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Sample records for product cation partitioning

  1. Electron Transfer Dissociation: Effects of Cation Charge State on Product Partitioning in Ion/Ion Electron Transfer to Multiply Protonated Polypeptides

    PubMed Central

    Liu, Jian; McLuckey, Scott A.

    2012-01-01

    The effect of cation charge state on product partitioning in the gas-phase ion/ion electron transfer reactions of multiply protonated tryptic peptides, model peptides, and relatively large peptides with singly charged radical anions has been examined. In particular, partitioning into various competing channels, such as proton transfer (PT) versus electron transfer (ET), electron transfer with subsequent dissociation (ETD) versus electron transfer with no dissociation (ET,noD), and fragmentation of backbone bonds versus fragmentation of side chains, was measured quantitatively as a function of peptide charge state to allow insights to be drawn about the fundamental aspects of ion/ion reactions that lead to ETD. The ET channel increases relative to the PT channel, ETD increases relative to ET,noD, and fragmentation at backbone bonds increases relative to side-chain cleavages as cation charge state increases. The increase in ET versus PT with charge state is consistent with a Landau-Zener based curve-crossing model. An optimum charge state for ET is predicted by the model for the ground state-to-ground state reaction. However, when the population of excited product ion states is considered, it is possible that a decrease in ET efficiency as charge state increases will not be observed due to the possibility of the population of excited electronic states of the products. Several factors can contribute to the increase in ETD versus ET,noD and backbone cleavage versus side-chain losses. These factors include an increase in reaction exothermicity and charge state dependent differences in precursor and product ion structures, stabilities, and sites of protonation. PMID:23264749

  2. CATION TRANSPORT AND PARTITIONING DURING A FIELD TEST OF ELECTROOSMOSIS

    EPA Science Inventory

    Field experiments were conducted to evaluate the effects of soil properties, such as the cation exchange capacity and mineral content, on pH, soluble ion concentrations, and electrical conductivity during electroosmosis in a silty clay soil. The soil is composed mainly of quartz ...

  3. CATION TRANSPORT AND PARTITIONING DURING A FIELD TEST OF ELECTROOSMOSIS

    EPA Science Inventory

    Field experiments were conducted to evaluate the effects of soil properties, such as the cation exchange capacity and mineral content, on pH, soluble ion concentrations, and electrical conductivity during electroosmosis in a silty clay soil. The soil is composed mainly of quartz ...

  4. Modeling the selective partitioning of cations into negatively charged nanopores in water

    NASA Astrophysics Data System (ADS)

    Yang, Lu; Garde, Shekhar

    2007-02-01

    Partitioning and transport of water and small solutes into and through nanopores are important to a variety of chemical and biological processes and applications. Here we study water structure in negatively charged model cylindrical [carbon nanotube (CNT)-like] nanopores, as well as the partitioning of positive ions of increasing size (Na+, K+, and Cs+) into the pore interior using extensive molecular dynamics simulations. Despite the simplicity of the simulation system—containing a short CNT-like nanopore in water carrying a uniformly distributed charge of qpore=-ne surrounded by n (=0,…,8) cations, making the overall system charge neutral—the results provide new and useful insights on both the pore hydration and ion partitioning. For n =0, that is, for a neutral nanopore, water molecules partition into the pore and form single-file hydrogen-bonded wire spanning the pore length. With increasing n, water molecules enter the pore from both ends with preferred orientations, resulting in a mutual repulsion between oriented water molecules at the pore center and creating a cavity-like low density region at the center. For low negative charge densities on the pore, the driving force for partitioning of positive ions into the pore is weak, and no partitioning is observed. Increasing the pore charge gradually leads to partitioning of positive ions into the pore. Interestingly, over a range of intermediate negative charge densities, nanopores display both thermodynamic as well as kinetic selectivity toward partitioning of the larger K+ and Cs+ ions into their interior over the smaller Na+ ions. Specifically, the driving force is in the order K+>Cs+>Na+, and K+ and Cs+ ions enter the pore much more rapidly than Na+ ions. At higher charge densities, the driving force for partitioning increases for all cations—it is highest for K+ ions—and becomes similar for Na+ and Cs+ ions. The variation of thermodynamic driving force and the average partitioning time with the

  5. Partitioning in parallel processing of production systems

    SciTech Connect

    Oflazer, K.

    1987-01-01

    This thesis presents research on certain issues related to parallel processing of production systems. It first presents a parallel production system interpreter that has been implemented on a four-processor multiprocessor. This parallel interpreter is based on Forgy's OPS5 interpreter and exploits production-level parallelism in production systems. Runs on the multiprocessor system indicate that it is possible to obtain speed-up of around 1.7 in the match computation for certain production systems when productions are split into three sets that are processed in parallel. The next issue addressed is that of partitioning a set of rules to processors in a parallel interpreter with production-level parallelism, and the extent of additional improvement in performance. The partitioning problem is formulated and an algorithm for approximate solutions is presented. The thesis next presents a parallel processing scheme for OPS5 production systems that allows some redundancy in the match computation. This redundancy enables the processing of a production to be divided into units of medium granularity each of which can be processed in parallel. Subsequently, a parallel processor architecture for implementing the parallel processing algorithm is presented.

  6. Time Domain Partitioning of Electricity Production Cost Simulations

    SciTech Connect

    Barrows, C.; Hummon, M.; Jones, W.; Hale, E.

    2014-01-01

    Production cost models are often used for planning by simulating power system operations over long time horizons. The simulation of a day-ahead energy market can take several weeks to compute. Tractability improvements are often made through model simplifications, such as: reductions in transmission modeling detail, relaxation of commitment variable integrality, reductions in cost modeling detail, etc. One common simplification is to partition the simulation horizon so that weekly or monthly horizons can be simulated in parallel. However, horizon partitions are often executed with overlap periods of arbitrary and sometimes zero length. We calculate the time domain persistence of historical unit commitment decisions to inform time domain partitioning of production cost models. The results are implemented using PLEXOS production cost modeling software in an HPC environment to improve the computation time of simulations while maintaining solution integrity.

  7. Generalized Enhanced Multivariance Product Representation for Data Partitioning: Constancy Level

    SciTech Connect

    Tunga, M. Alper; Demiralp, Metin

    2011-09-14

    Enhanced Multivariance Product Representation (EMPR) method is used to represent multivariate functions in terms of less-variate structures. The EMPR method extends the HDMR expansion by inserting some additional support functions to increase the quality of the approximants obtained for dominantly or purely multiplicative analytical structures. This work aims to develop the generalized form of the EMPR method to be used in multivariate data partitioning approaches. For this purpose, the Generalized HDMR philosophy is taken into consideration to construct the details of the Generalized EMPR at constancy level as the introductory steps and encouraging results are obtained in data partitioning problems by using our new method. In addition, to examine this performance, a number of numerical implementations with concluding remarks are given at the end of this paper.

  8. Effect of pressure on cation partitioning between immiscible liquids in the system Ti0 2-SiO 2

    NASA Astrophysics Data System (ADS)

    Circone, S.; Agee, C. B.

    1995-03-01

    Liquidus phase relations in the system Si0 2-TiO 2 have been determined at 3.0 GPa to investigate the effect of pressure on the partitioning of Si and Ti between coexisting immiscible liquids. Experiments on oxide mixtures containing 10, 50, 90, and 100 mol% TiO 2 were performed in multi-anvil and piston-cylinder apparatus at 2173-2740 K. At 1 atm, immiscible liquids form because the liquid structures are dissimilar: tetravalent cations occur in primarily fourfold (Si0 2-rich liquid) vs. sixfold (TiO 2-rich liquid) coordination by oxygen. At 3.0 GPa, immiscible liquids also coexist, but the phase relations and liquid compositions are significantly different. The eutectic liquid is now Ti0 2-rich (78.4 vs. 8.1 mol% TiO 2 at 1 atm). Above the liquidus, the coexisting immiscible liquids are enriched in Si0 2. The Si0 2 content of the TiO 2-rich liquid has increased by more than a factor of 3, while the TiO2-content of the SiO 2-rich liquid has decreased by 1/2. The persistence of a wide solvus implies that pressure does not cause liquid structure assimilation. The observed shift in immiscible liquid compositions indicated that pressure has raised the activity of TiO 2 in the liquid dominated by tetravalent cations in fourfold coordination and lowered the activity of SiO 2 in a liquid dominated by tetravalent cations in sixfold coordination. The decrease in TiO 2 content of the SiO 2-rich liquid with pressure is probably related to the positive volume of mixing observed in 1 atm glasses in this composition range. The enhanced solubility of SiO 2 in the TiO 2-rich liquid with pressure may be due to a pressure-induced increase in the coordination state of Si.

  9. A Product Partition Model With Regression on Covariates

    PubMed Central

    Müller, Peter; Quintana, Fernando; Rosner, Gary L.

    2011-01-01

    We propose a probability model for random partitions in the presence of covariates. In other words, we develop a model-based clustering algorithm that exploits available covariates. The motivating application is predicting time to progression for patients in a breast cancer trial. We proceed by reporting a weighted average of the responses of clusters of earlier patients. The weights should be determined by the similarity of the new patient’s covariate with the covariates of patients in each cluster. We achieve the desired inference by defining a random partition model that includes a regression on covariates. Patients with similar covariates are a priori more likely to be clustered together. Posterior predictive inference in this model formalizes the desired prediction. We build on product partition models (PPM). We define an extension of the PPM to include a regression on covariates by including in the cohesion function a new factor that increases the probability of experimental units with similar covariates to be included in the same cluster. We discuss implementations suitable for any combination of continuous, categorical, count, and ordinal covariates. An implementation of the proposed model as R-package is available for download. PMID:21566678

  10. The radical cation of syn-tricyclooctadiene and its rearrangement products

    PubMed

    Bally; Bernhard; Matzinger; Roulin; Sastry; Truttmann; Zhu; Marcinek; Adamus; Kaminski; Gebicki; Williams; Chen; Fulscher

    2000-03-03

    The syn dimer of cyclobutadiene (tricyclo[4.2.0.0(2.5)]octa-3,7-diene, TOD) is subjected to ionization under different conditions and the resulting species are probed by optical and ESR spectroscopy. By means of quantum chemical modelling of the potential energy surfaces and the optical spectra, it is possible to assign the different products that arise spontaneously after ionization or after subsequent warming or illumination of the samples. Based on these findings, we propose a mechanistic scheme which involves a partitioning of the incipient radical cation of TOD between two electronic states. These two states engage in (near) activation-less decay to the more stable valence isomers, cyclooctatetraene (COT*+) and a bis-cyclobutenylium radical cation BCB*+. The latter product undergoes further rearrangement, first to tetracyclo[4.2.0.0(2,4).0(3,5]oct-7-ene (TCO*+) and eventually to bicyclo[4.2.0]octa-2,4,7-triene (BOT*+) which can also be generated photochemically from BCB*+ or TCO*+. The surprising departure of syn-TOD*+ from the least-motion reaction path leading to BOT*+ can be traced to strong vibronic interactions (second-order Jahn-Teller effects) which prevail in both possible ground states of syn-TOD*+. Such effects seem to be more important in determining the intramolecular reactivity of radical cations than orbital or state symmetry rules.

  11. Cationic vinyl pyridine copolymers and products thereof

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1978-01-01

    Quaternized, cross-linked, insoluble copolymers of unsubstituted and substituted vinyl pyridines and a dihalo organic compound are spontaneously formed at ambient temperature on mixing the two monomers in bulk, in solution or in suspension. The amount of cross-linking may be varied according to the composition and reaction conditions. The polymer product exhibits ion exchange capacity and undergoes a reversible color change from black at a pH above 7 to yellow at a pH below 7. The polymer may be formed in the presence of preformed polymers, substrates such as porous or impervious particles or films to deposit an ion exchange film in situ or on the surface of the substrate. The coated or resin impregnated substrate may be utilized for separation of anionic species from aqueous solution.

  12. Formation of (Cr, Al)UO4 from doped UO2 and its influence on partition of soluble fission products

    NASA Astrophysics Data System (ADS)

    Cooper, M. W. D.; Gregg, D. J.; Zhang, Y.; Thorogood, G. J.; Lumpkin, G. R.; Grimes, R. W.; Middleburgh, S. C.

    2013-11-01

    CrUO4 and (Cr, Al)UO4 have been fabricated by a sol-gel method, studied using diffraction techniques and modelled using empirical pair potentials. Cr2O3 was predicted to preferentially form CrUO4 over entering solution into hyper-stoichiometric UO2+x by atomic scale simulation. Further, it was predicted that the formation of CrUO4 can proceed by removing excess oxygen from the UO2 lattice. Attempts to synthesise AlUO4 failed, instead forming U3O8 and Al2O3. X-ray diffraction confirmed the structure of CrUO4 and identifies the existence of a (Cr, Al)UO4 phase for the first time (with a maximum Al to Cr mole ratio of 1:3). Simulation was subsequently used to predict the partition energies for the removal of fission products or fuel additives from hyper-stoichiometric UO2+x and their incorporation into the secondary phase. The partition energies are consistent only with smaller cations (e.g. Zr4+, Mo4+ and Fe3+) residing in CrUO4, while all divalent cations are predicted to remain in UO2+x. Additions of Al had little effect on partition behaviour. The reduction of UO2+x due to the formation of CrUO4 has important implications for the solution limits of other fission products as many species are less soluble in UO2 than UO2+x.

  13. Thermal expansion and cation partitioning of MnFe2O4 (Jacobsite) from 1.6 to 1276 K studied by using neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Levy, Davide; Pastero, Linda; Hoser, Andreas; Viscovo, Gabriele

    2015-01-01

    MnFe2O4 is a low-cost and stable magnetic spinel ferrite. In this phase, the influence of the inversion degree on the magnetic properties is still not well understood. To understand this relationship, Mn-ferrite was synthesized by a chemical co-precipitation method modified in our laboratory and studied by using the Neutron Powder Diffraction from 1.6 K to 1243 K. A full refinement of both crystal and magnetic structures was performed in order to correlate the high-temperature cation partitioning, the Curie transition and the structure changes of the Mn-ferrite. In this work three main temperature intervals are detected, characterized by different Mn-ferrite behaviors: first, ranging from 1.6 K to 573 K, where MnFe2O4 is magnetic; second, from 573 K to 623 K, where MnFe2O4 becomes paramagnetic without cation partitioning; and lastly, from 673 K to 1243 K, where cation partitioning occurs.

  14. H + CD4 abstraction reaction dynamics: product energy partitioning.

    PubMed

    Hu, Wenfang; Lendvay, György; Troya, Diego; Schatz, George C; Camden, Jon P; Bechtel, Hans A; Brown, Davida J A; Martin, Marion R; Zare, Richard N

    2006-03-09

    This paper presents experimental and theoretical studies of the product energy partitioning associated with the H + CD4 (nu = 0) --> HD + CD3 reaction for the collision energy range 0.5-3.0 eV. The theoretical results are based on quasiclassical trajectories from (1) first principles direct dynamics calculations (B3LYP/6-31G), (2) an empirical surface developed by Espinosa-García [J. Chem. Phys. 2002, 116, 10664] (EG), and (3) two semiempirical surfaces (MSINDO and reparametrized MSINDO). We find that most of the energy appears in product translation at energies just above the reactive threshold; however, HD vibration and rotation become quite important at energies above 1 eV, each accounting for over 20% of the available energy above 1.5 eV, according to the B3LYP calculations. The barrier on the B3LYP surface, though being later than that on EG, predicts significantly higher HD vibrational excitation than EG. This deviation is contradictory to what would be expected on the basis of the Polanyi rules and derives from modest differences in the potential energy surfaces. The CD3 internal energy is generally quite low, and we present detailed rotational state distributions which show that the CD3 rotational distribution is largely independent of collision energy in the 0.75-1.95 eV range. The most populated rotational levels are N = 5 and 6 on B3LYP, with most of that excitation being associated with motion about the C2 axes, rather than C3 axis, of the CD3 product, in good agreement with the experimental results. Through our extensive studies in this and previous work concerning the scattering dynamics, we conclude that B3LYP/6-31G provides the best available description of the overall dynamics for the title reaction at relatively high collision energies.

  15. Process and apparatus for the production of Bi-213 cations

    SciTech Connect

    Horwitz, E.P.; Hines, J.J.; Chiarizia, R.; Dietz, M.

    1998-12-29

    A process for producing substantially impurity-free Bi-213 cations is disclosed. An aqueous acid feed solution containing Ac-225 cations is contacted with an ion exchange medium to bind the Ac-225 cations and form an Ac-225-laden ion exchange medium. The bound Ac-225 incubates on the ion exchange medium to form Bi-213 cations by radioactive decay. The Bi-213 cations are then recovered from the Ac-225-laden ion exchange medium to form a substantially impurity-free aqueous Bi-213 cation acid solution. An apparatus for carrying out this process is also disclosed. 7 figs.

  16. Process and apparatus for the production of Bi-213 cations

    DOEpatents

    Horwitz, E.P.; Hines, J.J.; Chiarizia, R.; Dietz, M.

    1998-12-29

    A process for producing substantially impurity-free Bi-213 cations is disclosed. An aqueous acid feed solution containing Ac-225 cations is contacted with an ion exchange medium to bind the Ac-225 cations and form an Ac-225-laden ion exchange medium. The bound Ac-225 incubates on the ion exchange medium to form Bi-213 cations by radioactive decay. The Bi-213 cations are then recovered from the Ac-225-laden ion exchange medium to form a substantially impurity-free aqueous Bi-213 cation acid solution. An apparatus for carrying out this process is also disclosed. 7 figs.

  17. Process and apparatus for the production of BI-213 cations

    DOEpatents

    Horwitz, E. Philip; Hines, John J.; Chiarizia, Renato; Dietz, Mark

    1998-01-01

    A process for producing substantially impurity-free Bi-213 cations is disclosed. An aqueous acid feed solution containing Ac-225 cations is contacted with an ion exchange medium to bind the Ac-225 cations and form an Ac-225-laden ion exchange medium. The bound Ac-225 incubates on the ion exchange medium to form Bi-213 cations by radioactive decay. The Bi-213 cations are then recovered from the Ac-225-laden ion exchange medium to form a substantially impurity-free aqueous Bi-213 cation acid solution. An apparatus for carrying out this process is also disclosed.

  18. On the star partition dimension of comb product of cycle and path

    NASA Astrophysics Data System (ADS)

    Alfarisi, Ridho; Darmaji

    2017-08-01

    Let G = (V, E) be a connected graphs with vertex set V(G), edge set E(G) and S ⊆ V(G). Given an ordered partition Π = {S1, S2, S3, …, Sk} of the vertex set V of G, the representation of a vertex v ∈ V with respect to Π is the vector r(v|Π) = (d(v, S1), d(v, S2), …, d(v, Sk)), where d(v, Sk) represents the distance between the vertex v and the set Sk and d(v, Sk) = min{d(v, x)|x ∈ Sk }. A partition Π of V(G) is a resolving partition if different vertices of G have distinct representations, i.e., for every pair of vertices u, v ∈ V(G), r(u|Π) ≠ r(v|Π). The minimum k of Π resolving partition is a partition dimension of G, denoted by pd(G). The resolving partition Π = {S1, S2, S3, …, Sk } is called a star resolving partition for G if it is a resolving partition and each subgraph induced by Si, 1 ≤ i ≤ k, is a star. The minimum k for which there exists a star resolving partition of V(G) is the star partition dimension of G, denoted by spd(G). Finding the star partition dimension of G is classified to be a NP-Hard problem. In this paper, we will show that the partition dimension of comb product of cycle and path namely Cm⊳Pn and Pn⊳Cm for n ≥ 2 and m ≥ 3.

  19. Biological removal of cationic fission products from nuclear wastewater.

    PubMed

    Ngwenya, N; Chirwa, E M N

    2011-01-01

    Nuclear energy is becoming a preferred energy source amidst rising concerns over the impacts of fossil fuel based energy on global warming and climate change. However, the radioactive waste generated during nuclear power generation contains harmful long-lived fission products such as strontium (Sr). In this study, cationic strontium uptake from solution by microbial cultures obtained from mine wastewater is evaluated. A high strontium removal capacity (q(max)) with maximum loading of 444 mg/g biomass was achieved by a mixed sulphate reducing bacteria (SRB) culture. Sr removal in SRB was facilitated by cell surface based electrostatic interactions with the formation of weak ionic bonds, as 68% of the adsorbed Sr(2+) was easily desorbed from the biomass in an ion exchange reaction with MgCl₂. To a lesser extent, precipitation reactions were also found to account for the removal of Sr from aqueous solution as about 3% of the sorbed Sr was precipitated due to the presence of chemical ligands while the remainder occurred as an immobile fraction. Further analysis of the Sr-loaded SRB biomass by scanning electron microscopy (SEM) coupled to energy dispersive X-ray (EDX) confirmed extracellular Sr(2+) precipitation as a result of chemical interaction. In summary, the obtained results demonstrate the prospects of using biological technologies for the remediation of industrial wastewaters contaminated by fission products.

  20. On the partition dimension of comb product of path and complete graph

    NASA Astrophysics Data System (ADS)

    Darmaji, Alfarisi, Ridho

    2017-08-01

    For a vertex v of a connected graph G(V, E) with vertex set V(G), edge set E(G) and S ⊆ V(G). Given an ordered partition Π = {S1, S2, S3, …, Sk} of the vertex set V of G, the representation of a vertex v ∈ V with respect to Π is the vector r(v|Π) = (d(v, S1), d(v, S2), …, d(v, Sk)), where d(v, Sk) represents the distance between the vertex v and the set Sk and d(v, Sk) = min{d(v, x)|x ∈ Sk}. A partition Π of V(G) is a resolving partition if different vertices of G have distinct representations, i.e., for every pair of vertices u, v ∈ V(G), r(u|Π) ≠ r(v|Π). The minimum k of Π resolving partition is a partition dimension of G, denoted by pd(G). Finding the partition dimension of G is classified to be a NP-Hard problem. In this paper, we will show that the partition dimension of comb product of path and complete graph. The results show that comb product of complete grapph Km and path Pn namely p d (Km⊳Pn)=m where m ≥ 3 and n ≥ 2 and p d (Pn⊳Km)=m where m ≥ 3, n ≥ 2 and m ≥ n.

  1. Trace Element Partitioning under Crustal and Uppermost Mantle Conditions: The Influences of Ionic Radius, Cation Charge, Pressure, and Temperature

    NASA Astrophysics Data System (ADS)

    Wood, B. J.; Blundy, J. D.

    2003-12-01

    The controls on partitioning of trace elements between crystals and silicate melts were initially the subject of crystal-chemical, rather than petrogenetic interest. Goldschmidt (1937) systematized his observations of elemental concentrations in minerals as a means of understanding and predicting element behavior during crystallization from liquids or gases. Thus, he proposed his three "rules" of element partitioning, which may be summarized as follows: (i) Any two ions of the same charge and very similar ionic radius have essentially the same crystal-liquid partition coefficient (D=[i]xtl/[i]liq, where [i] refers to the concentration of element i). (ii) If there is a small difference of ionic radius, the smaller ion enters the crystal preferentially, e.g., DMg2+>DFe2+, DK+>DRb+>DCs+. (iii) For ions of similar radius but different charges, the ion with the higher charge enters the crystal preferentially, i.e., DSc3+>DMg2+>DLi+, DCa2+>DNa+, and DBa2+>DK+. These principles were taught to generations of students and, as we will show below, under certain circumstances, retain a degree of validity. They are neither, however, universally correct nor do they have any quantitative applicability. The aim of this chapter is to summarize the ways in which Goldschmidt's work has been amplified through a combination of theory and experimental measurement in order to quantify crystal-liquid partitioning behavior.Since the development of accurate methods of determining element concentration at the ppm level, the trace-element contents of igneous rocks have frequently been used to model their chemical evolution. These studies use estimated crystal-liquid partition coefficients together with solutions for the differential equations describing, e.g., fractional crystallization or fractional melting (Schilling and Winchester, 1967; Gast, 1968; Shaw, 1970) to model evolution of the melt during precipitation or dissolution of the crystalline phases. Generally, because of lack of data

  2. On the star partition dimension of comb product of cycle and complete graph

    NASA Astrophysics Data System (ADS)

    Alfarisi, Ridho; Darmaji; Dafik

    2017-06-01

    Let G = (V, E) be a connected graphs with vertex set V (G), edge set E(G) and S ⊆ V (G). For an ordered partition Π = {S 1, S 2, S 3, …, Sk } of V (G), the representation of a vertex v ∈ V (G) with respect to Π is the k-vectors r(v|Π) = (d(v, S 1), d(v, S 2), …, d(v, Sk )), where d(v, Sk ) represents the distance between the vertex v and the set Sk , defined by d(v, Sk ) = min{d(v, x)|x ∈ Sk}. The partition Π of V (G) is a resolving partition if the k-vektors r(v|Π), v ∈ V (G) are distinct. The minimum resolving partition Π is a partition dimension of G, denoted by pd(G). The resolving partition Π = {S 1, S 2, S 3, …, Sk} is called a star resolving partition for G if it is a resolving partition and each subgraph induced by Si , 1 ≤ i ≤ k, is a star. The minimum k for which there exists a star resolving partition of V (G) is the star partition dimension of G, denoted by spd(G). Finding a star partition dimension of G is classified to be a NP-Hard problem. Furthermore, the comb product between G and H, denoted by G ⊲ H, is a graph obtained by taking one copy of G and |V (G)| copies of H and grafting the i-th copy of H at the vertex o to the i-th vertex of G. By definition of comb product, we can say that V (G ⊲ H) = {(a, u)|a ∈ V (G), u ∈ V (H)} and (a, u)(b, v) ∈ E(G ⊲ H) whenever a = b and uv ∈ E(H), or ab ∈ E(G) and u = v = o. In this paper, we will study the star partition dimension of comb product of cycle and complete graph, namely Cn ⊲ Km and Km ⊲ Cn for n ≥ 3 and m ≥ 3.

  3. Multivariate regression model for partitioning tree volume of white oak into round-product classes

    Treesearch

    Daniel A. Yaussy; David L. Sonderman

    1984-01-01

    Describes the development of multivariate equations that predict the expected cubic volume of four round-product classes from independent variables composed of individual tree-quality characteristics. Although the model has limited application at this time, it does demonstrate the feasibility of partitioning total tree cubic volume into round-product classes based on...

  4. Intercrystalline cation partitioning between minerals of the triplite-zwieselite-magniotriplite and the triphylite-lithiophilite series in granitic pegmatites

    NASA Astrophysics Data System (ADS)

    Keller, Paul; Fontan, François; Fransolet, André-Mathicu

    1994-12-01

    Minerals of the triphylite-lithiophilite, Li(Fe, Mn)PO4, and the triplite-zwieselite-magniotriplite series, (Mn, Fe, Mg)2PO4F, occur in the late stage period of pegmatite evolution. Unfortunately, neither are the genetic relationships between these phosphates fully understood nor are thermodynamic data known. Consequently, phosphate associations and assemblages from 8 granitic pegmatites — Clementine II, Rubicon II and III, and Tsaobismund (Namibia); Hagendorf-Süd and Rabenstein (Germany); Valmy (France); Viitaniemi (Finland) — have been tested for compositional zoning and intercrystalline partitioning of main elements by electron microprobe techniques. Although the selected pegmatites display varying degrees of fractionation, and the intergrowth textures indicate different genetic relationships between the phosphates, the plots of mole fractions X Fe=Fe/(Fe+Mn+Mg+Ca), X Mn=Mn/(Fe+Mn+Mg+Ca), and X Mg=Mg/(Fe+Mn+Mg+Ca) can be fitted relatively well with smooth curves in Roozeboom diagrams. Their deviations from symmetrical distribution curves are mainly dependent upon X Mg or X Ca, and upon non-ideal solutions. Surprisingly small differences between the partition coefficients were detected for intergrowths of different origin. However, the partitioning of shared components among coexisting phases is clearly dependent upon the conditions of formation. Compositional zoning is observed only when both Fe-Mn phosphates are intergrown mutually or with other Fe-Mn-Mg mineral solid-solutios. Thus, the zoning does not seem to be due to continuous crystallization, but to later diffusion processes. The triplite structure has preference for Mn, Mg, and Ca, while Fe prefers minerals of the triphylite series. A quantification of main element fractionation between minerals of the triphylite and the triplite series is possible in the cases where diffusion can be excluded. For the Fe/(Fe+Mn) ratios of core compositions an equation with a high correlation coefficient (R=0

  5. Reverse-micelle formation in the partitioning of trivalent F-element cations by biphasic systems containing a tetraalkyldiglycolamide.

    PubMed

    Jensen, Mark P; Yaita, Tsuyoshi; Chiarizia, Renato

    2007-04-24

    The conditions for reverse-micelle formation were studied for solutions of tetra-n-octyldiglycolamide (TODGA) in alkane diluents equilibrated with aqueous solutions of nitric or hydrochloric acids in the presence and absence of Nd3+. Small-angle neutron scattering, vapor-pressure osmometry, and tensiometry are all consistent with the partial formation of TODGA dimers at the lowest acidities, transitioning to a polydisperse mixture containing TODGA monomers, dimers, and small reverse-micelles of TODGA tetramers at aqueous nitric acid acidities of 0.7 M or higher in the absence of Nd. Application of the Baxter model to the samples containing 0.005-0.015 M Nd reveals the persistence of tetrameric TODGA reverse-micelles with significant interparticle attraction between the polar cores of the micelles that increases with increasing organic phase concentrations of acid or Nd. Our experimental findings suggest that the peculiar behavior of TODGA with respect to the extraction of trivalent lanthanide and actinide cations arises from the affinity of these metal cations for the preformed TODGA reverse-micelle tetramers.

  6. Cation solvation with quantum chemical effects modeled by a size-consistent multi-partitioning quantum mechanics/molecular mechanics method.

    PubMed

    Watanabe, Hiroshi C; Kubillus, Maximilian; Kubař, Tomáš; Stach, Robert; Mizaikoff, Boris; Ishikita, Hiroshi

    2017-07-21

    In the condensed phase, quantum chemical properties such as many-body effects and intermolecular charge fluctuations are critical determinants of the solvation structure and dynamics. Thus, a quantum mechanical (QM) molecular description is required for both solute and solvent to incorporate these properties. However, it is challenging to conduct molecular dynamics (MD) simulations for condensed systems of sufficient scale when adapting QM potentials. To overcome this problem, we recently developed the size-consistent multi-partitioning (SCMP) quantum mechanics/molecular mechanics (QM/MM) method and realized stable and accurate MD simulations, using the QM potential to a benchmark system. In the present study, as the first application of the SCMP method, we have investigated the structures and dynamics of Na(+), K(+), and Ca(2+) solutions based on nanosecond-scale sampling, a sampling 100-times longer than that of conventional QM-based samplings. Furthermore, we have evaluated two dynamic properties, the diffusion coefficient and difference spectra, with high statistical certainty. Furthermore the calculation of these properties has not previously been possible within the conventional QM/MM framework. Based on our analysis, we have quantitatively evaluated the quantum chemical solvation effects, which show distinct differences between the cations.

  7. Product energy distributions and energy partitioning in O atom reactions on surfaces

    NASA Technical Reports Server (NTRS)

    Halpern, Bret; Kori, Moris

    1987-01-01

    Surface reactions involving O atoms are likely to be highly exoergic, with different consequences if energy is channeled mostly to product molecules or surface modes. Thus the surface may become a source of excited species which can react elsewhere, or a sink for localized heat deposition which may disrupt the surface. The vibrational energy distribution of the product molecule contains strong clues about the flow of released energy. Two instructive examples of energy partitioning at surfaces are the Pt catalyzed oxidations: (1) C(ads) + O(ads) yields CO* (T is greater than 1000 K); and (2) CO(ads) + O(gas) yields CO2* (T is approx. 300 K). The infrared emission spectra of the excited product molecules were recorded and the vibrational population distributions were determined. In reaction 1, energy appeared to be statistically partitioned between the product CO and several Pt atoms. In reaction 2, partitioning was non-statistical; the CO2 asymmetric stretch distribution was inverted. In gas reactions these results would indicate a long lived and short lived activated complex. The requirement that Pt be heated in O atoms to promote reaction of atomic O and CO at room temperature is specifically addressed. Finally, the fraction of released energy that is deposited in the catalyst is estimated.

  8. Enhancement of soil retention for phenanthrene in binary cationic gemini and nonionic surfactant mixtures: characterizing two-step adsorption and partition processes through experimental and modeling approaches.

    PubMed

    Zhao, Shan; Huang, Gordon; An, Chunjiang; Wei, Jia; Yao, Yao

    2015-04-09

    The enhancement of soil retention for phenanthrene (PHE) through the addition of a binary mixture of cationic gemini (12-2-12) and nonionic surfactants (C12E10) was investigated. The maximum apparent sorption coefficient Kd(*) reached 4247.8 mL/g through the addition of mixed 12-2-12 gemini and C12E10 surfactants, which was markedly higher than the summed individual results in the presence of individual 12-2-12 gemini (1148.6 mL/g) or C12E10 (210.0 mL/g) surfactant. However, the sorption of 12-2-12 gemini was inhibited by the increasing C12E10 dose; and a higher initial 12-2-12 gemini dose showed a higher "desorption" rate. The present study also addressed the sorption behavior of the single 12-2-12 gemini surfactant at the soil/aqueous interface. The sorption isotherm was divided into two steps to elucidate the sorption process; and the sorption schematics were proposed to elaborate the growth of surfactant aggregates corresponding to the various steps of the sorption isotherm. Finally, a two-step adsorption and partition model (TAPM) was developed to simulate the sorption process. Analysis of the equilibrium data indicated that the sorption isotherms of 12-2-12 gemini fitted the TAPM model better. Thermodynamic calculations confirmed that the 12-2-12 gemini sorption at the soil/aqueous interface was spontaneous and exothermic from 288 to 308K. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Influence of porewater sulfide on methylmercury production and partitioning in sulfate-impacted lake sediments.

    PubMed

    Bailey, Logan T; Mitchell, Carl P J; Engstrom, Daniel R; Berndt, Michael E; Coleman Wasik, Jill K; Johnson, Nathan W

    2017-02-15

    In low-sulfate and sulfate-limited freshwater sediments, sulfate loading increases the production of methylmercury (MeHg), a potent and bioaccumulative neurotoxin. Sulfate loading to anoxic sediments leads to sulfide production that can inhibit mercury methylation, but this has not been commonly observed in freshwater lakes and wetlands. In this study, sediments were collected from sulfate-impacted, neutral pH, surface water bodies located downstream from ongoing and historic mining activities to examine how chronic sulfate loading produces porewater sulfide, and influences MeHg production and transport. Sediments were collected over two years, during several seasons from lakes with a wide range of overlying water sulfate concentration. Samples were characterized for in-situ solid phase and porewater MeHg, Hg methylation potentials via incubations with enriched stable Hg isotopes, and sulfur, carbon, and iron content and speciation. Porewater sulfide reflected historic sulfur loading and was strongly related to the extractable iron content of sediment. Overall, methylation potentials were consistent with the accumulation of MeHg on the solid phase, but both methylation potentials and MeHg were significantly lower at chronically sulfate-impacted sites with a low solid-phase Fe:S ratio. At these heavily sulfate-impacted sites that also contained elevated porewater sulfide, both MeHg production and partitioning are influenced: Hg methylation potentials and sediment MeHg concentrations are lower, but occasionally porewater MeHg concentrations in sediment are elevated, particularly in the spring. The dual role of sulfide as a ligand for inorganic mercury (decreasing bioavailability) and methylmercury (increasing partitioning into porewater) means that elucidating the role of iron and sulfur loads as they define porewater sulfide is key to understanding sulfate's influence on MeHg production and partitioning in sulfate-impacted freshwater sediment.

  10. A method for the production of weakly acidic cation exchange resins

    NASA Astrophysics Data System (ADS)

    Heller, H.; Werner, F.; Mitschker, A.; Diehl, H. V.; Schaefer, A.

    1991-12-01

    The invention relates to a nonpolluting method for the production of weakly acidic cation exchange resins by saponification of cross-linked acrylonitrile bead polymers, with an alkaline saponification agent at elevated temperature, according to which method the bead polymer and alkaline saponification agent are jointly added only at elevated temperature.

  11. Experimental determination of partition coefficient for β-pinene ozonolysis products in SOA

    NASA Astrophysics Data System (ADS)

    Gensch, Iulia; Hohaus, Thorsten; Kimmel, Joel; Jayne, John T.; Worsnop, Douglas R.; Kiendler-Scharr, Astrid

    2013-04-01

    In the present study, simultaneous measurement of β-pinene ozonolysis products in the gas phase by Proton Transfer Reaction - Time of Flight Mass Spectrometry (PTR-ToFMS) and particle phase by using an Aerosol Collection Module coupled to a Gas Chromatograph - Mass Spectrometer (ACM-GC-MS) were employed to determine the equilibrium partitioning coefficient (Kp) of several semi-volatile organic species. Mean Kp values of 6.7 10-5 ± 2.5 10-5 for nopinone, 4.8 10-4 ± 1.7 10-4 for apoverbenone, 7.0 10-4 ± 1.7 10-4 for oxonopinone and 1.9 10-3 ± 1.1 10-3 for hydroxynopinone were obtained. The results were compared with calculations arising from studies on the gas-particle partitioning, based on the Pankow absorption model. The experimental partition coefficients are two to three orders of magnitudes higher than the calculated values, leading to the conclusion that the amount of semi-volatile organic compounds in secondary organic aerosol (SOA) is currently underestimated by the theory, thus impacting on the modeling of the organic matter in the atmosphere.

  12. Partitioning of Evapotranspiration Using a Stable Water Isotope Technique in a High Temperature Agricultural Production System

    NASA Astrophysics Data System (ADS)

    Lu, X.; Liang, L.; Wang, L.; Jenerette, D.; Grantz, D. A.

    2015-12-01

    Agricultural production in the hot and arid low desert systems of southern California relies heavily on irrigation. A better understanding of how much and to what extent the irrigation water is transpired by crops relative to being lost through evaporation will contribute to better management of increasingly limited agricultural water resources. In this study, we examined the evapotranspiration (ET) partitioning over a field of forage sorghum (S. bicolor) during a growing season with several irrigation cycles. In several field campaigns we used continuous measurements of near-surface variations in the stable isotopic composition of water vapor (δ2H). We employed custom built transparent chambers coupled with a laser-based isotope analyzer and used Keeling plot and mass balance methods for surface flux partitioning. The preliminary results show that δT is more enriched than δE in the early growing season, and becomes less enriched than δE later in the season as canopy cover increases. There is an increase in the contribution of transpiration to ET as (1) leaf area index increases, and (2) as soil surface moisture declines. These results are consistent with theory, and extend these measurements to an environment that experiences extreme soil surface temperatures. The data further support the use of chamber based methods with stable isotopic analysis for characterization of ET partitioning in challenging field environments.

  13. Intensified extraction of ionized natural products by ion pair centrifugal partition extraction.

    PubMed

    Hamzaoui, Mahmoud; Hubert, Jane; Hadj-Salem, Jamila; Richard, Bernard; Harakat, Dominique; Marchal, Luc; Foucault, Alain; Lavaud, Catherine; Renault, Jean-Hugues

    2011-08-05

    The potential of centrifugal partition extraction (CPE) combined with the ion-pair (IP) extraction mode to simultaneously extract and purify natural ionized saponins from licorice is presented in this work. The design of the instrument, a new laboratory-scale Fast Centrifugal Partition Extractor (FCPE300(®)), has evolved from centrifugal partition chromatography (CPC) columns, but with less cells of larger volume. Some hydrodynamic characteristics of the FCPE300(®) were highlighted by investigating the retention of the stationary phase under different flow rate conditions and for different biphasic solvent systems. A method based on the ion-pair extraction mode was developed to extract glycyrrhizin (GL), a biologically active ionic saponin naturally present in licorice (Glycyrrhiza glabra L., Fabaceae) roots. The extraction of GL was performed at a flow rate of 20 mL/min in the descending mode by using the biphasic solvent system ethyl acetate/n-butanol/water in the proportions 3/2/5 (v/v/v). Trioctylmethylammonium with chloride as a counter-ion (Al336(®)) was used as the anion extractant in the organic stationary phase and iodide, with potassium as counter-ion, was used as the displacer in the aqueous mobile phase. From 20 g of a crude extract of licorice roots, 2.2g of GL were recovered after 70 min, for a total process duration of 90 min. The combination of the centrifugal partition extractor with the ion-pair extraction mode (IP-CPE) offers promising perspectives for industrial applications in the field of natural product isolation or for the fractionation of natural complex mixtures.

  14. Experimental determination of the partitioning coefficient of β-pinene oxidation products in SOAs.

    PubMed

    Hohaus, Thorsten; Gensch, Iulia; Kimmel, Joel; Worsnop, Douglas R; Kiendler-Scharr, Astrid

    2015-06-14

    The composition of secondary organic aerosols (SOAs) formed by β-pinene ozonolysis was experimentally investigated in the Juelich aerosol chamber. Partitioning of oxidation products between gas and particles was measured through concurrent concentration measurements in both phases. Partitioning coefficients (Kp) of 2.23 × 10(-5) ± 3.20 × 10(-6) m(3) μg(-1) for nopinone, 4.86 × 10(-4) ± 1.80 × 10(-4) m(3) μg(-1) for apoverbenone, 6.84 × 10(-4) ± 1.52 × 10(-4) m(3) μg(-1) for oxonopinone and 2.00 × 10(-3) ± 1.13 × 10(-3) m(3) μg(-1) for hydroxynopinone were derived, showing higher values for more oxygenated species. The observed Kp values were compared with values predicted using two different semi-empirical approaches. Both methods led to an underestimation of the partitioning coefficients with systematic differences between the methods. Assuming that the deviation between the experiment and the model is due to non-ideality of the mixed solution in particles, activity coefficients of 4.82 × 10(-2) for nopinone, 2.17 × 10(-3) for apoverbenone, 3.09 × 10(-1) for oxonopinone and 7.74 × 10(-1) for hydroxynopinone would result using the vapour pressure estimation technique that leads to higher Kp. We discuss that such large non-ideality for nopinone could arise due to particle phase processes lowering the effective nopinone vapour pressure such as diol- or dimer formation. The observed high partitioning coefficients compared to modelled results imply an underestimation of SOA mass by applying equilibrium conditions.

  15. Biosorption of silver cations onto Lactococcus lactis and Lactobacillus casei isolated from dairy products

    PubMed Central

    Milanowski, Maciej; Pomastowski, Paweł; Railean-Plugaru, Viorica; Rafińska, Katarzyna; Ligor, Tomasz; Buszewski, Bogusław

    2017-01-01

    The current work deals with the phenomenon of silver cations uptake by two kinds of bacteria isolated from dairy products. The mechanism of sorption of silver cations by Lactococcus lactis and Lactobacillus casei bacteria was investigated. Inductively coupled plasma–mass spectrometry (ICP-MS) was used for determination of silver concentration sorbed by bacteria. Analysis of charge distribution was conducted by diffraction light scattering method. Changes in the ultrastructure of Lactococcus lactis and Lactobacillus casei cells after treatment with silver cations were investigated using transmission electron microscopy observation. Molecular spectroscopy methods, namely Fourier transform-infrared spectroscopy (FT-IR) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) were employed for description of the sorption mechanism. Moreover, an analysis of volatile organic compounds (VOCs) extracted from bacterial cells was performed. PMID:28362838

  16. Equilibrium and nonequilibrium partition coefficients of volatile fission products between liquid sodium and the gas phase

    SciTech Connect

    Haga, K.; Nishizawa, Y.; Watanabe, T.; Miyahara, S.; Himeno, Y. )

    1992-02-01

    Two series of experiments have been conducted to obtain the gas-liquid equilibrium partition coefficient K{sub d} and the nonequilibrium partition coefficient K{prime}{sub d} of volatile fission products such as cesium, iodine, and tellurium between liquid sodium and the gas phase. In the equilibrium experiment, a sodium pool mixed with a fission product simulant was heated by a n electric furnace, and the solvent of the vapors and aerosols trapped by filters was quantitatively analyzed. The results provided in this paper are as follows: Cesium shows the largest K{sub d} (20 to 100). The K{sub d} values of cesium and iodine agree well with the theoretical ones reported by Castleman and Tang. If sodium telluride, which is harder to vaporize than pure tellurium, is assumed, the measured K{sub d} value of tellurium agrees with the theoretical. The nonequilibrium experiment in which the temperature dropped relatively sharply in the cover-gas region shows that K{prime}{sub d} was not larger than K{sub d}.

  17. Contributions of parent molecule fixed and excess energies to product energy partitioning in four-center elimination reactions

    NASA Astrophysics Data System (ADS)

    Benito, R. M.; Santamaría, J.

    1989-03-01

    In four-center elimination reactions such as hydrogen halide elimination from halogenated hydrocarbons the energy barrier is higher than the difference in enthalpy of formation between the parent molecule and its fragments (HX and olefin). This determines that the energy available to products has two origins: the reverse reaction barrier (fixed energy), and the excess energy (energy above the barrier). Both types of energy are partitioned among products following different laws: more or less statistical for excess energy and non-statistical for fixed energy. In a study of CF 3-CH 3 decomposition, we describe a practical method, based on the variation of product energy partitioning with excess energy, to determine the partitioning of the fixed energy among different types of product energy, thus defining the exact nature of the reverse reaction energy barrier. We applied this model to other types of reactions, such as three-center molecular eliminations.

  18. Simultaneous production and partitioning of heterologous polyketide and isoprenoid natural products in an Escherichia coli two-phase bioprocess.

    PubMed

    Boghigian, Brett A; Myint, Melissa; Wu, Jiequn; Pfeifer, Blaine A

    2011-11-01

    Natural products have long served as rich sources of drugs possessing a wide range of pharmacological activities. The discovery and development of natural product drug candidates is often hampered by the inability to efficiently scale and produce a molecule of interest, due to inherent qualities of the native producer. Heterologous biosynthesis in an engineering and process-friendly host emerged as an option to produce complex natural products. Escherichia coli has previously been utilized to produce complex precursors to two popular natural product drugs, erythromycin and paclitaxel. These two molecules represent two of the largest classes of natural products, polyketides and isoprenoids, respectively. In this study, we have developed a platform E. coli strain capable of simultaneous production of both product precursors at titers greater than 15 mg l(-1). The utilization of a two-phase batch bioreactor allowed for very strong in situ separation (having a partitioning coefficient of greater than 5,000), which would facilitate downstream purification processes. The system developed here could also be used in metagenomic studies to screen environmental DNA for natural product discovery and preliminary production experiments.

  19. Conjugated fatty acid synthesis: residues 111 and 115 influence product partitioning of Momordica charantia conjugase.

    PubMed

    Rawat, Richa; Yu, Xiao-Hong; Sweet, Marie; Shanklin, John

    2012-05-11

    Conjugated linolenic acids (CLNs), 18:3 Δ(9,11,13), lack the methylene groups found between the double bonds of linolenic acid (18:3 Δ(9,12,15)). CLNs are produced by conjugase enzymes that are homologs of the oleate desaturases FAD2. The goal of this study was to map the domain(s) within the Momordica charantia conjugase (FADX) responsible for CLN formation. To achieve this, a series of Momordica FADX-Arabidopsis FAD2 chimeras were expressed in the Arabidopsis fad3fae1 mutant, and the transformed seeds were analyzed for the accumulation of CLN. These experiments identified helix 2 and the first histidine box as a determinant of conjugase product partitioning into punicic acid (18:3 Δ(9cis,11trans,13cis)) or α-eleostearic acid (18:3 Δ(9cis,11trans,13trans)). This was confirmed by analysis of a FADX mutant containing six substitutions in which the sequence of helix 2 and first histidine box was converted to that of FAD2. Each of the six FAD2 substitutions was individually converted back to the FADX equivalent identifying residues 111 and 115, adjacent to the first histidine box, as key determinants of conjugase product partitioning. Additionally, expression of FADX G111V and FADX G111V/D115E resulted in an approximate doubling of eleostearic acid accumulation to 20.4% and 21.2%, respectively, compared with 9.9% upon expression of the native Momordica FADX. Like the Momordica conjugase, FADX G111V and FADX D115E produced predominantly α-eleostearic acid and little punicic acid, but the FADX G111V/D115E double mutant produced approximately equal amounts of α-eleostearic acid and its isomer, punicic acid, implicating an interactive effect of residues 111 and 115 in punicic acid formation.

  20. Resource partitioning within major bottom fish species in a highly productive upwelling ecosystem

    NASA Astrophysics Data System (ADS)

    Abdellaoui, Souad; El Halouani, Hassan; Tai, Imane; Masski, Hicham

    2017-09-01

    The Saharan Bank (21-26°N) is a wide subtropical continental shelf and a highly productive upwelling ecosystem. The bottom communities are dominated by octopus and sparid fish, which are the main targets of bottom-trawl fishing fleets. To investigate resource partitioning within the bottom fish community, adult fish from 14 of the most abundant species were investigated for stomach content analysis. Samples were collected during two periods: October 2003 and May 2007. The diet of the analysed species showed more variation between periods than between size classes, suggesting that temporal or spatial variability in prey availability appears to play a significant role in their diet. Multivariate analysis and subsequent clustering led to a grouping of the species within five trophic guilds. Two species were fish feeders, and the others mainly fed on benthic invertebrates, where epibenthic crustaceans, lamellibranchs and fish were the most important groups in defining trophic guilds. We found that the studied species had a high rate of overlapping spatial distributions and overlapping trophic niches. In this highly productive upwelling ecosystem, where food resources may not be a limiting factor, inter-specific competition did not appear to be an important factor in structuring bottom fish communities. For the species that showed differences in the proportions of prey categories in comparison with other ecosystems, the rise of the proportion of epibenthic crustaceans in their diet was a common feature; a possible consequence of the benthic productivity of this highly productive upwelling ecosystem.

  1. Determinants of recombinant production of antimicrobial cationic peptides and creation of peptide variants in bacteria.

    PubMed

    Zhang, L; Falla, T; Wu, M; Fidai, S; Burian, J; Kay, W; Hancock, R E

    1998-06-29

    Cationic peptides possessing antibacterial activity are virtually ubiquitous in nature, and offer exciting prospects as new therapeutic agents. We had previously demonstrated that such peptides could be produced by fusion protein technology in bacteria and several carrier proteins had been tested as fusion partners including glutathione-S-transferase, S. aureus protein A, IgG binding protein and P. aeruginosa outer membrane protein OprF. However these fusion partners, while successfully employed in peptide expression, were not optimized for high level production of cationic peptides (Piers, K., Brow, M. L., and Hancock, R. E. W. 1993, Gene 137, 7-13). In this paper we took advantage of a small replication protein RepA from E. coli and used its truncated version to construct fusion partners. The minimal elements required for high level expression of cationic peptide were defined as a DNA sequence encoding a fusion protein comprising, from the N-terminus, a 68 amino acid carrier region, an anionic prepro domain, a single methionine and the peptide of interest. The 68 amino acid carrier region was a block of three polypeptides consisting of a truncated RepA, a synthetic cellulose binding domain and a hexa histidine domain. The improved system showed high level expression and simplified downstream purification. The active peptide could be yielded by CNBr cleavage of the fusion protein. This novel vector was used to express three classes of cationic peptides including the alpha-helical peptide CEMA, the looped peptide bactenecin and the extended peptide indolicidin. In addition, mutagenesis of the peptide gene to produce peptide variants of CEMA and indolicidin using the improved vector system was shown to be successful.

  2. Effects of partly replacing dietary starch with fiber and fat on milk production and energy partitioning.

    PubMed

    Boerman, J P; Potts, S B; VandeHaar, M J; Lock, A L

    2015-10-01

    The effects of partly replacing dietary starch with fiber and fat to provide a diet with similar net energy for lactation (NEL) density on yields of milk and milk components and on energy partitioning were evaluated in a crossover design experiment. Holstein cows (n = 32; 109 ± 22 d in milk, mean ± standard deviation) were randomly assigned to treatment sequence. Treatments were a high-starch diet containing 33% corn grain (mixture of dry ground and high-moisture corn; HS) or a high-fiber, high-fat diet containing 2.5% palmitic acid-enriched fatty acid (FA) supplement (HFF). Diets contained corn silage, alfalfa silage, and wheat straw as forage sources; HS contained 32% starch, 3.2% FA, and 25% neutral detergent fiber, whereas HFF contained 16% starch, 5.4% FA, and 33% neutral detergent fiber. Compared with HS, the HFF treatment reduced milk yield, milk protein concentration, and milk protein yield, but increased milk fat concentration, milk fat yield, milk energy output, and milk to feed ratio (energy-corrected milk/dry matter intake). The HFF treatment reduced the yield of de novo synthesized (< 16-carbon) milk FA and increased the yield of 16-carbon milk FA. Yield of preformed (> 16-carbon) milk FA was not different. The HFF treatment increased plasma concentrations of triglycerides and nonesterified fatty acids, but decreased plasma concentration of insulin. Compared with HS, the HFF treatment reduced body weight gain, change in body condition score, and fat thickness over the rump and rib. Calculated body energy gain, as a fraction of NEL use, was less for HFF than HS, whereas milk energy as a fraction of NEL use was increased for HFF. We concluded that the 2 treatments resulted in similar apparent NEL densities and intakes, but the HS treatment partitioned more energy toward body gain whereas the HFF treatment partitioned more energy toward milk. A high-fiber, high-fat diet might diminish the incidence of over conditioning in mid-lactation cows while

  3. Asymmetric partitioning of metals among cluster anions and cations generated via laser ablation of mixed aluminum/Group 6 transition metal targets.

    PubMed

    Waller, Sarah E; Mann, Jennifer E; Jarrold, Caroline Chick

    2013-02-28

    While high-power laser ablation of metal alloys indiscriminately produces gas-phase atomic ions in proportion to the abundance of the various metals in the alloy, gas-phase ions produced by moderate-power laser ablation sources coupled with molecular beams are formed by more complicated mechanisms. A mass spectrometric study that directly compares the mass distributions of cluster anions and cations generated from laser ablation of pure aluminum, an aluminum/molybdenum mixed target, and an aluminum/tungsten mixed target is detailed. Mass spectra of anionic species generated from the mixed targets showed that both tungsten and molybdenum were in higher abundance in the negatively charged species than in the target material. Mass spectra of the cationic species showed primarily Al(+) and aluminum oxide and hydroxide cluster cations. No molybdenum- or tungsten-containing cluster cations were definitively assigned. The asymmetric distribution of aluminum and Group 6 transition metals in cation and anion cluster composition is attributed to the low ionization energy of atomic aluminum and aluminum suboxide clusters. In addition, the propensity of both molybdenum and tungsten to form metal oxide cluster anions under the same conditions that favor metallic aluminum cluster anions is attributed to differences in the optical properties of the surface oxide that is present in the metal powders used to prepare the ablation targets. Mechanisms of mixed metal oxide clusters are considered.

  4. Phytoplankton succession explains size-partitioning of new production following upwelling-induced blooms

    NASA Astrophysics Data System (ADS)

    Van Oostende, N.; Dunne, J. P.; Fawcett, S. E.; Ward, B. B.

    2015-08-01

    Large and chain-forming diatoms typically dominate the phytoplankton biomass after initiation of coastal upwelling. The ability of these diatoms to accelerate and maintain elevated nitrate uptake rates has been proposed to explain the dominance of diatoms over all other phytoplankton groups. Moreover, the observed delay in biomass accumulation following nitrate supply after initiation of upwelling events has been hypothesised to result from changes in the diatom community structure or from physiological acclimation. To investigate these mechanisms, we used both numerical modelling and experimental incubations that reproduced the characteristic succession from small to large species in phytoplankton community composition and size structure. Using the Tracers Of Phytoplankton with Allometric Zooplankton (TOPAZ) ecosystem model as a framework, we find that variations in functional group-specific traits must be taken into account, through adjustments of group-dependent maximum production rates (PCmax, s- 1), in order to accurately reproduce the observed patterns and timescales of size-partitioned new production in a non-steady state environment. Representation of neither nutrient acclimation, nor diatom diversity in the model was necessary as long as lower than theoretical maximum production rates were implemented. We conclude that this physiological feature, PCmax, is critical in representing the early, relatively higher specific nitrate uptake rate of large diatoms, and explains the differential success of small and large phytoplankton communities in response to nitrate supply during upwelling.

  5. The radical cation of anti-tricyclooctadiene and its rearrangement products

    PubMed

    Bally; Bernhard; Matzinger; Truttmann; Zhu; Roulin; Marcinek; Gebicki; Williams; Chen; Roth; Herbertz

    2000-03-03

    The anti dimer of cyclobutadiene (anti-tricyclo[4.2.0.0(2.5)]octa-3,7-diene, TOD) is subjected to ionization by gamma-irradiation in Freon matrices, pulse radiolysis in hydrocarbon matrices, and photoinduced electron transfer in solution. The resulting species are probed by optical and ESR spectroscopy (solid phase) as well as by CIDNP spectroscopy (solution). Thereby it is found that ionization of anti-TOD invariably leads to spontaneous decay to two products, that is bicyclo[4.2.0]octa-2,4,7-triene (BOT) and 1,4-dihydropentalene (1,4-DHP), whose relative yield strongly depends on the conditions of the experiment. Exploration of the C8H8*+ potential energy surface by the B3LYP/6-31G* density functional method leads to a mechanistic hypothesis for the observed rearrangements which involves a bifurcation between a pathway leading to the simple valence isomer, BOT*+, and another one leading to an unprecedented other valence isomer, the anti form of the bicyclo[3.3.0]octa-2,6-diene-4,8-diyl radical cation (anti-BOD*+). The latter product undergoes a very facile H-shift to yield the radical cation of 1,3a-dihydropentalene (1,3a-DHP*+) which ultimately rearrranges by a further H-shift to the observed product, 1,4-DHP*+.

  6. Partitioning of selected fission products from irradiated oxide fuel induced by thermal treatment

    NASA Astrophysics Data System (ADS)

    Shcherbina, Natalia; Kivel, Niko; Günther-Leopold, Ines

    2013-06-01

    The release of fission products (FPs) from spent nuclear fuel (SNF) has been studied as a function of the temperature and redox conditions. The present paper concerns essentially the high temperature separation of Cs and Sr from irradiated pressurized (PWR) and boiling water reactor (BWR) fuel of different burn-up levels with use of an in-house designed system for inductive vaporization (InVap). Using thermodynamic calculations with the Module of Fission Product Release (MFPR) code along with annealing experiments on SNF in the InVap it was shown that the speciation of Cs and Sr, hence their release behavior at high temperature, is sensitive to the redox conditions during thermal treatment. It was demonstrated that annealing conditions in the InVap can be adjusted in the way to promote the release of selected FPs without significant loss of the fuel matrix or actinides: complete release of Cs and I was achieved during treatment of irradiated fuel at 1800 °C under reducing atmosphere (0.7% H2/Ar mixture). The developed partitioning procedure can be used for the SNF pretreatment as an advanced head-end step in the hydrometallurgical or pyrochemical reprocessing technology.

  7. Production of cationic xylan-METAC copolymer as a flocculant for textile industry.

    PubMed

    Wang, Shoujuan; Hou, Qingxi; Kong, Fangong; Fatehi, Pedram

    2015-06-25

    Xylan is a part of hemicelluloses of woody materials and can be converted to value-added products such as flocculants for the textile industry. To assess the production of flocculants from hemicelluloses of woody materials, xylan was selected as a model and rendered cationic via copolymerization. In this study, the copolymerization reaction of xylan and [2-(methacryloyloxy) ethyl] trimethylammonium chloride (METAC) was optimized. The optimum parameters were 3mol/mol METAC/xylose, 3h reaction time, 80°C reaction temperature, pH 7 and 25g/L xylan concentration. The copolymer was characterized by a charge density analyzer, viscometer, gel permeation chromatography (GPC), light scattering instrument, Fourier transform infrared spectroscopy (FTIR) and an elemental analyzer. The application of the cationic xylan copolymer as a flocculant to decolorize the simulated reactive orange 16 azo-dye wastewater was evaluated. The results confirmed that, by having 160mg/L xylan-METAC concentration in the dye solution with the concentration of 100mg/L, 97.8% of dye could be removed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. The effect of dietary cation-anion difference concentration and cation source on milk production and feed efficiency in lactating dairy cows.

    PubMed

    Iwaniuk, M E; Weidman, A E; Erdman, R A

    2015-03-01

    Feed costs currently account for 55% or more of the total cost of milk production in US dairy herds, and dairy producers are looking for strategies to improve feed efficiency [FE; 3.5% fat-corrected milk (FCM) per dry matter (DM) intake]. Increasing dietary cation-anion difference [DCAD; Na+K-Cl (mEq/kg of DM)] has been shown to increase milk production, FCM, and FE. However, the optimal DCAD concentration for maximal FE has yet to be determined. The objectives of this research were to test the effects of DCAD concentration and cation source on dairy FE. Sixty Holstein dairy cows (20 cows per experiment) were used in three 4×4 Latin square design experiments with 3-wk experimental periods. In experiments 1 and 2, we tested the effect of DCAD concentration: cows were fed a basal diet containing ~250 mEq/kg of DM DCAD that was supplemented with potassium carbonate at 0, 50, 100, and 150 mEq/kg of DM or 0, 125, 250, and 375 mEq/kg of DM in experiments 1 and 2, respectively. In experiment 3, we tested the effect of cation source: sodium sesquicarbonate replaced 0, 33, 67, and 100% of the supplemental potassium carbonate (150 mEq/kg of DM DCAD). The DCAD concentration had no effect on milk production, milk protein concentration, or milk protein yield in experiments 1 and 2. Dry matter intake was not affected by DCAD concentration in experiment 1 or by cation source in experiment 3. However, DMI increased linearly with increasing DCAD in experiment 2. We detected a linear increase in milk fat concentration and yield with increasing DCAD in experiments 1 and 2 and by substituting sodium sesquicarbonate for potassium carbonate in experiment 3. Increased milk fat concentration with increasing DCAD led to increases in 3.5% FCM in experiments 1 and 2. Maximal dairy FE was achieved at a DCAD concentration of 426 mEq/kg of DM in experiments 1 and 2 and by substituting Na for K in experiment 3. The results of these experiments suggest that both DCAD concentration and the cation

  9. Sediment-porewater partitioning, total sulfur, and methylmercury production in estuaries.

    PubMed

    Schartup, Amina T; Balcom, Prentiss H; Mason, Robert P

    2014-01-21

    Mercury (Hg) speciation and the activity of Hg(II)-methylating bacteria are responsible for the rate of methylmercury production and thus bioaccumulation in marine foodwebs. Factors affecting porewater partitioning (Kd) and methylation of Hg(II) were examined at 11 sites in sediment of 4 biogeochemically diverse estuaries in the Northeast U.S. In Long Island Sound, 88% of total mercury (HgT) log Kd variability was described by porewater dissolved organic carbon concentration and sediment total sulfur (S) content. Whereas across all estuaries, regression analyses showed that S alone drives about 70% of Kd variability and 50% of changes in methylation rates; and the inclusion of DOC and sulfides did not improve the prediction. Thus, we demonstrated that S is a better predictor of HgT log Kd than the sediment organic matter across multiple estuaries, and while organic matter and S are interchangeable in small-scale studies, on a larger scale, sediment S content is the simplest and most effective variable to measure.

  10. Sediment-Porewater Partitioning, Total Sulfur and Methylmercury Production in Estuaries

    PubMed Central

    Schartup, Amina T.; Balcom, Prentiss H.; Mason, Robert P.

    2014-01-01

    Mercury (Hg) speciation and the activity of Hg(II)-methylating bacteria are responsible for the rate of methylmercury (MeHg) production and thus bioaccumulation in marine foodwebs. Factors affecting porewater partitioning (Kd) and methylation of Hg(II) were examined at 11 sites in sediment of 4 biogeochemically diverse estuaries in the Northeast U. S. In Long Island Sound, 88% of total mercury (HgT) log Kd variability was described by porewater dissolved organic carbon concentration and sediment total sulfur (S) content. Whereas across all estuaries, regression analyses showed that S alone drives about 70% of Kd variability and 50% of changes in methylation rates; and the inclusion of DOC and sulfides did not improve the prediction. Thus, we demonstrated that S is a better predictor of HgT log Kd than the sediment organic matter across multiple estuaries, and while organic matter and S are interchangeable in small-scale studies, on a larger scale, sediment S content is the simplest and most effective variable to measure. PMID:24344684

  11. Mercury cycling in stream ecosystems. 2. Benthic methylmercury production and bed sediment - Pore water partitioning

    USGS Publications Warehouse

    Marvin-DiPasquale, M.; Lutz, M.A.; Brigham, M.E.; Krabbenhoft, D.P.; Aiken, G.R.; Orem, W.H.; Hall, B.D.

    2009-01-01

    Mercury speciation, controls on methylmercury (MeHg) production, and bed sediment - pore water partitioning of total Hg (THg) and MeHg were examined in bed sediment from eight geochemically diverse streams where atmospheric deposition was the predominant Hg input. Across all streams, sediment THg concentrations were best described as a combined function of sediment percent fines (%fines; particles < 63 ??m) and organic content. MeHg concentrations were best described as a combined function of organic content and the activity of the Hg(II)-methylating microbial community and were comparable to MeHg concentrations in streams with Hg inputs from industrial and mining sources. Whole sediment tin-reducible inorganic reactive Hg (Hg(II)R) was used as a proxy measure for the Hg(II) pool available for microbial methylation. In conjunction with radiotracer-derived rate constants of 203Hg(II) methylation, Hg(II)R was used to calculate MeHg production potential rates and to explain the spatial variability in MeHg concentration. The %Hg(II)R (of THg) was low (2.1 ?? 5.7%) and was inversely related to both microbial sulfate reduction rates and sediment total reduced sulfur concentration. While sediment THg concentrations were higher in urban streams, %MeHg and %Hg(II)R were higher in nonurban streams. Sediment pore water distribution coefficients (log Kd's) for both THg and MeHg were inversely related to the log-transformed ratio of pore water dissolved organic carbon (DOC) to bed sediment %fines. The stream with the highest drainage basin wetland density also had the highest pore water DOC ?? 2009 American Chemical Society.

  12. Comparison of modeling approaches for carbon partitioning: Impact on estimates of global net primary production and equilibrium biomass of woody vegetation from MODIS GPP

    Treesearch

    Takeshi Ise; Creighton M. Litton; Christian P. Giardina; Akihiko Ito

    2010-01-01

    Partitioning of gross primary production (GPP) to aboveground versus belowground, to growth versus respiration, and to short versus long�]lived tissues exerts a strong influence on ecosystem structure and function, with potentially large implications for the global carbon budget. A recent meta-analysis of forest ecosystems suggests that carbon partitioning...

  13. Partition of actinides and fission products between metal and molten salt phases: Theory, measurement, and application to IFR pyroprocess development

    SciTech Connect

    Ackerman, J.P.; Johnson, T.R.

    1993-10-01

    The chemical basis of Integral Fast Reactor fuel reprocessing (pyroprocessing) is partition of fuel, cladding, and fission product elements between molten LiCl-KCl and either a solid metal phase or a liquid cadmium phase. The partition reactions are described herein, and the thermodynamic basis for predicting distributions of actinides and fission products in the pyroprocess is discussed. The critical role of metal-phase activity coefficients, especially those of rare earth and the transuranic elements, is described. Measured separation factors, which are analogous to equilibrium constants but which involve concentrations rather than activities, are presented. The uses of thermodynamic calculations in process development are described, as are computer codes developed for calculating material flows and phase compositions in pyroprocessing.

  14. Maximum Entropy Production Modeling of Evapotranspiration Partitioning on Heterogeneous Terrain and Canopy Cover: advantages and limitations.

