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Sample records for carboxyl functional groups

  1. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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.

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

    SciTech Connect

    Tretiak, Sergei

    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.

  4. Carboxyl group participation in sulfate and sulfamate group transfer reactions

    SciTech Connect

    Hopkins, A.; Williams, A.

    1982-04-23

    The pH dependence for the hydrolysis of N-(2-carboxyphenyl)sulfamic acid exhibits a plateau region corresponding to participation of the carboxyl function. A normal deuterium oxide solvent isotope effect indicates that proton transfer from the carboxylic acid is concerted with sulfamate group transfer to water. Hydrolysis of salicylic sulfate and N-(2-carboxyphenyl)sulfamate in /sup 18/O-enriched water yields salicylic acid and anthranilic acids with no enrichment, excluding catalysis by neighboring nucleophilic attack on sulfur by the carboxylate group. Intermolecular catalysis by carboxylic acids is demonstrated in the hydrolysis of N-(1-naphthyl)sulfamic acid; the mechanism is shown to involve preequilibrium protonation of the nitrogen followed by nucleophilic attack on sulfur by the carboxylate anion. Fast decomposition of the acyl sulfate completes the hydrolysis; this mechanism is considered to be the most efficient but is excluded in the intramolecular case which is constrained by the electronic requirements of displacement at the sulfur atom (6-ENDO-tet).

  5. Quantifying the Carboxyl Group Density of Microbial Cell Surfaces as a Function of Salinity: Insights Into Microbial Precipitation of Low-Temperature Dolomite

    E-print Network

    Voegerl, Ryan Scott

    2014-08-31

    that carboxyl groups form a cell wall complex with Mg2+, dewatering the magnesium ion and overcoming kinetic barriers that allow dolomite formation at low temperature. Three microorganisms, two that precipitate dolomite in laboratory and field settings...

  6. 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

  7. Ozone-driven photochemical formation of carboxylic acid groups from alkane groups

    NASA Astrophysics Data System (ADS)

    Liu, S.; Day, D. A.; Shields, J. E.; Russell, L. M.

    2011-03-01

    Carboxylic acids are ubiquitous in atmospheric particles, and they play an important role in the physical and chemical properties of aerosol particles. During measurements in coastal California in the summer of 2009, carboxylic acid functional groups were highly associated with trajectories from an industrial region with high organic mass (OM), likely from fossil fuel combustion emissions. The concentration of carboxylic acid groups peaked during daytime, suggesting a photochemical secondary formation mechanism. This daytime increase in concentration was tightly correlated with O3 mixing ratio, indicating O3 was the likely driver in acid formation. Based on the diurnal cycles of carboxylic acid and alkane groups, the covariation of carboxylic acid groups with O3, and the composition of the Combustion factor resulted from the factor analyses, gas-phase alkane oxidation by OH radicals to form dihyfrofuran followed by further oxidation of dihydrofuran by O3 is the likely acid formation mechanism. Using the multi-day average of the daytime increase of carboxylic acid group concentrations and m/z 44-based Aged Combustion factor, we estimated the lower-bound contributions of secondary organic aerosol (SOA) formed in 12-h daytime of processing in a single day to be 30% of the carboxylic acid groups and 25-45% of the Combustion factor concentration. These unique ambient observations of photochemically-driven acid formation suggest that gas-phase alkanes might be important sources of SOA formation in this coastal region.

  8. 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

  9. Ozone-driven daytime formation of secondary organic aerosol containing carboxylic acid groups and alkane groups

    NASA Astrophysics Data System (ADS)

    Liu, S.; Day, D. A.; Shields, J. E.; Russell, L. M.

    2011-08-01

    Carboxylic acids are present in substantial quantities in atmospheric particles, and they play an important role in the physical and chemical properties of aerosol particles. During measurements in coastal California in the summer of 2009, carboxylic acid functional groups were exclusively associated with a fossil fuel combustion factor derived from factor analysis of Fourier transform infrared spectroscopic measurements and closely correlated with oxygenated organic factors from aerosol mass spectrometry measurements. The high fraction of acid groups and the high ratio of oxygen to carbon in this factor suggest that this factor is composed of secondary organic aerosol (SOA) products of combustion emissions from the upwind industrial region (the ports of Los Angeles and Long Beach). Another indication of the photochemically-driven secondary formation of this combustion-emitted organic mass (OM) was the daytime increase in the concentrations of acid groups and the combustion factors. This daytime increase closely tracked the O3 mixing ratio with a correlation coefficient of 0.7, indicating O3 was closely associated with the SOA maximum and thus likely the oxidant that resulted in acid group formation. Using a pseudo-Lagrangian framework to interpret this daytime increase of carboxylic acid groups and the combustion factors, we estimate that the carboxylic acid groups formed in a 12-h daytime period of one day ("Today's SOA") accounted for 25-33 % of the measured carboxylic acid group mass, while the remaining 67-75 % (of the carboxylic acid group mass) was likely formed 1-3 days previously (the "Background SOA"). A similar estimate of the daytime increase in the combustion factors suggests that "Today's SOA" and the "Background SOA" respectively contributed 25-50 % and 50-75 % of the combustion factor (the "Total SOA"), for a "Total SOA" contribution to the OM of 60 % for the project average. Further, size-resolved spectrometric and spectroscopic characterization of the particle OM indicate that the majority of the OM formed by condensation of gas-phase oxidation products. This unique set of measurements and methods to quantify and characterize photochemically and ozone-linked carboxylic acid group formation provide independent and consistent assessments of the secondary fraction of OM, which could result from second generation products of the oxidation of gas-phase alkane (molecules).

  10. 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) ...

  11. Adsorption of UO 2+2 by polyethylene adsorbents with amidoxime, carboxyl, and amidoxime/carboxyl group

    NASA Astrophysics Data System (ADS)

    Choi, Seong-Ho; Nho, Young Chang

    2000-02-01

    The polyethylene (PE) adsorbents were prepared by a radiation-induced grafting of acrylonitrile (AN), acrylic acid (AA), and the mixture of AN/AA onto PE film, and by subsequent amidoximation of cyano groups of poly-AN graft chains. With an increase of AA composition in AN/AA monomer mixture, the water uptake of the grafted polyethylene film increased. In AN/AA mixture, the maximum adsorption of UO 2+2 was observed in the adsorbent with a ratio of AN/AA (50/50, mol%) in copolymer. The amidoxime, carboxyl, and amidoxime/carboxyl groups onto PE acted as a chelating site for the selected UO 2+2. The complex structure of polyethylene with three functional groups and UO 2+2 was confirmed by Fourier Transform Infrared (FTIR) spectroscopy.

  12. Green process for chemical functionalization of nanocellulose with carboxylic acids.

    PubMed

    Espino-Pérez, Etzael; Domenek, Sandra; Belgacem, Naceur; Sillard, Cécile; Bras, Julien

    2014-12-01

    An environmentally friendly and simple method, named SolReact, has been developed for a solvent-free esterification of cellulose nanocrystals (CNC) surface by using two nontoxic carboxylic acids (CA), phenylacetic acid and hydrocinnamic acid. In this process, the carboxylic acids do not only act as grafting agent, but also as solvent media above their melting point. Key is the in situ solvent exchange by water evaporation driving the esterification reaction without drying the CNC. Atomic force microscopy and X-ray diffraction analyses showed no significant change in the CNC dimensions and crystallinity index after this green process. The presence of the grafted carboxylic was characterized by analysis of the "bulk" CNC with elemental analysis, infrared spectroscopy, and (13)C NMR. The ability to tune the surface properties of grafted nanocrystals (CNC-g-CA) was evaluated by X-ray photoelectron spectroscopy analysis. The hydrophobicity behavior of the functionalized CNC was studied through the water contact-angle measurements and vapor adsorption. The functionalization of these bionanoparticles may offer applications in composite manufacturing, where these nanoparticles have limited dispersibility in hydrophobic polymer matrices and as nanoadsorbers due to the presence of phenolic groups attached on the surface. PMID:25353612

  13. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Gao, Peng; Wang, Yun; Guo, Jun; Zhang, Ke-Qin; Du, Dezhuang; Dai, Xiao; Zou, Guifu

    2015-08-01

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  14. Carboxyl functionalization of ultrasmall luminescent silicon nanoparticles through thermal hydrosilylation

    E-print Network

    Braun, Paul

    Carboxyl functionalization of ultrasmall luminescent silicon nanoparticles through thermal and optical properties of silicon nanoparticles (Si-np) are a strong function of size,17,18 allowing them use as environmentally sensitive probes, similar to work that was done with porous silicon

  15. IV. -Amino Acids: carboxyl and amino groups bonded to -Carbo n A. Acid/Base properties

    E-print Network

    Frey, Terry

    IV. -Amino Acids: carboxyl and amino groups bonded to -Carbo n A. Acid/Base properties 1. carboxyl group is proton donor ! weak acid 2. amino group is proton acceptor ! weak base 3. At physiological p natural amino acids (few exceptions) 2. 20 different R groups C. Classification based on R-group - know

  16. Density Functional Theory Study on the Interactions of Metal Ions with Long Chain Deprotonated Carboxylic Acids.

    PubMed

    Mehandzhiyski, Aleksandar Y; Riccardi, Enrico; van Erp, Titus S; Koch, Henrik; Åstrand, Per-Olof; Trinh, Thuat T; Grimes, Brian A

    2015-10-01

    In this work, interactions between carboxylate ions and calcium or sodium ions are investigated via density functional theory (DFT). Despite the ubiquitous presence of these interactions in natural and industrial chemical processes, few DFT studies on these systems exist in the literature. Special focus has been placed on determining the influence of the multibody interactions (with up to 4 carboxylates and one metal ion) on an effective pair-interaction potential, such as those used in molecular mechanics (MM). Specifically, DFT calculations are employed to quantify an effective pair-potential that implicitly includes multibody interactions to construct potential energy curves for carboxylate-metal ion pairs. The DFT calculated potential curves are compared to a widely used molecular mechanics force field (OPLS-AA). The calculations indicate that multibody effects do influence the energetic behavior of these ionic pairs and the extent of this influence is determined by a balance between (a) charge transfer from the carboxylate to the metal ions which stabilizes the complex and (b) repulsion between carboxylates, which destabilizes the complex. Additionally, the potential curves of the complexes with 1 and 2 carboxylates and one counterion have been examined to higher separation distance (20 Å) by the use of relaxed scan optimization and constrained density functional theory (CDFT). The results from the relaxed scan optimization indicate that near the equilibrium distance, the charge transfer between the metal ion and the deprotonated carboxylic acid group is significant and leads to non-negligible differences between the DFT and MM potential curves, especially for calcium. However, at longer separation distances the MM calculated interaction potential functions converge to those calculated with CDFT, effectively indicating the approximate domain of the separation distance coordinate where charge transfer between the ions is occurring. PMID:26331433

  17. FT-IR quantification of aliphatic and carboxyl groups in soil humic fractions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aliphatic and carboxyl groups are two important components in soil humic fractions. Absorbance bands in the ranges of 3020-2800 cm-1 (band A) and 1720-1600 cm-1 (band B) in Fourier Transform Infrared (FT-IR) spectra have been attributed to aliphatic and carboxyl groups, respectively. We prepared mob...

  18. Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 1. Minor structures

    USGS Publications Warehouse

    Leenheer, J.A.; Wershaw, R.L.; Reddy, M.M.

    1995-01-01

    An investigation of the strong-acid characteristics (pKa 3.0 or less) of fulvic acid from the Suwannee River, Georgia, was conducted. Quantitative determinations were made for amino acid and sulfur-containing acid structures, oxalate half-ester structures, malonic acid structures, keto acid structures, and aromatic carboxyl-group structures. These determinations were made by using a variety of spectrometric (13C-nuclear magnetic resonance, infrared, and ultraviolet spectrometry) and titrimetric characterizations on fulvic acid or fulvic acid samples that were chemically derivatized to indicate certain functional groups. Only keto acid and aromatic carboxyl-group structures contributed significantly to the strong-acid characteristics of the fulvic acid; these structures accounted for 43% of the strong-acid acidity. The remaining 57% of the strong acids are aliphatic carboxyl groups in unusual and/or complex configurations for which limited model compound data are available.

  19. Influence of concentration and position of carboxyl groups on the electronic properties of single-walled carbon nanotubes.

    PubMed

    Lara, Ivi Valentini; Zanella, Ivana; de Souza Filho, Antonio Gomes; Fagan, Solange Binotto

    2014-10-21

    The effects of attaching COOH groups at different sites and in various concentrations on electronic and structural properties of (8,0) single-walled carbon nanotubes (SWNT) were investigated using ab initio calculations. The binding energies and the charge transfers between the COOH functional groups and the tube were calculated for several configurations and a novel feature in the electronic structure of these groups was observed. The electronic character of these systems can be modulated by playing with the concentration and the position of the carboxyl groups bonded on the tube wall. The carboxyl groups bound to different carbon atom sub-lattices are more hybridized than those bound in the same one. These results suggested that SWNT-COOH systems are a playground for engineering electronic properties through a proper chemical functionalization which exploit both the attachment site and concentration of functional groups. PMID:25189125

  20. Theoretical insights on the interaction of uranium with amidoxime and carboxyl groups.

    PubMed

    Wang, Cong-Zhi; Lan, Jian-Hui; Wu, Qun-Yan; Luo, Qiong; Zhao, Yu-Liang; Wang, Xiang-Ke; Chai, Zhi-Fang; Shi, Wei-Qun

    2014-09-15

    Recovery of uranium from seawater is extremely challenging but important for the persistent development of nuclear energy, and thus exploring the coordination structures and bonding nature of uranyl complexes becomes essential for designing highly efficient uranium adsorbents. In this work, the interactions of uranium and a series of adsorbents with various well-known functional groups including amidoximate (AO(-)), carboxyl (Ac(-)), glutarimidedioximate (HA(-)), and bifunctional AO(-)/Ac(-), HA(-)/Ac(-) on different alkyl chains (R'?CH3, R??C13H26) were systematically studied by quantum chemical calculations. For all the uranyl complexes, the monodentate and ?(2) coordination are the main binding modes for the AO(-) groups, while Ac(-) groups act as monodentate and bidentate ligands. Amidoximes can also form cyclic imide dioximes (H2A), which coordinate to UO2(2+) as tridentate ligands. Kinetic analysis of the model displacement reaction confirms the rate-determining step in the extraction process, that is, the complexing of uranyl by amidoxime group coupled with the dissociation of the carbonate group from the uranyl tricarbonate complex [UO2(CO3)3](4-). Complexing species with AO(-) groups show higher binding energies than the analogues with Ac(-) groups. However, the obtained uranyl complexes with Ac(-) seem to be more favorable according to reactions with [UO2(CO3)3](4-) as reactant, which may be due to the higher stability of HAO compared to HAc. This is also the reason that species with mixed functional group AO(-)/Ac(-) are more stable than those with monoligand. Thus, as reported in the literature, the adsorbability of uranium can be improved by the synergistic effects of amidoxime and carboxyl groups. PMID:25188818

  1. Kinetics of formation of nanoparticles from first group metal carboxylates

    NASA Astrophysics Data System (ADS)

    Solov'ev, M. E.; Irzhak, T. F.; Irzhak, V. I.

    2015-09-01

    A kinetic model of the formation of metal nanoparticles via reduction of their carboxylates under conditions of clustering is proposed. It is found that the kinetics of the process is characterized by an induction period in carboxylate consumption and by almost linear growth of the average size of nanoparticles with conversion. It is shown that the maximum rate of nanoparticle formation grows along with the rate of ternary associate formation, the induction period becomes longer, and the particle size decreases. At the same time, it is characterized by a narrow size distribution.

  2. Facile Synthesis of Carboxylic Functionalized MFe2O4 (M = Mn, Co, Zn) Nanospheres.

    PubMed

    Xing, Ruimin; Lu, Li; Huang, Haiping; Liu, Shanhu; Niu, Jingyang

    2015-07-01

    A facile one-pot solvothermal method was developed for the synthesis of carboxylic functionalized MFe2O4 (M = Mn, Co, Zn) nanospheres. Field-emission scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectrometer, and a superconducting quantum interference device magnetometer were used to characterize the morphologies, compositions and properties of the functionalized materials. Results show that all of the products were cubic spinel structures and exhibited hierarchical sphere-like morphologies, which were composed of primary nanocrystals. The MFe2O4 present advantageous functionality and good water dispensability due to the preferential exposure of uncoordinated carboxylate groups on their respective surfaces. These properties make them ideal candidates for various important applications such as drug delivery, bioseparation, and magnetic resonance imaging. PMID:26373101

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

    E-print Network

    MacMillan, David W. C.

    Carboxylic 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 of a broad series of carboxylic acids, including hydrocarbon-substituted, - oxy, and -amino acids, provides

  4. 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.

  5. Effects of carboxyl groups on the adsorption behavior of low-molecular-weight substances on a stainless steel surface.

    PubMed

    Nagayasu, Takeshi; Yoshioka, Chisato; Imamura, Koreyoshi; Nakanishi, Kazuhiro

    2004-11-15

    The adsorption isotherms of various carboxylic acids and several amines on a stainless steel surface were taken as a function of pH and the ionic strength of the solution at 30 degrees C. In particular, the effect of the number of carboxyl groups on the adsorption behavior was investigated. Monocarboxylic acids such as benzoic acid and n-butyric acid were reversibly adsorbed on the stainless steel particles and showed a Langmuir-type adsorption isotherm, i.e., Q=KqmC/(1+KC), where Q and C are, respectively, the amount of adsorbate adsorbed and the equilibrium concentration in the bulk solution, qm, the maximum adsorbed amount, and K is the adsorption equilibrium constant. Carboxylic acids having plural carboxyl groups had much higher affinity to the surface and were adsorbed in both reversible and irreversible modes. The adsorption isotherms for the carboxylic acids having plural carboxyl groups could be expressed by a modified Langmuir-type adsorption isotherm, i.e., Q=q(irrev)+Kq(rev)C/(1+KC), where q(irrev) and q(rev) are, respectively, the maximum amounts adsorbed irreversibly and reversibly. The K and q(irrev) values increased with an increase in the number of carboxyl groups except for isophthalic acid and terephthalic acid. On the basis of the pH dependencies of K, qm, q(irrev), and q(rev) as well as the surface properties of the stainless steel, both reversible and irreversible adsorptions were considered to occur through the electrostatic interaction between negatively charged carboxyl groups and the positively charged sites on the surface. The dependency of the q(irrev) value on ionic strength was discussed on the basis of the differences in their adsorbed state with the interaction forces to the surface and repulsive forces among the adsorbed molecules. The adsorption of amine components was quite weak. The RA-IR and molecular dynamics calculation were done to investigate the adsorption states of phthalic acid, trimellitic acid, and mellitic acid. PMID:15464793

  6. 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

  7. Novel Carbazole (Cbz)-Based Carboxylated Functional Monomers: Design, Synthesis, and Characterization

    PubMed Central

    Mondal, Ejabul; Lellouche, Jean-Paul; Naddaka, Maria

    2015-01-01

    A series of novel functional carbazole (Cbz)-based carboxylated monomers were synthesized and characterized. A Clauson-Kaas procedure, a deprotection step, amide coupling, and hydrolysis were utilized as key chemical reactions towards the multistep synthesis of monomers in good to excellent isolated yields. The design strategy was further extended to complex carbazole-COOH monomers incorporated arylazo groups as photoreactive moieties. In addition, photoreactive hybrid carbazole (Cbz)-pyrrole (Pyr)-based carboxylated monomers, comprising a pyrrole core linking a carbazole and a photoreactive phenylazide or benzophenone moiety through an amide spacer in the molecular structure, were also synthesized. The latter can be utilized for surface modification of polymeric films in their monomeric form or as polymeric microparticles (MPs). PMID:26478845

  8. Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 2. Major structures

    USGS Publications Warehouse

    Leenheer, J.A.; Wershaw, R.L.; Reddy, M.M.

    1995-01-01

    Polycarboxylic acid structures that account for the strong-acid characteristics (pKa1 near 2.0) were examined for fulvic acid from the Suwannee River. Studies of model compounds demonstrated that pKa values near 2.0 occur only if the ??-ether or ??-ester groups were in cyclic structures with two to three additional electronegative functional groups (carboxyl, ester, ketone, aromatic groups) at adjacent positions on the ring. Ester linkage removal by alkaline hydrolysis and destruction of ether linkages through cleavage and reduction with hydriodic acid confirmed that the strong carboxyl acidity in fulvic acid was associated with polycarboxylic ??-ether and ??-ester structures. Studies of hypothetical structural models of fulvic acid indicated possible relation of these polycarboxylic structures with the amphiphilic and metal-binding properties of fulvic acid.

  9. Isotope-Encoded Carboxyl Group Footprinting for Mass Spectrometry-Based Protein Conformational Studies

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Liu, Haijun; Blankenship, Robert E.; Gross, Michael L.

    2015-09-01

    We report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded "heavy" and "light" GEE are used to label separately the two states of the orange carotenoid protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the "heavy" and "light" peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting.

  10. Isotope-Encoded Carboxyl Group Footprinting for Mass Spectrometry-Based Protein Conformational Studies.

    PubMed

    Zhang, Hao; Liu, Haijun; Blankenship, Robert E; Gross, Michael L

    2016-01-01

    We report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded "heavy" and "light" GEE are used to label separately the two states of the orange carotenoid protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the "heavy" and "light" peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting. Graphical Abstract ?. PMID:26384685

  11. Silylesterification of oxidized multi-wall carbon nanotubes by catalyzed dehydrogenative cross-coupling between carboxylic and hydrosilane functions

    NASA Astrophysics Data System (ADS)

    Seffer, J.-F.; Detriche, S.; Nagy, J. B.; Delhalle, J.; Mekhalif, Z.

    2014-06-01

    Surface modification of oxidized carbon nanotubes (O-CNTs) with silicon based anchoring groups (R-SiR3) is a relatively uncommon approach of the CNTs functionalization. Hydrosilane derivatives constitute an attractive subclass of compounds for silanization reactions on the CNTs surface. In this work, we report on the ZnCl2 catalytically controlled reaction (hydrosilane dehydrogenative cross-coupling, DHCC) of fluorinated hydrosilane probes with the carboxylic functions present on the surface of oxidized multi-wall carbon nanotubes. Carbon nanotubes functionalized with essentially alcohol groups are also used to compare the selectivity of zinc chloride toward carboxylic groups. To assess the efficiency of functionalization, X-ray Photoelectron Spectroscopy is used to determine the qualitative and quantitative composition of the different samples. Solubility tests on the oxidized and silanized MWNTs are also carried out in the framework of the Hansen Solubility Parameters (HSP) theory to apprehend at another scale the effect of DHCC.

  12. Synthesis of water soluble, biodegradable, and electroactive polysaccharide crosslinker with aldehyde and carboxylic groups for biomedical applications.

    PubMed

    Wang, Qian; He, Wen; Huang, Junqi; Liu, Siwei; Wu, Guifu; Teng, Wei; Wang, Qinmei; Dong, Yugang

    2011-03-10

    We report the synthesis and characterization of a polysaccharide crosslinker of tetraaniline grafting oxidized sodium alginate with large aldehyde and carboxylic groups. We demonstrate that this copolymer has the following properties: it is water soluble under any pH, biodegradable, electroactive, and noncytotoxic; it can self-assemble into nanoparticles with large active functional groups on the outer surface; it can crosslink materials with amino and aminoderivative groups like gelatin to form hydrogels, and thus the electroactivity is readily introduced to the materials. This copolymer has potential applications in biomedical fields such as tissue engineering, drug delivery, and nerve probes where electroactivity is required. PMID:21077224

  13. Mapping of Fab-1:VEGF Interface Using Carboxyl Group Footprinting Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Wecksler, Aaron T.; Kalo, Matt S.; Deperalta, Galahad

    2015-09-01

    A proof-of-concept study was performed to demonstrate that carboxyl group footprinting, a relatively simple, bench-top method, has utility for first-pass analysis to determine epitope regions of therapeutic mAb:antigen complexes. The binding interface of vascular endothelial growth factor (VEGF) and the Fab portion of a neutralizing antibody (Fab-1) was analyzed using carboxyl group footprinting with glycine ethyl ester (GEE) labeling. Tryptic peptides involved in the binding interface between VEGF and Fab-1 were identified by determining the specific GEE-labeled residues that exhibited a reduction in the rate of labeling after complex formation. A significant reduction in the rate of GEE labeling was observed for E93 in the VEGF tryptic peptide V5, and D28 and E57 in the Fab-1 tryptic peptides HC2 and HC4, respectively. Results from the carboxyl group footprinting were compared with the binding interface identified from a previously characterized crystal structure (PDB: 1BJ1). All of these residues are located at the Fab-1:VEGF interface according to the crystal structure, demonstrating the potential utility of carboxyl group footprinting with GEE labeling for mapping epitopes.

  14. Preferential Interaction of Na+ over K+ to Carboxylate-functionalized Silver Nanoparticles

    EPA Science Inventory

    Elucidating mechanistic interactions between specific ions (Na+/ K+) and nanoparticle surfaces to alter particle stability in polar media has received little attention. We investigated relative preferential binding of Na+ and K+ to carboxylate-functionalized silver nanoparticles ...

  15. The comparison between carboxyl, amido and hydroxy group in influencing electrorheological performance

    NASA Astrophysics Data System (ADS)

    Li, Huo; Li, Jun-Ran; Liao, Fu-Hui

    2011-03-01

    Three kinds of electrorheological (ER) materials with carboxyl, amido and hydroxyl group, respectively, were synthesized by a simple adsorption method. The powder of silicon dioxide as a substrate of the materials, as well as terephthalic acid [ p-C6H4(COOH)2, abbr.: phen-COOH], p-phenylenediamine [ p-C6H4(NH2)2, abbr.: phen-NH2] and hydroquinone [ p-C6H4(OH)2, abbr.: phen-OH] were chosen as starting materials. The ER properties of suspensions of the materials in silicon oil were studied. The suspension of the material adsorbing phen-COOH reveals the highest ER activity, the relative shear stress of the suspension (25 wt%), ?r(=?E/?0, ?E and ?0 are the shear stresses at electric field strengths of E=4.2 and 0 kV/mm, respectively), reaches 220 under a DC electric field at a shear rate of 14.5 s-1. The shear stress of the suspension of the material adsorbing phen-NH2 is the largest at an high electric field strength. The ER activity of the material adsorbing phen-OH is the lowest among the three materials. The molecule structure is an importance factor in influencing ER performance of the materials for similar compounds with different polar function groups. The relationship between the ER activity and dielectric property of the materials was discussed.

  16. Copper(II)-Promoted Cyclization/Difunctionalization of Allenols and Allenylsulfonamides: Synthesis of Heterocycle-Functionalized Vinyl Carboxylate Esters.

    PubMed

    Casavant, Barbara J; Khoder, Zainab M; Berhane, Ilyas A; Chemler, Sherry R

    2015-12-18

    A unique method to affect intramolecular aminooxygenation and dioxygenation of allenols and allenylsulfonamides is described. These operationally simple reactions occur under neutral or basic conditions where copper(II) carboxylates serve as reaction promoter, oxidant, and carboxylate source. Moderate to high yields of heterocycle-functionalized vinyl carboxylate esters are formed with moderate to high levels of diastereoselectivity. Such vinyl carboxylate esters could serve as precursors to ?-amino and ?-oxy ketones and derivatives thereof. PMID:26624861

  17. Nonlinear-optical properties of ?-diiminedithiolatonickel(II) complexes enhanced by electron-withdrawing carboxyl groups.

    PubMed

    Pilia, Luca; Pizzotti, Maddalena; Tessore, Francesca; Robertson, Neil

    2014-05-01

    We report the synthesis, characterization, nonlinear-optical (NLO) properties, and density functional theory (DFT) calculations for three nickel diiminedithiolate complexes [Ni(4,4'-R2carboxy-bpy)(L)] [R = methyl, L = 1,2-benzenedithiolate (bdt), 1; R = ethyl, L = 5,6-dihydro-1,4-dithine-2,3-dithiolate (dddt), 2; R = ethyl, L = 1-(N-methylindol-5-yl)ethene-1,2-dithiolate (mi-5edt), 3]. The crystal structure of 1 shows a square-planar coordination for the nickel ion and bond distances consistent with a diiminedithiolate description for the complex. For all complexes, the cyclic voltammetry measurements show two reversible reduction processes (-1.353/-1.380 V and -0798/-0.830 V, respectively) and an anodic wave (+0.372/+0.601 V). The UV-vis spectra present a band around 600-700 nm (? = 4880-6000 dm(3) mol(-1) cm(-1)) mainly attributed to a charge-transfer highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) transition, which shows a large negative solvatochromic shift, characteristic of push-pull complexes, and is responsible for the NLO properties of these molecules. The charge-transfer character of this electronic transition is confirmed by DFT calculations, with the HOMO mainly centered on the dithiolate moiety and the LUMO on the bpy ligand, with important contribution given by the carboxyl groups (?13%). Small contributions from the nickel(II) ion are present in both of the frontier orbitals. The carboxyl groups enhance the optical properties of this class of complexes, confirmed by comparison with the corresponding unsubstituted compounds. The second-order NLO properties have been measured by an electric-field-induced second-harmonic-generation technique using a 10(-3) M solution in N,N-dimethylformamide and working with a 1.907 ?m incident wavelength, giving for ??1.907 (??0) values of -1095 (-581), -2760 (-954), and -1650 (-618) × 10(-48) esu for 1-3, respectively. These values are among the highest in the class of square-planar push-pull complexes, similar to those found for dithionedithiolate compounds. Moreover, spectroelectrochemical experiments demonstrate the possibility of using these complexes as redox-switchable NLO chromophores. PMID:24762131

  18. 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

  19. 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 ...

  20. 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

  1. On the role of humic acids' carboxyl groups in the binding of charged organic compounds.

    PubMed

    Smilek, Ji?í; Sedlá?ek, Petr; Kalina, Michal; Klu?áková, Martina

    2015-11-01

    Interactions of humic acids (HAs) with two cationic dyes (methylene blue and rhodamine 6G) were studied using a unique combination of diffusion and partitioning studies in HAs, containing hydrogels and batch sorption experiments. In order to investigate the involvement of carboxyl groups of HAs in these interactions, all experiments were performed for both, the original lignite HAs and HAs with selectively methylated carboxyls. The results of the diffusion experiments confirm that the interactions between the solute and humic substances have a strong impact on the rate of diffusion process. Surprisingly, the effect is almost equally approved for original and methylated HAs. On the other hand, the results of batch sorption experiments show strong improvement of the sorption capacity (methylated HAs), which is explained by changed morphology of alkylated HAs. The comparison of the results of diffusion and adsorption experiments shows that the diffusion experiments simulate the transport of solutes in natural humics containing environment more reasonably. PMID:26203865

  2. 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.

  3. Target-Specific Capture of Environmentally Relevant Gaseous Aldehydes and Carboxylic Acids with Functional Nanoparticles.

    PubMed

    Campbell, McKenzie L; Guerra, Fernanda D; Dhulekar, Jhilmil; Alexis, Frank; Whitehead, Daniel C

    2015-10-12

    Aldehyde and carboxylic acid volatile organic compounds (VOCs) present significant environmental concern due to their prevalence in the atmosphere. We developed biodegradable functional nanoparticles comprised of poly(d,l-lactic acid)-poly(ethylene glycol)-poly(ethyleneimine) (PDLLA-PEG-PEI) block co-polymers that capture these VOCs by chemical reaction. Polymeric nanoparticles (NPs) preparation involved nanoprecipitation and surface functionalization with branched PEI. The PDLLA-PEG-PEI NPs were characterized by using TGA, IR, (1) H?NMR, elemental analysis, and TEM. The materials feature 1°, 2°, and 3° amines on their surface, capable of capturing aldehydes and carboxylic acids from gaseous mixtures. Aldehydes were captured by a condensation reaction forming imines, whereas carboxylic acids were captured by acid/base reaction. These materials reacted selectively with target contaminants obviating off-target binding when challenged by other VOCs with orthogonal reactivity. The NPs outperformed conventional activated carbon sorbents. PMID:26331393

  4. 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.

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

    PubMed

    Mrsevic, Miroslav; Düsselberg, David; Staudt, Claudia

    2012-01-01

    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

  6. A Convenient, General Synthesis of 1,1-Dimethylallyl Esters as Protecting Groups for Carboxylic Acids

    PubMed Central

    Sedighi, Minoo; Lipton, Mark A.

    2006-01-01

    Carboxylic acids were converted in high yield to their 1,1-dimethylallyl (DMA) esters in two steps. Palladium-catalyzed deprotection of DMA esters was shown to be compatible with tert-butyl, benzyl and Fmoc protecting groups, and Fmoc deprotection could be carried out selectively in the presence of DMA esters. DMA esters were also shown to be resistant to nucleophilic attack, suggesting that they will serve as alternatives to tert-butyl esters when acidic deprotection conditions need to be avoided. PMID:15816730

  7. 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.

  8. Directed nucleation of monomeric and dimeric uranium(VI) complexes with a room temperature carboxyl-functionalized phosphonium ionic liquid.

    PubMed

    Chen, Xiao-Yan; Goff, George S; Quiroz-Guzman, Mauricio; Fagnant, Daniel P; Brennecke, Joan F; Scott, Brian L; Runde, Wolfgang

    2013-03-01

    The carboxyl-functionalized phosphonium ionic liquid (IL), [HCTMP][Tf(2)N], enabled the directed nucleation of monomeric or dimeric uranyl(vi) compounds. This new IL is the first carboxyl-functionalized IL which is liquid at room temperature and exhibits a wider electrochemical window and lower melting point than its ammonium analogue. PMID:23296265

  9. Adsorption of uranium ions by resins with amidoxime and amidoxime/carboxyl group prepared by radiation-induced polymerization

    NASA Astrophysics Data System (ADS)

    Choi, Seong-Ho; Choi, Min-Seok; Park, Yong-Tae; Lee, Kwang-Pill; Kang, Hee-Dong

    2003-06-01

    In order to recover uranium ions from seawater, chelate-type resins with amidoxime and amidoxime/carboxylic acid groups were prepared by radiation-induced polymerization of acrylonitrile (AN) and AN/acrylic acid and by subsequent amidoximation of cyano group of poly(AN), respectively. The resins were characterized by FT-IR, FT-Raman, solid-state 13C-NMR, SEM, and elemental analysis, respectively. The adsorption rate of uranium ion by resins with the amidoxime/carboxylic acid group were higher than that of resins with the amidoxime group. The adsorption of uranium ions in artificial seawater to chelate-type resins was also examined.

  10. 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,…

  11. Simple synthesis of carboxyl-functionalized upconversion nanoparticles for biosensing and bioimaging applications.

    PubMed

    Han, Gui-Mei; Li, Hui; Huang, Xiao-Xi; Kong, De-Ming

    2016-01-15

    We report a simple one-step hydrothermal method for the synthesis of hydrophilic luminescent upconversion nanoparticles (UCNPs) using malonic acid as the stabilizer and functional agent. Using this method, two UCNPs with different colors of upconversion luminescence were synthesized. The surface of the as-prepared UCNPs was capped with carboxyl groups, which not only resulted in the UCNPs having good dispersity in water, but also allowed further conjugation with other functional molecules, thus indicating the potential applications in biosensing and bioimaging. To demonstrate this, amino-labeled single-stranded DNA (ssDNA) was conjugated on the surface of the UCNPs. Based on the different absorption and luminescence quenching abilities of graphene oxide (GO) to ssDNA-modified UCNPs before and after exonuclease I (Exo I)-triggered hydrolysis of ssDNA, a detection platform was developed for the detection of Exo I activity with a detection limit of 0.02UmL(-1). The prepared hydrophilic UCNPs were also used successfully for in vivo upconversion luminescence imaging of nude mice. PMID:26592597

  12. 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

  13. Effect of intramonolayer hydrogen bonding of carboxyl groups in self-assembled monolayers on a single force with phenylurea on an AFM probe tip.

    PubMed

    Kado, Shinpei; Murakami, Tomoo; Kimura, Keiichi

    2006-04-01

    The molecular interaction force of the intermonolayer hydrogen bonding between phenylurea groups on a probe tip and carboxyl groups in self-assembled monolayers was measured directly by means of atomic force microscopy in ethanol. Gold-coated AFM probe tips were modified chemically with 2-(N'-phenylureido)ethanethiol possessing a terminal urea moiety, which is a well-known powerful functionality for forming stable hydrogen bondings with neutral and anionic species. Adhesion force measurements were carried out on gold substrates coated with a COOH-terminated SAM composed of 6-mercaptohexanoic acid in ethanol using the phenylurea-functionalized probe tip. The adhesion force observed was decreased in the presence of H2PO4(-) in the measurement bath, indicating that the intermonolayer hydrogen bonding between the phenylurea moieties and carboxyl groups attached covalently to the probe tip and substrate, respectively, is suppressed by the anion added to the measurement solution. The specific hydrogen-bonding force was measured on binary mixed SAMs prepared by mixing 6-mercaptohexanoic acid with 1-hexanethiol. The individual hydrogen-bonding force between the phenylurea-modified tip and the binary mixed SAMs with various fractions of MHA was evaluated by repetitive force measurements and their statistical analyses by an autocorrelation method. We discuss the effect of diluting the COOH-terminated component in the mixed SAM on the adhesion force and the single force between the phenylurea and carboxyl groups in terms of competition between intermonolayer and intramonolayer hydrogen bonding. PMID:16760591

  14. Renormalization group functional equations

    SciTech Connect

    Curtright, Thomas L.; Zachos, Cosmas K.

    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. Evaluation of a 7-Methoxycoumarin-3-carboxylic Acid Ester Derivative as a Fluorescent, Cell-Cleavable, Phosphonate Protecting Group.

    PubMed

    Wiemer, Andrew J; Shippy, Rebekah R; Kilcollins, Ashley M; Li, Jin; Hsiao, Chia-Hung Christine; Barney, Rocky J; Geng, M Lei; Wiemer, David F

    2016-01-01

    Cell-cleavable protecting groups often enhance cellular delivery of species that are charged at physiological pH. Although several phosphonate protecting groups have achieved clinical success, it remains difficult to use these prodrugs in live cells to clarify biological mechanisms. Here, we present a strategy that uses a 7-methoxycoumarin-3-carboxylic acid ester as a fluorescent protecting group. This strategy was applied to synthesis of an (E)-4-hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) analogue to assess cellular uptake and human V?9V?2 T?cell activation. The fluorescent ester displayed low cellular toxicity (IC50 >100??m) and strong T?cell activation (EC50 =0.018??m) relative to the unprotected anion (EC50 =23??m). The coumarin-derived analogue allowed no-wash analysis of biological deprotection, which revealed rapid internalization of the prodrug. These results demonstrate that fluorescent groups can be applied both as functional drug delivery tools and useful biological probes of drug uptake. PMID:26503489

  17. Dielectric, electric and thermal properties of carboxylic functionalized multiwalled carbon nanotubes impregnated polydimethylsiloxane nanocomposite

    NASA Astrophysics Data System (ADS)

    Sagar, Sadia; Iqbal, Nadeem; Maqsood, Asghari

    2013-06-01

    The dielectric, electric and thermal properties of carboxylic functionalized multiwalled carbon nanotubes (F-MWCNT) incorporated into the polydimethylsiloxane (PDMS) were evaluated to determine their potential in the field of electronic materials. Carboxylic functionalization of the pristine multi walled carbon tubes (Ps-MWCNT) was confirmed through Fourier transform infrared spectroscopy, X-ray diffraction patterns for both Ps-MWCNTs and F-MWCNTs elaborated that crystalline behavior did not change with carboxylic moieties. Thermogravimetric and differential thermal analyses were performed to elucidate the thermal stability with increasing weight % addition of F-MWCNTs in the polymer matrix. Crystallization/glass transition / melting temperatures were evaluated using differential scanning calorimeter and it was observed that glass transition and crystallization temperatures were diminished while temperatures of first and second melting transitions were progressed with increasing F-MWCNT concentration in the PDMS matrix. Scanning electron microscopy and energy dispersive x-ray spectroscopy were carried out to confirm the morphology, functionalization, and uniform dispersion of F-MWCNTs in the polymer matrix. Electrical resistivity at temperature range (100-300°C), dielectric loss (tan?) and dielectric parameters (epsilon/ epsilon//) were measured in the frequency range (1MHz-3GHz). The measured data simulate that the aforementioned properties were influenced by increasing filler contents in the polymer matrix because of the high polarization of conductive F-MWCNTs at the reinforcement/polymer interface.

  18. 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

  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.; Katti, K.V. |; Volkert, W.A. |

    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. The pKa of the General Acid/Base Carboxyl Group of a Glycosidase Cycles during Catalysis: A 13

    E-print Network

    McIntosh, Lawrence P.

    The pKa of the General Acid/Base Carboxyl Group of a Glycosidase Cycles during Catalysis: A 13 C and hence pKa values. 13C-NMR titrations of xylanase, labeled with [-13C]glutamic acid, have revealed p with general acid-catalyzed cleavage of the glycosidic bond. The active site residues responsible for this acid/base

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

    PubMed Central

    2015-01-01

    The direct application of carboxylic acids as a traceless activation group for radical Michael additions has been accomplished via visible light-mediated photoredox catalysis. Photon-induced oxidation of a broad series of carboxylic acids, including hydrocarbon-substituted, ?-oxy, and ?-amino acids, provides a versatile CO2-extrusion platform to generate Michael donors without the requirement for organometallic activation or propagation. A diverse array of Michael acceptors is amenable to this new conjugate addition strategy. An application of this technology to a three-step synthesis of the medicinal agent pregabalin (commercialized by Pfizer under the trade name Lyrica) is also presented. PMID:25032785

  2. 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.

  3. 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

  4. Pyrimidine-2-carboxylic Acid as an Electron-Accepting and Anchoring Group for Dye-Sensitized Solar Cells.

    PubMed

    Wu, Zhifang; Li, Xin; Ågren, Hans; Hua, Jianli; Tian, He

    2015-12-01

    We report a new dye (INPA) adopting pyrimidine-2-carboxylic acid as an electron-accepting and anchoring group to be used in dye-sensitized solar cells. IR spectral analysis indicates that the anchoring group may form two coordination bonds with TiO2 and so facilitate the interaction between the anchoring group and TiO2. The INPA-based cell exhibits an overall conversion efficiency of 5.45%, which is considerably higher than that obtained with cyanoacrylic acid commonly used as the electron acceptor. PMID:26581583

  5. Preparation of non-covalently functionalized graphene using 9-anthracene carboxylic acid.

    PubMed

    Bose, Saswata; Kuila, Tapas; Mishra, Ananta Kumar; Kim, Nam Hoon; Lee, Joong Hee

    2011-10-01

    A simple way of achieving stable aqueous dispersion of graphene by non-covalent functionalization using 9-anthracene carboxylic acid has been successfully accomplished. Unlike in chemically reduced graphene, the C-sp(2) network of the graphene remains undistorted and therefore of superior quality. The non-covalent functionalization facilitates the exfoliation of graphite layers in a polarity controlled combination of media. A detailed exfoliation mechanism is proposed based on the controlled experiment and is supported by the data from UV-vis spectroscopy, transmission electron microscopy, and x-ray diffraction studies. Formation of monolayer graphene has been confirmed from Raman spectroscopy. The graphene based ultracapacitor shows a high value of specific capacitance (148 F g(-1)). PMID:21911926

  6. Preparation of non-covalently functionalized graphene using 9-anthracene carboxylic acid

    NASA Astrophysics Data System (ADS)

    Bose, Saswata; Kuila, Tapas; Mishra, Ananta Kumar; Kim, Nam Hoon; Lee, Joong Hee

    2011-10-01

    A simple way of achieving stable aqueous dispersion of graphene by non-covalent functionalization using 9-anthracene carboxylic acid has been successfully accomplished. Unlike in chemically reduced graphene, the C-sp2 network of the graphene remains undistorted and therefore of superior quality. The non-covalent functionalization facilitates the exfoliation of graphite layers in a polarity controlled combination of media. A detailed exfoliation mechanism is proposed based on the controlled experiment and is supported by the data from UV-vis spectroscopy, transmission electron microscopy, and x-ray diffraction studies. Formation of monolayer graphene has been confirmed from Raman spectroscopy. The graphene based ultracapacitor shows a high value of specific capacitance (148 F g - 1).

  7. The Debaryomyces hansenii carboxylate transporters Jen1 homologues are functional in Saccharomyces cerevisiae.

    PubMed

    Soares-Silva, Isabel; Ribas, David; Foskolou, Iosifina P; Barata, Beatriz; Bessa, Daniela; Paiva, Sandra; Queirós, Odília; Casal, Margarida

    2015-12-01

    We have functionally characterized the four Saccharomyces cerevisiae (Sc) Jen1 homologues of Debaryomyces hansenii (Dh) by heterologous expression in S. cerevisiae. Debaryomyces hansenii cells display mediated transport for the uptake of lactate, acetate, succinate and malate. DHJEN genes expression was detected by RT-PCR in all carbon sources assayed, namely lactate, succinate, citrate, glycerol and glucose. The heterologous expression in the S. cerevisiae W303-1A jen1? ady2? strain demonstrated that the D. hansenii JEN genes encode four carboxylate transporters. DH27 gene encodes an acetate transporter (Km 0.94 ± 0.17 mM; Vmax 0.43 ± 0.03 nmol s(-1) mg(-1)), DH17 encodes a malate transporter (Km 0.27 ± 0.04 mM; Vmax 0.11 ± 0.01 nmol s(-1) mg(-1)) and both DH18 and DH24 encode succinate transporters with the following kinetic parameters, respectively, Km 0.31 ± 0.06 mM; Vmax 0.83 ± 0.04 nmol s(-1) mg(-1)and Km 0.16 ± 0.02 mM; Vmax 0.19 ± 0.02 nmol s(-1) mg(-1). Surprisingly, no lactate transporter was found, although D. hansenii presents a mediated transport for this acid. This work advanced the current knowledge on yeast carboxylate transporters by characterizing four new plasma membrane transporters in D. hansenii. PMID:26500234

  8. Carboxylate-assisted ruthenium-catalyzed alkyne annulations by C-H/Het-H bond functionalizations.

    PubMed

    Ackermann, Lutz

    2014-02-18

    To improve the atom- and step-economy of organic syntheses, researchers would like to capitalize upon the chemistry of otherwise inert carbon-hydrogen (C-H) bonds. During the past decade, remarkable progress in organometallic chemistry has set the stage for the development of increasingly viable metal catalysts for C-H bond activation reactions. Among these methods, oxidative C-H bond functionalizations are particularly attractive because they avoid the use of prefunctionalized starting materials. For example, oxidative annulations that involve sequential C-H and heteroatom-H bond cleavages allow for the modular assembly of regioselectively decorated heterocycles. These structures serve as key scaffolds for natural products, functional materials, crop protecting agents, and drugs. While other researchers have devised rhodium or palladium complexes for oxidative alkyne annulations, my laboratory has focused on the application of significantly less expensive, yet highly selective ruthenium complexes. This Account summarizes the evolution of versatile ruthenium(II) complexes for annulations of alkynes via C-H/N-H, C-H/O-H, or C-H/N-O bond cleavages. To achieve selective C-H bond functionalizations, we needed to understand the detailed mechanism of the crucial C-H bond metalation with ruthenium(II) complexes and particularly the importance of carboxylate assistance in this process. As a consequence, our recent efforts have resulted in widely applicable methods for the versatile preparation of differently decorated arenes and heteroarenes, providing access to among others isoquinolones, 2-pyridones, isoquinolines, indoles, pyrroles, or ?-pyrones. Most of these reactions used Cu(OAc)2·H2O, which not only acted as the oxidant but also served as the essential source of acetate for the carboxylate-assisted ruthenation manifold. Notably, the ruthenium(II)-catalyzed oxidative annulations also occurred under an ambient atmosphere of air with cocatalytic amounts of Cu(OAc)2·H2O. Moreover, substrates displaying N-O bonds served as "internal oxidants" for the syntheses of isoquinolones and isoquinolines. Detailed experimental mechanistic studies have provided strong support for a catalytic cycle that relies on initial carboxylate-assisted C-H bond ruthenation, followed by coordinative insertion of the alkyne, reductive elimination, and reoxidation of the thus formed ruthenium(0) complex. PMID:23379589

  9. Ionization of Functional Groups: The Meaning and Use of the pKa Values Following our discussion of "weak binding forces", solubility, and LogP, we can see that the

    E-print Network

    Gates, Kent. S.

