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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

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

PubMed

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

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

2007-12-12

3

Gas-Phase Reactivity of Carboxylic Acid Functional Groups with Carbodiimides  

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

4

Hydrogel with chains functionalized with carboxyl groups as universal 3D platform in DNA biosensors.  

PubMed

Application of hydrogel based on N-isopropylacrylamide with carboxyl groups grafted to the chains enabled the immobilization of DNA at an extent exceeding that for flat surfaces by at least one order of magnitude. The probe DNA strands in the 3D platform were fully available for the hybridization process. The examination of the gels containing different amounts of grafted carboxyl groups (1-10%) was done using quartz crystal microbalance, electrochemical impedance spectroscopy, chronoamperometry and ionic coupled plasma with laser ablation. The optimal carboxyl group content was determined to be 5%. A very good agreement of the data obtained with independent techniques on content of DNA in the gel was obtained. In comparison to the other methods of immobilization of DNA the new platform enabled complete removal of DNA after the measurements and analysis and, therefore, could be used many times. After a 10-fold exchange of the DNA-sensing layer the efficiency of hybridization and analytical signal did not change by more than 5%. The sensor response increased linearly with logarithm of concentration of target DNA in the range 1×10(-13)-1×10(-6) M. The obtained detection limit was circa 8×10(-13) M of target DNA in the sample which is a substantial improvement over the planar sensing layers. PMID:24287408

Kowalczyk, Agata; Fau, Michal; Karbarz, Marcin; Donten, Mikolaj; Stojek, Zbigniew; Nowicka, Anna M

2014-04-15

5

Fluorescence quantum efficiency of CdSe/CdS magic-sized quantum dots functionalized with carboxyl or hydroxyl groups  

NASA Astrophysics Data System (ADS)

The present letter reports the thermo-optical properties of functionalized CdSe/CdS magic-sized quantum dots (MSQDs) (sizes 1.9-2.3 nm) with carboxyl (R-COOH) or hydroxyl (R-OH) groups in aqueous solutions. Atomic force microscopy and infrared transmittance measurements were used to determine the size of the QDs and to highlight the functionalized groups. Absolute nonradiative quantum efficiency (?) and radiative quantum efficiency (?) values were determined by applying two techniques: thermal lens (TL) and an alternative method that analyzes the ring patterns generated in a laser beam due to thermally induced self-phase-modulation effects known as the conical diffraction. Fluorescence measurements corroborate the TL results.

Pilla, Viviane; de Lima, Sthanley R.; Andrade, Acácio A.; Silva, Anielle C. A.; Dantas, Noelio O.

2013-08-01

6

Thermoreversible hydrogels based on triblock copolymers of poly(ethylene glycol) and carboxyl functionalized poly(?-caprolactone): The effect of carboxyl group substitution on the transition temperature and biocompatibility in plasma.  

PubMed

In this study we report on the development, characterization and plasma protein interaction of novel thermoresponsive in situ hydrogels based on triblock copolymers of poly(ethylene glycol) (PEG) and poly(?-carboxyl-co-benzyl carboxylate)-?-caprolactone (PCBCL) having two different degrees of carboxyl group substitution on the PCBCL block. Block copolymers were synthesized through ring-opening polymerization of ?-benzyl carboxylate-?-caprolactone by dihydroxy PEG, leading to the production of poly(?-benzyl carboxylate-?-caprolactone)-PEG-poly(?-benzyl carboxylate-?-caprolactone) (PBCL-PEG-PBCL). This was followed by partial debenzylation of PBCL blocks under controlled conditions, leading to the preparation of PCBCL-PEG-PCBCL triblock copolymers with 30 and 54mol.% carboxyl group substitution. Prepared PCBCL-PEG-PCBCL block copolymers have been shown to have a concentration-dependent sol to gel transition as a result of an increase in temperature above ?29°C, as evidenced by the inverse flow method, differential scanning calorimetry and dynamic mechanical analysis. The sol-gel transition temperature/concentration and dynamic mechanical properties of the gel were found to be dependent on the level of carboxyl group substitution. Both hydrogels (30 and 54mol.% carboxyl group substitution) showed similar amounts of protein adsorption but striking differences in the profiles of the adsorbed proteome. Additionally, the two systems showed similarities in their clot formation kinetics but substantial differences in clot endpoints. The results show great promise for the above-mentioned thermoreversible in situ hydrogels as biocompatible materials for biomedical applications. PMID:25451305

Nikouei, Nazila Safaei; Vakili, Mohammad Reza; Bahniuk, Markian S; Unsworth, Larry; Akbari, Ali; Wu, Jianping; Lavasanifar, Afsaneh

2015-01-15

7

Use of carboxylic group functionalized magnetic nanoparticles for the preconcentration of metals in juice samples prior to the determination by capillary electrophoresis.  

PubMed

Nowadays food industry demands reliable and precise methods to resolve problems related to quality and security control. The pretreatment steps, prior to sample analysis, are necessary to extract the target analytes because of the complexities of the food samples matrices. In this work, we have studied, for the first time, the potential of carboxylic group functionalized magnetic nanoparticles to preconcentrate metals from liquid samples before CE analysis. For the extraction of metals, 10 mL of an aqueous sample containing the metal mixture was added to 2 mg carboxylic group functionalized magnetic nanoparticles. Metals retained in the nanoparticles were re-extracted with 200 ?L solution consisting of 0.8 mM 1,10-phenanthroline and 0.04% hydroxylamine chloride at pH 2. The electrophoretic buffer used in this work to separate different metals (Co, Cu, Zn, Ni, and Cd) consisted of 30 mM hydroxylamine chloride, 0.30 mM 1,10-phenanthroline, 80 mM urea, 15 mM ammonium chloride, and 0.1% methanol at pH 3.6. Finally, measurements were made at 270 nm. Under the optimized conditions, detection limits for Co, Zn, Cu, Ni, and Cd were 0.004, 0.003, 0.004, 0.008, and 0.009 mg L(-1) , respectively. PMID:22887167

Carpio, Azahara; Mercader-Trejo, Flora; Arce, Lourdes; Valcárcel, Miguel

2012-08-01

8

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) ...

9

Conjugation of enzyme on superparamagnetic nanogels covered with carboxyl groups.  

PubMed

Alpha-chymotrypsin (CT) as model enzyme was conjugated onto the novel carboxyl-functionalized superparamagnetic nanogels, prepared via facile photochemical in situ polymerization, by using 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide (EDC) as coupling reagent. The obtained magnetic immobilized enzyme was characterized by use of photo correlation spectroscopy (PCS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) measurement, thermogravimetric (TG) analysis and vibrating sample magnetometer (VSM) measurement. PCS result showed that the immobilized enzyme was 68 nm in diameter while the magnetic nanogels with carboxyl groups were only 38 nm; enzyme immobilization led to pronounced change in size. Superparamagnetic properties were retained for Fe3O4 after enzyme immobilization while slightly reducing its value of saturation magnetization. Immobilization and surface coating did not induce phase change of Fe3O4 by XRD analysis. The binding capacity was 30 mg enzyme/g and 37.5 mg enzyme/g nanogel determined by TG analysis and BCA protein assay, respectively. Specific activity of the immobilized CT was calculated to be 0.77 U/(mg min), 82.7% as that of the free form. PMID:17241826

Hong, Jun; Xu, Dongmei; Gong, Peijun; Ma, Hongjuan; Dong, Li; Yao, Side

2007-05-01

10

Highly visible-light luminescence properties of the carboxyl-functionalized short and ultrashort MWNTs  

SciTech Connect

Luminescence of the short multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups has been studied. The results show that the carboxyl-functionalized short MWNTs could emit luminescence and the emission peak appears at 500 nm with a corresponding optimal excitation wavelength centering at 310 nm. When the short MWNTs are filtered through 0.15 {mu}m polytetrafluoroethylene (PTFE) membrane, the ultrashort MWNTs are obtained from the filtrate. An interesting feature for the ultrashort MWNTs is that the emission intensity is strengthened and the peak is slightly blue shifted to 460 nm. This result indicates that the luminescence properties of MWNTs are strongly affected by the tube length. After chemical oxidization cutting, defects and carboxylic acid groups at the tube end and/or sidewall can be produced; the more shorten of MWNTs, the better dispersion and carboxylic passivation of the nanotubes, and the more intense luminescence emissions. The broad emissions are logically attributed to the trapping of excitation energy by defect sites in the carboxyl-functionalized nanotube structure. - Graphical abstract: Luminescence of the short and ultrashort multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups, which is logically attributed to the trapping of excitation energy by defect sites, has been studied.

Luo Yongsong [Department of Physics, Central China Normal University, Wuhan 430079 (China); Department of Physics, XinYang Normal University, Xinyang 464000 (China)], E-mail: ysluo@mails.ccnu.edu.cn; Xia Xiaohong [Department of Physics, Central China Normal University, Wuhan 430079 (China); Liang Ying [Department of Physics, Central China Normal University, Wuhan 430079 (China); Zhang Yonggang [Department of Physics, Central China Normal University, Wuhan 430079 (China); Ren Qinfeng [Department of Physics, Central China Normal University, Wuhan 430079 (China); Li Jialin [Department of Physics, Central China Normal University, Wuhan 430079 (China)], E-mail: lijl@phy.ccnu.edu.cn; Jia Zhijie [Department of Physics, Central China Normal University, Wuhan 430079 (China); Tang Yiwen [Department of Physics, Central China Normal University, Wuhan 430079 (China)

2007-06-15

11

Functionalized carboxyl nanoparticles enhance mucus dispersion and hydration  

PubMed Central

Luminal accumulation of viscous, poorly hydrated, and less transportable mucus has been associated with altered mucus rheology and reduced mucociliary clearance. These symptoms are some of the cardinal clinical manifestations found throughout major respiratory diseases as well as gastrointestinal and digestive disorders. Applications of current mucolytics may yield short-term improvements but are continuously challenged by undesirable side-effects. While nanoparticles (NPs) can interact with mucin polymers, whether functionalized NPs can rectify mucus rheology is unknown. Herein, we report that carboxyl-functionalized NPs (24?nm and 120?nm) dramatically reduced mucin gel size and accelerated mucin matrix hydration rate (diffusivity). Our results suggest that carboxyl-functionalized NPs disperse mucin gels possibly by enhancing network hydration. This report highlights the prospective usages of carboxyl-functionalized NPs as a novel mucus dispersant or mucolytic agent in adjusting mucus rheological properties and improving mucociliary transport to relieve clinical symptoms of patients suffering from relevant diseases. PMID:22355725

Chen, Eric Y.; Daley, David; Wang, Yung-Chen; Garnica, Maria; Chen, Chi-Shuo; Chin, Wei-Chun

2012-01-01

12

Functionalized carboxyl nanoparticles enhance mucus dispersion and hydration  

NASA Astrophysics Data System (ADS)

Luminal accumulation of viscous, poorly hydrated, and less transportable mucus has been associated with altered mucus rheology and reduced mucociliary clearance. These symptoms are some of the cardinal clinical manifestations found throughout major respiratory diseases as well as gastrointestinal and digestive disorders. Applications of current mucolytics may yield short-term improvements but are continuously challenged by undesirable side-effects. While nanoparticles (NPs) can interact with mucin polymers, whether functionalized NPs can rectify mucus rheology is unknown. Herein, we report that carboxyl-functionalized NPs (24 nm and 120 nm) dramatically reduced mucin gel size and accelerated mucin matrix hydration rate (diffusivity). Our results suggest that carboxyl-functionalized NPs disperse mucin gels possibly by enhancing network hydration. This report highlights the prospective usages of carboxyl-functionalized NPs as a novel mucus dispersant or mucolytic agent in adjusting mucus rheological properties and improving mucociliary transport to relieve clinical symptoms of patients suffering from relevant diseases.

Chen, Eric Y.; Daley, David; Wang, Yung-Chen; Garnica, Maria; Chen, Chi-Shuo; Chin, Wei-Chun

2012-01-01

13

The hydroxyl group of S685 in Walker A motif and the carboxyl group of D792 in Walker B motif of NBD1 play a crucial role for multidrug resistance protein folding and function  

PubMed Central

Structural analysis of MRP1-NBD1 revealed that the Walker A S685 forms hydrogen-bond with the Walker B D792 and interacts with magnesium and the ?-phosphate of the bound ATP. We have found that substitution of the D792 with leucine resulted in misfolding of the protein. In this report we tested whether substitution of the S685 with residues that prevent formation of this hydrogen-bond would also cause misfolding. Indeed, substitution of the S685 with residues potentially preventing formation of this hydrogen-bond resulted in misfolding of the protein. In addition, some substitutions that might form hydrogen-bond with D792 also yielded immature protein. All these mutants are temperature-sensitive variants. However, these complex-glycosylated mature mutants prepared from the cells grown at 27 °C still significantly affect ATP binding and ATP-dependent solute transport. In contrast, substitution of the S685 with threonine yielded complex-glycosylated mature protein that is more active than the wild-type MRP1, indicating that the interaction between the hydroxyl group of 685 residue and the carboxyl group of D792 plays a crucial role for the protein folding and the interactions of the hydroxyl group at 685 with magnesium and the ?-phosphate of the bound ATP play an important role for ATP-binding and ATP-dependent solute transport. PMID:18088596

Yang, Runying; Scavetta, Robert; Chang, Xiu-bao

2010-01-01

14

Carboxylate-functionalized phosphomolybdates: ligand-directed conformations.  

PubMed

The [HPMo6O21](2-) units and carboxylate linkers can be combined to build novel polyanions by a carefully designed complementary system in self-assembly processes depending only on the number of carboxyl groups and the nature of carboxylic acids. Complexes (NH4)5[HPMo6O21(O2CC6H4OH)3]·4H2O (1), (NH4)8H2[(HPMo6O21)2(C2O4)3]·13H2O (2), (NH4)20[(HPMo6O21)4(O2CCH2CO2)6]·17H2O (3), and Cs2(NH4)10[(HPMo6O21)2(HPO3){C6H3(CO2)3}2]·5H2O (4) have been synthesized by a simple one-pot reaction of (NH4)6Mo7O24·4H2O, H3PO3, and carboxylic acid ligands in aqueous solution. Formation of these compounds is critically dependent on the identifying carboxylic acids, which play the important templated role in assembly processes. The stability of these clusters was explored using electrospray ionization mass spectrometry (ESI-MS) and (31)P NMR spectroscopy, and electron paramagnetic resonance (EPR) experiments further demonstrated the result of the interesting photochromic property. PMID:23844943

Yang, Donghui; Li, Suzhi; Ma, Pengtao; Wang, Jingping; Niu, Jingyang

2013-08-01

15

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

16

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

PubMed

Studies of structural changes in peptides and proteins using IR spectroscopy often rely on subtle changes in the amide I' band as a function of temperature. However, these changes can be obscured by the overlap with other absorptions, namely the side-chain and terminal carboxylic groups. The former were the subject of our previous report (Anderson et al., 2014). In this paper we investigate the IR spectra of the asymmetric stretch of ?-carboxylic groups for amino acids representing all major types (Gly, Ala, Val, Leu, Ser, Thr, Asp, Glu, Lys, Asn, His, Trp, Pro) as well as the C-terminal groups of three dipeptides (Gly-Gly, Gly-Ala, Ala-Gly) in D?O at neutral pH. Experimental temperature dependent IR spectra were analyzed by fitting of both symmetric and asymmetric pseudo-Voigt functions. Qualitatively the spectra exhibit shifts to higher frequency, loss in intensity and narrowing with increased temperature, similar to that observed previously for the side-chain carboxylic groups of Asp. The observed dependence of the band parameters (frequency, intensity, width and shape) on temperature is in all cases linear: simple linear regression is therefore used to describe the spectral changes. The spectral parameters vary between individual amino acids and show systematic differences between the free amino acids and dipeptides, particularly in the absolute peak frequencies, but the temperature variations are comparable. The relative variations between the dipeptide spectral parameters are most sensitive to the C-terminal amino acid, and follow the trends observed in the free amino acid spectra. General rules for modeling the ?-carboxylic IR absorption bands in peptides and proteins as the function of temperature are proposed. PMID:25036456

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

2015-01-01

17

Roles of carboxyl groups in the transmembrane insertion of peptides  

PubMed Central

We have used the pHLIP® peptide to study the roles of carboxyl groups in transmembrane peptide insertion. The pH (low) insertion peptide (pHLIP) binds to the surface of a lipid bilayer as a disordered peptide at neutral pH, and when the pH is lowered it inserts across the membrane to form a transmembrane helix. Peptide insertion is reversed when the pH is raised above the characteristic pKa (6.0). A key event facilitating the membrane insertion is the protonation of aspartic (Asp) and/or glutamic (Glu) acid residues, since at neutral pH their negatively charged side chains hinder membrane insertion. In order to gain mechanistic understanding, we studied the membrane insertion and exit of a series of pHLIP variants where the four Asp residues were sequentially mutated to nonacidic residues, including histidine (His). Our results show that the presence of His residues does not prevent the pH-dependent peptide membrane insertion at ~pH 4 driven by the protonation of carboxyl groups at the inserting end of the peptide. A further pH drop leads to the protonation of His residues in the TM part of peptide, which induces peptide exit from the bilayer. We also find that the number of ionizable residues that undergo a change in protonation during membrane insertion correlates with the pH-dependent insertion into and exit from the lipid bilayer, and that cooperativity increases with their number. We expect that our understanding will be used to improve the targeting of acidic diseased tissue by pHLIP peptides. PMID:21888917

Barrera, Francisco N.; Weerakkody, Dhammika; Anderson, Michael; Andreev, Oleg A.; Reshetnyak, Yana K.; Engelman, Donald M.

2011-01-01

18

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  

NASA Astrophysics Data System (ADS)

We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

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.

2011-05-01

19

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  

NASA Astrophysics Data System (ADS)

We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42-. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

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.

2011-09-01

20

Bone tissue response to titanium implant surfaces modified with carboxylate and sulfonate groups  

Microsoft Academic Search

The present study assessed in vivo new bone formation around titanium alloy implants chemically grafted with macromolecules\\u000a bearing ionic sulfonate and\\/or carboxylate groups. Unmodified and grafted Ti–6Al–4V exhibiting either 100% carboxylate, or\\u000a 100% sulfonate, or both carboxylate and sulfonate groups in the percent of 50\\/50 and 80\\/20 were bilaterally implanted into\\u000a rabbit femoral condyle. Neither toxicity nor inflammation were observed

S. Kerner; V. Migonney; G. Pavon-Djavid; G. Helary; L. Sedel; F. Anagnostou

2010-01-01

21

Acidity distribution of carboxyl groups in Loy Yang brown coal: its analysis and the change by heat treatment  

Microsoft Academic Search

Brown coals have a considerable number of acidic functional groups of which the main component is carboxyl groups, and the acidity has a wide distribution. In this paper, changes of the acidity distribution were examined by aqueous titration when brown coal was heat-treated to control its acidity distribution. For Loy Yang brown coal from Australia dried at 50°C under vacuum

Kenji Murakami; Ryuhei Kondo; Kiyoshi Fuda; Toshiaki Matsunaga

2003-01-01

22

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

E-print Network

using chromic acid/sulfuric acid introduces a high density of covalently attached carboxylic acid groupsLangmuir 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

Deutch, John

23

Dispersion of Al 2O 3 suspension with acrylic copolymers bearing carboxylic groups  

Microsoft Academic Search

The interaction between acrylic copolymers carrying carboxylic groups and the surface of an alumina powder in water has been studied. The trends of the adsorption isotherms suggest the formation of a monolayer according to the Langmuir model. The quantity absorbed on the plateau increases when the fraction of carboxylic groups on the polymer decreases. The electrokinetic properties of the alumina

M. Ramzi Ben Romdhane; Sami Boufi; Samir Baklouti; Thierry Chartier; Jean-François Baumard

2003-01-01

24

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

USGS Publications Warehouse

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.

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

1995-01-01

25

Density functional theory study of the oligomerization of carboxylic acids.  

PubMed

We present a density functional theory [M06-2X/6-31+G(d,p)] study of the structures and free energies of formation of oligomers of four carboxylic acids (formic acid, acetic acid, tetrolic acid, and benzoic acid) in water, chloroform, and carbon tetrachloride. Solvation effects were treated using the SMD continuum solvation model. The low-lying energy structures of molecular complexes were located by adopting an efficient search procedure to probe the potential energy surfaces of the oligomers of carboxylic acids (CA)n (n = 2-6). The free energies of the isomers of (CA)n in solution were determined as the sum of the electronic energy, vibrational-rotational-translational gas-phase contribution, and solvation free energy. The assessment of the computational protocol adopted in this study with respect to the dimerization of acetic acid, (AA)2, and formic acid, (FA)2, located new isomers of (AA)2 and (FA)2 and gave dimerization constants in good agreement with the experimental values. The calculation of the self-association of acetic acid, tetrolic acid, and benzoic acid shows the following: (i) Classic carboxylic dimers are the most stable isomer of (CA)2 in both the gas phase and solution. (ii) Trimers of carboxylic acid are stable in apolar aprotic solvents. (iii) Molecular clusters consisting of two interacting classic carboxylic dimers (CA)4,(D+D) are the most stable type of tetramers, but their formation from the self-association of classic carboxylic dimers is highly unfavorable. (iv) For acetic acid and tetrolic acid the reactions (CA)2 + 2CA ? (CA)4,(D+D) and (CA)3 + CA ? (CA)4,(D+D) are exoergonic, but these aggregation pathways go through unstable clusters that could hinder the formation of tetrameric species. (v) For tetrolic acid the prenucleation species that are more likely to form in solution are dimeric and trimeric structures that have encoded structural motifs resembling the ? and ? solid forms of tetrolic acid. (vi) Stable tetramers of benzoic acid could form in carbon tetrachloride from the aggregation of trimers and monomers. (vii) Higher order clusters such as acetic acid pentamers and tetrolic acid hexamers are highly unstable in all solvation environments. PMID:25357019

Di Tommaso, Devis; Watson, Ken L

2014-11-20

26

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

PubMed

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

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

27

Identification and quantification of aerosol polar oxygenated compounds bearing carboxylic or hydroxyl groups. 1. Method development.  

PubMed

In this study, a new analytical technique was developed for the identification and quantification of multifunctional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) of the multifunctional compound using an alcohol (e.g., methanol, 1-butanol) in the presence of a relatively strong Lewis acid (BF3) as a catalyst. This esterification reaction quickly and quantitatively converts carboxylic acids to their ester forms. The second step is based on silylation of the ester compounds using bis(trimethylsilyl) trifluoroacetamide (BSTFA) as the derivatizing agent. For compounds bearing ketone groups in addition to carboxylic and hydroxyl groups, a third step was used based on PFBHA derivatization of the carbonyls. Different parameters including temperature, reaction time, and effect due to artifacts were optimized. A GC/MS in EI and in methane-CI mode was used for the analysis of these compounds. The new approach was tested on a number of multifunctional compounds. The interpretation of their EI (70 eV) and CI mass spectra shows that critical information is gained leading to unambiguous identification of unknown compounds. For example, when derivatized only with BF(3)-methanol, their mass spectra comprise primary ions at m/z M.+ + 1, M.+ + 29, and M.+ - 31 for compounds bearing only carboxylic groups and M.+ + 1, M.+ + 29, M.+ - 31, and M+. - 17 for those bearing hydroxyl and carboxylic groups. However, when a second derivatization (BSTFA) was used, compounds bearing hydroxyl and carboxylic groups simultaneously show, in addition to the ions observed before, ions at m/z M.+ + 73, M.+ - 15, M.+ - 59, M.+ - 75, M.+ - 89, and 73. To the best of our knowledge, this technique describes systematically for the first time a method for identifying multifunctional oxygenated compounds containing simultaneously one or more hydroxyl and carboxylic acid groups. PMID:15307788

Jaoui, M; Kleindienst, T E; Lewandowski, M; Edney, E O

2004-08-15

28

Cowpea mosaic virus for material fabrication: addressable carboxylate groups on a programmable nanoscaffold.  

PubMed

For the first time, decoration of surface-exposed carboxylate groups on Cowpea mosaic virus particles is reported, thus increasing the number and types of addressable surface groups on this nanoscaffold. First, the addressabilty of carboxylates was demonstrated using a carboxylate-selective fluorescent dye, N-cyclohexyl-N'-(4-(dimethylamino)naphthyl)carbodiimide. Second, it was shown that the virions can be decorated with approximately 180 redox active, methyl(aminopropyl)viologen moieties by coupling to the surface carboxylates. The display of multiple redox centers on the virus particle surface may lead to the development of novel electron-transfer mediators in redox catalysis, to biosensors, and to nanoelectronic devices such as molecular batteries. PMID:16584217

Steinmetz, Nicole F; Lomonossoff, George P; Evans, David J

2006-04-11

29

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

USGS Publications Warehouse

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.

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

1995-01-01

30

Quantification of carboxyl groups in carbodiimide cross-linked collagen sponges.  

PubMed

Glutaraldehyde (GA) fixation of bioprosthetic tissue is a well adapted technique, with commercial products on the market for almost 40 years. Amine groups present in tissue react with GA to form different types of cross-links. An estimation of the degree of cross-linking of the tissue can be obtained by measuring the concentration of residual amine groups, which is frequently carried out with the 2,4,6 trinitrobenzene sulphonic acid (TNBS) assay. Cross-linked tissue and collagen matrices are usually further characterized by determining their physical properties (such as the shrinkage temperature), biological properties (such as resistance to enzymatic degradation), and mechanical properties before in vivo evaluation takes place. In an effort to improve the properties of cross-linked tissue and collagen, alternative cross-linking methods have been developed. One of these methods is based on the use of water soluble carbodiimides (CDI). It is generally accepted that this cross-linking method leads only to the formation of amide linkages between tissue carboxyl and amine groups. Therefore, until recently the TNBS assay was also used to determine the degree of cross-linking of CDI cross-linked tissue and collagen. However, it cannot be excluded that after activation of carboxyl groups of tissue and collagen by CDI, these groups can react with other nucleophiles (like hydroxyl groups) present in the matrix. To obtain a better insight in the degree of cross-linking of CDI cross-linked matrices a reliable assay for quantification of residual carboxyl groups is required. Up to now such an assay was not available. In this study a new assay to determine residual carboxyl groups in CDI cross-linked collagen matrices is presented. Reconstituted dermal bovine collagen matrices (RDBC) were cross-linked with a water soluble CDI and N-hydroxysuccinimide (NHS) and residual carboxyl groups were labeled using 5-bromomethyl fluorescein. Subsequently, the fluorescent label was released by mild hydrolysis and quantified with capillary zone electrophoresis. A calibration curve relating the concentration of carboxyl groups with peak intensities was obtained using Sephadex standards with known concentrations of carboxyl groups. The concentration of carboxyl groups in unprocessed RDBC as determined with this new technique was equal to the concentration of carboxyl groups measured by amino acid analysis. On the basis of the concentration of residual carboxyl groups determined for CDI/NHS cross-linked RDBC and RDBC, in which the amine groups were blocked with propionaldehyde before CDI/NHS cross-linking, it was concluded that activated carboxyl groups can also react with other groups (such as hydroxyl groups) present in the matrix. This implies that the crosslink density of RDBC matrices after treatment with CDI/NHS is higher than expected on the basis of amide bond formation only, as determined by the TNBS assay. PMID:17595021

Everaerts, Frank; Torrianni, Mark; Hendriks, Marc; Feijen, Jan

2007-12-15

31

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

32

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 ...

33

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

NASA Technical Reports Server (NTRS)

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.

Duraj, Stan A.

1994-01-01

34

Functional Group Interconversions  

ERIC Educational Resources Information Center

Describes some functional group interconversions that can be carried out on a small scale. The reactions are examples of transformations found in A-level, ONC and HNC courses for British chemistry students. (Author/GS)

Yeadon, A.

1974-01-01

35

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

SciTech Connect

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.

Hazum, E.

1987-11-03

36

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

PubMed

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

Mrsevic, Miroslav; Düsselberg, David; Staudt, Claudia

2012-01-01

37

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

PubMed Central

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

Mrsevic, Miroslav; Düsselberg, David

2012-01-01

38

Hydrogen-bonding linkage of thymidine derivatives with carboxylic acid and pyridyl groups in a crystalline state.  

PubMed

Thymidine derivatives with carboxylic acid and pyridyl groups were synthesized for constructing one-dimensional network structure based on hydrogen bonding in crystalline state. The solid sate structures and hydrogen bonding networks of the thymidine derivatives were characterized by single X-ray diffraction analysis. The thymidine derivatives formed a zwitterion structure with a pyridinium proton and a carboxylate moiety in a crystalline state due to transfer of a proton from the carboxylic acid to the pyridyl moiety. Strong hydrogen bonds between the pyridinium proton and the carboxylate moiety connected the thymidine units, resulting in a one-dimensional polymeric structure with a uniform direction reminiscent of the structure of single-strand polythymidine. The chemical structure of the pyridyl group affects the hydrogen-bonding networks. The well-designed hydrogen-bonding interaction served as connecting parts for polythymidine mimics even in the presence of other hydrogen-bonding motifs such as nucleobases. PMID:23901479

Hoshino, Junichi; Kuwabara, Junpei; Kanbara, Takaki

2013-07-01

39

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

PubMed

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

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

2014-08-15

40

5,6-dihydroxyindole-2-carboxylic acid (DHICA): a First Principles Density-Functional Study  

E-print Network

We report first principles density functional calculations for 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and several reduced forms. DHICA and 5,6-dihydroxyindole (DHI) are believed to be the basic building blocks of the eumelanins. Our results show that carboxylation has a significant effect on the physical properties of the molecules. In particular, the relative stabilities and the HOMO-LUMO gaps (calculated with the $\\Delta$SCF method) of the various redox forms are strongly affected. We predict that, in contrast to DHI, the density of unpaired electrons, and hence the ESR signal, in DHICA is negligibly small.

B. J. Powell

2004-08-24

41

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

PubMed

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

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

2015-02-13

42

Synthetic cannabinoids as designer drugs: new representatives of indol-3-carboxylates series and indazole-3-carboxylates as novel group of cannabinoids. Identification and analytical data.  

PubMed

By means of gas chromatography with mass spectrometry detection (GC-MS), including high resolution mass spectrometry (GC-HRMS) together with ultra-high performance liquid chromatography in combination with high resolution tandem mass spectrometry (UHPLC-HRMS), nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR), structure of new synthetic cannabinoids, representatives of indol- and indazole-3-carboxylates groups, used in smoke mixtures, was determined. Obtained analytical data make reliable identification of these compounds in a course of analysis of criminal seizures possible. PMID:25305529

Shevyrin, Vadim; Melkozerov, Vladimir; Nevero, Alexander; Eltsov, Oleg; Baranovsky, Alexander; Shafran, Yuri

2014-11-01

43

Adsorption of Fe(II) and U(VI) to carboxyl-functionalized microspheres: The influence of speciation on uranyl  

E-print Network

Adsorption of Fe(II) and U(VI) to carboxyl-functionalized microspheres: The influence of speciation-functionalized polysty- rene microspheres. Acid-base titrations were used to monitor protolytic reactions, and Fe K

Roden, Eric E.

44

Sulfonated poly(ether ether ketone) membranes containing pendent carboxylic acid groups and their application in vanadium flow battery  

NASA Astrophysics Data System (ADS)

Sulfonated poly(ether ether ketone) (C-SPEEK) membranes with pendent carboxylic acid groups are prepared and first investigated for vanadium flow battery (VFB) application. The introduction of carboxylic acid groups can effectively improve the ion conductivities of C-SPEEK membranes, while, keep their ion selectivities. The prepared C-SPEEK membranes exhibit excellent performance under VFB operating condition. VFB single cell assembled with C-SPEEK-50 membranes shows much higher energy efficiency (85% Vs 82%) and columbic efficiency (97.3% Vs 94.6%) than that assembled with Nafion 115. The membrane keeps a stable performance after more than 180 cycles charge-discharge test, showing good stability.

Chen, Dongju; Li, Xianfeng

2014-02-01

45

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

PubMed

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

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

2013-05-10

46

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

PubMed

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

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

2015-04-01

47

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

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.

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

1994-02-16

48

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

NASA Astrophysics Data System (ADS)

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.

Sagar, Sadia; Iqbal, Nadeem; Maqsood, Asghari

2013-06-01

49

A stable, pillar-layer metal-organic framework containing uncoordinated carboxyl groups for separation of transition metal ions.  

PubMed

A 3D pillar-layer framework (1) with uncoordinated carboxyl groups exhibits exceptional stability. It can effectively and selectively adsorb Cu(2+) ions and has been applied as a chromatographic column for separating Cu(2+)/Co(2+) ions. PMID:24811275

Meng, Xing; Zhong, Rong-Lin; Song, Xue-Zhi; Song, Shu-Yan; Hao, Zhao-Min; Zhu, Min; Zhao, Shu-Na; Zhang, Hong-Jie

2014-06-18

50

Chemical mutations of the catalytic carboxyl groups in lysozyme to the corresponding amides.  