    NASA Astrophysics Data System (ADS)

    Gutierrez-Jurado, H. A.; Guan, H.; Wang, J.; Wang, H.; Bras, R. L.; Simmons, C. T.

    2015-12-01

    Quantification of evapotranspiration (ET) and its partition over regions of heterogeneous topography and canopy poses a challenge using traditional approaches. In this study, we report the results of a novel field experiment design guided by the Maximum Entropy Production model of ET (MEP-ET), formulated for estimating evaporation and transpiration from homogeneous soil and canopy. A catchment with complex terrain and patchy vegetation in South Australia was instrumented to measure temperature, humidity and net radiation at soil and canopy surfaces. Performance of the MEP-ET model to quantify transpiration and soil evaporation was evaluated during wet and dry conditions with independently and directly measured transpiration from sapflow and soil evaporation using the Bowen Ratio Energy Balance (BREB). MEP-ET transpiration shows remarkable agreement with that obtained through sapflow measurements during wet conditions, but consistently overestimates the flux during dry periods. However, an additional term introduced to the original MEP-ET model accounting for higher stomatal regulation during dry spells, based on differences between leaf and air vapor pressure deficits and temperatures, significantly improves the model performance. On the other hand, MEP-ET soil evaporation is in good agreement with that from BREB regardless of moisture conditions. The experimental design allows a plot and tree scale quantification of evaporation and transpiration respectively. This study confirms for the first time that the MEP-ET originally developed for homogeneous open bare soil and closed canopy can be used for modeling ET over heterogeneous land surfaces. Furthermore, we show that with the addition of an empirical function simulating the plants ability to regulate transpiration, and based on the same measurements of temperature and humidity, the method can produce reliable estimates of ET during both wet and dry conditions without compromising its parsimony.

  15. GEMAS: prediction of solid-solution partitioning coefficients (Kd) for cationic metals in soils using mid-infrared diffuse reflectance spectroscopy.

    PubMed

    Janik, Leslie J; Forrester, Sean T; Soriano-Disla, José M; Kirby, Jason K; McLaughlin, Michael J; Reimann, Clemens

    2015-02-01

    Partial least squares regression (PLSR) models, using mid-infrared (MIR) diffuse reflectance Fourier-transformed (DRIFT) spectra, were used to predict distribution coefficient (Kd) values for selected added soluble metal cations (Ag(+), Co(2+), Cu(2+), Mn(2+), Ni(2+), Pb(2+), Sn(4+), and Zn(2+)) in 4813 soils of the Geochemical Mapping of Agricultural Soils (GEMAS) program. For the development of the PLSR models, approximately 500 representative soils were selected based on the spectra, and Kd values were determined using a single-point soluble metal or radioactive isotope spike. The optimum models, using a combination of MIR-DRIFT spectra and soil pH, resulted in good predictions for log Kd+1 for Co, Mn, Ni, Pb, and Zn (R(2) ≥ 0.83) but poor predictions for Ag, Cu, and Sn (R(2)  < 0.50). These models were applied to the prediction of log Kd+1 values in the remaining 4313 unknown soils. The PLSR models provide a rapid and inexpensive tool to assess the mobility and potential availability of selected metallic cations in European soils. Further model development and validation will be needed to enable the prediction of log K(d+1) values in soils worldwide with different soil types and properties not covered in the existing model.

  16. Uncertain Henry's law constants compromise equilibrium partitioning calculations of atmospheric oxidation products

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Yuan, Tiange; Wood, Stephen A.; Goss, Kai-Uwe; Li, Jingyi; Ying, Qi; Wania, Frank

    2017-06-01

    Gas-particle partitioning governs the distribution, removal, and transport of organic compounds in the atmosphere and the formation of secondary organic aerosol (SOA). The large variety of atmospheric species and their wide range of properties make predicting this partitioning equilibrium challenging. Here we expand on earlier work and predict gas-organic and gas-aqueous phase partitioning coefficients for 3414 atmospherically relevant molecules using COSMOtherm, SPARC Performs Automated Reasoning in Chemistry (SPARC), and poly-parameter linear free-energy relationships. The Master Chemical Mechanism generated the structures by oxidizing primary emitted volatile organic compounds. Predictions for gas-organic phase partitioning coefficients (KWIOM/G) by different methods are on average within 1 order of magnitude of each other, irrespective of the numbers of functional groups, except for predictions by COSMOtherm and SPARC for compounds with more than three functional groups, which have a slightly higher discrepancy. Discrepancies between predictions of gas-aqueous partitioning (KW/G) are much larger and increase with the number of functional groups in the molecule. In particular, COSMOtherm often predicts much lower KW/G for highly functionalized compounds than the other methods. While the quantum-chemistry-based COSMOtherm accounts for the influence of intra-molecular interactions on conformation, highly functionalized molecules likely fall outside of the applicability domain of the other techniques, which at least in part rely on empirical data for calibration. Further analysis suggests that atmospheric phase distribution calculations are sensitive to the partitioning coefficient estimation method, in particular to the estimated value of KW/G. The large uncertainty in KW/G predictions for highly functionalized organic compounds needs to be resolved to improve the quantitative treatment of SOA formation.

  17. Plasmolysis, red blood cell partitioning, and plasma protein binding of etofibrate, clofibrate, and their degradation products.

    PubMed

    Altmayer, P; Garrett, E R

    1983-11-01

    Etofibrate (I), the ethylene glycol diester of clofibric and nicotinic acids, degrades almost equally through both half-esters with half-lives of approximately 10 and 1 min in fresh dog and human plasma, respectively. The nicotinate V degrades with half-lives of approximately 12 hr and 50 min in fresh dog and human plasma, respectively. Ester III and clofibrate VI degrade by saturable Michaelis-Menten kinetics in fresh human plasma, with similar maximum initial rates and respective terminal first-order half-lives of 12 and 26 min. Tetraethyl pyrophosphate at 100 micrograms/ml inhibited human plasma and red blood cell esterases permitting plasma protein binding and red blood cell partitioning studies. The red blood cell-plasma water partition coefficient was 5.4 for 0.2-80 micrograms/ml of I. Clofibrate (VI) showed a saturable erythrocyte partitioning that decreased from 7.8 (10 micrograms/ml) to 1 (50 micrograms/ml). The strong binding of I and VI to ultrafiltration membranes necessitated the determination of their plasma protein binding by the method of variable plasma concentrations of erythrocyte suspensions to give 96.6% (0.2-80 micrograms/ml) and 98.2% (13.6-108.4 micrograms/ml) binding, respectively. Methods for the determination of the parameters of saturable and nonsaturable plasma protein binding for unstable and membrane-binding drugs by the method of variable plasma concentrations in partitioning erythrocyte suspensions are presented.

  18. Effects of the partitioning of diffuse and direct solar radiation on satellite-based modeling of crop gross primary production

    NASA Astrophysics Data System (ADS)

    Xin, Qinchuan; Gong, Peng; Suyker, Andrew E.; Si, Yali

    2016-08-01

    Modeling crop gross primary production (GPP) is critical to understanding the carbon dynamics of agro-ecosystems. Satellite-based studies have widely used production efficiency models (PEM) to estimate cropland GPP, wherein light use efficiency (LUE) is a key model parameter. One factor that has not been well considered in many PEMs is that canopy LUE could vary with illumination conditions. This study investigates how the partitioning of diffuse and direct solar radiation influences cropland GPP using both flux tower and satellite data. The field-measured hourly LUE under cloudy conditions was 1.50 and 1.70 times higher than that under near clear-sky conditions for irrigated corn and soybean, respectively. We applied a two-leaf model to simulate the canopy radiative transfer process, where modeled photosynthetically active radiation (PAR) absorbed by canopy agreed with tower measurements (R2 = 0.959 and 0.914 for corn and soybean, respectively). Derived canopy LUE became similar after accounting for the impact of light saturation on leaf photosynthetic capacity under varied illumination conditions. The impacts of solar radiation partitioning on satellite-based modeling of crop GPP was examined using vegetation indices (VI) derived from MODIS data. Consistent with the field modeling results, the relationship between daily GPP and PAR × VI under varied illumination conditions showed different patterns in terms of regression slope and intercept. We proposed a function to correct the influences of direct and diffuse radiation partitioning and the explained variance of flux tower GPP increased in all experiments. Our results suggest that the non-linear response of leaf photosynthesis to light absorption contributes to higher canopy LUE on cloudy days than on clear days. We conclude that accounting for the impacts of solar radiation partitioning is necessary for modeling crop GPP on a daily or shorter basis.

  19. Production of U{sub 3}O{sub 8} Using Macroporous Sulfonate Cation Exchange Resins in the Bead Form

    SciTech Connect

    Mosley, W.C.

    2001-08-16

    The use of cation exchange resin to product U{sub 3}O{sub 8} suitable for powder metallurgy fabrication of reactor fuel tubes with Al-U{sub 3}O{sub 8} cores is being investigated. This report presents the results of those studies.

  20. Degradation Product Partitioning in Source Zones Containing Chlorinated Ethene Dense Non-Aqueous-Phase Liquid

    DTIC Science & Technology

    2010-01-01

    organisms, with complete transformation to ethene linked to the presence and activity of Dehalococcoides spp. (5, 7). Differences in electron donor...studies). Previous studies have determined this duration sufficient to reach equilibrium (16, 20). The difference in the level of temperature control... isothermal flash calculation. Use of the RLA to calculate the partition coefficient implies that the Henry law coefficient is known at all temperatures of

  1. Non-structural carbohydrate partitioning in grass stems: a target to increase yield stability, stress tolerance, and biofuel production.

    PubMed

    Slewinski, Thomas L

    2012-08-01

    A dramatic change in agricultural crops is needed in order to keep pace with the demands of an increasing human population, exponential need for renewable fuels, and uncertain climatic changes. Grasses make up the vast majority of agricultural commodities. How these grasses capture, transport, and store carbohydrates underpins all aspects of crop productivity. Sink-source dynamics within the plant direct how much, where, and when carbohydrates are allocated, as well as determine the harvestable tissue. Carbohydrate partitioning can limit the yield capacity of these plants, thus offering a potential target for crop improvement. Grasses have the ability to buffer this sink-source interaction by transiently storing carbohydrates in stem tissue when production from the source is greater than whole-plant demand. These reserves improve yield stability in grain crops by providing an alternative source when photosynthetic capacity is reduced during the later phases of grain filling, or during periods of environmental and biotic stresses. Domesticated grasses such as sugarcane and sweet sorghum have undergone selection for high accumulation of stem carbohydrates, which serve as the primary sources of sugars for human and animal consumption, as well as ethanol production for fuel. With the enormous expectations placed on agricultural production in the near future, research into carbohydrate partitioning in grasses is essential for maintaining and increasing yields in grass crops. This review highlights the current knowledge of non-structural carbohydrate dynamics in grass stems and discusses the impacts of stem reserves in essential agronomic grasses.

  2. Production of Phytotoxic Cationic α-Helical Antimicrobial Peptides in Plant Cells Using Inducible Promoters

    PubMed Central

    Company, Nuri; Nadal, Anna; Ruiz, Cristina; Pla, Maria

    2014-01-01

    Synthetic linear antimicrobial peptides with cationic α-helical structures, such as BP100, have potent and specific activities against economically important plant pathogenic bacteria. They are also recognized as valuable therapeutics and preservatives. However, highly active BP100 derivatives are often phytotoxic when expressed at high levels as recombinant peptides in plants. Here we demonstrate that production of recombinant phytotoxic peptides in transgenic plants is possible by strictly limiting transgene expression to certain tissues and conditions, and specifically that minimization of this expression during transformation and regeneration of transgenic plants is essential to obtain viable plant biofactories. On the basis of whole-genome transcriptomic data available online, we identified the Os.hsp82 promoter that fulfilled this requirement and was highly induced in response to heat shock. Using this strategy, we generated transgenic rice lines producing moderate yields of severely phytotoxic BP100 derivatives on exposure to high temperature. In addition, a threshold for gene expression in selected tissues and stages was experimentally established, below which the corresponding promoters should be suitable for driving the expression of recombinant phytotoxic proteins in genetically modified plants. In view of the growing transcriptomics data available, this approach is of interest to assist promoter selection for specific purposes. PMID:25387106

  3. Production of phytotoxic cationic α-helical antimicrobial peptides in plant cells using inducible promoters.

    PubMed

    Company, Nuri; Nadal, Anna; Ruiz, Cristina; Pla, Maria

    2014-01-01

    Synthetic linear antimicrobial peptides with cationic α-helical structures, such as BP100, have potent and specific activities against economically important plant pathogenic bacteria. They are also recognized as valuable therapeutics and preservatives. However, highly active BP100 derivatives are often phytotoxic when expressed at high levels as recombinant peptides in plants. Here we demonstrate that production of recombinant phytotoxic peptides in transgenic plants is possible by strictly limiting transgene expression to certain tissues and conditions, and specifically that minimization of this expression during transformation and regeneration of transgenic plants is essential to obtain viable plant biofactories. On the basis of whole-genome transcriptomic data available online, we identified the Os.hsp82 promoter that fulfilled this requirement and was highly induced in response to heat shock. Using this strategy, we generated transgenic rice lines producing moderate yields of severely phytotoxic BP100 derivatives on exposure to high temperature. In addition, a threshold for gene expression in selected tissues and stages was experimentally established, below which the corresponding promoters should be suitable for driving the expression of recombinant phytotoxic proteins in genetically modified plants. In view of the growing transcriptomics data available, this approach is of interest to assist promoter selection for specific purposes.

  4. A comprehensive classification of solvent systems used for natural product purifications in countercurrent and centrifugal partition chromatography.

    PubMed

    Skalicka-Woźniak, Krystyna; Garrard, Ian

    2015-11-01

    Using both library paper copies and modern electronic copies, every known, published, English-language journal paper that employs either countercurrent or centrifugal partition chromatography solvent systems for natural product purifications has been studied and the solvent systems classified in a comprehensive database. Papers were studied from the earliest found examples containing natural product separations in 1984 until the end of 2014. In total, 2594 solvent systems have been classified, of which 272 are gradient systems. To observe any trends or patterns in the data, the natural product solutes were divided into 21 classes and the solvent systems into 7 different types. The complete database, sorted according to natural product class, is available for download to assist separation scientists in future liquid-liquid chromatography purifications.

  5. Characterization and production of multifunctional cationic peptides derived from rice proteins.

    PubMed

    Taniguchi, Masayuki; Ochiai, Akihito

    2017-04-01

    Food proteins have been identified as a source of bioactive peptides. These peptides are inactive within the sequence of the parent protein and must be released during gastrointestinal digestion, fermentation, or food processing. Of bioactive peptides, multifunctional cationic peptides are more useful than other peptides that have specific activity in promotion of health and/or the treatment of diseases. We have identified and characterized cationic peptides from rice enzymes and proteins that possess multiple functions, including antimicrobial, endotoxin-neutralizing, arginine gingipain-inhibitory, and/or angiogenic activities. In particular, we have elucidated the contribution of cationic amino acids (arginine and lysine) in the peptides to their bioactivities. Further, we have discussed the critical parameters, particularly proteinase preparations and fractionation or purification, in the enzymatic hydrolysis process for producing bioactive peptides from food proteins. Using an ampholyte-free isoelectric focusing (autofocusing) technique as a tool for fractionation, we successfully prepared fractions containing cationic peptides with multiple functions.

  6. Partitioning of CH4 and CO2 Production Originating from Rice Straw, Soil and Root Organic Carbon in Rice Microcosms

    PubMed Central

    Yuan, Quan; Pump, Judith; Conrad, Ralf

    2012-01-01

    Flooded rice fields are an important source of the greenhouse gas CH4. Possible carbon sources for CH4 and CO2 production in rice fields are soil organic matter (SOM), root organic carbon (ROC) and rice straw (RS), but partitioning of the flux between the different carbon sources is difficult. We conducted greenhouse experiments using soil microcosms planted with rice. The soil was amended with and without 13C-labeled RS, using two 13C-labeled RS treatments with equal RS (5 g kg−1 soil) but different δ13C of RS. This procedure allowed to determine the carbon flux from each of the three sources (SOM, ROC, RS) by determining the δ13C of CH4 and CO2 in the different incubations and from the δ13C of RS. Partitioning of carbon flux indicated that the contribution of ROC to CH4 production was 41% at tillering stage, increased with rice growth and was about 60% from the booting stage onwards. The contribution of ROC to CO2 was 43% at tillering stage, increased to around 70% at booting stage and stayed relatively constant afterwards. The contribution of RS was determined to be in a range of 12–24% for CH4 production and 11–31% for CO2 production; while the contribution of SOM was calculated to be 23–35% for CH4 production and 13–26% for CO2 production. The results indicate that ROC was the major source of CH4 though RS application greatly enhanced production and emission of CH4 in rice field soil. Our results also suggest that data of CH4 dissolved in rice field could be used as a proxy for the produced CH4 after tillering stage. PMID:23162678

  7. Influence of organic carbon and nitrate loading on partitioning between dissimilatory nitrate reduction to ammonium (DNRA) and N2 production

    NASA Astrophysics Data System (ADS)

    Hardison, Amber K.; Algar, Christopher K.; Giblin, Anne E.; Rich, Jeremy J.

    2015-09-01

    were inferred based on modeled rates as well as stoichiometric conversions of NH4+ production in pre-incubated vials. Based on model results, partitioning between DNRA and N2 production was positively linearly related to the ratio of C decomposition to NO3- reduction rates (C/NO3-) but not C decomposition alone. Based on vial results, partitioning was significantly related to C decomposition. Overall, this study supports the hypothesis that high organic C loading is a prerequisite for DNRA to be favored over denitrification but that N2 production may still be significant when organic C is high depending on NO3- availability.

  8. How drought severity constrains gross primary production(GPP) and its partitioning among carbon pools in a Quercus ilex coppice?

    NASA Astrophysics Data System (ADS)

    Rambal, S.; Lempereur, M.; Limousin, J. M.; Martin-StPaul, N. K.; Ourcival, J. M.; Rodríguez-Calcerrada, J.

    2014-12-01

    The partitioning of photosynthates toward biomass compartments plays a crucial role in the carbon (C) sink function of forests. Few studies have examined how carbon is allocated toward plant compartments in drought-prone forests. We analyzed the fate of gross primary production (GPP) in relation to yearly water deficit in an old evergreen Mediterranean Quercus ilex coppice severely affected by water limitations. Carbon fluxes between the ecosystem and the atmosphere were measured with an eddy covariance flux tower running continuously since 2001. Discrete measurements of litterfall, stem growth and fAPAR allowed us to derive annual productions of leaves, wood, flowers and acorns, and an isometric relationship between stem and belowground biomass has been used to estimate perennial belowground growth. By combining eddy covariance fluxes with annual net primary productions (NPP), we managed to close a C budget and derive values of autotrophic, heterotrophic respirations and carbon-use efficiency (CUE; the ratio between NPP and GPP). Average values of yearly net ecosystem production (NEP), GPP and Reco were 282, 1259 and 977 g C m-2. The corresponding aboveground net primary production (ANPP) components were 142.5, 26.4 and 69.6 g C m-2 for leaves, reproductive effort (flowers and fruits) and stems, respectively. NEP, GPP and Reco were affected by annual water deficit. Partitioning to the different plant compartments was also impacted by drought, with a hierarchy of responses going from the most affected - the stem growth - to the least affected - the leaf production. The average CUE was 0.40, which is well in the range for Mediterranean-type forest ecosystems. CUE tended to decrease less drastically in response to drought than GPP and NPP did, probably due to drought acclimation of autotrophic respiration. Overall, our results provide a baseline for modeling the inter-annual variations of carbon fluxes and allocation in this widespread Mediterranean ecosystem, and

  9. Surface cationized cellulose nanofibrils for the production of contact active antimicrobial surfaces.

    PubMed

    Saini, Seema; Yücel Falco, Çiğdem; Belgacem, Mohamed Naceur; Bras, Julien

    2016-01-01

    In the last decade, a new fiber pretreatment has been proposed to make easy cellulose fibrillation into microfibrils. In this context, different surface cationized MFC was prepared by optimizing the experimental parameters for cellulose fibers pretreatment before fibrillation. All MFCs were characterized by conductometric titration to establish degree of substitution, field emission gun scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM) and optical microscopy assessed the effect of pretreatment on the morphology of the ensuing MFCs. Antibacterial activities of neat and cationized MFC samples were investigated against Gram positive bacteria (Bacillus subtilis, Staphylococcus aureus) and Gram negative bacteria (Escherichia coli). The CATMFC sample at DS greater than 0.18 displayed promising results with antibacterial properties without any leaching of quaternary ammonium into the environment. This work proved the potential of cationic MFCs with specific DS for contact active antimicrobial surface applications in active food packaging, medical packaging or in health and cosmetic field.

  10. Quasiclassical trajectory study of the F + H 2 system. Rate constants, kinetic isotope effects and energy partitioning among reaction products

    NASA Astrophysics Data System (ADS)

    Rosenman, Efrat; Persky, Avigdor

    1995-06-01

    Quasiclassical trajectory calculations were carried out for the reactions F + H 2, F + D 2, and F + HD, using two potential energy surfaces T5A and 6SEC. The results which include rate constants and kinetic isotope effects as a function of temperature, isotopic branching ratios for F + HD as a function off collision energy and the energy partitioning and vibrational state distributions of the products at room temperature, are compared with experimental data. For most of the quantities under study, the results for the 6SEC surface are in qualitative agreement with experiment, as opposed to the results for the T5A surface. The conclusions from the present study concerning the quality of the 6SEC surface are consistent with the conclusions of Aoiz et al. which are based mainly on calculations of vibrationally state resolved differential cross sections and vibrational distributions of products, for specific collision energies.

  11. Divalent cations enhance fluoride binding to Streptococcus mutans and Streptococcus sanguinis cells and subsequently inhibit bacterial acid production.

    PubMed

    Domon-Tawaraya, H; Nakajo, K; Washio, J; Ashizawa, T; Ichino, T; Sugawara, H; Fukumoto, S; Takahashi, N

    2013-01-01

    One preventive effect of topical fluoride application is derived from the fact that fluoride can inhibit bacterial acid production. Furthermore, divalent cations such as Ca(2+) and Mg(2+) increase the binding of fluoride to bacterial cells. These findings suggest that exposure of oral bacteria to fluoride in the presence of divalent cations increases fluoride binding to bacterial cells and subsequently enhances fluoride-induced inhibition of bacterial acid production. This study investigated the effects of fluoride exposure (0-20,000 ppm F) in the presence of Ca(2+) or Mg(2+) prior to glucose challenge on pH fall ability by bacterial sugar fermentation, as well as fluoride binding to bacterial cells by exposure to fluoride, and fluoride release from bacterial cells during bacterial sugar fermentation, using caries-related bacteria, Streptococcus mutans and Streptococcus sanguinis. The pH fall by both streptococci was inhibited by exposure to over 250 ppm F in the presence of Ca(2+) (p < 0.01), whereas in the presence of Mg(2+), the pH fall by S. mutans and S. sanguinis was inhibited after exposure to over 250 and 950 ppm F, respectively (p < 0.05). The amounts of fluoride binding to and released from streptococcal cells increased with the concentration of fluoride the cells were exposed to in the presence of Mg(2+), but were high enough even after 250 ppm F exposure in the presence of Ca(2+). The enhanced inhibition of acid production in the presence of divalent cations is probably due to the improved efficiency of fluoride binding to bacterial cells being improved via these divalent cations.

  12. Effects of soil structure destruction on methane production andcarbon partitioning between methanogenic pathways in tropical rain forestsoils

    SciTech Connect

    Teh, Yit Arn; Silver, Whendee L.

    2005-01-25

    Controls on methanogenesis are often determined fromlaboratory incubations of soils converted to slurries. Destruction ofsoil structure during slurry conversion may disrupt syntrophicassociations, kill methanogens, and/or alter the microsite distributionof methanogenic activity, suppressing CH4 production. The effects ofslurry conversion on methanogenesis were investigated to determine ifdisruption of aggregate structure impacted methanogenesis, substrateutilization, and C partitioning between methanogenic pathways. Soils werecollected from the tropical rain forest life zone of the LuquilloExperimental Forest, Puerto Rico, and exposed to different physicaldisturbances, including flooding and physical homogenization. Slurryconversion negatively impacted methanogenesis. Rates of CH4 productiondeclined by a factor of 17 after well-aggregated soils were converted toslurries. Significantly more 13C-acetate was recovered in CO2 compared toCH4 after slurry conversion, suggesting that methanogens consumed lessacetate after slurry conversion and may have competed less effectivelywith other anaerobes for acetate. Isotopic data indicate that therelative partitioning of C between aceticlastic and hydrogenotrophicpathways wasunchanged after slurry conversion. These data suggest thatexperiments which destroy soil structure may significantly underestimatemethanogenesis and overestimate the potential for other microorganisms tocompete with methanogens for organic substrates. Current knowledge of thefactors that regulate methanogenesis in soil may be biased by thefindings of slurry-based experiments, that do not accurately representthe complex, spatially heterogeneous conditions found in well-aggregatedsoils.

  13. Evapotranspiration partitioning and variation of sap flow in female and male parents of maize for hybrid seed production in arid region

    USDA-ARS?s Scientific Manuscript database

    Understanding the variation of sap flow in female and male parents of maize for hybrid seed production and evapotranspiration (ET) partitioning is useful in accurately determining water use of the female and male parents and improving irrigation management of maize for hybrid seed production. Sap fl...

  14. Isolation and Characterization of the 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) Radical Cation-Scavenging Reaction Products of Arbutin.

    PubMed

    Tai, Akihiro; Ohno, Asako; Ito, Hideyuki

    2016-09-28

    Arbutin, a glucoside of hydroquinone, has shown strong 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation-scavenging activity, especially in reaction stoichiometry. This study investigated the reaction mechanism of arbutin against ABTS radical cation that caused high stoichiometry of arbutin in an ABTS radical cation-scavenging assay. HPLC analysis of the reaction mixture of arbutin and ABTS radical cation indicated the existence of two reaction products. The two reaction products were purified and identified to be a covalent adduct of arbutin with an ABTS degradation fragment and 3-ethyl-6-sulfonate benzothiazolone. A time-course study of the radical-scavenging reactions of arbutin and the two reaction products suggested that one molecule of arbutin scavenges three ABTS radical cation molecules to generate an arbutin-ABTS fragment adduct as a final reaction product. The results suggest that one molecule of arbutin reduced two ABTS radical cation molecules to ABTS and then cleaved the third ABTS radical cation molecule to generate two products, an arbutin-ABTS fragment adduct and 3-ethyl-6-sulfonate benzothiazolone.

  15. Partition search

    SciTech Connect

    Ginsberg, M.L.

    1996-12-31

    We introduce a new form of game search called partition search that incorporates dependency analysis, allowing substantial reductions in the portion of the tree that needs to be expanded. Both theoretical results and experimental data are presented. For the game of bridge, partition search provides approximately as much of an improvement over existing methods as {alpha}-{beta} pruning provides over minimax.

  16. Carbon partitioning in photosynthesis.

    PubMed

    Melis, Anastasios

    2013-06-01

    The work seeks to raise awareness of a fundamental problem that impacts the renewable generation of fuels and chemicals via (photo)synthetic biology. At issue is regulation of the endogenous cellular carbon partitioning between different biosynthetic pathways, over which the living cell exerts stringent control. The regulation of carbon partitioning in photosynthesis is not understood. In plants, microalgae and cyanobacteria, methods need be devised to alter photosynthetic carbon partitioning between the sugar, terpenoid, and fatty acid biosynthetic pathways, to lower the prevalence of sugar biosynthesis and correspondingly upregulate terpenoid and fatty acid hydrocarbons production in the cell. Insight from unusual but naturally occurring carbon-partitioning processes can help in the design of blueprints for improved photosynthetic fuels and chemicals production. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Sucrose synthase affects carbon partitioning to increase cellulose production and altered cell wall ultrastructure.

    PubMed

    Coleman, Heather D; Yan, Jimmy; Mansfield, Shawn D

    2009-08-04

    Overexpression of the Gossypium hirsutum sucrose synthase (SuSy) gene under the control of 2 promoters was examined in hybrid poplar (Populus alba x grandidentata). Analysis of RNA transcript abundance, enzyme activity, cell wall composition, and soluble carbohydrates revealed significant changes in the transgenic lines. All lines showed significantly increased SuSy enzyme activity in developing xylem. This activity manifested in altered secondary cell wall cellulose content per dry weight in all lines, with increases of 2% to 6% over control levels, without influencing plant growth. The elevated concentration of cellulose was associated with an increase in cell wall crystallinity but did not alter secondary wall microfibril angle. This finding suggests that the observed increase in crystallinity is a function of altered carbon partitioning to cellulose biosynthesis rather than the result of tension wood formation. Furthermore, the augmented deposition of cellulose in the transgenic lines resulted in thicker xylem secondary cell wall and consequently improved wood density. These findings clearly implicate SuSy as a key regulator of sink strength in poplar trees and demonstrate the tight association of SuSy with cellulose synthesis and secondary wall formation.

  18. Production and Preliminary Characterization of Monoclonal Antibodies against Cationic Peanut Peroxidase 1

    PubMed Central

    Hu, Chunfang; Carbonera, Daniela; van Huystee, Robert

    1987-01-01

    Ten monoclonal antibodies (McAbs) have been produced against the cationic peroxidase from peanut suspension cell culture. Eight of these antibodies were found to be of the immunoglobulin (Ig)G1 subclass and two were of IgA subclass. A combination of competitive enzyme-linked immunosorbent assay, Western blotting analysis, and direct antigen-binding assay revealed that the antibodies are directed against four different epitopes on the cationic peroxidase and the McAbs can be subdivided into four groups. Only group A inhibits peroxidase activity. Group B and D bind equally well to the native and the denatured form of cationic peroxidase, whereas the remaining McAbs react with more or less reduced affinity to the denatured antigen. Group C probably recognizes a conformation-dependent epitope. All the McAbs cross react weakly with the anionic peanut peroxidase, suggesting a structural nonidentity as well as some similarity between these two peroxidase isozymes. Cross reactivities of these McAbs with peroxidases of various plant species were also demonstrated. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:16665674

  19. Canopy leaf area constrains [CO2]-induced enhancement of productivity and partitioning among aboveground carbon pools.

    Treesearch

    Heather R. McCarthy; Ram Oren; Adrien C. Finzi; Kurt H. Johnsen

    2006-01-01

    Net primary productivity (NPP) is enhanced under future atmospheric [CO2] in temperate forests representing a broad range of productivity. Yet questions remain in regard to how elevated [CO2]-induced NPP enhancement may be affected by climatic variations and limiting nutrient resources, as well as how this additional...

  20. Use of wastes derived from earthquakes for the production of concrete masonry partition wall blocks

    SciTech Connect

    Xiao Zhao; Ling, Tung-Chai; Kou, Shi-Cong; Wang Qingyuan; Poon, Chi-Sun

    2011-08-15

    Highlights: > Solved the scientific and technological challenges impeding use of waste rubble derived from earthquake, by providing an alternative solution of recycling the waste in moulded concrete block products. > Significant requirements for optimum integration on the utilization of the waste aggregates in the production of concrete blocks are investigated. > A thorough understanding of the mechanical properties of concrete blocks made with waste derived from earthquake is reported. - Abstract: Utilization of construction and demolition (C and D) wastes as recycled aggregates in the production of concrete and concrete products have attracted much attention in recent years. However, the presence of large quantities of crushed clay brick in some the C and D waste streams (e.g. waste derived collapsed masonry buildings after an earthquake) renders the recycled aggregates unsuitable for high grade use. One possibility is to make use of the low grade recycled aggregates for concrete block production. In this paper, we report the results of a comprehensive study to assess the feasibility of using crushed clay brick as coarse and fine aggregates in concrete masonry block production. The effects of the content of crushed coarse and fine clay brick aggregates (CBA) on the mechanical properties of non-structural concrete block were quantified. From the experimental test results, it was observed that incorporating the crushed clay brick aggregates had a significant influence on the properties of blocks. The hardened density and drying shrinkage of the block specimens decreased with an increase in CBA content. The use of CBA increased the water absorption of block specimens. The results suggested that the amount of crushed clay brick to be used in concrete masonry blocks should be controlled at less than 25% (coarse aggregate) and within 50-75% for fine aggregates.

  1. Partitioning of pine bark components to obtain a value-added product for plywood manufacture

    Treesearch

    Thomas L. Eberhardt; Karen G. Reed; Chi-Leung So

    2009-01-01

    Southern yellow pine (SYP) bark particles and bark extracts have been used only to a limited extent in wood-based composites due to poor performance relative to existing products and/or economic barriers. Our efforts to identify alternative applications for this biomass resource require the development of an improved understanding of the interrelationships between bark...

  2. Use of wastes derived from earthquakes for the production of concrete masonry partition wall blocks.

    PubMed

    Xiao, Zhao; Ling, Tung-Chai; Kou, Shi-Cong; Wang, Qingyuan; Poon, Chi-Sun

    2011-08-01

    Utilization of construction and demolition (C&D) wastes as recycled aggregates in the production of concrete and concrete products have attracted much attention in recent years. However, the presence of large quantities of crushed clay brick in some the C&D waste streams (e.g. waste derived collapsed masonry buildings after an earthquake) renders the recycled aggregates unsuitable for high grade use. One possibility is to make use of the low grade recycled aggregates for concrete block production. In this paper, we report the results of a comprehensive study to assess the feasibility of using crushed clay brick as coarse and fine aggregates in concrete masonry block production. The effects of the content of crushed coarse and fine clay brick aggregates (CBA) on the mechanical properties of non-structural concrete block were quantified. From the experimental test results, it was observed that incorporating the crushed clay brick aggregates had a significant influence on the properties of blocks. The hardened density and drying shrinkage of the block specimens decreased with an increase in CBA content. The use of CBA increased the water absorption of block specimens. The results suggested that the amount of crushed clay brick to be used in concrete masonry blocks should be controlled at less than 25% (coarse aggregate) and within 50-75% for fine aggregates.

  3. Partition Equilibrium

    NASA Astrophysics Data System (ADS)

    Feldman, Michal; Tennenholtz, Moshe

    We introduce partition equilibrium and study its existence in resource selection games (RSG). In partition equilibrium the agents are partitioned into coalitions, and only deviations by the prescribed coalitions are considered. This is in difference to the classical concept of strong equilibrium according to which any subset of the agents may deviate. In resource selection games, each agent selects a resource from a set of resources, and its payoff is an increasing (or non-decreasing) function of the number of agents selecting its resource. While it has been shown that strong equilibrium exists in resource selection games, these games do not possess super-strong equilibrium, in which a fruitful deviation benefits at least one deviator without hurting any other deviator, even in the case of two identical resources with increasing cost functions. Similarly, strong equilibrium does not exist for that restricted two identical resources setting when the game is played repeatedly. We prove that for any given partition there exists a super-strong equilibrium for resource selection games of identical resources with increasing cost functions; we also show similar existence results for a variety of other classes of resource selection games. For the case of repeated games we identify partitions that guarantee the existence of strong equilibrium. Together, our work introduces a natural concept, which turns out to lead to positive and applicable results in one of the basic domains studied in the literature.

  4. Energy Partitioning to Product Translation in the Infrared Multiphoton Dissociation of Diethyl Ether.

    DTIC Science & Technology

    1983-06-07

    cm2 by attenuating the laser beam on passing it through a gas cell filled with from 0 to 360 torr of C2H4. The dissociation products were detected in...because the energies required to dissociate C2H5OH or CH3CHO to their smaller ion fragments are known to be small , -15 kcal/mole, and the ionization...a small fraction of the total number of dissociations . With increasing laser power, the average energy level a molecule will reach above the

  5. Microbial Ecological Niche Partitioning Affects N2 gas Production in the Largest Marine Oxygen Minimum Zone

    NASA Astrophysics Data System (ADS)

    Fuchsman, C. A.; Penn, J. L.; Devol, A.; Palevsky, H. I.; Deutsch, C. A.; Keil, R.; Ward, B. B.; Rocap, G.

    2016-02-01

    Up to half of oceanic N2 production occurs in oxygen minimum zones (OMZs). In the Eastern Tropical North Pacific OMZ in April 2012, we measured a nine station coast to open ocean transect of N2 gas in the heart of the ETNP OMZ. Depth profiles of excess N2 gas had dual maxima located at the top of the OMZ and at 300m. An ecosystem biogeochemical model of the ETNP was also found to produce dual maxima at stations with a shallow OMZ. The model indicated that high N2 production rates caused the upper N2 maxima while long water residence time caused the deeper maxima. At a low productivity open ocean station where dual N2 maxima were observed, we obtained a depth profile of metagenomic sequences from both free living and >30 μm fractions to determine which N2 producing microbes were living in these three ecological niches. We use a phylogenetically-aware approach to identify metagenomic sequences by placing them on reference trees, which allows us to utilize them in a semi-quantitative manner. Overall, genes for denitrification (napA, nirS, nirK, qnor, nosZ) were enriched on particles while anammox was free-living. However, separation of genes into phylotypes indicated that the system is more complicated. For example, 4 out of 5 N2O reductase denitrifier phylotypes were actually free-living, while the fifth, most abundant phylotype was particle-attached. In the water column, denitrifier and anammox genes were spatially separated with depth with denitrifiers focused on the top section of the OMZ and with anammox becoming abundant slightly deeper and being more dominant at the deep N2 maxima. Interestingly, different phylotypes of denitrifiers have different depth profiles, implying individual adaptations and niches. The presence of measurable ammonia (>200 nM) at the top 20m of the OMZ along with the very low numbers of anammox bacteria is consistent with recent shoaling of the OMZ at the time of sampling. Thus the spatial separation of denitrifiers and anammox at the

  6. Fission product partitioning in aerosol release from simulated spent nuclear fuel

    NASA Astrophysics Data System (ADS)

    Di Lemma, F. G.; Colle, J. Y.; Rasmussen, G.; Konings, R. J. M.

    2015-10-01

    Aerosols created by the vaporization of simulated spent nuclear fuel (simfuel) were produced by laser heating techniques and characterised by a wide range of post-analyses. In particular attention has been focused on determining the fission product behaviour in the aerosols, in order to improve the evaluation of the source term and consequently the risk associated with release from spent fuel sabotage or accidents. Different simulated spent fuels were tested with burn-up up to 8 at. %. The results from the aerosol characterisation were compared with studies of the vaporization process by Knudsen Effusion Mass Spectrometry and thermochemical equilibrium calculations. These studies permit an understanding of the aerosol gaseous precursors and the gaseous reactions taking place during the aerosol formation process.

  7. Aerosols and their influence on radiation partitioning and savanna productivity in northern Australia

    SciTech Connect

    Kanniah, K. D.; Beringer, J.; Tapper, N. J.; Long, Charles N.

    2010-05-01

    We investigated the effect of aerosols and clouds on the Net Ecosystem Productivity (NEP) of savannas in northern Australia using aerosol optical depth, clouds and radiation data from the Atmospheric Radiation Measurement (ARM) site in Darwin and carbon flux data measured from eddy covariance techniques from a site at Howard Springs, 35km southeast of Darwin. Generally we found that the concentration of aerosols in this region was relatively low than observed at other sites, therefore the proportion of diffuse radiation reaching the earths surface was only ~ 30%. As a result, we observed only a modest change in carbon uptake under aerosol laden skies and there was no significant difference for dry season Radiation Use Efficiency (RUE) between clear sky, aerosols or thin clouds. On the other hand thick clouds in the wet season produce much more diffuse radiation than aerosols or thin clouds and therefore the initial canopy quantum efficiency was seen to increase 45 and 2.5 times more than under thin clouds and aerosols respectively. The normalized carbon uptake under thick clouds is 57% and 50% higher than under aerosols and thin clouds respectively even though the total irradiance received under thick clouds was reduced 59% and 50% than under aerosols and thin clouds respectively. However, reduction in total irradiance decreases the mean absolute carbon uptake as much as 22% under heavy cloud cover compared to thin clouds or aerosols. Thus, any increase in aerosol concentration or cloud cover that can enhance the diffuse component may have large impacts on productivity in this region.

  8. Optimizing rainwater partitioning and millet production on degraded land in Niger using Water and Soil Conservation practices

    NASA Astrophysics Data System (ADS)

    Wildemeersch, Jasmien C. J.; Garba, Maman; Al-Barri, Bashar; Sabiou, Mahamane; Cornelis, Wim M.

    2015-04-01

    As a result of growing population pressure and severe soil erosion, farmers in the Sahel increasingly rely on degraded lands for millet production. The adverse Sahelian rainfall distribution and imbalanced rainfall partitioning over the rootzone of these degraded lands therefore calls for sustainable land management strategies that are water resource efficient. This study evaluates the soil-water balance of promising Nigerien Water and Soil Conservation (WSC) techniques (i.e., zaï pits, demi-lune microcatchments and scarification with standing crop residue) and their impact on millet yield by means of an in-situ field experiment (2011-2013) on degraded laterite soil classified as Plinthosol with a 1% slope. All WSC practices received the same amount of fertilizer and were compared to two control practices, one with and one without fertilizer. Soil-water content was recorded with a neutron probe till 105 cm depth and runoff by means of a cemented gutter directing runoff water with a multi-pipe divisor into a collector drum. WSC techniques proved to significantly reduce runoff (blue water) with overall runoff coefficients beings reduced from 25% (control practice) to 5-10%. Consequently, significantly more water was stored inside the catchments of the zaï pits and demi-lunes (green water). With the scarification treatment, no considerable differences in soil-water storage were found with the control. On the other hand, WSC practices had little impact on soil evaporation, which was only 12% of rainfall by the self-mulching soil. Crop transpiration increased with WSC and highest millet yields were found with zaï pits (4 to 5 times higher than under the fertilized control). Although rainwater was better partitioned in case of demi-lune microcatchments resulting in highest amounts of water stored in the soil, yield was only 40-60% of that with zaï pits. This was due to a higher plant density within each demi-lune microcatchment in an attempt to attain similar plant

  9. Partitioning of fission products from irradiated nitride fuel using inductive vaporization

    SciTech Connect

    Shcherbina, N.; Kulik, D.A.; Kivel, N.; Potthast, H.D.; Guenther-Leopold, I.

    2013-07-01

    Irradiated nitride fuel (Pu{sub 0.3}Zr{sub 0.7})N fabricated at PSI in frame of the CONFIRM project and having a burn-up of 10.4 % FIMA (Fission per Initial Metal Atom) has been investigated by means of inductive vaporization. The study of thermal stability and release behavior of Pu, Am, Zr and fission products (FPs) was performed in a wide temperature range (up to 2300 C. degrees) and on different redox conditions. On-line monitoring by ICP-MS detected low nitride stability and significant loss of Pu and Am at T>1900 C. degrees during annealing under inert atmosphere (Ar). The oxidative pre-treatment of nitride fuel on air at 1000 C. degrees resulted in strong retention of Pu and Am in the solid, as well as of most FPs. Thermodynamic modelling of elemental speciation using GEM-Selektor v.3 code (Gibbs Energy Minimization Selektor), supported by a comprehensive literature review on thermodynamics of actinides and FPs, revealed a number of binary compounds of Cs, Mo, Te, Sr and Ba to occur in the solid. Speciation of some FPs in the fuel is discussed and compared to earlier results of electron probe microanalysis (EPMA). Predominant vapor species predicted by GEM-Selektor calculations were Pu(g), Am(g) and N{sub 2}. Nitrogen can be completely released from the fuel after complete oxidation at 1000 C. degrees. With regard to the irradiated nitride reprocessing technology, this result can have an important practical application as an alternative way for {sup 15}N recovery. (authors)

  10. Partitioning of heat production in growing pigs as a tool to improve the determination of efficiency of energy utilization

    PubMed Central

    Labussière, Etienne; Dubois, Serge; van Milgen, Jaap; Noblet, Jean

    2013-01-01

    In growing pigs, the feed cost accounts for more than 60% of total production costs. The determination of efficiency of energy utilization through calorimetry measurements is of importance to sustain suitable feeding practice. The objective of this paper is to describe a methodology to correct daily heat production (HP) obtained from measurements in respiration chamber for the difference in energy expenditure related to physical activity between animals. The calculation is based on a preliminary published approach for partitioning HP between HP due to physical activity (AHP), thermic effect of feeding (TEF) and basal metabolic rate (fasting HP; FHP). Measurements with male growing pigs [mean body weight (BW): 115 kg] which were surgically castrated (SC), castrated through immunization against GnRH (IC), or kept as entire male (EM) were used as an example. Animals were fed the same diet ad-libitum and were housed individually in two 12-m3 open-circuit respiration chambers during 6 days when fed ad-libitum and one supplementary day when fasted. Physical activity was recorded through interruption of an infrared beam to detect standing and lying positions and with force transducers that recorded the mechanical force the animal exerted on the floor of the cage. Corrected AHP (AHPc), TEF (TEFc), and HP (HPc) were calculated to standardize the level of AHP between animals, assuming that the ratio between AHPc and ME intake should be constant. Inefficiency of energy utilization (sum of AHPc and TEFc) was lower than the inefficiency estimated from the slope of the classical relationship between HPc and ME intake but was associated with higher requirements for maintenance. Results indicate that EM pigs had higher FHP but lower TEFc than IC and SC pigs. These results agree with the higher contents in viscera of EM pigs that stimulate their basal metabolic rate and with the reduced utilization of dietary protein to provide energy for maintenance energy requirements and fat

  11. Partitioning of selected trace elements in coal combustion products from two coal-burning power plants in the United States

    USGS Publications Warehouse

    Swanson, Sharon M.; Engle, Mark A.; Ruppert, Leslie F.; Affolter, Ronald H.; Jones, Kevin B.

    2013-01-01

    Samples of feed coal (FC), bottom ash (BA), economizer fly ash (EFA), and fly ash (FA) were collected from power plants in the Central Appalachian basin and Colorado Plateau to determine the partitioning of As, Cr, Hg, Pb, and Se in coal combustion products (CCPs). The Appalachian plant burns a high-sulfur (about 3.9 wt.%) bituminous coal from the Upper Pennsylvanian Pittsburgh coal bed and operates with electrostatic precipitators (ESPs), with flue gas temperatures of about 163 °C in the ESPs. At this plant, As, Pb, Hg, and Se have the greatest median concentrations in FA samples, compared to BA and EFA. A mass balance (not including the FGD process) suggests that the following percentages of trace elements are captured in FA: As (48%), Cr (58%), Pb (54%), Se (20%), and Hg (2%). The relatively high temperatures of the flue gas in the ESPs and low amounts of unburned C in FA (0.5% loss-on-ignition for FA) may have led to the low amount of Hg captured in FA. The Colorado Plateau plant burns a blend of three low-S (about 0.74 wt.%) bituminous coals from the Upper Cretaceous Fruitland Formation and operates with fabric filters (FFs). Flue gas temperatures in the baghouses are about 104 °C. The elements As, Cr, Pb, Hg, and Se have the greatest median concentrations in the fine-grained fly ash product (FAP) produced by cyclone separators, compared to the other CCPs at this plant. The median concentration of Hg in FA (0.0983 ppm) at the Colorado Plateau plant is significantly higher than that for the Appalachian plant (0.0315 ppm); this higher concentration is related to the efficiency of FFs in Hg capture, the relatively low temperatures of flue gas in the baghouses (particularly in downstream compartments), and the amount of unburned C in FA (0.29% loss-on-ignition for FA).

  12. Overexpression of cationic amino acid transporter-1 increases nitric oxide production in hypoxic human pulmonary microvascular endothelial cells.

    PubMed

    Cui, Hongmei; Chen, Bernadette; Chicoine, Louis G; Nelin, Leif D

    2011-12-01

    1. The endogenous production of and/or the bioavailability of nitric oxide (NO) is decreased in pulmonary hypertensive diseases. L-arginine (L-arg) is the substrate for NO synthase (NOS). L-arg is transported into cells via the cationic amino acid transporters (CAT), of which there are two isoforms in endothelial cells, CAT-1 and CAT-2. 2. To test the hypothesis that hypoxia will decrease CAT expression and L-arg uptake resulting in decreased NO production in human pulmonary microvascular endothelial cells (hPMVEC), cells were incubated in either normoxia (21% O(2), 5% CO(2), balance N(2)) or hypoxia (1% O(2), 5% CO(2), balance N(2)). 3. The hPMVEC incubated in hypoxia had 80% less NO production than cells incubated in normoxia (P < 0.01). The hPMVEC incubated in hypoxia had significantly lower CAT-2 mRNA levels than normoxic hPMVEC (P < 0.005), and the transport of L-arg was 40% lower in hypoxic than in normoxic hPMVEC (P < 0.01). In hypoxic cells, overexpression of CAT-1 resulted in significantly greater L-arg transport and NO production (P < 0.05). 4. These results demonstrate that in hPMVEC, hypoxia decreased CAT-2 expression, L-arg uptake and NO production. Furthermore, the hypoxia-induced decrease in NO production in hPMVEC can be attenuated by overexpressing CAT in these cells. We speculate that the CAT may represent a novel therapeutic target for treating pulmonary hypertensive disorders. © 2011 The Authors. Clinical and Experimental Pharmacology and Physiology © 2011 Blackwell Publishing Asia Pty Ltd.

  13. Product Vectors in the Ranges of Multi-Partite States with Positive Partial Transposes and Permanents of Matrices

    NASA Astrophysics Data System (ADS)

    Kiem, Young-Hoon; Kye, Seung-Hyeok; Na, Joohan

    2015-09-01

    In this paper, we consider a system of homogeneous algebraic equations in complex variables and their conjugates, which arise naturally from the range criterion for separability of PPT states. We examine systematically these equations to get sufficient conditions for the existence of nontrivial solutions. This gives us possible upper bounds of ranks of PPT entangled edge states and their partial transposes. We will focus on the multi-partite cases, which are much more delicate than the bi-partite cases. We use the notion of permanents of matrices as well as techniques from algebraic geometry through the discussion.

  14. Determination of cationic surfactants as the preservatives in an oral solution and a cosmetic product by capillary electrophoresis.

    PubMed

    Oztekin, Nevin; Erim, F Bedia

    2005-04-29

    In this study, a capillary electrophoresis method was developed for the determination of cationic surfactants, benzethonium and cetylpyridinium ions, which are commonly used as preservatives in various pharmaceutical and cosmetic products. Determination was performed in a fused-silica capillary using a mixed 75 mmol/L phosphoric acid and 50% acetonitrile electrolyte at pH 2.5. Analysis of benzethonium and cetylpyridinium ions was achieved in around 5 min. Repeatability in migration times (R.S.D.%) for benzethonium and cetylpyridinium ions were 0.3. The calibration curves were linear from 0.0125 to 0.400 mmol/L for benzethonium ions and from 0.025 to 0.400 mmol/L for cetylpyridinium ions. The minimum detection limits (signal-to-noise ratio=3) are 1.47 and 4.30 microg/mL for benzethonium and cetylpyridinium ions, respectively. The method was applied to the analysis of benzethonium ion in a cosmetic product and cetylpyridinium ion in a mouthwash.

  15. Generation and integration of NaOH into NaCl clusters in supercritical water: a molecular dynamics study on hydrolysis product partitioning.

    PubMed

    Nahtigal, Istok G; Svishchev, Igor M

    2009-11-05

    The interaction of water with NaCl nanoparticles at supercritical conditions has been studied by molecular dynamics (MD) simulation. During the nanoparticle nucleation process, water is not only physically adsorbed to the periphery of the NaCl cluster but also exists in a confined state within subsurface regions for several picoseconds. Electrostatic fields generated by the coalescing ions are shown to be on the order of 10(10) V/m, which can drive the hydrolysis of confined water molecules. A molecular mechanism for the sodium chloride hydrolysis reaction at supercritical conditions is suggested. It involves proton transfer from water to chloride ions, followed by hydrolysis product partitioning. We provide MD results displaying the subsurface hydroxide localization in amorphous NaCl clusters, as well as the partitioning of the HCl into the supercritical water phase.

  16. Software Partitioning Technologies

    DTIC Science & Technology

    2001-05-29

    1 Software Partitioning Technologies Tim Skutt Smiths Aerospace 3290 Patterson Ave. SE Grand Rapids, MI 49512-1991 (616) 241-8645 skutt_timothy...Limitation of Abstract UU Number of Pages 12 2 Agenda n Software Partitioning Overview n Smiths Software Partitioning Technology n Software Partitioning...Partition Level OS Core Module Level OS Timers MMU I/O API Layer Partitioning Services 6 Smiths Software Partitioning Technology n Smiths has developed

  17. Gamma-Aminobutyric Acid Production Using Immobilized Glutamate Decarboxylase Followed by Downstream Processing with Cation Exchange Chromatography

    PubMed Central

    Lee, Seungwoon; Ahn, Jungoh; Kim, Yeon-Gu; Jung, Joon-Ki; Lee, Hongweon; Lee, Eun Gyo

    2013-01-01

    We have developed a gamma-aminobutyric acid (GABA) production technique using his-tag mediated immobilization of Escherichia coli-derived glutamate decarboxylase (GAD), an enzyme that catalyzes the conversion of glutamate to GABA. The GAD was obtained at 1.43 g/L from GAD-overexpressed E. coli fermentation and consisted of 59.7% monomer, 29.2% dimer and 2.3% tetramer with a 97.6% soluble form of the total GAD. The harvested GAD was immobilized to metal affinity gel with an immobilization yield of 92%. Based on an investigation of specific enzyme activity and reaction characteristics, glutamic acid (GA) was chosen over monosodium glutamate (MSG) as a substrate for immobilized GAD, resulting in conversion of 2.17 M GABA in a 1 L reactor within 100 min. The immobilized enzymes retained 58.1% of their initial activities after ten consecutive uses. By using cation exchange chromatography followed by enzymatic conversion, GABA was separated from the residual substrate and leached GAD. As a consequence, the glutamic acid was mostly removed with no detectable GAD, while 91.2% of GABA was yielded in the purification step. PMID:23322022

  18. A continuous process for biodiesel production in a fixed bed reactor packed with cation-exchange resin as heterogeneous catalyst.

    PubMed

    Feng, Yaohui; Zhang, Aiqing; Li, Jianxin; He, Benqiao

    2011-02-01

    Continuous esterification of free fatty acids (FFA) from acidified oil with methanol was carried out with NKC-9 cation-exchange resin in a fixed bed reactor with an internal diameter of 25 mm and a height of 450 mm to produce biodiesel. The results showed that the FFA conversion increased with increases in methanol/oil mass ratio, reaction temperature and catalyst bed height, whereas decreased with increases in initial water content in feedstock and feed flow rate. The FFA conversion kept over 98.0% during 500 h of continuous esterification processes under 2.8:1 methanol to oleic acid mass ratio, 44.0 cm catalyst bed height, 0.62 ml/min feed flow rate and 65°C reaction temperature, showing a much high conversion and operational stability. Furthermore, the loss of sulfonic acid groups from NKC-9 resin into the production was not found during continuous esterification. In sum, NKC-9 resin shows the potential commercial applications to esterification of FFA. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Austenite stabilization and high strength-elongation product of a low silicon aluminum-free hot-rolled directly quenched and dynamically partitioned steel

    SciTech Connect

    Tan, Xiao-Dong; Xu, Yun-Bo; Yang, Xiao-Long; Hu, Zhi-Ping; Peng, Fei; Ju, Xiao-Wei; Wu, Di

    2015-06-15

    Microstructures composed of lath martensite and retained austenite with volume fraction between 8.0 vol.% and 12.0 vol.% were obtained in a low-C low-Si Al-free steel through hot-rolling direct quenching and dynamical partitioning (HDQ&DP) processes. The austenite stabilization mechanism in the low-C low-Si Al-free steel under the special dynamical partitioning processes is investigated by analyzing the carbon partition behavior from martensite to austenite and the carbide precipitation-coarsening behavior in martensite laths combining with the possible hot rolling deformation inheritance. Results show that the satisfying retained austenite amount in currently studied low-Si Al-free HDQ&DP steel is caused by the high-efficiency carbon enrichment in the 30–80 nm thick regions of austenite near the interfaces in the hot-rolled ultra-fast cooled structure and the avoidance of serious carbides coarsening during the continuous cooling procedures. The excellent strength-elongation product reaching up to 26,000 MPa% shows that the involved HDQ&DP process is a promising method to develop a new generation of advanced high strength steel. - Highlights: • HDQ&DP processes were applied to a low-C low-Si Al-free steel. • Effective partitioning time during the continuous cooling processes is 1–220 s. • Retained austenite with volume fraction between 8.0 vol. % and 12.0 vol. % has been obtained. • The special austenite stabilization mechanism has been expounded.

  20. Development of high-productivity, strong cation-exchange adsorbers for protein capture by graft polymerization from membranes with different pore sizes

    PubMed Central

    Chenette, Heather C.S.; Robinson, Julie R.; Hobley, Eboni; Husson, Scott M.

    2012-01-01

    This paper describes the surface modification of macroporous membranes using ATRP (atom transfer radical polymerization) to create cation-exchange adsorbers with high protein binding capacity at high product throughput. The work is motivated by the need for a more economical and rapid capture step in downstream processing of protein therapeutics. Membranes with three reported nominal pore sizes (0.2, 0.45, 1.0 μm) were modified with poly(3-sulfopropyl methacrylate, potassium salt) tentacles, to create a high density of protein binding sites. A special formulation was used in which the monomer was protected by a crown ether to enable surface-initiated ATRP of this cationic polyelectrolyte. Success with modification was supported by chemical analysis using Fourier-transform infrared spectroscopy and indirectly by measurement of pure water flux as a function of polymerization time. Uniformity of modification within the membranes was visualized with confocal laser scanning microscopy. Static and dynamic binding capacities were measured using lysozyme protein to allow comparisons with reported performance data for commercial cation-exchange materials. Dynamic binding capacities were measured for flow rates ranging from 13 to 109 column volumes (CV)/min. Results show that this unique ATRP formulation can be used to fabricate cation-exchange membrane adsorbers with dynamic binding capacities as high as 70 mg/mL at a throughput of 100 CV/min and unprecedented productivity of 300 mg/mL/min. PMID:23175597

  1. Cationic electrodepositable coating composition comprising lignin

    DOEpatents

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  2. Evaluating dissolved organic carbon-water partitioning using polyparameter linear free energy relationships: Implications for the fate of disinfection by-products.

    PubMed

    Neale, Peta A; Escher, Beate I; Goss, Kai-Uwe; Endo, Satoshi

    2012-07-01

    The partitioning of micropollutants to dissolved organic carbon (DOC) can influence their toxicity, degradation, and transport in aquatic systems. In this study carbon-normalized DOC-water partition coefficients (K(DOC-w)) were measured for a range of non-polar and polar compounds with Suwannee River fulvic acid (FA) using headspace and solid-phase microextraction (SPME) methods. The studied chemicals were selected to represent a range of properties including van der Waal forces, cavity formation and hydrogen bonding interactions. The K(DOC-w) values were used to calibrate a polyparameter linear free energy relationship (pp-LFER). The difference between experimental and pp-LFER calculated K(DOC-w) values was generally less than 0.3 log units, indicating that the calibrated pp-LFER could provide a good indication of micropollutant interaction with FA, though statistical analysis suggested that more data would improve the predictive capacity of the model. A pp-LFER was also calibrated for Aldrich humic acid (HA) using K(DOC-w) values collected from the literature. Both experimental and pp-LFER calculated K(DOC-w) values for Aldrich HA were around one order of magnitude greater than Suwannee River FA. This difference can be explained by the higher cavity formation energy in Suwannee River FA. Experimental and pp-LFER calculated K(DOC-w) values were compared for halogenated alkanes and alkenes, including trihalomethane disinfection by-products, with good agreement between the two approaches. Experimental and calculated values show that DOC-water partitioning is generally low; indicating that sorption to DOC is not an important fate process for these chemicals in the environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Experimental determination of the partitioning coefficient and volatility of important BVOC oxidation products using the Aerosol Collection Module (ACM) coupled to a PTR-ToF-MS

    NASA Astrophysics Data System (ADS)

    Gkatzelis, G.; Hohaus, T.; Tillmann, R.; Schmitt, S. H.; Yu, Z.; Schlag, P.; Wegener, R.; Kaminski, M.; Kiendler-Scharr, A.

    2015-12-01

    Atmospheric aerosol can alter the Earth's radiative budget and global climate but can also affect human health. A dominant contributor to the submicrometer particulate matter (PM) is organic aerosol (OA). OA can be either directly emitted through e.g. combustion processes (primary OA) or formed through the oxidation of organic gases (secondary organic aerosol, SOA). A detailed understanding of SOA formation is of importance as it constitutes a major contribution to the total OA. The partitioning between the gas and particle phase as well as the volatility of individual components of SOA is yet poorly understood adding uncertainties and thus complicating climate modelling. In this work, a new experimental methodology was used for compound-specific analysis of organic aerosol. The Aerosol Collection Module (ACM) is a newly developed instrument that deploys an aerodynamic lens to separate the gas and particle phase of an aerosol. The particle phase is directed to a cooled sampling surface. After collection particles are thermally desorbed and transferred to a detector for further analysis. In the present work, the ACM was coupled to a Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS) to detect and quantify organic compounds partitioning between the gas and particle phase. This experimental approach was used in a set of experiments at the atmosphere simulation chamber SAPHIR to investigate SOA formation. Ozone oxidation with subsequent photochemical aging of β-pinene, limonene and real plant emissions from Pinus sylvestris (Scots pine) were studied. Simultaneous measurement of the gas and particle phase using the ACM-PTR-ToF-MS allows to report partitioning coefficients of important BVOC oxidation products. Additionally, volatility trends and changes of the SOA with photochemical aging are investigated and compared for all systems studied.

  4. Soil nutrients, aboveground productivity and vegetative diversity after 10 years of experimental acidification and base cation depletion

    Treesearch

    Mary Beth Adams; James A. Burger

    2010-01-01

    Soil acidification and base cation depletion are concerns for those wishing to manage central Appalachian hardwood forests sustainably. In this research, 2 experiments were established in 1996 and 1997 in two forest types common in the central Appalachian hardwood forests, to examine how these important forests respond to depletion of nutrients such as calcium and...

  5. IADS, a decomposition product of DIDS activates a cation conductance in Xenopus oocytes and human erythrocytes: new compound for the diagnosis of cystic fibrosis.

    PubMed

    Stumpf, Astrid; Almaca, Joana; Kunzelmann, Karl; Wenners-Epping, Kerstin; Huber, Stephan M; Haberle, Johannes; Falk, Sabine; Duebbers, Angelika; Walte, Mike; Oberleithner, Hans; Schillers, Hermann

    2006-01-01

    DIDS (4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid) is a commonly used blocker of plasma membrane anion channels and transporters. We observed that DIDS undergoes decomposition while stored in DMSO (dimethyl sulfoxide) forming a biologically active compound. One decomposition product, called IADS, was identified and synthesized. Voltage-clamp and patch clamp experiments on Xenopus laevis oocytes and human erythrocytes revealed that IADS is able to activate a plasma membrane cation conductance in both cell types. Furthermore, we found that IADS induces hemolysis in red blood cells of healthy donors but fails to hemolyze erythrocytes of donors with cystic fibrosis. Thus, IADS stimulated activation of a cation conductance could form the basis for a novel diagnostic test of cystic fibrosis. Copyright (c) 2006 S. Karger AG, Basel.

  6. Intake, milk production, ruminal, and feed efficiency responses to dietary cation-anion difference by lactating dairy cows.

    PubMed

    Iwaniuk, M E; Erdman, R A

    2015-12-01

    Previous meta-analyses of the effects of dietary cation anion difference (DCAD; mEq/kg; Na + K - Cl - S) in lactating dairy cow diets used studies conducted after the development of the DCAD concept. Dietary buffers, such as NaHCO3 and K2CO3, increase DCAD and have been used in lactating dairy cow diets for several decades. However, most published studies on buffer feeding were conducted before the development of the DCAD concept. Our objective was to determine the intake, milk production, ruminal, and feed efficiency responses to DCAD using previous studies with dietary buffer addition and more recent studies that focused on DCAD as dietary treatments. The database consisted of 43 articles that were published between 1965 and 2011. The studies included 196 dietary treatments and 89 treatment comparisons with a range in DCAD from -68 to 811mEq/kg of diet DM, with the vast majority between 0 and 500mEq/kg of diet DM. For studies that lacked analyses of one or more of the dietary strong ions (Na, K, Cl, or S), ion percentages were estimated from ingredient composition using the 2001 dairy National Research Council software. Two basic models were used to evaluate DCAD responses using the NLMIXED procedure in SAS 9.2 (SAS Institute Inc., Cary, NC): (1) a simple linear model, Y=A + B × (DCAD), where A=intercept and B=the increment (slope) in performance per unit DCAD (mEq/kg of diet DM); and (2) a nonlinear model, Y=A + M[1 - e((K × DCAD))], where M=maximal increment in performance from DCAD and K=the rate constant. In both models, study was designated as the random effect. The DCAD effects best described by the linear model included milk fat percent, fat yield, ruminal pH, NDF digestibility, and feed efficiency [3.5% fat-corrected milk (FCM; kg)/dry matter intake (DMI; kg)] where a 100mEq/kg increase in DCAD resulted in respective increases of 0.10%, 36g/d, 0.032 pH units, 1.5% NDF digestibility, and 0.013 FCM/DMI units. The DMI, milk yield, and 3.5% FCM were best

  7. Ecosystem carbon partitioning: aboveground net primary productivity correlates with the root carbon input in different land use types of Southern Alps

    NASA Astrophysics Data System (ADS)

    Rodeghiero, Mirco; Martinez, Cristina; Gianelle, Damiano; Camin, Federica; Zanotelli, Damiano; Magnani, Federico

    2013-04-01

    Terrestrial plant carbon partitioning to above- and below-ground compartments can be better understood by integrating studies on biomass allocation and estimates of root carbon input based on the use of stable isotopes. These experiments are essential to model ecosystem's metabolism and predict the effects of global change on carbon cycling. Using in-growth soil cores in conjunction with the 13C natural abundance method we quantified net plant-derived root carbon input into the soil, which has been pointed out as the main unaccounted NPP (net primary productivity) component. Four land use types located in the Trentino Region (northern Italy) and representing a range of aboveground net primary productivity (ANPP) values (155-868 gC m-2 y-1) were investigated: conifer forest, apple orchard, vineyard and grassland. Cores, filled with soil of a known C4 isotopic signature were inserted at 18 sampling points for each site and left in place for twelve months. After extraction, cores were analysed for %C and d13C, which were used to calculate the proportion of new plant-derived root C input by applying a mass balance equation. The GPP (gross primary productivity) of each ecosystem was determined by the eddy covariance technique whereas ANPP was quantified with a repeated inventory approach. We found a strong and significant relationship (R2 = 0.93; p=0.03) between ANPP and the fraction of GPP transferred to the soil as root C input across the investigated sites. This percentage varied between 10 and 25% of GPP with the grassland having the lowest value and the apple orchard the highest. Mechanistic ecosystem carbon balance models could benefit from this general relationship since ANPP is routinely and easily measured at many sites. This result also suggests that by quantifying site-specific ANPP, root carbon input can be reliably estimated, as opposed to using arbitrary root/shoot ratios which may under- or over-estimate C partitioning.

  8. Partitioning of [methyl-3H]methionine to methylated products and protein is altered during high methyl demand conditions in young Yucatan miniature pigs.