    's review a few facts about acid-base ionization reactions. The acidity for a given functional group related to the Ka is pKa: Defined as: pKa = -logKa. Consider the acid-base ionization of a common functional group found in drugs, the carboxylic acid group. The carboxylic acid group can exist

  10. Stimulation of monocytes and platelets by short-chain phosphatidylcholines with and without terminal carboxyl group.

    PubMed

    Kern, H; Volk, T; Knauer-Schiefer, S; Mieth, T; Rüstow, B; Kox, W J; Schlame, M

    1998-10-01

    Oxidation of unsaturated phosphatidylcholine (PC) produces fragmented phospholipids which have similar bioactivities as the platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-PC). Since a large number of molecular species are produced upon PC oxidation, the active ingredients have not been identified. We synthesized several short-chain PCs which are known to be characteristic PC oxidation products to test their PAF-like activity. The synthetic PCs contained palmitoyl or hexadecyl residues (both C16) in sn-1 position, and propionyl (C3), valeroyl (C5), succinyl (C4 with omega-carboxyl), glutaroyl (C5 with omega-carboxyl), or suberoyl (C8 with omega-carboxyl) residues in sn-2 position. Biological activity was measured by: (1) increase of intracellular calcium in human monocytes; (2) [3H]serotonin release from rabbit platelets; and (3) aggregation of human platelets. Specificity of the cellular response was tested by inhibition with the PAF-receptor antagonists BN 52021 and WEB 2086. Synthetic PC oxidation products activated both monocytes and platelets in a PAF-specific manner. The effective concentration varied with respect to assay system and chemical structure. In general, 1-hexadecyl-PCs were more effective than 1-palmitoyl-PCs, while increasing chain length in sn-2 position lowered biological activity. However, several 1-palmitoyl-PCs activated monocytes in concentrations between 10-8 and 10-6 M. In contrast, platelets were less susceptible to 1-palmitoyl-PCs. No significant difference was found between 2-valeroyl-PC (C5 with omega-methyl) and 2-glutaroyl-PC (C5 with omega-carboxyl). The data suggest that typical products of PC oxidation, containing propionyl, succinyl, or glutaroyl residues in sn-2 position, display PAF-like activity at micromolar concentrations. PMID:9767093

  11. THz and mid-IR spectroscopy of interstellar ice analogs: methyl and carboxylic acid groups.

    PubMed

    Ioppolo, S; McGuire, B A; Allodi, M A; Blake, G A

    2014-01-01

    A fundamental problem in astrochemistry concerns the synthesis and survival of complex organic molecules (COMs) throughout the process of star and planet formation. While it is generally accepted that most complex molecules and prebiotic species form in the solid phase on icy grain particles, a complete understanding of the formation pathways is still largely lacking. To take full advantage of the enormous number of available THz observations (e.g., Herschel Space Observatory, SOFIA, and ALMA), laboratory analogs must be studied systematically. Here, we present the THz (0.3-7.5 THz; 10-250 cm(-1)) and mid-IR (400-4000 cm(-1)) spectra of astrophysically-relevant species that share the same functional groups, including formic acid (HCOOH) and acetic acid (CH3COOH), and acetaldehyde (CH3CHO) and acetone ((CH3)2CO), compared to more abundant interstellar molecules such as water (H2O), methanol (CH3OH), and carbon monoxide (CO). A suite of pure and mixed binary ices are discussed. The effects on the spectra due to the composition and the structure of the ice at different temperatures are shown. Our results demonstrate that THz spectra are sensitive to reversible and irreversible transformations within the ice caused by thermal processing, suggesting that THz spectra can be used to study the composition, structure, and thermal history of interstellar ices. Moreover, the THz spectrum of an individual species depends on the functional group(s) within that molecule. Thus, future THz studies of different functional groups will help in characterizing the chemistry and physics of the interstellar medium (ISM). PMID:25302394

  12. Carboxyl group of residue Asp647 as possible proton donor in catalytic reaction of alpha-glucosidase from Schizosaccharomyces pombe.

    PubMed

    Okuyama, M; Okuno, A; Shimizu, N; Mori, H; Kimura, A; Chiba, S

    2001-04-01

    cDNA encoding Schizosaccharomyces pombe alpha-glucosidase was cloned from a library constructed from mRNA of the fission yeast, and expressed in Saccharomyces cerevisiae. The cDNA, 4176 bp in length, included a single ORF composed of 2910 bp encoding a polypeptide of 969 amino-acid residues with M(r) 106 138. The deduced amino-acid sequence showed a high homology to those of alpha-glucosidases from molds, plants and mammals. Therefore, the enzyme was categorized into the alpha-glucosidase family II. By site-directed mutagenesis, Asp481, Glu484 and Asp647 residues were confirmed to be essential in the catalytic reaction. The carboxyl group (-COOH) of the Asp647 residue was for the first time shown to be the most likely proton donor acting as the acid catalyst in the alpha-glucosidase of family II. Studies with the chemical modifier conduritol B epoxide suggested that the carboxylate group (-COO-) of the Asp481 residue was the catalytic nucleophile, although the role of the Glu484 residue remains obscure. PMID:11298744

  13. Determining the selectivity of divalent metal cations for the carboxyl group of alginate hydrogel beads during competitive sorption.

    PubMed

    An, Byungryul; Lee, Healim; Lee, Soonjae; Lee, Sang-Hyup; Choi, Jae-Woo

    2015-11-15

    To investigate the competitive sorption of divalent metal ions such as Ca(2+), Cu(2+), Ni(2+), and Pb(2+) on alginate hydrogel beads, batch and column tests were conducted. The concentration of carboxyl group was found to be limited in the preparation of spherical hydrogel beads. From kinetic test results, 80% of sorption was observed within 4h, and equilibrium was attained in 48 h. According to the comparison of the total uptake and release, divalent metal ions were found to stoichiometrically interact with the carboxyl group in the alginate polymer chain. From the Langmuir equation, the maximum capacities of Pb(2+), Cu(2+), and Ni(2+) were calculated to be 1.1, 0.48, and 0.13 mmol/g, respectively. The separation factor (?) values for ?Pb/Cu, ?Pb/Ni, and ?Cu/Ni were 14.0, 98.9, and 7.1, respectively. The sorption capacity of Pb(2+) was not affected by the solution pH; however, the sorption capacities of Cu(2+) and Ni(2+) decreased with increasing solution pH, caused by competition with hydrogen. According to the result from the fixed column test, Pb(2+) exhibited the highest affinity, followed by Cu(2+) and Ni(2+), which is in exact agreement with those of kinetic and isotherm tests. The sorbent could be regenerated using 4% HCl, and the regenerated sorbent exhibited 90% capacity upto 9 cycles. PMID:25988716

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

    PubMed

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

    2014-10-01

    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

  15. Effective removal of cationic dyes using carboxylate-functionalized cellulose nanocrystals.

    PubMed

    Qiao, Han; Zhou, Yanmei; Yu, Fang; Wang, Enze; Min, Yinghao; Huang, Qi; Pang, Lanfang; Ma, Tongsen

    2015-12-01

    A novel carboxylate-functionalized adsorbent (CNM) based on cellulose nanocrystals (CNCs) was prepared and adsorptive removal of multiple cationic dyes (crystal violet, methylene blue, malachite green and basic fuchsin) were investigated. The maximum cationic dyes uptakes ranged from 30.0 to 348.9mgg(-1) following the order of: CNM>CNCs>raw cellulose. Furthermore, the removal of crystal violet by CNM was investigated representatively where kinetics, thermodynamics and isotherm analysis were employed to explain in-depth information associated with the adsorption process. The adsorption kinetics fitted well to the pseudo-second-order model and thermodynamic analysis revealed that the adsorption process was spontaneous and exothermic. Meanwhile, isothermal study demonstrated a monolayer adsorption behavior following the Langmuir model with a calculated maximum absorption capacity of 243.9mgg(-1), which is higher than those of many other reported adsorbents. These findings prefigure the promising potentials of CNM as a versatile adsorbent for the efficient removal of cationic dyes from wastewater. PMID:26298027

  16. Functional properties and structural characterization of rice ?1-pyrroline-5-carboxylate reductase

    PubMed Central

    Forlani, Giuseppe; Bertazzini, Michele; Zarattini, Marco; Funck, Dietmar; Ruszkowski, Milosz; Nocek, Bogus?aw

    2015-01-01

    The majority of plant species accumulate high intracellular levels of proline to cope with hyperosmotic stress conditions. Proline synthesis from glutamate is tightly regulated at both the transcriptional and the translational levels, yet little is known about the mechanisms for post-translational regulation of the enzymatic activities involved. The gene coding in rice (Oryza sativa L.) for ?1-pyrroline-5-carboxylate (P5C) reductase, the enzyme that catalyzes the second and final step in this pathway, was isolated and expressed in Escherichia coli. The structural and functional properties of the affinity-purified protein were characterized. As for most species, rice P5C reductase was able to use in vitro either NADH or NADPH as the electron donor. However, strikingly different effects of cations and anions were found depending on the pyridine nucleotide used, namely inhibition of NADH-dependent activity and stimulation of NADPH-dependent activity. Moreover, physiological concentrations of proline and NADP+ were strongly inhibitory for the NADH-dependent reaction, whereas the NADPH-dependent activity was mildly affected. Our results suggest that only NADPH may be used in vivo and that stress-dependent variations in ion homeostasis and NADPH/NADP+ ratio could modulate enzyme activity, being functional in promoting proline accumulation and potentially also adjusting NADPH consumption during the defense against hyperosmotic stress. The apparent molecular weight of the native protein observed in size exclusion chromatography indicated a high oligomerization state. We also report the first crystal structure of a plant P5C reductase at 3.40-Å resolution, showing a decameric quaternary assembly. Based on the structure, it was possible to identify dynamic structural differences among rice, human, and bacterial enzymes. PMID:26284087

  17. Functional properties and structural characterization of rice ?1-pyrroline-5-carboxylate reductase

    SciTech Connect

    Forlani, Giuseppe; Bertazzini, Michele; Zarattini, Marco; Funck, Dietmar; Ruszkowski, Milosz; Nocek, Bogus?aw

    2015-07-28

    The majority of plant species accumulate high intracellular levels of proline to cope with hyperosmotic stress conditions. Proline synthesis from glutamate is tightly regulated at both the transcriptional and the translational levels, yet little is known about the mechanisms for post-translational regulation of the enzymatic activities involved. The gene coding in rice (Oryza sativa L.) for ?1-pyrroline-5-carboxylate (P5C) reductase, the enzyme that catalyzes the second and final step in this pathway, was isolated and expressed in Escherichia coli. The structural and functional properties of the affinity-purified protein were characterized. As for most species, rice P5C reductase was able to use in vitro either NADH or NADPH as the electron donor. However, strikingly different effects of cations and anions were found depending on the pyridine nucleotide used, namely inhibition of NADH-dependent activity and stimulation of NADPH-dependent activity. Moreover, physiological concentrations of proline and NADP+ were strongly inhibitory for the NADH-dependent reaction, whereas the NADPH-dependent activity was mildly affected. Our results suggest that only NADPH may be used in vivo and that stress-dependent variations in ion homeostasis and NADPH/NADP+ ratio could modulate enzyme activity, being functional in promoting proline accumulation and potentially also adjusting NADPH consumption during the defense against hyperosmotic stress. The apparent molecular weight of the native protein observed in size exclusion chromatography indicated a high oligomerization state. We also report the first crystal structure of a plant P5C reductase at 3.40-Å resolution, showing a decameric quaternary assembly. It was possible to identify dynamic structural differences among rice, human, and bacterial enzymes.

  18. Functional properties and structural characterization of rice ?1-pyrroline-5-carboxylate reductase

    DOE PAGESBeta

    Forlani, Giuseppe; Bertazzini, Michele; Zarattini, Marco; Funck, Dietmar; Ruszkowski, Milosz; Nocek, Bogus?aw

    2015-07-28

    The majority of plant species accumulate high intracellular levels of proline to cope with hyperosmotic stress conditions. Proline synthesis from glutamate is tightly regulated at both the transcriptional and the translational levels, yet little is known about the mechanisms for post-translational regulation of the enzymatic activities involved. The gene coding in rice (Oryza sativa L.) for ?1-pyrroline-5-carboxylate (P5C) reductase, the enzyme that catalyzes the second and final step in this pathway, was isolated and expressed in Escherichia coli. The structural and functional properties of the affinity-purified protein were characterized. As for most species, rice P5C reductase was able to usemore »in vitro either NADH or NADPH as the electron donor. However, strikingly different effects of cations and anions were found depending on the pyridine nucleotide used, namely inhibition of NADH-dependent activity and stimulation of NADPH-dependent activity. Moreover, physiological concentrations of proline and NADP+ were strongly inhibitory for the NADH-dependent reaction, whereas the NADPH-dependent activity was mildly affected. Our results suggest that only NADPH may be used in vivo and that stress-dependent variations in ion homeostasis and NADPH/NADP+ ratio could modulate enzyme activity, being functional in promoting proline accumulation and potentially also adjusting NADPH consumption during the defense against hyperosmotic stress. The apparent molecular weight of the native protein observed in size exclusion chromatography indicated a high oligomerization state. We also report the first crystal structure of a plant P5C reductase at 3.40-Å resolution, showing a decameric quaternary assembly. It was possible to identify dynamic structural differences among rice, human, and bacterial enzymes.« less

  19. Discriminating the carboxylic groups from the total acidic sites in oxidized multi-wall carbon nanotubes by means of acid base titration

    NASA Astrophysics Data System (ADS)

    González-Guerrero, Ana Belén; Mendoza, Ernest; Pellicer, Eva; Alsina, Francesc; Fernández-Sánchez, César; Lechuga, Laura M.

    2008-09-01

    This work reports on the quantitative determination of the carboxylic groups created upon HNO 3 treatment at multi-wall carbon nanotube (MWCNT) surface. To this purpose, MWCNTs have been oxidized by refluxing in acid for different periods of time (from 1 h to 12 h). The main goal of the present study comprises the development of a simple analytical methodology based on Boehm's titration that enables the rapid estimation of the total carboxylic groups and their discrimination from the total oxidized sites created at MWCNT surface as a result of the acid treatment. The trends observed are correlated with Raman spectroscopy analyses.

  20. Cationic screening of charged surface groups (carboxylates) affects electron transfer steps in photosystem-II water oxidation and quinone reduction.

    PubMed

    Karge, Oliver; Bondar, Ana-Nicoleta; Dau, Holger

    2014-10-01

    The functional or regulatory role of long-distance interactions between protein surface and interior represents an insufficiently understood aspect of protein function. Cationic screening of surface charges determines the morphology of thylakoid membrane stacks. We show that it also influences directly the light-driven reactions in the interior of photosystem II (PSII). After laser-flash excitation of PSII membrane particles from spinach, time courses of the delayed recombination fluorescence (10?s-10ms) and the variable chlorophyll-fluorescence yield (100?s-1s) were recorded in the presence of chloride salts. At low salt-concentrations, a stimulating effect was observed for the S-state transition efficiency, the time constant of O2-formation at the Mn4Ca-complex of PSII, and the halftime of re-oxidation of the primary quinone acceptor (Qa) by the secondary quinone acceptor (Qb). The cation valence determined the half-effect concentrations of the stimulating salt effect, which were around 6?M, 200?M and 10mM for trivalent (LaCl3), bivalent (MgCl2, CaCl2), and monovalent cations (NaCl, KCl), respectively. A depressing high-salt effect also depended strongly on the cation valence (onset concentrations around 2mM, 50mM, and 500mM). These salt effects are proposed to originate from electrostatic screening of negatively charged carboxylate sidechains, which are found in the form of carboxylate clusters at the solvent-exposed protein surface. We conclude that the influence of electrostatic screening by solvent cations manifests a functionally relevant long-distance interaction between protein surface and electron-transfer reactions in the protein interior. A relation to regulation and adaptation in response to environmental changes is conceivable. PMID:25062950

  1. Phosphorescent biscyclometallated iridium(III) ethylenediamine complexes functionalised with polar ester or carboxylate groups as bioimaging and visualisation reagents.

    PubMed

    Tang, Tommy Siu-Ming; Leung, Kam-Keung; Louie, Man-Wai; Liu, Hua-Wei; Cheng, Shuk Han; Lo, Kenneth Kam-Wing

    2015-03-21

    We report the synthesis, characterisation and photophysical properties of new phosphorescent biscyclometallated iridium(III) ethylenediamine (en) complexes functionalised with polar ester or carboxylate groups [Ir(N^C)2(en)](n)(X) (n = +1, X = Cl(-), HN^C = methyl 4-(2-pyridyl)benzoate Hppy-COOMe (1a), methyl 2-phenyl-4-quinolinecarboxylate Hpq-COOMe (2a); n = -1, X = Li(+), HN^C = 4-(2-pyridyl)benzoate Hppy-COO(-) (1b), 2-phenyl-4-quinolinecarboxylate Hpq-COO(-) (2b)). In aqueous solutions, the carboxylate complexes 1b and 2b displayed emission quenching (ca. 7 and 74 fold, respectively) and lifetime shortening upon protonation, and their pKa values were determined to be 5.13 and 3.46, respectively. The pq complexes 2a and 2b exhibited hypsochromic shifts in their emission maxima and a significant increase in emission intensity (ca. 84 and 15 fold, respectively) upon nonspecific binding to the protein bovine serum albumin (BSA). Inductively coupled plasma-mass spectroscopy (ICP-MS) and laser-scanning confocal microscopy (LSCM) results revealed that the ester complexes 1a and 2a were efficiently internalised by the human cervix epithelioid carcinoma (HeLa) cells through energy-requiring pathways and subsequently localised in endosomes and mitochondria, respectively. They showed good biocompatibility in the dark, but became significantly cytotoxic upon photoirradiation due to the generation of singlet oxygen. In contrast, in aqueous solutions of physiological pH, the carboxylate complexes 1b and 2b existed as the anionic form and hardly entered cells due to limited membrane permeability, as evidenced by the intense emission surrounding the plasma membrane of the cells. They showed negligible cytotoxicity and the cell viability remained over 95% for an incubation period of 24 hours. In view of the low cytotoxicity and strongly emissive nature of the hydrophilic ppy-COO(-) complex 1b in an aqueous medium, the potential application of the complex as a visualisation reagent has been demonstrated using zebrafish (Danio rerio) as an animal model. PMID:25522324

  2. Screening biochars for heavy metal retention in soil: role of oxygen functional groups

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxygen-containing carboxyl, hydroxyl, and phenolic surface functional groups of soil organic and mineral components play central roles in binding metal ions, and biochar amendment can provide means of increasing these surface ligands in soil. In this study, positive matrix factorization (PMF) was f...

  3. Floral Benzenoid Carboxyl Methyltransferases: From in Vitro to in Planta Function

    SciTech Connect

    Effmert,U.; Saschenbrecker, S.; Ross, J.; Negre, F.; Fraser, C.; Noel, J.; Dudareva, N.; Piechulla, B.

    2005-01-01

    Benzenoid carboxyl methyltransferases synthesize methyl esters (e.g., methyl benzoate and methyl salicylate), which are constituents of aromas and scents of many plant species and play important roles in plant communication with the surrounding environment. Within the past five years, eleven such carboxyl methyltransferases were isolated and most of them were comprehensively investigated at the biochemical, molecular and structural level. Two types of enzymes can be distinguished according to their substrate preferences: the SAMT-type enzymes isolated from Clarkia breweri, Stephanotis floribunda, Antirrhinum majus, Hoya carnosa, and Petunia hybrida, which have a higher catalytic efficiency and preference for salicylic acid, while BAMT-type enzymes from A. majus, Arabidopsis thaliana, Arabidopsis lyrata, and Nicotiana suaveolens prefer benzoic acid. The elucidation of C. breweri SAMT's three-dimensional structure allowed a detailed modelling of the active sites of the carboxyl methyltransferases and revealed that the SAM binding pocket is highly conserved among these enzymes while the methyl acceptor binding site exhibits some variability, allowing a classification into SAMT-type and BAMT-type enzymes. The analysis of expression patterns coupled with biochemical characterization showed that these carboxyl methyltransferases are involved either in floral scent biosynthesis or in plant defense responses. While the latter can be induced by biotic or abiotic stress, the genes responsible for floral scent synthesis exhibit developmental and rhythmic expression pattern. The nature of the product and efficiency of its formation in plants depend on the availability of substrates, the catalytic efficiency of the enzyme toward benzoic acid and/or salicylic acid, and the transcriptional, translational, and post-translational regulation at the enzyme level. The biochemical properties of benzenoid carboxyl methyltransferases suggest that the genes involved in plant defenses might represent the ancestor for the presently existing floral genes which during evolution gained different expression profiles and encoded enzymes with the ability to accept structurally similar substrates.

  4. Hydration of "nonfouling" functional groups.

    PubMed

    Hower, Jason C; Bernards, Matthew T; Chen, Shengfu; Tsao, Heng-Kwong; Sheng, Yu-Jane; Jiang, Shaoyi

    2009-01-01

    The prevention of nonspecific protein adsorption to synthetic materials and devices presents a major design challenge in the biomedical community. While some chemical groups can resist nonspecific protein adsorption from simple solutions for limited contact times, there remains a need for new nonfouling functional groups and surface coatings that prevent protein adsorption from complex media like blood or in harsh environments like seawater. Recent studies of the molecular mechanisms of nonfouling surfaces have identified a strong correlation between surface hydration and resistance to nonspecific protein adsorption. In this work, we describe a simple experimental method for evaluating the intrinsic hydration capacity of model surface coating functional groups based on the partial molal volume at infinite dilution. In order to evaluate a range of hydration capacity and nonfouling performance, solutes were selected from three classes: ethylene glycols, sugar alcohols, and glycine analogues. The number of hydrating water molecules bound to a solute was estimated by comparing the molecular volume at infinite dilution to the solute van der Waals molecular volume. The number of water molecules associated with each solute was further validated by constant pressure and temperature molecular dynamics simulations. Finally, a size-normalized molecular volume was correlated to previously observed protein adsorption experiments to relate the intrinsic hydration capacity of functional groups to their known nonfouling abilities. PMID:19072165

  5. Copper-Catalyzed Carboxylation of Aryl Iodides with Carbon Dioxide

    PubMed Central

    Tran-Vu, Hung; Daugulis, Olafs

    2013-01-01

    A method for carboxylation of aryl iodides with carbon dioxide has been developed. The reaction employs low loadings of copper iodide/TMEDA or DMEDA catalyst, 1 atm of CO2, DMSO or DMA solvent, and proceeds at 25–70 °C. Good functional group tolerance is observed, with ester, bromide, chloride, fluoride, ether, hydroxy, amino, and ketone functionalities tolerated. Additionally, hindered aryl iodides such as iodomesitylene can also be carboxylated PMID:24288654

  6. 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

  7. Adsorption of rhodamine B on Rhizopus oryzae: role of functional groups and cell wall components.

    PubMed

    Das, Sujoy K; Ghosh, Piyasa; Ghosh, Indrajit; Guha, Arun K

    2008-08-01

    The role of different functional groups (i.e. amino, carboxyl, hydroxyl as well as phosphate) and cell wall components (such as chitin, chitosan, glucan and phosphomannan) of Rhizopus oryzae on adsorption of rhodamine B is described. The functional groups were chemically modified to determine their contribution in the present adsorption process. Fourier transformed infrared spectroscopic (FTIR) study was used to characterize the modification of the functional groups due to chemical treatments. Carboxyl and amino groups were identified as most important moieties involved in the binding process. Different cell wall components were also isolated from the cell wall to explore their role involved in the binding process. Phosphomannan fraction adsorbed higher amounts of rhodamine B compared to the other cell wall components. Fluorescence microscopic images also supported the differential adsorption capacity of the various cell wall components. PMID:18407472

  8. Synthesis, characterization, and bioactivity of carboxylic acid-functionalized titanium dioxide nanobelts

    PubMed Central

    2014-01-01

    Background Surface modification strategies to reduce engineered nanomaterial (ENM) bioactivity have been used successfully in carbon nanotubes. This study examined the toxicity and inflammatory potential for two surface modifications (humic acid and carboxylation) on titanium nanobelts (TNB). Methods The in vitro exposure models include C57BL/6 alveolar macrophages (AM) and transformed human THP-1 cells exposed to TNB for 24 hrs in culture. Cell death and NLRP3 inflammasome activation (IL-1? release) were monitored. Short term (4 and 24 hr) in vivo studies in C57BL/6, BALB/c and IL-1R null mice evaluated inflammation and cytokine release, and cytokine release from ex vivo cultured AM. Results Both in vitro cell models suggest that the humic acid modification does not significantly affect TNB bioactivity, while carboxylation reduced both toxicity and NLRP3 inflammasome activation. In addition, short term in vivo exposures in both C57BL/6 and IL-1R null mouse strains demonstrated decreased markers of inflammation, supporting the in vitro finding that carboxylation is effective in reducing bioactivity. TNB instillations in IL-1R null mice demonstrated the critical role of IL-1? in initiation of TNB-induced lung inflammation. Neutrophils were completely absent in the lungs of IL-1R null mice instilled with TNB for 24 hrs. However, the cytokine content of the IL-1R null mice lung lavage samples indicated that other inflammatory agents, IL-6 and TNF-? were constitutively elevated indicating a potential compensatory inflammatory mechanism in the absence of IL-1 receptors. Conclusions Taken together, the data suggests that carboxylation, but not humic acid modification of TNB reduces, but does not totally eliminate bioactivity of TNB, which is consistent with previous studies of other long aspect ratio nanomaterials such as carbon nanotubes. PMID:25179214

  9. 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.

  10. Aqueous infrared carboxylate absorbances: Aliphatic di-acids

    USGS Publications Warehouse

    Cabaniss, S.E.; Leenheer, J.A.; McVey, I.F.

    1998-01-01

    Aqueous attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic di-carboxylic acids are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric carboxylate stretch is evident in many cases, so that bands which are nominally due to alkyl groups show increased intensity at higher pH. The asymmetric stretch of the HA- species is linearly related to the microscopic acidity constant of the H2A species, with ??pK 2 intervening atoms). The results suggest that aqueous ATR-FTIR may be able to estimate 'intrinsic' pKa values of carboxylic acids, in addition to providing quantitative estimates of ionization. ?? 1998 Elsevier Science B.V. All rights reserved.

  11. Preparation of Carboxylato-Coordinated Titanium Alkoxides from Carboxylic Anhydrides: Alkoxido Group Transfer from Metal Atom to Carbonyl Group.

    PubMed

    Czakler, Matthias; Artner, Christine; Schubert, Ulrich

    2012-07-01

    Reaction of titanium(IV) isopropoxide, Ti(OiPr)4, with an equimolar amount of phthalic anhydride resulted in the transfer of an isopropoxido group from the metal atom to one carbonyl group of the anhydride and coordination of the thus formed monoester to the titanium atom. One monoester ligand in Ti2(OiPr)6(?2-OOC-C6H4-COOiPr)(?(1)-OOC-C6H4-COOiPr)(iPrOH) is bridging and the other is ?(1)-coordinated. When the reaction is performed in the presence of 1 mol-equiv. of acetic acid, the oxido cluster Ti6(?3-O)6(OiPr)6(?2-OOC-C6H4-COOiPr)6 was instead obtained. The ?3-oxygen groups in the latter compound are due to esterification of acetic acid by the cleaved isopropyl alcohol. PMID:23549605

  12. Preparation of Carboxylato-Coordinated Titanium Alkoxides from Carboxylic Anhydrides: Alkoxido Group Transfer from Metal Atom to Carbonyl Group

    PubMed Central

    Czakler, Matthias; Artner, Christine; Schubert, Ulrich

    2012-01-01

    Reaction of titanium(IV) isopropoxide, Ti(OiPr)4, with an equimolar amount of phthalic anhydride resulted in the transfer of an isopropoxido group from the metal atom to one carbonyl group of the anhydride and coordination of the thus formed monoester to the titanium atom. One monoester ligand in Ti2(OiPr)6(?2-OOC-C6H4-COOiPr)(?1-OOC-C6H4-COOiPr)(iPrOH) is bridging and the other is ?1-coordinated. When the reaction is performed in the presence of 1 mol-equiv. of acetic acid, the oxido cluster Ti6(?3-O)6(OiPr)6(?2-OOC-C6H4-COOiPr)6 was instead obtained. The ?3-oxygen groups in the latter compound are due to esterification of acetic acid by the cleaved isopropyl alcohol. PMID:23549605

  13. Cationic mononuclear ruthenium carboxylates as catalyst prototypes for self-induced hydrogenation of carboxylic acids

    PubMed Central

    Naruto, Masayuki; Saito, Susumu

    2015-01-01

    Carboxylic acids are ubiquitous in bio-renewable and petrochemical sources of carbon. Hydrogenation of carboxylic acids to yield alcohols produces water as the only byproduct, and thus represents a possible next generation, sustainable method for the production of these alternative energy carriers/platform chemicals on a large scale. Reported herein are molecular insights into cationic mononuclear ruthenium carboxylates ([Ru(OCOR)]+) as prototypical catalysts for the hydrogenation of carboxylic acids. The substrate-derived coordinated carboxylate was found to function initially as a proton acceptor for the heterolytic cleavage of dihydrogen, and subsequently also as an acceptor for the hydride from [Ru–H]+, which was generated in the first step (self-induced catalysis). The hydrogenation proceeded selectively and at high levels of functional group tolerance, a feature that is challenging to achieve with existing heterogeneous/homogeneous catalyst systems. These fundamental insights are expected to significantly benefit the future development of metal carboxylate-catalysed hydrogenation processes of bio-renewable resources. PMID:26314266

  14. Control of Surface Functional Groups on Pertechntate Sorption on Activated Carbon

    SciTech Connect

    Y. Wang; H. Gao; R. Yeredla; H. Xu; M. Abrecht; G.D. Stasio

    2006-07-05

    {sup 99}Tc is highly soluble and poorly adsorbed by natural materials under oxidizing conditions, thus being of particular concern for radioactive waste disposal. Activated carbon can potentially be used as an adsorbent for removing Tc from aqueous solutions. We have tested six commercial activated carbon materials for their capabilities for sorption of pertechnetate (TcO{sub 4}{sup -}). The tested materials can be grouped into two distinct types: Type I materials have high sorption capabilities with the distribution coefficients (K{sub d}) varying from 9.5 x 10{sup 5} to 3.2 x 10{sup 3} mL/g as the pH changes from 4.5 to 9.5, whereas type II materials have relatively low sorption capabilities with K{sub d} remaining more or less constant (1.1 x 10{sup 3} - 1.8 x 10{sup 3} mL/g) over a similar pH range. The difference in sorption behavior between the two types of materials is attributed to the distribution of surface functional groups. The predominant surface groups are identified to be carboxylic and phenolic groups. The carboxylic group can be further divided into three subgroups A, B, and C in the order of increasing acidity. The high sorption capabilities of type I materials are found to be caused by the presence of a large fraction of carboxylic subgroups A and B, while the low sorption capabilities of type II materials are due to the exclusive presence of phenolic and carboxylic subgroup C. Therefore, the performance of activated carbon for removing TcO{sub 4}{sup -} can be improved by enhancing the formation of carboxylic subgroups A and B during material processing.

  15. A Functional Analytic Approach to Group Psychotherapy

    ERIC Educational Resources Information Center

    Vandenberghe, Luc

    2009-01-01

    This article provides a particular view on the use of Functional Analytical Psychotherapy (FAP) in a group therapy format. This view is based on the author's experiences as a supervisor of Functional Analytical Psychotherapy Groups, including groups for women with depression and groups for chronic pain patients. The contexts in which this approach…

  16. Statistical investigation of lead removal with various functionalized carboxylate ferroxane nanoparticles.

    PubMed

    Moattari, Rozita M; Rahimi, Safoora; Rajabi, Laleh; Derakhshan, Ali Ashraf; Keyhani, Mohammad

    2015-01-01

    Four new types of carboxylate-ferroxane nanoparticles, namely; maleate ferroxane (MF), fumarateferroxane (FF), para-amino benzoate ferroxane (PABF) and para-hydroxy benzoate ferroxane (PHBF) were synthesized, characterized and used for lead removal from aqueous solutions. Lepidocrocite nanoparticles were also synthesized and characterized asa precursorforcarboxylate-ferroxanes. FTIR, SEM and DLS analysis characterized the synthesized samplesand final Pb(II) concentration were analysed using inductively coupled plasma atomic emission spectrometer. Performance evaluation of the nanoparticlesin adsorption process was achieved using Taguchi experimental design. Variables in adsorption process were initial pH, contact time, adsorbent dose, adsorbent typeand initial concentration of Pb(2+) ions. The initial Pb(II) concentration was the most influential factor in the adsorption process among the five factors. Adsorption of lead was performed through two possible mechanisms; ion exchange and complex formation. Maleate ferroxane performed the best lead removal efficiency among the four types of ferroxane nanostructures studied. The adsorption kinetic data described well with a pseudo-second-order model and the equilibrium data fitted well to the Frendlich isotherm. PMID:25285999

  17. Arginine analogues incorporating carboxylate bioisosteric functions are micromolar inhibitors of human recombinant DDAH-1.

    PubMed

    Tommasi, Sara; Zanato, Chiara; Lewis, Benjamin C; Nair, Pramod C; Dall'Angelo, Sergio; Zanda, Matteo; Mangoni, Arduino A

    2015-12-14

    Dimethylarginine dimethylaminohydrolase (DDAH) is a key enzyme involved in the metabolism of asymmetric dimethylarginine (ADMA) and N-monomethyl arginine (NMMA), which are endogenous inhibitors of the nitric oxide synthase (NOS) family of enzymes. Two isoforms of DDAH have been identified in humans, DDAH-1 and DDAH-2. DDAH-1 inhibition represents a promising strategy to limit the overproduction of NO in pathological states without affecting the homeostatic role of this important messenger molecule. Here we describe the design and synthesis of 12 novel DDAH-1 inhibitors and report their derived kinetic parameters, IC50 and Ki. Arginine analogue 10a, characterized by an acylsulfonamide isosteric replacement of the carboxylate, showed a 13-fold greater inhibitory potential relative to the known DDAH-1 inhibitor, L-257. Compound 10a was utilized to study the putative binding interactions of human DDAH-1 inhibition using molecular dynamics simulations. The latter suggests that several stabilizing interactions occur in the DDAH-1 active-site, providing structural insights for the enhanced inhibitory potential demonstrated by in vitro inhibition studies. PMID:26420019

  18. 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.

  19. The pH-dependence of the Escherichia coli RNase HII-catalysed reaction suggests that an active site carboxylate group participates directly in catalysis.

    PubMed

    Bastock, James A; Webb, Michelle; Grasby, Jane A

    2007-04-27

    RNase HII specifically catalyses the hydrolysis of phosphate diester linkages contained within the RNA portion of DNA/RNA hybrids. The catalytic parameters of the enzyme derived from Escherichia coli BL21 have been measured using 5'-fluorescent oligodeoxynucleotide substrates containing embedded ribonucleotides. The products of the reaction and the chemistry of phosphate diester hydrolysis were assigned unequivocally using mass spectrometry. The pH-dependence of the catalytic parameters was measured under conditions of optimal magnesium ion concentration. The logarithm of the turnover number of the enzyme increases steeply with pH until a pH-independent region is reached close to neutrality. The slope of the pH-dependent region is 2, indicating that the catalytically proficient form of RNase HII is di-anionic. The pH-dependence of log 1/K(M) is a sigmoidal curve reaching a maximal value at higher pH, suggesting deprotonation of a residue stabilises substrate binding. Possible mechanisms for the RNase HII-catalysed reaction consistent with the pH-dependent behaviour of the enzyme are discussed. The active sites of RNase H enzymes contain a cluster of four strictly conserved carboxylate groups. Together, the data suggest a requirement for ionisation of an active site carboxylic acid for metal ion binding or correct positioning of metal ion(s) in the enzyme-substrate complex and a role for a second active site carboxylate in general base catalysis. PMID:17355881

  20. Functional Assessment of Residues in the Amino- and Carboxyl-Termini of Crustacean Hyperglycemic Hormone (CHH) in the Mud Crab Scylla olivacea Using Point-Mutated Peptides

    PubMed Central

    Liu, Chun-Jing; Huang, Shiau-Shan; Toullec, Jean-Yves; Chang, Cheng-Yen; Chen, Yun-Ru; Huang, Wen-San; Lee, Chi-Ying

    2015-01-01

    To assess functional importance of the residues in the amino- and carboxyl-termini of crustacean hyperglycemic hormone in the mud crab Scylla olivacea (Sco-CHH), both wild-type and point-mutated CHH peptides were produced with an amidated C-terminal end. Spectral analyses of circular dichroism, chromatographic retention time, and mass spectrometric analysis of the recombinant peptides indicate that they were close in conformation to native CHH and were produced with the intended substitutions. The recombinant peptides were subsequently used for an in vivo hyperglycemic assay. Two mutants (R13A and I69A rSco-CHH) completely lacked hyperglycemic activity, with temporal profiles similar to that of vehicle control. Temporal profiles of hyperglycemic responses elicited by 4 mutants (I2A, F3A, D12A, and D60A Sco-CHH) were different from that elicited by wild-type Sco-CHH; I2A was unique in that it exhibited significantly higher hyperglycemic activity, whereas the remaining 3 mutants showed lower activity. Four mutants (D4A, Q51A, E54A, and V72A rSco-CHH) elicited hyperglycemic responses with temporal profiles similar to those evoked by wild-type Sco-CHH. In contrast, the glycine-extended version of V72A rSco-CHH (V72A rSco-CHH-Gly) completely lost hyperglycemic activity. By comparing our study with previous ones of ion-transport peptide (ITP) and molt-inhibiting hormone (MIH) using deleted or point-mutated mutants, detail discussion is made regarding functionally important residues that are shared by both CHH and ITP (members of Group I of the CHH family), and those that discriminate CHH from ITP, and Group-I from Group-II peptides. Conclusions summarized in the present study provide insights into understanding of how functional diversification occurred within a peptide family of multifunctional members. PMID:26261986

  1. 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

  2. Functional groups on the surface of calcined special petroleum pyrolysis coke

    SciTech Connect

    Bedretdinova, L.B.; Zakrevskii, E.A.; Kuteinikov, A.F.; Mashkovich, L.A.

    1982-01-01

    Calcined coke, type KNPS, of the below 10 mm size class, obtained under industrial conditions in an 8-retort chamber oven was studied. In order to determine the functional groups the coke was first crushed in agate mortar to a particle size of below 1.2 to 2.0 mm in an isolated cell in an atmosphere of argon. As a result of the analysis the content of functional groups was determiend on the surface of the calcined coke, mg-eq/g: carbonyl 0.34, carboxyl 0.005, and phenol 0.25. The results of the study showed that although the total content of functional groups increased with vibratory milling time, their value, adjusted to a unit of surface area, decreases or remains practically the same in the case of the carboxyl groups. This means that these functional groups are not formed as a result of vibratory milling, but were present before. The vibratory milling only exposed surface oxides not accessible to determination, since the reactions of functional analysis of the cokes occur on the surface in a heterogenous medium. However, in the process of vibratory milling, there is significant absorption of oxygen from the air, forming some sort of surface oxides. In addition, vibratory milling causes the formation of peroxide groups. (JMT)

  3. Transesterification of PHA to oligomers covalently bonded with (bio)active compounds containing either carboxyl or hydroxyl functionalities.

    PubMed

    Kwiecie?, Iwona; Radecka, Iza; Kowalczuk, Marek; Adamus, Gra?yna

    2015-01-01

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

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

    PubMed Central

    Kwiecie?, Iwona; Radecka, Iza; Kowalczuk, Marek; Adamus, Gra?yna

    2015-01-01

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

  5. 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.

  6. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  8. Cobordism Group of Morse Functions on Surfaces

    E-print Network

    Saeki, Osamu

    Cobordism Group of Morse Functions on Surfaces with Boundary Osamu Saeki (Kyushu Univ.) Joint work Dimensional Cases #12;Morse function §1. Introduction §2. Reeb Graph and Reeb Space §3. Proof §4. Low with boundary. A C function f : N R is a Morse function if (1) the critical points of f and f|N are all non

  9. 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...

  10. 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

  11. Water makes the difference: rearrangement of water solvation layer triggers non-additivity of functional group contributions in protein-ligand binding.

    PubMed

    Biela, Adam; Betz, Michael; Heine, Andreas; Klebe, Gerhard

    2012-08-01

    The binding of four congeneric peptide-like thermolysin inhibitors has been studied by high-resolution crystal structure analysis and isothermal titration calorimetry. The ligands differ only by a terminal carboxylate and/or methyl group. A surprising non-additivity of functional group contributions for the carboxylate and/or methyl groups is detected. Adding the methyl first and then the carboxylate group results in a small Gibbs free energy increase and minor enthalpy/entropy partitioning for the first modification, whereas the second involves a strong affinity increase combined with large enthalpy/entropy changes. However, first adding the carboxylate and then the methyl group yields reverse effects: the acidic group attachment now causes minor effects, whereas the added methyl group provokes large changes. As all crystal structures show virtually identical binding modes, affinity changes are related to rearrangements of the first solvation layer next to the S(2)' pocket. About 20-25 water molecules are visible next to the studied complexes. The added COO(-) groups perturb the local water network in both carboxylated complexes, and the attached methyl groups provide favorable interaction sites for water molecules. Apart from one example, a contiguously connected water network between protein and ligand functional groups is observed in all complexes. In the complex with the carboxylated ligand, which still lacks the terminal methyl group, the water network is unfavorably ruptured. This results in a surprising thermodynamic signature showing only a minor affinity increase upon COO(-) group attachment. Because the further added methyl group provides a favorable interaction site for water, the network can be reestablished, and a strong affinity increase with a large enthalpy/entropy signature is then detected. PMID:22733601

  12. Relating Functional Groups to the Periodic Table

    ERIC Educational Resources Information Center

    Struyf, Jef

    2009-01-01

    An introduction to organic chemistry functional groups and their ionic variants is presented. Functional groups are ordered by the position of their specific (hetero) atom in the periodic table. Lewis structures are compared with their corresponding condensed formulas. (Contains 5 tables.)

  13. Biocompatible polymers coated on carboxylated nanotubes functionalized with betulinic acid for effective drug delivery.

    PubMed

    Tan, Julia M; Karthivashan, Govindarajan; Abd Gani, Shafinaz; Fakurazi, Sharida; Hussein, Mohd Zobir

    2016-02-01

    Chemically functionalized carbon nanotubes are highly suitable and promising materials for potential biomedical applications like drug delivery due to their distinct physico-chemical characteristics and unique architecture. However, they are often associated with problems like insoluble in physiological environment and cytotoxicity issue due to impurities and catalyst residues contained in the nanotubes. On the other hand, surface coating agents play an essential role in preventing the nanoparticles from excessive agglomeration as well as providing good water dispersibility by replacing the hydrophobic surfaces of nanoparticles with hydrophilic moieties. Therefore, we have prepared four types of biopolymer-coated single walled carbon nanotubes systems functionalized with anticancer drug, betulinic acid in the presence of Tween 20, Tween 80, polyethylene glycol and chitosan as a comparative study. The Fourier transform infrared spectroscopy studies confirm the bonding of the coating molecules with the SWBA and these results were further supported by Raman spectroscopy. All chemically coated samples were found to release the drug in a slow, sustained and prolonged fashion compared to the uncoated ones, with the best fit to pseudo-second order kinetic model. The cytotoxic effects of the synthesized samples were evaluated in mouse embryonic fibroblast cells (3T3) at 24, 48 and 72 h. The in vitro results reveal that the cytotoxicity of the samples were dependent upon the drug release profiles as well as the chemical components of the surface coating agents. In general, the initial burst, drug release pattern and cytotoxicity could be well-controlled by carefully selecting the desired materials to suit different therapeutic applications. PMID:26704543

  14. High fluorescence emission of carboxylic acid functionalized polystyrene/BaTiO{sub 3} nanocomposites and rare earth metal complexes: Preparation and characterization

    SciTech Connect

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

    2015-03-30

    Noble fluorescence nanocomposite compound based on barium titanate nanoparticles (BTO), polystyrene (PSt), and terbium ion (Tb{sup 3+}) 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 Tb{sup 3+} ions afforded fluorescent Tb{sup 3+} tagged aryl carboxylic acid functionalized polystyrene grafted barium titanate (BTO-g-PSt-Tb{sup 3+}) 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-Tb{sup 3+}nanohybrids. Furthermore, TGA profiles demonstrated the grafting of aryl carboxylic acid functionalized polystyrene on BTO surface. Optical properties of BTO-g-PSt-Tb{sup 3+} complexes were investigated by fluorescence spectroscopy.

  15. 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.

  16. Oxidation of carboxylic acids by horseradish peroxidase results in prosthetic heme modification and inactivation.

    PubMed

    Huang, Liusheng; Colas, Christophe; Ortiz de Montellano, Paul R

    2004-10-13

    Hemoproteins are powerful oxidative catalysts. However, despite the diversity of functions known to be susceptible to oxidation by these catalysts, it is not known whether they can oxidize carboxylic acids to carboxylic radicals. We report here that incubation of horseradish peroxidase (HRP) at acidic pH with H(2)O(2) in acetate buffer results in rapid modification of the heme group and loss of catalytic activity. Mass spectrometry and NMR indicate that an acetoxy group is covalently bound to the delta-meso-carbon in the modified heme. A heme with a hydroxyl group on the 8-methyl is also formed as a minor product. These reactions do not occur if protein-free heme and H(2)O(2) are co-incubated in acetate buffer, if the HRP reaction is carried out at pH 7, in the absence of H(2)O(2), or if citrate rather than acetate buffer is used. A similar heme modification is observed in incubations with n-caproic and phenylacetic acids. A mechanism involving oxidation of the carboxyl group to a carboxylic radical followed by addition to the delta-meso-position is proposed. This demonstration of the oxidation of a carboxylic acid solidifies the proposal that a carboxylic radical mediates the normal covalent attachment of the heme to the protein in the mammalian peroxidases and CYP4 family of P450 enzymes. The hemoprotein-mediated oxidation of carboxylic acids, ubiquitous natural constituents, may play other roles in biology. PMID:15469283

  17. Mild Conversion of ?-Diketones and ?-Ketoesters to Carboxylic Acids

    PubMed Central

    Zhang, Yang; Jiao, Jingliang

    2013-01-01

    A mild protocol for the conversion of ?-ketoesters and ?-diketones to carboxylic acids using CAN in CH3CN is described. The method is compatible with a number of functional groups, and can generate carboxylic acids under neutral conditions at room temperature. The reaction is fast and general, providing an alternative method to the commonly used malonic ester acid preparation. Initial mechanistic studies show that initial oxidation of the enol form of the ?-dicarbonyl initiates the reaction. The presence of nitrate as an oxidant ligand or as an additive is critical for success of the reaction. PMID:16749782

  18. 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

  19. In silico identification of bioisosteric functional groups.

    PubMed

    Ertl, Peter

    2007-05-01

    Bioisosteric replacement is a standard technique that is used in medicinal chemistry to design analogs of bioactive molecules with similar activity and with additional improved characteristics. However, successful bioisosteric design requires significant prior chemical knowledge, and the identification of a replacement group with an optimal balance of steric, hydrophobic, electronic and hydrogen-bonding properties that all influence ligand-receptor interactions usually requires a demanding procedure of trial and error. In this article, various methods that can help medicinal chemists to identify bioisosteric analogs are reviewed, beginning with classical techniques using experimental group properties. Methods to find bioisosteric pairs based on the analysis of large molecular databases are discussed. Various descriptors to characterize properties of functional groups are described, and methods to identify bioisosteric replacement by conducting property similarity search are presented. Examples of tools that help chemists to navigate within the group functional property space are also provided. PMID:17554854

  20. Functional renormalisation group in a finite volume

    E-print Network

    Leonard Fister; Jan Martin Pawlowski

    2015-04-20

    We study a $\\phi^4$-theory at finite temperature in a finite volume. Quantum, thermal and volume fluctuations are treated with the functional renormalisation group. Specifically, we focus on the interplay of temperature and length scales driving the system. We find that thermodynamical observables at finite volume such as the pressure approach the infinite volume limit similarly to that of the vanishing temperature limit. We also advance the functional renormalisation group method at finite volume. In particular, we identify requirements for suitable regulators that admit the exponential thermal and finite volume decay properties.

  1. Functional renormalization group in a finite volume

    NASA Astrophysics Data System (ADS)

    Fister, Leonard; Pawlowski, Jan M.