PubMed

In a two-step process, esterification and ammonolysis, Glu-35 and Asp-52 in lysozyme were amidated to glutamine and asparagine residues. Since the side chains of glutamine and asparagine are almost equal in size to those of glutamic acid and aspartic acid, these conversions would provide appropriate derivatives to elucidate the catalytic participations of these residues. The enzymatic activities of the resulting [Gln35]lysozyme and [Asn52]lysozyme were found to be less than 4% of that of native lysozyme in a pH range of 3.4-8.0. As these derivatives were inactive, we could determine the dissociation constants (Ks values) for the binding of beta-1,4-linked n-mer, a hexasaccharide of N-acetyl-D-glucosamine, to [Gln35]lysozyme and [Asn52] lysozyme. The values of Ks at pH 5.5 and 40 degrees C were 1.6 X 10(-5) M for [Gln35]lysozyme and 2.7 X 10(-5) M for [Asn52]lysozyme. These values are similar to that for native lysozyme. The results are direct proof for the involvements of Glu35 and Asp52 in the catalytic action of lysozyme. A method for ammonolysis of ester groups in proteins in liquid ammonia is described and will be useful for amidation of carboxyl groups of proteins. PMID:3759981

Kuroki, R; Yamada, H; Moriyama, T; Imoto, T

1986-10-15

51

Nickel-catalysed carboxylation of organoboronates.  

PubMed

A nickel/N-heterocyclic carbene (NHC) catalysed carboxylation of aryl-, heteroaryl- and alkenylboronates, affording the corresponding carboxylic acids, has been developed. This transformation proceeds under one atmosphere of CO2 with a broad range of substrates and exhibits good functional group compatibility. PMID:24915842

Makida, Yusuke; Marelli, Enrico; Slawin, Alexandra M Z; Nolan, Steven P

2014-07-28

52

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

PubMed Central

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

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

2013-01-01

53

The stereochemistry of amide side chains containing carboxyl groups influences water exchange rates in EuDOTA-tetraamide complexes  

PubMed Central

Many Eu(III) complexes formed with DOTA-tetraamide ligands (where DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) have sufficiently slow water exchange kinetics to meet the slow-to-intermediate condition required to serve as chemical exchange saturation transfer (CEST) contrast agents for MRI. This class of MRI contrast agents offers an attractive platform for creating biological sensors because water exchange is exquisitely sensitive to subtle ligand stereochemistry and electronic effects. Introduction of carboxyl groups or carboxyl ethyl ester groups on the amide substituents has been shown to slow water exchange in these complexes, but less is known about the orientation or position of these side-chain groups relative to the inner-sphere Eu(III)-bound water molecule. In this study, a series of Eu(III) complexes having one or more carboxyl groups or carboxyl esters at the ?-position of the pendant amide side chains were prepared. Initial attempts to prepare optically pure EuDOTA-[(S)-Asp]4 resulted in a chemically pure ligand consisting of a mixture of stereochemical isomers. This was traced to racemization of (S)-aspartate diethyl ester during the synthetic procedure. Nevertheless, NMR studies of the Eu(III) complexes of this mixture revealed that each isomer had a different water exchange rate, differing by a factor of 2 or more. A second controlled synthesis and CEST study of EuDOTA-[(S)-Asp]4 and cis-EuDOTA-[(S)-Asp]2[(R)-Asp]2 confirmed that the water exchange rates in these diastereomeric complexes are controlled by the axial versus equatorial orientation of the carboxyl groups on the amide side chains. These observations provide new insights toward the development of even more slowly water exchanging systems which will be necessary for practical in vivo applications. PMID:23979260

Mani, Tomoyasu; Opina, Ana Christina L.; Zhao, Piyu; Evbuomwan, Osasere M.; Milburn, Nate; Tircso, Gyula; Kumas, Cemile; Sherry, A. Dean

2013-01-01

54

Cluster functional renormalization group  

NASA Astrophysics Data System (ADS)

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

Reuther, Johannes; Thomale, Ronny

2014-01-01

55

Kinetic and equilibrium characterization of uranium(VI) adsorption onto carboxylate-functionalized poly(hydroxyethylmethacrylate)-grafted lignocellulosics.  

PubMed

This study investigated the feasibility of using a new adsorbent prepared from coconut coir pith, CP (a coir industry-based lignocellulosic residue), for the removal of uranium [U(VI)] from aqueous solutions. The adsorbent (PGCP-COOH) having a carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto CP using potassium peroxydisulphate-sodium thiosulphite as a redox initiator and in the presence of N,N'-methylenebisacrylamide as a crosslinking agent. IR spectroscopy results confirm the graft copolymer formation and carboxylate functionalization. XRD studies confirm the decrease of crystallinity in PGCP-COOH compared to CP, and it favors the protrusion of the functional group into the aqueous medium. The thermal stability of the samples was studied using thermogravimetry (TG). Surface charge density of the samples as a function of pH was determined using potentiometric titration. The ability of PGCP-COOH to remove U(VI) from aqueous solutions was assessed using a batch adsorption technique. The maximum adsorption capacity was observed at the pH range 4.0-6.0. Maximum removal of 99.2% was observed for an initial concentration of 25mg/L at pH 6.0 and an adsorbent dose of 2g/L. Equilibrium was achieved in approximately 3h. The experimental kinetic data were analyzed using a first-order kinetic model. The temperature dependence indicates an endothermic process. U(VI) adsorption was found to decrease with an increase in ionic strength due to the formation of outer-sphere surface complexes on PGCP-COOH. Equilibrium data were best modeled by the Langmuir isotherm. The thermodynamic parameters such as DeltaG(0), DeltaH(0) and DeltaS(0) were derived to predict the nature of adsorption. Adsorption experiments were also conducted using a commercial cation exchanger, Ceralite IRC-50, with carboxylate functionality for comparison. Utility of the adsorbent was tested by removing U(VI) from simulated nuclear industry wastewater. Adsorbed U(VI) ions were desorbed effectively (about 96.2+/-3.3%) by 0.1M HCl. The adsorbent was suitable for repeated use (more than four cycles) without any noticeable loss of capacity. PMID:18222595

Anirudhan, T S; Divya, L; Suchithra, P S

2009-01-01

56

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

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

Haghighatpanah, Shayesteh; Bohlén, Martin; Bolton, Kim

2014-01-01

57

The majority of potassium ions in muscle cells is adsorbed on beta- and gamma-carboxyl groups of myosin: potassium-ion-adsorbing carboxyl groups on myosin heads engage in cross-bridge formation during contraction.  

PubMed

High-molecular weight poly(ethylene glycol) (PEG-8000) in the bathing medium prolongs the survival of 2-mm-wide frog muscle segments with open ends. In a PEG-8000-containing medium Rb+, K+, and Na+ in the muscle segments reached new diffusion equilibrium in 2-4 hours. At this new equilibrium, the cell's preference of K+ over Na+ was preserved but very much weakened. Studies of the influence of pH on the equilibrium distribution of labelled Na+ in 2-mm-wide muscle segments confirmed the prediction that beta- and gamma-carboxyl groups, carried respectively on aspartic and glutamic acid residues of intracellular proteins, adsorb K+, Na+ and other monovalent cations. These carboxyl groups have a characteristic pKa between 3.65 and 4.25. A pKa of 3.85 was observed. These findings, when seen in the light of other relevant information available, led to the conclusion that beta- and gamma-carboxyl groups on myosin molecules adsorb--in a close contact one-ion-one-site fashion--the majority (67% to 80%) of K+ in resting muscle cells. Other evidence suggests that in muscle contraction, the K(+)-adsorbing beta- and gamma-carboxyl groups on myosin heads form salt linkages with cationic sites on actin, displacing and releasing the adsorbed K+. Present and earlier findings together offer support for an earlier suggestion that the formation and dissociation of these salt-linkages may underlie the force-generating, cyclic formation and dissociation of cross-bridges during muscle contraction. PMID:1775537

Ling, G N; Ochsenfeld, M M

1991-01-01

58

Functional Group Analysis.  

ERIC Educational Resources Information Center

Discusses analytical methods selected from current research articles. Groups information by topics of general interest, including acids, aldehydes and ketones, nitro compounds, phenols, and thiols. Cites 97 references. (CS)

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

1980-01-01

59

Variation in optoelectronic properties of azo dye-sensitized TiO2 semiconductor interfaces with different adsorption anchors: carboxylate, sulfonate, hydroxyl and pyridyl groups.  

PubMed

The optoelectronic properties of four azo dye-sensitized TiO2 interfaces are systematically studied as a function of a changing dye anchoring group: carboxylate, sulfonate, hydroxyl, and pyridyl. The variation in optoelectronic properties of the free dyes and those in dye/TiO2 nanocomposites are studied both experimentally and computationally, in the context of prospective dye-sensitized solar cell (DSSC) applications. Experimental UV/vis absorption spectroscopy, cyclic voltammetry, and DSSC device performance testing reveal a strong dependence on the nature of the anchor of the optoelectronic properties of these dyes, both in solution and as dye/TiO2 nanocomposites. First-principles calculations on both an isolated dye/TiO2 cluster model (using localized basis sets) and each dye modeled onto the surface of a 2D periodic TiO2 nanostructure (using plane wave basis sets) are presented. Detailed examination of these experimental and computational results, in terms of light harvesting, electron conversion and photovoltaic device performance characteristics, indicates that carboxylate is the best anchoring group, and hydroxyl is the worst, whereas sulfonate and pyridyl groups exhibit competing potential. Different sensitization solvents are found to affect critically the extent of dye adsorption achieved in the dye-sensitization of the TiO2 semiconductor, especially where the anchor is a pyridyl group. PMID:24786472

Zhang, Lei; Cole, Jacqueline M; Dai, Chencheng

2014-05-28

60

ATR-FTIR spectroscopic evidence for biomolecular phosphorus and carboxyl groups facilitating bacterial adhesion to iron oxides.  

PubMed

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

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

2014-07-01

61

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

PubMed

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

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

2009-10-28

62

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

PubMed

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

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

2014-01-01

63

Spectral functions from the functional renormalization group  

NASA Astrophysics Data System (ADS)

We present a viable method to obtain real-time quantities such as spectral functions or transport coefficients at finite temperature and density within a non-perturbative functional renormalization group approach. Our method is based on a thermodynamically consistent truncation of the flow equations for 2-point functions with analytically continued frequency components in the originally Euclidean external momenta. We demonstrate its feasibility by calculating the mesonic spectral functions in the quark-meson model at different temperatures and quark chemical potentials, in particular around the critical endpoint in the phase diagram of the model.

Tripolt, Ralf-Arno; Strodthoff, Nils; von Smekal, Lorenz; Wambach, Jochen

2014-11-01

64

Modification of chitosan with carboxyl-functionalized ionic liquid for anion adsorption.  

PubMed

We report a novel chitosan derivative, chitosan-ionic liquid (CS-IL) conjugation for anion adsorption. Specifically, CS-IL conjugation was synthesized through the reaction of amino groups of chitosan with carboxylic groups of 1-carboxybutyl-3-methylimidazolium chloride. Due to the amphiphilic structure, CS-IL conjugation could self-assemble into nanoparticles in distilled water. This novel chitosan derivative revealed good anion adsorption performance, and the adsorption capacity of Cr2O7(2-) and PF6(-) was 0.422 mmol/g and 0.840 mmol/g, respectively. The adsorption of Cr2O7(2-) and PF6(-) could be improved at low pH, which was ascribed to the adsorption of protonated NH2 on chitosan. Importantly, the chitosan derivative would aggregate in the water after the adsorption and could be easily separated. The properties enable CS-IL conjugation to be used as a novel anion adsorbent for wastewater treatment. PMID:24076195

Wei, Yanqi; Huang, Wei; Zhou, Yuan; Zhang, Shuang; Hua, Daoben; Zhu, Xiulin

2013-11-01

65

Surface Functionalization of Poly(ethylene terephthalate) Film and Membrane by Controlled Wet Chemistry: Chemical Characterization of Carboxylated Surfaces  

Microsoft Academic Search

Surface functionalization of poly(ethylene terephthalate) (PET) film or track-etched membrane was performed using the methods of organic synthesis conducted at the solid-liquid interface. Basic hydrolysis in aqueous acetonitrile followed by permanganate oxidation in diluted sulfuric acid created new carboxylic chain-ends. These reactive functions were assayed as follows: (i) activation with water soluble carbodiimide; (ii) coupling to 3 H-labeled amino acids;

Jacqueline Marchand-Brynaert; Michéle Deldime; Isabelle Dupont; Jean-Luc Dewez; Yves-Jacques Schneider

1995-01-01

66

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

PubMed

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

McShan, Danielle; Yu, Hongtao

2014-07-01

67

Hydrophilic Polymer Monolithic Capillary Microextraction Online Coupled to ICPMS for the Determination of Carboxyl Group-Containing Gold Nanoparticles in Environmental Waters.  

PubMed

In this study, the hydrophilic polymer monolithic capillary (poly(acrylamide-vinylpyridine-methylene bis(acrylamide)), poly(AA-VP-Bis)) was prepared for the separation and enrichment of carboxyl group-containing gold nanoparticles (Au NPs) from environmental waters followed by online ICPMS determination. The extraction mechanism of the prepared poly(AA-VP-Bis) monolithic capillary for Au NPs is based on the static electrical and hydrogen bond interactions between the carboxyl group on the surface of Au NPs and pyridine/amide groups on the surface of the monolith. Under the optimal conditions, a detection limit of 24.2 fmol L(-1) and a sample throughput of 6 h(-1) were achieved for 3 nm citrate stabilized Au NPs, and the original morphology of the Au NPs could be maintained during the extraction process. The developed method was successfully applied for the analysis of carboxyl group-containing Au NPs in environmental water samples, such as tap water, the Yangtze River water, and the East Lake water, with recoveries in the range of 77-103%. Compared with the reported approaches for analysis of Au NPs, this method is an online strategy for carboxyl group-containing Au NPs determination and has the merits of low detection limit, small sample consumption, fast extraction/desorption kinetics, wide linear range, high selectivity, and high throughput. PMID:25572871

Zhang, Lin; Chen, Beibei; He, Man; Liu, Xiaolan; Hu, Bin

2015-02-01

68

Floral benzenoid carboxyl methyltransferases: From in vitro to in planta function  

PubMed Central

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 planta 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. PMID:15946712

Effmert, Uta; Saschenbrecker, Sandra; Ross, Jeannine; Negre, Florence; Fraser, Chris M.; Noel, Joseph P.; Dudareva, Natalia; Piechulla, Birgit

2010-01-01

69

Harmonic functions over group actions Renato Feres  

E-print Network

Harmonic functions over group actions Renato Feres Washington University Renato Feres Washington University () Harmonic functions over group actions 1 / 25 #12;Topics: Harmonic functions and random walks on discrete groups The Liouville property and Poisson boundary Harmonic functions over group actions Examples

Feres, Renato

70

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

PubMed

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

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

2015-02-11

71

Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.  

PubMed

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. PMID:25554963

Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

2015-03-15

72

Semipermanent C-terminal carboxylic Acid protecting group: application to solubilizing peptides and fragment condensation.  

PubMed

The 2-methoxy-4-methylsulfinylbenzyl alcohol (Mmsb-OH) safety-catch linker has been described as a useful tool to overcome two obstacles in peptide synthesis: the solubility and fragment condensation of peptides. The incorporation of the linker into an insoluble peptide target, thereby allowing the conjugation of a poly-Lys as a "solubilizing tag", notably enhanced the solubility of the peptide. The selective conditions that remove that linker favored its incorporation as a semipermanent C-terminal protecting group, thereby allowing fragment condensation of peptides. PMID:25545716

Paradís-Bas, Marta; Tulla-Puche, Judit; Albericio, Fernando

2015-01-16

73

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

PubMed

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

Czakler, Matthias; Artner, Christine; Schubert, Ulrich

2012-07-01

74

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

PubMed Central

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

Czakler, Matthias; Artner, Christine; Schubert, Ulrich

2012-01-01

75

Copper-Catalyzed Carboxylation of Aryl Iodides with Carbon Dioxide  

PubMed Central

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

Tran-Vu, Hung; Daugulis, Olafs

2013-01-01

76

Aqueous infrared carboxylate absorbances: Aliphatic di-acids  

USGS Publications Warehouse

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.

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

1998-01-01

77

A Functional Analytic Approach to Group Psychotherapy  

ERIC Educational Resources Information Center

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…

Vandenberghe, Luc

2009-01-01

78

Fabrication of sulfonated poly(ether ether ketone)-based hybrid proton-conducting membranes containing carboxyl or amino acid-functionalized titania by in situ sol-gel process  

NASA Astrophysics Data System (ADS)

Functionalized titania are used as fillers to modify the sulfonated poly(ether ether ketone) (SPEEK) membrane for improved proton conductivity and methanol barrier property. The functionalized titania sol which contains proton conductive carboxylic acid groups or amino acid groups are derived from a facile chelation method using different functional additives. Then the novel SPEEK/carboxylic acid-functionalized titania (SPEEK/TC) and SPEEK/amino acid-functionalized titania (SPEEK/TNC) hybrid membranes are fabricated via in situ sol-gel method. The anti-swelling property and thermal stability of hybrid membranes are enhanced owing to the formation of electrostatic force between SPEEK and titania nanoparticles. The hybrid membranes exhibit higher proton conductivity than plain SPEEK membrane because more proton transfer sites are provided by the functionalized titania nanoparticles. Particularly, the proton conductivity of SPEEK/TNC membrane with 15% filler content reaches up to 6.24 × 10-2 S cm-1, which is 3.5 times higher than that of the pure SPEEK membrane. For methanol permeability, the SPEEK/TNC membranes possess the lowest values because the acid-base interaction between sulfonic acid groups in SPEEK and amino groups in functionalized titania leads to a more compact membrane structure.

Yin, Yongheng; Xu, Tao; He, Guangwei; Jiang, Zhongyi; Wu, Hong

2015-02-01

79

Capping methotrexate ?-carboxyl groups enhances systemic exposure and retains the cytotoxicity of drug conjugated PEGylated polylysine dendrimers.  

PubMed

A generation 5 PEGylated (PEG 1100) polylysine dendrimer, conjugated via a stable amide linker to OtBu protected methotrexate (MTX), was previously shown to have a circulatory half-life of 2 days and to target solid tumors in both rats and mice. Here, we show that deprotection of MTX and substitution of the stable linker with a matrix metalloproteinase (MMP) 2 and 9 cleavable linker (PVGLIG) dramatically increased plasma clearance and promoted deposition in the liver and spleen (50-80% of the dose recovered in the liver 3 days post dose). Similar rapid clearance was also seen using a scrambled peptide suggesting that clearance was not dependent on the cleavable nature of the linker. Surprisingly, dendrimers where OtBu capped MTX was linked to the dendrimer surface via the hexapeptide linker showed equivalent in vitro cytotoxicity against HT1080 cells when compared to the uncapped dendrimer and also retained the long circulating characteristics of the stable constructs. The OtBu capped MTX conjugated dendrimer was subsequently shown to significantly reduce tumor growth in HT1080 tumor bearing mice compared to control. In contrast the equivalent dendrimer comprising uncapped MTX conjugated to the dendrimer via the same hexapeptide linker did not reduce tumor growth, presumably reflecting very rapid clearance of the construct. The results are consistent with the suggestion that protection of the ?-carboxyl group of methotrexate may be used to improve the circulatory half-life and reduce the liver accumulation of similar MTX-conjugated dendrimers, while still retaining antitumor activity in vivo. PMID:21171585

Kaminskas, Lisa M; Kelly, Brian D; McLeod, Victoria M; Sberna, Gian; Boyd, Ben J; Owen, David J; Porter, Christopher J H

2011-04-01

80

Photovoltaic enhancement of dye-sensitized solar cell prepared from [TiO 2\\/ethyl cellulose\\/terpineol] paste employing TRITON™ X-based surfactant with carboxylic acid group in the oxyethylene chain end  

Microsoft Academic Search

This paper describes the formulation of nanocrystalline TiO2 paste for dye-sensitized solar cell (DSSC) applications employing a series of TRITON™ X-based surfactants with an octyl phenol ethoxylate (OPE) backbone and various chain ends. Five different functional group-terminated TRITON™ X (or OPE) derivatives, [OPE5-OH], [OPE5-COOH], [OPE5-NH2], [OPE5-Imidazole], and [OPE5-OPO(OH)2], were prepared from OPE of 5 oxyethylene units (n=5). The carboxylic acid-terminated

Jung-Gyu Nam; Eun-Sung Lee; Won-Cheol Jung; Young-Jun Park; Byung-Hee Sohn; Sang-Cheol Park; Joo Sung Kim; Jin-Young Bae

2009-01-01

81

Amino acid ester prodrugs conjugated to the ?-carboxylic acid group do not display affinity for the L-type amino acid transporter 1 (LAT1).  

PubMed

L-type amino acid transporter (LAT1) is an intriguing target for carrier-mediated transport of drugs as it is highly expressed in the blood-brain barrier and also in various types of cancer. Several studies have proposed that in order for compounds to act as LAT1 substrates they should possess both negatively charged ?-carboxyl and positively charged ?-amino groups. However, in some reports, such as in two recent publications describing an isoleucine-quinidine ester prodrug (1), compounds having no free ?-carboxyl group have been reported to exhibit high affinity for LAT1 in vitro. In the present study, 1 was synthesized and its affinity for LAT1 was evaluated both with an in situ rat brain perfusion technique and in the human breast cancer cell line MCF-7 in vitro. 1 showed no affinity for LAT1 in either model nor did it show any affinity for LAT2 in an in vitro study. Our results confirm the earlier reported requirements for LAT1 substrates. Thus drugs or prodrugs with substituted ?-carboxyl group cannot bind to LAT with high affinity. PMID:25305508

Rautio, Jarkko; Kärkkäinen, Jussi; Huttunen, Kristiina; Gynther, Mikko

2014-10-01

82

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

NASA Astrophysics Data System (ADS)

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

Lu, Haibao; Min Huang, Wei

2013-06-01

83

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

PubMed

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

Rodriguez, Jorge H; Ziegler, Christopher J

2015-01-01

84

Addressing Mechanistic Issues in the Coupling of Isonitriles and Carboxylic Acids: Potential Routes to Peptidic Constructs  

PubMed Central

Mechanistic issues surrounding the 2CC (two component coupling) reaction of carboxylic acids with isonitriles have been investigated. Experimental details suggest the FCMA (formimidate carboxylate mixed anhydride) intermediate exists in both interdictable and non-interdictable form. Furthermore, the 2CC reaction has been applied to the synthesis of a tripeptide featuring two formyl functional groups. PMID:18783225

Li, Xuechen; Yuan, Yu; Kan, Cindy; Danishefsky, Samuel J.

2008-01-01

85

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

PubMed

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

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

2015-02-11

86

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

PubMed Central

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

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

2011-01-01

87

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

88

Dehydrative C-H/N-OH Functionalizations in H2O by Ruthenium(II) Catalysis: Subtle Effect of Carboxylate Ligands and Mechanistic Insight.  

PubMed

A ruthenium(II) complex derived from the electron-deficient aromatic carboxylic acid 3-(F3C)C6H4CO2H proved to be a highly efficient catalyst for dehydrative alkyne annulation by NH-free hydroxamic acids in water. The C-H/N-OH functionalization occurred with excellent positional selectivity as well as ample substrate scope, setting the stage for effective intermolecular alkenylations of hydroxamic acids. Detailed mechanistic studies were suggestive of a kinetically relevant C-H metalation by carboxylate assistance along with subsequent migratory alkyne insertion, reductive elimination, and intramolecular oxidative addition. PMID:25335189

Yang, Fanzhi; Ackermann, Lutz

2014-12-19

89

Relating Functional Groups to the Periodic Table  

ERIC Educational Resources Information Center

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.)

Struyf, Jef

2009-01-01

90

Iron(III)- and copper(II) complexes of an asymmetric, pentadentate salen-like ligand bearing a pendant carboxylate group  

Microsoft Academic Search

The equilibrium and solution structural properties of the iron(III) and copper(II) complexes of an asymmetric salen-like ligand (N,N?-bis(2-hydroxybenzyl)-2,3-diamino-propionic acid, H3bhbdpa) bearing a pendant carboxylate group were characterized in aqueous solution by potentiometric, pH-dependent electron paramagnetic resonance (EPR) and UV–Vis (UV–Visible) measurements. In the equimolar systems the pentadentate ligand forms very stable, differently protonated mononuclear complexes with both metal ions. In

Attila Jancsó; Zoltán Paksi; Satu Mikkola; Antal Rockenbauer; Tamás Gajda

2005-01-01

91

FTIR Analysis of Functional Groups in Aerosol Particles  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

92

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

93

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

94

Designed nitrogen doping of few-layer graphene functionalized by selective oxygenic groups  

PubMed Central

Few-layer nitrogen doped graphene was synthesized originating from graphene oxide functionalized by selective oxygenic functional groups (hydroxyl, carbonyl, carboxyl etc.) under hydrothermal conditions, respectively. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) observation evidenced few-layer feature of the graphene oxide. X-ray diffraction (XRD) pattern confirmed phase structure of the graphene oxide and reduced graphene oxide. Nitrogen doping content and bonding configuration of the graphene was determined by X-ray photoelectron spectroscopy (XPS), which indicated that different oxygenic functional groups were evidently different in affecting the nitrogen doping process. Compared with other oxygenic groups, carboxyl group played a crucial role in the initial stage of nitrogen doping while hydroxyls exhibited more evident contribution to the doping process in the late stage of the reaction. Formation of graphitic-like nitrogen species was controlled by a synergistic effect of the involved oxygenic groups (e.g., -COOH, -OH, C-O-C, etc.). The doping mechanism of nitrogen in the graphene was scrutinized. The research in this work may not only contribute to the fundamental understandings of nitrogen doping within graphene but promote the development of producing novel graphene-based devices with designed surface functionalization. PMID:25520594

2014-01-01

95

pH-Responsive Non-Ionic Diblock Copolymers: Ionization of Carboxylic Acid End-Groups Induces an Order–Order Morphological Transition**  

PubMed Central

A carboxylic acid based reversible additionfragmentation transfer (RAFT) agent is used to prepare gels composed of worm-like diblock copolymers using two non-ionic monomers, glycerol monomethacrylate (GMA) and 2-hydroxypropyl methacrylate (HPMA). Ionization of the carboxylic acid end-group on the PGMA stabilizer block induces a worm-to-sphere transition, which in turn causes immediate degelation. This morphological transition is fully reversible as determined by TEM and rheology studies and occurs because of a subtle change in the packing parameter for the copolymer chains. A control experiment where the methyl ester derivative of the RAFT agent is used to prepare the same diblock copolymer confirms that no pH-responsive behavior occurs in this case. This end-group ionization approach is important for the design of new pH-responsive copolymer nano-objects as, unlike polyacids or polybases, only a minimal amount of added base (or acid) is required to drive the morphological transition. PMID:25418214

Lovett, Joseph R; Warren, Nicholas J; Ratcliffe, Liam P D; Kocik, Marzena K; Armes, Steven P

2015-01-01

96

pH-Responsive Non-Ionic Diblock Copolymers: Ionization of Carboxylic Acid End-Groups Induces an Order-Order Morphological Transition.  

PubMed

A carboxylic acid based reversible additionfragmentation transfer (RAFT) agent is used to prepare gels composed of worm-like diblock copolymers using two non-ionic monomers, glycerol monomethacrylate (GMA) and 2-hydroxypropyl methacrylate (HPMA). Ionization of the carboxylic acid end-group on the PGMA stabilizer block induces a worm-to-sphere transition, which in turn causes immediate degelation. This morphological transition is fully reversible as determined by TEM and rheology studies and occurs because of a subtle change in the packing parameter for the copolymer chains. A control experiment where the methyl ester derivative of the RAFT agent is used to prepare the same diblock copolymer confirms that no pH-responsive behavior occurs in this case. This end-group ionization approach is important for the design of new pH-responsive copolymer nano-objects as, unlike polyacids or polybases, only a minimal amount of added base (or acid) is required to drive the morphological transition. PMID:25418214

Lovett, Joseph R; Warren, Nicholas J; Ratcliffe, Liam P D; Kocik, Marzena K; Armes, Steven P

2014-11-21

97

Preparation and characterization of carboxyl functionalization of chitosan derivative magnetic nanoparticles  

Microsoft Academic Search

The functionalized magnetic Fe3O4-chitosan derivative nanoparticles have been prepared by the covalent binding of alpha-ketoglutaric acid chitosan (KCTS) onto the surface of Fe3O4 magnetic nanoparticles via carbodiimide activation. Transmission electron microscopy (TEM) showed that the KCTS-bound Fe3O4 nanoparticles were regular spheres with a mean diameter of 26nm. X-ray diffraction (XRD) patterns indicated that the Fe3O4 nanoparticles were pure Fe3O4 with

Gui-yin Li; Ke-long Huang; Yu-ren Jiang; Ping Ding; Dong-liang Yang

2008-01-01

98

Influence of functional groups on the C ?-C ? chain of L-phenylalanine and its derivatives  

NASA Astrophysics Data System (ADS)

L-phenylalanine ( L-phe) consists of three different functional groups, i.e., phenyl, carboxyl (-COOH) and amino (-NH 2), joining through the C ?-C ? bridge. Substitution of these groups produces 2-phenethylamine (PEA) and 3-phenylpropionic acid (PPA). Electronic structures of L-phe, PEA and PPA together with smaller "fragments" L-alanine and benzene were determined using density functional theory (DFT), from which core and valence shell ionization spectra were simulated. Comparison of the spectra reveals that core shell ionization energies clearly indicate that the carbon bridge is significantly affected by their functional group substitutions particularly at the C ? site. In the valence space, quite unexpectedly, the frontier orbitals are concentrated on the benzene group although some energy splitting is observed. The orbitals which significantly affect the C ?-C ? carbon backbone are from the inner valence shell in the ionization energy region of 20-26 eV of the molecules.

Ganesan, Aravindhan; Brunger, Michael; Wang, Feng

2010-07-01

99

Development of an Electrogenerated Chemiluminescence Biosensor using Carboxylic acid-functionalized MWCNT and Au Nanoparticles  

PubMed Central

A COOH-F-MWCNT-Nafion-Ru(bpy)32+-Au-ADH electrogenerated chemiluminescence (ECL) electrode using COOH-functionalized MWCNT (COOH-F-MWCNT) and Au nanoparticles synthesized by the radiation method was fabricated for ethanol sensing. A higher sensing efficiency for ethanol for the ECL biosensor prepared by PAAc-g-MWCNT was measured compared to that of the ECL biosensor prepared by PMAc-g-MWCNT, and purified MWCNT. Experimental parameters affecting ethanol detection were also examined in terms of pH and the content of PAAc-g-MWCNT in Nafion. Little interference of other compounds was observed for the assay of ethanol. Results suggest this ECL biosensor could be applied for ethanol detection in real samples. PMID:22573979

Piao, Ming-Hua; Yang, Dae-Soo; Yoon, Kuk-Ro; Lee, Seung-Ho; Choi, Seong-Ho

2009-01-01

100

Chiral metal-organic frameworks bearing free carboxylic acids for organocatalyst encapsulation.  

PubMed

Two chiral carboxylic acid functionalized micro- and mesoporous metal-organic frameworks (MOFs) are constructed by the stepwise assembly of triple-stranded heptametallic helicates with six carboxylic acid groups. The mesoporous MOF with permanent porosity functions as a host for encapsulation of an enantiopure organic amine catalyst by combining carboxylic acids and chiral amines in situ through acid-base interactions. The organocatalyst-loaded framework is shown to be an efficient and recyclable heterogeneous catalyst for the asymmetric direct aldol reactions with significantly enhanced stereoselectivity in relative to the homogeneous organocatalyst. PMID:25382736

Liu, Yan; Xi, Xiaobing; Ye, Chengcheng; Gong, Tengfei; Yang, Zhiwei; Cui, Yong

2014-12-01

101

Control of Mung bean pectinmethylesterase isoform activities. Influence of pH and carboxyl group distribution along the pectic chains.  

PubMed

Well-characterized pectin samples with a wide range of degrees of esterification (39-74%) were incubated with the solubilized pure alpha and gamma isoforms of pectinmethylesterase, from mung bean hypocotyl (Vigna radiata). Enzyme activity was determined at regular intervals along the deesterification pathway at pH 5.6 and pH 7.6. It has been demonstrated that the distribution of the carboxyl units along the pectin backbone controls the activity of the cell wall pectinmethylesterases to a much greater extent than the methylation degree, with a random distribution leading to the strongest activity. Polygalacturonic acid was shown to be a competitive inhibitor of the alpha isoform activity at pH 5.6 and to inhibit the gamma isoform activity at both pH 5.6 and pH 7.6. Under these conditions, the drop in enzyme activity was shown to be correlated to the formation of deesterified blocks of 19 +/- 1 galacturonic acid residues through simulations of the enzymatic digestion according to the mechanisms established previously (Catoire, L., Pierron, M., Morvan, C., Herve du Penhoat, C., and Goldberg, R. (1998) J. Biol. Chem. 273, 33150-33156). However, even in the absence of inhibition by the reaction product, activity dropped to negligible levels long before the substrate had been totally deesterified. Comparison of alpha and gamma isoform cDNAs suggests that the N-terminal region of catalytic domains might explain their subtle differences in activity revealed in this study. The role of pectinmethylesterase in the cell wall stiffening process along the growth gradient is discussed. PMID:11120736

Goldberg, R; Pierron, M; Bordenave, M; Breton, C; Morvan, C; du Penhoat, C H

2001-03-23

102

Interaction network among functional drug groups  

PubMed Central

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

2013-01-01

103

Department and function: Group Leader, Clinical Immunology  

E-print Network

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

Manstein, Dietmar J.