    PubMed

    McBreairty, Laura E; McGowan, Ross A; Brunton, Janet A; Bertolo, Robert F

    2013-06-01

    Methionine is the main source of methyl groups that are partitioned to synthesize various methylated products including creatine, phosphatidylcholine (PC), and methylated DNA. Whether increased methylation of 1 product can divert methionine from protein synthesis or other methylation products was the aim of this experiment. We used an excess of guanidinoacetate (GAA) to synthesize creatine to create a higher demand for available methyl groups in normal-weight (NW) (n = 10) and intrauterine growth-restricted (IUGR) (n = 10) piglets. Anesthetized piglets (15-18 d old) were intraportally infused with either GAA or saline for 2 h. A bolus of l-[methyl-(3)H]methionine was intraportally infused at 1 h, and hepatic metabolites were analyzed for methyl-(3)H incorporation 1 h later. Overall, 50-75% of label was recovered in creatine and PC with negligible amounts in DNA. In both NW and IUGR piglets, excess GAA led to an ≈ 80-120% increase in methyl incorporation into creatine (P < 0.05) with a concomitant decrease by ≈ 75-85% in methyl incorporation into PC (P < 0.05) as well as a 40% decrease in methyl incorporation into protein (P < 0.05), suggesting methyl groups were limited for PC synthesis and that methionine was diverted from protein synthesis. Compared with NW piglets, IUGR piglets had lower methyl incorporation into PC (P < 0.05), but not DNA or protein, suggesting IUGR affects methyl metabolism and could potentially impact lipid metabolism. The partitioning of methionine is sensitive to methyl supply in neonates, which has implications in infant diet composition and growth.

  9. [A Simultaneous Determination Method with Acetonitrile-n-Hexane Partitioning and Solid-Phase Extraction for Pesticide Residues in Livestock and Marine Products by GC-MS].

    PubMed

    Yoshizaki, Mayuko; Kobayashi, Yukari; Shimizu, Masanori; Maruyama, Kouichi

    2015-01-01

    A simultaneous determination method was examined for 312 pesticides (including isomers) in muscle of livestock and marine products by GC-MS. The pesticide residues extracted from samples with acetone and n-hexane were purified by acetonitrile-n-hexane partitioning, and C18 and SAX/PSA solid-phase extraction without using GPC. Matrix components such as cholesterol were effectively removed. In recovery tests performed by this method using pork, beef, chicken and shrimp, 237-257 pesticides showed recoveries within the range of 70-120% in each sample. Validity was confirmed for 214 of the target pesticides by means of a validation test using pork. In comparison with the Japanese official method using GPC, the treatment time of samples and the quantity of solvent were reduced substantially.

  10. Biomass production, forage quality, and cation uptake of Quail bush, four-wing saltbush, and seaside barley irrigated with moderately saline-sodic water

    SciTech Connect

    Bauder, J.W.; Browning, L.S.; Phelps, S.D.; Kirkpatrick, A.D.

    2008-07-01

    The study reported here investigated capacity of Atriplex lentiformis (Torr.) S. Wats. (Quail bush), Atriplex X aptera A. Nels. (pro sp.) (Wytana four-wing saltbush), and Hordeum marinum Huds. (seaside barley) to produce biomass and crude protein and take up cations when irrigated with moderately saline-sodic water, in the presence of a shallow water table. Water tables were established at 0.38, 0.76, and 1.14m below the surface in sand-filled columns. The columns were then planted to the study species. Study plants were irrigated for 224 days; irrigation water was supplied every 7 days equal to water lost to evapotranspiration (ET) plus 100mL (the volume of water removed in the most previous soil solution sampling). Water representing one of two irrigation sources was used: Powder River (PR) or coalbed natural gas (CBNG) wastewater. Biomass production did not differ significantly between water quality treatments but did differ significantly among species and water table depth within species. Averaged across water quality treatments, Hordeum marinum produced 79% more biomass than A. lentiformis and 122% more biomass than Atriplex X aptera, but contained only 11% crude protein compared to 16% crude protein in A. lentiformis and 14% crude protein in Atriplex X aptera. Atriplex spp. grown in columns with the water table at 0.38m depth produced more biomass, took up less calcium on a percentage basis, and took up more sodium on a percentage basis than when grown with the water table at a deeper depth. Uptake of cations by Atriplex lentiformis was approximately twice the uptake of cations by Atriplex X aptera and three times that of H. marinum. After 224 days of irrigation, crop growth, and cation uptake, followed by biomass harvest, EC and SAR of shallow groundwater in columns planted to A. lentiformis were less than EC and SAR of shallow ground water in columns planted to either of the other species.

  11. Demonstration of in situ product recovery of butyric acid via CO2 -facilitated pH swings and medium development in two-phase partitioning bioreactors.

    PubMed

    Peterson, Eric C; Daugulis, Andrew J

    2014-03-01

    Production of organic acids in solid-liquid two-phase partitioning bioreactors (TPPBs) is challenging, and highly pH-dependent, as cell growth occurs near neutral pH, while acid sorption occurs only at low pH conditions. CO2 sparging was used to achieve acidic pH swings, facilitating undissociated organic acid uptake without generating osmotic stress inherent in traditional acid/base pH control. A modified cultivation medium was formulated to permit greater pH reduction by CO2 sparging (pH 4.8) compared to typical media (pH 5.3), while still possessing adequate nutrients for extensive cell growth. In situ product recovery (ISPR) of butyric acid (pKa = 4.8) produced by Clostridium tyrobutyricum was achieved through intermittent CO2 sparging while recycling reactor contents through a column packed with absorptive polymer Hytrel® 3078. This polymer was selected on the basis of its composition as a polyether copolymer, and the use of solubility parameters for predicting solute polymer affinity, and was found to have a partition coefficient for butyric acid of 3. Total polymeric extraction of 3.2 g butyric acid with no CO2 mediated pH swings was increased to 4.5 g via CO2 -facilitated pH shifting, despite the buffering capacity of butyric acid, which resists pH shifting. This work shows that CO2 -mediated pH swings have an observable positive effect on organic acid extraction, with improvements well over 150% under optimal conditions in early stage fermentation compared to CO2 -free controls, and this technique can be applied other organic acid fermentations to achieve or improve ISPR.

  12. Long-term CO2 fertilization increases vegetation productivity and has little effect on hydrological partitioning in tropical rainforests

    NASA Astrophysics Data System (ADS)

    Yang, Yuting; Donohue, Randall J.; McVicar, Tim R.; Roderick, Michael L.; Beck, Hylke E.

    2016-08-01

    Understanding how tropical rainforests respond to elevated atmospheric CO2 concentration (eCO2) is essential for predicting Earth's carbon, water, and energy budgets under future climate change. Here we use long-term (1982-2010) precipitation (P) and runoff (Q) measurements to infer runoff coefficient (Q/P) and evapotranspiration (E) trends across 18 unimpaired tropical rainforest catchments. We complement that analysis by using satellite observations coupled with ecosystem process modeling (using both "top-down" and "bottom-up" perspectives) to examine trends in carbon uptake and relate that to the observed changes in Q/P and E. Our results show there have been only minor changes in the satellite-observed canopy leaf area over 1982-2010, suggesting that eCO2 has not increased vegetation leaf area in tropical rainforests and therefore any plant response to eCO2 occurs at the leaf level. Meanwhile, observed Q/P and E also remained relatively constant in the 18 catchments, implying an unchanged hydrological partitioning and thus approximately conserved transpiration under eCO2. For the same period, using a top-down model based on gas exchange theory, we predict increases in plant assimilation (A) and light use efficiency (ɛ) at the leaf level under eCO2, the magnitude of which is essentially that of eCO2 (i.e., 12% over 1982-2010). Simulations from 10 state-of-the-art bottom-up ecosystem models over the same catchments also show that the direct effect of eCO2 is to mostly increase A and ɛ with little impact on E. Our findings add to the current limited pool of knowledge regarding the long-term eCO2 impacts in tropical rainforests.

  13. Bacterial production and reconstitution in proteoliposomes of Solanum lycopersicum CAT2: a transporter of basic amino acids and organic cations.

    PubMed

    Regina, Teresa Maria Rosaria; Galluccio, Michele; Scalise, Mariafrancesca; Pochini, Lorena; Indiveri, Cesare

    2017-08-01

    The vacuolar SlCAT2 was cloned, over-produced in E. coli and reconstituted in proteoliposomes. Arg, Ornithine and Lys were identified as substrates. Unexpectedly, also the organic cations Tetraethylammonium and Acetylcholine were transported indicating involvement of SlCAT2 in signaling. In land plants several transporters are involved in ion and metabolite flux across membranes of cells or intracellular organelles. The vacuolar amino acid transporter CAT2 from Solanum lycopersicum was investigated in this work. SlCAT2 was cloned from tomato flower cDNA, over-produced in Escherichia coli and purified by Nichel-chelating chromatography. For functional studies, the transporter was reconstituted in proteoliposomes. Competence of SlCAT2 for Arg transport was demonstrated measuring uptake of [(3)H]Arg in proteoliposomes which was trans-stimulated by internal Arg or ornithine. Uptake of [(3)H]Ornithine and [(3)H]Lys was also detected at lower efficiency with respect to [(3)H]Arg. Transport was activated by the presence of intraliposomal ATP suggesting regulation by the nucleotide. The prototype for organic cations tetraethylammonium (TEA) was also transported by SlCAT2. However, scarce reciprocal inhibition between TEA and Arg was found, while the biguanide metformin was able to strongly inhibit uptake of both substrates. These findings suggest that amino acids and organic cations may interact with the transporter through different functional groups some of which are common for the two types of substrates. Interestingly, reconstituted SlCAT2 showed competence for acetylcholine transport, which was also inhibited by metformin. Kinetics of Arg and Ach transport were performed from which Km values of 0.29 and 0.79 mM were derived, respectively.

  14. Internal and translational energy partitioning of the NO product in the S2 photodissociation of methyl nitrite

    NASA Astrophysics Data System (ADS)

    Sumida, Masataka; Masumoto, Shu; Kato, Mitsue; Yamasaki, Katsuyoshi; Kohguchi, Hiroshi

    2017-04-01

    State-resolved scattering distributions of the NO product in the photodissociation of CH3ONO were measured at 213 nm with resonantly-enhanced multiphoton ionization spectroscopy and ion-imaging. The spectra of the NO product displayed the vibrational population up to the v = 3 state having the rotational state-distribution with a Gaussian-like function. The scattering data of the NO (v = 1) product indicate that the rotational excitation of the NO fragment and the translational energy release are fairly well compensated. This result is explained as being an outcome of the strong repulsion in the CH3Osbnd NO bond in the S2 state.

  15. Production of poly-β-hydroxybutyrate (PHB) by Methylobacterium organophilum isolated from a methanotrophic consortium in a two-phase partition bioreactor.

    PubMed

    Zúñiga, C; Morales, M; Le Borgne, S; Revah, S

    2011-06-15

    The biodegradation of methane, a greenhouse gas, and the accumulation of poly-β-hydroxybutyrate (PHB) were studied using a methanotrophic consortium and an isolated strain thereof. The specific rates for methane consumption were 100 and [Formula: see text] for the isolate and the consortium, respectively. Also the effect of including 10% (vv(-1)) of silicone oil in a two-phase partitioning bioreactor (TPPB) was assayed for the elimination of 1% methane in air stream. TPPB allowed a 33-45% increase of methane elimination under growing conditions. Nitrogen limitation was assayed in bioreactors to promote PHB production. Under this condition, the specific methane degradation rate remained unchanged for the consortium and decreased to [Formula: see text] for the isolated strain. The accumulated PHB in the reactor was 34% and 38% (ww(-1)) for the consortium and the isolate, respectively. The highest productivity was obtained in the TPPB and was 1.61 mg(PHB)g(x)(-1) h(-1). The CZ-2 isolate was identified as Methylobacterium organophilum, this is the first study that reports this species as being able to grow on methane and accumulate up to 57% (ww(-1)) of PHB under nitrogen limitation in microcosm experiments.

  16. Integrating biocompatible chemistry and manipulating cofactor partitioning in metabolically engineered Lactococcus lactis for fermentative production of (3S)-acetoin.

    PubMed

    Liu, Jianming; Solem, Christian; Jensen, Peter Ruhdal

    2016-12-01

    Biocompatible chemistry (BC), that is, non-enzymatic chemical reactions compatible with living organisms, is increasingly used in conjunction with metabolically engineered microorganisms for producing compounds that do not usually occur naturally. Here we report production of one such compound, (3S)-acetoin, a valuable precursor for chiral synthesis, using a metabolically engineered Lactococcus lactis strain growing under respiratory conditions with ferric iron serving as a BC component. The strain used has all competing product pathways inactivated, and an appropriate cofactor balance is achieved by fine-tuning the respiratory capacity indirectly via the hemin concentration. We achieve high-level (3S)-acetoin production with a final titer of 66 mM (5.8 g/L) and a high yield (71% of the theoretical maximum). To the best of our knowledge, this is the first report describing production of (3S)-acetoin from sugar by microbial fermentation, and the results obtained confirm the potential that lies with BC for producing useful chemicals. Biotechnol. Bioeng. 2016;113: 2744-2748. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  17. ADSORPTION METHOD FOR SEPARATING METAL CATIONS

    DOEpatents

    Khym, J.X.

    1959-03-10

    The chromatographic separation of fission product cations is discussed. By use of this method a mixture of metal cations containing Zr, Cb, Ce, Y, Ba, and Sr may be separated from one another. Mentioned as preferred exchange adsorbents are resins containing free sulfonic acid groups. Various eluants, such as tartaric acid, HCl, and citric acid, used at various acidities, are employed to effect the selective elution and separation of the various fission product cations.

  18. Impacts of insect-related forest mortality on hydrologic partitioning and forest productivity in the Southern Rocky Mountains, USA

    NASA Astrophysics Data System (ADS)

    Molotch, N. P.

    2014-12-01

    Recent large-scale changes in forest cover over Western North America associated with insect-related forest mortality may have widespread impacts on water availability. These changes have potentially varied impacts on water availability as forest mortality influences rates of snow accumulation, snowmelt, and evapotranspiration. These changes may significantly alter runoff production and gross primary productivity in mountain forests. Analysis of remotely sensed vegetation greenness data indicate strong forest and understory growth dependencies associated with snow accumulation and snowmelt with peak snow water equivalent explaining 40-50% of inter-annual greenness variability in the Rocky Mountains. Examples of these dependencies will be presented based on the 2012 drought in the Southwestern US whereby near record low snow accumulation and record high potential evapotranspiration have resulted in record low forest greening as evident in the 30+ year satellite record. Forest response to aridity in 2012 was exacerbated by forest disturbance with greenness anomalies 90% greater in magnitude in Bark Beetle and Spruce Budworm affected areas versus undisturbed areas and 182% greater in magnitude in areas impacted by fire. Growing season length was inversely proportional to peak greenness with record high Normalized Difference Vegetation Index (NDVI) values in April (14% above average) corresponding with record low NDVI values in July (7% below average). Gross primary productivity (GPP) estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS) and from the Niwot Ridge, Colorado Ameriflux tower indicate record high April GPP (30% and 90% above average for MODIS and the tower, respectively) correspodning with record low July GPP (19% and 30% below average, respectively). Differences in these energy, water, ecosystem relationships among difference distrurbance regimes indicate that the sensitivity of ecosystems to changes in climate is heavily dependent on

  19. Plasmid Partition Mechanisms.

    PubMed

    Baxter, Jamie C; Funnell, Barbara E

    2014-12-01

    The stable maintenance of low-copy-number plasmids in bacteria is actively driven by partition mechanisms that are responsible for the positioning of plasmids inside the cell. Partition systems are ubiquitous in the microbial world and are encoded by many bacterial chromosomes as well as plasmids. These systems, although different in sequence and mechanism, typically consist of two proteins and a DNA partition site, or prokaryotic centromere, on the plasmid or chromosome. One protein binds site-specifically to the centromere to form a partition complex, and the other protein uses the energy of nucleotide binding and hydrolysis to transport the plasmid, via interactions with this partition complex inside the cell. For plasmids, this minimal cassette is sufficient to direct proper segregation in bacterial cells. There has been significant progress in the last several years in our understanding of partition mechanisms. Two general areas that have developed are (i) the structural biology of partition proteins and their interactions with DNA and (ii) the action and dynamics of the partition ATPases that drive the process. In addition, systems that use tubulin-like GTPases to partition plasmids have recently been identified. In this chapter, we concentrate on these recent developments and the molecular details of plasmid partition mechanisms.

  20. Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

    NASA Astrophysics Data System (ADS)

    Lopez-Hilfiker, F. D.; Mohr, C.; Ehn, M.; Rubach, F.; Kleist, E.; Wildt, J.; Mentel, Th. F.; Carrasquillo, A. J.; Daumit, K. E.; Hunter, J. F.; Kroll, J. H.; Worsnop, D. R.; Thornton, J. A.

    2015-07-01

    We measured a large suite of gas- and particle-phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gas and particle phases, the latter being detected by temperature-programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO-HR-ToF-CIMS are highly correlated with, and explain at least 25-50 % of, the organic aerosol mass measured by an Aerodyne aerosol mass spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from high molecular weight organics and/or oligomers (i.e., multi-phase accretion reaction products). Approximately 50 % of the HR-ToF-CIMS particle-phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption-temperature-based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas-particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the conversion of

  1. Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

    NASA Astrophysics Data System (ADS)

    Lopez-Hilfiker, F. D.; Mohr, C.; Ehn, M.; Rubach, F.; Kleist, E.; Wildt, J.; Mentel, Th. F.; Carrasquillo, A.; Daumit, K.; Hunter, J.; Kroll, J. H.; Worsnop, D.; Thornton, J. A.

    2015-02-01

    We measured a large suite of gas and particle phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gas and particle phases, the latter being detected upon temperature programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO HR-ToF-CIMS are highly correlated with, and explain at least 25-50% of, the organic aerosol mass measured by an Aerodyne Aerosol Mass Spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from large molecular weight organics and/or oligomers (i.e. multi-phase accretion reaction products). Approximately 50% of the HR-ToF-CIMS particle phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption temperature based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas-particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the conversion of

  2. Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

    DOE PAGES

    Lopez-Hilfiker, F. D.; Mohr, C.; Ehn, M.; ...

    2015-02-18

    We measured a large suite of gas and particle phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gasmore » and particle phases, the latter being detected upon temperature programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO HR-ToF-CIMS are highly correlated with, and explain at least 25–50% of, the organic aerosol mass measured by an Aerodyne Aerosol Mass Spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from large molecular weight organics and/or oligomers (i.e. multi-phase accretion reaction products). Approximately 50% of the HR-ToF-CIMS particle phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption temperature based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas–particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the

  3. Phase partitioning and volatility of secondary organic aerosol components formed from α-pinene ozonolysis and OH oxidation: the importance of accretion products and other low volatility compounds

    DOE PAGES

    Lopez-Hilfiker, F. D.; Mohr, C.; Ehn, M.; ...

    2015-07-16

    We measured a large suite of gas- and particle-phase multi-functional organic compounds with a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington. The instrument was deployed on environmental simulation chambers to study monoterpene oxidation as a secondary organic aerosol (SOA) source. We focus here on results from experiments utilizing an ionization method most selective towards acids (acetate negative ion proton transfer), but our conclusions are based on more general physical and chemical properties of the SOA. Hundreds of compounds were observed in both gas andmore » particle phases, the latter being detected by temperature-programmed thermal desorption of collected particles. Particulate organic compounds detected by the FIGAERO–HR-ToF-CIMS are highly correlated with, and explain at least 25–50 % of, the organic aerosol mass measured by an Aerodyne aerosol mass spectrometer (AMS). Reproducible multi-modal structures in the thermograms for individual compounds of a given elemental composition reveal a significant SOA mass contribution from high molecular weight organics and/or oligomers (i.e., multi-phase accretion reaction products). Approximately 50 % of the HR-ToF-CIMS particle-phase mass is associated with compounds having effective vapor pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. The relative importance of these accretion-type and other extremely low volatility products appears to vary with photochemical conditions. We present a desorption-temperature-based framework for apportionment of thermogram signals into volatility bins. The volatility-based apportionment greatly improves agreement between measured and modeled gas-particle partitioning for select major and minor components of the SOA, consistent with thermal decomposition during desorption causing the

  4. Effect of corn preparation methods on dry-grind ethanol production by granular starch hydrolysis and partitioning of spent beer solids.

    PubMed

    Lamsal, B P; Wang, H; Johnson, L A

    2011-06-01

    Two corn preparation methods, rollermill flaking and hammermill grinding, were compared for efficient processing of corn into ethanol by granular starch hydrolysis and simultaneous fermentation by yeast Saccharomyces cerevisiae. Corn was either ground in a hammermill with different size screens or crushed in a smooth-surfaced rollermill at different roller gap settings. The partitioning of beer solids and size distribution of solids in the thin stillage were compared. The mean particle diameter d(50) for preparations varied with set-ups and ranged between 210 and 340 μm for ground corn, and 1180-1267 μm for flaked corn. The ethanol concentrations in beer were similar (18-19% v/v) for ground and flaked preparations, however, ethanol productivity increased with reduced particle size. Roller versus hammermilling of corn reduced solids in thin stillage by 28%, and doubled the volume percent of fines (d(50) ∼ 7 μm)in thin stillage and decreased coarse (d(50) ∼ 122 μm) by half compared to hammermilling.

  5. Augmentation of Cationic Antimicrobial Peptide Production with Histone Deacetylase Inhibitors as a Novel Epigenetic Therapy for Bacterial Infections

    PubMed Central

    Yedery, Roshan D.; Jerse, Ann E.

    2015-01-01

    The emergence of antibiotic resistance seriously threatens our ability to treat many common and medically important bacterial infections. Novel therapeutics are needed that can be used alone or in conjunction with antibiotics. Cationic antimicrobial peptides (CAMPs) are important effectors of the host innate defense that exhibit broad-spectrum activity against a wide range of microorganisms. CAMPs are carried within phagocytic granules and are constitutively or inducibly expressed by multiple cell types, including epithelial cells. The role of histone modification enzymes, specifically the histone deacetylases (HDAC), in down-regulating the transcription of CAMP-encoding genes is increasingly appreciated as is the capacity of HDAC inhibitors (HDACi) to block the action of HDACs to increase CAMP expression. The use of synthetic and natural HDACi molecules to increase CAMPs on mucosal surfaces, therefore, has potential therapeutic applications. Here, we review host and pathogen regulation of CAMP expression through the induction of HDACs and assess the therapeutic potential of natural and synthetic HDACi based on evidence from tissue culture systems, animal models, and clinical trials. PMID:27025614

  6. A dynamic growth model for prediction of nutrient partitioning and manure production in growing-finishing pigs: Model development and evaluation.

    PubMed

    Strathe, A B; Danfær, A; Jørgensen, H; Kebreab, E

    2015-03-01

    Nutrient loading and air emissions from swine operations raise environmental concerns. The objective of the study was to describe and evaluate a mathematical model (Davis Swine Model) of nutrient partitioning and predict manure excretion and composition on a daily basis. State variables of the model were AA, fatty acids, and a central pool of metabolites that supplied substrate for lipid synthesis and oxidation. The model traced the fate of ingested nutrients and water through digestion and intermediary metabolism into body protein, fat, water, and ash, where body protein and fat represented the body constituent pools. It was assumed that fluxes of metabolites follow saturation kinetics, depending on metabolite concentrations. The main inputs to the model were diet nutrient composition, feed intake, water-to-feed ratio, and initial BW. First, the model was challenged with nutrient partitioning data and then with excretion data. The data had 48 different feeding regimes with contrasting energy and lysine intakes at 2 different stages of growth. The overall observed and predicted mean were 109 and 112 g/d for protein deposition and 132 and 136 g/d for lipid deposition respectively, suggesting minor mean bias. Root mean square prediction error (RMSPE) was used in evaluation of the model for its predictive power. The overall RMSPE was 2.2 and 4.1 g/d for protein and lipid deposition, respectively. The excretion database used for evaluation of the model was constructed from 150 digestibility trials using growing-finishing pig diets that had a wide range of nutrient chemical composition. Nutrient and water excretion were quantified using the principle of mass conservation. The average daily observed and predicted manure production was 3.79 and 3.99 kg/d, respectively, with a RMSPE of 0.49 kg/d. There was a good agreement between observed and predicted mean fecal N output (9.9 and 9.8 g/d, respectively). Similarly, the overall observed and predicted mean urine N output

  7. Diaryldichalcogenide radical cations.

    PubMed

    Mallow, Ole; Khanfar, Monther A; Malischewski, Moritz; Finke, Pamela; Hesse, Malte; Lork, Enno; Augenstein, Timo; Breher, Frank; Harmer, Jeffrey R; Vasilieva, Nadezhda V; Zibarev, Andrey; Bogomyakov, Artem S; Seppelt, Konrad; Beckmann, Jens

    2015-01-01

    One-electron oxidation of two series of diaryldichalcogenides (C6F5E)2 (13a-c) and (2,6-Mes2C6H3E)2 (16a-c) was studied (E = S, Se, Te). The reaction of 13a and 13b with AsF5 and SbF5 gave rise to the formation of thermally unstable radical cations [(C6F5S)2]˙(+) (14a) and [(C6F5Se)2]˙(+) (14b) that were isolated as [Sb2F11](-) and [As2F11](-) salts, respectively. The reaction of 13c with AsF5 afforded only the product of a Te-C bond cleavage, namely the previously known dication [Te4](2+) that was isolated as [AsF6](-) salt. The reaction of (2,6-Mes2C6H3E)2 (16a-c) with [NO][SbF6] provided the corresponding radical cations [(2,6-Mes2C6H3E)2]˙(+) (17a-c; E = S, Se, Te) in the form of thermally stable [SbF6](-) salts in nearly quantitative yields. The electronic and structural properties of these radical cations were probed by X-ray diffraction analysis, EPR spectroscopy, and density functional theory calculations and other methods.

  8. Chromatographic cation exchange separation of decigram quantities of californium and other transplutonium elements

    SciTech Connect

    Benker, D.E.; Chattin, F.R.; Collins, E.D.; Knauer, J.B.; Orr, P.B.; Ross, R.G.; Wiggins, J.T.

    1981-01-01

    Decigram quantities of highly radioactive transplutonium elements are routinely partitioned at TRU by chromatographic elution from cation resin using AHIB eluents. Batch runs containing up to 200 mg of /sup 252/Cf can be made in about 5 h (2 h to load the feed and 3 h for the elution), with two high-pressure ion exchange columns, a small one for the initial loading of the feed and a large one for the elution. The separations achieved in the column are preserved by routing the column effluent through an alpha detector and using the response from the detector to select appropriate product fractions. The high-pressure ion exchange process has been reliable and relatively easy to operate; therefore it will continue to be used for partitioning transplutonium elements at TRU. 3 figures, 1 table.

  9. Development of a rapid high-efficiency scalable process for acetylated Sus scrofa cationic trypsin production from Escherichia coli inclusion bodies.

    PubMed

    Zhao, Mingzhi; Wu, Feilin; Xu, Ping

    2015-12-01

    Trypsin is one of the most important enzymatic tools in proteomics and biopharmaceutical studies. Here, we describe the complete recombinant expression and purification from a trypsinogen expression vector construct. The Sus scrofa cationic trypsin gene with a propeptide sequence was optimized according to Escherichia coli codon-usage bias and chemically synthesized. The gene was inserted into pET-11c plasmid to yield an expression vector. Using high-density E. coli fed-batch fermentation, trypsinogen was expressed in inclusion bodies at 1.47 g/L. The inclusion body was refolded with a high yield of 36%. The purified trypsinogen was then activated to produce trypsin. To address stability problems, the trypsin thus produced was acetylated. The final product was generated upon gel filtration. The final yield of acetylated trypsin was 182 mg/L from a 5-L fermenter. Our acetylated trypsin product demonstrated higher BAEE activity (30,100 BAEE unit/mg) than a commercial product (9500 BAEE unit/mg, Promega). It also demonstrated resistance to autolysis. This is the first report of production of acetylated recombinant trypsin that is stable and suitable for scale-up. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Cation-exchange chromatography of monoclonal antibodies: characterisation of a novel stationary phase designed for production-scale purification.

    PubMed

    Urmann, Marina; Graalfs, Heiner; Joehnck, Matthias; Jacob, Lothar R; Frech, Christian

    2010-01-01

    A novel cation-exchange resin, Eshmuno™ S, was compared to Fractogel® SO3(-) (M) and Toyopearl GigaCap S-650M. The stationary phases have different base matrices, and carry specific types of polymeric surface modifications. Three monoclonal antibodies (mAbs) were used as model proteins to characterize these chromatographic resins. Results from gradient elutions, stirred batch adsorptions and confocal laser scanning microscopic investigations were used to elucidate binding behaviour of mAbs onto Eshmuno™ S and Fractogel® SO3(-) and the corresponding transport mechanisms on these two resins. The number of charges involved in mAb binding for Eshmuno™ S is lower than for Fractogel® SO3(-), indicating a slightly weaker electrostatic interaction. Kinetics from batch uptake experiments are compared to kinetic data obtained from confocal laser scanning microscopy images. Both experimental approaches show an accelerated protein adsorption for the novel stationary phase. The influence of pH, salt concentrations and residence times on dynamic binding capacities was determined. A higher dynamic binding capacity for Eshmuno™ S over a wider range of pH values and residence times was found compared to Fractogel® SO3(-) and Toyopearl GigaCap S-650M. The capture of antibodies from cell culture supernatant, as well as post-protein A eluates, were analyzed with respect to their host cell protein (hcp) removal capabilities. Comparable or even better hcp clearance was observed at much higher protein loading for Eshmuno™ S than Fractogel® SO3(-) or Toyopearl GigaCap S-650M.

  11. Native-Like and Denatured Cytochrome c Ions Yield Cation-to-Anion Proton Transfer Reaction Products with Similar Collision Cross-Sections

    NASA Astrophysics Data System (ADS)

    Laszlo, Kenneth J.; Buckner, John H.; Munger, Eleanor B.; Bush, Matthew F.

    2017-02-01

    The relationship between structures of protein ions, their charge states, and their original structures prior to ionization remains challenging to decouple. Here, we use cation-to-anion proton transfer reactions (CAPTR) to reduce the charge states of cytochrome c ions in the gas phase, and ion mobility to probe their structures. Ions were formed using a new temperature-controlled nanoelectrospray ionization source at 25 °C. Characterization of this source demonstrates that the temperature of the liquid sample is decoupled from that of the atmospheric pressure interface, which is heated during CAPTR experiments. Ionization from denaturing conditions yields 18+ to 8+ ions, which were each isolated and reacted with monoanions to generate all CAPTR products with charge states of at least 3+. The highest, intermediate, and lowest charge-state products exhibit collision cross-section distributions that are unimodal, multimodal, and unimodal, respectively. These distributions depend strongly on the charge state of the product, although those for the intermediate charge-state products also depend on that of the precursor. The distributions of the 3+ products are all similar, with averages that are less than half that of the 18+ precursor ions. Ionization of cytochrome c from native-like conditions yields 7+ and 6+ ions. The 3+ CAPTR products from these precursors have slightly more compact collision cross-section distributions that are indistinguishable from those for the 3+ CAPTR products from denaturing conditions. More broadly, these results indicate that the collision cross-sections of ions of this single domain protein depend strongly on charge state for charge states greater than 4.

  12. Native-Like and Denatured Cytochrome c Ions Yield Cation-to-Anion Proton Transfer Reaction Products with Similar Collision Cross-Sections

    NASA Astrophysics Data System (ADS)

    Laszlo, Kenneth J.; Buckner, John H.; Munger, Eleanor B.; Bush, Matthew F.

    2017-07-01

    The relationship between structures of protein ions, their charge states, and their original structures prior to ionization remains challenging to decouple. Here, we use cation-to-anion proton transfer reactions (CAPTR) to reduce the charge states of cytochrome c ions in the gas phase, and ion mobility to probe their structures. Ions were formed using a new temperature-controlled nanoelectrospray ionization source at 25 °C. Characterization of this source demonstrates that the temperature of the liquid sample is decoupled from that of the atmospheric pressure interface, which is heated during CAPTR experiments. Ionization from denaturing conditions yields 18+ to 8+ ions, which were each isolated and reacted with monoanions to generate all CAPTR products with charge states of at least 3+. The highest, intermediate, and lowest charge-state products exhibit collision cross-section distributions that are unimodal, multimodal, and unimodal, respectively. These distributions depend strongly on the charge state of the product, although those for the intermediate charge-state products also depend on that of the precursor. The distributions of the 3+ products are all similar, with averages that are less than half that of the 18+ precursor ions. Ionization of cytochrome c from native-like conditions yields 7+ and 6+ ions. The 3+ CAPTR products from these precursors have slightly more compact collision cross-section distributions that are indistinguishable from those for the 3+ CAPTR products from denaturing conditions. More broadly, these results indicate that the collision cross-sections of ions of this single domain protein depend strongly on charge state for charge states greater than 4.

  13. Partition Coefficients of Organic Compounds in New Imidazolium and Tetralkylammonium Based Ionic Liquids Using Inverse Gas Chromatography

    SciTech Connect

    Mutelet, Fabrice; Revelli, Anne-Laure; Jaubert, Jean-Noel; Sprunger, Laura; Acree, William; Baker, Gary A

    2010-01-01

    Partition coefficients of 51 organic compounds in two ionic liquids (IL), 1-ethyl-3-methylimidazolium dicyanamide and trimethylhexylammonium bis((trifluoromethyl)sulfonyl)amide, were measured using inverse gas chromatography from (322.5 to 352.5) K. These partition coefficients were converted into water-to-IL partition coefficients using the corresponding gas-to-water partition coefficients. Both sets of partition coefficients were analyzed using the Abraham solvation parameter model with cation-specific and anionspecific equation coefficients. The derived equations correlated the experimental gas-to-IL and water-to-IL partition coefficient data to within (0.12 and 0.14) log units, respectively.

  14. Kinetics and product branching fractions of reactions between a cation and a radical: Ar(+) + CH3 and O2(+) + CH3.

    PubMed

    Sawyer, Jordan C; Shuman, Nicholas S; Wiens, Justin P; Viggiano, Albert A

    2015-02-12

    A novel technique is described for the measurement of rate constants and product branching fractions of thermal reactions between cation and radical species. The technique is a variant of the variable electron and neutral density attachment mass spectrometry (VENDAMS) method, employing a flowing afterglow-Langmuir probe apparatus. A radical species is produced in situ via dissociative electron attachment to a neutral precursor; this allows for a quantitative derivation of the radical concentration and, as a result, a quantitative determination of rate constants. The technique is applied to the reactions of Ar(+) and O2(+) with CH3 at 300 K. The Ar(+) + CH3 reaction proceeds near the collisional rate constant of 1.1 × 10(-9) cm(3) s(-1) and has three product channels: → CH3(+) + Ar (k = 5 ± 2 × 10(-10) cm(3) s(-1)), → CH2(+) + H + Ar (k = 7 ± 2 × 10(-10) cm(3) s(-1)), → CH(+) + H2 + Ar (k = 5 ± 3 × 10(-11) cm(3) s(-1)). The O2(+) + CH3 reaction is also efficient, with direct charge transfer yielding CH3(+) as the primary product channel. Several results needed to support these measurements are reported, including the kinetics of Ar(+) and O2(+) with CH3I, electron attachment to CH3I, and mutual neutralization of CH3(+) and CH2(+) with I(-).

  15. Synergistic effects of high molecular weight polyethylene oxide (PEO) and cationic cellulosic polymers on conditioning properties of hair care products [corrected].

    PubMed

    Li, Wing; Jordan, Susan L P; Zhang, Xiaodong; Amos, Jennifer; Davis, Cal

    2004-01-01

    A hair cleansing composition containing both high molecular weight PEO and cationic hydroxyethyl cellulose (HEC) was found to provide superior conditioning performance. Hair treated with a formulation containing both cationic HEC and high molecular weight PEO showed 30% better wet combing reduction than the formulation containing cationic HEC only. In conjunction with PEO, cationic HEC-dependent deposition of silicone oil and octyl methoxycinnamate (OMC) onto hair was enhanced 27% and 25%, respectively. When examined with a polarized microscope, the appearance of the polymer-surfactant complex (coacervate) of the diluted formation differed in the presence of PEO. In particular, the particle size of the coacervate in the formulation containing both PEO and cationic HEC was smaller. This result indicates PEO reduces the size of the deposition precipitate by preventing the coacervate from agglomerating. Surface analysis also showed that the presence of PEO in formulations containing cationic HEC deposited insoluble actives more evenly on the hair surface.

  16. Chemical behavior of organic compounds in the interface of water/dual-cation organobentonite.

    PubMed

    Chen, Bao-liang; Zhu, Li-zhong

    2002-01-01

    The sorption behavior of polar or ionizable organic compounds, such as p-nitrophenol, phenol and aniline, in the water/organobentonite systems is investigated. Both adsorption and partition occur to the sorption of organic compounds to dual-cation organobentonites. The separate contributions of adsorption and partition to the total sorption of organic compounds to dual-cation organobentonites are analyzed mathematically in the first time. The factors to the contributions are also discussed. The results indicated that the contribution of adsorption and partition is related to the composition and ratio of dual-cation surfactants exchanging onto the bentonite. The sorption of organic compounds to dual-cation organobentonite is dominated by adsorption at low concentrations and by partition at high concentrations, making the organobentonites powerful sorbents for organic contaminants over wide range of concentrations.

  17. Partitioning ecosystems for sustainability.

    PubMed

    Murray, Martyn G

    2016-03-01

    Decline in the abundance of renewable natural resources (RNRs) coupled with increasing demands of an expanding human population will greatly intensify competition for Earth's natural resources during this century, yet curiously, analytical approaches to the management of productive ecosystems (ecological theory of wildlife harvesting, tragedy of the commons, green economics, and bioeconomics) give only peripheral attention to the driving influence of competition on resource exploitation. Here, I apply resource competition theory (RCT) to the exploitation of RNRs and derive four general policies in support of their sustainable and equitable use: (1) regulate resource extraction technology to avoid damage to the resource base; (2) increase efficiency of resource use and reduce waste at every step in the resource supply chain and distribution network; (3) partition ecosystems with the harvesting niche as the basic organizing principle for sustainable management of natural resources by multiple users; and (4) increase negative feedback between consumer and resource to bring about long-term sustainable use. A simple policy framework demonstrates how RCT integrates with other elements of sustainability science to better manage productive ecosystems. Several problem areas of RNR management are discussed in the light of RCT, including tragedy of the commons, overharvesting, resource collapse, bycatch, single species quotas, and simplification of ecosystems.

  18. Synthesis on evaporation partitioning using stable isotopes

    NASA Astrophysics Data System (ADS)

    Coenders-Gerrits, Miriam; Bogaard, Thom; Wenninger, Jochen; Jonson Sutanto, Samuel

    2015-04-01

    Partitioning of evaporation into productive (transpiration) and non-productive evaporation (interception, soil evaporation) is of highest importance for water management practices, irrigation scheme design, and climate modeling. Despite this urge, the magnitude of the ratio of transpiration over total evaporation is still under debate and poorly understood due to measuring difficulties. However, with the current development in isotope measuring devices, new opportunities arise to untangle the partitioning of evaporation. In this paper we synthesize the opportunities and limitations using stable water isotopes in evaporation partitioning. We will analyze a set of field as well as laboratory studies to demonstrate the different evaporation components for various climate and vegetation conditions using stable isotopes 18O/16O and 2H/1H. Experimental data on evaporation partitioning of crops, grass, shrubs and trees are presented and we will discuss the specific experimental set-ups and data collection methods. The paper will be a synthesis of these studies.

  19. Soil C:N stoichiometry controls carbon sink partitioning between above-ground tree productivity and soil organic matter in high fertility forests

    NASA Astrophysics Data System (ADS)

    Cotrufo, M.; Alberti, G.; Vicca, S.; Inglima, I.; Belelli-Marchesini, L.; Genesio, L.; Miglietta, F.; Marjanovic, H.; Martinez, C.; Matteucci, G.; Peressotti, A.; Petrella, L.; Rodeghiero, M.

    2013-12-01

    The release of organic compounds from roots is a key process influencing soil carbon (C) dynamics and nutrient availability in terrestrial ecosystems and is a process by which plants stimulate microbial activity and soil organic matter (SOM) mineralization thus releasing nitrogen (N) to sustain their gross and net primary production (GPP and NPP). Root inputs also contribute to soil organic matter (SOM) formation. In this study, we quantified the annual net root derived C input to soil (Net-Croot) across six high fertile forests using an in-growth core isotope technique. On the basis of Net-Croot, wood and coarse root biomass changes and eddy covariance data, we quantified net belowground C sequestration. This and GPP were inversely related to soil C:N, but not to climate or age. Because, at these high fertile sites, biomass growth did not change with soil C:N ratio, biomass growth-to-GPP ratio significantly increased with increasing soil C:N. This was true for both our six forest sites and for high fertile sites across a set of other 23 sites selected at global scale. We suggest that, at high fertile sites, the interaction between plant demand for nutrients, soil stoichiometry and microbial activity sustain higher ecosystem C-sink allocation to above ground tree biomass with increasing soil C:N ratio and that this clear and strong relationship can be used for modelling forest C sink partitioning between plant biomass and soil. When C:N is high, microbes have a low C use efficiency, respire more of the fresh C inputs by roots and prime SOM decomposition increasing N availability for tree uptake. Soil C sequestration would therefore decrease, whereas the extra N released during SOM decomposition can promote tree growth and ecosystem C sink allocation in aboveground biomass. Conversely, C is sequestered in soil when the low soil C:N promotes microbial C use efficiency and new SOM formation.

  20. Pressure dependence on partition coefficients for trace elements between olivine and the coexisting melts

    NASA Astrophysics Data System (ADS)

    Taura, Hiroshi; Yurimoto, Hisayoshi; Kurita, Kei; Sueno, Shigeho

    Partition coefficients between olivine and melt at upper mantle conditions, 3 to 14 GPa, have been determined for 27 trace elements (Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Rb, Sr, Y, Zr, Cs, Ba, La and Ce) using secondary-ion mass-spectrometry (SIMS) and electron-probe microanalysis (EPMA). The general pattern of olivine/melt partitioning on Onuma diagrams resembles those reported previously for natural systems. This agreement strongly supports the argument that partitioning is under structural control of olivine even at high pressure. The partition coefficients for mono- and tri-valent cations show significant pressure dependence, both becoming larger with pressure, and are strongly correlated with coupled substitution into cation sites in the olivine structure. The dominant type of trace element substitution for mono- and tri-valent cations into olivine changes gradually from (Si, Mg)<-->(Al, Cr) at low pressure to (Si, Mg)<-->(Al, Al) and (Mg, Mg)<-->(Na, Al) at high pressure. The change in substitution type results in an increase in partition coefficients of Al and Na with pressure. An inverse correlation between the partition coefficients for divalent cations and pressure has been observed, especially for Ni, Co and Fe. The order of decreasing rate of partition coefficient with pressure correlates to strength of crystal field effect of the cation. The pressure dependence of olivine/melt partitioning can be attributed to the compression of cation polyhedra induced by pressure and the compensation of electrostatic valence by cation substitution.

  1. Cross sections for the production of energetic cations by electron impact on N2 and CO2

    NASA Technical Reports Server (NTRS)

    Iga, I.; Srivastava, S. K.; Rao, M. V. V. S.; Katayama, D. H.

    1995-01-01

    Dissociative ionization cross sections for the production of singly charged energetic ions by electron impact on N2 and CO2 have been measured. The ions were divided into two groups: one with energies less than 1 eV and the other with energies greater than 1 eV. The ions detected were N+ from N2 and C+, O+, and CO+ from CO2. The electron impact energy range, and cross section data on ions is given.

  2. Cross sections for the production of energetic cations by electron impact on N2 and CO2

    NASA Technical Reports Server (NTRS)

    Iga, I.; Srivastava, S. K.; Rao, M. V. V. S.; Katayama, D. H.

    1995-01-01

    Dissociative ionization cross sections for the production of singly charged energetic ions by electron impact on N2 and CO2 have been measured. The ions were divided into two groups: one with energies less than 1 eV and the other with energies greater than 1 eV. The ions detected were N+ from N2 and C+, O+, and CO+ from CO2. The electron impact energy range, and cross section data on ions is given.

  3. Use of Cation Exchange Resins for Production of U{sub 3}O{sub 8} Suitable for the Al-U{sub 3}O{sub 8} Powder Metallurgy Process

    SciTech Connect

    Mosley, W.C.

    2001-09-17

    This report describes the production of U{sub 3}O{sub 8} powders from three types of cation exchange resins: Dowex 50W, a strong acid, sulfonate resin; AG MP-50, a macroporous form of sulfonate resin; and Bio-Rex 70, a weak acid, carboxylic resin.

  4. An MCM modeling study of nitryl chloride (ClNO2) impacts on oxidation, ozone production and nitrogen oxide partitioning in polluted continental outflow

    NASA Astrophysics Data System (ADS)

    Riedel, T. P.; Wolfe, G. M.; Danas, K. T.; Gilman, J. B.; Kuster, W. C.; Bon, D. M.; Vlasenko, A.; Li, S.-M.; Williams, E. J.; Lerner, B. M.; Veres, P. R.; Roberts, J. M.; Holloway, J. S.; Lefer, B.; Brown, S. S.; Thornton, J. A.

    2014-04-01

    Nitryl chloride (ClNO2) is produced at night by reactions of dinitrogen pentoxide (N2O5) on chloride containing surfaces. ClNO2 is photolyzed during the morning hours after sunrise to liberate highly reactive chlorine atoms (Cl·). This chemistry takes place primarily in polluted environments where the concentrations of N2O5 precursors (nitrogen oxide radicals and ozone) are high, though it likely occurs in remote regions at lower intensities. Recent field measurements have illustrated the potential importance of ClNO2 as a daytime Cl· source and a nighttime NOx reservoir. However, the fate of the Cl· and the overall impact of ClNO2 on regional photochemistry remain poorly constrained by measurements and models. To this end, we have incorporated ClNO2 production, photolysis, and subsequent Cl· reactions into an existing master chemical mechanism (MCM version 3.2) box model framework using observational constraints from the CalNex 2010 field study. Cl· reactions with a set of alkenes and alcohols, and the simplified multiphase chemistry of N2O5, ClNO2, HOCl, ClONO2, and Cl2, none of which are currently part of the MCM, have been added to the mechanism. The presence of ClNO2 produces significant changes to oxidants, ozone, and nitrogen oxide partitioning, relative to model runs excluding ClNO2 formation. From a nighttime maximum of 1.5 ppbv ClNO2, the daytime maximum Cl· concentration reaches 1 × 105 atoms cm-3 at 07:00 model time, reacting mostly with a large suite of volatile organic compounds (VOC) to produce 2.2 times more organic peroxy radicals in the morning than in the absence of ClNO2. In the presence of several ppbv of nitrogen oxide radicals (NOx = NO + NO2), these perturbations lead to similar enhancements in hydrogen oxide radicals (HOx = OH + HO2). Neglecting contributions from HONO, the total integrated daytime radical source is 17% larger when including ClNO2, which leads to a similar enhancement in integrated ozone production of 15%. Detectable

  5. An MCM modeling study of nitryl chloride (ClNO2) impacts on oxidation, ozone production and nitrogen oxide partitioning in polluted continental outflow

    NASA Astrophysics Data System (ADS)

    Riedel, T. P.; Wolfe, G. M.; Danas, K. T.; Gilman, J. B.; Kuster, W. C.; Bon, D. M.; Vlasenko, A.; Li, S.-M.; Williams, E. J.; Lerner, B. M.; Veres, P. R.; Roberts, J. M.; Holloway, J. S.; Lefer, B.; Brown, S. S.; Thornton, J. A.

    2013-11-01

    Nitryl chloride (ClNO2) is produced at night by reactions of dinitrogen pentoxide (N2O5) on chloride containing surfaces. ClNO2 is photolyzed during the morning hours after sunrise to liberate highly reactive chlorine atoms (Cl·). This chemistry takes place primarily in polluted environments where the concentrations of N2O5 precursors (nitrogen oxide radicals and ozone) are high, though it likely occurs in remote regions at lower intensities. Recent field measurements have illustrated the potential importance of ClNO2 as a daytime Cl· source and a nighttime NOx reservoir. However, the fate of the Cl· and the overall impact of ClNO2 on regional photochemistry remain unclear. To this end, we have incorporated ClNO2 production, photolysis, and subsequent Cl· reactions into an existing Master Chemical Mechanism (MCM version 3.2) box model framework using observational constraints from the CalNex 2010 field study. Cl· reactions with a set of alkenes and alcohols, and the simplified multiphase chemistry of N2O5, ClNO2, HOCl, ClONO2, and Cl2, none of which are currently part of the MCM, have been added to the mechanism. The presence of ClNO2 produces significant changes to oxidants, ozone, and nitrogen oxide partitioning, relative to model runs excluding ClNO2 formation. From a nighttime maximum of 1.5 ppbv ClNO2, the daytime maximum Cl· concentration reaches 1 × 105 atoms cm-3 at 7 a.m., reacting mostly with a large suite of volatile organic compounds (VOC) to produce 2.2 times more organic peroxy radicals in the morning than in the absence of ClNO2. In the presence of several ppbv of nitrogen oxide radicals (NOx = NO + NO2), these perturbations lead to similar enhancements in hydrogen oxide radicals (HOx = OH + HO2). Neglecting contributions from HONO, the total integrated daytime radical source is 17% larger when including ClNO2, which leads to a similar enhancement in integrated ozone production of 15%. Detectable levels (tens of pptv) of chlorine containing

  6. Reactions of the melatonin metabolite N1-acetyl-5-methoxykynuramine (AMK) with the ABTS cation radical: identification of new oxidation products.

    PubMed

    Than, Ni Ni; Heer, Christina; Laatsch, Hartmut; Hardeland, Rüdiger

    2006-01-01

    The melatonin metabolite N1-acetyl-5-methoxykynuramine (AMK; 1), which was previously shown to be a potent radical scavenger, was oxidized using the ABTS cation radical [ABTS = 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid)]. Several new oxidation products were obtained, which were separated by repeated chromatography and characterized by spectroscopic methods such as mass spectrometry (ESI-MS and ESI-HRMS), 1H-NMR and 13C-NMR, HMBC, HSQC, H,H COSY correlations and IR spectroscopy. The main products were oligomers of 1 (3 dimers, 1 trimer and 2 tetramers). In all cases, the amino group N2 was involved in the reactions. Two of the dimers turned out to be cis (2a) and trans (2b) isomers containing an azo bond. In the other dimer (3a), the nitrogen atom N2 was attached to atom C5 of the second aromatic amine, with loss of the methoxy group. In the trimer (5), one N2 formed a bridge to C5 of unit B, as in the respective dimer, while this one of C had bridged to C6 of B. One of the tetramers (6) was composed of a trimer 5 attached to N2 of a fourth 1 molecule via an azo bond as in 2a/b. In the other tetramer (7), an additional C-C bond between rings B and C in 6 is assumed. Although oligomers of AMK may only attain low in vivo concentrations, the types of reactions observed shed light on the physiologically possible metabolism of AMK once reacted with a free radical. The displacement of a methoxy group, rarely seen in the oxidation of methoxylated biomolecules, underlines the reactivity of AMK (1). Preliminary data show that, in the presence of ABTS cation radicals, AMK (1) can interact with side chains of aromatic amino acids, a finding which may be crucial for understanding to date unidentified protein modification by a melatonin metabolite detected earlier in experiments with radioactively labeled melatonin.

  7. Activation of mitochondrial calcium-independent phospholipase A2γ (iPLA2γ) by divalent cations mediating arachidonate release and production of downstream eicosanoids.

    PubMed

    Moon, Sung Ho; Jenkins, Christopher M; Liu, Xinping; Guan, Shaoping; Mancuso, David J; Gross, Richard W

    2012-04-27

    Calcium-independent phospholipase A(2)γ (iPLA(2)γ) (PNPLA8) is the predominant phospholipase activity in mammalian mitochondria. However, the chemical mechanisms that regulate its activity are unknown. Here, we utilize iPLA(2)γ gain of function and loss of function genetic models to demonstrate the robust activation of iPLA(2)γ in murine myocardial mitochondria by Ca(2+) or Mg(2+) ions. Calcium ion stimulated the production of 2-arachidonoyl-lysophosphatidylcholine (2-AA-LPC) from 1-palmitoyl-2-[(14)C]arachidonoyl-sn-glycero-3-phosphocholine during incubations with wild-type heart mitochondrial homogenates. Furthermore, incubation of mitochondrial homogenates from transgenic myocardium expressing iPLA(2)γ resulted in 13- and 25-fold increases in the initial rate of radiolabeled 2-AA-LPC and arachidonic acid (AA) production, respectively, in the presence of calcium ion. Mass spectrometric analysis of the products of calcium-activated hydrolysis of endogenous mitochondrial phospholipids in transgenic iPLA(2)γ mitochondria revealed the robust production of AA, 2-AA-LPC, and 2-docosahexaenoyl-LPC that was over 10-fold greater than wild-type mitochondria. The mechanism-based inhibitor (R)-(E)-6-(bromomethylene)-3-(1-naphthalenyl)-2H-tetrahydropyran-2-one (BEL) (iPLA(2)γ selective), but not its enantiomer, (S)-BEL (iPLA(2)β selective) or pyrrolidine (cytosolic PLA(2)α selective), markedly attenuated Ca(2+)-dependent fatty acid release and polyunsaturated LPC production. Moreover, Ca(2+)-induced iPLA(2)γ activation was accompanied by the production of downstream eicosanoid metabolites that were nearly completely ablated by (R)-BEL or by genetic ablation of iPLA(2)γ. Intriguingly, Ca(2+)-induced iPLA(2)γ activation was completely inhibited by long-chain acyl-CoA (IC(50) ∼20 μm) as well as by a nonhydrolyzable acyl-CoA thioether analog. Collectively, these results demonstrate that mitochondrial iPLA(2)γ is activated by divalent cations and inhibited by acyl

  8. Activation of Mitochondrial Calcium-independent Phospholipase A2γ (iPLA2γ) by Divalent Cations Mediating Arachidonate Release and Production of Downstream Eicosanoids*♦

    PubMed Central

    Moon, Sung Ho; Jenkins, Christopher M.; Liu, Xinping; Guan, Shaoping; Mancuso, David J.; Gross, Richard W.

    2012-01-01

    Calcium-independent phospholipase A2γ (iPLA2γ) (PNPLA8) is the predominant phospholipase activity in mammalian mitochondria. However, the chemical mechanisms that regulate its activity are unknown. Here, we utilize iPLA2γ gain of function and loss of function genetic models to demonstrate the robust activation of iPLA2γ in murine myocardial mitochondria by Ca2+ or Mg2+ ions. Calcium ion stimulated the production of 2-arachidonoyl-lysophosphatidylcholine (2-AA-LPC) from 1-palmitoyl-2-[14C]arachidonoyl-sn-glycero-3-phosphocholine during incubations with wild-type heart mitochondrial homogenates. Furthermore, incubation of mitochondrial homogenates from transgenic myocardium expressing iPLA2γ resulted in 13- and 25-fold increases in the initial rate of radiolabeled 2-AA-LPC and arachidonic acid (AA) production, respectively, in the presence of calcium ion. Mass spectrometric analysis of the products of calcium-activated hydrolysis of endogenous mitochondrial phospholipids in transgenic iPLA2γ mitochondria revealed the robust production of AA, 2-AA-LPC, and 2-docosahexaenoyl-LPC that was over 10-fold greater than wild-type mitochondria. The mechanism-based inhibitor (R)-(E)-6-(bromomethylene)-3-(1-naphthalenyl)-2H-tetrahydropyran-2-one (BEL) (iPLA2γ selective), but not its enantiomer, (S)-BEL (iPLA2β selective) or pyrrolidine (cytosolic PLA2α selective), markedly attenuated Ca2+-dependent fatty acid release and polyunsaturated LPC production. Moreover, Ca2+-induced iPLA2γ activation was accompanied by the production of downstream eicosanoid metabolites that were nearly completely ablated by (R)-BEL or by genetic ablation of iPLA2γ. Intriguingly, Ca2+-induced iPLA2γ activation was completely inhibited by long-chain acyl-CoA (IC50 ∼20 μm) as well as by a nonhydrolyzable acyl-CoA thioether analog. Collectively, these results demonstrate that mitochondrial iPLA2γ is activated by divalent cations and inhibited by acyl-CoA modulating the generation of

  9. Production, Characterization, and Flocculation Mechanism of Cation Independent, pH Tolerant, and Thermally Stable Bioflocculant from Enterobacter sp. ETH-2

    PubMed Central

    Tang, Wei; Song, Liyan; Li, Dou; Qiao, Jing; Zhao, Tiantao; Zhao, Heping

    2014-01-01

    Synthetic high polymer flocculants, frequently utilized for flocculating efficiency and low cost, recently have been discovered as producing increased risk to human health and the environment. Development of a more efficient and environmentally sound alternative flocculant agent is investigated in this paper. Bioflocculants are produced by microorganisms and may exhibit a high rate of flocculation activity. The bioflocculant ETH-2, with high flocculating activity (2849 mg Kaolin particle/mg ETH-2), produced by strain Enterobacter sp. isolated from activated sludge, was systematically investigated with regard to its production, characterization, and flocculation mechanism. Analyses of microscopic observation, zeta potential and ETH-2 structure demonstrates the bridging mechanism, as opposed to charge neutralization, was responsible for flocculation of the ETH-2. ETH-2 retains high molecular weight (603 to 1820 kDa) and multi-functional groups (hydroxyl, amide and carboxyl) that contributed to flocculation. Polysaccharides mainly composed of mannose, glucose, and galactose, with a molar ratio of 1∶2.9∶9.8 were identified as the active constituents in bioflocculant. The structure of the long backbone with active sites of polysaccharides was determined as a primary basis for the high flocculation activity. Bioflocculant ETH-2 is cation independent, pH tolerant, and thermally stable, suggesting a potential fit for industrial application. PMID:25485629

  10. Production, characterization, and flocculation mechanism of cation independent, pH tolerant, and thermally stable bioflocculant from Enterobacter sp. ETH-2.

    PubMed

    Tang, Wei; Song, Liyan; Li, Dou; Qiao, Jing; Zhao, Tiantao; Zhao, Heping

    2014-01-01

    Synthetic high polymer flocculants, frequently utilized for flocculating efficiency and low cost, recently have been discovered as producing increased risk to human health and the environment. Development of a more efficient and environmentally sound alternative flocculant agent is investigated in this paper. Bioflocculants are produced by microorganisms and may exhibit a high rate of flocculation activity. The bioflocculant ETH-2, with high flocculating activity (2849 mg Kaolin particle/mg ETH-2), produced by strain Enterobacter sp. isolated from activated sludge, was systematically investigated with regard to its production, characterization, and flocculation mechanism. Analyses of microscopic observation, zeta potential and ETH-2 structure demonstrates the bridging mechanism, as opposed to charge neutralization, was responsible for flocculation of the ETH-2. ETH-2 retains high molecular weight (603 to 1820 kDa) and multi-functional groups (hydroxyl, amide and carboxyl) that contributed to flocculation. Polysaccharides mainly composed of mannose, glucose, and galactose, with a molar ratio of 1:2.9:9.8 were identified as the active constituents in bioflocculant. The structure of the long backbone with active sites of polysaccharides was determined as a primary basis for the high flocculation activity. Bioflocculant ETH-2 is cation independent, pH tolerant, and thermally stable, suggesting a potential fit for industrial application.

  11. The effect of concentrate feeding amount and feeding strategy on milk production, dry matter intake, and energy partitioning of autumn-calving Holstein-Friesian cows.

    PubMed

    Lawrence, D C; O'Donovan, M; Boland, T M; Lewis, E; Kennedy, E

    2015-01-01

    The objective of this study was to compare the milk production, dry matter intake, and energy partitioning of autumn-calving Holstein-Friesian cows offered a high or low amount of concentrate using 1 of 2 feeding strategies. One hundred and eight autumn-calving Holstein-Friesian cows were blocked based on milk production data from wk 3 and 4 of lactation, and were divided into low-, medium-, and high-milk yield subgroups. Cows were randomly assigned to 1 of 4 treatments (n=27) in a 2×2 factorial design. Treatment factors were concentrate feeding amount, high concentrate=7.0 (Hi) or low concentrate=4.0kg of DM/cow per day (Lo), and concentrate feeding strategy, flat rate (FR) or group-fed to yield (GFY). In the GFY treatments, cows were allocated concentrate based on their milk yield in the third and fourth weeks of lactation. The lowest-yielding cows (n=9) received 5.3 and 2.3kg of DM of concentrate on the Hi and Lo treatments respectively, the highest-yielding cows (n=9) received 8.7 and 5.7kg of DM of concentrate on the Hi and Lo treatments respectively, and the average yield cows received the same amount of concentrate as the corresponding FR group (i.e., 7.0 and 4.0kg of DM of concentrate on the Hi and Lo treatments, respectively). The proportion of forage in the diet was 63% of total dry matter intake (TDMI) for the Hi treatment and 75% of TDMI for the Lo treatment. No significant interaction was noted between concentrate feeding amount and concentrate feeding strategy for dry matter intake or milk yield. Cows on the Hi treatment had a higher TDMI (18.7±0.36kg/cow per day) compared with cows on the Lo treatment (15.8±0.36kg/cow per day). The milk yield of cows offered the Hi treatment was 1.3kg/cow per day higher than the milk yield of cows on the Lo treatment (23.8±0.31kg/cow per day). Milk solids yield was 0.10kg/cow per day higher on the Hi treatment than on the Lo treatment (1.83±0.03kg of DM/cow per day). Cows on the Hi treatment had an estimated net

  12. Productivity, Respiration, CO2 Sink Potential, and Light-Response Parameters of World Grasslands Derived From Flux-Tower Data Partitioning

    NASA Astrophysics Data System (ADS)

    Gilmanov, T. G.; Contributors, W. D.

    2007-12-01

    Net CO2 flux (Fc) data from 52 grassland flux tower sites in North America, Europe, and Asia representing 101 years of measurements were partitioned into gross primary productivity (Pg) and ecosystem respiration (Re) components using light-temperature-response functions method (Bas. Appl. Ecol. 2003, 4:167-183). This sample of sites encompasses a wide climatic range (mean annual temperatures 0.5 to 20° C and precipitation 190 to 1500 mm/yr) and includes unmanaged and extensively or intensively managed grasslands. Highest values of daily gross primary productivity (Pg,max = 64 g CO2/m2/d) were found in intensively managed grasslands of W. Europe with Atlantic climate, while lowest Pg,max (<10 g CO2/m2/d) were recorded in mixed prairies and shortgragss steppes of the Great Plains, shrubsteppes of the Intermountain West, and dry steppes of Mongolia. Maximum values of gross primary production (GPP) were achieved in intensively managed European grasslands with Atlantic climate (GPP=6900 g CO2/m2/yr), and lowest GPP values (<500 g CO2/m2/yr) were estimated for grazed mixed prairies under drought. Highest annual ecosystem respiration (RE) were recorded for warm-temperate and low montane W.European grasslands (RE > 5000 g CO2/m2/yr), and lowest RE were characteristic for shrubsteppes and grazed dry steppes (RE < 1000 g CO2/m2/yr). In 62 out of 101 site-years, the grasslands were net CO2 sinks, with average net annual CO2 exchange NEE = 250, maximum NEE = 2400 (uptake), and minimum NEE = -1350 g CO2/m2/yr (release). Maximum mean weekly values of the apparent quantum yield (α >70 mmol CO2/mol photons) were recorded in intensively managed Atlantic grasslands, the lowest weekly quantum efficiencies were observed in grazed mixed prairies of N.America and dry steppes of Central Asia (α <10 mmol/mol). The maximum values of the gross photosynthesis parameter (mean weekly Amax>2 mg CO2/m2/s) were estimated for intensively managed C3 grasslands of W.Europe and for unmanaged

  13. Milk production and nutrient partitioning as measured by (13)C enrichment of milk components during C3 and C4 plant feeding in purebred Holstein and in Charolais × Holstein F2 crossbred cows.

    PubMed

    Hillal, Hany; Voigt, Jürgen; Metges, Cornelia C; Hammon, Harald M

    2015-01-01

    Nutrient partitioning was investigated in cows with different genetic merits for milk production by measuring (13)C/(12)C ratios (reported by delta values δ(13)C) in milk components in response to C3 (grass silage) and C4 diets (corn silage). We hypothesised that changes of δ(13)C in milk differ between Holstein (HOL; high milk production) and Charolais × Holstein cows with medium (CHM) and low (CHL) milk production. Changes of δ(13)C (Δδ(13)C) in milk components were estimated by calculating differences of δ(13)C due to switch from C3 to C4 feeding. After switch to C4 feeding, Δδ(13)C of lactose was greater in HOL than in CHL. Immediate Δδ(13)C of milk fat was the lowest in CHL. The maximal Δδ(13)C of casein was the lowest in HOL. The proportion of carbon in milk derived from diet increased with milk yield, indicating the main impact of the milk production level, but minor impact of breed, on nutrient partitioning towards the mammary gland.

  14. Partitioning Breaks Communities

    NASA Astrophysics Data System (ADS)

    Reid, Fergal; McDaid, Aaron; Hurley, Neil

    Considering a clique as a conservative definition of community structure, we examine how graph partitioning algorithms interact with cliques. Many popular community-finding algorithms partition the entire graph into non-overlapping communities. We show that on a wide range of empirical networks, from different domains, significant numbers of cliques are split across the separate partitions produced by these algorithms. We then examine the largest connected component of the subgraph formed by retaining only edges in cliques, and apply partitioning strategies that explicitly minimise the number of cliques split. We further examine several modern overlapping community finding algorithms, in terms of the interaction between cliques and the communities they find, and in terms of the global overlap of the sets of communities they find. We conclude that, due to the connectedness of many networks, any community finding algorithm that produces partitions must fail to find at least some significant structures. Moreover, contrary to traditional intuition, in some empirical networks, strong ties and cliques frequently do cross community boundaries; much community structure is fundamentally overlapping and unpartitionable in nature.

  15. ABSORPTION METHOD FOR SEPARATING METAL CATIONS

    DOEpatents

    Tompkins, E.R.; Parker, G.W.

    1959-03-10

    An improved method is presented for the chromatographic separation of fission products wherein a substantial reduction in liquid volume is obtained. The process consists in contacting a solution containing fission products with a body of ion-exchange adsorbent to effect adsorption of fission product cations. The loaded exchange resin is then contacted with a small volume of a carboxylic acid eluant, thereby recovering the fission products. The fission product carrying eluate is acidified without increasing its volume to the volume of the original solution, and the acidified eluate is then used as a feed solution for a smaller body of ion-exchange resin effecting readsorption of the fission product cations.

  16. Iron Partitioning in Ferropericlase

    NASA Astrophysics Data System (ADS)

    Braithwaite, J. W. H.; Stixrude, L. P.; Pinilla, C.; Holmstrom, E.

    2015-12-01

    Ferropericlase, (Mg,Fe)O, is the second most abundant mineral in the Earth's lower mantle. Whether iron favours the liquid or solid phase of (Mg,Fe)O has important implications for the Earth's mantle, both chemically and dynamically. As iron is much heavier than magnesium, the partitioning of iron between liquid and solid will lead to a contrast in densities. This difference in density will lead one phase to be more buoyant than the other and would help, in part, to explain how the mantle crystallised from the magma ocean of the Hadean eon to its current state. The partitioning of iron between the two phases is characterized by partition coefficients. Using ab-initio methods, thermodynamic integration and adiabatic switching these coefficients have been determined. Results are presented for pressures encompassing the region between the upper mantle and the core-mantle boundary (10-140GPa).

