Carbon Materials with Oxygen K-edge X-ray Absorption Near Edge Structure Spectroscopy

    SciTech Connect

    K Kim; P Zhu; L Na; X Ma; Y Chen

    2011-12-31

    Surface functional groups on carbon materials are critical to their surface properties and related applications. Many characterization techniques have been used to identify and quantify the surface functional groups, but none is completely satisfactory especially for quantification. In this work, we used oxygen K-edge X-ray absorption near edge structure (XANES) spectroscopy to identify and quantify the oxygen containing surface functional groups on carbon materials. XANES spectra were collected in fluorescence yield mode to minimize charging effect due to poor sample conductivity which can potentially distort XANES spectra. The surface functional groups are grouped into three types, namely carboxyl-type, carbonyl-type, and hydroxyl-type. XANES spectra of the same type are very similar while spectra of different types are significantly different. Two activated carbon samples were analyzed by XANES. The total oxygen contents of the samples were estimated from the edge step of their XANES spectra, and the identity and abundance of different functional groups were determined by fitting of the sample XANES spectrum to a linear combination of spectra of the reference compounds. It is concluded that oxygen K-edge XANES spectroscopy is a reliable characterization technique for the identification and quantification of surface functional groups on carbon materials.

  17. From infinite to two dimensions through the functional renormalization group.

    PubMed

    Taranto, C; Andergassen, S; Bauer, J; Held, K; Katanin, A; Metzner, W; Rohringer, G; Toschi, A

    2014-05-16

    We present a novel scheme for an unbiased, nonperturbative treatment of strongly correlated fermions. The proposed approach combines two of the most successful many-body methods, the dynamical mean field theory and the functional renormalization group. Physically, this allows for a systematic inclusion of nonlocal correlations via the functional renormalization group flow equations, after the local correlations are taken into account nonperturbatively by the dynamical mean field theory. To demonstrate the feasibility of the approach, we present numerical results for the two-dimensional Hubbard model at half filling. PMID:24877952

  18. First Principles Study of Chemically Functionalized Graphene

    NASA Astrophysics Data System (ADS)

    Jha, Sanjiv; Vasiliev, Igor

    2015-03-01

    The electronic, structural and vibrational properties of carbon nanomaterials can be affected by chemical functionalization. We applied ab initio computational methods based on density functional theory to study the covalent functionalization of graphene with benzyne, carboxyl groups and tetracyanoethylene oxide (TCNEO). Our calculations were carried out using the SIESTA and Quantum-ESPRESSO electronic structure codes combined with the local density and generalized gradient approximations for the exchange correlation functional and norm-conserving Troullier-Martins pseudopotentials. The simulated Raman and infrared spectra of graphene functionalized with carboxyl groups and TCNEO were consistent with the available experimental results. The computed vibrational spectra of graphene functionalized with carboxyl groups showed that the presence of point defects near the functionalization site affects the Raman and infrared spectroscopic signatures of functionalized graphene. Supported by NSF CHE-1112388.

  19. Heterogeneous Catalyst Design by Multiple Functional Group Positioning in Organic-Inorganic Materials: On the Route to Analogs of Multifunctional Enzymes

    NASA Astrophysics Data System (ADS)

    Margelefsky, Eric L.; Zeidan, Ryan K.; Davis, Mark E.

    Enzymes catalyze reactions with high rates and selectivities through the sophisticated use of cooperative interactions between neighboring functional groups within an active site. For example, the “catalytic triad” in proteases is capable of accelerating the cleavage of amides by 1011 through neighboring interactions between carboxylic acid, imidazole, and alcohol sites. Guided by these principles, heterogeneous catalysts having two different types of functional groups have been prepared, and the cooperative behavior have been demonstrated with catalytic reactions in the liquid phase. Cooperative interactions between thiols and sulfonic acids and between incompatible acid and base groups are achievable with rates and selectivities that are superior to homogeneous systems, especially for the latter case wherein there is no reactivity.

  20. Synthesis and structures of cadmium carboxylate and thiocarboxylate compounds with a sulfur-rich coordination environment: carboxylate exchange kinetics involving tris(2-mercapto-1-t-butylimidazolyl)hydroborato cadmium complexes, [Tm(Bu(t))]Cd(O2CR).

    PubMed

    Kreider-Mueller, Ava; Quinlivan, Patrick J; Owen, Jonathan S; Parkin, Gerard

    2015-04-20

    A series of cadmium carboxylate compounds in a sulfur-rich environment provided by the tris(2-tert-butylmercaptoimidazolyl)hydroborato ligand, namely, [Tm(Bu(t))]CdO2CR, has been synthesized via the reactions of the cadmium methyl derivative [Tm(Bu(t))]CdMe with RCO2H. Such compounds mimic aspects of cadmium-substituted zinc enzymes and also the surface atoms of cadmium chalcogenide crystals, and have therefore been employed to model relevant ligand exchange processes. Significantly, both (1)H and (19)F NMR spectroscopy demonstrate that the exchange of carboxylate groups between [Tm(Bu(t))]Cd(?(2)-O2CR) and the carboxylic acid RCO2H is facile on the NMR time scale, even at low temperature. Analysis of the rate of exchange as a function of concentration of RCO2H indicates that reaction occurs via an associative rather than dissociative pathway. In addition to carboxylate compounds, the thiocarboxylate derivative [Tm(Bu(t))]Cd[?(1)-SC(O)Ph] has also been synthesized via the reaction of [Tm(Bu(t))]CdMe with thiobenzoic acid. The molecular structure of [Tm(Bu(t))]Cd[?(1)-SC(O)Ph] has been determined by X-ray diffraction, and an interesting feature is that, in contrast to the carboxylate derivatives [Tm(Bu(t))]Cd(?(2)-O2CR), the thiocarboxylate ligand binds in a ?(1) manner via only the sulfur atom. PMID:25826184

  1. The intracellular carboxyl tail of the PAR-2 receptor controls intracellular signaling and cell death.

    PubMed

    Zhu, Zhihui; Stricker, Rolf; Li, Rong yu; Zündorf, Gregor; Reiser, Georg

    2015-03-01

    The protease-activated receptors are a group of unique G protein-coupled receptors, including PAR-1, PAR-2, PAR-3 and PAR-4. PAR-2 is activated by multiple trypsin-like serine proteases, including trypsin, tryptase and coagulation proteases. The clusters of phosphorylation sites in the PAR-2 carboxyl tail are suggested to be important for the binding of adaptor proteins to initiate intracellular signaling to Ca(2+) and mitogen-activated protein kinases. To explore the functional role of PAR-2 carboxyl tail in controlling intracellular Ca(2+), ERK and AKT signaling, a series of truncated mutants containing different clusters of serines/threonines were generated and expressed in HEK293 cells. Firstly, we observed that lack of the complete C-terminus of PAR-2 in a mutated receptor gave a relatively low level of localization on the cell plasma membrane. Secondly, the shortened carboxyl tail containing 13 amino acids was sufficient for receptor internalization. Thirdly, the cells expressing truncation mutants showed deficits in their capacity to couple to intracellular Ca(2+) and ERK and AKT signaling upon trypsin challenge. In addition, HEK293 cells carrying different PAR-2 truncation mutants displayed decreased levels of cell survival after long-lasting trypsin stimulation. In summary, the PAR-2 carboxyl tail was found to control the receptor localization, internalization, intracellular Ca(2+) responses and signaling to ERK and AKT. The latter can be considered to be important for cell death control. PMID:25519044

  2. Modeling the active sites of non-heme diiron metalloproteins with sterically hindered carboxylates and syn N-Donor ligands

    E-print Network

    Friedle, Simone, 1976-

    2009-01-01

    Chapter 1. Different Synthetic Approaches to Modeling the Active Sites of Carboxylate-Bridged Non-Heme Diiron Enzymes Carboxylate-bridged non-heme diiron enzymes activate dioxygen to perform a variety of biological functions. ...

  3. MOM renormalization group functions in the maximal abelian gauge

    E-print Network

    J. M. Bell; J. A. Gracey

    2013-10-01

    The one loop 3-point vertex functions of QCD in the maximal abelian gauge (MAG) are evaluated at the fully symmetric point at one loop. As a consequence the theory is renormalized in the various momentum (MOM) schemes which are defined by the trivalent vertices, as well as in the MSbar scheme. From these the two loop renormalization group functions in the MOM schemes are derived using the one loop conversion functions. In parallel we repeat the analysis for the Curci-Ferrari gauge which corresponds to the MAG in a specific limit. The relation between the Lambda parameters in different schemes is also provided.

  4. MOM renormalization group functions in the maximal abelian gauge

    E-print Network

    Bell, J M

    2013-01-01

    The one loop 3-point vertex functions of QCD in the maximal abelian gauge (MAG) are evaluated at the fully symmetric point at one loop. As a consequence the theory is renormalized in the various momentum (MOM) schemes which are defined by the trivalent vertices, as well as in the MSbar scheme. From these the two loop renormalization group functions in the MOM schemes are derived using the one loop conversion functions. In parallel we repeat the analysis for the Curci-Ferrari gauge which corresponds to the MAG in a specific limit. The relation between the Lambda parameters in different schemes is also provided.

  5. 2005 Nature Publishing Group WUSCHEL controls meristem function by direct

    E-print Network

    Weigel, Detlef

    © 2005 Nature Publishing Group WUSCHEL controls meristem function by direct regulation of cytokinin,2 . Phytohormones such as auxin and cytokinin are also important for meristem regulation3 . Here we show, ARR6, ARR7 and ARR15), which act in the negative- feedback loop of cytokinin signalling4

  6. Analysis of synthetic fuels for functional group determination

    Microsoft Academic Search

    Leonidas. Petrakis; David T. Allen; George R. Gavalas; Bruce C. Gates

    1983-01-01

    A method for the structural characterisation of complex mixtures has been developed which uses elemental analysis, NMR and other analytical data to determine functional group concentrations. The method was tested with mixtures of known composition and was applied to a set of hydrodesulphurised coal liquids. The results are compared with mass spectrometric data and with the results of established methods

  7. Pelagic functional group modeling: Progress, challenges and prospects

    Microsoft Academic Search

    Raleigh R. Hood; Edward A. Laws; Robert A. Armstrong; Nicholas R. Bates; Christopher W. Brown; Craig A. Carlson; Fei Chai; Scott C. Doney; Paul G. Falkowski; Richard A. Feely; Marjorie A. M. Friedrichs; Michael R. Landry; J. Keith Moore; David M. Nelson; Tammi L. Richardson; Baris Salihoglu; Markus Schartau; Dierdre A. Toole; Jerry D. Wiggert

    2006-01-01

    In this paper, we review the state of the art and major challenges in current efforts to incorporate biogeochemical functional groups into models that can be applied on basin-wide and global scales, with an emphasis on models that might ultimately be used to predict how biogeochemical cycles in the ocean will respond to global warming. We define the term “biogeochemical

  8. Langmuir monolayers from functionalized amphiphiles with epoxy terminal groups

    E-print Network

    Vakni, David

    Langmuir monolayers from functionalized amphiphiles with epoxy terminal groups Kirsten L. Gensona June 2005 Abstract We studied Langmuir and Langmuir­Blodgett monolayers from amphiphiles applications [1­4]. Among them, photo- responsive amphiphiles possess the possibility of forming ordered, two

  9. Pelagic functional group modeling: Progress, challenges and prospects

    NASA Astrophysics Data System (ADS)

    Hood, Raleigh R.; Laws, Edward A.; Armstrong, Robert A.; Bates, Nicholas R.; Brown, Christopher W.; Carlson, Craig A.; Chai, Fei; Doney, Scott C.; Falkowski, Paul G.; Feely, Richard A.; Friedrichs, Marjorie A. M.; Landry, Michael R.; Keith Moore, J.; Nelson, David M.; Richardson, Tammi L.; Salihoglu, Baris; Schartau, Markus; Toole, Dierdre A.; Wiggert, Jerry D.

    2006-03-01

    In this paper, we review the state of the art and major challenges in current efforts to incorporate biogeochemical functional groups into models that can be applied on basin-wide and global scales, with an emphasis on models that might ultimately be used to predict how biogeochemical cycles in the ocean will respond to global warming. We define the term "biogeochemical functional group" to refer to groups of organisms that mediate specific chemical reactions in the ocean. Thus, according to this definition, "functional groups" have no phylogenetic meaning—these are composed of many different species with common biogeochemical functions. Substantial progress has been made in the last decade toward quantifying the rates of these various functions and understanding the factors that control them. For some of these groups, we have developed fairly sophisticated models that incorporate this understanding, e.g. for diazotrophs (e.g. Trichodesmium), silica producers (diatoms) and calcifiers (e.g. coccolithophorids and specifically Emiliania huxleyi). However, current representations of nitrogen fixation and calcification are incomplete, i.e., based primarily upon models of Trichodesmium and E. huxleyi, respectively, and many important functional groups have not yet been considered in open-ocean biogeochemical models. Progress has been made over the last decade in efforts to simulate dimethylsulfide (DMS) production and cycling (i.e., by dinoflagellates and prymnesiophytes) and denitrification, but these efforts are still in their infancy, and many significant problems remain. One obvious gap is that virtually all functional group modeling efforts have focused on autotrophic microbes, while higher trophic levels have been completely ignored. It appears that in some cases (e.g., calcification), incorporating higher trophic levels may be essential not only for representing a particular biogeochemical reaction, but also for modeling export. Another serious problem is our tendency to model the organisms for which we have the most validation data (e.g., E. huxleyi and Trichodesmium) even when they may represent only a fraction of the biogeochemical functional group we are trying to represent. When we step back and look at the paleo-oceanographic record, it suggests that oxygen concentrations have played a central role in the evolution and emergence of many of the key functional groups that influence biogeochemical cycles in the present-day ocean. However, more subtle effects are likely to be important over the next century like changes in silicate supply or turbulence that can influence the relative success of diatoms versus dinoflagellates, coccolithophorids and diazotrophs. In general, inferences drawn from the paleo-oceanographic record and theoretical work suggest that global warming will tend to favor the latter because it will give rise to increased stratification. However, decreases in pH and Fe supply could adversely impact coccolithophorids and diazotrophs in the future. It may be necessary to include explicit dynamic representations of nitrogen fixation, denitrification, silicification and calcification in our models if our goal is predicting the oceanic carbon cycle in the future, because these processes appear to play a very significant role in the carbon cycle of the present-day ocean and they are sensitive to climate change. Observations and models suggest that it may also be necessary to include the DMS cycle to predict future climate, though the effects are still highly uncertain. We have learned a tremendous amount about the distributions and biogeochemical impact of bacteria in the ocean in recent years, yet this improved understanding has not yet been incorporated into many of our models. All of these considerations lead us toward the development of increasingly complex models. However, recent quantitative model intercomparison studies suggest that continuing to add complexity and more functional groups to our ecosystem models may lead to decreases in predictive ability if the models are not p

  10. Tandem decarboxylative hydroformylation-hydrogenation reaction of ?,?-unsaturated carboxylic acids toward aliphatic alcohols under mild conditions employing a supramolecular catalyst system.

    PubMed

    Diab, Lisa; Gellrich, Urs; Breit, Bernhard

    2013-10-28

    A new atom economic catalytic method for a highly chemoselective reduction of ?,?-unsaturated carboxylic acids to the corresponding saturated alcohols under mild reaction conditions, compatible with a wide range reactive functional groups, is reported. The new methodology consists of a novel tandem decarboxylative hydroformylation/aldehyde reduction sequence employing a unique supramolecular catalyst system. PMID:24022335

  11. The size of hydroxyl groups in solution and the changes in size associated with the ionization of phenolic, carboxylic and amino groups in phenolic quaternary ammonium salts, nicotine and some amino acids: possible implications for drug-water and drug-receptor interactions.

    PubMed Central

    Barlow, R. B.

    1980-01-01

    Size in solution can be expressed either as the apparent molal volume at infinite dilution (phi 0v) amd the concentration parameter (j) or as the partial molal volume of the solute at infinite dilution (V0(2)) and the concentration parameter for the solute or solvent (qs or qw). Although calculated differently, these are derived from the same results and are equivalent. From measurement with phenolic quaternary ammonium salts, including compounds with high nicotine-like activity, the apparent size of the hydroxyl group in water is small and variable. Phenolic groups are slightly larger than alcoholic groups, which should be better hydrogen donors. By measuring the volume change associated with ionisation it is possible to measure the size of charged groups such as phenate and carboxylate; these are much smaller than phenolic and carboxyl. Ammonium groups, however, are only slightly smaller than the corresponding amines. The zwitterion forms of amino acids are associated with a minimum in volume but the volume changes increase with chain length from glycine to gamma-aminobutyric acid. Groups separated by less than this distance interact in their effects on water. Decreases in volume or unexpectedly small increments in apparent molal volume represent decreases in entropy which must be taken into account in drug-water-receptor interactions. Although they may be offset by enthalpy changes, they should favour binding because there is more scope for an increase in entropy. This might explain the association of the small apparent size in water of the hydroxyl group in many compounds with its effects of their affinity for receptors. PMID:7470734

  12. Cinoxacin complexes with divalent metal ions. Spectroscopic characterization. Crystal structure of a new dinuclear Cd(II) complex having two chelate-bridging carboxylate groups. Antibacterial studies

    Microsoft Academic Search

    M Ru??z; L Perelló; J Server-Carrió; R Ortiz; S Garc??a-Granda; M. R D??az; E Cantón

    1998-01-01

    Several cinoxacin (HCx) complexes with divalent metal ions have been prepared and characterized by spectroscopic techniques. The crystal structure of [Cd2(Cx)4(H2O)2]·10H2O has been determined by X-ray diffraction. The complex is triclinic, space group P1? with unit-cell dimensions: a=10.412(2), b=11.119(2), c=13.143(6)Å, ?=76.78(4)°, ?=74.59(3)°, ?=77.12(3)°, V=1406.0(8) Å3. In this complex each cadmium atom is heptacoordinated; the metal environment is formed by two

  13. catena-Poly[[bis-(?-5-bromo-pyridine-3-carboxyl-ato-?O:O')dicopper(II)]-bis-(?-5-bromo-pyridine-3-carboxyl-ato)-?O,O':N;?N:O,O'].

    PubMed

    Deburgomaster, Paul; Zubieta, Jon

    2010-01-01

    The title compound [Cu(2)(C(6)H(3)BrNO(2))(4)](n), forms sheets in the bc plane. The structure features the dinuclear paddle-wheel cage motif common to copper(II) carboxyl-ates. The polymeric structure is achieved through bridging between binuclear units by the pyridyl donors of two of the four carboxyl-ates of the cage. Each cage engages in axial bonding at each copper atom to a pyridyl nitro-gen donor and extends two 5-bromo-pyridine-3-carboxyl-ate groups to bridge to adjacent binuclear sites in the bc plane. Each cage is linked to four adjacent cages in the plane. The intra-dimer Cu?Cu distance is 2.6465?(5)?Å. The remaining 5-bromo-pyridine-3-carboxyl-ate groups project into the inter-lamellar domain and inter-digitate in pairs from each neighboring layer. PMID:21588877

  14. 1H-Azepine-2-oxo-5-amino-5-carboxylic Acid: A 310 Helix Inducer and an Effective Tool for Functionalized Gold Nanoparticles.

    PubMed

    Pellegrino, Sara; Bonetti, Andrea; Clerici, Francesca; Contini, Alessandro; Moretto, Alessandro; Soave, Raffaella; Gelmi, Maria Luisa

    2015-06-01

    A new ?,?-disubstituted constrained glutamine analogue has been designed to decorate gold nanoparticles and to induce a 310-helix when inserted in peptides. Using an efficient "one-pot" asymmetric Schmidt reaction between 4-disubstituted-cyclohexanone and hydroxyalkylazides, 1H-azepine-2-oxo-5-amino-5-carboxylic acid was prepared. The main (R) isomer was inserted at the N-terminus in a very short peptide sequence (i.e., PhCO-(R)-Oxo-Azn-l-Ala-Aib-l-AlaNHMe) and a stable 310-helix conformation was obtained, as verified by both NMR experiments and molecular dynamics (MD) simulations. Finally, the presence of the hydroxyl chain at the nitrogen atom of the ring allowed for the preparation of covered chiral gold nanoparticles. PMID:25938852

  15. Structural Characterization and Function Determination of a Nonspecific Carboxylate Esterase from the Amidohydrolase Superfamily with a Promiscuous Ability To Hydrolyze Methylphosphonate Esters

    PubMed Central

    2015-01-01

    The uncharacterized protein Rsp3690 from Rhodobacter sphaeroides is a member of the amidohydrolase superfamily of enzymes. In this investigation the gene for Rsp3690 was expressed in Escherichia coli and purified to homogeneity, and the three-dimensional structure was determined to a resolution of 1.8 Å. The protein folds as a distorted (?/?)8-barrel, and the subunits associate as a homotetramer. The active site is localized to the C-terminal end of the ?-barrel and is highlighted by the formation of a binuclear metal center with two manganese ions that are bridged by Glu-175 and hydroxide. The remaining ligands to the metal center include His-32, His-34, His-207, His-236, and Asp-302. Rsp3690 was shown to catalyze the hydrolysis of a wide variety of carboxylate esters, in addition to organophosphate and organophosphonate esters. The best carboxylate ester substrates identified for Rsp3690 included 2-naphthyl acetate (kcat/Km = 1.0 × 105 M–1 s–1), 2-naphthyl propionate (kcat/Km = 1.5 × 105 M–1 s–1), 1-naphthyl acetate (kcat/Km = 7.5 × 103 M–1 s–1), 4-methylumbelliferyl acetate (kcat/Km = 2.7 × 103 M–1 s–1), 4-nitrophenyl acetate (kcat/Km = 2.3 × 105 M–1 s–1), and 4-nitrophenyl butyrate (kcat/Km = 8.8 × 105 M–1 s–1). The best organophosphonate ester substrates included ethyl 4-nitrophenyl methylphosphonate (kcat/Km = 3.8 × 105 M–1 s–1) and isobutyl 4-nitrophenyl methylphosphonate (kcat/Km = 1.1 × 104 M–1 s–1). The (SP)-enantiomer of isobutyl 4-nitrophenyl methylphosphonate was hydrolyzed 10 times faster than the less toxic (RP)-enantiomer. The high inherent catalytic activity of Rsp3690 for the hydrolysis of the toxic enantiomer of methylphosphonate esters make this enzyme an attractive target for directed evolution investigations. PMID:24832101

  16. In vitro mutagenesis of Caenorhabditis elegans cuticle collagens identifies a potential subtilisin-like protease cleavage site and demonstrates that carboxyl domain disulfide bonding is required for normal function but not assembly.

    PubMed Central

    Yang, J; Kramer, J M

    1994-01-01

    The importance of conserved amino acids in the amino and carboxyl non-Gly-X-Y domains of Caenorhabditis elegans cuticle collagens was examined by analyzing site-directed mutations of the sqt-1 and rol-6 collagen genes in transgenic animals. Altered collagen genes on transgenic arrays were shown to produce appropriate phenotypes by injecting in vivo cloned mutant alleles. Equivalent alterations in sqt-1 and rol-6 generally produced the same phenotypes, indicating that conserved amino acids in these two collagens have similar functions. Serine substitutions for either of two conserved carboxyl domain cysteines produced LRol phenotypes. Substitution for both cysteines in sqt-1 also resulted in an LRol phenotype, demonstrating that disulfide bonding is important for normal function but not required for assembly. Arg-1 or Arg-4 to Cys mutations in homology block A (HBA; consensus, 1-RXRRQ-5; in the amino non-Gly-X-Y domain) caused RRol phenotypes, while the same alteration at Arg-3 had no effect, indicating that Arg-3 is functionally different from Arg-1 and Arg-4. Substitutions of Arg-4 with Ser, Leu, or Glu also produced the RRol phenotype, while Lys substitutions for Arg-1 or Arg-4 did not generate any abnormal phenotypes. His substitutions for Arg-1 or Arg-4 caused somewhat less severe RRol phenotypes. Therefore, strong positively charged residues, Arg or Lys, are required at positions 1 and 4 for normal function. The conserved pattern of arginines in HBA matches the cleavage sites of the subtilisin-like endoproteinases. HBA may be a cleavage site for a subtilisin-like protease, and cleavage may be important for cuticle collagen processing. PMID:8139571

  17. Computing the Effective Action with the Functional Renormalization Group

    E-print Network

    Codello, Alessandro; Rachwal, Leslaw; Tonero, Alberto

    2015-01-01

    The "exact" or "functional" renormalization group equation describes the renormalization group flow of the effective average action $\\Gamma_k$. The ordinary effective action $\\Gamma_0$ can be obtained by integrating the flow equation from an ultraviolet scale $k=\\Lambda$ down to $k=0$. We give several examples of such calculations at one-loop, both in renormalizable and in effective field theories. We use the results of Barvinsky, Vilkovisky and Avramidi on the non-local heat kernel coefficients to reproduce the four point scattering amplitude in the case of a real scalar field theory with quartic potential and in the case of the pion chiral lagrangian. In the case of gauge theories, we reproduce the vacuum polarization of QED and of Yang-Mills theory. We also compute the two point functions for scalars and gravitons in the effective field theory of scalar fields minimally coupled to gravity.

  18. Computing the Effective Action with the Functional Renormalization Group

    E-print Network

    Alessandro Codello; Roberto Percacci; Leslaw Rachwal; Alberto Tonero

    2015-05-12

    The "exact" or "functional" renormalization group equation describes the renormalization group flow of the effective average action $\\Gamma_k$. The ordinary effective action $\\Gamma_0$ can be obtained by integrating the flow equation from an ultraviolet scale $k=\\Lambda$ down to $k=0$. We give several examples of such calculations at one-loop, both in renormalizable and in effective field theories. We use the results of Barvinsky, Vilkovisky and Avramidi on the non-local heat kernel coefficients to reproduce the four point scattering amplitude in the case of a real scalar field theory with quartic potential and in the case of the pion chiral lagrangian. In the case of gauge theories, we reproduce the vacuum polarization of QED and of Yang-Mills theory. We also compute the two point functions for scalars and gravitons in the effective field theory of scalar fields minimally coupled to gravity.

  19. Conversion of carboxylate salts to carboxylic acids via reactive distillation

    E-print Network

    Williamson, Shelly Ann

    2000-01-01

    on the conversion of the carboxylate salts produced via fermentation into their corresponding acids via reactive distillation. The primary objective is to determine the optimal operating conditions of the distillation. A secondary objective is to optimize...

  20. Conversion of carboxylate salts to carboxylic acids via reactive distillation 

    E-print Network

    Williamson, Shelly Ann

    2000-01-01

    , municipal solid wastes, sewage sludge, and industrial biosludge. Using a proprietary technology owned by Texas A&M University the wastes are first treated with lime to enhance reactivity. Then they are converted to calcium carboxylate salts using a mixed...

  1. Protist functional groups in a sublittoral estuarine epibenthic area

    Microsoft Academic Search

    Gregorio Fernandez-Leborans; Delia Fernandez-Fernandez

    2002-01-01

    Protist communities were studied monthly at Santoña beach (Cantabrian Sea, Spain) throughout one year. Twelve abiotic parameters\\u000a were analyzed. The following functional groups (defined according to the preferential source of food) were considered: photoautotrophs\\u000a (P), saprotrophs (S), bacterivores (B), algivores (A), non-selectives (N), and predators or raptors (R). A total of 269 species\\u000a was found. The percentage of species in

  2. Crystallization of silver carboxylates from sodium carboxylate mixtures.

    PubMed

    Dong, Jingshan; Whitcomb, David R; McCormick, Alon V; Davis, H Ted

    2007-07-17

    Silver carboxylates can be made by the reaction of silver nitrate and the corresponding sodium carboxylates. The length of the alkyl chain has a significant impact on the product behavior. In this study, 18, 20, and 22 carbon chains (stearate, arachidate, and behenate, respectively) have been selected. All three sodium carboxylates are very insoluble in water at room temperature. Solutions are obtained above the Krafft temperature, which precipitates lamellar crystals if cooled at the proper cooling rate. Depending on the chain length, metastable morphologies, such as vesicles and tiny fibers, can be seen consecutively before hexagonal plates form. The carboxylate with the shorter chain length reaches equilibrium more quickly. All three silver carboxylates also take on a lamellar structure. Small-angle X-ray scattering (SAXS) shows that the d spacing of the crystals increases as the chain length increases. Cryo-TEM illustrates that the crystallites are the result of micelle nucleation and micelle aggregation. In addition, the crystallization process in the presence of silver bromide nanocrystals has been investigated. In the initial stage, an epitaxial interface is formed between the silver carboxylate crystallites and the cubic silver bromide grains. Budlike and strandlike structures grow because of it. The consequent strand enclosure restrains the crystal growth, which reduces the size and changes the morphology of the crystals. PMID:17567157

  3. Vibrational spectroscopic and molecular docking study of 4-Methylphenylquinoline-2-carboxylate

    NASA Astrophysics Data System (ADS)

    Fazal, E.; Panicker, C. Yohannan; Varghese, Hema Tresa; Nagarajan, S.; Sudha, B. S.; War, Javeed Ahamad; Srivastava, S. K.; Harikumar, B.; Anto, P. L.

    2015-05-01

    FT-IR and FT-Raman spectra of 4-Methylphenylquinoline-2-carboxylate were recorded and analyzed. The structure of the molecule has been optimized and structural characteristics have been determined by density functional theory. The geometrical parameters (DFT) are in agreement with the XRD results. HOMO and LUMO and other chemical properties are reported. Nonlinear optical properties are also reported. A detailed molecular picture of the title compound and its interactions were obtained from NBO analysis. The negative (red and yellow) regions of the MEP are related to electrophilic reactivity and the positive (blue) regions to nucleophilic reactivity, as shown in the MEP plot and the carbonyl group and the phenyl rings are observed as electrophilic. PASS analysis predicts that the 4-Methylphenylquinoline-2-carboxylate might exhibit anti-diabetic activity. Molecular docking results suggest that the compound might exhibit inhibitory activity against GPb.

  4. Thermolysis of carboxylic acid salts

    SciTech Connect

    Khlestkin, R.N.; Khlestkina, V.L.; Usanov, N.G.; Gareev, V.M.

    1982-07-01

    The dependence of the thermal stability of carboxylic acid salts on the nature of the anion and cation of the salt was studied. It was found that the capacity for thermal decomposition by salts of aliphatic, naphthenic, aromatic and heterocyclic carboxylic acids (with the exception of alkali salts) varies in inverse proportion to the values of the pK/sub a/ of the acids and to the values of the standard heats of formation of oxides (of the metal which forms the salt) relative to a monovalent bond with oxygen. An empirical equation which permits the thermal stability of many carboxylic acid salts to be predicted is given. Recommendations are developed for evaluating the relative activity of oxide and carbonate catalysts in reactions of vapor-phase conversion of aliphatic carboxylic acids to ketones and their operating temperatures.

  5. Functional group diversity of bee pollinators increases crop yield

    PubMed Central

    Hoehn, Patrick; Tscharntke, Teja; Tylianakis, Jason M; Steffan-Dewenter, Ingolf

    2008-01-01

    Niche complementarity is a commonly invoked mechanism underlying the positive relationship between biodiversity and ecosystem functioning, but little empirical evidence exists for complementarity among pollinator species. This study related differences in three functional traits of pollinating bees (flower height preference, daily time of flower visitation and within-flower behaviour) to the seed set of the obligate cross-pollinated pumpkin Cucurbita moschata Duch. ex Poir. across a land-use intensity gradient from tropical rainforest and agroforests to grassland in Indonesia. Bee richness and abundance changed with habitat variables and we used this natural variation to test whether complementary resource use by the diverse pollinator community enhanced final yield. We found that pollinator diversity, but not abundance, was positively related to seed set of pumpkins. Bees showed species-specific spatial and temporal variation in flower visitation traits and within-flower behaviour, allowing for classification into functional guilds. Diversity of functional groups explained even more of the variance in seed set (r2=45%) than did species richness (r2=32%) highlighting the role of functional complementarity. Even though we do not provide experimental, but rather correlative evidence, we can link spatial and temporal complementarity in highly diverse pollinator communities to pollination success in the field, leading to enhanced crop yield without any managed honeybees. PMID:18595841

  6. Photocaging of carboxylic acids: a modular approach.

    PubMed

    Szyma?ski, Wiktor; Velema, Willem A; Feringa, Ben L

    2014-08-11

    Photocaged compounds are important tools for studying and regulating multiple processes, including biological functions. Reported herein is the use of the Passerini multicomponent reaction for modular preparation of photocaged carboxylic acids. The reaction is compatible with several functionalities and proceeds smoothly both in water and dichloromethane. The choice of aldehyde determines the wavelength used for deprotection and enables formation of orthogonally protected products. The isocyanide component can be used for introduction of reactive tags and photosensitizers, as well as for immobilization on a solid support. PMID:24801857

  7. [Influence of carboxylic carbon nanotube supported platinum catalyst on cathode oxygen reduction performance of MFC].

    PubMed

    Tu, Li-Xing; Zhu, Neng-Wu; Wu, Ping-Xiao; Li, Ping; Wu, Jin-Hua

    2013-04-01

    The cathodic catalyst plays an important role in the electricity generation of the microbial fuel cell (MFC). In order to evaluate the efficiency of oxygen reduction on the carbon nanotube (CNT) functionalized with different carboxylic groups supported Pt, carboxylic CNTs under the conditions of 80 degrees C and 95 degrees C were prepared, respectively. Pt/CNT catalysts (Pt/CNT-80 and Pt/CNT-95) was prepared by the dipping-precipitation method and their oxygen reduction efficiency was tested in the MFC (MFC-80, MFC-95 and MFC-C) with the air cathode. The results showed that the maximum power output densities of the MFC-95 and MFC-80 were 568.8 mWx m(-2) and 412.8 mWx m(-2), internal resistances were 204.7 omega and 207.7 omega, and open circuit potentials were 0.719 V and 0.651 V, respectively. However, the maximum power output density of the control MFC-C was only 5.4 mW x m(-2), and its internal resistance was 826.2 omega. XPS and XRD analysis results demonstrate that the efficiency of Pt/CNT-95 catalyst is better than Pt/CNT-80 may result from the surface of carboxylic CNT in the 95 degrees C introduced rich oxygen containing groups. PMID:23798151

  8. Organized thiol functional groups in mesoporous core shell colloids

    SciTech Connect

    Marchena, Martin H. [Gerencia Quimica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), Avda. Gral. Paz 1499, B1650KNA Buenos Aires (Argentina); Granada, Mara [Centro Atomico Bariloche-CNEA, 8400 San Carlos de Bariloche (Argentina); Instituto Balseiro-Centro Atomico Bariloche-CNEA, San Carlos de Bariloche 8400 (Argentina); Bordoni, Andrea V. [Gerencia Quimica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), Avda. Gral. Paz 1499, B1650KNA Buenos Aires (Argentina); Joselevich, Maria [Asociacion Civil Expedicion Ciencia, Cabrera 4948, C1414BGP Buenos Aires (Argentina); Troiani, Horacio [Centro Atomico Bariloche-CNEA, 8400 San Carlos de Bariloche (Argentina); Instituto Balseiro-Centro Atomico Bariloche-CNEA, San Carlos de Bariloche 8400 (Argentina); Williams, Federico J. [DQIAQyF-INQUIMAE FCEN, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon II, C1428EHA Buenos Aires (Argentina); Wolosiuk, Alejandro, E-mail: wolosiuk@cnea.gov.ar [Gerencia Quimica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), Avda. Gral. Paz 1499, B1650KNA Buenos Aires (Argentina)

    2012-03-15

    The co-condensation in situ of tetraethoxysilane (TEOS) and mercaptopropyltrimethoxysilane (MPTMS) using cetyltrimethylammonium bromide (CTAB) as a template results in the synthesis of multilayered mesoporous structured SiO{sub 2} colloids with 'onion-like' chemical environments. Thiol groups were anchored to an inner selected SiO{sub 2} porous layer in a bilayered core shell particle producing different chemical regions inside the colloidal layered structure. X-Ray Photoelectron Spectroscopy (XPS) shows a preferential anchoring of the -SH groups in the double layer shell system, while porosimetry and simple chemical modifications confirm that pores are accessible. We can envision the synthesis of interesting colloidal objects with defined chemical environments with highly controlled properties. - Graphical abstract: Mesoporous core shell SiO{sub 2} colloids with organized thiol groups. Highlights: Black-Right-Pointing-Pointer Double shell mesoporous silica colloids templated with CTAB. Black-Right-Pointing-Pointer Sequential deposition of mesoporous SiO{sub 2} layers with different chemistries. Black-Right-Pointing-Pointer XPS shows the selective functionalization of mesoporous layers with thiol groups.

  9. Symmetry groups, density-matrix equations and covariant Wigner functions

    NASA Astrophysics Data System (ADS)

    Santana, A. E.; Neto, A. Matos; Vianna, J. D. M.; Khanna, F. C.

    2000-06-01

    A representation theory for Lie groups is developed taking the Hilbert space, say Hw, of the w?-algebra standard representation as the representation space. In this context the states describing physical systems are amplitude wave functions but closely connected with the notion of the density matrix. Then, based on symmetry properties, a general physical interpretation for the dual variables of thermal theories, in particular the thermofield dynamics (TFD) formalism, is introduced. The kinematic symmetries, Galilei and Poincaré, are studied and (density) amplitude matrix equations are derived for both of these cases. In the same context of group theory, the notion of phase space in quantum theory is analysed. Thus, in the non-relativistic situation, the concept of density amplitude is introduced, and as an example, a spin-half system is algebraically studied; Wigner function representations for the amplitude density matrices are derived and the connection of TFD and the usual Wigner-function methods are analysed. For the Poincaré symmetries the relativistic density matrix equations are studied for the scalar and spinorial fields. The relativistic phase space is built following the lines of the non-relativistic case. So, for the scalar field, the kinetic theory is introduced via the Klein-Gordon density-matrix equation, and a derivation of the Jüttiner distribution is presented as an example, thus making it possible to compare with the standard approaches. The analysis of the phase space for the Dirac field is carried out in connection with the dual spinor structure induced by the Dirac-field density-matrix equation, with the physical content relying on the symmetry groups. Gauge invariance is considered and, as a basic result, it is shown that the Heinz density operator (which has been used to develope a gauge covariant kinetic theory) is a particular solution for the (Klein-Gordon and Dirac) density-matrix equation.

  10. Cloning and Functional Characterization of Novel Variants and Tissue-Specific Expression of Alternative Amino and Carboxyl Termini of Products of Slc4a10

    PubMed Central

    Qin, Xue; Xie, Zhang-Dong; Wang, Qing K.; Liu, Mugen; Chen, Li-Ming

    2013-01-01

    Previous studies have shown that the electroneutral Na+/HCO3? cotransporter NBCn2 (SLC4A10) is predominantly expressed in the central nervous system (CNS). The physiological and pathological significances of NBCn2 have been well recognized. However, little is known about the tissue specificity of expression of different NBCn2 variants. Moreover, little is known about the expression of NBCn2 proteins in systems other than CNS. Here, we identified a set of novel Slc4a10 variants differing from the originally described ones by containing a distinct 5? untranslated region encoding a new extreme amino-terminus (Nt). Electrophysiology measurements showed that both NBCn2 variants with alternative Nt contain typical electroneutral Na+-coupled HCO3? transport activity in Xenopus oocytes. Luciferase reporter assay showed that Slc4a10 contains two alternative promoters responsible for expression of the two types of NBCn2 with distinct extreme Nt. Western blotting showed that NBCn2 proteins with the original Nt are primarily expressed in CNS, whereas those with the novel Nt are predominantly expressed in the kidney and to a lesser extent in the small intestine. Due to alternative splicing, the known NBCn2 variants contain two types of carboxyl-termini (CT) differing in the optional inclusion of a PDZ-binding motif. cDNA cloning showed that virtually all NBCn2 variants expressed in epithelial tissues contain, but the vast majority of those from the neural tissues lack the PDZ-binding motif. We conclude that alternative transcription and splicing of Slc4a10 products are regulated in a tissue-specific manner. Our findings provide critical insights that will greatly influence the study of the physiology of NBCn2. PMID:23409100

  11. The interaction of carboxylic acids with aluminium oxides: journeying from a basic understanding of alumina nanoparticles to water treatment for industrial and humanitarian applications.

    PubMed

    Barron, Andrew R

    2014-06-14

    Carboxylic acids are found to react with aluminium oxides via a topotactic reaction such that the carboxylate acts as a bridging ligand. This reaction allows for carboxylate-functionalized alumina nanoparticles to be prepared directly from boehmite (AlOOH). Understanding the structural relationship between molecular and surface species allows for the rationalization/prediction of suitable alternative ligands as well as alternative oxide surfaces. The identity of the carboxylate substituent controls the pH stability of a nanoparticle as well as the porosity and processability of ceramics prepared by thermolysis. Through the choice of functional groups on the carboxylic acid the properties of the alumina surface or alumina nanoparticle can be tailored. For example, the solubility/miscibility of nanoparticles can be tuned to the solvent/matrix, and the wettability to be varied from hydrophobic to super hydrophilic. The choice Zwitter ionic substituents on alumina micro-/ultra-filtration membranes are found to enhance the flux and limit fouling while allowing for the facile separation of organic compounds from water. Examples are presented of purification of frac and flow-back water from oil well production as well as providing drinking water from contaminated sources in underdeveloped regions. PMID:24728503

  12. A group theoretical approach to graviton two-point function

    NASA Astrophysics Data System (ADS)

    Rahbardehghan, S.; Pejhan, H.; Elmizadeh, M.