    2015-10-01

    We study a ?4 theory at finite temperature in a finite volume. Quantum, thermal and volume fluctuations are treated with the functional renormalization group. Specifically, we focus on the interplay of temperature and length scales driving the system. We find that thermodynamical observables at finite volume such as the pressure approach the infinite volume limit similarly to that of the vanishing temperature limit. We also advance the functional renormalization group method at finite volume. In particular, we identify requirements for suitable regulators that admit the exponential thermal and finite volume decay properties.

  2. Real time correlation functions and the functional renormalization group

    NASA Astrophysics Data System (ADS)

    Pawlowski, Jan M.; Strodthoff, Nils

    2015-11-01

    We put forward a functional renormalization group approach for the direct computation of real time correlation functions, also applicable at finite temperature and density. We construct a general class of regulators that preserve the space-time symmetries, and allows the computation of correlation functions at complex frequencies. This includes both imaginary time and real time, and allows in particular the use of the plethora of imaginary time results for the computation of real time correlation functions. We also discuss real time computation on the Keldysh contour with general spatial momentum regulators. Both setups give access to the general momentum and frequency dependence of correlation functions.

  3. Microbial Transformation of Esters of Chlorinated Carboxylic Acids

    PubMed Central

    Paris, D. F.; Wolfe, N. L.; Steen, W. C.

    1984-01-01

    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 group. Microorganisms from environmental waters and a pure culture of Pseudomonas putida U were used. The bacterial populations were monitored by plate counts, and disappearance of the parent compound was followed by gas-liquid chromatography as a function of time. The products of microbial hydrolysis were the respective carboxylic acids. Octanol-water partition coefficients (Kow) for the compounds were measured. These values spanned three orders of magnitude, whereas microbial transformation rate constants (kb) varied only 50-fold. The microbial rate constants of the carboxylic acid esters with a fixed aromatic moiety increased with an increasing length of alkyl substituents. The regression coefficient for the linear relationships between log kb and log Kow was high for group 1 compounds, indicating that these parameters correlated well. The regression coefficient for the linear relationships for group 2 compounds, however, was low, indicating that these parameters correlated poorly. PMID:16346459

  4. Modification of a polyethersulfone matrix by grafting functional groups and the research of biomedical performance.

    PubMed

    Bai, Pengli; Cao, Xuelian; Zhang, Yijia; Yin, Zehua; Wei, Qiang; Zhao, Changsheng

    2010-01-01

    A new method for the functional modification of polyethersulfone (PES) is described in this paper in which PES was sulfonated by chlorosulfonic acid firstly and then chlorinated by phosphorus pentachloride. Thereby, chlorosulfonic groups (-SO2Cl) were introduced in PES successfully, and the degree of the chlorosulfonation was about 15%. Since the chlorosulfonic group is reactive enough towards the amino group (-NH2), the conformation of chlorosulfonic-based covalent bonding functional route could further extend the PES application area with versatile functionality. In this article, hydroxyl (-OH), carboxyl (-COOH), amino (-NH2) and methyl (-CH3) groups were grafted onto a PES matrix through the reaction of chlorosulfonic groups and the amino groups. The functional groups have effects on protein adsorption and cell behavior. The membrane modified with an amino group was in favor of cell adhesion and proliferation, and the membrane modified with hydroxyl and methyl did not so well as the membrane modified with an amino group, which will give guidance for biomaterial modification. PMID:20537241

  5. 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.

  6. Interaction network among functional drug groups

    PubMed Central

    2013-01-01

    Background More attention has been being paid to combinatorial effects of drugs to treat complex diseases or to avoid adverse combinations of drug cocktail. Although drug interaction information has been increasingly accumulated, a novel approach like network-based method is needed to analyse that information systematically and intuitively Results Beyond focussing on drug-drug interactions, we examined interactions between functional drug groups. In this work, functional drug groups were defined based on the Anatomical Therapeutic Chemical (ATC) Classification System. We defined criteria whether two functional drug groups are related. Then we constructed the interaction network of drug groups. The resulting network provides intuitive interpretations. We further constructed another network based on interaction sharing ratio of the first network. Subsequent analysis of the networks showed that some features of drugs can be well described by this kind of interaction even for the case of structurally dissimilar drugs. Conclusion Our networks in this work provide intuitive insights into interactions among drug groups rather than those among single drugs. In addition, information on these interactions can be used as a useful source to describe mechanisms and features of drugs. PMID:24555875

  7. NUCLEAR CHIRAL THERMODYNAMICS FUNCTIONAL RENORMALIZATION GROUP

    E-print Network

    Weise, Wolfram

    1 NUCLEAR CHIRAL THERMODYNAMICS and the FUNCTIONAL RENORMALIZATION GROUP Wolfram Weise ECT* Trento potential VC(r) with NGauss = 5. (Right) The scatterin 1 Nuclear Forces Hierarchy of SCALES Early history: M(kF/m) in ] IN-MEDIUM CHIRAL PERTURBATION THEORY Nuclear thermodynamics: compute free energy density (3-loop

  8. 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

  9. Mass spectrometry-based carboxyl footprinting of proteins: Method evaluation

    SciTech Connect

    Zhang, Hao; Wen, Jianzhong; Huang, Richard Y-C.; Blankenship, Robert E.; Gross, Michael L.

    2012-02-01

    Protein structure determines function in biology, and a variety of approaches have been employed to obtain structural information about proteins. Mass spectrometry-based protein footprinting is one fast-growing approach. One labeling-based footprinting approach is the use of a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and glycine ethyl ester (GEE) to modify solvent-accessible carboxyl groups on glutamate (E) and aspartate (D). This paper describes method development of carboxyl-group modification in protein footprinting. The modification protocol was evaluated by using the protein calmodulin as a model. Because carboxyl-group modification is a slow reaction relative to protein folding and unfolding, there is an issue that modifications at certain sites may induce protein unfolding and lead to additional modification at sites that are not solvent-accessible in the wild-type protein. We investigated this possibility by using hydrogen deuterium amide exchange (H/DX). The study demonstrated that application of carboxyl group modification in probing conformational changes in calmodulin induced by Ca{sup 2+} binding provides useful information that is not compromised by modification-induced protein unfolding.

  10. 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

  11. The circular velocity function of group galaxies

    SciTech Connect

    Abramson, Louis E.; Williams, Rik J.; Benson, Andrew J.; Kollmeier, Juna A.; Mulchaey, John S.

    2014-09-20

    A robust prediction of ?CDM cosmology is the halo circular velocity function (CVF), a dynamical cousin of the halo mass function. The correspondence between theoretical and observed CVFs is uncertain, however: cluster galaxies are reported to exhibit a power-law CVF consistent with N-body simulations, but that of the field is distinctly Schechter-like, flattened compared to ?CDM expectations at circular velocities v {sub c} ? 200 km s{sup –1}. Groups offer a powerful probe of the role environment plays in this discrepancy as they bridge the field and clusters. Here, we construct the CVF for a large, mass- and multiplicity-complete sample of group galaxies from the Sloan Digital Sky Survey. Using independent photometric v {sub c} estimators, we find no transition from field to ?CDM-shaped CVF above v {sub c} = 50 km s{sup –1} as a function of group halo mass. All groups with 12.4 ? log M {sub halo}/M {sub ?} ? 15.1 (Local Group analogs to rich clusters) display similar Schechter-like CVFs marginally suppressed at low v {sub c} compared to that of the field. Conversely, some agreement with N-body results emerges for samples saturated with late-type galaxies, with isolated late-types displaying a CVF similar in shape to ?CDM predictions. We conclude that the flattening of the low-v {sub c} slope in groups is due to their depressed late-type fractions—environment affecting the CVF only to the extent that it correlates with this quantity—and that previous cluster analyses may suffer from interloper contamination. These results serve as useful benchmarks for cosmological simulations of galaxy formation.

  12. The Circular Velocity Function of Group Galaxies

    NASA Astrophysics Data System (ADS)

    Abramson, Louis E.; Williams, Rik J.; Benson, Andrew J.; Kollmeier, Juna A.; Mulchaey, John S.

    2014-09-01

    A robust prediction of ?CDM cosmology is the halo circular velocity function (CVF), a dynamical cousin of the halo mass function. The correspondence between theoretical and observed CVFs is uncertain, however: cluster galaxies are reported to exhibit a power-law CVF consistent with N-body simulations, but that of the field is distinctly Schechter-like, flattened compared to ?CDM expectations at circular velocities v c <~ 200 km s-1. Groups offer a powerful probe of the role environment plays in this discrepancy as they bridge the field and clusters. Here, we construct the CVF for a large, mass- and multiplicity-complete sample of group galaxies from the Sloan Digital Sky Survey. Using independent photometric v c estimators, we find no transition from field to ?CDM-shaped CVF above v c = 50 km s-1 as a function of group halo mass. All groups with 12.4 <~ log M halo/M ? <~ 15.1 (Local Group analogs to rich clusters) display similar Schechter-like CVFs marginally suppressed at low v c compared to that of the field. Conversely, some agreement with N-body results emerges for samples saturated with late-type galaxies, with isolated late-types displaying a CVF similar in shape to ?CDM predictions. We conclude that the flattening of the low-v c slope in groups is due to their depressed late-type fractions—environment affecting the CVF only to the extent that it correlates with this quantity—and that previous cluster analyses may suffer from interloper contamination. These results serve as useful benchmarks for cosmological simulations of galaxy formation.

  13. 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

  14. Use of sterically hindered carboxylate ligands to model structural and functional features of dioxygen-activating centers in non-heme diiron enzymes

    E-print Network

    Lee, Dongwhan, 1970-

    2002-01-01

    Chapter I. Modeling Dioxygen-Activating Centers in Non-Heme Diiron Enzymes: Carboxylate Shifts in Diiron(II) Complexes Supported by Sterically Hindered Carboxylate Ligands General synthetic routes are described for a series ...

  15. 1-Azaniumylcyclobutane-1-carboxylate monohydrate

    NASA Technical Reports Server (NTRS)

    Butcher, Ray J.; Brewer, Greg; Burton, Aaron S.; Dworkin, Jason

    2014-01-01

    In the title compound, C5H9NO2H2O, the amino acid is in the usual zwitterionic form involving the carboxylate group. The cyclobutane backbone of the amino acid is disordered over two conformations, with occupancies of 0.882 (7) and0.118 (7). In the crystal, NH O and OH O hydrogen bonds link the zwitterions [with the water molecule involved as both acceptor (with the NH3+) and donor (through a single carboxylate O from two different aminocyclobutane carboxylatemoities)], resulting in a two-dimensional layered structure lying parallel to (100).

  16. Synthesis of carboxylate-functionalized graphene nanosheets for high dispersion of platinum nanoparticles based on the reduction of graphene oxide via 1-pyrenecarboxaldehyde.

    PubMed

    Kuang, Yinjie; Chen, Jinhua; Zheng, Xingliang; Zhang, Xiaohua; Zhou, Qionghua; Lu, Cuihong

    2013-10-01

    A one-step reduction/functionalization strategy for the synthesis of carboxylate-functionalized graphene nanosheets is reported in this paper. 1-pyrenecarboxaldehyde (PCA) is introduced as a new reductant for the chemical reduction of graphene oxide (GO), serving three roles: reducing GO to graphene nanosheets (GNs), stabilizing the as-prepared GNs due to the electrostatic repulsion of the oxidation products of PCA (1-pyrenecarboxylate, PC?) on the surface of the GNs and anchoring Pt nanoparticles (Pt NPs) with high dispersion and small particle size. Transmission electron microscopy shows that Pt NPs with an average diameter of 1.3 ± 0.2 nm are uniformly dispersed on the surface of the PC?-functionalized GNs (PC?-GNs). The obtained Pt NPs/PC?-GNs nanohybrids have higher electrocatalytic activity and stability towards methanol oxidation in comparison with Pt NPs supported on GNs obtained by the chemical reduction of GO with the typical reductant, hydrazine. PMID:24013585

  17. Computational Studies on Pd-Catalyzed Functionalization of Csp(2)-H Bonds Using a 1,2,3-Triazole Directing Group: Cyclization versus Substitution.

    PubMed

    Li, Juan; Du, Lijuan; Gu, Honghong

    2015-11-01

    The Pd-catalyzed functionalization of Csp(2)-H bonds using a 1,2,3-triazole directing group has been investigated by density functional theory calculations at the B3LYP level. The results of these calculations showed that the substitution pathway was kinetically favored over the cyclization pathway for the N2-pyridine-1,2,3-triazole-4-carboxylic acid (TAPy)-directed functionalization of Csp(2)-H bonds, while the cyclization pathway was kinetically favored over the substitution pathway for the N1-aryl-1,2,3-triazole-4-carboxylic acid (TAA)-directed Csp(2)-H functionalization. The kinetic preference of the TAPy directing group for the substitution reaction can be attributed the reduced level of bond cleavage in the transition structure of the substitution step because the pyridine moiety of the TAPy directing group can act as a ligand for the Pd center. PMID:26484381

  18. 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.

  19. Contribution of cytochrome P450 and UDT-glucuronosyltransferase to the metabolism of drugs containing carboxylic acid groups: risk assessment of acylglucuronides using human hepatocytes.

    PubMed

    Jinno, Norimasa; Tagashira, Mizuka; Tsurui, Kazuyuki; Yamada, Shizuo

    2014-08-01

    1.?In order to evaluate the inhibition activity of 1-aminobenzotriazole (ABT) and (-)-borneol (borneol) against cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT), the substrates of these metabolic enzymes were incubated with ABT and borneol in human hepatocytes. We found that 3?mM ABT and 300??M borneol were the most suitable experimental levels to specifically inhibit CYP and UGT. 2.?Montelukast, mefenamic acid, flufenamic acid, diclofenac, tienilic acid, gemfibrozil, ibufenac and repaglinide were markedly metabolized in human hepatocytes, and the metabolism of gemfibrozil, mefenamic acid and flufenamic acid was inhibited by borneol. With regard to repaglinide, montelukast, diclofenac and tienilic acid, metabolism was inhibited by ABT. Ibufenac was partly inhibited by both inhibitors. Zomepirac, tolmetin, ibuprofen, indomethacin and levofloxacin were moderately metabolized by human hepatocytes, and the metabolism of zomepirac, ibuprofen and indomethacin was equally inhibited by both ABT and borneol. The metabolism of tolmetin was strongly inhibited by ABT, and was also inhibited weakly by borneol. Residual drugs, telmisartan, valsartan, furosemide, naproxen and probenecid were scarcely metabolized. 3.?Although we attempted to predict the toxicological risks of drugs containing carboxylic groups from the combination chemical stability and CLint via UGT, the results indicated that this combination was not sufficient and that clinical daily dose is important. PMID:24575896

  20. Functional modulation of cerebral gamma-aminobutyric acidA receptor/benzodiazepine receptor/chloride ion channel complex with ethyl beta-carboline-3-carboxylate: Presence of independent binding site for ethyl beta-carboline-3-carboxylate

    SciTech Connect

    Taguchi, J.; Kuriyama, K. )

    1990-05-01

    Effect of ethyl beta-carboline-3-carboxylate (beta-CCE) on the function of gamma-aminobutyric acid (GABA)A receptor/benzodiazepine receptor/chloride ion channel complex was studied. Beta-CCE noncompetitively and competitively inhibited (3H)flunitrazepam binding to benzodiazepine receptor, but not (3H)muscimol binding to GABAA receptor as well as t-(3H)butylbicycloorthobenzoate (( 3H) TBOB) binding to chloride ion channel, in particulate fraction of the mouse brain. Ro15-1788 also inhibited competitively (3H) flunitrazepam binding. On the other hand, the binding of beta-(3H)CCE was inhibited noncompetitively and competitively by clonazepam and competitively by Ro15-1788. In agreement with these results, benzodiazepines-stimulated (3H)muscimol binding was antagonized by beta-CCE and Ro15-1788. Gel column chromatography for the solubilized fraction from cerebral particulate fraction by 0.2% sodium deoxycholate (DOC-Na) in the presence of 1 M KCl indicated that beta-(3H)CCE binding site was eluted in the same fraction (molecular weight, 250,000) as the binding sites for (3H)flunitrazepam, (3H)muscimol and (3H)TBOB. GABA-stimulated 36Cl- influx into membrane vesicles prepared from the bovine cerebral cortex was stimulated and attenuated by flunitrazepam and beta-CCE, respectively. These effects of flunitrazepam and beta-CCE on the GABA-stimulated 36Cl- influx were antagonized by Ro15-1788. The present results suggest that the binding site for beta-CCE, which resides on GABAA receptor/benzodiazepine receptor/chloride ion channel complex, may be different from that for benzodiazepine. Possible roles of beta-CCE binding site in the allosteric inhibitions on benzodiazepine binding site as well as on the functional coupling between chloride ion channel and GABAA receptor are also suggested.

  1. Identification of the functional groups on the surface of nanoparticles formed in photonucleation of aldehydes generated during forest fire events

    NASA Astrophysics Data System (ADS)

    Dultsev, Fedor N.; Mik, Ivan A.; Dubtsov, Sergei N.; Dultseva, Galina G.

    2014-11-01

    We describe the new procedure developed to determine the functional groups on the surface of nanoparticles formed in photonucleation of furfural, one of the aldehydes generated during forest fire events. The procedure is based on the detection of nanoparticle rupture from chemically modified surface of the quartz crystal microbalance oscillating in the thickness shear mode under voltage sweep. The rupture force is determined from the voltage at which the rupture occurs. It depends on particle mass and on the affinity of the surface functional groups of the particle to the groups that are present on the modified QCM surface. It was demonstrated with the amine modification of the surface that the nanoparticles formed in furfural photonucleation contain carbonyl and carboxyl groups. The applicability of the method for the investigation of functional groups on the surface of the nanoparticles of atmospheric aerosol is demonstrated.

  2. Palladium-catalyzed decarboxylative trifluoroethylation of aryl alkynyl carboxylic acids.

    PubMed

    Hwang, Jinil; Park, Kyungho; Choe, Juseok; Min, Hongkeun; Song, Kwang Ho; Lee, Sunwoo

    2014-04-01

    A trifluoroethylation of alkynes through a palladium-catalyzed decarboxylative coupling reaction was developed. When alkynyl carboxylic acids and ICH2CF3 were allowed to react with [Pd(?(3)-allyl)Cl]2/XantPhos and Cs2CO3 in N,N-dimethylformamide (DMF) at 80 °C for 1 h, the desired products were formed in good yields. This catalytic system showed high functional group tolerance. PMID:24628537

  3. Self-assembly of Sn-3Ag-0.5Cu Solder in Thermoplastic Resin Containing Carboxyl Group and its Interconnection

    NASA Astrophysics Data System (ADS)

    Miyauchi, Kazuhiro; Yamashita, Yukihiko; Suzuki, Naoya; Takano, Nozomu

    2014-09-01

    The self-assembly of solder powder on pads is attractive as a novel interconnection method between chips and substrates. However, the solder used in this method is limited to Sn-58Bi and Sn-52In. In contrast, Sn-3Ag-0.5Cu has been relatively less studied despite its wide use as a lead-free solder in assembling semiconductor packages. Hence, here, polymeric materials incorporating Sn-3Ag-0.5Cu solder powder were investigated for the self-assembly of the solder on pads at temperatures up to 260°C in a lead-free reflow process. The self-assembly of the solder was observed with an optical microscope through transparent glass chips placed on substrates covered with the polymeric materials incorporating the solder powder. Differential scanning calorimetry measurements were performed to confirm the behaviors of the reaction of the resins and the melting of the solder. When epoxy resin with a fluxing additive was used as a matrix, self-assembly of the solder was prevented by the cross-linking reaction. Conversely, when thermoplastic resin containing carboxyl groups was used as a matrix, the self-assembly of solder was successfully achieved in the absence of fluxing additives. The shear strength of interconnection using reflowfilm with lamination was sufficient and significantly increased during the reflow process. However, the shear strength of the reflowfilm showed cohesive failure, possibly because of the brittle intermetallic compounds (Ag3Sn, Au4Sn) network in bulk was lower than that of conventional solder paste that showed interfacial failure after the reflow process with a rapid cooling rate.

  4. Homogeneous Ziegler-Natta polymerization of functionalized monomers catalyzed by cationic group IV metallocenes

    SciTech Connect

    Kesti, M.R.; Coates, G.W.; Waymouth, R.M.

    1992-11-18

    Ziegler-Natta catalysts are remarkable in their ability to polymerize {alpha}-olefins to high molecular weight, stereoregular polyolefins. One of the major limitations of conventional Ziegler-Natta catalysts is their intolerance to Lewis bases; catalysts based on titanium halides and alkylaluminum cocatalysts are poisoned by most types of monomers containing ethers, esters, amines, and carboxylic acids. The absence of functionality in hydrocarbon polymers seriously affects their adhesive properties, affinity for dyes, permeability, and compatibility with more polar polymers. Previous attempts to polymerize sterically hindered amines, esters and amides, alkyl halides, and carboxylic acids using catalysts derived from TiCl{sub 3} and AlR{sub 3-n}Cl{sub n} have achieved limited success due to the severe loss of catalytic activity in the presence of these monomers. This work reports that cationic, group four metallocenes are active catalysts for the homo-polymerization of {alpha}-olefins containing silyl-protected alcohols and tertiary amines. Employing different monomers and conditions, a table shows the starting monomer, reaction time and temperature, and spectroscopic analysis of the end products. A major advanatage of these metallocene-based catalysts is that the ligand system can be modified to proved the optimal combination of catalystic activity, stereospecificity, and tolerance to functionality. 32 refs., 1 tab.

  5. 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).

  6. Improvement of the fracture toughness of hydroxyapatite (HAp) by incorporation of carboxyl functionalized single walled carbon nanotubes (CfSWCNTs) and nylon.

    PubMed

    Khanal, S P; Mahfuz, H; Rondinone, A J; Leventouri, Th

    2016-03-01

    The potential of improving the fracture toughness of synthetic hydroxyapatite (HAp) by incorporating carboxyl functionalized single walled carbon nanotubes (CfSWCNTs) and polymerized ?-caprolactam (nylon) was studied. A series of HAp samples with CfSWCNTs concentrations varying from 0 to 1.5wt.%, without, and with nylon addition was prepared. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) were used to characterize the samples. The three point bending test was applied to measure the fracture toughness of the composites. A reproducible value of 3.6±0.3MPa.?m was found for samples containing 1wt.% CfSWCNTs and nylon. This value is in the range of the cortical bone fracture toughness. Increase of the CfSWCNTs content results to decrease of the fracture toughness, and formation of secondary phases. PMID:26706523

  7. Refinements to the structure of graphite oxide: absolute quantification of functional groups via selective labelling.

    PubMed

    Eng, Alex Yong Sheng; Chua, Chun Kiang; Pumera, Martin

    2015-12-21

    Chemical modification and functionalization of inherent functional groups within graphite oxide (GO) are essential aspects of graphene-based nano-materials used in wide-ranging applications. Despite extensive research, there remains some discrepancy in its structure, with current knowledge limited primarily to spectroscopic data from XPS, NMR and vibrational spectroscopies. We report herein an innovative electrochemistry-based approach. Four electroactive labels are chosen to selectively functionalize groups in GO, and quantification of each group is achieved by voltammetric analysis. This allows for the first time quantification of absolute amounts of each group, with a further advantage of distinguishing various carbonyl species: namely ortho- and para-quinones from aliphatic ketones. Intrinsic variations in the compositions of permanganate versus chlorate-oxidized GOs were thus observed. Principal differences include permanganate-GO exhibiting substantial quinonyl content, in comparison to chlorate-GO with the vast majority of its carbonyls as isolated ketones. The results confirm that carboxylic groups are rare in actuality, and are in fact entirely absent from chlorate-GO. These observations refine and advance our understanding of GO structure by addressing certain disparities in past models resulting from employment of different oxidation routes, with the vital implication that GO production methods cannot be used interchangeably in the manufacture of graphene-based devices. PMID:26579848

  8. Functional group analysis in coal and on coal surfaces by NMR spectroscopy

    SciTech Connect

    Verkade, J.G.

    1990-01-01

    An accurate knowledge of the oxygen-bearing labile hydrogen functional groups (e.g., carboxylic acids, phenols and alcohols) in coal is required for today's increasingly sophisticated coal cleaning and beneficiation processes. Phospholanes (compounds having the general structure -POCH{sub 2}CH{sub 2}O (1)) are being investigated as reagents for the tagging of liable hydrogen functional groups in coal materials with the NMR-active {sup 31}P nucleus. Of twelve such reagents investigated so far, 2 (2-chloro-1,3-dioxaphospholane, ClPOCH{sub 2}CH{sub 2}O) and 8 (2-chloro-1,3-dithiaphospholane, ClPSCH{sub 2}CH{sub 2}S) have been found to be useful in identifying and quantitating, by {sup 31}P NMR spectroscopy, labile hydrogen functional groups in an Illinois No. 6 coal condensate. Reagent 2 has also been used to quantitate moisture in pyridine extracts of Argonne Premium Coal Samples. Preliminary {sup 119}Sn NMR spectroscopic results on model compounds with the new reagent CF{sub 3}C(O)NHSnMe{sub 3} (N-trimethylstannyltrifluoroacetamide, 14) suggest that labile hydrogen functional groups in coal materials may be more precisely identified with 14 than with phospholanes. 14 refs., 2 figs., 2 tabs.

  9. Carboxyl-functionalized polyurethane nanoparticles with immunosuppressive properties as a new type of anti-inflammatory platform.

    PubMed

    Huang, Yen-Jang; Hung, Kun-Che; Hsieh, Fu-Yu; Hsu, Shan-Hui

    2015-12-28

    The interaction of nanoparticles (NPs) with the body immune system is critically important for their biomedical applications. Most NPs stimulate the immune response of macrophages. Here we show that synthetic polyurethane nanoparticles (PU NPs, diameter 34-64 nm) with rich surface COO(-) functional groups (zeta potential -70 to -50 mV) can suppress the immune response of macrophages. The specially-designed PU NPs reduce the gene expression levels of proinflammatory cytokines (IL-1?, IL-6, and TNF-?) for endotoxin-treated macrophages. The PU NPs increase the intracellular calcium of macrophages (4.5-6.5 fold) and activate autophagy. This is in contrast to the autophagy dysfunction generally observed upon NP exposure. These PU NPs may further decrease the nuclear factor-?B-related inflammation via autophagy pathways. The immunosuppressive activities of PU NPs can prevent animal death by inhibiting the macrophage recruitment and proinflammatory responses, confirmed by an in vivo zebrafish model. Therefore, the novel biodegradable PU NPs demonstrate COO(-) dependent immunosuppressive properties without carrying any anti-inflammatory agents. This study suggests that NP surface chemistry may regulate the immune response, which provides a new paradigm for potential applications of NPs in anti-inflammation and immunomodulation. PMID:26602242

  10. Assignment of functional domains involved in ADP-ribosylation and B-oligomer binding within the carboxyl terminus of the S1 subunit of pertussis toxin.

    PubMed Central

    Krueger, K M; Barbieri, J T

    1994-01-01

    The roles of the carboxyl terminus of the S1 subunit (composed of 235 amino acids) of pertussis toxin in the ADP-ribosylation of transducin (Gt) and in B-oligomer binding were defined by analysis of two carboxyl-terminal deletion mutants of the recombinant S1 (rS1) subunit: C204, which is composed of amino acids 1 through 204 of S1, and C219, which is composed of amino acids 1 through 219 of S1. C204 was expressed in Escherichia coli as a stable, soluble peptide that had an apparent molecular mass of 23.4 kDa. In a linear velocity assay, the specific activity of C180 was 2% and that of C204 was 80% of the activity displayed by rS1 in catalyzing the ADP-ribosylation of Gt. In addition, C204 possessed catalytic efficiencies (kcat/Km) that were 110% at variable Gt concentrations and 40% at variable NAD concentrations of those reported for rS1. These data showed that the catalytic activity of C204 approached the activity of S1. C204 and C219 were unable to associate with the B oligomer under conditions which promoted association of rS1 with the B oligomer. Consistent with these results, mixtures of C204 or C219 with the B oligomer did not elicit a clustering phenotype in CHO cells, whereas rS1 which had associated with the B oligomer was as cytotoxic as native pertussis toxin. These data indicate that residues between 219 and 235 are important in the association of the S1 subunit with the B oligomer. These data allow the assignment of functional regions to the carboxyl terminus of S1. Residues 195 to 204 are required for optimal ADP-ribosyltransferase activity, residues 205 to 219 link the catalytic region of S1 and a B-oligomer-binding region of S1, and residues 220 to 235 are required for association of S1 with the B oligomer. Images PMID:8168972

  11. Luminescent properties of europium carboxylates

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.; Zadorozhnaya, A. N.; Nikolenko, Yu. M.

    2015-11-01

    Mixed-ligand europium carboxylates with nitrogen- and phosphorus-containing neutral ligands having polymer or island structure were studied by the luminescent and X-ray photoelectron spectroscopy methods. In similar groups of the compounds, the value of Stark splitting of the 7F1 - level decreased with decrease of the electron density transfer from europium ion to ligand (covalence of metal-ligand bond increases) and the relative intensity of electro-dipole 5D0 - 7F4 transition rised.

  12. Poly(ethylene glycol)- and carboxylate-functionalized gold nanoparticles using polymer linkages: single-step synthesis, high stability, and plasmonic detection of proteins.

    PubMed

    Park, Garam; Seo, Daeha; Chung, Im Sik; Song, Hyunjoon

    2013-11-01

    Gold nanoparticles with suitable surface functionalities have been widely used as a versatile nanobioplatform. However, functionalized gold nanoparticles using thiol-terminated ligands have a tendency to aggregate, particularly in many enzymatic reaction buffers containing biological thiols, because of ligand exchange reactions. In the present study, we developed a one-step synthesis of poly(ethylene glycol) (PEG)ylated gold nanoparticles using poly(dimethylaminoethyl methacrylate) (PDMAEMA) in PEG as a polyol solvent. Because of the chelate effect of polymeric functionalities on the gold surface, the resulting PEGylated gold nanoparticles (Au@P-PEG) are very stable under the extreme conditions at which the thiol-monolayer-protected gold nanoparticles are easily coagulated. Using the solvent mixture of PEG and ethylene glycol (EG) and subsequent hydrolysis, gold nanoparticles bearing mixed functionalities of PEG and carboxylate are generated. The resulting particles exhibit selective adsorption of positively charged chymotrypsin (ChT) without nonselective adsorption of bovine serum albumin (BSA). The present nanoparticle system has many advantages, including high stability, simple one-step synthesis, biocompatibility, and excellent binding specificity; thus, this system can be used as a versatile platform for potential bio-related applications, such as separation, sensing, imaging, and assays. PMID:24090031

  13. 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

  14. 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

  15. 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

  16. Synergistic effect between defect sites and functional groups on the hydrolysis of cellulose over activated carbon.

    PubMed

    Foo, Guo Shiou; Sievers, Carsten

    2015-02-01

    The chemical oxidation of activated carbon by H2 O2 and H2 SO4 is investigated, structural and chemical modifications are characterized, and the materials are used as catalysts for the hydrolysis of cellulose. Treatment with H2 O2 enlarges the pore size and imparts functional groups such as phenols, lactones, and carboxylic acids. H2 SO4 treatment targets the edges of carbon sheets primarily, and this effect is more pronounced with a higher temperature. Adsorption isotherms demonstrate that the adsorption of oligomers on functionalized carbon is dominated by van der Waals forces. The materials treated chemically are active for the hydrolysis of cellulose despite the relative weakness of most of their acid sites. It is proposed that a synergistic effect between defect sites and functional groups enhances the activity by inducing a conformational change in the glucan chains if they are adsorbed at defect sites. This activates the glycosidic bonds for hydrolysis by in-plane functional groups. PMID:25504913

  17. The carboxyl group of Glu113 is required for stabilization of the diferrous and bis-FeIV states of MauG

    PubMed Central

    Tarboush, Nafez Abu; Yukl, Erik T.; Shin, Sooim; Feng, Manliang; Wilmot, Carrie M.; Davidson, Victor L.

    2013-01-01

    The diheme enzyme MauG catalyzes a six-electron oxidation required for posttranslational modification of a precursor of methylamine dehydrogenase (preMADH) to complete the biosynthesis of its protein-derived tryptophan tryptophylquinone (TTQ) cofactor. Crystallographic studies have implicated Glu113 in the formation of the bis-FeIV state of MauG, in which one heme is FeIV=O and the other is FeIV with His-Tyr axial ligation. An E113Q mutation had no effect on the structure of MauG, but significantly altered its redox properties. E113Q MauG could not be converted to the diferrous state by reduction with dithionite, but was only reduced to a mixed valence FeII/FeIII state, which is never observed in wild-type (WT) MauG. Addition of H2O2 to E113Q MauG generated a high valence state that formed more slowly and was less stable than the bis-FeIV state of WT MauG. E113Q MauG exhibited no detectable TTQ biosynthesis activity in a steady-state assay with preMADH as the substrate. It did catalyze the steady-state oxidation of quinol MADH to the quinone, but 1000-fold less efficiently than WT MauG. Addition of H2O2 to a crystal of the E113Q MauG-preMADH complex resulted in partial synthesis of TTQ. Extended exposure of these crystals to H2O2 resulted in hydroxylation of Pro107 in the distal pocket of the high-spin heme. It is concluded that the loss of the carboxylic group of Glu113 disrupts the redox cooperativity between hemes that allows rapid formation of the diferrous state, and alters the distribution of high-valence species that participate in charge-resonance stabilization of the bis-FeIV redox state. PMID:23952537

  18. Synthesis of Terminal Allenes via a Copper-Catalyzed Decarboxylative Coupling Reaction of Alkynyl Carboxylic Acids.

    PubMed

    Lim, Jeongah; Choi, Jinseop; Kim, Han-Sung; Kim, In Seon; Nam, Kye Chun; Kim, Jimin; Lee, Sunwoo

    2016-01-01

    Synthesis of terminal allenes via a copper-catalyzed decarboxylative coupling reaction was developed. Aryl alkynyl carboxylic acid, paraformaldehyde, and dicyclohexylamine were reacted with CuI (20 mol %) in diglyme at 100 °C for 2 h to produce the terminal allene in moderate to good yields. The method showed good functional group tolerance. PMID:26618610

  19. Doping Level of Boron-Doped Diamond Electrodes Controls the Grafting Density of Functional Groups for DNA Assays.

    PubMed

    Švorc, ?ubomír; Jambrec, Daliborka; Vojs, Marian; Barwe, Stefan; Clausmeyer, Jan; Michniak, Pavol; Marton, Marián; Schuhmann, Wolfgang

    2015-09-01

    The impact of different doping levels of boron-doped diamond on the surface functionalization was investigated by means of electrochemical reduction of aryldiazonium salts. The grafting efficiency of 4-nitrophenyl groups increased with the boron levels (B/C ratio from 0 to 20,000 ppm). Controlled grafting of nitrophenyldiazonium was used to adjust the amount of immobilized single-stranded DNA strands at the surface and further on the hybridization yield in dependence on the boron doping level. The grafted nitro functions were electrochemically reduced to the amine moieties. Subsequent functionalization with a succinic acid introduced carboxyl groups for subsequent binding of an amino-terminated DNA probe. DNA hybridization significantly depends on the probe density which is in turn dependent on the boron doping level. The proposed approach opens new insights for the design and control of doped diamond surface functionalization for the construction of DNA hybridization assays. PMID:26285076

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

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

    DOE PAGESBeta

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

    2015-09-01

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

  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. PMID:25209851

  6. Various fates of neuronal progenitor cells observed on several different chemical functional groups

    NASA Astrophysics Data System (ADS)

    Liu, Xi; Wang, Ying; He, Jin; Wang, Xiu-Mei; Cui, Fu-Zhai; Xu, Quan-Yuan

    2011-12-01

    Neuronal progenitor cells cultured on gold-coated glass surfaces modified by different chemical functional groups, including hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), bromo (-Br), mercapto (-SH), - Phenyl and methyl (-CH3), were studied here to investigate the influence of surface chemistry on the cells' adhesion, morphology, proliferation and functional gene expression. Focal adhesion staining indicated in the initial culture stage cells exhibited morphological changes in response to different chemical functional groups. Cells cultured on -NH2 grafted surface displayed focal adhesion plaque and flattened morphology and had the largest contact area. However, their counter parts on -CH3 grafted surface displayed no focal adhesion and rounded morphology and had the smallest contact area. After 6 days culture, the proliferation trend was as follows: -NH2 > -SH> -COOH> - Phenyl > - Br > -OH> -CH3. To determine the neural functional properties of the cells affected by surface chemistry, the expression of glutamate decarboxylase (GAD67), nerve growth factor (NGF) and brainderived neurotrophic factor (BDNF) were characterized. An increase of GAD67 expression was observed on -NH2, -COOH and -SH grafted surfaces, while no increase in NGF and BDNF expression was observed on any chemical surfaces. These results highlight the importance of surface chemistry in the fate determination of neuronal progenitor cells, and suggest that surface chemistry must be considered in the design of biomaterials for neural tissue engineering.

  7. Boron-containing amino carboxylic acid compounds and uses thereof

    DOEpatents

    Kabalka, George W. (Knoxville, TN); Srivastava, Rajiv R. (Knoxville, TN)

    2000-03-14

    Novel compounds which are useful for boron neutron capture therapy (BNCT) are disclosed. The compounds comprise a stable boron-containing group and an aminocycloalkane carboxylic acid group or a boronated acyclic hydrocarbon-linked amino carboxylic acid. Methods for synthesis of the compounds and for use of the compounds in BNCT are disclosed.

  8. Appendix 31 Disturbance Processes and Functions of Habitat Groups

    E-print Network

    Appendix 31 Disturbance Processes and Functions of Habitat Groups The following descriptions of the ecological processes and functions of subbasin habitat groups are adapted from Gautreau (1999). Habitat Group is an important mechanism for energy flow, maintenance of habitat diversity, vegetative succession, canopy

  9. Generation of Turkish Verbal Groups with Systemic-Functional Grammar

    E-print Network

    Cicekli, Ilyas

    Generation of Turkish Verbal Groups with Systemic-Functional Grammar Turgay Korkmaz, and Ilyas presents the verbal group part of a Turkish sentence gen- erator that is currently under development{functional representation and realization of Turkish verbal groups. Keywords: Natural Language Generation, Computational

  10. 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

  11. 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

  12. Identification and Characterization of Carboxyl Esterases of Gill Chamber-Associated Microbiota in the Deep-Sea Shrimp Rimicaris exoculata by Using Functional Metagenomics

    PubMed Central

    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.

    2015-01-01

    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

  13. 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

  14. Biomineralization on polymer-coated multi-walled carbon nanotubes with different surface functional groups.

    PubMed

    Li, Xiaoli; Lan, Jinle; Ai, Miao; Guo, Yougang; Cai, Qing; Yang, Xiaoping

    2014-11-01

    Substrate-controlled mineralization from simulated body fluid (SBF) has been studied as a model for biomineralization and for the synthesis of bioinspired hybrid materials. The mineralization procedure is complex and the features of final minerals are affected by many factors. Surface functional groups are among them and play important roles in inducing nucleation, crystal growth and transformation. In this study, multi-walled carbon nanotubes (MWCNTs) were surface-modified with poly(acrylic acid), polyacrylamide or poly(hydroxyethyl methylacrylate), and used as templates for biomineralization. The polymer coating was gained via photo-initiated polymerization of monomers and adsorption of polymer chains onto MWCNTs in solution. Then, the modified MWCNTs with different surface functional groups were incubated in 1.5 times SBF for different times to compare the effect of carboxyl, acylamino and hydroxyl group on calcium phosphate formation. The study involved various characterizations such as morphology observation, weight increase, chemical and crystal structures of deposited minerals at different soaking time points. In all cases, carbonated calcium-deficient hydroxyapatite (CDHA) was identified after 7 days immersion. The continuously growing mineral crystals would wrap MWCNTs into spherical composite particles ultimately. However, the rates of nucleation and crystal growth depended on the type of surface functional groups, in an order of COOH>CONH2>OH. And their different charge characteristics led to different Ca/P ratios in initially formed minerals. It revealed that acylamino group, which demonstrated the lowest Ca/P ratio in nucleation stage, was helpful to obtain c-axis preferentially oriented morphology resembling the HA structure in natural bone tissue. PMID:25454665

  15. Shintani Zeta Functions and Weyl Group Multiple Dirichlet Series

    E-print Network

    Sutherland, Scott

    Shintani Zeta Functions and Weyl Group Multiple Dirichlet Series A Dissertation presented by Jun series with functional equations. In this dissertation, we investigate the Shintani zeta function as meanings and completely determine the integral orbits. We prove that the associated Shintani zeta function

  16. 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.

  17. R''O NR2''' Oxidation States of Organic Functional Groups

    E-print Network

    (enamine) ester orthoester nitrile ketene trihalomethyl hydroxamic acid alkyl haloformatecarbamate xanthate, p. 615!664. Carruthers, W. In Some Modern Methods of Organic Synthesis 3rd Ed., Cambridge University by the progression of a methyl group to a carboxylic acid in a series of 2-electron oxidations, as shown at right

  18. REPRESENTATION ZETA FUNCTIONS OF WREATH PRODUCTS WITH FINITE GROUPS

    E-print Network

    Genève, Université de

    OF WREATH PRODUCTS The representation zeta function of a rigid group G is the Dirichlet series (1.1) GREPRESENTATION ZETA FUNCTIONS OF WREATH PRODUCTS WITH FINITE GROUPS Laurent Bartholdi and Pierre de linear repre- sentations in GLn(C) for all n 1. Let (G, s) = P n=1 hn(G)n-s be its representation zeta

  19. Functional Grouping of Genes Using Spectral Clustering and Gene Ontology

    E-print Network

    Zell, Andreas

    Functional Grouping of Genes Using Spectral Clustering and Gene Ontology Nora Speer, Holger amounts of biological data. During the analysis of such data the need for a functional grouping of genes arises. In this paper, we propose a new method based on spectral clustering for the partitioning of genes

  20. Spectral Clustering Gene Ontology Terms to Group Genes by Function

    E-print Network

    Zell, Andreas

    Spectral Clustering Gene Ontology Terms to Group Genes by Function Nora Speer, Christian Spieth throughput me- thods like DNA microarrays, biologists are capable of producing huge amounts of data. During the analysis of such data the need for a group- ing of the genes according to their biological function arises

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

    E-print Network

    Williamson, Shelly Ann

    2000-01-01

    carboxylate salts are concentrated and reacted with a low-molecular-weight tertiary amine and carbon dioxide to precipitate calcium carbonate. In a distillation column, the low-molecular-weight amine carboxylate reacts with a high-molecular-weight tertiary...

  2. 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…

  3. Functional characterization and expression analysis of rice ?1-pyrroline-5-carboxylate dehydrogenase provide new insight into the regulation of proline and arginine catabolism

    PubMed Central

    Forlani, Giuseppe; Bertazzini, Michele; Zarattini, Marco; Funck, Dietmar

    2015-01-01

    While intracellular proline accumulation in response to various stress conditions has been investigated in great detail, the biochemistry and physiological relevance of proline degradation in plants is much less understood. Moreover, the second and last step in proline catabolism, the oxidation of ?1-pyrroline-5-carboxylic acid (P5C) to glutamate, is shared with arginine catabolism. Little information is available to date concerning the regulatory mechanisms coordinating these two pathways. Expression of the gene coding for P5C dehydrogenase was analyzed in rice by real-time PCR either following the exogenous supply of amino acids of the glutamate family, or under hyperosmotic stress conditions. The rice enzyme was heterologously expressed in E. coli, and the affinity-purified protein was thoroughly characterized with respect to structural and functional properties. A tetrameric oligomerization state was observed in size exclusion chromatography, which suggests a structure of the plant enzyme different from that shown for the bacterial P5C dehydrogenases structurally characterized to date. Kinetic analysis accounted for a preferential use of NAD+ as the electron acceptor. Cations were found to modulate enzyme activity, whereas anion effects were negligible. Several metal ions were inhibitory in the micromolar range. Interestingly, arginine also inhibited the enzyme at higher concentrations, with a mechanism of uncompetitive type with respect to P5C. This implies that millimolar levels of arginine would increase the affinity of P5C dehydrogenase toward its specific substrate. Results are discussed in view of the involvement of the enzyme in either proline or arginine catabolism. PMID:26300893

  4. Functional characterization and expression analysis of rice ?(1)-pyrroline-5-carboxylate dehydrogenase provide new insight into the regulation of proline and arginine catabolism.

    PubMed

    Forlani, Giuseppe; Bertazzini, Michele; Zarattini, Marco; Funck, Dietmar

    2015-01-01

    While intracellular proline accumulation in response to various stress conditions has been investigated in great detail, the biochemistry and physiological relevance of proline degradation in plants is much less understood. Moreover, the second and last step in proline catabolism, the oxidation of ?(1)-pyrroline-5-carboxylic acid (P5C) to glutamate, is shared with arginine catabolism. Little information is available to date concerning the regulatory mechanisms coordinating these two pathways. Expression of the gene coding for P5C dehydrogenase was analyzed in rice by real-time PCR either following the exogenous supply of amino acids of the glutamate family, or under hyperosmotic stress conditions. The rice enzyme was heterologously expressed in E. coli, and the affinity-purified protein was thoroughly characterized with respect to structural and functional properties. A tetrameric oligomerization state was observed in size exclusion chromatography, which suggests a structure of the plant enzyme different from that shown for the bacterial P5C dehydrogenases structurally characterized to date. Kinetic analysis accounted for a preferential use of NAD(+) as the electron acceptor. Cations were found to modulate enzyme activity, whereas anion effects were negligible. Several metal ions were inhibitory in the micromolar range. Interestingly, arginine also inhibited the enzyme at higher concentrations, with a mechanism of uncompetitive type with respect to P5C. This implies that millimolar levels of arginine would increase the affinity of P5C dehydrogenase toward its specific substrate. Results are discussed in view of the involvement of the enzyme in either proline or arginine catabolism. PMID:26300893

  5. Density functional theory calculation of cyclic carboxylic phosphorus mixed anhydrides as possible intermediates in biochemical reactions: implications for the Pro-Tide approach.

    PubMed

    Ricci, Antonio; Brancale, Andrea

    2012-04-15

    Cyclic acyl phosphoramidates (CAPAs) are important components in several fundamental biological reactions such as protein synthesis and phosphorylation. These structures are particularly interesting in the nucleotide pro-drug approach, Pro-Tide, since they are putative intermediates in one of the hydrolysis steps required for activation. The central role played by the amino acid carboxylate function suggests first the formation of a cyclic mixed phosphorus anhydride, rapidly followed by water attack. To investigate such speculations, we performed quantum mechanical calculations using the B3LYP/6-311+G** level of theory for the plausible mechanisms of action considered. In the five-membered ring case, transition state theory demonstrated how the overall, gas-phase, mechanism of action could be split into two in-line addition-elimination (A-E) steps separated by a penta-coordinate phosphorane intermediate. The difference between five-membered and six-membered ring first A-E was also explored, revealing a single step, unimolecular reaction for the six-membered ring A-E profile. Implicit solvent contribution further confirmed the importance of CAPAs as reactive intermediates in such kind of reactions. Lastly, the second A-E pathway was analyzed to understand the complete pathway of the reaction. This analysis is the first attempt to clarify the putative mechanism of action involved in the activation of Pro-Tides and casts light also on the possible mechanism of action involved in primordial protein syntheses, strengthening the hypothesis of a common cyclic mixed phosphorus anhydride species as a common intermediate. PMID:22318882

  6. Structure and luminescent property of complexes of aryl carboxylic acid-functionalized polystyrene with Eu(III) and Tb(III) ions.

