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Sample records for oxygen-containing functional groups

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

    SciTech Connect

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

    2014-07-03

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

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

    SciTech Connect

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

    2006-10-15

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

  3. Effect of the oxygen-containing functional group of graphene oxide on the aqueous cadmium ions removal

    NASA Astrophysics Data System (ADS)

    Bian, Yu; Bian, Zhao-Yong; Zhang, Jun-Xiao; Ding, Ai-Zhong; Liu, Shao-Lei; Wang, Hui

    2015-02-01

    The adsorption process of graphene oxide (GO) with oxygen-containing functional groups towards cadmium ions was investigated. GO synthesized from graphite by using the modified Hummers method was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS). The oxygen-containing groups on the surfaces of GO played an important role in Cd(II) ion adsorption onto GO. The results of batch experiments indicated that maximal adsorption, which was found to be 23.9 mg/g, could be achieved over the broad pH range of 6.0-7.0. Adsorption isotherms were better fitted by Freundlich model than by Langmuir model and kinetic studies suggested that adsorption was controlled by chemical adsorption. According to FT-IR and XPS analyses of before and after Cd(II) adsorption on GO, electrostatic attraction and cation exchange between Cd(II) and O-containing functional groups on GO were the dominant mechanisms responsible for Cd(II) sorption.

  4. Effect of Oxygen-containing Functional Groups on Protein Stability in Ionic Liquid Solutions

    NASA Technical Reports Server (NTRS)

    Turner, Megan B.; Holbrey, John D.; Spear, Scott K.; Pusey, Marc L.; Rogers, Robin D.

    2004-01-01

    The ability of functionalized ionic liquids (ILs) to provide an environment of increased stability for biomolecules has been studied. Serum albumin is an inexpensive, widely available protein that contributes to the overall colloid osmotic blood pressure within the vascular system. Albumin is used in the present study as a marker of biomolecular stability in the presence of various ILs in a range of concentrations. The incorporation of hydroxyl functionality into the methylimidazolium-based cation leads to increased protein stability detected by fluorescence spectroscopy and circular dichroic (CD) spectrometry.

  5. Oxygen-containing functional group-facilitated CO2 capture by carbide-derived carbons

    PubMed Central

    2014-01-01

    A series of carbide-derived carbons (CDCs) with different surface oxygen contents were prepared from TiC powder by chlorination and followed by HNO3 oxidation. The CDCs were characterized systematically by a variety of means such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultimate analysis, energy dispersive spectroscopy, N2 adsorption, and transmission electron microscopy. CO2 adsorption measurements showed that the oxidation process led to an increase in CO2 adsorption capacity of the porous carbons. Structural characterizations indicated that the adsorbability of the CDCs is not directly associated with its microporosity and specific surface area. As evidenced by elemental analysis, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy, the adsorbability of the CDCs has a linear correlation with their surface oxygen content. The adsorption mechanism was studied using quantum chemical calculation. It is found that the introduction of O atoms into the carbon surface facilitates the hydrogen bonding interactions between the carbon surface and CO2 molecules. This new finding demonstrated that not only the basic N-containing groups but also the acidic O-containing groups can enhance the CO2 adsorbability of porous carbon, thus providing a new approach to design porous materials with superior CO2 adsorption capacity. PMID:24872796

  6. Effects of nitrogen- and oxygen-containing functional groups of activated carbon nanotubes on the electrochemical performance in supercapacitors

    NASA Astrophysics Data System (ADS)

    Liu, Haiyan; Song, Huaihe; Chen, Xiaohong; Zhang, Su; Zhou, Jisheng; Ma, Zhaokun

    2015-07-01

    A kind of nitrogen- and oxygen-containing activated carbon nanotubes (ACNTs) has been prepared by carbonization and activation of polyaniline nanotubes obtained by rapidly mixed reaction. The ACNTs show oxygen content of 15.7% and nitrogen content of 2.97% (atomic ratio). The ACNTs perform high capacitance and good rate capability (327 F g-1 at the current density of 10 A g-1) when used as the electrode materials for supercapacitors. Hydrogen reduction has been further used to investigate the effects of surface functional groups on the electrochemical performance. The changes for both structural component and electrochemical performance reveal that the quinone oxygen, pyridinic nitrogen, and pyrrolic nitrogen of carbon have the most obvious influence on the capacitive property because of their pseudocapacitive contributions.

  7. Ion-molecule reactions for mass spectrometric identification of functional groups in protonated oxygen-containing monofunctional compounds.

    PubMed

    Watkins, Michael A; Price, Jason M; Winger, Brian E; Kenttämaa, Hilkka I

    2004-02-15

    Protonated oxygen-containing monofunctional compounds react with selected methoxyborane reagents by proton transfer followed by nucleophilic substitution of methanol at the boron atom in a Fourier transform ion cyclotron resonance mass spectrometer. The derivatized oxygen functionality can be identified by H/D exchange, collision-activated dissociation, or both. This information on the identity of the functionalities in the analyte, in conjunction with molecular formula information obtained from exact mass measurements on either the protonated or derivatized analyte, facilitates structure elucidation of unknown organic compounds in a mass spectrometer. PMID:14961727

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    SciTech Connect

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

    2011-12-31

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

  11. Odorants with Multiple Oxygen-Containing Functional Groups and Other Odorants with High Water Solubility Preferentially Activate Posterior Olfactory Bulb Glomeruli

    PubMed Central

    Johnson, Brett A.; Arguello, Spart; Leon, Michael

    2008-01-01

    In past studies in which we mapped 2-deoxyglucose uptake evoked by systematically different odorant chemicals across the entire rat olfactory bulb, glomerular responses could be related to each odorant's particular oxygen-containing functional group. In the present study, we tested whether aliphatic odorants containing two such functional groups (esters, ketones, acids, alcohols, and ethers) would stimulate the combination of glomerular regions that are associated with each of the functional groups separately, or whether they would evoke unique responses in different regions of the bulb. We found that these very highly water-soluble molecules rarely evoked activity in the regions responding to the individual functional groups; instead, they activated posterior glomeruli located about halfway between the dorsal and ventral extremes in both the lateral and the medial aspects of the bulb. Additional highly water-soluble odorants, including very small molecules with single oxygenic groups, also strongly stimulated these posterior regions, resulting in a statistically significant correlation between posterior 2-deoxyglucose uptake and molecular properties associated with water solubility. By showing that highly water-soluble odorants stimulate a part of the bulb associated with peripheral and ventral regions of the epithelium, our results challenge a prevalent notion that such odorants would activate class I odorant receptors located in zone 1 of the olfactory epithelium, which projects to the dorsal aspect of the bulb. PMID:17366613

  12. The effect of functional groups on the SO2 adsorption on carbon surface I: A new insight into noncovalent interaction between SO2 molecule and acidic oxygen-containing groups

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Sun, Fei; Qu, Zhibin; Gao, Jihui; Wu, Shaohua

    2016-04-01

    For the aim to give a new insight into the interactions between SO2 molecule and carbon surface and the effect of acidic oxygen-containing groups, density functional theory and noncovalent interaction analysis in terms of reduced density gradient were employed to investigate both the intensity and type of the interactions. The results indicate that the physisorption of SO2 molecule mainly occurs on the basal plane of pure carbon surface due to van der Waals interactions, however, when acidic oxygen-containing groups were decorated on the carbon surface, they would facilitate SO2 adsorption as a result of hydrogen bonding and dipole-dipole interactions. What's more, these groups could not affect the chemisorption of SO2 remarkably, no matter they are near the adsorption sites or not. In addition, calculation results show that the interactions between SO2 and acidic oxygen-containing groups are in physisorption nature, which challenges a long-held the viewpoint of irreversible chemisorption. Acidic oxygen-containing groups could boost the effective surface area of carbon by enhancing the physisorption on edge positions.

  13. Improvement of oxygen-containing functional groups on olive stones activated carbon by ozone and nitric acid for heavy metals removal from aqueous phase.

    PubMed

    Bohli, Thouraya; Ouederni, Abdelmottaleb

    2016-08-01

    Recently, modification of surface structure of activated carbons in order to improve their adsorption performance toward especial pollutants has gained great interest. Oxygen-containing functional groups have been devoted as the main responsible for heavy metal binding on the activated carbon surface; their introduction or enhancement needs specific modification and impregnation methods. In the present work, olive stones activated carbon (COSAC) undergoes surface modifications in gaseous phase using ozone (O3) and in liquid phase using nitric acid (HNO3). The activated carbon samples were characterized using N2 adsorption-desorption isotherm, SEM, pHpzc, FTIR, and Boehm titration. The activated carbon parent (COSAC) has a high surface area of 1194 m(2)/g and shows a predominantly microporous structure. Oxidation treatments with nitric acid and ozone show a decrease in both specific surface area and micropore volumes, whereas these acidic treatments have led to a fixation of high amount of surface oxygen functional groups, thus making the carbon surface more hydrophilic. Activated carbon samples were used as an adsorbent matrix for the removal of Co(II), Ni(II), and Cu(II) heavy metal ions from aqueous solutions. Adsorption isotherms were obtained at 30 °C, and the data are well fitted to the Redlich-Peterson and Langmuir equation. Results show that oxidized COSACs, especially COSAC(HNO3), are capable to remove more Co(II), Cu(II), and Ni(II) from aqueous solution. Nitric acid-oxidized olive stones activated carbon was tested in its ability to remove metal ions from binary systems and results show an important maximum adsorbed amount as compared to single systems. PMID:25794582

  14. Effects of pore sizes and oxygen-containing functional groups on desulfurization activity of Fe/NAC prepared by ultrasonic-assisted impregnation

    NASA Astrophysics Data System (ADS)

    Shu, Song; Guo, Jia-Xiu; Liu, Xiao-Li; Wang, Xue-Jiao; Yin, Hua-Qiang; Luo, De-Ming

    2016-01-01

    A series of Fe-loaded activated carbons treated by HNO3 (Fe/NAC) were prepared by incipient impregnation method with or without ultrasonic assistance and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy disperse spectroscope (SEM-EDS), transmission electron microscopy (TEM) and N2 adsorption/desorption. The desulfurization activities were evaluated at a fixed bed reactor under a mixed gas simulated from flue gas. The results showed that desulfurization activity from excellent to poor is as follows: Fe/NAC-60 > Fe/NAC-80 > Fe/NAC-30 > Fe/NAC-15 > Fe/NAC-0 > Fe/NAC-100 > NAC. Fe/NAC-60 exhibits the best desulfurization activity and has breakthrough sulfur capacity of 319 mg/g and breakthrough time of 540 min. The introduction of ultrasonic oscillation does not change the form of Fe oxides on activated carbon but can change the dispersion and relative contents of Fe3O4. The types of oxygen-containing functional groups have no obvious change for all samples but the texture properties show some differences when they are oscillated for different times. The fresh Fe/NAC-60 has a surface area of 1045 m2/g and total pore volume of 0.961 cm3/g with micropore volume of 0.437 cm3/g and is larger than Fe/NAC-0 (823 m2/g, 0.733 and 0.342 cm3/g). After desulfurization, surface area and pore volume of all samples decrease significantly, and those of the exhausted Fe/NAC-60 decrease to 233 m2/g and 0.481 cm3/g, indicating that some byproducts deposit on surface to cover pores. Pore size distribution influences SO2 adsorption, and fresh Fe/NAC-60 has more pore widths centralized at about 0.7 nm and 1.0-2.0 nm and corresponds to an excellent desulfurization activity, showing that micropore is conducive to the removal of SO2.

  15. Municipal sludge-derived carbon anode with nitrogen- and oxygen-containing functional groups for high-performance microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoxiao; Feng, Chunhua; Zhou, Weijia; Yu, Hui

    2016-03-01

    The demand for efficient and cost-effective anode materials in microbial fuel cells (MFCs) provides the impetus to use carbon derived from solid waste to support bacterial growth and proliferation. Here we show that the municipal sludge-derived carbon (SC) with a porous structure and abundant surface functional groups is effective in improving performance of MFCs. The SC is coated on the 3-D graphite felt (GF) surface by pyrrole electropolymerization in order to increase the surface cites that are interacted with bacteria, resulting in the formation of PPy/SC-modified GF anode. The scanning electron microscopy analysis indicates that the PPy/SC-modified GF can substantially increase anode surface area. The X-ray photoelectron spectroscopy (XPS) results suggest that the PPy/SC-modified GF anode possesses higher surface N/C ratio and higher relative contents of Odbnd C-NH2 and Odbnd C-O functional groups than other counterpart anodes. These characteristics are essential for increasing bacterial attachment to the anode surface, electron-transfer rate and thus anode performance and power performance. The maximum power density resulting from the PPy/SC-modified GF anode was 568.5 mW m-2 (13.6 W m-3) increased by 1.9, 2.7 and 3.5 times as compared to the PPy/AC-modified GF anode, the PPy alone-modified GF anode and the unmodified GF anode, respectively.

  16. Vapor pressure predictions of multi-functional oxygen-containing organic compounds with COSMO-RS

    NASA Astrophysics Data System (ADS)

    Schröder, Bernd; Fulem, Michal; Martins, Mónia A. R.

    2016-05-01

    Given the recent interest in multi-functional oxygen-containing organic compounds and the need of accurate and consistent data, a complete review and systematic analysis of available experimental vapor pressure data, as published in the original work of (Asher et al., 2002), was performed with the ThermoData Engine (TDE). A revised set of critical evaluated vapor pressure data, including their uncertainties based on the principles of dynamic data evaluation, is here recommended for a total of 58 compounds. COSMO-RS was further used for vapor pressure estimations for these compounds. The quality of the results is discussed in terms of the chemical functionalities of the molecules. To illustrate the partition behaviour of the title compounds under ambient conditions, a simple comparison of volatility binning between estimates and measurements was performed. Since the encountered vapor pressures are rather high, with respect to pressure range of semi-volatile organic compounds (SVOC), a large fraction is expected to stay in the atmosphere rather than to form secondary organic aerosol.

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

    PubMed

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

    2015-01-01

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

  18. Phase Behavior of Oxygen-Containing Polymers in CO2

    SciTech Connect

    Killic, Sevgi; Michalik, Stephen; Wang, Yang; Johnson, J.K.; Enick, R.M.; Beckman, E.J.

    2007-02-20

    The cloud point curves of a series of oxygen-containing polymers in CO2 were measured to attempt to deduce the effect of oxygen functional groups within a polymer on the polymer/CO2 phase behavior. The addition of an ether oxygen to a hydrocarbon polymer, either in the backbone or the side chain, enhances "CO2-philicity" by providing sites for specific interactions with CO2 as well as by enhancing the entropy of mixing by creating more flexible chains with higher free volume. Ab initio calculations show that both ether and ester oxygens provide very attractive interaction sites for CO2 molecules. The binding energy for an isolated ether oxygen with CO2 is larger in magnitude than that for a carbonyl oxygen/CO2 complex. However, acetate functionalized polymers are more CO2-soluble than polymers with only ether functionalities-possibly because acetate functional groups contain a total of three binding modes for CO2 interactions, compared with only one for the ether functional group. Experiments clearly indicate that adding a single methylene group as a spacer between a polymer backbone and either an ether or acetate group exhibits a strong deleterious effect on phase behavior. This effect cannot be explained from our ab initio calculations.

  19. Renormalization group functional equations

    SciTech Connect

    Curtright, Thomas L.; Zachos, Cosmas K.

    2011-03-15

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

  20. Functional Group Analysis.

    ERIC Educational Resources Information Center

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

    1984-01-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  2. Thermal rearrangement of oxygen-containing {omicron}-allyltoluene derivatives

    SciTech Connect

    Li, F.

    1995-02-10

    For several years, workers in the Trahanovsky group have been studying the gas phase thermal reactions of simple organic molecules. The FVP of {Omicron}-allyltoluene involves a novel rearrangement that is proposed to involve a diradical produced by intramolecular hydrogen-atom transfer which undergoes intramolecular coupling to give 2-methylindan. Studies of this rearrangement have been extended to other systems. The two papers in this thesis describe studies of the flash vacuum pyrolysis (FVP) of oxygen-containing {omicron}-allyltoluene derivatives. In the first chapter of this thesis, the results from o-allylbenzaldehyde and related compounds are examined in terms of the intramolecular hydrogen-atom transfer diradical/coupling mechanism. A mechanism which involves an enol intermediate generated by an oxa-1,5 H shift is proposed for formation of naphthalene from the FVP of o-allylbenzaldehyde. In the second chapter more limitations of the formation of the diradicals is revealed.

  3. Cluster functional renormalization group

    NASA Astrophysics Data System (ADS)

    Reuther, Johannes; Thomale, Ronny

    2014-01-01

    Functional renormalization group (FRG) has become a diverse and powerful tool to derive effective low-energy scattering vertices of interacting many-body systems. Starting from a free expansion point of the action, the flow of the RG parameter Λ 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.

  4. Application of thermogravimetric Fourier transform infrared spectroscopy (TG-FTIR) to the analysis of oxygen functional groups in coal

    SciTech Connect

    L. Giroux; J.-P. Charland; J.A. MacPhee

    2006-10-15

    This paper attempts to relate oxygen-containing gases H{sub 2}O, CO{sub 2}, and CO evolved during pyrolysis of the Argonne premium coals to oxygen-containing functional groups as a function of rank. Our approach to functional group analysis of oxygen-containing species in coal has been to use a pyrolysis technique, thermogravimetric Fourier transform infrared spectroscopy (TG-FTIR), involving thermogravimetric analysis with the measurement of the gaseous decomposition products via IR detection. Under suitable heating conditions, TG-FTIR pyrolysis of a coal sample in a stream of inert gas has been shown to expel quantitatively all of the organic oxygen in the form of H{sub 2}O, CO{sub 2}, and CO, and consequently, this technique can be effectively applied for determining the total oxygen content. Focusing on the Argonne premium coals, which cover a wide range in rank between lignite (Ro = 0.25) and low-volatile bituminous (Ro = 1.68), TG-FTIR provided complex pyrolysis profiles of oxygen-containing gases, which yield information on the sources of the different peaks observed in coal as a function of rank from a chemical-structure standpoint. Deconvolution of the complex profiles was performed to assign peaks to the different sources of oxygen-containing gases. Model polymers containing various oxygen functional groups in aliphatic and/or aromatic molecular environments were also pyrolyzed by TG-FTIR in an attempt to assign peaks in the gas evolution profiles of the Argonne premium coals. Although complex evolution profiles were observed for the three oxygen-containing gas species H{sub 2}O, CO{sub 2}, and CO in the Argonne premium coals, the strength of the TG-FTIR technique in revealing both similarities and differences in profiles depending upon the coal rank was evident. 19 refs., 6 figs., 9 tabs.

  5. Functional Group Analysis.

    ERIC Educational Resources Information Center

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

    1980-01-01

    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)

  6. Optimization and application of atmospheric pressure chemical and photoionization hydrogen-deuterium exchange mass spectrometry for speciation of oxygen-containing compounds.

    PubMed

    Acter, Thamina; Kim, Donghwi; Ahmed, Arif; Jin, Jang Mi; Yim, Un Hyuk; Shim, Won Joon; Kim, Young Hwan; Kim, Sunghwan

    2016-05-01

    This paper presents a detailed investigation of the feasibility of optimized positive and negative atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and atmospheric pressure photoionization (APPI) MS coupled to hydrogen-deuterium exchange (HDX) for structural assignment of diverse oxygen-containing compounds. The important parameters for optimization of HDX MS were characterized. The optimized techniques employed in the positive and negative modes showed satisfactory HDX product ions for the model compounds when dichloromethane and toluene were employed as a co-solvent in APCI- and APPI-HDX, respectively. The evaluation of the mass spectra obtained from 38 oxygen-containing compounds demonstrated that the extent of the HDX of the ions was structure-dependent. The combination of information provided by different ionization techniques could be used for better speciation of oxygen-containing compounds. For example, (+) APPI-HDX is sensitive to compounds with alcohol, ketone, or aldehyde substituents, while (-) APPI-HDX is sensitive to compounds with carboxylic functional groups. In addition, the compounds with alcohol can be distinguished from other compounds by the presence of exchanged peaks. The combined information was applied to study chemical compositions of degraded oils. The HDX pattern, double bond equivalent (DBE) distribution, and previously reported oxidation products were combined to predict structures of the compounds produced from oxidation of oil. Overall, this study shows that APCI- and APPI-HDX MS are useful experimental techniques that can be applied for the structural analysis of oxygen-containing compounds. PMID:26898203

  7. Preparation of oxygen-containing organic products from bed-oxidized brown coal by ozonation

    SciTech Connect

    Semenova, S.A.; Patrakov, Y.F.; Batina, M.V.

    2009-01-15

    The possibility of modifying the functional composition of humic acids by gas-phase ozonation of bed-oxidized brown coal was examined. About 90% of the organic matter of brown coal was converted to low-molecular weight soluble oxygen-containing products by stepwise liquid-phase ozonation (in chloroform and acetic acid).

  8. Investigation of oxygen functional groups in low rank coal

    SciTech Connect

    Hagaman, E.W.; Lee, S.K.

    1993-07-01

    The distribution of the organic oxygen content of coals among the principal oxygen containing functional groups typically is determined by a combination of chemical and spectroscopic methods (1,2) and results in a classification scheme such as % carboxyl, % hydroxyl, % carbonyl, and % ether. A notable subdivision in this classification scheme is the differentiation of phenols in a coal on the basis of their ortho-substitution pattern (3). Apart from this distinction, the further classification of oxygen into functional group subsets is virtually nonexistent. This paper presents initial experiments that indicate a fuller characterization of oxygen distribution in low rank coal is possible. The experimental approach couples selective chemical perturbation and solid state NMR analysis of the material, specifically, the fluorination of Argonne Premium Coal {number_sign}8, North Dakota lignite, and spectroscopic examination by high resolution solid state {sup 19}F NMR (4). The fluorination reagent is diethylaminosulfur trifluoride (DAST), (Et){sub 2}NSF{sub 3}, which promotes a rich slate of oxygen functional group interconversions that introduce fluorine into the coal matrix (5). The virtual absence of this element in coals make {sup 19}F an attractive NMR nuclei for this application (6). The present experiments use direct detection of the {sup 19}F nucleus under conditions of proton ({sup 1}H) heteronuclear dipolar decoupling and magic angle spinning (MAS). The ca 300 ppm range of {sup 19}F chemical shifts in common carbon-fluorine bonding configurations and high {sup 19}F nuclear sensitivity permit the identification of unique and chemically dilute functional groups in the coal milieu. The unique detection of aromatic and aliphatic carboxylic acids and primary and secondary alcohols provide examples of the exquisite functional group detail that is revealed by this combination of techniques.

  9. Copyrolysis of bitumen and oxygenate containing materials at low temperature

    NASA Astrophysics Data System (ADS)

    Toosi, Elaheh

    Bitumen, as one of the most important unconventional sources of energy, has long been an attractive source for production of liquid fuels. It is important to improve the yield and quality of the useful products resulting from bitumen upgrading processes so that the best outcome can be achieved with the least capital cost. It has been shown in literature that if the thermal upgrading processes are performed at lower temperature (below 400 °C), the obtained liquid yield can be improved. However, the low temperature slows down the rates and in general low temperature processes are less likely to be economical in industry. If this rate-challenge can be overcome, it is more beneficial to operate the bitumen upgrading processes at lower temperature. The working hypothesis was that oxygenate containing compounds, which are more reactive for thermal conversion, can be used to increase the overall reaction rate of bitumen conversion at lower temperature. This thesis studied the effect of co-processing some oxygenate containing materials with bitumen, namely, different coal and biomass derived materials.