    2015-03-01

    Respecting the group theoretical approach, it is debated that the theory of linear conformal gravity should be formulated through a tensor field of rank-3 and mixed symmetry (Binegar et al., Phys Rev D 27: 2249, 1983). Pursuing this path, such a field equation was obtained in de Sitter space (Takook et al., J Math Phys 51:032503, 2010). In the present work, considering the de Sitter ambient space notation, a proper solution to the physical part of this field equation is obtained. We have also calculated the related two-point function, which is interestingly de Sitter invariant and free of an infrared divergence.

  13. Functional renormalization group study of nuclear and neutron matter

    E-print Network

    Matthias Drews; Wolfram Weise

    2014-10-31

    A chiral model based on nucleons interacting via boson exchange is investigated. Fluctuation effects are included consistently beyond the mean-field approximation in the framework of the functional renormalization group. The liquid-gas phase transition of symmetric nuclear matter is studied in detail. No sign of a chiral restoration transition is found up to temperatures of about 100 MeV and densities of at least three times the density of normal nuclear matter. Moreover, the model is extended to asymmetric nuclear matter and the constraints from neutron star observations are discussed.

  14. Functional Renormalisation Group Approach for Tensorial Group Field Theory: a Rank-3 Model

    E-print Network

    Dario Benedetti; Joseph Ben Geloun; Daniele Oriti

    2015-02-01

    We set up the Functional Renormalisation Group formalism for Tensorial Group Field Theory in full generality. We then apply it to a rank-3 model over U(1) x U(1) x U(1), endowed with a linear kinetic term and nonlocal interactions. The system of FRG equations turns out to be non-autonomous in the RG flow parameter. This feature is explained by the existence of a hidden scale, the radius of the group manifold. We investigate in detail the opposite regimes of large cut-off (UV) and small cut-off (IR) of the FRG equations, where the system becomes autonomous, and we find, in both case, Gaussian and non-Gaussian fixed points. We derive and interpret the critical exponents and flow diagrams associated with these fixed points, and discuss how the UV and IR regimes are matched at finite N. Finally, we discuss the evidence for a phase transition from a symmetric phase to a broken or condensed phase, from an RG perspective, finding that this seems to exist only in the approximate regime of very large radius of the group manifold, as to be expected for systems on compact manifolds.

  15. Pear ACO genes encoding putative 1-aminocyclopropane-1-carboxylate oxidase homologs are functionally expressed during fruit ripening and involved in response to salicylic acid.

    PubMed

    Shi, Hai-Yan; Zhang, Yu-Xing

    2012-10-01

    1-Aminocyclopropane-1-carboxylate (ACC) oxidase catalyzes the final reaction of the ethylene biosynthetic pathway, converting ACC into ethylene. Past studies have shown a possible link between ACC oxidase and salicylic acid during fruit ripening in pear, but the relationship has received no more than modest study at the gene expression level. In this study, two cDNA clones encoding putative ACC oxidase, PpACO1 and PpACO2, were isolated from a cDNA library constructed by our own laboratory and produced using mRNA from mesocarp of pear (Pyrus pyrifolia Nakai. cv.Whangkeumbae). One cDNA clone, designated PpACO1 (GenBank accession No. JN807390), comprised an open reading frame of 945 bp encoding a protein of 314 amino acids. The other cDNA, designated PpACO2 (GenBank accession No. JN807392), encodes a protein with 322 amino acids that shares high similarity with the known plant ACOs. Using PCR amplification techniques, two genomic clones corresponding to PpACO1 and PpACO2 were isolated and shown to contain independently three introns with typical GT/AG boundaries defining the splice junctions. The PpACO1 gene product shared 99 % identity with an ACC oxidase from pear (Pyrus × bretschneideri Rehd.cv.Yali), and phylogenetic analyses clearly placed the gene product in the ACC oxidase cluster of the pear 2-oxoglutarate-dependent dioxygenase superfamily tree. Quantitative RT-PCR analysis indicated that the two PpACO genes are differentially expressed in pear tissues. PpACO1 and PpACO2 were predominantly expressed in fruit. The transcripts of PpACO1 were accumulated at relatively low levels in early fruit, but strongly high levels in fruit ripening and senescence stages, while the transcripts of PpACO2 were accumulated at higher levels in early fruit and much lower levels with further fruit cell development than the transcripts of PpACO1. In addition, PpACO1 gene was down-regulated in fruit by salicylic acid (SA). Nevertheless, PpACO2 gene was dramatically up-regulated in fruit by SA. These results suggested that the PpACOs may participate in regulation of fruit ripening and in response to SA in pear. PMID:22711312

  16. Poly[diaqua­(?-oxalato)(?-2-oxidopyridinium-3-carboxyl­ato)lanthanum(III)

    PubMed Central

    Hu, Zhen; Zhu, Zhi-Bo

    2009-01-01

    In the title complex, [La(C6H4NO3)(C2O4)(H2O)2]n, the LaIII ion is coordinated by eight O atoms from two 2-oxido­pyridinium-3-carboxyl­ate ligands, two oxalate ligands and two water mol­ecules in a distorted bicapped square-anti­prismatic geometry. The carboxyl­ate groups link adjacent LaIII ions, forming two-dimensional layers that are further linked by N—H?O and O—H?O hydrogen bonds. PMID:21583041

  17. Disorder in the anionic part of catena-poly[[(pyrazine-2-carboxyl­ato)copper(II)]-?-pyrazine-2-carboxyl­ato

    PubMed Central

    Albanez, Joselyn; Brito, Iván; Cárdenas, Alejandro; López-Rodríguez, Matías

    2012-01-01

    The title compound, [Cu(C5H3N2O2)0.88(C6H4NO2)1.12]n, is characterized by disorder of the anion, resulting from a statistical occupation in a 0.44?(3):0.56?(3) ratio of pyrazine-2-carboxylate and pyridine-2-carboxylate. The compound was isolated during attempts to synthesize a mixed-ligand coordination polymer by solvothermal reaction between copper(II) nitrate and equimolar mixtures of pyrazine-2-carboxylic acid and pyridine-2-carb­oxy­lic acid in a mixture of water and EtOH. The difference in the two components of the compound is due to substitutional disorder of a CH group for one of the N atoms of the pyrazine ring which share the same site in the structure. In the crystal structure, the CuII atom lies on an inversion centre and is six-coordinated in a distorted N2O4 geometry. The carboxyl­ate group carbonyl O atoms are weakly coordinated to an equivalent CuII atom that is translated one unit cell in the a-axis direction, thus forming a polymeric chain through carboxyl­ate bridges. PMID:22589852

  18. A method to quantify organic functional groups and inorganic compounds in ambient aerosols using attenuated total reflectance FTIR spectroscopy and multivariate chemometric techniques

    NASA Astrophysics Data System (ADS)

    Coury, Charity; Dillner, Ann M.

    An attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic technique and a multivariate calibration method were developed to quantify ambient aerosol organic functional groups and inorganic compounds. These methods were applied to size-resolved particulate matter samples collected in winter and summer of 2004 at three sites: a downtown Phoenix, Arizona location, a rural site near Phoenix, and an urban fringe site between the urban and rural site. Ten organic compound classes, including four classes which contain a carbonyl functional group, and three inorganic species were identified in the ambient samples. A partial least squares calibration was developed and applied to the ambient spectra, and 13 functional groups related to organic compounds (aliphatic and aromatic CH, methylene, methyl, alkene, aldehydes/ketones, carboxylic acids, esters/lactones, acid anhydrides, carbohydrate hydroxyl and ethers, amino acids, and amines) as well as ammonium sulfate and ammonium nitrate were quantified. Comparison of the sum of the mass measured by the ATR-FTIR technique and gravimetric mass indicates that this method can quantify nearly all of the aerosol mass on sub-micrometer size-segregated samples. Analysis of sample results shows that differences in organic functional group and inorganic compound concentrations at the three sampling sites can be measured with these methods. Future work will analyze the quantified data from these three sites in detail.

  19. Vibrational spectra, electronic absorption, nonlinear optical properties, evaluation of bonding, chemical reactivity and thermodynamic properties of ethyl 4-(1-(2-(hydrazinecarbonothioyl)hydrazono)ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate molecule by ab initio HF and density functional methods.

    PubMed

    Singh, R N; Rawat, Poonam; Sahu, Sangeeta

    2015-01-25

    In this work, detailed vibrational spectral analysis of ethyl 4-(1-(2-(hydrazinecarbonothioyl)hydrazono)ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate (EHCHEDPC) molecule has been carried out using FT-IR spectroscopy and potential energy distribution (PED). Theoretical calculations were performed by ab initio RHF and density functional theory (DFT) method, using 6-31G(d,p) and 6-311+G(d,p) basis sets. The other carried outwork cover: structural, thermodynamic properties, electronic transitions, bonding, multiple interaction, chemical reactivity and hyperpolarizability analysis. The results of the calculation were applied to the simulated spectra of (EHCHEDPC), which show excellent agreement with observed spectra. The vibrational analysis shows red shift in both group, the proton donor (pyrrole N-H) and proton acceptor (C=O of ester) indicating the presence of intermolecular hydrogen bonding. Time dependent density functional theory (TD-DFT) has been used to find electronic excitations and their nature. The results of natural bond orbital (NBOs) analysis show the charges transfer and delocalization in various intra- and intermolecular interactions. The binding energy of intermolecular multiple interactions is calculated to be 12.54 kcal mol(-1) using QTAIM calculation. The electronic descriptors analyses reveal the investigated molecule used as precursor for heterocyclic derivatives synthesis. First hyperpolarizability (?0) has been computed to evaluate non-linear optical (NLO) response. PMID:25168004

  20. Vibrational spectra, electronic absorption, nonlinear optical properties, evaluation of bonding, chemical reactivity and thermodynamic properties of ethyl 4-(1-(2-(hydrazinecarbonothioyl)hydrazono)ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate molecule by ab initio HF and density functional methods

    NASA Astrophysics Data System (ADS)

    Singh, R. N.; Rawat, Poonam; Sahu, Sangeeta

    2015-01-01

    In this work, detailed vibrational spectral analysis of ethyl 4-(1-(2-(hydrazinecarbonothioyl)hydrazono)ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylate (EHCHEDPC) molecule has been carried out using FT-IR spectroscopy and potential energy distribution (PED). Theoretical calculations were performed by ab initio RHF and density functional theory (DFT) method, using 6-31G(d,p) and 6-311+G(d,p) basis sets. The other carried outwork cover: structural, thermodynamic properties, electronic transitions, bonding, multiple interaction, chemical reactivity and hyperpolarizability analysis. The results of the calculation were applied to the simulated spectra of (EHCHEDPC), which show excellent agreement with observed spectra. The vibrational analysis shows red shift in both group, the proton donor (pyrrole Nsbnd H) and proton acceptor (Cdbnd O of ester) indicating the presence of intermolecular hydrogen bonding. Time dependent density functional theory (TD-DFT) has been used to find electronic excitations and their nature. The results of natural bond orbital (NBOs) analysis show the charges transfer and delocalization in various intra- and intermolecular interactions. The binding energy of intermolecular multiple interactions is calculated to be 12.54 kcal mol-1 using QTAIM calculation. The electronic descriptors analyses reveal the investigated molecule used as precursor for heterocyclic derivatives synthesis. First hyperpolarizability (?0) has been computed to evaluate non-linear optical (NLO) response.

  1. 5-Amino-1H-1,2,4-triazol-4-ium-3-carboxyl­ate hemihydrate

    PubMed Central

    Fernandes, José A.; Liu, Bing; Tomé, João P. C.; Cunha-Silva, Luís; Almeida Paz, Filipe A.

    2011-01-01

    The asymmetric unit of the title compound, C3H4N4O2·0.5H2O, comprises two whole mol­ecules of 5-amino-1H-1,2,4-triazole-3-carb­oxy­lic acid in its zwitterionic form (proton transfer occurs from the carb­oxy­lic acid group to the N hetero­atom at position 1), plus one water mol­ecule of crystallization. The organic moieties are disposed into supra­molecular layers linked by N—H?O and N—H?N hydrogen bonds parallel to the bc plane. Additional O—H?O and N—H?O hydrogen bonds involving the water mol­ecules and the organic mol­ecules lead to the formation of double-deck supra­molecular arrangements which are inter­connected along the a axis via ?–? stacking [centroid–centroid distance = 3.507?(3)?Å]. PMID:22091097

  2. Dominant Functional Group Effects on the Invasion Resistance at Different Resource Levels

    PubMed Central

    Wang, Jiang; Ge, Yuan; Zhang, Chong B.; Bai, Yi; Du, Zhao K.

    2013-01-01

    Background Functional group composition may affect invasion in two ways the effect of abundance, i.e. dominance of functional group; and the effect of traits, i.e. identity of functional groups. However, few studies have focused on the role of abundance of functional group on invasion resistance. Moreover, how resource availability influences the role of the dominant functional group in invasion resistance is even less understood. Methodology/Principal Findings In this experiment, we established experimental pots using four different functional groups (annual grass, perennial grass, deciduous shrub or arbor and evergreen shrub or arbor), and the dominant functional group was manipulated. These experimental pots were respectively constructed at different soil nitrogen levels (control and fertilized). After one year of growth, we added seeds of 20 different species (five species per functional group) to the experimental pots. Fertilization significantly increased the overall invasion success, while dominant functional group had little effect on overall invasion success. When invaders were grouped into functional groups, invaders generally had lower success in pots dominated by the same functional group in the control pots. However, individual invaders of the same functional group exhibited different invasion patterns. Fertilization generally increased success of invaders in pots dominated by the same than by another functional group. However, fertilization led to great differences for individual invaders. Conclusions/Significance The results showed that the dominant functional group, independent of functional group identity, had a significant effect on the composition of invaders. We suggest that the limiting similarity hypothesis may be applicable at the functional group level, and limiting similarity may have a limited role for individual invaders as shown by the inconsistent effects of dominant functional group and fertilization. PMID:24167565

  3. Synthesis, growth, structural, thermal and optical studies of pyrrolidinium-2-carboxylate-4-nitrophenol single crystals

    NASA Astrophysics Data System (ADS)

    Swarna Sowmya, N.; Sampathkrishnan, S.; Vidyalakshmi, Y.; Sudhahar, S.; Mohan Kumar, R.

    2015-06-01

    Organic nonlinear optical material, pyrrolidinium-2-carboxylate-4-nitrophenol (PCN) was synthesized and single crystals were grown by slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirmed the structure and lattice parameters of PCN crystals. Infrared, Raman and NMR spectral analyses were used to elucidate the functional groups present in the compound. The thermal behavior of synthesized compound was studied by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The photoluminescence property was studied by exciting the crystal at 360 nm. The relative second harmonic generation (SHG) efficiency of grown crystal was estimated by using Nd:YAG laser with fundamental wavelength of 1064 nm.

  4. Titania-Promoted Carboxylic Acid Alkylations of Alkenes and Cascade Addition–Cyclizations

    PubMed Central

    2014-01-01

    Photochemical reactions employing TiO2 and carboxylic acids under dry anaerobic conditions led to several types of C–C bond-forming processes with electron-deficient alkenes. The efficiency of alkylation varied appreciably with substituents in the carboxylic acids. The reactions of aryloxyacetic acids with maleimides resulted in a cascade process in which a pyrrolochromene derivative accompanied the alkylated succinimide. The selectivity for one or other of these products could be tuned to some extent by employing the photoredox catalyst under different conditions. Aryloxyacetic acids adapted for intramolecular ring closures by inclusion of 2-alkenyl, 2-aryl, or 2-oximinyl functionality reacted rather poorly. Profiles of reactant consumption and product formation for these systems were obtained by an in situ NMR monitoring technique. An array of different catalyst forms were tested for efficiency and ease of use. The proposed mechanism, involving hole capture at the TiO2 surface by the carboxylates followed by CO2 loss, was supported by EPR spectroscopic evidence of the intermediates. Deuterium labeling indicated that the titania likely donates protons from surface hydroxyl groups as well as supplying electrons and holes, thus acting as both a catalyst and a reaction partner. PMID:24437519

  5. Application of Hybrid Functional Groups to Predict ATP Binding Proteins

    PubMed Central

    Mbah, Andreas N.

    2014-01-01

    The ATP binding proteins exist as a hybrid of proteins with Walker A motif and universal stress proteins (USPs) having an alternative motif for binding ATP. There is an urgent need to find a reliable and comprehensive hybrid predictor for ATP binding proteins using whole sequence information. In this paper the open source LIBSVM toolbox was used to build a classifier at 10-fold cross-validation. The best hybrid model was the combination of amino acid and dipeptide composition with an accuracy of 84.57% and Mathews correlation coefficient (MCC) value of 0.693. This classifier proves to be better than many classical ATP binding protein predictors. The general trend observed is that combinations of descriptors performed better and improved the overall performances of individual descriptors, particularly when combined with amino acid composition. The work developed a comprehensive model for predicting ATP binding proteins irrespective of their functional motifs. This model provides a high probability of success for molecular biologists in predicting and selecting diverse groups of ATP binding proteins irrespective of their functional motifs. PMID:24729962

  6. Global Amine and Acid Functional Group Modification of Proteins

    PubMed Central

    Krusemark, Casey J.; Ferguson, Jonathan T.; Wenger, Craig D.; Kelleher, Neil L.; Belshaw, Peter J.

    2008-01-01

    A sequential reaction methodology is employed for the complete derivatization of protein thiols, amines, and acids in high purity under denaturing conditions. Following standard thiol alkylation, protein amines are modified via reductive methylation with formaldehyde and pyridine-borane. Protein acids are subsequently amidated under buffered conditions in DMSO using the coupling reagent (7-azabenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate. The generality of the approach is demonstrated with four proteins and with several amines yielding near-quantitative transformations as characterized by high-resolution Fourier transform mass spectrometry. The developed approach has numerous implications for protein characterization and general protein chemistry. Applications in mass spectrometry (MS) based proteomics of intact proteins (top-down MS) are explored, including the addition of stable isotopes for relative quantitation and protein identification through functional group counting. The methodology can be used for altering the physical and chemical properties of proteins, as demonstrated with amidation to modify protein isoelectric point and through derivatization with quaternary amines. Additionally, the chemistry has applications in the semisynthesis of mono-disperse polymers based on protein scaffolds. We prepare proteins modified with azides and alkynes to enable further functionalization via copper(I)-catalyzed 1,3-dipolar Huisgen cycloaddition (“click”) chemistry. PMID:18184016

  7. Four-point functions and the permutation group S4

    E-print Network

    Eichmann, Gernot; Heupel, Walter

    2015-01-01

    Four-point functions are at the heart of many interesting physical processes. A prime example is the light-by-light scattering amplitude, which plays an important role in the calculation of hadronic contributions to the anomalous magnetic moment of the muon. In the calculation of such quantities one faces the challenge of finding a suitable and well-behaved basis of tensor structures in coordinate and/or momentum space. Provided all (or many) of the external legs represent similar particle content, a powerful tool to construct and organize such bases is the permutation group S4. We introduce an efficient notation for dealing with the irreducible multiplets of S4, and we highlight the merits of this treatment by exemplifying four-point functions with gauge-boson legs such as the four-gluon vertex and the light-by-light scattering amplitude. The multiplet analysis is also useful for isolating the important kinematic regions and the dynamical singularity content of such amplitudes. Our analysis serves as a basis...

  8. Four-point functions and the permutation group S4

    E-print Network

    Gernot Eichmann; Christian S. Fischer; Walter Heupel

    2015-05-23

    Four-point functions are at the heart of many interesting physical processes. A prime example is the light-by-light scattering amplitude, which plays an important role in the calculation of hadronic contributions to the anomalous magnetic moment of the muon. In the calculation of such quantities one faces the challenge of finding a suitable and well-behaved basis of tensor structures in coordinate and/or momentum space. Provided all (or many) of the external legs represent similar particle content, a powerful tool to construct and organize such bases is the permutation group S4. We introduce an efficient notation for dealing with the irreducible multiplets of S4, and we highlight the merits of this treatment by exemplifying four-point functions with gauge-boson legs such as the four-gluon vertex and the light-by-light scattering amplitude. The multiplet analysis is also useful for isolating the important kinematic regions and the dynamical singularity content of such amplitudes. Our analysis serves as a basis for future efficient calculations of these and similar objects.

  9. Nucleotide substitutions revealing specific functions of Polycomb group genes.

    PubMed

    Bajusz, Izabella; Sipos, László; Pirity, Melinda K

    2015-04-01

    POLYCOMB group (PCG) proteins belong to the family of epigenetic regulators of genes playing important roles in differentiation and development. Mutants of PcG genes were isolated first in the fruit fly, Drosophila melanogaster, resulting in spectacular segmental transformations due to the ectopic expression of homeotic genes. Homologs of Drosophila PcG genes were also identified in plants and in vertebrates and subsequent experiments revealed the general role of PCG proteins in the maintenance of the repressed state of chromatin through cell divisions. The past decades of gene targeting experiments have allowed us to make significant strides towards understanding how the network of PCG proteins influences multiple aspects of cellular fate determination during development. Being involved in the transmission of specific expression profiles of different cell lineages, PCG proteins were found to control wide spectra of unrelated epigenetic processes in vertebrates, such as stem cell plasticity and renewal, genomic imprinting and inactivation of X-chromosome. PCG proteins also affect regulation of metabolic genes being important for switching programs between pluripotency and differentiation. Insight into the precise roles of PCG proteins in normal physiological processes has emerged from studies employing cell culture-based systems and genetically modified animals. Here we summarize the findings obtained from PcG mutant fruit flies and mice generated to date with a focus on PRC1 and PRC2 members altered by nucleotide substitutions resulting in specific alleles. We also include a compilation of lessons learned from these models about the in vivo functions of this complex protein family. With multiple knockout lines, sophisticated approaches to study the consequences of peculiar missense point mutations, and insights from complementary gain-of-function systems in hand, we are now in a unique position to significantly advance our understanding of the molecular basis of in vivo functions of PcG proteins. PMID:25669595

  10. Applying AFM-based nanofabrication for measuring the thickness of nanopatterns: the role of head groups in the vertical self-assembly of omega-functionalized n-alkanethiols.

    PubMed

    Kelley, Algernon T; Ngunjiri, Johnpeter N; Serem, Wilson K; Lawrence, Steve O; Yu, Jing-Jiang; Crowe, William E; Garno, Jayne C

    2010-03-01

    Molecules of n-alkanethiols with methyl head groups typically form well-ordered monolayers during solution self-assembly for a wide range of experimental conditions. However, we have consistently observed that, for either carboxylic acid or thiol-terminated n-alkanethiols, under certain conditions nanografted patterns are generated with a thickness corresponding precisely to a double layer. To investigate the role of head groups for solution self-assembly, designed patterns of omega-functionalized n-alkanethiols were nanografted with systematic changes in concentration. Nanografting is an in situ approach for writing patterns of thiolated molecules on gold surfaces by scanning with an AFM tip under high force, accomplished in dilute solutions of desired ink molecules. As the tip is scanned across the surface of a self-assembled monolayer under force, the matrix molecules are displaced from the surface and are immediately replaced with fresh molecules from solution to generate nanopatterns. In this report, side-by-side comparison of nanografted patterns is achieved for different matrix molecules using AFM images. The chain length and head groups (i.e., carboxyl, hydroxyl, methyl, thiol) were varied for the nanopatterns and matrix monolayers. Interactions such as head-to-head dimerization affect the vertical self-assembly of omega-functionalized n-alkanethiol molecules within nanografted patterns. At certain threshold concentrations, double layers were observed to form when nanografting with head groups of carboxylic acid and dithiols, whereas single layers were generated exclusively for nanografted patterns with methyl and hydroxyl groups, regardless of changes in concentration. PMID:20131892

  11. Molecular Structure of Cyclopropane carboxylic acid

    NSDL National Science Digital Library

    2003-04-11

    Cyclopropane carboxylic acid is a clear liquid used as an intermediate for agrochemicals, pharmaceuticals, and other organic synthesis such as for the applications of electronics, chemicals, polymer additives, coatings, adhesives, surfactants, and other applications. Also, derivatives of cyclopropane-carboxylic acid are used against parasites in plants and animals. For example, the alkynyl esters of cyclopropane-carboxylic acid are used as pesticides. Similarly, cyclopropane carboxylic acid esters containing a polyhalogenated substituent are used as fungicides.

  12. Functional movement screen scores in a group of running athletes.

    PubMed

    Loudon, Janice K; Parkerson-Mitchell, Amy J; Hildebrand, Laurie D; Teague, Connie

    2014-04-01

    The purpose of this study was to determine the mean values of the functional movement screen (FMS) in a group of long-distance runners. The secondary aims were to investigate whether the FMS performance differed between sexes and between young and older runners. Forty-three runners, 16 women (mean age = 33.5 years, height = 165.2 cm, weight = 56.3 kg, and body mass index [BMI] = 20.6) and 27 men (mean age = 39.3 years, height = 177.6 cm, weight = 75.8 kg, and BMI = 24.2) performed the FMS. All the runners were injury-free and ran >30 km·wk. Independent t-tests were performed on the composite scores to examine the differences between men and women and also between young (<40 years) and older runners (>40 years). Contingency tables (2 × 2) were developed for each of the 7 screening tests to further look at the differences in groups for each single test. The ? values were calculated to determine significant differences. Statistical significance was set at p ? 0.05. There was no significant difference in the composite score between women and men. There were significant differences between the sexes in the push-up and straight leg test scores, with the women scoring better on each test. A significant difference was found in the composite scores between younger and older runners (p < 0.000). Additional score differences were found for the squat, hurdle step, and in-line lunge tests with the younger runners scoring better. This study provided mean values for the FMS in a cohort of long-distance runners. These values can be used as a reference for comparing FMST scores in other runners who are screened with this tool. PMID:24662154

  13. Separation of certain carboxylic acids utilizing cation exchange membranes

    DOEpatents

    Chum, H.L.; Sopher, D.W.

    1983-05-09

    A method of substantially separating monofunctional lower carboxylic acids from a liquid mixture containing the acids wherein the pH of the mixture is adjusted to a value in the range of from about 1 to about 5 to form protonated acids. The mixture is heated to an elevated temperature not greater than about 100/sup 0/C and brought in contact with one side of a perfluorinated cation exchange membrane having sulfonate or carboxylate groups or mixtures thereof with the mixture containing the protonated acids. A pressure gradient can be established across the membrane with the mixture being under higher pressure, so that protonated monofunctional lower carboxylic acids pass through the membrane at a substantially faster rate than the remainder of the mixture thereby substantially separating the acids from the mixture.

  14. Density functional study of electronic, charge density, and chemical bonding properties of 9-methyl-3-Thiophen-2-YI-Thieno [3,2-e] [1, 2, 4] Thriazolo [4,3-c] pyrimidine-8-Carboxylic acid ethyl ester crystals

    NASA Astrophysics Data System (ADS)

    Reshak, A. H.; Kamarudin, H.; Alahmed, Z. A.; Auluck, S.; Chyský, Jan

    2014-06-01

    A comprehensive theoretical density functional investigation of the electronic crystal structure, chemical bonding, and the electron charge densities of 9-Methyl-3-Thiophen-2-YI-Thieno [3, 2-e] [1, 2, 4] Thriazolo [4,3-c] Pyrimidine-8-Carboxylic Acid Ethyl Ester (C15H12N4O2S2) is performed. The density of states at Fermi level equal to 5.50 (3.45) states/Ry cell, and the calculated bare electronic specific heat coefficient is found to be 0.95 (0.59) mJ/mole-K2 for the local density approximation (Engel-Vosko generalized gradient approximation). The electronic charge density space distribution contours in (1 0 0) and (1 1 0) planes were calculated. We find that there are two independent molecules (A and B) in the asymmetric unit exhibit intramolecular C-H…O, C-H…N interactions. This intramolecular interaction is different in molecules A and B, where A molecule show C-H…O interaction while B molecule exhibit C-H…N interaction. We should emphasis that there is ?-? interaction between the pyrimidine rings of the two neighbors B molecules gives extra strengths and stabilizations to the superamolecular structure. The calculated distance between the two neighbors pyrimidine rings found to be 3.345 Å, in good agreement with the measured one (3.424(1) Å).

  15. Large dielectric constant of the chemically functionalized carbon nanotube\\/polymer composites

    Microsoft Academic Search

    Qun Li; Qingzhong Xue; Lanzhong Hao; Xili Gao; Qingbin Zheng

    2008-01-01

    Pristine, carboxylic and ester functionalized multi-walled carbon nanotube (MWCNT)\\/poly(vinylidene fluoride) (PVDF) composites were fabricated by evaporating suspensions of the nanotubes in PVDF. Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) showed that carboxylic groups and ester groups had been introduced on the surface of MWCNTs. The Raman spectroscopy showed that the amorphous carbon materials and impurities had decreased

  16. 4-(Dimethylamino)pyridine-catalysed iodolactonisation of ?,?-unsaturated carboxylic acids.

    PubMed

    Meng, Chuisong; Liu, Zhihui; Liu, Yuxiu; Wang, Qingmin

    2015-06-10

    4-(Dimethylamino)pyridine functioned as an excellent catalyst for iodolactonisation reactions of ?,?-unsaturated carboxylic acids, affording ?-lactones, ?-lactones, or both under neutral conditions at room temperature. The effects of substrate structures on the iodolactonisation were investigated, and a catalytic mechanism is proposed. PMID:26009007

  17. Design of co-crystals/salts of some Nitrogenous bases and some derivatives of thiophene carboxylic acids through a combination of hydrogen and halogen bonds

    PubMed Central

    2014-01-01

    Background The utility of N-heterocyclic bases to obtain molecular complexes with carboxylic acids is well studied. Depending on the solid state interaction between the N-heterocyclic base and a carboxylic acid a variety of neutral or ionic synthons are observed. Meanwhile, pyridines and pyrimidines have been frequently chosen in the area of crystal engineering for their multipurpose functionality. HT (hetero trimers) and LHT (linear heterotetramers) are the well known synthons that are formed in the presence of pyrimidines and carboxylic acids. Results Fourteen crystals involving various substituted thiophene carboxylic acid derivatives and nitrogenous bases were prepared and characterized by using single crystal X-ray diffraction. The 14 crystals can further be divided into two groups [1a-7a], [8b-14b] based on the nature of the nitrogenous base. Carboxylic acid to pyridine proton transfer has occurred in 3 compounds of each group. In addition to the commonly occurring hydrogen bond based pyridine/carboxylic acid and pyrimidine/carboxylic acid synthons which is the reason for assembly of primary motifs, various other interactions like Cl…Cl, Cl…O, C–H…Cl, C-H…S add additional support in organizing these supermolecules into extended architectures. It is also interesting to note that in all the compounds ?-? stacking occurs between the pyrimidine-pyrimidine or pyridine-pyridine or acid-acid moieties rather than acid-pyrimidine/pyridine. Conclusions In all the compounds (1a-14b) either neutral O–H…Npyridyl/pyrimidine or charge-assisted Npyridinium-H…Ocarboxylate hydrogen bonds are present. The HT (hetero trimers) and LHT (linear heterotetramers) are dominant in the crystal structures of the adducts containing N-heterocyclic bases with two proton acceptors (1a-7a). Similar type supramolecular ladders are observed in 5TPC44BIPY (8b), TPC44BIPY (9b), TPC44TMBP (11b). Among the seven compounds [8b-14b] the extended ligands are linear in all except for the TMBP (10b, 11b, 12b). The structure of each compound depends on the dihedral angle between the carboxyl group and the nitrogenous base. All these compounds indicate three main synthons that regularly occur, namely linear heterodimer (HD), heterotrimer (HT) and heterotetramer (LHT). PMID:24655545

  18. The relation between Escherichia coli surface functional groups’ composition and their physicochemical properties

    PubMed Central

    Hamadi, Fatima; Latrache, Hassan; Zahir, Hafida; Elghmari, Abderrahmene; Timinouni, Mohamed; Ellouali, Mostapha

    2008-01-01

    Escherichia coli surface characteristics including hydrophobicity, electrophoretic mobility and surface functional groups’ composition were investigated. These characteristics were determined respectively by water contact angle measurements, microelectrophoresis and x-ray photoelectron spectroscopy (XPS). The relation between the physicochemical properties and functional groups’ composition was also examined. The electrophoretic mobility at pH 7 appeared to be governed on the cell surface by the (O=C) functional groups. The cell surface’s hydrophilicity was associated with high levels of (C-(O.N)) and (OH- (C-O-C)) functional groups, whereas the cell surface’s hydrophobicity was associated with (C-(C,H)) functional groups. PMID:24031168

  19. Detection of functional groups and antibodies on microfabricated surfaces by confocal microscopy

    SciTech Connect

    Nashat, A.H.; Ferrari, M. [Univ. of California, Berkeley, CA (United States)] [Univ. of California, Berkeley, CA (United States); Moronne, M. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States)

    1998-10-20

    Fluorescence confocal microscopy was used to characterize micron-sized microfabricated silicon particles and planar oxides surfaces after silanization and immobilization of IgG antibody. Surfaces treated with amino- and mercaptosilanes were tested by the presence of amine and sulfhydryl groups by labeling with specific fluorescein probes. In addition, human antibody (IgG) was immobilized to the thiol-coated microparticles using the heterobifunctional crosslinker succinimidyl 4-(N-maleimidolmthyl)-cyclohexane-1-carboxylate. Estimates of the surface density of IgG were consistent with 8.3% of a monolayer of covalently-bound antibody. Confocal images confirmed uniform layers of both silanes and antibodies on the microparticles. The sensitivity limit for the confocal measurements was determined to be as low as 1.5 x 10{sup {minus}5} fluors per nm{sup 2}.

  20. First principles investigations on the electronic structure of anchor groups on ZnO nanowires and surfaces

    SciTech Connect

    Dominguez, A.; Lorke, M.; Rosa, A. L.; Frauenheim, Th. [BCCMS, Universität Bremen, Am Fallturm 1, 28359 Bremen (Germany); Schoenhalz, A. L.; Dalpian, G. M. [CCNH, Universidade Federal do ABC, Av. dos Estados 5001, Santo André (Brazil); Rocha, A. R. [IFT, Universidade Estadual Paulista, R. Dr. Bento Teobaldo Ferraz, 271, São Paulo (Brazil)

    2014-05-28

    We report on density functional theory investigations of the electronic properties of monofunctional ligands adsorbed on ZnO-(1010) surfaces and ZnO nanowires using semi-local and hybrid exchange-correlation functionals. We consider three anchor groups, namely thiol, amino, and carboxyl groups. Our results indicate that neither the carboxyl nor the amino group modify the transport and conductivity properties of ZnO. In contrast, the modification of the ZnO surface and nanostructure with thiol leads to insertion of molecular states in the band gap, thus suggesting that functionalization with this moiety may customize the optical properties of ZnO nanomaterials.

  1. [Carboxylation enzymes of coryneform bacteria].

    PubMed

    Baryshnikova, L M; Loginova, N V

    1979-01-01

    The enzymes of carbon dioxide heterotrophic fixation were studied in six strains of coryneform bacteria belonging to the genera Arthrobacter, Brevibacterium, Corynebacterium and Nocardia. All of the strains were found to contain PEP (phosphoenolpyruvate) carboxylase (EC 4.1.1.31), NADP or NAD dependent malic enzymes (EC 1.1.1.38--40). Pyruvate carboxylase (EC 6.4.1.1) was found only in three strains of coryneforms: Brevibacterium ammoniagenes, Corynebacterium aquaticum and Nocardia erythropolis. PEP carboxykinase (EC 4.1.1.32) was detected in Brevibacterium ammoniagenes and Nocardia erythropolis. PEP carboxytransphosphorylase (EC 4.1.1.38) was found only in Brevibacterium ammoniagenes. These data suggest that carboxylation of C3-acids is one of the essential pathways in some coryneforms supplying the citric acid cycle with the products of glycolysis. The composition and the level of carboxylation enzymes reflect the ecological characteristics of the organisms rather than their taxonomical relations. PMID:119147

  2. Di-?-aqua-bis­[aqua­(5-carboxyl­ato-1H-1,2,3-triazole-4-carb­oxy­lic acid-?2 N 3,O 4)lithium

    PubMed Central

    Starosta, Wojciech; Leciejewicz, Janusz

    2013-01-01

    The crystal structure of the title compound, [Li2(C4H2N3O4)2(H2O)4], contains centrosymmetric dinuclear mol­ecules in which two LiI ions are bridged by two water O atoms. The metal ion is coordinated by one N,O-bidentate ligand and three water O atoms (one of them is symmetry generated), with one of the bridging water O atoms in the apical position of a distorted square pyramid. The carboxyl­ate group that participates in coordination to the metal ion remains protonated; the other is deprotonated and coordination inactive. An intra­molecular O—H?O hydrogen bond between carboxyl­ate groups is observed. In the crystal, dimers are linked by O—H?O, O—H?N and N—H?O hydrogen bonds, generating a three-dimensional network. PMID:24427005

  3. "Choose-a-size" approach in dynamic combinatorial chemistry: a single substrate dynamic combinatorial library of oligomacrocycles that adapts to the size and shape of carboxylates.

    PubMed

    Ulatowski, Filip; Sadowska-Kuzio?a, Agnieszka; Jurczak, Janusz

    2014-10-17

    A neutral anion binding receptor based on dipicolinic acid diamide was equipped with thiol groups in the amidic side arms. After the thiol was oxidized to disulfide groups with I2, a mixture of cyclic oligomers (a library) was obtained. The distribution of macrocycles can be controlled kinetically during the oxidation process or thermodynamically at basic conditions via disulfide bond exchange. The library proved to be very sensitive to templation with various carboxylates in DMSO. The amplification pattern reflects the structural features of the anionic template and is sensitive to changes in the template's geometry. The application of carboxylates with multiple functional groups resulted in very strong amplification of the large penta- and hexameric macrocycles. The thermodynamic parameters of some templation effects were rationalized using a simple model and confirmed using competitive NMR titration. PMID:25280250

  4. Functional volumes modeling: Scaling for group size in averaged images

    Microsoft Academic Search

    Peter T. Fox; Aileen Y. Huang; Lawrence M. Parsons; Jin-Hu Xiong; Lacey Rainey; Jack L. Lancaster

    1999-01-01

    Functional volumes modeling (FVM) is a statistical construct for metanalytic modeling of the locations of brain functional areas as spatial probability distributions. FV models have a variety of applications, in particular, to serve as spatially explicit predictions of the Talairach-space locations of functional activations, thereby allowing voxel-based analyses to be hypothesis testing rather than hypothesis generating. As image averaging is

  5. IRAG Working Group 3: Cell function-based assays

    Microsoft Academic Search

    P. Botham; R. Osborne; K. Atkinson; G. Carr; M. Cottin; R. G. Van Buskirk

    1997-01-01

    Cell function-based tests measure responses of cells at sublytic concentrations of test agents. The fluorescein leakage assay measures effects of substances on the barrier function of epithelial monolayers or multilayers (MDCK or NHEK cells) as in vitro models of corneal epithelial function. Two IRAG data submissions suggest that the fluorescein leakage assay shows promise as a screening test for surfactants

  6. Catalytic Thiol and Carboxylate: Role of Cysteine and Glutamic Acid in the Xylosidic Activity of Endoxylanase from Chainiasp. (NCL 82-5-1)

    Microsoft Academic Search

    S. Hegde Subray; R. Kumar Ameeta; N. Ganesh Krishna; Islam M. Khan

    1998-01-01

    Chemical modification of the endoxylanase fromChainiasp. with group-specific chemical modifiers in the absence and presence of substrate and kinetics of modification revealed the involvement of a thiol and a carboxylate in the catalytic function of the enzyme. The active-site peptides were chemically labeled and sequenced. The sequence alignment of the chemically labeled peptide with other family G\\/11 xylanases showed that

  7. Application of palladium-catalyzed carboxyl anhydride-boronic acid cross coupling in the synthesis of novel bile acids analogs with modified side chains.

    PubMed

    Mayorquín-Torres, Martha C; Flores-Álamo, Marcos; Iglesias-Arteaga, Martin A

    2015-09-01

    Palladium-catalyzed cross coupling of 4-methoxycarbonyl phenyboronic acid with acetylated bile acids in which the carboxyl functions was activated by formation of a mixed anhydride with pivalic anhydride afforded the cross coupled compounds, which were converted in novel side chain modified bile acids by one pot carbonyl reduction/removal of the protecting acetyl groups by Wolff-Kishner reduction. Unambiguous assignments of the NMR signals and crystal characterization of the heretofore unknown compounds are provided. PMID:26048448

  8. Polymerization process for carboxyl containing polymers utilizing oil soluble ionic surface active agents

    SciTech Connect

    Uebele, C.E.; Ball, L.E.; Jorkasky, R.J. II; Wardlow, E. Jr.

