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Sample records for affects carbon partitioning

  1. Carbon partitioning in photosynthesis.

    Science.gov (United States)

    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.

  2. Carbon partitioning during quenching and partitioning heat treatment accompanied by carbide precipitation

    International Nuclear Information System (INIS)

    Carbon partitioning from martensite into austenite in the quenching and partitioning (Q&P) process has been suggested to be controlled by the constrained carbon equilibrium (CCE) criterion. It defines an approach for predicting the carbon concentration in austenite under the condition that competing reactions such as carbide formation and bainite transformation are suppressed. Carbide precipitation in martensite is, however, often observed during the partitioning step, even in low-carbon steels as well as in high-carbon steels, even when containing a high amount of Si. Therefore, carbon partitioning from martensite into austenite is studied here, considering carbide precipitation in martensite. Carbon partitioning was investigated by means of a field-emission electron probe micro analysis (FE-EPMA) and atom probe tomography (APT), using 1.07 wt.% and 0.59 wt.% carbon steels with various martensite volume fractions. Carbon partitioning from martensite to austenite was clearly observed in all specimens, even though a considerable amount of carbide precipitated inside the martensite. The austenite carbon concentration after the partitioning step was not influenced by either the martensite volume fraction or the bulk carbon content. A modified model for predicting the austenite carbon concentration after the partitioning step was proposed to explain the experimental results by assuming carbon equilibria between austenite, ferrite and cementite under a constrained condition

  3. Coupled Model for Carbon Partitioning from Martensite into Austenite During the Quenching Process in Fe-C Steels

    Science.gov (United States)

    Liu, Peixing; Zhu, Bin; Wang, Yilin; Zhang, Yisheng

    2016-08-01

    In this paper, a coupled model for carbon partitioning from martensite into austenite during the quenching process in Fe-C steels is constructed where the carbon is permitted to partition while the martensite is continuously forming. A diffusion model of carbon at the `martensite/austenite interface' is created where the interface does not move during the carbon partitioning process, and the driving force for carbon partitioning originates from the chemical potential difference. The results show that the martensitic transformation and carbon partitioning affect each other, and that the cooling rate between the martensite start temperature ( M s) and room temperature has a major effect on the volume fraction of the final retained austenite. The simulation results are shown to be in good agreement with experiments.

  4. Marine microalgae growth and carbon partitioning as a function of nutrient availability.

    Science.gov (United States)

    Fernandes, Tomásia; Fernandes, Igor; Andrade, Carlos A P; Cordeiro, Nereida

    2016-08-01

    To understand in which way the structural differences of three marine microalgae (Nannochloropsis gaditana, Rhodomonas marina and Isochrysis sp.) affect their carbon partitioning, growth and applicability; a stoichiometric imbalance was imposed by steady carbon and other nutrients variation. Towards high nutrients concentrations/low carbon availability a decrease of 12-51% in C/N microalgae ratio was observed and maximum cell densities were achieved. Moreover, linear correlation between the nutrient input and microalgae protein content were observed. The macromolecular ratios pointed that carbohydrate was the main contributor for the C/N decrement. Although lipid content in R. marina remained constant throughout the experiment, a rise of 37-107% in N. gaditana and Isochrysis sp. was verified. Lipid fractions revealed high percentages of glycolipids in all microalgae (57-73% of total lipids). The present study shows an easy way to understand and modulate microalgae carbon partitioning relying on the field of application. PMID:27179298

  5. Genomics Mechanisms of Carbon Allocation and Partitioning in Poplar

    Energy Technology Data Exchange (ETDEWEB)