  10. Learning the Functional Groups: Keys to Success.

    ERIC Educational Resources Information Center

    Byrd, Shannon; Hildreth, David P.

    2001-01-01

    Points out the difficulties students have when they are expected to learn functional groups, which are frameworks for chemical and physical properties of molecules. Presents a classification key for functional groups categorized by 10 common functional groups. (YDS)

  11. Reaction of guanidine hydrohalides with oxygen-containing compounds

    SciTech Connect

    Berezovskii, F.I.; Demikhov, Y.N.; Korostyshevskii, I.Z.; Lyuta, N.N.

    1986-04-10

    To liberate oxygen in the form CO/sub 2/ from solid inorganic oxygen-containing compounds it was proposed that their reaction with guanidine hydrohalides (GHC) be used. The yield of oxygen is 100% for most basic and amphoteric oxides. Salts of carbonic, sulfuric, boric and other acids react with GHE to give 100% yield of oxygen. Some polymorphous modifications of oxides (alpha-Al/sub 2/O/sub 3/ and the like) and also nitrites and nitrates reaction non-quantitatively with GHC. The mechanisms of the reactions of GHC with oxides and carbonates have been studied. It was found that water is eliminated at the intermediate stage. The method is simple, economical and safe.

  12. A Functional Analytic Approach to Group Psychotherapy

    ERIC Educational Resources Information Center

    Vandenberghe, Luc

    2009-01-01

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

  13. The functions of ritual in social groups.

    PubMed

    Watson-Jones, Rachel E; Legare, Cristine H

    2016-01-01

    Ritual cognition builds upon social learning biases that may have become specialized for affiliation within social groups. The adaptive problems of group living required a means of identifying group members, ensuring commitment to the group, facilitating cooperation, and maintaining group cohesion. We discuss how ritual serves these social functions. PMID:26948744

  14. Energetic oxygen-containing tetrazole salts based on 3,4-diaminotriazole.

    PubMed

    Wu, Jin-Ting; Zhang, Jian-Guo; Yin, Xin; Wu, Kun

    2015-05-01

    Energetic mono- and dicationic 3,4-diaminotriazolium salts have been prepared by combining stoichiometric amounts (1:1 or 2:1 molar ratio) of 3,4-diaminotriazole with various oxygen-containing tetrazoles, and the structures have been confirmed by single-crystal XRD for the first time. All structures are dominated by a strong hydrogen-bond network owing to both amino groups and oxygen in the molecule. All salts, except 7, exhibit excellent thermal stabilities with decomposition temperatures over 200 °C. Based on experimental densities and theoretical calculations carried out by using the Gaussian 03 suite of programs, all salts have calculated detonation pressures (20.3-33.9 GPa) and velocities (7095-8642 m s(-1)). PMID:25712781

  15. Comparatively studying the ultrasound present in a mild two-stage approach on the content of functional groups in modified MWCNT

    NASA Astrophysics Data System (ADS)

    Tian, Run; Liang, Shaolei; Li, Guangfen; Zhang, Yanxia; Shi, Le

    2016-04-01

    A two-stage approach assisted with ultrasound for oxidation of multiwalled carbon nanotubes (MWCNT) with ultra-high content of functional groups was utilized. The effect of ultrasound on the content of functional groups of the modified MWCNTs from different stages was analyzed by FE-SEM, HR-TEM, FTIR, Raman, TGA, XPS and triple double-backward titration method. The results confirm that more oxygen-containing functional groups were grafted on MWCNT with little damage to the structure integrity of nanotubes. The particle size distribution and the dispersion photography of MWCNTs in water and in ethanol further show a better dispersion of modified MWCNTs in polar solvent.

  16. Localization of functions defined on cantor group

    NASA Astrophysics Data System (ADS)

    Krivoshein, Aleksander V.; Lebedeva, Elena A.

    2013-10-01

    We introduce a notion of localization for dyadic functions, i. e. functions defined on Cantor group. Both non-periodic and periodic cases are discussed. Localization is characterized by functionals UCd and UCdp similar to the Heisenberg (the Breitenberger) uncertainty constants used for real-line (periodic) functions. We are looking for dyadic analogs of uncertainty principles. To justify definition we use some test functions including dyadic scaling and wavelet functions.

  17. Relating Functional Groups to the Periodic Table

    ERIC Educational Resources Information Center

    Struyf, Jef

    2009-01-01

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

  18. Reactions of oxygen-containing molecules on transition metal carbides: Surface science insight into potential applications in catalysis and electrocatalysis

    NASA Astrophysics Data System (ADS)

    Stottlemyer, Alan L.; Kelly, Thomas G.; Meng, Qinghe; Chen, Jingguang G.

    2012-09-01

    Historically the interest in the catalytic properties of transition metal carbides (TMC) has been inspired by their "Pt-like" properties in the transformation reactions of hydrocarbon molecules. Recent studies, however, have revealed that the reaction pathways of oxygen-containing molecules are significantly different between TMCs and Pt-group metals. Nonetheless, TMCs demonstrate intriguing catalytic properties toward oxygen-containing molecules, either as the catalyst or as the catalytically active substrate to support metal catalysts, in several important catalytic and electrocatalytic applications, including water electrolysis, alcohol electrooxidation, biomass conversion, and water gas shift reactions. In the current review we provide a summary of theoretical and experimental studies of the interaction of TMC surfaces with oxygen-containing molecules, including both inorganic (O2, H2O, CO and CO2) and organic (alcohols, aldehydes, acids and esters) molecules. We will discuss the general trends in the reaction pathways, as well as future research opportunities in surface science studies that would facilitate the utilization of TMCs as catalysts and electrocatalysts.

  19. Reactions of oxygen-containing molecules on transition metal carbides: Surface science insight into potential applications in catalysis and electrocatalysis

    NASA Astrophysics Data System (ADS)

    Stottlemyer, Alan L.; Kelly, Thomas G.; Meng, Qinghe; Chen, Jingguang G.

    2012-09-01

    Historically the interest in the catalytic properties of transition metal carbides (TMC) has been inspired by their “Pt-like” properties in the transformation reactions of hydrocarbon molecules. Recent studies, however, have revealed that the reaction pathways of oxygen-containing molecules are significantly different between TMCs and Pt-group metals. Nonetheless, TMCs demonstrate intriguing catalytic properties toward oxygen-containing molecules, either as the catalyst or as the catalytically active substrate to support metal catalysts, in several important catalytic and electrocatalytic applications, including water electrolysis, alcohol electrooxidation, biomass conversion, and water gas shift reactions. In the current review we provide a summary of theoretical and experimental studies of the interaction of TMC surfaces with oxygen-containing molecules, including both inorganic (O2, H2O, CO and CO2) and organic (alcohols, aldehydes, acids and esters) molecules. We will discuss the general trends in the reaction pathways, as well as future research opportunities in surface science studies that would facilitate the utilization of TMCs as catalysts and electrocatalysts.

  20. Methods for separating oxygen from oxygen-containing gases

    DOEpatents

    Mackay, Richard; Schwartz, Michael; Sammells, Anthony F.

    2000-01-01

    This invention provides mixed conducting metal oxides particularly useful for the manufacture of catalytic membranes for gas-phase oxygen separation processes. The materials of this invention have the general formula: A.sub.x A'.sub.x A".sub.2-(x+x') B.sub.y B'.sub.y B".sub.2-(y+y') O.sub.5+z ; where x and x' are greater than 0; y and y' are greater than 0; x+x' is less than or equal to 2; y+y' is less than or equal to 2; z is a number that makes the metal oxide charge neutral; A is an element selected from the f block lanthanide elements; A' is an element selected from Be, Mg, Ca, Sr, Ba and Ra; A" is an element selected from the f block lanthanides or Be, Mg, Ca, Sr, Ba and Ra; B is an element selected from the group consisting of Al, Ga, In or mixtures thereof; and B' and B" are different elements and are independently selected from the group of elements Mg or the d-block transition elements. The invention also provides methods for oxygen separation and oxygen enrichment of oxygen deficient gases which employ mixed conducting metal oxides of the above formula. Examples of the materials used for the preparation of the membrane include A.sub.x Sr.sub.x' B.sub.y Fe.sub.y' Co.sub.2-(y+y') O.sub.5+z, where x is about 0.3 to about 0.5, x' is about 1.5 to about 1.7, y is 0.6, y' is between about 1.0 and 1.4 and B is Ga or Al.

  1. Sub millimeter absorption spectroscopy of oxygen containing fluorocarbon etching plasmas

    NASA Astrophysics Data System (ADS)

    Benck, Eric; Siegrist, Karen

    2004-09-01

    The role of oxygen in fluorocarbon etching plasmas is investigated using sub millimeter wavelength absorption spectroscopy. The plasmas were created in a specially modified capacitively coupled Gaseous Electronics Conference (GEC) Reference Reactor with a commercial electrostatic chuck. Photoresist and SiO2 blanket coated wafers were etched in C_4F_8/O_2/Ar, C_5F_8/O_2/Ar, and C_4F_6/O_2/Ar discharges. The absolute density of various radicals (CF, CF_2, CHF_3, COF_2, CO, etc.) were measured as a function of the percentage of oxygen in the feed gas mixture using a sub millimeter source based on a 48x frequency multiplication chain. These results are also compared with C_xF_y/O_2/Xe mixtures.

  2. Identifying copepod functional groups from species functional traits

    PubMed Central

    Benedetti, Fabio; Gasparini, Stéphane; Ayata, Sakina-Dorothée

    2016-01-01

    We gathered information on the functional traits of the most representative copepod species in the Mediterranean Sea. Our database includes 191 species described by 7 traits encompassing diverse ecological functions: minimal and maximal body length, trophic group, feeding type, spawning strategy, diel vertical migration and vertical habitat. Cluster analysis in the functional trait space revealed that Mediterranean copepods can be separated into groups with distinct ecological roles. PMID:26811565

  3. The circular velocity function of group galaxies

    SciTech Connect

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

    2014-09-20

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

  4. Interactions Between Odorant Functional Group and Hydrocarbon Structure Influence Activity in Glomerular Response Modules in the Rat Olfactory Bulb

    PubMed Central

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

    2008-01-01

    To investigate the effect of odorant hydrocarbon structure on spatial representations in the olfactory bulb systematically, we exposed rats to odorant chemicals possessing one of four different oxygen-containing functional groups on one of five different hydrocarbon backbones. We also used several hydrocarbon odorants lacking other functional groups. Hydrocarbon structural categories included straight-chained, branched, double-bonded, alicyclic, and aromatic features. Activity throughout the entire glomerular layer was measured as uptake of [14C]2-deoxyglucose and was mapped into anatomically standardized data matrices for statistical comparisons across different animals. Patterns evoked by straight-chained aliphatic odorants confirmed an association of activity in particular glomerular response modules with particular functional groups. However, the amount of activity in these same modules also was affected significantly by differences in hydrocarbon structure. Thus, the molecular features recognized by receptors projecting to these response modules appear to involve both functional group and hydrocarbon structural elements. In addition, particular benzyl and cyclohexyl odorants evoked activity in dorsal modules previously associated with the ketone functional group, which represents an exception to the rule of one feature per response module that had emerged from our previous studies. These dorsal modules also responded to nitrogen-containing aromatic compounds involving pyridine and pyrazine rings. The unexpected overlap in modular responses to ketones and odorants seemingly unrelated to ketones may reflect some covert shared molecular feature, the existence of odorant sensory neurons with multiple specificities, or a mosaic of sensory neuron projections to these particular modules. PMID:15678471

  5. The role of oxygen containing impurities in defects formation in cesium halide crystals

    NASA Astrophysics Data System (ADS)

    Hud, I.; Garapyn, I.; Pavlyk, B.

    2003-01-01

    The dependence of defect formation efficiency in CsI single crystals both on the type of oxygen containing impurities and the value of the absorbed irradiation dose was studied. Correlative results were obtained under investigation by methods of ionic thermocurrent (ITC), thermostimulated exoemission (TSEE), electrical conductivity and optical spectroscopy. The peculiarities of defect formation in gamma-irradiated CsI-CO3(SO4, OH) and X-irradiated CsI-OH single crystals are discussed.

  6. pi. -Electron ring currents and magnetic shielding in oxygen-containing unsaturated heterosystems

    SciTech Connect

    Vysotskii, Yu.B.; Sivyakova, L.N.

    1985-11-01

    A procedure developed previously for the calculation of molecular magnetic characteristics has been applied to calculations of diamagnetic susceptibilities and the chemical shifts of protons and /sup 13/C nuclei of oxygen-containing heterocycles. The results are in accord with experimental data. The distributions of current that are used as the basis for such calculations are discussed, and a scale of aromaticity is given for the systems that have been investigated.

  7. Functional renormalization group approach to noncollinear magnets

    NASA Astrophysics Data System (ADS)

    Delamotte, B.; Dudka, M.; Mouhanna, D.; Yabunaka, S.

    2016-02-01

    A functional renormalization group approach to d -dimensional, N -component, noncollinear magnets is performed using various truncations of the effective action relevant to study their long distance behavior. With help of these truncations we study the existence of a stable fixed point for dimensions between d =2.8 and d =4 for various values of N focusing on the critical value Nc(d ) that, for a given dimension d , separates a first-order region for N Nc(d ) . Our approach concludes to the absence of a stable fixed point in the physical—N =2 ,3 and d =3 —cases, in agreement with the ɛ =4 -d expansion and in contradiction with previous perturbative approaches performed at fixed dimension and with recent approaches based on the conformal bootstrap program.

  8. Kinetics of Several Oxygen-Containing Carbon-Centered Free Radical Reactions with Nitric Oxide.

    PubMed

    Rissanen, Matti P; Ihlenborg, Marvin; Pekkanen, Timo T; Timonen, Raimo S

    2015-07-16

    Kinetics of four carbon-centered, oxygen-containing free radical reactions with nitric oxide (NO) were investigated as a function of temperature at a few Torr pressure of helium, employing flow tube reactors coupled to a laser-photolysis/resonance-gas-discharge-lamp photoionization mass spectrometer (LP-RPIMS). Rate coefficients were directly determined from radical (R) decay signals under pseudo-first-order conditions ([R]0 ≪ [NO]). The obtained rate coefficients showed negative temperature dependences, typical for a radical-radical association process, and can be represented by the following parametrizations (all in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO) = (4.76 × 10(-21)) × (T/300 K)(15.92) × exp[50700/(RT)] (T = 266-363 K, p = 0.79-3.44 Torr); k(CH3CHOH + NO) = (1.27 × 10(-16)) × (T/300 K)(6.81) × exp[28700/(RT)] (T = 241-363 K, p = 0.52-3.43 Torr); k(CH3OCH2 + NO) = (3.58 ± 0.12) × 10(-12) × (T/300 K)(-3.17±0.14) (T = 221-363 K, p = 0.50-0.80 Torr); k(T)3 = 9.62 × 10(-11) × (T/300 K)(-5.99) × exp[-7100/(RT)] (T = 221-473 K, p = 1.41-2.95 Torr), with the uncertainties given as standard errors of the fits and the overall uncertainties estimated as ±20%. The rate of CH3OCH2 + NO reaction was measured in two density ranges due to its observed considerable pressure dependence, which was not found in the studied hydroxyalkyl reactions. In addition, the CH3CO + NO rate coefficient was determined at two temperatures resulting in k298K(CH3CO + NO) = (5.6 ± 2.8) × 10(-13) cm(3) molecule(-1) s(-1). No products were found during these experiments, reasons for which are briefly discussed. PMID:26000890

  9. Preconversion catalytic deoxygenation of phenolic functional groups

    SciTech Connect

    Kubiak, C.P.

    1991-01-01

    The deoxygenation of phenols is a conceptually simple, but unusually difficult chemical transformation to achieve. Aryl carbon-oxygen bond cleavage is a chemical transformation of importance in coal liquefaction and the upgrading of coal liquids as well as in the synthesis of natural products. This proposed research offers the possibility of effecting the selective catalytic deoxygenation of phenolic functional groups using CO. A program of research for the catalytic deoxygenation of phenols, via a low energy mechanistic pathway that is based on the use of the CO/CO{sub 2} couple to remove phenolic oxygen atoms, is underway. We are focusing on systems which have significant promise as catalysts: Ir(triphos)OPh, (Pt(triphos)OPh){sup +} and Rh(triphos)OPh. Our studies of phenol deoxygenation focus on monitoring the reactions for the elementary processes upon which catalytic activity will depend: CO insertion into M-OPh bonds, CO{sub 2} elimination from aryloxy carbonyls {l brace}M-C(O)-O-Ph{r brace}, followed by formation of a coordinated benzyne intermediate.

  10. Toward Relatively General and Accurate Quantum Chemical Predictions of Solid-State 17O NMR Chemical Shifts in Various Biologically Relevant Oxygen-containing Compounds

    PubMed Central

    Rorick, Amber; Michael, Matthew A.; Yang, Liu; Zhang, Yong

    2015-01-01

    Oxygen is an important element in most biologically significant molecules and experimental solid-state 17O NMR studies have provided numerous useful structural probes to study these systems. However, computational predictions of solid-state 17O NMR chemical shift tensor properties are still challenging in many cases and in particular each of the prior computational work is basically limited to one type of oxygen-containing systems. This work provides the first systematic study of the effects of geometry refinement, method and basis sets for metal and non-metal elements in both geometry optimization and NMR property calculations of some biologically relevant oxygen-containing compounds with a good variety of XO bonding groups, X= H, C, N, P, and metal. The experimental range studied is of 1455 ppm, a major part of the reported 17O NMR chemical shifts in organic and organometallic compounds. A number of computational factors towards relatively general and accurate predictions of 17O NMR chemical shifts were studied to provide helpful and detailed suggestions for future work. For the studied various kinds of oxygen-containing compounds, the best computational approach results in a theory-versus-experiment correlation coefficient R2 of 0.9880 and mean absolute deviation of 13 ppm (1.9% of the experimental range) for isotropic NMR shifts and R2 of 0.9926 for all shift tensor properties. These results shall facilitate future computational studies of 17O NMR chemical shifts in many biologically relevant systems, and the high accuracy may also help refinement and determination of active-site structures of some oxygen-containing substrate bound proteins. PMID:26274812

  11. Iron- and indium-catalyzed reactions toward nitrogen- and oxygen-containing saturated heterocycles.

    PubMed

    Cornil, Johan; Gonnard, Laurine; Bensoussan, Charlélie; Serra-Muns, Anna; Gnamm, Christian; Commandeur, Claude; Commandeur, Malgorzata; Reymond, Sébastien; Guérinot, Amandine; Cossy, Janine

    2015-03-17

    A myriad of natural and/or biologically active products include nitrogen- and oxygen-containing saturated heterocycles, which are thus considered as attractive scaffolds in the drug discovery process. As a consequence, a wide range of reactions has been developed for the construction of these frameworks, much effort being specially devoted to the formation of substituted tetrahydropyrans and piperidines. Among the existing methods to form these heterocycles, the metal-catalyzed heterocyclization of amino- or hydroxy-allylic alcohol derivatives has emerged as a powerful and stereoselective strategy that is particularly interesting in terms of both atom-economy and ecocompatibility. For a long time, palladium catalysts have widely dominated this area either in Tsuji-Trost reactions [Pd(0)] or in an electrophilic activation process [Pd(II)]. More recently, gold-catalyzed formation of saturated N- and O-heterocycles has received growing attention because it generally exhibits high efficiency and diastereoselectivity. Despite their demonstrated utility, Pd- and Au-complexes suffer from high costs, toxicity, and limited natural abundance, which can be barriers to their widespread use in industrial processes. Thus, the replacement of precious metals with less expensive and more environmentally benign catalysts has become a challenging issue for organic chemists. In 2010, our group took advantage of the ability of the low-toxicity and inexpensive FeCl3 in activating allylic or benzylic alcohols to develop iron-catalyzed N- and O-heterocylizations. We first focused on N-heterocycles, and a variety of 2,6-disubstituted piperidines as well as pyrrolidines were synthesized in a highly diastereoselective fashion in favor of the cis-compounds. The reaction was further extended to the construction of substituted tetrahydropyrans. Besides triggering the formation of heterocycles, the iron salts were shown to induce a thermodynamic epimerization, which is the key to reach the high

  12. Feminist Research Methodology Groups: Origins, Forms, Functions.

    ERIC Educational Resources Information Center

    Reinharz, Shulamit

    Feminist Research Methodology Groups (FRMGs) have developed as a specific type of women's group in which feminist academics can find supportive audiences for their work while contributing to a feminist redefinition of research methods. An analysis of two FRMGs reveals common characteristics, dynamics, and outcomes. Both were limited to small…

  13. Transition metal carbides, nitrides and borides, and their oxygen containing analogs useful as water gas shift catalysts

    DOEpatents

    Thompson, Levi T.; Patt, Jeremy; Moon, Dong Ju; Phillips, Cory

    2003-09-23

    Mono- and bimetallic transition metal carbides, nitrides and borides, and their oxygen containing analogs (e.g. oxycarbides) for use as water gas shift catalysts are described. In a preferred embodiment, the catalysts have the general formula of M1.sub.A M2.sub.B Z.sub.C O.sub.D, wherein M1 is selected from the group consisting of Mo, W, and combinations thereof; M2 is selected from the group consisting of Fe, Ni, Cu, Co, and combinations thereof; Z is selected from the group consisting of carbon, nitrogen, boron, and combinations thereof; A is an integer; B is 0 or an integer greater than 0; C is an integer; O is oxygen; and D is 0 or an integer greater than 0. The catalysts exhibit good reactivity, stability, and sulfur tolerance, as compared to conventional water shift gas catalysts. These catalysts hold promise for use in conjunction with proton exchange membrane fuel cell powered systems.

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

    PubMed Central

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

    2015-01-01

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

  15. Modifications of chemical functional groups of Pandanus amaryllifolius Roxb and its effect towards biosorption of heavy metals

    NASA Astrophysics Data System (ADS)

    Abdullah, Mohd. Zamri; Ismail, Siti Salwa

    2015-07-01

    The utilization of non-living biomass as an alternative biosorbent for heavy metal removal has gain a tremendous consideration through the years. Pandanus amaryllifolius Roxb or pandan leaves, which is widely used as food additives in the South East Asia region, has been selected for its viability in the said effort due to the presence of chemical functional groups on its cellular network that enables the sorption to occur. In order to elucidate the possible mechanisms participated during the heavy metal removal process, the biosorbent undergone a series of modification techniques to alter the chemical functional groups present on its constituent. From the outcome of the chemically-modified biosorbent being subjected to the contact with metal cations, nitrogen- and oxygen-containing groups present on the biosorbent are believed to be responsible for the metal uptake to occur through complexation mechanism. Modifying amine groups causes 14% reduction of Cu(II) uptake, whereas removing protein element increases the uptake to 26% as compared to the unmodified biosorbent. Also, scanning electron micrographs further suggested that the adsorption mechanism could perform in parallel, as attributed to the evidence of porous structure throughout the biosorbent fibrous nature.

  16. Modifications of chemical functional groups of Pandanus amaryllifolius Roxb and its effect towards biosorption of heavy metals

    SciTech Connect

    Abdullah, Mohd Zamri Ismail, Siti Salwa

    2015-07-22

    The utilization of non-living biomass as an alternative biosorbent for heavy metal removal has gain a tremendous consideration through the years. Pandanus amaryllifolius Roxb or pandan leaves, which is widely used as food additives in the South East Asia region, has been selected for its viability in the said effort due to the presence of chemical functional groups on its cellular network that enables the sorption to occur. In order to elucidate the possible mechanisms participated during the heavy metal removal process, the biosorbent undergone a series of modification techniques to alter the chemical functional groups present on its constituent. From the outcome of the chemically-modified biosorbent being subjected to the contact with metal cations, nitrogen- and oxygen-containing groups present on the biosorbent are believed to be responsible for the metal uptake to occur through complexation mechanism. Modifying amine groups causes 14% reduction of Cu(II) uptake, whereas removing protein element increases the uptake to 26% as compared to the unmodified biosorbent. Also, scanning electron micrographs further suggested that the adsorption mechanism could perform in parallel, as attributed to the evidence of porous structure throughout the biosorbent fibrous nature.