    PubMed

    Gao, Baojiao; Shi, Nan; Qiao, Zongwen

    2015-11-01

    Via polymer reactions, naphthoic acid (NA) and benzoic acid (BA) were bonded onto the side chains of polystyrene (PS), respectively, and two aryl carboxylic acid-functionalized polystyrenes, PSNA and PSBA, were obtained. Using PSNA and PSBA as macromolecule ligands and Eu(3+) and Tb(3+) ions as central ions, various luminescent binary polymer-rare earth complexes were prepared. At the same time, with 1,10-phenanthroline (Phen) and 4,4'-bipyridine (Bipy) as small-molecule co-ligands, various ternary polymer-rare earth complexes were also prepared. On the basis of characterizing PSNA, PSBA and complexes, the relationship between structure and luminescent property for these prepared complexes were mainly investigated. The study results show that the macromolecule ligands PSNA and PSBA, or the bonded NA and BA ligands, can strongly sensitize the fluorescence emissions of Eu(3+) ion or Tb(3+) ion, but the sensitization effect is strongly dependent on the structure of the ligands and the property of the central ions, namely it is strongly dependent on the matching degree of energy levels. The fluorescence emission of the binary complex PS-(NA)3-Eu(III) is stronger than that PS-(BA)3-Eu(III), indicating ligand NA has stronger sensitization action for Eu(3+) ion than ligand BA; the binary complex PS-(BA)3-Tb(III) emit strong characteristic fluorescence of Tb(3+) ion, displaying that ligand BA can strongly sensitize Tb(3+) ion, whereas the binary complex PS-(NA)3-Tb(III) nearly does not emit the characteristic fluorescence of Tb(3+) ion, showing that ligand NA does not sensitize Tb(3+) ion. The fluorescence intensity of the ternary complexes is much stronger than that of the binary complexes in the same series. PMID:26086996

  7. Butane-1,4-diammonium bis­(pyridine-2-carboxyl­ate) monohydrate

    PubMed Central

    Kim, Nam-Ho; Ha, Kwang

    2009-01-01

    The asymmetric unit of the title compound, C4H14N2 2+·2C6H4NO2 ?·H2O, consists of half of a doubly protonated tetra­methyl­enediammonium dication, a pyridine-2-carboxyl­ate anion and half of a solvent water mol­ecule; the dication is located on a centre of inversion and a twofold rotation axis passes through the O atom of the water mol­ecule. The carboxyl­ate group of the anion appears to be delocalized on the basis of the C—O bond lengths. In the crystal structure, the components are linked by inter­molecular N—H?O, N—H?N and O—H?O hydrogen bonds. PMID:21577560

  8. Propane-1,3-diaminium bis­(pyridine-4-carboxyl­ate) monohydrate

    PubMed Central

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

    2011-01-01

    The asymmetric unit of the title compound, C3H12N2 2+·2C6H4NO2 ?·H2O, consists of half of a doubly protonated propane-1,3-diammonium dication, a pyridine-4-carboxyl­ate anion and half of a solvent water mol­ecule; the dication and the solvent water are located on a twofold rotation axis which passes through the central C atom of the dication and the water O atom. The carboxyl­ate group of the anion appears to be delocalized on the basis of the C—O bond lengths. In the crystal, the components are linked by inter­molecular N—H?O, N—H?N and O—H?O hydrogen bonds. PMID:22065654

  9. A new synthesis of indole 5-carboxylic acids and 6-hydroxy-indole-5-carboxylic acids in the preparation of an o-hydroxylated metabolite of vilazodone.

    PubMed

    Heinrich, Timo; Böttcher, Henning

    2004-05-17

    A major metabolite of the potential antidepressant vilazodone formed in rat, dog, monkey and human liver microsomes is the 5-cyano-6-hydroxy-1H-indole derivative. For the construction of the salicyl-like substituted indole we adapted a synthesis of carmoxirole using Japp-Klingemann type Fischer-indole synthesis protocols. Functional group interconversion of carboxylic acid via carboxamide into cyanide was performed with methanesulfonic acid chloride. PMID:15109678

  10. Matrix Airy functions for compact Lie groups V. S. Varadarajan

    E-print Network

    Varadarajan, Veeravalli S.

    student Rahul Fernandez. #12;The original Airy function First discovery due to Sir George Biddell AiryMatrix Airy functions for compact Lie groups V. S. Varadarajan University of California, Los Angeles, CA, USA Los Angeles, November 12, 2008 #12;Abstract The classical Airy function and its many

  11. Local renormalization group functions from quantum renormalization group and holographic bulk locality

    NASA Astrophysics Data System (ADS)

    Nakayama, Yu

    2015-06-01

    The bulk locality in the constructive holographic renormalization group requires miraculous cancellations among various local renormalization group functions. The cancellation is not only from the properties of the spectrum but from more detailed aspects of operator product expansions in relation to conformal anomaly. It is remarkable that one-loop computation of the universal local renormalization group functions in the weakly coupled limit of the super Yang-Mills theory fulfils the necessary condition for the cancellation in the strongly coupled limit in its SL(2, Z) duality invariant form. From the consistency between the quantum renormalization group and the holographic renormalization group, we determine some unexplored local renormalization group functions (e.g. diffusive term in the beta function for the gauge coupling constant) in the strongly coupled limit of the planar super Yang-Mills theory.

  12. Differential Item Functioning Detection across Two Methods of Defining Group Comparisons: Pairwise and Composite Group Comparisons

    ERIC Educational Resources Information Center

    Sari, Halil Ibrahim; Huggins, Anne Corinne

    2015-01-01

    This study compares two methods of defining groups for the detection of differential item functioning (DIF): (a) pairwise comparisons and (b) composite group comparisons. We aim to emphasize and empirically support the notion that the choice of pairwise versus composite group definitions in DIF is a reflection of how one defines fairness in DIF…

  13. Carboxylic acid sorption regeneration process

    DOEpatents

    King, C. Judson (Kensington, CA); Poole, Loree J. (Baton Rouge, LA)

    1995-01-01

    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.

  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. Guest-Host Chemistry with Dendrimers—Binding of Carboxylates in Aqueous Solution

    PubMed Central

    Ficker, Mario; Petersen, Johannes F.; Hansen, Jon S.; Christensen, Jørn B.

    2015-01-01

    Recognition and binding of anions in water is difficult due to the ability of water molecules to form strong hydrogen bonds and to solvate the anions. The complexation of two different carboxylates with 1-(4-carbomethoxypyrrolidone)-terminated PAMAM dendrimers was studied in aqueous solution using NMR and ITC binding models. Sodium 2-naphthoate and sodium 3-hydroxy-2-naphthoate were chosen as carboxylate model compounds, since they carry structural similarities to many non-steroidal anti-inflammatory drugs and they possess only a limited number of functional groups, making them ideal to study the carboxylate-dendrimer interaction selectively. The binding stoichiometry for 3-hydroxy-2-naphthoate was found to be two strongly bound guest molecules per dendrimer and an additional 40 molecules with weak binding affinity. The NOESY NMR showed a clear binding correlation of sodium 3-hydroxy-2-naphthoate with the lyophilic dendrimer core, possibly with the two high affinity guest molecules. In comparison, sodium 2-naphthoate showed a weaker binding strength and had a stoichiometry of two guests per dendrimer with no additional weakly bound guests. This stronger dendrimer interaction with sodium 3-hydroxy-2-naphthoate is possibly a result of the additional interactions of the dendrimer with the extra hydroxyl group and an internal stabilization of the negative charge due to the hydroxyl group. These findings illustrate the potential of the G4 1-(4-carbomethoxy) pyrrolidone dendrimer to complex carboxylate guests in water and act as a possible carrier of such molecules. PMID:26448138

  16. Roles of functional groups of naproxen in its sorption to kaolinite.

    PubMed

    Yu, Chenglong; Bi, Erping

    2015-11-01

    The sorption of acidic anti-inflammatory drugs to soils is important for evaluating their fate and transformations in the water-soil environment. However, roles of functional groups of ionisable drugs onto mineral surfaces have not been sufficiently studied. In this study, batch experiments of naproxen (NPX, anti-inflammatory drug) and two kinds of competitors to kaolinite were studied. The Kd of naproxen to kaolinite is 1.30-1.62 L kg(-1). The n-? electron donor-acceptor (n-? EDA) interaction between diaromatic ring of naproxen (?-electron acceptors) and the siloxane oxygens (n-donors) of kaolinite is the dominant sorption mechanism. The carboxyl group of naproxen can contribute to the overall sorption. A conception model was put forward to elucidate to sorption mechanisms, in which the contribution of n-? EDA and hydrogen bond to overall sorption was quantified. These sorption mechanisms can be helpful for estimating the fate and mobility of acid pharmaceuticals in soil-water environment. PMID:26126188

  17. Relationship between thermal extraction yield and oxygen-containing functional groups

    SciTech Connect

    Nao Kashimura; Toshimasa Takanohashi; Kensuke Masaki; Takahiro Shishido; Sinya Sato; Akimitsu Matsumura; Ikuo Saito

    2006-10-15

    Generating power from HyperCoal is a high-efficiency process in which the organic portion of coal is extracted with industrial solvents at a temperature around 360{sup o}C and fed to a gas turbine directly. This study sought to establish a selection index for identifying subbituminous coals that give high extraction yields. Subbituminous coals were extracted at 360{sup o}C with flowing industrial solvents, and we investigated the relationship between the extraction yield and the quantity of oxygen-containing functional groups in the coal. The extraction yield with a polar solvent, crude methylnaphthalene oil (CMNO), increased with the quantity of carboxylate groups bridged by metal cations, such as Ca{sup 2+} and Mg{sup 2+} (COOM). The correlation coefficient between the extraction yield and the quantity was 0.82. Acid treatment of coal before extraction released COOM cross-links, increasing the extraction yield. These results suggest that the thermal extraction of low-rank coals strongly depends on the cross-links rather than the hydrogen bonds. Therefore, the thermal extraction yields of low-rank coals can be estimated from the quantity of COOM in the original coals. The intercept of the regression line between the quantity of COOM and the extraction yield with CMNO was 57.8%. This value is the average extraction yield for low-rank coals with free COOM. 23 refs., 6 figs., 2 tabs.

  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. Electron mobility enhancement in ZnO thin films via surface modification by carboxylic acids

    E-print Network

    Evans, Paul G.

    Electron mobility enhancement in ZnO thin films via surface modification by carboxylic acids Josef://apl.aip.org/authors #12;Electron mobility enhancement in ZnO thin films via surface modification by carboxylic acids Josef a monolayer of organic molecules with carboxylic acid attachment groups increases the field-effect electron

  20. 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

  1. Separation of aromatic carboxylic acids using quaternary ammonium salts on reversed-phase HPLC. 1. Separation behavior of aromatic carboxylic acids

    SciTech Connect

    Kawamura, K.; Okuwaki, A.; Verheyen, T.; Perry, G.J.

    2006-02-15

    In order to develop separation processes and analytical methods for aromatic carboxylic acids for the coal oxidation products, the separation behavior of aromatic carboxylic acids on a reversed-phase HPLC using eluent containing quaternary ammonium salt has been investigated. The retention mechanism of aromatic carboxylic acids was discussed on the basis of both ion-pair partition model and ion-exchange model. The retention behavior of aromatic carboxylic acids possessing one (or two) carboxylic acid group(s) followed the ion-pair partition model, where linear free energy relationship was observed between the capacity factor and the extraction equilibrium constants of benzoic acid and naphthalene carboxylic acid. Besides, the retention behavior followed ion-exchange model with increasing the number of carboxylic acids, where the capacity factor of benzene polycarboxylic acids is proportional to the association constants between aromatic acids and quaternary ammonium ions calculated on the basis of an electrostatic interaction model.

  2. Diagonals of rational functions and selected differential Galois groups

    NASA Astrophysics Data System (ADS)

    Bostan, A.; Boukraa, S.; Maillard, J.-M.; Weil, J.-A.

    2015-12-01

    We recall that diagonals of rational functions naturally occur in lattice statistical mechanics and enumerative combinatorics. In all the examples emerging from physics, the minimal linear differential operators annihilating these diagonals of rational functions have been shown to actually possess orthogonal or symplectic differential Galois groups. In order to understand the emergence of such orthogonal or symplectic groups, we analyze exhaustively three sets of diagonals of rational functions, corresponding respectively to rational functions of three variables, four variables and six variables. We impose the constraints that the degree of the denominators in each variable is at most one, and the coefficients of the monomials are 0 or \\+/- 1, so that the analysis can be exhaustive. We find the minimal linear differential operators annihilating the diagonals of these rational functions of three, four, five and six variables. We find that, even for these sets of examples which, at first sight, have no relation with physics, their differential Galois groups are always orthogonal or symplectic groups. We discuss the conditions on the rational functions such that the operators annihilating their diagonals do not correspond to orthogonal or symplectic differential Galois groups, but rather to generic special linear groups.

  3. PERMUTATION GROUPING: INTELLIGENT HASH FUNCTION DESIGN FOR AUDIO & IMAGE RETRIEVAL

    E-print Network

    Cortes, Corinna

    PERMUTATION GROUPING: INTELLIGENT HASH FUNCTION DESIGN FOR AUDIO & IMAGE RETRIEVAL Shumeet Baluja systems. In this study, we introduce the idea of permutation-grouping to intelligently design the hash for retrieval [1]. It was designed to hold 108 -109 keys, distributed to a network of machines. Despite

  4. Photochemical transformation of carboxylated multiwalled carbon nanotubes: role of reactive oxygen species.

    PubMed

    Qu, Xiaolei; Alvarez, Pedro J J; Li, Qilin

    2013-12-17

    The study investigated the photochemical transformation of carboxylated multiwalled carbon nanotubes (COOH-MWCNTs), an important environmental process affecting their physicochemical characteristics and hence fate and transport. UVA irradiation removed carboxyl groups from COOH-MWCNT surface while creating other oxygen-containing functional groups with an overall decrease in total surface oxygen content. This was attributed to reactions with photogenerated reactive oxygen species (ROS). COOH-MWCNTs generated singlet oxygen ((1)O2) and hydroxyl radical ((•)OH) under UVA light, which exhibited different reactivity toward the COOH-MWCNT surface. Inhibition experiments that isolate the effects of (•)OH and (1)O2 as well as experiments using externally generated (•)OH and (1)O2 separately revealed that (•)OH played an important role in the photochemical transformation of COOH-MWCNTs under UVA irradiation. The Raman spectroscopy and surface functional group analysis results suggested that (•)OH initially reacted with the surface carboxylated carbonaceous fragments, resulting in their degradation or exfoliation. Further reaction between (•)OH and the graphitic sidewall led to formation of defects including functional groups and vacancies. These reactions reduced the surface potential and colloidal stability of COOH-MWCNTs, and are expected to reduce their mobility in aquatic systems. PMID:24255932

  5. Recursive Method for Nekrasov partition function for classical Lie groups

    E-print Network

    Satoshi Nakamura; Futoshi Okazawa; Yutaka Matsuo

    2014-11-27

    Nekrasov partition function for the supersymmetric gauge theories with general Lie groups is not so far known in a closed form while there is a definition in terms of the integral. In this paper, as an intermediate step to derive it, we give a recursion formula among partition functions, which can be derived from the integral. We apply the method to a toy model which reflects the basic structure of partition functions for BCD type Lie groups and obtained a closed expression for the factor associated with the generalized Young diagram.

  6. Application of Lie group analysis to functional differential equations

    E-print Network

    Martin Oberlack; Marta Waclawczyk

    2006-10-27

    In the present paper the classical point symmetry analysis is extended from partial differential to functional differential equations with functional derivatives. In order to perform the group analysis and deal with the functional derivatives we extend the quantities such as infinitesimal transformations, prolongations and invariant solutions. For the sake of example the procedure is applied to the continuum limit of the heat equation. The method can further lead to significant applications in statistical physics and fluid dynamics.

  7. 14 CFR 11 - Functional Classification-Operating Expenses of Group II and Group III Air Carriers

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Functional Classification-Operating Expenses of Group II and Group III Air Carriers Section 11 Section Section 11 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR...

  8. Microscopic mechanism of electron transfer through the hydrogen bonds between carboxylated alkanethiol molecules connected to gold electrodes

    NASA Astrophysics Data System (ADS)

    Li, Yang; Tu, Xingchen; Wang, Minglang; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2014-11-01

    The atomic structure and the electron transfer properties of hydrogen bonds formed between two carboxylated alkanethiol molecules connected to gold electrodes are investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. Three types of molecular junctions are constructed, in which one carboxyl alkanethiol molecule contains two methylene, -CH2, groups and the other one is composed of one, two, or three -CH2 groups. Our calculations show that, similarly to the cases of isolated carboxylic acid dimers, in these molecular junctions the two carboxyl, -COOH, groups form two H-bonds resulting in a cyclic structure. When self-interaction corrections are explicitly considered, the calculated transmission coefficients of these three H-bonded molecular junctions at the Fermi level are in good agreement with the experimental values. The analysis of the projected density of states confirms that the covalent Au-S bonds localized at the molecule-electrode interfaces and the electronic coupling between -COOH and S dominate the low-bias junction conductance. Following the increase of the number of the -CH2 groups, the coupling between -COOH and S decreases deeply. As a result, the junction conductance decays rapidly as the length of the H-bonded molecules increases. These findings not only provide an explanation to the observed distance dependence of the electron transfer properties of H-bonds, but also help the design of molecular devices constructed through H-bonds.

  9. Microscopic mechanism of electron transfer through the hydrogen bonds between carboxylated alkanethiol molecules connected to gold electrodes

    SciTech Connect

    Li, Yang; Tu, Xingchen; Wang, Minglang; Wang, Hao; Hou, Shimin; Sanvito, Stefano

    2014-11-07

    The atomic structure and the electron transfer properties of hydrogen bonds formed between two carboxylated alkanethiol molecules connected to gold electrodes are investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. Three types of molecular junctions are constructed, in which one carboxyl alkanethiol molecule contains two methylene, –CH{sub 2}, groups and the other one is composed of one, two, or three –CH{sub 2} groups. Our calculations show that, similarly to the cases of isolated carboxylic acid dimers, in these molecular junctions the two carboxyl, –COOH, groups form two H-bonds resulting in a cyclic structure. When self-interaction corrections are explicitly considered, the calculated transmission coefficients of these three H-bonded molecular junctions at the Fermi level are in good agreement with the experimental values. The analysis of the projected density of states confirms that the covalent Au–S bonds localized at the molecule-electrode interfaces and the electronic coupling between –COOH and S dominate the low-bias junction conductance. Following the increase of the number of the –CH{sub 2} groups, the coupling between –COOH and S decreases deeply. As a result, the junction conductance decays rapidly as the length of the H-bonded molecules increases. These findings not only provide an explanation to the observed distance dependence of the electron transfer properties of H-bonds, but also help the design of molecular devices constructed through H-bonds.

  10. Single or functionalized fullerenes interacting with heme group

    SciTech Connect

    Costa, Wallison Chaves; Diniz, Eduardo Moraes

    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. Lysine carboxylation: unveiling a spontaneous post-translational modification

    PubMed Central

    Jimenez-Morales, David; Adamian, Larisa; Shi, Dashuang; Liang, Jie

    2014-01-01

    The carboxylation of lysine residues is a post-translational modification (PTM) that plays a critical role in the catalytic mechanisms of several important enzymes. It occurs spontaneously under certain physicochemical conditions, but is difficult to detect experimentally. Its full impact is unknown. In this work, the signature microenvironment of lysine-carboxylation sites has been characterized. In addition, a computational method called Predictor of Lysine Carboxyl­ation (PreLysCar) for the detection of lysine carboxylation in proteins with available three-dimensional structures has been developed. The likely prevalence of lysine carboxylation in the proteome was assessed through large-scale computations. The results suggest that about 1.3% of large proteins may contain a carboxylated lysine residue. This unexpected prevalence of lysine carboxylation implies an enrichment of reactions in which it may play functional roles. The results also suggest that by switching enzymes on and off under appropriate physicochemical conditions spontaneous PTMs may serve as an important and widely used efficient biological machinery for regulation. PMID:24419378

  12. Lysine carboxylation: unveiling a spontaneous post-translational modification

    SciTech Connect

    Jimenez-Morales, David; Adamian, Larisa; Shi, Dashuang; Liang, Jie

    2014-01-01

    A computational method for the prediction of lysine carboxylation (KCX) in protein structures is described. The method accurately identifies misreported KCXs and predicts previously unknown KCX sites. The carboxylation of lysine residues is a post-translational modification (PTM) that plays a critical role in the catalytic mechanisms of several important enzymes. It occurs spontaneously under certain physicochemical conditions, but is difficult to detect experimentally. Its full impact is unknown. In this work, the signature microenvironment of lysine-carboxylation sites has been characterized. In addition, a computational method called Predictor of Lysine Carboxylation (PreLysCar) for the detection of lysine carboxylation in proteins with available three-dimensional structures has been developed. The likely prevalence of lysine carboxylation in the proteome was assessed through large-scale computations. The results suggest that about 1.3% of large proteins may contain a carboxylated lysine residue. This unexpected prevalence of lysine carboxylation implies an enrichment of reactions in which it may play functional roles. The results also suggest that by switching enzymes on and off under appropriate physicochemical conditions spontaneous PTMs may serve as an important and widely used efficient biological machinery for regulation.

  13. 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.

  14. Quantum groups and functional relations for higher rank

    E-print Network

    H. Boos; F. Göhmann; A. Klümper; Kh. S. Nirov; A. V. Razumov

    2015-04-13

    A detailed construction of the universal integrability objects related to the integrable systems associated with the quantum group $\\mathrm U_q(\\mathcal L(\\mathfrak{sl}_3))$ is given. The full proof of the functional relations in the form independent of the representation of the quantum group on the quantum space is presented. The case of the general gradation and general twisting is treated. The specialization of the universal functional relations to the case when the quantum space is the state space of a discrete spin chain is described.

  15. From Infinite to Two Dimensions through the Functional Renormalization Group

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  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. Galaxy and Group Baryonic Mass Functions for the RESOLVE Survey

    NASA Astrophysics Data System (ADS)

    Eckert, Kathleen D.; Kannappan, Sheila; Moffett, Amanda J.; Baker, Ashley; Stark, David; Berlind, Andreas A.; Storey-Fisher, Kate; Erickcek, Adrienne L.; Norris, Mark A.; Resolve Team

    2015-01-01

    We present a comparison of the galaxy and group baryonic mass functions for a subvolume of the RESOLVE (Resolved Spectroscopy Of a Local VolumE) survey. RESOLVE occupies A and B semester volumes totaling ~52,000 cubic Mpc, complete in baryonic mass to ~10^9.3 Msun and 10^9.0 Msun respectively, with galaxies and groups ranging in halo mass from 10^11-10^14 Msun. The A semester volume is surrounded by the larger ECO catalog, which lacks complete HI data but occupies ~561,000 cubic Mpc. We define the observed baryonic mass of a galaxy or group to be the sum of its stellar and cold atomic hydrogen components, with the latter inferred indirectly for much of ECO. For groups, we infer the total baryonic mass by summing the observed components of each constituent galaxy and add the likely hot halo gas based on prescriptions from observations and semi-analytic models. We perform subhalo/halo abundance matching between observed galaxies/groups and dark matter simulations, and we compare derived halo properties based on matching on luminosity vs. on observed baryonic mass (or on inferred total baryonic mass for groups). We also present a status update on the galaxy and group velocity functions for these surveys, which will allow for more direct comparison with dark matter simulations. This project was supported by NSF funding for the RESOLVE survey (AST-0955368).

  18. Functional renormalization group approach to correlated fermion systems

    NASA Astrophysics Data System (ADS)

    Metzner, Walter; Salmhofer, Manfred; Honerkamp, Carsten; Meden, Volker; Schönhammer, Kurt

    2012-01-01

    Numerous correlated electron systems exhibit a strongly scale-dependent behavior. Upon lowering the energy scale, collective phenomena, bound states, and new effective degrees of freedom emerge. Typical examples include (i) competing magnetic, charge, and pairing instabilities in two-dimensional electron systems; (ii) the interplay of electronic excitations and order parameter fluctuations near thermal and quantum phase transitions in metals; and (iii) correlation effects such as Luttinger liquid behavior and the Kondo effect showing up in linear and nonequilibrium transport through quantum wires and quantum dots. The functional renormalization group is a flexible and unbiased tool for dealing with such scale-dependent behavior. Its starting point is an exact functional flow equation, which yields the gradual evolution from a microscopic model action to the final effective action as a function of a continuously decreasing energy scale. Expanding in powers of the fields one obtains an exact hierarchy of flow equations for vertex functions. Truncations of this hierarchy have led to powerful new approximation schemes. This review is a comprehensive introduction to the functional renormalization group method for interacting Fermi systems. A self-contained derivation of the exact flow equations is presented and frequently used truncation schemes are described. Reviewing selected applications it is shown how approximations based on the functional renormalization group can be fruitfully used to improve our understanding of correlated fermion systems.

  19. Species, functional groups, and thresholds in ecological resilience

    USGS Publications Warehouse

    Sundstrom, Shana M.; Allen, Craig R.; Barichievy, Chris

    2012-01-01

    The cross-scale resilience model states that ecological resilience is generated in part from the distribution of functions within and across scales in a system. Resilience is a measure of a system's ability to remain organized around a particular set of mutually reinforcing processes and structures, known as a regime. We define scale as the geographic extent over which a process operates and the frequency with which a process occurs. Species can be categorized into functional groups that are a link between ecosystem processes and structures and ecological resilience. We applied the cross-scale resilience model to avian species in a grassland ecosystem. A species’ morphology is shaped in part by its interaction with ecological structure and pattern, so animal body mass reflects the spatial and temporal distribution of resources. We used the log-transformed rank-ordered body masses of breeding birds associated with grasslands to identify aggregations and discontinuities in the distribution of those body masses. We assessed cross-scale resilience on the basis of 3 metrics: overall number of functional groups, number of functional groups within an aggregation, and the redundancy of functional groups across aggregations. We assessed how the loss of threatened species would affect cross-scale resilience by removing threatened species from the data set and recalculating values of the 3 metrics. We also determined whether more function was retained than expected after the loss of threatened species by comparing observed loss with simulated random loss in a Monte Carlo process. The observed distribution of function compared with the random simulated loss of function indicated that more functionality in the observed data set was retained than expected. On the basis of our results, we believe an ecosystem with a full complement of species can sustain considerable species losses without affecting the distribution of functions within and across aggregations, although ecological resilience is reduced. We propose that the mechanisms responsible for shaping discontinuous distributions of body mass and the nonrandom distribution of functions may also shape species losses such that local extinctions will be nonrandom with respect to the retention and distribution of functions and that the distribution of function within and across aggregations will be conserved despite extinctions.

  20. Carboxylated poly(glycerol methacrylate)s for doxorubicin delivery.

    PubMed

    Ma, Yanan; Gao, Hui; Gu, Wenxing; Yang, Ying-Wei; Wang, Yinong; Fan, Yunge; Wu, Guolin; Ma, Jianbiao

    2012-01-23

    Poly(glycerol methacrylate)s (PGOHMAs) were successfully synthesized via the hydrolysis of the epoxy groups on linear and/or star-shaped poly(glycidyl methacrylate)s (PGMAs). Further modification of the hydroxyl groups on PGOHMAs with succinic anhydride (SA) or 1,2-cyclohexanedicarboxylic anhydride (CDA) resulted in a new type of polyacid polymer, namely, PGOHMACOOH for short, which was then employed to prepare pH-sensitive assemblies using dialysis method. The carboxylated polymers were quite effective in the encapsulation of doxorubicin hydrochloride (DOX) by electrostatic interaction. Compared with poly(acrylic acid) (PAA), the star-shaped PGOHMA modified with CDA exhibited higher encapsulation efficiency and loading capacity, as well as better pH-responsive release profile. Scanning electron microscope images showed that the polymeric nanoparticles before and after encapsulation of DOX were spherical in shape. The encapsulation efficiency, loading capacity and release properties of these polymers were found to rely on their backbone architectures and the type of carboxylated functionalities. By fine-tuning these factors to achieve optimal properties, such type of polymeric materials holds promise as an attractive and effective drug delivery vehicle. PMID:22085680

  1. 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.

  2. Victimization in the Peer Group and Children's Academic Functioning

    ERIC Educational Resources Information Center

    Schwartz, David; Gorman, Andrea Hopmeyer; Nakamoto, Jonathan; Toblin, Robin L.

    2005-01-01

    This short-term longitudinal investigation focused on associations between victimization in the peer group and academic functioning over a 1-year period. The authors used a multi-informant approach to assess peer victimization, symptoms of depression, and academic outcomes for 199 elementary school children (average age of 9.0 years; 105 boys, 94…

  3. 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

  4. Quantum groups and functional relations for lower rank

    E-print Network

    Kh. S. Nirov; A. V. Razumov

    2014-12-23

    A detailed construction of the universal integrability objects related to the integrable systems associated with the quantum group $\\mathrm U_q(\\mathcal L(\\mathfrak{sl}_2))$ is given. The full proof of the functional relations in the form independent of the representation of the quantum group on the quantum space is presented. The case of the general gradation and general twisting is treated. The specialization of the universal functional relations to the case when the quantum space is the state space of a discrete spin chain is described. This is a degression of the corresponding consideration for the case of the quantum group $\\mathrm U_q(\\mathcal L(\\mathfrak{sl}_3))$ with an extensions to the higher spin case.

  5. 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. ...

  6. 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

  7. 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

  8. Selective carboxyl methylation of structurally altered calmodulins in Xenopus oocytes.

    PubMed

    Desrosiers, R R; Romanik, E A; O'Connor, C M

    1990-12-01

    The eucaryotic protein carboxyl methyltransferase specifically modifies atypical D-aspartyl and L-isoaspartyl residues which are generated spontaneously as proteins age. The selectivity of the enzyme for altered proteins in intact cells was explored by co-injecting Xenopus laevis oocytes with S-adenosyl-L-[methyl-3H]methionine and structurally altered calmodulins generated during a 14-day preincubation in vitro. Control experiments indicated that the oocyte protein carboxyl methyltransferase was not saturated with endogenous substrates, since protein carboxyl methylation rates could be stimulated up to 8-fold by increasing concentrations of injected calmodulin. The oocyte protein carboxyl methyltransferase showed strong selectivities for bovine brain and bacterially synthesized calmodulins which had been preincubated in the presence of 1 mM EDTA relative to calmodulins which had been preincubated with 1 mM CaCl2. Radioactive methyl groups were incorporated into base-stable linkages with recombinant calmodulin as well as into carboxyl methyl esters following its microinjection into oocytes. This base-stable radioactivity most likely represents the trimethylation of lysine 115, a highly conserved post-translational modification which is present in bovine and Xenopus but not in bacterially synthesized calmodulin. Endogenous oocyte calmodulin incorporates radioactivity into both carboxyl methyl esters and into base-stable linkages following microinjection of oocytes with S-adenosyl-[methyl-3H]methionine alone. The rate of oocyte calmodulin carboxyl methylation in injected oocytes is calculated to be similar to that of lysine 115 trimethylation, suggesting that the rate of calmodulin carboxyl methylation is similar to that of calmodulin synthesis. At steady state, oocyte calmodulin contains approximately 0.0002 esters/mol of protein, which turn over rapidly. The results suggest the quantitative significance of carboxyl methylation in the metabolism of oocyte calmodulin. PMID:2123492

  9. Scaling and superscaling solutions from the functional renormalization group

    E-print Network

    Hellwig, Tobias; Zanusso, Omar

    2015-01-01

    We study the renormalization group flow of $\\mathbb{Z}_2$-invariant supersymmetric and non-supersymmetric scalar models in the local potential approximation using functional renormalization group methods. We focus our attention to the fixed points of the renormalization group flow of these models, which emerge as scaling solutions. In two dimensions these solutions are interpreted as the minimal (supersymmetric) models of conformal field theory, while in three dimension they are manifestations of the Wilson-Fisher universality class and its supersymmetric counterpart. We also study the analytically continued flow in fractal dimensions between 2 and 4 and determine the critical dimensions for which irrelevant operators become relevant and change the universality class of the scaling solution. We also include novel analytic and numerical investigations of the properties that determine the occurrence of the scaling solutions within the method. For each solution we offer new techniques to compute the spectrum of ...

  10. Scaling and superscaling solutions from the functional renormalization group

    NASA Astrophysics Data System (ADS)

    Hellwig, Tobias; Wipf, Andreas; Zanusso, Omar

    2015-10-01

    We study the renormalization group flow of Z2 -invariant supersymmetric and nonsupersymmetric scalar models in the local potential approximation using functional renormalization group methods. We focus our attention on the fixed points of the renormalization group flow of these models, which emerge as scaling solutions. In two dimensions these solutions are interpreted as the minimal (supersymmetric) models of conformal field theory, while in three dimensions they are manifestations of the Wilson-Fisher universality class and its supersymmetric counterpart. We also study the analytically continued flow in fractal dimensions between 2 and 4 and determine the critical dimensions for which irrelevant operators become relevant and change the universality class of the scaling solution. We include novel analytic and numerical investigations of the properties that determine the occurrence of the scaling solutions within the method. For each solution we offer new techniques to compute the spectrum of the deformations and obtain the corresponding critical exponents.

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

    PubMed

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

    2015-05-15

    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. PMID:25733248

  12. Organized thiol functional groups in mesoporous core shell colloids

    SciTech Connect

    Marchena, Martin H.; Granada, Mara; Bordoni, Andrea V.; Joselevich, Maria; Troiani, Horacio; Williams, Federico J.; Wolosiuk, Alejandro

    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.

  13. Ordered self-assembled monolayers terminated with different chemical functional groups direct neural stem cell linage behaviours.

    PubMed

    Yao, Shenglian; Liu, Xi; He, Jin; Wang, Xiumei; Wang, Ying; Cui, Fu-Zhai

    2015-01-01

    Neural stem cells (NSCs) have been a promising candidate for stem cell-based nerve tissue regeneration. Therefore, the design of idea biomaterials that deliver precise regulatory signals to control stem cell fate is currently a crucial issue that depends on a profound understanding of the interactions between NSCs with the surrounding micro-environment. In this work, self-assembled monolayers of alkanethiols on gold with different chemical groups, including hydroxyl (-OH), amino (-NH2), carboxyl (-COOH) and methyl (-CH3), were used as a simple model to study the effects of surface chemistry on NSC fate decisions. Contact angle measurement and x-ray photoelectron spectroscopy (XPS) examination implied that all types of alkanethiols self-assembled on gold into a close-packed phase structure with similar molecular densities. In this study, we evaluated NSC adhesion, migration and differentiation in response to different chemical functional groups cultured under serum-free conditions. Our studies showed that NSCs exhibited certain phenotypes with extreme sensitivity to surface chemical groups. Compared with other functional groups, the SAMs with hydroxyl end-groups provided the best micro-environment in promoting NSC migration and maintaining an undifferentiated or neuronal differentiation state.??-NH2 surfaces directed neural stem cells into astrocytic lineages, while NSCs on??-COOH and??-CH3 surfaces had a similar potency to differentiate into three nerve lineages. To further investigate the possible signaling pathway, the gene expression of integrin ?1 and ?4 were examined. The results indicated that a high expression of ?1 integrin would probably have a tight correlation with the expression of nestin, which implied the stemness of NSCs, while ?4 integrin seemed to correspond to the differentiated NSCs. The results presented here give useful information for the future design of biomaterials to regulate the preservation, proliferation and differentiation of NSCs for central nervous tissue engineering. PMID:26694757

  14. A Group Theoretical Approach to Graviton Two-Point Function

    E-print Network

    S. Rahbardehghan; H. Pejhan; M. Elmizadeh

    2015-01-22

    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 \\cite{binegar}. Pursuing this path, such a field equation was obtained in de Sitter space \\cite{takook}. In 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 infrared divergence.

  15. Identifying functional sites based on prediction of charged group behavior.

    PubMed

    Ondrechen, Mary Jo

    2004-09-01

    This protocol describes the implementation and interpretation of THEMATICS, a simple computational predictor of functional information for proteins from the three-dimensional structure. This method is based on the computation of the electrical potential function for the protein and the calculation of the predicted titration curves for each of the titratable groups in the protein. While most of the titratable residues in a protein have predicted titration behavior that fits the Henderson-Hasselbalch equation, the ionizable residues in the active site generally deviate dramatically from the typical behavior. From the calculated titration curves, one identifies those residues that deviate significantly from Henderson-Hasselbalch behavior. A cluster of two or more of such deviant titratable residues in physical proximity is a reliable predictor of active-site location. PMID:18428736

  16. Biogenic Hydroxylated Carboxylate Monomers Serve as Dispersants for

    E-print Network

    Aksay, Ilhan A.

    carboxylic acids, citric acid and tricarballylic acid were undertaken: measurements of zeta potential in Table 1. Tartaric, citric, and mucic acids produced the best dispersion with the 113 Mat. Res. Soc. Symp, citric, mucic, malic, tartronic and mesoxalic acids all contain hydroxyl group(s). In contrast, succinic

  17. Photothermal therapy of Lewis lung carcinoma in mice using gold nanoshells on carboxylated polystyrene spheres

    NASA Astrophysics Data System (ADS)

    Liu, Huiyu; Chen, Dong; Tang, Fangqiong; Du, Gangjun; Li, Linlin; Meng, Xianwei; Liang, Wei; Zhang, Yangde; Teng, Xu; Li, Yi

    2008-11-01

    A new approach towards the design of gold nanoshells on carboxylated polystyrene spheres (GNCPSs) is reported here. Gold nanoshells were self-assembled on the surface of carboxylated polystyrene spheres by a seed growth method. Chitosan (CHI) was used as a functional agent of carboxylated polystyrene spheres for attaching gold seeds. The surface plasmon resonance (SPR) peak of GNCPSs can be tuned, greatly redshifted, over a broad spectral range including the near-infrared (NIR) wavelength region, which provides maximal penetration of light through tissue. Irradiation of GNCPSs at their peak extinction coefficient results in the conversion of light to heat energy that produces a local rise in temperature. Our study revealed that the Lewis lung carcinoma (LLC) in mice treated with GNCPSs exposed to a low dose of NIR light (808 nm, 4 W cm-2) induced irreversible tissue damage. The tumor volumes of the treatment group by GNCPSs were significantly lower than those of control groups, with an average inhibition rate over 55% (P<0.005). This study proves that GNCPSs are promising in plasmonic photothermal tumor therapy.

  18. Changes in Bird Functional Diversity across Multiple Land Uses: Interpretations of Functional Redundancy Depend on Functional Group Identity

    PubMed Central

    Luck, Gary W.; Carter, Andrew; Smallbone, Lisa

    2013-01-01

    Examinations of the impact of land-use change on functional diversity link changes in ecological community structure driven by land modification with the consequences for ecosystem function. Yet, most studies have been small-scale, experimental analyses and primarily focussed on plants. There is a lack of research on fauna communities and at large-scales across multiple land uses. We assessed changes in the functional diversity of bird communities across 24 land uses aligned along an intensification gradient. We tested the hypothesis that functional diversity is higher in less intensively used landscapes, documented changes in diversity using four diversity metrics, and examined how functional diversity varied with species richness to identify levels of functional redundancy. Functional diversity, measured using a dendogram-based metric, increased from high to low intensity land uses, but observed values did not differ significantly from randomly-generated expected values. Values for functional evenness and functional divergence did not vary consistently with land-use intensification, although higher than expected values were mostly recorded in high intensity land uses. A total of 16 land uses had lower than expected values for functional dispersion and these were mostly low intensity native vegetation sites. Relations between functional diversity and bird species richness yielded strikingly different patterns for the entire bird community vs. particular functional groups. For all birds and insectivores, functional evenness, divergence and dispersion showed a linear decline with increasing species richness suggesting substantial functional redundancy across communities. However, for nectarivores, frugivores and carnivores, there was a significant hump-shaped or non-significant positive linear relationship between these functional measures and species richness indicating less redundancy. Hump-shaped relationships signify that the most functionally diverse communities occur at intermediate levels of species richness. Interpretations of redundancy thus vary for different functional groups and related ecosystem functions (e.g. pollination), and can be substantially different to relationships involving entire ecological communities. PMID:23696844

  19. Observations of Adolescent Peer Group Interactions as a Function of Within- and Between-Group Centrality Status

    ERIC Educational Resources Information Center

    Ellis, Wendy E.; Dumas, Tara M.; Mahdy, Jasmine C.; Wolfe, David A.

    2012-01-01

    Observations of adolescent (n = 258; M age = 15.45) peer group triads (n = 86) were analyzed to identify conversation and interaction styles as a function of within-group and between-group centrality status. Group members' discussions about hypothetical dilemmas were coded for agreements, disagreements, commands, and opinions. Interactions during…

  20. 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

  1. 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.

  2. The influence of oxygen-containing functional groups on the dispersion of single-walled carbon nanotubes in amide solvents.

    PubMed

    Brandão, S D F; Andrada, D; Mesquita, A F; Santos, A P; Gorgulho, H F; Paniago, R; Pimenta, M A; Fantini, C; Furtado, C A

    2010-08-25

    Surface composition plays an important role in carbon nanotube dispersibility in different environments. Indeed, it determines the choice of dispersion medium. In this paper the effect of oxidation on the dispersion of HiPCO single-walled carbon nanotubes (SWNTs) in N-methyl-pyrrolidinone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-dodecyl-pyrrolidinone (N12P) and cyclohexyl-pyrrolidinone (CHP) was systematically studied. During the oxidation process, similar amounts of carboxylic acid and phenolic groups were introduced to mostly already existing defects. For each solvent the dispersion limits and the absorption coefficients were estimated by optical absorption analysis over a range of SWNT concentrations. The presence of acid oxygenated groups increased SWNT dispersibility in NMP, DMF and DMA, but decreased in N12P and CHP. The absorption coefficients, however, decreased for all solvents after oxidation, reflecting the weakening of the effective transition dipole of the ?-? transition with even limited extension functionalization and solvent interaction. The analysis of the results in terms of Hansen and Flory-Huggins solubility parameters evidenced the influence of dipolar interactions and hydrogen bonding on the dispersibility of oxidized SWNTs. PMID:21386512

  3. The influence of oxygen-containing functional groups on the dispersion of single-walled carbon nanotubes in amide solvents

    NASA Astrophysics Data System (ADS)

    Brandão, S. D. F.; Andrada, D.; Mesquita, A. F.; Santos, A. P.; Gorgulho, H. F.; Paniago, R.; Pimenta, M. A.; Fantini, C.; Furtado, C. A.

    2010-08-01

    Surface composition plays an important role in carbon nanotube dispersibility in different environments. Indeed, it determines the choice of dispersion medium. In this paper the effect of oxidation on the dispersion of HiPCO single-walled carbon nanotubes (SWNTs) in N-methyl-pyrrolidinone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), N-dodecyl-pyrrolidinone (N12P) and cyclohexyl-pyrrolidinone (CHP) was systematically studied. During the oxidation process, similar amounts of carboxylic acid and phenolic groups were introduced to mostly already existing defects. For each solvent the dispersion limits and the absorption coefficients were estimated by optical absorption analysis over a range of SWNT concentrations. The presence of acid oxygenated groups increased SWNT dispersibility in NMP, DMF and DMA, but decreased in N12P and CHP. The absorption coefficients, however, decreased for all solvents after oxidation, reflecting the weakening of the effective transition dipole of the ?-? transition with even limited extension functionalization and solvent interaction. The analysis of the results in terms of Hansen and Flory-Huggins solubility parameters evidenced the influence of dipolar interactions and hydrogen bonding on the dispersibility of oxidized SWNTs.

  4. Controls of functional group chemistry on calcium carbonate nucleation: Insights into systematics of biomolecular innovations for skeletal mineralization?

    NASA Astrophysics Data System (ADS)

    Dove, P. M.; Hamm, L. M.; Giuffre, A. J.

    2012-12-01

    Living organisms produce skeletal structures within a complex matrix of organic macromolecules that guide the nucleation and growth of crystalline structures into the organic-inorganic composites we know as biominerals. This type of biomolecule-directed mineralization is an ancient process as evidenced by structures in the fossil record that date to the Ediacaran (ca. 549 Ma). Our understanding of template-directed biomineralization, however, is largely based upon assumptions from studies that: 1) qualitatively demonstrate some chemical functionalities influence the nucleating mineral phase and morphology; 2) propose proteins are the primary driver to template-directed mineralization and 3) propose the ubiquitous polysaccharides are inert components. Thus, a mechanistic basis for how the underlying chemistry of macromolecules controls nucleation kinetics and thermodynamics in template-directed nucleation is not well established. Moreover, there is not yet a good appreciation for how patterns of skeletal mineralization evolved with biochemical innovations in response to environmental changes over geologic timescales. In small steps toward understanding biochemical controls on biomineralization, we test the hypothesis that the kinetics and thermodynamics of calcium carbonate (CaCO3) formation is regulated by a systematic relationship to the functional group chemistry of macromolecules. A long-term goal is to establish the energetic basis for biochemical motifs that are seen (and not seen) at sites of calcification across the phylogenetic tree. Two types of studies were conducted. The first measured nucleation rates on model biomolecular substrates with termini that are found in proteins associated with sites of calcification (-COOH, -PO4, and -SH) and two alkanethiol chain lengths (16-C and 11-C) at a variety of chemical driving forces. The measurements show functional group chemistry and molecule conformation regulate rates by a predictable relation to interfacial free energy. A second study tested the hypothesis that polysaccharides can also confer reactivity through their functional group chemistry. Using high purity polysaccharides with regular monomer sequences as simple model compounds, we quantify the effect of functional group chemistry (chitosan, hyaluronic acid, heparin, alginic acid) and monomer sequencing (two stereoisomers of alginic acid) on the kinetic and thermodynamic barriers to CaCO3 formation. Analysis of the data indicates the barriers to nucleation are correlated by a systematic relationship to charge as the number of carboxyl groups per monomer of polysaccharide. The findings demonstrate a physical basis for how organic surfaces regulate the thermodynamic barrier to nucleation through interfacial free energy and suggest the chemical basis for recurring motifs that are seen in modern organisms. We also show that polysaccharides may indeed have active roles in promoting calcite mineralization and suggest their presumed function as inert framework molecules should be revisited.

  5. Correlation functions from a unified variational principle: Trial Lie groups

    NASA Astrophysics Data System (ADS)

    Balian, R.; Vénéroni, M.

    2015-11-01

    Time-dependent expectation values and correlation functions for many-body quantum systems are evaluated by means of a unified variational principle. It optimizes a generating functional depending on sources associated with the observables of interest. It is built by imposing through Lagrange multipliers constraints that account for the initial state (at equilibrium or off equilibrium) and for the backward Heisenberg evolution of the observables. The trial objects are respectively akin to a density operator and to an operator involving the observables of interest and the sources. We work out here the case where trial spaces constitute Lie groups. This choice reduces the original degrees of freedom to those of the underlying Lie algebra, consisting of simple observables; the resulting objects are labeled by the indices of a basis of this algebra. Explicit results are obtained by expanding in powers of the sources. Zeroth and first orders provide thermodynamic quantities and expectation values in the form of mean-field approximations, with dynamical equations having a classical Lie-Poisson structure. At second order, the variational expression for two-time correlation functions separates-as does its exact counterpart-the approximate dynamics of the observables from the approximate correlations in the initial state. Two building blocks are involved: (i) a commutation matrix which stems from the structure constants of the Lie algebra; and (ii) the second-derivative matrix of a free-energy function. The diagonalization of both matrices, required for practical calculations, is worked out, in a way analogous to the standard RPA. The ensuing structure of the variational formulae is the same as for a system of non-interacting bosons (or of harmonic oscillators) plus, at non-zero temperature, classical Gaussian variables. This property is explained by mapping the original Lie algebra onto a simpler Lie algebra. The results, valid for any trial Lie group, fulfill consistency properties and encompass several special cases: linear responses, static and time-dependent fluctuations, zero- and high-temperature limits, static and dynamic stability of small deviations.

  6. Improved preparation of haloalkyl bridged carboxylic ortho esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protection of a carboxylic acid function as a bridged ortho ester derivative enables the use of strong basic conditions in the synthetic strategy. For example, a protected 3-halopropionic acid can behave like an alkyl halide because the protons, alpha to the halide function, are less acidic. Ester...

  7. Fragrance material review on methyl hexyl oxo cyclopentanone carboxylate.

    PubMed

    Scognamiglio, J; Jones, L; Letizia, C S; Api, A M

    2012-10-01

    A toxicologic and dermatologic review of methyl hexyl oxo cyclopentanone carboxylate when used as a fragrance ingredient is presented. Methyl hexyl oxo cyclopentanone carboxylate is a member of the fragrance structural group ketones cyclopentanones and cyclopentenones. The common characteristic structural element of the group members is a cyclopentanone or cyclopentenone ring with a straight or branched chain alkane or alkene substituent. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for methyl hexyl oxo cyclopentanone carboxylate were evaluated then summarized and includes physical properties, acute toxicity, skin irritation, skin sensitization, and genotoxicity data. A safety assessment of the entire ketones cyclopentanones and cyclopentenones will be published simultaneously with this document; please refer to Belsito et al. (this issue) for an overall assessment of the safe use of this material and all ketones cyclopentanones and cyclopentenones in fragrances. PMID:22449537

  8. Correlated starting points for the functional renormalization group

    NASA Astrophysics Data System (ADS)

    Wentzell, N.; Taranto, C.; Katanin, A.; Toschi, A.; Andergassen, S.