  17. Partition density functional theory

    NASA Astrophysics Data System (ADS)

    Nafziger, Jonathan

    Partition density functional theory (PDFT) is a method for dividing a molecular electronic structure calculation into fragment calculations. The molecular density and energy corresponding to Kohn Sham density-functional theory (KS-DFT) may be exactly recovered from these fragments. Each fragment acts as an isolated system except for the influence of a global one-body 'partition' potential which deforms the fragment densities. In this work, the developments of PDFT are put into the context of other fragment-based density functional methods. We developed three numerical implementations of PDFT: One within the NWChem computational chemistry package using basis sets, and the other two developed from scratch using real-space grids. It is shown that all three of these programs can exactly reproduce a KS-DFT calculation via fragment calculations. The first of our in-house codes handles non-interacting electrons in arbitrary one-dimensional potentials with any number of fragments. This code is used to explore how the exact partition potential changes for different partitionings of the same system and also to study features which determine which systems yield non-integer PDFT occupations and which systems are locked into integer PDFT occupations. The second in-house code, CADMium, performs real-space calculations of diatomic molecules. Features of the exact partition potential are studied for a variety of cases and an analytical formula determining singularities in the partition potential is derived. We introduce an approximation for the non-additive kinetic energy and show how this quantity can be computed exactly. Finally a PDFT functional is developed to address the issues of static correlation and delocalization errors in approximations within DFT. The functional is applied to the dissociation of H2 + and H2.

  18. Electron capture dissociation mass spectrometry of peptide cations containing a lysine homologue: a mobile proton model for explaining the observation of b-type product ions.

    PubMed

    Lee, Sunyoung; Chung, Gyusung; Kim, Jaedong; Oh, Han Bin

    2006-01-01

    Eleven doubly protonated peptides with a residue homologous to lysine were investigated by electron capture dissociation mass spectrometry (ECD-MS). Lysine homologues provide the unique opportunity to examine the ECD fragmentation behavior by allowing us to vary the length of the lysine side chain, with minimal structural change. The lysine homologue has a primary amine side chain with a length that successively decreases by one methylene (CH(2)) unit from the --CH(2)CH(2)CH(2)CH(2)NH(2) of lysine and the accompanying decrease of its proton affinities: lysine (K), 1006.5(+/-7.2) kJ/mol; ornithine (K(*)), 1001.1(+/-6.6) kJ/mol; 2,4-diaminobutanoic acid (K(**)), 975.8(+/-7.4) kJ/mol; 2,3-diaminopropanoic acid (K(***)), 950.2(+/-7.2) kJ/mol. In general, the lysine-homologous peptides exhibited overall ECD fragmentation patterns similar to that of the lysine-containing peptides in terms of the locations, abundances, and ion types of products, such as yielding c(+) and z(+.) ions as the dominant product ions. However, a close inspection of product ion mass spectra showed that ECD-MS for the alanine-rich peptides with an ornithinyl or 2,4-diaminobutanoyl residue gave rise to b ions, while the lysinyl-residue-containing peptides did not, in most cases, produce any b ions. The peptide selectivity in the generation of b(+) ions could be understood from within the framework of the mobile proton model in ECD-MS, previously proposed by Cooper (Ref. 29). The exact mass analysis of the resultant b ions reveals that these b ions are not radical species but rather the cationic species with R-CO(+) structure (or protonated oxozalone ion), that is, b(+) ions. The absence of [M+2H](+.) species in the ECD mass spectra and the selective b(+)-ion formation are evidence that the peptides underwent H-atom loss upon electron capture, and then the resulting reduced species dissociated following typical MS/MS fragmentation pathways. This explanation was further supported by extensive b

  19. FNAS phase partitions

    NASA Technical Reports Server (NTRS)

    Vanalstine, James M.

    1993-01-01

    Project NAS8-36955 D.O. #100 initially involved the following tasks: (1) evaluation of various coatings' ability to control wall wetting and surface zeta potential expression; (2) testing various methods to mix and control the demixing of phase systems; and (3) videomicroscopic investigation of cell partition. Three complementary areas were identified for modification and extension of the original contract. They were: (1) identification of new supports for column cell partition; (2) electrokinetic detection of protein adsorption; and (3) emulsion studies related to bioseparations.

  20. The EPRL intertwiners and corrected partition function

    NASA Astrophysics Data System (ADS)

    Kamiński, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy

    2010-08-01

    Do the SU(2) intertwiners parametrize the space of the Engle, Pereira, Rovelli, Livine (EPRL) solutions to the simplicity constraint? What is the complete form of the partition function written in terms of this parametrization? We prove that the EPRL map is injective in the general n-valent vertex case for the Barbero-Immirzi parameter less than 1. We find, however, that the EPRL map is not isometric. In the consequence, a partition function can be defined either using the EPRL intertwiners Hilbert product or the SU(2) intertwiners Hilbert product. We use the EPRL one and derive a new, complete formula for the partition function. Next, we view it in terms of the SU(2) intertwiners. The result, however, goes beyond the SU(2) spin-foam models' framework and the original EPRL proposal.

  1. ESR study of the guanine cation

    NASA Astrophysics Data System (ADS)

    Close, David M.; Sagstuen, Einar; Nelson, William H.

    1985-05-01

    It has been proposed that the primary direct radiation damage products in DNA are guanine cations and thymine anions. Experiments reported here characterize a guanine cation observed in a single crystal of guanine:HCl:H2O. ESR experiments were performed by x-irradiating and observing the crystals at 15 K. Spectral parameters for the cation include N3 and N10 hyperfine couplings, a C8-Hα hyperfine coupling, and two small exchangeable couplings presumably from the N10 protons. The computed spin densities of ρ(N3)=0.283, ρ(N10)=0.168, and ρ(C8)=0.182 agree nicely with those observed for the guanine cation in DNA. In the single crystal the native molecule is protonated at N7. It is proposed that once the native molecule is oxidized it rapidly deprotonates at N7 to form the cation observed.

  2. The cubyl cation rearrangements.

    PubMed

    Jalife, Said; Mondal, Sukanta; Cabellos, Jose Luis; Martinez-Guajardo, Gerardo; Fernandez-Herrera, Maria A; Merino, Gabriel

    2016-02-25

    Born-Oppenheimer molecular dynamics simulations and high-level ab initio computations predict that the cage-opening rearrangement of the cubyl cation to the 7H(+)-pentalenyl cation is feasible in the gas phase. The rate-determining step is the formation of the cuneyl cation with an activation barrier of 25.3 kcal mol(-1) at the CCSD(T)/def2-TZVP//MP2/def2-TZVP level. Thus, the cubyl cation is kinetically stable enough to be formed and trapped at moderate temperatures, but it may be rearranged at higher temperatures.

  3. Advancements in Anion Exchange Membrane Cations

    SciTech Connect

    Sturgeon, Matthew R.; Long, Hai; Park, Andrew M.; Pivovar, Bryan S.

    2015-10-15

    Anion-exchange membrane fuel cells (AME-FCs) are of increasingly popular interest as they enable the use of non-Pt fuel cell catalysts, the primary cost limitation of proton exchange membrane fuel cells. Benzyltrimethyl ammonium (BTMA) is the standard cation that has historically been utilized as the hydroxide conductor in AEMs. Herein we approach AEMs from two directions. First and foremost we study the stability of several different cations in a hydroxide solution at elevated temperatures. We specifically targeted BTMA and methoxy and nitro substituted BTMA. We've also studied the effects of adding an akyl spacer units between the ammonium cation and the phenyl group. In the second approach we use computational studies to predict stable ammonium cations, which are then synthesized and tested for stability. Our unique method to study cation stability in caustic conditions at elevated temperatures utilizes Teflon Parr reactors suitable for use under various temperatures and cation concentrations. NMR analysis was used to determine remaining cation concentrations at specific time points with GCMS analysis verifying product distribution. We then compare the experimental results with calculated modeling stabilities. Our studies show that the electron donating methoxy groups slightly increase stability (compared to that of BTMA), while the electron withdrawing nitro groups greatly decrease stability in base. These results give insight into possible linking strategies to be employed when tethering a BTMA like ammonium cation to a polymeric backbone; thus synthesizing an anion exchange membrane.

  4. Gluing Nekrasov Partition Functions

    NASA Astrophysics Data System (ADS)

    Qiu, Jian; Tizzano, Luigi; Winding, Jacob; Zabzine, Maxim

    2015-07-01

    In this paper we summarise the localisation calculation of 5D super Yang-Mills on simply connected toric Sasaki-Einstein (SE) manifolds. We show how various aspects of the computation, including the equivariant index, the asymptotic behaviour and the factorisation property are governed by the combinatorial data of the toric geometry. We prove that the perturbative partition function on a simply connected SE manifold corresponding to an n-gon toric diagram factorises to n copies of perturbative part (zero instanton sector) of the Nekrasov partition function. This leads us to conjecture a prescription for the computation of the complete partition function, by gluing n copies of the full Nekrasov partition functions. This work is a generalisation of some earlier computation carried out on Y p, q manifolds, whose moment map cone has a quadrangle base and our result is valid for manifolds whose moment map cones have pentagon base, hexagon base, etc. The algorithm we used for dealing with general cones may also be of independent interest.

  5. DOES NITROGEN PARTITIONING PROMOTE SPECIES DIVERSITY IN ARCTIC TUSSOCK TUNDRA?

    EPA Science Inventory

    We used 15N soil-labeling techniques to examine how the dominant species in a N-limited, tussock tundra plant community partitioned soil N, and how such partitioning may contribute to community organization. The five most productive species were well differentiated with respect ...

  6. DOES NITROGEN PARTITIONING PROMOTE SPECIES DIVERSITY IN ARCTIC TUSSOCK TUNDRA?

    EPA Science Inventory

    We used 15N soil-labeling techniques to examine how the dominant species in a N-limited, tussock tundra plant community partitioned soil N, and how such partitioning may contribute to community organization. The five most productive species were well differentiated with respect ...

  7. A review of approaches for evapotranspiration partitioning

    USDA-ARS?s Scientific Manuscript database

    Partitioning of evapotranspiration (ET) into evaporation from the soil surface (E) and transpiration (T) is challenging but important in order to assess biomass production and the allocation of increasingly scarce water resources. Generally T is the desired component with the water being used to enh...

  8. Set Partitions and the Multiplication Principle

    ERIC Educational Resources Information Center

    Lockwood, Elise; Caughman, John S., IV

    2016-01-01

    To further understand student thinking in the context of combinatorial enumeration, we examine student work on a problem involving set partitions. In this context, we note some key features of the multiplication principle that were often not attended to by students. We also share a productive way of thinking that emerged for several students who…

  9. Set Partitions and the Multiplication Principle

    ERIC Educational Resources Information Center

    Lockwood, Elise; Caughman, John S., IV

    2016-01-01

    To further understand student thinking in the context of combinatorial enumeration, we examine student work on a problem involving set partitions. In this context, we note some key features of the multiplication principle that were often not attended to by students. We also share a productive way of thinking that emerged for several students who…

  10. Purification of dirucotide, a synthetic 17-aminoacid peptide, by ion exchange centrifugal partition chromatography.

    PubMed

    Boudesocque, Leslie; Forni, Luciano; Martinez, Agathe; Nuzillard, Jean-Marc; Giraud, Matthieu; Renault, Jean-Hugues

    2017-09-01

    Dirucotide is a synthetic drug candidate for the treatment of multiple sclerosis. This 17-aminoacid peptide was successfully purified by ion exchange centrifugal partition chromatography. The optimized conditions involved the biphasic methyl tert-butyl ether/acetonitrile/n-butanol/water (2:1:2:5, v/v) solvent system in the descending mode, the di(2-ethylhexyl)phosphoric acid cation-exchanger with an exchanger (di(2-ethylhexyl)phosphoric acid)/dirucotide mole ratio of 100 and Ca(2+) ions in aqueous solution as displacer. Critical impurities were efficiently eliminated and dirucotide was recovered in high yield and purity (69% and 98%, respectively) and with a productivity of 2.29g per liter of stationary phase per hour. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Mechanisms of fragmentation of cationic peptide ions

    NASA Astrophysics Data System (ADS)

    Zhao, Hong; Adams, Jeanette

    1993-06-01

    Fragmentation mechanisms for formation of several commonly occurring product ions in high-energy collision-induced induced decomposition spectra of either (M + Cat2+ - H)+ ions of peptides cationized with alkaline earth metal ions, (M + Ca+)+ ions cationized with alkali metal ions, or (M + H)+ ions are evaluated by using deuterium-labelled peptides. The different sources of hydrogen transferred in the reactions are identified. Our study supports some previously proposed mechanisms but also provides evidence for others.

  12. Equilibration timescale of atmospheric secondary organic aerosol partitioning

    NASA Astrophysics Data System (ADS)

    Shiraiwa, Manabu; Seinfeld, John H.

    2012-12-01

    Secondary organic aerosol (SOA) formed from partitioning of oxidation products of anthropogenic and biogenic volatile organic compounds (VOCs) accounts for a substantial portion of atmospheric particulate matter. In describing SOA formation, it is generally assumed that VOC oxidation products rapidly adopt gas-aerosol equilibrium. Here we estimate the equilibration timescale, τeq, of SOA gas-particle partitioning using a state-of-the-art kinetic flux model. τeq is found to be of order seconds to minutes for partitioning of relatively high volatility organic compounds into liquid particles, thereby adhering to equilibrium gas-particle partitioning. However, τeq increases to hours or days for organic aerosol associated with semi-solid particles, low volatility, large particle size, and low mass loadings. Instantaneous equilibrium partitioning may lead to substantial overestimation of particle mass concentration and underestimation of gas-phase concentration.

  13. Cation binding by bacteriorhodopsin

    SciTech Connect

    Chang, C.H.; Chen, J.G.; Govindjee, R.; Ebrey, T.

    1984-01-01

    It was found that extensively washed purple membrane has about 1 calcium and 3-4 magnesium ions bound per bacteriorhodopsin molecule. When these divalent cations are removed by any of a variety of means, the pigment changes its color from purple to blue (lambda/sub max/ approx. = 600 nm). This blue pigment, which can be formed at near neutral pH, is probably very similar to blue species formed when the pH of a purple membrane sample is lowered to approx. = 2. When any of a wide variety of cations are added to a blue membrane preparation, the characteristic purple color of bacteriorhodopsin returns. Divalent and trivalent cations are much more efficient than monovalent cations in restoring the purple color and are effective at a ratio approaching one cation per pigment molecule. Besides shifting the absorption spectrum, removal of the divalent cations drastically alters the photochemical cycle of bacteriorhodopsin, including abolishing the unprotonated Schiff base (M-type) intermediate. Finally, lanthanum not only displaces the divalent cations normally bound to the purple membrane but also greatly reduces both the rate of decay of the M412 intermediate and proton uptake.

  14. Selective Production of Electrostatically-Bound Adducts of Alkyl Cations/Polyoxoanions by the Collision-Induced Fragmentations of Their Quaternary Ammonium Counterparts

    NASA Astrophysics Data System (ADS)

    Cao, Jie; Xu, Chong; Fan, YanXuan; Fan, LinYuan; Zhang, XiuHui; Hu, ChangWen

    2013-06-01

    Solutions of the quaternary ammonium salts of a set of classic polyoxometalates (POMs) (Keggin [XM12O40]n-, Dawson [P2W18O62]6-, and Lindqvist [M6O19]2- (X = P, Si; M = W, Mo) were characterized by electrospray mass spectrometry. The gas-phase fragmentations of a series of quaternary ammonium-associated clusters were investigated by their collision-induced dissociations to elucidate their fragmentation mechanisms. It was found that the quaternary ammonium-associated clusters had distinctive dissociation characteristics. Moreover, the mono-quaternary ammonium-associated clusters, {NR4[POMs]}(n-1)-, shared a common fragmentation feature, that is, they decomposed exclusively into their respective alkyl cation-bound clusters irrespective of the different cation sizes and the different natures of the polyoxoanions. The optimized geometries and the binding energies of the mono cation-bound Lindqvist POM-based clusters were obtained by calculations. To the best of our knowledge, this is the first investigation of the gas-phase fragmentations of these noncovalent complexes between organic amines and inorganic POM anions by a combination of theory and mass spectrometry.

  15. Shedding light on daytime flux partitioning

    NASA Astrophysics Data System (ADS)

    Wohlfahrt, Georg

    2017-04-01

    Flux partitioning, that is disaggregating the measured net ecosystem carbon dioxide exchange into the underlying gross primary productivity (GPP) and ecosystem respiration (ER), has become a key component of the FLUXNET processing chain and the resulting products are widely used by experimentalists and modellers alike. Here I review flux partitioning based on light response curve modelling, commonly termed the daytime flux partitioning approach. In particular I tackle the question whether daytime flux partitioning is able to account for the reduction in daytime ER relative to nighttime due to the reduction in leaf mitochondrial respiration in the presence of daylight. To this end I use synthetic data (with realistic noise superimposed) generated (i) by light response curve models upon which a daytime reduction in ER was imposed, (ii) results from a process-oriented soil-vegetation-atmosphere-transfer model, as well as (iii) experimental data from a simple ecosystem, where daytime ER was estimated based on a combination of complementary measurements and a canopy model.

  16. Characterization of room-temperature ionic liquids by the Abraham model with cation-specific and anion-specific equation coefficients.

    PubMed

    Sprunger, Laura; Clark, Michael; Acree, William E; Abraham, Michael H

    2007-01-01

    Gas-to-RTIL (room-temperature ionic liquid) partition coefficients have been compiled for 592 different solute-RTIL combinations. These partition coefficients were converted into water-to-RTIL partition coefficients using the corresponding gas-to-water partition coefficients. Both sets of partition coefficients were analyzed using the Abraham solvation parameter model with cation-specific and anion-specific equation coefficients. The derived equations correlated the experimental gas-to-RTIL and water-to-RTIL partition coefficient data to within 0.10 and 0.14 log units, respectively. The 8 sets of calculated cation-specific equation coefficients and 4 sets of calculated anion-specific equation coefficients can be combined to yield expressions capable of predicting the partition coefficients of solutes in 32 different RTILs.

  17. Down-regulation of KORRIGAN-like endo-β-1,4-glucanase genes impacts carbon partitioning, mycorrhizal colonization and biomass production in Populus

    DOE PAGES

    Kalluri, Udaya C; Engle, Nancy L.; Bali, Garima; ...

    2016-10-04

    Here, a greater understanding of the genetic regulation of plant cell wall remodeling and the impact of modified cell walls on plant performance is important for the development of sustainable biofuel crops. Here, we studied the impact of down-regulating KORRIGAN-like cell wall biosynthesis genes, belonging to the endo-β-1,4-glucanase gene family, on Populus growth, metabolism and the ability to interact with symbiotic microbes. The reductions in cellulose content and lignin syringyl-to-guaiacyl unit ratio, and increase in cellulose crystallinity of cell walls of PdKOR RNAi plants corroborated the functional role of PdKOR in cell wall biosynthesis. Altered metabolism and reduced growth characteristicsmore » of RNAi plants revealed new implications on carbon allocation and partitioning. The distinctive metabolome phenotype comprised of a higher phenolic and salicylic acid content, and reduced lignin, shikimic acid and maleic acid content relative to control. Plant sustainability implications of modified cell walls on beneficial plant-microbe interactions were explored via co-culture with an ectomycorrhizal fungus, Laccaria bicolor. A significant increase in the mycorrhization rate was observed in transgenic plants, leading to measurable beneficial growth effects. These findings present new evidence for functional interconnectedness of cellulose biosynthesis pathway, metabolism and mycorrhizal association in plants, and further emphasize the consideration of the sustainability implications of plant trait improvement efforts.« less

  18. Down-Regulation of KORRIGAN-Like Endo-β-1,4-Glucanase Genes Impacts Carbon Partitioning, Mycorrhizal Colonization and Biomass Production in Populus

    PubMed Central

    Kalluri, Udaya C.; Payyavula, Raja S.; Labbé, Jessy L.; Engle, Nancy; Bali, Garima; Jawdy, Sara S.; Sykes, Robert W.; Davis, Mark; Ragauskas, Arthur; Tuskan, Gerald A.; Tschaplinski, Timothy J.

    2016-01-01

    A greater understanding of the genetic regulation of plant cell wall remodeling and the impact of modified cell walls on plant performance is important for the development of sustainable biofuel crops. Here, we studied the impact of down-regulating KORRIGAN-like cell wall biosynthesis genes, belonging to the endo-β-1,4-glucanase gene family, on Populus growth, metabolism and the ability to interact with symbiotic microbes. The reductions in cellulose content and lignin syringyl-to-guaiacyl unit ratio, and increase in cellulose crystallinity of cell walls of PdKOR RNAi plants corroborated the functional role of PdKOR in cell wall biosynthesis. Altered metabolism and reduced growth characteristics of RNAi plants revealed new implications on carbon allocation and partitioning. The distinctive metabolome phenotype comprised of a higher phenolic and salicylic acid content, and reduced lignin, shikimic acid and maleic acid content relative to control. Plant sustainability implications of modified cell walls on beneficial plant-microbe interactions were explored via co-culture with an ectomycorrhizal fungus, Laccaria bicolor. A significant increase in the mycorrhization rate was observed in transgenic plants, leading to measurable beneficial growth effects. These findings present new evidence for functional interconnectedness of cellulose biosynthesis pathway, metabolism and mycorrhizal association in plants, and further emphasize the consideration of the sustainability implications of plant trait improvement efforts. PMID:27757116

  19. Acid-catalyzed condensed-phase reactions of limonene and terpineol and their impacts on gas-to-particle partitioning in the formation of organic aerosols.

    PubMed

    Li, Yong Jie; Cheong, Gema Y L; Lau, Arthur P S; Chan, Chak K

    2010-07-15

    We investigated the condensed-phase reactions of biogenic VOCs with C double bond C bonds (limonene, C(10)H(16), and terpineol, C(10)H(18)O) catalyzed by sulfuric acid by both bulk solution (BS) experiments and gas-particle (GP) experiments using a flow cell reactor. Product analysis by gas chromatography-mass spectrometry (GC-MS) showed that cationic polymerization led to dimeric and trimeric product formation under conditions of relative humidity (RH) <20% (in the GP experiments) and a sulfuric acid concentration of 57.8 wt % (in the BS experiments), while hydration occurred under conditions of RH > 20% (in the GP experiments) and sulfuric acid concentrations of 46.3 wt % or lower (in the BS experiments). Apparent partitioning coefficients (K(p,rxn)) were estimated from the GP experiments by including the reaction products. Only under extremely low RH conditions (RH < 5%) did the values of K(p,rxn) ( approximately 5 x 10(-6) m(3)/microg for limonene and approximately 2 x 10(-5) m(3)/microg for terpineol) substantially exceed the physical partitioning coefficients (K(p) = 6.5 x 10(-8) m(3)/microg for limonene and =2.3 x 10(-6) m(3)/microg for terpineol) derived from the absorptive partitioning theory. At RH higher than 5%, the apparent partitioning coefficients (K(p,rxn)) of both limonene and terpineol were in the same order of magnitude as the K(p) values derived from the absorptive partitioning theory. Compared with other conditions including VOC concentration and degree of neutralization (by ammonium) of acidic particles, RH is a critical parameter that influences both the reaction mechanisms and the uptake ability (K(p,rxn) values) of these processes. The finding suggests that RH needs to be considered when taking the effects of acid-catalyzed reactions into account in estimating organic aerosol formation from C double bond C containing VOCs.

  20. Partitioning in Avionics Architectures: Requirements, Mechanisms, and Assurance

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1999-01-01

    Automated aircraft control has traditionally been divided into distinct "functions" that are implemented separately (e.g., autopilot, autothrottle, flight management); each function has its own fault-tolerant computer system, and dependencies among different functions are generally limited to the exchange of sensor and control data. A by-product of this "federated" architecture is that faults are strongly contained within the computer system of the function where they occur and cannot readily propagate to affect the operation of other functions. More modern avionics architectures contemplate supporting multiple functions on a single, shared, fault-tolerant computer system where natural fault containment boundaries are less sharply defined. Partitioning uses appropriate hardware and software mechanisms to restore strong fault containment to such integrated architectures. This report examines the requirements for partitioning, mechanisms for their realization, and issues in providing assurance for partitioning. Because partitioning shares some concerns with computer security, security models are reviewed and compared with the concerns of partitioning.

  1. Trace element partitioning between clinopyroxene and trachy-phonolitic melts: A case study from the Campanian Ignimbrite (Campi Flegrei, Italy)

    NASA Astrophysics Data System (ADS)

    Mollo, S.; Forni, F.; Bachmann, O.; Blundy, J. D.; De Astis, G.; Scarlato, P.

    2016-05-01

    The partitioning of trace elements between crystals and melts provides an important petrogenetic tool for understanding magmatic processes. We present trace element partition coefficients measured between clinopyroxene phenocrysts and trachy-phonolitic magmas at the Campi Flegrei (Italy), whose late Quaternary volcanism has been characterized by two major caldera-forming events (Campanian Ignimbrite at ~ 39 ka, and Neapolitan Yellow Tuff at ~ 15 ka). Our data indicate that the increase of trivalent rare earth elements and yttrium into the crystal lattice M2 site is facilitated by the charge-balancing substitution of Si4 + with Al3 + on the tetrahedral site. Higher concentrations of tetravalent and pentavalent high field strength elements on the M1 site are also measured when the average charge on this site is increased by the substitution of divalent cations by Alvi. In contrast, due to these charge balance requirements, divalent transitional elements become less compatible within the crystal lattice. On the basis of the lattice strain theory, we document that the incorporation of rare earth elements and yttrium in clinopyroxene is influenced by both compositional and physical parameters. Data from this study allow to update existing partitioning equations for rare earth elements in order to construct a self-consistent model for trachy-phonolitic magmas based on the lattice strain theory. The application of this model to natural products from the Campanian Ignimbrite, the largest caldera-forming eruption at the Campi Flegrei, reveals that the complex rare earth element pattern recorded by the eruptive products can be successfully described by the stepwise fractional crystallization of clinopyroxene and feldspar where the clinopyroxene-melt partition coefficient changes progressively as a function of the physicochemical conditions of the system.

  2. Partition of polycyclic aromatic hydrocarbons on organobentonites from water.

    PubMed

    Chen, B L; Zhu, L Z

    2001-04-01

    A series of organobentonites synthesized by exchanging organic cation such as dodecyltri-methylammonium (DTMA), benzyldimethyltetradecylammonium (BDTDA), cetyltrimethyl-ammonium (CTMA), octodeyltrimethylammonium (OTMA) on bentonite. The optimal condition, properties and mechanisms for the organobentonites to sorb phenanthrene, anthracene, naphthalene, acenaphthene in water were investigated in detail. The partition behavior was determined for four polycyclic aromatic hydrocarbons (PAHs), such as naphthalene, phenanthrene, anthracene and acenaphthene, from water to a series of organobentonites. The interlayer spacings and organic carbon contents of organobentonites, removal rate and sorption capacities for organobentonites to treat phenanthrene, anthracene, naphthalene, acenaphthene were correlated to the length of alkyl chains and the amounts of cation surfactant exchanged on the bentonite. Phenanthrene, anthracene, naphthalene, and acenaphthene sorption to organobentonites were characterized by linear isotherms, indicating solute partition between water and the organic phase composed of the large alkyl functional groups of quaternary ammonium cations. PAHs distribution coefficients (Kd) between organobentonites and water were proportional to the organic carbon contents of organobentonites. However, the partition coefficients (Koc) were nearly constants for PAHs in the system of organobentonite-water. The Koc of phenanthrene, anthracene, naphthalene, acenaphthene were 2.621 x 10(5), 2.106 x 10(5), 2.247 x 10(4), 5.085 x 10(4), respectively. The means Koc values on the organobentonites are about ten to twenty times larger than the values on the soils/sediments, what is significant prerequisite for organobentonite to apply to remediation of pollution soil and groundwater. The sorption mechanism was also evaluated from octanol-water partition coefficients and aqueous solubility of PAHs. The correlations between 1gKoc and 1gKow, 1gKoc and 1gS for PAHs in the system of

  3. Partitioning of Nb, Mo, Ba, Ce, Pb, Th and U between immiscible carbonate and silicate liquids: Evaluating the effects of P2O5,F, and carbonate composition

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Walker, D.

    1993-01-01

    Previously we have reported carbonate liq./silicate liq. partition coefficients (D) for a standard suite of trace elements (Nb, Mo, Ba, Ce, Pb, Th, and U) and Ra and Pa as well. In brief, we have found that immiscible liquid partitioning is a strong function of temperature. As the critical temperature of the carbonate-silicate solvus is approached, all partition coefficients approach unity. Additionally, for the overwhelming majority of the partitioning elements, InD is a linear function of 'ionic field strength,' z/r, where z is the charge of the partitioned cation and r is its ionic radius.

  4. Chemical amplification based on fluid partitioning

    DOEpatents

    Anderson, Brian L.; Colston, Jr., Billy W.; Elkin, Chris

    2006-05-09

    A system for nucleic acid amplification of a sample comprises partitioning the sample into partitioned sections and performing PCR on the partitioned sections of the sample. Another embodiment of the invention provides a system for nucleic acid amplification and detection of a sample comprising partitioning the sample into partitioned sections, performing PCR on the partitioned sections of the sample, and detecting and analyzing the partitioned sections of the sample.

  5. A search for blues brothers: X-ray crystallographic/spectroscopic characterization of the tetraarylbenzidine cation radical as a product of aging of solid magic blue.

    PubMed

    Talipov, Marat R; Hossain, Mohammad M; Boddeda, Anitha; Thakur, Khushabu; Rathore, Rajendra

    2016-03-14

    Magic blue (MB+˙ SbCl6− salt), i.e. tris-4-bromophenylamminium cation radical, is a routinely employed one-electron oxidant that slowly decomposes in the solid state upon storage to form so called ‘blues brothers’, which often complicate the quantitative analyses of the oxidation processes. Herein, we disclose the identity of the main ‘blues brother’ as the cation radical and dication of tetrakis-(4-bromophenyl)benzidine (TAB) by a combined DFT and experimental approach, including isolation of TAB+˙ SbCl6− and its X-ray crystallography characterization. The formation of TAB in aged magic blue samples occurs by a Scholl-type coupling of a pair of MB followed by a loss of molecular bromine. The recognition of this fact led us to the rational design and synthesis of tris(2-bromo-4-tert-butylphenyl)amine, referred to as ‘blues cousin’ (BC: Eox1 = 0.78 V vs. Fc/Fc+, λmax(BC+˙) = 805 nm, εmax = 9930 cm−1 M−1), whose oxidative dimerization is significantly hampered by positioning the sterically demanding tert-butyl groups at the para-positions of the aryl rings. A ready two-step synthesis of BC from triphenylamine and the high stability of its cation radical (BC+˙) promise that BC will serve as a ready replacement for MB and an oxidant of choice for mechanistic investigations of one-electron transfer processes in organic, inorganic, and organometallic transformations.

  6. Partitioning the Quaternary

    NASA Astrophysics Data System (ADS)

    Gibbard, Philip L.; Lewin, John

    2016-11-01

    We review the historical purposes and procedures for stratigraphical division and naming within the Quaternary, and summarize the current requirements for formal partitioning through the International Commission on Stratigraphy (ICS). A raft of new data and evidence has impacted traditional approaches: quasi-continuous records from ocean sediments and ice cores, new numerical dating techniques, and alternative macro-models, such as those provided through Sequence Stratigraphy and Earth-System Science. The practical usefulness of division remains, but there is now greater appreciation of complex Quaternary detail and the modelling of time continua, the latter also extending into the future. There are problems both of commission (what is done, but could be done better) and of omission (what gets left out) in partitioning the Quaternary. These include the challenge set by the use of unconformities as stage boundaries, how to deal with multiphase records in ocean and terrestrial sediments, what happened at the 'Early-Mid- (Middle) Pleistocene Transition', dealing with trends that cross phase boundaries, and the current controversial focus on how to subdivide the Holocene and formally define an 'Anthropocene'.

  7. Inhibition of phospho-MurNAc-pentapeptide translocase (MraY) by nucleoside natural product antibiotics, bacteriophage ϕX174 lysis protein E, and cationic antibacterial peptides.

    PubMed

    Bugg, Timothy D H; Rodolis, Maria T; Mihalyi, Agnes; Jamshidi, Shirin

    2016-12-15

    This review covers recent developments in the inhibition of translocase MraY and related phospho-GlcNAc transferases WecA and TagO, and insight into the inhibition and catalytic mechanism of this class of integral membrane proteins from the structure of Aquifex aeolicus MraY. Recent studies have also identified a protein-protein interaction site in Escherichia coli MraY, that is targeted by bacteriophage ϕX174 lysis protein E, and also by cationic antimicrobial peptides containing Arg-Trp close to their N- or C-termini. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Collision cross-sections of [C,H,O] cations and radical cations from aliphatic [C,H,O] compounds

    NASA Astrophysics Data System (ADS)

    van Houte, J. J.; van Thuijl, J.

    1994-05-01

    Over 260 collision cross-section [sigma]ot, expressed in »ngströms squared, have been determined for the studied ions at 20 and 70 eV by extrapolation of [sigma]t to zero target gas pressure, and these yield two types of structural information. The first type concerns occurrence and detection of cyclic ions, the second isomerization of parent molecular ions and different product ion distributions at 20 and 70 eV. In addition, examples of two distinct fragmentation mechanisms operative in the formation of identical daughter ions from a given precursor could be traced. Formation of cyclic daughter ions is, for instance, observed for C2H3O+ from oxirane, C3H5O+ from oxetane, C4H7O+2 from 4-methyl-1,3-dioxolane. Cyclic molecular ions are formed in varying proportions from oxirane, tetrahydrofuran, 2- and 4-methyl-1,3-dioxolane but not from porpylene oxide, oxetane and 1,3-dioxolane. Isomerization of the parent molecular ion is proposed for the following fragmentations: CH2 from allyl alcohol, CHO2+ from formic acid, C2H2O·+ from oxirane, and C3H6O·+ from 3-methyl butanal and 2-methyl pentanal. Different product ion distributions at 20 and 70 eV were found for C3H5O+ from ethyl propionate and 2-pentanone, C2H4O·+ and C4H8O·+ from butane-1,3-diol, and C3H6O·+ from 2- and 4-methyl-1,3-dioxolane. Two distinct fragmentation mechanisms were traced for the following processes: CH2OH, C2H2O·+ and C2H3O+ from methyl vinyl ether, CH2 and C2H5O+ from butane-1,3-diol and C2H2O·+ from butanone. Self protonation of acetaldehyde also appears to take place by two mechanisms. Energy partitioning is evident in the formation of formyl cations HCO+ but wears off for processes in which larger daughter ions are formed. For formyl cations from straight chain aldehydes, the 70 eV collision cross-section is linearly related to the logarithm of the reciprocal of the number of degrees of freedom in the parent molcule, log (1/DFp). One example of a proton-bound dimer is given, that of

  9. Partitioning the UMLS semantic network.

    PubMed

    Chen, Zong; Perl, Yehoshua; Halper, Michael; Geller, James; Gu, Huanying

    2002-06-01

    The unified medical language system (UMLS) integrates many well-established biomedical terminologies. The UMLS semantic network (SN) can help orient users to the vast knowledge content of the UMLS Metathesaurus (META) via its abstract conceptual view. However, the SN itself is large and complex and may still be difficult to comprehend. Our technique partitions the SN into smaller meaningful units amenable to display on limited-sized computer screens. The basis for the partitioning is the distribution of the relationships within the SN. Three rules are applied to transform the original partition into a second more cohesive partition.

  10. Sorption of phenol, p-nitrophenol, and aniline to dual-cation organobentonites from water

    SciTech Connect

    Zhu, L.; Chen, B.; Shen, X.

    2000-02-01

    A series of dual-cation organobentonites are synthesized by replacing the metal ions in bentonite with both long-chain alkyl quaternary ammonium cations, such as dodecyltrimethylammonium (DTMA), benzyldimethyltetradecylammonium (BDTDA), cetyltrimethylammonium (CTMA), octodecyltrimethylammonium (OTMA), and short-chain alkyl quaternary ammonium cations, such as tetramethylammonium (TMA). The influential factors, mechanisms and characteristics of polar and ionizable organic contaminants, such as p-nitrophenol, phenol, and aniline, and sorption to dual-cation organobentonites from water are investigated systematically and described quantitatively. The sorption properties are affected by treatment conditions, such as pH, amount of organobentonite, and shaking time; structure of organobentonites, such as interlayer spacings and organic carbon contents; and the properties of organic compounds, such as solubility and octanol-water coefficient partition. Sorption isotherms of p-nitrophenol, phenol, and aniline are typically nonlinear. Both adsorption and partition contribute to the sorption of organic compounds to dual-cation organobentonites. The separate contributions of adsorption and partition to the total sorption of organic compounds to dual-cation organobentonites are analyzed mathematically, e.g., Q{sub A} = a in C{sub e} + b {minus} K{sub oc}{center_dot}f{sub oc}{center_dot}C{sub e}, O{sub p} = K{sub oc}{center_dot}f{sub oc}{center_dot}C{sub e}. Results indicate that the partition effect is weak and linear to contaminant concentration, whereas adsorption effect is more powerful and nonlinear to contaminant concentration. The sorption of organic compounds to dual-cation organobentonite is dominated by adsorption at low concentrations and by partition at high concentrations, making the organobentonites powerful sorbents for organic contaminants over a wide range of concentrations.

  11. The production of recombinant cationic α-helical antimicrobial peptides in plant cells induces the formation of protein bodies derived from the endoplasmic reticulum.

    PubMed

    Company, Nuri; Nadal, Anna; La Paz, José-Luis; Martínez, Sílvia; Rasche, Stefan; Schillberg, Stefan; Montesinos, Emilio; Pla, Maria

    2014-01-01

    Synthetic linear antimicrobial peptides with cationic α-helical structures, such as BP100, are valuable as novel therapeutics and preservatives. However, they tend to be toxic when expressed at high levels as recombinant peptides in plants, and they can be difficult to detect and isolate from complex plant tissues because they are strongly cationic and display low extinction coefficient and extremely limited immunogenicity. We therefore expressed BP100 with a C-terminal tag which preserved its antimicrobial activity and demonstrated significant accumulation in plant cells. We used a fluorescent tag to trace BP100 following transiently expression in Nicotiana benthamiana leaves and showed that it accumulated in large vesicles derived from the endoplasmic reticulum (ER) along with typical ER luminal proteins. Interestingly, the formation of these vesicles was induced by BP100. Similar vesicles formed in stably transformed Arabidopsis thaliana seedlings, but the recombinant peptide was toxic to the host during latter developmental stages. This was avoided by selecting active BP100 derivatives based on their low haemolytic activity even though the selected peptides remained toxic to plant cells when applied exogenously at high doses. Using this strategy, we generated transgenic rice lines producing active BP100 derivatives with a yield of up to 0.5% total soluble protein. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  12. Actinide Partitioning and Radiation Effects in U(VI)-Solids: Thermodynamic & Mechanistic Study

    SciTech Connect

    Clark, Sue B.; Ewing, Rodney C.

    2010-05-20

    In most environmental systems, the mobility of a contaminant metal cation depends on its partitioning between the solid and solution phase. At the molecular level, partitioning to the solid phase is controlled by the coordination requirements of the contaminant cation. In this work, we developed linear free energy relationships (LFERs) to describe the partitioning of non-U actinide cations to U(VI) solid phases in a radiation environment; the LFERs are based on knowledge of the actinide coordination environment in or on the surface of the U(VI) solid, and the impact of ionizing radiation on the atomic interactions of the non-U actinide cations. LFERs were established for predicting (1) free energies of formation of pure U(VI) solids and solid solutions with non-U actinide cations, and (2) the adsorption of non-U actinide cations to pure U(VI) solids. We demonstrated the application of LFERs developed from knowledge of molecular structures of U(VI) solid phases to predict the predominance of U(VI) oxide hydrate and silicate solid phases as a function of geochemical conditions. We extended our efforts to define LFERs for U(VI) phosphate solids, and included the impact of actinide self-radiation on all LFERs for free energies of formation for U(VI) solids. We also defined LFERs for the formation of solid solutions between the U(VI) solids and non-U actinide cations such as Th, Np, Pu, Am, and Cm. We demonstrated the importance of nanocrystalline solids in the solid phase partitioning of these non-U actinide cations. For those solid solutions formed, we investigated the impact of ionizing radiation on the stability of those phases, and the release of the non-U actinide cations from the solids. Finally, developed LFERs to predict the adsorption of the non-U actinide cations to the surfaces of U(VI) oxide hydrates and U(VI) phosphates. We determined adsorption constants and coordination requirements for actinide adsorption to U(VI) solid phases. We determined

  13. Cationically polymerizable monomers derived from renewable sources. Final report

    SciTech Connect

    1995-09-01

    Objective is to use products from plant sources as monomers for direct production of polymers for plastic applications. (Epoxidized triglycerides as renewable monomers in photoinitiated cationic polymerization.) High-volume American agricultural products such as soybean, cotton or linseed oils or forestry products such as lignin and cellulose derived chemicals were targeted for use either directly or with slight modification for producing the plastics. Cationic photopolymerization will be used.

  14. Partition Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Wasserman, Adam

    2012-02-01

    Partition Density Functional Theory (PDFT) is a formally exact method for obtaining molecular properties from self-consistent calculations on isolated fragments [1,2]. For a given choice of fragmentation, PDFT outputs the (in principle exact) molecular energy and density, as well as fragment densities that sum to the correct molecular density. I describe our progress understanding the behavior of the fragment energies as a function of fragment occupations, derivative discontinuities, practical implementation, and applications of PDFT to small molecules. I also discuss implications for ground-state Density Functional Theory, such as the promise of PDFT to circumvent the delocalization error of approximate density functionals. [4pt] [1] M.H. Cohen and A. Wasserman, J. Phys. Chem. A, 111, 2229(2007).[0pt] [2] P. Elliott, K. Burke, M.H. Cohen, and A. Wasserman, Phys. Rev. A 82, 024501 (2010).

  15. Cationically polymerizable monomers derived from renewable sources

    SciTech Connect

    Crivello, J.V.

    1991-10-01

    The objective of this project is to make use of products obtained from renewable plant sources as monomers for the direct production of polymers which can be used for a wide range of plastic applications. In this report is described progress in the synthesis and polymerization of cationically polymerizable monomers and oligomers derived from botanical oils, terpenes, natural rubber, and lignin. Nine different botanical oils were obtained from various sources, characterized and then epoxidized. Their photopolymerization was carried out using cationic photoinitiators and the mechanical properties of the resulting polymers characterized. Preliminary biodegradation studies are being conducted on the photopolymerized films from several of these oils. Limonene was cationically polymerized to give dimers and the dimers epoxidized to yield highly reactive monomers suitable for coatings, inks and adhesives. The direct phase transfer epoxidation of squalene and natural rubber was carried out. The modified rubbers undergo facile photocrosslinking in the presence of onium salts to give crosslinked elastomers. 12 refs., 3 figs., 10 tabs.

  16. Exact partition functions for gauge theories on Rλ3

    NASA Astrophysics Data System (ADS)

    Wallet, Jean-Christophe

    2016-11-01

    The noncommutative space Rλ3, a deformation of R3, supports a 3-parameter family of gauge theory models with gauge-invariant harmonic term, stable vacuum and which are perturbatively finite to all orders. Properties of this family are discussed. The partition function factorizes as an infinite product of reduced partition functions, each one corresponding to the reduced gauge theory on one of the fuzzy spheres entering the decomposition of Rλ3. For a particular sub-family of gauge theories, each reduced partition function is exactly expressible as a ratio of determinants. A relation with integrable 2-D Toda lattice hierarchy is indicated.

  17. Partitioning: splitting fact from fiction.

    PubMed

    Pike, Brian

    2012-05-01

    Many larger hospitals are sprawling complexes with endless corridors and rooms of varying purpose. While cleanliness and infection control are, understandably, leading considerations in any hospital building, fire safety also plays a crucial role. Here Brian Pike MBE, technical consultant at partitioning system designer and manufacturer, Komfort Workspace, looks at how current fire guidelines impact on the use of partitioning systems in hospital premises.

  18. Partitioning of Ni, Co and V between Spinel-Structured Oxides and Silicate Melts: Importance of Spinel Composition

    NASA Technical Reports Server (NTRS)

    Righter, K.; Leeman, W. P.; Hervig, R. L.

    2006-01-01

    Partitioning of Ni, Co and V between Cr-rich spinels and basaltic melt has been studied experimentally between 1150 and 1325 C, and at controlled oxygen fugacity from the Co-CoO buffer to slightly above the hematite magnetite buffer. These new results, together with new Ni, Co and V analyses of experimental run products from Leeman [Leeman, W.P., 1974. Experimental determination of the partitioning of divalent cations between olivine and basaltic liquid, Pt. II. PhD thesis, Univ. Oregon, 231 - 337.], show that experimentally determined spinel melt partition coefficients (D) are dependent upon temperature (T), oxygen fugacity (fO2) and spinel composition. In particular, partition coefficients determined on doped systems are higher than those in natural (undoped) systems, perhaps due to changing activity coefficients over the composition range defined by the experimental data. Using our new results and published runs (n =85), we obtain a multilinear regression equation that predicts experimental D(V) values as a function of T, fO2, concentration of V in melt and spinel composition. This equation allows prediction of D(V) spinel/melt values for natural mafic liquids at relevant crystallization conditions. Similarly, D(Ni) and D(Co) values can be inferred from our experiments at redox conditions approaching the QFM buffer, temperatures of 1150 to 1250 C and spinel composition (early Cr-bearing and later Ti-magnetite) appropriate for basic magma differentiation. When coupled with major element modelling of liquid lines of descent, these values (D(Ni) sp/melt=10 and D(Co) sp/melt=5) closely reproduce the compositional variation observed in komatiite, mid-ocean ridge basalt (MORB), ocean island basalt (OIB) and basalt to rhyolite suites.

  19. Partitioning Rectangular and Structurally Nonsymmetric Sparse Matrices for Parallel Processing

    SciTech Connect

    B. Hendrickson; T.G. Kolda

    1998-09-01

    A common operation in scientific computing is the multiplication of a sparse, rectangular or structurally nonsymmetric matrix and a vector. In many applications the matrix- transpose-vector product is also required. This paper addresses the efficient parallelization of these operations. We show that the problem can be expressed in terms of partitioning bipartite graphs. We then introduce several algorithms for this partitioning problem and compare their performance on a set of test matrices.

  20. Phase II Nuclide Partition Laboratory Study Influence of Cellulose Degradation Products on the Transport of Nuclides from SRS Shallow Land Burial Facilities

    SciTech Connect

    Serkiz, S.M.

    1999-10-04

    Degradation products of cellulosic materials (e.g., paper and wood products) can significantly influence the subsurface transport of metals and radionuclides. Codisposal of radionuclides with cellulosic materials in the E-Area slit trenches at the Savannah River Site (SRS) is, therefore, expected to influence nuclide fate and transport in the subsurface. Due to the complexities of these systems and the scarcity of site-specific data, the effects of cellulose waste loading and its subsequent influence on nuclide transport are not well established.

  1. Production and Isomeric Distribution of Xanthylium Cation Pigments and Their Precursors in Wine-like Conditions: Impact of Cu(II), Fe(II), Fe(III), Mn(II), Zn(II), and Al(III).

    PubMed

    Guo, Anque; Kontoudakis, Nikolaos; Scollary, Geoffrey R; Clark, Andrew C

    2017-03-09

    This study establishes the influence of Cu(II), Fe(II), Fe(III), Zn(II), Al(III), and Mn(II) on the oxidative production of xanthylium cations from (+)-catechin and either tartaric acid or glyoxylic acid in model wine systems. The reaction was studied at 25 °C using UHPLC and LC-HRMS for the analysis of phenolic products and their isomeric distribution. In addition to the expected products, a colorless product, tentatively assigned as a lactone, was detected for the first time. The results show the importance of Fe ions and a synergistic influence of Mn(II) in degrading tartaric acid to glyoxylic acid, whereas the other metal ions had minimal activity in this mechanistic step. Fe(II) and Fe(III) were shown to mediate the (+)-catechin-glyoxylic acid addition reaction, a role previously attributed to only Cu(II). Importantly, the study demonstrates that C-8 addition products of (+)-catechin are promoted by Cu(II), whereas C-6 addition products are promoted by Fe ions.

  2. Photosynthesis and assimilate partitioning between carbohydrates and isoprenoid products in vegetatively active and dormant guayule: physiological and environmental constraints on rubber accumulation in a semiarid shrub

    USDA-ARS?s Scientific Manuscript database

    The stems and roots of the desert shrub guayule, Parthenium argentatum, contain a significant amount of latex that can be used as a source of natural rubber. Photosynthesis and the levels of carbohydrates and volatile isoprenoid products were measured in guayule plants grown under simulated summer-...

  3. Thermodynamic controls on element partitioning between titanomagnetite and andesitic-dacitic silicate melts

    NASA Astrophysics Data System (ADS)

    Sievwright, R. H.; Wilkinson, J. J.; O'Neill, H. St. C.; Berry, A. J.

    2017-08-01

    Titanomagnetite-melt partitioning of Mg, Mn, Al, Ti, Sc, V, Co, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Hf and Ta was investigated experimentally as a function of oxygen fugacity ( fO2) and temperature ( T) in an andesitic-dacitic bulk-chemical compositional range. In these bulk systems, at constant T, there are strong increases in the titanomagnetite-melt partitioning of the divalent cations (Mg2+, Mn2+, Co2+, Ni2+, Zn2+) and Cu2+/Cu+ with increasing fO2 between 0.2 and 3.7 log units above the fayalite-magnetite-quartz buffer. This is attributed to a coupling between magnetite crystallisation and melt composition. Although melt structure has been invoked to explain the patterns of mineral-melt partitioning of divalent cations, a more rigorous justification of magnetite-melt partitioning can be derived from thermodynamic principles, which accounts for much of the supposed influence ascribed to melt structure. The presence of magnetite-rich spinel in equilibrium with melt over a range of fO2 implies a reciprocal relationship between a(Fe2+O) and a(Fe3+O1.5) in the melt. We show that this relationship accounts for the observed dependence of titanomagnetite-melt partitioning of divalent cations with fO2 in magnetite-rich spinel. As a result of this, titanomagnetite-melt partitioning of divalent cations is indirectly sensitive to changes in fO2 in silicic, but less so in mafic bulk systems.

  4. Cation-Coupled Bicarbonate Transporters

    PubMed Central

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2016-01-01

    Cation-coupled HCO3− transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3− and associated with Na+ and Cl− movement. The first Na+-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 (SLC4A7 gene product); the Na+-driven Cl,HCO3-exchanger NDCBE (SLC4A8 gene product); and NBCn2/NCBE (SLC4A10 gene product), which has been characterized as an electroneutral Na,HCO3-cotransporter or a Na+-driven Cl,HCO3-exchanger. Despite the similarity in amino acid sequence and predicted structure among the NCBTs of the SLC4-family, they exhibit distinct differences in ion dependency, transport function, pharmacological properties, and interactions with other proteins. In epithelia, NCBTs are involved in transcellular movement of acid-base equivalents and intracellular pH control. In nonepithelial tissues, NCBTs contribute to intracellular pH regulation; and hence, they are crucial for diverse tissue functions including neuronal discharge, sensory neuron development, performance of the heart, and vascular tone regulation. The function and expression levels of the NCBTs are generally sensitive to intracellular and systemic pH. Animal models have revealed pathophysiological roles of the transporters in disease states including metabolic acidosis, hypertension, visual defects, and epileptic seizures. Studies are being conducted to understand the physiological consequences of genetic polymorphisms in the SLC4-members, which are associated with cancer, hypertension, and drug addiction. Here, we describe the current knowledge regarding the function, structure, and regulation of the mammalian cation-coupled HCO3− transporters of the SLC4-family. PMID:25428855

  5. Cation-coupled bicarbonate transporters.

    PubMed

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2014-10-01

    Cation-coupled HCO3(-) transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3(-) and associated with Na(+) and Cl(-) movement. The first Na(+)-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 (SLC4A7 gene product); the Na(+)-driven Cl,HCO3-exchanger NDCBE (SLC4A8 gene product); and NBCn2/NCBE (SLC4A10 gene product), which has been characterized as an electroneutral Na,HCO3-cotransporter or a Na(+)-driven Cl,HCO3-exchanger. Despite the similarity in amino acid sequence and predicted structure among the NCBTs of the SLC4-family, they exhibit distinct differences in ion dependency, transport function, pharmacological properties, and interactions with other proteins. In epithelia, NCBTs are involved in transcellular movement of acid-base equivalents and intracellular pH control. In nonepithelial tissues, NCBTs contribute to intracellular pH regulation; and hence, they are crucial for diverse tissue functions including neuronal discharge, sensory neuron development, performance of the heart, and vascular tone regulation. The function and expression levels of the NCBTs are generally sensitive to intracellular and systemic pH. Animal models have revealed pathophysiological roles of the transporters in disease states including metabolic acidosis, hypertension, visual defects, and epileptic seizures. Studies are being conducted to understand the physiological consequences of genetic polymorphisms in the SLC4-members, which are associated with cancer, hypertension, and drug addiction. Here, we describe the current knowledge regarding the function, structure, and regulation of the mammalian cation-coupled HCO3(-) transporters of the SLC4-family.

  6. Specific ion interactions with aromatic rings in aqueous solutions: Comparison of molecular dynamics simulations with a thermodynamic solute partitioning model and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Vincent, Jordan C.; Matt, Sarah M.; Rankin, Blake M.; D'Auria, Raffaella; Freites, J. Alfredo; Ben-Amotz, Dor; Tobias, Douglas J.

    2015-10-01

    Specific ion interactions of KF, and the Na+ salts of SO42-, F-, Cl-, NO3-, I-, and ClO4- with benzene in aqueous solutions were investigated using molecular dynamics simulations and compared with experimental Raman multivariate curve resolution (Raman-MCR) and thermodynamic results. Good agreement is found with the hydration-shell partition coefficients of salts obtained from the thermodynamic analysis and of halogen anions obtained from the Raman-MCR spectra of benzene and pyridine. Larger discrepancies between the simulation and thermodynamic cation partitioning results point to the influence of counter-ion interaction on cation partitioning.

  7. A brief history of partitions of numbers, partition functions and their modern applications

    NASA Astrophysics Data System (ADS)

    Debnath, Lokenath

    2016-04-01

    'Number rules the universe.' The Pythagoras 'If you wish to forsee the future of mathematics our course is to study the history and present conditions of the science.' Henri Poincaré 'The primary source (Urqell) of all mathematics are integers.' Hermann Minkowski This paper is written to commemorate the centennial anniversary of the Mathematical Association of America. It deals with a short history of different kinds of natural numbers including triangular, square, pentagonal, hexagonal and k-gonal numbers, and their simple properties and their geometrical representations. Included are Euclid's and Pythagorean's main contributions to elementary number theory with the main contents of the Euclid Elements of the 13-volume masterpiece of mathematical work. This is followed by Euler's new discovery of the additive number theory based on partitions of numbers. Special attention is given to many examples, Euler's theorems on partitions of numbers with geometrical representations of Ferrers' graphs, Young's diagrams, Lagrange's four-square theorem and the celebrated Waring problem. Included are Euler's generating functions for the partitions of numbers, Euler's pentagonal number theorem, Gauss' triangular and square number theorems and the Jacobi triple product identity. Applications of the theory of partitions of numbers to different statistics such as the Bose- Einstein, Fermi- Dirac, Gentile, and Maxwell- Boltzmann statistics are briefly discussed. Special attention is given to pedagogical information through historical approach to number theory so that students and teachers at the school, college and university levels can become familiar with the basic concepts of partitions of numbers, partition functions and their modern applications, and can pursue advanced study and research in analytical and computational number theory.

  8. Cationically polymerizable monomers derived from renewable sources

    SciTech Connect

    Crivello, J.V.

    1992-10-01

    The objectives of this project are to design and synthesize novel monomers which orginate from renewable biological sources and to carry out their rapid, efficient, pollution-free and energy efficient cationic polymerization to useful products under the influence of ultraviolet light or heat. A summary of the results of the past year's research on cationically polymerizable monomers derived from renewable sources is presented. Three major areas of investigation corresponding to the different classes of naturally occurring starting materials were investigated; epoxidized terpenes and natural rubber and vinyl ethers from alcohols and carbohydrates.

  9. Optimization of a cationic dye removal by a chemically modified agriculture by-product using response surface methodology: biomasses characterization and adsorption properties.

    PubMed

    Azzaz, Ahmed Amine; Jellali, Salah; Akrout, Hanene; Assadi, Aymen Amine; Bousselmi, Latifa

    2016-10-10

    The present study investigates the alkaline modification of raw orange tree sawdust (ROS) for an optimal removal of methylene blue (MB), as a cationic dye model, from synthetic solutions. The effects of operating parameters, namely, sodium hydroxide (NaOH) concentrations, ROS doses in NaOH solutions, stirring times, and initial MB concentrations on dye removal efficiency, were followed in batch mode. The process optimization was performed through the response surface methodology approach (RSM) by using Minitab17 software. The results showed that the order of importance of the followed parameters was NaOH treatment concentrations > stirring times > initial MB concentrations > ROS doses in NaOH solutions. The optimal experimental conditions ensuring the maximal MB removal efficiency was found for a NaOH treatment concentration of 0.14 M, a stirring time of 1 h, a ROS dose in NaOH solutions of 50 g L(-1), and an initial MB concentration of 69.5 mg L(-1). Specific analyses of the raw and alkali-treated biomasses, e.g., SEM/EDS and XRD analyses, demonstrated an important modification of the crystalline structure of the wooden material and a significant increase in its surface basic functional groups. Kinetic and isotherm studies of MB removal from synthetic solutions by ROS and the alkali-treated material (ATOS) showed that for both adsorbents, the pseudo-second-order and Langmuir model fitted the best the experimental data, respectively, which indicates that MB removal might be mainly a chemical and a monolayer process. Furthermore, thanks to the chemical modification of the ROS, the MB maximal uptake capacity has increased from about 39.7 to 78.7 mg g(-1). On the other hand, due to the competition phenomenon, the coexistence of MB and Zn(II) ions could significantly decrease the MB removal efficiency. A maximal decrease of about 32 % was registered for an initial Zn(II) concentration of 140 mg L(-1). Desorption experiments undertaken at natural pH (without

  10. Incentives for partitioning, revisited

    SciTech Connect

    Cloninger, M.O.

    1980-03-24

    The incentives for separating and eliminating various elements from radioactive waste prior to final geologic disposal were investigated. Exposure pathways to humans were defined, and potential radiation doses to an individual living within the region of influence of the underground storage site were calculated. The assumed radionuclide source was 1/5 of the accumulated high-level waste from the US nuclear power economy through the year 2000. The repository containing the waste was assumed to be located in a reference salt site geology. The study required numerous assumptions concerning the transport of radioactivity from the geologic storage site to man. The assumptions used maximized the estimated potential radiation doses, particularly in the case of the intrusion water well scenario, where hydrologic flow field dispersion effects were ignored. Thus, incentives for removing elements from the waste tended to be maximized. Incentives were also maximized by assuming that elements removed from the waste could be eliminated from the earth without risk. The results of the study indicate that for reasonable disposal conditions, incentives for partitioning any elements from the waste in order to minimize the risk to humans are marginal at best.

  11. Adsorption of reovirus to clay minerals: effects of cation-exchange capacity, cation saturation, and surface area.

    PubMed Central

    Lipson, S M; Stotzky, G

    1983-01-01

    The adsorption of reovirus to clay minerals has been reported by several investigators, but the mechanisms defining this association have been studied only minimally. The purpose of this investigation was to elucidate the mechanisms involved with this interaction. More reovirus type 3 was adsorbed, in both distilled and synthetic estuarine water, by low concentrations of montmorillonite than by comparable concentrations of kaolinite containing a mixed complement of cations on the exchange complex. Adsorption to the clays was essentially immediate and was correlated with the cation-exchange capacity of the clays, indicating that adsorption was primarily to negatively charged sites on the clays. Adsorption was greater with low concentrations of clays in estuarine water than in distilled water, as the higher ionic strength of the estuarine water reduced the electrokinetic potential of both clay and virus particles. The addition of cations (as chloride salts) to distilled water enhanced adsorption, with divalent cations being more effective than monovalent cations and 10(-2) M resulting in more adsorption than 10(-3) M. Potassium ions suppressed reovirus adsorption to montmorillonite, probably by collapsing the clay lattices and preventing the expression of the interlayer-derived cation-exchange capacity. More virus was adsorbed by montmorillonite made homoionic to various mono-, di-, and trivalent cations (except by montmorillonite homoionic to potassium) than by comparable concentrations of kaolinite homoionic to the same cations. The sequence of the amount of adsorption to homoionic montmorillonite was Al greater than Ca greater than Mg greater than Na greater than K; the sequence of adsorption to kaolinite was Na greater than Al greater than Ca greater than Mg greater than K. The constant partition-type adsorption isotherms obtained when the clay concentration was maintained constant and the virus concentration was varied indicated that a fixed proportion of the

  12. Cation Transport in Escherichia coli

    PubMed Central

    Schultz, Stanley G.; Solomon, A. K.

    1961-01-01

    Methods have been developed to study the intracellular Na and K concentrations in E. coli, strain K-12. These intracellular cation concentrations have been shown to be functions of the extracellular cation concentrations and the age of the bacterial culture. During the early logarithmic phase of growth, the intracellular K concentration greatly exceeds that of the external medium, whereas the intracellular Na concentration is lower than that of the growth medium. As the age of the culture increases, the intracellular K concentration falls and the intracellular Na concentration rises, changes which are related to the fall in the pH of the medium and to the accumulation of the products of bacterial metabolism. When stationary phase cells, which are rich in Na and poor in K, are resuspended in fresh growth medium, there is a rapid reaccumulation of K and extrusion of Na. These processes represent oppositely directed net ion movements against concentration gradients, and have been shown to be dependent upon the presence of an intact metabolic energy supply. PMID:13909521

  13. Analysis of trace degradation products (decarboxylated diastereoisomers) of S-adenosylmethionine by electrophoresis in capillaries with cationic coatings (N-methylpolyvinylpyridinium or divalent barium).

    PubMed

    Sebastiano, Roberto; Knob, Radim; Citterio, Attilio; Righetti, Pier Giorgio

    2010-10-01

    Commercial preparations of S-adenosylmethionine (SAM) when analyzed in uncoated capillaries show a minute impurity believed to be decarboxylated (dc) SAM. By using two types of cationic coatings, thus reducing the electro-endo-osmotic flow (EOF), it was possible to separate this impurity into two diastereoisomers of dcSAM. The coatings evaluated for this purpose were: (i) N-methylpolyvinylpyridinium, used under reversed EOF at acidic conditions (pH 4.0) and (ii) deposition of divalent barium at alkaline pH values (pH 9.4), providing reduced EOF. Under these conditions, it was possible to separate this impurity into two diastereoisomers, which by chemical synthesis were indeed proven to be dcSAM. It was further demonstrated that, in the alkylation of 5'-methylthioadenosine by 3-bromopropylamine in bromidric acid to dcSAM, another minute impurity was present, proven, via mass spectrometry, to consist of S-(5'-adenosyl)-3-thiopropylamine (decarboxylated and demethylated (dc-SAH)). The LOD for the two dcSAM diastereoisomers was assessed as 17.5 μg/mL and their LOQ as 25.5 μg/mL. By the barium-based protocol it was possible to quantify the dcSAM, present in a commercial sample of SAM, as a 0.1% impurity.

  14. Mechanism of rate enhancement of wood fiber saccharification by cationic polyelectrolytes.

    PubMed

    Mora, Sandeep; Lu, Jian; Banerjee, Sujit

    2011-09-01

    Cationic polyelectrolytes can increase the cellulase-induced hydrolysis rates of bleached wood fiber. We show that the polymer associates mainly with the amorphous region of fiber and acts principally on endoglucanase. Fiber/water partitioning of the enzyme follows a Langmuir isotherm for the untreated fiber but a Freundlich isotherm is obeyed for the polymer-treated fiber.

  15. Charge balancing of trivalent trace elements in olivine and low-Ca pyroxene - A test using experimental partitioning data

    NASA Technical Reports Server (NTRS)

    Colson, R. O.; Taylor, L. A.; Mckay, G. A.

    1989-01-01

    Charge-balancing substitution mechanisms are determined for the incorporation of the trivalent cations Al and Sc in low-Ca pyroxene and Al, Sc, Yb, and Cr in olivine. In low-Ca pyroxene, the substitution mechanism is determined by evaluating covariations of trivalent trace cations with Si, Mg, Fe, and Ca. In olivine, substitution mechanisms are determined by comparing the observed compositional dependence of partitioning to the compositional dependence theoretically expected for each substitution reaction. A realistic equilibrium constant is formulated for trace element exchanges between olivines, low-Ca pyroxenes, and melt, making possible improved modeling of the variations of trace element partitioning with temperature and phase composition.

  16. Eaton's reagent-mediated domino π-cationic arylations of aromatic carboxylic acids to Iasi-red polymethoxylated polycyclic aromatic hydrocarbons: products with unprecedented biological activities as tubulin polymerization inhibitors.

    PubMed

    Ghinet, Alina; Gautret, Philippe; Hijfte, Nathalie Van; Ledé, Bertrand; Hénichart, Jean-Pierre; Bîcu, Elena; Darbost, Ulrich; Rigo, Benoît; Daïch, Adam

    2014-08-04

    A rapid domino π-cationic arylation of aromatic carboxylic acids, mediated by Eaton's reagent, has been developed for the synthesis of Iasi-red polymethoxylated polycyclic aromatic hydrocarbons (PAHs). This route is currently the easiest method to obtain such popular PAH compounds, which bear in addition numerous methoxy groups. The domino process was generalized, the structure of the obtained red products and the mechanism of their formations were elucidated, and some of their photophysical properties were determined. Newly synthesized polymethoxylated-PAHs were tested for their interaction with tubulin polymerization as well as for their cytotoxicity on a panel of NCI-60 human cancer cell lines. Interestingly, one of these rubicene derivatives exhibited remarkable cytotoxicity in vitro, including inhibition of leukemia, colon, melanoma, CNS, and ovarian cancer cell lines with GI50 values in the low nanomolar range (GI50 < 10 nM). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Chemiluminescent reactions of manganese with fluorine: Influence of dynamics on product energy partitioning in vibration and rotation of MnF*(b,c).

    PubMed

    Green, Karen M; Parson, John M

    2004-12-15

    Chemiluminescent exit channels of Mn+F2-->MnF*+F were investigated using the molecular beam technique in a beam-gas configuration with an array detector. Two uncongested regions, corresponding to MnF transitions c5Sigma+(b)-a5Sigma+(b) and b5Pi(i)(int)-a5Sigma+(b) were fit for vibrational and rotational populations, which were used to develop a microscopic reaction mechanism for these chemiluminescent exit channels. In both MnF* electronic states, significant vibrational excitation but little rotational excitation was found. Significant vibrational excitation has been attributed to early energy release as Mn loses an electron at long range to the lowest unoccupied molecular orbital on F2. The incipient bond is strengthened as backbonding from the F2- to Mn+ increases the covalent character of the intermediate. Finally, no strict geometric constraints are placed on the exit channel and hence there is no significant repulsive energy release into product rotation. Our proposed mechanism exhibits dynamic control in that the course of the reaction is determined by both geometric factors and dynamic factors.