  17. The formation of oxygen-containing organic molecules in the Orion compact ridge

    NASA Technical Reports Server (NTRS)

    Millar, T. J.; Herbst, Eric; Charnley, S. B.

    1991-01-01

    Following a suggestion of Blake et al. (1987), an attempt was made to account for the unusually large abundances of selected oxygen-containing organic molecules in the so-called 'compact ridge' source directed toward Orion KL by a gas-phase chemical model in which large amounts of water are injected into the source from the IRc2 outflow. Although quantitative model results show that the calculated abundances of methanol, methyl formate, and dimethyl ether can be enhanced relative to their values in the absence of water injection, the enhancements fall far short of explaining the very large observed abundances of these species. Models in which methanol is injected rather than water are more successful, although the source of the methanol is unclear.

  18. Plant for producing an oxygen-containing additive as an ecologically beneficial component for liquid motor fuels

    DOEpatents

    Siryk, Yury Paul; Balytski, Ivan Peter; Korolyov, Volodymyr George; Klishyn, Olexiy Nick; Lnianiy, Vitaly Nick; Lyakh, Yury Alex; Rogulin, Victor Valery

    2013-04-30

    A plant for producing an oxygen-containing additive for liquid motor fuels comprises an anaerobic fermentation vessel, a gasholder, a system for removal of sulphuretted hydrogen, and a hotwell. The plant further comprises an aerobic fermentation vessel, a device for liquid substance pumping, a device for liquid aeration with an oxygen-containing gas, a removal system of solid mass residue after fermentation, a gas distribution device; a device for heavy gases utilization; a device for ammonia adsorption by water; a liquid-gas mixer; a cavity mixer, a system that serves superficial active and dispersant matters and a cooler; all of these being connected to each other by pipelines. The technical result being the implementation of a process for producing an oxygen containing additive, which after being added to liquid motor fuels, provides an ecologically beneficial component for motor fuels by ensuring the stability of composition fuel properties during long-term storage.

  19. Oxygen-containing subunits in sulfur-rich non-polar macromolecules

    NASA Astrophysics Data System (ADS)

    Jenisch-Anton, A.; Adam, P.; Schaeffer, P.; Albrecht, P.

    1999-04-01

    Substantial amounts of alcohols occur in the desulfurization products of sulfur-rich nonpolar macromolecular fractions (NPMF) isolated from two crude oils and a sediment extract. These macromolecularly bound oxygenated compounds have been investigated in detail. Released straight chain components may have a hydroxy functionality at any position of the carbon skeleton and without any isomer predominance. Furthermore, the carbon-number distributions are very similar for the different alcohol isomers in each case and resemble those of the aliphatic hydrocarbons released by desulfurization. Thus, released hydrocarbons and alcohols likely originate from common functionalized precursors, most probably from polyunsaturated lipids of biological origin. Furthermore, they may derive from polyunsaturated components formed by elimination reactions on functionalized precursors which incorporated oxygen in free or already bound form at an early stage of diagenesis. The presence of hydroxyl functionalities at every position in the carbon skeleton suggests that double bond isomerization probably occurred in linear components prior to oxygen incorporation. Similarly, 2-hydroxy stanols released by desulfurization most likely result from oxygen uptake into Δ 2-sterenes during diagenesis. The presence of mid-chain hydroxylated phytanols in the degradation products with OH-group mainly at the tertiary positions indicates that they result (at least partially) from oxygen incorporation into unsaturated phytane skeletons. Additional functionalities in the oxygenated substances, such as double bonds, aldehydes or allylic alcohols, may have served as substrates for reactions with sulfur species, resulting in sulfur-rich cross-linked macromolecular structures. The type of oxygen groups present in the macromolecules could be partially assigned by sequential chemical degradation experiments. The results indicate that free OH-functions are not abundant. Part of the oxygen is present as

  20. Cellular response to oxygen containing biomedical polymers modified by Ar and He implantation.

    PubMed

    Manso, M; Navas, C Rodríguez; Gilliland, D; Ruiz, P García; Rossi, F

    2007-09-01

    Ion beam modification is an attractive way to adapt the response of a biopolymer surface with the view to modifying cellular processes. In this work we performed Ar and He implantations into three oxygen-containing biomedical polymers: polycaprolactone (PCL), poly(ethylene glycol) (PEG) and poly(methyl methacrylate) (PMMA). An ion energy of 25keV was selected on the basis of singularities observed in simulated implantations. The implantations were carried out with fluences of 5x10(13) cm(-2) considering also the ion current density as a source of differentiated damage. The modification of the polymer structure and composition was assayed by Fourier transform infrared spectroscopy, which confirmed the selectivity of the ion current density in producing polymer film damage. Biomedical assays denoted lack of structural stability on the PMMA surfaces. Surface analysis of proteins adsorbed from fetal bovine serum on ion-beam-modified PEG were realized by quartz-crystal microbalance with dissipation, which supported the film stabilization and anti-fouling behaviour of the films. On the other hand, protein adsorption studies on micropatterned PCL surfaces were performed by time-of-flight secondary ion mass spectroscopy and revealed a clear enhancement of protein immobilization in ion-beam-modified areas. The response of human mesenchymal stem cells to the surfaces was observed to depend on the biopolymer characteristics, showing adhesion inhibition onto He-modified PEG and specially enhanced colonization onto He-irradiated PCL. PMID:17398171

  1. Flotation properties of some oxygen-containing compounds of the acyclic series

    SciTech Connect

    Shreider, E.M.; Para, S.F.; Galanov, M.E.; Trachik, T.L.; Lagutina, L.V.

    1981-01-01

    In the monatomic alcohols series, maximum flotation activity is reached at 6 to 8 carbon atoms in the radical. It was decided to investigate the reagent properties of some other substances containing hydroxyl radicals which have not previously been considered. Oxygen-containing compounds in the acyclic series were examined, including alcohols: I - ethanol, ethylene-glycol, glycerol, pentaerythrytol, D-mannitol; II - dulcitol, D-sorbitol, D-mannitol, xylitol; glycols - monoethyleneglycol, diethyleneglycol, triethyleneglycol, polyethyleneglycol; and ethanolamines - ethanolamine, triethanolamine. The flotation properties of the reagents were determined in a Mekhanobr laboratory flotation machine with a chamber volume of 1.5 liter and an impeller speed of 1800 rpm. The materials tested were the <1 mm size fractions from run-of-plant charge and slurry from the radial thickeners. The samples were first dried and averaged. The pulp density was 200 g/l. The reagent conditions were kept constant throughout (50% of the total added at the start of a test, 25% after 2 min and 25% after 4 min from the start). The reagent additions were 1.0 to 1.4 kg/ton. All of these compounds had a very weak flotation activity.

  2. Dwarf Galaxies in the Leo I Group: the Group Luminosity Function beyond the Local Group (Oral Contribution)

    NASA Astrophysics Data System (ADS)

    Flint, K.; Bolte, M.; Mendes de Oliveira, C.

    We present first results of a survey of the Leo I group at 10 Mpc for M_R < -10 dwarf galaxies. This is part of a larger program to measure the faint end of the galaxy luminosity function in nearby poor groups. Our method is optimized to find Local-Group-like dwarfs down to dwarf spheroidal surface brightnesses, but we also find very large LSB dwarfs in Leo I with no Local Group counterpart. A preliminary measurement of the luminosity function yields a slope consistent with that measured in the Local Group.

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

    ERIC Educational Resources Information Center

    Hoekstra, Renee

    2008-01-01

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

  4. Detection of Differential Item Functioning in Multiple Groups.

    ERIC Educational Resources Information Center

    Kim, Seock-Ho; And Others

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

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

    NASA Astrophysics Data System (ADS)

    Nakayama, Yu

    2015-06-01

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

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

    ERIC Educational Resources Information Center

    Sari, Halil Ibrahim; Huggins, Anne Corinne

    2015-01-01

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

  7. Using Text Analysis to Identify Functionally Coherent Gene Groups

    PubMed Central

    Raychaudhuri, Soumya; Schütze, Hinrich; Altman, Russ B.

    2002-01-01

    The analysis of large-scale genomic information (such as sequence data or expression patterns) frequently involves grouping genes on the basis of common experimental features. Often, as with gene expression clustering, there are too many groups to easily identify the functionally relevant ones. One valuable source of information about gene function is the published literature. We present a method, neighbor divergence, for assessing whether the genes within a group share a common biological function based on their associated scientific literature. The method uses statistical natural language processing techniques to interpret biological text. It requires only a corpus of documents relevant to the genes being studied (e.g., all genes in an organism) and an index connecting the documents to appropriate genes. Given a group of genes, neighbor divergence assigns a numerical score indicating how “functionally coherent” the gene group is from the perspective of the published literature. We evaluate our method by testing its ability to distinguish 19 known functional gene groups from 1900 randomly assembled groups. Neighbor divergence achieves 79% sensitivity at 100% specificity, comparing favorably to other tested methods. We also apply neighbor divergence to previously published gene expression clusters to assess its ability to recognize gene groups that had been manually identified as representative of a common function. PMID:12368251

  8. Electron scattering cross sections for the modelling of oxygen-containing plasmas

    NASA Astrophysics Data System (ADS)

    Lemos Alves, Luís; Coche, Philippe; Ridenti, Marco Antonio; Guerra, Vasco

    2016-05-01

    This work proposes a set of electron scattering cross sections for molecular and atomic oxygen, with interest for the modelling of oxygen-containing plasmas. These cross sections, compiled for kinetic energies up to 1 keV, are part of the IST-LISBON database with LXCat, being used as input data to the LoKI (LisbOn KInetics) numerical code. The cross sections for ground-state molecular oxygen describe elastic and inelastic collision mechanisms, the latter including rotational excitations/de-excitations (treated using either a discrete or a continuous approach), vibrational and electronic excitations (including dissociation), dissociative attachment and ionisation. This set yields calculated swarm parameters that reproduce measurements within 5-20% (transport parameters) and within a factor of 2 difference (Townsend coefficients), for reduced electric fields in the range 10-3-103 Td. The cross sections describing the kinetics of atomic oxygen by electron-impact comprise elastic mechanisms, electronic excitation and ionisation from O(3P) ground-state, dissociation of O2(X,a,b) (including dissociative ionisation and attachment) and of O3, and detachment. These cross sections are indirectly validated, together with other elementary data for oxygen, by comparing the densities of O((4S0)3p 5P) obtained from the self-consistent modelling and from calibrated optical emission spectroscopy diagnostics of microwave-sustained micro-plasmas in dry air (80% N2: 20% O2), produced using a surface-wave excitation (2.45 GHz frequency) within a small radius capillary (R = 345 μm) at low pressure (p = 300 Pa). The calculated densities are in good qualitative agreement with measurements, overestimating them by a factor ˜1.5. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  9. Electron scattering cross sections for the modelling of oxygen-containing plasmas*

    NASA Astrophysics Data System (ADS)

    Alves, Luís Lemos; Coche, Philippe; Ridenti, Marco Antonio; Guerra, Vasco

    2016-06-01

    This work proposes a set of electron scattering cross sections for molecular and atomic oxygen, with interest for the modelling of oxygen-containing plasmas. These cross sections, compiled for kinetic energies up to 1 keV, are part of the IST-LISBON database with LXCat, being used as input data to the LoKI (LisbOn KInetics) numerical code. The cross sections for ground-state molecular oxygen describe elastic and inelastic collision mechanisms, the latter including rotational excitations/de-excitations (treated using either a discrete or a continuous approach), vibrational and electronic excitations (including dissociation), dissociative attachment and ionisation. This set yields calculated swarm parameters that reproduce measurements within 5-20% (transport parameters) and within a factor of 2 difference (Townsend coefficients), for reduced electric fields in the range 10-3-103 Td. The cross sections describing the kinetics of atomic oxygen by electron-impact comprise elastic mechanisms, electronic excitation and ionisation from O(3P) ground-state, dissociation of O2(X,a,b) (including dissociative ionisation and attachment) and of O3, and detachment. These cross sections are indirectly validated, together with other elementary data for oxygen, by comparing the densities of O((4S0)3 p 5P) obtained from the self-consistent modelling and from calibrated optical emission spectroscopy diagnostics of microwave-sustained micro-plasmas in dry air (80% N2: 20% O2), produced using a surface-wave excitation (2.45 GHz frequency) within a small radius capillary ( R = 345 μm) at low pressure ( p = 300 Pa). The calculated densities are in good qualitative agreement with measurements, overestimating them by a factor ˜1.5.

  10. Analysis of polycyclic aromatic hydrocarbons and their oxygen-containing derivatives and metabolites in soils.

    PubMed

    Bandowe, Benjamin A Musa; Wilcke, Wolfgang

    2010-01-01

    Although polycyclic aromatic hydrocarbons (PAHs) have been extensively studied, the knowledge of their oxygen-containing derivatives and metabolites (OPAHs) in soils is limited. We modified and tested an existing analytical protocol involving pressurized liquid extraction of soil followed by fractionation of target compounds into PAHs and OPAHs on a silica gel column and gas chromatography/ mass spectrometry-based separation and quantification. Polycyclic aromatic hydrocarbons and carbonyl-OPAHs were quantified directly after separation on silica gel columns, and hydroxyl/carboxyl-OPAHs were quantified after silylation with N,O-bis(trimethylsilyl)trifluoroacetamide. Recoveries between 78 and 97% (relative standard deviation [RSD], 5-12%) were obtained for six carbonyl-OPAHs, whereas 1,2-acenaphthenequinone and 1,4-naphthoquinone showed lower recoveries of 34 and 44% (RSD, 19 and 28%, respectively). Five hydroxyl/carboxyl-OPAHs had recoveries between 36 and 70% (RSD, 13-46%), six others had between 2 and 7% (RSD, 8-25%), and nine were lost in sample preparation. Limits of detection ranged from 0.1 to 1.6 ng g(-1) for OPAHs and from 0.01 to 0.56 ng g(-1) for PAHs. The protocol was applied to soils from a former gasworks site, Berlin, an urban soil from Mainz, both in Germany, and a forest soil from near Manaus, Brazil. The sums of 34 PAH concentrations were 107,000, 3505, and 21 ng g(-1); those of seven carbonyl-OPAHs were 15,690, 170, and 7 ng g(-1); and those of 11 hydroxyl/carboxyl-OPAHs 518, 36, and 16 ng g(-1) for Berlin, Mainz, and Manaus soils, respectively. Several OPAHs were present at concentrations higher than or equal to their parent PAHs, demonstrating the importance of OPAH measurement for the assessment of PAH-related environmental risks. PMID:20830923

  11. Recent advances in hydrotreating of pyrolysis bio-oil and its oxygen-containing model compounds

    SciTech Connect

    Wang, Huamin; Male, Jonathan L.; Wang, Yong

    2013-05-01

    There is considerable world-wide interest in discovering renewable sources of energy that can substitute for fossil fuels. Lignocellulosic biomass, which is the most abundant and inexpensive renewable feedstock on the planet, has a great potential for sustainable production of fuels, chemicals, and carbon-based materials. Fast pyrolysis integrated with hydrotreating is one of the simplest, most cost-effective and most efficient processes to convert lignocellulosic biomass to liquid hydrocarbon fuels for transportation, which has attracted significant attention in recent decades. However, effective hydrotreating of pyrolysis bio-oil presents a daunting challenge to the commercialization of biomass conversion via pyrolysis-hydrotreating. Specifically, development of active, selective, and stable hydrotreating catalysts is the bottleneck due to the poor quality of pyrolysis bio-oil feedstock (high oxygen content, molecular complexity, coking propensity, and corrosiveness). Significant research has been conducted to address the practical issues and provide the fundamental understanding of the hydrotreating/hydrodeoxygenation (HDO) of bio-oils and their oxygen-containing model compounds, including phenolics, furans, and carboxylic acids. A wide range of catalysts have been studied, including conventional Mo-based sulfide catalysts and noble metal catalysts, with the latter being the primary focus of the recent research because of their excellent catalytic performances and no requirement of environmentally unfriendly sulfur. The reaction mechanisms of HDO of model compounds on noble metal catalysts as well as their efficacy for hydrotreating or stabilization of bio-oil have been recently reported. This review provides a survey of the relevant literatures of recent 10 years about the advances in the understanding of the HDO chemistry of bio-oils and their model compounds mainly on noble metal catalysts.

  12. Single or functionalized fullerenes interacting with heme group

    NASA Astrophysics Data System (ADS)

    Costa, Wallison Chaves; Diniz, Eduardo Moraes

    2014-09-01

    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 C60 fullerene or with C60 functionalized with small functional groups (-CH3, -COOH, -NH2, -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.

  13. The luminosity function of galaxies in compact groups

    NASA Technical Reports Server (NTRS)

    Ribeiro, A. L. B.; De Carvalho, R. R.; Zepf, S. E.

    1994-01-01

    We use counts of faint galaxies in the regions of compact groups to extend the study of the luminosity function of galaxies in compact groups to absolute magnitudes as faint as M(sub B) = -14.5 + 5 log h. We find a slope of the faint end of the luminosity function of approximately alpha = -0.8, with a formal uncertainty of 0.15. This slope is not significantly different from that found for galaxies in other environments. Our results do not support previous suggestions of a dramatic underabundance of intrinsically faint galaxies in compact groups, which were based on extrapolations from fits at brighter magnitudes. The normal faint-end slope of the luminosity function in compact groups is in agreement with previous evidence that most galaxies in compact groups have not been dramatically affected by recent merging.

  14. Functional Group and Substructure Searching as a Tool in Metabolomics

    PubMed Central

    Kotera, Masaaki; McDonald, Andrew G.; Boyce, Sinéad; Tipton, Keith F.

    2008-01-01

    Background A direct link between the names and structures of compounds and the functional groups contained within them is important, not only because biochemists frequently rely on literature that uses a free-text format to describe functional groups, but also because metabolic models depend upon the connections between enzymes and substrates being known and appropriately stored in databases. Methodology We have developed a database named “Biochemical Substructure Search Catalogue” (BiSSCat), which contains 489 functional groups, >200,000 compounds and >1,000,000 different computationally constructed substructures, to allow identification of chemical compounds of biological interest. Conclusions This database and its associated web-based search program (http://bisscat.org/) can be used to find compounds containing selected combinations of substructures and functional groups. It can be used to determine possible additional substrates for known enzymes and for putative enzymes found in genome projects. Its applications to enzyme inhibitor design are also discussed. PMID:18253485

  15. Using the Group Presentation to Foster Functional Skills.

    ERIC Educational Resources Information Center

    King, Kim M.

    1990-01-01

    Suggests using group presentations as a method for instructors with large introductory courses to help students gain functional skills and also make the courses more interesting. Provides examples of group presentation projects. States goals of projects as showing how sociology can be used in everyday life and providing a review of the examination…

  16. Implement the medical group revenue function. Create competitive advantage.

    PubMed

    Colucci, C

    1998-01-01

    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

  17. [Macrozoobenthos functional groups in intertidal flat of northwest Jiaozhou Bay].

    PubMed

    Xin, Jun-hong; Ren, Yi-ping; Xu, Bin-duo; Zhang, Chong-liang; Xue, Ying; Ji, Yu-peng

    2011-07-01

    Based on the survey of macrozoobenthos at 35 locations of 7 sections in the intertidal flat of northwest Jiaozhou Bay in February, May, August, and November 2009, three zones including high tidal zone (A), mid tidal zone (B, C, and D), and low tidal zone (E) were selected to study the functional groups of macrozoobenthos in the flat. A total of 71 macrozoobenthos species were recorded, most of which were of mollusk (31 species), polychaete (20 species), and crustacean (14 species). The species number in A, B, C, D, and E was 26, 33, 35, 38, and 31, respectively. According to their food preferences, the macrozoobenthos were classified into 4 functional groups, i. e., planktonphagous, carnivorous, omnivorous, and detritivorous. The percentage of the species number of each functional group in the total species number of macrozoobenthos was in the order of carnivorous > planktophagous > detritivorous > omnivorous. Carnivorous group had the highest species diversity index, while omnivorous group had the lowest one. Overall, the species richness index, evenness index, and species diversity index were higher in mid tidal zone and lower in high and low tidal zones. The present study showed that the distribution of macrozoobenthos functional groups varied with the environment of tidal zones, being an integrative reflection of their habitat conditions. PMID:22007469

  18. N-doped structures and surface functional groups of reduced graphene oxide and their effect on the electrochemical performance of supercapacitor with organic electrolyte

    NASA Astrophysics Data System (ADS)

    Li, Shin-Ming; Yang, Shin-Yi; Wang, Yu-Sheng; Tsai, Hsiu-Ping; Tien, Hsi-Wen; Hsiao, Sheng-Tsung; Liao, Wei-Hao; Chang, Chien-Liang; Ma, Chen-Chi M.; Hu, Chi-Chang

    2015-03-01

    Nitrogen-doped reduced graphene oxide (N-rGO) has been synthesized using a simple, efficient method combining instant thermal exfoliation and covalent bond transformation from a melamine-graphene oxide mixture. The capacitive performance of N-rGO has been tested in both aqueous (0.5 M H2SO4) and organic (1 M tetraethyl-ammonium tetrafluoroborate (TEABF4) in propylene carbonate (PC)) electrolytes, which are compared with those obtained from thermal-reduced graphene oxide (T-rGO) and chemical-reduced graphene oxide (C-rGO). The contributions of scan-rate-independent (double-layer-like) and scan-rate-dependent (pseudo-capacitance-like) capacitance of all reduced graphene oxides in both aqueous and organic electrolytes were evaluated and compared. The results show that relatively rich oxygen-containing functional groups on C-rGO form significant ion-diffusion barrier, resulting in worse electrochemical responses in organic electrolyte. By contrast, the N-doped structures, large surface area, and lower density of oxygen-containing groups make N-rGO become a promising electrode material for organic electric double-layer capacitors (EDLCs). The capacitance rate-retention of N-rGO reaches 71.1% in 1 M TEABF4/PC electrolyte when the scan rate is elevated to 200 mVs-1, demonstrating that N-rGO improves the relatively low-power drawback of EDLCs in organic electrolytes. The specific energy and power of a symmetric N-rGO cell in the organic electrolyte reach 25 Wh kg-1 and 10 kW kg-1, respectively.

  19. Single or functionalized fullerenes interacting with heme group

    SciTech Connect

    Costa, Wallison Chaves; Diniz, Eduardo Moraes

    2014-09-15

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

  20. The carbon functional group budget of a peatland

    NASA Astrophysics Data System (ADS)

    Moody, Catherine; Worrall, Fred; Clay, Gareth; Apperley, David

    2016-04-01

    Organic matter samples were taken from each organic matter reservoir and fluvial flux found in a peatland and analysed by elemental analysis for carbon, hydrogen, nitrogen and oxygen content, and by 13C solid state nuclear magnetic resonance (NMR) for functional group composition. The samples analysed were: aboveground, belowground, heather, mosses and sedges, litter layer, four different depths from a peat core, and monthly samples of fluvial particulate and dissolved organic matter. All organic matter samples were taken from a 100% peat catchment within Moor House National Nature Reserve in the North Pennines, UK. The proportion of carbon atoms from each of the eight carbon functional groups (C-alkyl, N-alkyl/methoxyl C, O-alkyl, O2-alkyl/acetal C, aromatic/unsaturated C, phenolic C, aldehyde/ketone C and amide/carboxyl C) from each type of organic matter were combined with an existing carbon budget from the same site, to give a functional group carbon budget. The budget results show that the ecosystem is accumulating N-alkyl/methoxyl C, O-alkyl, O2-alkyl/acetal C and phenolic C groups, but losing C-alkyl, aromatic/unsaturated C, amide/carboxyl C and aldehyde/ketone C. Comparing the functional group compositions between the sampled organic matter pools shows that DOM arises from two distinct sources; from the peat itself and from a vegetation source.