104

A Layered Mixed Zirconium Phosphate/Phosphonate with Exposed Carboxylic and Phosphonic Groups: X-ray Powder Structure and Proton Conductivity Properties.  

PubMed

A novel mixed zirconium phosphate/phosphonate based on glyphosine, of formula Zr2(PO4)H5(L)2·H2O [L = (O3PCH2)2NCH2COO], was synthesized in mild conditions. The compound has a layered structure that was solved ab initio from laboratory PXRD data. It crystallizes in the monoclinic C2/c space group with the following cell parameters: a = 29.925(3), b = 8.4225(5), c = 9.0985(4) Å, and ? = 98.474(6)°. Phosphate groups are placed inside the sheets and connect the zirconium atoms in a tetradentate fashion, while uncoordinated carboxylate and P-OH phosphonate groups are exposed on the layer surface. Due to the presence of these acidic groups, the compound showed remarkable proton conductivity properties, which were studied in a wide range of temperature and relative humidity (RH). The conductivity is strongly dependent on RH and reaches 1 × 10(-3) S cm(-1) at 140 °C and 95% RH. At this RH, the activation energy of conduction is 0.15 eV in the temperature range 80-140 °C. The similarities of this structure with related structures already reported in the literature were also discussed. PMID:25423946

Donnadio, Anna; Nocchetti, Morena; Costantino, Ferdinando; Taddei, Marco; Casciola, Mario; da Silva Lisboa, Fábio; Vivani, Riccardo

2014-12-15

105

A Novel Plant Cysteine Protease Has a Dual Function as a Regulator of 1-Aminocyclopropane-1-Carboxylic Acid  

E-print Network

-Carboxylic Acid Synthase Gene Expression W Noa Matarasso, Silvia Schuster, and Adi Avni1 Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel The hormone ethylene influences plant growth Ethylene as a plant hormone influences many aspects of plant growth and development (Mattoo and Suttle

Avni, Adi

106

The Circular Velocity Function of Group Galaxies  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

107

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)

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

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

2013-06-01

108

Functional renormalization group approach to neutron matter  

NASA Astrophysics Data System (ADS)

The chiral nucleon-meson model, previously applied to systems with equal number of neutrons and protons, is extended to asymmetric nuclear matter. Fluctuations are included in the framework of the functional renormalization group. The equation of state for pure neutron matter is studied and compared to recent advanced many-body calculations. The chiral condensate in neutron matter is computed as a function of baryon density. It is found that, once fluctuations are incorporated, the chiral restoration transition for pure neutron matter is shifted to high densities, much beyond three times the density of normal nuclear matter.

Drews, Matthias; Weise, Wolfram

2014-11-01

109

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

110

Role of functional groups in fiber in the binding of zinc  

SciTech Connect

The binding of zinc by purified cellulose, xylan, methylated xylan, pectin and methylated pectin was measured in vitro. Methylated xylan and methylated pectin were prepared chemically from xylan and pectin, respectively, to block hydroxyl and carboxyl groups. Comparison of zinc binding capacities was made between xylan and methylated xylan, and between pectin and methylated pectin to assess the role of the two functional groups in binding minerals. The binding of zinc was conducted at pH 2.6, 4.0, 5.4 and 6.8 in various concentrations of ZnSO/sub 4/ solution containing /sup 65/Zn using a dialysis system for water-soluble pectin and an incubation-centrifugation model for the other four water-insoluble fibers. The results showed that zinc binding by each fiber was pH dependent and it increased from pH 2.6 to 6.8 (p < 0.001). At pH 6.8, % Zn bound to fiber decreased as concentration of ZnSO/sub 4/ increased from 1 ..mu..M to 96 ..mu..M (p less than or equal to 0.01). mean zinc binding ratio of pectin to methylated xylan was 5.1, whereas the ratio of pectin t methylated pectin was only 1.7. This suggests that the hydroxyl group in xylan plays a more important role than the carboxyl group in pectin in the binding of zinc.

Jiang, K.

1986-03-01

111

Direct enantioselective conjugate addition of carboxylic acids with chiral lithium amides as traceless auxiliaries.  

PubMed

Michael addition is a premier synthetic method for carbon-carbon and carbon-heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B. PMID:25562717

Lu, Ping; Jackson, Jeffrey J; Eickhoff, John A; Zakarian, Armen

2015-01-21

112

A simple one-step modification of various materials for introducing effective multi-functional groups.  

PubMed

Covalent immobilization of various biomolecules is a desired strategy for bio-multifunctional surface modification. Multi-functionalization of a material surface is considered to be the premise of immobilizing a variety of biomolecules. However, currently adopted methods, used to introduce proper reactive functional groups on material surfaces, mostly are hard to be carried out and frequently can only introduce insufficient functional groups. In this work, we successfully develop the films (GAHD films) prepared via the simple copolymerization of gallic acid (GA) and hexamethylenediamine (HD), which can be deposited on different kinds of material surfaces including metals, ceramics and polymers by a one-step dip-coating method. Moreover, these copolymerized GAHD films possess high concentration of multi-functional groups like carboxyl (COOH), primary amine (-NH2) and quinone groups on the surfaces. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results prove either the occurrence of Michael addition reaction, Schiff base reaction in the film-forming process, or the existence of COOH, NH2 and quinone groups on the surfaces. The maximum contents of carboxyl and amine on the GAHD film are 24.9 nmol/cm(2) and 31.7 nmol/cm(2) respectively. After dynamical immersion for 30 days, slight swellings can be observed, which reveals that the GAHD films possess good stability. Moreover, Heparin (Hep), fibronectin (Fn) and laminin (Ln) are successfully immobilized on the GAHD film surfaces. The results of cell counting kit-8 (CCK-8) and rhodamine fluorescence photograph indicate that the 1:1.62 GAHD film has good cytocompatibility. PMID:24064415

Chen, Si; Li, Xin; Yang, Zhilu; Zhou, Shuo; Luo, Rifang; Maitz, Manfred F; Zhao, Yuancong; Wang, Jin; Xiong, Kaiqin; Huang, Nan

2014-01-01

113

Glioma cell line proliferation controlled by different chemical functional groups in vitro  

NASA Astrophysics Data System (ADS)

Glioma cell line C6 cultured on silicon surfaces modified by different chemical functional groups, including mercapto (-SH), carboxyl (-COOH), amino (-NH2), hydroxyl (-OH) and methyl (-CH3) groups, was studied here to investigate the influence of surface chemistry on the cell proliferation, adhesion and apoptosis. AFM confirmed the similar characteristic of different functional groups occupation. The adhering C6 exhibited morphological changes in response to different chemical functional groups. The C6 adhered to -COOH, -NH2, -OH and -CH3 surfaces and flattened morphology, while those on -SH surface exhibited the smallest contact area with mostly rounded morphology, which led to the death of cancer cells. The results of MTT assay showed that the -COOH and -NH2 groups promoted cell proliferation, while the -SH significantly inhibited the proliferation. Compared with other chemical functional groups, the -SH group exhibited its unique effect on the fate of cancer cells, which might provide means for the design of biomaterials to prevent and treat glioma.

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

2013-03-01

114

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

PubMed

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

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

2014-08-01

115

Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.  

PubMed

Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions. PMID:24720707

Chen, Yuehua; Wang, Huiyong; Wang, Jianji

2014-05-01

116

4-Chloro­phenyl quinoline-2-carboxyl­ate  

PubMed Central

In the title compound, C16H10ClNO2, the dihedral angle between the quinoline ring system and the benzene ring is 14.7?(5)°. The carboxyl­ate group is twisted from the mean planes of the quinoline ring system and the benzene ring by 17.7?(5) and 32.1?(4)°, respectively. In the crystal, inversion dimers are formed with the molecules linked by pairs of weak C—H?O inter­actions arising from an activated aromatic C atom adjacent to the C—Cl bond, generating R 2 2(14) loops. PMID:24454260

Fazal, E.; Kaur, Manpreet; Sudha, B. S.; Nagarajan, S.; Jasinski, Jerry P.

2013-01-01

117

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)

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.

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

2014-11-01

118

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

119

1-Azaniumylcyclobutane-1-carboxylate monohydrate  

NASA Technical Reports Server (NTRS)

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).

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

2014-01-01

120

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

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.

Taguchi, J.; Kuriyama, K. (Kyoto Prefectural Univ. of Medicine (Japan))

1990-05-01

121

Adsorption of Fe(II) and U(VI) to carboxyl-functionalized microspheres: The influence of speciation on uranyl reduction studied by titration and XAFS  

NASA Astrophysics Data System (ADS)

The chemical reduction of U(VI) by Fe(II) is a potentially important pathway for immobilization of uranium in subsurface environments. Although the presence of surfaces has been shown to catalyze the reaction between Fe(II) and U(VI) aqueous species, the mechanism(s) responsible for the enhanced reactivity remain ambiguous. To gain further insight into the U-Fe redox process at a complexing, non-conducting surface that is relevant to common organic phases in the environment, we studied suspensions containing combinations of 0.1 mM U(VI), 1.0 mM Fe(II), and 4.2 g/L carboxyl-functionalized polystyrene microspheres. Acid-base titrations were used to monitor protolytic reactions, and Fe K-edge and U L-edge X-ray absorption fine structure spectroscopy was used to determine the valence and atomic environment of the adsorbed Fe and U species. In the Fe + surface carboxyl system, a transition from monomeric to oligomeric Fe(II) surface species was observed between pH 7.5 and pH 8.4. In the U + surface carboxyl system, the U(VI) cation was adsorbed as a mononuclear uranyl-carboxyl complex at both pH 7.5 and 8.4. In the ternary U + Fe + surface carboxyl system, U(VI) was not reduced by the solvated or adsorbed Fe(II) at pH 7.5 over a 4-month period, whereas complete and rapid reduction to U(IV) nanoparticles occurred at pH 8.4. The U(IV) product reoxidized rapidly upon exposure to air, but it was stable over a 4-month period under anoxic conditions. Fe atoms were found in the local environment of the reduced U(IV) atoms at a distance of 3.56 Å. The U(IV)-Fe coordination is consistent with an inner-sphere electron transfer mechanism between the redox centers and involvement of Fe(II) atoms in both steps of the reduction from U(VI) to U(IV). The inability of Fe(II) to reduce U(VI) in solution and at pH 7.5 in the U + Fe + carboxyl system is explained by the formation of a transient, "dead-end" U(V)-Fe(III) complex that blocks the U(V) disproportionation pathway after the first electron transfer. The increased reactivity at pH 8.4 relative to pH 7.5 is explained by the reaction of U(VI) with an Fe(II) oligomer, whereby the bonds between Fe atoms facilitate the transfer of a second electron to the hypothetical U(V)-Fe(III) intermediate. We discuss how this mechanism may explain the commonly observed higher efficiency of uranyl reduction by adsorbed or structural Fe(II) relative to aqueous Fe(II).

Boyanov, Maxim I.; O'Loughlin, Edward J.; Roden, Eric E.; Fein, Jeremy B.; Kemner, Kenneth M.

2007-04-01

122

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

123

Functional group analysis of natural organic colloids and clay association kinetics using C(1s) spectromicroscopy  

NASA Astrophysics Data System (ADS)

The quantification of natural humic colloid functional group content and chemical association of humic substances with clay minerals exerts a crucial role in the colloid-borne mobility of actinides due to the functional group dependent strong interaction with multivalent metal ions. Functional group quantification in isolated fulvic acids of the Gorleben groundwater (Lower Saxony, NW Germany) by comparison of high resolution C(1s) NEXAFS spectra deconvolution with ^{13}C-NMR measurements showed good correlation (r^2> 0.9) and gives a potential quantification tool in complex natural groundwater Systems. Time resolved soft X-ray spectromicroscopy on dissolved organic carbon stabilized SWy-2 smectite colloids revealed an enrichment of carboxyl groups on broken edges (silanol/aluminol groups) at short contact times (1h). With longer contact times (7d, 6 months) the clay associated organic carbon increases and significantly higher aromatic content associated with basal surfaces were detected. The enhanced sorption of aromatic compounds can be related to an increase in mineral surface hydrophobicity and/or preferential sorption on charged siloxane surfaces.

Schäfer, T.; Hertkorn, N.; Artinger, R.; Claret, F.; Bauer, A.

2003-03-01

124

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

SciTech Connect

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.

Verkade, J.G.

1990-01-01

125

Olfactory Sensitivity and Odor Structure-Activity Relationships for Aliphatic Carboxylic Acids in CD-1 Mice  

PubMed Central

Using a conditioning paradigm, the olfactory sensitivity of CD-1 mice for a homologous series of aliphatic n-carboxylic acids (ethanoic acid to n-octanoic acid) and several of their isomeric forms was investigated. With all 14 odorants, the animals significantly discriminated concentrations as low as 0.03 ppm (parts per million) from the solvent, and with four odorants the best-scoring animals even detected concentrations as low as 3 ppt (parts per trillion). Analysis of odor structure-activity relationships showed that the correlation between olfactory detection thresholds of the mice for the unbranched carboxylic acids and carbon chain length can best be described as a U-shaped function with the lowest threshold values at n-butanoic acid. A significant positive correlation between olfactory detection thresholds and carbon chain length of the carboxylic acids with their branching next to the functional carboxyl group was found. In contrast, no such correlation was found for carboxylic acids with their branching at the distal end of the carbon chain relative to the functional carboxyl group. Finally, a significant correlation was found between olfactory detection thresholds and the position of the branching of the carboxylic acids. Across-species comparisons suggest that mice are more sensitive for short-chained (C2 to C4) aliphatic n-carboxylic acids than other mammalian species, but not for longer-chained ones (C5 to C8). Further comparisons suggest that odor structure-activity relationships are both substance class- and species-specific. PMID:22479594

Can Güven, Selçuk; Laska, Matthias

2012-01-01

126

Olfactory sensitivity and odor structure-activity relationships for aliphatic carboxylic acids in CD-1 mice.  

PubMed

Using a conditioning paradigm, the olfactory sensitivity of CD-1 mice for a homologous series of aliphatic n-carboxylic acids (ethanoic acid to n-octanoic acid) and several of their isomeric forms was investigated. With all 14 odorants, the animals significantly discriminated concentrations as low as 0.03 ppm (parts per million) from the solvent, and with four odorants the best-scoring animals even detected concentrations as low as 3 ppt (parts per trillion). Analysis of odor structure-activity relationships showed that the correlation between olfactory detection thresholds of the mice for the unbranched carboxylic acids and carbon chain length can best be described as a U-shaped function with the lowest threshold values at n-butanoic acid. A significant positive correlation between olfactory detection thresholds and carbon chain length of the carboxylic acids with their branching next to the functional carboxyl group was found. In contrast, no such correlation was found for carboxylic acids with their branching at the distal end of the carbon chain relative to the functional carboxyl group. Finally, a significant correlation was found between olfactory detection thresholds and the position of the branching of the carboxylic acids. Across-species comparisons suggest that mice are more sensitive for short-chained (C(2) to C(4)) aliphatic n-carboxylic acids than other mammalian species, but not for longer-chained ones (C(5) to C(8)). Further comparisons suggest that odor structure-activity relationships are both substance class- and species-specific. PMID:22479594

Can Güven, Selçuk; Laska, Matthias

2012-01-01

127

A conformation and orientation model of the carboxylic group of fatty acids dependent on chain length in a Langmuir monolayer film studied by polarization-modulation infrared reflection absorption spectroscopy.  

PubMed

The conformation of the carboxylic group of fatty acids in a Langmuir (L) monolayer film on water is described in relation to the aggregation property of the hydrocarbon chain. Polarization-modulation infrared reflection absorption spectra (PM-IRRAS) of L films of heptadecanoic acid (C(17)), octadecanoic acid (C(18)), and nonadecanoic acid (C(19)) exhibit systematic spectral changes in both the C-H and C=O stretching vibration regions. Through a stabilization analysis of the L films at a high surface pressure, the C(19) L film has been found outstandingly stable exhibiting no film shrink, while the other two compounds exhibit a large shrink at high surface pressure. By taking into account the uniquely high aggregation property of the hydrocarbon chains of C(19), the three major bands arising from the C=O stretching vibration mode propose three types of molecular conformations about the carboxylic group, which are elucidated by a balance of the hydration of the carboxylic group, the chain length of the hydrocarbon chain, and the surface pressure. PMID:20718412

Muro, Maiko; Itoh, Yuki; Hasegawa, Takeshi

2010-09-01

128

1-Aza­niumyl­cyclo­butane-1-carboxyl­ate monohydrate  

PubMed Central

In the title compound, C5H9NO2·H2O, 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) and 0.118?(7). In the crystal, N—H?O and O—H?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 carb­oxylate moities)], resulting in a two-dimensional layered structure lying parallel to (100). PMID:24764920

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

2014-01-01

129

Toward Functional Carboxylate-Bridged Diiron Protein Mimics: Achieving Structural Stability and Conformational Flexibility Using a Macrocylic Ligand Framework  

PubMed Central

A dinucleating macrocycle, H2PIM, containing phenoxylimine metal-binding units has been prepared. Reaction of H2PIM with [Fe2(Mes)4] (Mes = 2,4,6-trimethylphenyl) and sterically hindered carboxylic acids, Ph3CCO2H or ArTolCO2H (2,6-bis(p-tolyl)benzoic acid), afforded complexes [Fe2(PIM)(Ph3CCO2)2] (1) and [Fe2(PIM)(ArTolCO2)2] (2), respectively. X-ray diffraction studies revealed that these diiron(II) complexes closely mimic the active site structures of the hydroxylase components of bacterial multi-component monooxygenases (BMMs), particularly the syn disposition of the nitrogen donor atoms and the bridging ?-?1?2 and ?-?1?1 modes of the carboxylate ligands at the diiron(II) centers. Cyclic voltammograms of 1 and 2 displayed quasi-reversible redox couples at +16 and +108 mV vs. ferrocene/ferrocenium, respectively. Treatment of 2 with silver perchlorate afforded a silver(I)/iron(III) heterodimetallic complex, [Fe2(?-OH)2(ClO4)2(PIM)(ArTolCO2)Ag] (3), which was structurally and spectroscopically characterized. Complexes 1 and 2 both react rapidly with dioxygen. Oxygenation of 1 afforded a (?-hydroxo)diiron(III) complex [Fe2(?-OH)(PIM)(Ph3CCO2)3] (4), a hexa(?-hydroxo)tetrairon(III) complex [Fe4(?-OH)6(PIM)2(Ph3CCO2)2] (5), and an unidentified iron(III) species. Oxygenation of 2 exclusively formed di(carboxylato)diiron(III) compounds, a testimony to the role of the macrocylic ligand in preserving the dinuclear iron center under oxidizing conditions. X-ray crystallographic and 57Fe Mössbauer spectroscopic investigations indicated that 2 reacts with dioxygen to give a mixture of (?-oxo)diiron(III) [Fe2(?-O)(PIM)(ArTolCO2)2] (6) and di(?-hydroxo)diiron(III) [Fe2(?-OH)2(PIM)(ArTolCO2)2] (7) units in the same crystal lattice. Compounds 6 and 7 spontaneously convert to a tetrairon(III) complex, [Fe4(?-OH)6(PIM)2(ArTolCO2)2] (8), when treated with excess H2O. PMID:21682286

Do, Loi H.; Lippard, Stephen J.

2011-01-01

130

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

PubMed

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

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

2014-10-01

131

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

PubMed

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

Mathew, Thomas V; Kuriakose, Sunny

2013-10-01

132

Poly[?2-aqua-?2-(pyrazine-2-carboxyl­ato)-lithium  

PubMed Central

The structure of the title compound, [Li(C5H3N2O2)(H2O)]n, contains an LiI ion with a distorted trigonal–bipyramidal coordination environment involving the N and O atoms of pyrazine-2-carboxyl­ate ligands with a bridging carboxyl­ate group, and two aqua O atoms also in a bridging mode. The symmetry-related LiI ions bridged by a carboxyl­ate O atom and a coordinating water O atom form an Li2O2 unit with an Li?Li distance of 3.052?(4)?Å, which generates mol­ecular ribbons propagating in the c-axis direction. The ribbons are held together by a network of O—H?O hydrogen bonds in which the coordinating water mol­ecules act as donors and the carboxyl­ate O atoms as acceptors. PMID:22807764

Starosta, Wojciech; Leciejewicz, Janusz

2012-01-01

133

2-Isopropyl-5-methyl­cyclo­hexyl quinoline-2-carboxyl­ate  

PubMed Central

In the title compound, C20H25NO2, the cyclo­hexyl ring adopts a slightly disordered chair conformation. The dihedral angle between the mean planes of the quinoline ring and the carboxyl­ate group is 22.2?(6)°. In the crystal, weak C—H?N inter­actions make chains along [010]. PMID:24526982

Fazal, E.; Jasinski, Jerry P.; Anderson, Brian J.; Sudha, B. S.; Nagarajan, S.

2014-01-01

134

Structural Group Analysis of Functional Activation Maps  

Microsoft Academic Search

We present here a new method for cerebral activation detection over a group of subjects. This method is performed using individual activation maps of any sort. It aims at processing a group analysis while preserving individual information and at overcoming as far as possible limitations of the spatial normalization used to compare different subjects. We designed it such that it

O. Coulon; J.-F. Mangin; J.-B. Poline; M. Zilbovicius; D. Roumenov; Y. Samson; V. Frouin; I. Bloch

2000-01-01

135

Oriented binding of the His6-tagged carboxyl-tail of the L-type Ca2+ channel alpha1-subunit to a new NTA-functionalized self-assembled monolayer.  

PubMed

Oriented stable binding of functional proteins on surfaces is of fundamental interest for receptor/ligand studies in atomic force microscopy (AFM) and surface plasmon resonance (SPR) experiments. Here we have chosen the His6-tagged carboxyl-tail (C-tail) of the alpha1c-subunit of the L-type Ca2+ channel and calmodulin (CaM) as its cognitive partner as a model system to develop a new functional surface. Covalently attached self-assembled monolayers on ultraflat gold containing NTA-thiols to which the His6-tagged C-tail was bound and thiols with triethylene-glycol groups as matrix-thiols represented the system of choice. The topography of this surface was characterized using AFM; its ability to bind C-tail proteins oriented and stable was confirmed by SPR measurements and by complementary force spectroscopy experiments with a CaM4-construct covalently attached to the tip. The developed anchoring strategy can now be used to study receptor/ligand interactions in general applying force spectroscopy and SPR on His6-tagged proteins oriented immobilized onto this new NTA-functionalized self-assembled monolayer. PMID:16459605

Gamsjaeger, Roland; Wimmer, Barbara; Kahr, Heike; Tinazli, Ali; Picuric, Srdjan; Lata, Suman; Tampé, Robert; Maulet, Yves; Gruber, Hermann J; Hinterdorfer, Peter; Romanin, Christoph

2004-07-01

136

The Dehn function of Stallings' group To appear in Geometric and Functional Analysis  

E-print Network

The Dehn function of Stallings' group To appear in Geometric and Functional Analysis Will Dison Classification: 20F65 Keywords: Dehn function, Stallings' group, isoperimetric function, finiteness properties In memoriam John R. Stallings, 1935­2008. Abstract We prove that the Dehn function of a group of Stallings

Riley, Tim

137

Biomembrane disruption by silica-core nanoparticles: effect of surface functional group measured using a tethered bilayer lipid membrane  

PubMed Central

Engineered nanomaterials (ENM) have desirable properties that make them well suited for many commercial applications. However, a limited understanding of how ENM’s properties influence their molecular interactions with biomembranes hampers efforts to design ENM that are both safe and effective. This paper describes the use of a tethered bilayer lipid membrane (tBLM) to characterize biomembrane disruption by functionalized silica-core nanoparticles. Electrochemical impedance spectroscopy was used to measure the time trajectory of tBLM resistance following nanoparticle exposure. Statistical analysis of parameters from an exponential resistance decay model was then used to quantify and analyze differences between the impedance profiles of nanoparticles that were unfunctionalized, amine-functionalized, or carboxyl-functionalized. All of the nanoparticles triggered a decrease in membrane resistance, indicating nanoparticle-induced disruption of the tBLM. Hierarchical clustering allowed the potency of nanoparticles for reducing tBLM resistance to be ranked in the order amine > carboxyl ~ bare silica. Dynamic light scattering analysis revealed that tBLM exposure triggered minor coalescence for bare and amine-functionalized silica nanoparticles but not for carboxyl-functionalized silica nanoparticles. These results indicate that the tBLM method can reproducibly characterize ENM-induced biomembrane disruption and can distinguish the BLM-disruption patterns of nanoparticles that are identical except for their surface functional groups. The method provides insight into mechanisms of molecular interaction involving biomembranes and is suitable for miniaturization and automation for high-throughput applications to help assess the health risk of nanomaterial exposure or identify ENM having a desired mode of interaction with biomembranes. PMID:24060565

Liu, Ying; Zhang, Zhen; Zhang, Quanxuan; Baker, Gregory L.; Worden, R. Mark

2013-01-01

138

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

139

AN ANALYSIS OF LABORATORY AND CLASSROOM GROUP FUNCTIONING.  

ERIC Educational Resources Information Center

GROUP FUNCTIONING AND ACTIVITIES WERE STUDIED IN TWO CONTEXTS, THE LABORATORY AND THE REGULAR SCHOOL CLASSROOM. THE LABORATORY STUDY INVOLVED SMALL GROUP PROBLEM-SOLVING IN ARITHMETIC AND IN SOCIAL STUDIES. STUDIES CONSISTED OF GROUP PERFORMANCE, THE RELATIONSHIP OF THE HIGH ABILITY STUDENTS TO GROUP PERFORMANCE, THE RELATIVE IMPORTANCE OF…

HUDGINS, BRYCE B.; SMITH, LOUIS M.

140

Department and function: Group leader, Department of Toxicology  

E-print Network

Department and function: Group leader, Department of Toxicology Education: 1998-95 Chemistry Positions: 2000-recent: Group leader, Institute of Toxicology/ Hannover Medical School Major research://www.mh-hannover.de/ toxicology.html?&no_cache=1 #12;

Manstein, Dietmar J.

141

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

PubMed

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

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

2007-02-27

142

Structural Group Analysis of Functional Maps  

Microsoft Academic Search

We present here a new method for cerebral activation detection. This method is performed on individual activation maps of\\u000a any sort and aims at performing a multi-subject group analysis while preserving individual information and overcoming problems\\u000a induced by spatial normalisation. The analysis is made through a multi-scale object-based description of individual maps.\\u000a It is these structural descriptions which are compared,

Olivier Coulon; Jean-francois Mangin; Jean-baptiste Poline; Vincent Frouin; Isabelle Bloch

1999-01-01

143

Electrical transport and field-effect transistors using inkjet-printed SWCNT films having different functional side groups.  

PubMed

The electrical properties of random networks of single-wall carbon nanotubes (SWNTs) obtained by inkjet printing are studied. Water-based stable inks of functionalized SWNTs (carboxylic acid, amide, poly(ethylene glycol), and polyaminobenzene sulfonic acid) were prepared and applied to inkjet deposit microscopic patterns of nanotube films on lithographically defined silicon chips with a back-side gate arrangement. Source-drain transfer characteristics and gate-effect measurements confirm the important role of the chemical functional groups in the electrical behavior of carbon nanotube networks. Considerable nonlinear transport in conjunction with a high channel current on/off ratio of approximately 70 was observed with poly(ethylene glycol)-functionalized nanotubes. The positive temperature coefficient of channel resistance shows the nonmetallic behavior of the inkjet-printed films. Other inkjet-printed field-effect transistors using carboxyl-functionalized nanotubes as source, drain, and gate electrodes, poly(ethylene glycol)-functionalized nanotubes as the channel, and poly(ethylene glycol) as the gate dielectric were also tested and characterized. PMID:20481513

Gracia-Espino, Eduardo; Sala, Giovanni; Pino, Flavio; Halonen, Niina; Luomahaara, Juho; Mäklin, Jani; Tóth, Géza; Kordás, Krisztián; Jantunen, Heli; Terrones, Mauricio; Helistö, Panu; Seppä, Heikki; Ajayan, Pulickel M; Vajtai, Robert

2010-06-22

144

Derivatization of hydroxyl functional groups for liquid chromatography and capillary electroseparation.  

PubMed

The derivatization reactions commonly used to enhance the analytical signal in the HPLC and CE determination of compounds with hydroxyl functional groups are revised. Focus is placed on the determination of compounds having aliphatic alcohols and phenols while lacking other reactive functional groups. The derivatization with acyl chlorides, organic anhydrides, isocyanates and a variety of other approaches, including oxidation of primary and secondary alcohols, sulfonation, esterification with carboxylic acids, and the use of azides, sulfonyl chlorides and other reagents having miscellaneous leaving groups, is covered. Reactions mainly addressed to introduce a chromophore or a fluorophore in the analyte molecule, or to introduce a charge to enhance sensitivity in MS detection, or to enable CE separation are included. Applications related to the industrial quality control of raw materials and manufactured products, and to the evaluation of their environmental impact are emphasized. The problem of the different response factors of the derivatives when complex mixtures of oligomers are derivatized, as occurs with non-ionic surfactants (mainly fatty alcohol ethoxylates) and soluble synthetic polymers, is discussed. Other applications related to the biochemical, biomedical, pharmaceutical, nutritional and toxicological fields are also reviewed. The reactions, the criteria to be applied to select the reagent, and the characteristics of the derivatives in relation to separation and detection, are discussed. PMID:23643100

Escrig-Doménech, A; Simó-Alfonso, E F; Herrero-Martínez, J M; Ramis-Ramos, G

2013-06-28

145

Polymer nanoparticle-protein interface. Evaluation of the contribution of positively charged functional groups to protein affinity.  

PubMed

Cationic-functionalized polymer nanoparticles (NPs) show strikingly distinct affinities to proteins depending on the nature of the cationic functional group. N-Isopropylacrylamide (NIPAm) polymer NPs incorporating three types of positively charged functional groups (guanidinium, primary amino, and quaternary ammonium groups) were prepared by precipitation polymerization. The affinities to fibrinogen, a protein with an isoelectric point (pI) of 5.5, were compared using UV-vis spectrometry and a quartz crystal microbalance (QCM). Guanidinium-containing NPs showed the highest affinity to fibrinogen. The observation is attributed to strong, specific interactions with carboxylate groups on the protein surface. The affinity of the positively charged NPs to proteins with a range of pIs revealed that protein-NP affinity is due to a combination of ionic, hydrogen bonding, and hydrophobic interactions. Protein affinity can be modulated by varying the composition of these functional monomers in the acrylamide NPs. Engineered NPs containing the guanidinium group with hydrophobic and hydrogen bonding functional groups were used in an affinity precipitation for the selective separation of fibrinogen from a plasma protein mixture. Circular dichroism (CD) revealed that the protein was not denatured in the process of binding or release. PMID:23259461

Yonamine, Yusuke; Yoshimatsu, Keiichi; Lee, Shih-Hui; Hoshino, Yu; Okahata, Yoshio; Shea, Kenneth J

2013-01-23

146

Applications of proton magnetic resonance to functional group analysis  

Microsoft Academic Search

The application of proton magnetic resonance spectrometry to functional group analysis is discussed. Two examples are given viz. the distinction and simultaneous determination of primary, secondary, and tertiary functional groups in aliphatic monocarboxylic acids and in monovalent alcohols. Binary mixtures of acid types, and binary and ternary mixtures of alcohol types can be analysed with an accuracy of 5%m absolute

N. Meurs

1964-01-01

147

An efficient tandem approach for the synthesis of functionalized 2-pyridone-3-carboxylic acids using three-component reaction in aqueous media.  

PubMed

Novel analogs of 2-pyridone-3-carboxylic acids 4a-l have been prepared by the three-component reaction of 3-formyl chromone, Meldrum's acid, and primary amines in the presence of a catalytic amount of diammonium hydrogen phosphate in water. Good-to-high yields, easy work-up, and an environmentally friendly profile are the advantages of this method for the synthesis of 2-pyridone-3-carboxylic acid derivatives. PMID:24792225

Mehrparvar, Saber; Balalaie, Saeed; Rabbanizadeh, Mahnaz; Ghabraie, Elmira; Rominger, Frank

2014-08-01

148

Boron-containing amino carboxylic acid compounds and uses thereof  

DOEpatents

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.

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

2000-03-14

149

MICROBIAL TRANSFORMATION OF ESTERS OF CHLORINATED CARBOXYLIC ACIDS  

EPA Science Inventory

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

150

Co-exposure of carboxyl-functionalized single-walled carbon nanotubes and 17?-ethinylestradiol in cultured cells: effects on bioactivity and cytotoxicity.  