  18. The partitioning of trace elements during pulverized coal combustion

    NASA Astrophysics Data System (ADS)

    Seames, Wayne Stewart

    The environmental impact resulting from the release of trace elements during coal combustion is an important issue for the coal-fired electric utility industry. Trace elements exit the combustor by partitioning between the flue gas and the fly ash particles. A comprehensive study has been conducted to investigate the mechanisms governing the partitioning of trace elements during pulverized coal combustion. The behavior of seven trace elements (arsenic, selenium, antimony, cobalt, cesium, thorium, and cerium) in six pulverized coals were studied under commercially relevant conditions in a well-described laboratory combustion environment. The partitioning of trace elements is governed by the extent of volatilization during combustion, the form of occurrence in the flue gas, and the mechanisms controlling vapor-to-solid phase transformation to fly ash particle surfaces. The most common vapor-to-solid phase partitioning mechanism for semi-volatile trace elements is reaction with active fly ash surfaces. Trace elements that form oxy-anions upon volatilization (e.g. arsenic, selenium, antimony) will react with active calcium and iron cation fly ash surface sites. Trace elements that form simple oxides upon volatilization (e.g. cobalt, cesium) will react with active aluminum oxy-anion fly ash surface sites. The maximum combustion temperature affects the availability of active calcium and iron surface sites but not aluminum sites. Sulfur inhibits the reactivity of oxy-anions with iron surface sites. For coals with high sulfur contents (>1 wt % as SO 2), volatilized trace elements that form oxy-anions will partition by reaction with calcium surface sites if sufficient sites are available. For coals with low sulfur contents, volatilized trace elements that form oxy-anions, will partition by reaction with iron surface sites. Volatilized trace elements that form oxy-anions will not partition by reaction if the coal sulfur content is high and the calcium content is low (<3 wt

  19. Degradation of the anticancer drug erlotinib during water chlorination: Non-targeted approach for the identification of transformation products.

    PubMed

    Negreira, Noelia; Regueiro, Jorge; López de Alda, Miren; Barceló, Damià

    2015-11-15

    Erlotinib is a highly potent tyrosine kinase inhibitor used in the treatment of the most common type of lung cancer. Due to its recent introduction, very scarce information is available on its occurrence, environmental fate and toxicological effects on aquatic organisms. During chlorination processes normally carried out in wastewater treatment plants and in the pretreatment of hospital effluents, chlorinated transformation products can be formed with an enhanced toxicity relative to the parent compound. Thus, the reactivity of the cytostatic drug erlotinib in free chlorine-containing water was investigated for the first time in the present work. A non-targeted screening approach based on the use of differential profiling tools was applied in order to reveal its potential transformation products. Structural elucidation of the detected transformation products was performed by ultra-performance liquid chromatography coupled to high-resolution hybrid quadrupole-Orbitrap tandem mass spectrometry. The proposed approach allowed detecting a total of nineteen transformation products, being eighteen of them described for the first time in this work, which demonstrates its potential in environmental analysis. Among them, six compounds presented chlorine atoms in their structures, which may be of major concern. Other transformation products involved hydroxylation and oxidation reactions. Time-course profiles of erlotinib and its transformation products were followed in real wastewater samples under conditions that simulate wastewater disinfection. Although the structures of these transformation products could not be positively confirmed due to lack of standards, their chemical formulas and product ions can be added to databases, which will allow their screening in future monitoring studies.

  20. Cation diffusion in titanomagnetites

    NASA Astrophysics Data System (ADS)

    Aragon, R.; McCallister, R. H.; Harrison, H. R.

    1984-02-01

    Interdiffusion couple experiments were performed with titanomagnetite single crystals at 1,000°C, 1,100° C and 1,200° C in various buffered atmospheres. The dependence of the interdiffusion coefficient on oxygen fugacity, composition and temperature was interpreted in terms of point defect structure. Estimates of the cation tracer diffusivities indicate that Fe migrates via a point defect mechanism, involving mixed tetrahedral-octahedral site jumps, with an activation energy of 33 Kcal/mole; whereas Ti migration is one to two orders of magnitude slower, is restricted to octahedral sites and has an activation energy of 60 Kcal/mole.

  1. Dissecting the cation-cation interaction between two uranyl units.

    PubMed

    Tecmer, Paweł; Hong, Sung W; Boguslawski, Katharina

    2016-07-21

    We present a state-of-the-art computational study of the uranyl(vi) and uranyl(v) cation-cation interactions (dications) in aqueous solution. Reliable electronic structures of two interacting uranyl(vi) and uranyl(v) subunits as well as those of the uranyl(vi) and uranyl(v) clusters are presented for the first time. Our theoretical study elucidates the impact of cation-cation interactions on changes in the molecular structure as well as changes in vibrational and UV-Vis spectra of the bare uranyl(vi) and uranyl(v) moieties for different total spin-states and total charges of the dications.

  2. Adaptive density partitioning technique in the auxiliary plane wave method

    NASA Astrophysics Data System (ADS)

    Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

    2006-01-01

    We have developed the adaptive density partitioning technique (ADPT) in the auxiliary plane wave method, in which a part of the density is expanded to plane waves, for the fast evaluation of Coulomb matrix. Our partitioning is based on the error estimations and allows us to control the accuracy and efficiency. Moreover, we can drastically reduce the core Gaussian products that are left in Gaussian representation (its analytical integrals is the bottleneck in this method). For the taxol molecule with 6-31G** basis, the core Gaussian products accounted only for 5% in submicrohartree error.

  3. Interactions of melatonin and its metabolites with the ABTS cation radical: extension of the radical scavenger cascade and formation of a novel class of oxidation products, C2-substituted 3-indolinones.

    PubMed

    Rosen, Joachim; Than, Ni Ni; Koch, Dorothea; Poeggeler, Burkhard; Laatsch, Hartmut; Hardeland, Rüdiger

    2006-11-01

    Melatonin had previously been shown to reduce up to four 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) cation radicals (ABTS*+) via a scavenger cascade ending with N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK). However, when melatonin is added to the reaction system in much lower quantities than ABTS*+, the number of radicals scavenged per melatonin molecule is considerably higher and can attain a value of ten. Under conditions allowing for such a stoichiometry, novel products have been detected which derive from AFMK (1). These were separated by repeated chromatography and the major compounds were characterized by spectroscopic methods, such as mass spectrometry (HPLC-MS, EI-MS and ESI-HRMS), 1H nuclear magnetic resonance (NMR) and 13C NMR, heteronuclear multiple bond connectivity (HMBC) correlations. The identified substances are formed by re-cyclization and represent 3-indolinones carrying the side chain at C2; the N-formyl group can be maintained, but deformylated analogs seem to be also generated, according to MS. The primary product from AFMK (1) is N-(1-formyl-5-methoxy-3-oxo-2,3-dihydro-1H-indol-2-ylidenemethyl)-acetamide (2), which is obtained after purification as E- and Z-isomers (2a, 2b); a secondary product has been identified as N-(1-formyl-2-hydroxy-5-methoxy-3-oxo-2,3-dihydro-1H-indol-2-ylmethyl)-acetamide (3). When H2O2 is added to the ABTS*+ reaction mixture in quantities not already leading to substantial reduction of this radical, compound 3 is isolated as the major product, whereas 2a and 2b are virtually absent. The substances formed differ from all previously known oxidation products which derive from melatonin and are, among these, the first 3-indolinones. Moreover, the aliphatic side chain at C2 is reminiscent of other substances which have been synthesized in the search for melatonin receptor ligands.

  4. The pi-Cation Radical of Chlorophyll a.

    PubMed

    Borg, D C; Fajer, J; Felton, R H; Dolphin, D

    1970-10-01

    Chlorophyll a undergoes reversible one-electron oxidation in dichloromethane and butyronitrile. Removal of the electron by controlled potential electrolysis or by stoichiometric charge transfer to a known cation radical yields a radical (epr line width = 9 gauss, g = 2.0025 +/- 0.0001) whose optical spectrum is bleached relative to that of chlorophyll. Upon electrophoresis this bleached species behaves as a cation. By comparison with the known properties of pi-cation radicals of porphyrins and chlorins, the chlorophyll radical is also identified as a pi-cation. Further correlation of optical and epr properties with published studies on photosynthesis leads to the conclusion that oxidized P700, the first photochemical product of photosystem I in green plants, contains a pi-cation radical of the chlorin component of chlorophyll a. This radical is the likely source of the rapidly-decaying, narrow epr signal of photosynthesis.

  5. Self-Amplified Surface Charging and Partitioning of Ionic Liquids in Nanopores

    NASA Astrophysics Data System (ADS)

    Neal, Justin N.; Van Aken, K. L.; Gogotsi, Y.; Wesolowski, David J.; Wu, Jianzhong

    2017-09-01

    We study ion partitioning and self-charging of nanoporous electrodes with room-temperature ionic liquids using a classical density-functional theory that accounts for molecular-excluded volume effects and electrostatic correlations. Nanopores of zero electrical potential are predicted to favor adsorption of small ions even without specific surface attraction, and the imbalanced distributions of cations and anions inside the pore induces a net surface charge that promotes further enrichment of small ions. The self-amplified ion partitioning is most significant when the nanopore and the ionic species are of comparable dimension.

  6. Evolving bipartite authentication graph partitions

    DOE PAGES

    Pope, Aaron Scott; Tauritz, Daniel Remy; Kent, Alexander D.

    2017-01-16

    As large scale enterprise computer networks become more ubiquitous, finding the appropriate balance between user convenience and user access control is an increasingly challenging proposition. Suboptimal partitioning of users’ access and available services contributes to the vulnerability of enterprise networks. Previous edge-cut partitioning methods unduly restrict users’ access to network resources. This paper introduces a novel method of network partitioning superior to the current state-of-the-art which minimizes user impact by providing alternate avenues for access that reduce vulnerability. Networks are modeled as bipartite authentication access graphs and a multi-objective evolutionary algorithm is used to simultaneously minimize the size of largemore » connected components while minimizing overall restrictions on network users. Lastly, results are presented on a real world data set that demonstrate the effectiveness of the introduced method compared to previous naive methods.« less

  7. Temporal Partitioning on Multicore Platform

    NASA Astrophysics Data System (ADS)

    Mahmud Pathan, Ristat; Hashi, Feysal; Stenstrom, Per; Green, Lars-Goran; Hult, Torbjorn; Sandin, Patrik

    2014-08-01

    This paper addresses the problem of ensuring temporal partitioning according to the ARINC-653 standard for integrating multiple applications on the same multicore platform. To employ temporal partitioning, we propose the design and analysis of a hierarchical scheduling framework (HSF) for multicore platform. In HSF, each application has a server task, which is mapped to one of the physical cores of the multicore platform. The HSF framework is based on scheduling at two-levels: (i) a system-level scheduler for each core schedules the server tasks that are mapped to that core, and (ii) a task- level scheduler for each application schedules the tasks of the application. This paper presents the design and analysis of this two-level HSF that can be used to ensure temporal partitioning and meeting all the deadlines of each application tasks. The effectiveness of our technique is demonstrated using real-world space applications provided by RUAG Space Sweden AB.

  8. Partitioned aquaculture systems

    USDA-ARS?s Scientific Manuscript database

    Conventional aquaculture ponds provide a number of ecological services supporting fish and shellfish production. The pond provides confinement space for the aquatic organisms, while algal growth in the pond serves as the base of an aquatic food chain providing some or all of the feed, depending on p...

  9. Partitioned pond aquaculture systems

    USDA-ARS?s Scientific Manuscript database

    World aquaculture is dominated by the use of simple earthen ponds in which suitable water quality is maintained by photosynthetic processes. Relying upon sunlight to maintain water quality offers the lowest cost and most sustainable approach to fish or shellfish production, which explains the popula...

  10. Asymptotic prime partitions of integers

    NASA Astrophysics Data System (ADS)

    Bartel, Johann; Bhaduri, R. K.; Brack, Matthias; Murthy, M. V. N.

    2017-05-01

    In this paper, we discuss P (n ) , the number of ways a given integer n may be written as a sum of primes. In particular, an asymptotic form Pas(n ) valid for n →∞ is obtained analytically using standard techniques of quantum statistical mechanics. First, the bosonic partition function of primes, or the generating function of unrestricted prime partitions in number theory, is constructed. Next, the density of states is obtained using the saddle-point method for Laplace inversion of the partition function in the limit of large n . This gives directly the asymptotic number of prime partitions Pas(n ) . The leading term in the asymptotic expression grows exponentially as √{n /ln(n ) } and agrees with previous estimates. We calculate the next-to-leading-order term in the exponent, proportional to ln[ln(n )]/ln(n ) , and we show that an earlier result in the literature for its coefficient is incorrect. Furthermore, we also calculate the next higher-order correction, proportional to 1 /ln(n ) and given in Eq. (43), which so far has not been available in the literature. Finally, we compare our analytical results with the exact numerical values of P (n ) up to n ˜8 ×106 . For the highest values, the remaining error between the exact P (n ) and our Pas(n ) is only about half of that obtained with the leading-order approximation. But we also show that, unlike for other types of partitions, the asymptotic limit for the prime partitions is still quite far from being reached even for n ˜107 .

  11. Genuine N -partite entanglement without N -partite correlation functions

    NASA Astrophysics Data System (ADS)

    Tran, Minh Cong; Zuppardo, Margherita; de Rosier, Anna; Knips, Lukas; Laskowski, Wiesław; Paterek, Tomasz; Weinfurter, Harald

    2017-06-01

    A genuinely N -partite entangled state may display vanishing N -partite correlations measured for arbitrary local observables. In such states the genuine entanglement is noticeable solely in correlations between subsets of particles. A straightforward way to obtain such states for odd N is to design an "antistate" in which all correlations between an odd number of observers are exactly opposite. Evenly mixing a state with its antistate then produces a mixed state with no N -partite correlations, with many of them genuinely multiparty entangled. Intriguingly, all known examples of "entanglement without correlations" involve an odd number of particles. Here we further develop the idea of antistates, thereby shedding light on the different properties of even and odd particle systems. We conjecture that there is no antistate to any pure even-N -party entangled state making the simple construction scheme unfeasible. However, as we prove by construction, higher-rank examples of entanglement without correlations for arbitrary even N indeed exist. These classes of states exhibit genuine entanglement and even violate an N -partite Bell inequality, clearly demonstrating the nonclassical features of these states as well as showing their applicability for quantum information processing.

  12. Fragmentation Pathways in the Uracil Radical Cation

    SciTech Connect

    Zhou, Congyi; Matsika, Spiridoula; Kotur, Marija; Weinacht, Thomas C.

    2012-08-24

    We investigate pathways for fragmentation in the uracil radical cation using ab initio electronic structure calculations. We focus on the main fragments produced in pump–probe dissociative ionization experiments. These are fragments with mass to charge ratios (m/z) of 69, 28, 41, and 42. Barriers to dissociation along the ground ionic surface are reported, which provide an estimate of the energetic requirements for the production of the main fragments. Finally, direct and sequential fragmentation mechanisms have been analyzed, and it is concluded that sequential fragmentation after production of fragment with m/z 69 is the dominant mechanism for the production of the smaller fragments.

  13. Sn Cation Valency Dependence in Cation Exchange Reactions Involving Cu2-xSe Nanocrystals

    PubMed Central

    2014-01-01

    We studied cation exchange reactions in colloidal Cu2-xSe nanocrystals (NCs) involving the replacement of Cu+ cations with either Sn2+ or Sn4+ cations. This is a model system in several aspects: first, the +2 and +4 oxidation states for tin are relatively stable; in addition, the phase of the Cu2-xSe NCs remains cubic regardless of the degree of copper deficiency (that is, “x”) in the NC lattice. Also, Sn4+ ions are comparable in size to the Cu+ ions, while Sn2+ ones are much larger. We show here that the valency of the entering Sn ions dictates the structure and composition not only of the final products but also of the intermediate steps of the exchange. When Sn4+ cations are used, alloyed Cu2–4ySnySe NCs (with y ≤ 0.33) are formed as intermediates, with almost no distortion of the anion framework, apart from a small contraction. In this exchange reaction the final stoichiometry of the NCs cannot go beyond Cu0.66Sn0.33Se (that is Cu2SnSe3), as any further replacement of Cu+ cations with Sn4+ cations would require a drastic reorganization of the anion framework, which is not possible at the reaction conditions of the experiments. When instead Sn2+ cations are employed, SnSe NCs are formed, mostly in the orthorhombic phase, with significant, albeit not drastic, distortion of the anion framework. Intermediate steps in this exchange reaction are represented by Janus-type Cu2-xSe/SnSe heterostructures, with no Cu–Sn–Se alloys. PMID:25340627

  14. Sn cation valency dependence in cation exchange reactions involving Cu(2-x)Se nanocrystals.

    PubMed

    De Trizio, Luca; Li, Hongbo; Casu, Alberto; Genovese, Alessandro; Sathya, Ayyappan; Messina, Gabriele C; Manna, Liberato

    2014-11-19

    We studied cation exchange reactions in colloidal Cu(2-x)Se nanocrystals (NCs) involving the replacement of Cu(+) cations with either Sn(2+) or Sn(4+) cations. This is a model system in several aspects: first, the +2 and +4 oxidation states for tin are relatively stable; in addition, the phase of the Cu(2-x)Se NCs remains cubic regardless of the degree of copper deficiency (that is, "x") in the NC lattice. Also, Sn(4+) ions are comparable in size to the Cu(+) ions, while Sn(2+) ones are much larger. We show here that the valency of the entering Sn ions dictates the structure and composition not only of the final products but also of the intermediate steps of the exchange. When Sn(4+) cations are used, alloyed Cu(2-4y)Sn(y)Se NCs (with y ≤ 0.33) are formed as intermediates, with almost no distortion of the anion framework, apart from a small contraction. In this exchange reaction the final stoichiometry of the NCs cannot go beyond Cu0.66Sn0.33Se (that is Cu2SnSe3), as any further replacement of Cu(+) cations with Sn(4+) cations would require a drastic reorganization of the anion framework, which is not possible at the reaction conditions of the experiments. When instead Sn(2+) cations are employed, SnSe NCs are formed, mostly in the orthorhombic phase, with significant, albeit not drastic, distortion of the anion framework. Intermediate steps in this exchange reaction are represented by Janus-type Cu(2-x)Se/SnSe heterostructures, with no Cu-Sn-Se alloys.

  15. Rectilinear partitioning of irregular data parallel computations

    NASA Technical Reports Server (NTRS)

    Nicol, David M.

    1991-01-01

    New mapping algorithms for domain oriented data-parallel computations, where the workload is distributed irregularly throughout the domain, but exhibits localized communication patterns are described. Researchers consider the problem of partitioning the domain for parallel processing in such a way that the workload on the most heavily loaded processor is minimized, subject to the constraint that the partition be perfectly rectilinear. Rectilinear partitions are useful on architectures that have a fast local mesh network. Discussed here is an improved algorithm for finding the optimal partitioning in one dimension, new algorithms for partitioning in two dimensions, and optimal partitioning in three dimensions. The application of these algorithms to real problems are discussed.

  16. Role of the multipolar electrostatic interaction energy components in strong and weak cation-π interactions.

    PubMed

    Kadlubanski, Pawel; Calderón-Mojica, Katherine; Rodriguez, Weyshla A; Majumdar, D; Roszak, Szczepan; Leszczynski, Jerzy

    2013-08-22

    Density functional and Møller-Plesset second-order perturbation (MP2) calculations have been carried out on various model cation-π complexes formed through the interactions of Mg(2+), Ca(2+), and NH4(+) cations with benzene, p-methylphenol, and 3-methylindole. Partial hydration of the metal cations was also considered in these model studies to monitor the effect of hydration of cations in cation-π interactions. The binding energies of these complexes were computed from the fully optimized structures using coupled cluster calculations including triple excitations (CCSD(T)) and Gaussian-G4-MP2 (G4MP2) techniques. An analysis of the charge sharing between the donor (the π-systems) and the acceptors (the cations) together with the partitioning of total interaction energies revealed that the strong and weak cation-π interactions have similar electrostatic interaction properties. Further decomposition of such electrostatic terms into their multipolar components showed the importance of the charge-dipole, charge-quadrupole, and charge-octopole terms in shaping the electrostatic forces in such interactions. The computed vibrational spectra of the complexes were analyzed for the specific cation-π interaction modes and have been shown to contain the signature of higher order electrostatic interaction energy components (quadrupole and octopole) in such interactions.

  17. METAL PARTITIONING IN COMBUSTION PROCESSES

    EPA Science Inventory

    This article summarizes ongoing research efforts at the National Risk Management Research Laboratory of the U.S. Environmental Protection Agency examining [high temperature] metal behavior within combustion environments. The partitioning of non-volatile (Cr and Ni), semi-volatil...

  18. METAL PARTITIONING IN COMBUSTION PROCESSES

    EPA Science Inventory

    This article summarizes ongoing research efforts at the National Risk Management Research Laboratory of the U.S. Environmental Protection Agency examining [high temperature] metal behavior within combustion environments. The partitioning of non-volatile (Cr and Ni), semi-volatil...

  19. Understanding Partitive Division of Fractions.

    ERIC Educational Resources Information Center

    Ott, Jack M.; And Others

    1991-01-01

    Concrete experience should be a first step in the development of new abstract concepts and their symbolization. Presents concrete activities based on Hyde and Nelson's work with egg cartons and Steiner's work with money to develop students' understanding of partitive division when using fractions. (MDH)

  20. Understanding Partitive Division of Fractions.

    ERIC Educational Resources Information Center

    Ott, Jack M.; And Others

    1991-01-01

    Concrete experience should be a first step in the development of new abstract concepts and their symbolization. Presents concrete activities based on Hyde and Nelson's work with egg cartons and Steiner's work with money to develop students' understanding of partitive division when using fractions. (MDH)

  1. Stabilities and partitioning of arenonium ions in aqueous media.

    PubMed

    Lawlor, D A; More O'Ferrall, R A; Rao, S N

    2008-12-31

    The phenathrenonium ion is formed as a reactive intermediate in the solvolysis of 9-dichloroacetoxy-9,10-dihydrophenanthrene in aqueous acetonitrile and undergoes competing reactions with water acting as a base and nucleophile. Measurements of product ratios in the presence of azide ion as a trap and 'clock' yield rate constants kp = 3.7 x 10(10) and kH2O = 1.5 x 10(8) s(-1), respectively. Combining these with rate constants for the reverse reactions (protonation of phenanthrene and acid-catalyzed aromatization of its water adduct) gives equilibrium constants pKa = -20.9 and pK(R) = -11.6. For a series of arenonium and benzylic cations, correlation of log kp with pKa, taking account of the limit to kp set by the relaxation of water (10(11) s(-1)), leads to extrapolation of kp = 9.0 x 10(10) s(-1) and pKa = -24.5 for the benzenonium ion and kp = 6.5 x 10(10) s(-1) and pKa = -22.5 for the 1-naphthalenonium ion. Combining these pKa's with estimates of equilibrium constants pKH2O for the hydration of benzene and naphthalene, and the relationship pKR = pKa + pKH2O based on Hess's law, gives pKR = -2.3 and -8.0 respectively, and highlights the inherent stability of the benzenonium ion. A correlation exists between the partitioning ratio, kp/kH2O, for carbocations reacting in water and KH2O the equilibrium constant between the respective reaction products, i.e., log(kp/kH2O) = 0.46pKH2O - 3.7. It implies that kp exceeds kH2O only when KH2O > 10(8). This is consistent with the proton transfer (a) possessing a lower intrinsic reactivity than reaction of the carbocation with water as a nucleophile and (b) being rate-determining in the hydration of alkenes (and dehydration of alcohols) except when the double bond of the alkene is unusually stabilized, as in the case of aromatic molecules.

  2. Antiviral Cationic Peptides as a Strategy for Innovation in Global Health Therapeutics for Dengue Virus: High Yield Production of the Biologically Active Recombinant Plectasin Peptide

    PubMed Central

    Mohamed, Zulqarnain; Suhaeb, Abdulrazzaq M.; Rahman, Noorsaadah Abd; Yusof, Rohana

    2013-01-01

    Abstract Dengue virus infects millions of people worldwide, and there is no vaccine or anti-dengue therapeutic available. Antimicrobial peptides have been shown to possess effective antiviral activity against various viruses. One of the main limitations of developing these peptides as potent antiviral drugs is the high cost of production. In this study, high yield production of biologically active plectasin peptide was inexpensively achieved by producing tandem plectasin peptides as inclusion bodies in E. coli. Antiviral activity of the recombinant peptide towards dengue serotype-2 NS2B-NS3 protease (DENV2 NS2B-NS3pro) was assessed as a target to inhibit dengue virus replication in Vero cells. Single units of recombinant plectasin were collected after applying consecutive steps of refolding, cleaving by Factor Xa, and nickel column purification to obtain recombinant proteins of high purity. The maximal nontoxic dose (MNTD) of the recombinant peptide against Vero cells was 20 μM (100 μg/mL). The reaction velocity of DENV2 NS2B-NS3pro decreased significantly after increasing concentrations of recombinant plectasin were applied to the reaction mixture. Plectasin peptide noncompetitively inhibited DENV2 NS2B-NS3pro at Ki value of 5.03±0.98 μM. The percentage of viral inhibition was more than 80% at the MNTD value of plectasin. In this study, biologically active recombinant plectasin which was able to inhibit dengue protease and viral replication in Vero cells was successfully produced in E. coli in a time- and cost- effective method. These findings are potentially important in the development of potent therapeutics against dengue infection. PMID:24044366

  3. Short-term carbon partitioning fertilizer responses vary among two full-sib loblolly pine clones

    Treesearch

    Jeremy P. Stovall; John R. Seiler; Thomas R. Fox

    2012-01-01

    We investigated the effects of fertilizer application on the partitioning of gross primary productivity (GPP) between contrasting full-sib clones of Pinus taeda (L.). Our objective was to determine if fertilizer growth responses resulted from similar short-term changes to partitioning. A modeling approach incorporating respiratory carbon (C) fluxes,...

  4. Li partitioning in the benthic foraminifera Amphistegina lessonii

    NASA Astrophysics Data System (ADS)

    Langer, Gerald; Sadekov, Aleksey; Thoms, Silke; Mewes, Antje; Nehrke, Gernot; Greaves, Mervyn; Misra, Sambuddha; Bijma, Jelle; Elderfield, Henry

    2015-12-01

    The shallow water benthic foraminifer Amphistegina lessonii was grown in seawater of variable Li and Ca concentration and shell Li/Ca was determined by means of LA-ICPMS. Shell Li/Ca is positively correlated to seawater Li/Ca only when the Li concentration of seawater is changed. If the seawater Ca concentration is changed, shell Li/Ca remains constant. This indicates that Li does not compete with Ca for incorporation in the shell of A. lessonii. A recently proposed calcification model can be applied to divalent cations (e.g., Mg and Sr), which compete for binding sites of ion transporters and positions in the calcite lattice. By contrast, the transport pathway of monovalent cations such as Li is probably diffusion based (e.g., ion-channels), and monovalent cations do not compete with Ca for a position in the calcite lattice. Here we present a new model for Li partitioning into foraminiferal calcite which predicts our experimental results and should also be applicable to other alkali metals.

  5. Evaluation of solubility and partition properties of ampicillin-based ionic liquids.

    PubMed

    Florindo, Catarina; Araújo, João M M; Alves, Filipa; Matos, Carla; Ferraz, Ricardo; Prudêncio, Cristina; Noronha, João Paulo; Petrovski, Željko; Branco, Luís; Rebelo, Luís Paulo N; Marrucho, Isabel M

    2013-11-18

    In order to overcome the problems associated with low water solubility, and consequently low bioavailability of active pharmaceutical ingredients (APIs), herein we explore a modular ionic liquid synthetic strategy for improved APIs. Ionic liquids containing L-ampicillin as active pharmaceutical ingredient anion were prepared using the methodology developed in our previous work, using organic cations selected from substituted ammonium, phosphonium, pyridinium and methylimidazolium salts, with the intent of enhancing the solubility and bioavailability of L-ampicillin forms. In order to evaluate important properties of the synthesized API-ILs, the water solubility at 25 °C and 37 °C (body temperature) as well as octanol-water partition coefficients (Kow's) and HDPC micelles partition at 25 °C were measured. Critical micelle concentrations (CMC's) in water at 25 °C and 37 °C of the pharmaceutical ionic liquids bearing cations with surfactant properties were also determined from ionic conductivity measurements.

  6. Independent Generation and Reactivity of Thymidine Radical Cations.

    PubMed

    Sun, Huabing; Taverna Porro, Marisa L; Greenberg, Marc M

    2017-10-10

    Thymidine radical cation (1) is produced by ionizing radiation and has been invoked as an intermediate in electron transfer in DNA. Previous studies on its structure and reactivity have utilized thymidine as a precursor, which limits quantitative product analysis because thymidine is readily reformed from 1. In this investigation, radical cation 1 is independently generated via β-heterolysis of a pyrimidine radical generated photochemically from an aryl sulfide. Thymidine is the major product (33%) from 1 at pH 7.2. Diastereomeric mixtures of thymidine glycol and the corresponding 5-hydroxperoxides resulting from water trapping of 1 are formed. Significantly lower yields of products such as 5-formyl-2'-deoxyuridine that are ascribable to deprotonation from the C5-methyl group of 1 are observed. Independent generation of the N3-methyl analogue of 1 (NMe-1) produces considerably higher yields of products derived from water trapping, and these products are formed in much higher yields than those attributable to the C5-methyl group deprotonation in NMe-1. N3-Methyl-thymidine is, however, the major product and is produced in as high as 70% yield when the radical cation is produced in the presence of excess thiol. The effects of exogenous reagents on product distributions are consistent with the formation of diffusively free radical cations (1, NMe-1). This method should be compatible with producing radical cations at defined positions within DNA.

  7. Some trees with partition dimension three

    NASA Astrophysics Data System (ADS)

    Fredlina, Ketut Queena; Baskoro, Edy Tri

    2016-02-01

    The concept of partition dimension of a graph was introduced by Chartrand, E. Salehi and P. Zhang (1998) [2]. Let G(V, E) be a connected graph. For S ⊆ V (G) and v ∈ V (G), define the distance d(v, S) from v to S is min{d(v, x)|x ∈ S}. Let Π be an ordered partition of V (G) and Π = {S1, S2, ..., Sk }. The representation r(v|Π) of vertex v with respect to Π is (d(v, S1), d(v, S2), ..., d(v, Sk)). If the representations of all vertices are distinct, then the partition Π is called a resolving partition of G. The partition dimension of G is the minimum k such that G has a resolving partition with k partition classes. In this paper, we characterize some classes of trees with partition dimension three, namely olive trees, weeds, and centipedes.

  8. Use of the "partition" test in behavioral and pharmacological experiments.

    PubMed

    Kudryavtseva, N N

    2003-06-01

    he characteristics and potential applications of a test assessing animals' behavioral responses to another individual placed in the neighboring sector of the cage, divided in half by a transparent partition with holes, are discussed. The animals' behavioral responses differed depending on the physiological and psychological state of an individual, its social experience, type of partner in the neighboring sector, and line. The "partition" test can be informative and productive in experiments designed to study the neurochemical and neurophysiological mechanisms of sociability, anxiety, olfaction, aggressive and sexual behavior, and in experiments addressing the psychotropic properties of agents.

  9. The effects of organic impurities on the partitioning of iodine

    SciTech Connect

    Lutz, J.B.; Kelly, J.L.

    1988-03-01

    The effects of four common organic species (methanol, phenoxide, acetone, and methane) on the partitioning of iodine were studied over a range of concentrations, pHs, and radiation dose rates at --20/sup 0/C. The primary goal of the study was to identify conditions leading to the production of significant quantities of volatile organic iodides. For all of the conditions studied, only the case of irradiated methane-iodine-air-water systems yielded sufficient volatile organic iodides to bring about decreases in the iodine partition coefficient.

  10. On the Analysis of Partitioned Data.

    ERIC Educational Resources Information Center

    Pruzek, Robert M.; And Others

    A description is given of a general method for studying partitions. The main focus is with the analysis of relationships among several different partitions of the same items for the explorations as well as confirmation of structural relationships. A partition is defined as a set of mutually exclusive clusters of items; however, this paper deals…

  11. ESTimating plant phylogeny: lessons from partitioning

    PubMed Central

    de la Torre, Jose EB; Egan, Mary G; Katari, Manpreet S; Brenner, Eric D; Stevenson, Dennis W; Coruzzi, Gloria M; DeSalle, Rob

    2006-01-01

    addition, approaches that examine conflict and support in a simultaneous analysis framework allow for a more precise understanding of the evolutionary history of individual process partitions and may be a novel way to understand functional aspects of different kinds of cellular classes of gene products. PMID:16776834

  12. First experimentally determined thermodynamic values of francium: hydration energy, energy of partitioning, and thermodynamic radius.

    PubMed

    Delmau, Lætitia H; Moine, Jérôme; Mirzadeh, Saed; Moyer, Bruce A

    2013-08-08

    The Gibbs energy of partitioning of Fr(+) ion between water and nitrobenzene has been determined to be 14.5 ± 0.6 kJ/mol at 25 °C, the first ever Gibbs energy of partitioning for francium in particular and the first ever solution thermodynamic quantity for francium in general. This value enabled the ionic radius and standard Gibbs energy of hydration for Fr(+) to be estimated as 173 pm and -251 kJ/mol, respectively, the former value being significantly smaller than previously thought. A new experimental method was established using a cesium dicarbollide as a cation-exchange agent, overcoming problems inherent to the trace-level concentrations of francium. The methodology opens the door to the study of the partitioning behavior of francium to other water-immiscible solvents and the determination of complexation constants for francium binding by receptor molecules.

  13. The Cation-π Interaction

    PubMed Central

    DOUGHERTY, DENNIS A.

    2014-01-01

    CONSPECTUS The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author’s perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forgo aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction – Li+ binds to benzene with 38 kcal/mol of binding energy; NH4+ with 19 kcal/mol– distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2 – 5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) Cδ−–Hδ+ bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li+>Na+>K+>Rb+: as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane

  14. Partitioning of acidic, basic and neutral amino acids into imidazolium-based ionic liquids.

    PubMed

    Absalan, Ghodratollah; Akhond, Morteza; Sheikhian, Leila

    2010-06-01

    In this paper, partitioning behaviors of typical neutral (Alanine), acidic (Glutamic acid) and basic (Lysine) amino acids into imidazolium-based ionic liquids [C(4)mim][PF(6)], [C(6)mim][PF(6)], [C(8)mim][PF(6)], [C(6)mim][BF(4)] and [C(8)mim][BF(4)] as extracting solvents were examined. [C(6)mim][BF(4)] showed the best efficiency for partitioning of amino acids. The partition coefficients of amino acids in ionic liquids were found to depend strongly on pH of the aqueous solution, amino acid and ionic liquid chemical structures. Different chemical forms of amino acids in aqueous solutions were pH dependent, so the pH value of the aqueous phase was a determining factor for extraction of amino acids into ionic liquid phase. Both water content of ionic liquids and charge densities of their anionic and cationic parts were important factors for partitioning of cationic and anionic forms of amino acids into ionic liquid phase. Extracted amino acids were back extracted into phosphate buffer solutions adjusted on appropriate pH values. The results showed that ionic liquids could be used as suitable modifiers on the stationary phase of an HPLC column for efficient separation of acidic, basic, and neutral amino acids.

  15. Partitioning sparse rectangular matrices for parallel processing

    SciTech Connect

    Kolda, T.G.

    1998-05-01

    The authors are interested in partitioning sparse rectangular matrices for parallel processing. The partitioning problem has been well-studied in the square symmetric case, but the rectangular problem has received very little attention. They will formalize the rectangular matrix partitioning problem and discuss several methods for solving it. They will extend the spectral partitioning method for symmetric matrices to the rectangular case and compare this method to three new methods -- the alternating partitioning method and two hybrid methods. The hybrid methods will be shown to be best.

  16. Spectral partitioning in equitable graphs

    NASA Astrophysics Data System (ADS)

    Barucca, Paolo

    2017-06-01

    Graph partitioning problems emerge in a wide variety of complex systems, ranging from biology to finance, but can be rigorously analyzed and solved only for a few graph ensembles. Here, an ensemble of equitable graphs, i.e., random graphs with a block-regular structure, is studied, for which analytical results can be obtained. In particular, the spectral density of this ensemble is computed exactly for a modular and bipartite structure. Kesten-McKay's law for random regular graphs is found analytically to apply also for modular and bipartite structures when blocks are homogeneous. An exact solution to graph partitioning for two equal-sized communities is proposed and verified numerically, and a conjecture on the absence of an efficient recovery detectability transition in equitable graphs is suggested. A final discussion summarizes results and outlines their relevance for the solution of graph partitioning problems in other graph ensembles, in particular for the study of detectability thresholds and resolution limits in stochastic block models.

  17. Cationic Nitrogen Doped Helical Nanographenes.

    PubMed

    Xu, Kun; Feng, Xinliang; Berger, Reinhard; Popov, Alexey A; Weigand, Jan J; Vincon, Ilka; Machata, Peter; Hennersdorf, Felix; Zhou, Youjia; Fu, Yubin

    2017-09-13

    Herein, we report on the synthesis of a series of novel cationic nitrogen doped nanographenes (CNDN) by rhodium catalyzed annulation reactions. This powerful method allows for the synthesis of cationic nanographenes with non-planar, axial chiral geometries. Single-crystal X-ray analysis reveals helical and cove-edged structures. Compared to their all-carbon analogues, the CNDN exhibit energetically lower lying frontier orbitals with a reduced optical energy gap and an electron accepting behavior. All derivatives show quasi reversible reductions in cyclic voltammetry. Depending on the number of nitrogen dopant, in situ spectroelectrochemistry proves the formation of neutral radicals (one nitrogen dopant) or radical cations (two nitrogen dopants) upon reduction. The developed synthetic protocol paves the way for the design and synthesis of expanded nanographenes or even graphene nanoribbons containing cationic nitrogen doping. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Liquid centrifugation for nuclear waste partitioning

    SciTech Connect

    Bowman, C.D.

    1992-03-11

    The performance of liquid centrifugation for nuclear waste partitioning is examined for the Accelerator Transmutation of Waste Program currently under study at the Los Alamos National Laboratory. Centrifugation might have application for the separation of the LiF-BeF{sub 2} salt from heavier radioactive materials fission product and actinides in the separation of fission product from actinides, in the isotope separation of fission-product cesium before transmutation of the {sup 137}Cs and {sup 135}Cs, and in the removal of spallation product from the liquid lead target. It is found that useful chemical separations should be possible using existing materials for the centrifuge construction for all four cases with the actinide fraction in fission product perhaps as low as 1 part in 10{sup 7} and the fraction of {sup 137}CS in {sup 133}Cs being as low as a few parts in 10{sup 5}. A centrifuge cascade has the advantage that it can be assembled and operated as a completely closed system without a waste stream except that associated with maintenance or replacement of centrifuge components.

  19. The Ziegler—Natta olefin insertion reaction for cationic metals

    NASA Astrophysics Data System (ADS)

    Jensen, Vidar R.; Siegban, Per E. M.

    1993-09-01

    The catalytic Ziegler—Natta polymerization reaction has been studied for a set of metal cations, in order to identify the role of the positive charge on this process. Geometry optimizations have been performed for the reactant metal—methyl systems, the π-coordinated olefin systems, the transition states for the olefin insertion and finally for the product metal—propyl systems. All valence electrons are correlated. The cations selected for this study are the transition metals Zr + and Ti +, the non-transition metals Be +, Mg +, Al + and finally also Si +. The transition metal cations are found to have very low barriers for the insertion, but the lowest barrier is actually found for Be +. The results are discussed in terms of the ionization energies and the accessibility to valence p and d orbitals. Comparisons are made to previous theoretical work on cationic model systems.

  20. Multiphoton fragmentation spectra of zirconium and niobium cluster cations

    NASA Astrophysics Data System (ADS)

    Aydin, M.; Lombardi, John R.

    2004-06-01

    The dissociation energies of the mass-selected zirconium dimer cation (90Zr2+) and niobium cation clusters, Nb2+ and Nb4+, were investigated using laser vaporization techniques coupled with time-of-flight (TOF) mass spectroscopy for production of jet-cooled cationic cluster beams. The selected cationic species were then fragmented by irradiation with an Nd:YAG-pumped (532 nm), tunable-pulsed PDL dye laser in the 15,500-18,500 cm-1 region. Dissociation energies were directly measured from a significant sharp rise in the spectral background as D0(90Zr2+)=4.18+/-0.01, D0(Nb2+)=5.94+/-0.01, and D0(Nb+3-Nb)=5.994+/-0.004 eV. We also estimate the first ionization energy of 90Zr2+ to be 5.82+/-0.01 eV using the thermochemical cycle.

  1. Advanced Aqueous Separation Systems for Actinide Partitioning

    SciTech Connect

    Nash, Kenneth L.; Clark, Sue; Meier, G Patrick; Alexandratos, Spiro; Paine, Robert; Hancock, Robert; Ensor, Dale

    2012-03-21

    One of the most challenging aspects of advanced processing of spent nuclear fuel is the need to isolate transuranium elements from fission product lanthanides. This project expanded the scope of earlier investigations of americium (Am) partitioning from the lanthanides with the synthesis of new separations materials and a centralized focus on radiochemical characterization of the separation systems that could be developed based on these new materials. The primary objective of this program was to explore alternative materials for actinide separations and to link the design of new reagents for actinide separations to characterizations based on actinide chemistry. In the predominant trivalent oxidation state, the chemistry of lanthanides overlaps substantially with that of the trivalent actinides and their mutual separation is quite challenging.

  2. Regulation of Cation Balance in Saccharomyces cerevisiae

    PubMed Central

    Cyert, Martha S.; Philpott, Caroline C.

    2013-01-01

    All living organisms require nutrient minerals for growth and have developed mechanisms to acquire, utilize, and store nutrient minerals effectively. In the aqueous cellular environment, these elements exist as charged ions that, together with protons and hydroxide ions, facilitate biochemical reactions and establish the electrochemical gradients across membranes that drive cellular processes such as transport and ATP synthesis. Metal ions serve as essential enzyme cofactors and perform both structural and signaling roles within cells. However, because these ions can also be toxic, cells have developed sophisticated homeostatic mechanisms to regulate their levels and avoid toxicity. Studies in Saccharomyces cerevisiae have characterized many of the gene products and processes responsible for acquiring, utilizing, storing, and regulating levels of these ions. Findings in this model organism have often allowed the corresponding machinery in humans to be identified and have provided insights into diseases that result from defects in ion homeostasis. This review summarizes our current understanding of how cation balance is achieved and modulated in baker’s yeast. Control of intracellular pH is discussed, as well as uptake, storage, and efflux mechanisms for the alkali metal cations, Na+ and K+, the divalent cations, Ca2+ and Mg2+, and the trace metal ions, Fe2+, Zn2+, Cu2+, and Mn2+. Signal transduction pathways that are regulated by pH and Ca2+ are reviewed, as well as the mechanisms that allow cells to maintain appropriate intracellular cation concentrations when challenged by extreme conditions, i.e., either limited availability or toxic levels in the environment. PMID:23463800

  3. Effects of ammonium on uranium partitioning and kaolinite mineral dissolution.

    PubMed

    Emerson, Hilary P; Di Pietro, Silvina; Katsenovich, Yelena; Szecsody, Jim

    2017-02-01

    Ammonia gas injection is a promising technique for the remediation of uranium within the vadose zone. It can be used to manipulate the pH of a system and cause co-precipitation processes that are expected to remove uranium from the aqueous phase and decrease leaching from the solid phase. The work presented in this paper explores the effects of ammonium and sodium hydroxide on the partitioning of uranium and dissolution of the kaolinite mineral in simplified synthetic groundwaters using equilibrium batch sorption and sequential extraction experiments. It shows that there is a significant increase in uranium removal in systems with divalent cations present in the aqueous phase but not in sodium chloride synthetic groundwaters. Further, the initial conditions of the aqueous phase do not affect the dissolution of kaolinite. However, the type of base treatment does have an effect on mineral dissolution. Published by Elsevier Ltd.

  4. Screening and evaluating aminated cationic functional moieties for potential CO(2) capture applications using an anionic MOF scaffold.

    PubMed

    Li, Tao; Rosi, Nathaniel L

    2013-12-18

    Three cations with different amine density, guanidinium, aminoguanidinium, and diaminoguanidinium, were loaded into anionic via cation-exchange. The structures and compositions of the cation-exchange products were characterized, and their N2 and CO2 adsorption properties were studied and compared.

  5. Laser system with partitioned prism

    SciTech Connect

    Nettleton, J. E.; Barr, D. N.

    1985-03-26

    An array of optical frequency-sensitive elements such as diffraction gratings or interference filters are arranged in a row, and the optical path of the laser cavity can be directed to include one of these elements. A partitioned optical prism consisting of a triangular portion and one or more paralleogramatic portions are used to direct the path. Between the portions are piezoelectric elements which, when energized, expand to provide an air gap between the portions and to allow total reflection of an optical ray at the surface of the prism next to the gap.

  6. Critical review and interpretation of environmental data for volatile methylsiloxanes: partition properties.

    PubMed

    Xu, Shihe; Kozerski, Gary; Mackay, Donald

    2014-10-21

    Volatile methylsiloxanes (VMS) enter the environment through industrial activities and the use of various consumer products. Reliable measurements of environmental partition properties for these compounds are critical for accurate prediction of their environmental fate, distribution, transport, exposure and potential effects. In this study, the measured partition properties including air/water (K(AW)), octanol/water (K(OW)), and octanol/air partitioning coefficients (K(OA)), soil organic carbon/water distribution coefficient (K(OC)), and biological medium/fluid partition coefficients, and their temperature dependence were critically reviewed. Based on these results, organosilicon compounds such as methylsiloxanes are expected to behave differently in the environment compared to conventional hydrophobic environmental contaminants, as a result of their inherent characteristics related to molecular size and capacity for different types of molecular interactions that control partitioning. The differences are critical and need to be taken into consideration in environmental exposure and risk analyses of these compounds.

  7. Starch synthesis and carbon partitioning in developing endosperm.

    PubMed

    Emes, M J; Bowsher, C G; Hedley, C; Burrell, M M; Scrase-Field, E S F; Tetlow, I J

    2003-01-01

    The biosynthesis of starch is the major determinant of yield in cereal grains. In this short review, attention is focused on the synthesis of the soluble substrate for starch synthesis, ADPglucose (ADPG). Consideration is given to the pathway of ADPG production, its subcellular compartmentation, and the role of metabolite transporters in mediating its delivery to the site of starch synthesis. As ADPG is an activated sugar, the dependence of its production on respiration, changes which occur during development, and the constraints which ATP production may place on carbon partitioning into different end-products are discussed.

  8. Estimating optimal partitions for stochastic complex systems

    NASA Astrophysics Data System (ADS)

    Hirata, Yoshito; Aihara, Kazuyuki

    2013-06-01

    Partitions provide simple symbolic representations for complex systems. For a deterministic system, a generating partition establishes one-to-one correspondence between an orbit and the infinite symbolic sequence generated by the partition. For a stochastic system, however, a generating partition does not exist. In this paper, we propose a method to obtain a partition that best specifies the locations of points for a time series generated from a stochastic system by using the corresponding symbolic sequence under a constraint of an information rate. When the length of the substrings is limited with a finite length, the method coincides with that for estimating a generating partition from a time series generated from a deterministic system. The two real datasets analyzed in Kennel and Buhl, Phys. Rev. Lett. 91, 084102 (2003), are reanalyzed with the proposed method to understand their underlying dynamics intuitively.

  9. On some trees having partition dimension four

    NASA Astrophysics Data System (ADS)

    Ida Bagus Kade Puja Arimbawa, K.; Baskoro, Edy Tri

    2016-02-01

    In 1998, G. Chartrand, E. Salehi and P. Zhang introduced the notion of partition dimension of a graph. Since then, the study of this graph parameter has received much attention. A number of results have been obtained to know the values of partition dimensions of various classes of graphs. However, for some particular classes of graphs, finding of their partition dimensions is still not completely solved, for instances a class of general tree. In this paper, we study the properties of trees having partition dimension 4. In particular, we show that, for olive trees O(n), its partition dimension is equal to 4 if and only if 8 ≤ n ≤ 17. We also characterize all centipede trees having partition dimension 4.

  10. Displaying multimedia environmental partitioning by triangular diagrams

    SciTech Connect

    Lee, S.C.; Mackay, D.

    1995-11-01

    It is suggested that equilateral triangular diagrams are a useful method of depicting the equilibrium partitioning of organic chemicals among the three primary environmental media of the atmosphere, the hydrosphere, and the organosphere (natural organic matter and biotic lipids and waxes). The technique is useful for grouping chemicals into classes according to their partitioning tendencies, for depicting the incremental effects of substituents such as alkyl groups and chlorine, and for showing how partitioning changes in response to changes in temperature.

  11. Cylindric partitions, {{\\boldsymbol{ W }}}_{r} characters and the Andrews-Gordon-Bressoud identities

    NASA Astrophysics Data System (ADS)

    Foda, O.; Welsh, T. A.

    2016-04-01

    We study the Andrews-Gordon-Bressoud (AGB) generalisations of the Rogers-Ramanujan q-series identities in the context of cylindric partitions. We recall the definition of r-cylindric partitions, and provide a simple proof of Borodin’s product expression for their generating functions, that can be regarded as a limiting case of an unpublished proof by Krattenthaler. We also recall the relationships between the r-cylindric partition generating functions, the principal characters of {\\hat{{sl}}}r algebras, the {{\\boldsymbol{ M }}}r r,r+d minimal model characters of {{\\boldsymbol{ W }}}r algebras, and the r-string abaci generating functions, providing simple proofs for each. We then set r = 2, and use two-cylindric partitions to re-derive the AGB identities as follows. Firstly, we use Borodin’s product expression for the generating functions of the two-cylindric partitions with infinitely long parts, to obtain the product sides of the AGB identities, times a factor {(q;q)}∞ -1, which is the generating function of ordinary partitions. Next, we obtain a bijection from the two-cylindric partitions, via two-string abaci, into decorated versions of Bressoud’s restricted lattice paths. Extending Bressoud’s method of transforming between restricted paths that obey different restrictions, we obtain sum expressions with manifestly non-negative coefficients for the generating functions of the two-cylindric partitions which contains a factor {(q;q)}∞ -1. Equating the product and sum expressions of the same two-cylindric partitions, and canceling a factor of {(q;q)}∞ -1 on each side, we obtain the AGB identities.

  12. Chemical amplification based on fluid partitioning in an immiscible liquid

    DOEpatents

    Anderson, Brian L.; Colston, Bill W.; Elkin, Christopher J.

    2010-09-28

    A system for nucleic acid amplification of a sample comprises partitioning the sample into partitioned sections and performing PCR on the partitioned sections of the sample. Another embodiment of the invention provides a system for nucleic acid amplification and detection of a sample comprising partitioning the sample into partitioned sections, performing PCR on the partitioned sections of the sample, and detecting and analyzing the partitioned sections of the sample.

  13. The stringy instanton partition function

    NASA Astrophysics Data System (ADS)

    Bonelli, Giulio; Sciarappa, Antonio; Tanzini, Alessandro; Vasko, Petr

    2014-01-01

    We perform an exact computation of the gauged linear sigma model associated to a D1-D5 brane system on a resolved A 1 singularity. This is accomplished via supersymmetric localization on the blown-up two-sphere. We show that in the blow-down limit the partition function reduces to the Nekrasov partition function evaluating the equivariant volume of the instanton moduli space. For finite radius we obtain a tower of world-sheet instanton corrections, that we identify with the equivariant Gromov-Witten invariants of the ADHM moduli space. We show that these corrections can be encoded in a deformation of the Seiberg-Witten prepotential. From the mathematical viewpoint, the D1-D5 system under study displays a twofold nature: the D1-branes viewpoint captures the equivariant quantum cohomology of the ADHM instanton moduli space in the Givental formalism, and the D5-branes viewpoint is related to higher rank equivariant Donaldson-Thomas invariants of.

  14. Aggregation of Kanamycin A: dimer formation with physiological cations.

    PubMed

    Dieterich, Johannes M; Gerstel, Ulrich; Schröder, Jens-Michael; Hartke, Bernd

    2011-12-01

    Global cluster geometry optimization has focused so far on clusters of atoms or of compact molecules. We are demonstrating here that present-day techniques also allow to globally optimize clusters of extended, flexible molecules, and that such studies have immediate relevance to experiment. For example, recent experimental findings point to production of larger clusters of an aminoglycoside closely related to Kanamycin A (KA), together with certain preferred physiological cations, by Pseudomonas aeruginosa. The present study provides first theoretical support for KA clustering, with a close examination of the monomer, the bare dimer, and dimers with sodium and potassium cations, employing global cluster structure optimization, in conjunction with force fields, semiempirical methods, DFT and ab-initio approaches. Interestingly, already at this stage the theoretical findings support the experimental observation that sodium cations are preferred over potassium cations in KA clusters, due to fundamentally different cationic embedding. Theoretically predicted NMR and IR spectra for these species indicate that it should be possible to experimentally detect the aggregation state and even the cationic embedding mode in such clusters.

  15. Metal/Silicate Partitioning at High Pressures and Temperatures

    NASA Technical Reports Server (NTRS)

    Shofner, G.; Campbell, A.; Danielson, L.; Righter, K.; Rahman, Z.

    2010-01-01

    The behavior of siderophile elements during metal-silicate segregation, and their resulting distributions provide insight into core formation processes. Determination of partition coefficients allows the calculation of element distributions that can be compared to established values of element abundances in the silicate (mantle) and metallic (core) portions of the Earth. Moderately siderophile elements, including W, are particularly useful in constraining core formation conditions because they are sensitive to variations in T, P, oxygen fugacity (fO2), and silicate composition. To constrain the effect of pressure on W metal/silicate partitioning, we performed experiments at high pressures and temperatures using a multi anvil press (MAP) at NASA Johnson Space Center and laser-heated diamond anvil cells (LHDAC) at the University of Maryland. Starting materials consisted of natural peridotite mixed with Fe and W metals. Pressure conditions in the MAP experiments ranged from 10 to 16 GPa at 2400 K. Pressures in the LHDAC experiments ranged from 26 to 58 GPa, and peak temperatures ranged up to 5000 K. LHDAC experimental run products were sectioned by focused ion beam (FIB) at NASA JSC. Run products were analyzed by electron microprobe using wavelength dispersive spectroscopy. Liquid metal/liquid silicate partition coefficients for W were calculated from element abundances determined by microprobe analyses, and corrected to a common fO2 condition of IW-2 assuming +4 valence for W. Within analytical uncertainties, W partitioning shows a flat trend with increasing pressure from 10 to 16 GPa. At higher pressures, W becomes more siderophile, with an increase in partition coefficient of approximately 0.5 log units.

  16. Geometric crossovers for multiway graph partitioning.

    PubMed

    Moraglio, Alberto; Kim, Yong-Hyuk; Yoon, Yourim; Moon, Byung-Ro

    2007-01-01

    Geometric crossover is a representation-independent generalization of the traditional crossover defined using the distance of the solution space. By choosing a distance firmly rooted in the syntax of the solution representation as a basis for geometric crossover, one can design new crossovers for any representation. Using a distance tailored to the problem at hand, the formal definition of geometric crossover allows us to design new problem-specific crossovers that embed problem-knowledge in the search. The standard encoding for multiway graph partitioning is highly redundant: each solution has a number of representations, one for each way of labeling the represented partition. Traditional crossover does not perform well on redundant encodings. We propose a new geometric crossover for graph partitioning based on a labeling-independent distance that filters out the redundancy of the encoding. A correlation analysis of the fitness landscape based on this distance shows that it is well suited to graph partitioning. A second difficulty with designing a crossover for multiway graph partitioning is that of feasibility: in general recombining feasible partitions does not lead to feasible offspring partitions. We design a new geometric crossover for permutations with repetitions that naturally suits partition problems and we test it on the graph partitioning problem. We then combine it with the labeling-independent crossover and obtain a much superior geometric crossover inheriting both advantages.

  17. Partitioning Strategy Using Static Analysis Techniques

    NASA Astrophysics Data System (ADS)

    Seo, Yongjin; Soo Kim, Hyeon

    2016-08-01

    Flight software is software used in satellites' on-board computers. It has requirements such as real time and reliability. The IMA architecture is used to satisfy these requirements. The IMA architecture has the concept of partitions and this affected the configuration of flight software. That is, situations occurred in which software that had been loaded on one system was divided into many partitions when being loaded. For new issues, existing studies use experience based partitioning methods. However, these methods have a problem that they cannot be reused. In this respect, this paper proposes a partitioning method that is reusable and consistent.

  18. Automatic analysis of D-partition

    NASA Astrophysics Data System (ADS)

    Bogaevskaya, V. G.

    2017-01-01

    The paper is dedicated to automatization of D-partition analysis. D-partition is one of the most common methods for determination of solution stability in systems with time-delayed feedback control and its dependency on values of control parameters. A transition from analytical form of D-partition to plain graph has been investigated. An algorithm of graph faces determination and calculation of count of characteristic equation roots with positive real part for appropriate area of D-partition has been developed. The algorithm keeps an information about analytical formulas for edges of faces. It allows to make further analytical research based on the results of computer analysis.

  19. Anion concentration-dependent partitioning mechanism in the extraction of uranium into room-temperature ionic liquids.

    PubMed

    Dietz, Mark L; Stepinski, Dominique C

    2008-04-15

    The mode of partitioning of uranyl ion between nitrate-containing aqueous phases and various N,N'-dialkylimidazolium-based room-temperature ionic liquids (RTILs) in the presence of tri-n-butyl phosphate (TBP) is shown to change from an ion-exchange process to one involving extraction of a neutral uranyl-TBP-nitrato complex as the aqueous nitrate concentration is increased. Increasing the hydrophobicity of the RTIL cation eventually leads to nitrato complex extraction as the predominant mode of partitioning, regardless of nitrate concentration.

  20. Cost efficient CFD simulations: Proper selection of domain partitioning strategies

    NASA Astrophysics Data System (ADS)

    Haddadi, Bahram; Jordan, Christian; Harasek, Michael

    2017-10-01

    Computational Fluid Dynamics (CFD) is one of the most powerful simulation methods, which is used for temporally and spatially resolved solutions of fluid flow, heat transfer, mass transfer, etc. One of the challenges of Computational Fluid Dynamics is the extreme hardware demand. Nowadays super-computers (e.g. High Performance Computing, HPC) featuring multiple CPU cores are applied for solving-the simulation domain is split into partitions for each core. Some of the different methods for partitioning are investigated in this paper. As a practical example, a new open source based solver was utilized for simulating packed bed adsorption, a common separation method within the field of thermal process engineering. Adsorption can for example be applied for removal of trace gases from a gas stream or pure gases production like Hydrogen. For comparing the performance of the partitioning methods, a 60 million cell mesh for a packed bed of spherical adsorbents was created; one second of the adsorption process was simulated. Different partitioning methods available in OpenFOAM® (Scotch, Simple, and Hierarchical) have been used with different numbers of sub-domains. The effect of the different methods and number of processor cores on the simulation speedup and also energy consumption were investigated for two different hardware infrastructures (Vienna Scientific Clusters VSC 2 and VSC 3). As a general recommendation an optimum number of cells per processor core was calculated. Optimized simulation speed, lower energy consumption and consequently the cost effects are reported here.

  1. Methodology for optimally sized centrifugal partition chromatography columns.

    PubMed

    Chollet, Sébastien; Marchal, Luc; Jérémy Meucci; Renault, Jean-Hugues; Legrand, Jack; Foucault, Alain

    2015-04-03

    Centrifugal Partition Chromatography (CPC) is a separation process based on the partitioning of solutes between two partially miscible liquid phases. There is no solid support for the stationary phase. The centrifugal acceleration is responsible for both stationary phase retention and mobile phase dispersion. CPC is thus a process based on liquid-liquid mass transfer. The separation efficiency is mainly influenced by the hydrodynamics of the phases in each cell of the column. Thanks to a visualization system, called "Visual CPC", it was observed that the mobile phase can flow through the stationary phase as a sheet, or a spray. Hydrodynamics, which directly governs the instrument efficiency, is directly affected during scale changes, and non-linear phenomena prevent the successful achievement of mastered geometrical scale changes. In this work, a methodology for CPC column sizing is proposed, based on the characterization of the efficiency of advanced cell shapes, taking into account the hydrodynamics. Knowledge about relationship between stationary phase volume, cell efficiency and separation resolution in CPC allowed calculating the optimum cell number for laboratory and industrial scale CPC application. The methodology is highlighted with results on five different geometries from 25 to 5000 mL, for two applications: the separation of alkylbenzene by partitioning with heptane/methanol/water biphasic system; and the separation of peptides by partitioning with n-butanol/acetic acid/water (4/1/5) biphasic system. With this approach, it is possible to predict the optimal CPC column length leading to highest productivity.

  2. Efficient partitioning and assignment on programs for multiprocessor execution

    NASA Technical Reports Server (NTRS)

    Standley, Hilda M.

    1993-01-01

    The general problem studied is that of segmenting or partitioning programs for distribution across a multiprocessor system. Efficient partitioning and the assignment of program elements are of great importance since the time consumed in this overhead activity may easily dominate the computation, effectively eliminating any gains made by the use of the parallelism. In this study, the partitioning of sequentially structured programs (written in FORTRAN) is evaluated. Heuristics, developed for similar applications are examined. Finally, a model for queueing networks with finite queues is developed which may be used to analyze multiprocessor system architectures with a shared memory approach to the problem of partitioning. The properties of sequentially written programs form obstacles to large scale (at the procedure or subroutine level) parallelization. Data dependencies of even the minutest nature, reflecting the sequential development of the program, severely limit parallelism. The design of heuristic algorithms is tied to the experience gained in the parallel splitting. Parallelism obtained through the physical separation of data has seen some success, especially at the data element level. Data parallelism on a grander scale requires models that accurately reflect the effects of blocking caused by finite queues. A model for the approximation of the performance of finite queueing networks is developed. This model makes use of the decomposition approach combined with the efficiency of product form solutions.

  3. Cation Uptake and Allocation by Red Pine Seedlings under Cation-Nutrient Stress in a Column Growth Experiment

    SciTech Connect

    Shi, Zhenqing; Balogh-Brunstad, Zsuzsanna; Grant, Michael R.; Harsh, James B.; Gill, Richard; Thomashow, Linda; Dohnalkova, Alice; Stacks, Daryl; Letourneau, Melissa; Keller, Chester K.

    2014-01-10

    Background and Aims Plant nutrient uptake is affected by environmental stress, but how plants respond to cation-nutrient stress is poorly understood. We assessed the impact of varying degrees of cation-nutrient limitation on cation uptake in an experimental plant-mineral system. Methods Column experiments, with red pine (Pinus resinosa Ait.) seedlings growing in sand/mineral mixtures, were conducted for up to nine months under a range of Ca- and K-limited conditions. The Ca and K were supplied from both minerals and nutrient solutions with varying Ca and K concentrations. Results Cation nutrient stress had little impact on carbon allocation after nine months of plant growth and K was the limiting nutrient for biomass production. The Ca/Sr and K/Rb ratio results allowed independent estimation of dissolution incongruency and discrimination against Sr and Rb during cation uptake processes. The fraction of K in biomass from biotite increased with decreasing K supply from nutrient solutions. The mineral anorthite was consistently the major source of Ca, regardless of nutrient treatment. Conclusions Red pine seedlings exploited more mineral K in response to more severe K deficiency. This did not occur for Ca. Plant discrimination factors must be carefully considered to accurately identify nutrient sources using cation tracers.

  4. Radionuclide Partitioning in an Underground Nuclear Test Cavity

    SciTech Connect

    Rose, T P; Hu, Q; Zhao, P; Conrado, C L; Dickerson, R; Eaton, G F; Kersting, A B; Moran, J E; Nimz, G; Powell, B A; Ramon, E C; Ryerson, F J; Williams, R W; Wooddy, P T; Zavarin, M

    2009-01-09

    In 2004, a borehole was drilled into the 1983 Chancellor underground nuclear test cavity to investigate the distribution of radionuclides within the cavity. Sidewall core samples were collected from a range of depths within the re-entry hole and two sidetrack holes. Upon completion of drilling, casing was installed and a submersible pump was used to collect groundwater samples. Test debris and groundwater samples were analyzed for a variety of radionuclides including the fission products {sup 99}Tc, {sup 125}Sb, {sup 129}I, {sup 137}Cs, and {sup 155}Eu, the activation products {sup 60}Co, {sup 152}Eu, and {sup 154}Eu, and the actinides U, Pu, and Am. In addition, the physical and bulk chemical properties of the test debris were characterized using Scanning Electron Microscopy (SEM) and Electron Microprobe measurements. Analytical results were used to evaluate the partitioning of radionuclides between the melt glass, rubble, and groundwater phases in the Chancellor test cavity. Three comparative approaches were used to calculate partitioning values, though each method could not be applied to every nuclide. These approaches are based on: (1) the average Area 19 inventory from Bowen et al. (2001); (2) melt glass, rubble, and groundwater mass estimates from Zhao et al. (2008); and (3) fission product mass yield data from England and Rider (1994). The U and Pu analyses of the test debris are classified and partitioning estimates for these elements were calculated directly from the classified Miller et al. (2002) inventory for the Chancellor test. The partitioning results from this study were compared to partitioning data that were previously published by the IAEA (1998). Predictions of radionuclide distributions from the two studies are in agreement for a majority of the nuclides under consideration. Substantial differences were noted in the partitioning values for {sup 99}Tc, {sup 125}Sb, {sup 129}I, and uranium. These differences are attributable to two factors

  5. Capability of cation exchange technology to remove proven N-nitrosodimethylamine precursors.

    PubMed

    Li, Shixiang; Zhang, Xulan; Bei, Er; Yue, Huihui; Lin, Pengfei; Wang, Jun; Zhang, Xiaojian; Chen, Chao

    2017-08-01

    N-nitrosodimethylamine (NDMA) precursors consist of a positively charged dimethylamine group and a non-polar moiety, which inspired us to develop a targeted cation exchange technology to remove NDMA precursors. In this study, we tested the removal of two representative NDMA precursors, dimethylamine (DMA) and ranitidine (RNTD), by strong acidic cation exchange resin. The results showed that pH greatly affected the exchange efficiency, with high removal (DMA>78% and RNTD>94%) observed at pHMg(2+)>RNTD(+)>K(+)>DMA(+)>NH4(+)>Na(+). The partition coefficient of DMA(+) to Na(+) was 1.41±0.26, while that of RNTD(+) to Na(+) was 12.1±1.9. The pseudo second-order equation fitted the cation exchange kinetics well. Bivalent inorganic cations such as Ca(2+) were found to have a notable effect on NA precursor removal in softening column test. Besides DMA and RNTD, cation exchange process also worked well for removing other 7 model NDMA precursors. Overall, NDMA precursor removal can be an added benefit of making use of cation exchange water softening processes. Copyright © 2017. Published by Elsevier B.V.