    2015-01-01

    We present a general frame to extend functional renormalization group (fRG) based computational schemes by using an exactly solvable interacting reference problem as starting point for the RG flow. The systematic expansion around this solution accounts for a nonperturbative inclusion of correlations. Introducing auxiliary fermionic fields by means of a Hubbard-Stratonovich transformation, we derive the flow equations for the auxiliary fields and determine the relation to the conventional weak-coupling truncation of the hierarchy of flow equations. As a specific example we consider the dynamical mean field theory (DMFT) solution as reference system, and discuss the relation to the recently introduced DMF2RG and the dual-fermion formalism.

  9. 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.

  10. 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

  11. Functional trait responses to grazing are mediated by soil moisture and plant functional group identity

    PubMed Central

    Zheng, Shuxia; Li, Wenhuai; Lan, Zhichun; Ren, Haiyan; Wang, Kaibo

    2015-01-01

    Abundant evidence has shown that grazing alters plant functional traits, community structure and ecosystem functioning of grasslands. Few studies, however, have tested how plant responses to grazing are mediated by resource availability and plant functional group identity. We examined the effects of grazing on functional traits across a broad range of species along a soil moisture gradient in Inner Mongolia grassland. Our results showed that trait syndromes of plant size (individual biomass) and shoot growth (leaf N content and leaf density) distinguished plant species responses to grazing. The effects of grazing on functional traits were mediated by soil moisture and dependent on functional group identity. For most species, grazing decreased plant height but increased leaf N and specific leaf area (SLA) along the moisture gradient. Grazing enhanced the community-weighted attributes (leaf NCWM and SLACWM), which were triggered mainly by the positive trait responses of annuals and biennials and perennial grasses, and increased relative abundance of perennial forbs. Our results suggest that grazing-induced species turnover and increased intraspecific trait variability are two drivers for the observed changes in community weighted attributes. The dominant perennial bunchgrasses exhibited mixed tolerance–resistance strategies to grazing and mixed acquisitive–conservative strategies in resource utilization. PMID:26655858

  12. Functional trait responses to grazing are mediated by soil moisture and plant functional group identity.

    PubMed

    Zheng, Shuxia; Li, Wenhuai; Lan, Zhichun; Ren, Haiyan; Wang, Kaibo

    2015-01-01

    Abundant evidence has shown that grazing alters plant functional traits, community structure and ecosystem functioning of grasslands. Few studies, however, have tested how plant responses to grazing are mediated by resource availability and plant functional group identity. We examined the effects of grazing on functional traits across a broad range of species along a soil moisture gradient in Inner Mongolia grassland. Our results showed that trait syndromes of plant size (individual biomass) and shoot growth (leaf N content and leaf density) distinguished plant species responses to grazing. The effects of grazing on functional traits were mediated by soil moisture and dependent on functional group identity. For most species, grazing decreased plant height but increased leaf N and specific leaf area (SLA) along the moisture gradient. Grazing enhanced the community-weighted attributes (leaf NCWM and SLACWM), which were triggered mainly by the positive trait responses of annuals and biennials and perennial grasses, and increased relative abundance of perennial forbs. Our results suggest that grazing-induced species turnover and increased intraspecific trait variability are two drivers for the observed changes in community weighted attributes. The dominant perennial bunchgrasses exhibited mixed tolerance-resistance strategies to grazing and mixed acquisitive-conservative strategies in resource utilization. PMID:26655858

  13. 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

  14. Four-point functions and the permutation group S4

    NASA Astrophysics Data System (ADS)

    Eichmann, Gernot; Fischer, Christian S.; Heupel, Walter

    2015-09-01

    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 for future efficient calculations of these and similar objects.

  15. Butane-1,4-diyl bis­(pyridine-3-carboxyl­ate)

    PubMed Central

    Vallejos, Javier; Brito, Iván; Cárdenas, Alejandro; Bolte, Michael

    2012-01-01

    Mol­ecules of the title compound (alternative name: butane-1,4-diyl dinicotinate), C16H16N2O4, lie on a inversion centre, located at the mid-point of the central C—C bond of the aliphatic chain, giving one half-mol­ecule per asymmetric unit. The butane chain adopts an all-trans conformation. The dihedral angle between the mean plane of the butane-3-carboxyl­ate group [for the non-H atoms, maximum deviation = 0.0871?(15)?Å] and the pyridine ring is 10.83?(7)°. In the crystal, mol­ecules lie in planes parallel to (122). The structure features weak ?–? inter­actions with a centroid–centroid distance of 3.9281?(11)?Å. PMID:22807836

  16. Chemical modification and pH dependence of kinetic parameters to identify functional groups in a glucosyltransferase from Strep. Mutans

    SciTech Connect

    Bell, J.E.; Leone, A.; Bell, E.T.

    1986-05-01

    A glucosyltransferase, forming a predominantly al-6 linked glucan, was partially purified from the culture filtrate of S. mutans GS-5. The kinetic properties of the enzyme, assessed using the transfer of /sup 14/C glucose from sucrose into total glucan, were studied at pH values from pH 3.5 to 6.5. From the dependence of km on pH, a group with pKa = 5.5 must be protonated to maximize substrate binding. From plots of V/sub max/ vs pH two groups, with pKa's of 4.5 and 5.5 were indicated. The results suggest the involvement of either two carboxyl groups (one protonated, one unprotonated in the native enzyme) or a carboxyl group (unprotonated) and some other protonated group such as histidine, cysteine. Chemical modification studies showed that Diethylyrocarbonate (histidine specific) had no effect on enzyme activity while modification with p-phydroxy-mercuribenzoate or iodoacetic acid (sulfhydryl reactive) and carbodimide reagents (carboxyl specific) resulted in almost complete inactivation. Activity loss was dependent upon time of incubation and reagent concentration. The disaccharide lylose, (shown to be an inhibitor of the enzyme with similar affinity to sucrose) offers no protection against modification by the sulfhydryl reactive reagents.

  17. Plant Species and Functional Group Combinations Affect Green Roof Ecosystem Functions

    PubMed Central

    Lundholm, Jeremy; MacIvor, J. Scott; MacDougall, Zachary; Ranalli, Melissa

    2010-01-01

    Background Green 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 improving these functions. Methodology/Principal Findings We used a replicated modular extensive (shallow growing- medium) green roof system planted with monocultures or mixtures containing one, three or five life-forms, to quantify two ecosystem services: summer roof cooling and water capture. We also measured the related ecosystem properties/processes of albedo, evapotranspiration, and the mean and temporal variability of aboveground biomass over four months. Mixtures containing three or five life-form groups, simultaneously optimized several green roof ecosystem functions, outperforming monocultures and single life-form groups, but there was much variation in performance depending on which life-forms were present in the three life-form mixtures. Some mixtures outperformed the best monocultures for water capture, evapotranspiration, and an index combining both water capture and temperature reductions. Combinations of tall forbs, grasses and succulents simultaneously optimized a range of ecosystem performance measures, thus the main benefit of including all three groups was not to maximize any single process but to perform a variety of functions well. Conclusions/Significance Ecosystem services from green roofs can be improved by planting certain life-form groups in combination, directly contributing to climate change mitigation and adaptation strategies. The strong performance by certain mixtures of life-forms, especially tall forbs, grasses and succulents, warrants further investigation into niche complementarity or facilitation as mechanisms governing biodiversity-ecosystem functioning relationships in green roof ecosystems. PMID:20300196

  18. Methyl 9-diethyl-amino-2,2-bis-(4-meth-oxy-phen-yl)-2H-benzo[h]chromene-5-carboxyl-ate.

    PubMed

    Kim, Moon-Hwan; Park, Hee-Moon; Kim, Chong-Hyeak

    2011-04-01

    In the title compound, C(31)H(29)NO(5), the methyl carboxyl-ate and dimethyl-amino groups on the naphtho-pyran group are almost coplanar with the naphtho-pyran ring system [r.m.s. deviations = 0.08?(2) and 0.161?(2)?Å, respectively]. The dihedral angle between the methyl carboxyl-ate and dimethyl-amino groups is 4.9?(1)°. The pyran ring has an envelope conformation with the quaternary C atom out of plane by 0.4739?(13)?Å. The meth-oxy-phenyl substituent forms a dihedral angle of 16.6?(1)° with the plane of the benzene ring, while the other meth-oxy-phenyl group is almost coplanar, making a dihedral angle of 1.4?(1)°. PMID:21754239

  19. Facile synthesis of functionalized ionic surfactant templated mesoporous silica for incorporation of poorly water-soluble drug.

    PubMed

    Li, Jing; Xu, Lu; Yang, Baixue; Wang, Hongyu; Bao, Zhihong; Pan, Weisan; Li, Sanming

    2015-08-15

    The present paper reported amino group functionalized anionic surfactant templated mesoporous silica (Amino-AMS) for loading and release of poorly water-soluble drug indomethacin (IMC) and carboxyl group functionalized cationic surfactant templated mesoporous silica (Carboxyl-CMS) for loading and release of poorly water-soluble drug famotidine (FMT). Herein, Amino-AMS and Carboxyl-CMS were facilely synthesized using co-condensation method through two types of silane coupling agent. Amino-AMS was spherical nanoparticles, and Carboxyl-CMS was well-formed spherical nanosphere with a thin layer presented at the edge. Drug loading capacity was obviously enhanced when using Amino-AMS and Carboxyl-CMS as drug carriers due to the stronger hydrogen bonding force formed between surface modified carrier and drug. Amino-AMS and Carboxyl-CMS had the ability to transform crystalline state of loaded drug from crystalline phase to amorphous phase. Therefore, IMC loaded Amino-AMS presented obviously faster release than IMC because amorphous phase of IMC favored its dissolution. The application of asymmetric membrane capsule delayed FMT release significantly, and Carboxyl-CMS favored sustained release of FMT due to its long mesoporous channels and strong interaction formed between its carboxyl group and amino group of FMT. PMID:26163764

  20. Titania-promoted carboxylic acid alkylations of alkenes and cascade addition-cyclizations.

    PubMed

    Manley, David W; McBurney, Roy T; Miller, Phillip; Walton, John C; Mills, Andrew; O'Rourke, Christopher

    2014-02-01

    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

  1. Submicron aerosol organic functional groups, ions, and water content at the Centreville SEARCH site (Alabama), during SOAS campaign

    NASA Astrophysics Data System (ADS)

    Ruggeri, G.; Ergin, G.; Modini, R. L.; Takahama, S.

    2013-12-01

    The SOAS campaign was conducted from June 1 to July 15 of 2013 in order to understand the relationship between biogenic and anthropogenic emissions in the South East US1,2. In this study, the organic and inorganic composition of submicron aerosol in the Centreville SEARCH site was measured by Fourier Transform Infrared Spectroscopy (FTIR) and the Ambient Ion Monitor (AIM; URG Corporation), whereas the aerosol water content was measured with a Dry Ambient Aerosol Size Spectrometer (DAASS)3. Organic functional group analysis was performed on PM1 aerosol selected by cyclone and collected on teflon filters with a time resolution of 4-12 hours, using one inlet heated to 50 °C and the other operated either at ambient temperature or 70 °C 4. The AIM measured both condensed and gas phase composition with a time resolution of 1 hour, providing partitioning behavior of inorganic species such as NH3/NH4+, HNO3/NO3-. These measurements collectively permit calculation of pure-component vapor pressures of candidate organic compounds and activity coefficients of interacting components in the condensed phase, using models such as SIMPOL.15, E-AIM6, and AIOMFAC7. From these results, the water content of the aerosol is predicted, and a comparison between modeled and measured partitioning of inorganic compounds and water vapor are discussed, in addition to organic aerosol volatility prediction based on functional group analysis. [1]- Goldstein, A.H., et al., Biogenic carbon and anthropogenic pollutants combine to form a cooling haze over the southeastern United States. Proceedings of the National Academy of Sciences of the United States of America, 2009. 106(22), 8835-8840. [2]- Carlton, A.G., Turpin, B.J., 2013. Particle partitioning potential of organic compounds is highest in the Eastern US and driven by anthropogenic water. Atmospheric Chemistry and Physics Discussions 13, 12743-12770. [3]- Khlystov, A., Stanier, C.O., Takahama, S., Pandis, S.N., 2005. Water content of ambient aerosol during the Pittsburgh Air Quality Study. Journal of Geophysical Research: Atmospheres 110, n/a-n/a. [4]- Takahama, S., Johnson, A., Russell, L.M., 2013. Quantification of Carboxylic and Carbonyl Functional Groups in Organic Aerosol Infrared Absorbance Spectra. Aerosol Science and Technology 47, 310-325. [5]- Pankow, J.F., Asher, W.E., 2008. SIMPOL.1: a simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds. Atmos. Chem. Phys. 8, 2773-2796. [6]- Clegg, S.L., Brimblecombe, P., Wexler, A.S., 1998. Thermodynamic Model of the System H+-NH4+-SO42--NO3--H2O at Tropospheric Temperatures. J. Phys. Chem. A 102, 2137-2154. [7]- Zuend, A., Marcolli, C., Booth, A.M., Lienhard, D.M., Soonsin, V., Krieger, U.K., Topping, D.O., McFiggans, G., Peter, T., Seinfeld, J.H., 2011. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups. Atmos. Chem. Phys. 11, 9155-9206.

  2. The Nonenzymatic Reactivity of the Acyl-Linked Metabolites of Mefenamic Acid toward Amino and Thiol Functional Group Bionucleophiles

    PubMed Central

    Horng, Howard

    2013-01-01

    Mefenamic acid (MFA), a carboxylic acid–containing nonsteroidal anti-inflammatory drug, is metabolized into the chemically-reactive MFA-1-O-acyl-glucuronide (MFA-1-O-G), MFA-acyl-adenylate (MFA-AMP), and the MFA-S-acyl-coenzyme A (MFA-CoA), all of which are electrophilic and capable of acylating nucleophilic sites on biomolecules. In this study, we investigate the nonenzymatic ability of each MFA acyl-linked metabolite to transacylate amino and thiol functional groups on the acceptor biomolecules Gly, Tau, l-glutathione (GSH), and N-acetylcysteine (NAC). In vitro incubations with each of the MFA acyl-linked metabolites (1 ?M) in buffer under physiologic conditions with Gly, Tau, GSH, or NAC (10 mM) revealed that MFA-CoA was 11.5- and 19.5-fold more reactive than MFA-AMP toward the acylation of cysteine-sulfhydryl groups of GSH and NAC, respectively. However, MFA-AMP was more reactive toward both Gly and Tau, 17.5-fold more reactive toward the N-acyl-amidation of taurine than its corresponding CoA thioester, while MFA-CoA displayed little reactivity toward glycine. Additionally, mefenamic acid-S-acyl-glutathione (MFA-GSH) was 5.6- and 108-fold more reactive toward NAC than MFA-CoA and MFA-AMP, respectively. In comparison with MFA-AMP and MFA-CoA, MFA-1-O-G was not significantly reactive toward all four bionucleophiles. MFA-AMP, MFA-CoA, MFA-1-O-G, MFA-GSH, and mefenamic acid-taurine were also detected in rat in vitro hepatocyte MFA (100 ?M) incubations, while mefenamic acid-glycine was not. These results demonstrate that MFA-AMP selectively reacts with the amino functional groups of glycine and lysine nonenzymatically, MFA-CoA selectively reacts nonenzymatically with the thiol functional groups of GSH and NAC, and MFA-GSH reacts with the thiol functional group of GSH nonenzymatically, all of which may potentially elicit an idiosyncratic toxicity in vivo. PMID:23975029

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

    E-print Network

    Borguet, Eric

    Detection 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 rights reserved. Keywords: Carbon fibers; X-ray photoelectron spectroscopy; Infrared spectroscopy

  4. Highly adaptive tests for group differences in brain functional connectivity

    PubMed Central

    Kim, Junghi; Pan, Wei

    2015-01-01

    Resting-state functional magnetic resonance imaging (rs-fMRI) and other technologies have been offering evidence and insights showing that altered brain functional networks are associated with neurological illnesses such as Alzheimer's disease. Exploring brain networks of clinical populations compared to those of controls would be a key inquiry to reveal underlying neurological processes related to such illnesses. For such a purpose, group-level inference is a necessary first step in order to establish whether there are any genuinely disrupted brain subnetworks. Such an analysis is also challenging due to the high dimensionality of the parameters in a network model and high noise levels in neuroimaging data. We are still in the early stage of method development as highlighted by Varoquaux and Craddock (2013) that “there is currently no unique solution, but a spectrum of related methods and analytical strategies” to learn and compare brain connectivity. In practice the important issue of how to choose several critical parameters in estimating a network, such as what association measure to use and what is the sparsity of the estimated network, has not been carefully addressed, largely because the answers are unknown yet. For example, even though the choice of tuning parameters in model estimation has been extensively discussed in the literature, as to be shown here, an optimal choice of a parameter for network estimation may not be optimal in the current context of hypothesis testing. Arbitrarily choosing or mis-specifying such parameters may lead to extremely low-powered tests. Here we develop highly adaptive tests to detect group differences in brain connectivity while accounting for unknown optimal choices of some tuning parameters. The proposed tests combine statistical evidence against a null hypothesis from multiple sources across a range of plausible tuning parameter values reflecting uncertainty with the unknown truth. These highly adaptive tests are not only easy to use, but also high-powered robustly across various scenarios. The usage and advantages of these novel tests are demonstrated on an Alzheimer's disease dataset and simulated data.

  5. Prediction of functional sites in proteins using conserved functional group analysis.

    PubMed

    Innis, C Axel; Anand, A Prem; Sowdhamini, R

    2004-04-01

    A detailed knowledge of a protein's functional site is an absolute prerequisite for understanding its mode of action at the molecular level. However, the rapid pace at which sequence and structural information is being accumulated for proteins greatly exceeds our ability to determine their biochemical roles experimentally. As a result, computational methods are required which allow for the efficient processing of the evolutionary information contained in this wealth of data, in particular that related to the nature and location of functionally important sites and residues. The method presented here, referred to as conserved functional group (CFG) analysis, relies on a simplified representation of the chemical groups found in amino acid side-chains to identify functional sites from a single protein structure and a number of its sequence homologues. We show that CFG analysis can fully or partially predict the location of functional sites in approximately 96% of the 470 cases tested and that, unlike other methods available, it is able to tolerate wide variations in sequence identity. In addition, we discuss its potential in a structural genomics context, where automation, scalability and efficiency are critical, and an increasing number of protein structures are determined with no prior knowledge of function. This is exemplified by our analysis of the hypothetical protein Ydde_Ecoli, whose structure was recently solved by members of the North East Structural Genomics consortium. Although the proposed active site for this protein needs to be validated experimentally, this example illustrates the scope of CFG analysis as a general tool for the identification of residues likely to play an important role in a protein's biochemical function. Thus, our method offers a convenient solution to rapidly and automatically process the vast amounts of data that are beginning to emerge from structural genomics projects. PMID:15033369

  6. Separation of certain carboxylic acids utilizing cation exchange membranes

    DOEpatents

    Chum, Helena L. (Arvada, CO); Sopher, David W. (Maarssenbroek, NL)

    1984-01-01

    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.degree. 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.

  7. 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.

  8. Electrochemiluminescence sensor for melamine based on a Ru(bpy)3(2+)-doped silica nanoparticles/carboxylic acid functionalized multi-walled carbon nanotubes/Nafion composite film modified electrode.

    PubMed

    Chen, Xiaomei; Lian, Sai; Ma, Ying; Peng, Aihong; Tian, Xiaotian; Huang, Zhiyong; Chen, Xi

    2016-01-01

    In this work, a sensitive electrochemiluminescence (ECL) sensor for the determination of melamine (MEL) was developed based on a Ru(bpy)3(2+)-doped silica nanoparticles (RUDS)/carboxylic acid functionalized multi-walled carbon nanotubes (CMWCNTs)/Nafion composite film modified electrode. The homogeneous spherical RUDS were synthesized by a reverse microemulsion method. As Ru(bpy)3(2+) were encapsulated in the RUDS, Ru(bpy)3(2+) dropping from the modified electrode can be greatly prevented, which is helpful for obtaining a stable ECL signal. Moreover, to improve the conductivity of the film and promote the electron transfer rate on electrode surface, CMWCNTs with excellent electrical conductivity and large surface area were applied in the construction of the sensing film. As CMWCNTs acted as electron bridges making more Ru(bpy)3(2+) participate in the reaction, the ECL intensity was greatly enhanced. Under the optimum conditions, the relative ECL signal (?IECL) was proportional to the logarithmic MEL concentration ranging from 5×10(-13) to 1×10(-7)molL(-1) with a detection limit of 1×10(-13)molL(-1). To verify the reliability, the thus-fabricated ECL sensor was applied to determine the concentration of MEL in milk. Based on these investigations, the proposed ECL sensor exhibited good feasibility and high sensitivity for the determination of MEL, promising the applicability of this sensor in practical analysis. PMID:26695338

  9. Polymer containing functional end groups is base for new polymers

    NASA Technical Reports Server (NTRS)

    Hirshfield, S. M.

    1971-01-01

    Butadiene is polymerized with lithium-p-lithiophenoxide to produce linear polymer containing oxy-lithium group at one end and active carbon-lithium group at other end. Living polymers represent new approach to preparation of difunctional polymers in which structural features, molecular weight, type and number of end groups are controlled.

  10. Preconversion catalytic deoxygenation of phenolic functional groups. Quarterly technical progress report, January 1--March 30, 1996 and April 1--June 30, 1996

    SciTech Connect

    Kubiak, C.P.

    1997-05-01

    Over the course of his 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 his 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}{sup 3} {pi} bonding observed in metal-allyl complexes.

  11. Effects of Oxygen Element and Oxygen-Containing Functional Groups on Surface Wettability of Coal Dust with Various Metamorphic Degrees Based on XPS Experiment

    PubMed Central

    Zhou, Gang; Xu, Cuicui; Cheng, Weimin; Zhang, Qi; Nie, Wen

    2015-01-01

    To investigate the difference of surface oxygen element and oxygen-containing functional groups among coal dusts with different metamorphic degrees and their influence on surface wettability, a series of X-ray photoelectron spectroscopy experiments on 6 coal samples are carried out. The result demonstrates that the O/C ratio of coal surface shows an overall increasing trend compared with the result of its elements analysis. As the metamorphic degree increases, the O/C ratio on the surface gradually declines and the hydrophilic groups tend to fall off from coal surface. It could be found that different coals show different surface distributions of carboxyl and hydroxyl which are considered as the greatest promoter to the wettability of coal surface. With the change of metamorphic degree, the distribution of ether group is irregular while the carbonyl distribution keeps stable. In general, as the metamorphic degree goes higher, the content of oxygen-containing polar group tends to reduce. According to the measurement results, the contact angle is negatively related to the content of oxygen element, surface oxygen, and polar groups. In addition, compared with surface oxygen content, the content of oxygen-containing polar group serves as a more reasonable indicator of coal dust wettability. PMID:26257980

  12. A mechanistic analysis of the increase in the thermal stability of proteins in aqueous carboxylic acid salt solutions.

    PubMed Central

    Kaushik, J. K.; Bhat, R.

    1999-01-01

    The stability of proteins is known to be affected significantly in the presence of high concentration of salts and is highly pH dependent. Extensive studies have been carried out on the stability of proteins in the presence of simple electrolytes and evaluated in terms of preferential interactions and increase in the surface tension of the medium. We have carried out an in-depth study of the effects of a series of carboxylic acid salts: ethylene diamine tetra acetate, butane tetra carboxylate, propane tricarballylate, citrate, succinate, tartarate, malonate, and gluconate on the thermal stability of five different proteins that vary in their physico-chemical properties: RNase A, cytochrome c, trypsin inhibitor, myoglobin, and lysozyme. Surface tension measurements of aqueous solutions of the salts indicate an increase in the surface tension of the medium that is very strongly correlated with the increase in the thermal stability of proteins. There is also a linear correlation of the increase in thermal stability with the number of carboxylic groups in the salt. Thermal stability has been found to increase by as much as 22 C at 1 M concentration of salt. Such a high thermal stability at identical concentrations has not been reported before. The differences in the heat capacities of denaturation, deltaCp for RNase A, deduced from the transition curves obtained in the presence of varying concentrations of GdmCl and that of carboxylic acid salts as a function of pH, indicate that the nature of the solvent medium and its interactions with the two end states of the protein control the thermodynamics of protein denaturation. Among the physico-chemical properties of proteins, there seems to be an interplay of the hydrophobic and electrostatic interactions that lead to an overall stabilizing effect. Increase in surface free energy of the solvent medium upon addition of the carboxylic acid salts appears to be the dominant factor in governing the thermal stability of proteins. PMID:10210200

  13. 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

  14. The preparation of new functionalized [2.2]paracyclophane derivatives with N-containing functional groups

    PubMed Central

    Narayanan, Swaminathan Vijay; Jones, Peter G

    2015-01-01

    Summary The two isomeric bis(isocyanates) 4,12- and 4,16-di-isocyanato[2.2]paracyclophane, 16 and 28, have been prepared from their corresponding diacids by simple routes. The two isomers are versatile intermediates for the preparation of various cyclophanes bearing substituents with nitrogen-containing functional groups, e.g., the pseudo-ortho diamine 8, the bis secondary amine 23, and the crownophanes 18 and 19. Several of these new cyclophane derivatives (18, 19, 22, 26, 28) have been characterized by X-ray structural analysis. PMID:25977718

  15. Students' Perceptions of Classroom Group Work as a Function of Group Member Selection

    ERIC Educational Resources Information Center

    Myers, Scott A.

    2012-01-01

    The purpose of this assessment was to examine whether differences exist between students who self-select their classroom work group members and students who are randomly assigned to their classroom work groups in terms of their use of organizational citizenship behaviors with their work group members; their commitment to, trust in, and relational…

  16. 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

  17. 14 CFR Section 11 - Functional Classification-Operating Expenses of Group II and Group III Air Carriers

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Functional Classification-Operating Expenses of Group II and Group III Air Carriers Section 11 Section 11 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED...

  18. 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.

  19. A Generalized Logistic Regression Procedure to Detect Differential Item Functioning among Multiple Groups

    ERIC Educational Resources Information Center

    Magis, David; Raiche, Gilles; Beland, Sebastien; Gerard, Paul

    2011-01-01

    We present an extension of the logistic regression procedure to identify dichotomous differential item functioning (DIF) in the presence of more than two groups of respondents. Starting from the usual framework of a single focal group, we propose a general approach to estimate the item response functions in each group and to test for the presence…

  20. Generation of Turkish Noun and Verbal Groups with Systemic-Functional Grammar1

    E-print Network

    Cicekli, Ilyas

    Generation of Turkish Noun and Verbal Groups with Systemic-Functional Grammar1 Ilyas Cicekli Dept@mailbox.syr.edu Abstract This paper mainly presents noun and verbal group parts of a Turkish sentence generator to produce{functional representation and the realization of noun and verbal groups in Turkish sentences. 1 Introduction Natural

  1. Generation of Turkish Verbal Groups with Systemic-Functional Grammar1

    E-print Network

    Cicekli, Ilyas

    Generation of Turkish Verbal Groups with Systemic-Functional Grammar1 Turgay Korkmaz and Ilyas-mail: fturgay,ilyasg@cs.bilkent.edu.tr Abstract This paper mainly presents the verbal group part of a Turkish. In this paper, we present the systemic{functional representation and realization of Turkish verbal groups

  2. PhI(OAc)2 mediated decarboxylative sulfonylation of ?-aryl-?,?-unsaturated carboxylic acids: a synthesis of (E)-vinyl sulfones.

    PubMed

    Katrun, Praewpan; Hlekhlai, Sornsiri; Meesin, Jatuporn; Pohmakotr, Manat; Reutrakul, Vichai; Jaipetch, Thaworn; Soorukram, Darunee; Kuhakarn, Chutima

    2015-04-28

    A highly efficient metal-free decarboxylative sulfonylation protocol for the preparation of (E)-vinyl sulfones from of ?-aryl-?,?-unsaturated carboxylic acids using sodium sulfinates and (diacetoxyiodo)benzene (PhI(OAc)2) was developed. This strategy offers a simple and expedient synthesis of (E)-vinyl sulfones bearing a wide variety of functional groups. A radical-based pathway has been proposed for this decarboxylative sulfonylation reaction. PMID:25811160

  3. 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.

  4. ZETA FUNCTIONS OF DISCRETE GROUPS ACTING ON BRYAN CLAIR AND SHAHRIAR MOKHTARI-SHARGHI

    E-print Network

    Clair, Bryan

    of operators defined on edges or vertices of the tree. A zeta function associated to a non-uniform tree lattice or finite covolume group action. Introduction The zeta function associated to a finite graph originatedZETA FUNCTIONS OF DISCRETE GROUPS ACTING ON TREES BRYAN CLAIR AND SHAHRIAR MOKHTARI

  5. Green functions for groups of types E6 and F4 in characteristic 2

    E-print Network

    Malle, Gunter

    the Green functions of G, and they are the ones we are going to determine. The Qw are known Green functions for groups of types E6 and F4, Germany In this paper we determine the Green functions for the connected groups E6(2n ), 2E 6(2n

  6. Large Sample Group Independent Component Analysis of Functional Magnetic Resonance Imaging Using Anatomical

    E-print Network

    Yuille, Alan L.

    Large Sample Group Independent Component Analysis of Functional Magnetic Resonance Imaging Using of functional magnetic resonance imaging (fMRI) signals that is capable of revealing connected brain systems fMRI; group ICA; bagging; clustering; bootstrap I. INTRODUCTION Functional magnetic resonance

  7. Zwitterionic metal carboxylate complexes: In solid state

    NASA Astrophysics Data System (ADS)

    Nath, Bhaskar; Kalita, Dipjyoti; Baruah, Jubaraj B.

    2012-07-01

    A flexible dicarboxylic acid having composition [(CH(o-C5H4N)(p-C6H4OCH2CO2H)2] derived from corresponding bis-phenol reacts with various metal(II) acetates such as manganese(II), cobalt(II) and nickel(II) acetate leads to zwtterionic complexes with compositions [CH(o-C5H4N)(p-C6H4OCH2CO2){p-C6H4OCH2CO2M(H2O)5}].6H2O (where M = Mn, Co, Ni). The complexes are characterised by X-ray crystallography. These complexes have chiral center due to unsymmetric structure conferred to the ligand through coordination at only one carboxylate group of the ligand. In solid state these complexes are racemic.

  8. Quantification of chemical states, dissociation constants and contents of oxygen-containing groups on the surface of biochars produced at different temperatures.

    PubMed

    Chen, Zaiming; Xiao, Xin; Chen, Baoliang; Zhu, Lizhong

    2015-01-01

    Surface functional groups such as carboxyl play a vital role in the environmental applications of biochar as a soil amendment. However, the quantification of oxygen-containing groups on a biochar surface still lacks systematical investigation. In this paper, we report an integrated method combining chemical and spectroscopic techniques that were established to quantitatively identify the chemical states, dissociation constants (pK(a)), and contents of oxygen-containing groups on dairy manure-derived biochars prepared at 100-700 °C. Unexpectedly, the dissociation pH of carboxyl groups on the biochar surface covered a wide range of pH values (pH 2-11), due to the varied structural microenvironments and chemical states. For low temperature biochars (? 350 °C), carboxyl existed not only as hydrogen-bonded carboxyl and unbonded carboxyl groups but also formed esters at the surface of biochars. The esters consumed OH(-) via saponification in the alkaline pH region and enhanced the dissolution of organic matter from biochars. For high temperature biochars (? 500 °C), esters came from carboxyl were almost eliminated via carbonization (ester pyrolysis), while lactones were developed. The surface density of carboxyl groups on biochars decreased sharply with the increase of the biochar-producing temperature, but the total contents of the surface carboxyls for different biochars were comparable (with a difference <3-fold) as a result of the expanded surface area at high pyrolytic temperatures. Understanding the wide pKa ranges and the abundant contents of carboxyl groups on biochars is a prerequisite to recognition of the multifunctional applications and biogeochemical cycling of biochars. PMID:25453912

  9. Group structure and weighting function effects on neutron penetration through thick sodium-iron shields

    SciTech Connect

    Fu, C.Y.; Ingersoll, D.T.

    1987-01-01

    The effects of group structures and weighting functions on neutron penetration through a thick Na-Fe geometry are studied. The recommended broad-group (61-neutron/23-gamma-ray) and few-group (22-neutron/10-gamma-ray) structures are tailored to the sodium and iron resonances, windows, and capture gamma-ray spectra. The best weighting functions are shown to be fine-group fluxes selected from a few key locations in the geometry. These group structures and weighting functions, relative to existing group structures and conventional weighting functions, improve the accuracy of the computed 61-neutron-group Bonner ball responses by up to one hundred percent and of the computed 22-neutron-group results by up to six hundred percent.

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

    SciTech Connect

    Dutta, Saikat; Wu, Kevin C.-W. E-mail: kevinwu@ntu.edu.tw; Kao, Hsien-Ming E-mail: kevinwu@ntu.edu.tw

    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 {sup 13}C 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.

  11. Do carboximide-carboxylic acid combinations form co-crystals? The role of hydroxyl substitution on the formation of co-crystals and eutectics.

    PubMed

    Kaur, Ramanpreet; Gautam, Raj; Cherukuvada, Suryanarayan; Guru Row, Tayur N

    2015-05-01

    Carboxylic acids, amides and imides are key organic systems which provide understanding of molecular recognition and binding phenomena important in biological and pharmaceutical settings. In this context, studies of their mutual interactions and compatibility through co-crystallization may pave the way for greater understanding and new applications of their combinations. Extensive co-crystallization studies are available for carboxylic acid/amide combinations, but only a few examples of carboxylic acid/imide co-crystals are currently observed in the literature. The non-formation of co-crystals for carboxylic acid/imide combinations has previously been rationalized, based on steric and computed stability factors. In the light of the growing awareness of eutectic mixtures as an alternative outcome in co-crystallization experiments, the nature of various benzoic acid/cyclic imide combinations is established in this paper. Since an additional functional group can provide sites for new intermolecular inter-actions and, potentially, promote supramolecular growth into a co-crystal, benzoic acids decorated with one or more hydroxyl groups have been systematically screened for co-crystallization with one unsaturated and two saturated cyclic imides. The facile formation of an abundant number of hydroxybenzoic acid/cyclic carboximide co-crystals is reported, including polymorphic and variable stoichiometry co-crystals. In the cases where co-crystals did not form, the combinations are shown invariably to result in eutectics. The presence or absence and geometric disposition of hydroxyl functionality on benzoic acid is thus found to drive the formation of co-crystals or eutectics for the studied carboxylic acid/imide combinations. PMID:25995843

  12. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    NASA Astrophysics Data System (ADS)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  13. 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.

  14. 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.

  15. Effect of Gross Motor Group Exercise on Functional Status in Chronic Stroke: A Randomized Controlled Trial

    PubMed Central

    Kim, Kwanghyun; Lee, Byungjoon; Lee, Wanhee

    2014-01-01

    [Purpose] The aim of this study was to understand the effects of task-oriented gross motor group exercise based on motor development on chronic stroke patients’ joint, bone, muscle, and motor functions and activities of daily living. [Subjects] Twenty-eight stroke patients hospitalized at P municipal nursing facility for the severely handicapped were randomly assigned to the gross motor group exercise group (experimental group, n=14) or the control group (n=14). [Methods] The two groups performed morning exercise led by a trainer for 30 minutes a day, 5 times a week for 6 weeks in total. The experimental group performed a gross motor group exercise in addition to this exercise for 50 minutes a day, 3 times a week for 6 weeks in total. Before the experiment, all subjects were measured with the Modified Barthel Index (MBI) and for their neuromuscular skeletal and motor-related functions according to the International Classification of Functioning, Disability and Health. [Results] Significant improvements were found in the experimental group’s neuromusculoskeletal and motor-related functions and MBI test, except for the stability of joint functions. The control group showed no significant difference from the initial evaluation. [Conclusion] The gross motor group exercise based on motor development is recommended for chronic stroke patients with severe handicaps. PMID:25140077

  16. Carboxylic Acids Plasma Membrane Transporters in Saccharomyces cerevisiae.

    PubMed

    Casal, Margarida; Queirós, Odília; Talaia, Gabriel; Ribas, David; Paiva, Sandra

    2016-01-01

    This chapter covers the functionally characterized plasma membrane carboxylic acids transporters Jen1, Ady2, Fps1 and Pdr12 in the yeast Saccharomyces cerevisiae, addressing also their homologues in other microorganisms, as filamentous fungi and bacteria. Carboxylic acids can either be transported into the cells, to be used as nutrients, or extruded in response to acid stress conditions. The secondary active transporters Jen1 and Ady2 can mediate the uptake of the anionic form of these substrates by a H(+)-symport mechanism. The undissociated form of carboxylic acids is lipid-soluble, crossing the plasma membrane by simple diffusion. Furthermore, acetic acid can also be transported by facilitated diffusion via Fps1 channel. At the cytoplasmic physiological pH, the anionic form of the acid prevails and it can be exported by the Pdr12 pump. This review will highlight the mechanisms involving carboxylic acids transporters, and the way they operate according to the yeast cell response to environmental changes, as carbon source availability, extracellular pH and acid stress conditions. PMID:26721276

  17. Novel lead(II) carboxylate arsonate hybrids

    NASA Astrophysics Data System (ADS)

    Yi, Fei-Yan; Song, Jun-Ling; Zhao, Na; Mao, Jiang-Gao

    2008-06-01

    Hydrothermal reactions of lead(II) acetate with phenylarsonic acid (H 2L 1) (or 4-hydroxy-3-nitrophenylarsonic acid, H 3L 2) and 5-sulfoisophthalic acid monosodium salt (NaH 2SIP) (or 1,3,5-benzenetricarboxylic acid (H 3BTC)) as the second metal linkers afforded three novel mixed-ligand lead(II) carboxylate-arsonates, namely, Pb 5(SIP) 2(L 1) 2(H 2O) 1, Pb 3(SIP)(L 2)(H 2O) 2 and Pb(H 2L 2)(H 2BTC) 3. The structure of 1 features a complicated 3D network composed of 2D double layers of lead(II) sulfoisophthalate bridged by 1D chains of lead(II) arsonates along b-axis, forming large tunnels along b-axis which are occupied by phenyl rings of the arsonate ligands. In 2, the Pb(II) ions are bridged by {L 2} 3- anions into a 2D double layer whereas the interconnection of the Pb(II) ions via bridging and chelating SIP anions gave a 2D double layer. The cross-linkage of the above two building units leads to a complicated 3D network. In 3, the interconnection of the Pb(II) ions via bridging {H 2L 2} - and {H 2BTC} - anions leads to a 1D double chain down a-axis. These 1D chains are further interconnected via hydrogen bonds among non-coordination carboxylate groups and arsonate oxygens into a 3D supramolecular architecture.

  18. New integral representations of Whittaker functions for classical Lie groups

    NASA Astrophysics Data System (ADS)

    Gerasimov, A. A.; Lebedev, Dmitrii R.; Oblezin, Sergei V.

    2012-02-01

    The present paper proposes new integral representations of \\mathfrak{g}-Whittaker functions corresponding to an arbitrary semisimple Lie algebra \\mathfrak{g} with the integrand expressed in terms of matrix elements of the fundamental representations of \\mathfrak{g}. For the classical Lie algebras \\mathfrak{sp}_{2\\ell}, \\mathfrak{so}_{2\\ell}, and \\mathfrak{so}_{2\\ell+1} a modification of this construction is proposed, providing a direct generalization of the integral representation of \\mathfrak{gl}_{\\ell+1}-Whittaker functions first introduced by Givental. The Givental representation has a recursive structure with respect to the rank \\ell+1 of the Lie algebra \\mathfrak{gl}_{\\ell+1}, and the proposed generalization to all classical Lie algebras retains this property. It was observed elsewhere that an integral recursion operator for the \\mathfrak{gl}_{\\ell+1}-Whittaker function in the Givental representation coincides with a degeneration of the Baxter \\mathscr{Q}-operator for \\widehat{\\mathfrak{gl}}_{\\ell+1}-Toda chains. In this paper \\mathscr{Q}-operators for the affine Lie algebras \\widehat{\\mathfrak{so}}_{2\\ell}, \\widehat{\\mathfrak{so}}_{2\\ell+1} and a twisted form of \\vphantom{\\rule{0pt}{10pt}}\\widehat{\\mathfrak{gl}}_{2\\ell} are constructed. It is then demonstrated that the relation between integral recursion operators for the generalized Givental representations and degenerate \\mathscr{Q}-operators remains valid for all classical Lie algebras. Bibliography: 33 titles.

  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. 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...

  1. 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...

  2. Functions Preserving Matrix Groups and Iterations for the Matrix Square Root

    E-print Network

    Higham, Nicholas J.

    Functions Preserving Matrix Groups and Iterations for the Matrix Square Root Nicholas J. Higham, D ISSN 1749-9097 #12;FUNCTIONS PRESERVING MATRIX GROUPS AND ITERATIONS FOR THE MATRIX SQUARE ROOT NICHOLAS J. HIGHAM, D. STEVEN MACKEY, NILOUFER MACKEY, AND FRANC¸OISE TISSEUR SIAM J. MATRIX ANAL. APPL. c

  3. Woody Plant Encroachment into Grasslands: Spatial Patterns of Functional Group Distribution and Community

    E-print Network

    Archer, Steven R.

    Woody Plant Encroachment into Grasslands: Spatial Patterns of Functional Group Distribution Abstract Woody plant encroachment into grasslands has been globally widespread. The woody species invading grasslands represent a variety of contrasting plant functional groups and growth forms. Are some woody plant

  4. Detecting and quantifying oxygen functional groups on graphite nanofibers by fluorescence labeling

    E-print Network

    Borguet, Eric

    Detecting and quantifying oxygen functional groups on graphite nanofibers by fluorescence labeling July 2010 A B S T R A C T The ability to quantify functional groups on graphitic carbon nanofiber (GCNF. All rights reserved. 1. Introduction Since the discovery of graphite nanofibers (GCNFs) in the mid

  5. Dissecting latitudinal diversity gradients: functional groups and clades of marine bivalves

    E-print Network

    Dissecting latitudinal diversity gradients: functional groups and clades of marine bivalves Kaustuv-eastern Paci¢c marine shelf bivalves, we found that bivalves as a whole, and both infauna and epifauna SST to diversity remain unclear. Most bivalve clades within broad functional groups conform

  6. 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

    2015-06-18

    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

  7. Metal-Free Coupling of 2-Vinylphenols and Carboxylic Acids: An Access to 3-Acyloxy-2,3-dihydrobenzofurans.

    PubMed

    Chen, Jijun; Shao, Ying; Zheng, Hao; Cheng, Jiang; Wan, Xiaobing

    2015-11-01

    A new coupling reaction between 2-vinylphenols and carboxylic acids was developed to synthesize 3-acyloxy-2,3-dihydrobenzofurans using Bu4NI as a catalyst and t-BuOOH as an oxidant. This simple and practical methodology is notable due to the ability to complete it under metal-free conditions, with easily available precursors, resulting in a product with high atom economy and high functional group tolerance. Upon the basis of experimental observations and literature, a plausible mechanism is proposed. PMID:26457863

  8. 21 CFR 177.1600 - Polyethylene resins, carboxyl modified.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Polyethylene resins, carboxyl modified. 177...Contact Surfaces § 177.1600 Polyethylene resins, carboxyl modified. Carboxyl-modified polyethylene resins may be safely used as...

  9. 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...

  10. 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

  11. 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

  12. Water electrolyte promoted oxidation of functional thiol groups.

    PubMed

    Lauwers, K; Breynaert, E; Rombouts, I; Delcour, J A; Kirschhock, C E A

    2016-04-15

    The formation of disulfide bonds is of the utmost importance for a wide range of food products with gluten or globular proteins as functional agents. Here, the impact of mineral electrolyte composition of aqueous solutions on thiol oxidation kinetics was studied, using glutathione (GSH) and cysteine (CYS) as model systems. Interestingly, the oxidation rate of both compounds into their corresponding disulfides was significantly higher in common tap water than in ultrapure water. The systematic study of different electrolyte components showed that especially CaCl2 improved the oxidation rate of GSH. However, this effect was not observed for CYS, which indicated a strong impact of the local chemical environment on thiol oxidation kinetics. PMID:26675862

  13. Social disinterest attitudes and group cognitive-behavioral social skills training for functional disability in schizophrenia.

    PubMed

    Granholm, Eric; Ben-Zeev, Dror; Link, Peter C

    2009-09-01

    The majority of clinical trials of cognitive-behavioral therapy (CBT) for schizophrenia have used individual therapy to target positive symptoms. Promising results have been found, however, for group CBT interventions and other treatment targets like psychosocial functioning. CBT for functioning in schizophrenia is based on a cognitive model of functional outcome in schizophrenia that incorporates dysfunctional attitudes (eg, social disinterest, defeatist performance beliefs) as mediators between neurocognitive impairment and functional outcome. In this report, 18 clinical trials of CBT for schizophrenia that included measures of psychosocial functioning were reviewed, and two-thirds showed improvements in functioning in CBT. The cognitive model of functional outcome was also tested by examining the relationship between social disinterest attitudes and functional outcome in 79 people with schizophrenia randomized to either group cognitive-behavioral social skills training or a goal-focused supportive contact intervention. Consistent with the cognitive model, lower social disinterest attitudes at baseline and greater reduction in social disinterest during group therapy predicted better functional outcome at end of treatment for both groups. However, the groups did not differ significantly with regard to overall change in social disinterest attitudes during treatment, suggesting that nonspecific social interactions during group therapy can lead to changes in social disinterest, regardless of whether these attitudes are directly targeted by cognitive therapy interventions. PMID:19628761

  14. Acid-catalyzed carboxylic acid esterification and ester hydrolysis mechanism: acylium ion as a sharing active intermediate via a spontaneous trimolecular reaction based on density functional theory calculation and supported by electrospray ionization-mass spectrometry.

    PubMed

    Shi, Hongchang; Wang, Yilei; Hua, Ruimao

    2015-11-11

    By DFT calculation, we found that acid-catalyzed carboxylic acid esterification and ester hydrolysis are brief two-step reactions. First, the carboxylic acid hydroxyl-oxygen or ester alkyl-oxygen is protonated, which generates a highly active acylium ion. The protonation requires an activation energy (Ea) of 4-10 kcal mol(-1), and is the rate-controlling step of the esterification or hydrolysis. Sequentially, the acylium ion spontaneously reacts with two alcohol or two water molecules to form a neutral product molecule; this is a trimolecular reaction. The acylium ion is the highly active intermediate shared by esterification and hydrolysis. ESI-MS data for several typical carboxylic acids confirmed that their acylium ions are easily generated. For 2,4,6-trialkylbenzoic acid and its ester, the two unsubstituted carbons in the benzene ring are very easily protonated, and we have thus revealed the root of the success of Newman's method. Based on these results, the popular esterification and hydrolysis mechanism in organic chemistry textbooks is incorrect. PMID:26445892

  15. Succession of phytoplankton functional groups regulated by monsoonal hydrology in a large canyon-shaped reservoir.

    PubMed

    Xiao, Li-Juan; Wang, Tian; Hu, Ren; Han, Bo-Ping; Wang, Sheng; Qian, Xin; Padisák, Judit

    2011-10-15

    Liuxihe reservoir is a deep, monomictic, oligo-mesotrophic canyon-reservoir in the subtropical monsoon climate region of southern China. Phytoplankton functional groups in the reservoir were investigated and a comparison made between the succession observed in 2008, an exceptionally wet year, and 2009, an average year. The reservoir shows strong annual fluctuations in water level caused by monsoon rains and artificial drawdown. Altogether 28 functional groups of phytoplankton were identified, including 79 genera. Twelve of the groups were analyzed in detail using redundancy analysis. Because of the oligo-mesotrophic and P-limited condition of the reservoir, the dominant functional groups were those tolerant of nutrient (phosphorus) deficiency. The predominant functional groups in the succession process were Groups A (Cyclotella with greatest axial linear dimension<10 ?m), B (Cyclotella with greatest axial linear dimension>10 ?m), LO (Peridinium), LM (Ceratium and Microcystis), E (Dinobryon and Mallomonas), F (Botryococcus), X1 (Ankistrodesmus, Ankyra, Chlorella and Monoraphidium) and X2 (Chlamydomonas and Chroomonas). The development of groups A, B and LO was remarkably seasonal. Group A was dominant during stratification, when characteristic small size and high surface/volume ratio morphology conferred an advantage. Group LO was dominant during dry stratification, when motility was advantageous. Group B plankton exhibited a high relative biomass during periods of reduced euphotic depth and isothermy. Groups LM, E, F, X1 and X2 occasionally exhibited high relative biomasses attributable to specific environmental events (e.g. drawdown, changes in zooplankton community). A greater diversity of phytoplankton functional groups was apparent during isothermy. This study underscores the usefulness of functional algal groups in studying succession in subtropical impoundments, in which phytoplankton succession can be significantly affected by external factors such as monsoonal hydrology and artificial drawdown, which alter variables such as retention time, mixing regime and thermal structure and influence light and nutrient availability. PMID:21831406

  16. POINCARE SERIES AND ZETA FUNCTIONS FOR SURFACE GROUP ACTIONS ON R-TREES

    E-print Network

    Sharp, Richard

    POINCAR´E SERIES AND ZETA FUNCTIONS FOR SURFACE GROUP ACTIONS ON R-TREES Mark Pollicott and Richard, pick a point x T and define the associated Poincar´e series by (s) = g e-sd(x,gx) , where plane. Our definition of a zeta function has strong parallels with the Ihara zeta function associated

  17. Airy Functions for Compact Lie Groups. Rahul N. Fernandez and V. S. Varadarajan

    E-print Network

    Varadarajan, Veeravalli S.