    Kirst, Matias; Peter, Gary; Martin, Timothy

    2009-07-30

    The genetic control of carbon allocation and partitioning in woody perennial plants is poorly understood despite its importance for carbon sequestration. It is also unclear how environmental cues such as nitrogen availability impact the genes that regulate growth, and biomass allocation and wood composition in trees. To address these questions we phenotyped 396 clonally replicated genotypes of an interspecific pseudo-backcross pedigree of Populus for wood composition and biomass traits in above and below ground organs. The loci that regulate growth, carbon allocation and partitioning under two nitrogen conditions were identified, defining the contribution of environmental cues to their genetic control. Fifty-seven quantitative trait loci (QTL) were identified for twenty traits analyzed. The majority of QTL are specific to one of the two nitrogen treatments, demonstrating significant nitrogen-dependent genetic control. A highly significant genetic correlation was observed between plant growth and lignin/cellulose composition, and QTL co-localization identified the genomic position of potential pleiotropic regulators. Gene expression analysis of all poplar genes was also characterized in differentiating xylem, whole-roots and developing leaves of 192 of the segregating population. By integrating the QTL and gene expression information we identified genes that regulate carbon partitioning and several biomass growth related properties. The work developed in this project resulted in the publication of three book chapters, four scientific articles (three others currently in preparation), 17 presentations in international conferences and two provisional patent applications.

  6. Partitioning Carbon Dioxide Emission and Assessing Dissolved Organic Carbon Leaching of a Drained Peatland Cultivated with Pineapple at Saratok, Malaysia

    Directory of Open Access Journals (Sweden)

    Liza Nuriati Lim Kim Choo

    2014-01-01

    Full Text Available Pineapples (Ananas comosus (L. Merr. cultivation on drained peats could affect the release of carbon dioxide (CO2 into the atmosphere and also the leaching of dissolved organic carbon (DOC. Carbon dioxide emission needs to be partitioned before deciding on whether cultivated peat is net sink or net source of carbon. Partitioning of CO2 emission into root respiration, microbial respiration, and oxidative peat decomposition was achieved using a lysimeter experiment with three treatments: peat soil cultivated with pineapple, bare peat soil, and bare peat soil fumigated with chloroform. Drainage water leached from cultivated peat and bare peat soil was also analyzed for DOC. On a yearly basis, CO2 emissions were higher under bare peat (218.8 t CO2 ha/yr than under bare peat treated with chloroform (205 t CO2 ha/yr, and they were the lowest (179.6 t CO2 ha/yr under cultivated peat. Decreasing CO2 emissions under pineapple were attributed to the positive effects of photosynthesis and soil autotrophic activities. An average 235.7 mg/L loss of DOC under bare peat suggests rapid decline of peat organic carbon through heterotrophic respiration and peat decomposition. Soil CO2 emission depended on moderate temperature fluctuations, but it was not affected by soil moisture.

  7. Partitioning carbon dioxide emission and assessing dissolved organic carbon leaching of a drained peatland cultivated with pineapple at Saratok, Malaysia.

    Science.gov (United States)

    Lim Kim Choo, Liza Nuriati; Ahmed, Osumanu Haruna

    2014-01-01

    Pineapples (Ananas comosus (L.) Merr.) cultivation on drained peats could affect the release of carbon dioxide (CO2) into the atmosphere and also the leaching of dissolved organic carbon (DOC). Carbon dioxide emission needs to be partitioned before deciding on whether cultivated peat is net sink or net source of carbon. Partitioning of CO2 emission into root respiration, microbial respiration, and oxidative peat decomposition was achieved using a lysimeter experiment with three treatments: peat soil cultivated with pineapple, bare peat soil, and bare peat soil fumigated with chloroform. Drainage water leached from cultivated peat and bare peat soil was also analyzed for DOC. On a yearly basis, CO2 emissions were higher under bare peat (218.8 t CO2 ha/yr) than under bare peat treated with chloroform (205 t CO2 ha/yr), and they were the lowest (179.6 t CO2 ha/yr) under cultivated peat. Decreasing CO2 emissions under pineapple were attributed to the positive effects of photosynthesis and soil autotrophic activities. An average 235.7 mg/L loss of DOC under bare peat suggests rapid decline of peat organic carbon through heterotrophic respiration and peat decomposition. Soil CO2 emission depended on moderate temperature fluctuations, but it was not affected by soil moisture. PMID:25215335

  8. How drought severity constrains GPP and its partitioning among carbon pools in a Quercus ilex coppice?

    Directory of Open Access Journals (Sweden)