PubMed

17?-Ethinylestradiol (EE2) is the representative of environmental estrogens. Although EE2 can interact with some engineered nanoparticles (NPs), little is known about the bioactivity of NP-associated EE2 in organisms. In this study, we investigated the combined effects of the co-exposed carboxyl-functionalized single-walled carbon nanotubes (cf-SWCNTs) and EE2 in the human breast adenocarcinoma cell line (MCF-7 cells), focusing on the cytotoxicity and bioactivity. There were no significant differences in mitochondrial activity, membrane damage, and cell apoptosis when exposed to cf-SWCNTs with and without adsorbed EE2. However, the bioactivity of adsorbed EE2 on cf-SWCNTs was significantly inhibited. The calculated effective concentration of EE2 in cultured cells showed that less than 0.2% of the total adsorbed EE2 was released, indicating that most EE2 was retained on the cf-SWCNTs during cellular exposure. Furthermore, there were no obvious changes in the bioactivity of adsorbed EE2 in the culture medium containing 5-20% fetal bovine serum (FBS), even up to 10 days of incubation, indicating that the adsorbed EE2 on cf-SWCNTs is highly stable in the cell culture medium. These results mark a promising possibility for EE2 to be adsorbed by cf-SWCNTs in environmentally relevant settings and thereby influenced its toxicity and biological fate. This is also tempting for future studies involving risk assessment ways for association between NPs and contaminants in the environment. PMID:25383629

Song, Maoyong; Wang, Fengbang; Zeng, Luzhe; Yin, Junfa; Wang, Hailin; Jiang, Guibin

2014-12-01

151

Simultaneously functionalization and reduction of graphene oxide containing isocyanate groups  

NASA Astrophysics Data System (ADS)

A facile and efficient approach is developed to simultaneously functionalize and reduce graphene oxide (GO) containing isocyanate groups with toluene-2,4-diisocyanate (TDI). In this approach, the reaction between some isocyanate groups of TDI and oxygen containing functional groups of GO has occurred, with the GO reducing. The result can be found that others active isocyanate groups of TDI remain upon surface of GO, and the surface of GO changes from hydrophile to hydrophobic. In order to obtain the largest amount of isocyanate groups on surface of TDI-rGO, appropriate temperature and equilibrium time of the reaction are determined to be 75 °C and 5 h.

Lin, Peng; Meng, Linghui; Huang, Yudong; Liu, Li; Fan, Dapeng

2015-01-01

152

Breaking the Carboxyl Rule  

PubMed Central

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

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

2013-01-01

153

3,4-Di­methyl­phenyl quinoline-2-carboxyl­ate  

PubMed Central

In the title compound, C18H15NO2, the dihedral angle between the mean planes of the quinoline ring system and the phenyl ring is 48.1?(5)°. The mean plane of the carboxyl­ate group is twisted from the mean planes of the latter by 19.8?(8) and 64.9?(5)°, respectively. The crystal packing features weak C—H?O inter­actions, which form chains along [010]. PMID:24454268

Fazal, E.; Kaur, Manpreet; Sudha, B. S.; Nagarajan, S.; Jasinski, Jerry P.

2013-01-01

154

A DFT-based model for calculating solvolytic reactivity. The nucleofugality of aliphatic carboxylates in terms of Nf parameters.  

PubMed

The most comprehensive nucleofugality scale, based on the correlation and solvolytic rate constants of benzhydrylium derivatives, has recently been proposed by Mayr and co-workers (Acc. Chem. Res., 2010, 43, 1537-1549). In this work, the possibility of employing quantum chemical calculations in further determination of nucleofugality (Nf) parameters of leaving groups is explored. Whereas the heterolytic transition state of benzhydryl carboxylate cannot be optimized by quantum chemical calculations, the possibility of an alternative model reaction is examined in order to obtain nucleofugality parameters of various aliphatic carboxylates, which can properly be included in the current nucleofugality scale. For that purpose, ground and transition state structures have been optimized for the proposed model reaction, which includes anchimerically assisted heterolytic dissociation of cis-2,3-dihydroxycyclopropyl trans-carboxylates. The validity of the model reaction as well as of applied DFT methods in the presence of the IEFPCM solvation model is verified by correlating calculated free energies of activation of the model reaction with literature experimental data for solvolysis of reference dianisylmethyl carboxylates. For this purpose the ability of several functionals (including popular B3LYP) is examined, among which the M06-2X gives the best results. The very good correlation indicates acceptable accurate relative reactivities of aliphatic carboxylates, and enables the estimation of rate constants for solvolysis of other dianisylmethyl carboxylates in aqueous ethanol mixtures, from which the corresponding Nf parameters are determined using mentioned Mayr's equation. In addition, DFT calculations confirm the previous experimental observation that the abilities of aliphatic carboxylate leaving groups in solution are governed by the inductive effect of substituents attached to the carboxyl group. PMID:24964919

Denegri, Bernard; Mati?, Mirela; Kronja, Olga

2014-08-14

155

High Lipophilicty of Perfluoroalkyl Carboxylate and Sulfonate  

PubMed Central

Here we report on remarkably high lipophilicity of perfluoroalkyl carboxylate and sulfonate. A lipophilic nature of this emerging class of organic pollutants has been hypothesized as an origin of their bioaccumulation and toxicity. Both carboxylate and sulfonate, however, are considered hydrophilic while perfluroalkyl groups are not only hydrophobic but also oleophobic. Partition coefficients of homologous series of perfluoroalkyl and alkyl carboxylates between water and n-octanol were determined as a measure of their lipophilicity by ion-transfer cyclic voltammetry. Very similar lipophilicity of perfluoroalkyl and alkyl chains with the same length is demonstrated experimentally for the first time by fragment analysis of the partition coefficients. This finding is important for pharmaceutical and biomedical applications of perfluoroalkyl compounds. Interestingly, ?2 orders of magnitude higher lipophilicity of a perfluoroalkyl carboxylate or sulfonate in comparison to its alkyl counterpart is ascribed nearly exclusively to their oxoanion groups. The higher lipophilicity originates from a strong electron-withdrawing effect of the perfluoroalkyl group on the adjacent oxoanion group, which is weakly hydrated to decrease its hydrophilicity. In fact, the inductive effect is dramatically reduced for a fluorotelomer with an ethylene spacer between perfluorohexyl and carboxylate groups, which is only as lipophilic as its alkyl counterpart, nonanoate, and is 400 times less lipophilic than perfluorononanoate. The high lipophilicity of perfluoroalkyl carboxylate and sulfonate implies that their permeation across such a thin lipophilic membrane as a bilayer lipid membrane is limited by their transfer at a membrane/water interface. The limiting permeability is lower and less dependent on their lipophilicity than the permeability controlled by their diffusion in the membrane interior as assumed in the classical solubility-diffusion model. PMID:19170492

Jing, Ping; Rodgers, Patrick J.; Amemiya, Shigeru

2009-01-01

156

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

E-print Network

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

Manstein, Dietmar J.

157

Analysis of Functional Groups by Solubility and Infrared Analysis.  

ERIC Educational Resources Information Center

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

Turek, William N.

1984-01-01

158

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

PubMed

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

Ricci, Antonio; Brancale, Andrea

2012-04-15

159

On Exponential Moments for Functionals Defined on the Loop Group  

E-print Network

On Exponential Moments for Functionals Defined on the Loop Group David Ma´rquez-Carreras1. *Correspondence: David Ma´rquez-Carreras, Facultat de Matema`tiques, Universitat de Barcelona, Gran Via 585, 08007 as its associated loop group over G, have been developed, among others, by L. Gross,[1,2] M. P. Malliavin

Márquez-Carreras, David

160

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

SciTech Connect

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.

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

1991-11-01

161

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

NASA Technical Reports Server (NTRS)

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.

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

162

$q$-special functions and their occurrence in quantum groups  

Microsoft Academic Search

Summary In classical Lie group theory irreducible representation spaces are often de- composed into subspaces belonging to irreducible representations of a subgroup (or a chain of subgroups). Matrix elements of the representation w.r.t. a basis obtained in this way can often be expressed in terms of special functions. In par- ticular, spherical functions are the matrix elements being left and

T. H. Koornwinder

1992-01-01

163

Eating problems and interpersonal functioning among several groups of women.  

PubMed

This paper examines the relationship between eating disorders and problems in interpersonal functioning. Questionnaires that measure eating problems, interpersonal adjustment, and general neuroticism were completed by several groups of women: anorexic patients, persons whose interests or occupations involved a concern about bodily shape or condition (dancers, models, and athletes), and members of the general public. A substantial and significant relationship was found between eating symptomatology and interpersonal functioning in all groups. However, this association survived only in the anorexic patient group when general neuroticism was partialled out. We take this to imply that psychosocial difficulties are unlikely to play a strong role in the initial development of eating problems. PMID:7560134

O'Mahony, J F; Hollwey, S

1995-05-01

164

Nanoparticles made of multi-block copolymer of lactic acid and ethylene glycol containing periodic side-chain carboxyl groups for oral delivery of cyclosporine A  

PubMed Central

The purpose of this study was to evaluate the potential of new carboxylated multi-block copolymer of lactic acid and ethylene glycol (EL14) for nanoparticle (NP) formation and their ability to deliver high molecular weight hydrophobic drug—cyclosporine A (CsA). CsA-loaded EL14 NPs were compared with traditional poly(lactide-co-glycolide) (PLGA) NPs, both prepared by emulsion–diffusion–evaporation process. On the one hand, the increase in drug payload from 10 to 30 per cent for EL14 NPs showed no difference in particle size, however the entrapment efficiency tends to decrease from 50 to 43 per cent; on the other hand, the more hydrophobic PLGA showed an increasing trend in entrapment efficiency from 20 to 62 per cent with increasing particle size. Over 90 per cent of CsA was released in vitro from both the nanoparticulates; however, the release was much slower in the case of more hydrophobic PLGA. On in vivo evaluation in rats, the NPs made of EL14 showed a higher Cmax, a faster Tmax and enhanced tissue levels to that of PLGA that are crucial for CsA's activity and toxicity; however, the overall bioavailability of the nanoparticulates was similar and higher than Neoral. Together these data demonstrate the feasibility of NPs made of low molecular weight, hydrophilic polymer EL14 for efficient delivery of CsA. PMID:20504806

Ankola, D. D.; Battisti, A.; Solaro, R.; Kumar, M. N. V. Ravi

2010-01-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

166

Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN  

E-print Network

Point/Boiling Point If your carboxylic acid is a solid, take its melting point. If it is a liquid, take its micro- boiling point. C. Titration/Neutralization EquivalenceMolecular Weight Determination WeighCarboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN A. Solubility Tests: Water, Na

Jasperse, Craig P.

167

Implement the medical group revenue function. Create competitive advantage.  

PubMed

This article shows medical groups how they can employ new financial management and information technology techniques to safeguard their revenue and income streams. These managerial techniques stem from the application of the medical group revenue function, which is defined herein. This article also describes how the medical group revenue function can be used to create value by employing a database and a decision support system. Finally, the article describes how the decision support system can be used to create competitive advantage. Through the wise use of internally generated information, medical groups can negotiate better contract terms, improve their operations, cut their costs, embark on capital investment programs and improve market share. As medical groups gain market power by improving in these areas, they will be more attractive to potential strategic allies, payers and investment bankers. PMID:10181647

Colucci, C

1998-01-01

168

Detection of rare functional variants using group ISIS.  

PubMed

Genome-wide association studies have been firmly established in investigations of the associations between common genetic variants and complex traits or diseases. However, a large portion of complex traits and diseases cannot be explained well by common variants. Detecting rare functional variants becomes a trend and a necessity. Because rare variants have such a small minor allele frequency (e.g., <0.05), detecting functional rare variants is challenging. Group iterative sure independence screening (ISIS), a fast group selection tool, was developed to select important genes and the single-nucleotide polymorphisms within. The performance of the group ISIS and group penalization methods is compared for detecting important genes in the Genetic Analysis Workshop 17 data. The results suggest that the group ISIS is an efficient tool to discover genes and single-nucleotide polymorphisms associated to phenotypes. PMID:22373055

Niu, Yue S; Hao, Ning; An, Lingling

2011-01-01

169

Detection of rare functional variants using group ISIS  

PubMed Central

Genome-wide association studies have been firmly established in investigations of the associations between common genetic variants and complex traits or diseases. However, a large portion of complex traits and diseases cannot be explained well by common variants. Detecting rare functional variants becomes a trend and a necessity. Because rare variants have such a small minor allele frequency (e.g., <0.05), detecting functional rare variants is challenging. Group iterative sure independence screening (ISIS), a fast group selection tool, was developed to select important genes and the single-nucleotide polymorphisms within. The performance of the group ISIS and group penalization methods is compared for detecting important genes in the Genetic Analysis Workshop 17 data. The results suggest that the group ISIS is an efficient tool to discover genes and single-nucleotide polymorphisms associated to phenotypes. PMID:22373055

2011-01-01

170

Mapping of functional groups in metal-organic frameworks.  

PubMed

We determined the heterogeneous mesoscale spatial apportionment of functional groups in a series of multivariate metal-organic frameworks (MTV-MOF-5) containing BDC (1,4-benzenedicarboxylate) linkers with different functional groups--B (BDC-NH2), E (BDC-NO2), F [(BDC-(CH3)2], H [BDC-(OC3H5)2], and I [BDC-(OC7H7)2]--using solid-state nuclear magnetic resonance measurements combined with molecular simulations. Our analysis reveals that these methods discern between random (EF), alternating (EI and EHI), and various cluster (BF) forms of functional group apportionments. This combined synthetic, characterization, and computational approach predicts the adsorptive properties of crystalline MTV-MOF systems. This methodology, developed in the context of ordered frameworks, is a first step in resolving the more general problem of spatial disorder in other ordered materials, including mesoporous materials, functionalized polymers, and defect distributions within crystalline solids. PMID:23887875

Kong, Xueqian; Deng, Hexiang; Yan, Fangyong; Kim, Jihan; Swisher, Joseph A; Smit, Berend; Yaghi, Omar M; Reimer, Jeffrey A

2013-08-23

171

Coordination behavior of the carboxylate group in organotin(IV) derivatives of 2-[(2?,4?,6?-tribromophenylamido)]benzoic acid and 3-[(2?,4?,6?-tribromophenylamido)]propenoic acid: Spectroscopic studies  

Microsoft Academic Search

The complexes of two organic carboxylates (containing {O,O}-donor atoms) with Me2Sn(IV)Cl2, n-Bu2Sn(IV)Cl2, Bz2Sn(IV)Cl2, Oct2Sn(IV)O, Me3Sn(IV)Cl, n-Bu3Sn(IV)Cl, Ph3Sn(IV)Cl, Ph3Sn(IV)Cl, and Bz3Sn(IV)Cl having ligand-to-metal ratios of 1: 2 and 1: 1 were prepared by two different methods. The FT-IR spectra clearly demonstrated\\u000a that organotin(IV) moieties react with {O,O}-atoms of the ligands. It was found that in all cases the COO? group was

S. Shahzadi; K. Shahid; S. Ali

2007-01-01

172

Single or functionalized fullerenes interacting with heme group  

SciTech Connect

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.

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

2014-09-15

173

Carboxylic acid sorption regeneration process  

DOEpatents

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.

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

1995-05-02

174

Carboxylic acid sorption regeneration process  

DOEpatents

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.

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

1995-01-01

175

Comparison of solar cell performance of conducting polymer dyes with different functional groups  

NASA Astrophysics Data System (ADS)

Conductive polymer precursors, including carboxylic acid, cyano groups, amino groups, 5,2?:5?,2?-terthiophene-3?-carboxylic acid (TTCA), 3?-cyano-5,2?:5?,2?-terthiophene (CTT), and 3?,4?-diamino-2,2?:5?,2?-terthiophene (DATT) are synthesized. Electrochemically polymerized films of the precursors on a nanocrystalline TiO2 layer are examined as photo sensitizers, and the cell performance is compared. The photovoltaic cells are assembled with a polymer-coated TiO2 layer treated with TiCl4 as an anode and a Pt layer as a cathode in a propionitrile solution containing an iodide ion-based redox electrolyte. The charge-transfer processes of polymer-dyed cells are studied using impedance spectroscopy. The polymer dyes on the TiO2 surfaces are characterized by scanning electron microscope (SEM), atomic force microscope (AFM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). XPS results show that the conducting polymer dye, bearing a carboxylic acid group, is more strongly bound to the TiO2 layer in comparison with other groups. Various experimental parameters affecting the cell efficiency are optimized, including the scan rate, number of potential cycles, and terthiophene monomer concentration. Of these polymers, the best cell efficiency is attained for poly-TTCA containing a carboxylic acid group. The optimized cell with the poly-TTCA dye shows a short-circuit current of 6.78 mA cm-2, an open-circuit voltage of 0.54 V, and a fill factor of 63.6. An energy conversion efficiency of 2.32% is obtained with a cell area of 0.24 cm2 under an air mass 1.5 solar simulated light irradiation of 100 mW cm-2.

Yoon, Jang-Hee; Kim, Dong-Min; Yoon, Sang-Su; Won, Mi-Sook; Shim, Yoon-Bo

2011-10-01

176

Metabolism of Cyclohexane Carboxylic Acid by Alcaligenes Strain W1  

PubMed Central

Thirty-three microorganisms capable of growth with cyclohexane carboxylate as the sole source of carbon were isolated from mud, water, and soil samples from the Aberystwyth area. Preliminary screening and whole-cell oxidation studies suggested that, with one exception, all of the strains metabolized the growth substrate by beta-oxidation of the coenzyme A ester. This single distinctive strain, able to oxidize rapidly trans-4-hydroxycyclohexane carboxylate, 4-ketocyclohexane carboxylate, p-hydroxybenzoate, and protocatechuate when grown with cyclohexane carboxylate, was classified as a strain of Alcaligenes and given the number W1. Enzymes capable of converting cyclohexane carboxylate to p-hydroxybenzoate were induced by growth with the alicyclic acid and included the first unambiguous specimen of a cyclohexane carboxylate hydroxylase. Because it is a very fragile protein, attempts to stabilize the cyclohexane carboxylate hydroxylase so that a purification procedure could be developed have consistently failed. In limited studies with crude cell extracts, we found that hydroxylation occurred at the 4 position, probably yielding the trans isomer of 4-hydroxycyclohexane carboxylate. Simultaneous measurement of oxygen consumption and reduced nicotinamide adenine dinucleotide oxidation, coupled with an assessment of reactant stoichiometry, showed the enzyme to be a mixed-function oxygenase. Mass spectral analysis enabled the conversion of cyclohexane carboxylate to p-hydroxybenzoate by cell extracts to be established unequivocally, and all of our data were consistent with the pathway: cyclohexane carboxylate ? trans-4-hydroxycyclohexane carboxylate ? 4-ketocyclohexane carboxylate ? p-hydroxybenzoate. The further metabolism of p-hydroxybenzoate proceeded by meta fission and by the oxidative branch of the 2-hydroxy-4-carboxymuconic semialde-hyde-cleaving pathway. PMID:207665

Taylor, David G.; Trudgill, Peter W.

1978-01-01

177

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

SciTech Connect

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

R.L. Ames

2004-09-01

178

Galaxy and Group Baryonic Mass Functions for the RESOLVE Survey  

NASA Astrophysics Data System (ADS)

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).

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

179

Species, functional groups, and thresholds in ecological resilience  

USGS Publications Warehouse

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.

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

2012-01-01

180

A diagram technique for nonorthogonal electron group functions. I. Right coset decomposition of symmetric group  

NASA Astrophysics Data System (ADS)

For an N-electron system partitioned into a set of electron groups, an expanded arrow diagram (EAD) technique is proposed. It is useful when the wave function of the system is approximated by an antisymmetrized product of mutually nonorthogonal group functions. The technique provides a graphic representation of the right (left) coset decomposition of the symmetric group SN with respect to its subgroup S0 generated by all the intragroup permutations. The connection between the EADs and arrow diagrams of Matsen, Klein et al., and Wilson is stated and used to prove the validity of the arrow diagram representation of the double coset decomposition of SN with respect to S0, as well as to obtain the decomposition coefficients explicitly. The technique is applicable to systems composed of any finite or infinite number of electron groups each containing an arbitrary number of electrons.

Kantorovich, L. N.; Zapol, B. P.

1992-06-01

181

Generalized discrete orbit function transforms of affine Weyl groups  

E-print Network

The affine Weyl groups with their corresponding four types of orbit functions are considered. Two independent admissible shifts, which preserve the symmetries of the weight and the dual weight lattices, are classified. Finite subsets of the shifted weight and the shifted dual weight lattices, which serve as a sampling grid and a set of labels of the orbit functions, respectively, are introduced. The complete sets of discretely orthogonal orbit functions over the sampling grids are found and the corresponding discrete Fourier transforms are formulated. The eight standard one-dimensional discrete cosine and sine transforms form special cases of the presented transforms.

Tomasz Czy?ycki; Ji?í Hrivnák

2014-11-14

182

Langmuir monolayers from functionalized amphiphiles with epoxy terminal groups  

E-print Network

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

Vakni, David

183

Pelagic functional group modeling: Progress, challenges and prospects  

Microsoft Academic Search

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

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

2006-01-01

184

Pelagic functional group modeling: Progress, challenges and prospects  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

185

Synthesis of Silver Nanoclusters and Functionalization with Glucosamine for Glyconanoparticles  

Microsoft Academic Search

Functionalized nanoparticles are promising candidates for the construction of new nanomaterials. In this paper, glucosamine was covalently functionalized on the surface of silver nanoparticles to fabricate glyconanoparticles. Silver nanoclusters obtained by liquid-solid-solution (LSS) strategy under hydrothermal condition were first functionalized by carboxyl-terminated alkanethiol and the terminal carboxyl group was subsequently bonded with side-chain amino group of glucosamine surface through EDC\\/NHS

Murugan Veerapandian; Kyusik Yun

2010-01-01

186

New approaches to the synthesis of selected hydroxyquinolines and their hydroxyquinoline carboxylic acid analogues  

NASA Astrophysics Data System (ADS)

New approaches to the synthesis of selected crystalline hydroxyquinolines and their carboxylic acid analogues were elaborated in this paper with the auxiliary of computational and spectroscopic characterization, such as FTIR, NMR and single crystal X-ray measurements. The experimental data were further rationalized based on a DFT calculation method with B3LYP functional, which reflected the impact of electron donating or withdrawing groups on the energy level of HOMO orbitals and the reactivity of the substituted hydroxyquinolines.

Szala, Marcin; Nycz, Jacek E.; Malecki, Grzegorz J.

2014-08-01

187

Functional gene group analysis identifies synaptic gene groups as risk factor for schizophrenia  

PubMed Central

Schizophrenia is a highly heritable disorder with a polygenic pattern of inheritance and a population prevalence of ?1%. Previous studies have implicated synaptic dysfunction in schizophrenia. We tested the accumulated association of genetic variants in expert-curated synaptic gene groups with schizophrenia in 4673 cases and 4965 healthy controls, using functional gene group analysis. Identifying groups of genes with similar cellular function rather than genes in isolation may have clinical implications for finding additional drug targets. We found that a group of 1026 synaptic genes was significantly associated with the risk of schizophrenia (P=7.6 × 10?11) and more strongly associated than 100 randomly drawn, matched control groups of genetic variants (P<0.01). Subsequent analysis of synaptic subgroups suggested that the strongest association signals are derived from three synaptic gene groups: intracellular signal transduction (P=2.0 × 10?4), excitability (P=9.0 × 10?4) and cell adhesion and trans-synaptic signaling (P=2.4 × 10?3). These results are consistent with a role of synaptic dysfunction in schizophrenia and imply that impaired intracellular signal transduction in synapses, synaptic excitability and cell adhesion and trans-synaptic signaling play a role in the pathology of schizophrenia. PMID:21931320

Lips, E S; Cornelisse, L N; Toonen, R F; Min, J L; Hultman, C M; Holmans, P A; O'Donovan, M C; Purcell, S M; Smit, A B; Verhage, M; Sullivan, P F; Visscher, P M; Posthuma, D

2012-01-01

188

Conformally covariant boundary correlation functions with a quantum group  

E-print Network

Particular boundary correlation functions of conformal field theory are needed to answer some questions related to random conformally invariant curves known as Schramm-Loewner evolutions (SLE). In this article, we introduce a correspondence and establish its fundamental properties, which are used in companion articles for explicitly solving two such problems. The correspondence associates Coulomb gas type integrals to vectors in a tensor product representation of a quantum group, a q-deformation of the Lie algebra sl2. We show that desired properties of the functions are guaranteed by natural representation theoretical properties of the vectors.

Kalle Kytölä; Eveliina Peltola

2014-08-06

189

Properties of graphene inks stabilized by different functional groups  

Microsoft Academic Search

Different graphene inks have been synthesized by chemical methods. These uniform dispersions were stabilized by various functional groups such as room temperature ionic liquid, polyaniline, polyelectrolyte (poly[2,5-bis(3-sulfonatopropoxy)-1,4-ethynylphenylene-alt-1,4-ethynylphenylene] sodium salt) and poly(styrenesulfonate) (PSS). The dispersions can be easily cast into high-quality, free-standing films but with very different physiochemical properties such as surface tension and adhesion. SEM and AFM methods have been

Di Wei; Hongwei Li; Dongxue Han; Qixian Zhang; Li Niu; Huafeng Yang; Chris Bower; Piers Andrew; Tapani Ryhänen

2011-01-01

190

Correlation functions for pairs and groups of galaxies  

NASA Technical Reports Server (NTRS)

There are many studies on the correlation functions of galaxies, of clusters of galaxies, even of superclusters (e.g., Groth and Peebles 1977; Davies and Peebles 1983; Kalinkov and Kuneva 1985, 1986; Bahcall 1988 and references therein) but not so many on pairs and groups of galaxies. Results of the calculations of two-point correlation fuctions for some catalogs of pairs and groups of galaxies are given. It is assumed that the distances to pairs and groups of galaxies are given by their mean redshifts according to R = sigma (sup n, sub i-1) V sub i/nH (sub 0), where n is the number of galaxies in the system and H sub 0 = 100 km s(exp -1) Mpc(exp -1).

Kalinkov, M.; Kuneva, I.

1990-01-01

191

The p K a of the General Acid\\/Base Carboxyl Group of a Glycosidase Cycles during Catalysis:  A 13 C-NMR Study of Bacillus circulans Xylanase †  

Microsoft Academic Search

The 20 kDa xylanase from Bacillus circulans carries out hydrolysis of xylan via a two-step mechanism involving a covalent glycosyl-enzyme intermediate. In this double-displacement reaction, Glu78 functions as a nucleophile to form the intermediate, while Glu172 acts as a general acid catalyst during glycosylation, protonating the departing aglycone, and then as a general base during deglycosylation, deprotonating the attacking water.

Lawrence P. McIntosh; Greg Hand; Philip E. Johnson; Manish D. Joshi; Michael Körner; Leigh A. Plesniak; Lothar Ziser; Warren W. Wakarchuk; Stephen G. Withers

1996-01-01

192

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

SciTech Connect

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.

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

1987-11-10

193

4-Chloro-3-methyl­phenyl quinoline-2-carboxyl­ate  

PubMed Central

In the title compound, C17H12ClNO2, the dihedral angle between the mean planes of the quinoline ring system and the benzene ring is 68.7?(7)°. The mean plane of the carboxyl­ate group is twisted from the latter planes by 14.0?(1) and 80.2?(4)°, respectively. In the crystal, weak C—H?O inter­actions are observed, forming chains along [001]. In addition, ?–? stacking inter­actions [centroid–centroid distances = 3.8343?(13) and 3.7372?(13)Å] occur. No classical hydrogen bonds were observed. PMID:24454261

Fazal, E.; Kaur, Manpreet; Sudha, B. S.; Nagarajan, S.; Jasinski, Jerry P.

2013-01-01

194

Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations  

NASA Astrophysics Data System (ADS)

In pursuit of our ultimate goal to better understand the prodigious capacity of the marine macroalga Ulva lactuca (sea lettuce) for adsorbing a broad range of dissolved trace metals from seawater, we performed an initial characterization of its surface functional groups. Specifically, the number of distinct functional groups as well as their individual bulk concentrations and acid dissociation constants (pKas) were determined by potentiometric titrations in NaCl solutions of various ionic strengths (I = 0.01-5.0 M), under inert nitrogen atmosphere at 25°C. Depending on the ionic strength, Ulva samples were manually titrated down to pH 2 or 3 with 1 N HCl and then up to pH 10 with 1 N NaOH in steps of 0.1-0.2 units, continuously monitoring pH with a glass combination electrode. Titrations of a dehydrated Ulva standard reference material (BCR-279) were compared with fresh Ulva tissue cultured in our laboratory. A titration in filtered natural seawater was also compared with one in an NaCl solution of equal ionic strength. Equilibrium constants for the ionization of water in NaCl solutions as a function of ionic strength were obtained from the literature. Fits to the titration data ([H]T vs. pH) were performed with the FITEQL4.0 computer code using non-electrostatic 3-, 4-, and 5-site models, either by fixing ionic strength at its experimental value or by allowing it to be extrapolated to zero, while considering all functional group pKas and bulk concentrations as adjustable parameters. Since pKas and bulk concentrations were found to be strongly correlated, the latter were also fixed in some cases to further constrain the pKas. Whereas these calculations are currently ongoing, preliminary results point to three, possibly four, functional groups with pKas of about 4.1, 6.3, and 9.5 at I = 0. Bulk concentrations of the three groups are very similar, about 5-6×10-4 mol/g based on dry weight, which suggests that all are homogeneously distributed over the surface and probably part of a single macromolecular scaffold. Fresh Ulva tissue appears to contain the same three functional groups but at lower concentrations, based on wet weight. The titration in natural seawater was largely dominated by the non-carbonate alkalinity of the solution and could not be robustly modeled. Results of fits with ionic strengths fixed at their experimental values indicate that the pKas of all three groups display prominent Debije-Hückel-type behavior, hence that these acid dissociation reactions involve a different mechanism than metal-proton exchange reactions on mineral surfaces, whose distribution coefficients (i.e., equilibrium constants) generally show a weak ionic strength dependence.

Ebling, A. M.; Schijf, J.

2008-12-01

195

Functional group diversity of bee pollinators increases crop yield  

PubMed Central

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

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

2008-01-01

196

Organized thiol functional groups in mesoporous core shell colloids  

SciTech Connect

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.

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

2012-03-15

197

Finding sequence motifs in groups of functionally related proteins.  

PubMed Central

We have developed a method for rapidly finding patterns of conserved amino acid residues (motifs) in groups of functionally related proteins. All 3-amino acid patterns in a group of proteins of the type aa1 d1 aa2 d2 aa3, where d1 and d2 are distances that can be varied in a range up to 24 residues, are accumulated into an array. Segments of the proteins containing those patterns that occur most frequently are aligned on each other by a scoring method that obtains an average relatedness value for all the amino acids in each column of the aligned sequence block based on the Dayhoff relatedness odds matrix. The automated method successfully finds and displays nearly all of the sequence motifs that have been previously reported to occur in 33 reverse transcriptases, 18 DNA integrases, and 30 DNA methyltransferases. PMID:1689055

Smith, H O; Annau, T M; Chandrasegaran, S

1990-01-01

198

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

E-print Network

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. ...

Friedle, Simone, 1976-

2009-01-01

199

Functional renormalization group study of nuclear and neutron matter  

E-print Network

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

Matthias Drews; Wolfram Weise

2014-10-31

200

Local Group velocity versus gravity: the coherence function  

E-print Network

In maximum-likelihood analyses of the Local Group (LG) acceleration, the object describing nonlinear effects is the coherence function (CF), i.e. the cross-correlation coefficient of the Fourier modes of the velocity and gravity fields. We study the CF both analytically, using perturbation theory, and numerically, using a hydrodynamic code. The dependence of the function on Omega_m and the shape of the power spectrum is very weak. The only cosmological parameter that the CF is strongly sensitive to is the normalization sigma_8 of the underlying density field. Perturbative approximation for the function turns out to be accurate as long as sigma_8 is smaller than about 0.3. For higher normalizations we provide an analytical fit for the CF as a function of sigma_8 and the wavevector. The characteristic decoherence scale which our formula predicts is an order of magnitude smaller than that determined by Strauss et al. This implies that present likelihood constraints on cosmological parameters from analyses of the LG acceleration are significantly tighter than hitherto reported.

Michal Chodorowski; Pawel Ciecielag

2001-11-19

201

Spectral functions from the functional renormalization group at finite temperature and density  

E-print Network

We present a viable method to obtain real-time quantities such as spectral functions or transport coefficients at finite temperature and density within a non-perturbative Functional Renormalization Group approach. Our method is based on a thermodynamically consistent truncation of the flow equations for 2-point functions with analytically continued frequency components in the originally Euclidean external momenta. We demonstrate its feasibility by calculating the mesonic spectral functions in the quark-meson model at different temperatures and quark chemical potentials, in particular around the critical endpoint in the phase diagram of the model.

Ralf-Arno Tripolt; Nils Strodthoff; Lorenz von Smekal; Jochen Wambach

2014-07-31

202

Templated aqueous synthesis of inorganics within carboxyl-containing block copolymer domains  

E-print Network

Template-directed, aqueous-based syntheses of nanoscale inorganic materials in carboxyl-functionalized block copolymer domains (nanoreactors) were demonstrated. First, the successful application of electroless metal ...

Boontongkong, Yot

2002-01-01

203

Changes in bird functional diversity across multiple land uses: interpretations of functional redundancy depend on functional group identity.  