  1. Functionalization of carbon nanotube by carboxyl group under radial deformation

    NASA Astrophysics Data System (ADS)

    Lara, Ivi Valentini; Zanella, Ivana; Fagan, Solange Binotto

    2014-01-01

    The dependence of the structural and the electronic properties of functionalized (5, 5) single-walled carbon nanotubes (SWNT) were investigated through ab initio density functional simulations when the carboxyl group is bonded on the flatter or curved regions. Radial deformations result in diameter decrease of up to 20 per cent of the original size, which was the limit reduction that maintains the SWNT functionalized structure. Changes on the electronic structure were observed due to the symmetry break of the SWNT caused by both the carboxyl group and the C-C bond distortions resulted by the radial deformation. It is observed that the functionalization process is specially favored by the sp3 hybridization induced on the more curved region of the deformed SWNT.

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

    USGS Publications Warehouse

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

    2012-01-01

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

  3. Chapter 8. Resident Group Influences on Team Functioning

    ERIC Educational Resources Information Center

    Burford, Gale E.; Fulcher, Leon C.

    2006-01-01

    Research has documented important interplays between the diagnostic characteristics of residents in group care centers and the functioning of staff teams responsible for the delivery of services. Factors that impact on the quality of working life satisfactions and frustrations are variable over time and may originate from within the team, the…

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

    PubMed Central

    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

    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

  5. Oxide scales formed on Fe-Cr-Al-based model alloys exposed to oxygen containing molten lead

    NASA Astrophysics Data System (ADS)

    Weisenburger, A.; Jianu, A.; Doyle, S.; Bruns, M.; Fetzer, R.; Heinzel, A.; DelGiacco, M.; An, W.; Müller, G.

    2013-06-01

    Based on the state of the art oxide maps concerning oxidation behavior of Fe-Cr-Al model alloys at 800 and 1000 °C in oxygen atmosphere, ten compositions, belonging to this alloy system, were designed in order to tap the borders of the alumina stability domain, during their exposure to oxygen (10-6 wt.%) containing lead, at 400, 500 and 600 °C. Eight alloys, Fe-6Cr-6Al, Fe-8Cr-6Al, Fe-10Cr-5Al, Fe-14Cr-4Al, Fe-16Cr-4Al, Fe-6Cr-8Al, Fe-10Cr-7Al and Fe-12Cr-5Al, were found to be protected against corrosion in oxygen containing lead, either by a duplex layer (Fe3O4 + (Fe1-x-yCrxAly)3O4) or by (Fe1-x-yCrxAly)3O4, depending on the temperature at which they were exposed. Two alloys namely Fe-12Cr-7Al and Fe-16Cr-6Al were found to form transient aluminas, κ-Al2O3 (at 400 and 500 °C) and θ-Al2O3 (at 600 °C), as protective oxide scale against corrosion in oxygen containing lead. An oxide map illustrating the stability domain of alumina, grown on Fe-Cr-Al alloys when exposed to molten, oxygen containing lead, was drawn. The map includes also additional points, extracted from literature and corresponding to alumina forming alloys, when exposed to HLMs, which fit very well with our findings. Chromium and aluminium contents of 12.5-17 wt.% and 6-7.5 wt.%, respectively, are high enough to obtain thin, stable and protective alumina scales on Fe-Cr-Al-based alloys exposed to oxygen containing lead at 400, 500 and 600 °C. For the temperature range and exposure times used during the current evaluation, the growth rate of the alumina scale was low. No area with detached scale was observed and no trace of α-Al2O3 was detected.

  6. Computing the effective action with the functional renormalization group

    NASA Astrophysics Data System (ADS)

    Codello, Alessandro; Percacci, Roberto; Rachwał, Lesław; Tonero, Alberto

    2016-04-01

    The "exact" or "functional" renormalization group equation describes the renormalization group flow of the effective average action Γ _k. The ordinary effective action Γ _0 can be obtained by integrating the flow equation from an ultraviolet scale k=Λ down to k=0. We give several examples of such calculations at one-loop, both in renormalizable and in effective field theories. We reproduce the four-point scattering amplitude in the case of a real scalar field theory with quartic potential and in the case of the pion chiral Lagrangian. In the case of gauge theories, we reproduce the vacuum polarization of QED and of Yang-Mills theory. We also compute the two-point functions for scalars and gravitons in the effective field theory of scalar fields minimally coupled to gravity.

  7. Properties of graphene inks stabilized by different functional groups.

    PubMed

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

    2011-06-17

    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 applied to have a detailed study of the properties of the inks. It is found that graphenes modified by p-type polyaniline show the highest surface tension. Diverse surface adhesive properties to the substrate are also found with various functional groups. The different viscoelasticities of graphene inks were related to the microscopic structure of their coating layer and subsequently related to the configuration, chemistry and molecular dimensions of the modifying molecules to establish the property-structure relationship. Modifications of graphene inks made from chemical reduction cannot only enable cost-effective processing for printable electronics but also extend the applications into, for example, self-assembly of graphene via bottom-up nano-architecture and surface energy engineering of the graphenes. To fabricate useful devices, understanding the surface properties of graphene inks is very important. It is the first paper of this kind to study the surface tension and adhesion of graphene influenced by different functional groups. PMID:21508455

  8. Properties of graphene inks stabilized by different functional groups

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    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 applied to have a detailed study of the properties of the inks. It is found that graphenes modified by p-type polyaniline show the highest surface tension. Diverse surface adhesive properties to the substrate are also found with various functional groups. The different viscoelasticities of graphene inks were related to the microscopic structure of their coating layer and subsequently related to the configuration, chemistry and molecular dimensions of the modifying molecules to establish the property-structure relationship. Modifications of graphene inks made from chemical reduction cannot only enable cost-effective processing for printable electronics but also extend the applications into, for example, self-assembly of graphene via bottom-up nano-architecture and surface energy engineering of the graphenes. To fabricate useful devices, understanding the surface properties of graphene inks is very important. It is the first paper of this kind to study the surface tension and adhesion of graphene influenced by different functional groups.

  9. Functional renormalization group analysis of tensorial group field theories on Rd

    NASA Astrophysics Data System (ADS)

    Geloun, Joseph Ben; Martini, Riccardo; Oriti, Daniele

    2016-07-01

    Rank-d tensorial group field theories are quantum field theories (QFTs) defined on a group manifold G×d , which represent a nonlocal generalization of standard QFT and a candidate formalism for quantum gravity, since, when endowed with appropriate data, they can be interpreted as defining a field theoretic description of the fundamental building blocks of quantum spacetime. Their renormalization analysis is crucial both for establishing their consistency as quantum field theories and for studying the emergence of continuum spacetime and geometry from them. In this paper, we study the renormalization group flow of two simple classes of tensorial group field theories (TGFTs), defined for the group G =R for arbitrary rank, both without and with gauge invariance conditions, by means of functional renormalization group techniques. The issue of IR divergences is tackled by the definition of a proper thermodynamic limit for TGFTs. We map the phase diagram of such models, in a simple truncation, and identify both UV and IR fixed points of the RG flow. Encouragingly, for all the models we study, we find evidence for the existence of a phase transition of condensation type.

  10. Functional renormalization group approach for tensorial group field theory: a rank-6 model with closure constraint

    NASA Astrophysics Data System (ADS)

    Benedetti, Dario; Lahoche, Vincent

    2016-05-01

    We develop the functional renormalization group formalism for a tensorial group field theory with closure constraint, in the case of a just renormalizable model over U{(1)}\\otimes 6, with quartic interactions. The method allows us to obtain a closed but non-autonomous system of differential equations which describe the renormalization group flow of the couplings beyond perturbation theory. The explicit dependence of the beta functions on the running scale is due to the existence of an external scale in the model, the radius of {S}1≃ U(1). We study the occurrence of fixed points and their critical properties in two different approximate regimes, corresponding to the deep UV and deep IR. Besides confirming the asymptotic freedom of the model, we find also a non-trivial fixed point, with one relevant direction. Our results are qualitatively similar to those found previously for a rank-3 model without closure constraint, and it is thus tempting to speculate that the presence of a Wilson-Fisher-like fixed point is a general feature of asymptotically free tensorial group field theories.

  11. Experimental study of the thermal stability of materials in high temperature oxygen-containing media

    NASA Technical Reports Server (NTRS)

    Abaltusov, Y. Y.; Bagramyan, A. R.; Grishin, A. M.; Yukhvid, V. I.

    1986-01-01

    An experimental study is made of the interaction of several materials with a high temperature medium containing oxygen. The temperature of the surface was measured as a function of time. It is found that the higher the velocity of mass removal from the surface, the more effective is the material from the viewpoint of heat resistance.

  12. Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations

    NASA Astrophysics Data System (ADS)

    Ebling, A. M.; Schijf, J.

    2008-12-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    In this paper, we review the state of the art and major challenges in current efforts to incorporate biogeochemical functional groups into models that can be applied on basin-wide and global scales, with an emphasis on models that might ultimately be used to predict how biogeochemical cycles in the ocean will respond to global warming. We define the term "biogeochemical functional group" to refer to groups of organisms that mediate specific chemical reactions in the ocean. Thus, according to this definition, "functional groups" have no phylogenetic meaning—these are composed of many different species with common biogeochemical functions. Substantial progress has been made in the last decade toward quantifying the rates of these various functions and understanding the factors that control them. For some of these groups, we have developed fairly sophisticated models that incorporate this understanding, e.g. for diazotrophs (e.g. Trichodesmium), silica producers (diatoms) and calcifiers (e.g. coccolithophorids and specifically Emiliania huxleyi). However, current representations of nitrogen fixation and calcification are incomplete, i.e., based primarily upon models of Trichodesmium and E. huxleyi, respectively, and many important functional groups have not yet been considered in open-ocean biogeochemical models. Progress has been made over the last decade in efforts to simulate dimethylsulfide (DMS) production and cycling (i.e., by dinoflagellates and prymnesiophytes) and denitrification, but these efforts are still in their infancy, and many significant problems remain. One obvious gap is that virtually all functional group modeling efforts have focused on autotrophic microbes, while higher trophic levels have been completely ignored. It appears that in some cases (e.g., calcification), incorporating higher trophic levels may be essential not only for representing a particular biogeochemical reaction, but also for modeling export. Another serious problem is our

  14. Molecular dynamics simulations of functionalized carbon nanotubes in water: Effects of type and position of functional groups

    NASA Astrophysics Data System (ADS)

    Foroutan, Masumeh; Moshari, Mahshad

    2010-11-01

    In this work the behavior of the (8,2) single walled carbon nanotubes (CNTs) and functionalized carbon nanotubes (FCNTs) with four functional groups in water were studied using molecular dynamic (MD) simulation method. Glutamine as a long chain functional group and carboxyl as a short chain functional group have been used as functional groups in FCNTs. Four functional groups in each FCNT were localized at two positions: (i) all four functional groups were in the sidewalls of nanotube, (ii) two functional groups were at the ends and two functional groups were in the sidewalls of nanotube. The intermolecular interaction energies between CNTs or FCNTs and water molecules, the plots of radial distribution function and the diffusion coefficients of CNTs and FCNTs in water were computed for investigating the effects of type and position of functional groups on the behavior of FCNTs in water. The obtained results from three methods are consistent with each others. Results showed that the position of the functional groups in FCNTs has an important role in the interaction of hydrophilic groups of FCNTs with water molecules. Furthermore we also investigated the behavior of FCNTs with sixteen carboxyl functional groups in water. The presence of these large numbers of carboxyl functional groups on the carbon nanotubes prevents water molecules from moving towards hydrophilic carboxyl functional groups. This demonstrates the advantage of using lower number of functional groups each containing many hydrophilic groups like glutamine functional group.

  15. Oxidation and microstrucure of V-Cr-Ti alloys exposed to oxygen-containing environments

    SciTech Connect

    Natesan, K.; Uz, M.; Ulie, T.

    1997-08-01

    The objectives of this task are to (a) evaluate the oxygen uptake of several V-Cr-Ti alloys as a function of temperature and oxygen partial pressure in the exposure environment, (b) examine the microstructural characteristics of oxide scales and oxygen trapped at the grain boundaries in the substrate alloys, and (c) evaluate the influence of alloy composition on oxygen uptake and develop correlation(s) between alloy composition, exposure environment, and temperature.

  16. Organized thiol functional groups in mesoporous core shell colloids

    SciTech Connect

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

    2012-03-15

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

  17. FTIR Analysis of Functional Groups in Aerosol Particles

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  18. Along the Ta Diffusion Path Through a Boron and Oxygen Containing Tri-layer Structure

    NASA Astrophysics Data System (ADS)

    Ying, Ji-Feng; Ji, Rong; Wang, Chen Chen; Ter Lim, Sze; Xie, Huiqing; Gerard, Ernult F.

    2014-08-01

    Diffusion and migration of elements are commonly observed in the fabrication of multilayer thin-film devices, including those of STT-RAM. The CoFeB/MgO/CoFeB tri-layer thin-film stack has been widely used in the design of STT-RAM devices as the functional magnetic-tunnel-junction (MTJ) structure. Such issues faced in the fabrication of these devices have been extensively researched from the stand point of engineering the materials property and structure to achieve the best MTJ performance. In this work, we conducted a detailed examination of the chemical-state change of the Ta and B in a CoFeB/MgO/CoFeB/Ta film stack by using x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry. We showed that the chemical-state change of Ta and B is a result of the Ta diffusion phenomena through the CoFeB/MgO/CoFeB tri-layer structure. In particular, we report the evidences of the formation of TaB x O y compound at some considerable depth away from the Ta layer. Also of value to XPS spectroscopy, the Ta binding energy for such TaB x O y compound is reported for the first time.

  19. Electronic spectra of oxygen containing polycyclic hydrocarbon cations and the protonated analogues.

    PubMed

    Chakraborty, Arghya; Fulara, Jan; Maier, John P

    2015-08-28

    The electronic transitions of 9-fluorenone FL(+) and 2,3,6,7-dibenzotropone DBT(+) cations were detected in 6 K neon matrices following a mass-selective deposition. The absorptions at 649.2 and 472.2 nm are assigned to the 2 (2)B1←X̃(2)A2 FL(+) and 2(2)A(')←X̃(2)A(') DBT(+) transitions. Absorption spectra of protonated 9-fluorenone H(+)-FL and 2,3,6,7-dibenzotropone H(+)-DBT have also been measured. Protonation of the oxygenated polycyclic aromatic hydrocarbons is carried out in a hot cathode source via in situ produced protonated ethanol. Vibrationally resolved absorptions commencing at 423.3 nm of H-FL(+) and two band systems of H-DBT(+) with origins at 502.4 and 371.5 nm are assigned to the 2(1)A(')←X̃(1)A(') electronic transition of 9-hydroxy-fluorenyl cation and 1 (1)A←X̃(1)A, 2 (1)A←X̃(1)A of 2,3,6,7-dibenzocycloheptenol cation. The assignments are based on vertical excitation energy calculations with time dependent density functional theory, symmetry adapted cluster configuration interaction, and MS-CASPT2 methods. PMID:26328848

  20. Individual Functional ROI Optimization via Maximization of Group-wise Consistency of Structural and Functional Profiles

    PubMed Central

    Li, Kaiming; Guo, Lei; Zhu, Dajiang; Hu, Xintao; Han, Junwei; Liu, Tianming

    2013-01-01

    Studying connectivities among functional brain regions and the functional dynamics on brain networks has drawn increasing interest. A fundamental issue that affects functional connectivity and dynamics studies is how to determine the best possible functional brain regions or ROIs (regions of interest) for a group of individuals, since the connectivity measurements are heavily dependent on ROI locations. Essentially, identification of accurate, reliable and consistent corresponding ROIs is challenging due to the unclear boundaries between brain regions, variability across individuals, and nonlinearity of the ROIs. In response to these challenges, this paper presents a novel methodology to computationally optimize ROIs locations derived from task-based fMRI data for individuals so that the optimized ROIs are more consistent, reproducible and predictable across brains. Our computational strategy is to formulate the individual ROI location optimization as a group variance minimization problem, in which group-wise consistencies in functional/structural connectivity patterns and anatomic profiles are defined as optimization constraints. Our experimental results from multimodal fMRI and DTI data show that the optimized ROIs have significantly improved consistency in structural and functional profiles across individuals. These improved functional ROIs with better consistency could contribute to further study of functional interaction and dynamics in the human brain. PMID:22281931

  1. Difference in nutritional risk between mild cognitive impairment group and normal cognitive function elderly group.

    PubMed

    Lee, Kang Soo; Hong, Chang Hyung; Cheong, Hae-Kwan; Oh, Byoung Hoon

    2009-01-01

    The purpose of this study was to delineate the difference in nutritional risk between mild cognitive impairment (MCI) groups and normal cognitive function (NCF) elderly groups in the community. Data obtained from 490 subjects (237 NCF elderly and 253 MCI subjects) between 60 and 90 years of age were analyzed. The study protocol comprised demographic characteristics, history of current and past illnesses, drug history, Korean version of short-form Geriatric Depression Scale (K-SGDS), and nutritional screening initiative (NSI) checklist. Cognitive function was assessed by digit span, Korean short version of Boston naming test (K-BNT), simple Rey figure test, auditory verbal learning test (AVLT), controlled oral word association test (COWAT), stroop, go-no go, and contrasting program. Also, we examined the blood pressure, fasting serum glucose level, lipid profile, body mass index (BMI), and ApoE genotype. Multiple logistic regression analysis found that MCI was associated with moderate or high nutritional risk after adjustment for age, sex, educational level, and K-SGDS score (odds ratio (OR)=1.13, 95%; confidence interval (CI)=1.01-1.26). These results suggest that MCI may be associated with nutritional risk. Screening for nutritional risk should be included in multidimensional geriatric evaluation. PMID:18524396

  2. Highlighting functional groups in self-assembled overlayers with specific functionalized scanning tunnelling microscopy tips

    NASA Astrophysics Data System (ADS)

    Volcke, Cedric; Simonis, Priscilla; Thiry, Paul A.; Lambin, Philippe; Culot, Christine; Humbert, Christophe

    2005-11-01

    Overlayers of a fatty acid (palmitic and lauric acid) formed at the interface between a solution of this molecule in phenyloctane and the basal plane of graphite are studied by in situ scanning tunnelling microscopy. The layers organize into lamellae, which are formed by a close packing arrangement of molecules parallel to the graphite surface. Chemical modification of the STM tips used allowed identification of the functional group. Indeed, the gold tips used are functionalized with 4-mercaptobenzoic acid (4-MBA) and 4-mercaptotoluene (4-MT). The same functional group on a sample is then 'seen' as a dark and a bright spot when imaged with 4-MBA and 4-MT modified tips, respectively. This contrast distinction is related to interactions (or a lack of them) between the carboxyl group on the sample and molecules on the tip, which can facilitate (or hinder) the electron tunnelling.

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

    NASA Astrophysics Data System (ADS)

    Balian, R.; Vénéroni, M.

    2015-11-01

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

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

    PubMed

    Friestad, Gregory K

    2012-01-01

    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 α-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

  5. Relative energies, structures, vibrational frequencies, and electronic spectra of pyrylium cation, an oxygen-containing carbocyclic ring isoelectronic with benzene, and its isomers

    NASA Astrophysics Data System (ADS)

    Bera, Partha P.; Head-Gordon, Martin; Lee, Timothy J.

    2013-11-01

    We have studied relative energies, structures, rotational, vibrational, and electronic spectra of the pyrylium cation, an oxygen-containing six-membered carbocyclic ring, and its six isomers, using ab initio quantum chemical methods. Isoelectronic with benzene, the pyrylium cation has a benzenoid structure and is the global minimum on the singlet potential energy surface of C5H5O+. The second lowest energy isomer, the furfuryl cation, has a five membered backbone akin to a sugar, and is only 16 kcal mol-1 above the global minimum computed using coupled cluster theory with singles, doubles, and perturbative triple excitations (CCSD(T)) with the correlation consistent cc-pVTZ basis set. Other isomers are 25, 26, 37, 60, and 65 kcal mol-1 above the global minimum, respectively, at the same level of theory. Lower level methods such as density functional theory (B3LYP) and second order Møller-Plesset perturbation theory performed well when tested against the CCSD(T) results. The pyrylium and furfuryl cations, although separated by only 16 kcal mol-1, are not easily interconverted, as multiple bonds must be broken and formed, and the existence of more than one transition state is likely. Additionally, we have also investigated the asymptotes for the barrierless ion-molecule association of molecules known to exist in the interstellar medium that may lead to formation of the pyrylium cation.

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

    PubMed

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

    2015-04-01

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

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

    PubMed

    Kim, Junghi; Pan, Wei

    2015-01-01

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

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

    PubMed Central

    Kim, Junghi; Pan, Wei

    2015-01-01

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

  9. The Formation of Oxygen-Containing Molecules in Liquid Water Environments on the Surface of Titan (Invited)

    NASA Astrophysics Data System (ADS)

    Neish, C.

    2010-12-01

    Saturn’s moon Titan represents a unique locale for studying prebiotic chemistry. Reactions occurring in its thick nitrogen - methane atmosphere produce a wide variety of organic molecules. Observations by the Voyager spacecraft found evidence for six gas-phase hydrocarbons and three nitriles, along with an enveloping haze layer shrouding the surface of the moon (Hanel et al., 1981; Kunde et al., 1981; Maguire et al., 1981). More recently, the INMS instrument on the Cassini spacecraft has found evidence for organic molecules up to its mass limit of 100 Da at altitudes as high as 1200 km (Waite et al., 2005; Vuitton et al. 2007). Laboratory experiments that simulate the reactions occurring in Titan’s atmosphere produce many of the same organic molecules observed by Voyager and Cassini, along with organic precipitates known as tholins. Tholins have the general formula CxHyNz and are spectrally similar to Titan’s haze (Khare et al., 1984). Though interesting from the point of view of organic chemistry, the molecules found in Titan’s atmosphere stop short of addressing questions related to the origins of life. Oxygen - a key element for most known biological molecules - is generally lacking in Titan’s atmosphere. The most abundant oxygenated molecule, CO, is present at only ~50 ppm (de Kok et al., 2007). However, if Titan’s atmospheric organic molecules mix with water found in cryovolcanic lavas or impact melts, they may react to produce oxygen-containing, prebiotic species. In this paper, I will show that reactions between Titan tholins and low temperature aqueous solutions produce a wide variety of oxygen-containing species. These reactions display first-order kinetic behaviour with half-lives between 0.4 to 7 days at 273 K (in water) and between 0.3 and 14 days at 253 K (in 13 wt. % ammonia-water). Tholin hydrolysis is thus very fast compared to the freezing timescales of impact melts and volcanic sites on Titan, which take hundreds to thousands of years

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  12. The Mechanism and Function of Group II Chaperonins.