    . The Airy function was discovered by the mathematician and as- tronomer Sir George Biddell Airy, who firstAiry Functions for Compact Lie Groups. Rahul N. Fernandez and V. S. Varadarajan Department of Mathematics University of California, Los Angeles, CA 90095-1555, USA. Abstract. The classical Airy function

  18. 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

  19. Variation of phytoplankton functional groups modulated by hydraulic controls in Hongze Lake, China.

    PubMed

    Tian, Chang; Pei, Haiyan; Hu, Wenrong; Hao, Daping; Doblin, Martina A; Ren, Ying; Wei, Jielin; Feng, Yawei

    2015-11-01

    Hongze Lake is a large, shallow, polymictic, eutrophic lake in the eastern China. Phytoplankton functional groups in this lake were investigated from March 2011 to February 2013, and a comparison was made between the eastern, western, and northern regions. The lake shows strong fluctuations in water level caused by monsoon rains and regular hydraulic controls. By application of the phytoplankton functional group approach, this study aims to investigate the spatial and temporal dynamics and analyze their influencing factors. Altogether, 18 functional groups of phytoplankton were identified, encompassing 187 species. In order to seek the best variable describing the phytoplankton functional group distribution, 14 of the groups were analyzed in detail using redundancy analysis. Due to the turbid condition of the lake, the dominant functional groups were those tolerant of low light. The predominant functional groups in the annual succession were D (Cyclotella spp. and Synedra acus), T (Planctonema lauterbornii), P (Fragilaria crotonensis), X1 (Chlorella vulgaris and Chlorella pyrenoidosa), C (Cyclotella meneghiniana and Cyclotella ocellata), and Y (Cryptomonas erosa). An opposite relationship between water level and the biomass of predominant groups was observed in the present study. Water level fluctuations, caused by monsoonal climate and artificial drawdown, were significant factors influencing phytoplankton succession in Hongze Lake, since they alter the hydrological conditions and influence light and nutrient availability. The clearly demonstrated factors, which significantly influence phytoplankton dynamics in Hongze Lake, will help government manage the large shallow lakes with frequent water level fluctuations. PMID:26178825

  20. 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.

  1. 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.

  2. Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

    PubMed Central

    Matthessen, Roman; Fransaer, Jan; Binnemans, Koen

    2014-01-01

    Summary The near-unlimited availability of CO2 has stimulated a growing research effort in creating value-added products from this greenhouse gas. This paper presents the trends on the most important methods used in the electrochemical synthesis of carboxylic acids from carbon dioxide. An overview is given of different substrate groups which form carboxylic acids upon CO2 fixation, including mechanistic considerations. While most work focuses on the electrocarboxylation of substrates with sacrificial anodes, this review considers the possibilities and challenges of implementing other synthetic methodologies. In view of potential industrial application, the choice of reactor setup, electrode type and reaction pathway has a large influence on the sustainability and efficiency of the process. PMID:25383120

  3. Acting-out: its functions within analytic group psychotherapy and its transformation into dreams.

    PubMed

    Richarz, Bernhard; Römisch, Sylvelin

    2002-07-01

    In group processes, acting-out has diverse functions, all of them equally important. It has an intrapsychic, interpersonal, and group dynamic function. Not only may it be understood as a form of resistance, but also in its communicative and reparative potential. The authors investigate the thesis that acting-out also contains the seed for change, thus helping patients divest themselves of pathological behavior. Using a group process as an example, this article shows how boundaries can be drawn between past and present experiences while using the communicative and reparative functions of acting-out. Unconscious psychodynamics can then be transformed from acting-out into dreams. PMID:12082675

  4. The role of oxygen functional groups in the adsorption of heteroaromatic nitrogen compounds.

    PubMed

    Han, Xue; Lin, Hongfei; Zheng, Ying

    2015-10-30

    A wood-based activated carbon (AC) was oxidized using different oxidants. The resultant adsorbents were applied to adsorb nitrogen (N) containing compounds that appeared in light cycled oil. Appropriate oxidation treatment can increase oxygen functional groups on the surface of AC without much damage to its pore structure. Oxygen functional groups play a key role in enhancing adsorptive selectivity of carbons. Lactone groups can facilitate the selective removal of 1-ring N compounds. Phenolic groups, total CO2-releasing groups and total O groups show an improvement in the adsorption of 2-ring N compounds. Aldehyde groups favor the adsorption of 3-ring and 4-ring N compounds. However, excessive oxidation can result in the collapse of pore structure and closure of pore channels. For instance, the carbon oxidized by a mixture of concentrated H2SO4 and HNO3 has an extremely low adsorption performance. PMID:25967098

  5. Solvatochromic behaviours and structure-spectra relationships of 4-carboxyl-2,6-dinitrophenylazohydroxynaphthalenes

    NASA Astrophysics Data System (ADS)

    Adegoke, Olajire A.; Idowu, Olakunle S.

    2010-02-01

    Comprehensive electronic absorption spectra of a new dye series, 4-carboxyl-2,6-dinitrophenylazohydroxynaphthalenes have been investigated in solvents of varying polarities. The solvent dependent UV-vis spectral shifts were analysed using some solvent physical parameters such as refractive index, dielectric function, hydrogen bonding acceptor ability, orientation of polarization and others. The observed spectral shifts were correlated with different solute-solvent interaction mechanisms using simple and multiple linear regression analyses. The results of the curve fitting coefficients enabled us to classify the various interactions of solvents with the dyes and relate the solvatochromic behaviours to the substituent effects on the dye molecules. Charge-transfer complexation occurring between one of the congeners and N,N'-dimethylformamide was extensively studied and discovered to be both concentration- and temperature-dependent. The electronic character and the chemical nature of the solvents as well as the chemical nature of the other substituents, apart from the common hydroxyl group, are important factors for the observed solvatochromic properties of the 4-carboxyl-2, 6-dinitrophenylazohydroxynaphthalenes.

  6. Vibrational coupling in carboxylic acid dimers.

    PubMed

    Nandi, Chayan K; Hazra, Montu K; Chakraborty, Tapas

    2005-09-22

    The vibrational level splitting in the ground electronic state of carboxylic acid dimers mediated by the doubly hydrogen-bonded networks are investigated using pure and mixed dimers of benzoic acid with formic acid as molecular prototypes. Within the 0-2000-cm(-1) range, the frequencies for the fundamental and combination vibrations of the two dimers are experimentally measured by using dispersed fluorescence spectroscopy in a supersonic jet expansion. Density-functional-theory calculations predict that most of the dimer vibrations are essentially in-phase and out-of-phase combinations of the monomer modes, and many of such combinations show significantly large splitting in vibrational frequencies. The infrared spectrum of the jet-cooled benzoic acid dimer, reported recently by Bakker et al. [J. Chem. Phys. 119, 11180 (2003)], has been used along with the dispersed fluorescence spectra to analyze the coupled g-u vibrational levels. Assignments of the dispersed fluorescence spectra of the mixed dimer are suggested by comparing the vibronic features with those in the homodimer spectrum and the predictions of density-functional-theory calculation. The fluorescence spectra measured by excitations of the low-lying single vibronic levels of the mixed dimer reveal that the hydrogen-bond vibrations are extensively mixed with the ring modes in the S1 surface. PMID:16392485

  7. Controlling surface functionality through generation of thiol groups in a self-assembled monolayer.

    SciTech Connect

    Lud, S. Q.; Neppl, S.; Richter, G.; Bruno, P.; Gruen, D. M.; Jordan, R.; Feulner, P.; Stutzmann, M.; Garrido, J. A.; Materials Science Division; Technische Univ. Munchen

    2010-01-01

    A lithographic method to generate reactive thiol groups on functionalized synthetic diamond for biosensor and molecular electronic applications is developed. We demonstrate that ultrananocrystalline diamond (UNCD) thin films covalently functionalized with surface-generated thiol groups allow controlled thiol-disulfide exchange surface hybridization processes. The generation of the thiol functional head groups was obtained by irradiating phenylsulfonic acid (PSA) monolayers on UNCD surfaces. The conversion of the functional headgroup of the self-assembled monolayer was verified by using X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and fluorescence microscopy. Our findings indicate the selective generation of reactive thiol surface groups. Furthermore, we demonstrate the grafting of yeast cytochrome c to the thiol-modified diamond surface and the electron transfer between protein and electrode.

  8. We conducted genetic and functional analyses of isolates from a patient with group B streptococcal (GBS)

    E-print Network

    Nizet, Victor

    We conducted genetic and functional analyses of isolates from a patient with group B streptococcal with antioxidant properties (6,15), and these 2 factors act in concert to im- pair macrophage-based immune

  9. Chemical imaging of functional group distributions in living biofilms using infrared microspectroscopy

    E-print Network

    Chemical imaging of functional group distributions in living biofilms using infrared Kingdom INTRODUCTION Bacteria predominantly grow as biofilms attached to liquid or solid interfaces. Biofilms are complex structures that contain bacterial cells interwoven in an extracellular polysaccharide

  10. Illustrating the Use of Nonparametric Regression To Assess Differential Item and Bundle Functioning among Multiple Groups.

    ERIC Educational Resources Information Center

    Gierl, Mark J.; Bolt, Daniel M.

    2001-01-01

    Presents an overview of nonparametric regression as it allies to differential item functioning analysis and then provides three examples to illustrate how nonparametric regression can be applied to multilingual, multicultural data to study group differences. (SLD)

  11. Synthesis and small molecule chemistry of the niobaziridine-hydride functional group

    E-print Network

    Figueroa, Joshua S

    2005-01-01

    Chapter 1. Synthesis and Divergent Reactivity of the Niobaziridine-Hydride Functional Group The synthesis, characterization and reactivity of the niobaziridine-hydride complex Nb(H)([eta]²-t- ]Bu(H)C=NAr)(N[Np]Ar)? (la-H; ...

  12. Synthesis of 2-oxazolone-4-carboxylates from 3-nosyloxy- and 3-bromo-2-ketoesters.

    PubMed

    Okonya, John F; Hoffman, Robert V; Johnson, M Catherine

    2002-02-22

    New methods for the synthesis of 2-oxazolone-4-carboxylates from 3-nosyloxy- and 3-bromo-2-ketoesters are described. Condensation of 3-nosyloxy-2-ketoesters with methyl carbamate in refluxing toluene in the presence of p-TSA provided 2-oxazolone-4-carboxylates in good yields (41-80%). Alternatively, bromination of alpha-ketoesters with CuBr2 provided 3-bromo-2-ketoesters which condensed with methyl carbamate in the presence of p-TSA and AgOTf under similar conditions to provide 2-oxazolone-4-carboxylates in comparable yields (30-79%). The 2-oxazolone-4-carboxylates bear functionality that can be elaborated to a variety of potentially useful compounds. For example, some of these heterocycles were readily N-acylated, reduced to alcohols, or saponified and coupled with amino acids. PMID:11846650

  13. FUNCTIONS PRESERVING MATRIX GROUPS AND ITERATIONS FOR THE MATRIX SQUARE ROOT

    E-print Network

    Higham, Nicholas J.

    FUNCTIONS PRESERVING MATRIX GROUPS AND ITERATIONS FOR THE MATRIX SQUARE ROOT NICHOLAS J. HIGHAM, D. STEVEN MACKEY, NILOUFER MACKEY, AND FRANC¸OISE TISSEUR SIAM J. MATRIX ANAL. APPL. c 2005 Society? For example, if A is symplectic when is f(A) symplectic? We show that group structure is preserved precisely

  14. Evaluation of Assertive Training and Homosexual Guidance Service Groups Designed to Improve Homosexual Functioning

    ERIC Educational Resources Information Center

    Russell, A.; Winkler, R.

    1977-01-01

    It is proposed that clinicians should develop research-based assertiveness training procedures for homosexuals that are designed to facilitate homosexual functioning. Subjects (N=27) were assigned to a behaviorally oriented assertive training group or a non-directive group run by a homosexual guidance service. Self-report measures indicated…

  15. 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…

  16. Aggressive and Prosocial Peer Group Functioning: Effects on Children's Social, School, and Psychological Adjustment

    ERIC Educational Resources Information Center

    Chung-Hall, Janet; Chen, Xinyin

    2010-01-01

    This study examined the effects of aggressive and prosocial contexts of peer groups on children's socioemotional and school adjustment. Data on informal peer groups, social functioning, and different aspects of adjustment were collected from multiple sources in a sample of elementary school children (149 boys, 181 girls; M age = 10 years).…

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

    NASA Technical Reports Server (NTRS)

    Foster, Tammy E.; Brooks, J. Renee

    2004-01-01

    The functional grouping hypothesis, which suggests that complexity in ecosystem 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 Florida scrub regulate exchange of carbon and water with the atmosphere as indicated by both instantaneous gas exchange measurements and integrated measures of function (%N, delta C-13, delta N-15, C-N ratio). Using cluster analysis, five distinct physiologically-based functional groups were identified in the fire maintained scrub. These functional groups were tested to determine if they were robust spatially, temporally, and with management regime. Analysis of Similarities (ANOSIM), a non-parametric multivariate analysis, indicated that these five physiologically-based groupings were not altered by plot differences (R = -0.115, p = 0.893) or by the three different management regimes; prescribed burn, mechanically treated and burn, and fire-suppressed (R = 0.018, p = 0.349). The physiological groupings also remained robust between the two climatically different years 1999 and 2000 (R = -0.027, p = 0.725). Easy-to-measure morphological characteristics indicating functional groups would be more practical for scaling and modeling ecosystem processes than detailed gas-exchange measurements, therefore we tested a variety of morphological characteristics as functional indicators. A combination of non-parametric multivariate techniques (Hierarchical cluster analysis, non-metric Multi-Dimensional Scaling, and ANOSIM) were used to compare the ability of life form, leaf thickness, and specific leaf area classifications to identify the physiologically-based functional groups. Life form classifications (ANOSIM; R = 0.629, p 0.001) were able to depict the physiological groupings more adequately than either specific leaf area (ANOSIM; R = 0.426, p = 0.001) or leaf thickness (ANOSIM; R 0.344, p 0.001). The ability of life forms to depict the physiological groupings was improved by separating the parasitic Ximenia americana from the shrub category (ANOSIM; R = 0.794, p = 0.001). Therefore, a life form classification including parasites was determined to be a good indicator of the physiological processes of scrub species, and would be a useful method of grouping for scaling physiological processes to the ecosystem level.

  18. Carboxylic acid accelerated formation of diesters

    DOEpatents

    Tustin, G.C.; Dickson, T.J.

    1998-04-28

    This invention pertains to accelerating the rate of formation of 1,1-dicarboxylic esters from the reaction of an aldehyde with a carboxylic acid anhydride or a ketene in the presence of a non-iodide containing a strong Bronsted acid catalyst by the addition of a carboxylic acid at about one bar pressure and between about 0 and 80 C in the substantial absence of a hydrogenation or carbonylation catalyst.

  19. Carboxylic acid accelerated formation of diesters

    DOEpatents

    Tustin, Gerald Charles (Kingsport, TN); Dickson, Todd Jay (Kingsport, TN)

    1998-01-01

    This invention pertains to accelerating the rate of formation of 1,1-dicarboxylic esters from the reaction of an aldehyde with a carboxylic acid anhydride or a ketene in the presence of a non-iodide containing a strong Bronsted acid catalyst by the addition of a carboxylic acid at about one bar pressure and between about 0.degree. and 80.degree. C. in the substantial absence of a hydrogenation or carbonylation catalyst.

  20. Lung function decline rates according to GOLD group in patients with chronic obstructive pulmonary disease

    PubMed Central

    Kim, Joohae; Yoon, Ho Il; Oh, Yeon-Mok; Lim, Seong Yong; Lee, Ji-Hyun; Kim, Tae-Hyung; Lee, Sang Yeub; Lee, Jin Hwa; Lee, Sang-Do; Lee, Chang-Hoon

    2015-01-01

    Background Since the Global Initiative for Chronic Obstructive Lung Disease (GOLD) groups A–D were introduced, the lung function changes according to group have been evaluated rarely. Objective We investigated the rate of decline in annual lung function in patients categorized according to the 2014 GOLD guidelines. Methods Patients with COPD included in the Korean Obstructive Lung Disease (KOLD) prospective study, who underwent yearly postbronchodilator spirometry at least three times, were included. The main outcome was the annual decline in postbronchodilator forced expiratory volume in 1 second (FEV1), which was analyzed by random-slope and random-intercept mixed linear regression. Results A total 175 participants were included. No significant postbronchodilator FEV1 decline was observed between the groups (?34.4±7.9 [group A]; ?26.2±9.4 [group B]; ?22.7±16.0 [group C]; and ?24.0±8.7 mL/year [group D]) (P=0.79). The group with less symptoms (?32.3±7.2 vs ?25.0±6.5 mL/year) (P=0.44) and the low risk group (?31.0±6.1 vs ?23.6±7.7 mL/year) (P=0.44) at baseline showed a more rapid decline in the postbronchodilator FEV1, but the trends were not statistically significant. However, GOLD stages classified by FEV1 were significantly related to the annual lung function decline. Conclusion There was no significant difference in lung function decline rates according to the GOLD groups. Prior classification using postbronchodilator FEV1 predicts decline in lung function better than does the new classification. PMID:26379432

  1. UNIVERSALITY OF THE SELBERG ZETA-FUNCTION FOR THE MODULAR GROUP

    E-print Network

    Garunkstis, Ramunas

    series. 1. Introduction Let s = + it denote the complex variable. The Riemann zeta-function (s) = n=1 1UNIVERSALITY OF THE SELBERG ZETA-FUNCTION FOR THE MODULAR GROUP PAULIUS DRUNGILAS, RAM¯UNAS GARUNKSTIS, AND AUDRIUS KAC ENAS Abstract. In 1975 S.M. Voronin proved that the Riemann zeta

  2. Quantitative analysis of sulfur functional groups in natural organic matter by XANES spectroscopy

    E-print Network

    Quantitative analysis of sulfur functional groups in natural organic matter by XANES spectroscopy sulfur functionalities in natural organic matter from S K-edge XANES spectroscopy are presented-induced errors, inherent to the choice of a particular curve, are typically lower than 5% of total sulfur

  3. On immanant functions related to Weyl groups of $A_n$

    E-print Network

    Lenka Háková; Agnieszka Tereszkiewicz

    2014-12-04

    In this work we recall the definition of matrix immanants, a generalization of the determinant and permanent of a matrix. We use them to generalize families of symmetric and antisymmetric orbit functions related to Weyl groups of the simple Lie algebras $A_n$. The new functions and their properties are described, in particular we give their continuous orthogonality relations. Several examples are shown.

  4. 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

  5. [Effectiveness of group physiotherapy on motor function in elderly stroke patients].

    PubMed

    Rusi, R

    1991-01-01

    The purpose of this study was to assess the effectiveness of group physiotherapy with special emphasis on motor function of the elderly stroke patients. The sample comprised sixteen persons who had survived a stroke and who lived at home. The sample was treated by using group physiotherapy weekly and ten times altogether. The patients' motor function were assessed before and after the intervention programme with a chart for assessing motor capacity. In addition, each patient was interviewed regarding his or her usual activity, health and life situation. Mainly descriptive statistical methods were used, e.g medians, lower and upper quartiles. The outcome of the study shows that group physiotherapy has effectiveness to maintain and in some respects also to improve basic motor function. It seems that survivors need and also get different kind of rehabilitation and care to minimize their motor impairment and to maintain their functional capacity. PMID:1790016

  6. 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

  7. 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

  8. Measuring Functional Renormalization Group Fixed-Point Functions for Pinned Manifolds A. Alan Middleton,1

    E-print Network

    Wiese, Kay Jörg

    . Proposed field theories are unconventional and harder to control than those for pure critical systems of nonanalytic functions, perturbative control was recovered to one-loop order [i.e., to O 4 ÿ d] and fixed be avoided. This Letter presents a new level of ``smoking gun'' tests of the FRG for manifolds, by directly

  9. Modeling phytoplankton community in reservoirs. A comparison between taxonomic and functional groups-based models.

    PubMed

    Di Maggio, Jimena; Fernández, Carolina; Parodi, Elisa R; Diaz, M Soledad; Estrada, Vanina

    2016-01-01

    In this paper we address the formulation of two mechanistic water quality models that differ in the way the phytoplankton community is described. We carry out parameter estimation subject to differential-algebraic constraints and validation for each model and comparison between models performance. The first approach aggregates phytoplankton species based on their phylogenetic characteristics (Taxonomic group model) and the second one, on their morpho-functional properties following Reynolds' classification (Functional group model). The latter approach takes into account tolerance and sensitivity to environmental conditions. The constrained parameter estimation problems are formulated within an equation oriented framework, with a maximum likelihood objective function. The study site is Paso de las Piedras Reservoir (Argentina), which supplies water for consumption for 450,000 population. Numerical results show that phytoplankton morpho-functional groups more closely represent each species growth requirements within the group. Each model performance is quantitatively assessed by three diagnostic measures. Parameter estimation results for seasonal dynamics of the phytoplankton community and main biogeochemical variables for a one-year time horizon are presented and compared for both models, showing the functional group model enhanced performance. Finally, we explore increasing nutrient loading scenarios and predict their effect on phytoplankton dynamics throughout a one-year time horizon. PMID:26406877

  10. 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

  11. Carboxylate-Based Molybdenum Alkylidene Catalysts: Synthesis, Characterization, and Use as Initiators for 1,6-Heptadiyne

    E-print Network

    Müller, Peter

    Carboxylate-Based Molybdenum Alkylidene Catalysts: Synthesis, Characterization, and Use for the regioselective polymerization of diethyl dipropargylmalonate (DEPDM). Introduction Tungsten and molybdenum highb,d,4 Molybdenum-based compounds are believed to be less sensitive to functionalities than tungsten

  12. Effect of Functionalization on the Crystallization Behavior of MWNT-PBT Nanocomposites

    E-print Network

    Fisher, Frank

    Effect of Functionalization on the Crystallization Behavior of MWNT-PBT Nanocomposites Gaurav Mago1 and mechanical properties, nanocomposites were fabricated with both as-received and carboxyl group (-COOH crystallization. However, functionalization was found to decrease the rate of nanocomposite crystallization

  13. Porous polymer monoliths with large surface area and functional groups prepared via copolymerization of protected functional monomers and hypercrosslinking.

    PubMed

    Maya, Fernando; Svec, Frantisek

    2013-11-22

    A new approach to the preparation of porous polymer monoliths possessing both large surface area and functional groups has been developed. The chloromethyl groups of poly(styrene-co-4-acetoxystyrene-co-vinylbenzyl chloride-co-divinylbenzene) monolith enable post-polymerization hypercrosslinking catalyzed by ferric chloride in dichloroethane leading to a multitude of small pores thus enhancing the surface area. The acetoxy functionalities are easily deprotected using hydrazine to produce polar phenolic hydroxyl groups, which would be difficult to obtain by direct copolymerization of hydroxyl-containing monomers. The hypercrosslinking and deprotection reactions as well as their sequence were studied in detail with bulk polymer monoliths containing up to 50% 4-acetoxystyrene and its progress monitored by infrared spectrometry and nitrogen adsorption/desorption measurements. No significant difference was found for both possible successions. All monoliths were also prepared in a capillary column format, then deprotected and hypercrosslinked. Capillary columns were tested for the separation of small molecules using reversed phase and normal phase chromatographic modes. For polymer monoliths containing 50% deprotected 4-acetoxystyrene, column efficiencies of 40,000 plates/m for benzene in reversed phase mode and 31,800 plates/m for nitrobenzene in normal phase mode, were obtained. The percentage of hydroxyl groups in the monoliths enables modulation of polarity of the stationary phase. They also represent functionalities that are potentially suitable for further modifications and formation of new types of stationary phases for liquid chromatography. PMID:23910448

  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. Assessment of female sexual function in a group of uncircumcised obese Egyptian women.

    PubMed

    Elnashar, A R M; Ibrahim, N H; Ahmed, H-Eh; Hassanin, A M; Elgawady, M A

    2015-09-01

    The aim of the present study was to assess female sexual function in an obese group (250 women) and to compare it with a control group (100 women), among 25-35-year-old uncircumcised Egyptian women, using female sexual function index (FSFI) score. FSFI total score of ?26.55 was considered diagnostic of Female Sexual Dysfunction (FSD). The percentage of FSD in the obese group was 73.6% while it was 71% in the control group, which was statistically insignificant (P>0.05). The difference between both groups regarding the total (FSFI) score was insignificant (P>0.05), but arousal and satisfaction domains scores were significantly lower in the obese group. In the obese group, a strong negative correlation between body mass index and arousal, orgasm and the total FSFI score was found. Women with excessive obesity had the lowest total FSFI score. In the obese group, college graduates had the highest total scores and all domain scores of FSFI followed by high school graduates while the least educated women had the lowest scores and when these subgroups were compared, significant differences were found among them. We conclude that in uncircumcised 25-35-year-old Egyptian women, obesity is not a major detrimental factor for FSD, but it may affect some sexual domains such as arousal and satisfaction, although excessive obesity is associated with FSD. Also, educational and cultural factors may have an impact on perception of sex and pleasure. PMID:26155831

  16. The electrokinetic characterization of gold nanoparticles, functionalized with cationic functional groups, and its' interaction with DNA.

    PubMed

    Lazarus, Geraldine Genevive; Revaprasadu, Neerish; López-Viota, Julián; Singh, Moganavelli

    2014-09-01

    Gold nanoparticles have attracted strong biomedical interest for drug delivery due to their low toxic nature, surface plasmon resonance and capability of increasing the stability of the payload. However, gene transfection represents another important biological application. Considering that cellular barriers keep enclosed their secret to deliver genes using nanoparticles, an important step can be achieved by studying the functionalization of nanoparticles with DNA. In the present contribution the synthesis of nanoparticles consisting of a gold core coated with one or more layers of amino acid (l-lysine), and cationic polyelectrolytes (poly-ethyleneimine and poly-l-lysine) is reported. All nanoparticles were subjected to dynamic light scattering, electrophoretic mobility measurements, UV-vis optical spectrophotometry analysis and transmission electron microscopy imaging. In addition, the adsorption of DNA plasmid (pSGS) with linear and supercoiled configurations was studied for those gold nanoparticles under the most suitable surface modifications. Preliminary results showed that the gold nanoparticles functionalized with poly-ethyleneimine and poly-l-lysine, respectively, and bound to linear DNA configurations, present in absolute value a higher electrophoretic mobility irrespective of the pH of the media, compared to the supercoiled and nicked configuration. The findings from this study suggest that poly-ethyleneimine and poly-l-lysine functionalized gold nanoparticles are biocompatible and may be promising in the chemical design and future optimization of nanostructures for biomedical applications such as gene and drug delivery. PMID:25009100

  17. Effects of metals and surface functional groups on adsorptive properties of GAC

    SciTech Connect

    Uranowski, L.J.; Tessmer, C.H.; Vidic, R.D.

    1995-11-01

    This study evaluated the mechanisms responsible for the catalytic behavior of granular activated carbon (GAC) in the presence of oxygen, which was previously documented in the case of aromatic organic compounds. Oxygen-containing functional groups as well as metals and metal oxide complexes on the GAC surface are being investigated for their role in promoting oxidative coupling of phenolics under oxic conditions. This study is utilizing a virgin bituminous coal-based carbon and versions of the same carbon whose metals were removed by acid-washing or surface functional groups removed by outgassing. Freundich isotherm parameters and solvent extraction efficiencies for the virgin and modified version of this carbon have shown that the removal of oxygen-containing functional groups or metals and their complexes does not have a significant impact on adsorptive properties exhibited in the presence of molecular oxygen.

  18. Wigner Functions for Noncommutative Quantum Mechanics: a group representation based construction

    E-print Network

    S. Hasibul Hassan Chowdhury; S. Twareque Ali

    2015-06-21

    This paper is devoted to the construction and analysis of the Wigner functions for noncommutative quantum mechanics, their marginal distributions and star-products, following a technique developed earlier, {\\it viz\\/,} using the unitary irreducible representations of the group $\\g$, which is the three fold central extension of the abelian group of $\\mathbb R^4$. These representations have been exhaustively studied in earlier papers. The group $\\g$ is identified with the kinematical symmetry group of noncommutative quantum mechanics of a system with two degrees of freedom. The Wigner functions studied here reflect different levels of non-commutativity -- both the operators of position and those of momentum not commuting, the position operators not commuting and finally, the case of standard quantum mechanics, obeying the canonical commutation relations only.

  19. 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

  20. Functional network organizations of two contrasting temperament groups in dimensions of novelty seeking and harm avoidance.

    PubMed

    Kyeong, Sunghyon; Kim, Eunjoo; Park, Hae-Jeong; Hwang, Dong-Uk

    2014-08-01

    Novelty seeking (NS) and harm avoidance (HA) are two major dimensions of temperament in Cloninger?s neurobiological model of personality. Previous neurofunctional and biological studies on temperament dimensions of HA and NS suggested that the temperamental traits have significant correlations with cortical and subcortical brain regions. However, no study to date has investigated the functional network modular organization as a function of the temperament dimension. The temperament dimensions were originally proposed to be independent of one another. However, a meta-analysis based on 16 published articles found a significant negative correlation between HA and NS (Miettunen et al., 2008). Based on this negative correlation, the current study revealed the whole-brain connectivity modular architecture for two contrasting temperament groups. The k-means clustering algorithm, with the temperamental traits of HA and NS as an input, was applied to divide the 40 subjects into two temperament groups: 'high HA and low NS' versus 'low HA and high NS'. Using the graph theoretical framework, we found a functional segregation of whole brain network architectures derived from resting-state functional MRI. In the 'high HA and low NS' group, the regulatory brain regions, such as the prefrontal cortex (PFC), are clustered together with the limbic system. In the 'low HA and high NS' group, however, brain regions lying on the dopaminergic pathways, such as the PFC and basal ganglia, are partitioned together. These findings suggest that the neural basis of inhibited, passive, and inactive behaviors in the 'high HA and low NS' group was derived from the increased network associations between the PFC and limbic clusters. In addition, supporting evidence of topological differences between the two temperament groups was found by analyzing the functional connectivity density and gray matter volume, and by computing the relationships between the morphometry and function of the brain. PMID:24881884

  1. 14 CFR Section 11 - Functional Classification-Operating Expenses of Group II and Group III Air Carriers

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...Classification-Operating Expenses of Group II and Group III Air Carriers Section 11...Classification—Operating Expenses of Group II and Group III Air Carriers 5100Flying Operations...expenses incurred on the ground in protecting and controlling the...

  2. 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.

  3. 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

  4. Water Contact Angle Dependence with Hydroxyl Functional Groups on Silica Surfaces under CO2 Sequestration Conditions.

    PubMed

    Chen, Cong; Zhang, Ning; Li, Weizhong; Song, Yongchen

    2015-12-15

    Functional groups on silica surfaces under CO2 sequestration conditions are complex due to reactions among supercritical CO2, brine and silica. Molecular dynamics simulations have been performed to investigate the effects of hydroxyl functional groups on wettability. It has been found that wettability shows a strong dependence on functional groups on silica surfaces: silanol number density, space distribution, and deprotonation/protonation degree. For neutral silica surfaces with crystalline structure (Q(3), Q(3)/Q(4), Q(4)), as silanol number density decreases, contact angle increases from 33.5° to 146.7° at 10.5 MPa and 318 K. When Q(3) surface changes to an amorphous structure, water contact angle increases 20°. Water contact angle decreases about 12° when 9% of silanol groups on Q(3) surface are deprotonated. When the deprotonation degree increases to 50%, water contact angle decreases to 0. The dependence of wettability on silica surface functional groups was used to analyze contact angle measurement ambiguity in literature. The composition of silica surfaces is complicated under CO2 sequestration conditions, the results found in this study may help to better understand wettability of CO2/brine/silica system. PMID:26509282

  5. Effects of surface functional groups on the formation of nanoparticle-protein corona

    E-print Network

    Ramakrishna Podila; Ran Chen; Pu Chun Ke; Apparao M. Rao

    2012-09-25

    Herein, we examined the dependence of protein adsorption on the nanoparticle surface in the presence of functional groups. Our UV-visible spectrophotometry, transmission electron microscopy, infrared spectroscopy and dynamic light scattering measurements evidently suggested that the functional groups play an important role in the formation of nanoparticle-protein corona. We found that uncoated and surfactant-free silver nanoparticles derived from a laser ablation process promoted a maximum protein (bovine serum albumin) coating due to increased changes in entropy. On the other hand, BSA displayed a lower affinity for electrostatically stabilized nanoparticles due to the constrained entropy changes.

  6. Effects of surface functional groups on the formation of nanoparticle-protein corona

    E-print Network

    Podila, Ramakrishna; Ke, Pu Chun; Rao, Apparao M

    2012-01-01

    Herein, we examined the dependence of protein adsorption on the nanoparticle surface in the presence of functional groups. Our UV-visible spectrophotometry, transmission electron microscopy, infrared spectroscopy and dynamic light scattering measurements evidently suggested that the functional groups play an important role in the formation of nanoparticle-protein corona. We found that uncoated and surfactant-free silver nanoparticles derived from a laser ablation process promoted a maximum protein (bovine serum albumin) coating due to increased changes in entropy. On the other hand, BSA displayed a lower affinity for electrostatically stabilized nanoparticles due to the constrained entropy changes.

  7. Bi-invariant functions on the group of transformations leaving a measure quasi-invariant

    SciTech Connect

    Neretin, Yu A

    2014-09-30

    Let Gms be the group of transformations of a Lebesgue space leaving the measure quasi-invariant. Let Ams be a subgroup of it consisting of transformations preserving the measure. We describe canonical forms of double cosets of Gms by the subgroup Ams and show that all continuous Ams-bi-invariant functions on Gms are functionals of the distribution of a Radon-Nikodym derivative. Bibliography: 14 titles.

  8. Lower Uncarboxylated Osteocalcin Concentrations in Children with Prediabetes Is Associated with ?-Cell Function

    PubMed Central

    Bernard, Paul J.; Gower, Barbara A.; Gundberg, Caren M.; Wenger, Karl; Misra, Sudipta; Bassali, Reda W.; Davis, Catherine L.

    2011-01-01

    Context: Although animal studies suggest that it is the uncarboxylated rather than carboxylated form of osteocalcin that affects glucose homeostasis, the human data are scant and equivocal. Objective: This study investigated associations of uncarboxylated and carboxylated forms of osteocalcin with insulin sensitivity and ?-cell function in 140 overweight prepubertal children (43% female, 46% black, 84% obese) with normal glucose levels (n = 99) and prediabetes (n = 41). Methods: An oral glucose tolerance test was used to identify prediabetes and for measurement of insulin sensitivity (Matsuda index), ?-cell function [oral glucose tolerance test derived insulinogenic index and disposition index (DIOGTT)] and uncarboxylated and carboxylated forms of osteocalcin. Visceral adipose tissue (VAT) was assessed using magnetic resonance imaging. Results: After controlling for age, sex and race, lower uncarboxylated osteocalcin concentrations, Matsuda index, insulinogenic index, and DIOGTT and higher VAT levels were found in the prediabetes vs. normal-glucose group (all P < 0.03). Carboxylated osteocalcin levels were not different between groups. Multiple linear regression adjusting for age, sex, race, and VAT revealed that uncarboxylated osteocalcin was associated with insulinogenic index and DIOGTT (? = 0.34, 0.36, respectively, both P < 0.04) in the prediabetes group but not the normal-glucose group. In both the normal-glucose and prediabetes groups, carboxylated osteocalcin was associated with insulin sensitivity (? = 0.26, 0.47, respectively, both P < 0.02). Conclusions: These data suggest that the lower uncarboxylated osteocalcin concentrations found in children with prediabetes may be associated with ?-cell dysfunction. In addition, our findings between carboxylated osteocalcin and insulin sensitivity suggest that carboxylated osteocalcin plays a role in human glucose homeostasis. PMID:21508147

  9. Cellular uptake of functionalized carbon nanotubes is independent of functional group and cell type

    NASA Astrophysics Data System (ADS)

    Kostarelos, Kostas; Lacerda, Lara; Pastorin, Giorgia; Wu, Wei; Wieckowski, Sébastien; Luangsivilay, Jacqueline; Godefroy, Sylvie; Pantarotto, Davide; Briand, Jean-Paul; Muller, Sylviane; Prato, Maurizio; Bianco, Alberto

    2007-02-01

    The development of nanomaterials for biomedical and biotechnological applications is an area of research that holds great promise and intense interest, and carbon-based nanostructures in particular, such as carbon nanotubes (CNTs), are attracting an increasing level of attention. One of the key advantages that CNTs offer is the possibility of effectively crossing biological barriers, which would allow their use in the delivery of therapeutically active molecules. Our laboratories have been investigating the use of CNTs in biomedical applications, and in particular as nanovectors for therapeutic agent delivery. The interaction between cells and CNTs is a critical issue that will determine any future biological application of such structures. Here we show that various types of functionalized carbon nanotubes (f-CNTs) exhibit a capacity to be taken up by a wide range of cells and can intracellularly traffic through different cellular barriers.

  10. CCA-Secure Public Key Encryption without Group-Dependent Hash Functions

    NASA Astrophysics Data System (ADS)

    Cui, Yang; Hanaoka, Goichiro; Imai, Hideki

    So far, in almost all of the practical public key encryption schemes, hash functions which are dependent on underlying cyclic groups are necessary, e.g., H: {0, 1}* ? Zp where p is the order of the underlying cyclic group, and it could be required to construct a dedicated hash function for each public key. The motivation of this note is derived from the following two facts: 1). there is an important technical gap between hashing to a specific prime-order group and hashing to a certain length bit sequence, and this could cause a security hole; 2). surprisingly, to our best knowledge, there is no explicit induction that one could use the simple construction, instead of tailor-made hash functions. In this note, we investigate this issue and provide the first rigorous discussion that in many existing schemes, it is possible to replace such hash functions with a target collision resistant hash function H: {0, 1}* ? {0, 1}k, where k is the security parameter. We think that it is very useful and could drastically save the cost for the hash function implementation in many practical cryptographic schemes.

  11. One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres with enhanced photocatalytic performance

    SciTech Connect

    Qu, Lingling; Luo, Zhijun; Tang, Chao

    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.

  12. Experimental and theoretical studies on aqueous-phase reactivity of hydroxyl radicals with multiple carboxylated and hydroxylated benzene compounds.

    PubMed

    Minakata, Daisuke; Song, Weihua; Mezyk, Stephen P; Cooper, William J

    2015-05-01

    In this study, we shed light on the initial addition of hydroxyl radicals (HO?) to multiple carboxylated and hydroxylated benzene compounds in aqueous-phase advanced oxidation processes (AOPs). We analyze the experimentally measured transient spectra near neutral pH using quantum mechanical-based time-dependent density functional theory (TD-DFT). The ab initio DFT method was first used to find and optimize aqueous-phase transition state structures, then the TD-DFT was used to analyze molecular orbitals (MOs) of the optimized transition state structures to reveal the functional groups that are responsible for the individual absorption peaks. The initial addition of HO? to the benzene ring produced hydroxycyclohexadienyl radicals. Then, HO-adducts are generated from dimerization or disproportionation of hydroxycyclohexadienyl radicals and represent their transient spectral peaks at approximately 350 nm and 250 nm. As reaction proceeds, the HO-adducts are decreased depending on the subsequent reactions. These investigations into the experimental transient spectra coupled with the theoretical analysis using the TD-DFT enable us to visualize an initial transformation of organic compounds induced by the aqueous phase HO? oxidation. Moreover, the experimental reaction rate constants and the theoretically calculated aqueous phase free energies of activation provide quantitative insights into the addition of HO? to multiple carboxylated and hydroxylated benzene compounds. PMID:25868384

  13. Solvent induced rapid modulation of micro/nano structures of metal carboxylates coordination polymers: mechanism and morphology dependent magnetism

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Shen, Zhu-Rui; Li, Yue; Han, Song-De; Hu, Tong-Liang; Zhang, Da-Shuai; Bu, Xian-He; Ruan, Wen-Juan

    2014-08-01

    Rational modulation of morphology is very important for functional coordination polymers (CPs) micro/nanostructures, and new strategies are still desired to achieve this challenging target. Herein, organic solvents have been established as the capping agents for rapid modulating the growth of metal-carboxylates CPs in organic solvent/water mixtures at ambient conditions. Co-3,5-pyridinedicarboxylate (pydc) CPs was studied here as the example. During the reaction, the organic solvents exhibited three types of modulation effect: anisotropic growth, anisotropic growth/formation of new crystalline phase and the formation of new crystalline phase solely, which was due to the variation of their binding ability with metal cations. The following study revealed that the binding ability was critically affected by their functional groups and molecular size. Moreover, their modulation effect could be finely tuned by changing volume ratios of solvent mixtures. Furthermore, they could be applied for modulating other metal-carboxylates CPs: Co-1,3,5-benzenetricarboxylic (BTC), Zn-pydc and Eu-pydc etc. Additionally, the as-prepared Co-pydc CPs showed a fascinating morphology-dependent antiferromagnetic behavior.

  14. Solvent induced rapid modulation of micro/nano structures of metal carboxylates coordination polymers: mechanism and morphology dependent magnetism

    PubMed Central

    Liu, Kun; Shen, Zhu-Rui; Li, Yue; Han, Song-De; Hu, Tong-Liang; Zhang, Da-Shuai; Bu, Xian-He; Ruan, Wen-Juan

    2014-01-01

    Rational modulation of morphology is very important for functional coordination polymers (CPs) micro/nanostructures, and new strategies are still desired to achieve this challenging target. Herein, organic solvents have been established as the capping agents for rapid modulating the growth of metal-carboxylates CPs in organic solvent/water mixtures at ambient conditions. Co-3,5-pyridinedicarboxylate (pydc) CPs was studied here as the example. During the reaction, the organic solvents exhibited three types of modulation effect: anisotropic growth, anisotropic growth/formation of new crystalline phase and the formation of new crystalline phase solely, which was due to the variation of their binding ability with metal cations. The following study revealed that the binding ability was critically affected by their functional groups and molecular size. Moreover, their modulation effect could be finely tuned by changing volume ratios of solvent mixtures. Furthermore, they could be applied for modulating other metal-carboxylates CPs: Co-1,3,5-benzenetricarboxylic (BTC), Zn-pydc and Eu-pydc etc. Additionally, the as-prepared Co-pydc CPs showed a fascinating morphology-dependent antiferromagnetic behavior. PMID:25113225

  15. Asymmetric Fluorolactonization with a Bifunctional Hydroxyl Carboxylate Catalyst.

    PubMed

    Egami, Hiromichi; Asada, Junshi; Sato, Kentaro; Hashizume, Daisuke; Kawato, Yuji; Hamashima, Yoshitaka

    2015-08-19

    We report the first successful example of a highly enantioselective fluorolactonization with an electrophilic fluorinating reagent, Selectfluor(®), in the presence of a novel bifunctional organocatalyst. The catalyst design includes a carboxylate anion functioning as a phase-transfer agent and a benzyl alcohol unit to capture the substrate through hydrogen bonding. Fluorinated isobenzofuranones were obtained in good yields with up to 94% ee (97:3 er). On the basis of mechanistic studies, we propose a unique reaction mechanism with potential for further applications. PMID:26251311

  16. Figure 1: Functionalization of TiO2 by anhydrous chemical vapor deposition of trifunctional siloxane adsorbates.

    E-print Network

    and electronic structure calculations based on density functional theory (DFT). We predict that trifunctional covalent bonds with the TiO2 surface. The alkoxysiloxane groups are robust under heat and water treatment with surface hydroxyl groups (e.g., alcohols,9 diols,10,11 carboxylic acids,10,12,13 siloxanes,14 boronic acids

  17. Bis(3-amino­pyrazine-2-carboxyl­ato-?2 N 1,O)di­aqua­nickel(II) dihydrate

    PubMed Central

    Bouchene, Rafika; Khadri, Amina; Bouacida, Sofiane; Berrah, Fadila; Merazig, Hocine

    2013-01-01

    In the title compound, [Ni(C5H4N3O2)2(H2O)2]·2H2O, the NiII ion lies on an inversion center and is coordinated in an slightly distorted octa­hedral environment by two N,O-chelating 3-amino­pyrazine-2-carboxyl­ate (APZC) ligands in the equatorial plane and two trans-axial aqua ligands. In the crystal, O—H?O, N—H?O and O—H?N hydrogen bonds involving the solvent water mol­ecules, aqua and APZC ligands form layers parallel to (010). These layers are linked further via O—H?O, N—H?O and C—H?O hydrogen bonds involving the axial aqua ligands, amino groups and the carboxyl­ate groups of the APZC ligands, forming a three-dimensional network. PMID:23794977

  18. 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

  19. Investigation of hydrogen-bonded compounds by high-resolution NMR spectroscopy of solids. Part 2. Symmetry and strength of O?H … O bonds in some hydrogen-bonded compounds containing carboxylic groups determined by 1H and 13C chemical shifts

    NASA Astrophysics Data System (ADS)

    Schröter, B.; Rosenberger, H.; Hadz?i, D.

    1983-01-01

    1H and 13C high-resolution solid-state NMR using magic angle sample spinning is applied to determine the strength and symmetry of the O?H … O bonds in the hydrogen-bonded compounds potassium hydrogen malonate (KHM), succinate (KHS) and phthalate (KHPh), ammonium hydrogen glutarate (AHG) and its deuterated analogue (ADG), the cis-trans isomers ammonium hydrogen maleate (AHM) and fumarate (AHF) and maleic and fumaric acids. A marked loss of symmetry of the H-bond is observed in ADG relative to AHG. The R O…O distances and symmetry are estimated for AHM and AHF. In general, the 1H chemical-shift values, overline?, yield information on the strength of the H-bonds while conclusions concerning the symmetry of the H-bonding may be deduced from the 13C overline? values which are sensitive to crystallographic and molecular symmetry. These key signals in the case of strongly H-bonded carboxylic groups are sufficiently distinct from other signals as to yield reliable information on the type of H-bond. This information can now be obtained from NMR investigations of polycrystalline samples at room temperature.

  20. 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.

  1. IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION

    EPA Science Inventory

    The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

  2. Urinary Cortisol Circadian Rhythm in a Group of High-Functioning Children with Autism.

    ERIC Educational Resources Information Center

    Richdale, Amanda L.; Prior, Margot R.

    1992-01-01

    This study found no evidence for abnormal temporal placement of the basal urinary cortisol circadian rhythm in a group of 18 high-functioning children (ages 4-14) with autism. There was a tendency toward cortisol hypersecretion during the day, predominantly in autistic children who were integrated into the normal school system. (Author/JDD)

  3. Correlation functions of just renormalizable tensorial group field theory: The melonic

    E-print Network

    Wulkenhaar, Raimar

    Correlation functions of just renormalizable tensorial group field theory: The melonic. The leading contributions result from so-called melonic graphs which are dual to the D-sphere. This is a note about the Schwinger-Dyson equations of the tensorial 4 5-model (with propagator 1/p2) and their melonic

  4. 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 ...

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

    E-print Network

    International Association for Cryptologic Research (IACR)

    Constructing Vectorial Boolean Functions with High Algebraic Immunity Based on Group Decomposition a class of vectorial Boolean func- tions over F2n with high algebraic immunity based on the decomposition with high algebraic immunity. Moreover, when n is even, we provide two special classes of vectorial Boolean

  6. 14 CFR 10 - Functional Classification-Operating Expenses of Group I Air Carriers

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Functional Classification-Operating Expenses of Group I Air Carriers Section 10 Section Section 10 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR...