PubMed

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

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

2013-01-01

204

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

PubMed Central

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

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

2013-01-01

205

Preparation and Properties of Enterosorbents Based on Carboxylated Microcrystalline Cellulose  

Microsoft Academic Search

Features of a non-traditional method of preparation of cellulose-based cation-exchange enterosorbents using nitrogen (IV) oxide are discussed. The proposed approach involves sequential use of oxidative and acid-hydrolyzing functions of nitrogen (IV) oxide to convert ordinary cellulose into carboxylated microcrystalline cellulose. X-ray phase analysis and transmission electron microscopy data show evidence of a topochemical character of cellulose microcrystal modification with carboxyl

E. V. Gert; V. I. Torgashov; O. V. Zubets; F. N. Kaputskii

2005-01-01

206

Structural characterization and function determination of a nonspecific carboxylate esterase from the amidohydrolase superfamily with a promiscuous ability to hydrolyze methylphosphonate esters.  

PubMed

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 × 10(5) M(-1) s(-1)), 2-naphthyl propionate (kcat/Km = 1.5 × 10(5) M(-1) s(-1)), 1-naphthyl acetate (kcat/Km = 7.5 × 10(3) M(-1) s(-1)), 4-methylumbelliferyl acetate (kcat/Km = 2.7 × 10(3) M(-1) s(-1)), 4-nitrophenyl acetate (kcat/Km = 2.3 × 10(5) M(-1) s(-1)), and 4-nitrophenyl butyrate (kcat/Km = 8.8 × 10(5) M(-1) s(-1)). The best organophosphonate ester substrates included ethyl 4-nitrophenyl methylphosphonate (kcat/Km = 3.8 × 10(5) M(-1) s(-1)) and isobutyl 4-nitrophenyl methylphosphonate (kcat/Km = 1.1 × 10(4) 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

Xiang, Dao Feng; Kumaran, Desigan; Swaminathan, Subramanyam; Raushel, Frank M

2014-06-01

207

8, 1000510020, 2008 Carboxyl groups in  

E-print Network

with a dissociation constant of about pK =3.4, which fits well into the interval represented by fulvic and humic acids. This implies that HULIS10 can not be regarded as polycarboxilic acid. The average molecular mass of HULIS de molecule ranges from 248 to 305 Da. It was concluded that HULIS are a moderately strong/weak acid

Boyer, Edmond

208

Application of macrobenthos functional groups to estimate the ecosystem health in a semi-enclosed bay.  

PubMed

In this study, the functional group concept was first applied to evaluate the ecosystem health of Bohai Bay. Macrobenthos functional groups were defined according to feeding types and divided into five groups: a carnivorous group (CA), omnivorous group (OM), planktivorous group (PL), herbivorous group (HE), and detritivorous group (DE). Groups CA, DE, OM, and PL were identified, but the HE group was absent from Bohai Bay. Group DE was dominant during the study periods. The ecosystem health was assessed using a functional group evenness index. The functional group evenness values of most sampling stations were less than 0.40, indicating that the ecosystem health was deteriorated in Bohai Bay. Such deterioration could be attributed to land reclamation, industrial and sewage effluents, oil pollution, and hypersaline water discharge. This study demonstrates that the functional group concept can be applied to ecosystem health assessment in a semi-enclosed bay. PMID:23849956

Peng, Shitao; Zhou, Ran; Qin, Xuebo; Shi, Honghua; Ding, Dewen

2013-09-15

209

Oxidation of alpha-ketoglutarate is required for reductive carboxylation in cancer cells with mitochondrial defects  

PubMed Central

Summary Mammalian cells generate citrate by decarboxylating pyruvate in the mitochondria to supply the tricarboxylic acid (TCA) cycle. In contrast, hypoxia and other impairments of mitochondrial function induce an alternative pathway that produces citrate by reductively carboxylating ?-ketoglutarate (AKG) via NADPH-dependent isocitrate dehydrogenase (IDH). It is unknown how cells generate reducing equivalents necessary to supply reductive carboxylation in the setting of mitochondrial impairment. Here we identified shared metabolic features in cells using reductive carboxylation. Paradoxically, reductive carboxylation was accompanied by concomitant AKG oxidation in the TCA cycle. Inhibiting AKG oxidation decreased reducing equivalent availability and suppressed reductive carboxylation. Interrupting transfer of reducing equivalents from NADH to NADPH by nicotinamide nucleotide transhydrogenase increased NADH abundance and decreased NADPH abundance while suppressing reductive carboxylation. The data demonstrate that reductive carboxylation requires bidirectional AKG metabolism along oxidative and reductive pathways, with the oxidative pathway producing reducing equivalents used to operate IDH in reverse. PMID:24857658

Mullen, Andrew R.; Hu, Zeping; Shi, Xiaolei; Jiang, Lei; Boroughs, Lindsey K.; Kovacs, Zoltan; Boriack, Richard; Rakheja, Dinesh; Sullivan, Lucas B.; Linehan, W. Marston; Chandel, Navdeep S.; DeBerardinis, Ralph J.

2014-01-01

210

Functional renormalization group approach for inhomogeneous interacting Fermi systems  

NASA Astrophysics Data System (ADS)

The functional renormalization group (fRG) approach has the property that, in general, the flow equation for the two-particle vertex generates O (N4) independent variables, where N is the number of interacting states (e.g., sites of a real-space discretization). In order to include the flow equation for the two-particle vertex, one needs to make further approximations if N becomes too large. We present such an approximation scheme, called the coupled-ladder approximation, for the special case of an onsite interaction. Like the generic third-order-truncated fRG, the coupled-ladder approximation is exact to second order and is closely related to a simultaneous treatment of the random phase approximation in all channels, i.e., summing up parquet-type diagrams. The scheme is applied to a one-dimensional model describing a quantum point contact.

Bauer, Florian; Heyder, Jan; von Delft, Jan

2014-01-01

211

Functional renormalization group study of the Anderson-Holstein model  

NASA Astrophysics Data System (ADS)

We present a comprehensive study of the spectral and transport properties in the Anderson-Holstein model both in and out of equilibrium using the functional renormalization group (fRG). We show how the previously established machinery of Matsubara and Keldysh fRG can be extended to include the local phonon mode. Based on the analysis of spectral properties in equilibrium we identify different regimes depending on the strength of the electron-phonon interaction and the frequency of the phonon mode. We supplement these considerations with analytical results from the Kondo model. We also calculate the nonlinear differential conductance through the Anderson-Holstein quantum dot and find clear signatures of the presence of the phonon mode.

Laakso, M. A.; Kennes, D. M.; Jakobs, S. G.; Meden, V.

2014-02-01

212

Fermionic functional renormalization group approach to superfluid phase transition  

NASA Astrophysics Data System (ADS)

A fermionic functional renormalization group (FRG) is applied to describe the superfluid phase transition of the two-component fermionic system with attractive contact interaction. The connection between the fermionic FRG approach and the conventional Bardeen-Cooper-Schrieffer (BCS) theory with Gorkov and Melik-Barkhudarov (GMB) correction are clarified in detail in the weak coupling region by using the renormalization group flow of the fermionic four-point vertex with particle-particle and particle-hole scattering contributions. To go beyond the BCS+GMB theory, coupled FRG flow equations of the fermion self-energy and the four-point vertex are studied under an Ansatz concerning their frequency/momentum dependence. We found that the fermion self-energy turns out to be substantial even in the weak coupling region, and the frequency dependence of the four-point vertex is essential to obtain the correct asymptotic-ultraviolet behavior of the flow for the self-energy. The superfluid transition temperature and the associated chemical potential are calculated in the region of negative scattering lengths.

Tanizaki, Yuya; Fej?s, Gergely; Hatsuda, Tetsuo

2014-04-01

213

Binding modes of carboxylate- and acetylacetonate-linked chromophores to homodisperse polyoxotitanate nanoclusters.  

PubMed

The binding of carboxylate- and acetylacetonate-linked chromophores to homodisperse polyoxotitanate nanoclusters with 17 Ti atoms or more are surveyed and found to be limited to chelate-bidentate and the bridging modes, the former being dominant for the acetylacetonate-linked chromophores, the latter for the carboxylate linkers. Chromophores with acetylacetonate linking groups invariably bind in the chelate mode, whereas carboxylic acid terminated chromophores more frequently are observed to have the bridging mode, with the exception of three cases in which a strong electron-donating substituent is present on two different sensitizers. The calculations for isonicotinateand nitrophenylacetylacetonate functionalized Ti17 clusters show the observed binding modes to correspond to the lower energy functionalized clusters, but do not predict the difference between the cinnamic acid and dimethylaminocinnamic acid binding to Ti17, which are bridging and chelate respectively. Both binding modes were never observed to occur for a single chromophore, even when synthetic conditions were varied. Density of state calculations show broadening and splitting of the chromophore LUMO on complexation due to interaction with the cluster's conduction band, as well as frequent penetration of sensitizer orbitals into the bandgap of the functionalized nanoparticle. PMID:22709348

Sokolow, Jesse D; Trzop, Elzbieta; Chen, Yang; Tang, Jiji; Allen, Laura J; Crabtree, Robert H; Benedict, Jason B; Coppens, Philip

2012-07-18

214

Vibrational spectra and structures of zinc carboxylates II. Anhydrous zinc acetate and zinc stearate  

Microsoft Academic Search

A normal mode analysis was carried out for a monoclinic anhydrous zinc acetate crystal in which the acetate groups had bridging bidentate coordination forms, and spectral assignments were made. Based on the assignments, a relation between the coordination structure of the carboxylate groups around the zinc atom and the vibrational frequencies of the carboxylate rocking mode was found. This relation

Tsutomu Ishioka; Youko Shibata; Mizuki Takahashi; Isao Kanesaka

1998-01-01

215

Radical additions to chiral hydrazones: stereoselectivity and functional group compatibility.  

PubMed

Free radical additions to imino compounds offer increased synthetic accessibility of chiral amines, but lack of general methods for stereocontrol has hindered their development. This review focuses on two asymmetric amine synthesis strategies designed to address this problem, with emphasis on addition of functionalized radicals which may facilitate applications to synthesis of complex targets. First, chiral N-acylhydrazones are acceptors for intermolecular radical additions of a wide range of primary, secondary, and tertiary alkyl halides to the C=N bond, with radicals generated under manganese-, tin-, or boron-mediated conditions. A variety of aldehydes and ketones serve as viable precursors for the chiral hydrazones, and the highly stereoselective reactions tolerate electrophilic functionality in both coupling components. Second, radical precursors may be linked to chiral ?-hydroxyhydrazones via a silicon tether to the hydroxyl group; conformational constraints impart stereocontrol during 5-exo radical cyclization under stannyl- or thiyl-mediated conditions. The silicon tether may later be removed to reveal the formal adducts of hydroxymethyl, vinyl, acetyl, and 2-oxoethyl radicals to the C=N bond. Methodology development and applications to biologically important targets are discussed. PMID:21842359

Friestad, Gregory K

2012-01-01

216

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

217

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

NASA Astrophysics Data System (ADS)

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.

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

218

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

PubMed

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

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

219

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

PubMed Central

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

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

2013-01-01

220

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

PubMed Central

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

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

2013-01-01

221

Plant Species and Functional Group Combinations Affect Green Roof Ecosystem Functions  

PubMed Central

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

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

2010-01-01

222

Evaluation of a series of prolylamidepyridines as the chiral derivatization reagents for enantioseparation of carboxylic acids by LC-ESI-MS/MS and the application to human saliva.  

PubMed

Mass spectrometry has become a popular analytical tool because of its high sensitivity and specificity. The use of a chiral derivatization reagent for the mass spectrometry (MS) detection seems to be efficient for the enantiomeric separation of racemates. However, the number of chiral reagents for the liquid chromatography (LC)-MS/MS analysis is very limited. According to these observations, we are currently in the process of developing novel labeling reagents for chiral molecules in MS/MS analysis. The derivatization reagent that is effective for enhancing not only the electrospray ionization-MS/MS sensitivity but also the reversed-phase LC resolution of carboxylic acid enantiomers should have a highly proton-affinitive moiety and an asymmetric structure near the reactive functional group. Furthermore, the resulting derivative has to provide a characteristic product ion suitable for the selected reaction monitoring. Based upon these considerations, a series of prolylamidepyridines ((S)-N-pyrrolidine-2-carboxylic acid N-(pyridine-2-yl)amide (PCP2), (S)-N-pyrrolidine-2-carboxylic acid N-(pyridine-3-yl)amide, and (S)-N-pyrrolidine-2-carboxylic acid N-(pyridine-4-yl)amide) was synthesized as ideal labeling reagents for the enantioseparation of chiral carboxylic acids and evaluated in terms of separation efficiency and detection sensitivity by ultra-performance LC (UPLC)-MS/MS. Among the synthesized reagents, PCP2 was the most efficient chiral derivatization reagent for the enantioseparation of carboxylic acid. The Rs values and the detection limits of the derivatives of non-steroidal anti-inflammatory drugs, which were selected as the representative carboxylic acids, were in the range of 2.52-6.07 and 49-260 amol, respectively. The sensitive detection of biological carboxylic acids (detection limits, 32-520 amol) was also carried out by the proposed method using PCP2 and UPLC-MS/MS. The PCP2 was applied to the determination of carboxylic acids in human saliva. Several biological carboxylic acids, such as lactic acid (LA), 3-hydroxybutylic acid, maric acid, succinic acid, ?-ketoglutalic acid, and citric acid, were clearly identified in the saliva of healthy persons and diabetic patients. Furthermore, the ratio of D-LA in diabetic patients was higher than that in normal subjects. Judging from these results, PCP2 seems to be a useful chiral derivatization reagent for the determination not only of chiral, but also achiral, carboxylic acids in real samples. PMID:24500756

Kuwabara, Tomohiro; Takayama, Takahiro; Todoroki, Kenichiro; Inoue, Koichi; Min, Jun Zhe; Toyo'oka, Toshimasa

2014-04-01

223

Functional movement screen scores in a group of running athletes.  

PubMed

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

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

2014-04-01

224

Effects of the acylcarnitine-transferase blocking agent sodium 2[5-(4-chlorophenyl)-pentyl]-oxirane-2-carboxylate (POCA) on metabolism and regional function in the underperfused canine myocardium.  

PubMed

We investigated the effects of sodium 2[5-(4-chlorophenyl)-pentyl]-oxirane-2-carboxylate (POCA) on regional myocardial function and metabolism in anesthetized, thoracotomized dogs subjected to a 53.5% reduction in flow through the circumflex branch of the left coronary artery (LCX). Regional function in the area supplied by the LCX and the left anterior descending coronary artery (LAD) was assessed by means of two pairs of subendocardially inserted ultrasonic transducers. Hemoglobin content, oxygen saturation, pH, PCO2, PO2, lactate, glucose, and free fatty acids were determined in arterial and local venous blood obtained from the area supplied by the LCX. POCA (20 mg/kg/20 min i.v.) induced a transient decrease in left ventricular power and cardiac output. Arterial free fatty acid (FFA) levels increased continuously throughout the experiment, whilst arterial glucose levels showed a continuous decrease. FFA uptake, lactate release, and oxygen uptake were reduced in the underperfused area by POCA. At the same time, POCA induced a transient increase in end-diastolic segment length and a sustained decrease in systolic shortening during the ejection phase in the underperfused area. No changes in regional function were observed in the area perfused by the nonconstricted LAD. PMID:2581080

Seitelberger, R; Kraupp, O; Winkler, M; Brugger, G; Raberger, G

1985-01-01

225

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

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

Barron, Andrew R

2014-06-14

226

Charge distribution on the S layer of Bacillus stearothermophilus NRS 1536/3c and importance of charged groups for morphogenesis and function.  

PubMed Central

The distribution and functional significance of charged groups on the outer and inner faces of the S layer from Bacillus stearothermophilus NRS 1536/3c was investigated. Chemical modification of the exposed amino or carboxyl groups was performed on whole cells, isolated S layers self-assembled in vitro, and cell wall fragments (S layer attached to the peptidoglycan-containing sacculus). Without chemical modification, S layer self-assembly products could be labeled with polycationic ferritin, while S layers on whole cells could not. Following treatment with glutaraldehyde, whole cells were uniformly labeled with polycationic ferritin. Whole cells treated with glutaraldehyde and glycine methyl ester in the presence of carbodiimide did not bind polycationic ferritin significantly above background. Treatment of cell wall fragments with amino-specific, homobifunctional cross-linkers or with carbodiimide alone rendered the S layer protein nonextractable with sodium dodecyl sulfate. After amidation of the accessible carboxyl groups, the modified, guanidine hydrochloride-extractable S layer protomers did not self-assemble into regularly structured lattices. N-Amidination with ethylacetimidate did not interfere with the self-assembly of the isolated protomers. N-Acetylation resulted in a considerable destabilization of the S layer lattice, as seen by the release of a large amount of modified protomers during the reaction. N-Succinylation led to a complete disintegration of the protein lattice. These results indicated that only the inner face of the S layer carried a net negative charge. On both faces, free amino and carboxyl groups of adjacent protomers were arranged in proximity so as to contribute by electrostatic interactions to the cohesion of the protomers in the two-dimensional array. The native charge of the protomers was required for both the in vitro self-assembly of the isolated subunits and the maintenance of the structural integrity of the S layer lattice. Among other functions, the biological significance of the S layers may be in masking the electronegative charge of the cell wall proper. Images PMID:3584071

Sára, M; Sleytr, U B

1987-01-01

227

Quantifying Additive Interactions of the Osmolyte Proline with Individual Functional Groups of Proteins: Comparisons with Urea and Glycine Betaine, Interpretation of m-Values  

PubMed Central

To quantify interactions of the osmolyte L-proline with protein functional groups and predict its effects on protein processes, we use vapor pressure osmometry to determine chemical potential derivatives dµ2/dm3 = µ23 quantifying preferential interactions of proline (component 3) with 21 solutes (component 2) selected to display different combinations of aliphatic or aromatic C, amide, carboxylate, phosphate or hydroxyl O, and/or amide or cationic N surface. Solubility data yield µ23 values for 4 less-soluble solutes. Values of µ23 are dissected using an ASA-based analysis to test the hypothesis of additivity and obtain ?-values (proline interaction potentials) for these eight surface types and three inorganic ions. Values of µ23 predicted from these ?-values agree with experiment, demonstrating additivity. Molecular interpretation of ?-values using the solute partitioning model yields partition coefficients (Kp) quantifying the local accumulation or exclusion of proline in the hydration water of each functional group. Interactions of proline with native protein surface and effects of proline on protein unfolding are predicted from ?-values and ASA information and compared with experimental data, with results for glycine betaine and urea, and with predictions from transfer free energy analysis. We conclude that proline stabilizes proteins because of its unfavorable interactions with (exclusion from) amide oxygens and aliphatic hydrocarbon surface exposed in unfolding, and that proline is an effective in vivo osmolyte because of the osmolality increase resulting from its unfavorable interactions with anionic (carboxylate and phosphate) and amide oxygens and aliphatic hydrocarbon groups on the surface of cytoplasmic proteins and nucleic acids. PMID:23909383

Diehl, Roger C.; Guinn, Emily J.; Capp, Michael W.; Tsodikov, Oleg V.; Record, M. Thomas

2013-01-01

228

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)

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.

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

2015-01-01

229

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

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

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

2015-01-25

230

Fragrance material review on methyl hexyl oxo cyclopentanone carboxylate.  

PubMed

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

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

2012-10-01

231

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2012 CFR

... Polyethylene resins, carboxyl modified. 177.1600 Section 177.1600...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Polyethylene resins, carboxyl modified. Carboxyl-modified...

2012-04-01

232

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2010 CFR

... Polyethylene resins, carboxyl modified. 177.1600 Section 177.1600...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Polyethylene resins, carboxyl modified. Carboxyl-modified...

2010-04-01

233

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2013 CFR

... Polyethylene resins, carboxyl modified. 177.1600 Section 177.1600...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Polyethylene resins, carboxyl modified. Carboxyl-modified...

2013-04-01

234

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

Code of Federal Regulations, 2011 CFR

... Polyethylene resins, carboxyl modified. 177.1600 Section 177.1600...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Polyethylene resins, carboxyl modified. Carboxyl-modified...

2011-04-01

235

Critical design features of phenyl carboxylate-containing polymer microbicides.  

PubMed

Recent studies of cellulose-based polymers substituted with carboxylic acids like cellulose acetate phthalate (CAP) have demonstrated the utility of using carboxylic acid groups instead of the more common sulfate or sulfonate moieties. However, the pK(a) of the free carboxylic acid group is very important and needs careful selection. In a polymer like CAP the pK(a) is approximately 5.28. This means that under the low pH conditions found in the vaginal lumen, CAP would be only minimally soluble and the carboxylic acid would not be fully dissociated. These issues can be overcome by substitution of the cellulose backbone with a moiety whose free carboxylic acid group(s) has a lower pK(a). Hydroxypropyl methylcellulose trimellitate (HPMCT) is structurally similar to CAP; however, its free carboxylic acids have pK(a)s of 3.84 and 5.2. HPMCT, therefore, remains soluble and molecularly dispersed at a much lower pH than CAP. In this study, we measured the difference in solubility and dissociation between CAP and HPMCT and the effect these parameters might have on antiviral efficacy. Further experiments revealed that the degree of acid substitution of the cellulose backbone can significantly impact the overall efficacy of the polymer, thereby demonstrating the need to optimize any prospective polymer microbicide with respect to pH considerations and the degree of acid substitution. In addition, we have found HPMCT to be a potent inhibitor of CXCR4, CCR5, and dual tropic strains of human immunodeficiency virus in peripheral blood mononuclear cells. Therefore, the data presented herein strongly support further evaluation of an optimized HPMCT variant as a candidate microbicide. PMID:16940105

Rando, Robert F; Obara, Sakae; Osterling, Mark C; Mankowski, Marie; Miller, Shendra R; Ferguson, Mary L; Krebs, Fred C; Wigdahl, Brian; Labib, Mohamed; Kokubo, Hiroyasu

2006-09-01

236

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

ERIC Educational Resources Information Center

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…

Myers, Scott A.

2012-01-01

237

The Social Support Function in Epilepsy Self-Help Groups.  

ERIC Educational Resources Information Center

Results of a preliminary survey of epilepsy self-help group members are presented, and effects relating to stigmatization, reasons for participation, asserted curative factors, and formal-only versus informal participation in the self-help group process are examined. Societal reaction to people with epilepsy is viewed as a major contributor to…

Droge, David; And Others

1986-01-01

238

Specificity of dopachrome tautomerase and inhibition by carboxylated indoles. Considerations on the enzyme active site.  

PubMed Central

Dopachrome tautomerase (EC 5.3.2.3) catalyses the tautomerization of dopachrome to 5,6-dihydroxyindole-2-carboxylic acid (DHICA) within the melanin-formation pathway. We have analysed a series of substrate analogues and related compounds as possible substrates and inhibitors of tautomerization. The enzyme appears to be highly specific since D-dopachrome, alpha-methyldopachrome, dopaminochrome, adrenochrome methyl ether and deoxyadrenochrome are not substrates. Conversely, dopachrome tautomerase catalyses the tautomerization of dopachrome methyl ester, suggesting that a carboxy group, either free or as a methyl ester, is essential for enzyme recognition. No inhibition of dopachrome tautomerization was observed in the presence of either semiquinonic compounds, such as tropolone and L-mimosine, or pyrrole-2-carboxylic acid and unsubstituted indole. However, a number of indole derivatives, including DHICA, the product of dopachrome tautomerization, and the analogues 5-hydroxyindole-2-carboxylic and indole-2-carboxylic acid were able to inhibit the enzyme. Furthermore, indoles with a side chain at position 3 of the ring and containing a carboxylic group at the gamma-position of this chain, such as L-tryptophan or indole-3-propionic acid, are stronger inhibitors of the enzyme. Indole-3-carboxylic acid, indole-3-acetic acid and indole-3-butyric acid are very weak inhibitors, showing that the carboxylic group needs to be located at an optimal distance from the indole ring to mimic the carboxylic group at position 2 on the authentic substrate. PMID:1859367

Aroca, P; Solano, F; Garcia-Borrón, J C; Lozano, J A

1991-01-01

239

A Manganese Carboxylate with Geometrically Frustrated Magnetic Layers of Novel Topology  

E-print Network

A Manganese Carboxylate with Geometrically Frustrated Magnetic Layers of Novel Topology Xin-Yi Wang synthesized and characterized by single-crystal X-ray diffraction and magnetic measurements. The Mn2+ cations, linked by the carboxylate groups of the THFTC, form a geometrically frustrated network with a novel (3

240

Specificity of dopachrome tautomerase and inhibition by carboxylated indoles. Considerations on the enzyme active site.  

PubMed

Dopachrome tautomerase (EC 5.3.2.3) catalyses the tautomerization of dopachrome to 5,6-dihydroxyindole-2-carboxylic acid (DHICA) within the melanin-formation pathway. We have analysed a series of substrate analogues and related compounds as possible substrates and inhibitors of tautomerization. The enzyme appears to be highly specific since D-dopachrome, alpha-methyldopachrome, dopaminochrome, adrenochrome methyl ether and deoxyadrenochrome are not substrates. Conversely, dopachrome tautomerase catalyses the tautomerization of dopachrome methyl ester, suggesting that a carboxy group, either free or as a methyl ester, is essential for enzyme recognition. No inhibition of dopachrome tautomerization was observed in the presence of either semiquinonic compounds, such as tropolone and L-mimosine, or pyrrole-2-carboxylic acid and unsubstituted indole. However, a number of indole derivatives, including DHICA, the product of dopachrome tautomerization, and the analogues 5-hydroxyindole-2-carboxylic and indole-2-carboxylic acid were able to inhibit the enzyme. Furthermore, indoles with a side chain at position 3 of the ring and containing a carboxylic group at the gamma-position of this chain, such as L-tryptophan or indole-3-propionic acid, are stronger inhibitors of the enzyme. Indole-3-carboxylic acid, indole-3-acetic acid and indole-3-butyric acid are very weak inhibitors, showing that the carboxylic group needs to be located at an optimal distance from the indole ring to mimic the carboxylic group at position 2 on the authentic substrate. PMID:1859367

Aroca, P; Solano, F; Garcia-Borrón, J C; Lozano, J A

1991-07-15

241

Influence of substituents and functional groups on the surface composition of ionic liquids.  

PubMed

We have performed a systematic study addressing the surface behavior of a variety of functionalized and non-functionalized ionic liquids (ILs). From angle-resolved X-ray photoelectron spectroscopy, detailed conclusions on the surface enrichment of the functional groups and the molecular orientation of the cations and anions is derived. The systems include imidazolium-based ILs methylated at the C2 position, a phenyl-functionalized IL, an alkoxysilane-functionalized IL, halo-functionalized ILs, thioether-functionalized ILs, and amine-functionalized ILs. The results are compared with the results for corresponding non-functionalized ILs where available. Generally, enrichment of the functional group at the surface is only observed for systems that have very weak interaction between the functional group and the ionic head groups. PMID:24643947

Kolbeck, Claudia; Niedermaier, Inga; Deyko, Alexey; Lovelock, Kevin R J; Taccardi, Nicola; Wei, Wei; Wasserscheid, Peter; Maier, Florian; Steinrück, Hans-Peter

2014-04-01

242

Hydrolysis of organonitrate functional groups in aerosol particles  

SciTech Connect

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.

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

2012-10-19

243

Opinion Changing Aversion Functions for Group Settlement Modeling  

Microsoft Academic Search

\\u000a Opinion changing aversion (OCA) functions are used to quantify the decision makers’ resistance to opinion changing. By introducing\\u000a OCA functions of polynomial form we will show that if each expert has a quadratic opinion changing aversion function then\\u000a the minimum-cost solution is nothing else but the weighted average of the individual optimal solutions where the weights are\\u000a the relative importances

Matteo Brunelli; Robert Fullér; József Mezei

244

Investigation of Carboxylic Acid-Neodymium Conversion Films on Magnesium Alloy  

NASA Astrophysics Data System (ADS)

The new carboxylic acid-neodymium anhydrous conversion films were successfully prepared and applied on the AZ91D magnesium alloy surface by taking absolute ethyl alcohol as solvent and four kinds of soluble carboxylic acid as activators. The corrosion resistance of the coating was measured by potentiodynamic polarization test in 3.5 wt.% NaCl solution in pH 7.0. The morphology, structure, and constituents of the coating were observed by scanning electron microscope, energy dispersivespectrum, x-ray photoelectron spectrum, and Fourier infrared spectrometer. Results show that corrosion resistance properties of samples coated with four different anhydrous conversion films were improved obviously. The corrosion potential increased, corrosion current density decreased, and polarization resistance increased. Among these four kinds of conversion films the one added with phytic exhibits the best corrosion resistant property. The mechanism of anhydrous-neodymium conversion film formation is also analyzed in this paper. It reveals that the gadolinium conversion coating is mainly composed of stable Nd2O3, MgO, Mg(OH)2, and carboxylate of Nd. And that the sample surface is rich in organic functional groups.

Cui, Xiufang; Liu, Zhe; Lin, Lili; Jin, Guo; Wang, Haidou; Xu, Binshi

2015-01-01

245

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

PubMed Central

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

2014-01-01

246

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

PubMed

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

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

2014-02-01

247

Reactivity of End-functionalized Polymers Containing Diels-Alder Functional Groups  

NASA Astrophysics Data System (ADS)

Incorporation of reversible covalent bond into macromolecular systems has proven useful in engineering novel responsive architectures, and Diels-Alder bonding in this context is now well established. However, efficient synthesis of end-functionalized polymers is a major obstacle hindering further development of responsive and modular polymer architectures. In this current research, two immiscible polymers, poly(methyl methacrylate) (PMMA) and poly(benzyl methacrylate) (PBzMA) with controlled molecular weight, bearing terminal furan-maleimide groups, are prepared via Reversible Addition-Fragmentation chain transfer (RAFT) polymerization. The reactivity of such end-functionalized polymers is explored to expose the relationship between chain composition and their ability to undergo modular cross-coupling to form monodisperse block copolymers. To elucidate how reaction conditions affect the efficiency of the Diels-Alder reaction, Hydrogen Nuclear Magnetic Resonance (H-NMR) and Size Exclusion Chromatography (SEC) techniques are actively applied. Experimental results will be interpreted on the basis of dissimilarity between interaction energies of polymer segments and the concentration of reactive groups.

Meng, Yuan; Zhang, Yuan; Anthamatten, Mitchell

2013-03-01

248

Functional Group Transformations in Derivatives of 6Oxoverdazyl Marcin Jasinski,  

E-print Network

demonstrated in radical 1c. Pt-catalyzed reduction of the NO2 group led to the aniline derivative, which generation in columnar discotic radicals10,11 as the first step toward photovoltaic applications. Further

Kaszynski, Piotr

249

Molecular Structure of Cyclopropane carboxylic acid  

NSDL National Science Digital Library

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

2003-04-11

250

Unitary representations of a loop ax+b group, Wiener measure and Gamma-function  

E-print Network

We construct a family of irreducible unitary representations of the loop affine group of a line (ax+b group) with central extension on the Hilbert space of square integrable functions with respect to the Wiener measure. We relate the matrix coefficients of the elements of the loop ax+b group to the loop analogue of the Gamma-function.

Anton M. Zeitlin

2010-12-21

251

Estimating functional groups in human gut microbiome with probabilistic topic models.  

PubMed

In this paper, based on the functional elements derived from non-redundant CDs catalogue, we show that the configuration of functional groups in meta-genome samples can be inferred by probabilistic topic modeling. The probabilistic topic modeling is a Bayesian method that is able to extract useful topical information from unlabeled data. When used to study microbial samples (assuming that relative abundance of functional elements is already obtained by a homology-based approach), each sample can be considered as a "document," which has a mixture of functional groups, while each functional group (also known as a "latent topic") is a weight mixture of functional elements (including taxonomic levels, and indicators of gene orthologous groups and KEGG pathway mappings). The functional elements bear an analogy with "words." Estimating the probabilistic topic model can uncover the configuration of functional groups (the latent topic) in each sample. The experimental results demonstrate the effectiveness of our proposed method. PMID:22987126

Chen, Xin; He, TingTing; Hu, Xiaohua; Zhou, Yanhong; An, Yuan; Wu, Xindong

2012-09-01

252

Post-Functionalized Polymer Brushes for Bio-Separation: Tuning GFP Adsorption via Functional Group Display  

NASA Astrophysics Data System (ADS)

An inexpensive and robust biosensor platform that can be tuned to separate and/or detect complex mixtures of biomolecules while minimizing reagents would be of great use for military, homeland security, and medical diagnostic applications. Gradient surfaces of poly(2-hydroxyethyl methacrylate) (PHEMA) brushes have been previously shown to spatially localize biomolecule binding, while minimizing non-specific adsorption of the same biomolecule on other regions of the gradient specimen. In order to further improve the specificity and to provide latent functionality for detection of the binding events, post-polymerization modification of PHEMA with various functional groups has been investigated. Using standard succinimide-based coupling, hydroxyl pendants of PHEMA brushes were conjugated to oligo-peptides, alkanes and oligo(ethylene glycol) (OEG) through an alpha-terminus primary amine. Ellipsometry, contact angle, XPS and ER-FTIR spectroscopy indicated that coupling occurred with efficiencies ranging from 10-40%. Post-functionalization of PHEMA with OEG and hexadecane allows manipulation of the hydrophilicity of the surface and thus tuning of Green Fluorescent Protein (GFP) binding.