    PubMed

    Lopez, Tom; Dalton, Kevin; Frydman, Judith

    2015-09-11

    Protein folding in the cell requires the assistance of enzymes collectively called chaperones. Among these, the chaperonins are 1-MDa ring-shaped oligomeric complexes that bind unfolded polypeptides and promote their folding within an isolated chamber in an ATP-dependent manner. Group II chaperonins, found in archaea and eukaryotes, contain a built-in lid that opens and closes over the central chamber. In eukaryotes, the chaperonin TRiC/CCT is hetero-oligomeric, consisting of two stacked rings of eight paralogous subunits each. TRiC facilitates folding of approximately 10% of the eukaryotic proteome, including many cytoskeletal components and cell cycle regulators. Folding of many cellular substrates of TRiC cannot be assisted by any other chaperone. A complete structural and mechanistic understanding of this highly conserved and essential chaperonin remains elusive. However, recent work is beginning to shed light on key aspects of chaperonin function and how their unique properties underlie their contribution to maintaining cellular proteostasis. PMID:25936650

  13. Functional renormalization group - a new approach to frustrated quantum magnetism

    NASA Astrophysics Data System (ADS)

    Reuther, Johannes

    The experimental and theoretical investigation of quantum spin systems has become one of the central disciplines of contemporary condensed matter physics. From an experimental viewpoint, the field has been significantly fueled by the recent synthesis of novel strongly correlated materials with exotic magnetic or quantum paramagnetic ground states. From a theoretical perspective, however, the numerical treatment of realistic models for quantum magnetism in two and three spatial dimensions still constitutes a serious challenge. This particularly applies to frustrated systems, which complicate the employment of established methods. This talk intends to propagate the pseudofermion functional renormalization group (PFFRG) as a novel approach to determine large size ground state correlations of a wide class of spin Hamiltonians. Using a diagrammatic pseudofermion representation for quantum spin models, the PFFRG performs systematic summations in all two-particle fermionic interaction channels, capturing the correct balance between classical magnetic ordering and quantum fluctuations. Numerical results for various frustrated spin models on different 2D and 3D lattices are reviewed, and benchmarked against other methods if available.

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

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Functional Classification-Operating... ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Profit and Loss Classification Section 11 Functional Classification—Operating Expenses of Group II and Group III Air Carriers 5100Flying Operations....

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

    PubMed Central

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

    2010-01-01

    Background Green roofs perform ecosystem services such as summer roof temperature reduction and stormwater capture that directly contribute to lower building energy use and potential economic savings. These services are in turn related to ecosystem functions performed by the vegetation layer such as radiation reflection and transpiration, but little work has examined the role of plant species composition and diversity in improving these functions. Methodology/Principal Findings We used a replicated modular extensive (shallow growing- medium) green roof system planted with monocultures or mixtures containing one, three or five life-forms, to quantify two ecosystem services: summer roof cooling and water capture. We also measured the related ecosystem properties/processes of albedo, evapotranspiration, and the mean and temporal variability of aboveground biomass over four months. Mixtures containing three or five life-form groups, simultaneously optimized several green roof ecosystem functions, outperforming monocultures and single life-form groups, but there was much variation in performance depending on which life-forms were present in the three life-form mixtures. Some mixtures outperformed the best monocultures for water capture, evapotranspiration, and an index combining both water capture and temperature reductions. Combinations of tall forbs, grasses and succulents simultaneously optimized a range of ecosystem performance measures, thus the main benefit of including all three groups was not to maximize any single process but to perform a variety of functions well. Conclusions/Significance Ecosystem services from green roofs can be improved by planting certain life-form groups in combination, directly contributing to climate change mitigation and adaptation strategies. The strong performance by certain mixtures of life-forms, especially tall forbs, grasses and succulents, warrants further investigation into niche complementarity or facilitation as mechanisms

  16. Effects of oxygen-containing terpenes as skin permeation enhancers on the lipoidal pathways of human epidermal membrane.

    PubMed

    Chantasart, Doungdaw; Pongjanyakul, Thaned; Higuchi, William I; Li, S Kevin

    2009-10-01

    The present study investigated the effects of oxygen-containing terpenes as skin permeation enhancers on the lipoidal pathways of human epidermal membrane (HEM). The enhancement (E(HEM)) effects of menthol, thymol, carvacrol, menthone, and cineole on the transport of a probe permeant, corticosterone, across HEM were determined. It was found that the enhancer potencies of menthol, thymol, carvacrol, and menthone were essentially the same and higher than that of cineole based on their aqueous concentration in the diffusion cell chamber at E(HEM) = 4. Thymol and carvacrol also had the same E(HEM) = 10 concentration further supporting that they had the same enhancer potency based on the aqueous concentration. The uptake amounts of terpene into the HEM stratum corneum (SC) intercellular lipid under the same conditions indicate that the intrinsic potencies of the studied terpenes are the same based on their concentration in the SC and similar to those of n-alkanol and n-alkylphenyl alcohol. Moreover, they are all better enhancers compared to branched-chain alkanol. The approximately same uptake enhancement of beta-estradiol induced by the studied terpenes and alcohols at E(HEM) conditions into the SC intercellular lipids suggests that the mechanism of enhancement action for the terpenes and those of alcohols are essentially the same. PMID:19156845

  17. Impact of Functional Group Modifications on Designer Phenethylamine Induced Hyperthermia.

    PubMed

    Grecco, Gregory G; Sprague, Jon E

    2016-05-16

    The popularity of designer phenethylamines such as synthetic cathinones ("bath salts") has led to increased reports of life-threatening hyperthermia. The diversity of chemical modifications has resulted in the toxicological profile of most synthetic cathinones being mostly uncharacterized. Here, we investigated the thermogenic effects of six recently identified designer phenethylamines (4-methylmethamphetamine, methylone, mephedrone, butylone, pentylone, and MDPV) and compared these effects to the established thermogenic agent 3,4-methylenedioxymethamphetamine (MDMA). Specifically, we determined the impact of a β-ketone, α-alkyl, or pyrrolidine functional group on core-body temperature changes. Sprague-Dawley rats (n = 5-6) were administered a dose (30 mg/kg, sc) of a designer phenethylamine or MDMA, and core body temperature measurements were recorded at 30 min intervals for 150 min post treatment. MDMA elicited the greatest maximum temperature change (ΔTmax), and this effect was significantly greater than that of its β-ketone analogue, methylone. Temperature-area under the curves (TAUCs) and ΔTmax were also significantly different between 4-methylmethamphetamine (4-MMA) and its β-ketone analogue mephedrone. Lengthening the α-alkyl chain of methylone to produce butylone and pentylone significantly attenuated the thermogenic response on both TAUCs and ΔTmax compared to those of methylone; however, butylone and pentylone were not different from each other. Pyrrolidine substitution on the N-terminus of pentylone produces 3,4-methylenedioxypyrovalerone (MDPV), which did not significantly alter core body temperature. Thermogenic comparisons of MDMA vs methylone and 4-MMA vs mephedrone indicate that oxidation at the benzylic position significantly attenuates the hyperthermic response. Furthermore, either extending the α-alkyl chain to ethyl and propyl (butylone and pentylone, respectively) or extending the α-alkyl chain and adding a pyrrolidine on the N

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

    PubMed

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

    2004-04-01

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

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

    ERIC Educational Resources Information Center

    Myers, Scott A.

    2012-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  1. Perceptual Visual Grouping under Inattention: Electrophysiological Functional Imaging

    ERIC Educational Resources Information Center

    Razpurker-Apfeld, Irene; Pratt, Hillel

    2008-01-01

    Two types of perceptual visual grouping, differing in complexity of shape formation, were examined under inattention. Fourteen participants performed a similarity judgment task concerning two successive briefly presented central targets surrounded by task-irrelevant simple and complex grouping patterns. Event-related potentials (ERPs) were…

  2. Moral Judgment as a Function of Peer Group Interaction

    ERIC Educational Resources Information Center

    Maitland, Karen A.; Goldman, Jacquelin R.

    1974-01-01

    This article presents an investigation into the effects of peer group interaction on moral judgment among 36 male and female eleventh and twelfth graders. The results indicate greater social conflict and pressure in a group discussion induces greater change in the level of moral judgment. (DE)

  3. Parent, Alkylated, and Sulfur/Oxygen-Containing Polycyclic Aromatic Hydrocarbons in Mainstream Smoke from 13 Brands of Chinese Cigarettes.

    PubMed

    Gao, Bo; Du, Xueqing; Wang, Xinming; Tang, Jianhui; Ding, Xiang; Zhang, Yanli; Bi, Xinhui; Zhang, Gan

    2015-08-01

    China has the world's largest population of smokers with serious health consequences, yet we know a very limited spectrum of hazardous chemicals in cigarette smoke even for carcinogenic polycyclic aromatic hydrocarbons (PAHs). Here, we chose 13 popular cigarette brands sold in China markets, collected particulate matters in mainstream smoke using filter pads and an automatic smoking machine, and analyzed 56 PAHs, including 31 parent, 18 alkylated, and 7 sulfur/oxygen-containing PAHs (S/O PAHs). The 56 PAHs in mainstream smoke totaled from 244.2 ± 28.5 to 10254.8 ± 481.5 ng cig(-1); parent, alkylated, and S/O PAHs shared 16-23%, 64-74%, and 6-18%, respectively. Benzo[a]pyrene (BaP) ranged 1.1-41.6 ng cig(-1), while BaP equivalent concentrations (BaPeq) ranged 3.6-120.2 ng cig(-1), but contributions to BaPeq by individual carcinogenic PAH species varied with cigarette brands. When these cigarette smoke source profiles were pooled together with those of other combustion ones available in the literature, we found that widely used diagnostic ratios of parent PAHs failed to distinguish cigarette smoke from other combustion sources, except that the ratio indeno[1,2,3-cd]pyrene/(indeno[1,2,3-cd]pyrene + benzo[g,h,i]perylene) can largely separate cigarette smoke from vehicular emissions and that the ratio of Retene/(Retene + chrysene) can further discriminate cigarette smoke from coal combustion when alkylated PAHs are involved. PMID:26119395

  4. Hydrolysis of organonitrate functional groups in aerosol particles

    SciTech Connect

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

    2012-10-19

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

  5. Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield

    SciTech Connect

    Vagin, Nikolai P; Ionin, Andrei A; Klimachev, Yu M; Kotkov, A A; Podmar'kov, Yu P; Seleznev, L V; Sinitsyn, D V; Frolov, M P; Yuryshev, Nikolai N; Kochetov, Igor' V; Napartovich, A P; Hager, G D

    2004-09-30

    The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume ({approx}18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts ({approx}1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving {approx}6.5 kJ L{sup -1} atm{sup -1} per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O{sub 2} : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O{sub 2}(a{sup 1{Delta}}{sub g}) and O{sub 2}(b{sup 1{Sigma}}{sub g}{sup +}), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O{sub 2}(a{sup 1{Delta}}{sub g}) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value {approx}3% for W {approx} 1.0 kJ L{sup -1} atm{sup -1} is in agreement with the theoretical estimate. Theoretical calculations performed for W {approx} 6.5 kJ L{sup -1} atm{sup -1} at a fixed temperature show that the singlet-oxygen yield may be {approx}20%, which is higher than the value required to achieve the lasing threshold in an oxygen-iodine laser at room temperature. (laser applications and other topics in quantum electronics)

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

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

    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.

  7. Rectifying and negative differential resistance behaviors of a functionalized Tour wire: The position effects of functional groups

    NASA Astrophysics Data System (ADS)

    Kwong, Gordon; Zhang, Zhenhua; Pan, Jinbo

    2011-09-01

    Based on Tour wire, we construct four D-π-A molecular devices with different positional functional groups, in an attempt to explore the position effects of functional groups on their electronic transport properties and to show that some interesting physical phenomena can emerge by only varying the position of functional groups. The first-principles calculations demonstrate that the position of functional groups can affect the rectifying behaviors (rectification direction and ratio) significantly and determines whether or not the negative differential resistance (NDR) can be observed as well as the physical origin of the NDR phenomenon.

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

    PubMed

    Sakata, Sho; Inoue, Yuuki; Ishihara, Kazuhiko

    2014-03-18

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

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  10. Realizing load reduction functions by aperiodic switching of load groups

    SciTech Connect

    Navid-Azarbaijani, N.; Banakar, M.H.

    1996-05-01

    This paper investigates the problem of scheduling ON/OFF switching of residential appliances under the control of a Load Management System (LMS). The scheduling process is intended to reduce the controlled appliances` power demand in accordance with a predefined load reduction profile. To solve this problem, a solution approach, based on the methodology of Pulse Width Modulation (PWM), is introduced. This approach provides a flexible mathematical basis for studying different aspects of the scheduling problem. The conventional practices in this area are shown to be special cases of the PWM technique. By applying the PWM-based technique to the scheduling problem, important classes of scheduling errors are identified and analytical expressions describing them are derived. These expressions are shown to provide sufficient information to compensate for the errors. Detailed simulations of load groups` response to switching actions are use to support conclusions of this study.

  11. Visualization of group inference data in functional neuroimaging.

    PubMed

    Gläscher, Jan

    2009-01-01

    While thresholded statistical parametric maps can convey an accurate account for the location and spatial extent of an effect in functional neuroimaging studies, their use is somewhat limited for characterizing more complex experimental effects, such as interactions in a factorial design. The resulting necessity for plotting the underlying data has long been recognized. Statistical Parametric Mapping (SPM) is a widely used software package for analyzing functional neuroimaging data that offers a variety of options for visualizing data from first level analyses. However, nowadays, the thrust of the statistical inference lies at the second level thus allowing for population inference. Unfortunately, the options for visualizing data from second level analyses are quite sparse. rfxplot is a new toolbox designed to alleviate this problem by providing a comprehensive array of options for plotting data from within second level analyses in SPM. These include graphs of average effect sizes (across subjects), averaged fitted responses and event-related blood oxygen level-dependent (BOLD) time courses. All data are retrieved from the underlying first level analyses and voxel selection can be tailored to the maximum effect in each subject within a defined search volume. All plot configurations can be easily configured via a graphical user-interface as well as non-interactively via a script. The large variety of plot options renders rfxplot suitable both for data exploration as well as producing high-quality figures for publications. PMID:19140033

  12. Water electrolyte promoted oxidation of functional thiol groups.

    PubMed

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

    2016-04-15

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

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

    PubMed

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

    2014-06-28

    We have synthesized five novel Ru(ii) phenanthroline complexes with an additional aryl sulfonate ligating substituent at the 5-position [Ru(L)(bpy)2](BF4)2 (1), [Ru(L)(bpy)(SCN)2] (2), [Ru(L)3](BF4)2 (3), [Ru(L)2(bpy)](BF4)2 (4) and [Ru(L)(BPhen)(SCN)2] (5) (where L = 6-one-[1,10]phenanthroline-5-ylamino)-3-hydroxynaphthalene 1-sulfonic, bpy = 2,2'-bipyridine, BPhen = 4,7-diphenyl-1,10-phenanthroline), as both photosensitizers for oxide semiconductor solar cells (DSSCs) and light emitting diodes (LEDs). The absorption and emission maxima of these complexes red shifted upon extending the conjugation of the phenanthroline ligand. Ru phenanthroline complexes exhibit broad metal to ligand charge transfer-centered electroluminescence (EL) with a maximum near 580 nm. Our results indicated that a particular structure (2) can be considered as both DSSC and OLED devices. The efficiency of the LED performance can be tuned by using a range of ligands. Device (2) has a luminance of 550 cd m(-2) and maximum efficiency of 0.9 cd A(-1) at 18 V, which are the highest values among the five devices. The turn-on voltage of this device is approximately 5 V. The role of auxiliary ligands in the photophysical properties of Ru complexes was investigated by DFT calculation. We have also studied photovoltaic properties of dye-sensitized nanocrystalline semiconductor solar cells based on Ru phenanthroline complexes and an iodine redox electrolyte. A solar energy to electricity conversion efficiency (η) 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

  14. Positive-type functions on groups and new inequalities in classical and quantum mechanics

    NASA Astrophysics Data System (ADS)

    Man'ko, V. I.; Marmo, G.; Simoni, A.; Ventriglia, F.

    2010-09-01

    Out of any unitary representation of a group, positive-type functions on the group can be obtained. These functions allow one to construct positive semi-definite matrices that may be used to define new inequalities for higher moments of observables associated with classical probability distribution functions and density states of quantum systems. The inequalities stemming from the Heisenberg-Weyl group representations are considered in connection with Gaussian distributions. We obtain new inequalities for multi-variable Hermite polynomials.

  15. Synthesis of Highly Functionalized Triarylbismuthines by Functional Group Manipulation and Use in Palladium- and Copper-Catalyzed Arylation Reactions.

    PubMed

    Hébert, Martin; Petiot, Pauline; Benoit, Emeline; Dansereau, Julien; Ahmad, Tabinda; Le Roch, Adrien; Ottenwaelder, Xavier; Gagnon, Alexandre

    2016-07-01

    Organobismuthines are an attractive class of organometallic reagents that can be accessed from inexpensive and nontoxic bismuth salts. Triarylbismuthines are particularly interesting due to their air and moisture stability and high functional group tolerance. We report herein a detailed study on the preparation of highly functionalized triarylbismuth reagents by triple functional group manipulation and their use in palladium- and copper-catalyzed C-, N-, and O-arylation reactions. PMID:27231755

  16. Metallicity Distribution Functions of Four Local Group Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  17. Mapping functional groups on oxidised multi-walled carbon nanotubes at the nanometre scale.

    PubMed

    Goode, A E; Hine, N D M; Chen, S; Bergin, S D; Shaffer, M S P; Ryan, M P; Haynes, P D; Porter, A E; McComb, D W

    2014-06-28

    Despite voluminous research on the acid oxidation of carbon nanotubes (CNTs), there is a distinct lack of experimental results showing distributions of functional groups at the nanometre length scale. Here, functional peaks have been mapped across individual multi-walled CNTs with low-dose, monochromated electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). Density functional theory simulations show that the EELS features are consistent with oxygenated functional groups, most likely carboxyl moieties. PMID:24827593

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  19. Use of morphological characteristics to define functional groups of predatory fishes in the Celtic Sea.

    PubMed

    Reecht, Y; Rochet, M-J; Trenkel, V M; Jennings, S; Pinnegar, J K

    2013-08-01

    An ecomorphological method was developed, with a focus on predation functions, to define functional groups in the Celtic Sea fish community. Eleven functional traits, measured for 930 individuals from 33 species, led to 11 functional groups. Membership of functional groups was linked to body size and taxonomy. For seven species, there were ontogenetic changes in group membership. When diet composition, expressed as the proportions of different prey types recorded in stomachs, was compared among functional groups, morphology-based predictions accounted for 28-56% of the interindividual variance in prey type. This was larger than the 12-24% of variance that could be explained solely on the basis of body size. PMID:23902311

  20. 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 ...

  1. 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...

  2. Biogeographical boundaries, functional group structure and diversity of Rocky Shore communities along the Argentinean coast.

    PubMed

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

    2012-01-01

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

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

    PubMed Central

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

    2012-01-01

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

  4. 14 CFR Section 10 - Functional Classification-Operating Expenses of Group I Air Carriers

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Functional Classification-Operating... REPORTS FOR LARGE CERTIFICATED AIR CARRIERS Profit and Loss Classification Section 10 Functional Classification—Operating Expenses of Group I Air Carriers 5100Flying Operations. (a) This function shall...

  5. Use of the Sequence Rule for Indexing Functional Groups in Organic Compounds

    ERIC Educational Resources Information Center

    Hudrlik, Paul F.

    1973-01-01

    A new method of indexing functional groups in organic compounds is described, utilizing the Cahn-Ingold-Prelog sequence rule. Functional carbon atoms are first classified by functionality, a measure of the oxidation state, then ordered by means of a modified sequence rule. Substructure searching and other applications are discussed. (30…

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

    PubMed

    Richarz, Bernhard; Römisch, Sylvelin

    2002-07-01

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

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

    PubMed Central

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

    2008-01-01

    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

  8. Controllable Tailoring Graphene Nanoribbons with Tunable Surface Functionalities: An Effective Strategy toward High-Performance Lithium-Ion Batteries.

    PubMed

    Wang, Chundong; Li, Yan-Sheng; Jiang, Jianjun; Chiang, Wei-Hung

    2015-08-12

    An effective, large-scale synthesis strategy for producing graphene nanoribbons (GNRs) with a nearly 100% yield has been proposed using a stepwise, solution-based, lengthwise unzipping carbon nanotube (CNT) method. Detailed Raman and X-ray photoelectron spectroscopy (XPS) analysis suggest that GNRs with tunable density of oxygen-containing functional groups on the GNR surfaces can be synthesized by adjusting the oxidant concentration during the CNT unzipping. The electrochemical characterization reveals that the as-produced GNRs with 42.91 atomic percent (atom %) oxygen-containing functional groups deliver a capacity of 437 mAh g(-1) after 100 cycles at 0.33C, while the as-produced GNRs with higher oxygen-containing functional groups only present a capacity of 225 mAh g(-1). On the basis of the electrochemical assessment and XPS analysis, the funtionals groups (epoxy-, carbonyl-, and carboxyl groups) in GNRs could be the effective contributor for the high-performance Li-ion batteries with appropriate adjustment. PMID:26196904

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

    NASA Astrophysics Data System (ADS)

    Cowan, Mark Timothy

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

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

    ERIC Educational Resources Information Center

    Clinging, R.; Lynch, M. F.

    1973-01-01

    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)

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

    SciTech Connect

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

    2010-01-01

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

  12. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dron, J.; El Haddad, I.; Temime-Roussel, B.; Jaffrezo, J.-L.; Wortham, H.; Marchand, N.

    2010-04-01

    The functional group composition of various organic aerosols (OA) is being investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS). The determinations of the three functional groups' contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups) and precursor ion (nitro groups) scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA) produced through photo-oxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounted for 1.7% (vehicular) to 13.5% (o-xylene photo-oxidation) of the organic carbon. The diagnostic functional group ratios are then used to tentatively differentiate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France) during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to distinguish the sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assesses a wood burning organic carbon contribution of about 60%. Finally, examples of functional group mass spectra of all

  13. Evaluation of group A1B erythrocytes converted to type as group O: studies of markers of function and compatibility

    PubMed Central

    Gao, Hong-Wei; Zhuo, Hai-Long; Zhang, Xue; Ji, Shou-Ping; Tan, Ying-Xia; Li, Su-Bo; Jia, Yan-Jun; Xu, Hua; Wu, Qing-Fa; Yun, Zhi-Min; Luo, Qun; Gong, Feng

    2016-01-01

    Background Enzymatic conversion of blood group A1B red blood cells (RBC) to group O RBC (ECO) was achieved by combined treatment with α-galactosidase and α-N-acetylgalactosaminidase. The aim of this study was to evaluate the function and safety of these A1B-ECO RBC in vitro. Materials and methods A 20% packed volume of A1B RBC was treated with enzymes in 250 mM glycine buffer, pH 6.8. The efficiency of the conversion of A and B antigen was evaluated by traditional typing in test tubes, gel column agglutination technology and fluorescence-activated cell sorting (FACS) analysis. The physiological and metabolic parameters of native and ECO RBC were compared, including osmotic fragility, erythrocyte deformation index, levels of 2,3-diphosphoglycerate, ATP, methaemoglobin, free Na+, and free K+. The morphology of native and ECO RBC was observed by scanning electron microscopy. Residual α-galactosidase or α-N-acetylgalactosaminidase in A1B-ECO RBC was detected by double-antibody sandwich ELISA method. Manual cross-matching was applied to ensure blood compatibility. Results The RBC agglutination tests and FACS results showed that A1B RBC were efficiently converted to O RBC. Functional analysis suggested that the conversion process had little impact on the physiological and metabolic parameters of the RBC. The residual amounts of either α-galactosidase or α-N-acetylgalactosaminidase in the A1B-ECO RBC were less than 10 ng/mL of packed RBC. About 18% of group B and 55% of group O sera reacted with the A1B-ECO RBC in a sensitive gel column cross-matching test. Discussion The conversion process does not appear to affect the morphological, physiological or metabolic parameters of A1B-ECO RBC. However, the A1B-ECO RBC still reacted with some antigens. More research on group O and B sera, which may partly reflect the complexity of group A1 the safety of A1B-ECO RBC is necessary before the application of these RBC in clinical transfusion. PMID:26509826

  14. The Use of Language Functions in Mathematical Group Games. Teacher Insights.

    ERIC Educational Resources Information Center

    Black, Carolyn; Huerta, Maria G.