    1987-09-08

    This patent describes a method for polymerizing olefinically unsaturated carboxylic acid monomers containing at least one activated carbon to carbon olefinic double bond and at least one carboxyl group. The monomers are polymerized in an organic media consisting essentially of organic liquids, in the presence of free radical forming catalysts and at least one oil soluble ionic surface active agent selected from the group consisting of: (a) anionic surface active agents; (b) cationic surface active agents; and (c) amphoteric surface active agents.

  9. Defining functional groups based on running kinematics using Self-Organizing Maps and Support Vector Machines.

    PubMed

    Hoerzer, Stefan; von Tscharner, Vinzenz; Jacob, Christian; Nigg, Benno M

    2015-07-16

    A functional group is a collection of individuals who react in a similar way to a specific intervention/product such as a sport shoe. Matching footwear features to a functional group can possibly enhance footwear-related comfort, improve running performance, and decrease the risk of movement-related injuries. To match footwear features to a functional group, one has to first define the different groups using their distinctive movement patterns. Therefore, the main objective of this study was to propose and apply a methodological approach to define functional groups with different movement patterns using Self-Organizing Maps and Support Vector Machines. Further study objectives were to identify differences in age, gender and footwear-related comfort preferences between the functional groups. Kinematic data and subjective comfort preferences of 88 subjects (16-76 years; 45 m/43 f) were analysed. Eight functional groups with distinctive movement patterns were defined. The findings revealed that most of the groups differed in age or gender. Certain functional groups differed in their comfort preferences and, therefore, had group-specific footwear requirements to enhance footwear-related comfort. Some of the groups, which had group-specific footwear requirements, did not show any differences in age or gender. This is important because when defining functional groups simply using common grouping criteria like age or gender, certain functional groups with group-specific movement patterns and footwear requirements might not be detected. This emphasises the power of the proposed pattern recognition approach to automatically define groups by their distinctive movement patterns in order to be able to address their group-specific product requirements. PMID:25869722

  10. When does the in-group like the out-group? Bias among children as a function of group norms.

    PubMed

    Rutland, Adam; Hitti, Aline; Mulvey, Kelly Lynn; Abrams, Dominic; Killen, Melanie

    2015-06-01

    Research indicates that in-group favoritism is prevalent among both adults and children. Although research has documented that individuals do not consistently display an in-group bias, the conditions under which out-group preference exists are not well understood. In this study, participants (N = 462) aged 9 to 16 years judged in-group deviant acts that were either in line with or counter to a generic norm shared by both groups. The findings demonstrated, for the first time, that children preferred out-group over in-group deviance only when the in-group peer's deviance was in line with the generic norm and a threat to their group's identity. Participants justified their disapproval of these deviants by focusing on the need for group cohesion and loyalty, while they signified their approval by spotlighting the need for autonomy. Our findings suggest that children's intergroup attitudes are influenced by how the behavior of their peers matches different levels of group norms. PMID:25888686

  11. Children's Ideas about Group Functioning: A Socio-developmental Perspective.

    ERIC Educational Resources Information Center

    Garnier, Catherine; Cucumel, Guy

    1997-01-01

    Questioned day care center children during free play about their collective activity to determine how the representation of cooperation is structured and what kind of transformation appears during development. Found a developmental trend of representation of group activity after age 2. Results highlight the importance of group and day care center…

  12. Structural basis for low-affinity binding of non-R2 carboxylate-substituted tricyclic quinoline analogs to CK2?: comparative molecular dynamics simulation studies.

    PubMed

    Zhou, Yue; Li, Xitao; Zhang, Na; Zhong, Rugang

    2015-02-01

    Protein kinase CK2 is a novel potential target for cancer treatment. The tricyclic quinoline compound CX-4945 (R2 = COOH) is the first bioavailable CK2 inhibitor used in human clinical trials for advanced solid tumors. CX-4945 analogs with non-R2 carboxylate function were demonstrated to be approximately 5000-fold less potent than compound 12 (R2 = COOH) in vitro. Molecular docking and molecular dynamics simulations were employed to elucidate the structural mechanisms through which the R2 non-ionizable and R3 carboxylic acid substituents influence binding affinity. Results show that the structure of CK2? and the orientation of ligands changed to different degrees in non-R2 carboxylate function systems. The inappropriate electrostatic interactions between the non-R2 carboxylate group and the positive region lead to improper protein-ligand recognition, which is followed by the reorientation of tricyclic skeletons. For CK2?, the affected positions are distributed over the glycine-rich loop (G-loop), C-loop, and the ?4/?5 loop. The allosteric mechanisms between the deviated ligands and the changed regions are proposed. Detailed energy calculation and residue-based energy decomposition indicate the energetic influences on the contributions of the critical residues. These results are in accordance with one another and could provide rational clues to the design of more potent CK2 inhibitors. PMID:24903887

  13. Hydrolysis of organonitrate functional groups in aerosol particles

    SciTech Connect

    Liu, Shang; Shilling, John E.; Song, Chen; Hiranuma, Naruki; Zaveri, Rahul A.; Russell, Lynn M.

    2012-10-19

    Organonitrate (ON) groups are important substituents in secondary organic aerosols. Model simulations and laboratory studies indicate a large fraction of ON groups in aerosol particles, but much lower quantities are observed in the atmosphere. Hydrolysis of ON groups in aerosol particles has been proposed recently. To test this hypothesis, we simulated formation of ON molecules in a reaction chamber under a wide range of relative humidity (0% to 90%). The mass fraction of ON groups (5% to 20% for high-NOx experiments) consistently decreased with increasing relative humidity, which was best explained by hydrolysis of ON groups at a rate of 4 day-1 (lifetime of 6 hours) for reactions under relative humidity greater than 20%. In addition, we found that secondary nitrogen-containing molecules absorb light, with greater absorption under dry and high-NOx conditions. This work provides the first evidence for particle-phase hydrolysis of ON groups, a process that could substantially reduce ON group concentration in the atmosphere.

  14. Automorphism group of the set of all bent functions Natalia N. Tokareva 1

    E-print Network

    Automorphism group of the set of all bent functions Natalia N. Tokareva 1 Sobolev Institute@math.nsc.ru Abstract. Boolean function in even number of variables is called bent if it is at the maximal possible mapping of the set of all Boolean functions into itself that transforms bent functions into bent functions

  15. Automorphism group of the set of all bent functions Natalia N. Tokareva 1

    E-print Network

    Automorphism group of the set of all bent functions Natalia N. Tokareva 1 Sobolev Institute@math.nsc.ru Abstract. Boolean function in even number of variables is called bent if it is at the maximal possible of the set of all Boolean functions into itself that transforms bent functions into bent functions

  16. Effect of carboxylic acid of periodic mesoporous organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems

    NASA Astrophysics Data System (ADS)

    Dutta, Saikat; Kao, Hsien-Ming; Wu, Kevin C.-W.

    2014-11-01

    This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (-COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and 13C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed.

  17. Lysine Carboxylation in Proteins: OXA-10 -Lactamase Jason B. Cross,1

    E-print Network

    Schlegel, H. Bernhard

    -base chemistry, in expan- sion of function beyond those of the 20 standard amino acids. In this study, the ONIOM; ONIOM QM/MM method; density func- tional calculations INTRODUCTION Carboxylated lysine residues have

  18. An ab initio density functional study of the optical functions of 9-Methyl-3-Thiophen-2-YI-Thieno [3,2e] [1,2,4] Thriazolo [4,3c] Pyrimidine-8-Carboxylic Acid Ethyl Ester crystals

    NASA Astrophysics Data System (ADS)

    Reshak, Ali H.; Kityk, I. V.; Khenata, R.; Al-Douri, Y.; Auluck, S.

    An ab initio investigation of the optical constants of 9-Methyl-3-Thiophen-2-YI-Thieno [3,2e] [1,2,4] Thriazolo [4,3c] Pyrimidine-8-Carboxylic Acid Ethyl Ester crystal is performed within a framework of local density approximation (LDA), and the Engel-Vosko generalized gradient approximation (EV-GGA) exchange correlation potentials. It is established that there are two independent molecules (A and B) exhibiting different intra-molecular interactions: C-H⋯O (A) and C-H⋯N (B). These intra-molecular interactions favor stabilization of the crystal structure for molecules A and B. It should be emphasized that there exist remarkable ?-? interactions between the pyrimidine rings of the two neighbors B molecules giving extra strengths and stabilizations to the superamolecular structure. These different intra-molecular interactions C-H⋯O (A) and C-H⋯N (B) and the ?-? interaction between the pyrimidine rings of the two neighbors B molecules give principal contribution to dispersion of optical properties. With a view to seek deeper insight into the electronic structure, the optical properties were investigated. Our calculations show that the optical constants are very anisotropic. The EVGGA calculation shows a blue spectral shift of around 0.024 eV with significant changes in the spectra compared to the LDA calculation. The observed spectral shifts are in agreement with the calculated band structure and corresponding electron density of states.

  19. Dual-functional biomimetic materials: nonfouling poly(carboxybetaine) with active functional groups for protein immobilization.

    PubMed

    Zhang, Zheng; Chen, Shengfu; Jiang, Shaoyi

    2006-12-01

    We introduce a dual-functional biocompatible material based on zwitterionic poly(carboxybetaine methacrylate) (polyCBMA), which not only highly resists protein adsorption/cell adhesion, but also has abundant functional groups convenient for the immobilization of biological ligands, such as proteins. The dual-functional properties are unique to carboxybetaine moieties and are not found in other nonfouling moieties such as ethylene glycol, phosphobetaine, and sulfobetaine. The unique properties are demonstrated in this work by grafting a polyCBMA polymer onto a surface or by preparing a polyCBMA-based hydrogel. PolyCBMA brushes with a thickness of 10-15 nm were grafted on a gold surface using the surface-initiated atom transfer radical polymerization method. Protein adsorption was analyzed using a surface plasmon resonance sensor. The surface grafted with polyCBMA very largely prevented the nonspecific adsorption of three test proteins, that is, fibrinogen, lysozyme, and human chorionic gonadotropin (hCG). The immobilization of anti-hCG on the surface resulted in the specific binding of hCG while maintaining a high resistance to nonspecific protein adsorption. Transparent polyCBMA-based hydrogel disks were decorated with immobilized fibronectin. Aortic endothelial cells did not bind to the polyCBMA controls, but appeared to adhere well and spread on the fibronectin-modified surface. With their dual functionality and biomimetic nature, polyCBMA-based materials are very promising for their applications in medical diagnostics, biomaterials/tissue engineering, and drug delivery. PMID:17154457

  20. Solvent extraction of rare-earth metals by carboxylic acids

    SciTech Connect

    Preez, A.C. du; Preston, J.S. [Mintek, Randburg (South Africa)

    1992-04-01

    The solvent extraction of the trivalent lanthanides and yttrium from nitrate media by solutions of carboxylic acids in xylene has been studied. Commercially available carboxylic acids such as Versatic 10 and naphthenic acids were used, as well as model compounds of known structure, such as 2-ethylhexanoic and 3-cyclohexylpropanoic acids. In a few cases, extraction of the metals from sulphate and chloride solutions was also investigated. The dependence of the extraction properties of the carboxylic acids on the atomic number of the lanthanide shows a definite relationship to the steric bulk of the carboxylic acid molecule quantified by means of the steric parameter, E{sub s}{prime} of the substituent alkyl group. The stoichiometries of the extracted complexes for representative light (La), middle (Gd) and heavy (Lu) rare-earth metals were investigated by the slope-analysis technique for a sterically hindered acid (Versatic 10 acid; -E{prime}{sub s} = 3.83) and an acid with low steric hindrance (3-cyclohexylpropanoic acid; -E{prime}{sub s} = 0.28). 14 refs., 13 figs., 3 tabs.

  1. GROUP SPARSITY WITH OVERLAPPING PARTITION FUNCTIONS Gabriel Peyre1

    E-print Network

    Paris-Sud XI, Université de

    by Donoho and Johnstone on thresholding operators in orthogonal bases for denoising [19]. Sparsity and inverse problems in- volving natural images. Indeed, wavelet coefficients of im- ages are not only sparse.Fadili@greyc.ensicaen.fr ABSTRACT This paper introduces a novel and versatile group sparsity prior for denoising and to regularize

  2. Continuity of a percolation function on the hierarchical group

    E-print Network

    for Cyber Security, University of Texas at San Antonio San Antonio, Texas 78249, USA 2 SUTD, · · · , # # i=1 x i metric d on it: d(x, y) = # # # 0, x = y, max{i : x i #= y i }, x to their most recent common ancestor. Figure 1 shows the group# 2 along with its metric generating tree

  3. Alpha-hydroxyacids and carboxylic acids.

    PubMed

    Yu, Ruey J; Van Scott, Eugene J

    2004-04-01

    The carboxylic acids include alpha-hydroxyacids (AHAs), polyhydroxy acids (PHAs), aldobionic acids (ABAs), retinoic acid, vitamin C and azelaic acid. They all have therapeutic actions. AHAs, PHAs and ABAs are organic hydroxyacids, a group of natural and physiological substances which can modulate skin keratinization and increase biosynthesis of dermal components. Because of these effects, AHAs, PHAs and ABAs are therapeutically effective or beneficial for topical treatment of dry skin, rough skin, acne, rosacea, warts, eczema, psoriasis and skin changes associated with ageing, including wrinkles and photoageing. In addition, PHAs and ABAs, which are antioxidants, are topically beneficial for sensitive or diseased skin and for the prevention of oxidative damage caused by UV radiation. The vitamin A derivatives, known as retinoids, include three that are found physiologically. Retinoic acid is the most potent of these in promoting proliferation and differentiation of epithelial cells, and in stimulating biosynthesis of collagen I and III. Because of these actions, retinoic acid is therapeutically effective for topical treatment of acne, actinic keratoses and photoaged skin. Vitamin C, which is l-ascorbic acid and a lactone form of 3-keto-polyhydroxy acid, is a water-soluble antioxidant. Because of this property vitamin C has been promoted for topical prevention of skin damage caused by UV radiation. Azelaic acid has been shown to normalize keratinization in the follicular infundibulum, exert an antibacterial effect against Propionibacterium acnes and inhibit melanogenesis and so has been used for topical treatment of acne and melasma. The carboxylic acids display similarities and differences in their topical actions and therapeutic applications. PMID:17147560

  4. Constructing Vectorial Boolean Functions with High Algebraic Immunity Based on Group

    E-print Network

    , algebraic immu- nity, balancedness, algebraic degree, hyper-bent functions. 1 Introduction Boolean functions two special classes of such kind of Boolean functions: one is hyper-bent and the other is balancedConstructing Vectorial Boolean Functions with High Algebraic Immunity Based on Group Decomposition

  5. Functional Groups Based on Leaf Physiology: Are they Spatially and Temporally Robust?

    NASA Technical Reports Server (NTRS)

    Foster, Tammy E.; Brooks, J. Renee; Quincy, Charles (Technical Monitor)

    2002-01-01

    The functional grouping hypothesis, which suggests that complexity in function can be simplified by grouping species with similar responses, was tested in the Florida scrub habitat. Functional groups were identified based on how species in fire maintained FL scrub function in terms of carbon, water and nitrogen dynamics. The suite of physiologic parameters measured to determine function included both instantaneous gas exchange measurements obtained from photosynthetic light response curves and integrated measures of function. Using cluster analysis, five distinct physiologically-based functional groups were identified. Using non-parametric multivariate analyses, it was determined that these five groupings were not altered by plot differences or by the three different management regimes; prescribed burn, mechanically treated and burn, and fire-suppressed. The physiological groupings also remained robust between the two years 1999 and 2000. In order for these groupings to be of use for scaling ecosystem processes, there needs to be an easy-to-measure morphological indicator of function. Life form classifications were able to depict the physiological groupings more adequately than either specific leaf area or leaf thickness. THe ability of life forms to depict the groupings was improved by separating the parasitic Ximenia americana from the shrub category.

  6. Effects of Oxygen-Containing Functional Groups on Supercapacitor Performance

    SciTech Connect

    Kerisit, Sebastien N.; Schwenzer, Birgit; Vijayakumar, M.

    2014-07-03

    Molecular dynamics (MD) simulations of the interface between graphene and the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIM OTf) were carried out to gain molecular-level insights into the performance of graphene-based supercapacitors and, in particular, determine the effects of the presence of oxygen-containing defects at the graphene surface on their integral capacitance. The MD simulations predict that increasing the surface coverage of hydroxyl groups negatively affects the integral capacitance, whereas the effect of the presence of epoxy groups is much less significant. The calculated variations in capacitance are found to be directly correlated to the interfacial structure. Indeed, hydrogen bonding between hydroxyl groups and SO3 anion moieties prevents BMIM+ and OTf- molecules from interacting favorably in the dense interfacial layer and restrains the orientation and mobility of OTf- ions, thereby reducing the permittivity of the ionic liquid at the interface. The results of the molecular simulations can facilitate the rational design of electrode materials for supercapacitors.

  7. SPACES OF BOUNDED SPHERICAL FUNCTIONS ON HEISENBERG GROUPS: PART I

    E-print Network

    Benson, Chal

    L 1 K (N) of integrable K­invariant functions on N is commutative. In this case the spectrum ( · )(z) = ( 1 · z), is multiplicit ree . The papers 1 and 1 classi all such multiplicit ree actions uirement that a multiplicit ree action V be well­behaved is made precise in efinition . below. Here

  8. Reactivities of amine functions grafted to carbon fiber surfaces by tetraethylenepentamine. Designing interfacial bonding

    Microsoft Academic Search

    C. U. Pittman; Z. Wu; W. Jiang; G.-R. He; B. Wu; W. Li; S. D. Gardner

    1997-01-01

    PAN-base carbon fibers were oxidized with 70% nitric acid at 115 °C to introduce surface carboxyl, hydroxyl and other oxygenated functions. Subsequent reactions of these surfaces at 190–200 °C with tetraethylenepentamine (TEPA) generated amide bonds at carboxyl and ester sites thereby grafting TEPA and introducing primary and secondary amine groups onto the fiber surfaces. The reactivity of these surface-bound amine

  9. Crystal structure of ethyl 2-(3,5-di­fluoro­phen­yl)quinoline-4-carboxyl­ate

    PubMed Central

    Sunitha, V. M.; Naveen, S.; Manjunath, H. R.; Benaka Prasad, S. B.; Manivannan, V.; Lokanath, N. K.

    2015-01-01

    In the title compound, C18H13F2NO2, the two rings of the quinoline system are fused almost coaxially, with a dihedral angle between their planes of 2.28?(8)°. The plane of the attached benzene ring is inclined to the plane of the quinoline system by 7.65?(7)°. The carboxyl­ate group attached to the quinoline system is in an anti­periplanar conformation. There is a short intra­molecular C—H?O contact involving the carbonyl group. In the crystal, mol­ecules are linked via C—H?O hydrogen bonds, forming chains lying in the (1-10) plane. PMID:25995938

  10. Crystal structure of ethyl 2-(3,5-di-fluoro-phen-yl)quinoline-4-carboxyl-ate.

    PubMed

    Sunitha, V M; Naveen, S; Manjunath, H R; Benaka Prasad, S B; Manivannan, V; Lokanath, N K

    2015-05-01

    In the title compound, C18H13F2NO2, the two rings of the quinoline system are fused almost coaxially, with a dihedral angle between their planes of 2.28?(8)°. The plane of the attached benzene ring is inclined to the plane of the quinoline system by 7.65?(7)°. The carboxyl-ate group attached to the quinoline system is in an anti-periplanar conformation. There is a short intra-molecular C-H?O contact involving the carbonyl group. In the crystal, mol-ecules are linked via C-H?O hydrogen bonds, forming chains lying in the (1-10) plane. PMID:25995938

  11. Recovery of carboxylic acids produced by fermentation.

    PubMed

    López-Garzón, Camilo S; Straathof, Adrie J J

    2014-01-01

    Carboxylic acids such as citric, lactic, succinic and itaconic acids are useful products and are obtained on large scale by fermentation. This review describes the options for recovering these and other fermentative carboxylic acids. After cell removal, often a primary recovery step is performed, using liquid-liquid extraction, adsorption, precipitation or conventional electrodialysis. If the carboxylate is formed rather than the carboxylic acid, the recovery process involves a step for removing the cation of the formed carboxylate. Then, bipolar electrodialysis and thermal methods for salt splitting can prevent that waste inorganic salts are co-produced. Final carboxylic acid purification requires either distillation or crystallization, usually involving evaporation of water. Process steps can often be combined synergistically. In-situ removal of carboxylic acid by extraction during fermentation is the most popular approach. Recovery of the extractant can easily lead to waste inorganic salt formation, which counteracts the advantage of the in-situ removal. For industrial production, various recovery principles and configurations are used, because the fermentation conditions and physical properties of specific carboxylic acids differ. PMID:24751382

  12. Ethane-1,2-diyl bis­(pyridine-3-car­box­ylate)

    PubMed Central

    Brito, Iván; Vallejos, Javier; López-Rodríguez, Matías; Cárdenas, Alejandro

    2010-01-01

    The title compound, C14H12N2O4, has twofold imposed crystallographic symmetry in the solid state. The asymmetric unit contains one half-mol­ecule. An intra­molecular C—H?O hydrogen bond is formed between the carboxyl­ate O group and one H atom of the aromatic ring such that a five-membered ring is formed. The angle between the planes of symmetry-related aromatic rings is 44.71?(19)°. PMID:21580003

  13. Decomposition mechanism of the tert-butyl esters of carboxylic acids

    Microsoft Academic Search

    V. G. Avakyan; A. D. Litmanovich; V. O. Cherkezyan

    1984-01-01

    1.It has been shown by quantum-chemical calculations that the monomolecular decomposition of tert-butyl esters ot carboxylic acids, which involves the detachment of isobutylene, takes place as the result of the transfer of a proton from the closest CH3 group of the tert-butyl substituent to the carbonyl O atom.2.The catalytic action of carboxylic acids on this reaction is exhibited by the

  14. Ketone Production from the Thermal Decomposition of Carboxylate Salts

    E-print Network

    Landoll, Michael 1984-

    2012-08-15

    The MixAlco process uses an anaerobic, mixed-culture fermentation to convert lignocellulosic biomass to carboxylate salts. The fermentation broth must be clarified so that only carboxylate salts, water, and minimal impurities remain. Carboxylate...

  15. Psychosocial functioning in patients with treatment-resistant depression after group cognitive behavioral therapy

    Microsoft Academic Search

    Miki Matsunaga; Yasumasa Okamoto; Shin-ichi Suzuki; Akiko Kinoshita; Shinpei Yoshimura; Atsuo Yoshino; Yoshihiko Kunisato; Shigeto Yamawaki

    2010-01-01

    BACKGROUND: Although patients with Treatment Resistant Depression (TRD) often have impaired social functioning, few studies have investigated the effectiveness of psychosocial treatment for these patients. We examined whether adding group cognitive behavioral therapy (group-CBT) to medication would improve both the depressive symptoms and the social functioning of patient with mild TRD, and whether any improvements would be maintained over one

  16. Plant parameters for plant functional groups of western rangelands to enable process-based simulation modeling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Regional environmental assessments with process-based models require realistic estimates of plant parameters for the primary plant functional groups in the region. “Functional group” in this context is an operational term, based on similarities in plant type and in plant parameter values. Likewise...

  17. Synthesis of porous carbon fibers with strong anion exchange functional groups.

    PubMed

    Zheng, Weihua; Hu, Jingtian; Han, Zheshen; Wang, Zixing; Zheng, Zhen; Langer, James; Economy, James

    2015-06-01

    Hybrid porous carbon fibers with strong anion-exchangeable functional groups (HACAX) were synthesized by alkylation of pyrolyzed polyacrylonitrile. HACAX exhibits generic stable positively charged functional groups. This expands the applications of porous carbon media for interacting with anions without adjusting pH, such as Cr(vi) adsorption at natural pH. PMID:25990389

  18. Functional group and species responses to spring precipitation in three semi-arid rangeland ecosystems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determining if precipitation-induced changes to forage production and basal and foliar cover in semi-arid rangelands are species-specific, functional group-specific or ubiquitous across species and functional groups will enhance decision making among producers and increase precision of forage produc...

  19. Development of acid functional groups during the thermal degradation of wood and wood components

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study provides data on acid functional groups in charcoals and how the acid functional group content varies with the formation conditions. Chars were created from purified cellulose, purified lignin, pine wood, and pine bark. The charring temperatures and charring duration were controlled in a ...

  20. Detection of low concentration oxygen containing functional groups on activated carbon fiber surfaces through fluorescent labeling

    E-print Network

    Borguet, Eric

    carbon, activated carbon fibers and carbon nano- tubes, are based on the presence of oxygen containingDetection of low concentration oxygen containing functional groups on activated carbon fiber of surface functional groups (OH, COOH and CHO) on activated carbon fiber surfaces. The chromophores were

  1. THE SPHERICAL TRANSFORM OF A SCHWARTZ FUNCTION ON THE HEISENBERG GROUP

    E-print Network

    Benson, Chal

    THE SPHERICAL TRANSFORM OF A SCHWARTZ FUNCTION ON THE HEISENBERG GROUP CHAL BENSON, JOE JENKINS the Heisenberg group Hn = V Ã? R with group law (z, t)(z , t ) = z + z , t + t - 1 2 Im z, z . 1991 Mathematics of the National Science Foundation. 1 #12;2 C. BENSON, J. JENKINS, AND G. RATCLIFF In order to present explicit

  2. An Improved Particle Swarm Optimization Algorithm Mimicking Territorial Dispute Between Groups for Multimodal Function Optimization Problems

    Microsoft Academic Search

    Jang-Ho Seo; Chang-Hwan Im; Sang-Yeop Kwak; Cheol-Gyun Lee; Hyun-Kyo Jung

    2008-01-01

    In the present paper, an improved particle swarm optimization (PSO) algorithm for multimodal function optimization is proposed. The new algorithm, named auto-tuning multigrouped PSO (AT-MGPSO) algorithm mimics natural phenomena in ecosystem such as territorial dispute between different group members and immigration of weak groups, resulting in automatic determination of the size of each group's territory and robust convergence. The usefulness

  3. Remarks on the star product of functions on finite and compact groups

    E-print Network

    Aniello, P; Man'ko, V; Marmo, G; 10.1016/j.physleta.2008.11.047

    2009-01-01

    Using the formalism of quantizers and dequantizers, we show that the characters of irreducible unitary representations of finite and compact groups provide kernels for star products of complex-valued functions of the group elements. Examples of permutation groups of two and three elements, as well as the SU(2) group, are considered. The k-deformed star products of functions on finite and compact groups are presented. The explicit form of the quantizers and dequantizers, and the duality symmetry of the considered star products are discussed.

  4. Biogeographical Boundaries, Functional Group Structure and Diversity of Rocky Shore Communities along the Argentinean Coast

    PubMed Central

    Wieters, Evie A.; McQuaid, Christopher; Palomo, Gabriela; Pappalardo, Paula; Navarrete, Sergio A.

    2012-01-01

    We investigate the extent to which functional structure and spatial variability of intertidal communities coincide with major biogeographical boundaries, areas where extensive compositional changes in the biota are observed over a limited geographic extension. We then investigate whether spatial variation in the biomass of functional groups, over geographic (10?s km) and local (10?s m) scales, could be associated to species diversity within and among these groups. Functional community structure expressed as abundance (density, cover and biomass) and composition of major functional groups was quantified through field surveys at 20 rocky intertidal shores spanning six degrees of latitude along the southwest Atlantic coast of Argentina and extending across the boundaries between the Argentinean and Magellanic Provinces. Patterns of abundance of individual functional groups were not uniformly matched with biogeographical regions. Only ephemeral algae showed an abrupt geographical discontinuity coincident with changes in biogeographic boundaries, and this was limited to the mid intertidal zone. We identified 3–4 main ‘groups’ of sites in terms of the total and relative abundance of the major functional groups, but these did not coincide with biogeographical boundaries, nor did they follow latitudinal arrangement. Thus, processes that determine the functional structure of these intertidal communities are insensitive to biogeographical boundaries. Over both geographical and local spatial scales, and for most functional groups and tidal levels, increases in species richness within the functional group was significantly associated to increased total biomass and reduced spatial variability of the group. These results suggest that species belonging to the same functional group are sufficiently uncorrelated over space (i.e. metres and site-to-site ) to stabilize patterns of biomass variability and, in this manner, provide a buffer, or “insurance”, against spatial variability in environmental conditions. PMID:23166756

  5. Simple approach to carboxyl-rich materials through low-temperature heat treatment of hydrothermal carbon in air

    NASA Astrophysics Data System (ADS)

    Chen, Zhen; Ma, Lijian; Li, Shuqiong; Geng, Junxia; Song, Qiang; Liu, Jun; Wang, Chunli; Wang, Hang; Li, Juan; Qin, Zhi; Li, Shoujian

    2011-08-01

    It was found that a large number of oxygen-containing functional groups (OFGs) could be created on the surface of hydrothermal carbon (HTC) by simply heating at lower temperature in air during the course of our preliminary experiments which focused on oxidation pre-treatment of pristine HTC for the purpose of grafting functionalization. Especially carboxyl groups on HTC would increase significantly, from 0.53 to 3.70 mmol/g after heat treatment at 300 °C. So, effects of heat-treatment on the OFGs on the carbon microsphere were deeply studied to confirm and explain the findings. Experiments involving different materials (HTC, activated carbon and glucose) were performed under varying conditions (heating temperature and time, in air or in Ar atmosphere). A reaction mechanism for newly generating carboxyl groups on HTC surface during heat-treatment process was supposed based on the results from the sample characterization using Boehm titrations, infrared spectra, X-ray photoelectron spectroscopy, energy dispersive spectrometry and elemental analysis. In addition, the as heat-treated product has excellent sorption capability for Pb 2+ and Cd 2+ ions.

  6. Purification and characterization of a pyrrole-2-carboxylate oxygenase from Arthrobacter strain Py1.

    PubMed

    Hormann, K; Andreesen, J R

    1994-03-01

    Pyrrole-2-carboxylate oxygenase was purified 8.2-fold to homogeneity from Arthrobacter strain Py1 grown on pyrrole-2-carboxylate as sole carbon, nitrogen, and energy source. FAD and dithioerythritol had to be present during the purification procedure to stabilize the enzyme activity. The molecular mass of the pyrrole-2-carboxylate oxygenase was about 160 kDa by gel filtration chromatography and native gradient PAGE, only one polypeptide of about 60 kDa was present after SDS-PAGE. The FAD content was 2.7 to 3.6 mol FAD per enzyme (160 kDa). The non-covalently bound FAD of the pyrrole-2-carboxylate oxygenase was reduced by NADH and reoxidized by oxygen and pyrrole-2-carboxylate. The enzyme exhibited a narrow substrate specificity. Besides pyrrole-2-carboxylate, only pyrrole, pyrrole-2-aldehyde, and indole-2-carboxylate stimulated the oxygen consumption at a very low rate. The enzyme activity was strongly reduced by different sulfhydryl group inhibitors, but it could be restored by 2-mercaptoethanol or dithiothreitol. The content of pyrrole-2-carboxylate oxygenase was about 6% of the soluble protein as determined by antibodies raised against the enzyme. No cross reacting material was present in other bacteria also able to degrade pyrrole-2-carboxylate. A low amount of the enzyme was present in uninduced cells of Arthrobacter strain Py1, although the enzymatic activity was below the detection limit. The N-terminal amino acid sequence of the enzyme did not contain the consensus sequence GXGXXG found to be present close to the N-terminus of many flavin-dependent monoxygenases sequenced so far. PMID:8011178

  7. RADON TRANSFORM ON SPHERES AND GENERALIZED BESSEL FUNCTION ASSOCIATED WITH DIHEDRAL GROUPS

    E-print Network

    Paris-Sud XI, Université de

    RADON TRANSFORM ON SPHERES AND GENERALIZED BESSEL FUNCTION ASSOCIATED WITH DIHEDRAL GROUPS N. Demni a modified Bessel function and a Gegenbauer polynomial, that generalizes a known series already considered considerations allowed the author to derive the so-called generalized Bessel function associated with dihedral

  8. Metallicity Distribution Functions of Four Local Group dwarf galaxies

    E-print Network

    Ross, Teresa L; Saha, Abhijit; Anthony-Twarog, Barbara J

    2015-01-01

    We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 (WFC3) instrument aboard the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, 1) matching stars to isochrones in color-color diagrams, and 2) solving for the best linear combination of synthetic populations to match the observed color-color diagram. The synthetic technique reduces the effect of photometric scatter, and produces MDFs 30-50 % narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEM) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spher...

  9. A CRM Domain Protein Functions Dually in Group I and Group II Intron Splicing in Land Plant Chloroplasts[W

    PubMed Central

    Asakura, Yukari; Barkan, Alice

    2007-01-01

    The CRM domain is a recently recognized RNA binding domain found in three group II intron splicing factors in chloroplasts, in a bacterial protein that associates with ribosome precursors, and in a family of uncharacterized proteins in plants. To elucidate the functional repertoire of proteins with CRM domains, we studied CFM2 (for CRM Family Member 2), which harbors four CRM domains. RNA coimmunoprecipitation assays showed that CFM2 in maize (Zea mays) chloroplasts is associated with the group I intron in pre-trnL-UAA and group II introns in the ndhA and ycf3 pre-mRNAs. T-DNA insertions in the Arabidopsis thaliana ortholog condition a defective-seed phenotype (strong allele) or chlorophyll-deficient seedlings with impaired splicing of the trnL group I intron and the ndhA, ycf3-int1, and clpP-int2 group II introns (weak alleles). CFM2 and two previously described CRM proteins are bound simultaneously to the ndhA and ycf3-int1 introns and act in a nonredundant fashion to promote their splicing. With these findings, CRM domain proteins are implicated in the activities of three classes of catalytic RNA: group I introns, group II introns, and 23S rRNA. PMID:18065687

  10. Size dependent aqueous dispersibility of carboxylated multiwall carbon nanotubes

    PubMed Central

    Ntim, Susana Addo; Sae-Khow, Ornthida; Desai, Chintal; Witzmann, Frank A.; Mitra, Somenath

    2013-01-01

    The size dependent colloidal behavior of aqueous dispersions of carboxylated multiwall carbon nanotubes (c-MWCNTs) is presented. The presence of carboxylic groups provided electrostatic stabilization in water, where the size affected agglomeration. While aspect ratio did not show any definite correlation, the hydrophobicity indices (HI), zeta potential and aggregation kinetics showed dependence on the length of the c-MWCNTs where the shorter c-MWCNTs showed significantly lower HI values, smaller particle aggregates, higher zeta potential values and higher critical coagulation concentrations (ccc) in the presence of electrolytes. Although the diameter of the short c-MWCNTs did not appear to influence their aggregation behavior, the longer c-MWCNTs showed a dependence on diameter where stability decreased with increasing CNT diameter. PMID:22972403

  11. Red electroluminescence of ruthenium sensitizer functionalized by sulfonate anchoring groups.

    PubMed

    Shahroosvand, Hashem; Abbasi, Parisa; Mohajerani, Ezeddin; Janghouri, Mohammad

    2014-06-28

    We have synthesized five novel Ru(ii) phenanthroline complexes with an additional aryl sulfonate ligating substituent at the 5-position [Ru(L)(bpy)2](BF4)2 (1), [Ru(L)(bpy)(SCN)2] (2), [Ru(L)3](BF4)2 (3), [Ru(L)2(bpy)](BF4)2 (4) and [Ru(L)(BPhen)(SCN)2] (5) (where L = 6-one-[1,10]phenanthroline-5-ylamino)-3-hydroxynaphthalene 1-sulfonic, bpy = 2,2'-bipyridine, BPhen = 4,7-diphenyl-1,10-phenanthroline), as both photosensitizers for oxide semiconductor solar cells (DSSCs) and light emitting diodes (LEDs). The absorption and emission maxima of these complexes red shifted upon extending the conjugation of the phenanthroline ligand. Ru phenanthroline complexes exhibit broad metal to ligand charge transfer-centered electroluminescence (EL) with a maximum near 580 nm. Our results indicated that a particular structure (2) can be considered as both DSSC and OLED devices. The efficiency of the LED performance can be tuned by using a range of ligands. Device (2) has a luminance of 550 cd m(-2) and maximum efficiency of 0.9 cd A(-1) at 18 V, which are the highest values among the five devices. The turn-on voltage of this device is approximately 5 V. The role of auxiliary ligands in the photophysical properties of Ru complexes was investigated by DFT calculation. We have also studied photovoltaic properties of dye-sensitized nanocrystalline semiconductor solar cells based on Ru phenanthroline complexes and an iodine redox electrolyte. A solar energy to electricity conversion efficiency (?) of 0.67% was obtained for Ru complex (2) under standard AM 1.5 irradiation with a short-circuit photocurrent density (Jsc) of 2.46 mA cm(-2), an open-circuit photovoltage (Voc) of 0.6 V, and a fill factor (ff) of 40%, which are all among the highest values for ruthenium sulfonated anchoring groups reported so far. Monochromatic incident photon to current conversion efficiency was 23% at 475 nm. Photovoltaic studies clearly indicated dyes with two SCN substituents yielded a higher Jsc for the cell than dyes with a tris-homoleptic anchor substituent. PMID:24818219

  12. Solvent-dependent decarboxylation of 1,3-dimethylimdazolium-2-carboxylate.

    PubMed

    Denning, Derek M; Falvey, Daniel E

    2014-05-16

    1,3-Dimethylimidazolium-2-carboxylate 1 is stable in both pure water and pure acetonitrile. However, in mixtures of the two solvents, this compound suffers a rapid decarboxylation/protonaton reaction, forming 1,3-dimethylimidazolium cation 2. A series of kinetic and mechanistic experiments, along with DFT calculations, were carried out to understand the mechanism of this process and to elucidate the role of solvation on the stability of 1. These findings demonstrate that the decomposition process is a reversible decarboxylation forming the corresponding N-heterocyclic carbene (1,3-dimethylimidazolylidene, 3), followed by a rapid protonation of 3 by water or other protic species. The length and strength of the C-C bond between in the imidazolium ring and the carboxylate group (denoted C(NHC)-CO2) of 1 is remarkably dependent on the polarity of the solvent. Density functional theory (DFT) calculations predict a ca. 20 kcal/mol change in the barrier to decarboxylation in going from the gas phase to (SMD-simulated) water. Thus, addition of water has two effects on the stability of 1. At low concentrations, it provides a proton source for the trapping of the carbene 3 and accelerates decomposition. At higher concentrations, it increases the polarity of the medium. slowing the decarboxylation process and likewise the overall decomposition rate. PMID:24762208

  13. Isolation of carboxylic acid-protected Au25 clusters using a borohydride purification strategy.

    PubMed

    Shivhare, Atal; Wang, Lisa; Scott, Robert W J

    2015-02-10

    We report the synthesis of 11-mercaptoundecanoic acid (11-MUA) and 16-mercaptohexadecanoic acid (16-MHA) protected Au25 clusters with moderate yields (?15%) using a NaBH4 purification strategy. UV-vis spectroscopy, transmission electron microscopy (TEM), and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry were employed to study the entire process of the isolation of 11-MUA-protected Au25 clusters from a polydisperse Au cluster solution. UV-vis and TEM data clearly show the formation of a polydisperse mixture, which upon the addition of NaBH4 leads to the growth and precipitation of non-Au25 clusters, leaving the Au25 clusters behind. MALDI MS shows the molecular ion peak for the 11-MUA-protected Au25 cluster. 11-MUA-protected Au25 clusters in THF were purified by slowly increasing the pH of the solution, which leads to the complete deprotonation of carboxyl groups on the surface and eventually precipitation of Au25 clusters. Further protonation of these clusters by acetic acid leads to their solubilization in THF. These results show that, owing to the inherent stability of Au25 clusters, a NaBH4 purification strategy can be used to isolate Au25 clusters with surface carboxylic acid functionalities from a polydisperse Au cluster solution. PMID:25590767

  14. Group theory of Wannier functions providing the basis for a deeper understanding of magnetism and superconductivity

    E-print Network

    Ekkehard Krüger; Horst P. Strunk

    2015-02-14

    The paper presents the group theory of best localized and symmetry-adapted Wannier functions in a crystal of any given space group G or magnetic group M. Provided that the calculated band structure of the considered material is given and that the symmetry of the Bloch functions at all the points of symmetry in the Brillouin zone is known, the paper details whether or not the Bloch functions of particular energy bands can be unitarily transformed into best localized Wannier functions symmetry-adapted to the space group G, to the magnetic group M, or to a subgroup of G or M. In this context, the paper considers usual as well as spin-dependent Wannier functions, the latter representing the most general definition of Wannier functions. The presented group theory is a review of the theory published by one of the authors in several former papers and is independent of any physical model of magnetism or superconductivity. However, it is suggested to interpret the special symmetry of the best localized Wannier functions in the framework of a nonadiabatic extension of the Heisenberg model, the nonadiabatic Heisenberg model. On the basis of the symmetry of the Wannier functions, this model of strongly correlated localized electrons makes clear predictions whether or not the system can possess superconducting or magnetic eigenstates.

  15. Metallicity Distribution Functions of Four Local Group Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Ross, Teresa L.; Holtzman, Jon; Saha, Abhijit; Anthony-Twarog, Barbara J.