  6. Advanced Aqueous Separation Systems for Actinide Partitioning

    SciTech Connect

    Nash, Ken; Martin, Leigh; Lumetta, Gregg

    2015-04-02

    One of the most challenging aspects of advanced processing of used nuclear fuel is the separation of transplutonium actinides from fission product lanthanides. This separation is essential if actinide transmutation options are to be pursued in advanced fuel cycles, as lanthanides compete with actinides for neutrons in both thermal and fast reactors, thus limiting efficiency. The separation is difficult because the chemistry of Am3+ and Cm3+ is nearly identical to that of the trivalent lanthanides (Ln3+). The prior literature teaches that two approaches offer the greatest probability of devising a successful group separation process based on aqueous processes: 1) the application of complexing agents containing ligand donor atoms that are softer than oxygen (N, S, Cl-) or 2) changing the oxidation state of Am to the IV, V, or VI state to increase the essential differences between Am and lanthanide chemistry (an approach utilized in the PUREX process to selectively remove Pu4+ and UO22+ from fission products). The latter approach offers the additional benefit of enabling a separation of Am from Cm, as Cm(III) is resistant to oxidation and so can easily be made to follow the lanthanides. The fundamental limitations of these approaches are that 1) the soft(er) donor atoms that interact more strongly with actinide cations than lanthanides form substantially weaker bonds than oxygen atoms, thus necessitating modification of extraction conditions for adequate phase transfer efficiency, 2) soft donor reagents have been seen to suffer slow phase transfer kinetics and hydro-/radiolytic stability limitations and 3) the upper oxidation states of Am are all moderately strong oxidants, hence of only transient stability in media representative of conventional aqueous separations systems. There are examples in the literature of both approaches having been described. However, it is not clear at present that any extant process is sufficiently robust for application at the scale

  7. Electrospray ionization tandem mass spectrometry of ammonium cationized polyethers.

    PubMed

    Nasioudis, Andreas; Heeren, Ron M A; van Doormalen, Irene; de Wijs-Rot, Nicolette; van den Brink, Oscar F

    2011-05-01

    Quaternary ammonium salts (Quats) and amines are known to facilitate the MS analysis of high molar mass polyethers by forming low charge state adduct ions. The formation, stability, and behavior upon collision-induced dissociation (CID) of adduct ions of polyethers with a variety of Quats and amines were studied by electrospray ionization quadrupole time-of-flight, quadrupole ion trap, and linear ion trap tandem mass spectrometry (MS/MS). The linear ion trap instrument was part of an Orbitrap hybrid mass spectrometer that allowed accurate mass MS/MS measurements. The Quats and amines studied were of different degree of substitution, structure, and size. The stability of the adduct ions was related to the structure of the cation, especially the amine's degree of substitution. CID of singly/doubly charged primary and tertiary ammonium cationized polymers resulted in the neutral loss of the amine followed by fragmentation of the protonated product ions. The latter reveals information about the monomer unit, polymer sequence, and endgroup structure. In addition, the detection of product ions retaining the ammonium ion was observed. The predominant process in the CID of singly charged quaternary ammonium cationized polymers was cation detachment, whereas their doubly charged adduct ions provided the same information as the primary and tertiary ammonium cationized adduct ions. This study shows the potential of specific amines as tools for the structural elucidation of high molar mass polyethers.

  8. Electrospray Ionization Tandem Mass Spectrometry of Ammonium Cationized Polyethers

    NASA Astrophysics Data System (ADS)

    Nasioudis, Andreas; Heeren, Ron M. A.; van Doormalen, Irene; de Wijs-Rot, Nicolette; van den Brink, Oscar F.

    2011-05-01

    Quaternary ammonium salts (Quats) and amines are known to facilitate the MS analysis of high molar mass polyethers by forming low charge state adduct ions. The formation, stability, and behavior upon collision-induced dissociation (CID) of adduct ions of polyethers with a variety of Quats and amines were studied by electrospray ionization quadrupole time-of-flight, quadrupole ion trap, and linear ion trap tandem mass spectrometry (MS/MS). The linear ion trap instrument was part of an Orbitrap hybrid mass spectrometer that allowed accurate mass MS/MS measurements. The Quats and amines studied were of different degree of substitution, structure, and size. The stability of the adduct ions was related to the structure of the cation, especially the amine's degree of substitution. CID of singly/doubly charged primary and tertiary ammonium cationized polymers resulted in the neutral loss of the amine followed by fragmentation of the protonated product ions. The latter reveals information about the monomer unit, polymer sequence, and endgroup structure. In addition, the detection of product ions retaining the ammonium ion was observed. The predominant process in the CID of singly charged quaternary ammonium cationized polymers was cation detachment, whereas their doubly charged adduct ions provided the same information as the primary and tertiary ammonium cationized adduct ions. This study shows the potential of specific amines as tools for the structural elucidation of high molar mass polyethers.

  9. Cation affinity numbers of Lewis bases.

    PubMed

    Lindner, Christoph; Tandon, Raman; Maryasin, Boris; Larionov, Evgeny; Zipse, Hendrik

    2012-01-01

    Using selected theoretical methods the affinity of a large range of Lewis bases towards model cations has been quantified. The range of model cations includes the methyl cation as the smallest carbon-centered electrophile, the benzhydryl and trityl cations as models for electrophilic substrates encountered in Lewis base-catalyzed synthetic procedures, and the acetyl cation as a substrate model for acyl-transfer reactions. Affinities towards these cationic electrophiles are complemented by data for Lewis-base addition to Michael acceptors as prototypical neutral electrophiles.

  10. Assimilate partitioning during reproductive growth

    SciTech Connect

    Finazzo, S.F.; Davenport, T.L.

    1987-04-01

    Leaves having various phyllotactic relationships to fruitlets were labeled for 1 hour with 10/sub r/Ci of /sup 14/CO/sub 2/. Fruitlets were also labeled. Fruitlets did fix /sup 14/CO/sub 2/. Translocation of radioactivity from the peel into the fruit occurred slowly and to a limited extent. No evidence of translocation out of the fruitlets was observed. Assimilate partitioning in avocado was strongly influenced by phyllotaxy. If a fruit and the labeled leaf had the same phyllotaxy then greater than 95% of the radiolabel was present in this fruit. When the fruit did not have the same phyllotaxy as the labeled leaf, the radiolabel distribution was skewed with 70% of the label going to a single adjacent position. Avocado fruitlets exhibit uniform labeling throughout a particular tissue. In avocado, assimilates preferentially move from leaves to fruits with the same phyllotaxy.

  11. Ionic partitioning and stomatal regulation

    PubMed Central

    Sanoubar, Rabab; Orsini, Francesco; Gianquinto, Giorgio Prosdocimi

    2013-01-01

    Vegetable grafting is commonly claimed to improve crop’s tolerance to biotic and abiotic stresses, including salinity. Although the use of inter-specific graftings is relatively common, whether the improved salt tolerance should be attributed to the genotypic background rather than the grafting per se is a matter of discussion among scientists. It is clear that most of published research has to date overlooked the issue, with the mutual presence of self-grafted and non-grafted controls resulting to be quite rare within experimental evidences. It was recently demonstrated that the genotype of the rootstock and grafting per se are responsible respectively for the differential ion accumulation and partitioning as well as to the stomatal adaptation to the stress. The present paper contributes to the ongoing discussion with further data on the differences associated to salinity response in a range of grafted melon combinations. PMID:24309549

  12. HPAM: Hirshfeld partitioned atomic multipoles

    NASA Astrophysics Data System (ADS)

    Elking, Dennis M.; Perera, Lalith; Pedersen, Lee G.

    2012-02-01

    An implementation of the Hirshfeld (HD) and Hirshfeld-Iterated (HD-I) atomic charge density partitioning schemes is described. Atomic charges and atomic multipoles are calculated from the HD and HD-I atomic charge densities for arbitrary atomic multipole rank l on molecules of arbitrary shape and size. The HD and HD-I atomic charges/multipoles are tested by comparing molecular multipole moments and the electrostatic potential (ESP) surrounding a molecule with their reference ab initio values. In general, the HD-I atomic charges/multipoles are found to better reproduce ab initio electrostatic properties over HD atomic charges/multipoles. A systematic increase in precision for reproducing ab initio electrostatic properties is demonstrated by increasing the atomic multipole rank from l=0 (atomic charges) to l=4 (atomic hexadecapoles). Both HD and HD-I atomic multipoles up to rank l are shown to exactly reproduce ab initio molecular multipole moments of rank L for L⩽l. In addition, molecular dipole moments calculated by HD, HD-I, and ChelpG atomic charges only ( l=0) are compared with reference ab initio values. Significant errors in reproducing ab initio molecular dipole moments are found if only HD or HD-I atomic charges used. Program summaryProgram title: HPAM Catalogue identifier: AEKP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License v2 No. of lines in distributed program, including test data, etc.: 500 809 No. of bytes in distributed program, including test data, etc.: 13 424 494 Distribution format: tar.gz Programming language: C Computer: Any Operating system: Linux RAM: Typically, a few hundred megabytes Classification: 16.13 External routines: The program requires 'formatted checkpoint' files obtained from the Gaussian 03 or Gaussian 09 quantum chemistry program. Nature of problem: An ab initio

  13. MULTIVARIATE KERNEL PARTITION PROCESS MIXTURES

    PubMed Central

    Dunson, David B.

    2013-01-01

    Mixtures provide a useful approach for relaxing parametric assumptions. Discrete mixture models induce clusters, typically with the same cluster allocation for each parameter in multivariate cases. As a more flexible approach that facilitates sparse nonparametric modeling of multivariate random effects distributions, this article proposes a kernel partition process (KPP) in which the cluster allocation varies for different parameters. The KPP is shown to be the driving measure for a multivariate ordered Chinese restaurant process that induces a highly-flexible dependence structure in local clustering. This structure allows the relative locations of the random effects to inform the clustering process, with spatially-proximal random effects likely to be assigned the same cluster index. An exact block Gibbs sampler is developed for posterior computation, avoiding truncation of the infinite measure. The methods are applied to hormone curve data, and a dependent KPP is proposed for classification from functional predictors. PMID:24478563

  14. Body Partitioning in ASL Metaphorical Blends

    ERIC Educational Resources Information Center

    Wulf, Alyssa; Dudis, Paul

    2005-01-01

    Grounded blends may be literal or metaphorical, the latter allowing for an even richer variety of blend characteristics. This contribution of metaphor is achieved largely through the utilization of body partitioning. Body partitioning may result in: (1) the appearance of a single, coherent source-domain scene iconically represented; (2) a single…

  15. [On the partition of acupuncture academic schools].

    PubMed

    Yang, Pengyan; Luo, Xi; Xia, Youbing

    2016-05-01

    Nowadays extensive attention has been paid on the research of acupuncture academic schools, however, a widely accepted method of partition of acupuncture academic schools is still in need. In this paper, the methods of partition of acupuncture academic schools in the history have been arranged, and three typical methods of"partition of five schools" "partition of eighteen schools" and "two-stage based partition" are summarized. After adeep analysis on the disadvantages and advantages of these three methods, a new method of partition of acupuncture academic schools that is called "three-stage based partition" is proposed. In this method, after the overall acupuncture academic schools are divided into an ancient stage, a modern stage and a contemporary stage, each schoolis divided into its sub-school category. It is believed that this method of partition can remedy the weaknesses ofcurrent methods, but also explore a new model of inheritance and development under a different aspect through thedifferentiation and interaction of acupuncture academic schools at three stages.

  16. Building Ecology and Partition Design. Technical Bulletin.

    ERIC Educational Resources Information Center

    Maryland State Dept. of Education, Baltimore.

    This bulletin is intended as a resource for school system facility planners and architects who design schools. Ways in which decision makers can incorporate environmental concerns in the design of school buildings are detailed. Focus is on the design of interior partition systems. Partition systems in schools serve several purposes; they define…

  17. Building Ecology and Partition Design. Technical Bulletin.

    ERIC Educational Resources Information Center

    Maryland State Dept. of Education, Baltimore.

    This bulletin is intended as a resource for school system facility planners and architects who design schools. Ways in which decision makers can incorporate environmental concerns in the design of school buildings are detailed. Focus is on the design of interior partition systems. Partition systems in schools serve several purposes; they define…

  18. Graph Partitioning Models for Parallel Computing

    SciTech Connect

    Hendrickson, B.; Kolda, T.G.

    1999-03-02

    Calculations can naturally be described as graphs in which vertices represent computation and edges reflect data dependencies. By partitioning the vertices of a graph, the calculation can be divided among processors of a parallel computer. However, the standard methodology for graph partitioning minimizes the wrong metric and lacks expressibility. We survey several recently proposed alternatives and discuss their relative merits.

  19. Efficient multiple-way graph partitioning algorithms

    SciTech Connect

    Dasdan, A.; Aykanat, C.

    1995-12-01

    Graph partitioning deals with evenly dividing a graph into two or more parts such that the total weight of edges interconnecting these parts, i.e., cutsize, is minimized. Graph partitioning has important applications in VLSI layout, mapping, and sparse Gaussian elimination. Since graph partitioning problem is NP-hard, we should resort to polynomial-time algorithms to obtain a good solution, or hopefully a near-optimal solution. Kernighan-Lin (KL) propsoed a 2-way partitioning algorithms. Fiduccia-Mattheyses (FM) introduced a faster version of KL algorithm. Sanchis (FMS) generalized FM algorithm to a multiple-way partitioning algorithm. Simulated Annealing (SA) is one of the most successful approaches that are not KL-based.

  20. Cell partition in two phase polymer systems

    NASA Technical Reports Server (NTRS)

    Brooks, D. E.

    1979-01-01

    Aqueous phase-separated polymer solutions can be used as support media for the partition of biological macromolecules, organelles and cells. Cell separations using the technique have proven to be extremely sensitive to cell surface properties but application of the systems are limited to cells or aggregates which do not significantly while the phases are settling. Partition in zero g in principle removes this limitation but an external driving force must be applied to induce the phases to separate since their density difference disappears. We have recently shown that an applied electric field can supply the necessary driving force. We are proposing to utilize the NASA FES to study field-driven phase separation and cell partition on the ground and in zero g to help define the separation/partition process, with the ultimate goal being to develop partition as a zero g cell separation technique.

  1. Parallel hypergraph partitioning for scientific computing.

    SciTech Connect

    Heaphy, Robert; Devine, Karen Dragon; Catalyurek, Umit; Bisseling, Robert; Hendrickson, Bruce Alan; Boman, Erik Gunnar

    2005-07-01

    Graph partitioning is often used for load balancing in parallel computing, but it is known that hypergraph partitioning has several advantages. First, hypergraphs more accurately model communication volume, and second, they are more expressive and can better represent nonsymmetric problems. Hypergraph partitioning is particularly suited to parallel sparse matrix-vector multiplication, a common kernel in scientific computing. We present a parallel software package for hypergraph (and sparse matrix) partitioning developed at Sandia National Labs. The algorithm is a variation on multilevel partitioning. Our parallel implementation is novel in that it uses a two-dimensional data distribution among processors. We present empirical results that show our parallel implementation achieves good speedup on several large problems (up to 33 million nonzeros) with up to 64 processors on a Linux cluster.

  2. Purification of biomaterials by phase partitioning

    NASA Technical Reports Server (NTRS)

    Harris, J. M.

    1984-01-01

    A technique which is particularly suited to microgravity environments and which is potentially more powerful than electrophoresis is phase partitioning. Phase partitioning is purification by partitioning between the two immiscible aqueous layers formed by solution of the polymers poly(ethylene glycol) and dextran in water. This technique proved to be very useful for separations in one-g but is limited for cells because the cells are more dense than the phase solutions thus tend to sediment to the bottom of the container before reaching equilibrium with the preferred phase. There are three phases to work in this area: synthesis of new polymers for affinity phase partitioning; development of automated apparatus for ground-based separations; and design of apparatus for performing simple phase partitioning space experiments, including examination of mechanisms for separating phases in the absence of gravity.

  3. Purification of biomaterials by phase partitioning

    NASA Technical Reports Server (NTRS)

    Harris, J. M.

    1984-01-01

    A technique which is particularly suited to microgravity environments and which is potentially more powerful than electrophoresis is phase partitioning. Phase partitioning is purification by partitioning between the two immiscible aqueous layers formed by solution of the polymers poly(ethylene glycol) and dextran in water. This technique proved to be very useful for separations in one-g but is limited for cells because the cells are more dense than the phase solutions thus tend to sediment to the bottom of the container before reaching equilibrium with the preferred phase. There are three phases to work in this area: synthesis of new polymers for affinity phase partitioning; development of automated apparatus for ground-based separations; and design of apparatus for performing simple phase partitioning space experiments, including examination of mechanisms for separating phases in the absence of gravity.

  4. Recovery of small bioparticles by interfacial partitioning.

    PubMed

    Jauregi, P; Hoeben, M A; van der Lans, R G J M; Kwant, G; van der Wielen, L A M

    2002-05-20

    In this article, a qualitative study of the recovery of small bioparticles by interfacial partitioning in liquid-liquid biphasic systems is presented. A range of crystallised biomolecules with varying polarities have been chosen such as glycine, phenylglycine and ampicillin. Liquid-liquid biphasic systems in a range of polarity differences were selected such as an aqueous two-phase system (ATPS), water-butanol and water-hexanol. The results indicate that interfacial partitioning of crystals occurs even when their density exceeds that of the individual liquid phases. Yet, not all crystals partition to the same extent to the interface to form a stable and thick interphase layer. This indicates some degree of selectivity. From the analysis of these results in relation to the physicochemical properties of the crystals and the liquid phases, a hypothetical mechanism for the interfacial partitioning is deduced. Overall these results support the potential of interfacial partitioning as a large scale separation technology.

  5. Neptunium(V) partitioning to uranium(VI) oxide and peroxide solids.

    PubMed

    Douglas, Matthew; Clark, Sue B; Friese, Judah I; Arey, Bruce W; Buck, Edgar C; Hanson, Brady D

    2005-06-01

    Metaschoepite, [(UO2)8O2(OH)12] x 10H2O, and metastudtite, UO4 x 4H2O, are alteration phases anticipated in a spent nuclear fuel repository following the moist oxidation of UO2 on a geologic time scale. Dissolved concentrations and hence potential mobility of other radionuclides in the fuel, such as the neptunyl cation (NpO2+), will likely be determined by the extent of their partitioning into these U(VI) solids. 237Np is of particular interest due to its potential high mobility and long half-life (2.1 x 10(6) years.) In this study, metaschoepite has been precipitated and subsequently transformed to studtite in the presence of dissolved Np. The metaschoepite and studtite solids that formed initially contained <10 and 6500 ppm Np, respectively. Batch dissolution studies of these solids at pH 6 demonstrate release of Np that exceeds congruent dissolution of U from metastudtite; furthermore, the released Np cation remains in solution. Thus, although the Np partitions into the metastudtite solid initially, it is released to solution over time, indicating that metastudtite is not likely to serve as a host solid for Np incorporation or sorption of the neptunyl cation on long time scales.

  6. Comparing methods for partitioning a decade of carbon dioxide and water vapor fluxes in a temperate forest

    Treesearch

    Benjamin N. Sulman; Daniel Tyler Roman; Todd M. Scanlon; Lixin Wang; Kimberly A. Novick

    2016-01-01

    The eddy covariance (EC) method is routinely used to measure net ecosystem fluxes of carbon dioxide (CO2) and evapotranspiration (ET) in terrestrial ecosystems. It is often desirable to partition CO2 flux into gross primary production (GPP) and ecosystem respiration (RE), and to partition ET into evaporation and...

  7. GAS- AND SOLID-PHASE PARTITIONING OF PCDDS/FS ON MSWI FLY ASH AND THE EFFECTS OF SAMPLING

    EPA Science Inventory

    Semi-volatile organic compounds (SOCs), including polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/Fs), are partitioned as gas-phase and particle-bound products of many industrial combustion processes. This gas/particle partitioning of SOCs has severe implications on both ...

  8. Ultrafast photochemistry with two product channels: Wavepacket motion through two distinct conical intersections

    NASA Astrophysics Data System (ADS)

    Riedle, Eberhard; Roos, Matthias K.; Thallmair, Sebastian; Sailer, Christian F.; Krebs, Nils; Fingerhut, Benjamin P.; de Vivie-Riedle, Regina

    2017-09-01

    Light induced bond cleavage is an ubiquitous process in large molecules, yet its quantum nature is not fully understood. We present a comprehensive description of the ultrafast light induced Csbnd Cl bond cleavage in diarylmethyl chlorides combining femtosecond transient absorption measurements with ab initio calculations. We observe a delayed appearance of radicals (80 fs) and cations (125 fs). The excited state wavepacket moves initially toward two conical intersections and the passing through these intersections determines the partitioning into the differing product channels. Different locations of the conical intersections explain the observed delay times.

  9. Glycosyl Cations versus Allylic Cations in Spontaneous and Enzymatic Hydrolysis.

    PubMed

    Danby, Phillip M; Withers, Stephen G

    2017-08-09

    Enzymatic prenyl and glycosyl transfer are seemingly unrelated reactions that yield molecules and protein modifications with disparate biological functions. However, both reactions employ diphosphate-activated donors and each proceed via cationic species: allylic cations and oxocarbenium ions, respectively. In this study, we explore the relationship between these processes by preparing valienyl ethers to serve as glycoside mimics that are capable of allylic rather than oxocarbenium cation stabilization. Rate constants for spontaneous hydrolysis of aryl glycosides and their analogous valienyl ethers were found to be almost identical, as were the corresponding activation enthalpies and entropies. This close similarity extended to the associated secondary kinetic isotope effects (KIEs), indicating very similar transition state stabilities and structures. Screening a library of over 100 β-glucosidases identified a number of enzymes that catalyze hydrolysis of these valienyl ethers with kcat values up to 20 s(-1). Detailed analysis of one such enzyme showed that ether hydrolysis occurs via the analogous mechanisms found for glycosides, and through a very similar transition state. This suggests that the generally lower rates of enzymatic cleavage of the cyclitol ethers reflects evolutionary specialization of these enzymes toward glycosides rather than inherent reactivity differences.

  10. Heavy metal cations permeate the TRPV6 epithelial cation channel.

    PubMed

    Kovacs, Gergely; Danko, Tamas; Bergeron, Marc J; Balazs, Bernadett; Suzuki, Yoshiro; Zsembery, Akos; Hediger, Matthias A

    2011-01-01

    TRPV6 belongs to the vanilloid family of the transient receptor potential channel (TRP) superfamily. This calcium-selective channel is highly expressed in the duodenum and the placenta, being responsible for calcium absorption in the body and fetus. Previous observations have suggested that TRPV6 is not only permeable to calcium but also to other divalent cations in epithelial tissues. In this study, we tested whether TRPV6 is indeed also permeable to cations such as zinc and cadmium. We found that the basal intracellular calcium concentration was higher in HEK293 cells transfected with hTRPV6 than in non-transfected cells, and that this difference almost disappeared in nominally calcium-free solution. Live cell imaging experiments with Fura-2 and NewPort Green DCF showed that overexpression of human TRPV6 increased the permeability for Ca(2+), Ba(2+), Sr(2+), Mn(2+), Zn(2+), Cd(2+), and interestingly also for La(3+) and Gd(3+). These results were confirmed using the patch clamp technique. (45)Ca uptake experiments showed that cadmium, lanthanum and gadolinium were also highly efficient inhibitors of TRPV6-mediated calcium influx at higher micromolar concentrations. Our results suggest that TRPV6 is not only involved in calcium transport but also in the transport of other divalent cations, including heavy metal ions, which may have toxicological implications.

  11. Halogenated silanes, radicals, and cations

    NASA Astrophysics Data System (ADS)

    Wang, Liming; He, Yi-Liang

    2008-09-01

    Quantum chemistry study has been carried out on the structure and energetics of halogenated silanes, radicals, and cations (SiHxXy0,+1, X = F, Cl, Br; x + y = 1-4). The geometries are optimized at B3LYP/6-31+G(2df,p) level. The adiabatic ionization energiess (IEas), relative energetics of cations, proton affinities (PAs) of silanes, and the enthalpies of formation are predicted using G3(CC) model chemistry. Non-classical ion complex structures are found for hydrogenated cations and transition states connecting classical and non-classical structures are also located. The most stable cations for silylene and silyl radicals have their classical divalent and trivalent structures, and those for silanes have non-classical structures except for SiH3Br+ and SiH2Br2+. The non-classical structures for halosilane cations imply difficulty in experimentally measurement of the adiabatic ionization energies using photoionization or photoelectron studies. For SiH3X, SiH2X2, and SiHX3, the G3(CC) adiabatic IEas to classical ionic structures closest to their neutrals agree better with the photoelectron spectroscopic measurements. The transition states between classical and non-classical structures also hamper the photoionization determination of the appearance energies for silylene cations from silanes. The G3(CC) results for SiHx0,+1 agree excellently with the photoionization mass spectrometric study, and the results for fluorinated and chlorinated species also agree with the previous theoretical predictions at correlation levels from BAC-MP4 to CCSD(T)/CBS. The predicted enthalpy differences between SiH2Cl+, SiHCl2+, and SiCl3+ are also in accordance with previous kinetics study. The G3(CC) results show large discrepancies to the collision-induced charge transfer and/or dissociation reactions involving SiFx+ and SiClx+ ions, for which the G3(CC) enthalpies of formation are also significantly differed from the previous theoretical predictions, especially on SiFx+ (x = 2-4). The G3

  12. Cationically polymerizable monomers derived from renewable sources. Annual performance report

    SciTech Connect

    Crivello, J.V.

    1992-10-01

    The objectives of this project are to design and synthesize novel monomers which orginate from renewable biological sources and to carry out their rapid, efficient, pollution-free and energy efficient cationic polymerization to useful products under the influence of ultraviolet light or heat. A summary of the results of the past year`s research on cationically polymerizable monomers derived from renewable sources is presented. Three major areas of investigation corresponding to the different classes of naturally occurring starting materials were investigated; epoxidized terpenes and natural rubber and vinyl ethers from alcohols and carbohydrates.

  13. Spatial assignment of symmetry adapted perturbation theory interaction energy components: The atomic SAPT partition

    NASA Astrophysics Data System (ADS)

    Parrish, Robert M.; Sherrill, C. David

    2014-07-01

    We develop a physically-motivated assignment of symmetry adapted perturbation theory for intermolecular interactions (SAPT) into atom-pairwise contributions (the A-SAPT partition). The basic precept of A-SAPT is that the many-body interaction energy components are computed normally under the formalism of SAPT, following which a spatially-localized two-body quasiparticle interaction is extracted from the many-body interaction terms. For electrostatics and induction source terms, the relevant quasiparticles are atoms, which are obtained in this work through the iterative stockholder analysis (ISA) procedure. For the exchange, induction response, and dispersion terms, the relevant quasiparticles are local occupied orbitals, which are obtained in this work through the Pipek-Mezey procedure. The local orbital atomic charges obtained from ISA additionally allow the terms involving local orbitals to be assigned in an atom-pairwise manner. Further summation over the atoms of one or the other monomer allows for a chemically intuitive visualization of the contribution of each atom and interaction component to the overall noncovalent interaction strength. Herein, we present the intuitive development and mathematical form for A-SAPT applied in the SAPT0 approximation (the A-SAPT0 partition). We also provide an efficient series of algorithms for the computation of the A-SAPT0 partition with essentially the same computational cost as the corresponding SAPT0 decomposition. We probe the sensitivity of the A-SAPT0 partition to the ISA grid and convergence parameter, orbital localization metric, and induction coupling treatment, and recommend a set of practical choices which closes the definition of the A-SAPT0 partition. We demonstrate the utility and computational tractability of the A-SAPT0 partition in the context of side-on cation-π interactions and the intercalation of DNA by proflavine. A-SAPT0 clearly shows the key processes in these complicated noncovalent interactions, in

  14. Spatial assignment of symmetry adapted perturbation theory interaction energy components: The atomic SAPT partition.

    PubMed

    Parrish, Robert M; Sherrill, C David

    2014-07-28

    We develop a physically-motivated assignment of symmetry adapted perturbation theory for intermolecular interactions (SAPT) into atom-pairwise contributions (the A-SAPT partition). The basic precept of A-SAPT is that the many-body interaction energy components are computed normally under the formalism of SAPT, following which a spatially-localized two-body quasiparticle interaction is extracted from the many-body interaction terms. For electrostatics and induction source terms, the relevant quasiparticles are atoms, which are obtained in this work through the iterative stockholder analysis (ISA) procedure. For the exchange, induction response, and dispersion terms, the relevant quasiparticles are local occupied orbitals, which are obtained in this work through the Pipek-Mezey procedure. The local orbital atomic charges obtained from ISA additionally allow the terms involving local orbitals to be assigned in an atom-pairwise manner. Further summation over the atoms of one or the other monomer allows for a chemically intuitive visualization of the contribution of each atom and interaction component to the overall noncovalent interaction strength. Herein, we present the intuitive development and mathematical form for A-SAPT applied in the SAPT0 approximation (the A-SAPT0 partition). We also provide an efficient series of algorithms for the computation of the A-SAPT0 partition with essentially the same computational cost as the corresponding SAPT0 decomposition. We probe the sensitivity of the A-SAPT0 partition to the ISA grid and convergence parameter, orbital localization metric, and induction coupling treatment, and recommend a set of practical choices which closes the definition of the A-SAPT0 partition. We demonstrate the utility and computational tractability of the A-SAPT0 partition in the context of side-on cation-π interactions and the intercalation of DNA by proflavine. A-SAPT0 clearly shows the key processes in these complicated noncovalent interactions, in

  15. Spatial assignment of symmetry adapted perturbation theory interaction energy components: The atomic SAPT partition

    SciTech Connect

    Parrish, Robert M.; Sherrill, C. David

    2014-07-28

    We develop a physically-motivated assignment of symmetry adapted perturbation theory for intermolecular interactions (SAPT) into atom-pairwise contributions (the A-SAPT partition). The basic precept of A-SAPT is that the many-body interaction energy components are computed normally under the formalism of SAPT, following which a spatially-localized two-body quasiparticle interaction is extracted from the many-body interaction terms. For electrostatics and induction source terms, the relevant quasiparticles are atoms, which are obtained in this work through the iterative stockholder analysis (ISA) procedure. For the exchange, induction response, and dispersion terms, the relevant quasiparticles are local occupied orbitals, which are obtained in this work through the Pipek-Mezey procedure. The local orbital atomic charges obtained from ISA additionally allow the terms involving local orbitals to be assigned in an atom-pairwise manner. Further summation over the atoms of one or the other monomer allows for a chemically intuitive visualization of the contribution of each atom and interaction component to the overall noncovalent interaction strength. Herein, we present the intuitive development and mathematical form for A-SAPT applied in the SAPT0 approximation (the A-SAPT0 partition). We also provide an efficient series of algorithms for the computation of the A-SAPT0 partition with essentially the same computational cost as the corresponding SAPT0 decomposition. We probe the sensitivity of the A-SAPT0 partition to the ISA grid and convergence parameter, orbital localization metric, and induction coupling treatment, and recommend a set of practical choices which closes the definition of the A-SAPT0 partition. We demonstrate the utility and computational tractability of the A-SAPT0 partition in the context of side-on cation-π interactions and the intercalation of DNA by proflavine. A-SAPT0 clearly shows the key processes in these complicated noncovalent interactions, in

  16. Development of cationic nanocrystals for ocular delivery.

    PubMed

    Romero, Gregori B; Keck, Cornelia M; Müller, Rainer H; Bou-Chacra, Nadia A

    2016-10-01

    A cationic nanocrystal formulation containing dexamethasone acetate nanocrystals (0.05%) and polymyxin B (0.10%) for ophthalmic application was produced using a self-developed small scale method for wet bead milling. The formulation developed offers the advantage of increased saturation solubility of the drug (due to the nano-size of the crystals) and increased residence time in the eye (due to small size and increased mucoadhesion by the cationic charge) resulting ultimately in potential increased bioavailability. Characterization of the nanosuspensions by photon correlation spectroscopy (PCS) and transmission electron microscopy showed that the production method was successful in achieving dexamethasone crystals in the range of about 200-250nm. The physical stabilization of the nanocrystals and generation of the positive charge were realized by using cetylpyridinium chloride (CPC) and benzalkonium chloride (BAC) at the concentration of 0.01%. In contrast to other cationic excipients, they are regulatorily accepted due to their use as preservatives. The drug polymyxin B also contributed to the positive charge. Positive zeta potentials in the range +20 to +30mV were achieved. Isotonicity was adjusted using NaCl and non-ionic excipients (glycerol, sorbitol, dextrose). Physical and chemical stabilities were monitored for a period of 6months at room temperature, 5°C and 40°C. Particle size of the bulk population assessed by PCS remained practically unchanged over 6months of storage for the various formulations without isotonicity agents, and for the CPC-containing formulations with non-ionic isotonicity excipients. The chemical content also proved stable after 6months for all 3 temperatures evaluated. In vitro investigation of mucoadhesion was tested using mucin solutions at different concentrations, and the generated negative zeta potential was used as a measure of the interaction. The zeta potential reversed to about -15mV, indicating distinct interaction. The

  17. Ecological partitioning and diversity in tropical planktonic foraminifera

    PubMed Central

    2012-01-01

    Background Ecological processes are increasingly being viewed as an important mode of diversification in the marine environment, where the high dispersal potential of pelagic organisms, and a lack of absolute barriers to gene flow may limit the occurrence of allopatric speciation through vicariance. Here we focus on the potential role of ecological partitioning in the diversification of a widely distributed group of marine protists, the planktonic foraminifera. Sampling was conducted in the tropical Arabian Sea, during the southwest (summer) monsoon, when pronounced environmental conditions result in a strong disparity in temperature, salinity and productivity between distinct northern and southern water masses. Results We uncovered extensive genetic diversity within the Arabian Sea planktonic foraminifera, identifying 13 morphospecies, represented by 20 distinct SSU rRNA genetic types. Several morphospecies/genetic types displayed non-random biogeographical distributions, partitioning between the northern and southern water masses, giving a strong indication of independent ecological adaptations. Conclusions We propose sea-surface primary productivity as the main factor driving the geographical segregation of Arabian Sea planktonic foraminifera, during the SW monsoon, with variations in symbiotic associations possibly playing a role in the specific ecological adaptations observed. Our findings suggest that ecological partitioning could be contributing to the high levels of 'cryptic' genetic diversity observed within the planktonic foraminifera, and support the view that ecological processes may play a key role in the diversification of marine pelagic organisms. PMID:22507289

  18. Selecting optimal partitioning schemes for phylogenomic datasets.

    PubMed

    Lanfear, Robert; Calcott, Brett; Kainer, David; Mayer, Christoph; Stamatakis, Alexandros

    2014-04-17

    Partitioning involves estimating independent models of molecular evolution for different subsets of sites in a sequence alignment, and has been shown to improve phylogenetic inference. Current methods for estimating best-fit partitioning schemes, however, are only computationally feasible with datasets of fewer than 100 loci. This is a problem because datasets with thousands of loci are increasingly common in phylogenetics. We develop two novel methods for estimating best-fit partitioning schemes on large phylogenomic datasets: strict and relaxed hierarchical clustering. These methods use information from the underlying data to cluster together similar subsets of sites in an alignment, and build on clustering approaches that have been proposed elsewhere. We compare the performance of our methods to each other, and to existing methods for selecting partitioning schemes. We demonstrate that while strict hierarchical clustering has the best computational efficiency on very large datasets, relaxed hierarchical clustering provides scalable efficiency and returns dramatically better partitioning schemes as assessed by common criteria such as AICc and BIC scores. These two methods provide the best current approaches to inferring partitioning schemes for very large datasets. We provide free open-source implementations of the methods in the PartitionFinder software. We hope that the use of these methods will help to improve the inferences made from large phylogenomic datasets.

  19. Photodissociation of Cerium Oxide Nanocluster Cations.

    PubMed

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A

    2016-04-21

    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)).

  20. Regulation of assimilate partitioning by daylength and spectral quality

    SciTech Connect

    Britz, S.J.

    1994-12-31

    Photosynthesis is the process by which plants utilize light energy to assimilate and transform carbon dioxide into products that support growth and development. The preceding review provides an excellent summary of photosynthetic mechanisms and diurnal patterns of carbon metabolism with emphasis on the importance of gradual changes in photosynthetically-active radiation at dawn and dusk. In addition to these direct effects of irradiance, there are indirect effects of light period duration and spectral quality on carbohydrate metabolism and assimilate partitioning. Both daylength and spectral quality trigger developmental phenomena such as flowering (e.g., photoperiodism) and shade avoidance responses, but their effects on partitioning of photoassimilates in leaves are less well known. Moreover, the adaptive significance to the plants of such effects is sometimes not clear.

  1. Experimental determination of the partition coefficient of HOI

    SciTech Connect

    Harrell, J.R.; Lutz, J.B.; Kelly, J.L.

    1986-01-01

    An understanding of iodine-water chemistry and the partitioning of iodine species between the liquid and vapor phases is necessary for the purpose of iodine source term evaluations. Hypoiodous acid (HOI) is a volatile iodine species formed by the hydrolysis of iodine. In a well-mixed system, equilibrium between the vapor and liquid phases is quickly attained and is quantified in terms of the partition coefficient (PC). At the ANS Topical Meeting on Fission Product Behavior and Source Term Research at Snowbird, Utah, other investigators reported values for the HOI PC in excess of 10/sup 4/. Work at the University of Virginia, however, indicates that a more realistic value is closer to 10/sup 3/. This paper summarizes that work.

  2. Photosynthate partitioning during flowering in relation to senescence of spinach

    SciTech Connect

    Sklensky, D.; Davies, P.J. )

    1990-05-01

    Male spinach plants are frequently cited as a counter-example to the nutrient drain hypothesis. Photosynthate partitioning in both male and female plants was examined. Leaves just below the inflorescences in plants at various stages of flowering were labelled with {sup 14}CO{sub 2} and the photosynthate allowed to partition for three hours. The leaves, flowers and stems of the inflorescence, and the other above ground vegetative tissue were harvested. These parts were combusted in a sample oxidizer for the collection of the {sup 14}CO{sub 2}. Allocation to the male and female flowers at very early stages are similar. As the flowers develop further, male flowers receive more photosynthate than do female flowers in early fruit production. Thus it is possible that nutrient drain to the flowers in male spinach plants is sufficient to account for senescence.

  3. Aryl cation and carbene intermediates in the photodehalogenation of chlorophenols.

    PubMed

    Manet, Ilse; Monti, Sandra; Fagnoni, Maurizio; Protti, Stefano; Albini, Angelo

    2004-12-17

    The photochemistry of 2,6-dimethyl-4-chlorophenol (6) has been studied in methanol and trifluoroethanol (TFE) through product studies and transient absorption spectroscopy. Chloride loss from triplet 6 gave triplet hydroxyphenyl cation 14, which equilibrated with triplet oxocyclohexadienylydene 15 within a few tens of nanoseconds; the cation can, however, be selectively trapped by allyltrimethylsilane (k(ad) = 10(8)-10(9) m(-1) s(-1)) to give a phenonium ion and the allylated phenol. In neat alcohols, 14 and 15 are reduced through different mechanisms, namely by hydrogen transfer through radical cation 17 and via phenoxyl radical 16, respectively. The mechanistic rationalization has been substantiated by the parallel study of an O-silylated derivative. The work shows that the chemistry of the highly (but selectively) reactive phenyl cation 14 can not only be discriminated from that of the likewise highly reactive carbene 15, but also exploited for synthetically useful reactions, as in this case with alkenes. Photolysis of electron-donating substituted halobenzenes may be the method of choice for the mild generation of some classes of phenyl cations.

  4. Calorimetric study of cationic photopolymerization

    NASA Astrophysics Data System (ADS)

    Czajlik, I.; Hedvig, P.; Ille, A.; Dobó, J.

    1996-03-01

    The photopolymerization of penta-erythritol tetra-glycidyl ether (initiator Degacure KI-85) was studied by a du Pont 910 type DSC. From our experimental results the following conclusions can be drawn: (1) During the cationic polymerization reaction the lifetime of the initiating centers are long compared to the lifetime of free radicals in case of radical polymerization. (2) The rate of deactivation of the initiating centers increases with increasing temperature.

  5. Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.

    PubMed

    Padró, Juan M; Pellegrino Vidal, Rocío B; Reta, Mario

    2014-12-01

    The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium bromide, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium dicyanamide, were accurately measured. In this way, we extended our database of partition coefficients in room-temperature ionic liquids previously reported. We employed the solvation parameter model with different probe molecules (the training set) to elucidate the chemical interactions involved in the partition process and discussed the most relevant differences among the three types of ionic liquids. The multiparametric equations obtained with the aforementioned model were used to predict the partition coefficients for compounds (the test set) not present in the training set, most being of biological and pharmacological interest. An excellent agreement between calculated and experimental log P IL/w values was obtained. Thus, the obtained equations can be used to predict, a priori, the extraction efficiency for any compound using these ionic liquids as extraction solvents in liquid-liquid extractions.

  6. Partitioning of quencher ions in the micellar microenvironment of polyoxyethylene nonyl phenol

    NASA Astrophysics Data System (ADS)

    Ghosh, Sujit Kumar; Khatua, Pijus Kanti; Ghosh, Jayanta Kumar; Bhattacharya, Subhash Chandra

    2005-01-01

    This paper has explored the quenching of fluorescence of the dye safranine T (ST) by the inorganic cations viz Cu 2+, Co 2+, Ni 2+ and Mn 2+ in micellar solutions of the surfactant dioxyethylene nonyl phenol (Igepal CO-210), pentaoxyethylene nonyl phenol (Igepal CO-520) and dodecaoxyethylene nonyl phenol (Igepal CO-720). The quenching results have been calculated in light of stern volmer equation (SV) to evaluate the extent of interaction between the fluorophore (ST) and quencher. The average concentration of the quencher ions in the micelle have been determined. The quenching efficiency of ST by inorganic ions in micellar medium is lower than that in aqueous medium. The results show that the ions get partitioned in the micellar medium. The values of the partition coefficient of the ions decrease with increase in HLB value and number of oxyethylene groups in Igepal.

  7. Partitioning of quencher ions in the micellar microenvironment of polyoxyethylene nonyl phenol.

    PubMed

    Ghosh, Sujit Kumar; Khatua, Pijus Kanti; Ghosh, Jayanta Kumar; Bhattacharya, Subhash Chandra

    2005-01-14

    This paper has explored the quenching of fluorescence of the dye safranine T (ST) by the inorganic cations viz Cu2+, Co2+, Ni2+ and Mn2+ in micellar solutions of the surfactant dioxyethylene nonyl phenol (Igepal CO-210), pentaoxyethylene nonyl phenol (Igepal CO-520) and dodecaoxyethylene nonyl phenol (Igepal CO-720). The quenching results have been calculated in light of stern volmer equation (SV) to evaluate the extent of interaction between the fluorophore (ST) and quencher. The average concentration of the quencher ions in the micelle have been determined. The quenching efficiency of ST by inorganic ions in micellar medium is lower than that in aqueous medium. The results show that the ions get partitioned in the micellar medium. The values of the partition coefficient of the ions decrease with increase in HLB value and number of oxyethylene groups in Igepal.

  8. Partitioned Bayesian analyses, partition choice, and the phylogenetic relationships of scincid lizards.

    PubMed

    Brandley, Matthew C; Schmitz, Andreas; Reeder, Tod W

    2005-06-01

    Partitioned Bayesian analyses of approximately 2.2 kb of nucleotide sequence data (mtDNA) were used to elucidate phylogenetic relationships among 30 scincid lizard genera. Few partitioned Bayesian analyses exist in the literature, resulting in a lack of methods to determine the appropriate number of and identity of partitions. Thus, a criterion, based on the Bayes factor, for selecting among competing partitioning strategies is proposed and tested. Improvements in both mean -lnL and estimated posterior probabilities were observed when specific models and parameter estimates were assumed for partitions of the total data set. This result is expected given that the 95% credible intervals of model parameter estimates for numerous partitions do not overlap and it reveals that different data partitions may evolve quite differently. We further demonstrate that how one partitions the data (by gene, codon position, etc.) is shown to be a greater concern than simply the overall number of partitions. Using the criterion of the 2 ln Bayes factor > 10, the phylogenetic analysis employing the largest number of partitions was decisively better than all other strategies. Strategies that partitioned the ND1 gene by codon position performed better than other partition strategies, regardless of the overall number of partitions. Scincidae, Acontinae, Lygosominae, east Asian and North American "Eumeces" + Neoseps; North African Eumeces, Scincus, and Scincopus, and a large group primarily from sub-Saharan Africa, Madagascar, and neighboring islands are monophyletic. Feylinia, a limbless group of previously uncertain relationships, is nested within a "scincine" clade from sub-Saharan Africa. We reject the hypothesis that the nearly limbless dibamids are derived from within the Scincidae, but cannot reject the hypothesis that they represent the sister taxon to skinks. Amphiglossus, Chalcides, the acontines Acontias and Typhlosaurus, and Scincinae are paraphyletic. The globally widespread

  9. REE Partitioning in Lunar Minerals

    NASA Technical Reports Server (NTRS)

    Rapp, J. F.; Lapen, T. J.; Draper, D. S.

    2015-01-01

    Rare earth elements (REE) are an extremely useful tool in modeling lunar magmatic processes. Here we present the first experimentally derived plagioclase/melt partition coefficients in lunar compositions covering the entire suite of REE. Positive europium anomalies are ubiquitous in the plagioclase-rich rocks of the lunar highlands, and complementary negative Eu anomalies are found in most lunar basalts. These features are taken as evidence of a large-scale differentiation event, with crystallization of a global-scale lunar magma ocean (LMO) resulting in a plagioclase flotation crust and a mafic lunar interior from which mare basalts were subsequently derived. However, the extent of the Eu anomaly in lunar rocks is variable. Fagan and Neal [1] reported highly anorthitic plagioclase grains in lunar impact melt rock 60635,19 that displayed negative Eu anomalies as well as the more usual positive anomalies. Indeed some grains in the sample are reported to display both positive and negative anomalies. Judging from cathodoluminescence images, these anomalies do not appear to be associated with crystal overgrowths or zones.

  10. HPAM: Hirshfeld Partitioned Atomic Multipoles

    PubMed Central

    Elking, Dennis M.; Perera, Lalith; Pedersen, Lee G.

    2011-01-01

    An implementation of the Hirshfeld (HD) and Hirshfeld-Iterated (HD-I) atomic charge density partitioning schemes is described. Atomic charges and atomic multipoles are calculated from the HD and HD-I atomic charge densities for arbitrary atomic multipole rank lmax on molecules of arbitrary shape and size. The HD and HD-I atomic charges/multipoles are tested by comparing molecular multipole moments and the electrostatic potential (ESP) surrounding a molecule with their reference ab initio values. In general, the HD-I atomic charges/multipoles are found to better reproduce ab initio electrostatic properties over HD atomic charges/multipoles. A systematic increase in precision for reproducing ab initio electrostatic properties is demonstrated by increasing the atomic multipole rank from lmax = 0 (atomic charges) to lmax = 4 (atomic hexadecapoles). Both HD and HD-I atomic multipoles up to rank lmax are shown to exactly reproduce ab initio molecular multipole moments of rank L for L ≤ lmax. In addition, molecular dipole moments calculated by HD, HD-I, and ChelpG atomic charges only (lmax = 0) are compared with reference ab initio values. Significant errors in reproducing ab initio molecular dipole moments are found if only HD or HD-I atomic charges used. PMID:22140274

  11. Spectral partitioning in diffraction tomography

    SciTech Connect

    Lehman, S K; Chambers, D H; Candy, J V

    1999-06-14

    The scattering mechanism of diffraction tomography is described by the integral form of the Helmholtz equation. The goal of diffraction tomography is to invert this equation in order to reconstruct the object function from the measured scattered fields. During the forward propagation process, the spatial spectrum of the object under investigation is ''smeared,'' by a convolution in the spectral domain, across the propagating and evanescent regions of the received field. Hence, care must be taken in performing the reconstruction, as the object's spectral information has been moved into regions where it may be considered to be noise rather than useful information. This will reduce the quality and resolution of the reconstruction. We show haw the object's spectrum can be partitioned into resolvable and non-resolvable parts based upon the cutoff between the propagating and evanescent fields. Operating under the Born approximation, we develop a beam-forming on transmit approach to direct the energy into either the propagating or evanescent parts of the spectrum. In this manner, we may individually interrogate the propagating and evanescent regions of the object spectrum.

  12. Intersecting surface defects and instanton partition functions

    DOE PAGES

    Pan, Yiwen; Peelaers, Wolfger

    2017-07-14

    We analyze intersecting surface defects inserted in interacting four-dimensional N = 2 supersymmetric quantum field theories. We employ the realization of a class of such systems as the infrared xed points of renormalization group flows from larger theories, triggered by perturbed Seiberg-Witten monopole-like con gurations, to compute their partition functions. These results are cast into the form of a partition function of 4d/2d/0d coupled systems. In conclusion, our computations provide concrete expressions for the instanton partition function in the presence of intersecting defects and we study the corresponding ADHM model.

  13. Partitioning of regular computation on multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Lee, Fung Fung

    1988-01-01

    Problem partitioning of regular computation over two dimensional meshes on multiprocessor systems is examined. The regular computation model considered involves repetitive evaluation of values at each mesh point with local communication. The computational workload and the communication pattern are the same at each mesh point. The regular computation model arises in numerical solutions of partial differential equations and simulations of cellular automata. Given a communication pattern, a systematic way to generate a family of partitions is presented. The influence of various partitioning schemes on performance is compared on the basis of computation to communication ratio.

  14. Partitioning of regular computation on multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Lee, Fung F.

    1990-01-01

    Problem partitioning of regular computation over two dimensional meshes on multiprocessor systems is examined. The regular computation model considered involves repetitive evaluation of values at each mesh point with local communication. The computational workload and the communication pattern are the same at each mesh point. The regular computation model arises in numerical solutions of partial differential equations and simulations of cellular automata. Given a communication pattern, a systematic way to generate a family of partitions is presented. The influence of various partitioning schemes on performance is compared on the basis of computation to communication ratio.

  15. Partitioning of regular computation on multiprocessor systems

    SciTech Connect

    Lee, F. . Computer Systems Lab.)

    1990-07-01

    Problem partitioning of regular computation over two-dimensional meshes on multiprocessor systems is examined. The regular computation model considered involves repetitive evaluation of values at each mesh point with local communication. The computational workload and the communication pattern are the same at each mesh point. The regular computation model arises in numerical solutions of partial differential equations and simulations of cellular automata. Given a communication pattern, a systematic way to generate a family of partitions is presented. The influence of various partitioning schemes on performance is compared on the basis of computation to communication ratio.

  16. Intersecting surface defects and instanton partition functions

    NASA Astrophysics Data System (ADS)

    Pan, Yiwen; Peelaers, Wolfger

    2017-07-01

    We analyze intersecting surface defects inserted in interacting four-dimensional N=2 supersymmetric quantum field theories. We employ the realization of a class of such systems as the infrared fixed points of renormalization group flows from larger theories, triggered by perturbed Seiberg-Witten monopole-like configurations, to compute their partition functions. These results are cast into the form of a partition function of 4d/2d/0d coupled systems. Our computations provide concrete expressions for the instanton partition function in the presence of intersecting defects and we study the corresponding ADHM model.

  17. Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide

    DOE PAGES

    Resasco, Joaquin; Chen, Leanne D.; Clark, Ezra; ...

    2017-07-24

    The electrochemical reduction of CO2 is known to be influenced by the identity of the alkali metal cation in the electrolyte; however, a satisfactory explanation for this phenomenon has not been developed. Here we present the results of experimental and theoretical studies aimed at elucidating the effects of electrolyte cation size on the intrinsic activity and selectivity of metal catalysts for the reduction of CO2. Experiments were conducted under conditions where the influence of electrolyte polarization is minimal in order to show that cation size affects the intrinsic rates of formation of certain reaction products, most notably for HCOO–, C2H4,more » and C2H5OH over Cu(100)- and Cu(111)-oriented thin films, and for CO and HCOO– over polycrystalline Ag and Sn. Interpretation of the findings for CO2 reduction was informed by studies of the reduction of glyoxal and CO, key intermediates along the reaction pathway to final products. Density functional theory calculations show that the alkali metal cations influence the distribution of products formed as a consequence of electrostatic interactions between solvated cations present at the outer Helmholtz plane and adsorbed species having large dipole moments. As a result, the observed trends in activity with cation size are attributed to an increase in the concentration of cations at the outer Helmholtz plane with increasing cation size.« less

  18. Demonstration of spray booth recirculation and partitioning -- Phase 2

    SciTech Connect

    Proffitt, D.; Clayton, R.K.; Ayer, J.

    1996-12-31

    Acurex Environmental was contracted by the US EPA to demonstrate an advanced pollution control cost reduction strategy at a US Marine Corps maintenance facility in Barstow, CA. One booth was modified and two new booths were built and manifolded into a single air pollution control device. This SERDP funded project grew out of previous studies by the EPA and DoD to evaluate and develop economic volatile organic compound (VOC) control technologies for painting facilities. This first application of partitioned recirculating booth in a high volume production environment fulfills a stated SERDP goal of transferring promising design concepts into reliable production applications.

  19. The effect of glycerol, propylene glycol and polyethylene glycol 400 on the partition coefficient of benzophenone-3 (oxybenzone).

    PubMed

    Mbah, C J

    2007-01-01

    Sunscreen products are widely used to protect the skin from sun-related deleterious effects. The objective of the study was to investigate the potential effect of glycerol, propylene glycol and polyethylene glycol 400 on dermal absorption of oxybenzone by studying their effects on its partition coefficient. The partition coefficient was evaluated in a chloroform-water system at room temperature. It was found that glycerol and propylene glycol decreased the partition coefficient of oxybenzone, while an increase in partition coefficient was observed with polyethylene glycol 400. The findings suggest that polyethylene glycol 400 in contrast to glycerol and propylene glycol has the potential of increasing the vehicle-skin partition coefficient of oxybenzone when cosmetic products containing such an UV absorber are topically applied to the skin.

  20. Partitioning of Organic Ions to Muscle Protein: Experimental Data, Modeling, and Implications for in Vivo Distribution of Organic Ions.

    PubMed

    Henneberger, Luise; Goss, Kai-Uwe; Endo, Satoshi

    2016-07-05

    The in vivo partitioning behavior of ionogenic organic chemicals (IOCs) is of paramount importance for their toxicokinetics and bioaccumulation. Among other proteins, structural proteins including muscle proteins could be an important sorption phase for IOCs, because of their high quantity in the human and other animals' body and their polar nature. Binding data for IOCs to structural proteins are, however, severely limited. Therefore, in this study muscle protein-water partition coefficients (KMP/w) of 51 systematically selected organic anions and cations were determined experimentally. A comparison of the measured KMP/w with bovine serum albumin (BSA)-water partition coefficients showed that anionic chemicals sorb more strongly to BSA than to muscle protein (by up to 3.5 orders of magnitude), while cations sorb similarly to both proteins. Sorption isotherms of selected IOCs to muscle protein are linear (i.e., KMP/w is concentration independent), and KMP/w is only marginally influenced by pH value and salt concentration. Using the obtained data set of KMP/w a polyparameter linear free energy relationship (PP-LFER) model was established. The derived equation fits the data well (R(2) = 0.89, RMSE = 0.29). Finally, it was demonstrated that the in vitro measured KMP/w values of this study have the potential to be used to evaluate tissue-plasma partitioning of IOCs in vivo.

  1. Predicting solvent-water partitioning of charged organic species using quantum-chemically estimated Abraham pp-LFER solute parameters.

    PubMed

    Davis, Craig Warren; Di Toro, Dominic M

    2016-12-01

    Methods for obtaining accurate predictions of solvent-water partitioning for neutral organic chemicals (e.g., Kow) are well-established. However, methods that provide comparable accuracy are not available for predicting the solvent-water partitioning of ionic species. Previous methods for addressing charge contributions to solvent-water partitioning rely on charged solute descriptors which are obtained from regressions to neutral species descriptors as well as charged descriptors which are specific to unique charge-functionalities and structural moieties. This paper presents a method for obtaining Abraham poly-parameter linear free energy relationship (pp-LFER) descriptors using quantum chemical calculations and molecular structure, only. The method utilizes a large number of solvent-water systems to overcome large errors in individual quantum chemical computations of ionic solvent-water partition coefficients. The result is a single set of quantum-chemically estimated Abraham solute parameters (QCAP) which are solvent-independent, and can be used to predict the solvent-water partitioning of ionic species. Predictions of solvent-water partition coefficients for ionic species using quantum-chemically estimated Abraham parameters (QCAPs) are shown to provide improved accuracy compared over both existing Absolv-estimated Abraham solute parameters (AAP) as well as direct a priori quantum chemical (QC) calculations for partitioning of anionic solutes in 4 organic solvent-water systems (RMS = 0.740, 2.48 and 0.426 for the Absolv, QC and QCAP methods, respectively). For quaternary amine cations in the octanol-water system the RMS errors of the solvent-water partition coefficients were larger and similar between the two Abraham models (RMSE = 0.997 and 1.16, for the AAP and QCAP methods, respectively). Both methods showed significant improvement over direct QC calculations (RMSE = 2.82). Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Down-regulation of KORRIGAN-like endo-β-1,4-glucanase genes impacts carbon partitioning, mycorrhizal colonization and biomass production in Populus

    SciTech Connect

    Kalluri, Udaya C; Engle, Nancy L.; Bali, Garima; Jawdy, Sara S.; Sykes, Robert W.; Davis, Mark F.; Ragauskas, Arthur J.; Tuskan, Gerald A.; Tschaplinski, Timothy J.; Payyavula, Raja S.; Labbe, Jessy L.

    2016-10-04

    Here, a greater understanding of the genetic regulation of plant cell wall remodeling and the impact of modified cell walls on plant performance is important for the development of sustainable biofuel crops. Here, we studied the impact of down-regulating KORRIGAN-like cell wall biosynthesis genes, belonging to the endo-β-1,4-glucanase gene family, on Populus growth, metabolism and the ability to interact with symbiotic microbes. The reductions in cellulose content and lignin syringyl-to-guaiacyl unit ratio, and increase in cellulose crystallinity of cell walls of PdKOR RNAi plants corroborated the functional role of PdKOR in cell wall biosynthesis. Altered metabolism and reduced growth characteristics of RNAi plants revealed new implications on carbon allocation and partitioning. The distinctive metabolome phenotype comprised of a higher phenolic and salicylic acid content, and reduced lignin, shikimic acid and maleic acid content relative to control. Plant sustainability implications of modified cell walls on beneficial plant-microbe interactions were explored via co-culture with an ectomycorrhizal fungus, Laccaria bicolor. A significant increase in the mycorrhization rate was observed in transgenic plants, leading to measurable beneficial growth effects. These findings present new evidence for functional interconnectedness of cellulose biosynthesis pathway, metabolism and mycorrhizal association in plants, and further emphasize the consideration of the sustainability implications of plant trait improvement efforts.

  3. Virasoro constraint for Nekrasov instanton partition function

    NASA Astrophysics Data System (ADS)

    Kanno, Shoichi; Matsuo, Yutaka; Zhang, Hong

    2012-10-01

    We show that Nekrasov instanton partition function for SU( N ) gauge theories satisfies recursion relations in the form of U(1)+Virasoro constraints when β = 1. The constraints give a direct support for AGT conjecture for general quiver gauge theories.

  4. Merging Groups to Maximize Object Partition Comparison.

    ERIC Educational Resources Information Center

    Klastorin, T. D.

    1980-01-01

    The problem of objectively comparing two independently determined partitions of N objects or variables is discussed. A similarity measure based on the simple matching coefficient is defined and related to previously suggested measures. (Author/JKS)

  5. Connections between groundwater flow and transpiration partitioning.

    PubMed

    Maxwell, Reed M; Condon, Laura E

    2016-07-22

    Understanding freshwater fluxes at continental scales will help us better predict hydrologic response and manage our terrestrial water resources. The partitioning of evapotranspiration into bare soil evaporation and plant transpiration remains a key uncertainty in the terrestrial water balance. We used integrated hydrologic simulations that couple vegetation and land-energy processes with surface and subsurface hydrology to study transpiration partitioning at the continental scale. Both latent heat flux and partitioning are connected to water table depth, and including lateral groundwater flow in the model increases transpiration partitioning from 47 ± 13 to 62 ± 12%. This suggests that lateral groundwater flow, which is generally simplified or excluded in Earth system models, may provide a missing link for reconciling observations and global models of terrestrial water fluxes.

  6. Connections between groundwater flow and transpiration partitioning

    NASA Astrophysics Data System (ADS)

    Maxwell, Reed M.; Condon, Laura E.

    2016-07-01

    Understanding freshwater fluxes at continental scales will help us better predict hydrologic response and manage our terrestrial water resources. The partitioning of evapotranspiration into bare soil evaporation and plant transpiration remains a key uncertainty in the terrestrial water balance. We used integrated hydrologic simulations that couple vegetation and land-energy processes with surface and subsurface hydrology to study transpiration partitioning at the continental scale. Both latent heat flux and partitioning are connected to water table depth, and including lateral groundwater flow in the model increases transpiration partitioning from 47 ± 13 to 62 ± 12%. This suggests that lateral groundwater flow, which is generally simplified or excluded in Earth system models, may provide a missing link for reconciling observations and global models of terrestrial water fluxes.

  7. Niche saturation reveals resource partitioning among consumers.

    PubMed

    Northfield, Tobin D; Snyder, Gretchen B; Ives, Anthony R; Snyder, William E

    2010-03-01

    More diverse communities of consumers typically use more resources, which often is attributed to resource partitioning. However, experimentally demonstrating this role of resource partitioning in diverse communities has been difficult. We used an experimental response-surface design, varying intra- and interspecific consumer densities, to compare patterns of resource exploitation between simple and diverse communities of aphid predators. With increasing density, each single consumer species rapidly plateaued in its ability to extract more resources. This suggests intraspecific competition for a subset of the resource pool, a hallmark of resource partitioning. In contrast, more diverse-predator communities achieved greater overall resource depletion. By statistically fitting mechanistic models to the data, we demonstrated that resource partitioning rather than facilitation provides the better explanation for the observed differences in resource use between simple and diverse communities. This model-fitting approach also allowed us to quantify overlap in resource use by different consumer species.

  8. Merging Groups to Maximize Object Partition Comparison.

    ERIC Educational Resources Information Center

    Klastorin, T. D.

    1980-01-01

    The problem of objectively comparing two independently determined partitions of N objects or variables is discussed. A similarity measure based on the simple matching coefficient is defined and related to previously suggested measures. (Author/JKS)

  9. Cell Partition in Two Polymer Aqueous Phases

    NASA Technical Reports Server (NTRS)

    Harris, J. M.

    1985-01-01

    Partition of biological cells in two phase aqueous polymer systems is recognized as a powerful separation technique which is limited by gravity. The synthesis of new, selective polymer ligand conjugates to be used in affinity partition separations is of interest. The two most commonly used polymers in two phase partitioning are dextran and polyethylene glycol. A thorough review of the chemistry of these polymers was begun, particularly in the area of protein attachment. Preliminary studies indicate the importance in affinity partitioning of minimizing gravity induced randomizing forces in the phase separation process. The PEG-protein conjugates that were prepared appear to be ideally suited for achieving high quality purifications in a microgravity environment. An interesting spin-off of this synthetic work was the observation of catalytic activity for certain of our polymer derivatives.

  10. Cell Partition in Two Polymer Aqueous Phases

    NASA Technical Reports Server (NTRS)

    Harris, J. M.

    1985-01-01

    Partition of biological cells in two phase aqueous polymer systems is recognized as a powerful separation technique which is limited by gravity. The synthesis of new, selective polymer ligand conjugates to be used in affinity partition separations is of interest. The two most commonly used polymers in two phase partitioning are dextran and polyethylene glycol. A thorough review of the chemistry of these polymers was begun, particularly in the area of protein attachment. Preliminary studies indicate the importance in affinity partitioning of minimizing gravity induced randomizing forces in the phase separation process. The PEG-protein conjugates that were prepared appear to be ideally suited for achieving high quality purifications in a microgravity environment. An interesting spin-off of this synthetic work was the observation of catalytic activity for certain of our polymer derivatives.

  11. Reducing variance in batch partitioning measurements

    SciTech Connect

    Mariner, Paul E.

    2010-08-11

    The partitioning experiment is commonly performed with little or no attention to reducing measurement variance. Batch test procedures such as those used to measure K{sub d} values (e.g., ASTM D 4646 and EPA402 -R-99-004A) do not explain how to evaluate measurement uncertainty nor how to minimize measurement variance. In fact, ASTM D 4646 prescribes a sorbent:water ratio that prevents variance minimization. Consequently, the variance of a set of partitioning measurements can be extreme and even absurd. Such data sets, which are commonplace, hamper probabilistic modeling efforts. An error-savvy design requires adjustment of the solution:sorbent ratio so that approximately half of the sorbate partitions to the sorbent. Results of Monte Carlo simulations indicate that this simple step can markedly improve the precision and statistical characterization of partitioning uncertainty.

  12. Potential effect of cationic liposomes on interactions with oral bacterial cells and biofilms.

    PubMed

    Sugano, Marika; Morisaki, Hirobumi; Negishi, Yoichi; Endo-Takahashi, Yoko; Kuwata, Hirotaka; Miyazaki, Takashi; Yamamoto, Matsuo

    2016-01-01

    Although oral infectious diseases have been attributed to bacteria, drug treatments remain ineffective because bacteria and their products exist as biofilms. Cationic liposomes have been suggested to electrostatically interact with the negative charge on the bacterial surface, thereby improving the effects of conventional drug therapies. However, the electrostatic interaction between oral bacteria and cationic liposomes has not yet been examined in detail. The aim of the present study was to examine the behavior of cationic liposomes and Streptococcus mutans in planktonic cells and biofilms. Liposomes with or without cationic lipid were prepared using a reverse-phase evaporation method. The zeta potentials of conventional liposomes (without cationic lipid) and cationic liposomes were -13 and 8 mV, respectively, and both had a mean particle size of approximately 180 nm. We first assessed the interaction between liposomes and planktonic bacterial cells with a flow cytometer. We then used a surface plasmon resonance method to examine the binding of liposomes to biofilms. We confirmed the binding behavior of liposomes with biofilms using confocal laser scanning microscopy. The interactions between cationic liposomes and S. mutans cells and biofilms were stronger than those of conventional liposomes. Microscopic observations revealed that many cationic liposomes interacted with the bacterial mass and penetrated the deep layers of biofilms. In this study, we demonstrated that cationic liposomes had higher affinity not only to oral bacterial cells, but also biofilms than conventional liposomes. This electrostatic interaction may be useful as a potential drug delivery system to biofilms.

  13. Site partitioning for distributed redundant disk arrays

    NASA Technical Reports Server (NTRS)

    Mourad, Antoine N.; Fuchs, W. K.; Saab, Daniel G.

    1992-01-01

    Distributed redundant disk arrays can be used in a distributed computing system or database system to provide recovery in the presence of temporary and permanent failures of single sites. In this paper, we look at the problem of partitioning the sites into redundant arrays in such way that the communication costs for maintaining the parity information are minimized. We show that the partitioning problem is NP-complete and we propose two heuristic algorithms for finding approximate solutions.

  14. Automatic Data Partitioning on Distributed Memory Multiprocessors

    DTIC Science & Technology

    1990-10-01

    to the user. In this paper , we present a novel approach to the problem of automatic data partitioning. We introduce the notion of constraints on data...partitioning scheme for a program. Most of the current projects leave this tedious problem almost entirely to the user. In this paper , we present a novel...tedious. In this paper , we propose a strategy which would instead allow a parallelizing compiler I to come up with a suitable data distribution pattern

  15. Deriving the Hirshfeld partitioning using distance metrics

    SciTech Connect

    Heidar-Zadeh, Farnaz; Ayers, Paul W.; Bultinck, Patrick

    2014-09-07

    The atoms in molecules associated with the Hirshfeld partitioning minimize the generalized Hellinger-Bhattacharya distance to the reference pro-atom densities. Moreover, the reference pro-atoms can be chosen by minimizing the distance between the pro-molecule density and the true molecular density. This provides an alternative to both the heuristic “stockholder” and the mathematical information-theoretic interpretations of the Hirshfeld partitioning. These results extend to any member of the family of f-divergences.