    1994-01-01

    Six group games were introduced into a second-grade bilingual classroom. Children's talk during each game was classified using a modification of Dyson's five language functions (representational, directive, heuristic, personal, and interactional). Group games provided many communication opportunities. Some children tried new communication styles.…

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

    ERIC Educational Resources Information Center

    Magis, David; De Boeck, Paul

    2011-01-01

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

  16. Characteristics of Interactional Management Functions in Group Oral by Japanese Learners of English

    ERIC Educational Resources Information Center

    Negishi, Junko

    2010-01-01

    This study attempted to investigate the characteristics of interaction dynamics in a group oral interaction carried out by Japanese learners of English. The relationship between the participants' language development and interactional management functions (IMFs) was also explored. Oral performance tests in a paired or a small group have recently…

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

    NASA Technical Reports Server (NTRS)

    Foster, Tammy E.; Brooks, J. Renee

    2004-01-01

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

  18. Multiple-Group Noncompensatory Differential Item Functioning in Raju's Differential Functioning of Items and Tests

    ERIC Educational Resources Information Center

    Oshima, T. C.; Wright, Keith; White, Nick

    2015-01-01

    Raju, van der Linden, and Fleer (1995) introduced a framework for differential functioning of items and tests (DFIT) for unidimensional dichotomous models. Since then, DFIT has been shown to be a quite versatile framework as it can handle polytomous as well as multidimensional models both at the item and test levels. However, DFIT is still limited…

  19. Sub-grouping and sub-functionalization of the RIFIN multi-copy protein family

    PubMed Central

    Joannin, Nicolas; Abhiman, Saraswathi; Sonnhammer, Erik L; Wahlgren, Mats

    2008-01-01

    Background Parasitic protozoans possess many multicopy gene families which have central roles in parasite survival and virulence. The number and variability of members of these gene families often make it difficult to predict possible functions of the encoded proteins. The families of extra-cellular proteins that are exposed to a host immune response have been driven via immune selection to become antigenically variant, and thereby avoid immune recognition while maintaining protein function to establish a chronic infection. Results We have combined phylogenetic and function shift analyses to study the evolution of the RIFIN proteins, which are antigenically variant and are encoded by the largest multicopy gene family in Plasmodium falciparum. We show that this family can be subdivided into two major groups that we named A- and B-RIFIN proteins. This suggested sub-grouping is supported by a recently published study that showed that, despite the presence of the Plasmodium export (PEXEL) motif in all RIFIN variants, proteins from each group have different cellular localizations during the intraerythrocytic life cycle of the parasite. In the present study we show that function shift analysis, a novel technique to predict functional divergence between sub-groups of a protein family, indicates that RIFINs have undergone neo- or sub-functionalization. Conclusion These results question the general trend of clustering large antigenically variant protein groups into homogenous families. Assigning functions to protein families requires their subdivision into meaningful groups such as we have shown for the RIFIN protein family. Using phylogenetic and function shift analysis methods, we identify new directions for the investigation of this broad and complex group of proteins. PMID:18197962

  20. 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...

  1. Heterologous expression and functional analysis of the wheat group 1 pathogenesis-related (PR-1) proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The group 1 pathogenesis-related (PR-1) proteins have been widely used as hallmarks of plant defense pathways, but their biological functions are still unknown. We report here the functional analysis of two basic PR-1 proteins following the identification of the wheat PR-1 gene family (Lu et al., 20...

  2. The dual roles of functional groups in the photoluminescence of graphene quantum dots

    NASA Astrophysics Data System (ADS)

    Wang, Shujun; Cole, Ivan S.; Zhao, Dongyuan; Li, Qin

    2016-03-01

    The photoluminescent properties of graphene nanoparticle (named graphene quantum dots) have attracted significant research attention in recent years owing to their profound application potential. However, the photoluminescence (PL) origin of this class of nanocarbons is still unclear. In this paper, combining direct experimental evidence enabled by a facile size-tunable oxygenated graphene quantum dots (GQDs) synthesis method and theoretical calculations, the roles of the aromatic core, functional groups and disordered structures (i.e. defects and sp3 carbon) in the PL of oxygenated GQDs are elucidated in detail. In particular, we found that the functional groups on GQDs play dual roles in the overall emission: (1) they enable π* --> n and σ* --> n transitions, resulting in a molecular type of PL, spectrally invariable with change of particle size or excitation energy; (2) similar to defects and sp3 carbon, functional groups also induce structural deformation to the aromatic core, leading to mid-gap states or, in other words, energy traps, causing π* --> mid-gap states --> π transitions. Therefore, functional groups contribute to both the blue edge and the red shoulder of GQDs' PL spectra. The new insights on the role of functional groups in PL of fluorescent nanocarbons will enable better designs of this new class of materials.The photoluminescent properties of graphene nanoparticle (named graphene quantum dots) have attracted significant research attention in recent years owing to their profound application potential. However, the photoluminescence (PL) origin of this class of nanocarbons is still unclear. In this paper, combining direct experimental evidence enabled by a facile size-tunable oxygenated graphene quantum dots (GQDs) synthesis method and theoretical calculations, the roles of the aromatic core, functional groups and disordered structures (i.e. defects and sp3 carbon) in the PL of oxygenated GQDs are elucidated in detail. In particular, we found

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

    PubMed

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

    2011-01-01

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

  4. The impact of functional group on the electronic structure of coordination center

    NASA Astrophysics Data System (ADS)

    Hooshmand Gharehbagh, Zahra; L, Duy; Rahman, Talat S.

    While 9, 10 dicyano-anthracene (DCA) forms a coordination network on Cu(111) surface with Cu adatom coordinated by three DCA molecules, its isomers, 9,10-diisocyano-anthracene forms, surprisingly, molecular rows on the same surface. To understand the impact of functional groups on the electronic structure of the coordination center, we have carried out density functional theory based calculations of the electronic structure of a set of naphthalene molecules with different functional groups (N, CN, NC, NH2, COH, COOH) adsorbed on Cu(111), with and without a Cu adatom. Our results show that while the interaction between the naphthalene backbone and the Cu(111) surface is dominated by van der Waals (vdW) forces, in all cases considered the functional group forms a covalent bond with the Cu (ad)atom (on) of the surface. The calculated differential charge redistribution shows that the strongest covalent bond is formed by the NC group, which differs remarkably from that formed by the CN group, while the vdW interaction is very similar in both cases. These results provide insights into the different surface coordination behavior of molecules with above-mentioned functional groups. Work support in part by NSF Grant CHE-1310327.

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

    PubMed Central

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

    2011-01-01

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

  6. On the psychological function of flags and logos: Group identity symbols increase perceived entitativity.

    PubMed

    Callahan, Shannon P; Ledgerwood, Alison

    2016-04-01

    Group identity symbols such as flags and logos have been widely used across time and cultures, yet researchers know very little about the psychological functions that such symbols can serve. The present research tested the hypotheses that (a) simply having a symbol leads collections of individuals to seem more like real, unified groups, (b) this increased psychological realness leads groups to seem more threatening and effective to others, and (c) group members therefore strategically emphasize symbols when they want their group to appear unified and intimidating. In Studies 1a-1c, participants perceived various task groups as more entitative when they happened to have a symbol. In Study 2, symbols not only helped groups make up for lacking a physical characteristic associated with entitativity (physical similarity), but also led groups to seem more threatening. Study 3 examined the processes underlying this effect and found that group symbols increase entitativity by increasing perceived cohesiveness. Study 4 extended our results to show that symbols not only shape the impressions people form of novel groups, but also change people's existing impressions of more familiar and real-world social groups, making them seem more entitative and competent but also less warm. Finally, Studies 5a and 5b further expand our understanding of the psychological function of symbols by showing that group members strategically display symbols when they are motivated to convey an impression of their group as unified and threatening (vs. inclusive and cooperative). We discuss implications for understanding how group members navigate their social identities. (PsycINFO Database Record PMID:27078507

  7. Stability domain of alumina thermally grown on Fe-Cr-Al-based model alloys and modified surface layers exposed to oxygen-containing molten Pb

    NASA Astrophysics Data System (ADS)

    Jianu, A.; Fetzer, R.; Weisenburger, A.; Doyle, S.; Bruns, M.; Heinzel, A.; Hosemann, P.; Mueller, G.

    2016-03-01

    The paper gives experimental results concerning the morphology, composition, structure and thickness of the oxide scales grown on Fe-Cr-Al-based bulk alloys during exposure to oxygen-containing molten lead. The results are discussed and compared with former results obtained on Al-containing surface layers, modified by melting with intense pulsed electron beam and exposed to similar conditions. The present and previous results provide the alumina stability domain and also the criterion of the Al/Cr ratio for the formation of a highly protective alumina layer on the surface of Fe-Cr-Al-based alloys and on modified surface layers exposed to molten lead with 10-6 wt.% oxygen at 400-600 °C. The protective oxide scales, grown on alumina-forming Fe-Cr-Al alloys under the given experimental conditions, were transient aluminas, namely, kappa-Al2O3 and theta-Al2O3.

  8. [Functional groups of high trophic level communities in adjacent waters of Changjiang estuary].

    PubMed

    Zhang, Bo; Jin, Xian-Shi; Tang, Qi-Sheng

    2009-02-01

    Based on the three bottom trawl surveys in adjacent waters of Changjiang estuary in June, August and October 2006, the composition and variation of the functional groups of high trophic level communities in the waters were studied. According to diet analysis, the high trophic level communities in the waters included six functional groups, i.e., piscivore, shrimp predator, crab predator, benthivore, planktivore, and generalist predator. Due to the variation of marine environment and fish migration behavior, the composition and trophic level of the high trophic level communities had greater monthly change. In June, fishes, acetes, and crabs dominated the communities, and planktivore was the major functional group, with its trophic level being the lowest (3.06); in August, fishes were dominant, and shrimp predator was the major functional group, with its trophic level being the highest (3.78); and in October, fishes also dominated the communities, the proportion of shrimp and crab increased, and planktivore and benthivore were the major functional groups, with a trophic level of 3.58. PMID:19459374

  9. The dual roles of functional groups in the photoluminescence of graphene quantum dots.

    PubMed

    Wang, Shujun; Cole, Ivan S; Zhao, Dongyuan; Li, Qin

    2016-04-14

    The photoluminescent properties of graphene nanoparticle (named graphene quantum dots) have attracted significant research attention in recent years owing to their profound application potential. However, the photoluminescence (PL) origin of this class of nanocarbons is still unclear. In this paper, combining direct experimental evidence enabled by a facile size-tunable oxygenated graphene quantum dots (GQDs) synthesis method and theoretical calculations, the roles of the aromatic core, functional groups and disordered structures (i.e. defects and sp(3) carbon) in the PL of oxygenated GQDs are elucidated in detail. In particular, we found that the functional groups on GQDs play dual roles in the overall emission: (1) they enable π* → n and σ* → n transitions, resulting in a molecular type of PL, spectrally invariable with change of particle size or excitation energy; (2) similar to defects and sp(3) carbon, functional groups also induce structural deformation to the aromatic core, leading to mid-gap states or, in other words, energy traps, causing π* → mid-gap states → π transitions. Therefore, functional groups contribute to both the blue edge and the red shoulder of GQDs' PL spectra. The new insights on the role of functional groups in PL of fluorescent nanocarbons will enable better designs of this new class of materials. PMID:26731007

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

    PubMed

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

    2016-01-01

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

  11. Local and Regional Determinants of an Uncommon Functional Group in Freshwater Lakes and Ponds

    PubMed Central

    McCann, Michael James

    2015-01-01

    A combination of local and regional factors and stochastic forces is expected to determine the occurrence of species and the structure of communities. However, in most cases, our understanding is incomplete, with large amounts of unexplained variation. Using functional groups rather than individual species may help explain the relationship between community composition and conditions. In this study, I used survey data from freshwater lakes and ponds to understand factors that determine the presence of the floating plant functional group in the northeast United States. Of the 176 water bodies surveyed, 104 (59.1%) did not contain any floating plant species. The occurrence of this functional group was largely determined by local abiotic conditions, which were spatially autocorrelated across the region. A model predicting the presence of the floating plant functional group performed similarly to the best species-specific models. Using a permutation test, I also found that the observed prevalence of floating plants is no different than expected by random assembly from a species pool of its size. These results suggest that the size of the species pool interacts with local conditions in determining the presence of a functional group. Nevertheless, a large amount of unexplained variation remains, attributable to either stochastic species occurrence or incomplete predictive models. The simple permutation approach in this study can be extended to test alternative models of community assembly. PMID:26121636

  12. Inverse transfer method using polymers with various functional groups for controllable graphene doping.

    PubMed

    Lee, Seong Kyu; Yang, Jae Won; Kim, Hyun Ho; Jo, Sae Byeok; Kang, Boseok; Bong, Hyojin; Lee, Hyo Chan; Lee, Geunsik; Kim, Kwang S; Cho, Kilwon

    2014-08-26

    The polymer-supported transfer of chemical vapor deposition (CVD)-grown graphene provides large-area and high-quality graphene on a target substrate; however, the polymer and organic solvent residues left by the transfer process hinder the application of CVD-grown graphene in electronic and photonic devices. Here, we describe an inverse transfer method (ITM) that permits the simultaneous transfer and doping of graphene without generating undesirable residues by using polymers with different functional groups. Unlike conventional wet transfer methods, the polymer supporting layer used in the ITM serves as a graphene doping layer placed at the interface between the graphene and the substrate. Polymers bearing functional groups can induce n-doping or p-doping into the graphene depending on the electron-donating or -withdrawing characteristics of functional groups. Theoretical models of dipole layer-induced graphene doping offered insights into the experimentally measured change in the work function and the Dirac point of the graphene. Finally, the electrical properties of pentacene field effect transistors prepared using graphene electrodes could be enhanced by employing the ITM to introduce a polymer layer that tuned the work function of graphene. The versatility of polymer functional groups suggests that the method developed here will provide valuable routes to the development of applications of CVD-grown graphene in organic electronic devices. PMID:25050634

  13. Linking of sensor molecules with amino groups to amino-functionalized AFM tips.

    PubMed

    Wildling, Linda; Unterauer, Barbara; Zhu, Rong; Rupprecht, Anne; Haselgrübler, Thomas; Rankl, Christian; Ebner, Andreas; Vater, Doris; Pollheimer, Philipp; Pohl, Elena E; Hinterdorfer, Peter; Gruber, Hermann J

    2011-06-15

    The measuring tip of an atomic force microscope (AFM) can be upgraded to a specific biosensor by attaching one or a few biomolecules to the apex of the tip. The biofunctionalized tip is then used to map cognate target molecules on a sample surface or to study biophysical parameters of interaction with the target molecules. The functionality of tip-bound sensor molecules is greatly enhanced if they are linked via a thin, flexible polymer chain. In a typical scheme of tip functionalization, reactive groups are first generated on the tip surface, a bifunctional cross-linker is then attached with one of its two reactive ends, and finally the probe molecule of interest is coupled to the free end of the cross-linker. Unfortunately, the most popular functional group generated on the tip surface is the amino group, while at the same time, the only useful coupling functions of many biomolecules (such as antibodies) are also NH(2) groups. In the past, various tricks or detours were applied to minimize the undesired bivalent reaction of bifunctional linkers with adjacent NH(2) groups on the tip surface. In the present study, an uncompromising solution to this problem was found with the help of a new cross-linker ("acetal-PEG-NHS") which possesses one activated carboxyl group and one acetal-protected benzaldehyde function. The activated carboxyl ensures rapid unilateral attachment to the amino-functionalized tip, and only then is the terminal acetal group converted into the amino-reactive benzaldehyde function by mild treatment (1% citric acid, 1-10 min) which does not harm the AFM tip. As an exception, AFM tips with magnetic coating become demagnetized in 1% citric acid. This problem was solved by deprotecting the acetal group before coupling the PEG linker to the AFM tip. Bivalent binding of the corresponding linker ("aldehyde-PEG-NHS") to adjacent NH(2) groups on the tip was largely suppressed by high linker concentrations. In this way, magnetic AFM tips could be

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

    PubMed

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

    2015-01-01

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

  15. Synthesis of neamine-derived pseudodisaccharides by stereo- and regio-selective functional group transformations.

    PubMed

    Pang, Li-Juan; Wang, Dan; Zhou, Jian; Zhang, Li-He; Ye, Xin-Shan

    2009-10-21

    Neamine is normally found as a core structure of aminoglycoside antibiotics. In order to understand the relationship between the antibiotic activity and the configurations of the functional groups of neamine, a series of novel neamine analogues with functional group manipulations on the 2-deoxystreptamine (2-DOS) ring or the sugar ring were designed and synthesized. The synthetic approach involved the construction of 2-DOS derivatives by catalytic Ferrier II rearrangement, stereo- and regio-selective functional group transformations, glycosyl coupling reaction, and global deprotection. Of the synthetic neamine analogues, four compounds showed comparable 16S rRNA binding affinities with neamine, whereas they displayed lower binding affinities towards 18S rRNA than neamine, implying a lower toxicity to mammals. This strategy might have applications in the chemical synthesis of other neamine derivatives and new aminoglycoside antibiotics with improved biological activities. PMID:19795065

  16. Wigner functions for noncommutative quantum mechanics: A group representation based construction

    SciTech Connect

    Chowdhury, S. Hasibul Hassan; Ali, S. Twareque

    2015-12-15

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

  17. Evaluation of various carbon substrates for the biosynthesis of polyhydroxyalkanoates bearing functional groups by Pseudomonas putida.

    PubMed

    Kim, D Y; Kim, Y B; Rhee, Y H

    2000-10-10

    The ability of Pseudomonas putida to synthesize polyhydroxyalkanoate (PHA) from 36 different carboxylic acids containing various functional groups was examined. This bacterium did not utilize short carboxylic acids (C(4)-C(6)) containing bromine, methoxy, ethoxy, cyclohexyl, phenoxy, and olefin groups as the sole carbon substrate. No polymer was isolated from the cells grown with carboxylic acids bearing hydroxyl, amino, para-methoxyphenoxy, and para-ethoxyphenoxy groups regardless of the carbon substrate chain lengths used even when they were cofed with nonanoic acid. Of all the carbon substrates evaluated, only 6-para-methylphenoxyhexanoic acid, 8-para-methylphenoxyoctanoic acid, 8-meta-methylphenoxyoctanoic acid, 10-undecenoic acid, and 10-undecynoic acid supported both growth and the production of PHA containing the corresponding functional groups by P. putida. The present results indicate that the carbon availability of P. putida for growth and PHA production is significantly different from that of P. oleovorans. PMID:11033174

  18. Contributions of functional groups and extracellular polymeric substances on the biosorption of dyes by aerobic granules.

    PubMed

    Gao, Jing-Feng; Zhang, Qian; Wang, Jin-Hui; Wu, Xue-Lei; Wang, Shu-Ying; Peng, Yong-Zhen

    2011-01-01

    The contributions of loosely bound extracellular polymeric substances (LB-EPS), tightly bound EPS (TB-EPS), residual sludge (the sludge left after EPS extraction) and functional groups such as amine, carboxyl, phosphate and lipid on aerobic granules on biosorption of four different dyes (Reactive Brilliant Blue KN-R (KN-R), Congo Red (CR), Reactive Brilliant Red K-2G (RBR) and Malachite Green (MG)) were investigated. EPS may be responsible for biosorption of cationic dyes. However, residual sludge always made greater contribution than that of EPS. The biosorption mechanisms were dependent on the functional groups on aerobic granules and dyes' chemical structures. The lipid and phosphate groups might be the main binding sites for KN-R biosorption. Amine, carboxyl, phosphate and lipid were all responsible for the binding of CR. The lipid fractions played an important role for RBR biosorption. For MG, the phosphate groups gave the largest contribution. PMID:20869236

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

    PubMed

    Maya, Fernando; Svec, Frantisek

    2013-11-22

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

  20. A Simple and Versatile Amide Directing Group for C-H Functionalizations.

    PubMed

    Zhu, Ru-Yi; Farmer, Marcus E; Chen, Yan-Qiao; Yu, Jin-Quan

    2016-08-26

    Achieving selective C-H activation at a single and strategic site in the presence of multiple C-H bonds can provide a powerful and generally useful retrosynthetic disconnection. In this context, a directing group serves as a compass to guide the transition metal to C-H bonds by using distance and geometry as powerful recognition parameters to distinguish between proximal and distal C-H bonds. However, the installation and removal of directing groups is a practical drawback. To improve the utility of this approach, one can seek solutions in three directions: 1) Simplifying the directing group, 2) using common functional groups or protecting groups as directing groups, and 3) attaching the directing group to substrates via a transient covalent bond to render the directing group catalytic. This Review describes the rational development of an extremely simple and yet broadly applicable directing group for Pd(II) , Rh(III) , and Ru(II) catalysts, namely the N-methoxy amide (CONHOMe) moiety. Through collective efforts in the community, a wide range of C-H activation transformations using this type of simple directing group have been developed. PMID:27479708

  1. Effect of carbon nanofiber surface functional groups on oxygen reduction in alkaline solution

    NASA Astrophysics Data System (ADS)

    Zhong, Ren-Sheng; Qin, Yuan-Hang; Niu, Dong-Fang; Tian, Jing-Wei; Zhang, Xin-Sheng; Zhou, Xin-Gui; Sun, Shi-Gang; Yuan, Wei-Kang

    2013-03-01

    Carbon nanofibers (CNFs) with different content of surface functional groups which are carboxyl groups (CNF-OX), carbonyl groups (CNF-CO) and hydroxyl groups (CNF-OH) and nitrogen-containing groups (CNF-ON) are synthesized, and their electrocatalytic activities toward oxygen reduction reaction (ORR) in alkaline solution are investigated. The result of X-ray photoelectron spectroscopy (XPS) characterization indicates that a higher concentration of carboxyl groups, carbonyl groups and hydroxyl groups are imported onto the CNF-OX, CNF-CO and CNF-OH, respectively. Cyclic voltammetry shows that both the oxygen- and nitrogen-containing groups can improve the electrocatalytic activity of CNFs for ORR. The CNF-ON/GC electrode, which has nitrogen-containing groups, exhibits the highest current density of ORR. Rotating disk electrode (RDE) characterization shows that the oxygen reduction on CNF-ON/GC electrode proceeds almost entirely through the four-electron reduction pathway, the CNF-OX/GC, CNF-CO/GC and CNF-OH/GC electrodes proceed a two-electron reduction pathway at low potentials (-0.2 V to -0.6 V) followed by a gradual four-electron reduction pathway at more negative potentials, while the untreated carbon nanofiber (CNF-P/GC) electrode proceeds predominantly by a two-electron reduction pathway within the whole range of potential studied.