    2015-06-01

    We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 instrument on board the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, (1) matching stars to isochrones in color–color diagrams and (2) solving for the best linear combination of synthetic populations to match the observed color–color diagram. The synthetic technique reduces the effect of photometric scatter and produces MDFs 30%–50% narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEMs) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spheroidal) to be very peaked with a steep metal-rich cutoff and an extended metal-poor tail, while Leo II (dwarf spheroidal), Phoenix (dwarf transition), and IC 1613 (dwarf irregular) have wider, less peaked MDFs than Leo I. A simple CEM is not the best fit for any of our galaxies; therefore we also fit the “Best Accretion Model” of Lynden-Bell. For Leo II, IC 1613, and Phoenix we find similar accretion parameters for the CEM even though they all have different effective yields, masses, star formation histories, and morphologies. We suggest that the dynamical history of a galaxy is reflected in the MDF, where broad MDFs are seen in galaxies that have chemically evolved in relative isolation and narrowly peaked MDFs are seen in galaxies that have experienced more complicated dynamical interactions concurrent with their chemical evolution. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 12304.

  16. a Renormalization Group Calculation of the Velocity - and Density-Density Correlation Functions.

    NASA Astrophysics Data System (ADS)

    Cowan, Mark Timothy

    The velocity-velocity correlation function of a free field theory is obtained. The renormalization group, along with a 4-varepsilon expansion, is then used to find the leading order behavior of the velocity-velocity correlation function for an interacting field theory in the high temperature phase near the critical point. The details of the calculation of the density-density correlation function for Hedgehogs, in the context of a free field theory, is presented next. Finally the renormalization group, along with a 4-varepsilon expansion, is used to find the leading order behavior of the density-density correlation function for Hedgehogs in an interacting field theory near the critical point.

  17. Theoretical study of structure and stability of small gadolinium carboxylate complexes in liquid scintillator solvents.

    PubMed

    Huang, Pin-Wen

    2014-09-01

    The structural properties of three small gadolinium carboxylate complexes in three liquid scintillator solvents (pseudocumene, linear alkylbenzene, and phenyl xylylethane) were theoretically investigated using density functional theory (B3LYP/LC-RECP) and polarizable continuum model (PCM). The average interaction energy between gadolinium atom and carboxylate ligand (E(int)) and the energy difference of the highest singly occupied molecular orbital and lowest unoccupied molecular orbital (?(SL)) were calculated to evaluate and compare the relative stability of these complexes in solvents. The calculation results show that the larger (with a longer alkyl chain) gadolinium carboxylate complex has greater stability than the smaller one, while these gadolinium carboxylates in linear alkylbenzene were found to have greater stability than those in the other two solvents. PMID:25204583

  18. The preparation of size-controlled functionalized polymeric nanoparticles in micelles

    NASA Astrophysics Data System (ADS)

    Vakurov, Alexander; Pchelintsev, Nikolay A.; Forde, Jessica; Ó'Fágáin, Ciaran; Gibson, Tim; Millner, Paul

    2009-07-01

    The reverse micellar system of dioctyl-sulfosuccinate (AOT)/octane and toluene have been used as a template for polymerization of acrylamide (AA)/bisacrylamide (BAA)-based functionalized polymeric nanoparticles. Such nanoparticles are typically sized between 20 and 90 nm. They can be synthesized with different functional groups according to the monomers added to the polymerization mixture. In our experiments the nanoparticles carried amino and carboxyl groups following incorporation of allylamine (AAm) or methacrylic acid (MAA) monomers, respectively. The available amine or carboxyl groups can then be used for immobilization of enzymes or other biomolecules. These enzymes, subtilisin, laccase and lipase, were immobilized onto polyAA/BAA/MAA nanoparticles covalently after activating the MAA carboxylic groups with Woodward's K reagent. Non-covalent immobilization via electrostatic interaction was also performed.

  19. Developing the group mind through functional subgrouping: linking systems-centered training (SCT) and interpersonal neurobiology.

    PubMed

    Gantt, Susan P; Agazarian, Yvonne M

    2010-10-01

    This article introduces the systems-centered concept of the "group mind" by linking systems-centered thinking and interpersonal neurobiology, building on Siegel's definition of mind as the process of regulating the flow of energy and information. Functional subgrouping, the systems-centered group method for resolving conflicts, discriminates and integrates the flow of energy and information within and between group members, subgroups, and the group-as-a-whole, thus potentiating survival, development, and transformation. This article uses the interpersonal neurobiological framework to discuss functional subgrouping as a tool for developing the group mind: considering how functional subgrouping facilitates emotional regulation, creates a secure relational context, and potentiates neural integration. PMID:21028975

  20. Analysis of functionalized polyethylene terephthalate with immobilized NTPDase and cysteine.

    PubMed

    Muthuvijayan, Vignesh; Gu, Jun; Lewis, Randy S

    2009-11-01

    Polyethylene terephthalate (PET) was functionalized to introduce carboxyl groups onto its surface by a carboxylation technique. Surface and bulk properties, such as possible surface deterioration, surface roughness and the mechanical strength of the carboxylated polymers, were studied and compared with those of aminolyzed and hydrolyzed PET. Atomic force microscopy studies showed that unlike aminolysis and hydrolysis, which increased the surface roughness significantly due to cracking and pitting, the surface roughness of unmodified and carboxylated PET were comparable. While hydrolysis and aminolysis of PET resulted in significant loss of strength, tensile testing revealed that unmodified and carboxylated polymers had similar strength. The development of mechanically stable, functionalized PET would vastly improve the biomedical applications of this polymer. To understand the potential for improving biomedical applications, biologically active molecules, namely nucleoside triphosphate diphosphohydrolase (NTPDase) and cysteine, were immobilized on the carboxylated PET using amide bonds. NTPDase was also immobilized to aminolyzed PET using imine bonds, while cysteine was immobilized on aminolyzed PET using both imine and amide bonds. Attachment of NTPDase and cysteine was verified by analyzing the NTPDase activity and the cysteine surface concentration. The stability of these immobilizations was also studied. PMID:19477307

  1. Ozonation of indigo enhanced by carboxylated carbon nanotubes: performance optimization, degradation products, reaction mechanism and toxicity evaluation.

    PubMed

    Qu, Ruijuan; Xu, Bingzhe; Meng, Lingjun; Wang, Liansheng; Wang, Zunyao

    2015-01-01

    As a promising disinfection technique to replace chlorination, ozonation has been demonstrated to be efficient in water treatment. This paper describes an effective way to enhance the ozonation of indigo by using carbon nanotubes functionalized with carboxyl groups (CNTs-COOH) as catalysts. The result of kinetic studies showed that the presence of CNTs-COOH dramatically increased the decolorization rate of indigo. Different types of catalysts were compared to further elucidate the internal mechanism of the catalytic reaction and the special nanostructure and the functional –COOH groups are considered to play an important role in the catalytic ozonation process. Four aromatic intermediate products were identified using an electrospray time-of-flight mass spectrometer and further rationalized by the frontier electron density calculations. Ion chromatography analysis revealed that the nitrogen atom of indigo was released predominantly as ammonium and to a lesser extent as nitrate. The presence of the catalyst CNTs-COOH leads to a higher mineralization degree than single ozonation, as suggested by the total organic carbon (TOC) measurement. Three major carboxylic acids (i.e., oxalic, formic and acetic acids) were also identified as oxidation by-products, and they contributed significantly to the residual TOC after 2 h of ozonation. In addition, the toxicity evolution during the degradation was investigated through two aquatic model species to evaluate the potential ecological risks of the intermediate products. PMID:25462739

  2. A Functional Group Approach for Prediction of APPI Response of Organic Synthetic Targets.

    PubMed

    Zhurov, Konstantin O; Menin, Laure; Di Franco, Thomas; Tsybin, Yury O

    2015-07-01

    Atmospheric pressure photoionization (APPI) is a technique of choice for ionization of non-polar molecules in mass spectrometry (MS). Reported APPI-based studies tend to focus on a selected compound class, which may contain a variety of functional groups. These studies demonstrate that APPI response frequently differs substantially, indicating a certain dependence on the functional group present. Although this dependence could be employed for APPI response prediction, its systematic use is currently absent. Here, we apply APPI MS to a judiciously-compiled set of 63 compounds containing a number of diverse functional groups commonly utilized in synthesis, reactive functional groups, as well as those containing boron and silicon. Based on the outcome of APPI MS of these compounds, we propose and evaluate a simple guideline to estimate the APPI response for a novel compound, the key properties of which have not been characterized in the gas phase. Briefly, we first identify key functional groups in the compound and gather knowledge on the known ionization energies from the smallest analogues containing said functional groups. We then consider local inductive and resonance effects on said ionization energies for the compounds of interest to estimate the APPI response. Finally, application of APPI MS to compounds of interest considered herein demonstrated extended upper mass ionization limit of 3.5 kDa for non-polymeric compounds. Graphical Abstract ?. PMID:25895888

  3. A Functional Group Approach for Prediction of APPI Response of Organic Synthetic Targets

    NASA Astrophysics Data System (ADS)

    Zhurov, Konstantin O.; Menin, Laure; Di Franco, Thomas; Tsybin, Yury O.

    2015-04-01

    Atmospheric pressure photoionization (APPI) is a technique of choice for ionization of non-polar molecules in mass spectrometry (MS). Reported APPI-based studies tend to focus on a selected compound class, which may contain a variety of functional groups. These studies demonstrate that APPI response frequently differs substantially, indicating a certain dependence on the functional group present. Although this dependence could be employed for APPI response prediction, its systematic use is currently absent. Here, we apply APPI MS to a judiciously-compiled set of 63 compounds containing a number of diverse functional groups commonly utilized in synthesis, reactive functional groups, as well as those containing boron and silicon. Based on the outcome of APPI MS of these compounds, we propose and evaluate a simple guideline to estimate the APPI response for a novel compound, the key properties of which have not been characterized in the gas phase. Briefly, we first identify key functional groups in the compound and gather knowledge on the known ionization energies from the smallest analogues containing said functional groups. We then consider local inductive and resonance effects on said ionization energies for the compounds of interest to estimate the APPI response. Finally, application of APPI MS to compounds of interest considered herein demonstrated extended upper mass ionization limit of 3.5 kDa for non-polymeric compounds.

  4. Computations for Group Sequential Boundaries Using the Lan-DeMets Spending Function Method

    Microsoft Academic Search

    David M. Reboussin; David L. DeMets; KyungMann Kim; K. K. Gordon Lan

    2000-01-01

    We describe an interactive Fortran program which performs computations related to the design and analysis of group sequential clinical trials using Lan-DeMets spending functions. Many clinical trials include interim analyses of accumulating data and rely on group sequential methods to avoid consequent inflation of the type I error rate. The computations are appropriate for interim test statistics whose distribution or

  5. Identification of Differential Item Functioning in Multiple-Group Settings: A Multivariate Outlier Detection Approach

    ERIC Educational Resources Information Center

    Magis, David; De Boeck, Paul

    2011-01-01

    We focus on the identification of differential item functioning (DIF) when more than two groups of examinees are considered. We propose to consider items as elements of a multivariate space, where DIF items are outlying elements. Following this approach, the situation of multiple groups is a quite natural case. A robust statistics technique is…

  6. THE SPHERICAL TRANSFORM OF A SCHWARTZ FUNCTION ON THE HEISENBERG GROUP

    E-print Network

    Benson, Chal

    THE SPHERICAL TRANSFORM OF A SCHWARTZ FUNCTION ON THE HEISENBERG GROUP CHAL BENSON, JOE JENKINS group H n = V \\Theta R with group law (z; t)(z 0 ; t 0 ) = ` z + z 0 ; t + t 0 \\Gamma 1 2 Imhz; z 0 i Subject Classification. Primary 22E30, 43A55. 1 #12; 2 C. BENSON, J. JENKINS, AND G. RATCLIFF of (V; h

  7. Psychosocial Functioning in a Group of Swedish Adults with Asperger Syndrome or High-Functioning Autism.

    ERIC Educational Resources Information Center

    Engstrom, I.; Ekstrom, L.; Emilsson, B.

    2003-01-01

    A study investigated psychosocial functioning in 16 Swedish adults with Asperger syndrome or high-functioning autism. The majority lived independently; all but one were unemployed; and none was married or had children. Most persons needed a high level of public and/or private support. Overall adjustment was rated good in 12%. (Contains…

  8. Representing key phytoplankton functional groups in ocean carbon cycle models: Coccolithophorids

    E-print Network

    Kleypas, Joanie

    that areas with sea surface temperatures (SST) between 3° and 15°C, a critical irradiance between 25 and 150Representing key phytoplankton functional groups in ocean carbon cycle models: Coccolithophorids M, we developed a probability density function that accounts for the physical chemical variables

  9. Direct UV-induced functionalization of surface hydroxy groups by thiol-ol chemistry.

    PubMed

    Li, Linxian; Li, Junsheng; Du, Xin; Welle, Alexander; Grunze, Michael; Trapp, Oliver; Levkin, Pavel A

    2014-04-01

    A novel UV-initiated surface modification method for the direct functionalization of surface hydroxy groups with thiol-containing molecules (termed "thiol-ol" modification) is described. This method is based on the oxidative conjugation of thiols to hydroxy groups. We demonstrate that different thiol-containing molecules, such as fluorophores, thiol-terminated poly(ethylene glycol) (PEG-SH), and a cysteine-containing peptide, can be attached onto the surface of porous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate). Direct functionalization of other hydroxy-group-bearing surfaces, fabrication of micropatterns, and double patterning have been also demonstrated using the thiol-ol method. PMID:24595963

  10. Classifying proteins into functional groups based on all-versus-all BLAST of 10 million proteins.

    PubMed

    Kolker, Natali; Higdon, Roger; Broomall, William; Stanberry, Larissa; Welch, Dean; Lu, Wei; Haynes, Winston; Barga, Roger; Kolker, Eugene

    2011-01-01

    To address the monumental challenge of assigning function to millions of sequenced proteins, we completed the first of a kind all-versus-all sequence alignments using BLAST for 9.9 million proteins in the UniRef100 database. Microsoft Windows Azure produced over 3 billion filtered records in 6 days using 475 eight-core virtual machines. Protein classification into functional groups was then performed using Hive and custom jars implemented on top of Apache Hadoop utilizing the MapReduce paradigm. First, using the Clusters of Orthologous Genes (COG) database, a length normalized bit score (LNBS) was determined to be the best similarity measure for classification of proteins. LNBS achieved sensitivity and specificity of 98% each. Second, out of 5.1 million bacterial proteins, about two-thirds were assigned to significantly extended COG groups, encompassing 30 times more assigned proteins. Third, the remaining proteins were classified into protein functional groups using an innovative implementation of a single-linkage algorithm on an in-house Hadoop compute cluster. This implementation significantly reduces the run time for nonindexed queries and optimizes efficient clustering on a large scale. The performance was also verified on Amazon Elastic MapReduce. This clustering assigned nearly 2 million proteins to approximately half a million different functional groups. A similar approach was applied to classify 2.8 million eukaryotic sequences resulting in over 1 million proteins being assign to existing KOG groups and the remainder clustered into 100,000 functional groups. PMID:21809957

  11. Vibrational spectroscopy of functional group chemistry and arsenate coordination in ettringite

    Microsoft Academic Search

    Satish C. B. Myneni; Samuel J. Traina; Glenn A. Waychunas; Terry J. Logan

    1998-01-01

    The functional group chemistry and coordination of AsO43?-sorption complexes in ettringite [Ca6Al2(SO4)3(OH)12·26H2O] were evaluated as a function of sorption type (adsorption, coprecipitation) and pH using Raman and Fourier Transform infrared (FTIR) spectroscopies. The reactive functional groups of ettringite, ?Al-OH, ?Ca-OH2, and ?Ca2-OH exhibit broad overlapping OH bands in the range 3600–3200 cm?1, prohibiting separation of component vibrational bands. The SO42?

  12. Benzyl 2-{[2,8-bis­(trifluoro­meth­yl)quinolin-4-yl](hy­droxy)meth­yl}piperidine-1-carboxyl­ate

    PubMed Central

    de Souza, Marcus V. N.; Gonçalves, Raoni S. B.; Wardell, James L.; Wardell, Solange M. S. V.; Tiekink, Edward R. T.

    2011-01-01

    The title mol­ecule, C25H22F6N2O3, adopts an open conformation whereby the quinoline and carboxyl­ate ester groups are orientated in opposite directions but to the same side of the piperidine ring so that the mol­ecule has an approximate U-shape. The piperidine ring adopts a distorted boat conformation. In the crystal, inversion dimers linked by pairs of O—H?O hydrogen bonds generate R 2 2(14) loops. PMID:22199814

  13. tert-Butyl 2-{[2,8-bis­(trifluoro­meth­yl)quinolin-4-yl](hy­droxy)meth­yl}piperidine-1-carboxyl­ate

    PubMed Central

    Gonçalves, Raoni S. B.; de Souza, Marcus V. N.; Wardell, James L.; Wardell, Solange M. S. V.; Tiekink, Edward R. T.

    2011-01-01

    The title mol­ecule, C22H24F6N2O3, adopts a folded conformation whereby the carboxyl­ate residue lies over the quinolinyl residue, with the dihedral angle between the carbamate and quinoline planes being 41.64?(7)°. Helical supra­molecular C(7) chains sustained by O—H?O hydrogen bonds propagating along the a-axis direction feature in the crystal packing. The F atoms of one of the CF3 groups are disordered over two orientations; the major component has a site occupancy of 0.824?(7). PMID:22199815

  14. Infrared Spectroscopy of Functionalized Graphene Sheets from First Principle Calculations

    NASA Astrophysics Data System (ADS)

    Zhang, Cui; Dabbs, Daniel; Aksay, Ilhan; Car, Roberto; Selloni, Annabella

    2014-03-01

    Detailed characterization of the structure of functionalized graphene sheets (FGSs) is an important and challenging task which could help to improve the performance of FGS materials for technological applications. We present here first principles calculations for the infrared (IR) spectra of different FGS models aimed at identifying the IR signatures of different functional groups and defect sites on FGSs. We found that vacancies and edges have significant effects on the IR frequencies of the functional groups on FGSs. In particular, hydroxyl groups close to vacancies have higher stretching and lower bending frequencies in comparison to hydroxyls in defect free regions of FGSs. More interestingly, the OH vibrations of carboxyl groups at edges exhibit unique features in the high frequency IR bands, which originate from the interactions with neighboring groups and the relative orientation of the carboxyl with respect to the FGS plane. Our results are supported by experimental IR measurements on FGS powders.

  15. Population dynamics: seasonal variation of phytoplankton functional groups in brazilian reservoirs (Billings and Guarapiranga, São Paulo).

    PubMed

    Gemelgo, M C P; Mucci, J L N; Navas-Pereira, D

    2009-11-01

    Phytoplankton may function as a 'sensor' of changes in aquatic environment and responds rapidly to such changes. In freshwaters, coexistence of species that have similar ecological requirements and show the same environmental requirements frequently occurs; such species groups are named functional groups. The use of phytoplankton functional groups to evaluate these changes has proven to be very useful and effective. Thus, the aim of this study was to evaluate the occurrence of functional groups of phytoplankton in two reservoirs (Billings and Guarapiranga) that supply water to millions of people in São Paulo city Metropolitan Area, southeastern Brazil. Surface water samples were collected monthly and physical, chemical and biological (quantitative and qualitative analyses of the phytoplankton) were performed. The highest biovolume (mm(3).L-1) of the descriptor species and functional groups were represented respectively by Anabaena circinalis Rabenh. (H1), Microcystis aeruginosa (Kützing) Kützing (L M/M) and Mougeotia sp. (T) in the Guarapiranga reservoir and Cylindrospermopsis raciborskii (Wolosz.) Seen. and Subba Raju (S N), Microcystis aeruginosa and M. panniformis Komárek et al. (L M/M), Planktothrix agardhii (Gom.) Anagn. and Komárek and P. cf. clathrata (Skuja) Anagn. and Komárek (S1) in the Billings reservoir. The environmental factors that most influenced the phytoplankton dynamics were water temperature, euphotic zone, turbidity, conductivity, pH, dissolved oxygen, nitrate and total phosphorous. PMID:19967171

  16. Local and Regional Determinants of an Uncommon Functional Group in Freshwater Lakes and Ponds

    PubMed Central

    McCann, Michael James

    2015-01-01

    A combination of local and regional factors and stochastic forces is expected to determine the occurrence of species and the structure of communities. However, in most cases, our understanding is incomplete, with large amounts of unexplained variation. Using functional groups rather than individual species may help explain the relationship between community composition and conditions. In this study, I used survey data from freshwater lakes and ponds to understand factors that determine the presence of the floating plant functional group in the northeast United States. Of the 176 water bodies surveyed, 104 (59.1%) did not contain any floating plant species. The occurrence of this functional group was largely determined by local abiotic conditions, which were spatially autocorrelated across the region. A model predicting the presence of the floating plant functional group performed similarly to the best species-specific models. Using a permutation test, I also found that the observed prevalence of floating plants is no different than expected by random assembly from a species pool of its size. These results suggest that the size of the species pool interacts with local conditions in determining the presence of a functional group. Nevertheless, a large amount of unexplained variation remains, attributable to either stochastic species occurrence or incomplete predictive models. The simple permutation approach in this study can be extended to test alternative models of community assembly. PMID:26121636

  17. Self-assembled carboxylate complexes of zinc, nickel and copper

    Microsoft Academic Search

    Kaustavmoni Deka; Nilotpal Barooah; Rupam Jyoti Sarma; Jubaraj B. Baruah

    2007-01-01

    A metallo-organic hybrid acid namely tetra-aquo bis-4-carboxy-N-phthaloylglycinato zinc(II) dihydrate is prepared and characterised. In this complex the hydrogen bonding by free carboxylic acid group and pi pi interactions between the rings in crystal lattice contributes to the formation of self-assembled structure. A monomeric nickel complex from 2-carbomethoxy benzoic acid (L2H) and pyridine [Ni(L2)(py)3(H2O)2]L2 is prepared (where py = pyridine). This

  18. Self-assembled carboxylate complexes of zinc, nickel and copper

    Microsoft Academic Search

    Kaustavmoni Deka; Nilotpal Barooah; Rupam Jyoti Sarma; Jubaraj B. Baruah

    2007-01-01

    A metallo-organic hybrid acid namely tetra-aquo bis-4-carboxy-N-phthaloylglycinato zinc(II) dihydrate is prepared and characterised. In this complex the hydrogen bonding by free carboxylic acid group and ?–? interactions between the rings in crystal lattice contributes to the formation of self-assembled structure. A monomeric nickel complex from 2-carbomethoxy benzoic acid (L2H) and pyridine [Ni(L2)(py)3(H2O)2]L2 is prepared (where py=pyridine). This complex has ionic

  19. Plant Species and Functional Group Combinations Affect Green Roof Ecosystem Functions

    Microsoft Academic Search

    Jeremy Lundholm; J. Scott Macivor; Zachary MacDougall; Melissa Ranalli; Hans Henrik Bruun

    2010-01-01

    BackgroundGreen roofs perform ecosystem services such as summer roof temperature reduction and stormwater capture that directly contribute to lower building energy use and potential economic savings. These services are in turn related to ecosystem functions performed by the vegetation layer such as radiation reflection and transpiration, but little work has examined the role of plant species composition and diversity in

  20. [Effects of long-term fertilization on organic carbon functional groups in black soil as revealed by synchrotron radiation soft X-ray near-edge absorption spectroscopy].

    PubMed

    Wang, Nan; Wang, Shuai; Wang, Qing-He; Dong, Pei-Bo; Li, Cui-Lan; Zhang, Jin-Jing; Gao, Qiang; Zhao, Yi-Dong

    2012-10-01

    A 20 years (1984-2004) stationary field experiment was conducted to evaluate the effects of long-term application of chemical fertilizers (N or NPK) alone or in combination with low (0.125 kg x hm(-2)) or high dose of corn stalk (0.25 kg x hm(-2)) on organic carbon functional groups in black soil using synchrotron radiation soft X-ray near-edge absorption spectroscopy (C-1s NEXAFS). Compared with the control (CK) treatment, the aromatic C and the carboxyl C of soil increased, whereas the aliphatic C, the carbonyl C and the aliphatic C/aromatic C ratio decreased after the application of chemical fertilizer alone. After the application of chemical fertilizations in combined with corn stalk, the aromatic C decreased while the aliphatic C and the aliphatic C/aromatic C ratio increased as compared to N or NPK fertilizer treatment. And the change tendency was more obvious with the increase in the dose of corn stalk applied. Regardless of corn stalk application, the aromatic C, the aliphatic C, and the aliphatic C/aromatic C ratio were all higher for NPK than for N fertilizer treatment. The above results indicated that, compared with the no-fertilizer control treatment, the application of chemical fertilizers alone resulted in the relative proportion of aromatic compounds increased whereas that of aliphatic hydrocarbon compounds decreased. On the other hand, the relative proportion of the aliphatic hydrocarbon compounds was higher after the application of chemical fertilizers with than without corn stalk, with high than with low dose of corn stalk, and with NPK than with N fertilization. C-1s NEXAFS spectroscopy could characterize in situ the changes of organic carbon functional groups in soil under long-term stationary fertilization. PMID:23285902

  1. How surface functional groups influence fracturation in nanofluid droplet dry-outs.

    PubMed

    Carle, Florian; Brutin, David

    2013-08-13

    In this study of drying water-based nanofluid droplets, we report the influence of surface functional groups and substrate surface energies on crack formation and dry-out shape. These two key parameters are investigated by allowing nanofluids with several functional groups grafted on polystyrene nanoparticle surfaces to dry on various substrates. These experiments result in a variety of regular crack patterns with identical nanoparticle diameter, material, concentration, and drying conditions. We demonstrate that, despite the various patterns observed, the crack spacing/deposit height ratio is constant for similar substrate surface energies and linearly increases with this parameter. Moreover, this study shows that the crack shape is strongly influenced by surface functional groups as a result of particle interactions (depending on the particle surface potentials) and compaction during solvent evaporation. PMID:23902151

  2. The Mass Function of Void Groups as a Probe of the Primordial non-Gaussianity

    E-print Network

    Hyunmi Song; Jounghun Lee

    2009-07-02

    The primordial non-Gaussianity signal, if measured accurately, will allow us to distinguish between different candidate models for the cosmic inflation. Since the galaxy groups located in void regions are rare events, their abundance may be a sensitive probe of the primordial non-Gaussianity. We construct an analytic model for the mass function of void groups in the framework of the extended Press-Schechter theory with non-Gaussian initial conditions and investigate how it depends on the primordial non-Gaussianity parameter. A feasibility study is conducted by fitting the analytic mass function of void groups to the observational results from the galaxy group catalog of the Sloan Digital Sky Survey Data Release 4 with adjusting the primordial non-Gaussianity parameter.

  3. Functional grouping and cortical–subcortical interactions in emotion: A meta-analysis of neuroimaging studies

    PubMed Central

    Kober, Hedy; Barrett, Lisa Feldman; Joseph, Josh; Bliss-Moreau, Eliza; Lindquist, Kristen; Wager, Tor D.

    2009-01-01

    We performed an updated quantitative meta-analysis of 162 neuroimaging studies of emotion using a novel multi-level kernel-based approach, focusing on locating brain regions consistently activated in emotional tasks and their functional organization into distributed functional groups, independent of semantically defined emotion category labels (e.g., “anger,” “fear”). Such brain-based analyses are critical if our ways of labeling emotions are to be evaluated and revised based on consistency with brain data. Consistent activations were limited to specific cortical sub-regions, including multiple functional areas within medial, orbital, and inferior lateral frontal cortices. Consistent with a wealth of animal literature, multiple subcortical activations were identified, including amygdala, ventral striatum, thalamus, hypothalamus, and periaqueductal gray. We used multivariate parcellation and clustering techniques to identify groups of co-activated brain regions across studies. These analyses identified six distributed functional groups, including medial and lateral frontal groups, two posterior cortical groups, and paralimbic and core limbic/brainstem groups. These functional groups provide information on potential organization of brain regions into large-scale networks. Specific follow-up analyses focused on amygdala, periaqueductal gray (PAG), and hypothalamic (Hy) activations, and identified frontal cortical areas co-activated with these core limbic structures. While multiple areas of frontal cortex co-activated with amygdala sub-regions, a specific region of dorsomedial prefrontal cortex (dmPFC, Brodmann’s Area 9/32) was the only area co-activated with both PAG and Hy. Subsequent mediation analyses were consistent with a pathway from dmPFC through PAG to Hy. These results suggest that medial frontal areas are more closely associated with core limbic activation than their lateral counterparts, and that dmPFC may play a particularly important role in the cognitive generation of emotional states. PMID:18579414

  4. Ethyl 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate

    PubMed Central

    Nizam Mohideen, M.; Rasheeth, A.; Huq, C. A. M. A.; Nizar, S. Syed

    2008-01-01

    The title compound, C14H16N2O3, belongs to a group of esters of 2-oxo- and 1,2,3,4-tetra­hydro­pyrimidine-5-carboxylic acids, which exhibit a wide spectrum of biological activities. The dihydro­pyrimidine ring adopts a screw-boat conformation. The crystal packing is stabilized by strong N—H?O and weak C—H?O inter­molecular hydrogen bonds. An intra­molecular C—H?O hydrogen bond is also present. PMID:21201734

  5. One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres with enhanced photocatalytic performance

    SciTech Connect

    Qu, Lingling [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Luo, Zhijun, E-mail: lzj@ujs.edu.cn [School of the Environment, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 (China); Tang, Chao [Maple Leaf International High School, Zhenjiang 212013 (China)

    2013-11-15

    Graphical abstract: Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core–shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs). Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation. - Highlights: • One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres. • Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@CRCSs. • Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits enhanced photocatalytic activity under visible light irradiation. - Abstract: Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core-shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs) have been synthesized via a one-step method. The core–shell nanosturctures of the as-prepared samples were confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Raman spectroscopy. The formation of Bi@Bi{sub 2}O{sub 3}@CRCSs core–shell nanosturctures should attribute to the synergetic roles of different functional groups of sodium gluconate. Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation (? > 420 nm) and shows an O{sub 2}-dependent feature. According to trapping experiments of radicals and holes, hydroxyl radicals were not the main active oxidative species in the photocatalytic degradation of MB, but O{sub 2}·{sup ?} are the main active oxidative species.

  6. Bis(?-2?-carboxyl­atobiphenyl-2-carboxylic acid-?2 O 2:O 2?)bis­[(2,2?-bipyridine-?2 N,N?)(2?-carboxyl­ato­biphenyl-2-carboxylic acid-?O 2?)zinc(II)

    PubMed Central

    An, Zhe

    2009-01-01

    In the dimeric title compound, [Zn2(C14H9O4)4(C10H8N2)2], the ZnII ions are penta­coordinated by one 2,2?-bipyridyl ligand and by three O atoms from three 2?-carboxyl­atobiphenyl-2-carboxylic acid ligands. Two of the 2?-carboxyl­atobiphenyl-2-carboxylic acid ligands act as bridging ligands and, together with two zinc(II) cations, produce an 18-membered ring system. The remaining 2?-carboxyl­atobiphenyl-2-carboxylic acid ligands work as monodentate ligands. The crystal packing diagram is consolidated by O—H?O hydrogen bonds. PMID:21578552

  7. Cellular distribution and cytotoxicity of graphene quantum dots with different functional groups

    NASA Astrophysics Data System (ADS)

    Yuan, Xiaochan; Liu, Zhiming; Guo, Zhouyi; Ji, Yanhong; Jin, Mei; Wang, Xinpeng

    2014-03-01

    Graphene quantum dots (GQDs) have been developed as promising optical probes for bioimaging due to their excellent photoluminescent properties. Additionally, the fluorescence spectrum and quantum yield of GQDs are highly dependent on the surface functional groups on the carbon sheets. However, the distribution and cytotoxicity of GQDs functionalized with different chemical groups have not been specifically investigated. Herein, the cytotoxicity of three kinds of GQDs with different modified groups (NH2, COOH, and CO-N (CH3)2, respectively) in human A549 lung carcinoma cells and human neural glioma C6 cells was investigated using thiazoyl blue colorimetric (MTT) assay and trypan blue assay. The cellular apoptosis or necrosis was then evaluated by flow cytometry analysis. It was demonstrated that the three modified GQDs showed good biocompatibility even when the concentration reached 200 ?g/mL. The Raman spectra of cells treated with GQDs with different functional groups also showed no distinct changes, affording molecular level evidence for the biocompatibility of the three kinds of GQDs. The cellular distribution of the three modified GQDs was observed using a fluorescence microscope. The data revealed that GQDs randomly dispersed in the cytoplasm but not diffused into nucleus. Therefore, GQDs with different functional groups have low cytotoxicity and excellent biocompatibility regardless of chemical modification, offering good prospects for bioimaging and other biomedical applications.

  8. Cellular distribution and cytotoxicity of graphene quantum dots with different functional groups

    PubMed Central

    2014-01-01

    Graphene quantum dots (GQDs) have been developed as promising optical probes for bioimaging due to their excellent photoluminescent properties. Additionally, the fluorescence spectrum and quantum yield of GQDs are highly dependent on the surface functional groups on the carbon sheets. However, the distribution and cytotoxicity of GQDs functionalized with different chemical groups have not been specifically investigated. Herein, the cytotoxicity of three kinds of GQDs with different modified groups (NH2, COOH, and CO-N (CH3)2, respectively) in human A549 lung carcinoma cells and human neural glioma C6 cells was investigated using thiazoyl blue colorimetric (MTT) assay and trypan blue assay. The cellular apoptosis or necrosis was then evaluated by flow cytometry analysis. It was demonstrated that the three modified GQDs showed good biocompatibility even when the concentration reached 200 ?g/mL. The Raman spectra of cells treated with GQDs with different functional groups also showed no distinct changes, affording molecular level evidence for the biocompatibility of the three kinds of GQDs. The cellular distribution of the three modified GQDs was observed using a fluorescence microscope. The data revealed that GQDs randomly dispersed in the cytoplasm but not diffused into nucleus. Therefore, GQDs with different functional groups have low cytotoxicity and excellent biocompatibility regardless of chemical modification, offering good prospects for bioimaging and other biomedical applications. PMID:24597852

  9. Cellular distribution and cytotoxicity of graphene quantum dots with different functional groups.

    PubMed

    Yuan, Xiaochan; Liu, Zhiming; Guo, Zhouyi; Ji, Yanhong; Jin, Mei; Wang, Xinpeng

    2014-01-01

    Graphene quantum dots (GQDs) have been developed as promising optical probes for bioimaging due to their excellent photoluminescent properties. Additionally, the fluorescence spectrum and quantum yield of GQDs are highly dependent on the surface functional groups on the carbon sheets. However, the distribution and cytotoxicity of GQDs functionalized with different chemical groups have not been specifically investigated. Herein, the cytotoxicity of three kinds of GQDs with different modified groups (NH2, COOH, and CO-N (CH3)2, respectively) in human A549 lung carcinoma cells and human neural glioma C6 cells was investigated using thiazoyl blue colorimetric (MTT) assay and trypan blue assay. The cellular apoptosis or necrosis was then evaluated by flow cytometry analysis. It was demonstrated that the three modified GQDs showed good biocompatibility even when the concentration reached 200 ?g/mL. The Raman spectra of cells treated with GQDs with different functional groups also showed no distinct changes, affording molecular level evidence for the biocompatibility of the three kinds of GQDs. The cellular distribution of the three modified GQDs was observed using a fluorescence microscope. The data revealed that GQDs randomly dispersed in the cytoplasm but not diffused into nucleus. Therefore, GQDs with different functional groups have low cytotoxicity and excellent biocompatibility regardless of chemical modification, offering good prospects for bioimaging and other biomedical applications. PMID:24597852

  10. Testing group differences in brain functional connectivity: using correlations or partial correlations?

    PubMed

    Kim, Junghi; Wozniak, Jeffrey R; Mueller, Bryon A; Pan, Wei

    2015-05-01

    Resting-state functional magnetic resonance imaging allows one to study brain functional connectivity, partly motivated by evidence that patients with complex disorders, such as Alzheimer's disease, may have altered functional brain connectivity patterns as compared with healthy subjects. A functional connectivity network describes statistical associations of the neural activities among distinct and distant brain regions. Recently, there is a major interest in group-level functional network analysis; however, there is a relative lack of studies on statistical inference, such as significance testing for group comparisons. In particular, it is still debatable which statistic should be used to measure pairwise associations as the connectivity weights. Many functional connectivity studies have used either (full or marginal) correlations or partial correlations for pairwise associations. This article investigates the performance of using either correlations or partial correlations for testing group differences in brain connectivity, and how sparsity levels and topological structures of the connectivity would influence statistical power to detect group differences. Our results suggest that, in general, testing group differences in networks deviates from estimating networks. For example, high regularization in both covariance matrices and precision matrices may lead to higher statistical power; in particular, optimally selected regularization (e.g., by cross-validation or even at the true sparsity level) on the precision matrices with small estimation errors may have low power. Most importantly, and perhaps surprisingly, using either correlations or partial correlations may give very different testing results, depending on which of the covariance matrices and the precision matrices are sparse. Specifically, if the precision matrices are sparse, presumably and arguably a reasonable assumption, then using correlations often yields much higher powered and more stable testing results than using partial correlations; the conclusion is reversed if the covariance matrices, not the precision matrices, are sparse. These results may have useful implications to future studies on testing functional connectivity differences. PMID:25492804

  11. DNA-Templated Functional Group Transformations Enable Sequence-Programmed Synthesis Using Small-Molecule Reagents

    E-print Network

    Liu, David R.

    the progress of these reactions, the putative amine products were captured with 20-mer-linked carboxylic acids in the presence of a carbodiimide, or with 20-mer-linked aldehydes in the presence of NaBH3CN. These secondary

  12. Inhibition of a medium chain acyl-CoA synthetase involved in glycine conjugation by carboxylic acids.

    PubMed

    Kasuya, F; Igarashi, K; Fukui, M

    1996-11-22

    Molecular characteristics of carboxylic acids were investigated for the ability to inhibit a purified medium chain acyl-CoA synthetase, using hexanoic acid as a substrate. Salicylic acid, 4-methylsalicylic acid, 2-hydroxynaphtoic acid, and 2-hydroxyoctanoic acid, which do not act as substrates for the medium chain acyl-CoA synthetase, were potent as inhibitors. Valproic acid was not an inhibitor. Salicylic acid, 2-hydroxynaphthoic acid, and 2-hydroxyoctanoic acid inhibited the medium chain acyl-CoA synthetase with Ki values of 37, 5.2, and 500 microM, respectively. 4-Methylsalicylic acid was more potent than salicylic acid. The inhibitory carboxylic acids were competitive with respect to hexanoic acid. The distance of the hydroxyl group from the carboxylic acid group of the benzene ring influenced the inhibitory activity. The hydroxyl group on the carbon adjacent to the carboxylic acid group was required for inhibitory activity. In addition, there was a good correlation between the lipophilicity of the carboxylic acids and the Ki values, suggesting that the lipophilicity of the carboxylic acids is a major determinant for inhibition of the medium chain acyl-CoA synthetase. PMID:8937481

  13. Crystal structure of 9-(4-bromo­but­yl)-9H-fluorene-9-carb­oxy­lic acid

    PubMed Central

    Zhang, Xu-Yang; Liu, Bing-Ni; Wang, Ping-Bao; Liu, Deng-Ke

    2014-01-01

    The title compound, C18H17BrO2, is a key inter­mediate in the synthesis of lomitapide mesylate, a microsomal triglyceride transfer protein inhibitor. Its asymmetric unit contains two independent mol­ecules with slightly different conformations; the mean planes of the 4-bromo­butyl and carboxyl­ate groups in the two mol­ecules form dihedral angles of 24.54?(12) and 17.10?(18)°. In the crystal, carboxyl­ate groups are involved in O—H?O hydrogen bonding, which leads to the formation of two crystallographically independent centrosymmetric dimers. Weak inter­molecular C—H?O inter­actions further link these dimers into layers parallel to the bc plane. PMID:25484705

  14. Evolutionary patterns of group B Sox binding and function in Drosophila

    E-print Network

    Carl, Sarah Hamilton

    2015-04-07

    and Episkopou, 1999; Wegner and Stolt, 2005). Group B Sox genes have also been analyzed at both sequence and expression levels in several species of invertebrates, showing strong evidence for functional conservation but also revealing a complex evolutionary... be simply translated from vertebrates to invertebrates. In the mouse, the group B1 genes Sox2 and Sox3 as well as the group C gene Sox11 are expressed in a suc- cessive fashion in the developing CNS; a recent ChIP-seq study examined binding patterns of Sox2...