    S. Rambal

    2014-06-01

    Full Text Available The partitioning of photosynthates toward biomass compartments has a crucial role in the carbon sink function of forests. Few studies have examined how carbon is allocated toward plant compartments in drought prone forests. We analyzed the fate of GPP in relation to yearly water deficit in an old evergreen Mediterranean Quercus ilex coppice severely affected by water limitations. Gross and net 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 productions we managed to close a C budget and derive values of autotrophic and heterotrophic respirations, NPP and carbon use efficiency (CUE, the ratio between NPP and GPP. Average values of yearly NEP, GPP and Reco were 282, 1259 and 977 g C m−2. The corresponding ANPP components were 142.5, 26.4 and 69.6 g C m−2 for leaves, reproductive effort (flowers and fruits and stems. Gross and net carbon exchange between the ecosystem and the atmosphere 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 more slightly in response to drought than GPP and NPP, 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 highlight the value of maintaining continuous

  9. How drought severity constrains GPP and its partitioning among carbon pools in a Quercus ilex coppice?

    Science.gov (United States)

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

    2014-06-01

    The partitioning of photosynthates toward biomass compartments has a crucial role in the carbon sink function of forests. Few studies have examined how carbon is allocated toward plant compartments in drought prone forests. We analyzed the fate of GPP in relation to yearly water deficit in an old evergreen Mediterranean Quercus ilex coppice severely affected by water limitations. Gross and net 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 productions we managed to close a C budget and derive values of autotrophic and heterotrophic respirations, NPP and carbon use efficiency (CUE, the ratio between NPP and GPP). Average values of yearly NEP, GPP and Reco were 282, 1259 and 977 g C m-2. The corresponding ANPP components were 142.5, 26.4 and 69.6 g C m-2 for leaves, reproductive effort (flowers and fruits) and stems. Gross and net carbon exchange between the ecosystem and the atmosphere 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 more slightly in response to drought than GPP and NPP, 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 highlight the value of maintaining continuous experimental

  10. Development of partitioning process: back-extraction of actinoid and lanthanoid with hydrazine carbonate

    International Nuclear Information System (INIS)

    In the present study the back extraction of actinoid, lanthanoid, Y, Zr, and Mo from DIDPA [Diisodecylphosphoric Acid] and HDEHP [Di(2-ethylhexylphosphoric) Acid] was investigated by using hydrazine carbonate solution. Hydrazine carbonate is a salt-free reagent and easy to decompose. If it is possible to apply this reagent to the 4-group partitioning process, more sophisticated process would be constructed, because of the reduction of secondary wastes. All the elements other than Y could be back-extracted from HDEHP and all the elements other than Y and Mo could be back-extracted from DIDPA by hydrazine carbonate. It was found that the nature of alcohol which was added to avoid emulsification affects on the distribution ratio more than the added amount. (author)

  11. Microstructural evolution and mechanical properties of a low-carbon quenching and partitioning steel after partial and full austenitization

    Institute of Scientific and Technical Information of China (English)

    Wan-song Li; Hong-ye Gao; Hideharu Nakashima; Satoshi Hata; Wen-huai Tian

    2016-01-01

    In this work, low-carbon steel specimens were subjected to the quenching and partitioning process after being partially or fully austenitized to investigate their microstructural evolution and mechanical properties. According to the results of scanning electron micros-copy and transmission electron microscopy observations, X-ray diffraction analysis, and tensile tests, upper bainite or tempered martensite appears successively in the microstructure with increasing austenitization temperature or increasing partitioning time. In the partially austeni-tized specimens, the retained austenite grains are carbon-enriched twice during the heat treatment, which can significantly stabilize the phases at room temperature. Furthermore, after partial austenitization, the specimen exhibits excellent elongation, with a maximum elongation of 37.1%. By contrast, after full austenitization, the specimens exhibit good ultimate tensile strength and high yield strength. In the case of a specimen with a yield strength of 969 MPa, the maximum value of the ultimate tensile strength reaches 1222 MPa. During the partitioning process, carbon partitioning and carbon homogenization within austenite affect interface migration. In addition, the volume fraction and grain size of retained austenite observed in the final microstructure will also be affected.