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

    PubMed Central

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

    2009-01-01

    We performed an updated quantitative meta-analysis of 162 neuroimaging studies of emotion using a novel multi-level kernel-based approach, focusing on locating brain regions consistently activated in emotional tasks and their functional organization into distributed functional groups, independent of semantically defined emotion category labels (e.g., “anger,” “fear”). Such brain-based analyses are critical if our ways of labeling emotions are to be evaluated and revised based on consistency with brain data. Consistent activations were limited to specific cortical sub-regions, including multiple functional areas within medial, orbital, and inferior lateral frontal cortices. Consistent with a wealth of animal literature, multiple subcortical activations were identified, including amygdala, ventral striatum, thalamus, hypothalamus, and periaqueductal gray. We used multivariate parcellation and clustering techniques to identify groups of co-activated brain regions across studies. These analyses identified six distributed functional groups, including medial and lateral frontal groups, two posterior cortical groups, and paralimbic and core limbic/brainstem groups. These functional groups provide information on potential organization of brain regions into large-scale networks. Specific follow-up analyses focused on amygdala, periaqueductal gray (PAG), and hypothalamic (Hy) activations, and identified frontal cortical areas co-activated with these core limbic structures. While multiple areas of frontal cortex co-activated with amygdala sub-regions, a specific region of dorsomedial prefrontal cortex (dmPFC, Brodmann’s Area 9/32) was the only area co-activated with both PAG and Hy. Subsequent mediation analyses were consistent with a pathway from dmPFC through PAG to Hy. These results suggest that medial frontal areas are more closely associated with core limbic activation than their lateral counterparts, and that dmPFC may play a particularly important role in the

  3. Plant diversity and functional groups affect Si and Ca pools in aboveground biomass of grassland systems.

    PubMed

    Schaller, Jörg; Roscher, Christiane; Hillebrand, Helmut; Weigelt, Alexandra; Oelmann, Yvonne; Wilcke, Wolfgang; Ebeling, Anne; Weisser, Wolfgang W

    2016-09-01

    Plant diversity is an important driver of nitrogen and phosphorus stocks in aboveground plant biomass of grassland ecosystems, but plant diversity effects on other elements also important for plant growth are less understood. We tested whether plant species richness, functional group richness or the presence/absence of particular plant functional groups influences the Si and Ca concentrations (mmol g(-1)) and stocks (mmol m(-2)) in aboveground plant biomass in a large grassland biodiversity experiment (Jena Experiment). In the experiment including 60 temperate grassland species, plant diversity was manipulated as sown species richness (1, 2, 4, 8, 16) and richness and identity of plant functional groups (1-4; grasses, small herbs, tall herbs, legumes). We found positive species richness effects on Si as well as Ca stocks that were attributable to increased biomass production. The presence of particular functional groups was the most important factor explaining variation in aboveground Si and Ca stocks (mmol m(-2)). Grass presence increased the Si stocks by 140 % and legume presence increased the Ca stock by 230 %. Both the presence of specific plant functional groups and species diversity altered Si and Ca stocks, whereas Si and Ca concentration were affected mostly by the presence of specific plant functional groups. However, we found a negative effect of species diversity on Si and Ca accumulation, by calculating the deviation between mixtures and mixture biomass proportions, but in monoculture concentrations. These changes may in turn affect ecosystem processes such as plant litter decomposition and nutrient cycling in grasslands. PMID:27164912

  4. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dron, J.; El Haddad, I.; Temime-Roussel, B.; Jaffrezo, J.-L.; Wortham, H.; Marchand, N.

    2010-08-01

    The functional group composition of various organic aerosols (OA) is investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS). The determinations of three functional groups contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups, R-COOH and R-CO-Ŕ respectively) and precursor ion (nitro groups, R-NO2) scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA) produced through photooxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounts for 1.7% (vehicular) to 13.5% (o-xylene photooxidation) of the organic carbon. Diagnostic functional group ratios are then used to tentatively discriminate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France) during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to discriminate sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assess a wood burning organic carbon contribution of about 60%. Finally, examples of functional group mass

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

    PubMed Central

    2014-01-01

    Graphene quantum dots (GQDs) have been developed as promising optical probes for bioimaging due to their excellent photoluminescent properties. Additionally, the fluorescence spectrum and quantum yield of GQDs are highly dependent on the surface functional groups on the carbon sheets. However, the distribution and cytotoxicity of GQDs functionalized with different chemical groups have not been specifically investigated. Herein, the cytotoxicity of three kinds of GQDs with different modified groups (NH2, COOH, and CO-N (CH3)2, respectively) in human A549 lung carcinoma cells and human neural glioma C6 cells was investigated using thiazoyl blue colorimetric (MTT) assay and trypan blue assay. The cellular apoptosis or necrosis was then evaluated by flow cytometry analysis. It was demonstrated that the three modified GQDs showed good biocompatibility even when the concentration reached 200 μg/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

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

    PubMed

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

    2015-12-15

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

  7. A novel joint sparse partial correlation method for estimating group functional networks.

    PubMed

    Liang, Xiaoyun; Connelly, Alan; Calamante, Fernando

    2016-03-01

    Advances in graph theory have provided a powerful tool to characterize brain networks. In particular, functional networks at group-level have great appeal to gain further insight into complex brain function, and to assess changes across disease conditions. These group networks, however, often have two main limitations. First, they are popularly estimated by directly averaging individual networks that are compromised by confounding variations. Secondly, functional networks have been estimated mainly through Pearson cross-correlation, without taking into account the influence of other regions. In this study, we propose a sparse group partial correlation method for robust estimation of functional networks based on a joint graphical models approach. To circumvent the issue of choosing the optimal regularization parameters, a stability selection method is employed to extract networks. The proposed method is, therefore, denoted as JGMSS. By applying JGMSS across simulated datasets, the resulting networks show consistently higher accuracy and sensitivity than those estimated using an alternative approach (the elastic-net regularization with stability selection, ENSS). The robustness of the JGMSS is evidenced by the independence of the estimated networks to choices of the initial set of regularization parameters. The performance of JGMSS in estimating group networks is further demonstrated with in vivo fMRI data (ASL and BOLD), which show that JGMSS can more robustly estimate brain hub regions at group-level and can better control intersubject variability than it is achieved using ENSS. PMID:26859311

  8. Testing Group Differences in Brain Functional Connectivity: Using Correlations or Partial Correlations?

    PubMed Central

    Kim, Junghi; Wozniak, Jeffrey R.; Mueller, Bryon A.

    2015-01-01

    Abstract Resting-state functional magnetic resonance imaging allows one to study brain functional connectivity, partly motivated by evidence that patients with complex disorders, such as Alzheimer's disease, may have altered functional brain connectivity patterns as compared with healthy subjects. A functional connectivity network describes statistical associations of the neural activities among distinct and distant brain regions. Recently, there is a major interest in group-level functional network analysis; however, there is a relative lack of studies on statistical inference, such as significance testing for group comparisons. In particular, it is still debatable which statistic should be used to measure pairwise associations as the connectivity weights. Many functional connectivity studies have used either (full or marginal) correlations or partial correlations for pairwise associations. This article investigates the performance of using either correlations or partial correlations for testing group differences in brain connectivity, and how sparsity levels and topological structures of the connectivity would influence statistical power to detect group differences. Our results suggest that, in general, testing group differences in networks deviates from estimating networks. For example, high regularization in both covariance matrices and precision matrices may lead to higher statistical power; in particular, optimally selected regularization (e.g., by cross-validation or even at the true sparsity level) on the precision matrices with small estimation errors may have low power. Most importantly, and perhaps surprisingly, using either correlations or partial correlations may give very different testing results, depending on which of the covariance matrices and the precision matrices are sparse. Specifically, if the precision matrices are sparse, presumably and arguably a reasonable assumption, then using correlations often yields much higher powered and more

  9. The Effect of Functional Groups in Bio-Derived Fuel Candidates.

    PubMed

    Jenkins, Rhodri W; Moore, Cameron M; Semelsberger, Troy A; Chuck, Christopher J; Gordon, John C; Sutton, Andrew D

    2016-05-10

    Interest in developing renewable fuels is continuing to grow and biomass represents a viable source of renewable carbon with which to replace fossil-based components in transportation fuels. During our own work, we noticed that chemists think in terms of functional groups whereas fuel engineers think in terms of physical fuel properties. In this Concept article, we discuss the effect of carbon and oxygen functional groups on potential fuel properties. This serves as a way of informing our own thinking and provides us with a basis with which to design and synthesize molecules from biomass that could provide useful transportation fuels. PMID:27099975

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

    PubMed Central

    Podila, R.; Chen, R.; Ke, P. C.; Brown, J. M.; Rao, A. M.

    2012-01-01

    Herein, we examined the dependence of protein adsorption on the nanoparticle surface in the presence of functional groups. Our UV-visible spectrophotometry, transmission electron microscopy, infrared spectroscopy, and dynamic light scattering measurements evidently suggested that the functional groups play an important role in the formation of nanoparticle-protein corona. We found that uncoated and surfactant-free silver nanoparticles derived from a laser ablation process promoted a maximum protein (bovine serum albumin) coating due to increased changes in entropy. On the other hand, bovine serum albumin displayed a relatively lower affinity for electrostatically stabilized nanoparticles due to the constrained entropy changes. PMID:23341687

  11. Multiconfiguration pair-density functional theory: barrier heights and main group and transition metal energetics.

    PubMed

    Carlson, Rebecca K; Li Manni, Giovanni; Sonnenberger, Andrew L; Truhlar, Donald G; Gagliardi, Laura

    2015-01-13

    Kohn-Sham density functional theory, resting on the representation of the electronic density and kinetic energy by a single Slater determinant, has revolutionized chemistry, but for open-shell systems, the Kohn-Sham Slater determinant has the wrong symmetry properties as compared to an accurate wave function. We have recently proposed a theory, called multiconfiguration pair-density functional theory (MC-PDFT), in which the electronic kinetic energy and classical Coulomb energy are calculated from a multiconfiguration wave function with the correct symmetry properties, and the rest of the energy is calculated from a density functional, called the on-top density functional, that depends on the density and the on-top pair density calculated from this wave function. We also proposed a simple way to approximate the on-top density functional by translation of Kohn-Sham exchange-correlation functionals. The method is much less expensive than other post-SCF methods for calculating the dynamical correlation energy starting with a multiconfiguration self-consistent-field wave function as the reference wave function, and initial tests of the theory were quite encouraging. Here, we provide a broader test of the theory by applying it to bond energies of main-group molecules and transition metal complexes, barrier heights and reaction energies for diverse chemical reactions, proton affinities, and the water dimerization energy. Averaged over 56 data points, the mean unsigned error is 3.2 kcal/mol for MC-PDFT, as compared to 6.9 kcal/mol for Kohn-Sham theory with a comparable density functional. MC-PDFT is more accurate on average than complete active space second-order perturbation theory (CASPT2) for main-group small-molecule bond energies, alkyl bond dissociation energies, transition-metal-ligand bond energies, proton affinities, and the water dimerization energy. PMID:26574206

  12. Importance of Having Low-Density Functional Groups for Generating High-Performance Semiconducting Polymer Dots

    PubMed Central

    Zhang, Xuanjun; Yu, Jiangbo; Wu, Changfeng; Jin, Yuhui; Rong, Yu; Ye, Fangmao

    2012-01-01

    Semiconducting polymers with low-density side-chain carboxylic acid groups were synthesized to form stable, functionalized, and highly fluorescent polymer dots (Pdots). The influence of the molar fraction of hydrophilic side-chains on Pdot properties and performance was systematically investigated. Our results show that the density of side-chain carboxylic acid groups significantly affects Pdot stability, internal structure, fluorescence brightness, and nonspecific binding in cellular labeling. Fluorescence spectroscopy, single-particle imaging, and a dye-doping method were employed to investigate the fluorescence brightness and the internal structure of the Pdots. The results of these experiments indicate that semiconducting polymers with low density of side-chain functional groups can form stable, compact, and highly bright Pdots as compared to those with high density of hydrophilic side-chains. The functionalized polymer dots were conjugated to streptavidin (SA) by carbodiimide-catalyzed coupling and the Pdot-SA probes effectively and specifically labeled the cancer cell-surface marker Her2 in human breast cancer cells. The carboxylate-functionalized polymer could also be covalently modified with small functional molecules to generate Pdot probes for click chemistry-based bioorthogonal labeling. This study presents a promising approach for further developing functional Pdot probes for biological applications. PMID:22607220

  13. Effect of Duration of Disease on Ventilatory Function in an Ethnic Saudi Group of Diabetic Patients

    PubMed Central

    Meo, Sultan A.; Al Drees, Abdul Majeed; Ahmed, Jehangeer; Ahmed Shah, Sayed Fayaz; Al-Regaiey, Khalid; Husain, Ashraf; Al-Rubean, Khalid

    2007-01-01

    Background Diabetes mellitus is a leading cause of illness and death across the world and is responsible for a growing proportion of global health care expenditures. The present study was designed to observe the effect of diabetes mellitus on lung function in patients with diabetes belonging to a specific ethnic group, namely Saudis. Method In this study, a group of 47 apparently healthy volunteer male Saudi patients with diabetes was randomly selected. Their ages ranged from 20 to 70 years. The patients were matched with another group of 50 healthy male control subjects in terms of age, height, weight, ethnicity, and socioeconomic status. Both groups met exclusion criteria as per standard. Spirometry was performed with an electronic spirometer (Schiller AT-2 Plus, Switzerland), and results were compared by a Student's t test. Results Subjects with diabetes showed a significant reduction in forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) relative to their matched controls. However, there were no significant differences in the forced expiratory ratio (FEV1/FVC%) and the middle half of the FVC (FEF25–75%) between the groups. We observed a significantly negative correlation between duration of disease and pulmonary function, as measured by FEV1 (r = 0.258, p = 0.04), FVC (r = 0.282, p = 0.28), and the middle half of the FVC (FEF25–75%) (r = 0.321, p = 0.014). Conclusions Pulmonary function in a specific ethnic group of patients with diabetes was impaired as evidenced by a decrease in FVC and FEV1 compared to pulmonary function in matched controls. Stratification of results by years of disease revealed a significant correlation between duration of disease and a decline in pulmonary function. PMID:19885139

  14. Pattern classification and recognition of invertebrate functional groups using self-organizing neural networks.

    PubMed

    Zhang, WenJun

    2007-07-01

    Self-organizing neural networks can be used to mimic non-linear systems. The main objective of this study is to make pattern classification and recognition on sampling information using two self-organizing neural network models. Invertebrate functional groups sampled in the irrigated rice field were classified and recognized using one-dimensional self-organizing map and self-organizing competitive learning neural networks. Comparisons between neural network models, distance (similarity) measures, and number of neurons were conducted. The results showed that self-organizing map and self-organizing competitive learning neural network models were effective in pattern classification and recognition of sampling information. Overall the performance of one-dimensional self-organizing map neural network was better than self-organizing competitive learning neural network. The number of neurons could determine the number of classes in the classification. Different neural network models with various distance (similarity) measures yielded similar classifications. Some differences, dependent upon the specific network structure, would be found. The pattern of an unrecognized functional group was recognized with the self-organizing neural network. A relative consistent classification indicated that the following invertebrate functional groups, terrestrial blood sucker; terrestrial flyer; tourist (nonpredatory species with no known functional role other than as prey in ecosystem); gall former; collector (gather, deposit feeder); predator and parasitoid; leaf miner; idiobiont (acarine ectoparasitoid), were classified into the same group, and the following invertebrate functional groups, external plant feeder; terrestrial crawler, walker, jumper or hunter; neustonic (water surface) swimmer (semi-aquatic), were classified into another group. It was concluded that reliable conclusions could be drawn from comparisons of different neural network models that use different distance

  15. Momentum subtraction scheme renormalization group functions in the maximal Abelian gauge

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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 Λ parameters in different schemes is also provided.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Many transformation reactions involving hydrocarbons occur in the presence of H2O in hydrothermal systems and deep sedimentary systems. We investigate these reactions using laboratory-based organic chemistry experiments at high temperature and pressure (300 °C and 100 MPa). Organic functional group transformation reactions using model organic compounds based on cyclohexane with one or two methyl groups provided regio- and stereochemical markers that yield information about reversibility and reaction mechanisms. We found rapidly reversible interconversion between alkanes, alkenes, dienes, alcohols, ketones, and enones. The alkane-to-ketone reactions were not only completely reversible, but also exhibited such extensive reversibility that any of the functional groups along the reaction path (alcohol, ketone, and even the diene) could be used as the reactant and form all the other groups as products. There was also a propensity for these ring-based structures to dehydrogenate; presumably from the alkene, through a diene, to an aromatic ring. The product suites provide strong evidence that water behaved as a reactant and the various functional groups showed differing degrees of reactivity. Mechanistically-revealing products indicated reaction mechanisms that involve carbon-centered cation intermediates. This work therefore demonstrates that a wide range of organic compound types can be generated by abiotic reactions at hydrothermal conditions.

  17. Evaluation of functional groups on amino acids in cyclic tetrapeptides in histone deacetylase inhibition.

    PubMed

    Islam, Md Shahidul; Bhuiyan, Mohammed P I; Islam, Md Nurul; Nsiama, Tienabe Kipassa; Oishi, Naoto; Kato, Tamaki; Nishino, Norikazu; Ito, Akihiro; Yoshida, Minoru

    2012-06-01

    The naturally occurring cyclic tetrapeptide, chlamydocin, originally isolated from fungus Diheterospora chlamydosphoria, consists of α-aminoisobutyric acid, L-phenylalanine, D-proline and an unusual amino acid (S)-2-amino-8-((S)-oxiran-2-yl)-8-oxooctanoic acid (Aoe) and inhibits the histone deacetylases (HDACs), a class of regulatory enzymes. The epoxyketone moiety of Aoe is the key functional group for inhibition. The cyclic tetrapeptide scaffold is supposed to play important role for effective binding to the surface of enzymes. In place of the epoxyketone group, hydroxamic acid and sulfhydryl group have been applied to design inhibitor ligands to zinc atom in catalytic site of HDACs. In the research for more potent HDAC inhibitors, we replaced the epoxyketone moiety of Aoe with different functional groups and synthesized a series of chlamydocin analogs as HDAC inhibitors. Among the functional groups, methoxymethylketone moiety showed as potent inhibition as the hydroxamic acid. On the contrary, we confirmed that borate, trifruoromethylketone, and 2-aminoanilide are almost inactive in HDAC inhibition. PMID:21638021

  18. Increased acetyl group availability enhances contractile function of canine skeletal muscle during ischemia.

    PubMed

    Timmons, J A; Poucher, S M; Constantin-Teodosiu, D; Worrall, V; Macdonald, I A; Greenhaff, P L

    1996-02-01

    Skeletal muscle contractile function is impaired during acute ischemia such as that experienced by peripheral vascular disease patients. We therefore, examined the effects of dichloroacetate, which can alter resting metabolism, on canine gracilis muscle contractile function during constant flow ischemia. Pretreatment with dichloroacetate increased resting pyruvate dehydrogenase complex activity and resting acetylcarnitine concentration by approximately 4- and approximately 10-fold, respectively. After 20-min contraction the control group had demonstrated an approximately 40% reduction in isomeric tension whereas the dichloroacetate group had fatigued by approximately 25% (P < 0.05). Dichloroacetate resulted in less lactate accumulation (10.3 +/- 3.0 vs 58.9 +/- 10.5 mmol.kg-1 dry muscle [dm], P < 0.05) and phosphocreatine hydrolysis (15.6 +/- 6.3 vs 33.8 +/- 9.0 mmol.kg-1 dm, P < 0.05) during contraction. Acetylcarnitine concentration fell during contraction by 5.4 +/- 1.8 mmol.kg-1 dm in the dichloroacetate group but increased by 10.0 +/- 1.9 mmol.kg-1 dm in the control group. In conclusion, dichloroacetate enhanced contractile function during ischemia, independently of blood flow, such that it appears oxidative ATP regeneration is limited by pyruvate dehydrogenase complex activity and acetyl group availability. PMID:8609248

  19. Human promoter genomic composition demonstrates non-random groupings that reflect general cellular function

    PubMed Central

    McNutt, Markey C; Tongbai, Ron; Cui, Wenwu; Collins, Irene; Freebern, Wendy J; Montano, Idalia; Haggerty, Cynthia M; Chandramouli, GVR; Gardner, Kevin

    2005-01-01

    Background The purpose of this study is to determine whether or not there exists nonrandom grouping of cis-regulatory elements within gene promoters that can be perceived independent of gene expression data and whether or not there is any correlation between this grouping and the biological function of the gene. Results Using ProSpector, a web-based promoter search and annotation tool, we have applied an unbiased approach to analyze the transcription factor binding site frequencies of 1400 base pair genomic segments positioned at 1200 base pairs upstream and 200 base pairs downstream of the transcriptional start site of 7298 commonly studied human genes. Partitional clustering of the transcription factor binding site composition within these promoter segments reveals a small number of gene groups that are selectively enriched for gene ontology terms consistent with distinct aspects of cellular function. Significance ranking of the class-determining transcription factor binding sites within these clusters show substantial overlap between the gene ontology terms of the transcriptions factors associated with the binding sites and the gene ontology terms of the regulated genes within each group. Conclusion Thus, gene sorting by promoter composition alone produces partitions in which the "regulated" and the "regulators" cosegregate into similar functional classes. These findings demonstrate that the transcription factor binding site composition is non-randomly distributed between gene promoters in a manner that reflects and partially defines general gene class function. PMID:16232321

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

    ERIC Educational Resources Information Center

    Richdale, Amanda L.; Prior, Margot R.

    1992-01-01

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

  1. Group-Specific Effects of Matching Subtest Contamination on the Identification of Differential Item Functioning

    ERIC Educational Resources Information Center

    Keiffer, Elizabeth Ann

    2011-01-01

    A differential item functioning (DIF) simulation study was conducted to explore the type and level of impact that contamination had on type I error and power rates in DIF analyses when the suspect item favored the same or opposite group as the DIF items in the matching subtest. Type I error and power rates were displayed separately for the…

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

    ERIC Educational Resources Information Center

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

    2006-01-01

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

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

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

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

    ERIC Educational Resources Information Center

    Gafni, Naomi; Estela, Melamed

    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…

  5. An Epistemological Inquiry into Organic Chemistry Education: Exploration of Undergraduate Students' Conceptual Understanding of Functional Groups

    ERIC Educational Resources Information Center

    Akkuzu, Nalan; Uyulgan, Melis Arzu

    2016-01-01

    This study sought to determine the levels of conceptual understanding of undergraduate students regarding organic compounds within different functional groups. A total of 60 students who were enrolled in the Department of Secondary Science and Mathematics Education of a Faculty of Education at a state university in Turkey and who had followed an…

  6. 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...

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

    ERIC Educational Resources Information Center

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

    2012-01-01

    This study examined the mediating and moderating role of social resources on the association between age and change in functional health for three age groups of older adults. Data were provided by those in their 60s, 80s, and 100s who participated in the first two phases of the Georgia Centenarian study. Analyses confirmed the study's hypothesis…

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

    ERIC Educational Resources Information Center

    Cappadocia, M. Catherine; Weiss, Jonathan A.

    2011-01-01

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

  9. 14 CFR 10 - Functional Classification-Operating Expenses of Group I Air Carriers

    Code of Federal Regulations, 2012 CFR

    2012-01-01

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

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  11. 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...

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

    ERIC Educational Resources Information Center

    Li, Hongli; Suen, Hoi K.