  16. Trace element partitioning between mica- and amphibole-bearing garnet lherzolite and hydrous basanitic melt: 1. Experimental results and the investigation of controls on partitioning behaviour

    NASA Astrophysics Data System (ADS)

    Adam, John; Green, Trevor

    2006-07-01

    Thirty five minor and trace elements (Li, Be, B, Sc, Cu, Zn, Ga, Ge, As, Rb, Nb, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ce, Nd, Sm, Tb, Ho, Tm, Lu, Hf, Ta, W, Tl, Pb, Bi, Th and U) in experimentally produced near-liquidus phases, from a primitive nelpheline basanite from Bow Hill in Tasmania (Australia), were analysed by LAM ICP-MS. A number of halogens (F, Cl and I) were also analysed by electron microprobe. The analyses were used to determine mineral/melt partition coefficients for mica, amphibole, garnet, clinopyroxene, orthopyroxene and olivine for conditions close to multiple saturation of the basanite liquidus with garnet lherzolite (approximately 2.6 GPa and 1,200°C with 7.5 wt% of added H2O). A broader range of conditions was also investigated from 1.0 GPa and 1,025°C to 3.5 GPa and 1,190°C with 5-10 wt% of added H2O. The scope and comprehensiveness of the data allow them to be used for two purposes, these include the following: an investigation of some of the controlling influences on partition coefficients; and the compilation of a set partition coefficients that are directly relevant to the formation of the Bow Hill basanite magma by partial melting of mantle peridotite. Considering clinopyroxene, the mineral phase for which the most data were obtained, systematic correlations were found between pressure and temperature, mineral composition, cation radius and valence, and Δ G coulb (the coulombic potential energy produced by substituting a cation of mismatched valence into a crystallographic site). Δ G coulb is distinctly different for different crystallographic sites, including the M2 and M1 sites in clinopyroxene. These differences can be modelled as a function of variations in optimum valence (expressed as 1 sigma standard deviations) within individual M1 and M2 site populations.

  17. Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents.

    PubMed

    Cocalia, Violina A; Jensen, Mark P; Holbrey, John D; Spear, Scott K; Stepinski, Dominique C; Rogers, Robin D

    2005-06-07

    The extraction of both UO2(2+) and trivalent lanthanide and actinide ions (Am3+, Nd3+, Eu3+) by dialkylphosphoric or dialkylphosphinic acids from aqueous solutions into the ionic liquid, 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide has been studied and compared to extractions into dodecane. Radiotracer partitioning measurements show comparable patterns of distribution ratios for both the ionic liquid/aqueous and dodecane/aqueous systems, and the limiting slopes at low acidity indicate the partitioning of neutral complexes in both solvent systems. The metal ion coordination environment, elucidated from EXAFS and UV-visible spectroscopy measurements, is equivalent in the ionic liquid and dodecane solutions with coordination of the uranyl cation by two hydrogen-bonded extractant dimers, and of the trivalent cations by three extractant dimers. This is the first definitive report of a system where both the biphasic extraction equilibria and metal coordination environment are the same in an ionic liquid and a molecular organic solvent.

  18. Cation separations using a proton-ionizable macrocycle in a dual module hollow fiber membrane system

    SciTech Connect

    Izatt, R.M.; Lamb, J.D.; Bruening, R.L.; Chuan Wang; Edge, N.; Bradshaw, J.S.

    1993-01-01

    Separation of metal cations in aqueous solution using a proton-ionizable macrocycle in a dual module hollow fiber membrane system is described. The advantages of this system, such as easy access to all phases, rapid transport rates, and the potential for continuous operation are maintained with the proton-ionizable macrocycles which allow for proton driven transport. Transport is diffusion limited in the organic phase boundary layer near and on the fibers. Hence, the selectivity of the extraction system is maintained. Selective transport of Ag{sup +} over all other cations tested from neutral source phases and of K{sup +} over other alkali metal cations from basic source phases using a triazole-18-crown-6 carrier has been demonstrated. Selective K{sup +} transport from less basic source phases has been demonstrated using the more acidic thiopyridone-18-crown-6 ligand. However, the large aqueous partition of this ligand makes it difficult to maintain it in the organic phase. Design of the separation systems requires a knowledge of extraction equilibrium constants and partition coefficients. These data have been measured in order to understand these membrane systems.

  19. Partitioning of hydrophobic pesticides within a soil-water-anionic surfactant system.

    PubMed

    Wang, Peng; Keller, Arturo A

    2009-02-01

    Surfactants can be added to pesticide-contaminated soils to enhance the treatment efficiency of soil washing. Our results showed that pesticide (atrazine and diuron) partitioning and desorbability within a soil-water-anionic surfactant system is soil particle-size dependent and is significantly influenced by the presence of anionic surfactant. Anionic surfactant (linear alkylbenzene sulphonate, LAS) sorption was influenced by its complexation with both the soluble and exchangeable divalent cations in soils (e.g. Ca2+, Mg2+). In this study, we propose a new concept: soil system hardness which defines the total amount of soluble and exchangeable divalent cations associated with a soil. Our results showed that anionic surfactant works better with soils having lower soil system hardness. It was also found that the hydrophobic organic compounds (HOCs) sorbed onto the LAS-divalent cation precipitate, resulting in a significant decrease in the aqueous concentration of HOC. Our results showed that the effect of exchangeable cations and sorption of HOC onto the surfactant precipitates needs to be considered to accurately predict HOC behavior within soil-water-anionic surfactant systems.

  20. Matrix isolation technique for the study of some factors affecting the partitioning of trace elements. [using vibrational spectroscopy

    NASA Technical Reports Server (NTRS)

    Grzybowski, J. M.; Allen, R. O.

    1974-01-01

    The factors that affect the preferred positions of cations in ionic solid solutions were investigated utilizing vibrational spectroscopy. Solid solutions of the sulfate and chromate ions codoped with La(+3) and Ca(+2) in a KBr host lattice were examined as a function of the polyvalent cation concentration. The cation-anion pairing process was found to be random for Ca(+2), whereas the formation of La(+3)-SO4(-2) ion pairs with a C2 sub v bonding geometry is highly preferential to any type of La(+3)-CrO4(-2) ion pair formation. The relative populations of ion pair site configurations are discussed in terms of an energy-entropy competition model which can be applied to the partition of trace elements during magmatic processes.

  1. A novel method for measuring polymer-water partition coefficients.

    PubMed

    Zhu, Tengyi; Jafvert, Chad T; Fu, Dafang; Hu, Yue

    2015-11-01

    Low density polyethylene (LDPE) often is used as the sorbent material in passive sampling devices to estimate the average temporal chemical concentration in water bodies or sediment pore water. To calculate water phase chemical concentrations from LDPE concentrations accurately, it is necessary to know the LDPE-water partition coefficients (KPE-w) of the chemicals of interest. However, even moderately hydrophobic chemicals have large KPE-w values, making direct measurement experimentally difficult. In this study we evaluated a simple three phase system from which KPE-w can be determined easily and accurately. In the method, chemical equilibrium distribution between LDPE and a surfactant micelle pseudo-phase is measured, with the ratio of these concentrations equal to the LDPE-micelle partition coefficient (KPE-mic). By employing sufficient mass of polymer and surfactant (Brij 30), the mass of chemical in the water phase remains negligible, albeit in equilibrium. In parallel, the micelle-water partition coefficient (Kmic-w) is determined experimentally. KPE-w is the product of KPE-mic and Kmic-w. The method was applied to measure values of KPE-w for 17 polycyclic aromatic hydrocarbons, 37 polychlorinated biphenyls, and 9 polybrominated diphenylethers. These values were compared to literature values. Mass fraction-based chemical activity coefficients (γ) were determined in each phase and showed that for each chemical, the micelles and LDPE had nearly identical affinity.

  2. A Partition Function Approximation Using Elementary Symmetric Functions

    PubMed Central

    Anandakrishnan, Ramu

    2012-01-01

    In statistical mechanics, the canonical partition function can be used to compute equilibrium properties of a physical system. Calculating however, is in general computationally intractable, since the computation scales exponentially with the number of particles in the system. A commonly used method for approximating equilibrium properties, is the Monte Carlo (MC) method. For some problems the MC method converges slowly, requiring a very large number of MC steps. For such problems the computational cost of the Monte Carlo method can be prohibitive. Presented here is a deterministic algorithm – the direct interaction algorithm (DIA) – for approximating the canonical partition function in operations. The DIA approximates the partition function as a combinatorial sum of products known as elementary symmetric functions (ESFs), which can be computed in operations. The DIA was used to compute equilibrium properties for the isotropic 2D Ising model, and the accuracy of the DIA was compared to that of the basic Metropolis Monte Carlo method. Our results show that the DIA may be a practical alternative for some problems where the Monte Carlo method converge slowly, and computational speed is a critical constraint, such as for very large systems or web-based applications. PMID:23251504

  3. Metatranscriptome analyses indicate resource partitioning between diatoms in the field.

    PubMed

    Alexander, Harriet; Jenkins, Bethany D; Rynearson, Tatiana A; Dyhrman, Sonya T

    2015-04-28

    Diverse communities of marine phytoplankton carry out half of global primary production. The vast diversity of the phytoplankton has long perplexed ecologists because these organisms coexist in an isotropic environment while competing for the same basic resources (e.g., inorganic nutrients). Differential niche partitioning of resources is one hypothesis to explain this "paradox of the plankton," but it is difficult to quantify and track variation in phytoplankton metabolism in situ. Here, we use quantitative metatranscriptome analyses to examine pathways of nitrogen (N) and phosphorus (P) metabolism in diatoms that cooccur regularly in an estuary on the east coast of the United States (Narragansett Bay). Expression of known N and P metabolic pathways varied between diatoms, indicating apparent differences in resource utilization capacity that may prevent direct competition. Nutrient amendment incubations skewed N/P ratios, elucidating nutrient-responsive patterns of expression and facilitating a quantitative comparison between diatoms. The resource-responsive (RR) gene sets deviated in composition from the metabolic profile of the organism, being enriched in genes associated with N and P metabolism. Expression of the RR gene set varied over time and differed significantly between diatoms, resulting in opposite transcriptional responses to the same environment. Apparent differences in metabolic capacity and the expression of that capacity in the environment suggest that diatom-specific resource partitioning was occurring in Narragansett Bay. This high-resolution approach highlights the molecular underpinnings of diatom resource utilization and how cooccurring diatoms adjust their cellular physiology to partition their niche space.

  4. Certificate Revocation Using Fine Grained Certificate Space Partitioning

    NASA Astrophysics Data System (ADS)

    Goyal, Vipul

    A new certificate revocation system is presented. The basic idea is to divide the certificate space into several partitions, the number of partitions being dependent on the PKI environment. Each partition contains the status of a set of certificates. A partition may either expire or be renewed at the end of a time slot. This is done efficiently using hash chains.

  5. Software Partitioning Schemes for Advanced Simulation Computer Systems. Final Report.

    ERIC Educational Resources Information Center

    Clymer, S. J.

    Conducted to design software partitioning techniques for use by the Air Force to partition a large flight simulator program for optimal execution on alternative configurations, this study resulted in a mathematical model which defines characteristics for an optimal partition, and a manually demonstrated partitioning algorithm design which…

  6. The partitioning of Sc, Y, and the rare earth elements between high-Ca pyroxene and natural mafic to intermediate lavas at 1 atmosphere

    NASA Astrophysics Data System (ADS)

    Gallahan, W. E.; Nielsen, R. L.

    1992-06-01

    The effects of composition and temperature on the partitioning behavior of Sc, Y, and the rare earth elements (REEs) between high-Ca clinopyroxene and natural silicate melts were evaluated from doped experiments on natural mafic to intermediate composition lavas at 1 atmosphere pressure. Partition coefficients for these elements were found to be dependent on temperature and composition. The most important compositional parameters controlling clinopyroxene-melt partitioning for Y, Sc, and REEs are Al content of the liquid and pyroxene Ca content. Towards the goal of deriving expressions describing partitioning behavior, approximations were made of equilibrium constants for reactions involving a REE-Al component in the pyroxene. Regression of these equilibrium constants over the experimental temperature range (1180-1050°C) produced expressions which, when applied to the experimental glasses, reproduced the clinopyroxene trace element contents with precisions between 9 and 32% (1σ). The most important conclusion of this work is that pyroxene-melt partition coefficients for trivalent cations have different compositional dependencies than divalent cations because of the participation of Al in paired substitution. Values for high-Ca pyroxene Sc, Y, and REE partition coefficients have a range of over a factor of two between alkali basalts, andesites, and tholeiitic basalts (e.g., 0.2-0.7 for Sm at 1100°C). This represents a large proportion of the total range for D values from all mafic and intermediate magmas. Our contribution is to describe the parameters that control partitioning behavior. This will allow us to more accurately determine REE partitioning for specific systems.

  7. Cation disorder in shocked orthopyroxene.

    NASA Technical Reports Server (NTRS)

    Dundon, R. W.; Hafner, S. S.

    1971-01-01

    The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

  8. Core-mantle carbon partitioning during Earth accretion

    NASA Astrophysics Data System (ADS)

    Fichtner, C.; Schmidt, M. W.; Liebske, C.; Bouvier, A. S.; Baumgartner, L. P.

    2016-12-01

    When Earth was accreting, a lid-less magma ocean is thought to have covered the upper hundreds of km. During this stage, carbon was distributed between metallic and silicate melts, and a hot, potentially dense atmosphere. The metal segregated gravitationally from the magma ocean and carbon partitioned between the two melts. This partitioning constrains the size of the Earth's core and mantle carbon reservoirs and is experimentally investigated in this study. Experiments were conducted at 1.5-15 GPa and 1400-1800 °C, and the range of oxygen fugacities thought to have prevailed during most of the core formation period are targeted (IW -4 to +0.9). The experimental run products were analyzed by bulk and in-situ methods (Elemental Analyzer, SIMS). For the SIMS measurements, iron carbide, FeNiC-alloy and silicate melt standards were synthesized and measured independently. For bulk analyses, the two melts were gravitationally separated by a centrifuging piston cylinder. Starting materials have been prepared such that little redox work between the starting material and the capsule material (San Carlos olivine, synthetic forsterite) occurred during the experiment. Other capsule materials were also tested, but no meaningful partition coefficients could be measured because of iron loss. Results at 1.5 GPa and 1400-1500 °C show that carbon behaves strongly siderophile at lower oxygen fugacities (IW -1.5 to -2), reaching partition coefficients of DCmetal/silicate = 10- 165. This suggests that carbon contributes to the Earth's core density deficit. Assuming a likely present-day mantle carbon content of 120 ppm, the Earth's core may store 2.4 wt% carbon.

  9. Below-ground carbon flux and partitioning: global patterns and response to temperature

    Treesearch

    C.M. Litton; C.P. Giardina

    2008-01-01

    1. The fraction of gross primary production (GPP) that is total below-ground carbon flux (TBCF) and the fraction of TBCF that is below-ground net primary production (BNPP) represent globally significant C fluxes that are fundamental in regulating ecosystem C balance. However, global estimates of the partitioning of GPP to TBCF and of TBCF to BNPP, as well as the...

  10. Anti-arthritis activity of cationic materials

    PubMed Central

    Dong, Lei; Xia, Suhua; Chen, Huan; Chen, Jiangning; Zhang, Junfeng

    2010-01-01

    Abstract Cationic materials exhibit remarkable anti-inflammatory activity in experimental arthritis models. Our aim was to confirm this character of cationic materials and investigate its possible mechanism. Adjuvant-induced arthritis (AIA) models were used to test cationic materials for their anti-inflammatory activity. Cationic dextran (C-dextran) with different cationic degrees was used to investigate the influence of the cationic elements of materials on their anti-inflammatory ability. Peritoneal macrophages and spleen cells were used to test the expression of cytokines stimulated by cationic materials. Interferon (IFN)-γ receptor-deficient mice and macrophage-depleted rats were used to examine the possible mechanisms of the anti-inflammatory activity of cationic materials. In AIA models, different cationic materials shared similar anti-inflammatory characters. The anti-inflammatory activity of C-dextran increased with as the cationic degree increased. Cationic materials stimulated interleukin (IL)-12 expression in peritoneal macrophages, and strong stimulation of IFN-γ secretion was subsequently observed in spleen cells. In vivo experiments revealed that circulating IL-12 and IFN-γ were enhanced by the cationic materials. Using IFN-γ receptor knockout mice and macrophage-depleted rats, we found that IFN-γ and macrophages played key roles in the anti-inflammatory activity of the materials towards cells. We also found that neutrophil infiltration at inflammatory sites was reduced when AIA animals were treated with C-dextran. We propose that cationic signals act through an unknown receptor on macrophages to induce IL-12 secretion, and that IL-12 promotes the expression of IFN-γ by natural killer cells (or T cells). The resulting elevated systemic levels of IFN-γ inhibit arthritis development by preventing neutrophil recruitment to inflammatory sites. PMID:19538477

  11. Ambient Gas-Particle Partitioning of Tracers for Biogenic Oxidation

    SciTech Connect

    Isaacman-VanWertz, Gabriel; Yee, Lindsay D.; Kreisberg, Nathan M.; Wernis, Rebecca; Moss, Joshua A.; Hering, Susanne V.; de Sa, Suzanne; Martin, Scot T.; Alexander, Mikaela L.; Palm, Brett B.; Hu, Weiwei; Campuzano-Jost, Pedro; Day, Douglas; Jimenez, Jose L.; Riva, Matthieu; Surratt, Jason D.; Viegas, Juarez; Manzi, Antonio; Edgerton, Eric S.; Baumann, K.; Souza, Rodrigo A.; Artaxo, Paulo; Goldstein, Allen H.

    2016-08-23

    Exchange of atmospheric organic compounds between gas and particle phases is important in the production and chemistry of particle-phase mass but is poorly understood due to a lack of simultaneous measurements in both phases of individual compounds. Measurements of particle- and gas phase organic compounds are reported here for the southeastern United States and central Amazonia. Polyols formed from isoprene oxidation contribute 8% and 15% on average to particle-phase organic mass at these sites but are also observed to have substantial gas-phase concentrations contrary to many models that treat these compounds as nonvolatile. The results of the present study show that the gas-particle partitioning of approximately 100 known and newly observed oxidation products is not well explained by environmental factors (e.g., temperature). Compounds having high vapor pressures have higher particle fractions than expected from absorptive equilibrium partitioning models. These observations support the conclusion that many commonly measured biogenic oxidation products may be bound in low-volatility mass (e.g., accretion products, inorganic organic adducts) that decomposes to individual compounds on analysis. However, the nature and extent of any such bonding remains uncertain. Similar conclusions are reach for both study locations, and average particle fractions for a given compound are consistent within similar to 25% across measurement sites.

  12. Strong ion exchange in centrifugal partition extraction (SIX-CPE): effect of partition cell design and dimensions on purification process efficiency.

    PubMed

    Hamzaoui, Mahmoud; Hubert, Jane; Reynaud, Romain; Marchal, Luc; Foucault, Alain; Renault, Jean-Hugues

    2012-07-20

    The aim of this article was to evaluate the influence of the column design of a hydrostatic support-free liquid-liquid chromatography device on the process efficiency when the strong ion-exchange (SIX) development mode is used. The purification of p-hydroxybenzylglucosinolate (sinalbin) from a crude aqueous extract of white mustard seeds (Sinapis alba L.) was achieved on two types of devices: a centrifugal partition chromatograph (CPC) and a centrifugal partition extractor (CPE). They differ in the number, volume and geometry of their partition cells. The SIX-CPE process was evaluated in terms of productivity and sinalbin purification capability as compared to previously optimized SIX-CPC protocols that were carried out on columns of 200 mL and 5700 mL inner volume, respectively. The objective was to determine whether the decrease in partition cell number, the increase in their volume and the use of a "twin cell" design would induce a significant increase in productivity by applying higher mobile phase flow rate while maintaining a constant separation quality. 4.6g of sinalbin (92% recovery) were isolated from 25 g of a crude white mustard seed extract, in only 32 min and with a purity of 94.7%, thus corresponding to a productivity of 28 g per hour and per liter of column volume (g/h/LV(c)). Therefore, the SIX-CPE process demonstrates promising industrial technology transfer perspectives for the large-scale isolation of ionized natural products.

  13. Quantitative Measurement of Cationic Polymer Vector and Polymer/pDNA Polyplex Intercalation into the Cell Plasma Membrane

    PubMed Central

    Vaidyanathan, Sriram; Anderson, Kevin B.; Merzel, Rachel L.; Jacobovitz, Binyamin; Kaushik, Milan P.; Kelly, Christina N.; van Dongen, Mallory A.; Dougherty, Casey A.; Orr, Bradford G.; Holl, Mark M. Banaszak

    2016-01-01

    Cationic gene delivery agents (vectors) are important for delivering nucleotides, but are also responsible for cytotoxicity. Cationic polymers (L-PEI, jetPEI, and G5 PAMAM) at 1x to 100x the concentrations required for translational activity (protein expression) induced the same increase in plasma membrane current of HEK 293A cells (30-50 nA) as measured by whole cell patch-clamp. This indicates saturation of the cell membrane by the cationic polymers. The increased currents induced by the polymers are not reversible for over 15 minutes. Irreversibility on this time scale is consistent with a polymer-supported pore or carpet model and indicates that the cell is unable to clear the polymer from the membrane. For polyplexes, although the charge concentration was the same (at N: P ration of 10:1), G5 PAMAM and jetPEI polyplexes induced a much larger current increase (40- 50 nA) than L-PEI polyplexes (< 20 nA). Both free cationic lipid and lipid polyplexes induced a lower increase in current than cationic polymers (< 20 nA). To quantify the membrane bound material, partition constants were measured for both free vectors and polyplexes into the HEK 293A cell membrane using a dye influx assay. The partition constants of free vectors increased with charge density of the vectors. Polyplex partition constants did not show such a trend. The long lasting cell plasma permeability induced by exposure to the polymer vectors or the polyplexes provides a plausible mechanism for the toxicity and inflammatory response induced by exposure to these materials. PMID:25952271

  14. Quantitative Measurement of Cationic Polymer Vector and Polymer-pDNA Polyplex Intercalation into the Cell Plasma Membrane.

    PubMed

    Vaidyanathan, Sriram; Anderson, Kevin B; Merzel, Rachel L; Jacobovitz, Binyamin; Kaushik, Milan P; Kelly, Christina N; van Dongen, Mallory A; Dougherty, Casey A; Orr, Bradford G; Banaszak Holl, Mark M

    2015-06-23

    Cationic gene delivery agents (vectors) are important for delivering nucleotides, but are also responsible for cytotoxicity. Cationic polymers (L-PEI, jetPEI, and G5 PAMAM) at 1× to 100× the concentrations required for translational activity (protein expression) induced the same increase in plasma membrane current of HEK 293A cells (30-50 nA) as measured by whole cell patch-clamp. This indicates saturation of the cell membrane by the cationic polymers. The increased currents induced by the polymers are not reversible for over 15 min. Irreversibility on this time scale is consistent with a polymer-supported pore or carpet model and indicates that the cell is unable to clear the polymer from the membrane. For polyplexes, although the charge concentration was the same (at N/P ratio of 10:1), G5 PAMAM and jetPEI polyplexes induced a much larger current increase (40-50 nA) than L-PEI polyplexes (<20 nA). Both free cationic lipid and lipid polyplexes induced a lower increase in current than cationic polymers (<20 nA). To quantify the membrane bound material, partition constants were measured for both free vectors and polyplexes into the HEK 293A cell membrane using a dye influx assay. The partition constants of free vectors increased with charge density of the vectors. Polyplex partition constants did not show such a trend. The long lasting cell plasma permeability induced by exposure to the polymer vectors or the polyplexes provides a plausible mechanism for the toxicity and inflammatory response induced by exposure to these materials.

  15. Generalized linear solvation energy model applied to solute partition coefficients in ionic liquid-supercritical carbon dioxide systems.

    PubMed

    Planeta, Josef; Karásek, Pavel; Hohnová, Barbora; Sťavíková, Lenka; Roth, Michal

    2012-08-10

    Biphasic solvent systems composed of an ionic liquid (IL) and supercritical carbon dioxide (scCO(2)) have become frequented in synthesis, extractions and electrochemistry. In the design of related applications, information on interphase partitioning of the target organics is essential, and the infinite-dilution partition coefficients of the organic solutes in IL-scCO(2) systems can conveniently be obtained by supercritical fluid chromatography. The data base of experimental partition coefficients obtained previously in this laboratory has been employed to test a generalized predictive model for the solute partition coefficients. The model is an amended version of that described before by Hiraga et al. (J. Supercrit. Fluids, in press). Because of difficulty of the problem to be modeled, the model involves several different concepts - linear solvation energy relationships, density-dependent solvent power of scCO(2), regular solution theory, and the Flory-Huggins theory of athermal solutions. The model shows a moderate success in correlating the infinite-dilution solute partition coefficients (K-factors) in individual IL-scCO(2) systems at varying temperature and pressure. However, larger K-factor data sets involving multiple IL-scCO(2) systems appear to be beyond reach of the model, especially when the ILs involved pertain to different cation classes.

  16. Theoretical vibrational spectra and thermodynamics of organic semiconductive tetrathiafulvalene and its cation radical.

    PubMed

    Mukherjee, V; Singh, N P

    2014-01-03

    Molecular structure in optimum geometry and vibrational frequencies of pentafulvalene [bicyclopentyliden-2,4,2',4'-tetraene], tetrathiafulvalene [2,2'-bis(1,3-dithiolylidene)] and its cation are calculated. All the calculations are carried out by employing density functional theory incorporated with a suitable basis set. Normal coordinate analysis is also employed to scale the DFT calculated frequencies and to calculate potential energy distributions. The molecular structures and vibrational frequencies are compared for both the pentafulvalene and tetrathiafulvalene molecules. The effect upon geometry and vibrational frequencies of TTF due to charge transfer has also been studied. The vibrational partition function and hence, the thermodynamical properties, such as Helmholtz free energy, entropy, specific heat at constant volume and enthalpy are also calculated and compared for the title molecules. The reason of conductivity of tetrathiafulvalene has been tried to explain on the basis of molecular geometry and normal modes. Study of vibrational partition function exhibits that below 109 K, PFV starts to condense.

  17. Liquid Crystalline Polymers by Cationic Polymerization,

    DTIC Science & Technology

    1986-01-01

    cation mechanism of Scholl reaction the Lewis acid and by the benzylic carbocations . Hydride transfer to benzylic carbenium ions leads to methyl groups...reviewed. Examples from ring-opening, carbocationic , and radical-cation poly- merizations and oligomerizations are discussed. Accesion For DrIC TAB3...Examples from ring- opening, carbocationic , and radical-cation polymeri- zations and oligomerizations are discussed. INTRODUCTION This paper will

  18. Modification of potato peel waste with base hydrolysis and subsequent cationization.

    PubMed

    Lappalainen, Katja; Kärkkäinen, Johanna; Joensuu, Päivi; Lajunen, Marja

    2015-11-05

    Potato peel waste (PW) is a starch containing biomaterial produced in large amounts by food processing industry. In this work, the treatment of PW by alkaline hydrolysis and cationization in the water phase is reported. In order to improve the cationization of starch, PW was hydrolyzed by heating with alkaline (NaOH) ethanol solution (80%) in a water bath. The impact of variable molar ratios of anhydroglucose unit (AGU):NaOH, heating temperatures and times was studied on the degradation of starch and the molecular size distribution of the product. The hydrolyzed PW was cationized subsequently in water by using glycidyltrimethylammonium chloride and catalyzed by NaOH under microwave irradiation or in an oil bath. The impact of the various reaction conditions on the cationization and degree of substitution of starch was studied. The degree of substitution of the cationized starch varied in the range of 0-0.35. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Chemo-Enzymatic Synthesis of Linear and Branched Cationic Peptides: Evaluation as Gene Carriers.

    PubMed

    Ageitos, Jose Manuel; Chuah, Jo-Ann; Numata, Keiji

    2015-07-01

    Cationic peptides such as poly(l-lysine) and poly(l-arginine) are important tools for gene delivery since they can efficiently condense DNA. It is difficult to produce cationic peptides by recombinant bacterial expression, and its chemical synthesis requires several steps of protection/deprotection and toxic agents. Chemo-enzymatic synthesis of peptides is a clean chemistry technique that allows fast production under mild conditions. With the aim to simplify the production of cationic peptides, the present work develops an enzymatic reaction which enables the synthesis of linear cationic peptides and, through terminal functionalization with tris(2-aminoethyl)amine, of branched cationic peptide conjugates, which show improved DNA complex formation. Cytotoxicity and transfection efficiency of all the chemo-enzymatically synthesized cationic peptides are evaluated for their novel use as gene delivery agents. Synthesized peptides exhibit transfection efficiencies comparable to previously reported monodisperse peptides. Chemo-enzymatic synthesis opens the door for efficient production of cationic peptides for their use as gene delivery carriers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Partition behaviour of alkylphenols in crude oil/brine systems under subsurface conditions

    NASA Astrophysics Data System (ADS)

    Bennett, B.; Larter, S. R.

    1997-10-01

    Partition of organic solutes between oils and water in the subsurface is an important geochemical process occurring during petroleum migration and reservoiring, during water washing, and during petroleum production. Currently no data exists on the quantitative aspects of the partition process at subsurface conditions for solutes such as phenols and aromatic hydrocarbons which are major components of both oils and waters. We have constructed an equilibration device for oils and waters based on flow injection analysis principles to measure partition coefficients of alkylphenols in crude oil/brine systems under reservoir conditions. Concentrations of C 0C 2 alkylphenols in waters and solid phase extracts of crude oils produced in the device were determined by reverse phase high performance liquid chromatography with electrochemical detection (RP-HPLC-ED), partition coefficients being measured as a function of pressure (25-340 bar), temperature (25-150°C), and water salinity (0-100,000 mg/L sodium chloride) for a variety of oils. Partition coefficients for all compounds decreased with increasing temperature, increased with water salinity and crude oil bulk NSO content, and showed little change with varying pressure. These laboratory measurements, determined under conditions close to those typically encountered in petroleum reservoirs, suggest temperature, water salinity, and crude oil bulk NSO content will have important influence on oil-water partition processes in the subsurface during migration and water washing.

  1. Alternative trait combinations and secondary resource partitioning in sexually selected color polymorphism

    PubMed Central

    Takahashi, Yuma; Kawata, Masakado

    2013-01-01

    Resource partitioning within a species, trophic polymorphism is hypothesized to evolve by disruptive selection when intraspecific competition for certain resources is severe. However, in this study, we reported the secondary partitioning of oviposition resources without resource competition in the damselfly Ischnura senegalensis. In this species, females show color polymorphism that has been evolved as counteradaptation against sexual conflict. One of the female morphs is a blue-green (andromorph, male-like morph), whereas the other morph is brown (gynomorph). These female morphs showed alternative preferences for oviposition resources (plant tissues); andromorphs used fresh (greenish) plant tissues, whereas gynomorphs used decaying (brownish) plants tissues, suggesting that they chose oviposition resources on which they are more cryptic. In addition, the two-color morphs had different egg morphologies. Andromorphs have smaller and more elongated eggs, which seemed to adapt to hard substrates compared with those of gynomorphs. The resource partitioning in this species is achieved by morphological and behavioral differences between the color morphs that allow them to effectively exploit different resources. Resource partitioning in this system may be a by-product of phenotypic integration with body color that has been sexually selected, suggesting an overlooked mechanism of the evolution of resource partitioning. Finally, we discuss the evolutionary and ecological consequences of such resource partitioning. PMID:23919150

  2. Ligand interaction of human alpha 2-macroglobulin-alpha 2-macroglobulin receptor studied by partitioning in aqueous two-phase systems.

    PubMed

    Birkenmeier, G; Kunath, M

    1996-05-17

    Alpha 2-macroglobulin (alpha 2-M) is a major proteinase inhibitor in human blood and tissue. Besides its antiproteolytic potential, alpha 2-M was found to modulate antigen- and mitogen-driven immune responses and cell growth by binding and transporting distinct cytokines, growth factors and hormones. The inhibitor is cleared from circulation by binding to a multifunctional cellular receptor present on different cell types. Alpha 2-M, as well as its receptor, are capable of binding a variety of ligands. In the present study we have applied aqueous two-phase systems to analyze the interaction of IL-1 beta and alpha 2-M receptor to different forms of alpha 2-M. The partition of IL-1 beta was changed by addition of transformed alpha 2-M to the two-phase systems rather than by the native inhibitor. The interaction between IL-1 beta and alpha 2-M was enhanced by divalent cations. In addition, the complex formation between 125I-labelled receptor and alpha 2-M could clearly be demonstrated by partitioning. In the presence of divalent cations, transformed alpha 2-M, in contrast to the native inhibitor, effectively changed the partition of the receptor. However, the observed alteration of the partition coefficient was found to be less compared with the values obtained by partitioning of the receptor in the presence of whole plasma containing the inhibitor in equivalent concentrations. The results indicate that other components of the plasma exist which competitively bind to the receptor but independent of Ca2+-ions.

  3. Screening of pesticides for environmental partitioning tendency.

    PubMed

    Gramatica, Paola; Di Guardo, Antonio

    2002-06-01

    The partitioning tendency of chemicals, in this study pesticides in particular, into different environmental compartments depends mainly on the concurrent relevance of the physico-chemical properties of the chemical itself. To rank the pesticides according to their distribution tendencies in the different environmental compartments we propose a multivariate approach: the combination, by principal component analysis, of those physico-chemical properties like organic carbon partition coefficient (Koc), n-octanol/water partition coefficient (Kow), water solubility (Sw), vapour pressure and Henry's law constant (H) that are more relevant to the determination of environmental partitioning. The resultant macrovariables, the PC1 and PC2 scores here named leaching index (LIN) and volatality index (VIN), are proposed as preliminary environmental partitioning indexes in different media. These two indexes are modeled by theoretical molecular descriptors with satisfactory predictive power. Such an approach allows a rapid pre-determination and screening of the environmental distribution of pesticides starting only from the molecular structure of the pesticide, without any a priori knowledge of the physico-chemical properties.

  4. A biologically motivated partitioning of mortality.

    PubMed

    Carnes, B A; Olshansky, S J

    1997-01-01

    For over a century, actuaries and biologists working independently of each other have presented arguments for why total mortality needs to be partitioned into biologically meaningful subcomponents. These mortality partitions tended to overlook genetic diseases that are inherited because the partitions were motivated by a paradigm focused on aging. In this article, we combine and extend the concepts from these disciplines to develop a conceptual partitioning of total mortality into extrinsic and intrinsic causes of death. An extrinsic death is either caused or initiated by something that orginates outside the body of an individual, while an intrinsic death is either caused or initiated by processes that originate within the body. It is argued that extrinsic mortality has been a driving force in determining why we die when we do from intrinsic causes of death. This biologically motivated partitioning of mortality provides a useful perspective for researchers interested in comparative mortality analyses, the consequences of population aging, limits to human life expectancy, the progress made by the biomedical sciences against lethal diseases, and demographic models that predict the life expectancy of future populations.

  5. Octanol/air partitioning of polychlorinated biphenyls

    SciTech Connect

    Komp, P.; McLachlan, M.S.

    1997-12-01

    The partitioning of 16 polychlorinated biphenyls (PCBs) between air and 1-octanol was investigated using a fugacity meter. The measurements were conducted over an environmentally relevant temperature range (10--43 C). For a given congener the measured 1-octanol/air partition coefficient K{sub OA} was exponentially proportional to the reciprocal temperature. The enthalpy of phase change (octanol to air) {Delta}H{sub OA} ranged from 71 to 93 kJ/mol. Up to log K{sub OA} values of 9.37 (corresponding to 2,2{prime},3,4{prime},5{prime},6-hexachlorobiphenyl), the enthalpy of phase change was similar to the enthalpy of vaporization of the subcooled liquid PCB. For the less volatile congeners (log K{sub OA} > 9.37), the enthalpies of vaporization exceeded the enthalpies of phase change, the difference increasing with increasing log K{sub OA}. Solubilities of the PCBs in 1-octanol were calculated from the data, and the results were in excellent agreement with octanol solubilities calculated using the OCTASOL fragment method. A very good correlation between the measured octanol/air partition coefficients and values calculated from octanol/water and air/water partition coefficients was obtained. This yielded a method to estimate reliably the octanol/air partitioning of all PCB congeners.

  6. A modified approach to controller partitioning

    NASA Technical Reports Server (NTRS)

    Garg, Sanjay; Veillette, Robert J.

    1993-01-01

    The idea of computing a decentralized control law for the integrated flight/propulsion control of an aircraft by partitioning a given centralized controller is investigated. An existing controller partitioning methodology is described, and a modified approach is proposed with the objective of simplifying the associated controller approximation problem. Under the existing approach, the decentralized control structure is a variable in the partitioning process; by contrast, the modified approach assumes that the structure is fixed a priori. Hence, the centralized controller design may take the decentralized control structure into account. Specifically, the centralized controller may be designed to include all the same inputs and outputs as the decentralized controller; then, the two controllers may be compared directly, simplifying the partitioning process considerably. Following the modified approach, a centralized controller is designed for an example aircraft mode. The design includes all the inputs and outputs to be used in a specified decentralized control structure. However, it is shown that the resulting centralized controller is not well suited for approximation by a decentralized controller of the given structure. The results indicate that it is not practical in general to cast the controller partitioning problem as a direct controller approximation problem.

  7. Photosynthate Partitioning into Starch in Soybean Leaves

    PubMed Central

    Chatterton, N. Jerry; Silvius, John E.

    1979-01-01

    Photosynthesis, photosynthate partitioning into foliar starch, and translocation were investigated in soybean plants (Glycine max (L.) Merr. cv. Amsoy 71), grown under different photoperiods and photosynthetic periods to determine the controls of leaf starch accumulation. Starch accumulation rates in soybean leaves were inversely related to the length of the daily photosynthetic period under which the plants were grown. Photosynthetic period and not photoperiod per se appears to be the important factor. Plants grown in a 14-hour photosynthetic period partitioned approximately 60% of the daily foliar accumulation into starch whereas 7-hour plants partitioned about 90% of their daily foliar accumulation into starch. The difference in starch accumulation resulted from a change in photosynthate partitioning between starch and leaf residual dry weight. Residual dry weight is defined as leaf dry weight minus the weight of total nonstructural carbohydrates. Differences in photosynthate partitioning into starch were also associated with changes in photosynthetic and translocation rates, as well as with leaf and whole plant morphology. It is concluded that leaf starch accumulation is a programmed process and not simply the result of a limitation in translocation. PMID:16661047

  8. Synthesis and antimicrobial activity of small cationic amphipathic aminobenzamide marine natural product mimics and evaluation of relevance against clinical isolates including ESBL-CARBA producing multi-resistant bacteria.

    PubMed

    Igumnova, Elizaveta M; Mishchenko, Ekaterina; Haug, Tor; Blencke, Hans-Matti; Sollid, Johanna U Ericson; Fredheim, Elizabeth G Aarag; Lauksund, Silje; Stensvåg, Klara; Strøm, Morten B

    2016-11-15

    A library of small aminobenzamide derivatives was synthesised to explore a cationic amphipathic motif found in marine natural antimicrobials. The most potent compound E23 displayed minimal inhibitory concentrations (MICs) of 0.5-2μg/ml against several Gram-positive bacterial strains, including methicillin resistant Staphylococcus epidermidis (MRSE).E23 was also potent against 275 clinical isolates including Staphylococcus aureus, Enterococcus spp., Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae, as well as methicillin-resistant S. aureus (MRSA), vancomycin-resistant enterococci (VRE), and ESBL-CARBA producing multi-resistant Gram-negative bacteria. The study demonstrates how structural motifs found in marine natural antimicrobials can be a valuable source for making novel antimicrobial lead-compounds. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. EFFECT OF CATIONS ON ALUMINUM SPECIATION UNDER ALKALINE CONDITIONS

    SciTech Connect

    Taylor-Pashow, K.; Hobbs, D.

    2012-07-31

    A series of experiments were performed to examine the effect of metal cations common to high level waste on the phase of aluminum formed. Experiments were performed at temperature of 150 C, 75 C, and room temperature, either without additional metal cation, or with 0.01-0.2 molar equivalents of either Ni{sup 2+}, Fe{sup 3+}, Mn{sup 2+}, or Cr{sup 3+}. Results showed that temperature has the greatest effect on the phase obtained. At 150 C, boehmite is the only phase obtained, independent of the presence of other metal cations, with only one exception where a small amount of gibbsite was also detected in the product when 0.2 equivalents of Ni{sup 2+} was present. At 75 C, a mixture of phases is obtained, most commonly including bayerite and gibbsite; however, boehmite is also formed under some conditions, including in the absence of additional metal ion. At room temperature, in the absence of additional metal ion, a mixture of bayerite and gibbsite is obtained. The addition of another metal cation suppresses the formation of gibbsite, with a couple of exceptions (0.2 equivalents of Ni{sup 2+} or 0.01 equivalents of Cr{sup 3+}) where both phases are still obtained.

  10. Changing sources of base cations during ecosystem development, Hawaiian Islands

    NASA Astrophysics Data System (ADS)

    Kennedy, M. J.; Chadwick, O. A.; Vitousek, P. M.; Derry, L. A.; Hendricks, D. M.

    1998-11-01

    87Sr/86Sr evidence from a soil chronosequence in the Hawaiian Islands demonstrates that the atmosphere supplies >85% of putatively rock-derived Sr in older sites. Initially, bedrock is the dominant source for Sr and other lithophile elements such as Ca, but high rates of weathering and leaching of the substrate by 20 ka lead to a shift to atmospheric sources. The loss of weathering inputs coincides with other physio-chemical changes in the soil and results in a steep decline of base cations in the soil pool. While these patterns imply the potential for limitation of biological productivity by low base cation supply, the atmosphere provides a supply of base cations in excess of nutritional needs, even after nearly all rock-derived base cations have been leached from the soil. This raises the possibility that P limitation in terrestrial ecosystems may develop at least as much because of low rates of atmospheric deposition of P (relative to Ca, K, and other rock-derived elements) as because of its chemical interaction in soil.

  11. Cation-specific effects on enzymatic catalysis driven by interactions at the tunnel mouth.

    PubMed

    Štěpánková, Veronika; Paterová, Jana; Damborský, Jiří; Jungwirth, Pavel; Chaloupková, Radka; Heyda, Jan

    2013-05-30

    Cationic specificity which follows the Hofmeister series has been established for the catalytic efficiency of haloalkane dehalogenase LinB by a combination of molecular dynamics simulations and enzyme kinetic experiments. Simulations provided a detailed molecular picture of cation interactions with negatively charged residues on the protein surface, particularly at the tunnel mouth leading to the enzyme active site. On the basis of the binding affinities, cations were ordered as Na(+) > K(+) > Rb(+) > Cs(+). In agreement with this result, a steady-state kinetic analysis disclosed that the smaller alkali cations influence formation and productivity of enzyme-substrate complexes more efficiently than the larger ones. A subsequent systematic investigation of two LinB mutants with engineered charge in the cation-binding site revealed that the observed cation affinities are enhanced by increasing the number of negatively charged residues at the tunnel mouth, and vice versa, reduced by decreasing this number. However, the cation-specific effects are overwhelmed by strong electrostatic interactions in the former case. Interestingly, the substrate inhibition of the mutant LinB L177D in the presence of chloride salts was 7 times lower than that of LinB wild type in glycine buffer. Our work provides new insight into the mechanisms of specific cation effects on enzyme activity and suggests a potential strategy for suppression of substrate inhibition by the combination of protein and medium engineering.

  12. ToF-SIMS investigation of the cationization of several lubricant components

    NASA Astrophysics Data System (ADS)

    Gunst, Ullrich; Arlinghaus, Heinrich F.

    2008-12-01

    Cationization of molecular substances results often in the emission of characteristic peak patterns of secondary ions (SI) of these molecular species and is accompanied by matrix-enhanced SI yields. Besides the cationization of molecular overlayers on substrates of periodic table group IB elements, recent especially matrix-enhanced SIMS by physical vapor deposition (PVD) processes of Ag and Au was in the focus of investigations. In this work, selected lubricants components were investigated by ToF-SIMS, using different methods for cationization: (i) substrate cationization with periodic table group IA and IB elements (Cu, Ag, Cs, Au), (ii) cationization by dissolved salts of group IA and IB elements (Li, K, Na, Cu, Ag), and (iii) the in situ PVD by sputtering of group IB element targets (Cu, Ag, Au) by using the pulsed dual source column (DSC) of a ToF-SIMS instrument and thick lubricant layers on silicon wafers positioned in the immediate vicinity of the sputter crater. The Cu- and Ag-cationization of the investigated trimethylol-propane esters TMP(C8/C10) and poly-alpha-olefins (PAO) were possible with all specified methods, whereas only the esters were cationized also by alkaline elements (Li, Na, K, Cs). Au-cationization products were only observed for volatile PAO components that have deposited on the fresh cleaned surface of the sputter crater bottom of the Au-target.

  13. Amphibole-melt trace element partitioning of fractionating calc-alkaline magmas in the lower crust: an experimental study

    NASA Astrophysics Data System (ADS)

    Nandedkar, Rohit H.; Hürlimann, Niklaus; Ulmer, Peter; Müntener, Othmar

    2016-09-01

    Amphibole is one of the most important hydrous minerals of the middle and lower continental crust and plays a key role in the formation of intermediate to silica-rich magmas. This study reports a consistent set of amphibole trace element partition coefficients derived from fractional crystallization experiments at 0.7 GPa in a piston cylinder apparatus. Starting materials were doped with trace elements on the 20-40 ppm level and measured using laser ablation (LA)-ICP-MS. Amphibole is stable from 1010 to 730 °C and systematically changes its composition from pargasite to magnesiohornblende to cummingtonite, while coexisting liquids vary from andesite to dacite and rhyolite. Amphibole-liquid partition coefficients increase systematically with decreasing temperature and increasing SiO2 in the liquid. Potassium displays an inverse behavior and partitioning decreases with decreasing temperature. Rare earth element (REE) partition coefficients, assumed to occupy the M4 site within the amphibole structure, increase continuously up to one order of magnitude. The calculated lattice parameters, ideal cation radius ( r 0) and Young's modulus ( E) remain nearly constant with decreasing temperature. The high-field strength elements Zr and Hf that occupy the M2 site of the amphibole structure reveal a fivefold increase in partition coefficients with decreasing temperature and constant lattice parameters r 0 and E. Partition coefficients correlate with edenite, tschermaks and cummingtonite exchange vectors indicating that the maximum partition coefficient ( D 0) for an ideal cation radius increases with decreasing edenite component, while the latter decreases linearly with temperature. Regressing Amph/L D Ca against trace elements results in fair to excellent correlations ( r 2 0.55-0.99) providing a predictive tool to implement the trace element partition coefficients in numerical geochemical modeling. Our data result in positive correlations between Amph/L D Nb/Ta and Amph/L D

  14. New parallel SOR method by domain partitioning

    SciTech Connect

    Xie, D.; Adams, L.

    1999-07-01

    In this paper the authors propose and analyze a new parallel SOR method, the PSOR method, formulated by using domain partitioning and interprocessor data communication techniques. They prove that the PSOR method has the same asymptotic rate of convergence as the Red/Black (R/B) SOR method for the five-point stencil on both strip and block partitions, and as the four-color (R/B/G/O) SOR method for the nine-point stencil on strip partitions. They also demonstrate the parallel performance of the PSOR method on four different MIMD multiprocessors (a KSR1, an Intel Delta, a Paragon, and an IBM SP2). Finally, they compare the parallel performance of PSOR, R/B SOR, and R/B/G/O SOR. Numerical results on the Paragon indicate that PSOR is more efficient than R/B SOR and R/B/G/O SOR in both computation and interprocessor data communication.

  15. Partitioning a macroscopic system into independent subsystems

    NASA Astrophysics Data System (ADS)

    Delle Site, Luigi; Ciccotti, Giovanni; Hartmann, Carsten

    2017-08-01

    We discuss the problem of partitioning a macroscopic system into a collection of independent subsystems. The partitioning of a system into replica-like subsystems is nowadays a subject of major interest in several fields of theoretical and applied physics. The thermodynamic approach currently favoured by practitioners is based on a phenomenological definition of an interface energy associated with the partition, due to a lack of easily computable expressions for a microscopic (i.e. particle-based) interface energy. In this article, we outline a general approach to derive sharp and computable bounds for the interface free energy in terms of microscopic statistical quantities. We discuss potential applications in nanothermodynamics and outline possible future directions.

  16. Factorization of the bosonic partition function

    NASA Astrophysics Data System (ADS)

    Alsharafat, Ayed; Chair, Noureddine

    2017-04-01

    The factorization formula in the non-interacting quantum field theories that relates the fermionic partition function to the bosonic partition function considered recently by Chair (2013) [3] is obtained for the harmonic oscillator using the path integral formulation. By using the latter, the fermionic partition function turns out to be the ratio of two determinants of the same operator (∂τ + ω), whose eigenmodes being both periodic on the imaginary time intervals [ 0 , 2 β ], [ 0 , β ]. The natural generalization of the factorization formula when β →2m β is derived, such a factorization implies that the bosonic oscillator at temperature β can be seen as a non-interacting mixture of a bosonic oscillator at temperature 2m β and m-fermionic oscillators at different temperatures 2 m - k β, k = 1 , 2 , … , m. As a consequence, a general relationship between the bosonic and fermionic thermal zeta functions is deduced.

  17. Parallel algorithms for dynamically partitioning unstructured grids

    SciTech Connect

    Diniz, P.; Plimpton, S.; Hendrickson, B.; Leland, R.

    1994-10-01

    Grid partitioning is the method of choice for decomposing a wide variety of computational problems into naturally parallel pieces. In problems where computational load on the grid or the grid itself changes as the simulation progresses, the ability to repartition dynamically and in parallel is attractive for achieving higher performance. We describe three algorithms suitable for parallel dynamic load-balancing which attempt to partition unstructured grids so that computational load is balanced and communication is minimized. The execution time of algorithms and the quality of the partitions they generate are compared to results from serial partitioners for two large grids. The integration of the algorithms into a parallel particle simulation is also briefly discussed.

  18. (3+2)-Cycloaddition Reactions of Oxyallyl Cations

    PubMed Central

    Li, Hui; Wu, Jimmy

    2014-01-01

    The (3+2)-cycloaddition reaction involving oxyallyl cations has proven to be a versatile and efficient approach for the construction of five-membered carbo- and heterocycles, which are prevalent frameworks in natural products and pharmaceuticals. The following article will provide a brief summary of recent disclosures on this process featuring chemo-, regio- and diastereoselective oxyallyl cycloadditions with both electron-rich and electron-deficient 2π partners. PMID:25598556

  19. Cationic Zinc-Cadmium Alloy Clusters in Zeolite A

    SciTech Connect

    Readman,J.; Gameson, I.; Hriljac, J.; Anderson, P.

    2007-01-01

    Rietveld analysis of synchrotron powder X-ray diffraction data obtained from the product of the reaction of cadmium vapor with dehydrated zinc-exchanged zeolite A (LTA structure type) indicates the formation of cationic zinc-cadmium alloy clusters. The clusters are located in approximately 40% of the sodalite cages; the remaining 60% of the cages contain divalent zinc ions coordinated both to the oxygen atoms of the zeolite framework and to residual extra framework oxygen.

  20. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    DOEpatents

    Wasserman, Stephen R.; Anderson, Kenneth B.; Song, Kang; Yuchs, Steven E.; Marshall, Christopher L.

    1998-01-01

    A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate.

  1. Molecular dynamics simulation of secondary sorption behavior of montmorillonite modified by single chain quaternary ammonium cations.

    PubMed

    Zhao, Qian; Burns, Susan E

    2012-04-03

    Organoclays synthesized from single chain quaternary ammonium cations (QAC) ((CH(3))(3)NR(+)) exhibit different mechanisms for the sorption of nonpolar organic compounds as the length of the carbon chain is increased. The interaction between a nonpolar sorbate and an organoclay intercalated with small QACs has been demonstrated to be surface adsorption, while partitioning is the dominant mechanism in clays intercalated with long chain surfactants. This study presents the results of a molecular dynamics (MD) simulation performed to examine the sorption mechanisms of benzene in the interlayer of three organoclays with chain lengths ranging from 1 to 16 carbons: tetramethylammonium (TMA) clay; decyltrimethylammonium (DTMA) clay; and hexadecyltrimethylammonium (HDTMA) clay. The basis of the overall simulation was a combined force field of ClayFF and CVFF. In the simulations, organic cations were intercalated and benzene molecules were introduced to the interlayer, followed by whole system NPT and NVT time integration. Trajectories of all the species were recorded after the system reached equilibrium and subsequently analyzed. Simulation results confirmed that the arrangement of the surfactants controlled the sorption mechanism of organoclays. Benzene molecules were observed to interact directly with the clay surface in the presence of TMA cations, but tended to interact with the aliphatic chain of the HDTMA cation in the interlayer. The simulation provided insight into the nature of the adsorption/partitioning mechanisms in organoclays, and explained experimental observations of decreased versus increased uptake capacities as a function of increasing total organic carbon (TOC) for TMA clay and HDTMA clay, respectively. The transition of sorption mechanisms was also quantified with simulation of DTMA clay, with a chain length between that of TMA and HDTMA. Furthermore, this study suggested that at the molecular level, the controlling factor for the ultimate sorption

  2. Downstream processing of human antibodies integrating an extraction capture step and cation exchange chromatography.

    PubMed

    Azevedo, Ana M; Rosa, Paula A J; Ferreira, I Filipa; de Vries, J; Visser, T J; Aires-Barros, M Raquel

    2009-01-01

    In this paper we explore an alternative process for the purification of human antibodies from a Chinese hamster ovary (CHO) cell supernatant comprising a ligand-enhanced extraction capture step and cation exchange chromatography (CEX). The extraction of human antibodies was performed in an aqueous two-phase system (ATPS) composed of dextran and polyethylene glycol (PEG), in which the terminal hydroxyl groups of the PEG molecule were modified with an amino acid mimetic ligand in order to enhance the partition of the antibodies to the PEG-rich phase. This capture step was optimized using a design of experiments and a central composite design allowed the determination of the conditions that favor the partition of the antibodies to the phase containing the PEG diglutaric acid (PEG-GA) polymer, in terms of system composition. Accordingly, higher recovery yields were obtained for higher concentrations of PEG-GA and lower concentrations of dextran. The highest yield experimentally obtained was observed for an ATPS composed of 5.17% (w/w) dextran and 8% (w/w) PEG-GA. Higher purities were however predicted for higher concentrations of both polymers. A compromise between yield and purity was achieved using 5% dextran and 10% PEG-GA, which allowed the recovery of 82% of the antibodies with a protein purity of 96% and a total purity of 63%, determined by size-exclusion chromatography. ATPS top phases were further purified by cation exchange chromatography and it was observed that the most adequate cation exchange ligand was carboxymethyl, as the sulfopropyl ligand induced the formation of multi-aggregates or denatured forms. This column allowed the elution of 89% of the antibodies present in the top phase, with a protein purity of 100% and a total purity of 91%. The overall process containing a ligand-enhanced extraction step and a cation exchange chromatography step had an overall yield of 73%.

  3. Charge transfer dissociation (CTD) mass spectrometry of peptide cations using kiloelectronvolt helium cations.

    PubMed

    Hoffmann, William D; Jackson, Glen P

    2014-11-01

    A kiloelectronvolt beam of helium ions is used to ionize and fragment precursor peptide ions starting in the 1+ charge state. The electron affinity of helium cations (24.6 eV) exceeds the ionization potential of protonated peptides and can therefore be used to abstract an electron from--or charge exchange with--the isolated precursor ions. Kiloelectronvolt energies are used, (1) to overcome the Coulombic repulsion barrier between the cationic reactants, (2) to overcome ion-defocussing effects in the ion trap, and (3) to provide additional activation energy. Charge transfer dissociation (CTD) of the [M+H](+) precursor of Substance P gives product ions such as [M+H](2+•) and a dominant series of a ions in both the 1+ and 2+ charge states. These observations, along with the less-abundant a + 1 ions, are consistent with ultraviolet photodissociation (UVPD) results of others and indicate that C-C(α) cleavages are possible through charge exchange with helium ions. Although the efficiencies and timescale of CTD are not yet suitable for on-line chromatography, this new approach to ion activation provides an additional potential tool for the interrogation of gas phase ions.

  4. Anion-exchange displacement centrifugal partition chromatography.

    PubMed

    Maciuk, Alexandre; Renault, Jean-Hugues; Margraff, Rodolphe; Trébuchet, Philippe; Zèches-Hanrot, Monique; Nuzillard, Jean-Marc

    2004-11-01

    Ion-exchange displacement chromatography has been adapted to centrifugal partition chromatography. The use of an ionic liquid, benzalkonium chloride, as a strong anion-exchanger has proven to be efficient for the preparative separation of phenolic acid regioisomers. Multigram quantities of a mixture of three hydroxycinnamic acid isomers were separated using iodide as a displacer. The displacement process was characterized by a trapezoidal profile of analyte concentration in the eluate with narrow transition zones. By taking advantage of the partition rules involved in support-free liquid-liquid chromatography, a numerical separation model is proposed as a tool for preliminary process validation and further optimization.

  5. Chiral partition functions of quantum Hall droplets

    SciTech Connect

    Cappelli, Andrea Viola, Giovanni; Zemba, Guillermo R.

    2010-02-15

    Chiral partition functions of conformal field theory describe the edge excitations of isolated Hall droplets. They are characterized by an index specifying the quasiparticle sector and transform among themselves by a finite-dimensional representation of the modular group. The partition functions are derived and used to describe electron transitions leading to Coulomb blockade conductance peaks. We find the peak patterns for Abelian hierarchical states and non-Abelian Read-Rezayi states, and compare them. Experimental observation of these features can check the qualitative properties of the conformal field theory description, such as the decomposition of the Hilbert space into sectors, involving charged and neutral parts, and the fusion rules.

  6. Partitioning SAT Instances for Distributed Solving

    NASA Astrophysics Data System (ADS)

    Hyvärinen, Antti E. J.; Junttila, Tommi; Niemelä, Ilkka

    In this paper we study the problem of solving hard propositional satisfiability problem (SAT) instances in a computing grid or cloud, where run times and communication between parallel running computations are limited.We study analytically an approach where the instance is partitioned iteratively into a tree of subproblems and each node in the tree is solved in parallel.We present new methods for constructing partitions which combine clause learning and lookahead. The methods are incorporated into the iterative approach and its performance is demonstrated with an extensive comparison against the best sequential solvers in the SAT competition 2009 as well as against two efficient parallel solvers.

  7. Cochlear implant in incomplete partition type I.

    PubMed

    Berrettini, S; Forli, F; De Vito, A; Bruschini, L; Quaranta, N

    2013-02-01

    In this investigation, we report on 4 patients affected by incomplete partition type I submitted to cochlear implant at our institutions. Preoperative, surgical, mapping and follow-up issues as well as results in cases with this complex malformation are described. The cases reported in the present study confirm that cochlear implantation in patients with incomplete partition type I may be challenging for cochlear implant teams. The results are variable, but in many cases satisfactory, and are mainly related to the surgical placement of the electrode and residual neural nerve fibres. Moreover, in some cases the association of cochlear nerve abnormalities and other disabilities may significantly affect results.

  8. Metal cation uptake and reduction kinetics in microalgal cell culture

    NASA Astrophysics Data System (ADS)

    Kare, Anudeep

    This work was conducted to create a bio synthetic process for production of sustainable Nano materials, such as Noble metal nanoparticles with the use of living organisms as catalysts. Dactylococcus, Coelastrella and Chlamydomonas reinhardtii are the different species of algae used through which the Au and Ag nanoparticles are extracted. Under the appropriate bioprocess conditions phototrophic algal cell cultures can catalyze the conversion of soluble metal cations, such as trivalent gold cation (Au+3), to metallic gold nanoparticles (Au0 NP) and silver cation (Ag+) to metallic silver nanoparticles (Ag0 NP). The primary objective of this experiment is to identify the rate-limiting kinetics such as, mixing, biological, pH and so forth to see whether a scalable process can be proposed for production of these high valued materials. It is proposed in the literature that the reducing power required to drive this reaction is derived from the electron flux produced in the algae's photosynthetic apparatus. However, due to the lack of fundamental knowledge about the transport and kinetics, and therefore the bottlenecks and key process parameters, there is currently no scalable, controllable phototrophic system has been developed for the production of metallic nanoparticles.

  9. Partitioning peat respiration with stable carbon isotopes

    NASA Astrophysics Data System (ADS)

    Chanton, J.; Corbett, J.; Burdige, D. J.; Glaser, P. H.; Cooper, W. T.; Tfaily, M. M.

    2010-12-01

    Equimolar production of CO2 and CH4 is assumed with methanogenesis. However, in both field and incubation studies of peat respiration, CO2 is continually reported to be in higher concentrations than CH4. It was assumed that this is due to loss of methane with ebullition and additional CO2 production by HMW organic matter fermentation. To determine the proportions of CO2 formed from both organic matter fermentation and methanogenesis and to determine the percent loss of CH4 from ebullition, isotope mass balance equations were developed. The 13C-CO2 measured in pore water represents a mixture between the 13C-CO2 from organic matter decomposition and methanogenesis. By collecting and analyzing pore water samples for δ13C and concentrations of both CO2 and CH4, the proportion of CO2 formed from organic matter fermentation and methanogenesis was calculated. It was found that, at 0, 154, and 261 cm depths, the percent CO2 from methanogenesis was 56%, 88%, and 91%, and the percent CH4 loss due to ebullition was 69%, 79%, and 85%, respectively. These findings indicate that with increasing depth both the percent CO2 formed from methanogenesis and the percent CH4 lost increased. Incubation experiments consisting of peat from five depth intervals (30-40, 70-80, 130-140, 170-180, and 270-280cm) were used to determine the accuracy of the isotope mass balance equations based on in situ concentrations and isotopic values. Measurements were made biweekly for concentrations and δ13C of CO2 and CH4. The percents of CO2 formed from methanogenesis based on the isotope mass balance equations were found to be to be 53%, 44%, 12%, 51%, and 54% corresponding to the respective depth ranges. The ratios of CH4/CO2 measured were 51%, 39%, 4%, 41%, and 54%, respectively. The average standard deviation between these sample sets was found to be ± 3.5%. This indicates that the isotope mass balance equations are an appropriate model for determining in situ CO2 partitioning in these systems.

  10. Cation Recombination Energy/Coulomb Repulsion Effects in ETD/ECD as Revealed by Variation of Charge per Residue at Fixed Total Charge

    PubMed Central

    Mentinova, Marija; Crizer, David M.; Baba, Takashi; McGee, William M.; Glish, Gary L.; McLuckey, Scott A.

    2013-01-01

    Electron capture dissociation (ECD) and electron transfer dissociation (ETD) experiments in electrodynamic ion traps operated in the presence of a bath gas in the 1–10 mTorr range have been conducted on a common set of doubly protonated model peptides of the form X(AG)nX (X = lysine, arginine, or histidine, n=1, 2, or 4). The partitioning of reaction products was measured using thermal electrons, anions of azobenzene, and anions of 1,3-dinitrobenzene as reagents. Variation of n alters the charge per residue of the peptide cation, which affects recombination energy. The ECD experiments showed that H-atom loss is greatest for the n=1 peptides and decreases as n increases. Proton transfer in ETD, on the other hand, is expected to increase as charge per residue decreases (i.e., as n increases). These opposing tendencies were apparent in the data for the K(AG)nK peptides. H-atom loss appeared to be more prevalent in ECD than in ETD and is rationalized on the basis of either internal energy differences, differences in angular momentum transfer associated with the electron capture versus electron transfer processes, or a combination of the two. The histidine peptides showed the greatest extent of charge reduction without dissociation, the arginine peptides showed the greatest extent of side-chain cleavages, and the lysine peptides generally showed the greatest extent of partitioning into the c/z•-product ion channels. The fragmentation patterns for the complementary c- and z•-ions for ETD and ECD were found to be remarkably similar, particularly for the peptides with X = lysine. PMID:23568028

  11. Cation exchange capacity of pine bark substrates

    USDA-ARS?s Scientific Manuscript database

    Cation exchange capacity (CEC) is an important soil and substrate chemical property. It describes a substrate's ability to retain cation nutrients. Higher CEC values for a substrate generally result in greater amounts of nutrients retained in the substrate and available for plant uptake, and great...

  12. Tripodal Receptors for Cation and Anion Sensors

    PubMed Central

    Kuswandi, Bambang; Nuriman; Verboom, Willem; Reinhoudt, David N.

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selective recognition and sensing of cations and anions. Examples on the relationship between structure and selectivity towards cations and anions are described. Furthermore, their applications as potentiometric ion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  13. Partitioning of nitroxides in dispersed systems investigated by ultrafiltration, EPR and NMR spectroscopy.

    PubMed

    Krudopp, Heimke; Sönnichsen, Frank D; Steffen-Heins, Anja

    2015-08-15

    The partitioning behavior of paramagnetic nitroxides in dispersed systems can be determined by deconvolution of electron paramagnetic resonance (EPR) spectra giving equivalent results with the validated methods of ultrafiltration techniques (UF) and pulsed-field gradient nuclear magnetic resonance spectroscopy (PFG-NMR). The partitioning behavior of nitroxides with increasing lipophilicity was investigated in anionic, cationic and nonionic micellar systems and 10 wt% o/w emulsions. Apart from EPR spectra deconvolution, the PFG-NMR was used in micellar solutions as a non-destructive approach, while UF based on separation of very small volume of the aqueous phase. As a function of their substituent and lipophilicity, the proportions of nitroxides that were solubilized in the micellar or emulsion interface increased with increasing nitroxide lipophilicity for all emulsifier used. Comparing the different approaches, EPR deconvolution and UF revealed comparable nitroxide proportions that were solubilized in the interfaces. Those proportions were higher than found with PFG-NMR. For PFG-NMR self-diffusion experiments the reduced nitroxides were used revealing a high dynamic of hydroxylamines and emulsifiers. Deconvolution of EPR spectra turned out to be the preferred method for measuring the partitioning behavior of paramagnetic molecules as it enables distinguishing between several populations at their individual solubilization sites. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Partition of heavy metals in a tropical river system impacted by municipal waste.

    PubMed

    Duc, Trinh Anh; Loi, Vu Duc; Thao, Ta Thi

    2013-02-01

    A research program was established to identify the governing factors for the partition coefficient (K(D)) of heavy metals between suspended particulate and dissolved phases in the Day River system a tropical, highly alluvial aquatic system, in Vietnam. The targeted river system, draining an urbanized-industrialized catchment where discharged wastewater is mostly untreated, could be separated into the least impacted, pristine area, and the most impacted, polluted area. Organic matter degradation was shown to govern the variation of parameters like total organic carbon, biochemical oxygen demand, chemical oxygen demand, nutrients, conductivity, or redox potential. Heavy metals in both dissolved and particulate phases were enriched in severely polluted area because of wastewater inflow that contains concentrated metals and intensification of metal influx from sediment. Results show log K(D) in the order Mn < As < Zn < Hg < Ni < Cu < Cd < Co < Pb < Cr < Fe and As < Zn < Ni < Mn < Cr < Cu < Co < Fe in the polluted zone and the pristine zone, respectively. A decreasing tendency of partition coefficients of 11 heavy metals considered from the pristine to the impacted zones was observed. Three explanations for the difference are: (1) increase of solubility of most heavy metals in low redox potential, (2) competition for the binding sites with major and minor cations, and (3) complexation with dissolved organic matter concentrated in municipal waste impacted water. Apart from domestic waste impact, statistical analysis has contributed to identify the influence of climate condition and hydrological regime to the partition of heavy metals in the area.