  12. Microstructural evolution and mechanical properties of a low-carbon quenching and partitioning steel after partial and full austenitization

    Science.gov (United States)

    Li, Wan-song; Gao, Hong-ye; Nakashima, Hideharu; Hata, Satoshi; Tian, Wen-huai

    2016-08-01

    In this work, low-carbon steel specimens were subjected to the quenching and partitioning process after being partially or fully austenitized to investigate their microstructural evolution and mechanical properties. According to the results of scanning electron microscopy and transmission electron microscopy observations, X-ray diffraction analysis, and tensile tests, upper bainite or tempered martensite appears successively in the microstructure with increasing austenitization temperature or increasing partitioning time. In the partially austenitized specimens, the retained austenite grains are carbon-enriched twice during the heat treatment, which can significantly stabilize the phases at room temperature. Furthermore, after partial austenitization, the specimen exhibits excellent elongation, with a maximum elongation of 37.1%. By contrast, after full austenitization, the specimens exhibit good ultimate tensile strength and high yield strength. In the case of a specimen with a yield strength of 969 MPa, the maximum value of the ultimate tensile strength reaches 1222 MPa. During the partitioning process, carbon partitioning and carbon homogenization within austenite affect interface migration. In addition, the volume fraction and grain size of retained austenite observed in the final microstructure will also be affected.

  13. Carbon-nitrogen interactions and biomass partitioning of Carex rostrata grown at three levels of nitrogen supply

    Energy Technology Data Exchange (ETDEWEB)

    Saarinen, T. [Helsinki Univ. (Finland). Dept. of Ecology and Systematics

    1996-12-31

    Biomass and production of vascular plants constitutes a major source of carbon input in peatlands. As rates of decomposition vary considerably with depth, the vertical distribution of biomass may substantially affect accumulation of carbon in peatlands. Therefore, allocation patterns between shoot and roots are particularly important when considering carbon balance of peatland ecosystems. The stimulatory effect of increasing atmospheric concentration of CO{sub 2} or photosynthesis may increase availability of carbon to most C3 plants. Availability of nitrogen may also alter both due to increased atmospheric deposition and changer in mineralisation rates associated with climate change. Most root-shoot partitioning models predict that allocation of biomass is dependent of the availability and uptake of carbon and nitrogen. A decrease in supply of carbon would favour allocation to shoots and a decrease in supply of nitrogen would increase allocation to roots. At a cellular level, non structural carbohydrates and free amino acids are thought to represent the biochemically available fraction of carbon and nitrogen, respectively. The aim of this work is study the long-term growth responses of Carex rostrata to changes in the availability of nitrogen. Special attention is paid to soluble sugars ant free amino acids, which may control partitioning of biomass. (10 refs.)

  14. Inhibition of Trehalose Breakdown Increases New Carbon Partitioning into Cellulosic Biomass in Nicotiana tabacum

    Energy Technology Data Exchange (ETDEWEB)

    Best, F.M.; Ferrieri, R.; Best, F.M.; Koenig, K.; McDonald, K.; Schueller, M.J.; Rogers, A.; Ferrieri, R.A.

    2011-01-18

    Validamycin A was used to inhibit in vivo trehalase activity in tobacco enabling the study of subsequent changes in new C partitioning into cellulosic biomass and lignin precursors. After 12-h exposure to treatment, plants were pulse labeled using radioactive {sup 11}CO{sub 2}, and the partitioning of isotope was traced into [{sup 11}C]cellulose and [{sup 11}C]hemicellulose, as well as into [{sup 11}C]phenylalanine, the precursor for lignin. Over this time course of treatment, new carbon partitioning into hemicellulose and cellulose was increased, while new carbon partitioning into phenylalanine was decreased. This trend was accompanied by a decrease in phenylalanine ammonia-lyase activity. After 4 d of exposure to validamycin A, we also measured leaf protein content and key C and N metabolite pools. Extended treatment increased foliar cellulose and starch content, decreased sucrose, and total amino acid and nitrate content, and had no effect on total protein.