Diamanti, Steve; Arifuzzaman, Shafi; Genzer, Jan; Naik, Rajesh; Vaia, Richard

2007-03-01

253

An experimental test of the effect of plant functional group diversity on arthropod diversity  

Microsoft Academic Search

Characteristics used to categorize plant species into functional groups for their effects on ecosystem functioning may also be relevant to higher trophic levels. In addition, plant and consumer diversity should be positively related because more diverse plant communities offer a greater variety of resources for the consumers. Thus, the functional group composition and richness of a plant community may affect

Amy J. Symstad; Evan Siemann; John Haarstad

2000-01-01

254

Effects of spatial grouping on the functional response of predators  

USGS Publications Warehouse

A unified mechanistic approach is given for the derivation of various forms of functional response in predator-prey models. The derivation is based on the principle-of-mass action but with the crucial refinement that the nature of the spatial distribution of predators and/or opportunities for predation are taken into account in an implicit way. If the predators are assumed to have a homogeneous spatial distribution, then the derived functional response is prey-dependent. If the predators are assumed to form a dense colony or school in a single (possibly moving) location, or if the region where predators can encounter prey is assumed to be of limited size, then the functional response depends on both predator and prey densities in a manner that reflects feeding interference between predators. Depending on the specific assumptions, the resulting functional response may be of Beddington-DeAngelis type, of Hassell-Varley type, or ratio-dependent.

Cosner, C.; DeAngelis, D.L.; Ault, J.S.; Olson, D.B.

1999-01-01

255

Functionalization of poly-SNS-anchored carboxylic acid with Lys and PAMAM: surface modifications for biomolecule immobilization/stabilization and bio-sensing applications.  

PubMed

Poly(2-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl) (SNS) acetic acid) was electrochemically deposited on graphite electrodes and functionalized with lysine (Lys) amino acid and poly(amidoamine) derivatives (PAMAM G2 and PAMAM G4) to investigate their matrix properties for biosensor applications. Glucose oxidase (GOx) was immobilized onto the modified surface as the model enzyme. X-Ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to report the surface properties of the matrices in each step of the biosensor construction. The biosensors were characterized in terms of their operational and storage stabilities and the kinetic parameters (K(app)(m) and I(max)). Three new glucose biosensors revealed good stability, featuring low detection limits (19.0 ?M, 3.47 ?M and 2.93 ?M for lysine-, PAMAM G2- and PAMAM G4-functionalized electrodes, respectively) and prolonged the shelf lives (4, 5, and 6 weeks for Lys-, PAMAM G2- and PAMAM G4-modified electrodes, respectively). The proposed biosensors were tested for glucose detection on real human blood serum samples. PMID:22832474

Demirci, Sema; Emre, Fatma Bilge; Ekiz, Fulya; O?uzkaya, Funda; Timur, Suna; Tanyeli, Cihangir; Toppare, Levent

2012-09-21

256

Langmuir-Blodgett deposition selects carboxylate headgroup coordination  

NASA Astrophysics Data System (ADS)

Infrared reflection-absorption spectroscopy results on stearic acid Langmuir monolayers containing Mn, Co, and Cd ions show that on the water surface, the ions induce unidentate and bidentate (both chelate and bridged) coordination in the carboxylate headgroup with some trace of undissociated acid. Moreover, with Cd and Mn ions in subphase, the preferred coordination is found to be unidentate, whereas for Co, bidentate chelate is most preferred. After transfer onto amorphous substrate, not all coordinations are found to exist in the same ratio for the deposited metal stearate monolayers. More specifically, after transfer, Mn is found to coordinate with the carboxylate group as bidentate chelate, Cd as unidentate and bidentate bridged (with unidentate as the preferred coordination), and Co as preferably bidentate bridged (although all coordinations are present). Results suggest a specific interaction in each case, as the metal-carboxylate pair at the water surface is transferred to the substrate surface during Langmuir-Blodgett deposition.

Mukherjee, Smita; Datta, Alokmay

2011-10-01

257

Separation of certain carboxylic acids utilizing cation exchange membranes  

DOEpatents

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.

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

1984-01-01

258

Separation of certain carboxylic acids utilizing cation exchange membranes  

DOEpatents

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.

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

1983-05-09

259

Quadratic function fields with exponent two ideal class group  

Microsoft Academic Search

It has been shown by Madden that there are only finitely many quadratic extensions of k(x), k a finite field, in which the ideal class group has exponent two and the infinity place of k(x) ramifies. We give a characterization of such fields that allow us to find a full list of all such field extensions for future reference. In

Victor Bautista-Ancona; Javier Diaz-Vargas

2006-01-01

260

Quadratic Function Fields with Exponent Two Ideal Class Group  

Microsoft Academic Search

It has been shown by Madden that there are only finitely many quadratic extensions of k(x), k a finite field, in which the ideal class group has exponent two and the infinity place of k(x) ramifies. We give a characterization of such fields that allow us to find a full list of all such field extensions for future reference. In

Victor Bautista-Ancona; Javier Diaz-Vargas

2005-01-01

261

Hydrolysis of organonitrate functional groups in aerosol particles , John E. Shilling2  

E-print Network

Hydrolysis of organonitrate functional groups in aerosol particles Shang Liu1 , John E Drive, La Jolla CA, 92093-0221 Running title: Hydrolysis of organonitrates Keywords: organonitrate, organic nitrate, hydrolysis, secondary organic aerosol #12; Abstract Organonitrate (ON) groups

Russell, Lynn

262

?-Amino Esters from the Reductive Ring Opening of Aziridine-2-carboxylates.  

PubMed

A general study is undertaken to examine the scope of the reductive ring opening of aziridine-2-carboxylates with samarium diiodide. The competition between C-C and C-N bond cleavage is examined as a function of the nature of the N-substituent of the aziridine, the nature of the substituent in the 3-position of the aziridine, and whether the substituent in the 3-position is in a cis or trans relationship with the carboxylate in the 2-position. The desired C-N bond cleavage leads to ?-amino esters that are the predominant products for most aziridines with an N-activating group. However, C-C cleavage products are observed with an aryl group in the 3-position; this can be particularly pronounced with cis-aziridines where a nearly equal mixture of the two is observed. Exclusive formation of the C-N cleavage product is observed for all aziridines with the strongly N-activating p-toluene sulfonate group. Similarly high selectivity is observed for the 2-trimethylsilylethyl sulfonate group (SES), which is easier to remove. The utility of these methods is illustrated in the synthesis of protected forms of (R)-?(3)-DOPA and l-DOPA from the same aziridine, the former by SmI2-mediated reductive opening at C-2 and the latter by palladium-mediated reductive opening at C-3. PMID:25329528

Zhao, Wenjun; Lu, Zhenjie; Wulff, William D

2014-10-20

263

Role of functional groups on Aspergillus niger biomass in the detoxification of hexavalent chromium.  

PubMed

Chromium (VI) contamination is not uncommon, especially near industries involved in leather tanning, chrome painting, metal cleaning and processing, wood preservation and alloy preparation. The mutagenic and carcinogenic properties of Chromium (VI) necessitate effective remedial processes. Difficulties associated with chemical and physical techniques to remediate a Chromium (VI) contaminated site to EPA recommended level (50 ppm), in addition to higher costs involved, assert the need for bioremedial measures. Biosorption can be one such solution to clean up heavy metal contamination. The objective of this study was to examine the main aspects of a possible strategy for the removal of Chromium (VI), employing Aspergillus niger biomass. The roles played by amines, carboxylic acids, phosphates, in Chromium (VI) biosorption were studied. Amino and the carboxy groups on the fungal cell wall play an important role in sorption. However, the role of carboxy group was far less than amino group. Surface adsorption of Chromium (VI) was also seen by scanning electron microscopy (SEM) thus indicating involvement of ion-exchange and surface adsorption mechanism in removal of Chromium (VI) ions. PMID:21117413

Narvekar, Sneha; Vaidya, Varsha K

2009-10-01

264

Heat capacity, saturation vapor pressure, and thermodynamic functions of ethyl esters of C3-C5 and C18 carboxylic acids  

NASA Astrophysics Data System (ADS)

The heat capacities of ethyl propanoate (EPr), ethyl n-pentanoate (EPen), and ethyl n-octadecanoate (ethyl stearate, ESt) were measured by vacuum adiabatic calorimetry in the temperature range of 6 to 373 K. Triple point temperatures, fusion enthalpies and entropies, and purity of the samples of the sub-stances under study were determined. The saturation vapor pressures for EPr and EPen were determined by comparative ebulliometry in an atmospheric pressure range of 4.0 to 101.7 kPa. The normal boiling points and vaporization enthalpies vs. temperature were obtained. The standard thermodynamic functions ( S, H, and G) were calculated for the condensed and ideal gas states on the basis of the experimental data. The vapor pressures of the atmospheric range were extrapolated to entire ranges of the liquid phases of EPr and EPen using the principle of corresponding states and the combined processing of pT parameters and low-temperature differences in the heat capacities of an ideal gas and liquid.

Agafonova, L. E.; Varushchenko, R. M.; Druzhinina, A. I.; Polyakova, O. V.; Kolesov, Yu. S.

2011-09-01

265

Effects of Oxygen-Containing Functional Groups on Supercapacitor Performance  

SciTech Connect

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.

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

2014-06-19

266

Methyl 2-[2-(benzyl­oxycarbon­ylamino)­propan-2-yl]-5-hy­droxy-1-methyl-6-oxo-1,6-dihydro­pyrimidine-4-carboxyl­ate  

PubMed Central

The title pyrimidine derivative, C18H21N3O6, was obtained by the reaction of methyl 2-[2-(benzyl­oxycarbon­yl)amino­propan-2-yl]-5-hy­droxy-6-oxo-1,6-dihydro­pyrimidine-4-carboxyl­ate with dimethyl sulfate in dimethyl sulfoxide. The mol­ecule has a V-shaped structure, the phenyl and the pyrimidine rings making a dihedral angle of 43.1?(1)°. The methyl group substituting the pyrimidine ring deviates slightly from the ring mean-plane [C—N—C—C torsion angle = 5.49?(15)°], and the methyl ester substituent has a conformation suitable for the formation of an intra­molecular O—H?O hydrogen bond with the hydroxyl functionality. In the crystal, molecules are linked into chains along the b axis by N—H?O hydrogen bonds. PMID:23284488

Shang, Zhenhua; Tao, Xiao; Ha, Jing; Yu, Fuda

2012-01-01

267

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

SciTech Connect

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

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

2014-05-28

268

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

PubMed Central

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

Kaushik, J. K.; Bhat, R.

1999-01-01

269

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

270

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

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

2014-01-01

271

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

PubMed Central

[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

Kim, Kwanghyun; Lee, Byungjoon; Lee, Wanhee

2014-01-01

272

Ru-Catalyzed Decarboxylative Annulations of ?-Keto Acids with Internal Alkynes: Dual Roles of COOH as Directing Group and Leaving Group.  

PubMed

Carboxylic acid serving as both directing and leaving group was discovered in Ru-catalyzed decarboxylative annulations of ?-keto acids with alkynes. The well-established protocol showed high functional group tolerance, which provided an efficient and alternative route to the coumarone backbone. PMID:25491036

Tan, Hui; Li, Hongji; Wang, Jiawang; Wang, Lei

2014-12-01

273

Crystal structures of (2 R,4 R)-2-(polyhydroxyalkyl)-1,3-thiazolidine-4-carboxylic acids: condensation products of l-cysteine with d-hexoses  

Microsoft Academic Search

We report herein the first crystal structures of (4-carboxy-1,3-thiazolidin-2-yl)pentitols [2-(polyhydroxyalkyl)thiazolidine-4-carboxylic acids], condensation products of l-cysteine with d-galactose and d-mannose: 2-(d-galacto-pentahydroxypentyl)thiazolidine-4-carboxylic acid hydrate, Gal-Cys·H2O (1), and 2-(d-manno-pentahydroxypentyl)thiazolidine-4-carboxylic acid hydrate, Man-Cys·H2O (2). In 1 and 2 the compounds crystallize as zwitterions, with the carboxylic groups deprotonated and the thiazolidine N atoms protonated. The sugar moiety and carboxylate group are in a cis

Miros?aw Tarnawski; Katarzyna ?lepokura; Tadeusz Lis

2011-01-01

274

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 ...

275

Atomic resolution imaging and spectroscopy of barium atoms and functional groups on graphene oxide  

E-print Network

Atomic resolution imaging and spectroscopy of barium atoms and functional groups on graphene oxide: Graphene oxide Functional groups Scanning transmission electron microscopy Transmission electron microscopy of graphene oxide modified with Ba2þ . In our experiments, which are carried out at 80 kV, the acquisition

Dunin-Borkowski, Rafal E.

276

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...

277

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

Microsoft Academic Search

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

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

2010-01-01

278

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

E-print Network

of functional magnetic resonance imaging (fMRI) signals that is capable of revealing connected brain systems to perform group-level analyses on datasets consisting of hundreds of scan sessions by combining the results fMRI; group ICA; bagging; clustering; bootstrap I. INTRODUCTION Functional magnetic resonance

Yuille, Alan L.

279

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...

280

Vibrational spectra and structures of zinc carboxylates II. Anhydrous zinc acetate and zinc stearate  

NASA Astrophysics Data System (ADS)

A normal mode analysis was carried out for a monoclinic anhydrous zinc acetate crystal in which the acetate groups had bridging bidentate coordination forms, and spectral assignments were made. Based on the assignments, a relation between the coordination structure of the carboxylate groups around the zinc atom and the vibrational frequencies of the carboxylate rocking mode was found. This relation was applied to zinc stearate to determine its coordination form, and we found that zinc stearate had a bridging bidentate form.

Ishioka, Tsutomu; Shibata, Youko; Takahashi, Mizuki; Kanesaka, Isao

1998-10-01

281

Synthesis of chromium(III) complex with 1-hydroxy-2-pyridinone-6-carboxylic acid as insulin-mimetic agent and its spectroscopic and computational studies  

NASA Astrophysics Data System (ADS)

The new complex of chromium(III) and 1-hydroxy-2-pyridinone-6-carboxylic acid was synthesized and its preparation routes were reported. Mass spectrometry and elemental analysis indicated the formation of chromium complex with the metal-to-ligand mole ratio of 1:3. Combination of spectroscopic measurement and spectral computations based on the density functional theory suggested that 1-hydroxy-2-pyridinone-6-carboxylic acid was a bidentate ligand using one oxygen atom at pyridinone carbonyl group and the other at N-oxide group as donor atoms upon chelation with chromium(III), forming the six-coordinate complex with five-membered chelate rings. Due to the enhanced stability of the chelate rings, such the pathway of chelation was theoretically predicted to be more favorable than the case where the carboxylate oxygen atom of ligand participated in the chelation. According to the preliminary tests, the chromium(III) complex with 1-hydroxy-2-pyridinone-6-carboxylic acid was found to be active in lowering plasma glucose levels in vivo.

Yasarawan, Nuttawisit; Thipyapong, Khajadpai; Sirichai, Somsak; Ruangpornvisuti, Vithaya

2013-01-01

282

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

PubMed Central

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

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

2012-01-01

283

Structural Basis for Low-Affinity Binding of Non-R2 Carboxylate-Substituted Tricyclic Quinoline Analogs to CK2?: Comparative Molecular Dynamics Simulation Studies.  

PubMed

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

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

2015-02-01

284

Quantification of Chemical States, Dissociation Constants and Contents of Oxygen-containing Groups on the Surface of Biochars Produced at Different Temperatures.  

PubMed

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 (pKa), 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

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

2015-01-01

285

Red electroluminescence of ruthenium sensitizer functionalized by sulfonate anchoring groups.  

PubMed

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

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

2014-06-28

286

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

SciTech Connect

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.

Dutta, Saikat; Wu, Kevin C.-W., E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Kao, Hsien-Ming, E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw [Department of Chemistry, National Central University, Chung-Li 32054, Taiwan (China)

2014-11-01

287

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

288

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

PubMed

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

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

2011-10-15

289

On the detection of functionally coherent groups of protein domains with an extension to protein annotation  

Microsoft Academic Search

BACKGROUND: Protein domains coordinate to perform multifaceted cellular functions, and domain combinations serve as the functional building blocks of the cell. The available methods to identify functional domain combinations are limited in their scope, e.g. to the identification of combinations falling within individual proteins or within specific regions in a translated genome. Further effort is needed to identify groups of

William A. Mclaughlin; Ken Chen; Tingjun Hou; Wei Wang

2007-01-01

290

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

PubMed Central

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. PMID:25008009

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

2014-01-01

291

Amine- and carboxyl- quantum dots affect membrane integrity of bacterium Cupriavidus metallidurans CH34.  

PubMed

The present study examines the interaction of amine- and carboxyl- PEG core/shell quantum dots (QDs) with metal resistant bacterium Cupriavidus metallidurans CH34. The evolution of the number of QDs, their hydrodynamic radius, diffusion coefficients, and single particle fluorescence were characterized before and during the contact with bacterium by fluorescence correlation spectroscopy (FCS). The obtained results showed that at nanomolar concentrations the amine- and carboxyl-PEG-QDs with average hydrodynamic radiuses of 16.4 and 13.5 nm, form stable dispersions in the absence and presence of 15 mgC L(-1) HA. The decrease of the number of fluorescent particles in the bacterial medium, determined by FCS, together with the increase of the fluorescence of bacterial cells over the background, found by flow cytometry (FCM), demonstrated the association of QDs to C. metallidurans. Furthermore, QDs enhanced the level of the reactive oxygen species in the bacterial cells and augmented the percentage of the cells with damaged and leaky membranes as probed by FCM in combination with 5-(and-6)-carboxy-27'-dichlorodihydrofluorescein diacetate and propidium iodide stains. No difference in the behavior of amine- and carboxyl-PEG-QDs was found, suggesting that different functional groups in the surface coating have no effect on bacterium-QD interactions under the studied conditions. The presence of HA does not affect the hydrodynamic characteristics of the functionalized QDs, but prevented the damage to the bacterial membrane. The slight decrease in the bacterial growth found after exposure of C. metallidurans to these QDs was attributed to the nanoparticles themselves rather the cadmium, zinc, or selenium ions released from the QDs. PMID:19673316

Slaveykova, Vera I; Startchev, Konstantin; Roberts, Joanna

2009-07-01

292

catena-Poly[[[?-aqua-penta­aqua­dizinc(II)]-?4-benzene-1,2,4,5-tetra­carboxyl­ato] dihydrate  

PubMed Central

The asymmetric unit of the title compound, {[Zn2(C10H2O8)(H2O)6]·2H2O}n, contains two distinct Zn atoms joined by a bridging water molecule and two bridging carboxyl­ate groups belonging to distinct halves of benzene-1,2,4,5-tetra­carboxyl­ate (tbec) tetra­anionic ligands, both lying on crystallographic inversion centres. The structure of this new isopolymorphic one-dimensional coordination polymer features asymmetric bimetallic octa­hedral knots. O—H?O hydrogen bonds between water molecules and carboxylate O atoms help to consolidate the crystal packing. PMID:21583373

Rotondo, Archimede; Bruno, Giuseppe; Nicoló, Francesco; Cento, Angelo

2009-01-01

293

Effects of Functional Group Position on Spatial Representations of Aliphatic Odorants in the Rat Olfactory Bulb  

PubMed Central

Principles of olfactory coding can be clarified by studying the olfactory bulb activity patterns that are evoked by odorants differing systematically in chemical structure. In the present study, we used series of aliphatic esters, ketones, and alcohols (27 odorants total) to determine the effects of functional group position on glomerular-layer activity patterns. These patterns were measured as uptake of [14C]2-deoxyglucose and were mapped into standardized data matrices for statistical comparison across different rats. The magnitude of the effect of position differed greatly for the different functional groups. For ketones, there was little or no effect of position on evoked patterns. For esters, uptake in individual glomerular modules increased, while uptake in others decreased with changing group position, and yet the overall patterns remained similar. For alcohols, group position had a profound effect on evoked activity patterns. For example, moving the hydroxyl group in either heptanol or nonanol from the first to the fourth carbon changed the activity patterns so greatly that the major areas of response did not overlap. Within every functional group series, however, responses were globally chemotopic, such that pairs of odorants with the smallest difference in functional group position evoked the most similar patterns. These results help to define further the specificities of glomeruli within previously described glomerular modules, and they show that functional group position can be an important feature in encoding an odorant molecule. PMID:15678475

Johnson, Brett A.; Farahbod, Haleh; Saber, Sepideh; Leon, Michael

2008-01-01

294

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

NASA Astrophysics Data System (ADS)

Modifying the surface of polycrystalline ZnO films using a monolayer of organic molecules with carboxylic acid attachment groups increases the field-effect electron mobility and zero-bias conductivity, resulting in improved transistors and transparent conductors. The improvement is consistent with the passivation of defects via covalent bonding of the carboxylic acid and is reversible by exposure to a UV-ozone lamp. The properties of the solvent used for the attachment are crucial because solvents with high acid dissociation constants (Ka) for carboxylic acids lead to high proton activities and etching of the nanometers-thick ZnO films, masking the electronic effect.

Spalenka, Josef W.; Gopalan, Padma; Katz, Howard E.; Evans, Paul G.

2013-01-01

295

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

NASA Astrophysics Data System (ADS)

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

Cowan, Mark Timothy

296

Group-ICA Model Order Highlights Patterns of Functional Brain Connectivity  

PubMed Central

Resting-state networks (RSNs) can be reliably and reproducibly detected using independent component analysis (ICA) at both individual subject and group levels. Altering ICA dimensionality (model order) estimation can have a significant impact on the spatial characteristics of the RSNs as well as their parcellation into sub-networks. Recent evidence from several neuroimaging studies suggests that the human brain has a modular hierarchical organization which resembles the hierarchy depicted by different ICA model orders. We hypothesized that functional connectivity between-group differences measured with ICA might be affected by model order selection. We investigated differences in functional connectivity using so-called dual regression as a function of ICA model order in a group of unmedicated seasonal affective disorder (SAD) patients compared to normal healthy controls. The results showed that the detected disease-related differences in functional connectivity alter as a function of ICA model order. The volume of between-group differences altered significantly as a function of ICA model order reaching maximum at model order 70 (which seems to be an optimal point that conveys the largest between-group difference) then stabilized afterwards. Our results show that fine-grained RSNs enable better detection of detailed disease-related functional connectivity changes. However, high model orders show an increased risk of false positives that needs to be overcome. Our findings suggest that multilevel ICA exploration of functional connectivity enables optimization of sensitivity to brain disorders. PMID:21687724

Abou Elseoud, Ahmed; Littow, Harri; Remes, Jukka; Starck, Tuomo; Nikkinen, Juha; Nissilä, Juuso; Timonen, Markku; Tervonen, Osmo; Kiviniemi, Vesa

2011-01-01

297

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

PubMed

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

Gantt, Susan P; Agazarian, Yvonne M

2010-10-01

298

Functional Group Compositions of Carbonaceous Materials of Hayabusa-Returned Samples  

NASA Astrophysics Data System (ADS)

We have analyzed the functional group compositions of the carbonaceous materials of Hayabusa-returned samples by STXM-XANES, in order to identify whether the materials are terrestrial or extraterrestrial.

Yabuta, H.; Uesugi, M.; Naraoka, H.; Ito, M.; Kilcoyne, D.; Sandford, S. A.; Kitajima, F.; Mita, H.; Takano, Y.; Yada, T.; Karouji, Y.; Ishibashi, Y.; Okada, T.; Abe, M.

2014-09-01

299

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

E-print Network

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; ...

Figueroa, Joshua S

2005-01-01

300

The unramified principal series of p-adic groups : the Bessel function  

E-print Network

Let G be a connected reductive group with a split maximal torus defined over a nonarchimedean local field. I evaluate a matrix coefficient of the unramified principal series of G known as the "Bessel function" at torus ...

DeFranco, Mario A. (Mario Anthony)

2014-01-01

301

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

SciTech Connect

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.

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

302

Production of Printed Indexes of Chemical Reactions. I. Analysis of Functional Group Interconversions  

ERIC Educational Resources Information Center

A program is described which identifies functional group interconversion reactions, hydrogenations, and dehydrogenations in a data base containing structures encoded as Wiswesser Line Notations. Production of the data base is briefly described. (17 references) (Authors)

Clinging, R.; Lynch, M. F.

1973-01-01

303

Novel metrics for evaluating the functional coherence of protein groups via protein semantic network  

PubMed Central

We present the metrics for assessing overall functional coherence of a group of proteins based on associated biomedical literature. A probabilistic topic model is applied to extract biologic concepts from a corpus of protein-related biomedical literature. Bipartite protein semantic networks are constructed, so that the functional coherence of a protein group can be evaluated with metrics that measure the closeness and strength of connectivity of the proteins in the network. PMID:17672896

Zheng, Bin; Lu, Xinghua

2007-01-01

304

Anatomic and Functional Variability: The Effects of Filter Size in Group fMRI Data Analysis  

Microsoft Academic Search

In the analysis of group fMRI scans, an optimal spatial filter should be large enough to accurately blend functionally homologous anatomic regions, yet small enough not to blur the functionally distinct regions. Hanning filters varying from 0.0 to 18.0 mm were evaluated in a group analysis of six healthy controls performing a simple finger-tapping paradigm. Test–retest reliability and Talairach-based measurements

Tonya White; Daniel O'Leary; Vincent Magnotta; Stephan Arndt; Michael Flaum; Nancy C. Andreasen

2001-01-01

305

A functional renormalization group approach to zero-dimensional interacting systems  

NASA Astrophysics Data System (ADS)

We apply the functional renormalization group method to the calculation of dynamical properties of zero-dimensional interacting quantum systems. We discuss as case studies the anharmonic oscillator and the single-impurity Anderson model. We truncate the hierarchy of flow equations such that the results are at least correct up to second-order perturbation theory in the coupling. For the anharmonic oscillator, energies and spectra obtained within two different functional renormalization group schemes are compared to numerically exact results, perturbation theory results, and the mean field approximation. Even at large coupling, the results obtained using the functional renormalization group agree quite well with the numerical exact solution. The better of the two schemes is used to calculate spectra of the single-impurity Anderson model, which are then compared to the results from perturbation theory and the numerical renormalization group ones. For small to intermediate couplings the functional renormalization group gives results which are close to the ones obtained using the very accurate numerical renormalization group method. In particular, the low energy scale (Kondo temperature) extracted from the functional renormalization group results shows the expected behaviour.

Hedden, R.; Meden, V.; Pruschke, Th; Schönhammer, K.

2004-07-01

306

Merging photoredox with nickel catalysis: Coupling of ?-carboxyl sp3-carbons with aryl halides  

PubMed Central

Over the past 40 years, transition metal catalysis has enabled bond formation between aryl and olefinic (sp2) carbons in a selective and predictable manner with high functional group tolerance. Couplings involving alkyl (sp3) carbons have proven more challenging. Here, we demonstrate that the synergistic combination of photoredox catalysis and nickel catalysis provides an alternative cross-coupling paradigm, in which simple and readily available organic molecules can be systematically used as coupling partners. By using this photoredox-metal catalysis approach, we have achieved a direct decarboxylative sp3–sp2 cross-coupling of amino acids, as well as ?-O– or phenyl-substituted carboxylic acids, with aryl halides. Moreover, this mode of catalysis can be applied to direct cross-coupling of Csp3–H in dimethylaniline with aryl halides via C–H functionalization. PMID:24903563

Zuo, Zhiwei; Ahneman, Derek T.; Chu, Lingling; Terrett, Jack A.; Doyle, Abigail G.; MacMillan, David W. C.

2015-01-01

307

A Phosphetane Catalyzes Deoxygenative Condensation of ?-Keto Esters and Carboxylic Acids via P(III)/P(V)?O Redox Cycling.  

PubMed

A small-ring phosphacycle is found to catalyze the deoxygenative condensation of ?-keto esters and carboxylic acids. The reaction provides a chemoselective catalytic synthesis of ?-acyloxy ester products with good functional group compatibility. Based on both stoichiometric and catalytic mechanistic experiments, the reaction is proposed to proceed via catalytic P(III)/P(V)?O cycling. The importance of ring strain in the phosphacyclic catalyst is substantiated by an observed temperature-dependent product selectivity effect. The results point to an inherent distinction in design criteria for organophosphorus-based catalysts operating via P(III)/P(V)?O redox cycling as opposed to Lewis base (nucleophilic) catalysis. PMID:25564133

Zhao, Wei; Yan, Patrick K; Radosevich, Alexander T

2015-01-21

308

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

Microsoft Academic Search

This study reports on psychosocial functioning in Swedish adults with Asperger syndrome (AS) or high-functioning autism (HFA). A systematically selected sample of patients and relatives was interviewed concerning their psychosocial situation. The majority was living independently. All persons but one were unemployed. None was married and none had children. Only a few had some kind of partner. Most persons needed

I. Engström; L. Ekström; B. Emilsson

2003-01-01

309

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

ERIC Educational Resources Information Center

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

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

2003-01-01

310

Correlation functions in Couette flow from group theory and molecular dynamics  

Microsoft Academic Search

We describe group theory statistical mechanics, GTSM, which enables us to predict new non-vanishing time correlation functions in fluids at steady state subjected to planar couette flow. These are by symmetry trivially zero at equilibrium. An ensemble average is treated using the rules of group theory in the laboratory XYZ frame and in the molecule-fixed xyz frame of the point

Myron W. Evans; David M. Heyes

1988-01-01

311

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

ERIC Educational Resources Information Center

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).…

Chung-Hall, Janet; Chen, Xinyin

2010-01-01

312

21 CFR 177.1600 - Polyethylene resins, carboxyl modified.  

...Polyethylene resins, carboxyl modified. 177.1600 Section 177...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT...Polyethylene resins, carboxyl modified. Carboxyl-modified polyethylene resins may...

2014-04-01

313

Percolation galaxy groups and clusters in the sdss redshift survey: identification, catalogs, and the multiplicity function  

SciTech Connect

We identify galaxy groups and clusters in volume-limited samples of the SDSS redshift survey, using a redshift-space friends-of-friends algorithm. We optimize the friends-of-friends linking lengths to recover galaxy systems that occupy the same dark matter halos, using a set of mock catalogs created by populating halos of N-body simulations with galaxies. Extensive tests with these mock catalogs show that no combination of perpendicular and line-of-sight linking lengths is able to yield groups and clusters that simultaneously recover the true halo multiplicity function, projected size distribution, and velocity dispersion. We adopt a linking length combination that yields, for galaxy groups with ten or more members: a group multiplicity function that is unbiased with respect to the true halo multiplicity function; an unbiased median relation between the multiplicities of groups and their associated halos; a spurious group fraction of less than {approx}1%; a halo completeness of more than {approx}97%; the correct projected size distribution as a function of multiplicity; and a velocity dispersion distribution that is {approx}20% too low at all multiplicities. These results hold over a range of mock catalogs that use different input recipes of populating halos with galaxies. We apply our group-finding algorithm to the SDSS data and obtain three group and cluster catalogs for three volume-limited samples that cover 3495.1 square degrees on the sky. We correct for incompleteness caused by fiber collisions and survey edges, and obtain measurements of the group multiplicity function, with errors calculated from realistic mock catalogs. These multiplicity function measurements provide a key constraint on the relation between galaxy populations and dark matter halos.

Berlind, Andreas A.; Frieman, Joshua A.; Weinberg, David H.; Blanton, Michael R.; Warren, Michael S.; Abazajian, Kevork; Scranton, Ryan; Hogg, David W.; Scoccimarro,; Bahcall, Neta A.; Brinkmann, J.; Gott, J.Richard, III; Kleinman, S.J.; Krzesinski, J.; Lee, Brian C.; Miller, Christopher J.; Nitta, Atsuko; Schneider, Donald P.; Tucker,; Zehavi, Idit; /CCPP, New York /Chicago U., Astron. Astrophys. Ctr. /Ohio State U., Dept. Astron. /Los Alamos /Pittsburgh U. /Princeton U. /Subaru Telescope /Apache

2006-01-01

314

Synthesis and Catalytic Applications of Sulfonic Acid Group–Functionalized Nano and Microsilica Structures  

Microsoft Academic Search

Sulfonic acid group–functionalized nano- and microsilica with different sizes and shapes were synthesized. Silica nanospheres with an average size of 225 nm, silica microtubes, and fine silica gel were prepared and functionalized by sulfonic acid. Their catalytic activity was investigated in the three-component Biginelli reaction for the synthesis of dihydropyrimidinones.