  7. 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…

  8. Impacts of chronic nitrogen additions vary seasonally and by microbial functional group in tundra soils

    E-print Network

    Colorado at Boulder, University of

    Impacts of chronic nitrogen additions vary seasonally and by microbial functional group in tundra, Tundra soils Abstract. Previous studies have shown that fertilization with nitrogen depresses overall nitrogen addi- tions in alpine tundra soils. We measured soil enzyme activities, mineralization kinetics

  9. 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…

  10. L-FUNCTIONS FOR THE p-ADIC GROUP GSp(4) By RAMIN TAKLOO-BIGHASH

    E-print Network

    Takloo-Bighash, Ramin

    ) over a nonarchemidean local field. 1. Introduction. In this paper we will study the p-adic theory groups of arbitrary odd degree. The local theory of Soudry's integrals appear in his Memoire paper [27], the main idea is to determine the germ expansions of Whittaker functions when restricted to the maximal

  11. Neuropsychological Functioning in Specific Learning Disorders--Reading, Writing and Mixed Groups

    ERIC Educational Resources Information Center

    Kohli, Adarsh; Kaur, Manreet; Mohanty, Manju; Malhotra, Savita

    2006-01-01

    Aim: The study compared the pattern of deficits, intelligence and neuropsychological functioning in subcategories of learning disorders. Methods: Forty-six children (16 with reading disorders, 11 with writing disorders and 19 with both reading and writing disorders--mixed group) in the age range of 7-14 years were assessed using the NIMHANS Index…

  12. Attraction to a Group as a Function of Attitude Similarity and Geographic Distance.

    ERIC Educational Resources Information Center

    Davis, John M.

    1984-01-01

    Investigated attraction toward a group as a function of attitude similarity and perceived geographic distance in students (N=60). Results showed that effects of attitude similarity were strongly significant and that distance had no signficant effect on attraction and limited effect on evaluations. (LLL)

  13. Group Social Skills Instruction for Adolescents with High-Functioning Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    White, Susan W.; Koenig, Kathleen; Scahill, Lawrence

    2010-01-01

    Given the increased recognition of autism spectrum disorders (ASD) and the chronic and pervasive nature of associated deficits, there is a pressing need for effective treatments. The feasibility and preliminary efficacy of a structured, group social skills training program for high-functioning youth with ASD was examined in this study. Fifteen…

  14. 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…

  15. In situ and ex situ spectroscopic monitoring of biochar's surface functional groups

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A number of studies described the higher heating temperature (HHT) as the primary pyrolysis parameter dictating the biochar property: surface functional group and fixed carbon contents, O/C, H/C ratios, and Brunauer-Emmett-Teller (BET) surface area. In order to produce desirable biochar properties ...

  16. 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...

  17. Chemkarta: A Card Game for Teaching Functional Groups in Undergraduate Organic Chemistry

    ERIC Educational Resources Information Center

    Knudtson, Christopher A.

    2015-01-01

    Students in undergraduate organic chemistry courses are frequently overwhelmed by the volume and complexity of information they are expected to learn. To aid in students' learning of organic functional groups, a novel card game "ChemKarta" is reported that can serve as a useful alternative to flashcards. This pedagogy is a simple…

  18. Energies of the adsorption of functional groups to calcium carbonate polymorphs: the importance of -OH and -COOH groups.

    PubMed

    Okhrimenko, D V; Nissenbaum, J; Andersson, M P; Olsson, M H M; Stipp, S L S

    2013-09-01

    The adsorption behavior of calcium carbonate is an important factor in many processes in nature, industry, and biological systems. We determined and compared the adsorption energies for a series of small molecules of different sizes and polarities (i.e., water, several alcohols, and acetic acid) on three synthetic CaCO3 polymorphs (calcite, aragonite, and vaterite). We measured isosteric heats of adsorption from vapor adsorption isotherms for 273 < T < 293 K, and we used XRD and SEM to confirm that samples did not change phase during the experiments. Density functional calculations and molecular dynamics simulations complemented the experimental results and aided interpretation. Alcohols with molecular mass greater than that of methanol bind more strongly to the calcium carbonate polymorphs than water and acetic acid. The adsorption energies for the alcohols are typical of chemisorption and indicate alcohol displacement of water from calcium carbonate surfaces. This explains why organisms favor biomolecules that contain alcohol functional groups (-OH) to control which polymorph they use, the crystal face and orientation, and the particle shape and size in biomineralization processes. This new insight is also very useful in understanding organic molecule adsorption mechanisms in soils, sediments, and rocks, which is important for predicting the behavior of mineral-fluid interactions when the challenge is to remediate contaminated groundwater aquifers or to produce oil and gas from reservoirs. PMID:23919655

  19. The template synthesis of mesoporous silicas with the thiourea functional group

    NASA Astrophysics Data System (ADS)

    Gona, E. I.; Zub, Yu. L.; Yaroshenko, N. A.; Goworek, Ya.

    2007-03-01

    Mono- and bifunctional mesoporous silicas containing the thiourea group ?Si(CH2)3NHC(S)NHC2H5 or thiourea and various nitrogen-containing groups [?Si(CH2)3NH2, ?Si(CH2)3NH(CH2)2NH2, or {?Si(CH2)3}2NH], respectively, in the surface layer were prepared by template syntheses with cetylpyridinium chloride as a template. The synthesized samples had well-developed porous structures ( S sp = 750 1150 m2/g, V c = 0.51 0.72 cm3/g, and d = 2.4 3.5 nm) and high functional group contents (1.0 2.0 mmol/g). Hydrothermal treatment of the mesophases in a mother liquor at 80°C (24 h) improved the structure-adsorption characteristics of the functionalized mesoporous silicas.

  20. 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.

  1. A SPARSE REDUCED RANK FRAMEWORK FOR GROUP ANALYSIS OF FUNCTIONAL NEUROIMAGING DATA

    PubMed Central

    Ahn, Mihye; Shen, Haipeng; Lin, Weili; Zhu, Hongtu

    2015-01-01

    In spatial-temporal neuroimaging studies, there is an evolving literature on the analysis of functional imaging data in order to learn the intrinsic functional connectivity patterns among different brain regions. However, there are only few efficient approaches for integrating functional connectivity pattern across subjects, while accounting for spatial-temporal functional variation across multiple groups of subjects. The objective of this paper is to develop a new sparse reduced rank (SRR) modeling framework for carrying out functional connectivity analysis across multiple groups of subjects in the frequency domain. Our new framework not only can extract both frequency and spatial factors across subjects, but also imposes sparse constraints on the frequency factors. It thus leads to the identification of important frequencies with high power spectra. In addition, we propose two novel adaptive criteria for automatic selection of sparsity level and model rank. Using simulated data, we demonstrate that SRR outperforms several existing methods. Finally, we apply SRR to detect group differences between controls and two subtypes of attention deficit hyperactivity disorder (ADHD) patients, through analyzing the ADHD-200 data. PMID:26405427

  2. The two-point correlation function for groups of galaxies in the Center for Astrophysics redshift survey

    NASA Technical Reports Server (NTRS)

    Ramella, Massimo; Geller, Margaret J.; Huchra, John P.

    1990-01-01

    The large-scale distribution of groups of galaxies selected from complete slices of the CfA redshift survey extension is examined. The survey is used to reexamine the contribution of group members to the galaxy correlation function. The relationship between the correlation function for groups and those calculated for rich clusters is discussed, and the results for groups are examined as an extension of the relation between correlation function amplitude and richness. The group correlation function indicates that groups and individual galaxies are equivalent tracers of the large-scale matter distribution. The distribution of group centers is equivalent to random sampling of the galaxy distribution. The amplitude of the correlation function for groups is consistent with an extrapolation of the amplitude-richness relation for clusters. The amplitude scaled by the mean intersystem separation is also consistent with results for richer clusters.

  3. 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

  4. 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.

  5. Zooplankton functional groups on the continental shelf of the yellow sea

    NASA Astrophysics Data System (ADS)

    Sun, Song; Huo, Yuanzi; Yang, Bo

    2010-06-01

    Zooplankton plays a vital role in marine ecosystems. Variations in the zooplankton species composition, biomass, and secondary production will change the structure and function of the ecosystem. How to describe this process and make it easier to be modeled in the Yellow Sea ecosystem is the main purpose of this paper. The zooplankton functional groups approach, which is considered a good method of linking the structure of food webs and the energy flow in the ecosystems, is used to describe the main contributors of secondary produciton of the Yellow Sea ecosystem. The zooplankton can be classified into six functional groups: giant crustaceans, large copepods, small copepods, chaetognaths, medusae, and salps. The giant crustaceans, large copepods, and small copepods groups, which are the main food resources for fish, are defined depending on the size spectrum. Medusae and chaetognaths are the two gelatinous carnivorous groups, which compete with fish for food. The salps group, acting as passive filter-feeders, competes with other species feeding on phytoplankton, but their energy could not be efficiently transferred to higher trophic levels. From the viewpoint of biomass, which is the basis of the food web, and feeding activities, the contributions of each functional group to the ecosystem were evaluated; the seasonal variations, geographical distribution patterns, and species composition of each functional group were analyzed. The average zooplankton biomass was 2.1 g dry wt m -2 in spring, to which the giant crustaceans, large copepods, and small copepods contributed 19, 44, and 26%, respectively. High biomasses of the large copepods and small copepods were distributed at the coastal waters, while the giant crustaceans were mainly located at offshore area. In summer, the mean biomass was 3.1 g dry wt m -2, which was mostly contributed by the giant crustaceans (73%), and high biomasses of the giant crustaceans, large copepods, and small copepods were all distributed in the central part of the Yellow Sea. During autumn, the mean biomass was 1.8 g dry wt m -2, which was similarly constituted by the giant crustaceans, large copepods, and small copepods (36, 33, and 23%, respectively), and high biomasses of the giant crustaceans and large copepods occurred in the central part of the Yellow Sea, while the small copepods were mainly located at offshore stations. The giant crustaceans and large copepods dominated the zooplankton biomass (2.9 g dry wt m -2) in winter, contributing respectively 57 and 27%, and they, as well as the small copepods, were all mainly located in the central part of the Yellow Sea. The chaetognaths group was mainly located in the northern part of the Yellow Sea during all seasons, but contributed less to the biomass compared with the other groups. The medusae and salps groups were distributed unevenly, with sporadic dynamics, mainly along the coastline and at the northern part of the Yellow Sea. No more than 10 species belonging to the respective functional groups dominated the zooplankton biomass and controlled the dynamics of the zooplankton community. The clear picture of the seasonal and spatial variations of each zooplankton functional group makes the complicated Yellow Sea ecosystem easier to be understood and modeled.

  6. Tumor-suppressor effects of chemical functional groups in an in vitro co-culture system

    NASA Astrophysics Data System (ADS)

    Xu, Su-Ju; Cui, Fu-Zhai; Kong, Xiang-Dong

    2014-06-01

    Liver normal cells and cancer cells co-cultured on surfaces modified by different chemical functional groups, including mercapto (-SH), hydroxyl (-OH) and methyl (-CH3) groups. The results showed that different cells exhibited changes in response to different surfaces. Normal cells on -SH surface exhibited the smallest contact area with mostly rounded morphology, which led to the death of cancer cells, while cancer cells could not grow on -CH3 groups, which also died. In the co-culture system, the -CH3 group exhibited its unique effect that could trigger the death of cancer cells and had no effects on normal cells. Our findings provide useful information on strategies for the design of efficient and safe regenerative medicine materials.

  7. 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.

  8. Cloud Forming Potential of Aminium Carboxylate Aerosols

    NASA Astrophysics Data System (ADS)

    Gomez Hernandez, M. E.; McKeown, M.; Taylor, N.; Collins, D. R.; Lavi, A.; Rudich, Y.; Zhang, R.

    2014-12-01

    Atmospheric aerosols affect visibility, air quality, human health, climate, and in particular the aerosol direct and indirect forcings represent the largest uncertainty in climate projections. In this paper, we present laboratory measurements of the hygroscopic growth factors (HGf) and cloud condensation nuclei (CCN) activity of a series of aminium carboxylate salt aerosols, utilizing a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) coupled to a Condensation Particle Counter (CPC) and a CCN counter. HGf measurements were conducted for size-selected aerosols with diameters ranging from 46 nm to 151 nm and at relative humidity (RH%) values ranging from 10 to 90%. In addition, we have calculated the CCN activation diameters for the aminium carboxylate aerosols and derived the hygroscopicity parameter (k or kappa) values for all species using three methods, i.e., the mixing rule approximation, HGf, and CCN results. Our results show that variations in the ratio of acid to base directly affect the activation diameter, HGf, and (k) values of the aminium carboxylate aerosols. Atmospheric implications of the variations in the chemical composition of aminium carboxylate aerosols on their cloud forming potential will be discussed.

  9. 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.

  10. 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

  11. Building thiol and metal-thiolate functions into coordination nets: Clues from a simple molecule

    NASA Astrophysics Data System (ADS)

    He, Jun; Yang, Chen; Xu, Zhengtao; Zeller, Matthias; Hunter, Allen D.; Lin, Jianhua

    2009-07-01

    The simple and easy-to-prepare bifunctional molecule 2,5-dimercapto-1,4-benzenedicarboxylic acid (H 4DMBD) interacts with the increasingly harder metal ions of Cu +, Pb 2+ and Eu 3+ to form the coordination networks of Cu 6(DMBD) 3(en) 4(Hen) 6 ( 1), Pb 2(DMBD)(en) 2 ( 2) and Eu 2(H 2DMBD) 3(DEF) 4 ( 3), where the carboxyl and thiol groups bind with distinct preference to the hard and soft metal ions, respectively. Notably, 1 features uncoordinated carboxylate groups and Cu 3 cluster units integrated via the thiolate groups into an extended network with significant interaction between the metal centers and the organic molecules; 2 features a 2D coordination net based on the mercapto and carboxylic groups all bonded to the Pb 2+ ions; 3 features free-standing thiol groups inside the channels of a metal-carboxylate-based network. This study illustrates the rich solid state structural features and potential functions offered by the carboxyl-thiol combination.

  12. 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...

  13. The luminosity function of the fossil group RX J1552.2+2013

    E-print Network

    De Oliveira, C L M; Sodré, L; Oliveira, Claudia L. Mendes de

    2005-01-01

    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, it is at a mean redshift of 0.136 and has a velocity dispersion of 623 km/s (or 797 km/s if four emission lines 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 ~1/3 R_vir), in the range -23.5< M_i'<-17.5, is well fitted by a Schechter function with M*i'=-21.3 +/- 0.4 and alpha = -0.6 +/- 0.3 or a Gaussian function centered on M_i'= -20.0 +/- 0.4 and with sigma=1.29 +/- 0.24 i' mag. (H_0 = 70 km/s Mpc, Omega_M=0.3, Omega_Lambda=0.7. The luminosity function obtained from a photometric survey in g', r', i'-bands (and statistical background correction) confirms the spectroscopically determined results. There is a significant dip in the luminosity function at M_r'=-18 mag, as also observed for other clusters. RX~J1552.2+2013 is a rich, str...

  14. Transcriptional regulators form diverse groups with context-dependent regulatory functions.

    PubMed

    Stampfel, Gerald; Kazmar, Tomáš; Frank, Olga; Wienerroither, Sebastian; Reiter, Franziska; Stark, Alexander

    2015-12-01

    One of the most important questions in biology is how transcription factors (TFs) and cofactors control enhancer function and thus gene expression. Enhancer activation usually requires combinations of several TFs, indicating that TFs function synergistically and combinatorially. However, while TF binding has been extensively studied, little is known about how combinations of TFs and cofactors control enhancer function once they are bound. It is typically unclear which TFs participate in combinatorial enhancer activation, whether different TFs form functionally distinct groups, or if certain TFs might substitute for each other in defined enhancer contexts. Here we assess the potential regulatory contributions of TFs and cofactors to combinatorial enhancer control with enhancer complementation assays. We recruited GAL4-DNA-binding-domain fusions of 812 Drosophila TFs and cofactors to 24 enhancer contexts and measured enhancer activities by 82,752 luciferase assays in S2 cells. Most factors were functional in at least one context, yet their contributions differed between contexts and varied from repression to activation (up to 289-fold) for individual factors. Based on functional similarities across contexts, we define 15 groups of TFs that differ in developmental functions and protein sequence features. Similar TFs can substitute for each other, enabling enhancer re-engineering by exchanging TF motifs, and TF-cofactor pairs cooperate during enhancer control and interact physically. Overall, we show that activators and repressors can have diverse regulatory functions that typically depend on the enhancer context. The systematic functional characterization of TFs and cofactors should further our understanding of combinatorial enhancer control and gene regulation. PMID:26550828

  15. GPU-based parallel group ICA for functional magnetic resonance data.

    PubMed

    Jing, Yanshan; Zeng, Weiming; Wang, Nizhuan; Ren, Tianlong; Shi, Yingchao; Yin, Jun; Xu, Qi

    2015-04-01

    The goal of our study is to develop a fast parallel implementation of group independent component analysis (ICA) for functional magnetic resonance imaging (fMRI) data using graphics processing units (GPU). Though ICA has become a standard method to identify brain functional connectivity of the fMRI data, it is computationally intensive, especially has a huge cost for the group data analysis. GPU with higher parallel computation power and lower cost are used for general purpose computing, which could contribute to fMRI data analysis significantly. In this study, a parallel group ICA (PGICA) on GPU, mainly consisting of GPU-based PCA using SVD and Infomax-ICA, is presented. In comparison to the serial group ICA, the proposed method demonstrated both significant speedup with 6-11 times and comparable accuracy of functional networks in our experiments. This proposed method is expected to perform the real-time post-processing for fMRI data analysis. PMID:25704870

  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. Cooperation of phosphates and carboxylates controls calcium oxalate crystallization in ultrafiltered urine.

    PubMed

    Grohe, Bernd; Chan, Brian P H; Sørensen, Esben S; Lajoie, Gilles; Goldberg, Harvey A; Hunter, Graeme K

    2011-10-01

    Osteopontin (OPN) is one of a group of proteins found in urine that are believed to limit the formation of kidney stones. In the present study, we investigate the roles of phosphate and carboxylate groups in the OPN-mediated modulation of calcium oxalate (CaOx), the principal mineral phase found in kidney stones. To this end, crystallization was induced by addition of CaOx solution to ultrafiltered human urine containing either human kidney OPN (kOPN; 7 consecutive carboxylates, 8 phosphates) or synthesized peptides corresponding to residues 65-80 (pSHDHMDDDDDDDDDGD; pOPAR) or 220-235 (pSHEpSTEQSDAIDpSAEK; P3) of rat bone OPN. Sequence 65-80 was also synthesized without the phosphate group (OPAR). Effects on calcium oxalate monohydrate (COM) and dihydrate (COD) formation were studied by scanning electron microscopy. We found that controls form large, partly intergrown COM platelets; COD was never observed. Adding any of the polyelectrolytes was sufficient to prevent intergrowth of COM platelets entirely, inhibiting formation of these platelets strongly, and inducing formation of the COD phase. Strongest effects on COM formation were found for pOPAR and OPAR followed by kOPN and then P3, showing that acidity and hydrophilicity are crucial in polyelectrolyte-affected COM crystallization. At higher concentrations, OPAR also inhibited COD formation, while P3, kOPN and, in particular, pOPAR promoted COD, a difference explainable by the variations of carboxylate and phosphate groups present in the molecules. Thus, we conclude that carboxylate groups play a primary role in inhibiting COM formation, but phosphate and carboxylate groups are both important in initiating and promoting COD formation. PMID:21234554

  18. Carboxyl-Assisted Synthesis of Nitrogen-Doped Graphene Sheets for Supercapacitor Applications

    NASA Astrophysics Data System (ADS)

    Xie, Bingqiao; Chen, Ying; Yu, Mengying; Shen, Xiang; Lei, Hanwu; Xie, Ting; Zhang, Yong; Wu, Yucheng

    2015-08-01

    The high ratio of pyridinic and pyridone N-doped graphene sheets have been synthesized by functionalizing graphene oxide (GO) with different oxygen groups on its surface. The typical N-doped graphene was determined to be ~3-5 layers by transmission electron microscopy (TEM) and atomic force microscopy (AFM), and the nitrogen content was measured as 6.8-8 at. % by X-ray photoelectron spectroscopy (XPS). The structure of the N-doped graphene with different surface functional groups was characterized by Raman spectroscopy. The research result indicates that the carboxylation of GO is the key factor to obtain pyridinic and pyridone N types during the N atom doping process. Compared to general N-doped graphene, the electrochemical test shows that specific capacitance of the GO-OOH-N sample reaches up to 217 F/g at a discharge current density 1 A/g and stable cycling performance (keep 88.8 % specific capacitance after 500 cycles at the same discharge current density) when applied to the supercapacitor electrode materials.

  19. Carboxyl-Assisted Synthesis of Nitrogen-Doped Graphene Sheets for Supercapacitor Applications.

    PubMed

    Xie, Bingqiao; Chen, Ying; Yu, Mengying; Shen, Xiang; Lei, Hanwu; Xie, Ting; Zhang, Yong; Wu, Yucheng

    2015-12-01

    The high ratio of pyridinic and pyridone N-doped graphene sheets have been synthesized by functionalizing graphene oxide (GO) with different oxygen groups on its surface. The typical N-doped graphene was determined to be ~3-5 layers by transmission electron microscopy (TEM) and atomic force microscopy (AFM), and the nitrogen content was measured as 6.8-8 at. % by X-ray photoelectron spectroscopy (XPS). The structure of the N-doped graphene with different surface functional groups was characterized by Raman spectroscopy. The research result indicates that the carboxylation of GO is the key factor to obtain pyridinic and pyridone N types during the N atom doping process. Compared to general N-doped graphene, the electrochemical test shows that specific capacitance of the GO-OOH-N sample reaches up to 217 F/g at a discharge current density 1 A/g and stable cycling performance (keep 88.8 % specific capacitance after 500 cycles at the same discharge current density) when applied to the supercapacitor electrode materials. PMID:26290040

  20. 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].

  1. TiO2/carboxylate-rich porous carbon: A highly efficient visible-light-driven photocatalyst based on the ligand-to-metal charge transfer (LMCT) process

    NASA Astrophysics Data System (ADS)

    Qu, Lingling; Huang, Dongliang; Shi, Hefei; Gu, Mengbin; Li, Jilei; Dong, Fei; Luo, Zhijun

    2015-10-01

    A novel visible-light-driven photocatalyst based on TiO2/carboxylate-rich porous carbon composite (TiO2/CRPC) was successfully synthesized by low temperature carbonization process in air. Sodium gluconate plays a crucial role in the formation of TiO2/CRPC. Different functional groups of sodium gluconate play synergetic roles in the formation of TiO2/CRPC. XRD and Raman spectra studies indicated that there are two different TiO2 crystalline phases existing in TiO2/CRPC, which are anatase and brookite, and the CRPC is amorphous. Via FT-IR and XPS spectra investigations, it was demonstrated that carboxylate group, the ligand-to-metal charge transfer (LMCT) forming functional group, was solidified into the CRPC and form the LMCT complex on TiO2 surface through the fabrication of TiO2/CRPC. Compared with the pure TiO2, TiO2/CRPC exhibit enhanced absorption in the UV and visible light region around 260-600 nm. The strong absorption in the visible light region gives TiO2/CRPC advantages over pure TiO2 for the degradation of organic pollutants. TiO2/CRPC can activate O2 in air under mild conditions and exhibit excellent visible-light-driven photocatalytic activities. However, TiO2/C composite obtained by using glucose instead of sodium gluconate exhibits poor photocatalytic activity, which demonstrated that carboxylate-TiO2 complexes are responsible for the prominent photocatalytic properties of TiO2/CRPC under visible light irradiation.

  2. 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

  3. First-principles study of the effect of functional groups on polyaniline backbone.

    PubMed

    Chen, X P; Jiang, J K; Liang, Q H; Yang, N; Ye, H Y; Cai, M; Shen, L; Yang, D G; Ren, T L

    2015-01-01

    We present a first-principles density functional theory study focused on how the chemical and electronic properties of polyaniline are adjusted by introducing suitable substituents on a polymer backbone. Analyses of the obtained energy barriers, reaction energies and minimum energy paths indicate that the chemical reactivity of the polyaniline derivatives is significantly enhanced by protonic acid doping of the substituted materials. Further study of the density of states at the Fermi level, band gap, HOMO and LUMO shows that both the unprotonated and protonated states of these polyanilines are altered to different degrees depending on the functional group. We also note that changes in both the chemical and electronic properties are very sensitive to the polarity and size of the functional group. It is worth noting that these changes do not substantially alter the inherent chemical and electronic properties of polyaniline. Our results demonstrate that introducing different functional groups on a polymer backbone is an effective approach to obtain tailored conductive polymers with desirable properties while retaining their intrinsic properties, such as conductivity. PMID:26584671

  4. Nanomechanical characterization of chemical interaction between gold nanoparticles and chemical functional groups

    PubMed Central

    2012-01-01

    We report on how to quantify the binding affinity between a nanoparticle and chemical functional group using various experimental methods such as cantilever assay, PeakForce quantitative nanomechanical property mapping, and lateral force microscopy. For the immobilization of Au nanoparticles (AuNPs) onto a microscale silicon substrate, we have considered two different chemical functional molecules of amine and catecholamine (here, dopamine was used). It is found that catecholamine-modified surface is more effective for the functionalization of AuNPs onto the surface than the amine-modified surface, which has been shown from our various experiments. The dimensionless parameter (i.e., ratio of binding affinity) introduced in this work from such experiments is useful in quantitatively depicting such binding affinity, indicating that the binding affinity and stability between AuNPs and catecholamine is approximately 1.5 times stronger than that between amine and AuNPs. Our study sheds light on the experiment-based quantitative characterization of the binding affinity between nanomaterial and chemical groups, which will eventually provide an insight into how to effectively design the functional material using chemical groups. PMID:23113991

  5. First-principles study of the effect of functional groups on polyaniline backbone

    PubMed Central

    Chen, X. P.; Jiang, J. K.; Liang, Q. H.; Yang, N.; Ye, H. Y.; Cai, M.; Shen, L.; Yang, D. G.; Ren, T. L.

    2015-01-01

    We present a first-principles density functional theory study focused on how the chemical and electronic properties of polyaniline are adjusted by introducing suitable substituents on a polymer backbone. Analyses of the obtained energy barriers, reaction energies and minimum energy paths indicate that the chemical reactivity of the polyaniline derivatives is significantly enhanced by protonic acid doping of the substituted materials. Further study of the density of states at the Fermi level, band gap, HOMO and LUMO shows that both the unprotonated and protonated states of these polyanilines are altered to different degrees depending on the functional group. We also note that changes in both the chemical and electronic properties are very sensitive to the polarity and size of the functional group. It is worth noting that these changes do not substantially alter the inherent chemical and electronic properties of polyaniline. Our results demonstrate that introducing different functional groups on a polymer backbone is an effective approach to obtain tailored conductive polymers with desirable properties while retaining their intrinsic properties, such as conductivity. PMID:26584671

  6. The functionalization and characterization of multi-walled carbon nanotubes (MWCNTs)

    NASA Astrophysics Data System (ADS)

    Abdullah, Mohd Pauzi; Zulkepli, Siti Aminah

    2015-09-01

    Functionalization is the process of introducing chemical functional groups on the surface of the material. In this study, a multi-walled carbon nanotube (MWCNTs) was functionalized by oxidation treatment using concentrated nitric acid. The functionalized and pristine MWCNTs were analyzed by using Fourier Transform Infrared Spectroscopy (FT-IR) and X-Ray Diffraction (XRD). The XRD patterns exhibit the graphitic properties for all samples. Besides, the XRD results also demonstrate that the percent of crystallinity of MWCNTs increases as the duration of acid treatment increases. The percent of crystallinity increases from 66% to 80% when the pristine MWCNT treated for 12 hours with additional 12 hours reflux process with nitric acid. The IR spectrum for the 12 hours-treated MWCNTs shows the formation of carboxyl functional group. Additional 12 hours reflux process with nitric acid on the 12 hours-treated MWCNTs have shown the loss of existing carboxyl group and only hydroxyl group formed.

  7. Analysis of carbonaceous biomarkers with the Mars Organic Analyzer microchip capillary electrophoresis system: carboxylic acids.

    PubMed

    Stockton, Amanda M; Tjin, Caroline Chandra; Chiesl, Thomas N; Mathies, Richard A

    2011-01-01

    The oxidizing surface chemistry on Mars argues that any comprehensive search for organic compounds indicative of life requires methods to analyze higher oxidation states of carbon with very low limits of detection. To address this goal, microchip capillary electrophoresis (?CE) methods were developed for analysis of carboxylic acids with the Mars Organic Analyzer (MOA). Fluorescent derivatization was achieved by activation with the water soluble 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) followed by reaction with Cascade Blue hydrazide in 30 mM borate, pH 3. A standard containing 12 carboxylic acids found in terrestrial life was successfully labeled and separated in 30 mM borate at pH 9.5, 20 °C by using the MOA CE system. Limits of detection were 5-10 nM for aliphatic monoacids, 20 nM for malic acid (diacid), and 230 nM for citric acid (triacid). Polyacid benzene derivatives containing 2, 3, 4, and 6 carboxyl groups were also analyzed. In particular, mellitic acid was successfully labeled and analyzed with a limit of detection of 300 nM (5 ppb). Analyses of carboxylic acids sampled from a lava tube cave and a hydrothermal area demonstrated the versatility and robustness of our method. This work establishes that the MOA can be used for sensitive analyses of a wide range of carboxylic acids in the search for extraterrestrial organic molecules. PMID:21790324

  8. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  9. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  10. 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...

  11. Production of carboxylic acid and salt co-products

    SciTech Connect

    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.

  12. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  13. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  14. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  15. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  16. 40 CFR 721.2093 - Alkenyl carboxylate, metal salt (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkenyl carboxylate, metal salt... Specific Chemical Substances § 721.2093 Alkenyl carboxylate, metal salt (generic). (a) Chemical substance... alkenyl carboxylate, metal salt (PMN P-99-0848) is subject to reporting under this section for...

  17. Group analysis of self-organizing maps based on functional MRI using restricted Frechet means.

    PubMed

    Fournel, Arnaud P; Reynaud, Emanuelle; Brammer, Michael J; Simmons, Andrew; Ginestet, Cedric E

    2013-08-01

    Studies of functional MRI data are increasingly concerned with the estimation of differences in spatio-temporal networks across groups of subjects or experimental conditions. Unsupervised clustering and independent component analysis (ICA) have been used to identify such spatio-temporal networks. While these approaches have been useful for estimating these networks at the subject-level, comparisons over groups or experimental conditions require further methodological development. In this paper, we tackle this problem by showing how self-organizing maps (SOMs) can be compared within a Frechean inferential framework. Here, we summarize the mean SOM in each group as a Frechet mean with respect to a metric on the space of SOMs. The advantage of this approach is twofold. Firstly, it allows the visualization of the mean SOM in each experimental condition. Secondly, this Frechean approach permits one to draw inference on group differences, using permutation of the group labels. We consider the use of different distance functions, and introduce one extension of the classical sum of minimum distance (SMD) between two SOMs, which take into account the spatial pattern of the fMRI data. The validity of these methods is illustrated on synthetic data. Through these simulations, we show that the two distance functions of interest behave as expected, in the sense that the ones capturing temporal and spatial aspects of the SOMs are more likely to reach significance under simulated scenarios characterized by temporal, spatial [and spatio-temporal] differences, respectively. In addition, a re-analysis of a classical experiment on visually-triggered emotions demonstrates the usefulness of this methodology. In this study, the multivariate functional patterns typical of the subjects exposed to pleasant and unpleasant stimuli are found to be more similar than the ones of the subjects exposed to emotionally neutral stimuli. In this re-analysis, the group-level SOM output units with the smallest sample Jaccard indices were compared with standard GLM group-specific z-score maps, and provided considerable levels of agreement. Taken together, these results indicate that our proposed methods can cast new light on existing data by adopting a global analytical perspective on functional MRI paradigms. PMID:23534989

  18. 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

  19. 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.

  20. The tertiary structure of group II introns: implications for biological function and evolution.

    PubMed

    Pyle, Anna Marie

    2010-06-01

    Group II introns are some of the largest ribozymes in nature, and they are a major source of information about RNA assembly and tertiary structural organization. These introns are of biological significance because they are self-splicing mobile elements that have migrated into diverse genomes and played a major role in the genomic organization and metabolism of most life forms. The tertiary structure of group II introns has been the subject of many phylogenetic, genetic, biochemical and biophysical investigations, all of which are consistent with the recent crystal structure of an intact group IIC intron from the alkaliphilic eubacterium Oceanobacillus iheyensis. The crystal structure reveals that catalytic intron domain V is enfolded within the other intronic domains through an elaborate network of diverse tertiary interactions. Within the folded core, DV adopts an activated conformation that readily binds catalytic metal ions and positions them in a manner appropriate for reaction with nucleic acid targets. The tertiary structure of the group II intron reveals new information on motifs for RNA architectural organization, mechanisms of group II intron catalysis, and the evolutionary relationships among RNA processing systems. Guided by the structure and the wealth of previous genetic and biochemical work, it is now possible to deduce the probable location of DVI and the site of additional domains that contribute to the function of the highly derived group IIB and IIA introns. PMID:20446804

  1. Brain functional networks extraction based on fMRI artifact removal: Single subject and group approaches.

    PubMed

    Yuhui Du; Allen, Elena A; Hao He; Jing Sui; Calhoun, Vince D

    2014-08-01

    Independent component analysis (ICA) has been widely applied to identify brain functional networks from multiple-subject fMRI. However, the best approach to handle artifacts is not yet clear. In this work, we study and compare two ICA approaches for artifact removal using simulations and real fMRI data. The first approach, recommended by the human connectome project, performs ICA on individual data to remove artifacts, and then applies group ICA on the cleaned data from all subjects. We refer to this approach as Individual ICA artifact Removal Plus Group ICA (TRPG). A second approach, Group Information Guided ICA (GIG-ICA), performs ICA on group data, and then removes the artifact group independent components (ICs), followed by individual subject ICA using the remaining group ICs as spatial references. Experiments demonstrate that GIG-ICA is more accurate in estimation of sources and time courses, more robust to data quality and quantity, and more reliable for identifying networks than IRPG. PMID:25570136

  2. Dissociation of equimolar mixtures of aqueous carboxylic acids in ionic liquids: role of specific interactions.

    PubMed

    Shukla, Shashi Kant; Kumar, Anil

    2015-04-30

    Hammett acidity function observes the effect of protonation/deprotonation on the optical density/absorbance of spectrophotometric indicator. In this work, the Hammett acidity, H0, of equimolar mixtures of aqueous HCOOH, CH3COOH, and CH3CH2COOH was measured in 1-methylimidazolium-, 1-methylpyrrolidinium-, and 1-methylpiperidinium-based protic ionic liquids (PILs) and 1-butyl-3-methylimidazolium-based aprotic ionic liquid (AIL) with formate (HCOO(-)) anion. Higher H0 values were observed for the equimolar mixtures of aqueous carboxylic acids in protic ionic liquids compared with those of the aprotic ionic liquid because of the involvement of the stronger specific interactions between the conjugate acid of ionic liquid and conjugate base of carboxylic acids as suggested by the hard-soft acid base (HSAB) theory. The different H0 values for the equimolar mixtures of aqueous carboxylic acids in protic and aprotic ionic liquids were noted to depend on the activation energy of proton transfer (Ea,H(+)). The higher activation energy of proton transfer was obtained in AIL, indicating lower ability to form specific interactions with solute than that of PILs. Thermodynamic parameters determined by the "indicator overlapping method" further confirmed the involvement of the secondary interactions in the dissociation of carboxylic acids. On the basis of the thermodynamic parameter values, the potential of different ionic liquids in the dissociation of carboxylic acids was observed to depend on the hydrogen bond donor acidity (?) and hydrogen bond acceptor basicity (?), characteristics of specific interactions. PMID:25839210

  3. How surface functional groups influence fracturation in nanofluids droplets dry-outs

    NASA Astrophysics Data System (ADS)

    Brutin, David; Carle, Florian

    2012-11-01

    We report an experimental investigation of the drying of a deposited droplets of nanofluids with different surface functional groups. For identical nano-particles diameter, material and concentration, identical drying conditions, the substrate and the functional groups at the nano-particles surface are changed. Both flow motion, adhesion, gelation and fracturation occur during the evaporation of this complex matter leading to different final typical patterns. The differences in between the patterns are explained based on the surface chemical potential. Crack shapes and wavelengths are globally proportional to the electrical charges carried at the nano- particles surface which is a new parameter to implement in existing predicting models. Presently only the colloid concentration and softness and the deposit thickness are used (Allain and Limat, 1995). The authors gratefully acknowledge the help and the fruitful discussions raised with J.B. Lang.

  4. Approaching many-body localization from disordered Luttinger liquids via the functional renormalization group

    NASA Astrophysics Data System (ADS)

    Karrasch, C.; Moore, J. E.

    2015-09-01

    We study the interplay of interactions and disorder in a one-dimensional fermion lattice coupled adiabatically to infinite reservoirs. We employ both the functional renormalization group (FRG) as well as matrix product state techniques, which serve as an accurate benchmark for small systems. Using the FRG, we compute the length- and temperature-dependence of the conductance averaged over 104 samples for lattices as large as 105 sites. We identify regimes in which non-Ohmic power law behavior can be observed and demonstrate that the corresponding exponents can be understood by adapting earlier predictions obtained perturbatively for disordered Luttinger liquids. In the presence of both disorder and isolated impurities, the conductance has a universal single-parameter scaling form. This lays the groundwork for an application of the functional renormalization group to the realm of many-body localization.

  5. Assemblage patterns of fish functional groups relative to habitat connectivity and conditions in floodplain lakes

    USGS Publications Warehouse

    Miyazono, S.; Aycock, J.N.; Miranda, L.E.; Tietjen, T.E.

    2010-01-01

    We evaluated the influences of habitat connectivity and local environmental factors on the distribution and abundance patterns of fish functional groups in 17 floodplain lakes in the Yazoo River Basin, USA. The results of univariate and multivariate analyses showed that species-environmental relationships varied with the functional groups. Species richness and assemblage structure of periodic strategists showed strong and positive correlations with habitat connectivity. Densities of most equilibrium and opportunistic strategists decreased with habitat connectivity. Densities of certain equilibrium and opportunistic strategists increased with turbidity. Forested wetlands around the lakes were positively related to the densities of periodic and equilibrium strategists. These results suggest that decreases in habitat connectivity, forested wetland buffers and water quality resulting from environmental manipulations may cause local extinction of certain fish taxa and accelerate the dominance of tolerant fishes in floodplain lakes. ?? 2010 John Wiley & Sons A/S.

  6. ?-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

  7. Templating route for mesostructured calcium phosphates with carboxylic acid- and amine-type surfactants.

    PubMed

    Ikawa, Nobuaki; Hori, Hideki; Kimura, Tatsuo; Oumi, Yasunori; Sano, Tsuneji

    2008-11-18

    Mesostructured calcium phosphates constructed by ionic frameworks were synthesized using carboxylic acid- and amine-type surfactants in mixed solvent systems of ethanol and water. A lamellar mesostructured calcium phosphate was prepared using palmitic acid as an anionic surfactant, as in the case using n-alkylamines. A wormhole-like mesostructured calcium phosphate can be obtained using dicarboxyl N-lauroyl- l-glutamic acid, whose headgroup is larger than that of palmitic acid. Similar mesostructured product was obtained using 4-dodecyldiethylenetriamine with a large headgroup containing two primary amine groups. Interactions of carboxyl and primary amino groups in the surfactant molecules with inorganic species are quite important for the formation of mesostructured calcium phosphates. The Ca/P molar ratio of mesostructured calcium phosphates was strongly affected by the molecular structure of surfactants containing carboxyl and primary amino groups. Ca-rich materials can be obtained using carboxylic acid-type surfactants (Ca/P approximately 1.7) rather than amine-type surfactants (Ca/P approximately 1.0). PMID:18947246

  8. Functional group-specific traits drive phytoplankton dynamics in the oligotrophic ocean.

    PubMed

    Alexander, Harriet; Rouco, Mónica; Haley, Sheean T; Wilson, Samuel T; Karl, David M; Dyhrman, Sonya T

    2015-11-01

    A diverse microbial assemblage in the ocean is responsible for nearly half of global primary production. It has been hypothesized and experimentally demonstrated that nutrient loading can stimulate blooms of large eukaryotic phytoplankton in oligotrophic systems. Although central to balancing biogeochemical models, knowledge of the metabolic traits that govern the dynamics of these bloom-forming phytoplankton is limited. We used eukaryotic metatranscriptomic techniques to identify the metabolic basis of functional group-specific traits that may drive the shift between net heterotrophy and autotrophy in the oligotrophic ocean. Replicated blooms were simulated by deep seawater (DSW) addition to mimic nutrient loading in the North Pacific Subtropical Gyre, and the transcriptional responses of phytoplankton functional groups were assayed. Responses of the diatom, haptophyte, and dinoflagellate functional groups in simulated blooms were unique, with diatoms and haptophytes significantly (95% confidence) shifting their quantitative metabolic fingerprint from the in situ condition, whereas dinoflagellates showed little response. Significantly differentially abundant genes identified the importance of colimitation by nutrients, metals, and vitamins in eukaryotic phytoplankton metabolism and bloom formation in this system. The variable transcript allocation ratio, used to quantify transcript reallocation following DSW amendment, differed for diatoms and haptophytes, reflecting the long-standing paradigm of phytoplankton r- and K-type growth strategies. Although the underlying metabolic potential of the large eukaryotic phytoplankton was consistently present, the lack of a bloom during the study period suggests a crucial dependence on physical and biogeochemical forcing, which are susceptible to alteration with changing climate. PMID:26460011

  9. Group 2 Innate Lymphoid Cells Express Functional NKp30 Receptor Inducing Type 2 Cytokine Production.

    PubMed

    Salimi, Maryam; Xue, Luzheng; Jolin, Helen; Hardman, Clare; Cousins, David J; McKenzie, Andrew N J; Ogg, Graham S

    2016-01-01

    Group 2 innate lymphoid cells (ILC2) are important in effector functions for eliciting allergic inflammation, parasite defense, epithelial repair, and lipid homeostasis. ILC2 lack rearranged Ag-specific receptors, and although many soluble factors such as cytokines and lipid mediators can influence ILC2, direct interaction of these cells with the microenvironment and other cells has been less explored. Natural cytotoxicity receptors are expressed by subsets of group 1 ILC and group 3 ILC and thought to be important for their effector function, but they have not been shown to be expressed by ILC2. Therefore, we sought to investigate the expression and functional properties of the natural cytotoxicity receptor NKp30 on human ILC2. A subset of ex vivo and cultured ILC2 express NKp30 that upon interaction with its cognate activatory ligand B7-H6 induces rapid production of type 2 cytokines. This interaction can be blocked by NKp30 blocking Ab and an inhibitory ligand, galectin-3. Higher expression of B7-H6 was observed in lesional skin biopsies of patients with atopic dermatitis, and incubation of keratinocytes with proinflammatory and type 2 cytokines upregulated B7-H6, leading to increased ILC2 cytokine production. NKp30-B7-H6 interaction is a novel cell contact mechanism that mediates activation of ILC2 and identifies a potential target for the development of novel therapeutics for atopic dermatitis and other atopic diseases. PMID:26582946

  10. Functional group-specific traits drive phytoplankton dynamics in the oligotrophic ocean

    PubMed Central

    Alexander, Harriet; Rouco, Mónica; Haley, Sheean T.; Wilson, Samuel T.; Karl, David M.; Dyhrman, Sonya T.

    2015-01-01

    A diverse microbial assemblage in the ocean is responsible for nearly half of global primary production. It has been hypothesized and experimentally demonstrated that nutrient loading can stimulate blooms of large eukaryotic phytoplankton in oligotrophic systems. Although central to balancing biogeochemical models, knowledge of the metabolic traits that govern the dynamics of these bloom-forming phytoplankton is limited. We used eukaryotic metatranscriptomic techniques to identify the metabolic basis of functional group-specific traits that may drive the shift between net heterotrophy and autotrophy in the oligotrophic ocean. Replicated blooms were simulated by deep seawater (DSW) addition to mimic nutrient loading in the North Pacific Subtropical Gyre, and the transcriptional responses of phytoplankton functional groups were assayed. Responses of the diatom, haptophyte, and dinoflagellate functional groups in simulated blooms were unique, with diatoms and haptophytes significantly (95% confidence) shifting their quantitative metabolic fingerprint from the in situ condition, whereas dinoflagellates showed little response. Significantly differentially abundant genes identified the importance of colimitation by nutrients, metals, and vitamins in eukaryotic phytoplankton metabolism and bloom formation in this system. The variable transcript allocation ratio, used to quantify transcript reallocation following DSW amendment, differed for diatoms and haptophytes, reflecting the long-standing paradigm of phytoplankton r- and K-type growth strategies. Although the underlying metabolic potential of the large eukaryotic phytoplankton was consistently present, the lack of a bloom during the study period suggests a crucial dependence on physical and biogeochemical forcing, which are susceptible to alteration with changing climate. PMID:26460011

  11. Microstructures and functional groups of Nannochloropsis sp. cells with arsenic adsorption and lipid accumulation.

    PubMed

    Sun, Jing; Cheng, Jun; Yang, Zongbo; Li, Ke; Zhou, Junhu; Cen, Kefa

    2015-10-01

    The pore structures and surface morphological characteristics of Nannochloropsis sp. cells with arsenic adsorption were initially investigated by N2-adsorption analysis and scanning electronic microscopy. Functional groups of cells were analysed by Fourier-transform infrared spectrometry and X-ray photoelectron spectroscopy. Total surface area of microalgal cells increased from 0.54 m(2)/g to 1.80 m(2)/g upon arsenic adsorption. The external cell surface area increased. More wrinkles and measles-like granules formed on the surfaces as a result of arsenic toxicity. Arsenic ions blocked cell pores and decreased the average pore diameter and total pore volume. Ether cross-linked structures in the algaenan layer of cell walls were disrupted as the percentage of C-O functional groups decreased. These functional groups underwent complexation reactions with arsenic ions. Accumulation of polyunsaturated fatty acids decreased because of oxidative stresses induced by arsenic. The increase in generation of short-chain saturated fatty acids was favourable for the production of quality biodiesel. PMID:26210144

  12. Expression of Amino-and Carboxyl-terminal -and -Tubulin Mutants in Cultured Epithelial Cells*

    E-print Network

    Stearns, Tim

    Expression of Amino- and Carboxyl-terminal - and -Tubulin Mutants in Cultured Epithelial Cells University, Stanford, California 94030-5020 Three distinct tubulin proteins are essential for mi- crotubule function: -, -, and -tubulin. After transla- tion, - and -tubulin proteins combine into a soluble, 7

  13. Technical Note: Development of chemoinformatic tools to enumerate functional groups in molecules for organic aerosol characterization

    NASA Astrophysics Data System (ADS)

    Ruggeri, G.; Takahama, S.

    2015-11-01

    Functional groups (FGs) can be used as a reduced representation of organic aerosol composition in both ambient and environmental controlled chamber studies, as they retain a certain chemical specificity. Furthermore, FG composition has been informative for source apportionment, and various models based on a group contribution framework have been developed to calculate physicochemical properties of organic compounds. In this work, we provide a set of validated chemoinformatic patterns that correspond to: (1) groups incorporated in the SIMPOL.1 vapor pressure estimation model, (2) FGs that are measurable by Fourier transform infrared spectroscopy (FTIR), (3) a complete set of functional groups that can entirely describe the molecules comprised in the ?-pinene and 1,3,5-trimethylbenzene MCMv3.2 oxidation schemes, and (4) bonds necessary for the calculation of carbon oxidation state. We also provide example applications for this set of patterns. We compare available aerosol composition reported by chemical speciation measurements and FTIR for different emission sources, and calculate the FG contribution to the O : C ratio of simulated gas phase composition generated from ?-pinene photooxidation (using MCMv3.2 oxidation scheme).

  14. 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.

  15. 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.

  16. Evidence supporting the importance of microbial functional groups in decomposition models

    NASA Astrophysics Data System (ADS)

    Todd-Brown, K. E.; Lu, L.; Allison, S. D.