  15. Seasonality and nitrogen supply modify carbon partitioning in understory vegetation of a boreal coniferous forest.

    Science.gov (United States)

    Hasselquist, N J; Metcalfe, D B; Marshall, J D; Lucas, R W; Högberg, P

    2016-03-01

    Given the strong coupling between the carbon (C) and nitrogen (N) cycles, there is substantial interest in understanding how N availability affects C cycling in terrestrial ecosystems, especially in ecosystems limited by N. However, most studies in temperate and boreal forests have focused on the effects of N addition on tree growth. By comparison, less is known about the effects of N availability on the cycling of C in understory vegetation despite some evidence that dwarf shrubs, mosses, and lichens play an important role in the forest C balance. In this study, we used an in situ 13CO2 pulse-labeling technique to examine the short-term dynamics of C partitioning in understory vegetation in three boreal Pinus sylvestris forest stands exposed to different rates of N addition: a low and high N addition that receive annual additions of NH4NO3 of 20 and 100 kg N/ha, respectively, and this is a typo. It should be an unfertilized control. Labeling was conducted at two distinct periods (early vs. late growing season), which provided a seasonal picture of how N addition affects C dynamics in understory vegetation. In contrast to what has been found in trees, there was no obvious trend in belowground C partitioning in ericaceous plants in response to N additions or seasonality. Increasing N addition led to a greater percentage of 13C being incorporated into ericaceous leaves with a high turnover, whereas high rates of N addition strongly reduced the incorporation of 13C into less degradable moss tissues. Addition of N also resulted in a greater percentage of the 13C label being respired back to the atmosphere and an overall reduction in total understory carbon use efficiency. Taken together, our results suggest a faster cycling of C in understory vegetation with increasing N additions; yet the magnitude of this general response was strongly dependent on the amount of N added and varied seasonally. These results provide some of the first in situ C and N partitioning

  16. Light Remodels Lipid Biosynthesis in Nannochloropsis gaditana by Modulating Carbon Partitioning between Organelles.

    Science.gov (United States)

    Alboresi, Alessandro; Perin, Giorgio; Vitulo, Nicola; Diretto, Gianfranco; Block, Maryse; Jouhet, Juliette; Meneghesso, Andrea; Valle, Giorgio; Giuliano, Giovanni; Maréchal, Eric; Morosinotto, Tomas

    2016-08-01

    The seawater microalga Nannochloropsis gaditana is capable of accumulating a large fraction of reduced carbon as lipids. To clarify the molecular bases of this metabolic feature, we investigated light-driven lipid biosynthesis in Nannochloropsis gaditana cultures combining the analysis of photosynthetic functionality with transcriptomic, lipidomic and metabolomic approaches. Light-dependent alterations are observed in amino acid, isoprenoid, nucleic acid, and vitamin biosynthesis, suggesting a deep remodeling in the microalgal metabolism triggered by photoadaptation. In particular, high light intensity is shown to affect lipid biosynthesis, inducing the accumulation of diacylglyceryl-N,N,N-trimethylhomo-Ser and triacylglycerols, together with the up-regulation of genes involved in their biosynthesis. Chloroplast polar lipids are instead decreased. This situation correlates with the induction of genes coding for a putative cytosolic fatty acid synthase of type 1 (FAS1) and polyketide synthase (PKS) and the down-regulation of the chloroplast fatty acid synthase of type 2 (FAS2). Lipid accumulation is accompanied by the regulation of triose phosphate/inorganic phosphate transport across the chloroplast membranes, tuning the carbon metabolic allocation between cell compartments, favoring the cytoplasm, mitochondrion, and endoplasmic reticulum at the expense of the chloroplast. These results highlight the high flexibility of lipid biosynthesis in N. gaditana and lay the foundations for a hypothetical mechanism of regulation of primary carbon partitioning by controlling metabolite allocation at the subcellular level. PMID:27325666

  17. The Mechanism of High Ductility for Novel High-Carbon Quenching-Partitioning-Tempering Martensitic Steel

    Science.gov (United States)

    Qin, Shengwei; Liu, Yu; Hao, Qingguo; Wang, Ying; Chen, Nailu; Zuo, Xunwei; Rong, Yonghua

    2015-09-01

    In this article, a novel quenching-partitioning-tempering (Q-P-T) process was applied to treat Fe-0.6C-1.5Mn-1.5Si-0.6Cr-0.05Nb hot-rolled high-carbon steel and the microstructures including retained austenite fraction and the average dislocation densities in both martensite and retained austenite were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, respectively. The Q-P-T steel exhibits high strength (1950 MPa) and elongation (12.4 pct). Comparing with the steel treated by traditional quenching and tempering (Q&T) process, the mechanism of high ductility for high-carbon Q-P-T steel is revealed as follows. Much more retained austenite existing in Q-P-T steel than in Q&T one remarkably enhances the ductility by the following two effects: the dislocation absorption by retained austenite effect and the transformation-induced plasticity effect. Besides, lower dislocation density in martensite matrix produced by Q-P-T process plays an important role in the improvement of ductility. However, some thin plates of twin-type martensite embedded in dislocation-type martensite matrix in high-carbon Q-P-T steel affect the further improvement of ductility.