  15. Isolation and Characterization of Functional Tripartite Group II Introns Using a Tn5-Based Genetic Screen

    PubMed Central

    Ritlop, Christine; Monat, Caroline; Cousineau, Benoit

    2012-01-01

    Background Group II introns are RNA enzymes that splice themselves from pre-mRNA transcripts. Most bacterial group II introns harbour an open reading frame (ORF), coding for a protein with reverse transcriptase, maturase and occasionally DNA binding and endonuclease activities. Some ORF-containing group II introns were shown to be mobile retroelements that invade new DNA target sites. From an evolutionary perspective, group II introns are hypothesized to be the ancestors of the spliceosome-dependent nuclear introns and the small nuclear RNAs (snRNAs – U1, U2, U4, U5 and U6) that are important functional elements of the spliceosome machinery. The ability of some group II introns fragmented in two or three pieces to assemble and undergo splicing in trans supports the theory that spliceosomal snRNAs evolved from portions of group II introns. Methodology/Principal Findings We used a transposon-based genetic screen to explore the ability of the Ll.LtrB group II intron from the Gram-positive bacterium Lactococcus lactis to be fragmented into three pieces in vivo. Trans-splicing tripartite variants of Ll.LtrB were selected using a highly efficient and sensitive trans-splicing/conjugation screen. We report that numerous fragmentation sites located throughout Ll.LtrB support tripartite trans-splicing, showing that this intron is remarkably tolerant to fragmentation. Conclusions/Significance This work unveils the great versatility of group II intron fragments to assemble and accurately trans-splice their flanking exons in vivo. The selected introns represent the first evidence of functional tripartite group II introns in bacteria and provide experimental support for the proposed evolutionary relationship between group II introns and snRNAs. PMID:22876289

  16. Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets

    SciTech Connect

    Saykally, Richard J; Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; Drisdell, Walter S.; Cohen, Ronald C.; Saykally, Richard J.

    2008-01-08

    We describe an approach for characterizing selective binding between oppositely charged ionic functional groups under biologically relevant conditions. Relative shifts in K-shell x-ray absorption spectra of aqueous cations and carboxylate anions indicate the corresponding binding strengths via perturbations of carbonyl antibonding orbitals. XAS spectra measured for aqueous formate and acetate solutions containing lithium, sodium, and potassium cations reveal monotonically stronger binding of the lighter metals, supporting recent results from simulations and other experiments. The carbon K-edge spectra of the acetate carbonyl feature centered near 290 eV clearly indicate a preferential interaction of sodium versus potassium, which was less apparent with formate. These results are in accord with the Law of Matching Water Affinities, relating relative hydration strengths of ions to their respective tendencies to form contact ion pairs. Density functional theory calculations of K-shell spectra support the experimental findings.

  17. Rh(III)-Catalyzed Decarboxylative Coupling of Acrylic Acids with Unsaturated Oxime Esters: Carboxylic Acids Serve as Traceless Activators

    PubMed Central

    2015-01-01

    ?,?-Unsaturated carboxylic acids undergo Rh(III)-catalyzed decarboxylative coupling with ?,?-unsaturated O-pivaloyl oximes to provide substituted pyridines in good yield. The carboxylic acid, which is removed by decarboxylation, serves as a traceless activating group, giving 5-substituted pyridines with very high levels of regioselectivity. Mechanistic studies rule out a picolinic acid intermediate, and an isolable rhodium complex sheds further light on the reaction mechanism. PMID:24512241

  18. Organic functional group transformations in water at elevated temperature and pressure: Reversibility, reactivity, and mechanisms

    NASA Astrophysics Data System (ADS)

    Shipp, Jessie; Gould, Ian R.; Herckes, Pierre; Shock, Everett L.; Williams, Lynda B.; Hartnett, Hilairy E.

    2013-03-01

    Many transformation reactions involving hydrocarbons occur in the presence of H2O in hydrothermal systems and deep sedimentary systems. We investigate these reactions using laboratory-based organic chemistry experiments at high temperature and pressure (300 °C and 100 MPa). Organic functional group transformation reactions using model organic compounds based on cyclohexane with one or two methyl groups provided regio- and stereochemical markers that yield information about reversibility and reaction mechanisms. We found rapidly reversible interconversion between alkanes, alkenes, dienes, alcohols, ketones, and enones. The alkane-to-ketone reactions were not only completely reversible, but also exhibited such extensive reversibility that any of the functional groups along the reaction path (alcohol, ketone, and even the diene) could be used as the reactant and form all the other groups as products. There was also a propensity for these ring-based structures to dehydrogenate; presumably from the alkene, through a diene, to an aromatic ring. The product suites provide strong evidence that water behaved as a reactant and the various functional groups showed differing degrees of reactivity. Mechanistically-revealing products indicated reaction mechanisms that involve carbon-centered cation intermediates. This work therefore demonstrates that a wide range of organic compound types can be generated by abiotic reactions at hydrothermal conditions.

  19. Quantum group symmetry of partition functions of IRF models and its application to Jones' index theory

    NASA Astrophysics Data System (ADS)

    Hayashi, Takahiro

    1993-10-01

    For each Boltzmann weight of a face model, we associate two quantum groups (face algebras) which describe the dependence of the partition function on boundary value condition. Using these, we give a proof of (non-)flatness of A-D-E connections of A. Ocneanu, which is a crucial algebraic part of the classification of subfactors with Jones' index less than 4.

  20. Roars of black howler monkeys (Alouatta caraya): evidence for a function in inter-group spacing

    E-print Network

    Roars of black howler monkeys (Alouatta caraya): evidence for a function in inter-group spacing) Summary Loud calls can be expected to play an important role in the lives of howler monkeys, given the specialised anatomy of howler vocal apparatus and the time and energy invested in call- ing. Here we present

  1. Detecting Native Language Group Differences at the Subskills Level of Reading: A Differential Skill Functioning Approach

    ERIC Educational Resources Information Center

    Li, Hongli; Suen, Hoi K.

    2013-01-01

    Differential skill functioning (DSF) exists when examinees from different groups have different probabilities of successful performance in a certain subskill underlying the measured construct, given that they have the same ability on the overall construct. Using a DSF approach, this study examined the differences between two native language…

  2. Group B Streptococcal b-Hemolysin/Cytolysin Directly Impairs Cardiomyocyte Viability and Function

    E-print Network

    Nizet, Victor

    , United States of America Abstract Background: Group B Streptococcus (GBS) is a leading cause of neonatal and later induced necrotic and apoptotic cell death. No effects on cardiomyocyte viability or function were with complete and rapid loss of detectable calcium transients in primary neonatal rat ventricular cardiomyocytes

  3. Cosmological constraints from the virial mass function of nearby galaxy groups and clusters

    E-print Network

    Hill, James Colin

    2008-01-01

    In this thesis, I present a new determination of the cluster mass function in a volume ~107 h-03 70 Mpc3 using the ROSAT-2MASS-FAST Group Survey (R2FGS). R2FGS is an X-ray-selected sample of systems from the ROSAT All-Sky ...

  4. Review of Social Skills Training Groups for Youth with Asperger Syndrome and High Functioning Autism

    ERIC Educational Resources Information Center

    Cappadocia, M. Catherine; Weiss, Jonathan A.

    2011-01-01

    Although social skills deficits represent core symptoms of Asperger Syndrome and High Functioning Autism, there is limited research investigating the empirical validity of social skills interventions currently being used with these populations. This literature review compares three types of social skills training groups: traditional, cognitive…

  5. Social Resources and Change in Functional Health: Comparing Three Age Groups

    ERIC Educational Resources Information Center

    Randall, G. Kevin; Martin, Peter; Bishop, Alex J.; Johnson, Mary Ann; Poon, Leonard W.

    2012-01-01

    This study examined the mediating and moderating role of social resources on the association between age and change in functional health for three age groups of older adults. Data were provided by those in their 60s, 80s, and 100s who participated in the first two phases of the Georgia Centenarian study. Analyses confirmed the study's hypothesis…

  6. Ants as bioindicators of habitat disturbance: validation of the functional group model

    E-print Network

    to the World Heritage rainforests of Queensland's humid tropics has not yet been validated. Here we test predictions based on the functional group model for ant commu- nities in Queensland's humid rainforests rainforest types, and three previously cleared sites, two of which were undergoing revegetation. A variety

  7. Simple plant traits explain functional group diversity decline in novel grassland communities of Texas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent work on novel ecosystems suggests that exotic species contribute to functional group diversity decline as exotic systems replace native ones. We experimentally compared 18 exotic and 18 native prairie species paired for phylogeny, growth form, and mode of photosynthesis grown both in monocul...

  8. Department and function: Institute for Virology; Group leader (Cell & Virus Genetics)

    E-print Network

    Manstein, Dietmar J.

    Department and function: Institute for Virology; Group leader (Cell & Virus Genetics) Education: 2002 PhD in Biology (Virology), University Heidelberg Positions: 2003-2006: Postdoc at the department for Virology Major research interests: Retroviral gene expression on the RNA level Mutations in cellular genes

  9. Department and function: Group leader (Institute of Medical Microbiology and Hospital

    E-print Network

    Manstein, Dietmar J.

    Department and function: Group leader (Institute of Medical Microbiology and Hospital Epidem.) Education: 1996 PhD in Biology (Microbiology/Biochemistry/Cell Biology), Ruhr-University Bochum, Germany 2003 Habilitation in Medical Microbiology, University of Würzburg, Germany Positions: 1998-1999: Junior

  10. Variation in tropical forest growth rates: combined effects of functional group composition and resource availability

    Microsoft Academic Search

    Timothy R. Baker; Michael D. Swaine; David F. R. P. Burslem

    2003-01-01

    Rates of tree growth in tropical forests reflect variation in life history strategies, contribute to the determination of species' distributional limits, set limits to timber harvesting and control the carbon balance of the stands. Here, we review the resources that limit tree growth at different temporal and spatial scales, and the different growth rates and responses of functional groups defined

  11. The superstability of d'Alembert's functional equation on the Heisenberg group

    Microsoft Academic Search

    B. Bouikhalene; E. Elqorachi; J. M. Rassias

    2010-01-01

    In this paper, we investigate the superstability of d’Alembert’s functional equation f(ab)+f(ai(b))=2f(a)f(b),a,b?H, where H is the Heisenberg group and the map i:H?H is an automorphism of H such that i?i=id (the identity map).

  12. [Methods of psychological compatibility evaluation of military personnel in the formation of small functional groups].

    PubMed

    Ivashchenko, S M

    2008-01-01

    The article presents the technique of definition of psychological compatibility of military personnel depending on accentuation of type of their personality to optimize the process of formation of small functional groups for performance of service tasks during daily activity of military persons. PMID:19663023

  13. Discussion Groups and Their Tutors: Relationships between Tutor Characteristics and Tutor Functioning.

    ERIC Educational Resources Information Center

    De Volder, M. L.

    1982-01-01

    Small group learning monitored by tutors is an essential ingredient of medical education at Limburg State University. Tutor functioning was assessed by students and found to be related to tutor expertise in subject matter under discussion but not to tutor age or experience. (Author/MSE)

  14. A FUNCTIONAL GROUP CHARACTERIZATION OF ORGANIC PM 2.5 EXPOSURE: RESULTS FROM THE RIOPA STUDY

    EPA Science Inventory

    The functional group (FG) composition of urban residential outdoor, indoor, and personal fine particle (PM2.5) samples is presented and used to provide insights relevant to organic PM2.5 exposure. PM2.5 samples (48 h) were collected during the Rel...

  15. Group-Specific Effects of Matching Subtest Contamination on the Identification of Differential Item Functioning

    ERIC Educational Resources Information Center

    Keiffer, Elizabeth Ann

    2011-01-01

    A differential item functioning (DIF) simulation study was conducted to explore the type and level of impact that contamination had on type I error and power rates in DIF analyses when the suspect item favored the same or opposite group as the DIF items in the matching subtest. Type I error and power rates were displayed separately for the…

  16. Impacts of chronic nitrogen additions vary seasonally and by microbial functional group in tundra soils

    Microsoft Academic Search

    S. K. Schmidt; D. A. Lipson; R. E. Ley; M. C. Fisk; A. E. West

    2004-01-01

    Previous studies have shown that fertilization with nitrogen depresses overall microbial biomass and activity in soil. In the present study we broaden our understanding of this phenomenon by studying the seasonality of responses of specific microbial functional groups to chronic nitrogen additions in alpine tundra soils. We measured soil enzyme activities, mineralization kinetics for 8 substrates, biomass of 8 microbial

  17. Chemical functionalization of carbon nano tube

    NASA Astrophysics Data System (ADS)

    Pisal, S. H.; Harale, N. S.; Pawar, S. A.; Deshamukh, H. P.; Patil, P. S.

    2013-06-01

    It is well known that carbon nanotubes do not represent significant reinforcement for composite but once functionalized it shows interesting new properties. In the present paper MWCNTs were initially chemically treated with mixture of 3:1 (v/v) of concentrated H2SO4/HNO3. This treatment modifies the surface of MWCNT but it has not disrupted its main structure. This acid treatment introducing the carboxylic acid groups only at defect sites and end of CNTs, then this carboxylic acid groups were first converted to acyl chlorides by using Thionyl chloride. Further this Chlorinated CNTs were functionalized with p-phenylenediamine to form amide bond that kept a long chain attached. The functionalized procedure was characterized by using Raman spectroscopy and scanning electron microscopy.

  18. Study on amino-functionalized multiwalled carbon nanotubes

    Microsoft Academic Search

    Jianfeng Shen; Weishi Huang; Liping Wu; Yizhe Hu; Mingxin Ye

    2007-01-01

    Functionalization with amine groups of MWNTs was achieved after such steps as carboxylation, acylation and amidation. XRD, Raman, FTIR, XPS, scanning electron microscopy (SEM) were used to investigate and determine the chemical structure and texture of the amino-functionalized MWNTs. By comparing with each other, it was found that the amino-functionalized MWNTs can improve their dispersion in H2O. However, concerning the

  19. Photoluminescent calcium azolium carboxylates with diversified calcium coordination geometry and thermal stability.

    PubMed

    Suresh, Paladugu; Babu, Chatla Naga; Sampath, Natarajan; Prabusankar, Ganesan

    2015-04-28

    Despite the popularity and versatility of transition-metal–azolium carboxylate coordination polymers, there are very few examples of group 2 complexes supported by azolium carboxylate ligands in the literature, and there are none featuring luminescent calcium azolium carboxylates. New ionic calcium coordination networks, {[Ca2(L(1))2(H2O)4](Br)4·6H2O}? (1), {[(L(3))2Ca(H2O)2]2(Br)2}? (3), {[(L(4))2Ca(H2O)2]2(Br)2}? (4), and {[(L(5))2Ca3(Na)(H2O)9(Cl)](Br)6·2H2O}? (5) along with binuclear {[Ca2(L(2))2(H2O)9](Br)4·4H2O} (2), and trinuclear {[(L(6))2Ca3(H2O)9](Br)6} (6) were isolated from the reaction between the corresponding azolium carboxylates and calcium carbonate in aqueous solution. 1–6 were characterized by FT-IR, NMR, TGA, UV-vis, fluorescence and single crystal X-ray diffraction techniques. Interestingly, the first tetra-cationic binuclear calcium 2 was isolated using L(2)H2Br2 and hexa-cationic trinuclear calcium 6 was isolated using L(6)H3Br3. The 3D coordination polymers 1 and 4 were derived with the help of L(1)H2Br2 and L(4)H2Br2, respectively, through Br···H hydrogen bonding. The 3D MOF 3 with rhomboidal channels was constructed using L(3)H2Br2, where the channel size is about 4.8 × 2.9 nm. 5 was isolated as a rare 1D coordination polymer. The choice of azolium carboxylates in these solids not only changes the topology of the network but also affects the chemistry exhibited by the network. Calcium azolium carboxylate assemblies 1–4 and 6 exhibit interesting solid-state photoluminescence properties, driven by azolium carboxylate ligands. Variation of the bridging chromophore produced significant effects on the fluorescence properties. 1–4 and 6 represent the first examples of luminescent calcium azolium carboxylate complexes. As can be seen in the six metal–organic assemblies presented in this report, a combination of carboxylate groups and steric hindrance affects the topology and physical properties of the resultant solids. PMID:25797947

  20. Kinetics of Silica Nucleation on Carboxyl-and Amine-Terminated Surfaces: Insights for Biomineralization

    E-print Network

    Dove, Patricia M.

    Kinetics of Silica Nucleation on Carboxyl- and Amine-Terminated Surfaces: Insights measure the kinetics of silica nucleation on model biosubstrates under chemical conditions that mimic as surrogates for charged and ionizable groups on silica-mineralizing organic matrices. The data show that amine

  1. Fate of Octyl- and Nonylphenol Ethoxylates and Some Carboxylated Derivatives in Three American Wastewater Treatment Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fate of a comprehensive group of nonylphenol and octylphenol ethoxylates and several of their carboxylated derivatives was studied in three American wastewater treatment plants (WWTPs), two of which included advanced treatment. In spite of being located in three different metropolitan areas, wa...

  2. Development of Acid Functional Groups and Lactones During the Thermal Degradation of Wood and Wood Components

    USGS Publications Warehouse

    Rutherford, David W.; Wershaw, Robert L.; Reeves, James B., III

    2008-01-01

    Black carbon (pyrogenic materials including chars) in soils has been recognized as a substantial portion of soil organic matter, and has been shown to play a vital role in nutrient cycling; however, little is known concerning the properties of this material. Previous studies have largely been concerned with the creation of high-surface-area materials for use as sorbents. These materials have been manufactured at high temperature and have often been activated. Chars occurring in the environment can be formed over a wide range of temperature. Because it is extremely difficult to isolate black carbon once it has been incorporated in soils, chars produced in the laboratory under controlled conditions can be used to investigate the range of properties possible for natural chars. This report shows that charring conditions (temperature and time) have substantial impact on the acid functional group and lactone content of chars. Low temperatures (250?C) and long charring times (greater than 72 hours) produce chars with the highest acid functional group and lactone content. The charring of cellulose appears to be responsible for the creation of the acid functional group and lactones. The significance of this study is that low-temperature chars can have acid functional group contents comparable to humic materials (as high as 8.8 milliequivalents per gram). Acid functional group and lactone content decreases as charring temperature increases. The variation in formation conditions expected under natural fire conditions will result in a wide range of sorption properties for natural chars which are an important component of soil organic matter. By controlling the temperature and duration of charring, it is possible to tailor the sorption properties of chars, which may be used as soil amendments.

  3. Determination of carboxylic acids in oil samples by capillary gas chromatography/mass spectrometry

    SciTech Connect

    Shen, J.

    1981-03-01

    A combined gas chromatography/mass spectrometric (GC/MS) method for measuring carboxylic acids in oil samples without first going through solvent extraction and group separation is reported. The carboxylic acids in oils are directly derivatized to their corresponding methyl esters via anion formation in tetramethylammonium hydroxide/methanol/methyl iodide/n-butyl acetate solutions prior to GC/MS analysis using a glass wall coated capillary column. The reaction is mild, selective, and rapid. It can usually be carried out at room temperature and completed in 10 to 15 min. Multiple ion detection techniques (MID) can be readily used to further resolve methyl esters from other compounds if necessary.

  4. Ion chromatography of organic carboxylic acids. Determination of monobasic carboxylic and hydroxy acids

    SciTech Connect

    Ivanov, A.A.; Shpigun, O.A.; Zolotov, Yu.A.

    1986-07-10

    An ion chromatographic method has been developed for the determination of monobasic carboxylic and hydroxy acids, as well as some of their chloroderivatives. The optimum eluent for the joint determination of monobasic carboxylic and hydroxy acids, fluoride and chloride ions is a 1 x 10/sup -4/ M solution of NaOH. The limit of detection of acids with this eluent is equal to (1.5-3.1) x 10/sup -3/ ..mu..g/ml. Inorganic anions (F/sup -/, Cl/sup -/, NO/sub 3//sup -/, and SO/sub 4//sup 2 -/), as well as dibasic carboxylic and hydroxy acids, do not interfere with the determination of monobasic carboxylic and hydroxy acids. The method has been used for the determination of lactic acid in gastric juice and that of formic, acetic, propionic, and butyric acids in water and condensate of thermoelectric power plants.

  5. Wetting properties of model interphases coated with defined organic functional groups

    NASA Astrophysics Data System (ADS)

    Woche, Susanne K.; Goebel, Marc-O.; Guggenberger, Georg; Tunega, Daniel; Bachmann, Joerg

    2013-04-01

    Surface properties of soil particles are of particular interest regarding transport of water and sorption of solutes, especially hazardous xenobiotic species. Wetting properties (e.g. determined by contact angle, CA), governed by the functional groups exposed, are crucial to understand sorption processes in water repellent soils as well as for the geometry of water films sustaining microbial processes on the pore scale. Natural soil particle surfaces are characterized by a wide variety of mineralogical and chemical compounds. Their composition is almost impossible to identify in full. Hence, in order to get a better understanding about surface properties, an option is the usage of defined model surfaces, whereas the created surface should be comparable to natural soil interphases. We exposed smooth glass surfaces to different silane compounds, resulting in a coating covalently bound to the surface and exhibiting defined organic functional groups towards the pore space. The wetting properties as evaluated by CA and the surface free energy (SFE), calculated according to the Acid-Base Theory, were found to be a function of the specific functional group. Specifically, the treated surfaces showed a large variation of CA and SFE as function of chain length and polarity of the organic functional group. The study of wetting properties was accompanied by XPS analysis for selective detection of chemical compounds of the interphase. As the reaction mechanism of the coating process is known, the resulting interphase structure can be modeled based on energetic considerations. A next step is to use same coatings for the defined modification of the pore surfaces of porous media to study transport and sorption processes in complex three phase systems.

  6. Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups

    SciTech Connect

    Fifield, Leonard S.; Grate, Jay W.

    2010-06-01

    Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.

  7. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Alkenyl carboxylate, metal salt (generic). 721.2093 Section 721...721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance...generically as alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to...

  8. Production of carboxylic acid and salt co-products

    DOEpatents

    Hanchar, Robert J.; Kleff, Susanne; Guettler, Michael V.

    2014-09-09

    This invention provide processes for producing carboxylic acid product, along with useful salts. The carboxylic acid product that is produced according to this invention is preferably a C.sub.2-C.sub.12 carboxylic acid. Among the salts produced in the process of the invention are ammonium salts.

  9. Synthesis, structural investigations, and anti-cancer activity of new methyl indole-3-carboxylate derivatives

    NASA Astrophysics Data System (ADS)

    Niemyjska, Maria; Maciejewska, Dorota; Wolska, Irena; Truszkowski, Pawe?

    2012-10-01

    Two new methyl indole-3-carboxylate derivatives: methyl 1-(3'-indolylmethane)-indole-3-carboxylate (1), and methyl 1-(1'-benzenosulfonyl-3'-indolylmethane)-indole-3-carboxylate (2) were synthesized. They are interesting as the analogs of 3,3'-diindolylmethane, which is intensively tested as a potent antitumor agent. Their solid-state structure was characterized using 13C CP/MAS NMR or X-ray diffraction measurements. Molecular modeling was used as a help in the structure elucidation. The solid-state NMR spectroscopy showed only one stable conformer of 1, but the X-ray diffraction results indicate that compound 2 crystallizes in the triclinic space group P-1 with two molecules, A and B, in the asymmetric unit. Both compounds inhibited the growth of melanoma, renal and breast cancers cell lines.

  10. Discovery of a Novel Series of CRTH2 (DP2) Receptor Antagonists Devoid of Carboxylic Acids

    PubMed Central

    2011-01-01

    Antagonism of the CRTH2 receptor represents a very attractive target for a variety of allergic diseases. Most CRTH2 antagonists known to date possess a carboxylic acid moiety, which is essential for binding. However, potential acid metabolites O-acyl glucuronides might be linked to idiosynchratic toxicity in humans. In this communication, we describe a new series of compounds that lack the carboxylic acid moiety. Compounds with high affinity (Ki < 10 nM) for the receptor have been identified. Subsequent optimization succeeded in reducing the high metabolic clearance of the first compounds in human and rat liver microsomes. At the same time, inhibition of the CYP isoforms was optimized, giving rise to stable compounds with an acceptable CYP inhibition profile (IC50 CYP2C9 and 2C19 > 1 ?M). Taken together, these data show that compounds devoid of carboxylic acid groups could represent an interesting alternative to current CRTH2 antagonists in development. PMID:24900284

  11. Functionalization of carbon nanotubes with -CHn, -NHn fragments, -COOH and -OH groups

    NASA Astrophysics Data System (ADS)

    Milowska, Karolina Z.; Majewski, Jacek A.

    2013-05-01

    We present results of extensive theoretical studies concerning stability, morphology, and band structure of single wall carbon nanotubes (CNTs) covalently functionalized by -CHn (for n = 2,3,4), -NHn (for n = 1,2,3,4), -COOH, and -OH groups. These studies are based on ab initio calculations in the framework of the density functional theory. For functionalized systems, we determine the dependence of the binding energies on the concentration of the adsorbed molecules, critical densities of adsorbed molecules, global and local changes in the morphology, and electronic structure paying particular attention to the functionalization induced changes of the band gaps. These studies reveal physical mechanisms that determine stability and electronic structure of functionalized systems and also provide valuable theoretical predictions relevant for application. In particular, we observe that functionalization of CNTs causes generally their elongation and locally sp2 to sp3 rehybridization in the neighborhood of chemisorbed molecules. For adsorbants making particularly strong covalent bonds with the CNTs, such as the -CH2 fragments, we observe formation of the characteristic pentagon/heptagon (5/7) defects. In systems functionalized with the -CH2, -NH4, and -OH groups, we determine critical density of molecules that could be covalently bound to the lateral surface of CNTs. Our studies show that functionalization of CNTs can be utilized for band gap engineering. Functionalization of CNTs can also lead to changes in their metallic/semiconductor character. In semiconducting CNTs, functionalizing molecules such as -CH3, -NH2, -OH, -COOH, and both -OH and -COOH, introduce "impurity" bands in the band gap of pristine CNTs. In the case of -CH3, -NH2 molecules, the induced band gaps are typically smaller than in the pure CNT and depend strongly on the concentration of adsorbants. However, functionalization of semiconducting CNTs with hydroxyl groups leads to the metallization of CNTs. On the other hand, the functionalization of semi-metallic (9,0) CNT with -CH2 molecules causes the increase of the band gap and induces semi-metall to semiconductor transition.

  12. Perceived Access to Reinforcers as a Function of Alcohol Consumption Among One First Nations Group

    PubMed Central

    Spillane, Nichea S.; Smith, Gregory T.; Kahler, Christopher W.

    2014-01-01

    Background Spillane & Smith (2007) postulated that high levels of problem drinking in some First Nation (FN) communities resulted in part from the perception that there is low access to alternative reinforcers (e.g., jobs, friendships, family relationships, and financial security), that many alternative reinforcers are less contingent on sobriety, and that others are available regardless of drinking status for reserve-dwelling FN members. Methods This study examined perceptions of access to alternative reinforcers and the extent to which access varied as a function of drinking in 211 FN members living on one reserve in Canada, 138 middle-socioeconomic status Caucasians (MCC), and 98 low-socioeconomic status Caucasians (LCC). Results The FN group expected less access to employment, quality family and friend relationships, and financial security compared to the MCC group. After controlling for perceived access in general, gender, and age, the FN group reported that drinking would not cause a decrease in access to employment, family relationships, friendships, and finances as compared to the MCC group. The FN group did not differ from the LCC group in the degree to which they expected drinking to cost access to family relationships or finances, but the LCC group expected drinking to have less of an impact on access to jobs and friendships as compared to the FN group. Conclusions The results provide initial support for the Spillane and Smith theory of problem drinking among this one First Nation Group. The results suggest that increasing access to these reinforcers may reduce problematic drinking in this First Nation group. PMID:22823415

  13. Fossil group origins V. The dependence of the luminosity function on the magnitude gap

    E-print Network

    Zarattini, S; Sanchez-Janssen, R; Barrena, R; Boschin, W; del Burgo, C; Castro-Rodriguez, N; Corsini, E M; D'Onghia, E; Girardi, M; Iglesias-Paramo, J; Kundert, A; Mendez-Abreu, J; Vilchez, J M

    2015-01-01

    In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system ($\\Delta m_{12}$). There are systems with gaps close to zero (e.g., the Coma cluster), and at the other extreme of the distribution, the largest gaps are found among the so-called fossil systems. Fossil and non-fossil systems could have different galaxy populations that should be reflected in their luminosity functions. In this work we study, for the first time, the dependence of the luminosity function parameters on $\\Delta m_{12}$ using data obtained by the fossil group origins (FOGO) project. We constructed a hybrid luminosity function for 102 groups and clusters at $z \\le 0.25$. We stacked all the individual luminosity functions, dividing them into bins of $\\Delta m_{12}$, and studied their best-fit Schechter parameters. We additionally computed a relative luminosity function, expressed as a function of the central galaxy luminosity, which boosts our capacity to detect differ...

  14. Transient binding of CO to Cu(B) in cytochrome c oxidase is dynamically linked to structural changes around a carboxyl group: a time-resolved step-scan Fourier transform infrared investigation.

    PubMed Central

    Heitbrink, Dirk; Sigurdson, Håkan; Bolwien, Carsten; Brzezinski, Peter; Heberle, Joachim

    2002-01-01

    The redox-driven proton pump cytochrome c oxidase is that enzymatic machinery of the respiratory chain that transfers electrons from cytochrome c to molecular oxygen and thereby splits molecular oxygen to form water. To investigate the reaction mechanism of cytochrome c oxidase on the single vibrational level, we used time-resolved step-scan Fourier transform infrared spectroscopy and studied the dynamics of the reduced enzyme after photodissociation of bound carbon monoxide across the mid-infrared range (2300-950 cm(-1)). Difference spectra of the bovine complex were obtained at -20 degrees C with 5 micros time resolution. The data demonstrate a dynamic link between the transient binding of CO to Cu(B) and changes in hydrogen bonding at the functionally important residue E(I-286). Variation of the pH revealed that the pK(a) of E(I-286) is >9.3 in the fully reduced CO-bound oxidase. Difference spectra of cytochrome c oxidase from beef heart are compared with those of the oxidase isolated from Rhodobacter sphaeroides. The bacterial enzyme does not show the environmental change in the vicinity of E(I-286) upon CO dissociation. The characteristic band shape appears, however, in redox-induced difference spectra of the bacterial enzyme but is absent in redox-induced difference spectra of mammalian enzyme. In conclusion, it is demonstrated that the dynamics of a large protein complex such as cytochrome c oxidase can be resolved on the single vibrational level with microsecond Fourier transform infrared spectroscopy. The applied methodology provides the basis for future investigations of the physiological reaction steps of this important enzyme. PMID:11751290

  15. Spectroscopic and electrochemical properties of group 12 acetates of di-2-pyridylketone thiophene-2-carboxylic acid hydrazone (dpktch-H) complexes. The structure of [Cd(?3-N,N,O-dpktch-H)2

    NASA Astrophysics Data System (ADS)

    Bakir, Mohammed; Lawrence, Mark A. W.; McBean, Shameal

    2015-07-01

    The reaction between [dpktch] and [M(OAc)2] (M = group 12 metal atom) in refluxing CH3CN gave [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O (n = 0 or 1). The infrared and 1H NMR spectra are consistent with the coordination of [?2-O,O-OAc] and [?3-N,N,O-dpktch-H]- and the proposed formulations. The electronic absorption spectra of [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O measured in non-aqueous solvents revealed a highly intense intra-ligand-charge transfer (ILCT) transition due to ?-?? of dpk followed by dpk ? thiophene charge transfer. The electronic transitions of [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O are solvent and concentration dependent. Spectrophotometric titrations of dmso solutions of [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O with benzoic acid revealed irreversible inter-conversion between [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O and it conjugate acid [M(?2-O,O-OAc)(?3-N,N,O-dpktch)]·nH2O pointing to ligand exchange between the acetate and benzoate anions. When CH2Cl2 solutions of [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O were titrated with dmso, changes appeared pointing to solvolysis or ligand exchange reactions. Electrochemical measurements on dmso solutions of [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O divulged irreversible redox transformations consistent with electrochemical decomposition of [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O. The solid state structure of a single crystal of [Cd(?3-N,N,O-dpktch-H)2] obtained from a dmso solution of [Cd(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O confirmed the ligand scrambling of [M(?2-O,O-OAc)(?3-N,N,O-dpktch-H)]·nH2O. The extended structure of [Cd(?3-N,N,O-dpktch-H)2] revealed stacks of [Cd(?3-N,N,O-dpktch-H)2] locked via a network of hydrogen bonds. A significant amount of empty space (35.5%) was observed in the solid state structure of [Cd(?3-N,N,O-dpktch-H)2].

  16. Quantity of Hydrophobic Functional CH-Groups - Decisive for Soil Water Repellency Caused by Digestate Amendment

    NASA Astrophysics Data System (ADS)

    Voelkner, Amrei; Holthusen, Dörthe; Ellerbrock, Ruth H.; Horn, Rainer

    2015-04-01

    Anaerobic digestates are used as organic fertilizers; however, they are suspected to interfere negatively with soils. To investigate the relevance of the anaerobic digestates composition on potential wettability and contact angle of the soil, we mixed in a laboratory experiment 30 m³ ha-1 of anaerobic digestates derived from mechanically pre-treated substrates from maize and sugar beet with a homogenized Cambic Luvisol. Fourier transform infrared-spectra and diffuse reflectance infrared Fourier transform-spectra of particle intact and finely ground soilanaerobic digestates-mixtures were analyzed to determine the quantities of hydrophobic functional groups in the soil-anaerobic digestates-mixtures that are used here as an indicator for the potential hydrophobicity. The anaerobic digestates application increased the amount of hydrophobic functional groups of the mixtures and reduced the wettability of the soil. However, for intact particle samples an up to threefold higher amount of hydrophobic groups was found as compared to the finely ground ones, indicating a dilution effect of mechanical grinding on the effectivity of the organic matter that is presumably located as a coating on mineral soil particles. For the particle intact samples, the intensity of hydrophobic functional groups bands denoting hydrophobic brickstones in organic matter is indicative for the actual wettability of the soil-anaerobic digestates-mixtures.

  17. Random matrix theory, the exceptional Lie groups, and L-functions

    E-print Network

    J. P. Keating; N. Linden; Z. Rudnick

    2002-10-30

    There has recently been interest in relating properties of matrices drawn at random from the classical compact groups to statistical characteristics of number-theoretical L-functions. One example is the relationship conjectured to hold between the value distributions of the characteristic polynomials of such matrices and value distributions within families of L-functions. These connections are here extended to non-classical groups. We focus on an explicit example: the exceptional Lie group G_2. The value distributions for characteristic polynomials associated with the 7- and 14-dimensional representations of G_2, defined with respect to the uniform invariant (Haar) measure, are calculated using two of the Macdonald constant term identities. A one parameter family of L-functions over a finite field is described whose value distribution in the limit as the size of the finite field grows is related to that of the characteristic polynomials associated with the 7-dimensional representation of G_2. The random matrix calculations extend to all exceptional Lie groups

  18. Infrared Multiple-Photon Dissociation spectroscopy of group II metal complexes with salicylate

    SciTech Connect

    Ryan P. Dain; Gary Gresham; Gary S. Groenewold; Jeffrey D. Steill; Jos Oomens; Michael J. van Stipdonk

    2011-07-01

    Ion-trap tandem mass spectrometry with collision-induced dissociation, and the combination of infrared multiple-photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) calculations were used to characterize singly-charged, 1:1 complexes of Ca2+, Sr2+ and Ba2+ with salicylate. For each metal-salicylate complex, the CID pathways are: (a) elimination of CO2 and (b) formation of [MOH]+ where M=Ca2+, Sr2+ or Ba2+. DFT calculations predict three minima for the cation-salicylate complexes which differ in the mode of metal binding. In the first, the metal ion is coordinated by O atoms of the (neutral) phenol and carboxylate groups of salicylate. In the second, the cation is coordinated by phenoxide and (neutral) carboxylic acid groups. The third mode involves coordination by the carboxylate group alone. The infrared spectrum for the metal-salicylate complexes contains a number of absorptions between 1000 – 1650 cm-1, and the best correlation between theoretical and experimental spectra for the structure that features coordination of the metal ion by phenoxide and the carbonyl group of the carboxylic acid group, consistent with calculated energies for the respective species.

  19. Azetidine- and N-carboxylic azetidine-iminosugars as amyloglucosidase inhibitors: synthesis, glycosidase inhibitory activity and molecular docking studies.