    2013-01-01

    Differential skill functioning (DSF) exists when examinees from different groups have different probabilities of successful performance in a certain subskill underlying the measured construct, given that they have the same ability on the overall construct. Using a DSF approach, this study examined the differences between two native language…

  13. Youth in group home care: youth characteristics and predictors of later functioning.

    PubMed

    Chow, Wai-Ying; Mettrick, Jennifer E; Stephan, Sharon H; Von Waldner, Christina A

    2014-10-01

    This paper presents the findings of an exploratory research study of foster care youth residing in group homes in a mid-Atlantic state in the USA. The aims of the present study were to (1) describe youth characteristics, (2) explore whether baseline functioning differed by gender or ethnicity, (3) explore predictors of cross-time differences in psychosocial functioning, and (4) explore predictors of later functioning, specifically age, gender, and length of stay. Psychosocial functioning at two time points (i.e., T1 = admission into group home; T2 = current or discharge) in 180 charts from 29 randomly selected group homes were reviewed. Youth were on average 14.86 years of age, predominantly male (71%; n = 128), and predominantly African American (79%). Findings suggest that group home placement may benefit some youth but not others, particularly girls and younger children with lower initial level of need. Findings underscore the potential complexity of intervention impact in the context of unique youth, family, and environment factors. PMID:22529035

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

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Functional Classification-Operating Expenses of Group I Air Carriers Section 10 Section 10 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS UNIFORM SYSTEM OF ACCOUNTS AND REPORTS FOR LARGE CERTIFICATED AIR CARRIERS...

  15. Simple plant traits explain functional group diversity decline in novel grassland communities of Texas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent work on novel ecosystems suggests that exotic species contribute to functional group diversity decline as exotic systems replace native ones. We experimentally compared 18 exotic and 18 native prairie species paired for phylogeny, growth form, and mode of photosynthesis grown both in monocul...

  16. 43 CFR 1784.6 - Membership and functions of resource advisory councils and sub-groups.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Membership and functions of resource advisory councils and sub-groups. 1784.6 Section 1784.6 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR GENERAL MANAGEMENT...

  17. 43 CFR 1784.6 - Membership and functions of resource advisory councils and sub-groups.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Membership and functions of resource advisory councils and sub-groups. 1784.6 Section 1784.6 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR GENERAL MANAGEMENT (1000) COOPERATIVE RELATIONS Advisory Committees...

  18. Functional group analysis in coal by sup 31 P NMR spectroscopy

    SciTech Connect

    Verkade, J.G.

    1989-05-01

    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.

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

    SciTech Connect

    Verkade, J.G.

    1990-01-01

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

  20. 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...

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

    ERIC Educational Resources Information Center

    Davis, John M.

    1984-01-01

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

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

    ERIC Educational Resources Information Center

    Knudtson, Christopher A.

    2015-01-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. Detection of Differential Item Functioning for More than Two Groups: A Monte Carlo Comparison of Methods

    ERIC Educational Resources Information Center

    Finch, W. Holmes

    2016-01-01

    Differential item functioning (DIF) assessment is a crucial component in test construction, serving as the primary way in which instrument developers ensure that measures perform in the same way for multiple groups within the population. When such is not the case, scores may not accurately reflect the trait of interest for all individuals in the…

  5. Structural and functional evolution of the P2Y12-like receptor group

    PubMed Central

    Hermsdorf, Thomas; Engemaier, Eva; Engel, Kathrin; Liebscher, Ines; Thor, Doreen; Zierau, Klaas; Römpler, Holger; Schulz, Angela

    2007-01-01

    Metabotropic pyrimidine and purine nucleotide receptors (P2Y receptors) belong to the superfamily of G protein-coupled receptors (GPCR). They are distinguishable from adenosine receptors (P1) as they bind adenine and/or uracil nucleotide triphosphates or diphosphates depending on the subtype. Over the past decade, P2Y receptors have been cloned from a variety of tissues and species, and as many as eight functional subtypes have been characterized. Most recently, several members of the P2Y12-like receptor group, which includes the clopidogrel-sensitive ADP receptor P2Y12, have been deorphanized. The P2Y12-like receptor group comprises several structurally related GPCR which, however, display heterogeneous agonist specificity including nucleotides, their derivatives, and lipids. Besides the established function of P2Y12 in platelet activation, expression in macrophages, neuronal and glial cells as well as recent results from functional studies implicate that several members of this group may have specific functions in neurotransmission, inflammation, chemotaxis, and response to tissue injury. This review focuses specifically on the structure-function relation and shortly summarizes some aspects of the physiological relevance of P2Y12-like receptor members. PMID:18404440

  6. A meta-analysis of functional group responses to forest recovery outside of the tropics.

    PubMed

    Spake, Rebecca; Ezard, Thomas H G; Martin, Philip A; Newton, Adrian C; Doncaster, C Patrick

    2015-12-01

    Both active and passive forest restoration schemes are used in degraded landscapes across the world to enhance biodiversity and ecosystem service provision. Restoration is increasingly also being implemented in biodiversity offset schemes as compensation for loss of natural habitat to anthropogenic development. This has raised concerns about the value of replacing old-growth forest with plantations, motivating research on biodiversity recovery as forest stands age. Functional diversity is now advocated as a key metric for restoration success, yet it has received little analytical attention to date. We conducted a meta-analysis of 90 studies that measured differences in species richness for functional groups of fungi, lichens, and beetles between old-growth control and planted or secondary treatment forests in temperate, boreal, and Mediterranean regions. We identified functional-group-specific relationships in the response of species richness to stand age after forest disturbance. Ectomycorrhizal fungi averaged 90 years for recovery to old-growth values (between 45 years and unrecoverable at 95% prediction limits), and epiphytic lichens took 180 years to reach 90% of old-growth values (between 140 years and never for recovery to old-growth values at 95% prediction limits). Non-saproxylic beetle richness, in contrast, decreased as stand age of broadleaved forests increased. The slow recovery by some functional groups essential to ecosystem functioning makes old-growth forest an effectively irreplaceable biodiversity resource that should be exempt from biodiversity offsetting initiatives. PMID:26040756

  7. Health and role functioning: the use of focus groups in the development of an item bank

    PubMed Central

    Bjorner, Jakob B.

    2013-01-01

    Background Role functioning is an important part of health-related quality of life. However, assessment of role functioning is complicated by the wide definition of roles and by fluctuations in role participation across the life-span. The aim of this study is to explore variations in role functioning across the lifespan using qualitative approaches, to inform the development of a role functioning item bank and to pilot test sample items from the bank. Methods Eight focus groups were conducted with a convenience sample of 38 English-speaking adults recruited in Rhode Island. Participants were stratified by gender and four age groups. Focus groups were taped, transcribed, and analyzed for thematic content. Results Participants of all ages identified family roles as the most important. There was age variation in the importance of social life roles, with younger and older adults rating them as more important. Occupational roles were identified as important by younger and middle-aged participants. The potential of health problems to affect role participation was recognized. Participants found the sample items easy to understand, response options identical in meaning and preferred five response choices. Conclusions Participants identified key aspects of role functioning and provided insights on their perception of the impact of health on their role participation. These results will inform item bank generation. PMID:20047086

  8. Effect of Habitat Size, Quality, and Isolation on Functional Groups of Beetles in Hollow Oaks.

    PubMed

    Pilskog, Hanne Eik; Birkemoe, Tone; Framstad, Erik; Sverdrup-Thygeson, Anne

    2016-01-01

    One of the largest threats to biodiversity is land use change and habitat loss. Hollow oaks (Quercus spp. L.) are well-defined patches that are hotspots for biodiversity and red-listed species, but they are often rare and fragmented in the landscape. We investigated the effect of patch size, habitat quality, and isolation on functional groups and red-listed saproxylic beetles in hollow oaks (n = 40) in Norway. The groups were defined by host tree association, trophic grouping, and red-listed status. Habitat quality, represented by tree form was most important in explaining species richness for most groups. Patch size, represented by circumference and amount of dead branches, was most important in explaining abundance. Isolation, that is single oaks compared with oaks in groups, had a negative effect on the abundance of beetles feeding both on wood and fungi (xylomycethopagous), as well as on species associated with broadleaved trees (oak semi-specialists), but did not affect species richness. This indicates that at this scale and in this landscape, isolated oaks are as species rich and valuable for conservation as other oaks, although some functional groups may be more vulnerable to isolation than others. The red-listed species only responded to patch size, indicating that oaks with large circumference and many dead branches are especially important for red-listed species and for conservation. PMID:26945089

  9. Effect of Habitat Size, Quality, and Isolation on Functional Groups of Beetles in Hollow Oaks

    PubMed Central

    Pilskog, Hanne Eik; Birkemoe, Tone; Framstad, Erik; Sverdrup-Thygeson, Anne

    2016-01-01

    One of the largest threats to biodiversity is land use change and habitat loss. Hollow oaks (Quercus spp. L.) are well-defined patches that are hotspots for biodiversity and red-listed species, but they are often rare and fragmented in the landscape. We investigated the effect of patch size, habitat quality, and isolation on functional groups and red-listed saproxylic beetles in hollow oaks (n = 40) in Norway. The groups were defined by host tree association, trophic grouping, and red-listed status. Habitat quality, represented by tree form was most important in explaining species richness for most groups. Patch size, represented by circumference and amount of dead branches, was most important in explaining abundance. Isolation, that is single oaks compared with oaks in groups, had a negative effect on the abundance of beetles feeding both on wood and fungi (xylomycethopagous), as well as on species associated with broadleaved trees (oak semi-specialists), but did not affect species richness. This indicates that at this scale and in this landscape, isolated oaks are as species rich and valuable for conservation as other oaks, although some functional groups may be more vulnerable to isolation than others. The red-listed species only responded to patch size, indicating that oaks with large circumference and many dead branches are especially important for red-listed species and for conservation. PMID:26945089

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

    USGS Publications Warehouse

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

    2008-01-01

    Black carbon (pyrogenic materials including chars) in soils has been recognized as a substantial portion of soil organic matter, and has been shown to play a vital role in nutrient cycling; however, little is known concerning the properties of this material. Previous studies have largely been concerned with the creation of high-surface-area materials for use as sorbents. These materials have been manufactured at high temperature and have often been activated. Chars occurring in the environment can be formed over a wide range of temperature. Because it is extremely difficult to isolate black carbon once it has been incorporated in soils, chars produced in the laboratory under controlled conditions can be used to investigate the range of properties possible for natural chars. This report shows that charring conditions (temperature and time) have substantial impact on the acid functional group and lactone content of chars. Low temperatures (250?C) and long charring times (greater than 72 hours) produce chars with the highest acid functional group and lactone content. The charring of cellulose appears to be responsible for the creation of the acid functional group and lactones. The significance of this study is that low-temperature chars can have acid functional group contents comparable to humic materials (as high as 8.8 milliequivalents per gram). Acid functional group and lactone content decreases as charring temperature increases. The variation in formation conditions expected under natural fire conditions will result in a wide range of sorption properties for natural chars which are an important component of soil organic matter. By controlling the temperature and duration of charring, it is possible to tailor the sorption properties of chars, which may be used as soil amendments.

  11. Easy route to functionalize iron oxide nanoparticles via long-term stable thiol groups.

    PubMed

    Maurizi, L; Bisht, H; Bouyer, F; Millot, N

    2009-08-18

    The functionalization of superparamagnetic iron oxide nanoparticles (SPIOs) by meso-2,3-dimercaptosuccinic acid (DMSA) was investigated. Under ambient conditions, the thiol groups from DMSA are not stable and do not allow a direct functionalization without storage in stringent conditions or a chemical regeneration of free thiols. In this study, we have developed a protocol based on poly(ethylene glycol) (PEG) grafting of SPIO prior to DMSA anchoring. We have observed that PEG helps to increase the stability of thiol groups under ambient conditions. The thiol functionalized SPIOs were stable under physiological pH and ionic strength as determined by Ellman's essay and allowed us to graft a thiol reactive fluorescent dye: tetramethylrhodamine-5-maleimide (TMRM). PMID:19572525

  12. Quantification of protein group coherence and pathway assignment using functional association

    PubMed Central

    2011-01-01

    Background Genomics and proteomics experiments produce a large amount of data that are awaiting functional elucidation. An important step in analyzing such data is to identify functional units, which consist of proteins that play coherent roles to carry out the function. Importantly, functional coherence is not identical with functional similarity. For example, proteins in the same pathway may not share the same Gene Ontology (GO) terms, but they work in a coordinated fashion so that the aimed function can be performed. Thus, simply applying existing functional similarity measures might not be the best solution to identify functional units in omics data. Results We have designed two scores for quantifying the functional coherence by considering association of GO terms observed in two biological contexts, co-occurrences in protein annotations and co-mentions in literature in the PubMed database. The counted co-occurrences of GO terms were normalized in a similar fashion as the statistical amino acid contact potential is computed in the protein structure prediction field. We demonstrate that the developed scores can identify functionally coherent protein sets, i.e. proteins in the same pathways, co-localized proteins, and protein complexes, with statistically significant score values showing a better accuracy than existing functional similarity scores. The scores are also capable of detecting protein pairs that interact with each other. It is further shown that the functional coherence scores can accurately assign proteins to their respective pathways. Conclusion We have developed two scores which quantify the functional coherence of sets of proteins. The scores reflect the actual associations of GO terms observed either in protein annotations or in literature. It has been shown that they have the ability to accurately distinguish biologically relevant groups of proteins from random ones as well as a good discriminative power for detecting interacting pairs of

  13. Kelvin-probe force microscopy of the pH-dependent charge of functional groups

    NASA Astrophysics Data System (ADS)

    Stone, Alexander D. D.; Mesquida, Patrick

    2016-06-01

    Kelvin-probe Force Microscopy (KFM) is an established method to map surface potentials or surface charges at high, spatial resolution. However, KFM does not work in water, which restricts its applicability considerably, especially when considering common, functional chemical groups in biophysics such as amine or carboxy groups, whose charge depends on pH. Here, we demonstrate that the KFM signal of such groups taken in air after exposure to water correlates qualitatively with their expected charge in water for a wide range of pH values. The correlation was tested with microcontact-printed thiols exposing amine and carboxy groups. Furthermore, it was shown that collagen fibrils, as an example of a biological material, exhibit a particular, pH-sensitive surface charge pattern, which could be caused by the particular arrangement of ionizable residues on the collagen fibril surface.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

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

    SciTech Connect

    Fifield, Leonard S.; Grate, Jay W.

    2010-06-01

    Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.

  16. Effects of trehalose polycation end-group functionalization on plasmid DNA uptake and transfection.

    PubMed

    Anderson, Kevin; Sizovs, Antons; Cortez, Mallory; Waldron, Chris; Haddleton, D M; Reineke, Theresa M

    2012-08-13

    In this study, we have synthesized six analogs of a trehalose-pentaethylenehexamine glycopolymer (Tr4) that contain (1A) adamantane, (1B) carboxy, (1C) alkynyl-oligoethyleneamine, (1D) azido trehalose, (1E) octyl, or (1F) oligoethyleneamine end groups and evaluated the effects of polymer end group chemistry on the ability of these systems to bind, compact, and deliver pDNA to cultured HeLa cells. The polymers were synthesized in one-pot azide-alkyne cycloaddition reactions with an adaptation of the Carothers equation for step-growth polymerization to produce a series of polymers with similar degrees of polymerization. An excess of end-capping monomer was added at the end of the polymerizations to maximize functionalization efficiency, which was evaluated with GPC, NMR, and MALDI-TOF. The polymers were all found to bind and compact pDNA at similarly low N/P ratios and form polyplexes with plasmid DNA. The effects of the different end group structures were most evident in the polyplex internalization and transfection assays in the presence of serum as determined by flow cytometry and luciferase gene expression, respectively. The Tr4 polymers end-capped with carboxyl groups (1B) (N/P = 7), octyne (1E) (N/P = 7), and oligoethyleneamine (1F) (N/P = 7), were taken into cells as polyplex and exhibited the highest levels of fluorescence, resulting from labeled plasmid. Similarly, the polymers end-functionalized with carboxyl groups (1E at N/P = 7), octyl groups (1E at N/P = 15), and in particular oligoethyleneamine groups (1F at N/P = 15) yielded dramatically higher reporter gene expression in the presence of serum. This study yields insight into how very subtle structural changes in polymer chemistry, such as end groups can yield very significant differences in the biological delivery efficiency and transgene expression of polymers used for pDNA delivery. PMID:22616977

  17. Matrix Intensification Alters Avian Functional Group Composition in Adjacent Rainforest Fragments

    PubMed Central

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  19. Quantity of Hydrophobic Functional CH-Groups - Decisive for Soil Water Repellency Caused by Digestate Amendment

    NASA Astrophysics Data System (ADS)

    Voelkner, Amrei; Holthusen, Dörthe; Ellerbrock, Ruth H.; Horn, Rainer

    2015-04-01

    Anaerobic digestates are used as organic fertilizers; however, they are suspected to interfere negatively with soils. To investigate the relevance of the anaerobic digestates composition on potential wettability and contact angle of the soil, we mixed in a laboratory experiment 30 m³ ha-1 of anaerobic digestates derived from mechanically pre-treated substrates from maize and sugar beet with a homogenized Cambic Luvisol. Fourier transform infrared-spectra and diffuse reflectance infrared Fourier transform-spectra of particle intact and finely ground soilanaerobic digestates-mixtures were analyzed to determine the quantities of hydrophobic functional groups in the soil-anaerobic digestates-mixtures that are used here as an indicator for the potential hydrophobicity. The anaerobic digestates application increased the amount of hydrophobic functional groups of the mixtures and reduced the wettability of the soil. However, for intact particle samples an up to threefold higher amount of hydrophobic groups was found as compared to the finely ground ones, indicating a dilution effect of mechanical grinding on the effectivity of the organic matter that is presumably located as a coating on mineral soil particles. For the particle intact samples, the intensity of hydrophobic functional groups bands denoting hydrophobic brickstones in organic matter is indicative for the actual wettability of the soil-anaerobic digestates-mixtures.

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

    PubMed

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

    2013-08-15

    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

  1. Tunable Oxygen Functional Groups as Electrocatalysts on Graphite Felt Surfaces for All-Vanadium Flow Batteries.

    PubMed

    Estevez, Luis; Reed, David; Nie, Zimin; Schwarz, Ashleigh M; Nandasiri, Manjula I; Kizewski, James P; Wang, Wei; Thomsen, Edwin; Liu, Jun; Zhang, Ji-Guang; Sprenkle, Vincent; Li, Bin

    2016-06-22

    A dual oxidative approach using O2 plasma followed by treatment with H2 O2 to impart oxygen functional groups onto the surface of a graphite felt electrode. When used as electrodes for an all-vanadium redox flow battery (VRB) system, the energy efficiency of the cell is enhanced by 8.2 % at a current density of 150 mA cm(-2) compared with one oxidized by thermal treatment in air. More importantly, by varying the oxidative techniques, the amount and type of oxygen groups was tailored and their effects were elucidated. It was found that O-C=O groups improve the cells performance whereas the C-O and C=O groups degrade it. The reason for the increased performance was found to be a reduction in the cell overpotential after functionalization of the graphite felt electrode. This work reveals a route for functionalizing carbon electrodes to improve the performance of VRB cells. This approach can lower the cost of VRB cells and pave the way for more commercially viable stationary energy storage systems that can be used for intermittent renewable energy storage. PMID:27184225

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Foo, Guo Shiou; Sievers, Carsten

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  7. Linking avian communities and avian influenza ecology in southern Africa using epidemiological functional groups

    PubMed Central

    2012-01-01

    The ecology of pathogens, and particularly their emergence in multi-host systems, is complex. New approaches are needed to reduce superficial complexities to a level that still allows scientists to analyse underlying and more fundamental processes. One promising approach for simplification is to use an epidemiological-function classification to describe ecological diversity in a way that relates directly to pathogen dynamics. In this article, we develop and apply the epidemiological functional group (EFG) concept to explore the relationships between wild bird communities and avian influenza virus (AIV) in three ecosystems in southern Africa. Using a two year dataset that combined bird counts and bimonthly sampling for AIV, we allocated each bird species to a set of EFGs that captured two overarching epidemiological functions: the capacity of species to maintain AIV in the system, and their potential to introduce the virus. Comparing AIV prevalence between EFGs suggested that the hypothesis that anseriforms (ducks) and charadriiforms (waders) drive AIV epidemiology cannot entirely explain the high prevalence observed in some EFGs. If anseriforms do play an important role in AIV dynamics in each of the three ecosystems, the role of other species in the local maintenance of AIV cannot be ruled out. The EFG concept thus helped us to identify gaps in knowledge and to highlight understudied bird groups that might play a role in AIV epidemiology. In general, the use of EFGs has potential for generating a range of valuable insights in epidemiology, just as functional group approaches have done in ecology. PMID:23101696

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

    PubMed Central

    2012-01-01

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

  9. Control of oxo-group functionalization and reduction of the uranyl ion.

    PubMed

    Arnold, Polly L; Pécharman, Anne-Frédérique; Lord, Rianne M; Jones, Guy M; Hollis, Emmalina; Nichol, Gary S; Maron, Laurent; Fang, Jian; Davin, Thomas; Love, Jason B

    2015-04-01

    Uranyl complexes of a large, compartmental N8-macrocycle adopt a rigid, "Pacman" geometry that stabilizes the U(V) oxidation state and promotes chemistry at a single uranyl oxo-group. We present here new and straightforward routes to singly reduced and oxo-silylated uranyl Pacman complexes and propose mechanisms that account for the product formation, and the byproduct distributions that are formed using alternative reagents. Uranyl(VI) Pacman complexes in which one oxo-group is functionalized by a single metal cation are activated toward single-electron reduction. As such, the addition of a second equivalent of a Lewis acidic metal complex such as MgN″2 (N″ = N(SiMe3)2) forms a uranyl(V) complex in which both oxo-groups are Mg functionalized as a result of Mg-N bond homolysis. In contrast, reactions with the less Lewis acidic complex [Zn(N″)Cl] favor the formation of weaker U-O-Zn dative interactions, leading to reductive silylation of the uranyl oxo-group in preference to metalation. Spectroscopic, crystallographic, and computational analysis of these reactions and of oxo-metalated products isolated by other routes have allowed us to propose mechanisms that account for pathways to metalation or silylation of the exo-oxo-group. PMID:25799215

  10. Effects of functional groups and soluble matrices in fish otolith on calcium carbonate mineralization.

    PubMed

    Ren, Dongni; Li, Zhuo; Gao, Yonghua; Feng, Qingling

    2010-10-01

    Calcium carbonate mineralization is significantly influenced by organic matrices in vivo. The effect mainly relies on functional groups in proteins. In order to study the influence of functional groups on calcium carbonate mineralization, -OH, -NH2 and -COOH groups were grafted onto single crystal silicon chips, and such modified chips were used as substrates in in vitro mineralization experiments. An x-ray photoelectron spectroscopy (XPS) test was conducted to examine the grafting efficiency, and the three groups were successfully grafted. Calcium carbonate mineralization on a modified silicon substrate was examined by a scanning electron microscope (SEM) and x-ray diffraction (XRD), and the results showed that the effects of -OH, -NH2 and -COOH groups were quite different. Furthermore, a water-soluble protein matrix (WSM) and an acid-soluble protein matrix (ASM) extracted from fish otolith were adsorbed onto the -COOH-modified silicon substrate, and the effects of the protein matrices on calcium carbonate mineralization were studied. The results showed that both WSM and ASM of lapillus could mediate aragonite crystallization, but the size and morphology of the formed crystals were different. The WSM and ASM of asteriscus adsorbed on the silicon substrate had little effect on calcium carbonate mineralization; almost all the crystals were calcite, while both asteriscus WSM and ASM in solution could mediate vaterite crystals, and the morphologies of vaterite crystal aggregates were different. PMID:20844320