  18. Photosynthesis and assimilate partitioning characteristics of the coconut palm as observed by carbon-14 labelling

    International Nuclear Information System (INIS)

    A technique was developed on the use of carbon dioxide(carbon-14 labelled) rapid labelling of foliage and to ascertain photosynthesis and partitioning characteristics of labelled assimilate into other parts of the coconut palm. An eight-year-old Tall x Tall young coconut palm growing under field conditions at Bandirippuwa Estate and with six developing bunches , was selected for this study. The labelling was carried out on a bright sunny day and soil was at field capacity. Seventh leaf from the youngest open leaf was used for labelling with 5 mCi of sodium bi carbonate (Carbon-14 labelled). The results revealed that within 24 hours, 60% of the labelled assimilate was partitioned into other parts of the palm and at the end of the seventh day about 18% of the labelled assimilate still remained in the labelled leaf. Among the developing bunches fifth and sixth bunches from the youngest developing bunch received more labelled assimilate than young developing bunches above them. It was revealed that partitioning of assimilate into various ''sinks'' is determined by the developmental stage or activeness of the ''sink''. The proportion of C-14 labelled carbon assimilate, partitioned into developing bunches was substantially low compared to the total amount of labelled carbon fixed by the labelled leaf. Further, it was observed that partitioning of assimilated labelled carbon into the young leaves above, as well as the mature leaves below the labelled leaf. The complex vascular anatomy of the palms could be attributed to this pattern of partitioning of assimilates into upper and lower leaves from the labelled leaf

  19. QQS orphan gene regulates carbon and nitrogen partitioning across species via NF-YC interactions.

    Science.gov (United States)

    Li, Ling; Zheng, Wenguang; Zhu, Yanbing; Ye, Huaxun; Tang, Buyun; Arendsee, Zebulun W; Jones, Dallas; Li, Ruoran; Ortiz, Diego; Zhao, Xuefeng; Du, Chuanlong; Nettleton, Dan; Scott, M Paul; Salas-Fernandez, Maria G; Yin, Yanhai; Wurtele, Eve Syrkin

    2015-11-24

    The allocation of carbon and nitrogen resources to the synthesis of plant proteins, carbohydrates, and lipids is complex and under the control of many genes; much remains to be understood about this process. QQS (Qua-Quine Starch; At3g30720), an orphan gene unique to Arabidopsis thaliana, regulates metabolic processes affecting carbon and nitrogen partitioning among proteins and carbohydrates, modulating leaf and seed composition in Arabidopsis and soybean. Here the universality of QQS function in modulating carbon and nitrogen allocation is exemplified by a series of transgenic experiments. We show that ectopic expression of QQS increases soybean protein independent of the genetic background and original protein content of the cultivar. Furthermore, transgenic QQS expression increases the protein content of maize, a C4 species (a species that uses 4-carbon photosynthesis), and rice, a protein-poor agronomic crop, both highly divergent from Arabidopsis. We determine that QQS protein binds to the transcriptional regulator AtNF-YC4 (Arabidopsis nuclear factor Y, subunit C4). Overexpression of AtNF-YC4 in Arabidopsis mimics the QQS-overexpression phenotype, increasing protein and decreasing starch levels. NF-YC, a component of the NF-Y complex, is conserved across eukaryotes. The NF-YC4 homologs of soybean, rice, and maize also bind to QQS, which provides an explanation of how QQS can act in species where it does not occur endogenously. These findings are, to our knowledge, the first insight into the mechanism of action of QQS in modulating carbon and nitrogen allocation across species. They have major implications for the emergence and function of orphan genes, and identify a nontransgenic strategy for modulating protein levels in crop species, a trait of great agronomic significance.