Laleh Torkian; Peyman Salehi; Minoo Dabiri; Sharmin Kharrazi

2011-01-01

315

Functional specialization and generalization for grouping of stimuli based on colour and motion  

PubMed Central

This study was undertaken to learn whether the principle of functional specialization that is evident at the level of the prestriate visual cortex extends to areas that are involved in grouping visual stimuli according to attribute, and specifically according to colour and motion. Subjects viewed, in an fMRI scanner, visual stimuli composed of moving dots, which could be either coloured or achromatic; in some stimuli the moving coloured dots were randomly distributed or moved in random directions; in others, some of the moving dots were grouped together according to colour or to direction of motion, with the number of groupings varying from 1 to 3. Increased activation was observed in area V4 in response to colour grouping and in V5 in response to motion grouping while both groupings led to activity in separate though contiguous compartments within the intraparietal cortex. The activity in all the above areas was parametrically related to the number of groupings, as was the prominent activity in Crus I of the cerebellum where the activity resulting from the two types of grouping overlapped. This suggests (a) that, the specialized visual areas of the prestriate cortex have functions beyond the processing of visual signals according to attribute, namely that of grouping signals according to colour (V4) or motion (V5); (b) that the functional separation evident in visual cortical areas devoted to motion and colour, respectively, is maintained at the level of parietal cortex, at least as far as grouping according to attribute is concerned; and (c) that, by contrast, this grouping-related functional segregation is not maintained at the level of the cerebellum. PMID:23415950

Zeki, Semir; Stutters, Jonathan

2013-01-01

316

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

PubMed

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

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

2011-01-01

317

Quantum group symmetric Bargmann-Fock space: Integral kernels, Green functions, driving forces  

Microsoft Academic Search

Raising and lowering operators that transform under the SUq(n)-quantum group get deformed commutation relations. They are represented as adjoint operators on a Hilbert space of noncommutative holomorphic functions. Through the algebraically defined integral on this function space, every operator on the Fock space can also be represented as an integral kernel. The Green function for free harmonic oscillators and spin-1\\/2’s

Achim Kempf

1993-01-01

318

Function Net Modeling with UML-RT: Experiences from an Automotive Project at BMW Group  

Microsoft Academic Search

\\u000a This paper presents the function net modeling approach that has been developed within an automotive project at BMW Group aimed at software development for electronic control\\u000a units. This modeling approach provides a graphical, quite abstract representation of a (typically large) set of functions\\u000a to be realized in software or hardware. Function net models are described in UML-RT, a dialect of

Michael Von Der Beeck

2004-01-01

319

Standard partial molar volumes of some aqueous alkanolamines and alkoxyamines at temperatures up to 325 degrees C: functional group additivity in polar organic solutes under hydrothermal conditions.  

PubMed

Apparent molar volumes of dilute aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N,N-dimethylethanolamine (DMEA), ethylethanolamine (EAE), 2-diethylethanolamine (2-DEEA), and 3-methoxypropylamine (3-MPA) and their salts were measured at temperatures from 150 to 325 degrees C and pressures as high as 15 MPa. The results were corrected for the ionization and used to obtain the standard partial molar volumes, Vo2. A three-parameter equation of state was used to describe the temperature and pressure dependence of the standard partial molar volumes. The fitting parameters were successfully divided into functional group contributions at all temperatures to obtain the standard partial molar volume contributions. Including literature results for alcohols, carboxylic acids, and hydroxycarboxylic acids yielded the standard partial molar volume contributions of the functional groups >CH-, >CH2, -CH3, -OH, -COOH, -O-, -->N, >NH, -NH2, -COO-Na+, -NH3+Cl-, >NH2+Cl-, and -->NH+Cl- over the range (150 degrees C groups at temperatures up to approximately 310 degrees C and pressures of 10-20 MPa to within a precision of +/-5 cm3 x mol(-1). The model could not be extended to higher temperatures because of uncertainties caused by thermal decomposition. At temperatures above approximately 250 degrees C, the order of the group contributions to Vo2 changes from that observed at 25 degrees C, to become increasingly consistent with the polarity of each functional group. The effect of the dipole moment of each molecule on the contribution to Vo2 from long-range solvent polarization was calculated from the multipole expansion of the Born equation using dipole moments estimated from restricted Hartree-Fock calculations with Gaussian 03 (Gaussian, Inc., Wallingford, CT) and the Onsager reaction-field approximation for solvent effects. Below 325 degrees C, the dipole contribution was found to be less than 2 cm3 x mol(-1) for all the solute molecules studied. At higher temperatures and pressures near steam saturation, the effect is much larger and may explain anomalies in functional group additivity observed in small, very polar solutes. PMID:18412415

Bulemela, E; Tremaine, Peter R

2008-05-01

320

Arrival order among native plant functional groups does not affect invasibility of constructed dune communities.  

PubMed

Different arrival order scenarios of native functional groups to a site may influence both resource use during development and final community structure. Arrival order may then indirectly influence community resistance to invasion. We present a mesocosm experiment of constructed coastal dune communities that monitored biotic and abiotic responses to different arrival orders of native functional groups. Constructed communities were compared with unplanted mesocosms. We then simulated a single invasion event by bitou (Chrysanthemoides monilifera ssp. rotundata), a dominant exotic shrub of coastal communities. We evaluated the hypothesis that plantings with simultaneous representation of grass, herb and shrub functional groups at the beginning of the experiment would more completely sequester resources and limit invasion than staggered plantings. Staggered plantings in turn would offer greater resource use and invasion resistance than unplanted mesocosms. Contrary to our expectations, there were few effects of arrival order on abiotic variables for the duration of the experiment and arrival order was unimportant in final community invasibility. All planted mesocosms supported significantly more invader germinants and significantly less invader abundance than unplanted mesocosms. Native functional group plantings may have a nurse effect during the invader germination and establishment phase and a competitive function during the invader juvenile and adult phase. Arrival order per se did not affect resource use and community invasibility in our mesocosm experiment. While grass, herb and shrub functional group plantings will not prevent invasion success in restored communities, they may limit final invader biomass. PMID:23468238

Mason, T J; French, K; Jolley, D

2013-10-01

321

Synthesis, spectroscopy and computational studies of selected hydroxyquinoline carboxylic acids and their selected fluoro-, thio-, and dithioanalogues  

NASA Astrophysics Data System (ADS)

The faster and more efficient new synthetic methodologies of crystalline hydroxyquinoline carboxylic acids and their fluoro-, thio- and dithioanalogues were elaborated. The FTIR, multinuclear NMR, UV-Vis and single crystal X-ray characteristics of the series of quinoline carboxylic acids have been determined experimentally and rationalized on the basis of DFT calculation method with B3LYP functional.

Nycz, Jacek E.; Malecki, Grzegorz J.

2013-01-01

322

Tensor renormalization group: Local magnetizations, correlation functions, and phase diagrams of systems with quenched randomness  

NASA Astrophysics Data System (ADS)

The tensor renormalization-group method, developed by Levin and Nave, brings systematic improvability to the position-space renormalization-group method and yields essentially exact results for phase diagrams and entire thermodynamic functions. The method, previously used on systems with no quenched randomness, is extended in this study to systems with quenched randomness. Local magnetizations and correlation functions as a function of spin separation are calculated as tensor products subject to renormalization-group transformation. Phase diagrams are extracted from the long-distance behavior of the correlation functions. The approach is illustrated with the quenched bond-diluted Ising model on the triangular lattice. An accurate phase diagram is obtained in temperature and bond-dilution probability for the entire temperature range down to the percolation threshold at zero temperature.

Güven, Can; Hinczewski, Michael; Berker, A. Nihat

2010-11-01

323

Tensor renormalization group: Local magnetizations, correlation functions, and phase diagrams of systems with quenched randomness  

NASA Astrophysics Data System (ADS)

The tensor renormalization-group method, developed by Levin and Nave, brings systematic improvability to the position-space renormalization-group method and yields essentially exact results for phase diagrams and entire thermodynamic functions. The method, previously used on systems with no quenched randomness, is extended in this study to systems with quenched randomness [1]. Local magnetizations and correlation functions as a function of spin separation are calculated as tensor products subject to renormalization-group transformation. Phase diagrams are extracted from the long-distance behavior of the correlation functions. The approach is illustrated with the quenched bond-diluted Ising model on the triangular lattice. An accurate phase diagram is obtained in temperature and bond-dilution probability for the entire temperature range down to the percolation threshold at zero temperature.[4pt] [1] C. G"uven, M. Hinczewski, and A.N. Berker, Phys. Rev. E 82, 051110 (2010).

Güven, Can; Hinczewski, Michael; Berker, A. Nihat

2011-03-01

324

Poly[(?3-5-tert-butyl­benzene-1,3-di­carboxyl­ato)di­pyridine­cobalt(II)  

PubMed Central

In the title compound, [Co(C12H12O4)(C5H5N)2]n, the CoII cation is coordinated by four O atoms from three 5-tert-butyl­benzene-1,3-di­carboxyl­ate anions and two N atoms from pyridine mol­ecules in a distorted octa­hedral geometry. One carboxyl­ate group of the anionic ligand chelates a CoII cation while another carboxyl­ate group bridges two CoII cations, resulting in a polymeric layer parallel to (101). Weak C—H?O hydrogen bonds occur between adjacent polymeric layers. In the crystal, one of pyridine mol­ecules is equally disordered over two positions. PMID:24526931

Noh, Kyungkyou; Kim, Jaheon

2013-01-01

325

Size dependent aqueous dispersibility of carboxylated multiwall carbon nanotubes  

PubMed Central

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

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

2013-01-01

326

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids  

PubMed Central

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

Matthessen, Roman; Fransaer, Jan; Binnemans, Koen

2014-01-01

327

Substrate Specificity within a Family of Outer Membrane Carboxylate Channels  

PubMed Central

Many Gram-negative bacteria, including human pathogens such as Pseudomonas aeruginosa, do not have large-channel porins. This results in an outer membrane (OM) that is highly impermeable to small polar molecules, making the bacteria intrinsically resistant towards many antibiotics. In such microorganisms, the majority of small molecules are taken up by members of the OprD outer membrane protein family. Here we show that OprD channels require a carboxyl group in the substrate for efficient transport, and based on this we have renamed the family Occ, for outer membrane carboxylate channels. We further show that Occ channels can be divided into two subfamilies, based on their very different substrate specificities. Our results rationalize how certain bacteria can efficiently take up a variety of substrates under nutrient-poor conditions without compromising membrane permeability. In addition, they explain how channel inactivation in response to antibiotics can cause resistance but does not lead to decreased fitness. PMID:22272184

Eren, Elif; Vijayaraghavan, Jagamya; Liu, Jiaming; Cheneke, Belete R.; Touw, Debra S.; Lepore, Bryan W.; Indic, Mridhu; Movileanu, Liviu; van den Berg, Bert

2012-01-01

328

Driving factors of the phytoplankton functional groups in a deep Mediterranean reservoir.  

PubMed

The control of phytoplankton growth is mainly related to the availability of light and nutrients. Both may select phytoplankton species, but only if they occur in limiting amounts. During the last decade, the functional groups approach, based on the physiological, morphological and ecological attributes of the species, has proved to be a more efficient way to analyze seasonal changes in phytoplankton biomass. We analysed the dynamics of the phytoplankton functional groups sensu Reynolds, recognising the driving forces (light, mixing regime, and nutrients) in the Sau Reservoir, based on a one-year cycle (monthly surface-water sampling). The Sau Reservoir is a Mediterranean water-supply reservoir with a canyon-shaped basin and a clear and mixed epilimnion layer. The long stratification period and high light availability led to high phytoplankton biomass (110.8 fresh-weight mg L(-1)) in the epilimnion during summer. The reservoir showed P-limitation for phytoplankton growth in this period. All functional groups included one or more species (X2-Rhodomonas spp.; Y-Cryptomonas spp.; F-Oocystis lacustris; K-Aphanocapsa spp.) selected by resources, especially phosphorus. Species of Cryptomonas (group Y) dominated during the mixing period (winter season) in conditions of low light and relatively high availability of dissolved nutrients. Increases in water-column stability during spring stratification led to phytoplankton biomass increases due to the dominance of small flagellate functional groups (X2 and X3, chrysophyceans). The colonial chlorophycean O. lacustris (group F) peaked during the mid-summer stratification, when the mixed epilimnion was clearly depleted in nutrients, especially SRP. High temperature and increases in nutrient concentration during the end-summer and mid-autumn resulted in a decrease of green algae (group F) and increase of Aphanocapsa spp. (cyanobacteria, group K) and dinoflagellates (group L(o)). The study also revealed the important role of physical processes in the seasonal gradient, in selecting phytoplankton functional groups, and consequently in the assessment of ecological status. The Q index (assemblage index) based on functional groups indicated the overall good ecological status of the Sau Reservoir, which varied as a function of the mixing regime. This is the first application of the Assemblage Index to a European water-supply reservoir. PMID:20398914

Becker, Vanessa; Caputo, Luciano; Ordóñez, Jaime; Marcé, Rafael; Armengol, Joan; Crossetti, Luciane O; Huszar, Vera L M

2010-06-01

329

Carboxylation of phenylphosphate by phenol carboxylase, an enzyme system of anaerobic phenol metabolism.  

PubMed Central

Several lines of evidence indicate that the first step in the anaerobic metabolism of phenol is phenol carboxylation to 4-hydroxybenzoate; this reaction is considered a biological Kolbe-Schmitt carboxylation. A phenol carboxylase system was characterized by using a denitrifying Pseudomonas strain, K 172, which catalyzes an isotope exchange between 14CO2 and the carboxyl group of 4-hydroxybenzoate. The enzymatic isotope exchange activity (100 nmol min-1 mg-1 of protein) requires Mn2+ and K+. We show that this system also catalyzes the carboxylation of phenylphosphate (the phosphoric acid monophenyl ester) to 4-hydroxybenzoate and phosphate. The specific activity of phenylphosphate carboxylation at the optimal pH of 6.5 is 12 nmol of CO2 fixed min-1 mg-1 of protein. Phenylphosphate cannot be replaced by Mg(2+)-ATP and phenol. The carboxylase activity requires Mn2+ but, in contrast to the isotope exchange activity, does not require K+. The apparent Km values are 1.5 mM dissolved CO2 and 0.2 mM phenylphosphate. Several convenient assays for phenylophosphate carboxylation are described. The isotope exchange reaction and the net carboxylation reaction are catalyzed by the same oxygen-sensitive enzyme, which has a half-life in an air-saturated solution of less than 1 min. Both activities cochromatographed with a protein with a Mr of 280,000, and both activities were induced only after anaerobic growth on phenol. The carboxylation of phenylphosphate suggests that phenylphosphate itself is the physiological CO2 acceptor molecular of this novel CO2 fixation reaction. Alternatively, phenylphosphate could simulate the unknown natural precursor. It is suggested that the formation of an enzyme-bound phenolate anion from the activated phenolic compound is the rate-determining step in the carboxylation reaction. PMID:1592817

Lack, A; Fuchs, G

1992-01-01

330

Mechanism of SmI2/Amine/H2O-Promoted Chemoselective Reductions of Carboxylic Acid Derivatives (Esters, Acids, and Amides) to Alcohols.  

PubMed

Samarium(II) iodide-water-amine reagents have emerged as some of the most powerful reagents (E° = -2.8 V) for the reduction of unactivated carboxylic acid derivatives to primary alcohols under single electron transfer conditions, a transformation that had been considered to lie outside the scope of the classic SmI2 reductant for more than 30 years. In this article, we present a detailed mechanistic investigation of the reduction of unactivated esters, carboxylic acids, and amides using SmI2-water-amine reagents, in which we compare the reactivity of three functional groups. The mechanism has been studied using the following: (i) kinetic, (ii) reactivity, (iii) radical clock, and (iv) isotopic labeling experiments. The kinetic data indicate that for the three functional groups all reaction components (SmI2, amine, water) are involved in the rate equation and that the rate of electron transfer is facilitated by base assisted deprotonation of water. Notably, the mechanistic details presented herein indicate that complexation between SmI2, water, and amines can result in a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to a variety of carboxylic acid derivatives. These observations will have important implications for the design and optimization of new processes involving Sm(II)-reduction of ketyl radicals. PMID:25232891

Szostak, Michal; Spain, Malcolm; Eberhart, Andrew J; Procter, David J

2014-12-19

331

Novel 5-substituted benzyloxy-2-arylbenzofuran-3-carboxylic acids as calcium activated chloride channel inhibitors  

PubMed Central

Transmembrane protein 16A (TMEM16A) channels are recently discovered membrane proteins that functions as a calcium activated chloride channel (CaCC). CaCCs are major regulators of various physiological processes, such as sensory transduction, epithelial secretion, smooth muscle contraction and oocyte fertilization. Thirty novel 5-substituted benzyloxy-2-arylbenzofuran-3-carboxylic acids (B01–B30) were synthesized and evaluated for their TMEM16A inhibitory activity by using short circuit current measurements in Fischer rat thyroid (FRT) cells expressing human TMEM16A. IC50 values were calculated using YFP fluorescence plate reader assay. Final compounds, having free carboxylic group displayed significant inhibition. Eight of the novel compounds B02, B13, B21, B23, B25, B27, B28, B29 exhibit excellent CaCCs inhibition with IC50 value <6 ?M, with compound B25 exhibiting the lowest IC50 value of 2.8 ± 1.3 ?M. None of the tested ester analogs of final benzofuran derivatives displayed TMEM16A/CaCCs inhibition. PMID:22739085

Kumar, Satish; Namkung, Wan; Verkman, A. S.; Sharma, Pawan K.

2013-01-01

332

Density functional theory calculations on azobenzene derivatives: a comparative study of functional group effect.  

PubMed

Density functional theory (DFT) calculations have been used to investigate the structural properties, dipole moments, polarizabilities, Gibbs energies, hardness, electronegativity, HOMO/LUMO energies, and chemical potentials of trans and cis configurations of eight para-substituted azobenzene derivatives. All properties have been obtained using the B3LYP functional and 6-31++G(d,p) basis set. The planar structures have been obtained for all optimized trans configurations. The energy difference between trans and cis configurations for considered derivatives was found to be between 64.2-73.1 kJ/mole. It has been obtained that the p-aminodiazo-benzene (ADAB) has the difference in the dipole moments between trans and cis forms higher than for trans and cis azobenzene. PMID:25644369

Piyanzina, Irina; Minisini, Benoit; Tayurskii, Dmitrii; Bardeau, Jean-François

2015-02-01

333

The luminosity function of galaxy systems - From single galaxies and small groups to rich clusters  

NASA Technical Reports Server (NTRS)

The luminosity function (LF) of galaxy systems is determined, from single galaxies and small groups to rich clusters. The LF of rich (Abell) clusters is found to be a steeply decreasing function of cluster number density with cluster luminosity, and the groupings LF (that is, groups to rich clusters) can be well represented by a Schechter-type (1976) analytic form. The general LF of all galaxy systems is also found to be a smooth and steeply decreasing function of number density with luminosity, exhibiting an exponential cutoff in the rich-cluster luminosity domain, a power law dependence over most of the intermediate luminosity range, and a flattening of slope below the characteristic galactic luminosity. Comparisons of the LF with the LF of galaxies and X-ray clusters of galaxies are also discussed.

Bahcall, N. A.

1979-01-01

334

THE MASS FUNCTION OF VOID GROUPS AS A PROBE OF PRIMORDIAL NON-GAUSSIANITY  

SciTech Connect

The primordial non-Gaussianity signal, if measured accurately, will allow us to distinguish between different candidate models for cosmic inflation. Since the galaxy groups located in void regions are rare events, their abundance may be a sensitive probe of primordial non-Gaussianity. We construct an analytic model for the mass function of void groups in the framework of the extended Press-Schechter theory with non-Gaussian initial conditions and investigate how it depends on the primordial non-Gaussianity parameter. A feasibility study is conducted by fitting the analytic mass function of void groups to the observational results from the galaxy group catalog of the Sloan Digital Sky Survey Data Release 4 by adjusting the primordial non-Gaussianity parameter.

Song, Hyunmi; Lee, Jounghun [Department of Physics and Astronomy, FPRD, Seoul National University, Seoul 151-747 (Korea, Republic of)], E-mail: yesuane@gmail.com, E-mail: jounghun@astro.snu.ac.kr

2009-08-10

335

Functional grouping and cortical–subcortical interactions in emotion: A meta-analysis of neuroimaging studies  

PubMed Central

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

Kober, Hedy; Barrett, Lisa Feldman; Joseph, Josh; Bliss-Moreau, Eliza; Lindquist, Kristen; Wager, Tor D.

2009-01-01

336

Modulating optical properties of graphene oxide: role of prominent functional groups.  

PubMed

To modulate the electronic and optical properties of graphene oxide via controlled deoxidation, a proper understanding of the role of the individual functional group in determining these properties is required. We, therefore, have performed ab initio density functional theory based calculations to study the electronic and optical properties of model structures of graphene oxide with different coverages and compositions. In particular, we considered various concentrations of major functional groups like epoxides, hydroxyls, and carbonyls, which mainly consititute the graphene oxide and the reduced graphene oxide. Our calculated electron energy loss spectra (EELS) demonstrate the ? plasmon peak to be less sensitive, while ? + ? plasmon is found to have a significant blue shift of about 1.0-3.0 eV, when the concentration of epoxy and hydroxyl functional groups in graphene oxide vary from 25% to 75%. However, the increase in carbonyl groups in the center of the graphene sheet creates holes, which lead to the red shift of the EELS. In the case of 37.5% of oxygen-to-carbon ratio, we find the ? plasmon peak to be shifted by roughly 1.0 eV as compared to that of the pristine graphene. Our results agree well with the experimental findings which suggest a blue shift in the EELS of graphene oxide and an absorption feature due to a ? electron transition of the carbonyl groups at a lower energy than that of epoxy and hydroxyl groups. We also show that the increase in the width of the hole created by the carbonyl groups significantly decreases the optical gap and opens the band gap, and thus, we argue that reduced graphene oxide with mostly carbonyl groups could be a useful material for developing tunable opto-electronic nanodevices. PMID:21875075

Johari, Priya; Shenoy, Vivek B

2011-09-27

337

Peripherally and axially carboxylic acid substituted subphthalocyanines for dye-sensitized solar cells.  

PubMed

A series of subphthalocyanines (SubPcs) bearing a carboxylic acid group either at the peripheral or axial position have been designed and synthesized to investigate the influence of the COOH group positions on the dye-sensitized solar cell (DSSC) performance. The DSSC devices based on SubPcs with axially substituted carboxylic acid groups showed low photovoltaic performance, whereas peripherally substituted one exhibited higher power conversion efficiency owing to improved injection from LUMO of SubPcs to the TiO2 conduction band. PMID:24443172

Ince, Mine; Medina, Anaïs; Yum, Jun-Ho; Yella, Aswani; Claessens, Christian G; Martínez-Díaz, M Victoria; Grätzel, Michael; Nazeeruddin, Mohammad K; Torres, Tomás

2014-02-10

338

Cellular distribution and cytotoxicity of graphene quantum dots with different functional groups  

NASA Astrophysics Data System (ADS)

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.

Yuan, Xiaochan; Liu, Zhiming; Guo, Zhouyi; Ji, Yanhong; Jin, Mei; Wang, Xinpeng

2014-03-01

339

Cellular distribution and cytotoxicity of graphene quantum dots with different functional groups  

PubMed Central

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

2014-01-01

340

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

E-print Network

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.

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

2012-09-25

341

Carboxylic acid accelerated formation of diesters  

DOEpatents

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.

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

1998-04-28

342

rac-3-exo-Ammonio-7-anti-carb-oxy-tricyclo-[2.2.1.0.(2,6)]heptane-3-endo-carboxyl-ate monohydrate.  

PubMed

The racemic title compound, C(9)H(11)NO(4)·H(2)O, a tricyclic rearranged amino-norbornane dicarb-oxy-lic acid, is a conformationally rigid analogue of glutamic acid and exists as an ammonium-carboxyl-ate zwitterion, with the bridghead carb-oxy-lic acid group anti-related. In the crystal, N-H?O and O-H?O hydrogen bonds involving the ammonium, carb-oxy-lic acid and water donor groups with both water and carboxyl O-atom acceptors give a three-dimensional framework structure. PMID:22590342

Smith, Graham; Wermuth, Urs D; Jenkins, Ian D

2012-05-01

343

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

NASA Astrophysics Data System (ADS)

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.

Neretin, Yu A.

2014-09-01

344

Particle swarm optimization with age-group topology for multimodal functions and data clustering  

NASA Astrophysics Data System (ADS)

This paper proposes particle swarm optimization with age-group topology (PSOAG), a novel age-based particle swarm optimization (PSO). In this work, we present a new concept of age to measure the search ability of each particle in local area. To keep population diversity during searching, we separate particles to different age-groups by their age and particles in each age-group can only select the ones in younger groups or their own groups as their neighbourhoods. To allow search escape from local optima, the aging particles are regularly replaced by new and randomly generated ones. In addition, we design an age-group based parameter setting method, where particles in different age-groups have different parameters, to accelerate convergence. This algorithm is applied to nonlinear function optimization and data clustering problems for performance evaluation. In comparison against several PSO variants and other EAs, we find that the proposed algorithm provides significantly better performances on both the function optimization problems and the data clustering tasks.

Jiang, Bo; Wang, Ning; Wang, Liping

2013-11-01

345

[Structural identification of carboxylic esters by pyrolysis gas chromatography].  

PubMed

A pyrolysis gas chromatographic method has been investigated for structural identification of carboxylic esters. The method can be applied to identify not only pure components, but also those separated by thin layer chromatography and scraped from the TLC plate without removing the adsorbent. The samples were pyrolyzed in tube furnace pyrolyzer at 500 degrees C (conventional pyrolysis) or were pyrolyzed at 550 degrees C after mixing with soda-lime powder (pyrolysis with soda-lime). Some esters such as iso-octyl palmitate, glycerol monostearate and diethyl phthalate were pyrolyzed. The pyrolysis products were identified by comparing with the known. The parent alcohols of monohydric and polyhydric alcohol esters can be determined respectively according to alcohols, alkenes produced on pyrolysis and dehydrated products of polyhydric alcohol at high temperature. The parent acids of monocarboxylic esters can be determined according to carboxylic acid produced on conventional pyrolysis or corresponding alkane formed from decarboxylation of parent acids on pyrolysis with soda-lime. For esters formed from dicarboxylic acids that can be dehydrated to produce five-, six-membered cyclic ketones or can be dehydrated and decarboxylated simultaneously to produce five-, six-membered cyclic acid anhydrides, parent acids can be determined according to corresponding cyclic ketones or cyclic acid anhydrides. This method is useful for identification of common carboxylic esters. When the compound or the component of the mixture was confirmed to contain ester-group by infra-red spectroscopy, PGC or TLC-PGC can be employed to make further identification. PMID:15739430

Liu, E; Chen, W

1997-01-01

346

Synthesis, characterization, single crystal X-ray structure determination and packing analysis of thallium(I) anthracene-9-carboxylate, [Tl4(H2O)2(anthracene-9-carboxylate)4  

NASA Astrophysics Data System (ADS)

A new tetranuclear thallium complex, [Tl4(H2O)2(anthracene-9-carboxylate)4] was isolated by reaction of hot aqueous solution of thallium(1)sulphate with sodium salt of anthracene-9-carboxylic acid in water taken in appropriate stoichiometric ratio. The newly synthesized complex was characterized by elemental analysis, thermogravimetric analysis, spectroscopic studies (FT-IR, UV-Visible, and multinuclear NMR). Complex crystallizes in monoclinic crystal system with P21/n space group. X-ray crystal structure determination revealed the presence of neutral centrosymmetric tetranuclear complex which contains two symmetry independent thallium cations. Tl1 is four-coordinate and bonded to three different anthracene-9-carboxylate anions. The other thallium cation, Tl2, is three-coordinate, being surrounded by two carboxylate oxygen atoms from two different ligands; anthracene-9-carboxylate and a water molecule. The crystal lattice is stabilized by Csbnd H/Osbnd H⋯O hydrogen bonding and cation⋯? interactions.

Kumar, Santosh; Sharma, Raj Pal; Saini, Anju; Venugopalan, Paloth; Starynowicz, Przemys?aw

2015-01-01

347

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

PubMed Central

Background Although patients with Treatment Resistant Depression (TRD) often have impaired social functioning, few studies have investigated the effectiveness of psychosocial treatment for these patients. We examined whether adding group cognitive behavioral therapy (group-CBT) to medication would improve both the depressive symptoms and the social functioning of patient with mild TRD, and whether any improvements would be maintained over one year. Methods Forty-three patients with TRD were treated with 12 weekly sessions of group-CBT. Patients were assessed with the Global Assessment of Functioning scale (GAF), the 36-item Short-Form Health Survey (SF-36), the Hamilton Rating Scale for Depression (HRSD), the Dysfunctional Attitudes Scale (DAS), and the Automatic Thought Questionnaire-Revised (ATQ-R) at baseline, at the termination of treatment, and at the 12-month follow-up. Results Thirty-eight patients completed treatment; five dropped out. For the patients who completed treatment, post-treatment scores on the GAF and SF-36 were significantly higher than baseline scores. Scores on the HRSD, DAS, and ATQ-R were significantly lower after the treatment. Thus patients improved on all measurements of psychosocial functioning and mood symptoms. Twenty patients participated in the 12-month follow-up. Their improvements for psychosocial functioning, depressive symptoms, and dysfunctional cognitions were sustained at 12 months following the completion of group-CBT. Conclusions These findings suggest a positive effect that the addition of cognitive behavioural group therapy to medication on depressive symptoms and social functioning of mildly depressed patients, showing treatment resistance. PMID:20230649

2010-01-01

348

Theoretical and experimental studies on the carbon-nanotube surface oxidation by nitric acid: interplay between functionalization and vacancy enlargement.  

PubMed

The nitric acid oxidation of multiwalled carbon nanotubes leading to surface carboxylic groups has been investigated both experimentally and theoretically. The experimental results show that such a reaction involves the initial rapid formation of carbonyl groups, which are then transformed into phenol or carboxylic groups. At room temperature, this reaction takes place on the most reactive carbon atoms. At higher temperatures a different mechanism would operate, as evidenced by the difference in activation energies. Experimental data can be partially related to first-principles calculations, showing a multistep functionalization mechanism. The theoretical aspects of the present article have led us to propose the most efficient pathway leading to carboxylic acid functional groups on the surface. Starting from mono-vacancies, it ends up with the synergistic formation of dangling -COOH groups and the enlargement of the vacancies. PMID:21922575

Gerber, Iann; Oubenali, Mustapha; Bacsa, Revathi; Durand, Jérôme; Gonçalves, Alexandra; Pereira, M Fernando R; Jolibois, Franck; Perrin, Lionel; Poteau, Romuald; Serp, Philippe

2011-10-01

349

Momentum subtraction scheme renormalization group functions in the maximal Abelian gauge  

NASA Astrophysics Data System (ADS)

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

Bell, J. M.; Gracey, J. A.

2013-10-01

350

Organic functional group transformations in water at elevated temperature and pressure: Reversibility, reactivity, and mechanisms  

NASA Astrophysics Data System (ADS)

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.

Shipp, Jessie; Gould, Ian R.; Herckes, Pierre; Shock, Everett L.; Williams, Lynda B.; Hartnett, Hilairy E.

2013-03-01

351

Identifying functional groups for response to disturbance in an abandoned pasture  

Microsoft Academic Search

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

Sandra Lavorel; Blaise Touzard; Jean-Dominique Lebreton; Bernard Clément

1998-01-01

352

Bayesian Estimation of Probabilistic Atlas for Anatomically-Informed Functional MRI Group  

E-print Network

Bayesian Estimation of Probabilistic Atlas for Anatomically-Informed Functional MRI Group Analyses (fMRI) use little anatomical information. The registration of the images to a template is based-based segmentation, multi-modal, T1 MRI and fMRI 1 Introduction Brain atlas is a useful tool in medical image

Paris-Sud XI, Université de

353

Detecting Native Language Group Differences at the Subskills Level of Reading: A Differential Skill Functioning Approach  

ERIC Educational Resources Information Center

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…

Li, Hongli; Suen, Hoi K.

2013-01-01

354

Class-Wide Function-Related Intervention Teams: Effects of Group Contingency Programs in Urban Classrooms  

ERIC Educational Resources Information Center

The purpose of the study was to determine the effectiveness of the Class-Wide Function-related Intervention Teams (CW-FIT) program, a group contingency intervention for whole classes, and for students with disruptive behaviors who are at risk for emotional/behavioral disorders (EBD). The CW-FIT program includes four elements designed from…

Kamps, Debra; Wills, Howard P.; Heitzman-Powell, Linda; Laylin, Jeff; Szoke, Carolyn; Petrillo, Tai; Culey, Amy

2011-01-01

355

A HEIGHT FUNCTION ON THE PICARD GROUP OF SINGULAR ARAKELOV VARIETIES  

E-print Network

its ring of integers and X=OK an arithmetic variety, by which we mean a reduced scheme, projective@geo.math.u­psud.fr For line bundles on possibly singular arithmetic varieties we construct height func­ tions using arithmetic for a height function on the Picard group of a regular arithmetic variety following the philosophy of Bost

Jahnel, Joerg

356

A HEIGHT FUNCTION ON THE PICARD GROUP OF SINGULAR ARAKELOV VARIETIES  

E-print Network

its ring of integers and X/OK an arithmetic variety, by which we mean a reduced scheme, projective@geo.math.u-psud.fr For line bundles on possibly singular arithmetic varieties we construct height func- tions using arithmetic for a height function on the Picard group of a regular arithmetic variety following the philosophy of Bost

Jahnel, Joerg

357

Differential Tendencies To Guess as a Function of Gender and Lingual-Cultural Reference Group.  

ERIC Educational Resources Information Center

The objective of this study was to investigate differential tendencies to avoid guessing as a function of three variables: (1) lingual-cultural-group; (2) gender; and (3) examination year. The Psychometric Entrance Test (PET) for universities in Israel was used, which is administered in Hebrew, Arabic, English, French, Spanish, and Russian. The…

Gafni, Naomi; Estela, Melamed

358

Differential Tendencies to Guess as a Function of Gender and Lingual-Cultural Reference Group.  