    2010-12-01

    Microbial communities mediate organic carbon decomposition in both soil and marine environments. Decomposition depends on microbes that produce extracellular enzymes to degrade complex organic matter, as well as microbes that mineralize simple organic matter to CO2. Therefore microbes could be represented in Earth system models as functional groups based on the extracellular enzymes they produce. However, the importance of including the functional diversity of microbes in decomposition models has been unclear. In this study we simulated microbial functional diversity with two strains of Pseudomonas fluorescens bacteria, one of which secretes extracellular protease and one that does not. These two strains were competed on several carbon resources including casein-glucose, casamino acids-glucose and glucose over several days. We then fit a series of models to the resulting data: 1) an explicit model representing both biomass and substrate pools, 2) a simplified substrate pool model with two biomass pools and one substrate pool, 3) a simplified biomass pool model with one biomass and two substrate pools, 4) a simplified biomass/substrate pool model with one biomass and one substrate pool, and 5) a single carbon pool model. We found that the explicit model (#1) fit the laboratory data significantly better than the other models, suggesting that functional groups and substrate pools should be represented in global decomposition models with time steps on the order of hours.

  17. Fossil group origins. V. The dependence of the luminosity function on the magnitude gap

    NASA Astrophysics Data System (ADS)

    Zarattini, S.; Aguerri, J. A. L.; Sánchez-Janssen, R.; Barrena, R.; Boschin, W.; del Burgo, C.; Castro-Rodriguez, N.; Corsini, E. M.; D'Onghia, E.; Girardi, M.; Iglesias-Páramo, J.; Kundert, A.; Méndez-Abreu, J.; Vilchez, J. M.

    2015-09-01

    Context. In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system (?m12). Thus, 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. The observed distribution of magnitude gaps is thought to be a consequence of the orbital decay of M? galaxies in massive halos and the associated growth of the central object. As a result, to first order the amplitude of this gap is a good statistical proxy for the dynamical age of a system of galaxies. Fossil and non-fossil systems could therefore have different galaxy populations that should be reflected in their luminosity functions. Aims: In this work we study, for the first time, the dependence of the luminosity function parameters on ?m12 using data obtained by the fossil group origins (FOGO) project. Methods: We constructed a hybrid luminosity function for 102 groups and clusters at z ? 0.25 using both photometric data from the SDSS-DR7 and redshifts from the DR7 and the FOGO surveys. The latter consists of ~1200 new redshifts in 34 fossil system candidates. We stacked all the individual luminosity functions, dividing them into bins of ?m12, 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 differences - especially at the bright end. Results: We find trends as a function of ?m12 at both the bright and faint ends of the luminosity function. In particular, at the bright end, the larger the magnitude gap, the fainter the characteristic magnitude M?. The characteristic luminosity in systems with negligible gaps is more than a factor three brighter than in fossil-like ones. Remarkably, we also find differences at the faint end. In this region, the larger the gap, the flatter the faint-end slope ?. Conclusions: The differences found at the bright end support a dissipationless, dynamical friction-driven merging model for the growth of the central galaxy in group- and cluster-sized halos. The differences in the faint end cannot be explained by this mechanism. Other processes - such as enhanced tidal disruption due to early infall and/or prevalence of eccentric orbits - may play a role. However, a larger sample of systems with ?m12> 1.5 is needed to establish the differences at the faint end.

  18. A renormalization group improved computation of correlation functions in theories with non-trivial phase diagram

    E-print Network

    Codello, Alessandro

    2015-01-01

    We present a simple and consistent way to compute correlation functions in interacting theories with non-trivial phase diagram. As an example we show how to consistently compute the four-point function in three dimensional $\\mathbb{Z}_2$-scalar theories. The idea is to perform the path integral by weighting the momentum modes that contribute to it according to their renormalization group (RG) relevance, i.e. we weight each mode according to the value of the running couplings at that scale. In this way, we are able encode in a loop computation the information regarding the RG trajectory along which we are integrating. We show that depending on the initial condition, or initial point in the phase diagram, we obtain different behaviors of the four-point function at the end point of the flow.

  19. Sequential Linker Installation: Precise Placement of Functional Groups in Multivariate Metal-Organic Frameworks

    SciTech Connect

    Yuan, S; Lu, WG; Chen, YP; Zhang, Q; Liu, TF; Feng, DW; Wang, X; Qin, JS; Zhou, HC

    2015-03-11

    A unique strategy, sequential linker installation (SLI), has been developed to construct multivariate MOFs with functional groups precisely positioned. PCN-700, a Zr-MOF with eight-connected Zr6O4(OH)(8)(H2O)(4) clusters, has been judiciously designed; the Zr-6 clusters in this MOF are arranged in such a fashion that, by replacement of terminal OH-/H2O ligands, subsequent insertion of linear dicarboxylate linkers is achieved. We demonstrate that linkers with distinct lengths and functionalities can be sequentially installed into PCN-700. Single-crystal to single-crystal transformation is realized so that the positions of the subsequently installed linkers are pinpointed via single-crystal X-ray diffraction analyses. This methodology provides a powerful tool to construct multivariate MOFs with precisely positioned functionalities in the desired proximity, which would otherwise be difficult to achieve.

  20. Pyrolysis Mechanisms of Aromatic Carboxylic Acids

    SciTech Connect

    Britt, P.F.; Eskay, T.P.; Buchanan, A.C. III

    1997-12-31

    Although decarboxylation of carboxylic acids is widely used in organic synthesis, there is limited mechanistic information on the uncatalyzed reaction pathways of aromatic carboxylic acids at 300-400 {degrees} C. The pyrolysis mechanisms of 1,2-(3,3-dicarboxyphenyl)ethane, 1,2-(4,4-dicarboxylphenyl)ethane, 1-(3-carboxyphenyl)-2-(4- biphenyl)ethane, and substituted benzoic acids have been investigated at 325-425 {degrees} C neat and diluted in an inert solvent. Decarboxylation is the dominant pyrolysis path. Arrhenius parameters, substituent effects, and deuterium isotope effects are consistent with decarboxylation by an electrophilic aromatic substitution reaction. Pyrolysis of benzoic acid in naphthalene, as a solvent, produces significant amounts of 1- and 2-phenylnaphthalenes. The mechanistic pathways for decarboxylation and arylation with be presented.

  1. Cyclohexane carboxylate and benzoate formation from crotonate in Syntrophus aciditrophicus.

    PubMed

    Mouttaki, Housna; Nanny, Mark A; McInerney, Michael J

    2007-02-01

    The anaerobic, syntrophic bacterium Syntrophus aciditrophicus grown in pure culture produced 1.4 +/- 0.24 mol of acetate and 0.16 +/- 0.02 mol of cyclohexane carboxylate per mole of crotonate metabolized. [U-13C]crotonate was metabolized to [1,2-(13)C]acetate and [1,2,3,4,5,7-(13)C]cyclohexane carboxylate. Cultures grown with unlabeled crotonate and [13C]sodium bicarbonate formed [6-(13)C]cyclohexane carboxylate. Trimethylsilyl (TMS) derivatives of cyclohexane carboxylate, cyclohex-1-ene carboxylate, benzoate, pimelate, glutarate, 3-hydroxybutyrate, and acetoacetate were detected as intermediates by comparison of retention times and mass spectral profiles to authentic standards. With [U-(13)C]crotonate, the m/z-15 ion of TMS-derivatized glutarate, 3-hydroxybutyrate, and acetoacetate each increased by +4 mass units, and the m/z-15 ion of TMS-derivatized pimelate, cyclohex-1-ene carboxylate, benzoate, and cyclohexane carboxylate each increased by +6 mass units. With [13C]sodium bicarbonate and unlabeled crotonate, the m/z-15 ion of TMS derivatives of glutarate, pimelate, cyclohex-1-ene carboxylate, benzoate, and cyclohexane carboxylate each increased by +1 mass unit, suggesting that carboxylation occurred after the synthesis of a four-carbon intermediate. With [1,2-(13)C]acetate and unlabeled crotonate, the m/z-15 ion of TMS-derivatized 3-hydroxybutyrate, acetoacetate, and glutarate each increased by +0, +2, and +4 mass units, respectively, and the m/z-15 ion of TMS-derivatized pimelate, cyclohex-1-ene carboxylate, benzoate, cyclohexane carboxylate, and 2-hydroxycyclohexane carboxylate each increased by +0, +2, +4, and +6 mass units. The data are consistent with a pathway for cyclohexane carboxylate formation involving the condensation of two-carbon units derived from crotonate degradation with CO2 addition, rather than the use of the intact four-carbon skeleton of crotonate. PMID:17158621

  2. Water Desalination through Zeolitic Imidazolate Framework Membranes: Significant Role of Functional Groups.

    PubMed

    Gupta, Krishna M; Zhang, Kang; Jiang, Jianwen

    2015-12-01

    A molecular simulation study is reported for water desalination through five zeolitic imidazolate framework (ZIF) membranes, namely ZIF-25, -71, -93, -96, and -97. The five ZIFs possess identical rho-topology but differ in functional groups. The rejection of salt (NaCl) is found to be around 97% in ZIF-25, and 100% in the other four ZIFs. The permeance ranges from 27 to 710 kg/(m(2)·h·bar), about one?two orders of magnitude higher compared with commercial reverse osmosis membranes. Due to a larger aperture size da, ZIF-25, -71, and -96 exhibit a much higher water flux than ZIF-93 and -97; however, the flux in ZIF-25, -71, and -96 is governed by the polarity of functional group rather than da. With the hydrophobic CH3 group, ZIF-25 has the highest flux despite the smallest da among ZIF-25, -71, and -96. The lifetime of hydrogen bonding in ZIF-25 is shorter than that in ZIF-71 and -96. Furthermore, water molecules undergo a fast flushing motion in ZIF-25, but frequent jumping in ZIF-96 and particularly in ZIF-97. An Arrhenius-type relationship is found between water flux in ZIF-25 and temperature, and the activation energy is predicted to be 6.5 kJ/mol. This simulation study provides a microscopic insight into water desalination in a series of ZIFs, reveals the key factors (aperture size and polarity of functional group) governing water flux, and suggests that ZIF-25 might be an interesting reverse osmosis membrane for high-performance water desalination. PMID:26588699

  3. Effect of functional groups on the sensing properties of silicon nanowires toward volatile compounds.

    PubMed

    Wang, Bin; Haick, Hossam

    2013-03-01

    Molecular layers attached to a silicon nanowire field effect transistor (SiNW FET) can serve as antennas for signal transduction of volatile organic compounds (VOCs). Nevertheless, the mutual relationship between the molecular layers and VOCs is still a puzzle. In the present paper, we explore the effect of the molecular layer's end (functional) groups on the sensing properties of VOCs. Toward this end, SiNW FETs were modified with tailor-made molecular layers that have the same backbone but differ in their end groups. Changes in the threshold voltage (?Vth) and changes in the mobility (??h) were then recorded upon exposure to various VOCs. Model-based analysis indicates that the interaction between molecular layers and VOCs can be classified to three main scenarios: (a) dipole-dipole interaction between the molecular layer and the polar VOCs; (b) induced dipole-dipole interaction between the molecular layers and the nonpolar VOCs; and (c) molecular layer tilt as a result of VOCs diffusion. Based on these scenarios, it is likely that the electron-donating/withdrawing properties of the functional groups control the dipole moment orientation of the adsorbed VOCs and, as a result, determine the direction (or sign) of the ?Vth. Additionally, it is likely the diffusion of VOCs into the molecular layer, determined by the type of functional groups, is the main reason for the ??h responses. The reported findings are expected to provide an efficient way to design chemical sensors that are based on SiNW FETs to nonpolar VOCs, which do not exchange carriers with the molecular layers. PMID:23452335

  4. Acoustic analysis and detection of hypernasality using a group delay function.

    PubMed

    Vijayalakshmi, P; Reddy, M Ramasubba; O'Shaughnessy, Douglas

    2007-04-01

    In this paper, we describe a group delay-based signal processing technique for the analysis and detection of hypernasal speech. Our preliminary acoustic analysis on nasalized vowels shows that, even though additional resonances are introduced at various frequency locations, the introduction of a new resonance in the low-frequency region (around 250 Hz) is found to be consistent. This observation is further confirmed by a perceptual analysis carried out on vowel sounds that are modified by introducing different nasal resonances, and an acoustic analysis on hypernasal speech. Based on this, for subsequent experiments the focus is given only to the low-frequency region. The additive property of the group delay function can be exploited to resolve two closely spaced formants. However, when the formants are very close with considerably wider bandwidths as in hypernasal speech, the group delay function also fails to resolve. To overcome this, we suggest a band-limited approach to estimate the locations of the formants. Using the band-limited group delay spectrum, we define a new acoustic measure for the detection of hypernasality. Experiments are carried out on the phonemes /a/, /i/, and /u/ uttered by 33 hypernasal speakers and 30 normal speakers. Using the group delay-based acoustic measure, the performance on a hypernasality detection task is found to be 100% for /a/, 88.78% for /i/ and 86.66% for /u/. The effectiveness of this acoustic measure is further cross-verified on a speech data collected in an entirely different recording environment. PMID:17405369

  5. An epididymis-specific carboxyl esterase CES5A is required for sperm capacitation and male fertility in the rat

    PubMed Central

    Ru, Yan-Fei; Xue, Hai-Min; Ni, Zi-Mei; Xia, Dong; Zhou, Yu-Chuan; Zhang, Yong-Lian

    2015-01-01

    Despite the fact that the phenomenon of capacitation was discovered over half century ago and much progress has been made in identifying sperm events involved in capacitation, few specific molecules of epididymal origin have been identified as being directly involved in this process in vivo. Previously, our group cloned and characterized a carboxyl esterase gene Ces5a in the rat epididymis. The CES5A protein is mainly expressed in the corpus and cauda epididymidis and secreted into the corresponding lumens. Here, we report the function of CES5A in sperm maturation. By local injection of Lentivirus-mediated siRNA in the CES5A-expressing region of the rat epididymis, Ces5a-knockdown animal models were created. These animals exhibited an inhibited sperm capacitation and a reduction in male fertility. These results suggest that CES5A plays an important role in sperm maturation and male fertility. PMID:25475668

  6. 14 CFR Section 11 - Functional Classification-Operating Expenses of Group II and Group III Air Carriers

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 false Functional Classification-Operating Expenses of...CARRIERS Profit and Loss Classification Section 11 Functional Classification—Operating Expenses of...expenses incurred on the ground in protecting and...

  7. Tree Diametric Increment and Litterfall Production in an Eastern Amazonian Forest: the Role of Functional Groups

    NASA Astrophysics Data System (ADS)

    Camargo, P. B. D.; Ferreira, M. L.; Oliveira Junior, R. C.; Saleska, S. R.

    2014-12-01

    Tree growth is a biotic variable of great importance in understanding the dynamics of tree communities and may be used as a tool in studies of biological or climate modeling. Some climate models predict more recurrent climate anomalies in this century, which may alter the functioning of tropical forests with serious structural and demographic implications. The present study aimed to evaluate the profile of tree growth and litterfall production in an eastern Amazon forest, which has suffered recent climatic disturbances. We contrasted different functional groups based on wood density (stem with 0.55; 0.56-0.7; >0.7 g cm-3), light availability (crown illumination index; high illuminated crown - IIC1 until shaded crown - IIC5), and, size class (trees 10-22.5; 22.6-35; 35.1-55; 55,1-90; >90 cm dbh). Tree diameter increment was monthly measured from November 2011 to September 2013 by using dendrometer bands installed on 850 individuals from different families. Litterfall was collected in 64 circular traps, oven dried and weighed, separated into leaves, twigs, reproductive parts and miscellaneous. During the rainy season the sampled trees had the highest rates of tree diametric increment. When analyzing the data by functional groups, large trees had faster growth, but when grouped by wood density, trees with wood density up to 0.55 and between 0.56 and 0.7 g cm-3 had the fastest rates of growth. When grouped by crown illumination index, trees exposed to higher levels of light grew more in comparison to partially shaded trees. Maximum daily air temperature and precipitation were the most important environmental variables in determining the diametric increment profile of the trees. Litterfall production was estimated to be 7.1 Mg ha-1.year-1 and showed a strong seasonal pattern, with dry season production being higher than in the rainy season. Leaves formed the largest fraction of the litterfall, followed by twigs, reproductive parts, and finally miscellaneous. These results show that the profile of tree diametric growth and litterfall production are recorded at close intervals in the preterit analyzes in the same study area and highlights the efficiency of functional groups in determining the tree growth profile.

  8. 14 CFR Section 11 - Functional Classification-Operating Expenses of Group II and Group III Air Carriers

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... assignment to an in-flight status. (b) This function shall not include expenses incurred in repairing... preparing aircraft or aircraft operational personnel for flight assignment. Such expenses shall be included in function 5400 Maintenance, or function 6400 Aircraft and Traffic Servicing. 5400Maintenance....

  9. 14 CFR Section 11 - Functional Classification-Operating Expenses of Group II and Group III Air Carriers

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... assignment to an in-flight status. (b) This function shall not include expenses incurred in repairing... preparing aircraft or aircraft operational personnel for flight assignment. Such expenses shall be included in function 5400 Maintenance, or function 6400 Aircraft and Traffic Servicing. 5400Maintenance....

  10. 14 CFR Section 11 - Functional Classification-Operating Expenses of Group II and Group III Air Carriers

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... assignment to an in-flight status. (b) This function shall not include expenses incurred in repairing... preparing aircraft or aircraft operational personnel for flight assignment. Such expenses shall be included in function 5400 Maintenance, or function 6400 Aircraft and Traffic Servicing. 5400Maintenance....

  11. Impact of dendrimer surface functional groups on the release of doxorubicin from dendrimer carriers.

    PubMed

    Zhang, Mengen; Guo, Rui; Kéri, Mónika; Bányai, István; Zheng, Yun; Cao, Mian; Cao, Xueyan; Shi, Xiangyang

    2014-02-13

    Generation 5 (G5) poly(amidoamine) dendrimers with acetyl (G5.NHAc), glycidol hydroxyl (G5.NGlyOH), and succinamic acid (G5.SAH) terminal groups were used to physically encapsulate an anticancer drug doxorubicin (DOX). Both UV-vis spectroscopy and multiple NMR techniques including one-dimensional NMR and two-dimensional NMR were applied to investigate the interactions between different dendrimers and DOX. The influence of the surface functional groups of G5 dendrimers on the DOX encapsulation, release kinetics, and cancer cell inhibition effect was investigated. We show that all three types of dendrimers are able to effectively encapsulate DOX and display therapeutic inhibition effect to cancer cells, which is solely associated with the loaded DOX. The relatively stronger interactions of G5.NHAc or G5.NGlyOH dendrimers with DOX than that of G5.SAH dendrimers with DOX demonstrated by NMR techniques correlate well with the slow release rate of DOX from G5.NHAc/DOX or G5.NGlyOH/DOX complexes. In contrast, the demonstrated weak interaction between G5.SAH and DOX causes a fast release of DOX, suggesting that the G5.SAH/DOX complex may not be a proper option for further in vivo research. Our findings suggest that the dendrimer surface functional groups are crucial for further design of multifunctional dendrimer-based drug delivery systems for various biomedical applications. PMID:24467521

  12. Toward a standardized structural-functional group connectome in MNI space.

    PubMed

    Horn, Andreas; Blankenburg, Felix

    2016-01-01

    The analysis of the structural architecture of the human brain in terms of connectivity between its subregions has provided profound insights into its underlying functional organization and has coined the concept of the "connectome", a structural description of the elements forming the human brain and the connections among them. Here, as a proof of concept, we introduce a novel group connectome in standard space based on a large sample of 169 subjects from the Enhanced Nathan Kline Institute-Rockland Sample (eNKI-RS). Whole brain structural connectomes of each subject were estimated with a global tracking approach, and the resulting fiber tracts were warped into standard stereotactic (MNI) space using DARTEL. Employing this group connectome, the results of published tracking studies (i.e., the JHU white matter and Oxford thalamic connectivity atlas) could be largely reproduced directly within MNI space. In a second analysis, a study that examined structural connectivity between regions of a functional network, namely the default mode network, was reproduced. Voxel-wise structural centrality was then calculated and compared to others' findings. Furthermore, including additional resting-state fMRI data from the same subjects, structural and functional connectivity matrices between approximately forty thousand nodes of the brain were calculated. This was done to estimate structure-function agreement indices of voxel-wise whole brain connectivity. Taken together, the combination of a novel whole brain fiber tracking approach and an advanced normalization method led to a group connectome that allowed (at least heuristically) performing fiber tracking directly within MNI space. Such an approach may be used for various purposes like the analysis of structural connectivity and modeling experiments that aim at studying the structure-function relationship of the human connectome. Moreover, it may even represent a first step toward a standard DTI template of the human brain in stereotactic space. The standardized group connectome might thus be a promising new resource to better understand and further analyze the anatomical architecture of the human brain on a population level. PMID:26327244

  13. Dissociative Binding of Carboxylic Acid Ligand on Nanoceria Surface in Aqueous Solution: A Joint in Situ Spectroscopic Characterization and First-Principles Study

    SciTech Connect

    Lu, Zhou; Karakoti, Ajay S.; Velarde Ruiz Esparza, Luis A.; Wang, Weina; Yang, Ping; Thevuthasan, Suntharampillai; Wang, Hongfei

    2013-11-21

    Carboxylic acid is a common ligand anchoring group to functionalize nanoparticle surfaces. Its binding structures and mechanisms as a function of the oxidation states of metal oxide nanoparticle surfaces are not well characterized experimentally. We present an in situ sum frequency generation vibrational spectroscopy (SFG-VS) study on the binding of deuterated acetic acid on ceria nanoparticles in the aqueous solution. In the SFG experiment, ceria nanoparticles were deposited on the flat surface of a CaF2 hemisphere in contact with acetic acid solutions. While the ceria nanoparticle deprotonated the acetic acid, the CaF2 surface could not. Thus, the binding of the deprotonated acetic acid on ceria can be selectively probed. SFG spectra revealed that the binding modes of the carboxylate group depend on the oxidation states of the ceria surfaces. SFG polarization analysis suggested that the bidentate chelating and bridging binding modes co-exist on the reduced ceria surfaces, while the oxidized ceria surfaces are dominated by the bidentate bridging mode. The direct spectroscopic evidence helps to clarify the binding structures and mechanisms on the ceria nanoparticles. Furthermore, the middle-infrared (IR) transparent CaF2 and its chemical inertness make CaF2 and similar substrate materials good candidates for direct SFG-VS measurement of nanoparticle surface reactions and binding chem-istry.

  14. Polycomb Group (PcG) Proteins and Human Cancers: Multifaceted Functions and Therapeutic Implications.

    PubMed

    Wang, Wei; Qin, Jiang-Jiang; Voruganti, Sukesh; Nag, Subhasree; Zhou, Jianwei; Zhang, Ruiwen

    2015-11-01

    Polycomb group (PcG) proteins are transcriptional repressors that regulate several crucial developmental and physiological processes in the cell. More recently, they have been found to play important roles in human carcinogenesis and cancer development and progression. The deregulation and dysfunction of PcG proteins often lead to blocking or inappropriate activation of developmental pathways, enhancing cellular proliferation, inhibiting apoptosis, and increasing the cancer stem cell population. Genetic and molecular investigations of PcG proteins have long been focused on their PcG functions. However, PcG proteins have recently been shown to exert non-classical-Pc-functions, contributing to the regulation of diverse cellular functions. We and others have demonstrated that PcG proteins regulate the expression and function of several oncogenes and tumor suppressor genes in a PcG-independent manner, and PcG proteins are associated with the survival of patients with cancer. In this review, we summarize the recent advances in the research on PcG proteins, including both the Pc-repressive and non-classical-Pc-functions. We specifically focus on the mechanisms by which PcG proteins play roles in cancer initiation, development, and progression. Finally, we discuss the potential value of PcG proteins as molecular biomarkers for the diagnosis and prognosis of cancer, and as molecular targets for cancer therapy. PMID:26227500

  15. The synthesis of desired functional groups on PEI microgel particles for biomedical and environmental applications

    NASA Astrophysics Data System (ADS)

    Sahiner, Nurettin; Demirci, Sahin; Sahiner, Mehtap; Al-Lohedan, Hamad

    2015-11-01

    Polyethyleneimine (PEI) microgels were synthesized by micro emulsion polymerization technique and converted to positively charged forms by chemical treatments with various modifying agents with different functional groups, such as 2-bromoethanol (-OH), 4-bromobutyronitrile (-CN), 2-bromoethylamine hydrobromide (-NH2), and glycidol (-OH). The functionalization of PEI microgels was confirmed by FT-IR, TGA and zeta potential measurements. Furthermore, a second modification of the modified PEI microgels was induced on 4-bromo butyronitrile-modified PEI microgels (PEI-CN) by amidoximation, to generate new functional groups on the modified PEI microgels. The PEI and modified PEI microgels were also tested for their antimicrobial effects against various bacteria such as Bacillus subtilis ATCC 6633, Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 25323. Moreover, the PEI-based particles were used for removal of organic dyes such as methyl orange (MO) and congo red (CR). The absorption capacity of PEI-based microgels increased with modification from 101.8 mg/g to 218.8 mg/g with 2-bromoethylamine, 216.2 m/g with 1-bromoethanol, and 224.5 mg/g with 4-bromobutyronitrile for MO. The increase in absorption for CR dyes was from 347.3 mg/g to 390.4 mg/g with 1-bromoethanol, 399.6 mg/g with glycidol, and 349.9 mg/g with 4-bromobutyronitrile.

  16. Poly[[nona­aqua­bis­(?-5-hy­droxy­benzene-1,3-di­carboxyl­ato)(5-hy­droxy­benzene-1,3-di­carboxyl­ato)dicerium(III)] hexa­hydrate

    PubMed Central

    Fan, Xiao; Daiguebonne, Carole; Guillou, Olivier; Camara, Magatte

    2014-01-01

    In the title coordination polymer, {[Ce2(C8H4O5)3(H2O)9]·6H2O}n, the asymmetric unit is formed by two CeIII atoms, three 5-hy­droxy­benzene-1,3-di­carboxyl­ate ligands, nine coordinating water mol­ecules and six water mol­ecules of crystallization. The two CeIII atoms are bridged by 5-hy­droxy­benzene-1,3-di­carboxyl­ate 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 carboxyl­ate groups of two bridging 5-hy­droxy­benzene-1,3-di­carboxyl­ate ligands and five O atoms from water mol­ecules, generating a tricapped trigonal–prismatic geometry. The coordination around the second CeIII atom is similar, except that one of the water mol­ecules is replaced by an O atom from an additional 5-hy­droxy­benzene-1,3-di­carboxyl­ate ligand acting in a monodentate coordination mode and forming a capped square-anti­prismatic geometry. PMID:24860313

  17. In vitro antioxidant activities of low-molecular-weight polysaccharides with various functional groups.

    PubMed

    Chen, Szu Kai; Tsai, Min Lang; Huang, Jin Ru; Chen, Rong Huei

    2009-04-01

    The objectives of this study were to evaluate the effect of different functional groups of sulfate, amine, and hydroxyl and/or their ionized groups on in vitro antioxidant capacities of low-molecular-weight polysaccharides (LMPS) prepared from agar (LMAG), chitosan (LMCH), and starch (LMST), respectively, and to elucidate their structure-activity relationship. Ascorbic acid and ethylenediaminetetraacetic acid (EDTA) were used as positive controls. The in vitro antioxidant capacities of LMAG and LMCH were higher than that of LMST in the DPPH radical, superoxide radical, hydrogen peroxide, and nitric oxide radical scavenging and ferrous metal-chelating capacities. The different scavenging capacities may be due to the combined effects of the different sizes of the electron-cloud density and the different accessibility between free radical and LMPS, which, in turn, depends upon the different hydrophobicities of the constituent sugars. PMID:19256513

  18. Ecological Significance of a Geomorphic Stream Classification: Species and Functional Group Composition of Riparian Plant Communities

    NASA Astrophysics Data System (ADS)

    Shaw, J. R.; Cooper, D. J.

    2014-12-01

    We tested the ecological significance of a geomorphic classification of Sonoran Desert ephemeral stream channels based on channel plan-form, degree of lateral confinement, and boundary material composition. This typology has been shown to discriminate among channel geometry and hydraulic characteristics for bedrock, bedrock with alluvium, incised alluvium, braided, and piedmont headwater channels. We examined stream reach-scale relationships of geomorphic stream types to the relative cover and density of perennial plant species and functional groups, and identified the dominant fluvial drivers, within riparian communities at 101 ephemeral stream reaches on the U.S. Army Yuma Proving Ground and Barry M. Goldwater Air Force Range in southwestern Arizona, USA. Nonparametric multivariate analysis of variance showed that species and functional group composition differed significantly among geomorphic stream types, both in terms of relative cover and density. Partitioning of among-site multivariate dissimilarity revealed that species compositional differences between stream types were caused largely by variation in the cover and density of the most common members of the regional flora. Distinctive functional group composition among reach types resulted from differences in the cover and density of drought-deciduous shrubs and subshrubs, evergreen trees and shrubs, and photosynthetic-stemmed trees. Comparison of environmental and biotic dissimilarity matrices highlighted the role of channel gradient as the dominant abiotic driver of riparian plant community composition, with stream channel elevation and width:depth providing additional explanatory power. Distinctive riparian plant community composition among the geomorphic stream types demonstrates the ecological significance of this a priori channel classification, and indicates its potential utility in understanding spatial patterns of ecological dynamics, sample stratification for process-based studies, and reference site selection.

  19. 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

  20. Acidity of the amidoxime functional group in aqueous solution. A combined experimental and computational study

    DOE PAGESBeta

    Mehio, Nada; Lashely, Mark A.; Nugent, Joseph W.; Tucker, Lyndsay; Correia, Bruna; Do-Thanh, Chi-Linh; Dai, Sheng; Hancock, Robert D.; Bryantsev, Vyacheslav S.

    2015-01-26

    Poly(acrylamidoxime) adsorbents are often invoked in discussions of mining uranium from seawater. It has been demonstrated repeatedly in the literature that the success of these materials is due to the amidoxime functional group. While the amidoxime-uranyl chelation mode has been established, a number of essential binding constants remain unclear. This is largely due to the wide range of conflicting pKa values that have been reported for the amidoxime functional group in the literature. To resolve this existing controversy we investigated the pKa values of the amidoxime functional group using a combination of experimental and computational methods. Experimentally, we used spectroscopicmore »titrations to measure the pKa values of representative amidoximes, acetamidoxime and benzamidoxime. Computationally, we report on the performance of several protocols for predicting the pKa values of aqueous oxoacids. Calculations carried out at the MP2 or M06-2X levels of theory combined with solvent effects calculated using the SMD model provide the best overall performance with a mean absolute error of 0.33 pKa units and 0.35 pKa units, respectively, and a root mean square deviation of 0.46 pKa units and 0.45 pKa units, respectively. Finally, we employ our two best methods to predict the pKa values of promising, uncharacterized amidoxime ligands. Hence, our study provides a convenient means for screening suitable amidoxime monomers for future generations of poly(acrylamidoxime) adsorbents used to mine uranium from seawater.« less

  1. Functional renormalization group approach to conventional theory of superfluidity and beyond

    E-print Network

    Yuya Tanizaki; Gergely Fej?s; Tetsuo Hatsuda

    2014-01-29

    Fermionic functional renormalization group (FRG) is applied to describe the superfluid phase transition of the two-component fermionic system with attractive contact interaction. Connection between the fermionic FRG approach and the Bardeen-Cooper-Schrieffer (BCS) theory with its Gorkov and Melik-Barkhudarov (GMB) correction is made clear, and the FRG flow of the fermion self-energy is also studied to go beyond the BCS+GMB theory. The superfluid transition temperature and the associated chemical potential are calculated in the region of the negative scattering length using fermionic FRG.

  2. Towards a Renormalization Group Approach to Density Functional Theory - General Formalism and Case Studies -

    E-print Network

    Sandra Kemler; Jens Braun

    2015-03-06

    We discuss a two-point particle irreducible (2PPI) approach to many-body physics which relies on a renormalization group (RG) flow equation for the associated effective action. In particular, the general structure and properties of this RG flow equation are analyzed in detail. Moreover, we discuss how our 2PPI RG approach relates to Density Functional Theory and argue that it can in principle be used to study ground-state properties of non-relativistic many-body systems from microscopic interactions, such as (heavy) nuclei. For illustration purposes, we use our formalism to compute the ground-state properties of two toy models.

  3. Nonlinear optical properties of copolyesters containing azobenzene functionality and chiral groups

    NASA Astrophysics Data System (ADS)

    Bahulayan, D.; Thomas, Vinoy; Sreekumar, K.

    1998-04-01

    The synthesis and characterization of a series of new copolyesters containing azo mesogenic groups and chiral building blocks are reported. The polyesters were prepared by the condensation of bis(4-hydroxyphenyl)azo 2,2'- dinitro(3,5,3',5'-tetramethyl)diphenylmethane, terephthaloyl chloride and 1,4;3,6-dianhydro-D-sorbitol. The polysters showed higher thermal and photochemical stability with high values of glass transition temperature. DSC studies showed liquid crystalline behavior over a wide range. High values of second order nonlinear susceptibilities were recorded as a function of the molar proportion of isosorbide units.

  4. Summing parquet diagrams using the functional renormalization group: X-ray problem revisited

    NASA Astrophysics Data System (ADS)

    Lange, Philipp; Drukier, Casper; Sharma, Anand; Kopietz, Peter

    2015-10-01

    We present a simple method for summing so-called parquet diagrams of fermionic many-body systems with competing instabilities using the functional renormalization group. Our method is based on partial bosonization of the interaction using multi-channel Hubbard-Stratonovich transformations. A simple truncation of the resulting flow equations, retaining only the frequency-independent parts of the two-point and three-point vertices amounts to solving coupled Bethe-Salpeter equations for the effective interaction to leading logarithmic order. We apply our method by revisiting the X-ray problem and deriving the singular frequency dependence of the X-ray response function and the particle-particle susceptibility. Our method is quite general and should be useful in many-body problems involving strong fluctuations in several scattering channels.

  5. Functional groups in a single pteridosperm species: Variability and circumscription (Pennsylvanian, Nova Scotia, Canada)

    USGS Publications Warehouse

    Zodrow, E.L.; Mastalerz, Maria

    2007-01-01

    Multiple foliar specimens of the Late Pennsylvanian fossil pteridosperm [gymnosperm] Alethopteris zeilleri (Ragot) Wagner were collected from one restricted stratigraphical horizon in the Canadian Sydney Coalfield. Variability of functional-group distribution using FTIR technique was studied in compressions, adaxial versus abaxial cuticles, and in unseparated cuticles as a function of maceration time from 48 to 168??h. The results obtained document spectral variability that could be expected within specimens of one species. For example, CH2/CH3 and Al/ox ratios can differ by as much as 20% of the values. Moreover, the experiments performed confirm that by using a previously established maceration protocol, long maceration periods do not bias FTIR spectra in terms of oxygenation overprinting. The inference that this cuticle is robust, under the given diagenetic level, probably reflects a reassuring degree of chemical fidelity of the Pennsylvanian plant to support Carboniferous chemotaxonomic observations. ?? 2006 Elsevier B.V. All rights reserved.

  6. 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

  7. 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

  8. Physics and the choice of regulators in functional renormalisation group flows

    E-print Network

    Pawlowski, Jan M; Schmidt, Richard; Wetzel, Sebastian J

    2015-01-01

    The Renormalisation Group is a versatile tool for the study of many systems where scale-dependent behaviour is important. Its functional formulation can be cast into the form of an exact flow equation for the scale-dependent effective action in the presence of an infrared regularisation. The functional RG flow for the scale-dependent effective action depends explicitly on the choice of regulator, while the physics does not. In this work, we systematically investigate three key aspects of how the regulator choice affects RG flows: (i) We study flow trajectories along closed loops in the space of action functionals varying both, the regulator scale and shape function. Such a flow does not vanish in the presence of truncations. Based on a definition of the length of an RG trajectory, we suggest a practical procedure for devising optimised regularisation schemes within a truncation. (ii) In systems with various field variables, a choice of relative cutoff scales is required. At the example of relativistic bosonic...

  9. Chemolithoautotrophy and mixotrophy in the thiophene-2-carboxylic acid-utilizing xanthobacter tagetidis

    PubMed

    Padden; Kelly; Wood

    1998-03-01

    Xanthobacter tagetidis grew as a chemolithotrophic autotroph on thiosulfate and other inorganic sulfur compounds, as a heterotroph on thiophene-2-carboxylic acid, acetic acid and alpha-ketoglutaric acid, and as a mixotroph on thiosulfate in combination with thiophene-2-carboxylic acid and/or acetic acid. Autotrophic growth on one-carbon organosulfur compounds, and intermediates in their oxidation are also reported. Thiosulfate enhanced the growth yields in mixotrophic cultures, presumably by acting as a supplementary energy source, since ribulose bisphosphate carboxylase was only active in thiosulfate-grown cells and was not detected in mixotrophic cultures using thiosulfate with thiophene-2-carboxylic acid. Bacteria grown on thiophene-2-carboxylic acid also oxidized sulfide, thiosulfate and tetrathionate, indicating these as possible sulfur intermediates in thiophene-2-carboxylic acid degradation. Thiosulfate and tetrathionate were oxidized completely to sulfate and, consequently, did not accumulate as products of thiophene-2-carboxylic acid oxidation in growing cultures. Km and Vmax values for the oxidation of thiosulfate, tetrathionate or sulfide were 13 &mgr;M and 83 nmol O2 min-1 (mg dry wt.)-1, respectively; thiosulfate and tetrathionate became autoinhibitory at concentrations above 100 &mgr;M. The true growth yield (Ymax) on thiophene-2-carboxylic acid was estimated from chemostat cultures (at dilution rates of 0.034-0.094 h-1) to be 112.2 g mol-1, with a maintenance coefficient (m) of 0.3 mmol thiophene-2-carboxylic acid (g dry wt.)-1 h-1, and the maximum specific growth rate (&mgr;max) was 0.116 h-1. Growth in chemostat culture at a dilution rate of 0. 041 h-1 indicated growth yields [g dry wt. (mol substrate)-1] of 8.1 g (mol thiosulfate)-1, 60.9 g (mol thiophene-2-carboxylic acid)-1, and 17.5 g (mol acetic acid)-1, with additive yields for growth on mixtures of these substrates. At a dilution rate of 0.034 h-1, yields of 57.8 g (mol alpha-ketoglutaric acid)-1 and 60.7 g (mol thiophene-2-carboxylic acid)-1 indicated some additional energy conservation from oxidation of the thiophene-sulfur. SDS-PAGE of cell-free preparations indicated a polypeptide (Mr, 21.0 kDa) specific to growth on thiophene-2-carboxylic acid for which no function can yet be ascribed: no metabolism of thiophene-2-carboxylic acid by cell-free extracts was detected. It was shown that X. tagetidis exhibits a remarkable degree of metabolic versatility and is representative of facultatively methylotrophic and chemolithotrophic autotrophs that contribute significantly to the turnover of simple inorganic and organic sulfur compounds (including substituted thiophenes) in the natural environment. PMID:9477260

  10. Synthesis, algal inhibition activities and QSAR studies of novel gramine compounds containing ester functional groups

    NASA Astrophysics Data System (ADS)

    Li, Xia; Yu, Liangmin; Jiang, Xiaohui; Xia, Shuwei; Zhao, Haizhou

    2009-05-01

    2,5,6-Tribromo-1-methylgramine (TBG), isolated from bryozoan Zoobotryon pellucidum was shown to be very efficient in preventing recruitment of larval settlement. In order to improve the compatibility of TBG and its analogues with other ingredients in antifouling paints, structural modification of TBG was focused mainly on halogen substitution and N-substitution. Two halogen-substitute gramines and their derivatives which contain ester functional groups at N-position of gramines were synthesized. Algal inhibition activities of the synthesized compounds against algae Nitzschia closterium were evaluated and the Median Effective Concentration (EC50) range was 1.06-6.74 ?g ml-1. Compounds that had a long chain ester group exhibited extremely high antifouling activity. Quantitive Structure Activity Relationship (QSAR) studies with multiple linear regression analysis were applied to find correlation between different calculated molecular descriptors and biological activity of the synthesized compounds. The results show that the toxicity (log (1/EC50)) is correlated well with the partition coefficient log P. Thus, these products have potential function as antifouling agents.

  11. Voluntary leadership roles in religious groups and rates of change in functional status during older adulthood

    PubMed Central

    Krause, Neal

    2013-01-01

    Linear growth curve modeling was used to compare rates of change in functional status between three groups of older adults: Individuals holding voluntary lay leadership positions in a church, regular church attenders who were not leaders, and those not regularly attending church. Functional status was tracked longitudinally over a 4-year period in a national sample of 1,152 Black and White older adults whose religious backgrounds were either Christian or unaffiliated. Leaders had significantly slower trajectories of increase in both the number of physical impairments and the severity of those impairments. Although regular church attenders who were not leaders had lower mean levels of impairment on both measures, compared with those not regularly attending church, the two groups of non-leaders did not differ from one another in their rates of impairment increase. Leadership roles may contribute to longer maintenance of physical ability in late life, and opportunities for voluntary leadership may help account for some of the health benefits of religious participation. PMID:23606309

  12. Acidity of the amidoxime functional group in aqueous solution: a combined experimental and computational study.

    PubMed

    Mehio, Nada; Lashely, Mark A; Nugent, Joseph W; Tucker, Lyndsay; Correia, Bruna; Do-Thanh, Chi-Linh; Dai, Sheng; Hancock, Robert D; Bryantsev, Vyacheslav S

    2015-02-26

    Poly(acrylamidoxime) adsorbents are often invoked in discussions of mining uranium from seawater. While the amidoxime-uranyl chelation mode has been established, a number of essential binding constants remain unclear. This is largely due to the wide range of conflicting pK(a) values that have been reported for the amidoxime functional group. To resolve this existing controversy we investigated the pK(a) values of the amidoxime functional group using a combination of experimental and computational methods. Experimentally, we used spectroscopic titrations to measure the pK(a) values of representative amidoximes, acetamidoxime, and benzamidoxime. Computationally, we report on the performance of several protocols for predicting the pK(a) values of aqueous oxoacids. Calculations carried out at the MP2 or M06-2X levels of theory combined with solvent effects calculated using the SMD model provide the best overall performance, with a root-mean-square deviation of 0.46 pK(a) units and 0.45 pK(a) units, respectively. Finally, we employ our two best methods to predict the pK(a) values of promising, uncharacterized amidoxime ligands, which provides a convenient means for screening suitable amidoxime monomers for future generations of poly(acrylamidoxime) adsorbents. PMID:25621618

  13. Chemical Assignment of Symmetry-Adapted Perturbation Theory Interaction Energy Components: The Functional-Group SAPT Partition.

    PubMed

    Parrish, Robert M; Parker, Trent M; Sherrill, C David

    2014-10-14

    Recently, we introduced an effective atom-pairwise partition of the many-body symmetry-adapted perturbation theory (SAPT) interaction energy decomposition, producing a method known as atomic SAPT (A-SAPT) [Parrish, R. M.; Sherrill, C. D. J. Chem. Phys. 2014, 141, 044115]. A-SAPT provides ab initio atom-pair potentials for force field development and also automatic visualizations of the spatial contributions of noncovalent interactions, but often has difficulty producing chemically useful partitions of the electrostatic energy, due to the buildup of oscillating partial charges on adjacent functional groups. In this work, we substitute chemical functional groups in place of atoms as the relevant local quasiparticles in the partition, resulting in a functional-group-pairwise partition denoted as functional-group SAPT (F-SAPT). F-SAPT assigns integral sets of local occupied electronic orbitals and protons to chemical functional groups and linking ? bonds. Link-bond contributions can be further assigned to chemical functional groups to simplify the analysis. This approach yields a SAPT partition between pairs of functional groups with integral charge (usually neutral), preventing oscillations in the electrostatic partition. F-SAPT qualitatively matches chemical intuition and the cut-and-cap fragmentation technique but additionally yields the quantitative many-body SAPT interaction energy. The conceptual simplicity, chemical utility, and computational efficiency of F-SAPT is demonstrated in the context of phenol dimer, proflavine(+)-DNA intercalation, and a cucurbituril host-guest inclusion complex. PMID:26588139

  14. Anisotropic adsorption and distribution of immobilized carboxyl on nanodiamond.

    PubMed

    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. PMID:25340582

  15. Extracytoplasmic function ? factors of the widely distributed group ECF41 contain a fused regulatory domain

    PubMed Central

    Wecke, Tina; Halang, Petra; Staro?, Anna; Dufour, Yann S; Donohue, Timothy J; Mascher, Thorsten

    2012-01-01

    Bacteria need signal transducing systems to respond to environmental changes. Next to one- and two-component systems, alternative ? factors of the extra-cytoplasmic function (ECF) protein family represent the third fundamental mechanism of bacterial signal transduction. A comprehensive classification of these proteins identified more than 40 phylogenetically distinct groups, most of which are not experimentally investigated. Here, we present the characterization of such a group with unique features, termed ECF41. Among analyzed bacterial genomes, ECF41 ? factors are widely distributed with about 400 proteins from 10 different phyla. They lack obvious anti-? factors that typically control activity of other ECF ? factors, but their structural genes are often predicted to be cotranscribed with carboxymuconolactone decarboxylases, oxidoreductases, or epimerases based on genomic context conservation. We demonstrate for Bacillus licheniformis and Rhodobacter sphaeroides that the corresponding genes are preceded by a highly conserved promoter motif and are the only detectable targets of ECF41-dependent gene regulation. In contrast to other ECF ? factors, proteins of group ECF41 contain a large C-terminal extension, which is crucial for ? factor activity. Our data demonstrate that ECF41 ? factors are regulated by a novel mechanism based on the presence of a fused regulatory domain. PMID:22950025

  16. 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.

  17. Montane meadow change during drought varies with background hydrologic regime and plant functional group.

    PubMed

    Debinski, Diane M; Wickham, Hadley; Kindscher, Kelly; Caruthers, Jennet C; Germino, Matthew

    2010-06-01

    Climate change models for many ecosystems predict more extreme climatic events in the future, including exacerbated drought conditions. Here we assess the effects of drought by quantifying temporal variation in community composition of a complex montane meadow landscape characterized by a hydrological gradient. The meadows occur in two regions of the Greater Yellowstone Ecosystem (Gallatin and Teton) and were classified into six categories (M1-M6, designating hydric to xeric) based upon Satellite pour l'Observation de la Terre (SPOT) satellite imagery. Both regions have similar plant communities, but patch sizes of meadows are much smaller in the Gallatin region. We measured changes in the percent cover of bare ground and plants by species and functional groups during five years between 1997 and 2007. We hypothesized that drought effects would not be manifested evenly across the hydrological gradient, but rather would be observed as hotspots of change in some areas and minimally evident in others. We also expected varying responses by plant functional groups (forbs vs. woody plants). Forbs, which typically use water from relatively shallow s,oils compared to woody plants, were expected to decrease in cover in mesic meadows, but increase in hydric meadows. Woody plants, such as Artemisia, were expected to increase, especially in mesic meadows. We identified several important trends in our meadow plant communities during this period of drought: (1) bare ground increased significantly in xeric meadows of both regions (Gallatin M6 and Teton M5) and in mesic (M3) meadows of the Teton, (2) forbs decreased significantly in the mesic and xeric meadows in both regions, (3) forbs increased in hydric (M1) meadows of the Gallatin region, and (4) woody species showed increases in M2 and M5 meadows of the Teton region and in M3 meadows of the Gallatin region. The woody response was dominated by changes in Artemisia spp. and Chrysothamnus viscidiflorus. Thus, our results supported our expectations that community change was not uniform across the landscape, but instead could be predicted based upon functional group responses to the spatial and temporal patterns of water availability, which are largely a function of plant water use and the hydrological gradient. PMID:20583709

  18. 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

  19. Conformation of carboxylated schizophyllan in aqueous solution.

    PubMed

    Yoshiba, Kazuto; Sato, Takahiro; Osumi, Takaaki; Ulset, Ann-Sissel T; Christensen, Bjørn E

    2015-12-10

    Carboxylated schizophyllan (sclerox) samples of different degrees of oxidation were molecularly characterized by size exclusion chromatography equipped with a multi-angle light scattering detector (SEC-MALS) in 0.10M aqueous NaCl solution. The molar mass distribution obtained by SEC-MALS shows that sclerox of low degree of oxidation is dissolved mainly as the trimer, whereas the trimer and single chain coexist in solution of sclerox of high degree of oxidation. The trimer of sclerox is much more flexible than the fully ordered triple helix of the parent schizophyllan and easily dissociates into single chains upon heating. PMID:26428092

  20. 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