  20. Resolution of Adsorption and Partition Components of Organic Compounds on Black Carbons.

    Science.gov (United States)

    Chiou, Cary T; Cheng, Jianzhong; Hung, Wei-Nung; Chen, Baoliang; Lin, Tsair-Fuh

    2015-08-01

    Black carbons (BCs) may sequester non-ionic organic compounds by adsorption and/or partition to varying extents. Up to now, no experimental method has been developed to accurately resolve the combined adsorption and partition capacity of a compound on a BC. In this study, a unique "adsorptive displacement method" is introduced to reliably resolve the adsorption and partition components for a solute-BC system. It estimates the solute adsorption on a BC by the use of an adsorptive displacer to displace the adsorbed target solute into the solution phase. The method is validated by tests with uses of activated carbon as the model carbonaceous adsorbent, soil organic matter as the model carbonaceous partition phase, o-xylene and 1,2,3-trichlorobenzene as the reference solutes, and p-nitrophenol as the adsorptive displacer. Thereafter, the adsorption-partition resolution was completed for the two solutes on selected model BCs: four biochars and two National Institute of Standards and Technology (NIST) standard soots (SRM-2975 and SRM-1650b). The adsorption and partition components resolved for selected solutes with given BCs and their dependences upon solute properties enable one to cross-check the sorption data of other solutes on the same BCs. The resolved components also provide a theoretical basis for exploring the potential modes and extents of different solute uptakes by given BCs in natural systems. PMID:26114972

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

    Science.gov (United States)

    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

  2. Field-Scale Partitioning of Ecosystem Respiration Components Suggests Carbon Stabilization in a Bioenergy Grass Ecosystem

    Science.gov (United States)

    Black, C. K.; Miller, J. N.; Masters, M. D.; Bernacchi, C.; DeLucia, E. H.

    2014-12-01

    Annually-harvested agroecosystems have the potential to be net carbon sinks only if their root systems allocate sufficient carbon belowground and if this carbon is then retained as stable soil organic matter. Soil respiration measurements are the most common approach to evaluate the stability of soil carbon at experimental time scales, but valid inferences require the partitioning of soil respiration into root-derived (current-year C) and heterotrophic (older C) components. This partitioning is challenging at the field scale because roots and soil are intricately mixed and physical separation in impossible without disturbing the fluxes to be measured. To partition soil flux and estimate the C sink potential of bioenergy crops, we used the carbon isotope difference between C3 and C4 plant species to quantify respiration from roots of three C4 grasses (maize, Miscanthus, and switchgrass) grown in a site with a mixed cropping history where respiration from the breakdown of old soil carbon has a mixed C3-C4 signature. We used a Keeling plot approach to partition fluxes both at the soil surface using soil chambers and from the whole field using continuous flow sampling of air within and above the canopy. Although soil respiration rates from perennial grasses were higher than those from maize, the isotopic signature of respired carbon indicated that the fraction of soil CO2 flux attributable to current-year vegetation was 1.5 (switchgrass) to 2 (Miscanthus) times greater in perennials than that from maize, indicating that soil CO2 flux came mostly from roots and turnover of soil organic matter was reduced in the perennial crops. This reduction in soil heterotrophic respiration, combined with the much greater quantities of C allocated belowground by perennial grasses compared to maize, suggests that perennial grasses grown as bioenergy crops may be able to provide an additional climate benefit by acting as carbon sinks in addition to reducing fossil fuel consumption.

  3. On the choice of the driving temperature for eddy-covariance carbon dioxide flux partitioning

    DEFF Research Database (Denmark)

    Lasslop, G.; Migliavacca, M.; Bohrer, G.;

    2012-01-01

    Networks that merge and harmonise eddy-covariance measurements from many different parts of the world have become an important observational resource for ecosystem science. Empirical algorithms have been developed which combine direct observations of the net ecosystem exchange of carbon dioxide...... uncertainties of the partitioned fluxes. The semi-empirical models used in flux partitioning algorithms require temperature observations as input, but as respiration takes place in many parts of an ecosystem, it is unclear which temperature input - air, surface, bole, or soil at a specific depth - should...... algorithms with air and soil temperature. We found the time lag (phase shift) between air and soil temperatures explains the differences in the GPP and Reco estimates when using either air or soil temperatures for flux partitioning. The impact of the source of temperature data on other derived ecosystem...