    PubMed

    Gavale, Kishor S; Chavan, Shrawan R; Khan, Ayesha; Joshi, Rakesh; Dhavale, Dilip D

    2015-06-21

    A simple strategy for the synthesis of hitherto unknown azetidine iminosugars 2a-2c and N-carboxylic azetidine iminosugar 2d has been reported. The methodology involves the conversion of 1,2:5,6-di-O-isopropylidene-3-oxo-?-d-glucofuranose 3 to 3-azido-3-deoxy-3-C-(formyl)-1,2:5,6-di-O-isopropylidene-?-d-glucofuranose 5 using the Jocic-Reeve and Corey-Link approaches. Compound 5 was transformed to 5-OTs 10/5-OMs 19 derivatives that on intramolecular nucleophilic displacement with in situ generated 3-amino functionality afforded the key azetidine ring skeletons 11 and 20, respectively. Hydrolysis of the 1,2-acetonide group and manipulation of the anomeric carbon in 12 provided azetidine iminosugars 2a-2c. In an attempt to synthesize azetidine iminosugars with an additional 4-hydroxymethyl group from 20, we encountered an interesting observation wherein the N-Cbz group in 20 hydrolyzed to the N-COOH functionality under TFA?:?H2O conditions that gave access for the synthesis of N-carboxylic azetidine iminosugar 2d. The glycosidase inhibitory activity of 2a-2d and intermediates 2e-f was studied with various glycosidases and was compared with Miglitol and 1-deoxynojirimycin (DNJ). Azetidine iminosugars 2 were found to inhibit amyloglucosidase with competitive type inhibition, amongst which 2d was found to be more active than Miglitol and DNJ. These results were substantiated by in silico molecular docking studies. PMID:25990982

  20. Control of oxo-group functionalization and reduction of the uranyl ion.

    PubMed

    Arnold, Polly L; Pécharman, Anne-Frédérique; Lord, Rianne M; Jones, Guy M; Hollis, Emmalina; Nichol, Gary S; Maron, Laurent; Fang, Jian; Davin, Thomas; Love, Jason B

    2015-04-01

    Uranyl complexes of a large, compartmental N8-macrocycle adopt a rigid, "Pacman" geometry that stabilizes the U(V) oxidation state and promotes chemistry at a single uranyl oxo-group. We present here new and straightforward routes to singly reduced and oxo-silylated uranyl Pacman complexes and propose mechanisms that account for the product formation, and the byproduct distributions that are formed using alternative reagents. Uranyl(VI) Pacman complexes in which one oxo-group is functionalized by a single metal cation are activated toward single-electron reduction. As such, the addition of a second equivalent of a Lewis acidic metal complex such as MgN?2 (N? = N(SiMe3)2) forms a uranyl(V) complex in which both oxo-groups are Mg functionalized as a result of Mg-N bond homolysis. In contrast, reactions with the less Lewis acidic complex [Zn(N?)Cl] favor the formation of weaker U-O-Zn dative interactions, leading to reductive silylation of the uranyl oxo-group in preference to metalation. Spectroscopic, crystallographic, and computational analysis of these reactions and of oxo-metalated products isolated by other routes have allowed us to propose mechanisms that account for pathways to metalation or silylation of the exo-oxo-group. PMID:25799215

  1. Biofuel purification in zeolitic imidazolate frameworks: the significant role of functional groups.

    PubMed

    Zhang, Kang; Nalaparaju, Anjaiah; Chen, Yifei; Jiang, Jianwen

    2014-05-28

    A molecular simulation study is reported for biofuel purification in six zeolitic imidazolate frameworks (ZIF-8, -25, -71, -90, -96 and -97) with different functional groups. For pure ethanol and water, the predicted adsorption isotherms agree fairly well with experimental data. Hydrogen bonding has an important effect on the adsorption of ethanol and water. In hydrophilic ZIFs (ZIF-90, -96 and -97) with polar groups, adsorption capacities are higher than in hydrophobic counterparts (ZIF-8, -25 and -71). The atomic charges in symmetrically functionalized ZIF-8, -25, and -71 are found to have an indiscernible effect on adsorption, in remarkable contrast to asymmetrically functionalized ZIF-90, -96 and -97. For ethanol-water mixtures representing the biofuel, the selectivity of ethanol-water drops with increasing ethanol in mixtures. It is revealed that the selectivity is determined primarily by framework hydrophobicity as well as the cage size. Among the six ZIFs, ZIF-8 exhibits the highest selectivity. This simulation study provides a microscopic insight into the adsorption of ethanol and water in various ZIFs, reveals the significant role of functional groups in governing biofuel purification, and would facilitate the development of new nanoporous materials for high-efficacy liquid separation. PMID:24727907

  2. Use of carboxylated cellulose nanofibrils-filled magnetic chitosan hydrogel beads as adsorbents for Pb(II).

    PubMed

    Zhou, Yiming; Fu, Shiyu; Zhang, Liangliang; Zhan, Huaiyu; Levit, Mikhail V

    2014-01-30

    Novel magnetic hydrogel beads (m-CS/PVA/CCNFs), consisting of carboxylated cellulose nanofibrils (CCNFs), amine-functionalized magnetite nanoparticles and poly(vinyl alcohol) (PVA) blended chitosan (CS), were prepared by an instantaneous gelation method. SEM, XRD, and TGA techniques were applied to investigate the structure of the hydrogel materials. The magnetic hydrogels were employed as absorbents for removal of Pb(II) ions from aqueous solutions and the fundamental adsorption behavior was studied. Experimental results revealed that the m-CS/PVA/CCNFs hydrogels exhibit higher adsorption capacity with the value of 171.0mg/g, and the carboxylate groups on the CCNFs surface play an important role in Pb(II) adsorption. Moreover, adsorption isotherm data were reliably described by the Langmuir model and the adsorption kinetics closely followed pseudo-second order model. Additionally, the Pb(II)-loaded m-CS/PVA/CCNFs hydrogels could be easily regenerated in weak acid solution and the adsorption effectiveness of 90% can be maintained after the 4 cycles. PMID:24299751

  3. Growth and Electrophysiological Properties of Rat Embryonic Cardiomyocytes on Hydroxyl- and Carboxyl-Modified Surfaces

    PubMed Central

    NATARAJAN, ANUPAMA; CHUN, CHANGJU; HICKMAN, JAMES J.; MOLNAR, PETER

    2010-01-01

    Biodegradable scaffolds such as poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) or poly(glycolic acid) (PGA) are commonly used materials in tissue engineering. The chemical composition of these scaffolds changes during degradation which provides a changing environment for the seeded cells. In this study we have developed a simple and relatively high-throughput method in order to test the physiological effects of this varying chemical environment on rat embryonic cardiac myocytes. In order to model the different degradation stages of the scaffold, glass coverslips were functionalized with 11-mercaptoundecanoic acid (MUA) and 11-mercapto-1-undecanol (MUL) as carboxyl- and hydroxyl-group presenting surfaces and also with trimethoxysilylpropyldiethylenetriamine (DETA) and (3-aminopropyl)triethoxysilane (APTES) as controls. Embryonic cardiac myocytes formed beating islands on all tested surfaces but the number of attached cells and beating patches was significantly lower on MUL compared to any of the other functionalized surfaces. Moreover, whole cell patch clamp experiments showed that the average length of action potentials generated by the beating cardiac myocytes were significantly longer on MUL compared to the other surfaces. Our results, using our simple test system, are in agreement with earlier observations that utilized the complex 3D biodegradable scaffold. Thus, surface functionalization with self-assembled monolayers combined with histological/physiological testing could be a relatively high throughput method for biocompatibility studies and for the optimization of the material/tissue interface in tissue engineering. PMID:18854125

  4. Simple thiol-ene click chemistry modification of SBA-15 silica pores with carboxylic acids.

    PubMed

    Bordoni, Andrea V; Lombardo, M Verónica; Regazzoni, Alberto E; Soler-Illia, Galo J A A; Wolosiuk, Alejandro

    2015-07-15

    A straightforward approach for anchoring tailored carboxylic groups in mesoporous SiO2 colloidal materials is presented. The thiol-ene photochemical reaction between vinyltrimethoxysilane precursors and various thiocarboxylic acids which has, click chemistry features (i.e. high conversion yields, insensitivity to oxygen, mild reaction conditions), results in carboxylated silane precursors that can be readily used as surface modifiers. The carboxylic groups of acetic, undecanoic and succinic acid were immobilized on the silica mesopore walls of SBA-15 powders employing the synthesized silane precursors. Post-grafting has been confirmed through infrared spectrometry (FTIR), energy dispersive X-ray spectroscopy (EDS), elemental analysis (EA) and zeta potential measurements. Detailed field-emission gun scanning electron microscopy (FESEM) images and small angle X-ray scattering (SAXS) data revealed parallel mesopores and ordered mesostructures. It is shown that the immobilized COOH groups are chemically accessible for acid-base reactions as well as copper adsorption. Immobilization of easily synthesized tailored carboxylic modified alkoxide precursors within mesoporous systems provides a unique chemical nanoenvironment within these ordered frameworks. PMID:25845883

  5. Study of quantitative structure–mobility relationship of carboxylic and sulphonic acids in capillary electrophoresis

    Microsoft Academic Search

    Chunxia Xue; Huanxiang Liu; Xiaojun Yao; Mancang Liu; Zhide Hu; Botao Fan

    2004-01-01

    A quantitative structure–mobility relationship (QSMR) was developed for the absolute mobilities of 115 carboxylic and sulphonic acids in capillary electrophoresis based on the descriptors calculated from the structure alone. The heuristic method (HM) and radial basis function neural networks (RBFNN) were utilized to construct the linear and nonlinear prediction models, respectively. The prediction results were in agreement with the experimental

  6. Does a Functioning Mind Need a Functioning Body? 307 Copyright 2005, Idea Group Inc. Copying or distributing in print or electronic forms without written

    E-print Network

    Kent, University of

    Does a Functioning Mind Need a Functioning Body? 307 Copyright © 2005, Idea Group Inc. Copying 14. Does a Functioning Mind Need a FunctioningBody? Some Perspectives from Postclassical Computation that are generated by mind and then reperceived and acted upon. This chapter considers the somatic marker hypothesis

  7. Influence of Organic Functional Groups on the Electrical Properties of Carbon Black: A Theoretical Study

    NASA Astrophysics Data System (ADS)

    Chutia, Arunabhiram; Zhu, Zhigang; Sahnoun, Riadh; Tsuboi, Hideyuki; Koyama, Michihisa; Hatekeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Del Carpio, Carlos A.; Miyamoto, Akira

    2008-04-01

    In the present investigation methods based on tight-binding approximation (TBA) and density functional theory (DFT) were employed to investigate the electronic properties of carbon black. The influence of organic functional groups (OFGs) such as -OH and -CHO in the basic structural units (BSUs) of carbon black was studied. It was seen that with the substitution of OFGs in the pristine graphene layers the energy gaps decreased. The changes in energy gaps associated with the topological association of OFGs were also investigated. The change of energy gaps associated with the topological association among the OFGs and with the graphene moieties was seen to be marginal.

  8. Impact of Nanotopography and/or Functional Groups on Periodontal Ligament Cell Growth

    NASA Astrophysics Data System (ADS)

    ?a?mazel, Hilal Türko?lu; Manolache, S.; Gümü?derel?o?lu, M.

    The main purpose of this contribution was to obtain COOH functionalities and/or nanotopographic changes on the surface of 3D, non-woven polyester fabric (NWPF) discs (12.5 mm in diameter) by using low pressure water/O2 plasma assisted treatments. The prepared discs were characterized by various methods after the plasma treatment. Periodontal ligament (PDL) fibroblasts were used in cell culture studies. The cell culture results showed that plasma treated 3D NWPF discs are favorable for PDL cell spreading, growth and viability due to the presence of functional groups and/or the nanotopography of their surfaces.

  9. Reductive carboxylation of propionate to butyrate in methanogenic ecosystems.

    PubMed

    Tholozan, J L; Samain, E; Grivet, J P; Moletta, R; Dubourguier, H C; Albagnac, G

    1988-02-01

    During the batch degradation of sodium propionate by the anaerobic sludge from an industrial digestor, we observed a significant amount of butyrate formation. Varying the initial propionate concentrations did not alter the ratio of maximal butyrate accumulation to initial propionate concentration within a large range. By measuring the decrease in the radioactivity of [1-C]butyrate during propionate degradation, we estimated that about 20% of the propionate was converted to butyrate. Labeled butyrate was formed from [1-C]propionate with the same specific radioactivity, suggesting a possible direct pathway from propionate to butyrate. We confirmed this hypothesis by nuclear magnetic resonance studies with [C]propionate. The results showed that [1-C]-, [2-C]-, and [3-C]propionate were converted to [2-C]-, [3-C]-, and [4-C]butyrate, respectively, demonstrating the direct carboxylation on the carboxyl group of propionate without randomization of the other two carbons. In addition, we observed an exchange reaction between C-2 and C-3 of the propionate, indicating that acetogensis may proceed through a randomizing pathway. The physiological significance and importance of various metabolic pathways involved in propionate degradation are discussed, and an unusual pathway of butyrate synthesis is proposed. PMID:16347557

  10. Effects of acidic functional groups on dielectric properties of sodium alginates and carrageenans in water.

    PubMed

    Tsubaki, Shuntaro; Hiraoka, Masanori; Hadano, Shingo; Okamura, Kei; Ueda, Tadaharu; Nishimura, Hiroshi; Kashimura, Keiichiro; Mitani, Tomohiko

    2015-01-22

    This study investigated the dielectric properties of sodium alginates and carrageenans in water at frequencies between 100 MHz and 20 GHz in regard to water-hydrocolloid interactions via acidic functional groups. Both sodium alginates and carrageenans showed conduction loss at lower frequencies and dielectric loss at higher frequencies. Reduction and desulfation of sodium alginates and carrageenans, which decreased the numbers of acidic functional groups, decreased their conduction loss. In addition, H(+)-form carrageenans showed the highest ionic conduction. Correlational analysis of dielectric properties and related physical parameters showed that the loss tangent (tan?) of the hydrocolloid solution was determined by the conductivity of the aqueous solution. Especially at pH below 2, strong H(+) conduction was associated with high tan? probably due to the Grotthuss mechanism. The molecular dynamics of free water and H(+), viscosity conditions were also suggested to be associated with dielectric property of water-hydrocolloid system. PMID:25439871

  11. The Luminosity Function of the Fossil Group RX J1552.2+2013

    NASA Astrophysics Data System (ADS)

    Mendes de Oliveira, Claudia L.; Cypriano, Eduardo S.; Sodré, Laerte, Jr.

    2006-01-01

    We determine the first fossil group luminosity function based on spectroscopy of the member galaxies. The fossil group RX J1552.2+2013 has 36 confirmed members, is at a mean redshift of 0.136, and has a velocity dispersion of 623 km s-1 (or 797 km s-1 if four emission-line galaxies in the outskirts of the velocity distribution are included). The luminosity function of RX J1552.2+2013, measured within the inner region of the system (~1/3Rvir) in the range -23.5function with M*i'=-21.3+/-0.4 and ?=-0.6+/-0.3 or by a Gaussian function centered on Mi'=-20.0+/-0.4 with ?=1.29+/-0.24 i' mag (H0=70 km s-1 Mpc-1, ?M=0.3, and ??=0.7). The luminosity function obtained from a photometric survey in the g', r', and i' bands (and statistical background correction) confirms the spectroscopically determined results. There is a significant dip in the luminosity function at Mr'=-18 mag, as is also observed for other clusters. RX J1552.2+2013 is a rich, red-galaxy-dominated system, with at least 19 galaxies with magnitudes between m3 and m3+2, within a surveyed circular area of radius 625 h-170 kpc centered on the peak of the X-ray emission. Its mass, ~3×1014 Msolar, M/L of 507 Msolar/LBsolar, and LX of 6.3×1043 h-250 ergs s-1 (bolometric) are more representative of a fossil cluster than of a fossil group. The central object of RX J1552.2+2013 is a cD galaxy that may have accreted the more luminous (~L*) former members of the group. Although dynamical friction and subsequent merging are probably the processes responsible for the lack of bright galaxies in the system, for the fainter members there must be another mechanism in action (perhaps tidal disruption) to deplete intermediate-luminosity galaxies (Mr'~-18) from the fossil group. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under a cooperative agreement with the National Science Foundation (NSF) on behalf of the Gemini partnership: the NSF (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina). Observing run ID: GN-2004B-Q-47.

  12. Pattern Classification and Recognition of Invertebrate Functional Groups Using Self-Organizing Neural Networks

    Microsoft Academic Search

    WenJun Zhang

    2007-01-01

    Self-organizing neural networks can be used to mimic non-linear systems. The main objective of this study is to make pattern\\u000a classification and recognition on sampling information using two self-organizing neural network models. Invertebrate functional\\u000a groups sampled in the irrigated rice field were classified and recognized using one-dimensional self-organizing map and self-organizing\\u000a competitive learning neural networks. Comparisons between neural network models,

  13. ?-Diversity of Functional Groups of Woody Plants in a Tropical Dry Forest in Yucatan

    PubMed Central

    López-Martínez, Jorge Omar; Sanaphre-Villanueva, Lucía; Dupuy, Juan Manuel; Hernández-Stefanoni, José Luis; Meave, Jorge Arturo; Gallardo-Cruz, José Alberto

    2013-01-01

    Two main theories have attempted to explain variation in plant species composition (?-diversity). Niche theory proposes that most of the variation is related to environment (environmental filtering), whereas neutral theory posits that dispersal limitation is the main driver of ?-diversity. In this study, we first explored how ?- and ?-diversity of plant functional groups defined by growth form (trees, shrubs and lianas, which represent different strategies of resource partitioning), and dispersal syndrome (autochory, anemochory and zoochory, which represent differences in dispersal limitation) vary with successional age and topographic position in a tropical dry forest. Second, we examined the effects of environmental, spatial, and spatially-structured environmental factors on ?-diversity of functional groups; we used the spatial structure of sampling sites as a proxy for dispersal limitation, and elevation, soil properties and forest stand age as indicators of environmental filtering. We recorded 200 species and 22,245 individuals in 276 plots; 120 species were trees, 41 shrubs and 39 lianas. We found that ?-diversity was highest for shrubs, intermediate for lianas and lowest for trees, and was slightly higher for zoochorous than for autochorous and anemochorous species. All three dispersal syndromes, trees and shrubs varied in composition among vegetation classes (successional age and topographic position), whilst lianas did not. ?-diversity was influenced mostly by proxies of environmental filtering, except for shrubs, for which the influence of dispersal limitation was more important. Stand age and topography significantly influenced ?-diversity across functional groups, but showed a low influence on ?-diversity –possibly due to the counterbalancing effect of resprouting on plant distribution and composition. Our results show that considering different plant functional groups reveals important differences in both ?- and ?-diversity patterns and correlates that are not apparent when focusing on overall woody plant diversity, and that have important implications for ecological theory and biodiversity conservation. PMID:24040014

  14. Small functional groups for controlled differentiation of hydrogel-encapsulated human mesenchymal stem cells

    Microsoft Academic Search

    Danielle S. W. Benoit; Michael P. Schwartz; Andrew R. Durney; Kristi S. Anseth

    2008-01-01

    Cell-matrix interactions have critical roles in regeneration, development and disease. The work presented here demonstrates that encapsulated human mesenchymal stem cells (hMSCs) can be induced to differentiate down osteogenic and adipogenic pathways by controlling their three-dimensional environment using tethered small-molecule chemical functional groups. Hydrogels were formed using sufficiently low concentrations of tether molecules to maintain constant physical characteristics, encapsulation of

  15. Small functional groups for controlled differentiation of hydrogel-encapsulated human mesenchymal stem cells

    Microsoft Academic Search

    Danielle S. W. Benoit; Michael P. Schwartz; Andrew R. Durney; Kristi S. Anseth

    2008-01-01

    Cell–matrix interactions have critical roles in regeneration, development and disease. The work presented here demonstrates that encapsulated human mesenchymal stem cells (hMSCs) can be induced to differentiate down osteogenic and adipogenic pathways by controlling their three-dimensional environment using tethered small-molecule chemical functional groups. Hydrogels were formed using sufficiently low concentrations of tether molecules to maintain constant physical characteristics, encapsulation of

  16. Predicting Drug-Target Interaction Networks Based on Functional Groups and Biological Features

    Microsoft Academic Search

    Zhisong He; Jian Zhang; Xiao-He Shi; Le-Le Hu; Xiangyin Kong; Yu-Dong Cai; Kuo-Chen Chou; Ramy K. Aziz

    2010-01-01

    BackgroundStudy of drug-target interaction networks is an important topic for drug development. It is both time-consuming and costly to determine compound-protein interactions or potential drug-target interactions by experiments alone. As a complement, the in silico prediction methods can provide us with very useful information in a timely manner.Methods\\/Principal FindingsTo realize this, drug compounds are encoded with functional groups and proteins

  17. Geometry of q-Hypergeometric Functions, Quantum Affine Algebras and Elliptic Quantum Groups

    Microsoft Academic Search

    Vitaly Tarasov; Alexander Varchenko

    1997-01-01

    The trigonometric quantized Knizhnik-Zamolodchikov equation (qKZ equation) associated with the quantum group $U_q(sl_2)$ is a system of linear difference equations with values in a tensor product of $U_q(sl_2)$ Verma modules. We solve the equation in terms of multidimensional $q$-hypergeometric functions and define a natural isomorphism between the space of solutions and the tensor product of the corresponding evaluation Verma modules

  18. Two types of meta-crystals for IV group elements: Density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Wu, Jianbao; Zhang, Weiyi; Mi, Yiming; Zhang, Chaoming

    2013-02-01

    Using density function theory (DFT) implemented in VASP package, we find two new type of meta-crystals constructed by IV group elements: Si-568 and Ge-568. The calculational results show that Si-568 has a band gap of 0.09 eV estimated by DFT, while Ge-568 behaves metallic. These two new types of nano-structures both can be created via experimentally observed di-vacancies (DVs) and Stone-Thrower-Wales (STW) defect.

  19. A functional group characterization of organic PM2.5 exposure: Results from the RIOPA study

    Microsoft Academic Search

    Adam Reffa; Barbara J. Turpinb; John H. Offenbergd; Clifford P. Weiselc; Jim Zhangc; Maria Morandie; Thomas Stocke; Steven Colomef; Arthur Winerg

    The functional group (FG) composition of urban residential outdoor, indoor, and personal fine particle (PM2.5) samples is presented and used to provide insights relevant to organic PM2.5 exposure. PM2.5 samples (48 h) were collected during the Relationship of Indoor, Outdoor, and Personal Air (RIOPA) study at 219 non-smoking homes (once or twice) in Los Angeles County, CA, Elizabeth, NJ, and

  20. A functional group characterization of organic PM 2.5 exposure: Results from the RIOPA study

    Microsoft Academic Search

    Adam Reff; Barbara J. Turpin; John H. Offenberg; Clifford P. Weisel; Jim Zhang; Maria Morandi; Thomas Stock; Steven Colome; Arthur Winer

    2007-01-01

    The functional group (FG) composition of urban residential outdoor, indoor, and personal fine particle (PM2.5) samples is presented and used to provide insights relevant to organic PM2.5 exposure. PM2.5 samples (48h) were collected during the Relationship of Indoor, Outdoor, and Personal Air (RIOPA) study at 219 non-smoking homes (once or twice) in Los Angeles County, CA, Elizabeth, NJ, and Houston,

  1. Isoperimetric and Isodiametric Functions of Groups Mark V. Sapir, JeanCamille Birget, Eliyahu Rips \\Lambda

    E-print Network

    Sapir, Mark

    an isoperimetric function of a finite presentation P = hX j Ri of a group G if for every number n and every word w over X which is equal to 1 in G, jwj Ÿ n, there exists a van Kampen diagram over P whose boundary label = hX j Ri if for every number n and every word w over X which is equal to 1 in G, jwj Ÿ n

  2. Lung toxicity and biodistribution of Cd/Se-ZnS quantum dots with different surface functional groups after pulmonary exposure in rats

    PubMed Central

    2013-01-01

    Background The potential use of quantum dots (QD) in biomedical applications, as well as in other systems that take advantage of their unique physiochemical properties, has led to concern regarding their toxicity, potential systemic distribution, and biopersistence. In addition, little is known about workplace exposure to QD in research, manufacturing, or medical settings. The goal of the present study was to assess pulmonary toxicity, clearance, and biodistribution of QD with different functional groups in rats after pulmonary exposure. Methods QD were composed of a cadmium-selenide (CdSe) core (~5nm) with a zinc sulfide (ZnS) shell functionalized with carboxyl (QD-COOH) or amine (QD-NH2) terminal groups. Male Sprague–Dawley rats were intratracheally-instilled (IT) with saline, QD-COOH, or QD-NH2 (12.5, 5.0, or 1.25 ?g/rat). On days 0, 1, 3, 5, 7, 14, and 28 post-IT, the left lung, lung-associated lymph nodes (LALN), heart, kidneys, spleen, liver, brain, and blood were collected for metal analysis of Cd content by neutron activation to evaluate clearance and biodistribution. One right lobe was ligated and fixed for microscopy and histopathological analysis. The remaining right lobes from rats in each group were subjected to bronchoalveolar lavage (BAL) to retrieve BAL fluid and cells for analysis of injury and inflammation. Results Lung injury and inflammation was found to be dose-dependent and peaked at days 7 and 14 post-exposure for both forms of QD, with slight variations in degree of toxicity at early and later time points. Both QD appeared to lose their fluorescent properties and destabilize after 1 week in the lung. Cd persisted up to 28 days for both forms of QD; however, clearance rate was slightly greater for QD-COOH over time. No Cd was detected in the liver, spleen, heart, brain, or blood at any time point. Cd appeared in the LALN and kidneys beginning at 1–2 weeks post-exposure. Conclusions QD-COOH and QD-NH2 differed in clearance rate and differed slightly in degree of toxicity at different time points; however, the overall pattern of toxicity and biodistribution was similar between the two particles. Toxicity may be dependent on the dissolution rate and bioavailability of free Cd. PMID:23497258

  3. Two group I ribozymes with different functions in a nuclear rDNA intron.

    PubMed Central

    Decatur, W A; Einvik, C; Johansen, S; Vogt, V M

    1995-01-01

    DiSSU1, a mobile intron in the nuclear rRNA gene of Didymium iridis, was previously reported to contain two independent catalytic RNA elements. We have found that both catalytic elements, renamed GIR1 and GIR2, are group I ribozymes, but with differing functionality. GIR2 carries out the several reactions associated with self-splicing. GIR1 carries out a hydrolysis reaction at an internal processing site (IPS-1). These conclusions are based on the catalytic properties of RNAs transcribed in vitro. Mutation of the P7 pairing segment of GIR2 abrogated self-splicing, while mutation of P7 in GIR1 abrogated hydrolysis at the IPS-1. Much of the P2 stem and all of the associated loop could be deleted without effect on self-splicing. These results are accounted for by a secondary structure model, in which a long P2 pairing segment brings the 5' splice site to the GIR2 catalytic core. GIR1 is the smallest natural group I ribozyme yet reported and is the first example of a group I ribozyme whose presumptive biological function is hydrolysis. We hypothesize that GIR1-mediated cleavage of the excised intron RNA functions in the generation and expression of the mRNA for the intron-encoded endonuclease I-DirI. Images PMID:7556099

  4. Algae as hosts for epifaunal bryozoans: Role of functional groups and taxonomic relatedness

    NASA Astrophysics Data System (ADS)

    Liuzzi, María G.; López Gappa, Juan

    2011-01-01

    Macroalgae build biogenic habitats which give shelter and provide a suitable physical environment for a great variety of organisms. Structural complexity of algal substrates may influence the composition of their attached epifauna. The aim of this study is to test whether the taxonomic relatedness of the algal hosts and the functional groups to which they belong influence the species richness and composition of their epifaunal bryozoans. We analysed 36 algal genera from the Atlantic coast of South America between 42°S and Cape Horn. Changes in bryozoan species richness (number of species) among different algal functional groups (filamentous algae, foliose algae, corticated foliose algae, corticated macrophytes) were non-significant. The composition of the epifaunal assemblages differed significantly only between filamentous and foliose algae. Sheet-like bryozoans (i.e. encrusting, pluriserial colonies) were more frequent on foliose than on filamentous algae, while runner-like species (i.e. uniserial stolons) were characteristic epibionts on filamentous thallii. Similarity of bryozoan assemblages increased with increasing taxonomic relatedness of their hosts. As most filamentous seaweeds analysed in this study are members of the Order Ceramiales, the influence of algal taxonomic relatedness and functional groups on the composition of their bryozoan assemblages can be viewed as two different aspects of the same phenomenon.

  5. Spectroscopic study on uranyl carboxylate complexes formed at the surface layer of Sulfolobus acidocaldarius.

    PubMed

    Reitz, Thomas; Rossberg, Andre; Barkleit, Astrid; Steudtner, Robin; Selenska-Pobell, Sonja; Merroun, Mohamed L

    2015-02-14

    The complexation of U(vi) at the proteinaceous surface layer (S-layer) of the archaeal strain Sulfolobus acidocaldarius was investigated over a pH range from pH 1.5 to 6 at the molecular scale using time-resolved laser-induced fluorescence spectroscopy (TRLFS) and U L(III)-edge extended X-ray absorption fine structure (EXAFS). The S-layer, which represents the interface between the cell and its environment, is very stable against high temperatures, proteases, and detergents. This allowed the isolation and purification of S-layer ghosts (= empty cells) that maintain the size and shape of the cells. In contrast to many other microbial cell envelope compounds the studied S-layer is not phosphorylated, enabling the investigation of uranyl carboxylate complexes formed at microbial surfaces. The latter are usually masked by preferentially formed uranyl phosphate complexes. We demonstrated that at highly acidic conditions (pH 1.5 to 3) no uranium was bound by the S-layer. In contrast to that, at moderate acidic pH conditions (pH 4.5 and 6) a complexation of U(vi) at the S-layer via deprotonated carboxylic groups was stimulated. Titration studies revealed dissociation constants for the carboxylic groups of glutamic and aspartic acid residues of pK(a) = 4.78 and 6.31. The uranyl carboxylate complexes formed at the S-layer did not show luminescence properties at room temperature, but only under cryogenic conditions. The obtained luminescence maxima are similar to those of uranyl acetate. EXAFS spectroscopy demonstrated that U(vi) in these complexes is mainly coordinated to carboxylate groups in a bidentate binding mode. The elucidation of the molecular structure of these complexes was facilitated by the absence of phosphate groups in the studied S-layer protein. PMID:25387060

  6. Sulfhydryl-group modifications of Torpedo Californica acetylcholine receptor: subunit localization and effects on function

    SciTech Connect

    McNamee, M.G.; Yee, A.S.

    1986-05-01

    The effects of thiol-group modification on acetylcholine receptor (ACHR) function were measured using purified Torpedo ACHR reconstituted into soybean lipid vesicles. N-Phenyl-maleimide (NPM) was used to modify sulfhydryl groups in ACHR in the absence of any prior reduction by dithiotheitol. Modification by NPM led to the inhibition of ion channel activity without a detectable effect on ligand binding. The ion flux inhibition by NPM primarily affected channel activation, since the initial rates of activation decreased over a wide range of carbamylcholine concentrations. The /sup 3/H-NPM subunit labelling pattern of ACHR (a multisubunit membrane protein with ..cap alpha../sub 2/..beta gamma..delta stoichiometry) revealed preferential labelling of the ..gamma.. subunit. At high NPM concentration, the number of sulfhydryl groups on the ..gamma.. subunit that could be modified with NPM was two. Detergent was required during labelling for functionally relevant thiol group modifications, and most of the label was protected from protease digestion in the reconstituted membranes. These results are consistent with the presence of the NPM modification in a bilayer and/or cytoplasmic domain. Analysis of cyanogen bromide and trypsin fragments indicates that the labeled cysteines may be located in the postulated amphipathic helix region of the ..gamma.. subunit.

  7. Molecular weight distribution and functional group profiles of TEMPO-oxidized lyocell fibers.

    PubMed

    Milanovic, Jovana; Schiehser, Sonja; Milanovic, Predrag; Potthast, Antje; Kostic, Mirjana

    2013-10-15

    The effects of TEMPO-mediated oxidation, performed with NaClO, a catalytic amount of NaBr, and 2,2',6,6'-tetramethylpiperidine-1-oxy radical (TEMPO), were studied on lyocell fibers by means of GPC using multiple detection and group-selective fluorescence labeling according to the CCOA and FDAM methodology. The applied method determines functional group content as a sum parameter, as well as functional group profiles in relation to the molecular weight of the cellulose fibers. Both the CHO and COOH profiles, as well as molecular weight alterations, were analyzed. A significant decrease in the average molecular weight was obtained during the first hour of TEMPO-mediated oxidation, but prolonged oxidation time resulted in no strong additional chain scission. Significant amounts of COOH groups were introduced in the high molecular weight fractions by the oxidation with higher concentrations of NaClO (2.42-9.67 mmol NaClO/g fiber) after modification times of 1h or longer. PMID:23987366

  8. Crystal structure of ethyl 2-amino-4-(4-meth­oxy­phen­yl)-4H-1-benzothieno[3,2-b]pyran-3-carboxyl­ate

    PubMed Central

    Bakhouch, Mohamed; Kerbal, Abdelali; El Yazidi, Mohamed; Saadi, Mohamed; El Ammari, Lahcen

    2015-01-01

    The mol­ecule of the title compound, C21H19NO4S, features a fused ring system whereby a five-membered ring is flanked by two six-membered rings. This is linked to an ethyl 3-carboxyl­ate group and to a meth­oxy­benzene group. The fused-ring system is quasi-planar, with the greatest deviation from the mean plane being 0.131?(1)?Å for the methine C atom. The plane through the meth­oxy­benzene ring is nearly perpendicular to that through the fused-ring system, as indicated by the dihedral angle of 85.72?(6)°. An intra­molecular N—H?O hydrogen bond is noted. In the crystal, mol­ecules are linked by N—H?O hydrogen bonds, forming layers that stack along the a axis. PMID:25995952

  9. Identifying functional groups for response to disturbance in an abandoned pasture

    NASA Astrophysics Data System (ADS)

    Lavorel, Sandra; Touzard, Blaise; Lebreton, Jean-Dominique; Clément, Bernard

    1998-06-01

    In an abandoned pasture in Brittany, we compared artificial small-scale disturbances to natural disturbances by wild boar and undisturbed vegetation. We developed a multivariate statistical approach which analyses how species biological attributes explain the response of community composition to disturbances. This technique, which reconciles the inductive and deductive approaches for functional classifications, identifies groups of species with similar responses to disturbance and characterizes their biological profiles. After 5 months of recolonization, artificial disturbances had a greater species richness than undisturbed vegetation as a result of recruitment of new species without the exclusion of pre-existing matrix species. Species morphology, described by canopy structure, canopy height and lateral spread, explained a large part (16 %) of community response to disturbance. Regeneration strategies, described by life history, seed mass, dispersal agent, dormancy and the existence of vegetative multiplication, explained a smaller part of community response to disturbance (8 %). Artificial disturbances were characterized by therophyte and compact rosettes with moderately dormant seeds, including a number of Asteraceae and other early successional species. Natural disturbances were colonized by leafy guerrilla species without seed dormancy. Few species were tightly related to undisturbed vegetation and were essentially grasses with a phalanx rosette morphology. The functional classification obtained is consistent with the classification of the community into fugitives, regenerators and persistors. These groups are structured according to Grubb's model for temperate grasslands, with regenerators and persistors in the matrix and fugitives taking advantage of gaps open by small-scale disturbances. The conjunction of functional diversity and species diversity within functional groups is the key to resilience to disturbance, an important ecosystem function.

  10. Functionalized quantum dots induce proinflammatory responses in vitro: the role of terminal functional group-associated endocytic pathways

    NASA Astrophysics Data System (ADS)

    Zhang, Yijuan; Pan, Hong; Zhang, Pengfei; Gao, Ningning; Lin, Yi; Luo, Zichao; Li, Ping; Wang, Ce; Liu, Lanlan; Pang, Daiwen; Cai, Lintao; Ma, Yifan

    2013-06-01

    PEGylation has been applied as an effective strategy of surface functionalization to improve the stability and reduce non-specific binding of quantum dots (QDs). However, its effects on the proinflammatory properties of QDs and the underlying mechanism have not been well elucidated yet. Herein, the proinflammatory effects of PEGylated CdSe/ZnS QDs with an amphiphilic polymer coating (PEG-pQDs) were investigated in human pulmonary epithelial cells and macrophages by evaluating the cytokine/chemokine production. The results showed that the proinflammatory effects of PEG-pQDs were strongly associated with the functional groups (-COOH, -NH2, -OH, and -OCH3) at the end of PEG chain. COOH-PEG-pQDs demonstrated the most proinflammatory effects followed by NH2-PEG-pQDs and HO-PEG-pQDs with CH3O-PEG-pQDs exhibiting the least proinflammatory effects. The proinflammatory effects of PEG-pQDs relied on lipid raft- and class A scavenger receptor (SRA)-dependent endocytic pathways as well as the downstream NF-?B and MAPK signaling cascades. COOH-PEG-pQDs were selectively internalized by lipid raft- and SRA-mediated endocytosis, which consequently activated NF-?B signaling pathway. On the other hand, NH2-PEG-pQDs and HO-PEG-pQDs were mostly internalized via lipid raft-mediated endocytosis, thereby activating p38 MAPK/AP-1 signaling cascades. These data revealed a critical role of terminal functional group-associated endocytic pathways in the proinflammatory responses induced by PEGylated QDs in human pulmonary epithelial cells and macrophages.PEGylation has been applied as an effective strategy of surface functionalization to improve the stability and reduce non-specific binding of quantum dots (QDs). However, its effects on the proinflammatory properties of QDs and the underlying mechanism have not been well elucidated yet. Herein, the proinflammatory effects of PEGylated CdSe/ZnS QDs with an amphiphilic polymer coating (PEG-pQDs) were investigated in human pulmonary epithelial cells and macrophages by evaluating the cytokine/chemokine production. The results showed that the proinflammatory effects of PEG-pQDs were strongly associated with the functional groups (-COOH, -NH2, -OH, and -OCH3) at the end of PEG chain. COOH-PEG-pQDs demonstrated the most proinflammatory effects followed by NH2-PEG-pQDs and HO-PEG-pQDs with CH3O-PEG-pQDs exhibiting the least proinflammatory effects. The proinflammatory effects of PEG-pQDs relied on lipid raft- and class A scavenger receptor (SRA)-dependent endocytic pathways as well as the downstream NF-?B and MAPK signaling cascades. COOH-PEG-pQDs were selectively internalized by lipid raft- and SRA-mediated endocytosis, which consequently activated NF-?B signaling pathway. On the other hand, NH2-PEG-pQDs and HO-PEG-pQDs were mostly internalized via lipid raft-mediated endocytosis, thereby activating p38 MAPK/AP-1 signaling cascades. These data revealed a critical role of terminal functional group-associated endocytic pathways in the proinflammatory responses induced by PEGylated QDs in human pulmonary epithelial cells and macrophages. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01653f

  11. Enhanced oil recovery using carboxylate surfactant systems

    Microsoft Academic Search

    James E. Shaw

    1984-01-01

    Oil displacement tests in water wet Berea sandstone cores containing residual crude oil flooded with water have shown that\\u000a high tertiary oil recoveries can be obtained using the sodium salts of readily available carboxylic acids. Using a 10% pore\\u000a volume surfactant slug containing 3.0% sodium isostearate and 3.0% isopentyl alcohol followed by a polyacrylamide mobility\\u000a buffer resulted in a 92%

  12. Interplay between group function of kinesin based transport and lipid bilayer mobility

    NASA Astrophysics Data System (ADS)

    Lopes, Joseph; Hirst, Linda; Xu, Jing

    2015-03-01

    Motor proteins, discovered in recent decades, are important building blocks to life. These molecular machines transport cargo and although indispensable to cell function, are not well understood at present. Single kinesin transport properties have been documented, but their group function remains unknown. In this project, the properties of kinesin-based transport by multiple motors are investigated in-vitro to establish a link between travel distance and lipid diffusion in the vesicle membrane. In the experiments, silica beads coated in a supported lipid membrane and giant lipid vesicles are transported along a microtubule by embedded kinesin motors. In an alternate geometry, this system can be inverted, whereby motors are bound to a surface of a lipid bilayer and microtubules are deposited. We have characterized motor function with respect to the fluidity of the membrane. To measure the diffusion properties of different membranes, planar lipid bilayers are prepared on silica slides and supported by bovine serum albumin protein. To establish a diffusion constant at room temperature for the lipid membrane we use the FRAP technique (fluorescence recovery after photobleaching). Using this method we can investigate if there is any interplay between group travel function and membrane fluidity.

  13. Group composition of carboxylic acids from West Siberian crude oils

    Microsoft Academic Search

    N. I. Zhil'tsov; V. A. Ershov; G. I. Samokhvalova

    1982-01-01

    with alkali [i]~ The physical and chemical properties of the crude oils from which the petroleum acids were obtained are listed in Table i, along with the results from chromatographic separation of the extracts into fractions of neutral substances, phenol, and carboxyiic acids. The deviation between results of parallel analyses was no greater than 15% (relative), and the losses in

  14. String partition functions, Hilbert schemes and affine Lie algebra representations on homology groups

    NASA Astrophysics Data System (ADS)

    Bonora, Loriano; Bytsenko, Andrey; Elizalde, Emilio

    2012-09-01

    This review paper contains a concise introduction to highest weight representations of infinite-dimensional Lie algebras, vertex operator algebras and Hilbert schemes of points, together with their physical applications to elliptic genera of superconformal quantum mechanics and superstring models. The common link of all these concepts and of the many examples considered in this paper is to be found in a very important feature of the theory of infinite-dimensional Lie algebras: the modular properties of the characters (generating functions) of certain representations. The characters of the highest weight modules represent the holomorphic parts of the partition functions on the torus for the corresponding conformal field theories. We discuss the role of the unimodular (and modular) groups and the (Selberg-type) Ruelle spectral functions of hyperbolic geometry in the calculation of elliptic genera and associated q-series. For mathematicians, elliptic genera are commonly associated with new mathematical invariants for spaces, while for physicists elliptic genera are one-loop string partition function. (Therefore, they are applicable, for instance, to topological Casimir effect calculations.) We show that elliptic genera can be conveniently transformed into product expressions, which can then inherit the homology properties of appropriate polygraded Lie algebras. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker’s 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’.

  15. Diversity, mobility, and structural and functional evolution of group II introns carrying an unusual 3' extension

    PubMed Central

    2011-01-01

    Background Group II introns are widespread genetic elements endowed with a dual functionality. They are catalytic RNAs (ribozymes) that are able of self-splicing and they are also mobile retroelements that can invade genomic DNA. The group II intron RNA secondary structure is typically made up of six domains. However, a number of unusual group II introns carrying a unique extension of 53-56 nucleotides at the 3' end have been identified previously in bacteria of the Bacillus cereus group. Methods In the present study, we conducted combined sequence comparisons and phylogenetic analyses of introns, host gene, plasmid and chromosome of host strains in order to gain insights into mobility, dispersal, and evolution of the unusual introns and their extension. We also performed in vitro mutational and kinetic experiments to investigate possible functional features related to the extension. Results We report the identification of novel copies of group II introns carrying a 3' extension including the first two copies in bacteria not belonging to the B. cereus group, Bacillus pseudofirmus OF4 and Bacillus sp. 2_A_57_CT2, an uncharacterized species phylogenetically close to B. firmus. Interestingly, the B. pseudofirmus intron has a longer extension of 70 bases. From sequence comparisons and phylogenetic analyses, several possible separate events of mobility involving the atypical introns could be identified, including both retrohoming and retrotransposition events. In addition, identical extensions were found in introns that otherwise exhibit little sequence conservation in the rest of their structures, with the exception of the conserved and catalytically critical domains V and VI, suggesting either separate acquisition of the extra segment by different group II introns or a strong selection pressure acting on the extension. Furthermore, we show by in vitro splicing experiments that the 3' extension affects the splicing properties differently in introns belonging to separate evolutionary branches. Conclusions Altogether this study provides additional insights into the structural and functional evolution of unusual introns harboring a 3' extension and lends further evidence that these introns are mobile with their extension. PMID:22204608

  16. Orthology, Function and Evolution of Accessory Gland Proteins in the Drosophila repleta Group

    PubMed Central

    Almeida, Francisca C.; DeSalle, Rob

    2009-01-01

    The accessory gland proteins (Acps) of Drosophila have become a model for the study of reproductive protein evolution. A major step in the study of Acps is to identify biological causes and consequences of the observed patterns of molecular evolution by comparing species groups with different biology. Here we characterize the Acp complement of Drosophila mayaguana, a repleta group representative. Species of this group show important differences in ecology and reproduction as compared to other Drosophila. Our results show that the extremely high rates of Acp evolution previously found are likely to be ubiquitous among species of the repleta group. These evolutionary rates are considerably higher than the ones observed in other Drosophila groups' Acps. This disparity, however, is not accompanied by major differences in the estimated number of Acps or in the functional categories represented as previously suggested. Among the genes expressed in accessory glands of D. mayaguana almost half are likely products of recent duplications. This allowed us to test predictions of the neofunctionalization model for gene duplication and paralog evolution in a more or less constrained timescale. We found that positive selection is a strong force in the early divergence of these gene pairs. PMID:19015541

  17. Improving plant functional groups for dynamic models of biodiversity: at the crossroads between functional and community ecology

    PubMed Central

    Isabelle, Boulangeat; Pauline, Philippe; Sylvain, Abdulhak; Roland, Douzet; Luc, Garraud; Sébastien, Lavergne; Sandra, Lavorel; Jérémie, Van Es; Pascal, Vittoz; Wilfried, Thuiller

    2013-01-01

    The pace of on-going climate change calls for reliable plant biodiversity scenarios. Traditional dynamic vegetation models use plant functional types that are summarized to such an extent that they become meaningless for biodiversity scenarios. Hybrid dynamic vegetation models of intermediate complexity (hybrid-DVMs) have recently been developed to address this issue. These models, at the crossroads between phenomenological and process-based models, are able to involve an intermediate number of well-chosen plant functional groups (PFGs). The challenge is to build meaningful PFGs that are representative of plant biodiversity, and consistent with the parameters and processes of hybrid-DVMs. Here, we propose and test a framework based on few selected traits to define a limited number of PFGs, which are both representative of the diversity (functional and taxonomic) of the flora in the Ecrins National Park, and adapted to hybrid-DVMs. This new classification scheme, together with recent advances in vegetation modeling, constitutes a step forward for mechanistic biodiversity modeling. PMID:24403847

  18. Competition patterns among phytoplankton functional groups: How useful are the complex mathematical models?

    NASA Astrophysics Data System (ADS)

    Zhao, Jingyang; Ramin, Maryam; Cheng, Vincent; Arhonditsis, George B.