  15. Partitioning of transition elements between orthopyroxene and clinopyroxene in peridotitic and websteritic xenoliths: New empirical geothermometers

    NASA Astrophysics Data System (ADS)

    Seitz, Hans-Michael; Altherr, Rainer; Ludwig, Thomas

    1999-12-01

    The partitioning of transition elements (Sc, Ti, V, Cr, Mn, Co, Ni) between orthopyroxene (opx) and clinopyroxene (cpx) in carefully selected garnet peridotite, spinel peridotite and garnet websterite xenoliths was determined by electron probe microanalyses (EPMA) and secondary ion mass spectrometry (SIMS). Xenoliths studied cover a wide compositional range and equilibrated under variable upper mantle conditions at temperatures between about 760 and 1370°C (two-pyroxene thermometer based on the enstatite-diopside solvus) and pressures between about 0.8 and 3.6 GPa (Al-in-opx and Ca-in-olivine barometers). We found that the partitioning of transition elements between opx and cpx (expressed as DM = concentration of element M in opx [cations per formula unit]/concentration of M in cpx [cations per formula unit]) is mainly controlled by temperature and to a much lesser degree by pressure. Variations in major element compositions of pyroxenes (e.g., variable XMg, Al IV or Na) have no influence on DM. For Sc, V, Cr, Mn, and Co, our data result in good correlations between ln DM and reciprocal absolute temperature, with correlation coefficients ( r) between 0.950 and 0.981. It is therefore possible to use the partitioning of these elements between opx and cpx from peridotites and websterites as geothermometers. On the basis of our data, we suggest the following empirical thermometer equations: TSc = [(17.64 · P + 5663)/(3.25 - ln DSc)], TV = [(18.06 · P + 3975)/(2.27 - ln DV)], TCr = [(11.00 · P + 2829)/(1.56 - ln DCr)], TMn = [(-0.20 · P - 2229)/(-1.37 - ln DMn)], TCo = [(-4.31 · P - 2358)/(-0.98 - ln DCo)], where T is the absolute temperature in Kelvin and P the pressure in kilobars. For Ti and Ni observed correlations between ln DM and 1/ T are less well defined.

  16. Cr-spinel/olivine and Cr-spinel/liquid nickel partition coefficients from natural samples

    NASA Astrophysics Data System (ADS)

    Li, Chusi; Ripley, Edward M.; Tao, Yan; Mathez, Edmond A.

    2008-03-01

    The Nernst partition coefficient of nickel ( DNi) between Cr-spinel and silicate melt in natural systems has been investigated using mid-ocean ridge basalts (MORB) and other volcanic rocks. The Cr-spinel/olivine DNi values in volcanic rocks are between 1.2 and 0.3, indicating that the Cr-spinel/liquid DNi values vary from slightly higher to significantly lower than the olivine/liquid DNi values in natural systems. The Cr-spinel/liquid DNi values from the MORB samples vary between 6 and 11, slightly higher than those from the S-bearing experiments of Satari et al. [Satari P., Brenan J. M., Horn I. and McDonough W. F. (2002) Experimental constraints on the sulfide- and chromite-silicate melt partitioning behavior of rhenium and platinum-group elements. Economic Geology97, 385-398]. The results of the MORB samples and the experiments of Satari et al. (2002) indicate a negative correlation between the Cr-spinel/liquid DNi and the XCr values in Cr-spinels (Cr cation number on the basis of 3 total cations in the spinel structure). Variations of Cr-spinel/liquid DNi values with Cr-spinel compositions can be estimated from an empirical equation based on the results of the MORB samples and the experiments by Satari et al. (2002). The choice of Cr-spinel/liquid DNi = 10 for numerical modeling by Righter et al. [Righter K., Leeman W. P. and Hervig R. L. (2006) Partitioning of Ni, Co, and V between spinel-structured oxides and silicate melts: importance of spinel composition. Chemical Geology227, 1-25] is reasonable for basaltic systems. For picritic and komatiitic systems a lower value of ˜5 is more appropriate.

  17. Structural and energetic study of cation-π-cation interactions in proteins.

    PubMed

    Pinheiro, Silvana; Soteras, Ignacio; Gelpí, Josep Lluis; Dehez, François; Chipot, Christophe; Luque, F Javier; Curutchet, Carles

    2017-04-12

    Cation-π interactions of aromatic rings and positively charged groups are among the most important interactions in structural biology. The role and energetic characteristics of these interactions are well established. However, the occurrence of cation-π-cation interactions is an unexpected motif, which raises intriguing questions about its functional role in proteins. We present a statistical analysis of the occurrence, composition and geometrical preferences of cation-π-cation interactions identified in a set of non-redundant protein structures taken from the Protein Data Bank. Our results demonstrate that this structural motif is observed at a small, albeit non-negligible frequency in proteins, and suggest a preference to establish cation-π-cation motifs with Trp, followed by Tyr and Phe. Furthermore, we have found that cation-π-cation interactions tend to be highly conserved, which supports their structural or functional role. Finally, we have performed an energetic analysis of a representative subset of cation-π-cation complexes combining quantum-chemical and continuum solvation calculations. Our results point out that the protein environment can strongly screen the cation-cation repulsion, leading to an attractive interaction in 64% of the complexes analyzed. Together with the high degree of conservation observed, these results suggest a potential stabilizing role in the protein fold, as demonstrated recently for a miniature protein (Craven et al., J. Am. Chem. Soc. 2016, 138, 1543). From a computational point of view, the significant contribution of non-additive three-body terms challenges the suitability of standard additive force fields for describing cation-π-cation motifs in molecular simulations.

  18. Generation of Bi-partite Polarization Correlation using Coherent States for Quantum Communication

    NASA Astrophysics Data System (ADS)

    Bollen, Viktor; Meng Sua, Yong; Fook Lee, Kim

    2010-03-01

    We present a novel scheme to generate bi-partite polarization correlation using coherent states for quantum communication. The scheme can be used for entanglement based quantum cryptography, where the bi-partite correlation will be protected by quantum noise. We perform experimental measurement on two independent coherent states with low mean photon numbers. A coherent state with polarization H is mixed with another coherent state with polarization V through a beam splitter. Polarization correlation is manipulated by using a quarter wave plate and a linear polarizer at each output of the beam splitter. The product signal obtained from the output modes contains bi-partite correlation and other noise terms. We obtain the bi-partite correlation function by employing mean-value measurement based on Stapp's formulation on the product signal, where the noise term is then averaged to zero due to randomness of quantum phase noise. The bi-partite correlation obtained by using two coherent states is quantum correlation because coherent states with low mean photon numbers are involved and the correlations are protected by randomness of quantum noise as inherited by mean photon number fluctuation and its associated phase fluctuation. Preparations for four types of coherent-state polarization correlation functions are also outlined.

  19. Projected partitioning of carbon by cotton and soybean crops in USA under climate change

    SciTech Connect

    Reddy, V.R.; Pachepsky, Y.A.

    1997-12-31

    The increase in atmospheric CO{sub 2} concentration and predicted global warming associated with climate change will have a substantial impact on agricultural production. Possible changes in crop yields have been an object of scrutiny in several extensive studies. Much less attention has been paid to changes in carbon partitioning between shoots and roots as affected by climate changes. This partitioning is essential both for carbon sequestration in soil and for aboveground biomass production. In our experiments with cotton plants, carbon allocation to roots has increased or decreased up to 30% with increase in [CO{sub 2}] depending on temperature levels and water availability. The carbon partitioning is a complex result of trade between roots needing to grow to supply water and nutrients and shoots needing to grow to supply carbon to the whole plant and to provide the reproduction. To estimate effects of the environment on the carbon partitioning, one has to use comprehensive crop simulators that explicitly account for the physiological processes resulting in the partitioning.

  20. Interactions among resource partitioning, sampling effect, and facilitation on the biodiversity effect: a modeling approach.

    PubMed

    Flombaum, Pedro; Sala, Osvaldo E; Rastetter, Edward B

    2014-02-01

    Resource partitioning, facilitation, and sampling effect are the three mechanisms behind the biodiversity effect, which is depicted usually as the effect of plant-species richness on aboveground net primary production. These mechanisms operate simultaneously but their relative importance and interactions are difficult to unravel experimentally. Thus, niche differentiation and facilitation have been lumped together and separated from the sampling effect. Here, we propose three hypotheses about interactions among the three mechanisms and test them using a simulation model. The model simulated water movement through soil and vegetation, and net primary production mimicking the Patagonian steppe. Using the model, we created grass and shrub monocultures and mixtures, controlled root overlap and grass water-use efficiency (WUE) to simulate gradients of biodiversity, resource partitioning and facilitation. The presence of shrubs facilitated grass growth by increasing its WUE and in turn increased the sampling effect, whereas root overlap (resource partitioning) had, on average, no effect on sampling effect. Interestingly, resource partitioning and facilitation interacted so the effect of facilitation on sampling effect decreased as resource partitioning increased. Sampling effect was enhanced by the difference between the two functional groups in their efficiency in using resources. Morphological and physiological differences make one group outperform the other; once these differences were established further differences did not enhance the sampling effect. In addition, grass WUE and root overlap positively influence the biodiversity effect but showed no interactions.

  1. Diel and Seasonal Behavior of Canopy Photosynthesis Revealed by Novel Isotopic Flux Partitioning in a Temperate Forest

    NASA Astrophysics Data System (ADS)

    Wehr, R. A.; Munger, J. W.; McManus, J. B.; Nelson, D. D.; Zahniser, M. S.; Saleska, S. R.

    2013-12-01

    Conventional methods for partitioning the net ecosystem-atmosphere exchange (NEE) of CO2 into gross primary production (GPP) and ecosystem respiration (R) work by extrapolating GPP or R using an empirical function fit to a week or a month of data. Accordingly, these methods do not allow investigation of short-term (e.g. diel) deviations of GPP or R from their monthly average behaviors. Moreover, these methods assume that daytime R is either constant or a smoothly varying function of temperature. Isotopic partitioning is an alternative that involves no assumptions about the behavior of R or GPP (though it requires knowledge or assumptions about the isotopic fractionations occurring in and around the leaves) and which allows for the investigation of diel variations because each flux measurement is partitioned separately. A novel isotopic flux partitioning approach using our unique long-term isotopic CO2 eddy flux record at the Harvard Forest reveals significant differences in both the diel and the seasonally averaged behavior of GPP as compared to conventional partitioning. At the diel timescale, large (~10 μmol m-2 s-1), rapid (~2 hours) variations in the respiratory component of measured NEE associated with subtle changes in wind direction (due to the breakdown of the basic EC assumption of horizontal landscape homogeneity) are misattributed to GPP by conventional partitioning, leading to inconsistency in the response of GPP to photosynthetically active radiation (PAR). Isotopically partitioned GPP responds much more consistently to PAR, and the seasonally averaged light response curve of isotopically partitioned GPP is much more linear than that of conventionally partitioned GPP (after controlling for the leaf-air water vapor gradient), suggesting that unsaturated (steeply inclined) leaves perform most of the canopy photosynthesis (Figure 1). The behavior of isotopically partitioned GPP follows largely from the observed behavior of the canopy-integrated stomatal

  2. Temperature-induced vesicle to micelle transition in cationic/cationic mixed surfactant systems.

    PubMed

    Yang, Yanjuan; Liu, Lifei; Huang, Xin; Tan, Xiuniang; Luo, Tian; Li, Wei

    2015-12-07

    Temperature-induced vesicle to micelle transition (VMT), which has rarely been reported in cationic/cationic mixed surfactant systems, was systemically studied in a didodecyldimethylammonium bromide (DDAB)/dodecyltrimethylammonium chloride (DTAC) aqueous solution. We investigated the effect of temperature on DDAB/DTAC aqueous solutions by means of turbidity, conductivity, cryo-TEM, a UV-vis spectrophotometer, and a steady-state fluorescence spectrometer. It was found that increasing temperature could induce the transformation from the vesicle to the micelle in this cationic/cationic mixed surfactant system. The degree of transformation can be easily controlled by the operation temperature. Additionally, by adjusting the proportion of the mixed cationic/cationic systems and employing cationic surfactants with different chain-lengths, we were able to conclude that the hydrophobic tail length of the surfactant affects the aggregation behavior of cationic/cationic mixed surfactant systems as a function of temperature. It is universal to induce the transformation from the vesicle to the micelle by temperature in cationic/cationic mixed surfactant systems. A possible mechanism for the temperature-induced VMT was proposed based on the experimental results.

  3. Partitioning and lipophilicity in quantitative structure-activity relationships.

    PubMed Central

    Dearden, J C

    1985-01-01

    The history of the relationship of biological activity to partition coefficient and related properties is briefly reviewed. The dominance of partition coefficient in quantitation of structure-activity relationships is emphasized, although the importance of other factors is also demonstrated. Various mathematical models of in vivo transport and binding are discussed; most of these involve partitioning as the primary mechanism of transport. The models describe observed quantitative structure-activity relationships (QSARs) well on the whole, confirming that partitioning is of key importance in in vivo behavior of a xenobiotic. The partition coefficient is shown to correlate with numerous other parameters representing bulk, such as molecular weight, volume and surface area, parachor and calculated indices such as molecular connectivity; this is especially so for apolar molecules, because for polar molecules lipophilicity factors into both bulk and polar or hydrogen bonding components. The relationship of partition coefficient to chromatographic parameters is discussed, and it is shown that such parameters, which are often readily obtainable experimentally, can successfully supplant partition coefficient in QSARs. The relationship of aqueous solubility with partition coefficient is examined in detail. Correlations are observed, even with solid compounds, and these can be used to predict solubility. The additive/constitutive nature of partition coefficient is discussed extensively, as are the available schemes for the calculation of partition coefficient. Finally the use of partition coefficient to provide structural information is considered. It is shown that partition coefficient can be a valuable structural tool, especially if the enthalpy and entropy of partitioning are available. PMID:3905374

  4. ApoER2 expression increases Aβ production while decreasing Amyloid Precursor Protein (APP) endocytosis: Possible role in the partitioning of APP into lipid rafts and in the regulation of γ-secretase activity

    PubMed Central

    Fuentealba, Rodrigo A; Barría, Maria Ines; Lee, Jiyeon; Cam, Judy; Araya, Claudia; Escudero, Claudia A; Inestrosa, Nibaldo C; Bronfman, Francisca C; Bu, Guojun; Marzolo, Maria-Paz

    2007-01-01

    Background The generation of the amyloid-β peptide (Aβ) through the proteolytic processing of the amyloid precursor protein (APP) is a central event in the pathogenesis of Alzheimer's disease (AD). Recent studies highlight APP endocytosis and localization to lipid rafts as important events favoring amyloidogenic processing. However, the precise mechanisms underlying these events are poorly understood. ApoER2 is a member of the low density lipoprotein receptor (LDL-R) family exhibiting slow endocytosis rate and a significant association with lipid rafts. Despite the important neurophysiological roles described for ApoER2, little is known regarding how ApoER2 regulates APP trafficking and processing. Results Here, we demonstrate that ApoER2 physically interacts and co-localizes with APP. Remarkably, we found that ApoER2 increases cell surface APP levels and APP association with lipid rafts. The increase of cell surface APP requires the presence of ApoER2 cytoplasmic domain and is a result of decreased APP internalization rate. Unexpectedly, ApoER2 expression correlated with a significant increase in Aβ production and reduced levels of APP-CTFs. The increased Aβ production was dependent on the integrity of the NPxY endocytosis motif of ApoER2. We also found that expression of ApoER2 increased APP association with lipid rafts and increased γ-secretase activity, both of which might contribute to increased Aβ production. Conclusion These findings show that ApoER2 negatively affects APP internalization. However, ApoER2 expression stimulates Aβ production by shifting the proportion of APP from the non-rafts to the raft membrane domains, thereby promoting β-secretase and γ-secretase mediated amyloidogenic processing and also by incrementing the activity of γ-secretase. PMID:17620134

  5. ApoER2 expression increases Abeta production while decreasing Amyloid Precursor Protein (APP) endocytosis: Possible role in the partitioning of APP into lipid rafts and in the regulation of gamma-secretase activity.

    PubMed

    Fuentealba, Rodrigo A; Barría, Maria Ines; Lee, Jiyeon; Cam, Judy; Araya, Claudia; Escudero, Claudia A; Inestrosa, Nibaldo C; Bronfman, Francisca C; Bu, Guojun; Marzolo, Maria-Paz

    2007-07-09

    The generation of the amyloid-beta peptide (Abeta) through the proteolytic processing of the amyloid precursor protein (APP) is a central event in the pathogenesis of Alzheimer's disease (AD). Recent studies highlight APP endocytosis and localization to lipid rafts as important events favoring amyloidogenic processing. However, the precise mechanisms underlying these events are poorly understood. ApoER2 is a member of the low density lipoprotein receptor (LDL-R) family exhibiting slow endocytosis rate and a significant association with lipid rafts. Despite the important neurophysiological roles described for ApoER2, little is known regarding how ApoER2 regulates APP trafficking and processing. Here, we demonstrate that ApoER2 physically interacts and co-localizes with APP. Remarkably, we found that ApoER2 increases cell surface APP levels and APP association with lipid rafts. The increase of cell surface APP requires the presence of ApoER2 cytoplasmic domain and is a result of decreased APP internalization rate. Unexpectedly, ApoER2 expression correlated with a significant increase in Abeta production and reduced levels of APP-CTFs. The increased Abeta production was dependent on the integrity of the NPxY endocytosis motif of ApoER2. We also found that expression of ApoER2 increased APP association with lipid rafts and increased gamma-secretase activity, both of which might contribute to increased Abeta production. These findings show that ApoER2 negatively affects APP internalization. However, ApoER2 expression stimulates Abeta production by shifting the proportion of APP from the non-rafts to the raft membrane domains, thereby promoting beta-secretase and gamma-secretase mediated amyloidogenic processing and also by incrementing the activity of gamma-secretase.

  6. Zr partitioning and kinetics and mechanism

    NASA Technical Reports Server (NTRS)

    Taylor, L. A.

    1973-01-01

    The results of investigations concerning the cooling histories of lunar rocks are reported. Publications resulting from this research are listed. Studies discussed include the partitioning of Zr between FeTi03 and Fe2Ti04 in the presence of Fe + Zr02, and ulvospinel reduction.

  7. Hydrologic transport and partitioning of phosphorus fractions

    NASA Astrophysics Data System (ADS)

    Berretta, C.; Sansalone, J.

    2011-06-01

    SummaryPhosphorus (P) in rainfall-runoff partitions between dissolved and particulate matter (PM) bound phases. This study investigates the transport and partitioning of P to PM fractions in runoff from a landscaped and biogenically-loaded carpark in Gainesville, FL (GNV). Additionally, partitioning and concentration results are compared to a similarly-sized concrete-paved source area of a similar rainfall depth frequency distribution in Baton Rouge, LA (BTR), where in contrast vehicular traffic represents the main source of pollutants. Results illustrate that concentrations of P fractions (dissolved, suspended, settleable and sediment) for GNV are one to two orders of magnitude higher than BTR. Despite these differences the dissolved fraction ( f d) and partitioning coefficient ( K d) distributions are similar, illustrating that P is predominantly bound to PM fractions. Examining PM size fractions, specific capacity for P (PSC) indicates that the P concentration order is suspended > settleable > sediment for GNV, similarly to BTR. For GNV the dominant PM mass fraction is sediment (>75 μm), while the mass of P is distributed predominantly between sediment and suspended (<25 μm) fractions since these PM mass fractions dominated the settleable one. With respect to transport of PM and P fractions the predominance of events for both areas is mass-limited first-flush, although each fraction illustrated unique washoff parameters. However, while transport is predominantly mass-limited, the transport of each PM and P fraction is influenced by separate hydrologic parameters.

  8. Application of partition technology to particle electrophoresis

    NASA Technical Reports Server (NTRS)

    Van Alstine, James M.; Harris, J. Milton; Karr, Laurel J.; Bamberger, Stephan; Matsos, Helen C.; Snyder, Robert S.

    1989-01-01

    The effects of polymer-ligand concentration on particle electrophoretic mobility and partition in aqueous polymer two-phase systems are investigated. Polymer coating chemistry and affinity ligand synthesis, purification, and analysis are conducted. It is observed that poly (ethylene glycol)-ligands are effective for controlling particle electrophoretic mobility.

  9. 25 CFR 152.33 - Partition.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER ISSUANCE OF PATENTS IN FEE, CERTIFICATES OF COMPETENCY, REMOVAL OF RESTRICTIONS, AND SALE OF CERTAIN INDIAN LANDS Partitions in Kind of Inherited Allotments § 152..., regardless of their competency, patents in fee to be issued to the competent heirs for their shares and...

  10. 25 CFR 152.33 - Partition.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER ISSUANCE OF PATENTS IN FEE, CERTIFICATES OF COMPETENCY, REMOVAL OF RESTRICTIONS, AND SALE OF CERTAIN INDIAN LANDS Partitions in Kind of Inherited Allotments § 152..., regardless of their competency, patents in fee to be issued to the competent heirs for their shares and...

  11. 25 CFR 152.33 - Partition.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER ISSUANCE OF PATENTS IN FEE, CERTIFICATES OF COMPETENCY, REMOVAL OF RESTRICTIONS, AND SALE OF CERTAIN INDIAN LANDS Partitions in Kind of Inherited Allotments § 152..., regardless of their competency, patents in fee to be issued to the competent heirs for their shares and...

  12. 25 CFR 152.33 - Partition.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER ISSUANCE OF PATENTS IN FEE, CERTIFICATES OF COMPETENCY, REMOVAL OF RESTRICTIONS, AND SALE OF CERTAIN INDIAN LANDS Partitions in Kind of Inherited Allotments § 152..., regardless of their competency, patents in fee to be issued to the competent heirs for their shares and...

  13. 25 CFR 152.33 - Partition.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER ISSUANCE OF PATENTS IN FEE, CERTIFICATES OF COMPETENCY, REMOVAL OF RESTRICTIONS, AND SALE OF CERTAIN INDIAN LANDS Partitions in Kind of Inherited Allotments § 152..., regardless of their competency, patents in fee to be issued to the competent heirs for their shares and...

  14. Mapping Pesticide Partition Coefficients By Electromagnetic Induction

    USDA-ARS?s Scientific Manuscript database

    A potential method for reducing pesticide leaching is to base application rates on the leaching potential of a specific chemical and soil combination. However, leaching is determined in part by the partitioning of the chemical between the soil and soil solution, which varies across a field. Standard...

  15. A Partition Formula for Fibonacci Numbers

    NASA Astrophysics Data System (ADS)

    Fahr, Philipp; Ringerl, Claus Michael

    2008-02-01

    We present a partition formula for the even index Fibonacci numbers. The formula is motivated by the appearance of these Fibonacci numbers in the representation theory of the socalled 3-Kronecker quiver, i.e., the oriented graph with two vertices and three arrows in the same direction.

  16. Solute partitioning and filtration by extracellular matrices

    PubMed Central

    Hofmann, Christina L.; Ferrell, Nicholas; Schnell, Lisa; Dubnisheva, Anna; Zydney, Andrew L.; Yurchenco, Peter D.; Roy, Shuvo

    2009-01-01

    The physiology of glomerular filtration remains mechanistically obscure despite its importance in disease. The correspondence between proteinuria and foot process effacement suggests podocytes as the locus of the filtration barrier. If so, retained macromolecules ought to accumulate at the filtration barrier, an effect called concentration polarization. Literature data indicate macromolecule concentrations decrease from subendothelial to subepithelial glomerular basement membrane (GBM), as would be expected if the GBM were itself the filter. The objective of this study was to obtain insights into the possible role of the GBM in protein retention by performing fundamental experimental and theoretical studies on the properties of three model gels. Solute partitioning and filtration through thin gels of a commercially available laminin-rich extracellular matrix, Matrigel, were measured using a polydisperse polysaccharide tracer molecule, Ficoll 70. Solute partitioning into laminin gels and lens basement membrane (LBM) were measured using Ficoll 70. A novel model of a laminin gel was numerically simulated, as well as a mixed structure-random-fiber model for LBM. Experimental partitioning was predicted by numerical simulations. Sieving coefficients through thin gels of Matrigel were size dependent and strongly flux dependent. The observed flux dependence arose from compression of the gel in response to the applied pressure. Gel compression may alter solute partitioning into extracellular matrix at physiologic pressures present in the glomerular capillary. This suggests a physical mechanism coupling podocyte structure to permeability characteristics of the GBM. PMID:19587146

  17. Partitioning of selected antioxidants in mayonnaise.

    PubMed

    Jacobsen, C; Schwarz, K; Stöckmann, H; Meyer, A S; Adler-Nissen, J

    1999-09-01

    This study examined partitioning of alpha-, beta-, and gamma-tocopherol and six polar antioxidants (Trolox, ferulic acid, caffeic acid, propyl gallate, gallic acid, and catechin) in mayonnaise. Partitioning of antioxidants between different phases was determined after separation of mayonnaise by either (a) centrifugation + ultracentrifugation or (b) centrifugation + dialysis. Antioxidants partitioned in accordance with their chemical structure and polarity: Tocopherols were concentrated in the oil phase (93-96%), while the proportion of polar antioxidants in the oil phase ranged from 0% (gallic acid and catechin) to 83% (Trolox). Accordingly, proportions of 6% (Trolox) to 80% (gallic acid and catechin) were found in the aqueous phase. Similar trends were observed after dialysis. After ultracentrifugation, large proportions of polar antioxidants were found in the "emulsion phase" and the "precipitate" (7-34% and 2-7%, respectively). This indicated entrapment of antioxidants at the oil-water interface in mayonnaise. The results signify that antioxidants partitioning into different phases of real food emulsions may vary widely.

  18. Intracellular trafficking mechanism of cationic phospholipids including cationic liposomes in HeLa cells.

    PubMed

    Un, K; Sakai-Kato, K; Goda, Y

    2014-07-01

    The development of gene delivery methods is essential for the achievement of effective gene therapy. Elucidation of the intracellular transfer mechanism for cationic carriers is in progress, but there are few reports regarding the intracellular trafficking processes of the cationic phospholipids taken up into cells. In the present work, the trafficking processes of a cationic phospholipid (1,2-dioleoyl-3-trimethylammonium-propane, DOTAP) were investigated from intracellular uptake to extracellular efflux using cationic liposomes in vitro. Following intracellular transport of liposomes via endocytosis, DOTAP was localized in the endoplasmic reticulum, Golgi apparatus, and mitochondria. Moreover, the proteins involved in DOTAP intracellular trafficking and extracellular efflux were identified. In addition, helper lipids of cationic liposomes were found to partially affect this intracellulartrafficking. These findings might provide valuable information for designing cationic carriers and avoiding unexpected toxic side effects derived from cationic liposomal components.

  19. Isotope fractionation of benzene during partitioning - Revisited.

    PubMed

    Kopinke, F-D; Georgi, A; Imfeld, G; Richnow, H-H

    2017-02-01

    Isotope fractionation between benzene-D0 and benzene-D6 caused by multi-step partitioning of the benzenes between water and two organic solvents, n-octane and 1-octanol, as well as between water and the gas phase, was measured. The obtained fractionation factors αH = KH/KD are αH = 1.080 ± 0.015 and αH = 1.074 ± 0.015 for extraction into n-octane and 1-octanol, respectively, and αH = 1.049 ± 0.010 for evaporation from aqueous solution. The comparison of solvent- and gas-phase partitioning reveals that about 2/3 of the driving force of fractionation is due to different interactions in the aqueous phase, whereas 1/3 is due to different interactions in the organic phase. The heavy benzene isotopologue behaves more 'hydrophilically' and the light one more 'hydrophobically'. This synergistic alignment gives rise to relatively large fractionation effects in partitioning between water and non-polar organic matter. In contrast to a previous study, there is no indication of strong fractionation by specific interactions between benzene and octanol. Partitioning under non-equilibrium conditions yields smaller apparent fractionation effects due to opposite trends of thermodynamic and kinetic fractionation parameters, i.e. partition and diffusion coefficients of the isotopologues. This may have consequences which should be taken into account when considering isotope fractionation due to sorption in environmental compartments.

  20. Recommended Partition Coefficient (Kd) Values for Nuclide Partitioning in the Presence of Cellulose Degradation Products

    SciTech Connect

    Serkiz, S.M.

    2001-02-23

    This report documents the data analysis of the results of the described laboratory studies in order to recommend Kd values for use in Performance Assessment modeling of nuclide transport in the presence of CDP.

  1. Cationic Bolaamphiphiles for Gene Delivery

    NASA Astrophysics Data System (ADS)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  2. Cation Transport in Escherichia coli

    PubMed Central

    Schultz, Stanley G.; Epstein, Wolfgang; Solomon, A. K.

    1963-01-01

    The resuspension of K-poor, Na-rich stationary phase E. coli in fresh medium at pH 7.0 results in a rapid uptake of K and extrusion of Na by the cells. In all experiments net K uptake exceeded net Na extrusion. An investigation of the uptake of glucose, PO4, and Mg and the secretion of H by these cells indicates that the excess K uptake is not balanced by the simultaneous uptake of anions but must be accompanied by the extrusion of cations from the cell. The kinetics of net K uptake are consistent with the existence of two parallel influx processes. The first is rapid, of brief duration, and accounts for approximately 60 per cent of the total net K uptake. This process is a function of the extracellular K concentration, is inhibited in acid media, and appears to be a 1 for 1 exchange of extracellular K for intracellular H. The second influx process has a half-time of approximately 12 minutes, and is not affected by acid media. This process is a function of the intracellular Na concentration, is dependent upon the presence of K in the medium, and may be ascribed to a 1 for 1 exchange of extracellular K for intracellular Na. PMID:14080819

  3. INORGANIC CATIONS IN RAT KIDNEY

    PubMed Central

    Tandler, C. J.; Kierszenbaum, A. L.

    1971-01-01

    For localization of pyroantimonate-precipitable cations, rat kidney was fixed by perfusion with a saturated aqueous solution of potassium pyroantimonate (pH about 9.2, without addition of any conventional fixative). A remarkably good preservation of the tissue and cell morphology was obtained as well as a consistent and reproducible localization of the insoluble antimonate salts of magnesium, calcium, and sodium. All proximal and distal tubules and glomeruli were delimited by massive electron-opaque precipitates localized in the basement membrane and, to a lesser extent, in adjacent connective tissue. In the intraglomerular capillaries the antimonate precipitate was encountered in the basement membranes and also between the foot processes. In addition to a more or less uniform distribution in the cytoplasm and between the microvilli of the brush border, antimonate precipitates were found in all cell nuclei, mainly between the masses of condensed chromatin. The mitochondria usually contained a few large antimonate deposits which probably correspond to the so-called "dense granules" observed after conventional fixations. PMID:4106544

  4. Nucleophilic Addition of Nitrogen to Aryl Cations: Mimicking Titan Chemistry

    NASA Astrophysics Data System (ADS)

    Li, Anyin; Jjunju, Fred P. M.; Cooks, R. Graham

    2013-11-01

    The reactivity of aryl cations toward molecular nitrogen is studied systematically in an ion trap mass spectrometer at 102 Pascal of nitrogen, the pressure of the Titan main haze layer. Nucleophilic addition of dinitrogen occurs and the nature of aryl group has a significant influence on the reactivity, through inductive effects and by changing the ground state spin multiplicity. The products of nitrogen activation, aryldiazonium ions, react with typical nitriles, aromatic amines, and alkynes (compounds that are relevant as possible Titan atmosphere constituents) to form covalently bonded heterocyclic products. Theoretical calculations at the level [DFT(B3LYP)/6-311++G(d,p)] indicate that the N2 addition reaction is exothermic for the singlet aryl cations but endothermic for their triplet spin isomers. The -OH and -NH2 substituted aryl ions are calculated to have triplet ground states, which is consistent with their decreased nitrogen addition reactivity. The energy needed for the generation of the aryl cations from their protonated precursors (ca. 340 kJ/mol starting with protonated aniline) is far less than that required to directly activate the nitrogen triple bond (the lowest energy excited state of N2 lies ca. 600 kJ/mol above the ground state). The formation of aza-aromatics via arene ionization and subsequent reactions provide a conceivable route to the genesis of nitrogen-containing organic molecules in the interstellar medium and Titan haze layers.

  5. Nucleophilic addition of nitrogen to aryl cations: mimicking Titan chemistry.

    PubMed

    Li, Anyin; Jjunju, Fred P M; Cooks, R Graham

    2013-11-01

    The reactivity of aryl cations toward molecular nitrogen is studied systematically in an ion trap mass spectrometer at 10(2) Pascal of nitrogen, the pressure of the Titan main haze layer. Nucleophilic addition of dinitrogen occurs and the nature of aryl group has a significant influence on the reactivity, through inductive effects and by changing the ground state spin multiplicity. The products of nitrogen activation, aryldiazonium ions, react with typical nitriles, aromatic amines, and alkynes (compounds that are relevant as possible Titan atmosphere constituents) to form covalently bonded heterocyclic products. Theoretical calculations at the level [DFT(B3LYP)/6-311++G(d,p)] indicate that the N2 addition reaction is exothermic for the singlet aryl cations but endothermic for their triplet spin isomers. The -OH and -NH2 substituted aryl ions are calculated to have triplet ground states, which is consistent with their decreased nitrogen addition reactivity. The energy needed for the generation of the aryl cations from their protonated precursors (ca. 340 kJ/mol starting with protonated aniline) is far less than that required to directly activate the nitrogen triple bond (the lowest energy excited state of N2 lies ca. 600 kJ/mol above the ground state). The formation of aza-aromatics via arene ionization and subsequent reactions provide a conceivable route to the genesis of nitrogen-containing organic molecules in the interstellar medium and Titan haze layers.

  6. Open software tools for eddy covariance flux partitioning

    USDA-ARS?s Scientific Manuscript database

    Agro-ecosystem management and assessment will benefit greatly from the development of reliable techniques for partitioning evapotranspiration (ET) into evaporation (E) and transpiration (T). Among other activities, flux partitioning can aid in evaluating consumptive vs. non-consumptive agricultural...

  7. Partitioning behavior of petrodiesel/biodiesel blends in water.

    PubMed

    Yassine, Mohamad H; Wu, Shuyun; Suidan, Makram T; Venosa, Albert D

    2012-07-17

    The partitioning behavior of six petrodiesel/soybean-biodiesel blends (B0, B20, B40, B60, B80, and B100, where B100 is 100% unblended biodiesel) in water was investigated at various oil loads by the 10-fold dilution method. Five fatty acid methyl esters (FAMEs), C10-C20 n-alkanes, and four monoaromatic compounds were targeted for analysis. Only the aromatic compounds were partitioned according to Raoult's law at all oil loads. The partitioning of the FAMEs and n-alkanes at higher oil loads was found to be orders of magnitude higher than the reported aqueous solubilities of these compounds, and directly correlated with the amount of oil load applied. Depth filtration of the water-accommodated fractions (WAFs) significantly reduced the observed concentrations of the FAMEs and n-alkanes, but did not appreciably affect the aromatic compounds. The FAMEs and n-alkanes concentrations in the filtered WAFs agreed with the aqueous solubilities of those compounds reported in the literature, but the n-alkanes showed progressive deviations from those solubilities with the increase in the amount of biodiesel in the blends. Further dilution experiments on pure n-hexadecane confirmed the presence of a metastable colloidal phase that seems to be controlled by hydrophobic interactions and surface phenomena. The addition of biodiesel to the oil blend appeared to have a positive impact on the dissolved concentrations and the colloidal accommodation of the n-alkanes. Autoxidation of the biodiesel constituents was found to be significant, and increased with increasing oil loads. Chemical products such as hexanal, n-butyl acetate, diethylene glycol monobutyl ether, and diethylene glycol monobutyl ether acetate were positively identified among the FAMEs' autoxidation byproducts. Our data suggest a positive enhancement for biodiesel on the formation of the oil in water colloidal phase, possibly by forming a surfactant-cosurfactant-like pair of the FAMEs and their autoxidation byproducts.

  8. Measurement and analysis of the mannitol partition coefficient in sucrose crystallization under simulated industrial conditions

    USDA-ARS?s Scientific Manuscript database

    Mannitol is a major deterioration product of Leuconstoc mesenteroides bacterial deterioration of both sugarcane and sugar beet. The effect of crystallization conditions on the mannitol partition coefficient (Keff) between impure sucrose syrup and crystal has been investigated in a batch laboratory c...

  9. Carbon allocation and partitioning in aspen clones varying in sensitivity to tropospheric ozone

    Treesearch

    M.D. Coleman; R.E. Dickson; J.G. Isebrands; D.F. Karnosky

    1995-01-01

    Clones of aspen (Populus tremuloides Michx.) were identified that differ in biomass production in response to O3exposure. 14Carbon tracer studies were used to determine if the differences in biomass response were linked to shifts in carbon allocation and carbon partitioning patterns. Rooted cuttings from...

  10. Soybean seed phenol, lignin, and isoflavones partitioning as affected by seed node position and genotype differences

    USDA-ARS?s Scientific Manuscript database

    Factors controlling the production and partitioning of seed phenolics within soybean are not understood. Understanding these factors may justify selection for higher levels of seed phenolics because of their beneficial impact on human health and soybean defense against diseases. The objective of thi...

  11. Assessing the effects of architectural variations on light partitioning within virtual wheat–pea mixtures

    PubMed Central

    Barillot, Romain; Escobar-Gutiérrez, Abraham J.; Fournier, Christian; Huynh, Pierre; Combes, Didier

    2014-01-01

    Background and Aims Predicting light partitioning in crop mixtures is a critical step in improving the productivity of such complex systems, and light interception has been shown to be closely linked to plant architecture. The aim of the present work was to analyse the relationships between plant architecture and light partitioning within wheat–pea (Triticum aestivum–Pisum sativum) mixtures. An existing model for wheat was utilized and a new model for pea morphogenesis was developed. Both models were then used to assess the effects of architectural variations in light partitioning. Methods First, a deterministic model (L-Pea) was developed in order to obtain dynamic reconstructions of pea architecture. The L-Pea model is based on L-systems formalism and consists of modules for ‘vegetative development’ and ‘organ extension’. A tripartite simulator was then built up from pea and wheat models interfaced with a radiative transfer model. Architectural parameters from both plant models, selected on the basis of their contribution to leaf area index (LAI), height and leaf geometry, were then modified in order to generate contrasting architectures of wheat and pea. Key results By scaling down the analysis to the organ level, it could be shown that the number of branches/tillers and length of internodes significantly determined the partitioning of light within mixtures. Temporal relationships between light partitioning and the LAI and height of the different species showed that light capture was mainly related to the architectural traits involved in plant LAI during the early stages of development, and in plant height during the onset of interspecific competition. Conclusions In silico experiments enabled the study of the intrinsic effects of architectural parameters on the partitioning of light in crop mixtures of wheat and pea. The findings show that plant architecture is an important criterion for the identification/breeding of plant ideotypes, particularly

  12. Assessing the effects of architectural variations on light partitioning within virtual wheat-pea mixtures.

    PubMed

    Barillot, Romain; Escobar-Gutiérrez, Abraham J; Fournier, Christian; Huynh, Pierre; Combes, Didier

    2014-09-01

    Predicting light partitioning in crop mixtures is a critical step in improving the productivity of such complex systems, and light interception has been shown to be closely linked to plant architecture. The aim of the present work was to analyse the relationships between plant architecture and light partitioning within wheat-pea (Triticum aestivum-Pisum sativum) mixtures. An existing model for wheat was utilized and a new model for pea morphogenesis was developed. Both models were then used to assess the effects of architectural variations in light partitioning. First, a deterministic model (L-Pea) was developed in order to obtain dynamic reconstructions of pea architecture. The L-Pea model is based on L-systems formalism and consists of modules for 'vegetative development' and 'organ extension'. A tripartite simulator was then built up from pea and wheat models interfaced with a radiative transfer model. Architectural parameters from both plant models, selected on the basis of their contribution to leaf area index (LAI), height and leaf geometry, were then modified in order to generate contrasting architectures of wheat and pea. By scaling down the analysis to the organ level, it could be shown that the number of branches/tillers and length of internodes significantly determined the partitioning of light within mixtures. Temporal relationships between light partitioning and the LAI and height of the different species showed that light capture was mainly related to the architectural traits involved in plant LAI during the early stages of development, and in plant height during the onset of interspecific competition. In silico experiments enabled the study of the intrinsic effects of architectural parameters on the partitioning of light in crop mixtures of wheat and pea. The findings show that plant architecture is an important criterion for the identification/breeding of plant ideotypes, particularly with respect to light partitioning.

  13. Aggregation of nucleosomes by divalent cations.

    PubMed Central

    de Frutos, M; Raspaud, E; Leforestier, A; Livolant, F

    2001-01-01

    Conditions of precipitation of nucleosome core particles (NCP) by divalent cations (Ca(2+) and Mg(2+)) have been explored over a large range of nucleosome and cation concentrations. Precipitation of NCP occurs for a threshold of divalent cation concentration, and redissolution is observed for further addition of salt. The phase diagram looks similar to those obtained with DNA and synthetic polyelectrolytes in the presence of multivalent cations, which supports the idea that NCP/NCP interactions are driven by cation condensation. In the phase separation domain the effective charge of the aggregates was determined by measurements of their electrophoretic mobility. Aggregates formed in the presence of divalent cations (Mg(2+)) remain negatively charged over the whole concentration range. They turn positively charged when aggregation is induced by trivalent (spermidine) or tetravalent (spermine) cations. The higher the valency of the counterions, the more significant is the reversal of the effective charge of the aggregates. The sign of the effective charge has no influence on the aspect of the phase diagram. We discuss the possible reasons for this charge reversal in the light of actual theoretical approaches. PMID:11463653

  14. Alternative mechanisms of action of cationic antimicrobial peptides on bacteria.

    PubMed

    Hale, John D F; Hancock, Robert E W

    2007-12-01

    Cationic antimicrobial peptides are a novel type of antibiotic offering much potential in the treatment of microbial-related diseases. They offer many advantages for commercial development, including a broad spectrum of action and modest size. However, despite the identification or synthetic production of thousands of such peptides, the mode of action remains elusive, except for a few examples. While the dogma for the mechanism of action of antimicrobial peptides against bacteria is believed to be through pore formation or membrane barrier disruption, some peptides clearly act differently and other intracellular target sites have been identified. This article presents an updated review of how cationic antimicrobial peptides are able to affect bacterial killing, with a focus on internal targets.

  15. Using Reward/Utility Based Impact Scores in Partitioning

    DTIC Science & Technology

    2014-05-01

    ing approach called Reward/Utility-Based Impact ( RUBI ). RUBI nds an e ective partitioning of agents while requir- ing no prior domain knowledge...provides better performance by discovering a non-trivial agent partitioning, and leads to faster simulations. We test RUBI in the Air Tra c Flow Management...partitioning with RUBI in the ATFMP, there is a 37% increase in per- formance, with a 510x speed up per simulation step over non-partitioning approaches

  16. Experimental Constraints on the Partitioning Behavior of F, Cl, and OH Between Apatite and Basaltic Melt

    NASA Technical Reports Server (NTRS)

    McCubbin, Francis M.; Barnes, Jessica J.; Vander Kaaden, Kathleen E.; Boyce, Jeremy W.; Ustunisik, Gokce; Whitson, Eric S.

    2017-01-01

    The mineral apatite is present in a wide range of planetary materials. The presence of volatiles (F, Cl, and OH) within its crystal structure (X-site) have motivated numerous studies to investigate the partitioning behavior of F, Cl, and OH between apatite and silicate melt with the end goal of using apatite to constrain the volatile contents of planetary magmas and mantle sources. A number of recent experimental studies have investigated the apatite-melt partitioning behavior of F, Cl, and OH in magmatic systems. Apatite-melt partitioning of volatiles are best described as exchange equilibria similar to Fe-Mg partitioning between olivine and silicate melt. However, the partitioning behavior is likely to change as a function of temperature, pressure, oxygen fugacity, apatite composition, and melt composition. In the present study, we have conducted experiments to assess the partitioning behavior of F, Cl, and OH between apatite and silicate melt over a pressure range of 0-6 gigapascals, a temperature range of 950-1500 degrees Centigrade, and a wide range of apatite ternary compositions. All of the experiments were conducted between iron-wustite oxidation potentials IW minus 1 and IW plus 2 in a basaltic melt composition. The experimental run products were analyzed by a combination of electron probe microanalysis and secondary ion mass spectrometry (NanoSIMS). Temperature, apatite crystal chemistry, and pressure all play important roles in the partitioning behavior of F, Cl, and OH between apatite and silicate melt. In portions of apatite ternary space that undergo ideal mixing of F, Cl, and OH, exchange coefficients remain constant at constant temperature and pressure. However, exchange coefficients vary at constant temperature (T) and pressure (P) in portions of apatite compositional space where F, Cl, and OH do not mix ideally in apatite. The variation in exchange coefficients exhibited by apatite that does not undergo ideal mixing far exceeds the variations

  17. Radical Cations and Acid Protection during Radiolysis

    SciTech Connect

    Bruce J. Mincher; Christopher A. Zarzana; Stephen P. Mezyk

    2016-09-01

    Ligand molecules for used nuclear fuel separation schemes are exposed to high radiation fields and high concentrations of acid. Thus, an understanding of the complex interactions between extraction ligands, diluent, and acid is critical to understanding the performance of a separation process. The diglycolamides are ligands with important structural similarities to CMPO; however, previous work has shown that their radiolytic degradation has important mechanistic differences from CMPO. The DGAs do not enjoy radioprotection by HNO3 and the kinetics of DGA radiolytic degradation are different. CMPO degrades with pseudo-zero-order kinetics in linear fashion with absorbed dose while the DGAs degrade in pseudo-first-order, exponential fashion. This suggests that the DGAs degrade by simple reaction with some product of direct diluent radiolysis, while CMPO degradation is probably multi-step, with a slow step that is not dependent on the CMPO concentration, and mitigated by HNO3. It is thus believed that radio-protection and the zero-order radiolytic degradation kinetics are related, and that these phenomena are a function of either the formation of strong acid complexes with CMPO and/or to the presence of the CMPO phenyl ring. Experiments to test both these hypotheses have been designed and partially conducted. This report summarizes findings related to these phenomena for FY16, in satisfaction of milestone M3FT-16IN030104053. It also reports continued kinetic measurements for the reactions of the dodecane radical cation with solvent extraction ligands.

  18. Various notions of positivity for bi-linear maps and applications to tri-partite entanglement

    SciTech Connect

    Han, Kyung Hoon; Kye, Seung-Hyeok

    2016-01-15

    We consider bi-linear analogues of s-positivity for linear maps. The dual objects of these notions can be described in terms of Schmidt ranks for tri-tensor products and Schmidt numbers for tri-partite quantum states. These tri-partite versions of Schmidt numbers cover various kinds of bi-separability, and so we may interpret witnesses for those in terms of bi-linear maps. We give concrete examples of witnesses for various kinds of three qubit entanglement.

  19. Proposed Molecular Beam Determination of Energy Partition in the Photodissociation of Polyatomic Molecules

    DOE R&D Accomplishments Database

    Zare, P. N.; Herschbach, D. R.

    1964-01-29

    Conventional photochemical experiments give no information about the partitioning of energy between translational recoil and internal excitation of the fragment molecules formed in photodissociation of a polyatomic molecule. In a molecular beam experiment, it becomes possible to determine the energy partition from the form of the laboratory angular distribution of one of the photodissociation products. A general kinematic analysis is worked out in detail, and the uncertainty introduced by the finite angular resolution of the apparatus and the velocity spread in the parent beam is examined. The experimental requirements are evaluated for he photolysis of methyl iodide by the 2537 angstrom Hg line.

  20. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  1. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  2. 33. Elevation of Doors / Typical Cement Toilet Partitions / ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. Elevation of Doors / Typical Cement Toilet Partitions / Typical Cement Shower Bath Partitions / Typical Marble Shower Bath Partitions / Dispensary Cupboard Supply Room Cupboard Similar / Section / Kitchen Cupboard and Sink / Screened Porch Cupboard (drawing 10) - Whittier State School, Hospital & Receiving Building, 11850 East Whittier Boulevard, Whittier, Los Angeles County, CA

  3. Bounds for the Eventual Positivity of Difference Functions of Partitions

    NASA Astrophysics Data System (ADS)

    Woodford, Roger

    2007-01-01

    In this paper we specialize work done by Bateman and Erdos concerning difference functions of partition functions. In particular, we are concerned with partitions into fixed powers of the primes. We show that any difference function of these partition functions is eventually increasing, and derive explicit bounds for when it will attain strictly positive values. From these bounds an asymptotic result is derived.

  4. 47 CFR 90.813 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.813 Partitioned licenses and disaggregated spectrum. (a) Eligibility.... Spectrum may be disaggregated in any amount. (3) Combined partitioning and disaggregation. The...

  5. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  6. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  7. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request...

  8. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request...

  9. 47 CFR 90.813 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.813 Partitioned licenses and disaggregated spectrum. (a) Eligibility.... Spectrum may be disaggregated in any amount. (3) Combined partitioning and disaggregation. The...

  10. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  11. 47 CFR 90.911 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.911 Partitioned licenses and disaggregated spectrum. (a) Eligibility...) that constitute the partitioned area. (2) Disaggregation. Spectrum may be disaggregated in any...

  12. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 2 2012-10-01 2012-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  13. 47 CFR 90.911 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.911 Partitioned licenses and disaggregated spectrum. (a) Eligibility...) that constitute the partitioned area. (2) Disaggregation. Spectrum may be disaggregated in any...

  14. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  15. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 2 2014-10-01 2014-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  16. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request...

  17. 47 CFR 90.911 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.911 Partitioned licenses and disaggregated spectrum. (a) Eligibility...) that constitute the partitioned area. (2) Disaggregation. Spectrum may be disaggregated in any...

  18. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  19. 47 CFR 90.813 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.813 Partitioned licenses and disaggregated spectrum. (a) Eligibility.... Spectrum may be disaggregated in any amount. (3) Combined partitioning and disaggregation. The...

  20. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  1. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request...

  2. 47 CFR 27.805 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 2 2013-10-01 2013-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1.4 GHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  3. 47 CFR 90.911 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.911 Partitioned licenses and disaggregated spectrum. (a) Eligibility...) that constitute the partitioned area. (2) Disaggregation. Spectrum may be disaggregated in any...

  4. 47 CFR 95.823 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Geographic partitioning and spectrum... Geographic partitioning and spectrum disaggregation. (a) Eligibility. Parties seeking Commission approval of geographic partitioning or spectrum disaggregation of 218-219 MHz Service system licenses shall request...

  5. 47 CFR 27.904 - Geographic partitioning and spectrum disaggregation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 2 2011-10-01 2011-10-01 false Geographic partitioning and spectrum... partitioning and spectrum disaggregation. An entity that acquires a portion of a 1670-1675 MHz band licensee's geographic area or spectrum subject to a geographic partitioning or spectrum disaggregation agreement...

  6. 47 CFR 90.813 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.813 Partitioned licenses and disaggregated spectrum. (a) Eligibility.... Spectrum may be disaggregated in any amount. (3) Combined partitioning and disaggregation. The...

  7. 47 CFR 90.911 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.911 Partitioned licenses and disaggregated spectrum. (a) Eligibility...) that constitute the partitioned area. (2) Disaggregation. Spectrum may be disaggregated in any...

  8. 47 CFR 90.813 - Partitioned licenses and disaggregated spectrum.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Partitioned licenses and disaggregated spectrum... Specialized Mobile Radio Service § 90.813 Partitioned licenses and disaggregated spectrum. (a) Eligibility.... Spectrum may be disaggregated in any amount. (3) Combined partitioning and disaggregation. The...

  9. Selective disulfide bond cleavage in gold(I) cationized polypeptide ions formed via gas-phase ion/ion cation switching.

    PubMed

    Gunawardena, Harsha P; O'Hair, Richard A J; McLuckey, Scott A

    2006-09-01

    Gaseous multiply protonated disulfide-linked peptides have been subjected to reactions with AuCl2(-) ions to explore the possibility of effecting cation switching of Au+ for two protons and to determine whether cationization by Au+ ions affords selective dissociation of disulfide linkages. The incorporation of Au+ into several model disulfide-linked peptides proved to be straightforward. The primary ion/ion reaction channels were proton transfer, which does not lead to Au+ incorporation, and attachment of AuCl2(-) ions to the polypeptide cation, which does incorporate Au+. Fragmentation of the attachment product, the extent of which varied with peptide and charge state, led to losses of one or more molecules of HCl and, to some extent, cleavage of polypeptides at the disulfide linkage into its two constituent chains. Collisional activation of the intact metal-ion-incorporated peptides showed cleavage of the disulfide linkage to be a major, and in some cases exclusive, process. Cations with protons as the only cationizing agents showed only small contributions from cleavage of the disulfide linkage. These results indicate that Au+ incorporation into a disulfide-linked polypeptide ion is a promising way to effect selective dissociation of disulfide bonds. Cation switching via ion/ion reactions is a convenient means for incorporating gold and is attractive because it avoids the requirement of adding metal salts to the analyte solution.

  10. Cationic liposomes evoke proinflammatory mediator release and neutrophil extracellular traps (NETs) toward human neutrophils.

    PubMed

    Hwang, Tsong-Long; Hsu, Ching-Yun; Aljuffali, Ibrahim A; Chen, Chun-Han; Chang, Yuan-Ting; Fang, Jia-You

    2015-04-01

    Cationic liposomes are widely used as nanocarriers for therapeutic and diagnostic purposes. The cationic components of liposomes can induce inflammatory responses. This study examined the effect of cationic liposomes on human neutrophil activation. Cetyltrimethylammonium bromide (CTAB) or soyaethyl morpholinium ethosulfate (SME) was incorporated into liposomes as the cationic additive. The liposomes' cytotoxicity and their induction of proinflammatory mediators, intracellular calcium, and neutrophil extracellular traps (NETs) were investigated. The interaction of the liposomes with the plasma membrane triggered the stimulation of neutrophils. CTAB liposomes induced complete leakage of lactate dehydrogenase (LDH) at all concentrations tested, whereas SME liposomes released LDH in a concentration-dependent manner. CTAB liposomes proved to more effectively activate neutrophils compared with SME liposomes, as indicated by increased superoxide anion and elastase levels. Calcium influx increased 9-fold after treatment with CTAB liposomes. This influx was not changed by SME liposomes compared with the untreated control. Scanning electron microscopy (SEM) and immunofluorescence images indicated the presence of NETs after treatment with cationic liposomes. NETs could be quickly formed, within minutes, after CTAB liposomal treatment. In contrast to this result, NET formation was slowly and gradually increased by SME liposomes, within 4h. Based on the data presented here, it is important to consider the toxicity of cationic liposomes during administration in the body. This is the first report providing evidence of NET production induced by cationic liposomes. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Effect of Titanium on REE and HFSE Partitioning Between Garnet and Melt

    NASA Astrophysics Data System (ADS)

    Dwarzski, R. E.; Draper, D. S.

    2004-12-01

    Garnet is a strong fractionator of trace elements and plays an important role in the petrogenetic history of planetary interiors at high pressure. In order to model petrogenetic processes that operate within terrestrial planets accurately, it is important to understand how garnet partitions rare earth and high field strength elements. Here we assess the influence of Ti on garnet-melt trace element partitioning with a view both to constrain important crystal-chemical effects and to evaluate possible roles for garnet in lunar petrogenesis. Experiments were performed at ˜5 GPa and 1650-1675° C in a Walker-style multi-anvil high pressure apparatus using an Apollo 14 black picritic glass composition ( ˜17 wt% TiO2) to assess the effect of Ti on garnet partitioning. These experiments were also designed to examine the possible presence of garnet in mare source regions. Experimental charges were analyzed for major and trace elements by EPMA and SIMS, respectively. D-values measured in this study using the Apollo 14 black Ti-rich composition are consistently higher than those measured by Draper et al. (2004, LPSC XXXV:1297), who used Apollo 15 green C glass (<0.5 wt% TiO2). D vs. ionic radii are well-described for the trivalent cations by the lattice-strain partitioning model of Blundy and Wood (1994, Nature 372:452), with D0 = 2.27 ± 0.40, E = 159 ± 58 GPa, and r0 = 0.879 ± 0.044 Å (r2 = 0.957). For comparison, this model applied to the low-Ti experiments of Draper et al. (2004) yields D0 = 2.93 ± 0.25, E = 572 ± 40 GPa, and r0 = 0.926 ± 0.005 Å (r2 = 0.996) at ˜3.5 GPa. Both these fits show significant mismatch to the partitioning predicted by the formulations of van Westrenen et al. (2001, CMP 142:219), as previously shown for Fe-rich systems by Draper et al. (2003, PEPI 139:149). Use of our D-values (for rare earth and high field strength elements in batch-melting models) provisionally supports the hypotheses of Neal (2001, JGR 106:27865) and Neal and

  12. Trace element transformations and partitioning during the roasting of pyrite ores in the sulfuric acid industry.

    PubMed

    Yang, Chunxia; Chen, Yongheng; Peng, Ping'an; Li, Chao; Chang, Xiangyang; Wu, Yingjuan

    2009-08-15

    Total concentrations combined with chemical partitioning of trace elements (Cd, Co, Cr, Mn, Ni, Pb, Tl, and Zn) in raw pyrite ore and solid roasting wastes were investigated in order to elucidate their transformations and partitioning during the roasting of raw pyrite ores in sulfuric acid production. In order to better understand the behavior of these elements during roasting, mineral transformations accompanying roasting were also investigated by using microscopy. Results indicated that the mode of occurrence of trace elements in raw pyrite ore and the thermostability of trace element-bearing species formed during roasting played major roles in the transformations of the selected trace elements. Silicate- and amorphous iron (hydr)oxide-bound elements (Cr and Pb) were stable and mainly retained in their original phases. However, acid-exchangeable and sulfide-bound elements tended to transform into other forms via different pathways: elements that tend to form low thermostable species (Cd, Pb and Tl) were significantly vaporized, whereas elements that tend to form high thermostable species (Co, Mn and Ni) mainly reacted with iron oxides or silicates, which then remained in the solid residues. The volatility of trace elements during the roasting has a significant effect on their subsequent partitioning in roasting wastes. Nonvolatile element (Co, Cr, Mn, and Ni) partitioning was determined by settling of the particulate in which they are bound, whereas the partitioning of (semi)volatile elements (Cd, Pb, Tl, and Zn) was controlled by the adsorption of their gaseous species on the particulate.

  13. Mass budget partitioning during explosive eruptions: insights from the 2006 paroxysm of Tungurahua volcano, Ecuador

    NASA Astrophysics Data System (ADS)

    Bernard, Julien; Eychenne, Julia; Le Pennec, Jean-Luc; Narváez, Diego

    2016-08-01

    How and how much the mass of juvenile magma is split between vent-derived tephra, PDC deposits and lavas (i.e., mass partition) is related to eruption dynamics and style. Estimating such mass partitioning budgets may reveal important for hazard evaluation purposes. We calculated the volume of each product emplaced during the August 2006 paroxysmal eruption of Tungurahua volcano (Ecuador) and converted it into masses using high-resolution grainsize, componentry and density data. This data set is one of the first complete descriptions of mass partitioning associated with a VEI 3 andesitic event. The scoria fall deposit, near-vent agglutinate and lava flow include 28, 16 and 12 wt. % of the erupted juvenile mass, respectively. Much (44 wt. %) of the juvenile material fed Pyroclastic Density Currents (i.e., dense flows, dilute surges and co-PDC plumes), highlighting that tephra fall deposits do not depict adequately the size and fragmentation processes of moderate PDC-forming event. The main parameters controlling the mass partitioning are the type of magmatic fragmentation, conditions of magma ascent, and crater area topography. Comparisons of our data set with other PDC-forming eruptions of different style and magma composition suggest that moderate andesitic eruptions are more prone to produce PDCs, in proportions, than any other eruption type. This finding may be explained by the relatively low magmatic fragmentation efficiency of moderate andesitic eruptions. These mass partitioning data reveal important trends that may be critical for hazard assessment, notably at frequently active andesitic edifices.

  14. Opuntia humifusa partitioned extracts inhibit the growth of U87MG human glioblastoma cells.

    PubMed

    Hahm, Sahng-Wook; Park, Jieun; Son, Yong-Suk

    2010-09-01

    Opuntia humifusa, a member of the Cactaceae family widely distributed in the southern regions of the Korean peninsula, has potential bioactive functions and medicinal benefits. In the present study, we investigated the effect of hexane, ethyl acetate extracts and water partitioned fraction of O. humifusa on proliferation, G1 arrest and apoptosis in U87MG human glioblastoma cells. Glioblastoma cellular proliferation was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and the effects of O. humifusa partitioned extracts on cell cycle and apoptosis were analyzed by flow cytometry. Our results revealed that when U87MG cells were treated with hexane extracts and water partitioned fraction of O. humifusa, the number of viable cells decreased in a concentration-dependent manner. In addition, water partitioned fractions of O. humifusa induced G1 arrest and non-apoptotic cell death as well as significant increases in ROS production in U87MG cells. In conclusion, water partitioned fractions of O. humifusa induce G1 arrest and inhibit U87MG human glioblastoma cell proliferation.

  15. Analysis of Microstructure Evolution in Quenching and Partitioning Automotive Sheet Steel

    NASA Astrophysics Data System (ADS)

    Speer, John G.; de Moor, E.; Findley, K. O.; Matlock, D. K.; de Cooman, B. C.; Edmonds, D. V.

    2011-12-01

    Extensive research efforts are underway globally to develop new steel microstructure concepts for high-strength sheet products, driven largely by the need for lightweight automotive structures in support of designs to enhance occupant safety and energy efficiency. One promising approach, involving the quenching and partitioning (Q&P) process, was introduced in the predecessor to this paper series, Austenite Formation and Decomposition, 2003.[1] Development of the Q&P process has continued through to the present, and the current status is highlighted in this article, along with some alternative approaches that are also receiving attention. Special emphasis is placed on the synthesis and interpretation of the fundamental phase transformation responses, perspectives related to alloying and processing, and the resulting microstructure and properties. Key mechanistic issues are discussed, including carbide formation and suppression, migration of the martensite/austenite interface, carbon partitioning, and partitioning kinetics.

  16. Relative hydrophobicity between the phases and partition of cytochrome-c in glycine ionic liquids aqueous two-phase systems.

    PubMed

    Wu, Changzeng; Wang, Jianji; Li, Zhiyong; Jing, Jun; Wang, Huiyong

    2013-08-30

    In this work, glycine ionic liquids tetramethylammonium glycine ([N1111][Gly]), tetraethylammonium glycine ([N2222][Gly]), tetra-n-butylammonium glycine ([N4444][Gly]), tetra-n-butylphosphonium glycine ([P4444][Gly]) and tetra-n-pentylammonium glycine ([N5555][Gly]) were synthesized and used to prepare aqueous two-phase systems (ATPSs) in the presence of K2HPO4. Binodal curves of such ATPSs and partition coefficients of a series of dinitrophenylated (DNP) amino acids in these ATPSs were determined at 298.15K to understand the effect of cationic structure of the ionic liquids on the phase-forming ability of glycine ionic liquids, relative hydrophobicity between the phases in the ionic liquids ATPSs, and polarity of the ionic liquids-rich phases. With the attempt to correlate the relative hydrophobicity of the phases in the ATPSs with their extraction capability for proteins, partition coefficients of cytochrome-c in the ATPSs were also determined. It was shown that partition coefficients of cytochrome-c were in the range from 2.83 to 20.7 under the studied pH conditions. Then, hydrophobic interactions between cytochrome-c and the ionic liquid are suggested to be the main driving force for the preferential partition of cytochrome-c in the glycine ionic liquid-rich phases of the ATPSs. Result derived from polarity of the ionic liquids-rich phases supports this mechanism.

  17. Fractionation of strontium isotopes in cation-exchange chromatography

    SciTech Connect

    Oi, Takao; Ogino, Hideki; Kakihana, Hidetake ); Hosoe, Morikazu )

    1992-04-01

    Strontium isotope fractionation has been observed in cation-exchange chromatography of strontium salts. The heavier isotopes have been found enriched at the front parts of displacement-type chromatograms, which means that the heavier isotopes are preferentially fractionated into the solution phase. The average values of the single-stage separation factor (S) minus one per unit mass difference between isotopes have been 1.0 {times} 10{sup {minus}6} for the strontium chloride system, 2.9 {times} 10{sup {minus}6} for the strontium acetate system, and 3.1 {times} 10{sup {minus}6} for the strontium lactate system at 25C. No evidence of the odd-even anomalous isotope effects has been observed. The isotopic reduced partition function ratios (RPFRs) of the strontium species involved in the present study have been estimated; the RPFRs of the complex species have been found to be larger than that of simple hydrated strontium lactate and strontium acetate systems are larger than that of the strontium chloride system.

  18. In-Situ TEM visualization of vacancy injection and chemical partition during oxidation of Ni-Cr nanoparticles

    PubMed Central

    Wang, Chong-Min; Genc, Arda; Cheng, Huikai; Pullan, Lee; Baer, Donald R.; Bruemmer, Stephen M.

    2014-01-01

    Oxidation of alloy often involves chemical partition and injection of vacancies. Chemical partition is the consequence of selective oxidation, while injection of vacancies is associated with the differences of diffusivity of cations and anions. It is far from clear as how the injected vacancies behave during oxidation of metal. Using in-situ transmission electron microscopy, we captured unprecedented details on the collective behavior of injected vacancies during oxidation of metal, featuring an initial multi-site oxide nucleation, vacancy supersaturation, nucleation of a single cavity, sinking of vacancies into the cavity and accelerated oxidation of the particle. High sensitive energy dispersive x-ray spectroscopy mapping reveals that Cr is preferentially oxidized even at the initial oxidation, leading to a structure that Cr oxide is sandwiched near the inner wall of the hollow particle. The work provides a general guidance on tailoring of nanostructured materials involving multi-ion exchange such as core-shell structured composite nanoparticles. PMID:24418778

  19. Decrease in ciprofloxacin absorption by polyvalent metal cations is not fully attributable to chelation or adsorption.

    PubMed

    Imaoka, Ayuko; Hattori, Michiko; Akiyoshi, Takeshi; Ohtani, Hisakazu

    2014-01-01

    The drug interaction between new quinolone antibiotics (NQs) and polyvalent metal cation products, leading to a significant decrease in the absorption of NQ, is considered to be attributable to the formation of poorly absorbable chelate and physicochemical adsorption of NQs to cation products. To clarify the mechanisms of this drug interaction in detail, we investigated the effects of Al(3+) or Mg(2+) on the membrane permeation profile of ciprofloxacin (CPFX) across human colon carcinoma cell lines (Caco-2) in monolayer culture, and characterized the adsorption nature of CPFX to polyvalent metal cation products under physiological conditions. As a result, Al(3+) or Mg(2+) partially but not fully impaired the permeation of CPFX across Caco-2 monolayer up to 30% or 60% of control, respectively. Physicochemical adsorption of CPFX to cation products was not observed under physiological pH. In conclusion, two possible mechanisms investigated, the decrease in the permeability of CPFX by chelate formation and adsorption of CPFX to polyvalent metal cation products, may partially but not fully explain the extent of the drug interaction clinically observed.

  20. Fingerprinting DNA oxidation processes: IR characterization of the 5-methyl-2'-deoxycytidine radical cation.

    PubMed

    Bucher, Dominik B; Pilles, Bert M; Pfaffeneder, Toni; Carell, Thomas; Zinth, Wolfgang

    2014-02-24

    Methylated cytidine plays an important role as an epigenetic signal in gene regulation. Its oxidation products are assumed to be involved in active demethylation processes but also in damaging DNA. Here, we report the photochemical production of the 5-methyl-2'-deoxycytidine radical cation via a two-photon ionization process. The radical cation is detected by time-resolved IR spectroscopy and identified by band assignment using density functional theory calculations. Two final oxidation products are characterized with liquid chromatography coupled to mass spectrometry. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.