ERIC Educational Resources Information Center

Differential tendencies to avoid guessing on the Psychometric Entrance Test (the Israeli college entrance examination) were studied as a function of language group, gender, and examination date for over 10,000 students. Students with different cultural backgrounds and genders differed in their tendencies to guess. Implications for test results are…

Gafni, Naomi; Melamed, Estela

1994-01-01

359

Predicting WAIS-R Scores from the Revised Beta for Low Functioning Minority Group Offenders.  

ERIC Educational Resources Information Center

Investigated the use of the Revised Beta for predicting Wechsler Adult Intelligence Scale-Revised (WAIS-R) scores of low functioning minority group criminal offenders (N=90). Results showed that offenders scored significantly lower on the Beta than on the WAIS-R. (LLL)

Hiltonsmith, Robert W.; And Others

1984-01-01

360

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

E-print Network

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

Schmidt, Steven K.

361

Abstract No. jone0499 FTIR Measurement of Organic Functional Groups in NY/NJ Harbor Sediments  

E-print Network

. Feng (Montclair State U.), S. Xu (BNL), N. Marinkovic (Albert Einstein College of Medicine) and K. W, acetone, hexane, and methyl alcohol to extract the organic compounds and analyzed using Fourier transform of functional groups on a micrometer-size scale and revealed that different extraction treatments remove

Brookhaven National Laboratory

362

Social Resources and Change in Functional Health: Comparing Three Age Groups  

ERIC Educational Resources Information Center

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…

Randall, G. Kevin; Martin, Peter; Bishop, Alex J.; Johnson, Mary Ann; Poon, Leonard W.

2012-01-01

363

Review of Social Skills Training Groups for Youth with Asperger Syndrome and High Functioning Autism  

ERIC Educational Resources Information Center

Although social skills deficits represent core symptoms of Asperger Syndrome and High Functioning Autism, there is limited research investigating the empirical validity of social skills interventions currently being used with these populations. This literature review compares three types of social skills training groups: traditional, cognitive…

Cappadocia, M. Catherine; Weiss, Jonathan A.

2011-01-01

364

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...

365

Redundant and Segregated Functions of Granule-Associated Heparin-Binding Group II Subfamily of Secretory  

E-print Network

Redundant and Segregated Functions of Granule-Associated Heparin-Binding Group II Subfamily of secretory phospholipase A2 (sPLA2) isozymes, and those having heparin affinity markedly enhance the exocytotic response. Rat mastocytoma RBL-2H3 cells transfected with heparin-binding (sPLA2-IIA, -V, and -IID

Gelb, Michael

366

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...

367

Sleep Characteristics of Youth with Functional Abdominal Pain and a Healthy Comparison Group  

Microsoft Academic Search

Objective To describe sleep problems among youth with and without functional abdominal pain (FAP). Methods Participants were 8-15 years of age diagnosed with FAP (n ¼67) or healthy pain-free comparisons (n ¼80). Parents and participants completed instruments assessing sleep, psychiatric status, and FAP symptoms. Parent and child reports of sleep problems were compared across groups and the association of FAP

Edward D. Huntley; John V. Campo; Ronald E. Dahl; Daniel S. Lewin

2007-01-01

368

Cosmological constraints from the virial mass function of nearby galaxy groups and clusters  

E-print Network

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 ...

Hill, James Colin

2008-01-01

369

Department and function: Group leader (Institute of Medical Microbiology and Hospital  

E-print Network

Department and function: Group leader (Institute of Medical Microbiology and Hospital Epidem.) Education: 1996 PhD in Biology (Microbiology/Biochemistry/Cell Biology), Ruhr-University Bochum, Germany 2003 Habilitation in Medical Microbiology, University of Würzburg, Germany Positions: 1998-1999: Junior

Manstein, Dietmar J.

370

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

Microsoft Academic Search

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)

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

2007-01-01

371

Functional group analysis in coal by sup 31 P NMR spectroscopy  

SciTech Connect

The purpose of this research is to determine the labile-hydrogen functional group composition of coal and coal-derived materials by the nmr spectroscopy of their derivatives made with reagents containing the nmr-active nuclei {sup 31}P, {sup 119}Sn, or {sup 205}Tl. 7 refs.

Verkade, J.G.

1989-05-01

372

Kernels and designs for modelling invariant functions: From group invariance to additivity  

E-print Network

in the last decades for designing and analysing costly de- terministic experiments [9, 7]. In most popular to a discussion on designs of experiments for RF models with invariant kernels, with examples in the additive caseKernels and designs for modelling invariant functions: From group invariance to additivity David

Boyer, Edmond

373

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

ERIC Educational Resources Information Center

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…

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

2006-01-01

374

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

Microsoft Academic Search

Previous studies have shown that fertilization with nitrogen depresses overall microbial biomass and activity in soil. In the present study we broaden our understanding of this phenomenon by studying the seasonality of responses of specific microbial functional groups to chronic nitrogen additions in alpine tundra soils. We measured soil enzyme activities, mineralization kinetics for 8 substrates, biomass of 8 microbial

S. K. Schmidt; D. A. Lipson; R. E. Ley; M. C. Fisk; A. E. West

2004-01-01

375

Behavior of carboxylic acids upon complexation with beryllium compounds.  

PubMed

A significant acidity enhancement and changes on aromaticity were previously observed in squaric acid and its derivatives when beryllium bonds are present in those systems. In order to know if these changes on the chemical properties could be considered a general behavior of carboxylic acids upon complexation with beryllium compounds, complexes between a set of representative carboxylic acids RCOOH (formic acid, acetic acid, propanoic acid, benzoic acid, and oxalic acid) and beryllium compounds BeX2 (X = H, F, Cl) were studied by means of density functional theory calculations. Complexes that contain a dihydrogen bond or a OH···X interaction are the most stable in comparison with other possible BeX2 complexation patterns in which no other weak interactions are involved apart from the beryllium bond. Formic, acetic, propanoic, benzoic, and oxalic acid complexes with BeX2 are much stronger acids than their related free forms. The analysis of the topology of the electron density helps to clarify the reasons behind this acidity enhancement. Importantly, when the halogen atom is replaced by hydrogen in the beryllium compound, the dihydrogen bond complex spontaneously generates a new neutral complex [RCOO:BeH] in which a hydrogen molecule is lost. This seems to be a trend for carboxylic acids on complexing BeX2 compounds. PMID:25010490

Mykolayivna-Lemishko, Kateryna; Montero-Campillo, M Merced; Mó, Otilia; Yáñez, Manuel

2014-07-31

376

Development of Acid Functional Groups and Lactones During the Thermal Degradation of Wood and Wood Components  

USGS Publications Warehouse

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.

Rutherford, David W.; Wershaw, Robert L.; Reeves, James B., III

2008-01-01

377

Vector-valued modular functions for the modular group and the hypergeometric equation  

E-print Network

A general theory of vector-valued modular functions, holomorphic in the upper half-plane, is presented for finite dimensional representations of the modular group. This also provides a description of vector-valued modular forms of arbitrary half-integer weight. It is shown that the space of these modular functions is spanned, as a module over the polynomials in J, by the columns of a matrix that satisfies an abstract hypergeometric equation, providing a simple solution of the Riemann-Hilbert problem for representations of the modular group. Restrictions on the coefficients of this differential equation implied by analyticity are discussed, and an inversion formula is presented that allows the determination of an arbitrary vector-valued modular function from its singular behavior. Questions of rationality and positivity of expansion coefficients are addressed. Closed expressions for the number of vector-valued modular forms of half-integer weight are given, and the general theory is illustrated on simple examples.

P. Bantay; T. Gannon

2007-05-17

378

Wetting properties of model interphases coated with defined organic functional groups  

NASA Astrophysics Data System (ADS)

Surface properties of soil particles are of particular interest regarding transport of water and sorption of solutes, especially hazardous xenobiotic species. Wetting properties (e.g. determined by contact angle, CA), governed by the functional groups exposed, are crucial to understand sorption processes in water repellent soils as well as for the geometry of water films sustaining microbial processes on the pore scale. Natural soil particle surfaces are characterized by a wide variety of mineralogical and chemical compounds. Their composition is almost impossible to identify in full. Hence, in order to get a better understanding about surface properties, an option is the usage of defined model surfaces, whereas the created surface should be comparable to natural soil interphases. We exposed smooth glass surfaces to different silane compounds, resulting in a coating covalently bound to the surface and exhibiting defined organic functional groups towards the pore space. The wetting properties as evaluated by CA and the surface free energy (SFE), calculated according to the Acid-Base Theory, were found to be a function of the specific functional group. Specifically, the treated surfaces showed a large variation of CA and SFE as function of chain length and polarity of the organic functional group. The study of wetting properties was accompanied by XPS analysis for selective detection of chemical compounds of the interphase. As the reaction mechanism of the coating process is known, the resulting interphase structure can be modeled based on energetic considerations. A next step is to use same coatings for the defined modification of the pore surfaces of porous media to study transport and sorption processes in complex three phase systems.

Woche, Susanne K.; Goebel, Marc-O.; Guggenberger, Georg; Tunega, Daniel; Bachmann, Joerg

2013-04-01

379

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

380

Zooplankton functional groups on the continental shelf of the yellow sea  

NASA Astrophysics Data System (ADS)

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.

Sun, Song; Huo, Yuanzi; Yang, Bo

2010-06-01

381

Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups  

SciTech Connect

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.

Fifield, Leonard S.; Grate, Jay W.

2010-06-01

382

Matrix Intensification Alters Avian Functional Group Composition in Adjacent Rainforest Fragments  

PubMed Central

Conversion of farmland land-use matrices to surface mining is an increasing threat to the habitat quality of forest remnants and their constituent biota, with consequences for ecosystem functionality. We evaluated the effects of matrix type on bird community composition and the abundance and evenness within avian functional groups in south-west Ghana. We hypothesized that surface mining near remnants may result in a shift in functional composition of avifaunal communities, potentially disrupting ecological processes within tropical forest ecosystems. Matrix intensification and proximity to the remnant edge strongly influenced the abundance of members of several functional guilds. Obligate frugivores, strict terrestrial insectivores, lower and upper strata birds, and insect gleaners were most negatively affected by adjacent mining matrices, suggesting certain ecosystem processes such as seed dispersal may be disrupted by landscape change in this region. Evenness of these functional guilds was also lower in remnants adjacent to surface mining, regardless of the distance from remnant edge, with the exception of strict terrestrial insectivores. These shifts suggest matrix intensification can influence avian functional group composition and related ecosystem-level processes in adjacent forest remnants. The management of matrix habitat quality near and within mine concessions is important for improving efforts to preserveavian biodiversity in landscapes undergoing intensification such as through increased surface mining. PMID:24058634

Deikumah, Justus P.; McAlpine, Clive A.; Maron, Martine

2013-01-01

383

Adsorption of volatile sulphur compounds onto modified activated carbons: effect of oxygen functional groups.  

PubMed

The effect of physical and chemical properties of activated carbon (AC) on the adsorption of ethyl mercaptan, dimethyl sulphide and dimethyl disulphide was investigated by treating a commercial AC with nitric acid and ozone. The chemical properties of ACs were characterised by temperature programme desorption and X-ray photoelectron spectroscopy. AC treated with nitric acid presented a larger amount of oxygen functional groups than materials oxidised with ozone. This enrichment allowed a significant improvement on adsorption capacities for ethyl mercaptan and dimethyl sulphide but not for dimethyl disulphide. In order to gain a deeper knowledge on the effect of the surface chemistry of AC on the adsorption of volatile sulphur compounds, the quantum-chemical COSMO-RS method was used to simulate the interactions between AC surface groups and the studied volatile sulphur compounds. In agreement with experimental data, this model predicted a greater affinity of dimethyl disulphide towards AC, unaffected by the incorporation of oxygen functional groups in the surface. Moreover, the model pointed out to an increase of the adsorption capacity of AC by the incorporation of hydroxyl functional groups in the case of ethyl mercaptan and dimethyl sulphide due to the hydrogen bond interactions. PMID:23708449

Vega, Esther; Lemus, Jesús; Anfruns, Alba; Gonzalez-Olmos, Rafael; Palomar, José; Martin, María J

2013-08-15

384

Motion of Carboxyl Terminus of G? Is Restricted upon G Protein Activation  

PubMed Central

The carboxyl terminus of the G protein ? subunit plays a key role in interactions with G protein-coupled receptors. Previous studies that have incorporated covalently attached probes have demonstrated that the carboxyl terminus undergoes conformational changes upon G protein activation. To examine the conformational changes that occur at the carboxyl terminus of G? subunits upon G protein activation in a more native system, we generated a semisynthetic G? subunit, site-specifically labeled in its carboxyl terminus with 13C amino acids. Using expressed protein ligation, 9-mer peptides were ligated to recombinant G?i1 subunits lacking the corresponding carboxyl-terminal residues. In a receptor-G protein reconstitution assay, the truncated G?i1 subunit could not be activated by receptor; whereas the semisynthetic protein demonstrated functionality that was comparable with recombinant G?i1. To study the conformation of the carboxyl terminus of the semisynthetic G protein, we applied high resolution solution NMR to G? subunits containing 13C labels at the corresponding sites in G?i1: Leu-348 (uniform), Gly-352 (? carbon), and Phe-354 (ring). In the GDP-bound state, the spectra of the ligated carboxyl terminus appeared similar to the spectra obtained for 13C-labeled free peptide. Upon titration with increasing concentrations of AlF4?, the 13C resonances demonstrated a marked loss of signal intensity in the semisynthetic G? subunit but not in free peptide subjected to the same conditions. Because AlF4? complexes with GDP to stabilize an activated state of the G? subunit, these results suggest that the G? carboxyl terminus is highly mobile in its GDP-bound state but adopts an ordered conformation upon activation by AlF4?. PMID:15983037

Anderson, Lori L.; Marshall, Garland R.; Crocker, Evan; Smith, Steven O.; Baranski, Thomas J.

2005-01-01

385

Configuration-dependent electronic and magnetic properties of graphene monolayers and nanoribbons functionalized with aryl groups  

SciTech Connect

Graphene monolayers functionalized with aryl groups exhibit configuration-dependent electronic and magnetic properties. The aryl groups were adsorbed in pairs of neighboring atoms in the same sublattice A (different sublattices) of graphene monolayers, denoted as the M{sub 2}{sup AA} (M{sub 2}{sup AB}) configuration. The M{sub 2}{sup AA} configuration behaved as a ferromagnetic semiconductor. The band gaps for the majority and minority bands were 1.1 eV and 1.2 eV, respectively. The M{sub 2}{sup AB} configuration behaved as a nonmagnetic semiconductor with a band gap of 0.8 eV. Each aryl group could induce 1 Bohr magneton (?{sub B}) into the molecule-graphene system. Armchair graphene nanoribbons (GNRs) exhibited the same configuration-dependent magnetic properties as the graphene monolayers. The net spin of the functionalized zigzag GNRs was mainly localized on the edges demonstrating an adsorption site-dependent magnetism. For the zigzag GNRs, both the M{sub 2}{sup AA} and M{sub 2}{sup AB} configurations possibly had a magnetic moment. Each aryl group could induce 1.5–3.5 ?{sub B} into the molecule-graphene system. There was a metal-to-insulator transition after adsorption of the aryl groups for the zigzag GNRs.

Tian, Xiaoqing, E-mail: xqtian2008@gmail.com; Gu, Juan [College of Physics and Technology, Shenzhen University, Shenzhen 518060, Guangdong (China)] [College of Physics and Technology, Shenzhen University, Shenzhen 518060, Guangdong (China); Xu, Jian-bin, E-mail: jbxu@ee.cuhk.edu.hk [Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong, Shatin, New Territories (Hong Kong)] [Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong, Shatin, New Territories (Hong Kong)

2014-01-28

386

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

PubMed Central

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

2012-01-01

387

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

PubMed

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

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

2013-08-01

388

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

PubMed Central

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

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

2013-01-01

389

Azidothymidine: crystal structure and possible functional role of the azido group.  

PubMed

The crystal and molecular structures of the anti-acquired immunodeficiency syndrome agent 3'-azido-3'-deoxythymidine (AZT) have been determined by x-ray diffraction. There are two crystallographically independent AZT molecules in the crystal asymmetric unit; they have similar conformations and differ primarily in the glycosyl torsion angle. Comparisons with a hydrated thymidylate structure indicate that the azido group does not significantly affect the gross conformational preference of the molecule. The comparisons also suggest possible functional roles for the azido group in enzyme binding. PMID:2446321

Camerman, A; Mastropaolo, D; Camerman, N

1987-12-01

390

Azidothymidine: crystal structure and possible functional role of the azido group.  

PubMed Central

The crystal and molecular structures of the anti-acquired immunodeficiency syndrome agent 3'-azido-3'-deoxythymidine (AZT) have been determined by x-ray diffraction. There are two crystallographically independent AZT molecules in the crystal asymmetric unit; they have similar conformations and differ primarily in the glycosyl torsion angle. Comparisons with a hydrated thymidylate structure indicate that the azido group does not significantly affect the gross conformational preference of the molecule. The comparisons also suggest possible functional roles for the azido group in enzyme binding. PMID:2446321

Camerman, A; Mastropaolo, D; Camerman, N

1987-01-01

391

High lipophilicity of perfluoroalkyl carboxylate and sulfonate: implications for their membrane permeability.  

PubMed

Here we report on remarkably high lipophilicity of perfluoroalkyl carboxylate and sulfonate. A lipophilic nature of this emerging class of organic pollutants has been hypothesized as an origin of their bioaccumulation and toxicity. Both carboxylate and sulfonate, however, are considered hydrophilic while perfluroalkyl groups are not only hydrophobic but also oleophobic. Partition coefficients of a homologous series of perfluoroalkyl and alkyl carboxylates between water and n-octanol were determined as a measure of their lipophilicity by ion-transfer cyclic voltammetry. Very similar lipophilicity of perfluoroalkyl and alkyl chains with the same length is demonstrated experimentally for the first time by fragment analysis of the partition coefficients. This finding is important for pharmaceutical and biomedical applications of perfluoroalkyl compounds. Interestingly, approximately 2 orders of magnitude higher lipophilicity of a perfluoroalkyl carboxylate or sulfonate in comparison to its alkyl counterpart is ascribed nearly exclusively to their oxoanion groups. The higher lipophilicity originates from a strong electron-withdrawing effect of the perfluoroalkyl group on the adjacent oxoanion group, which is weakly hydrated to decrease its hydrophilicity. In fact, the inductive effect is dramatically reduced for a fluorotelomer with an ethylene spacer between perfluorohexyl and carboxylate groups, which is only as lipophilic as its alkyl counterpart, nonanoate, and is 400 times less lipophilic than perfluorononanoate. The high lipophilicity of perfluoroalkyl carboxylate and sulfonate implies that their permeation across such a thin lipophilic membrane as a bilayer lipid membrane is limited by their transfer at a membrane/water interface. The limiting permeability is lower and less dependent on their lipophilicity than the permeability controlled by their diffusion in the membrane interior as assumed in the classical solubility-diffusion model. PMID:19170492

Jing, Ping; Rodgers, Patrick J; Amemiya, Shigeru

2009-02-18

392

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

E-print Network

for the functions of these proteins. These examples demonstrate the utility of this un- usual amino acid in acid-base chemistry, in expan- sion of function beyond those of the 20 standard amino acids. In this study, the ONIOM field. The barriers for unas- sisted carboxylation of neutral lysine by carbon dioxide or bicarbonate

Schlegel, H. Bernhard

393

Impact of Nanotopography and/or Functional Groups on Periodontal Ligament Cell Growth  

NASA Astrophysics Data System (ADS)

The main purpose of this contribution was to obtain COOH functionalities and/or nanotopographic changes on the surface of 3D, non-woven polyester fabric (NWPF) discs (12.5 mm in diameter) by using low pressure water/O2 plasma assisted treatments. The prepared discs were characterized by various methods after the plasma treatment. Periodontal ligament (PDL) fibroblasts were used in cell culture studies. The cell culture results showed that plasma treated 3D NWPF discs are favorable for PDL cell spreading, growth and viability due to the presence of functional groups and/or the nanotopography of their surfaces.

?a?mazel, Hilal Türko?lu; Manolache, S.; Gümü?derel?o?lu, M.

394

Closed equations of the two-point functions for tensorial group field theory  

NASA Astrophysics Data System (ADS)

In this paper, we provide the closed equations that satisfy two-point correlation functions of rank 3 and 4 tensorial group field theory. The formulation of the current problem extends the method used by Grosse and Wulkenhaar (2009 arXiv:0909.1389) to the tensor case. Ward-Takahashi identities and Schwinger-Dyson equations are combined to establish a nonlinear integral equation for the two-point functions. In the three-dimensional case, the solution of this equation is given perturbatively at the second order of the coupling constant.

Ousmane Samary, Dine

2014-09-01

395

Auditory functionality and early use of speech in a group of pediatric cochlear implant users.  

PubMed

This study examined auditory functionality and early use of speech in a group of paediatric cochlear implant users. Parents of 33 implanted children from the Universiti Kebangsaan Malaysia Cochlear Implant Program were interviewed using the Meaningful Auditory Integration Scale (MAIS) and the Meaningful Use of Speech Scale (MUSS). In general, higher MAIS scores post-implantation were significantly associated with higher MUSS scores suggesting that those with better functional hearing with the implant were also better in using spontaneous speech to communicate. Multiple regression analyses showed that several time factors significantly correlated with the MAIS scores post-implantation but not with the MUSS. PMID:21265239

Umat, C; Siti Hufaidah, K; Azlizawati, A R

2010-03-01

396

Geographic differences between functional groups in patterns of bird species richness in North America  

NASA Astrophysics Data System (ADS)

Geographic divergences in patterns of species richness were studied for the terrestrial birds of North America using Breeding Bird Survey (BBS) census data subdivided for guild and migratory groups. Our aim was to study if species richness patterns for North American birds were best viewed as the convergent response of different groups to a common mechanism or as the result of several different processes. We observed opposite geographical patterns of species richness and differences in the variables associated with species richness depending on the guild or migratory status considered. Several ecological variables seem to regulate large-scale patterns of terrestrial bird species richness in North America, mainly temperature-, productivity- and landscape habitat structure-related variables. These variables are diverse and group-specific. For instance, the results supported the productivity hypothesis in migratory and frugivore groups and the winter tolerance hypothesis in residents. Habitat structure was also identified as an important factor driving species richness, total abundance and community body mass variation. Overall, our results indicate that the large-scale patterns of bird species richness are the result of several divergent, group-specific processes, and that understanding diversity gradients requires the identification of the functional ecological groups included.

Carnicer, Jofre; Díaz-Delgado, Ricardo

2008-03-01

397

Effects of acidic functional groups on dielectric properties of sodium alginates and carrageenans in water.  

PubMed

This study investigated the dielectric properties of sodium alginates and carrageenans in water at frequencies between 100 MHz and 20 GHz in regard to water-hydrocolloid interactions via acidic functional groups. Both sodium alginates and carrageenans showed conduction loss at lower frequencies and dielectric loss at higher frequencies. Reduction and desulfation of sodium alginates and carrageenans, which decreased the numbers of acidic functional groups, decreased their conduction loss. In addition, H(+)-form carrageenans showed the highest ionic conduction. Correlational analysis of dielectric properties and related physical parameters showed that the loss tangent (tan?) of the hydrocolloid solution was determined by the conductivity of the aqueous solution. Especially at pH below 2, strong H(+) conduction was associated with high tan? probably due to the Grotthuss mechanism. The molecular dynamics of free water and H(+), viscosity conditions were also suggested to be associated with dielectric property of water-hydrocolloid system. PMID:25439871

Tsubaki, Shuntaro; Hiraoka, Masanori; Hadano, Shingo; Okamura, Kei; Ueda, Tadaharu; Nishimura, Hiroshi; Kashimura, Keiichiro; Mitani, Tomohiko

2015-01-22

398

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

USGS Publications Warehouse

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.

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

2010-01-01

399

?-Diversity of Functional Groups of Woody Plants in a Tropical Dry Forest in Yucatan  

PubMed Central

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

López-Martínez, Jorge Omar; Sanaphre-Villanueva, Lucía; Dupuy, Juan Manuel; Hernández-Stefanoni, José Luis; Meave, Jorge Arturo; Gallardo-Cruz, José Alberto

2013-01-01

400

Optimizing noisy funnel-like functions on the euclidean group with applications to protein docking  

Microsoft Academic Search

Formulated as an optimization problem, the final stages of protein docking can be viewed as optimizing a very noisy funnel-like function on the space of rigid body motions, the (special) Euclidean group SE(3). We have recently introduced a stochastic global optimization method, called semi-definite programming based underestimation (SDU) (Paschalidis et al., 2007), that constructs a convex quadratic under-estimator to the

Yang Shen; Pirooz Vakili; Sandor Vajda; I. C. Paschalidis

2007-01-01

401

Schwartz functions, tempered distributions, and Kernel Theorem on solvable Lie groups  

E-print Network

Let G be a solvable Lie group endowed with right Haar measure. We define and study a dense Frechet *-subalgebra S of L1(G), consisting of smooth functions rapidly-decreasing at infinity on G. When G is nilpotent, we recover the classical Schwartz algebra introduced by R. Howe and other authors. We develop a distribution theory for S, and we generalize the classical Kernel Theorem of L. Schwartz to our setting.

David-Guillou, E

2010-01-01

402

EFFECTS OF DIETARY ESFENVALERATE EXPOSURES ON THREE AQUATIC INSECT SPECIES REPRESENTING DIFFERENT FUNCTIONAL FEEDING GROUPS  

Microsoft Academic Search

Given the chemical properties of synthetic pyrethroids, it is probable that compounds, including esfenvalerate, that enter surface waters may become incorporated into aquatic insect food sources. We examined the effect of dietary esfenvalerate uptake in aquatic insects representing different functional feeding groups. We used three field-collected aquatic insect species: A grazing scraper,Cinygmula reticulata McDunnough (Ephemeroptera: Heptageniidae); an omnivorous filter feeder,Brachycentrusamericanus

Katherine R. Palmquist; Jeffrey J. Jenkins; Paul C. Jepson

2008-01-01

403

Does a Functioning Mind Need a Functioning Body? 307 Copyright 2005, Idea Group Inc. Copying or distributing in print or electronic forms without written  

E-print Network

Does a Functioning Mind Need a Functioning Body? 307 Copyright © 2005, Idea Group Inc. Copying 14. Does a Functioning Mind Need a FunctioningBody? Some Perspectives from Postclassical Computation that are generated by mind and then reperceived and acted upon. This chapter considers the somatic marker hypothesis

Kent, University of

404

Cross-Correlation Functions of Galaxies with Grouped and Isolated Quasars in SDSS DR10  

NASA Astrophysics Data System (ADS)

The correlation between galaxies and quasars has been well documented. Here we investigate if pairs and groups of quasars trace more surrounding galaxies than their isolated counterparts. Utilizing 67,961 quasars from the Sloan Digital Sky Survey (SDSS) Data Release 10, a nearest neighbor algorithm was constructed to find grouped and isolated quasars. The results were then compared to 1.7 million galaxies from SDSS DR10 to form quasar-galaxy two-point cross-correlation functions at different quasar redshifts. As expected, galaxies show a stronger correlation with pairs and groups of quasars than with isolated quasars at all redshifts. Our results could help predict regions in the sky where there may be distant galaxies with redshifts z>1.0.

Rhodes, Will; West, M.

2014-01-01

405

Functional renormalization group approach to the singlet-triplet transition in quantum dots.  

PubMed

We present a functional renormalization group approach to the zero bias transport properties of a quantum dot with two different orbitals and in the presence of Hund's coupling. Tuning the energy separation of the orbital states, the quantum dot can be driven through a singlet-triplet transition. Our approach, based on the approach by Karrasch et al (2006 Phys. Rev. B 73 235337), which we apply to spin-dependent interactions, recovers the key characteristics of the quantum dot transport properties with very little numerical effort. We present results on the conductance in the vicinity of the transition and compare our results both with previous numerical renormalization group results and with predictions of the perturbative renormalization group. PMID:22906995

Magnusson, E B; Hasselmann, N; Shelykh, I A

2012-09-12

406

Molecular weight distribution and functional group profiles of TEMPO-oxidized lyocell fibers.  

PubMed

The effects of TEMPO-mediated oxidation, performed with NaClO, a catalytic amount of NaBr, and 2,2',6,6'-tetramethylpiperidine-1-oxy radical (TEMPO), were studied on lyocell fibers by means of GPC using multiple detection and group-selective fluorescence labeling according to the CCOA and FDAM methodology. The applied method determines functional group content as a sum parameter, as well as functional group profiles in relation to the molecular weight of the cellulose fibers. Both the CHO and COOH profiles, as well as molecular weight alterations, were analyzed. A significant decrease in the average molecular weight was obtained during the first hour of TEMPO-mediated oxidation, but prolonged oxidation time resulted in no strong additional chain scission. Significant amounts of COOH groups were introduced in the high molecular weight fractions by the oxidation with higher concentrations of NaClO (2.42-9.67 mmol NaClO/g fiber) after modification times of 1h or longer. PMID:23987366

Milanovic, Jovana; Schiehser, Sonja; Milanovic, Predrag; Potthast, Antje; Kostic, Mirjana

2013-10-15

407

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

PubMed

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

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

408

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

PubMed Central

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

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

409

Functionalized quantum dots induce proinflammatory responses in vitro: the role of terminal functional group-associated endocytic pathways  

NASA Astrophysics Data System (ADS)

PEGylation has been applied as an effective strategy of surface functionalization to improve the stability and reduce non-specific binding of quantum dots (QDs). However, its effects on the proinflammatory properties of QDs and the underlying mechanism have not been well elucidated yet. Herein, the proinflammatory effects of PEGylated CdSe/ZnS QDs with an amphiphilic polymer coating (PEG-pQDs) were investigated in human pulmonary epithelial cells and macrophages by evaluating the cytokine/chemokine production. The results showed that the proinflammatory effects of PEG-pQDs were strongly associated with the functional groups (-COOH, -NH2, -OH, and -OCH3) at the end of PEG chain. COOH-PEG-pQDs demonstrated the most proinflammatory effects followed by NH2-PEG-pQDs and HO-PEG-pQDs with CH3O-PEG-pQDs exhibiting the least proinflammatory effects. The proinflammatory effects of PEG-pQDs relied on lipid raft- and class A scavenger receptor (SRA)-dependent endocytic pathways as well as the downstream NF-?B and MAPK signaling cascades. COOH-PEG-pQDs were selectively internalized by lipid raft- and SRA-mediated endocytosis, which consequently activated NF-?B signaling pathway. On the other hand, NH2-PEG-pQDs and HO-PEG-pQDs were mostly internalized via lipid raft-mediated endocytosis, thereby activating p38 MAPK/AP-1 signaling cascades. These data revealed a critical role of terminal functional group-associated endocytic pathways in the proinflammatory responses induced by PEGylated QDs in human pulmonary epithelial cells and macrophages.PEGylation has been applied as an effective strategy of surface functionalization to improve the stability and reduce non-specific binding of quantum dots (QDs). However, its effects on the proinflammatory properties of QDs and the underlying mechanism have not been well elucidated yet. Herein, the proinflammatory effects of PEGylated CdSe/ZnS QDs with an amphiphilic polymer coating (PEG-pQDs) were investigated in human pulmonary epithelial cells and macrophages by evaluating the cytokine/chemokine production. The results showed that the proinflammatory effects of PEG-pQDs were strongly associated with the functional groups (-COOH, -NH2, -OH, and -OCH3) at the end of PEG chain. COOH-PEG-pQDs demonstrated the most proinflammatory effects followed by NH2-PEG-pQDs and HO-PEG-pQDs with CH3O-PEG-pQDs exhibiting the least proinflammatory effects. The proinflammatory effects of PEG-pQDs relied on lipid raft- and class A scavenger receptor (SRA)-dependent endocytic pathways as well as the downstream NF-?B and MAPK signaling cascades. COOH-PEG-pQDs were selectively internalized by lipid raft- and SRA-mediated endocytosis, which consequently activated NF-?B signaling pathway. On the other hand, NH2-PEG-pQDs and HO-PEG-pQDs were mostly internalized via lipid raft-mediated endocytosis, thereby activating p38 MAPK/AP-1 signaling cascades. These data revealed a critical role of terminal functional group-associated endocytic pathways in the proinflammatory responses induced by PEGylated QDs in human pulmonary epithelial cells and macrophages. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01653f

Zhang, Yijuan; Pan, Hong; Zhang, Pengfei; Gao, Ningning; Lin, Yi; Luo, Zichao; Li, Ping; Wang, Ce; Liu, Lanlan; Pang, Daiwen; Cai, Lintao; Ma, Yifan

2013-06-01

410

Crystal structure of 9-(4-bromo­but­yl)-9H-fluorene-9-carb­oxy­lic acid  

PubMed Central

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

Zhang, Xu-Yang; Liu, Bing-Ni; Wang, Ping-Bao; Liu, Deng-Ke

2014-01-01

411

Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets  

PubMed Central

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. PMID:18463292

Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; Drisdell, Walter S.; Cohen, Ronald C.; Saykally, Richard J.

2008-01-01

412