    2008-05-01

    Simple models have significant contribution to the development of ecological theory. However, these minimalistic modeling approaches usually focus on a small subset of the causes of a phenomenon and neglect important aspects of system dynamics. In this study, we use a complex aquatic biogeochemical model to examine competition patterns and structural shifts in the phytoplankton community under nutrient enrichment conditions. Our model simulates multiple elemental cycles (org. C, N, P, Si, O), multiple functional phytoplankton (diatoms, green algae and cyanobacteria) and zooplankton (copepods and cladocerans) groups. It also takes into account recent advances in stoichiometric nutrient recycling theory, and the zooplankton grazing term is reformulated to include algal food quality effects on zooplankton assimilation efficiency. The model provided a realistic platform to examine the functional properties (e.g., kinetics, growth strategies, intracellular storage capacity) and the abiotic conditions (temperature, nutrient loading) under which the different phytoplankton groups can dominate or can be competitively excluded in oligo, meso and eutrophic environments. Based on the results of our analysis, the intergroup variability in the minimum cell quota and maximum transport rate at the cell surface for phosphorus along with the group-specific metabolic losses can shape the structure of plankton communities. We also use classification tree analysis to elucidate aspects (e.g., relative differences in the functional group properties, critical values of the abiotic conditions, levels of the other plankton community residents) of the complex interplay among physical, chemical and biological factors that drive epilimnetic plankton dynamics. Finally, our study highlights the importance of improving the mathematical representation of phytoplankton adaptive strategies for resources procurement (e.g., regulation of transport kinetics, effects of transport kinetics on the kinetics of assimilation, relationship between assimilation and growth) to effectively link variability at the organismal level with ecosystem-scale patterns.

  19. Rhodium(III)-Catalyzed ortho C?H Heteroarylation of (Hetero)aromatic Carboxylic Acids: A Rapid and Concise Access to ?-Conjugated Poly-heterocycles.

    PubMed

    Qin, Xurong; Li, Xiaoyu; Huang, Quan; Liu, Hu; Wu, Di; Guo, Qiang; Lan, Jingbo; Wang, Ruilin; You, Jingsong

    2015-06-01

    Rh(III) -catalyzed oxidative C?H/C?H cross-coupling between (hetero)aromatic carboxylic acids and various heteroarenes has been accomplished to construct highly functionalized ortho-carboxy-substituted bi(hetero)aryls. The use of a carboxy group as the directing group obviates tedious steps for installation and removal of extra directing groups, and enables a facile one-step synthesis of ortho-carboxy bi(hetero)aryls. The method provides opportunities for rapid assembly of a library of important fluorene and coumarin-type poly-heterocycles through intramolecular electrophilic substitution or oxidative lactonization. As illustrative examples, the strategy developed herein greatly streamlines accesses to a variety of appealing polyheterocycles such as DTPO (5H-dithieno[3,2-b:2',3'-d]pyran-5-one), CPDTO (cyclopentadithiophen-4-one), and indenothiophenes. PMID:25917223

  20. Poly[[nona-aqua-bis-(?-5-hy-droxy-benzene-1,3-di-carboxyl-ato)(5-hy-droxy-benzene-1,3-di-carboxyl-ato)dicerium(III)] hexa-hydrate].

    PubMed

    Fan, Xiao; Daiguebonne, Carole; Guillou, Olivier; Camara, Magatte

    2014-05-01

    In the title coordination polymer, {[Ce2(C8H4O5)3(H2O)9]·6H2O} n , the asymmetric unit is formed by two Ce(III) atoms, three 5-hy-droxy-benzene-1,3-di-carboxyl-ate ligands, nine coordinating water mol-ecules and six water mol-ecules of crystallization. The two Ce(III) atoms are bridged by 5-hy-droxy-benzene-1,3-di-carboxyl-ate ligands acting in a bis-bidentate coordination mode, generating infinite chains along [101]. Both independent metal atoms are nine-coordinated, one by four O atoms from the carboxyl-ate groups of two bridging 5-hy-droxy-benzene-1,3-di-carboxyl-ate ligands and five O atoms from water mol-ecules, generating a tricapped trigonal-prismatic geometry. The coordination around the second Ce(III) atom is similar, except that one of the water mol-ecules is replaced by an O atom from an additional 5-hy-droxy-benzene-1,3-di-carboxyl-ate ligand acting in a monodentate coordination mode and forming a capped square-anti-prismatic geometry. PMID:24860313

  1. Meta-Selective C-H Functionalization using a Nitrile based Directing Group and Cleavable Si-Tether

    PubMed Central

    Lee, Sunggi; Lee, Hyelee; Tan, Kian L.

    2014-01-01

    A nitrile-based template that enables meta-selective C-H bond functionalization was developed. The template is applicable to a range of substituted arenes and tolerates a variety of functional groups. The directing group uses a silicon atom for attachment allowing for a facile introduction/deprotection strategy increasing the synthetic practicality of this template. PMID:24325399

  2. Group I PAKs function downstream of Rac to promote podosome invasion during myoblast fusion in vivo

    PubMed Central

    Duan, Rui; Jin, Peng; Luo, Fengbao; Zhang, Guofeng; Anderson, Nathan

    2012-01-01

    The p21-activated kinases (PAKs) play essential roles in diverse cellular processes and are required for cell proliferation, apoptosis, polarity establishment, migration, and cell shape changes. Here, we have identified a novel function for the group I PAKs in cell–cell fusion. We show that the two Drosophila group I PAKs, DPak3 and DPak1, have partially redundant functions in myoblast fusion in vivo, with DPak3 playing a major role. DPak3 is enriched at the site of fusion colocalizing with the F-actin focus within a podosome-like structure (PLS), and promotes actin filament assembly during PLS invasion. Although the small GTPase Rac is involved in DPak3 activation and recruitment to the PLS, the kinase activity of DPak3 is required for effective PLS invasion. We propose a model whereby group I PAKs act downstream of Rac to organize the actin filaments within the PLS into a dense focus, which in turn promotes PLS invasion and fusion pore initiation during myoblast fusion. PMID:23007650

  3. Group I PAKs function downstream of Rac to promote podosome invasion during myoblast fusion in vivo.

    PubMed

    Duan, Rui; Jin, Peng; Luo, Fengbao; Zhang, Guofeng; Anderson, Nathan; Chen, Elizabeth H

    2012-10-01

    The p21-activated kinases (PAKs) play essential roles in diverse cellular processes and are required for cell proliferation, apoptosis, polarity establishment, migration, and cell shape changes. Here, we have identified a novel function for the group I PAKs in cell-cell fusion. We show that the two Drosophila group I PAKs, DPak3 and DPak1, have partially redundant functions in myoblast fusion in vivo, with DPak3 playing a major role. DPak3 is enriched at the site of fusion colocalizing with the F-actin focus within a podosome-like structure (PLS), and promotes actin filament assembly during PLS invasion. Although the small GTPase Rac is involved in DPak3 activation and recruitment to the PLS, the kinase activity of DPak3 is required for effective PLS invasion. We propose a model whereby group I PAKs act downstream of Rac to organize the actin filaments within the PLS into a dense focus, which in turn promotes PLS invasion and fusion pore initiation during myoblast fusion. PMID:23007650

  4. Carboxylates and sulfated carboxylates as inhibitors of steel corrosion in neutral media

    SciTech Connect

    Podobaev, N.I.; Larionov, E.A. [Moscow State Pedagogical Univ. (Russian Federation)

    1995-03-01

    Effects of carboxylates and sulfocarboxylates as well as their mixtures with o-nitrobenzoate on the corrosion of St3 steel in freely aerated distilled water and 0.01 - 0.04 M NaCl solutions (pH 7) are studied electrochemically and by the gravimetric technique. A noticeable improvement of the protective properties of sulfated mustard soap and sulfated castor oil is observed after the addition of 20 mg/l o-nitrobenzoate. Armco iron spontaneously passivates in 0.25 M CH{sub 3}COONa solution at a certain content of inhibitors and under a hydrodynamical regime. Sulfated carboxylates suppress the anodic process more strongly than do nonsulfated carboxylates.

  5. Architectural and Functional Diversity of Polycomb Group Response Elements in Drosophila

    PubMed Central

    Brown, J. Lesley; Kassis, Judith A.

    2013-01-01

    Polycomb group response elements (PREs) play an essential role in gene regulation by the Polycomb group (PcG) repressor proteins in Drosophila. PREs are required for the recruitment and maintenance of repression by the PcG proteins. PREs are made up of binding sites for multiple DNA-binding proteins, but it is still unclear what combination(s) of binding sites is required for PRE activity. Here we compare the binding sites and activities of two closely linked yet separable PREs of the Drosophila engrailed (en) gene, PRE1 and PRE2. Both PRE1 and PRE2 contain binding sites for multiple PRE–DNA-binding proteins, but the number, arrangement, and spacing of the sites differs between the two PREs. These differences have functional consequences. Both PRE1 and PRE2 mediate pairing-sensitive silencing of mini-white, a functional assay for PcG repression; however, PRE1 requires two binding sites for Pleiohomeotic (Pho), whereas PRE2 requires only one Pho-binding site for this activity. Furthermore, for full pairing-sensitive silencing activity, PRE1 requires an AT-rich region not found in PRE2. These two PREs behave differently in a PRE embryonic and larval reporter construct inserted at an identical location in the genome. Our data illustrate the diversity of architecture and function of PREs. PMID:23934890

  6. Telomere length kinetics assay (TELKA) sorts the telomere length maintenance (tlm) mutants into functional groups

    PubMed Central

    Rubinstein, Linda; Ungar, Lior; Harari, Yaniv; Babin, Vera; Ben-Aroya, Shay; Merenyi, Gabor; Marjavaara, Lisette; Chabes, Andrei; Kupiec, Martin

    2014-01-01

    Genome-wide systematic screens in yeast have uncovered a large gene network (the telomere length maintenance network or TLM), encompassing more than 400 genes, which acts coordinatively to maintain telomere length. Identifying the genes was an important first stage; the next challenge is to decipher their mechanism of action and to organize then into functional groups or pathways. Here we present a new telomere-length measuring program, TelQuant, and a novel assay, telomere length kinetics assay, and use them to organize tlm mutants into functional classes. Our results show that a mutant defective for the relatively unknown MET7 gene has the same telomeric kinetics as mutants defective for the ribonucleotide reductase subunit Rnr1, in charge of the limiting step in dNTP synthesis, or for the Ku heterodimer, a well-established telomere complex. We confirm the epistatic relationship between the mutants and show that physical interactions exist between Rnr1 and Met7. We also show that Met7 and the Ku heterodimer affect dNTP formation, and play a role in non-homologous end joining. Thus, our telomere kinetics assay uncovers new functional groups, as well as complex genetic interactions between tlm mutants. PMID:24728996

  7. pH feedback and phenotypic diversity within bacterial functional groups of the human gut.

    PubMed

    Kettle, Helen; Donnelly, Ruairi; Flint, Harry J; Marion, Glenn

    2014-02-01

    Microbial diversity in the human colon is very high with apparently large functional redundancy such that within each bacterial functional group there are many coexisting strains. Modelling this mathematically is problematic since strains within a functional group are often competing for the same limited number of resources and therefore competitive exclusion theory predicts a loss of diversity over time. Here we investigate, through computer simulation, a fluctuation dependent mechanism for the promotion of diversity. A variable pH environment caused by acidic by-products of bacterial growth on a fluctuating substrate coupled with small differences in acid tolerance between strains promotes diversity under both equilibrium and far-from-equilibrium conditions. Under equilibrium conditions pH fluctuations and relative nonlinearity in pH limitation among strains combine to prevent complete competitive exclusion. Under far-from-equilibrium conditions, loss of diversity through extinctions is made more difficult because pH cycling leads to fluctuations in the competitive ranking of strains, thereby helping to equalise fitness. We assume a trade-off between acid tolerance and maximum growth rate so that our microbial system consists of strains ranging from specialists to generalists. By altering the magnitude of the effect of the system on its pH environment (e.g. the buffering capacity of the colon) and the pattern of incoming resource we explore the conditions that promote diversity. PMID:24211524

  8. Two-particle irreducible functional renormalization group schemes—a comparative study

    NASA Astrophysics Data System (ADS)

    Rentrop, J. F.; Jakobs, S. G.; Meden, V.

    2015-04-01

    We derive functional renormalization group (fRG) schemes for Fermi systems which are based on the two-particle irreducible approach to the quantum many-body problem. In a first step, the cutoff is introduced in the non-interacting propagator as it is commonly done in fRG based on one-particle irreducible vertex functions. The most natural truncation of the resulting infinite hierarchy of flow equations is shown to be fully equivalent to self-consistent perturbation theory. An earlier suggested alternative truncation strategy is considered as well. In a second step, the cutoff is introduced in the two-particle interaction. Again two truncation procedures are investigated, one of which was derived before. In the latter, the mean-field solution of the many-body problem is considered as the starting point of the renormalization group flow. We compare the performance and the required numerical resources for solving the coupled flow equations for all the approximate schemes by applying them to the problem of the quantum anharmonic oscillator. In a functional integral representation, this model has a formal similarity to the quantum many-body problem. The perspectives for applying the derived two-particle irreducible fRG approaches to zero- and one-dimensional systems of correlated fermions are discussed.

  9. Submerged vegetation removal promotes shift of dominant phytoplankton functional groups in a eutrophic lake.

    PubMed

    Dong, Jing; Yang, Kai; Li, Shuangshuang; Li, Genbao; Song, Lirong

    2014-08-01

    Historical data indicate that the dominance of submerged plants in Dianchi Lake in the 1960s was characterized by low algal density with dominance of non-toxic group J (Scenedesmus, Pediastrum, etc.). The removal of submerged plants, which began in the 1970s, resulted in the expansion of bloom-forming Microcystis (group M). Laboratory experiments suggested that Microcystis aeruginosa was inclined to grow and develop at elevated temperatures. The growth of Scenedesmus obliquus was slower than that of co-cultivated M. aeruginosa in the absence of Ceratophyllum demersum, especially at higher temperatures. The existence of submerged plant C. demersum could inhibit the growth of the harmful algae M. aeruginosa and this inhibitory effect by C. demersum was enhanced with an increase in temperature. Instead, with C. demersum, the growth of S. obliquus was not inhibited, but the co-cultivated M. aeruginosa was eliminated in a short time. Combined with the historical data and laboratory experiments, it was indicated that the submerged plants might play important roles in the dominance of the non-toxic group J in the historical succession. Consequently, the introduction of the submerged plant such as C. demersum might alter the dominant phytoplankton functional groups from M to J and benefit the restoration of the eutrophic lake. PMID:25108726

  10. Group Forces in Instruction: Relationship to Learning. A Student and Teacher Training Program in Small Group Learning Functions.

    ERIC Educational Resources Information Center

    Mack, Richard G.; And Others

    The project's objectives were to increase achievement in mathematics, alter behavior in mathematics classes, and alter attitudes toward small-group work through training in small-group dynamics. The subjects were 85 10th grade geometry students assigned to one of two class periods (morning or afternoon). Within each class period, the students were…

  11. Preparation of magnetic latexes functionalized with chloromethyl groups via emulsifier-free miniemulsion polymerization

    NASA Astrophysics Data System (ADS)

    Faridi-Majidi, Reza; Sharifi-Sanjani, Naser

    2007-04-01

    Functionalized crosslinked polystyrene-co-divinylbenzene-co-chloromethylstyrene magnetic latex particles were prepared via emulsifier-free miniemulsion polymerization using 2, 2' azobis (2-amidinopropane) dihydrochloride (V-50) as an initiator and in the presence of magnetite nanoparticles in the monomers. Transmission electron microscopy (TEM) proved the presence of magnetite nanoparticles in polymer particles. Differential scanning calorimetery (DSC) analysis of the product showed an exothermic signal due to crosslinking of chains through electrophilic aromatic substitution of phenyl groups with chloromethyl groups in the presence of the dispersed Fe 3O 4 as Lewis acid. This was proven by thermogravimetric analysis (TGA) via the loss of gaseous HCl. The results were also compared with those of magnetite-free miniemulsion polymerization using V-50.

  12. Algorithmic derivation of functional renormalization group equations and Dyson-Schwinger equations

    NASA Astrophysics Data System (ADS)

    Huber, Markus Q.; Braun, Jens

    2012-06-01

    We present the Mathematica application DoFun which allows to derive Dyson-Schwinger equations and renormalization group flow equations for n-point functions in a simple manner. DoFun offers several tools which considerably simplify the derivation of these equations from a given physical action. We discuss the application of DoFun by means of two different types of quantum field theories, namely a bosonic O(N) theory and the Gross-Neveu model. Program summaryProgram title:DoFun Catalogue identifier: AELN_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELN_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 35 506 No. of bytes in distributed program, including test data, etc.: 571 837 Distribution format: tar.gz Programming language: Mathematica 7 and higher Computer: PCs and workstations Operating system: All on which Mathematica is available (Windows, Unix, MacOS) Classification: 11.1, 11.4, 11.5, 11.6 Nature of problem: Derivation of functional renormalization group equations and Dyson-Schwinger equations from the action of a given theory. Solution method: Implementation of an algorithm to derive functional renormalization group and Dyson-Schwinger equations. Unusual features: The results can be plotted as Feynman diagrams in Mathematica. The output is compatible with the syntax of many other programs and is therefore suitable for further (algebraic) computations. Running time: Seconds to minutes

  13. Development of function-related groups version 2.0: a classification system for medical rehabilitation.

    PubMed Central

    Stineman, M G; Tassoni, C J; Escarce, J J; Goin, J E; Granger, C V; Fiedler, R C; Williams, S V

    1997-01-01

    OBJECTIVE: To present a new version (2.0) of the Functional Independence Measure-Function Related Group (FIM-FRG) case-mix measure. DATA SOURCE/STUDY SETTING: 85,447 patient discharges from 252 freestanding facilities and hospital units contained in the 1992 Uniform Data System for Medical Rehabilitation. STUDY DESIGN: Patient impairment category, functional status at admission to rehabilitation, and patient age were used to develop groups that were homogeneous with respect to length of stay. Within each impairment category patients were randomly assigned to one data set to create the system (through recursive partitioning) or a second set for validation. Clinical and statistical criteria were used to increase the percentage of patients classified, expand the impairment categories of FIM-FRGs Version 1.1, and evaluate the incremental predictive ability of coexisting medical diagnoses. Predictive stability over time was evaluated using 1990 discharges. PRINCIPAL FINDINGS: In Version 2.0, the percentage of patients classified was increased to 92 percent. Version 2.0 includes two new impairment categories and separate groups for patients admitted to rehabilitation for evaluation only. Coexisting medical diagnoses did not improve LOS prediction. The system explains 31.7 percent of the variance in the logarithm of LOS in the 1992 validation sample, and 31.0 percent in 1990 discharges. CONCLUSIONS: FIM-FRGs Version 2.0 includes more specific impairment categories, classifies a higher percentage of patient discharges, and appears sufficiently stable over time to form the basis of a payment system for inpatient medical rehabilitation. PMID:9327817

  14. Pollinators of the Rocky Mountain columbine: temporal variation, functional groups and associations with floral traits

    PubMed Central

    Brunet, Johanne

    2009-01-01

    Background and Aims Pollinators together with other biotic and some abiotic factors can select for floral traits. However, variation in pollinator abundance over time and space can weaken such selection. In the present study, the variation in pollinator abundance over time and space was examined in populations of the Rocky Mountain columbine. The variation in three floral traits is described and correlations between pollinator type, functional pollinator groups or altitude and floral traits are examined. Methods Pollinator observations took place in six Aquilegia coerulea populations over 1–4 years and spur length, flower colour and sepal length were measured in 12 populations. Pollinator abundance, measured as visits per flower per hour, was compared among populations and years. Pollinators were grouped into two functional groups: pollen or nectar collectors. The following associations were examined: annual presence of hawkmoths and whiter flowers with longer spurs; the presence of Sphinx vashti and longer spurs; and higher altitudes and whiter flowers. The study looked at whether an increase in the proportion of hawkmoths in a population was associated with whiter and larger flowers with longer spurs. Key Results The abundance of different pollinator groups varied over time and space. Floral traits varied among populations. Higher altitude was correlated with bluer flowers. Whiter flowers were associated with the annual presence of hawkmoths. Populations visited by Sphinx vashti had longer spurs than populations visited only by Hyles lineata. Populations with greater percentage of nectar-collecting pollinators did not have whiter, larger flowers with longer spurs. Conclusions Despite the large variation in pollinator abundance over time and space, one species of bumble-bee or hawkmoth tended to predominate in each population each year. Future studies of Aquilegia coerulea should examine the specific influences of pollinators and the environment on flower colour and of hawkmoth species on spur length. PMID:19414518

  15. Pairing in asymmetric many-fermion systems: Functional renormalisation group approach

    NASA Astrophysics Data System (ADS)

    Krippa, Boris

    2015-05-01

    Functional renormalisation group approach is applied to a imbalanced many-fermion system with a short-range attractive force. We introduce a composite boson field to describe pairing effects, and assume a simple ansatz for the effective action. A set of approximate flow equations for the effective coupling including boson and fermionic fluctuations is derived and solved. We identify the critical values of particle number density mismatch when the system undergoes a normal state. We determine the phase diagram both at unitarity and around. The obtained phase diagram is in a reasonable agreement with the experimental data.

  16. Effect of functional end groups of silane self assembled monolayer surfaces on apatite formation, fibronectin adsorption and osteoblast cell function

    PubMed Central

    Toworfe, G.K.; Bhattacharyya, S.; Composto, R.J.; Adams, C.S.; Shapiro, I.M.; Ducheyne, P.

    2008-01-01

    Bioactive glass (BG) can directly bond to living bone without fibrous tissue encapsulation. Key mechanistic steps of BG’s activity are attributed to calcium phosphate formation, surface hydroxylation and fibronectin (FN) adsorption. In the present study, self-assembled monolayers (SAMs) of alkanesilanes with different surface chemistry (OH, NH2, and COOH) were used as a model system to mimic BG’s surface activity. Calcium phosphate (Ca-P) was formed on SAMs by immersion in a solution which simulates the electrolyte content of physiological fluids. FN adsorption kinetics and monolayer coverage was determined on SAMs with or without Ca-P coating. The surface roughness was also examined on these substrates before and after FN adsorption. The effects of FN-adsorbed, Ca-P coated SAMs on the function of MC3T3-E1 were evaluated by cell growth, expression of alkaline phosphatase activity, and actin cytoskeleton formation. We demonstrate that, although the FN monolayer coverage and the rms roughness are similar on ?OH and ?COOH terminated SAMs with or without Ca-P coating, higher levels of ALP activity, more actin cytoskeleton formation and more cell growth are obtained on ?OH and ?COOH terminated SAMs with Ca-P coating. In addition, although the FN monolayer coverage is higher on Ca-P coated ?NH2 terminated SAMs and SiOx surfaces, higher levels of ALP activity and more cell growth are obtained on Ca-P coated ?OH and ?COOH terminated SAMs. Thus with same Ca-P coatings, different surface functional groups have different effects on the function of osteoblastic cells. These findings represent new insights into the mechanism of bioactivity of BG and, thereby, may lead to designing superior constructs for bone grafting. PMID:19012271

  17. Truncation effects in the functional renormalization group study of spontaneous symmetry breaking

    NASA Astrophysics Data System (ADS)

    Defenu, N.; Mati, P.; Márián, I. G.; Nándori, I.; Trombettoni, A.

    2015-05-01

    We study the occurrence of spontaneous symmetry breaking (SSB) for O( N ) models using functional renormalization group techniques. We show that even the local potential approximation (LPA) when treated exactly is sufficient to give qualitatively correct results for systems with continuous symmetry, in agreement with the Mermin-Wagner theorem and its extension to systems with fractional dimensions. For general N (including the Ising model N = 1) we study the solutions of the LPA equations for various truncations around the zero field using a finite number of terms (and different regulators), showing that SSB always occurs even where it should not. The SSB is signalled by Wilson-Fisher fixed points which for any truncation are shown to stay on the line defined by vanishing mass beta functions.

  18. Nonperturbative renormalization group and momentum dependence of n-point functions. I

    SciTech Connect

    Blaizot, Jean-Paul; Mendez-Galain, Ramon; Wschebor, Nicolas [ECT, Villa Tambosi, strada delle Tabarelle 286, 38050 Villazzano (Italy); Instituto de Fisica, Facultad de Ingenieria, J.H.y Reissig 565, 11000 Montevideo (Uruguay)

    2006-11-15

    We present an approximation scheme to solve the nonperturbative renormalization group equations and obtain the full momentum dependence of the n-point functions. It is based on an iterative procedure where, in a first step, an initial ansatz for the n-point functions is constructed by solving approximate flow equations derived from well motivated approximations. These approximations exploit the derivative expansion and the decoupling of high momentum modes. The method is applied to the O(N) model. In leading order, the self-energy is already accurate both in the perturbative and the scaling regimes. A stringent test is provided by the calculation of the shift {delta}T{sub c} in the transition temperature of the weakly repulsive Bose gas, a quantity which is particularly sensitive to all momentum scales. The leading order result is in agreement with lattice calculations, albeit with a theoretical uncertainty of about 25%.

  19. Truncation Effects in the Functional Renormalization Group Study of Spontaneous Symmetry Breaking

    E-print Network

    N. Defenu; P. Mati; I. G. Marian; I. Nandori; A. Trombettoni

    2014-11-10

    We study the occurrence of spontaneous symmetry breaking (SSB) for O(N) models using functional renormalization group techniques. We show that even the local potential approximation (LPA) when treated exactly is sufficient to give qualitatively correct results for systems with continuous symmetry, in agreement with the Mermin-Wagner theorem and its extension to systems with fractional dimensions. For general N (including the Ising model N=1) we study the solutions of the LPA equations for various truncations around the zero field using a finite number of terms (and different regulators), showing that SSB always occurs even where it should not. The SSB is signalled by Wilson-Fisher fixed points which for any truncation are shown to stay on the line defined by vanishing mass beta functions.

  20. Challenging urban species diversity: contrasting phylogenetic patterns across plant functional groups in Germany.

    PubMed

    Knapp, Sonja; Kühn, Ingolf; Schweiger, Oliver; Klotz, Stefan

    2008-10-01

    Cities are hotspots of plant species richness, harboring more species than their rural surroundings, at least over large enough scales. However, species richness does not necessarily cover all aspects of biodiversity such as phylogenetic relationships. Ignoring these relationships, our understanding of how species assemblages develop and change in a changing environment remains incomplete. Given the high vascular plant species richness of urbanized areas in Germany, we asked whether these also have a higher phylogenetic diversity than rural areas, and whether phylogenetic diversity patterns differ systematically between species groups characterized by specific functional traits. Calculating the average phylogenetic distinctness of the total German flora and accounting for spatial autocorrelation, we show that phylogenetic diversity of urban areas does not reflect their high species richness. Hence, high urban species richness is mainly due to more closely related species that are functionally similar and able to deal with urbanization. This diminished phylogenetic information might decrease the flora's capacity to respond to environmental changes. PMID:18616547

  1. Ethyl 5-methyl-7-phenyl-1,2,4-triazolo[4,3-a]pyrimidine-6-carboxyl-ate.

    PubMed

    AboulWafa, Omaima M; Farghaly, Ahmed M; Teleb, Mohamed; Sinoussy, Khaled S

    2014-06-01

    In the title compound, C15H14N4O2, the triazolo-pyrimidine ring system is almost planar (r.m.s. deviation = 0.02?Å) and the phenyl ring is inclined to its mean plane by 42.45?(9)°. The carboxyl group is inclined to the triazolo-pyrimidine ring mean plane by 57.8?(3)°. In the mol-ecule, there is a short C-H?O contact involving the carbonyl O atom and an H atom of the adjacent methyl substituent. In the crystal, neighbouring mol-ecules are linked by C-H?O hydrogen bonds, forming chains propagating along [010]. There are also weak ?-? inter-actions present involving the pyridine and phenyl rings of neighbouring chains [inter-centroid distance = 3.8580?(16)?Å]. PMID:24940253

  2. Chemical reactivity of the functional groups of insulin. Concentration-dependence studies.

    PubMed Central

    Kaplan, H; Hefford, M A; Chan, A M; Oda, G

    1984-01-01

    A modification to the competitive labelling procedure of Duggleby and Kaplan [(1975) Biochemistry 14, 5168-5175] was used to study the reactivity of the N-termini, lysine, histidine and tyrosine groups of insulin over the concentration range 1 X 10(-3)-1 X 10(-7)M. Reactions were carried out with acetic anhydride and 1-fluoro-2,4-dinitrobenzene in 0.1 M-KCl at 37 degrees C using Pyrex glass, Tefzel and polystyrene reaction vessels. At high concentrations all groups had either normal or enhanced reactivity but at high dilution the reactivities of all functional groups became negligible. This behaviour is attributed to the adsorption of insulin to the reaction vessels. The histidine residues show a large decrease in reactivity in all reaction vessels in the concentration range 1 X 10(-3)-1 X 10(-5)M where there are no adsorption effects and where the reactivities of all other functional groups are independent of concentration. With polystyrene, where adsorption effects become significant only below 1 X 10(-6)M, the reactivity of the phenylalanine N-terminus also shows a decrease in reactivity between 1 X 10(-5) and 1 X 10(-6)M. In 1 M-KCl insulin does not absorb to Pyrex glass and under these conditions the histidine reactivity is concentration-dependent from 1 X 10(-3) to 5 X 10(-6)M and the B1 phenylalanine alpha-amino and the B29 lysine epsilon-amino reactivities from 5 X 10(-6) to 1 X 10(-7)M, whereas the reactivities of all other groups are constant. These alterations in reactivity on dilution are attributed to disruption of dimer-dimer interactions for histidine and to monomer-monomer interactions for the phenylalanine and lysine amino groups. It is concluded that the monomeric unit of insulin has essentially the same conformation in its free and associated states. PMID:6365082

  3. Nitrogen niches revealed through species and functional group removal in a boreal shrub community.

    PubMed

    Gundale, Michael J; Hyodo, Fujio; Nilsson, Marie-Charlotte; Wardle, David A

    2012-07-01

    Most theories attempting to explain the coexistence of species in local communities make fundamental assumptions regarding whether neighbors exhibit competitive, neutral, or positive resource-use interactions; however, few long-term data from naturally assembled plant communities exist to test these assumptions. We utilized a 13-year experiment consisting of factorial removal of three shrub species (Vaccinium myrtillus, V. vitis-idaea, and Empetrum hermaphroditum) and factorial removal of two functional groups (tree roots and feather mosses) to assess how neighbors affect N acquisition and growth of each of the three shrub species. The removal plots were established on each of 30 lake islands in northern Sweden that form a natural gradient of resource availability. We tested the hypotheses that: (1) the presence of functionally similar neighbors would reduce shrub N acquisition through competition for a shared N resource; (2) the removal of functional groups would affect shrub N acquisition by altering the breadth of their niches; and (3) soil fertility would influence the effects of neighbor removals. We found that the removal of functionally similar neighbors (i.e., other shrub species) usually resulted in higher biomass and biomass N, with the strength of these effects varying strongly with site fertility. Shrub species removals never resulted in altered stable N isotope ratios (delta(15)N), suggesting that the niche breadth of the three shrubs was unaffected by the presence of neighboring shrub species. In the functional group removal experiment, we found positive effects of feather moss removal on V. myrtillus biomass and biomass N, and negative effects on E. hermaphrotium N concentration and V. vitis-idaea biomass and biomass N. Tree root removal also caused a significant shift in foliar delta(15)N of V. myrtillus and altered the delta(15)N, biomass, and biomass N of E. hermaphroditum. Collectively, these results show that the resource acquisition and niche breadth of the three shrub species are often affected by neighbors, and further that both the identity of neighbors and site fertility strongly determine whether these interactions are positive, negative, or neutral. These findings have implications for understanding species coexistence and the reciprocal relationships between productivity and species diversity in this ecosystem. PMID:22919915

  4. Functional Subdivision of Group-ICA Results of fMRI Data Collected during Cinema Viewing

    PubMed Central

    Pamilo, Siina; Malinen, Sanna; Hlushchuk, Yevhen; Seppä, Mika; Tikka, Pia; Hari, Riitta

    2012-01-01

    Independent component analysis (ICA) can unravel functional brain networks from functional magnetic resonance imaging (fMRI) data. The number of the estimated components affects both the spatial pattern of the identified networks and their time-course estimates. Here group-ICA was applied at four dimensionalities (10, 20, 40, and 58 components) to fMRI data collected from 15 subjects who viewed a 15-min silent film (“At land” by Maya Deren). We focused on the dorsal attention network, the default-mode network, and the sensorimotor network. The lowest dimensionalities demonstrated most prominent activity within the dorsal attention network, combined with the visual areas, and in the default-mode network; the sensorimotor network only appeared with ICA comprising at least 20 components. The results suggest that even very low-dimensional ICA can unravel the most prominent functionally-connected brain networks. However, increasing the number of components gives a more detailed picture and functionally feasible subdivision of the major networks. These results improve our understanding of the hierarchical subdivision of brain networks during viewing of a movie that provides continuous stimulation embedded in an attention-directing narrative. PMID:22860044

  5. Mining approximate temporal functional dependencies with pure temporal grouping in clinical databases.

    PubMed

    Combi, Carlo; Mantovani, Matteo; Sabaini, Alberto; Sala, Pietro; Amaddeo, Francesco; Moretti, Ugo; Pozzi, Giuseppe

    2015-07-01

    Functional dependencies (FDs) typically represent associations over facts stored by a database, such as "patients with the same symptom get the same therapy." In more recent years, some extensions have been introduced to represent both temporal constraints (temporal functional dependencies - TFDs), as "for any given month, patients with the same symptom must have the same therapy, but their therapy may change from one month to the next one," and approximate properties (approximate functional dependencies - AFDs), as "patients with the same symptomgenerallyhave the same therapy." An AFD holds most of the facts stored by the database, enabling some data to deviate from the defined property: the percentage of data which violate the given property is user-defined. According to this scenario, in this paper we introduce approximate temporal functional dependencies (ATFDs) and use them to mine clinical data. Specifically, we considered the need for deriving new knowledge from psychiatric and pharmacovigilance data. ATFDs may be defined and measured either on temporal granules (e.g.grouping data by day, week, month, year) or on sliding windows (e.g.a fixed-length time interval which moves over the time axis): in this regard, we propose and discuss some specific and efficient data mining techniques for ATFDs. We also developed two running prototypes and showed the feasibility of our proposal by mining two real-world clinical data sets. The clinical interest of the dependencies derived considering the psychiatry and pharmacovigilance domains confirms the soundness and the usefulness of the proposed techniques. PMID:25220098

  6. THE DARK MATTER HALO CONCENTRATION AND STELLAR INITIAL MASS FUNCTION OF A CASSOWARY GROUP

    SciTech Connect

    Deason, A. J. [Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Auger, M. W.; Belokurov, V.; Evans, N. W., E-mail: alis@ucolick.org [Institute of Astronomy, Madingley Rd, Cambridge, CB3 0HA (United Kingdom)

    2013-08-10

    We exploit the group environment of the CAmbridge Sloan Survey Of Wide ARcs in the skY z = 0.3 lens J2158+0257 to measure the group dynamical mass as a complement to the central dynamical and lensing mass constraints. Follow-up spectroscopy of candidate group members is performed using VLT/FORS2. From the resulting N = 21 confirmed members, we measure the group dynamical mass by calibrating an analytic tracer mass estimator with cosmological simulations. The luminosity-weighted line-of-sight velocity dispersion and the Einstein radius of the lens are used as mass probes in the inner regions of the galaxy. Combining these three observational probes allows us to independently constrain the mass and concentration of the dark matter halo, in addition to the total stellar mass of the central galaxy. We find a dark matter halo in remarkably good agreement with simulations (log{sub 10} M{sub 200}/M{sub Sun} = 14.2 {+-} 0.2, c{sub 200}= 4.4{sup +1.6}{sub -1.4}) and a stellar mass-to-light ratio which favors a Salpeter initial mass function ((M/L)* = 5.7 {+-} 1.2). Our measurement of a normal halo concentration suggests that there is no discrepancy between simulations and observations at the group mass scale. This is in contrast to the cluster mass scale for which a number of studies have claimed over-concentrated halos. While the halo mass is robustly determined, and the halo concentration is not significantly affected by systematics, the resulting stellar mass-to-light ratio is sensitive to the choice of stellar parameters, such as density profile and velocity anisotropy.

  7. Anisotropic adsorption and distribution of immobilized carboxyl on nanodiamond

    NASA Astrophysics Data System (ADS)

    Lai, Lin; Barnard, Amanda S.

    2014-11-01

    Stable and predictable functionalization of nanodiamond with carboxyl is an important first step in loading these materials with therapeutic agents, and the conjugation with proteins, cytochrome, antigen, and DNA. By creating a map of the adsorption strength of COOH, OH, O and H with atomic level resolution across the entire surface of an experimentally realistic nanodiamond, we have shown how the distribution is highly anisotropic, and depends on surface reconstructions, facet orientation, and ultimately the shape. This provides useful insights into how the structure of nanodiamond impacts the formation of COOH surface monolayers, and suggests that efforts to separate nanodiamonds by shape would be highly beneficial in the development of drug delivery vehicles targeted to specific treatment regimes.Stable and predictable functionalization of nanodiamond with carboxyl is an important first step in loading these materials with therapeutic agents, and the conjugation with proteins, cytochrome, antigen, and DNA. By creating a map of the adsorption strength of COOH, OH, O and H with atomic level resolution across the entire surface of an experimentally realistic nanodiamond, we have shown how the distribution is highly anisotropic, and depends on surface reconstructions, facet orientation, and ultimately the shape. This provides useful insights into how the structure of nanodiamond impacts the formation of COOH surface monolayers, and suggests that efforts to separate nanodiamonds by shape would be highly beneficial in the development of drug delivery vehicles targeted to specific treatment regimes. Electronic supplementary information (ESI) available: Coordinates of the fully replaced diamond nanoparticle used in this study (in standard xyz format), and images of all of the relaxed ND-COOH binding configurations. See DOI: 10.1039/c4nr05363j

  8. General pharmacological properties of the new angiotensin II receptor antagonist (+/-)-1-(cyclohexyloxycarbonyloxy) ethyl 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl] methyl]-1 H-benzimidazole-7-carboxylate. Part II: Effect on cardiovascular system and renal functions.

    PubMed

    Kito, G; Ito, K; Shiomi, M

    1996-07-01

    The effects of TCV-116 ((+/-)-1-(cyclohexyloxycarbonyloxy) ethyl 2-ethoxy-1-[[2'-(1 H-tetrazol-5-yl)biphenyl-4-yl] methyl]-1 H-benzimidazole-7-carboxylate, CAS 145040-37-5) on the cardiovascular system and renal function were investigated in rats, guinea pigs, and dogs. TCV-116 at doses of 3 mg/kg (i.d.) and higher markedly increased renal blood flow in anesthetized dogs. TCV-116 at 30 mg/kg (i.d.) had no effect on heart rate, left ventricular systolic pressure, its dp/dtmax, or cardiac output in anesthetized dogs. Furthermore, TCV-116 at 10 and 30 mg/kg (p.o.) had little effect on cardiac output, right atrial pressure, pulmonary artery pressure, pulmonary capillary wedge pressure or respiration in conscious dogs. In isolated guinea pig perfused heart, CV-11974 even at a dose of 0.1 mg/ heart had no effect on cardiac function. In isolated guinea-pig atria, CV-11974, the active metabolite of TCV-116, even at 10(-4) mol/l had no effect on the spontaneous beating rate of the right atria or the contractile force of electrically-paced left atria. No significant effect of TCV-116 on urinary volume or urinary excretion of sodium and potassium was observed in rats (at 30, 100 or 300 mg/kg p.o.). These findings suggest that TCV-116 exerts no any additional pharmacological effects on cardiac and respiratory functions in dogs or on renal function in rats, other than an increase in renal blood flow in anesthetized dogs thought to be due to its inhibitory effect on the renin-angiotensin system. PMID:8842337

  9. Trophic links between functional groups of arable plants and beetles are stable at a national scale.

    PubMed

    Brooks, David R; Storkey, Jonathan; Clark, Suzanne J; Firbank, Les G; Petit, Sandrine; Woiwod, Ian P

    2012-01-01

    1. There is an urgent need to accurately model how environmental change affects the wide-scale functioning of ecosystems, but advances are hindered by a lack of knowledge of how trophic levels are linked across space. It is unclear which theoretical approach to take to improve modelling of such interactions, but evidence is gathering that linking species responses to their functional traits can increase understanding of ecosystem dynamics. Currently, there are no quantitative studies testing how this approach might improve models of multiple, trophically interacting species, at wide spatial scales. 2. Arable weeds play a foundational role in linking food webs, providing resources for many taxa, including carabid beetles that feed on their seeds and weed-associated invertebrate prey. Here, we model associations between weeds and carabids across farmland in Great Britain (GB), to test the hypothesis that wide-scale trophic links between these groups are structured by their species functional traits. 3. A network of c. 250 arable fields, covering four crops and most lowland areas of GB, was sampled for weed, carabid and invertebrate taxa over 3 years. Data sets of these groups were closely matched in time and space, and each contained numerous species with a range of eco-physiological traits. The consistency of trophic linkages between multiple taxa sharing functional traits was tested within multivariate and log-linear models. 4. Robust links were established between the functional traits of taxa and their trophic interactions. Autumn-germinating, small-seeded weeds were associated with smaller, spring-breeding carabids, more specialised in seed feeding, whereas spring-germinating, large-seeded weeds were associated with a range of larger, autumn-breeding omnivorous carabids. These relationships were strong and dynamic, being independent of changes in invertebrate food resources and consistent across sample dates, crops and regions of GB. 5. We conclude that, in at least one system of interacting taxa, functional traits can be used to predict consistent, wide-scale trophic links. This conceptual approach is useful for assessing how perturbations affecting lower trophic levels are ramified throughout ecosystems and could be used to assess how environmental change affects a wider range of secondary consumers. PMID:21883203

  10. Function of group IB inhibition during assisted stepping in human spinal cord injury.

    PubMed

    Knikou, Maria

    2012-06-01

    The aim of this study was to investigate the function of group Ib inhibition exerted between ankle synergists during assisted stepping in people with chronic motor incomplete spinal cord injury (SCI). During stepping, the soleus (SOL) H-reflex was conditioned by percutaneous stimulation of the medialis gastrocnemius (MG) nerve by a bipolar electrode placed distal and medial to the cathode electrode for the tibial nerve. Stimulation was delivered at 0.95 times MG M-wave motor threshold with a pulse train at short conditioning-test intervals. To counteract movement of recording and stimulating electrodes, a supramaximal stimulus at 80 to 100 milliseconds after the test H-reflex was delivered. Stimuli were randomly dispersed across the step cycle, which was divided into 16 equal bins. The conditioned SOL H-reflex was significantly facilitated throughout the stance phase, while it was depressed during the swing phase when compared with the unconditioned SOL H-reflex. Ankle clonus during the stance phase may have affected the excitability state of spinal motoneuronal and interneuronal circuits, but the presence of group Ib inhibition in the swing phase suggests that in the absence of loading this spinal circuit is modulated in a physiologic manner in human incomplete SCI. Repetitive body loading and unloading promotes functional integration of sensory signals mediating load in human SCI. PMID:22659724

  11. Existence of ultrafine crevices and functional groups along the edge surfaces of graphitized thermal carbon black.

    PubMed

    Zeng, Yonghong; Do, D D; Nicholson, D

    2015-04-14

    Adsorption of different gases on graphitized thermal carbon black (GTCB) has been studied with a new molecular model to examine the consequences of micropore crevices and functional groups at the junctions between adjacent basal planes. Adsorption was simulated in the Grand Canonical Monte Carlo ensemble and the theoretical Henry constants were calculated by Monte Carlo volume integration over the Boltzmann factor of the solid-fluid potential. The simulation results are in good agreement with high-resolution experimental isotherms for argon on mineralogical graphite measured by Lopez-Gonzalez et al.1 From detailed inspection of the argon isotherms at extremely low coverages, we find two distinct Henry law regions, separated by a plateau (suggesting saturation of the stronger sites) that spans over a few decades of pressure. The first Henry law region is attributed to adsorption in the ultrafine crevices at the junctions between two adjacent basal planes, and the second region corresponds to adsorption on the basal plane, as confirmed by the theoretical Henry constant. The simulated isosteric heat and snapshots of molecular configurations show that argon adsorbs preferentially in the ultrafine crevices where there is a deep potential well due to overlap from the opposite pore walls. Similar behavior was found for other nonassociating fluids (Ar, N2, and CO2); however, for associating fluids (NH3 and H2O), the strong sites for adsorption and nucleation come from the combined effects of functional groups and ultrafine crevices, since the latter cannot alone account for the observed adsorption. PMID:25797845

  12. cis-Tri­aqua­[1,1?-(propane-1,3-di­yl)bis­(pyridin-1-ium-4-carboxyl­ato)-?O]bis­(thio­cyanato-?N)manganese(II) dihydrate

    PubMed Central

    Tan, Qing-Hua; Wang, Yan-Qin

    2014-01-01

    In the title compound, [Mn(NCS)2(C15H14N2O4)(H2O)3]·2H2O, the metal ion is octa­hedrally coordinated by three water mol­ecules, one carboxyl­ate O atom from a 1,1?-(propane-1,3-di­yl)bis­(pyridinium-4-carboxyl­ate) ligand and two N atoms from two thio­cyanate anions in cis positions, forming a mononuclear complex mol­ecule. In the crystal, mol­ecules are connected into a three-dimensional architecture through O—H?O hydrogen bonds involving water mol­ecules and carboxyl­ate groups. PMID:24764814

  13. Assessing physiological responses of dune forest functional groups to changing water availability: from Tropics to Mediterranean.

    NASA Astrophysics Data System (ADS)

    Antunes, Cristina; Lo Cascio, Mauro; Correia, Otília; Vieira, Simone; Cruz Diaz Barradas, Maria; Zunzunegui, Maria; Ramos, Margarida; João Pereira, Maria; Máguas, Cristina

    2014-05-01

    Alterations in water availability are important to vegetation as can produce dramatic changes in plant communities, on physiological performance or survival of plant species. Particularly, groundwater lowering and surface water diversions will affect vulnerable coastal dune forests, ecosystems particularly sensitive to groundwater limitation. Reduction of water tables can prevent the plants from having access to one of their key water sources and inevitably affect groundwater-dependent species. The additional impact of drought due to climatic change on groundwater-dependent ecosystems has become of increasing concern since it aggravates groundwater reduction impacts with consequent uncertainties about how vegetation will respond over the short and long term. Sand dune plant communities encompass a diverse number of species that differ widely in root depth, tolerance to drought and capacity to shift between seasonal varying water sources. Plant functional groups may be affected by water distribution and availability differently. The high ecological diversity of sand dune forests, characterized by sandy soils, well or poorly drained, poor in nutrients and with different levels of salinity, can occur in different climatic regions of the globe. Such is the case of Tropical, Meso-mediterranean and Mediterranean areas, where future climate change is predicted to change water availability. Analyses of the relative natural abundances of stable isotopes of carbon (13C/12C) and oxygen (18O/16O) have been used across a wide range of scales, contributing to our understanding of plant ecology and interactions. This approach can show important temporal and spatial changes in utilization of different water sources by vegetation. Accordingly, the core idea of this work is to evaluate, along a climatic gradient, the responses and capacity of different coastal plant communities to adapt to changing water availability. This large-climatic-scale study, covering Brazil, Portugal and Spain, provide an excellent experimental network to study the water dynamics and community functioning in natural ecosystems of high ecological value. To fulfill the main objective, a stable isotope approach (leaf ?13C and xylem+water sources ?18O) was used as a tool to assess physiological performance and water strategies integrated in spatio-temporal water dynamics. Plant functional groups' water use was characterized in a water changing situation (at different seasons) in a climatic gradient. We evaluated stress sensitivity of the functional groups to seasonal changes in water availability in different communities and tried to understand their water use strategy.

  14. A semi-grand canonical Monte Carlo simulation model for ion binding to ionizable surfaces: proton binding of carboxylated latex particles as a case study.

    PubMed

    Madurga, Sergio; Rey-Castro, Carlos; Pastor, Isabel; Vilaseca, Eudald; David, Calin; Garcés, Josep Lluís; Puy, Jaume; Mas, Francesc

    2011-11-14

    In this paper, we present a computer simulation study of the ion binding process at an ionizable surface using a semi-grand canonical Monte Carlo method that models the surface as a discrete distribution of charged and neutral functional groups in equilibrium with explicit ions modelled in the context of the primitive model. The parameters of the simulation model were tuned and checked by comparison with experimental titrations of carboxylated latex particles in the presence of different ionic strengths of monovalent ions. The titration of these particles was analysed by calculating the degree of dissociation of the latex functional groups vs. pH curves at different background salt concentrations. As the charge of the titrated surface changes during the simulation, a procedure to keep the electroneutrality of the system is required. Here, two approaches are used with the choice depending on the ion selected to maintain electroneutrality: counterion or coion procedures. We compare and discuss the difference between the procedures. The simulations also provided a microscopic description of the electrostatic double layer (EDL) structure as a function of pH and ionic strength. The results allow us to quantify the effect of the size of the background salt ions and of the surface functional groups on the degree of dissociation. The non-homogeneous structure of the EDL was revealed by plotting the counterion density profiles around charged and neutral surface functional groups. PMID:22088048

  15. A semi-grand canonical Monte Carlo simulation model for ion binding to ionizable surfaces: Proton binding of carboxylated latex particles as a case study

    NASA Astrophysics Data System (ADS)

    Madurga, Sergio; Rey-Castro, Carlos; Pastor, Isabel; Vilaseca, Eudald; David, Calin; Garcés, Josep Lluís; Puy, Jaume; Mas, Francesc

    2011-11-01

    In this paper, we present a computer simulation study of the ion binding process at an ionizable surface using a semi-grand canonical Monte Carlo method that models the surface as a discrete distribution of charged and neutral functional groups in equilibrium with explicit ions modelled in the context of the primitive model. The parameters of the simulation model were tuned and checked by comparison with experimental titrations of carboxylated latex particles in the presence of different ionic strengths of monovalent ions. The titration of these particles was analysed by calculating the degree of dissociation of the latex functional groups vs. pH curves at different background salt concentrations. As the charge of the titrated surface changes during the simulation, a procedure to keep the electroneutrality of the system is required. Here, two approaches are used with the choice depending on the ion selected to maintain electroneutrality: counterion or coion procedures. We compare and discuss the difference between the procedures. The simulations also provided a microscopic description of the electrostatic double layer (EDL) structure as a function of pH and ionic strength. The results allow us to quantify the effect of the size of the background salt ions and of the surface functional groups on the degree of dissociation. The non-homogeneous structure of the EDL was revealed by plotting the counterion density profiles around charged and neutral surface functional groups.

  16. Functional group-dependent self-assembled nanostructures from thermo-responsive triblock copolymers.

    PubMed

    Banerjee, Rakesh; Dhara, Dibakar

    2014-04-15

    The ability to control the formation of nanostructures through self-assembly of amphiphilic block copolymers is of great interest in the field of biology and catalysis. In this work we have studied the self-assembling behavior of a new class of thermo-responsive triblock copolymers containing poly(ethylene glycol), and demonstrated the manner in which the aggregation pattern changed on simple functional group transformation on the copolymers. Two different triblock copolymers, poly(ethylene glycol)-b-poly(N-ispropylacrylamide)-b-poly(t-butyl acrylate) (P1) and poly(ethylene glycol)-b-poly(N-isopropylacrylamide)-b-poly(glycidyl methacrylate) (P2) were synthesized using reversible addition-fragmentation chain transfer (RAFT) technique. It was observed that P1 and P2 displayed different temperature dependent solution properties in water, with P1 forming micelles above the LCST of the PNIPA while P2 showing macroscopic phase separation under similar conditions. Thereafter, the tert-butyl group of P1 was converted to the corresponding acid (P1a) and the epoxy groups of P2 was converted to diols (P2a), thus transforming the hydrophobic blocks to hydrophilic ones. Quite interestingly, such transformations led to significant changes in their self-assembling behavior, as both P1a and P2a were seen to form vesicles beyond the LCST of PNIPA. Changes in the hydrophilic fraction in the block copolymers by subtle changes in the functionality and temperature led to the formation of varied nanostructured assemblies, as evident from dynamic light scattering (DLS), transmisison electron microscopy (TEM), and steady-state fluorescence analysis. Such formation of thermo-responsive vesicles induced by simple structural changes in the copolymers is quite interesting and highly significant in drug delivery applications. PMID:24650226

  17. The interaction of long chain sodium carboxylates and sodium dodecylsulfate with lead(II) ions in aqueous solutions.

    PubMed

    Pereira, Rui F P; Valente, Artur J M; Burrows, Hugh D

    2014-01-15

    The interaction of sodium octanoate, decanoate or dodecanoate with lead(II) has been studied in aqueous solutions using potentiometry, electrical conductivity, turbidity and ICP-OES measurements. These show an alkyl chain length dependence on the behavior. At the lead(II) concentration used (1.0 mM), relatively strong interactions are observed with the decanoate and dodecanaote, leading to formation of the lead carboxylates (soaps) as insoluble complexes. All techniques show 1:2 (metal:carboxylate) stoichiometry corresponding to charge neutralization. With sodium octanoate and lead(II), a rather weaker interaction is seen, and complexation is only observed at metal:carboxylate ratios > 0.5. However, in contrast to our previous work on octanoate and calcium(II) in aqueous solutions [1], precipitation does occur at higher concentrations. This difference between the behavior of the metal ions is probably due to the more covalent nature of the bonds of the carboxylate with Pb(2+) than with Ca(2+). Association constants of the complexes have been determined from potentiometric measurements and are consistent with data on solubility products. A comparison is made of the effect of surfactant head group on the interactions with lead(II) using two surfactants with the same chain length: dodecanoate and dodecylsulfate. Differences in their interactions with this metal ion in aqueous solutions are interpreted in terms of greater covalency of the bond between the metal and the carboxylate than with the sulfate group. PMID:24231086

  18. Preparation of functionalized polystyrene latexes by radiation-induced miniemulsion polymerization using a Y-type polymerizable surfactant as sole stabilizers

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Zhang, Zhicheng; Zhang, Qianfeng

    2009-11-01

    Functionalized polystyrene latexes were prepared by miniemulsion polymerization using a Y-type polymerizable surfactant bearing a carboxylic acid group as sole stabilizers. Kinetics analysis showed that there was no constant rate stage, which coincided with the kinetics mechanism of the typical miniemulsion polymerization. The latexes obtained were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. It was found that the latexes prepared by miniemulsion polymerization initiated by gamma-ray had more narrowly particle size distribution compared with by potassium persulfate. XPS and FTIR results indicated that the carboxyl group was present on the surface of the polymer particles.

  19. A thorough benchmark of density functional methods for general main group thermochemistry, kinetics, and noncovalent interactions.

    PubMed

    Goerigk, Lars; Grimme, Stefan

    2011-04-14

    A thorough energy benchmark study of various density functionals (DFs) is carried out with the new GMTKN30 database for general main group thermochemistry, kinetics and noncovalent interactions [Goerigk and Grimme, J. Chem. Theor. Comput., 2010, 6, 107; Goerigk and Grimme, J. Chem. Theor. Comput., 2011, 7, 291]. In total, 47 DFs are investigated: two LDAs, 14 GGAs, three meta-GGAs, 23 hybrids and five double-hybrids. Besides the double-hybrids, also other modern approaches, i.e., the M05 and M06 classes of functionals and range-separated hybrids, are tested. For almost all functionals, the new DFT-D3 correction is applied in order to consistently test the performance also for important noncovalent interactions; the parameters are taken from previous works or determined for the present study. Basis set and quadrature grid issues are also considered. The general aim of the study is to work out which functionals are generally well applicable and robust to describe the energies of molecules. In summary, we recommend on the GGA level the B97-D3 and revPBE-D3 functionals. The best meta-GGA is oTPSS-D3 although meta-GGAs represent in general no clear improvement compared to numerically simpler GGAs. Notably, the widely used B3LYP functional performs worse than the average of all tested hybrids and is also very sensitive to the application of dispersion corrections. We discourage its usage as a standard method without closer inspection of the results, as it still seems to be often done nowadays. Surprisingly, long-range corrected exchange functionals do in general not perform better than the corresponding standard hybrids. However, the ?B97X-D functional seems to be a promising method. The most robust hybrid is Zhao and Truhlar's PW6B95 functional in combination with DFT-D3. If higher accuracy is required, double-hybrids should be applied. The corresponding DSD-BLYP-D3 and PWPB95-D3 variants are the most accurate and robust functionals of the entire study. Additional calculations with MP2 and and its spin-scaled variants SCS-MP2, S2-MP2 and SOS-MP2 revealed that double-hybrids in general outperform those. Only SCS-MP2 can be recommended, particularly for reaction energies. We suggest its usage when a large self-interaction error is expected that prohibits usage of double-hybrids. Perdews' metaphoric picture of Jacob's Ladder for the classification of density functionals' performance could unbiasedly be confirmed with GMTKN30. We also show that there is no statistical correlation between a functional's accuracy for atomization energies and the performance for chemically more relevant reaction energies. PMID:21384027

  20. Reactivity of yttrium carboxylates toward alkylaluminum hydrides.

    PubMed

    Schädle, Christoph; Fischbach, Andreas; Herdtweck, Eberhardt; Törnroos, Karl W; Anwander, Reiner

    2013-11-25

    Yttrocene-carboxylate complex [Cp*2Y(OOCAr(Me))] (Cp*=C5Me5, Ar(Me) =C6H2Me3-2,4,6) was synthesized as a spectroscopically versatile model system for investigating the reactivity of alkylaluminum hydrides towards rare-earth-metal carboxylates. Equimolar reactions with bis-neosilylaluminum hydride and dimethylaluminum hydride gave adduct complexes of the general formula [Cp*2Y(?-OOCAr(Me))(?-H)AlR2] (R=CH2SiMe3, Me). The use of an excess of the respective aluminum hydride led to the formation of product mixtures, from which the yttrium-aluminum-hydride complex [{Cp*2Y(?-H)AlMe2(?-H)AlMe2(?-CH3)}2] could be isolated, which features a 12-membered-ring structure. The adduct complexes [Cp*2Y(?-OOCAr(Me))(?-H)AlR2] display identical (1)J(Y,H) coupling constants of 24.5 Hz for the bridging hydrido ligands and similar (89)Y NMR shifts of ?=-88.1 ppm (R=CH2SiMe3) and ?=-86.3 ppm (R=Me) in the (89)Y DEPT45 NMR experiments. PMID:24151216

  1. Carboxylic Acid catalyzed hydration of acetaldehyde.

    PubMed

    Rypkema, Heather A; Sinha, Amitabha; Francisco, Joseph S

    2015-05-14

    Electronic structure calculations of the pertinent stationary points on the potential energy surface show that carboxylic acids can act effectively as catalysts in the hydration of acetaldehyde. Barriers to this catalyzed process correlate strongly with the pKa of the acid, providing the potential to provide the predictive capacity of the effectiveness of carboxylic acid catalysts. Transition states for the acid-catalyzed systems take the form of pseudo-six-membered rings through the linear nature of their hydrogen bonds, which accounts for their relative stability compared to the more strained direct and water-catalyzed systems. When considered as a stepwise reaction of a dimerization followed by reaction/complexation, it is likely that collisional stabilization of the prereactive complex is more likely than reaction in the free gas phase, although the catalyzed hydration does retain the potential to proceed on water surfaces or in droplets. Lastly, it is observed that postreactive diol-acid complexes are significantly stable (?12-17 kcal/mol) relative to isolated products, suggesting the possibility of long-lived hygroscopic species that could act as a seed molecule for condensation of secondary organic aerosols. PMID:25734508

  2. Assembly of Acid-Functionalized Single-Walled Carbon Nanotubes at Oil/Water Interfaces

    NASA Astrophysics Data System (ADS)

    Feng, Tao; Hoagland, David; Russell, Thomas

    2014-03-01

    The segregation of water-soluble acid-functionalized single-walled carbon nanotubes (SWCNTs) at the oil/water interface was induced by dissolving low-molecular-weight amine-terminated polystyrene (PS-NH2) in the oil phase. Salt-bridge interactions between carboxylic acid groups of SWCNTs and amine groups of PS drove assembly of a mixed interfacial film, monitored by pendant drop tensiometry and laser scanning confocal microscopy. The influence of PS end-group functionality, PS and SWCNT concentrations, and degree of SWCNT acid modification on interfacial activity were assessed, and a sharp drop in interfacial tension was observed above a critical SWCNT concentration. Interfacial tensions were low enough to support stable oil/water emulsions. Further experiments, including potentiometric titrations and replacement of SWCNTs by other carboxyl-containing species, demonstrated that the interfacial tension drop reflects the loss of SWCNT charge as pH falls near/below the intrinsic carboxyl dissociation constant; species lacking multivalent carboxylic acid groups are inactive. The interfacial assemblies of SWCNTs appear neither ordered nor oriented. Research Advisor.

  3. Assembly of acid-functionalized single-walled carbon nanotubes at oil/water interfaces.

    PubMed

    Feng, Tao; Hoagland, David A; Russell, Thomas P

    2014-02-01

    The efficient segregation of water-soluble, acid-functionalized, single-walled carbon nanotubes (SWCNTs) at the oil/water interface was induced by dissolving low-molecular-weight amine-terminated polystyrene (PS-NH2) in the oil phase. Salt-bridge interactions between carboxylic acid groups of SWCNTs and amine groups of PS drove the assembly of SWCNTs at the interface, monitored by pendant drop tensiometry and laser scanning confocal microscopy. The impact of PS end-group functionality, PS and SWCNT concentrations, and the degree of SWCNT acid modification on the interfacial activity was assessed, and a sharp drop in interfacial tension was observed above a critical SWCNT concentration. Interfacial tensions were low enough to support stable oil/water emulsions. Further experiments, including potentiometric titrations and the replacement of SWCNTs by other carboxyl-containing species, demonstrated that the interfacial tension drop reflects the loss of SWCNT charge as the pH falls near/below the intrinsic carboxyl dissociation constant; species lacking multivalent carboxylic acid groups are inactive. The trapped SWCNTs appear to be neither ordered nor oriented. PMID:24443769

  4. The antimicrobial effects and metabolomic footprinting of carboxyl-capped bismuth nanoparticles against Helicobacter pylori.

    PubMed

    Nazari, P; Dowlatabadi-Bazaz, R; Mofid, M R; Pourmand, M R; Daryani, N E; Faramarzi, M A; Sepehrizadeh, Z; Shahverdi, A R

    2014-01-01

    Organic salts of bismuth are currently used as antimicrobial agents against Helicobacter pylori. This study evaluated the antibacterial effect of elemental bismuth nanoparticles (Bi NPs) using a serial agar dilution method for the first time against different clinical isolates and a standard strain of H. pylori. The Bi NPs were biologically prepared and purified by a recently described method and subjected to further characterization by infrared spectroscopy and anti-H. pylori evaluation. Infrared spectroscopy results showed the presence of carboxyl functional groups on the surface of biogenic Bi NPs. These biogenic nanoparticles showed good antibacterial activity against all tested H. pylori strains. The resulting MICs varied between 60 and 100 ?g/ml for clinical isolates of H. pylori and H. pylori (ATCC 26695). The antibacterial effect of bismuth ions was also tested against all test strains. The antimicrobial effect of Bi ions was lower than antimicrobial effect of bismuth in the form of elemental NPs. The effect of Bi NPs on metabolomic footprinting of H. pylori was further evaluated by (1)H NMR spectroscopy. Exposure of H. pylori to an inhibitory concentration of Bi NPs (100 ?g/ml) led to release of some metabolites such as acetate, formic acid, glutamate, valine, glycine, and uracil from bacteria into their supernatant. These findings confirm that these nanoparticles interfere with Krebs cycle, nucleotide, and amino acid metabolism and shows anti-H. pylori activity. PMID:24104691

  5. catena-Poly[[tri­aqua­copper(II)]-?-5-carb­oxy­benzene-1,3-di­carboxyl­ato-?2 O 1:O 3

    PubMed Central

    Ma, Yu-Hong; Ma, Pi-Zhuang; Yao, Ting; Hao, Jing-Tuan

    2013-01-01

    In the title complex, [Cu(C9H4O6)(H2O)3]n, the CuII cation exhibits a distorted square-pyramidal coordination geometry involving five O atoms from two monodentate 5-carb­oxy­benzene-1,3-di­carboxyl­ate anions and three water mol­ecules. The 5-carb­oxy­benzene-1,3-di­carboxyl­ate anions bridge CuII cations into zigzag polymeric chains running along the b-axis direction. These chains are further linked by O—H?O hydrogen bonds between coordinating water mol­ecules or carboxyl groups and carboxylate groups into a three-dimensional supra­molecular architecture. In the crystal, ?–? stacking is observed between parallel benzene rings of adjacent chains, the centroid–centroid distances being 3.584?(3) and 3.684?(3)?Å. PMID:24098171

  6. Sorption of beryllium from sulfate solutions by amino-carboxylic amphoteric ion-exchange resins (polyampholytes)

    SciTech Connect

    Pakholkov, V.S.; Tsevin, A.P.; Rychkov, V.N.

    1986-05-10

    In studies of sorption of beryllium ions from BeSO4 solutions by a series of aminocarboxylic polyampholytes the influence of pH and of the H2SO4, (NH4)2SO4, and BeSO4 concentrations was demonstrated. The mechanism of the process is postulated on the basis of sorption data and the results of IR-spectroscopic studies. It is concluded that carboxyl groups of polyampholytes take part in ion exchange.

  7. Differential Abundance of Microbial Functional Groups along the Elevation Gradient from the Coast to the Luquillo Mountains

    EPA Science Inventory

    Microbial communities respond to multiple abiotic and biotic factors that change along elevation gradients. We compare changes in microbial community composition in soil and review previous research on differential abundance of microbial functional groups along an elevation gradi...

  8. MODELING THE DYNAMICS OF THREE FUNCTIONAL GROUPS OF MACROALGAE IN TROPICAL SEAGRASS HABITATS. (R828677C004)

    EPA Science Inventory

    A model of three functional groups of macroalgae, drift algae, rhizophytic calcareous algae, and seagrass epiphytes, was developed to complement an existing seagrass production model for tropical habitats dominated by Thalassia testudinum (Turtle-grass). The current modeling e...

  9. Functionalised carboxylic acids in atmospheric particles: An annual cycle revealing seasonal trends and possible sources

    NASA Astrophysics Data System (ADS)

    Teich, Monique; van Pinxteren, Dominik; Herrmann, Hartmut

    2013-04-01

    Carboxylic acids represent a major fraction of the water soluble organic carbon (WSOC) in atmospheric particles. Among the particle phase carboxylic acids, straight-chain monocarboxylic acids (MCA) and dicarboxylic acids (DCA) with 2-10 carbon atoms have extensively been studied in the past. However, only a few studies exist dealing with functionalised carboxylic acids, i.e. having additional hydroxyl-, oxo- or nitro-groups. Regarding atmospheric chemistry, these functionalised carboxylic acids are of particular interest as they are supposed to be formed during atmospheric oxidation processes, e.g. through radical reactions. Therefore they can provide insights into the tropospheric multiphase chemistry. During this work 28 carboxylic acids (4 functionalised aliphatic MCAs, 5 aromatic MCAs, 3 nitroaromatic MCAs, 6 aliphatic DCAs, 6 functionalised aliphatic DCAs, 4 aromatic DCAs) were quantitatively determined in 256 filter samples taken at the rural research station Melpitz (Saxony, Germany) with a PM10 Digitel DHA-80 filter sampler. All samples were taken in 2010 covering a whole annual cycle. The resulting dataset was examined for a possible seasonal dependency of the acid concentrations. Furthermore the influence of the air mass origin on the acid concentrations was studied based on a simple two-sector classification (western or eastern sector) using a back trajectory analysis. Regarding the annual average, adipic acid was found to be the most abundant compound with a mean concentration of 7.8 ng m-3 followed by 4-oxopimelic acid with 6.1 ng m-3. The sum of all acid concentrations showed two maxima during the seasonal cycle; one in summer and one in winter, whereas the highest overall acid concentrations were found in summer. In general the target acids could be divided into two different groups, where one group has its maximum concentration in summer and the other group during winter. The first group contains all investigated aliphatic mono- and dicarboxylic acids. The high concentrations in summer could lead to the conclusion that these acids are mostly formed during photochemical processes in the atmosphere. However, the concentrations in autumn were often exceeded by the ones in winter. Therefore probably other sources beside photochemical processes have to be considered. The second group consists of aromatic compounds. Because of the high concentrations in winter it can be concluded that photochemical formation plays a minor role and primary emission sources e.g., wood combustion are likely. Further evidence in determining sources of the carboxylic acids could be obtained from the air mass origin. In general, air masses transported from East have a more anthropogenic influence than the air mass inflow from West. For all aromatic carboxylic acids higher concentrations were determined during eastern inflow, indicating anthropogenic sources. This presumption is supported by high correlations with the elemental carbon (EC). Regarding the aliphatic carboxylic there is one group with higher concentrations when the air mass is transported from West and one with higher concentrations when air mass is transported from East. In summary the findings of this study reveal a clear difference in the seasonal trends of the single target acids indicating a variety of different sources.

  10. A Combined Transition-Metal-Catalyzed and Photopromoted Process: Synthesis of 2,3-Fused 4-Phenylnaphthalen-1-yl Carboxylates from 1,7-Diaryl-1,6-diynes.

    PubMed

    Yamamoto, Yoshihiko; Mori, Shota; Shibuya, Masatoshi

    2015-06-15

    2,3-Fused 4-phenylnaphthalen-1-yl carboxylates were synthesized in a step- and atom-economical manner using a ruthenium-catalyzed hydrocarboxylative cyclization of 1,7-diaryl-1,6-diynes and subsequent oxidative photocyclization. The scope of this novel two-step process was demonstrated by the construction of diverse structures from substrates with various tethers and terminal aryl groups. Late-stage C?H functionalizations of the arylnaphthalene product further enhance the synthetic potential of the developed process. PMID:25980465

  11. Using multidimensional gas chromatography to group secondary organic aerosol species by functionality

    NASA Astrophysics Data System (ADS)

    Flores, Rosa M.; Doskey, Paul V.

    2014-10-01

    A carbon number-functionality grid (CNFG) for a complex mixture of secondary organic aerosol (SOA) precursors and oxidation products was developed from the theoretical retention index diagram of a multidimensional gas chromatographic (GC × 2GC) analysis of a mixture of SOA precursors and derivatized oxidation products. In the GC × 2GC analysis, comprehensive separation of the complex mixture was achieved by diverting the modulated effluent from a polar primary column into 2 polar secondary columns. Column stationary phases spanned the widest range of selectivity of commercially available GC analytic columns. In general, separation of the species by the polar primary column was by the number of carbon atoms in the molecule (when the homologous series of reference compounds was selected to have molecular volumes and functionalities similar to the target analytes) and the polar secondary columns provided additional separation according to functionality. An algebraic transformation of the Abraham solvation parameter model was used to estimate linear retention indices of solutes relative to elution of a homologous series of methyl diesters on the primary and secondary columns to develop the theoretical GC × 2GC retention diagram. Retention indices of many of the oxidation products of SOA precursors were estimated for derivatized forms of the solutes. The GC stationary phases selected for the primary column [(50%-Trifluoropropyl)-methylpolysiloxane] and secondary columns (90% Cyanopropyl Polysilphenylene-siloxane and Polyethylene Glycol in a Sol-Gel matrix) provided a theoretical separation of 33 SOA precursors and 98 derivatized oxidation products into 35 groups by molecular volume and functionality. Comprehensive analysis of extracts of vapor and aerosol samples containing semivolatile SOA precursors and oxidation products, respectively, is best accomplished by (1) separating the complex mixture of the vapor and underivatized aerosol extracts with a (50%-Trifluoropropyl)-methylpolysiloxane × 90% Cyanopropyl Polysilphenylene-siloxane × Polyethylene Glycol in a Sol-Gel matrix arrangement and (2) derivatizing the aerosol extract and reanalyzing the sample on the GC × 2GC column combination. Quantifying groupings and organic molecular species in time series of collections of vapor- and aerosol-phase atmospheric organic matter is a promising analytic technique for measuring production of SOA and evaluating transformations of SOA precursors.

  12. Automatic analyzer for highly polar carboxylic acids based on fluorescence derivatization-liquid chromatography.

    PubMed

    Todoroki, Kenichiro; Nakano, Tatsuki; Ishii, Yasuhiro; Goto, Kanoko; Tomita, Ryoko; Fujioka, Toshihiro; Min, Jun Zhe; Inoue, Koichi; Toyo'oka, Toshimasa

    2015-03-01

    A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization-liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4-(N,N-dimethylaminosulfonyl)-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD-PZ-carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD-PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC-MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal-to-noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm, which correspond to 95-550 fmol per injection. The intra- and inter-day precisions of typical, highly polar carboxylic acids were all <9.0%. The developed method was successfully applied to the comprehensive analysis of carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells. PMID:25082081

  13. Functional group analysis in coal and on coal surfaces by NMR spectroscopy

    SciTech Connect

    Verkade, J.G.

    1989-10-01

    The reaction of Cl{ovr POCH{sub 2}CH{sub 2}O} (2) with moisture in pyridine extracts of Argonne standard coal samples has been found to give results comparable with the ASTM D3302 moisture analyses of these samples. Differences in the two sets of results are discussed. Some exceptionally large solvent effects on {sup 31}P chemical shifts of model compounds derivatized with 2 and 8 have been discovered. Initial experiments aimed at labile hydrogen functional group analysis of solid coal samples with 2 and Me{sub 2}N{ovr POCH{sub 2}CH{sub 2}O} (15) are described. 17 refs., 1 fig., 6 tabs.

  14. The superstability of d’Alembert’s functional equation on step 2 nilpotent groups

    Microsoft Academic Search

    Ahmed Redouani; Elhoucien Elqorachi; Themistocles M. Rassias

    2007-01-01

    Summary.  In the present paper we study the superstability of d’Alembert’s functional equations\\u000a \\u000a \\u000a \\u000a \\u000a $$f(xy) +f(xy^{-1}) = 2f(x)f(y), x, y \\\\in G, $$\\u000a \\u000a \\u000a \\u000a and\\u000a \\u000a \\u000a \\u000a \\u000a $$f(xy) + f(yx) + f(xy^{-1}) +f(y^{-1}x) = 4f(x)f(y), x, y \\\\in G, $$\\u000a \\u000a \\u000a \\u000a on any step 2 nilpotent group G.

  15. [Trophie webs of reef fishes at Cuba's NW area. II. Functional groups].

    PubMed

    Hernández, Ivet; Aguilar, Consuelo; González Sansón, Gaspar

    2008-09-01

    A conceptual model of the food webs, mainly with fish, was built in a rocky shore of Havana City with data covering from October 2004 to February 2006. The stomach contents of the most abundant fish was complemented with the literature. We used the Relative Importance Index method to describe diets of carnivorous and omnivorous fish; and a modification of the Relative Abundance method for sponge eaters and herbivorous fish. Agglomerative numeric classification techniques were used to determine the diet's similarity. The matrix was made using Bray-Curtis dissimilarity index. Ten functional trophic groups were formed on the basis of diet similarity. The cascade effect is evidenced in this area by the big top predator shortage and the dominance of a few low trophic level species. The regulator role of top predators is low because of over-fishing: the trophic web of this area is highly altered. PMID:19419052

  16. Insight into the contribution of individual functional groups to the flash point of organic compounds.

    PubMed

    Mathieu, Didier; Alaime, Thibaud

    2014-02-28

    Flash point temperatures of organic compounds are predicted on the basis of a power law involving 21 additive contributions associated with non-hydrogen atoms and ring structures. The model is parametrized against a previous data set of 287 simple organic molecules. An average absolute error of 8.6K and a maximal error of about 50K are obtained when applying this model to an external test set of 488 compounds within its applicability domain. The overall performances of the method are remarkable given its simplicity and the small number of parameters involved. In addition, the present work provides valuable insight into the influence of individual functional groups to flash point temperatures. PMID:24444457

  17. Synthesis and modification of functional poly(lactide) copolymers: toward biofunctional materials.

    PubMed

    Noga, David E; Petrie, Timothy A; Kumar, Anjli; Weck, Marcus; García, Andrés J; Collard, David M

    2008-07-01

    A polylactide copolymer with pendant benzyloxy groups has been synthesized by the copolymerization of a benzyl-ether substituted monomer with lactide. Debenzylation of the polymer to provide pendant hydroxyl groups followed by modification with succinic anhydride affords the corresponding carboxylic acid functionalized copolymer that is amenable to standard carbodiimide coupling conditions to attach amine-containing biological molecules. An amino-substituted biotin derivative was coupled to the carboxyl functional groups of copolymer films as proof-of-concept. In a demonstration of the function of these new materials, an RGD-containing peptide sequence was tethered to copolymer films at various densities and was shown to enhance the adhesion of epithelial cells. This strategy provides the opportunity for the attachment of a variety of ligands, allowing for the fabrication of a versatile class of biodegradable, biocompatible materials. PMID:18576683

  18. Surface complexation of carboxylate adheres Cryptosporidium parvum oocysts to the hematite-water interface

    USGS Publications Warehouse

    Gao, X.; Metge, D.W.; Ray, C.; Harvey, R.W.; Chorover, J.

    2009-01-01

    The interaction of viable Cryptosporidium parvum ??ocysts at the hematite (??-Fe2O3)-water interface was examined over a wide range in solution chemistry using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Spectra for hematite-sorbed ??ocysts showed distinctchangesin carboxylate group vibrations relative to spectra obtained in the absence of hematite, indicative of direct chemical bonding between carboxylate groups and Fe metal centers of the hematite surface. The data also indicate that complexation modes vary with solution chemistry. In NaCl solution, ??ocysts are bound to hematite via monodentate and binuclear bidentate complexes. The former predominates at low pH, whereas the latter becomes increasingly prevalent with increasing pH. In a CaCl2 solution, only binuclear bidentate complexes are observed. When solution pH is above the point of zero net proton charge (PZNPC) of hematite, ??ocyst surface carboxylate groups are bound to the mineral surface via outer-sphere complexes in both electrolyte solutions. ?? 2009 American Chemical Society.

  19. An mTERF domain protein functions in group II intron splicing in maize chloroplasts.

    PubMed

    Hammani, Kamel; Barkan, Alice

    2014-04-01

    The mitochondrial transcription termination factor (mTERF) proteins are nucleic acid binding proteins characterized by degenerate helical repeats of ?30 amino acids. Metazoan genomes encode a small family of mTERF proteins whose members influence mitochondrial gene expression and DNA replication. The mTERF family in higher plants consists of roughly 30 members, which localize to mitochondria or chloroplasts. Effects of several mTERF proteins on plant development and physiology have been described, but molecular functions of mTERF proteins in plants are unknown. We show that a maize mTERF protein, Zm-mTERF4, promotes the splicing of group II introns in chloroplasts. Zm-mTERF4 coimmunoprecipitates with many chloroplast introns and the splicing of some of these introns is disrupted even in hypomorphic Zm-mterf4 mutants. Furthermore, Zm-mTERF4 is found in high molecular weight complexes that include known chloroplast splicing factors. The splicing of two transfer RNAs (trnI-GAU and trnA-UGC) and one ribosomal protein messenger RNA (rpl2) is particularly sensitive to the loss of Zm-mTERF4, accounting for the loss of plastid ribosomes in Zm-mTERF4 mutants. These findings extend the known functional repertoire of the mTERF family to include group II intron splicing and suggest that a conserved role in chloroplast RNA splicing underlies the physiological defects described for mutations in BSM/Rugosa2, the Zm-mTERF4 ortholog in Arabidopsis. PMID:24500208

  20. Tree species from different functional groups respond differently to environmental changes during establishment.

    PubMed

    Barbosa, Eduardo R M; van Langevelde, Frank; Tomlinson, Kyle W; Carvalheiro, Luísa G; Kirkman, Kevin; de Bie, Steven; Prins, Herbert H T

    2014-04-01

    Savanna plant communities change considerably across time and space. The processes driving savanna plant species diversity, coexistence and turnover along environmental gradients are still unclear. Understanding how species respond differently to varying environmental conditions during the seedling stage, a critical stage for plant population dynamics, is needed to explain the current composition of plant communities and to enable us to predict their responses to future environmental changes. Here we investigate whether seedling response to changes in resource availability, and to competition with grass, varied between two functional groups of African savanna trees: species with small leaves, spines and N-fixing associations (fine-leaved species), and species with broad leaves, no spines, and lacking N-fixing associations (broad-leaved species). We show that while tree species were strongly suppressed by grass, the effect of resource availability on seedling performance varied considerably between the two functional groups. Nutrient inputs increased stem length only of broad-leaved species and only under an even watering treatment. Low light conditions benefited mostly broad-leaved species' growth. Savannas are susceptible to ongoing global environment changes. Our results suggest that an increase in woody cover is only likely to occur in savannas if grass cover is strongly suppressed (e.g. by fire or overgrazing). However, if woody cover does increase, broad-leaved species will benefit most from the resulting shaded environments, potentially leading to an expansion of the distribution of these species. Eutrophication and changes in rainfall patterns may also affect the balance between fine- and broad-leaved species. PMID:24337711