  4. Partitioning Behavior of Organic Contaminants in Carbon Storage Environments: A Critical Review

    Energy Technology Data Exchange (ETDEWEB)

    Burant, Aniela; Lowry, Gregory V; Karamalidis, Athanasios K

    2012-12-04

    Carbon capture and storage is a promising strategy for mitigating the CO{sub 2} contribution to global climate change. The large scale implementation of the technology mandates better understanding of the risks associated with CO{sub 2} injection into geologic formations and the subsequent interactions with groundwater resources. The injected supercritical CO{sub 2} (sc-CO{sub 2}) is a nonpolar solvent that can potentially mobilize organic compounds that exist at residual saturation in the formation. Here, we review the partitioning behavior of selected organic compounds typically found in depleted oil reservoirs in the residual oil–brine–sc-CO{sub 2} system under carbon storage conditions. The solubility of pure phase organic compounds in sc-CO{sub 2} and partitioning of organic compounds between water and sc-CO{sub 2} follow trends predicted based on thermodynamics. Compounds with high volatility and low aqueous solubility have the highest potential to partition to sc-CO{sub 2}. The partitioning of low volatility compounds to sc-CO{sub 2} can be enhanced by co-solvency due to the presence of higher volatility compounds in the sc-CO{sub 2}. The effect of temperature, pressure, salinity, pH, and dissolution of water molecules into sc-CO{sub 2} on the partitioning behavior of organic compounds in the residual oil-brine-sc-CO{sub 2} system is discussed. Data gaps and research needs for models to predict the partitioning of organic compounds in brines and from complex mixtures of oils are presented. Models need to be able to better incorporate the effect of salinity and co-solvency, which will require more experimental data from key classes of organic compounds.

  5. Role of magnesium in carbon partitioning and alleviating photooxidative damage.

    Science.gov (United States)

    Cakmak, Ismail; Kirkby, Ernest A

    2008-08-01

    Magnesium (Mg) deficiency exerts a major influence on the partitioning of dry matter and carbohydrates between shoots and roots. One of the very early reactions of plants to Mg deficiency stress is the marked increase in the shoot-to-root dry weight ratio, which is associated with a massive accumulation of carbohydrates in source leaves, especially of sucrose and starch. These higher concentrations of carbohydrates in Mg-deficient leaves together with the accompanying increase in shoot-to-root dry weight ratio are indicative of a severe impairment in phloem export of photoassimilates from source leaves. Studies with common bean and sugar beet plants have shown that Mg plays a fundamental role in phloem loading of sucrose. At a very early stage of Mg deficiency, phloem export of sucrose is severely impaired, an effect that occurs before any noticeable changes in shoot growth, Chl concentration or photosynthetic activity. These findings suggest that accumulation of carbohydrates in Mg-deficient leaves is caused directly by Mg deficiency stress and not as a consequence of reduced sink activity. The role of Mg in the phloem-loading process seems to be specific; resupplying Mg for 12 or 24 h to Mg-deficient plants resulted in a very rapid recovery of sucrose export. It appears that the massive accumulation of carbohydrates and related impairment in photosynthetic CO2 fixation in Mg-deficient leaves cause an over-reduction in the photosynthetic electron transport chain that potentiates the generation of highly reactive O2 species (ROS). Plants respond to Mg deficiency stress by marked increases in antioxidative capacity of leaves, especially under high light intensity, suggesting that ROS generation is stimulated by Mg deficiency in chloroplasts. Accordingly, it has been found that Mg-deficient plants are very susceptible to high light intensity. Exposure of Mg-deficient plants to high light intensity rapidly induced leaf chlorosis and necrosis, an outcome that was

  6. Membrane-Transport Systems for Sucrose in Relation to Whole-Plant Carbon Partitioning

    Institute of Scientific and Technical Information of China (English)

    Brian G. Ayre

    2011-01-01

    T Sucrose is the principal product of photosynthesis used for the distribution of assimilated carbon in plants. Transport mechanisms and efficiency influence photosynthetic productivity by relieving product inhibition and contribute to plant vigor by controlling source/sink relationships and biomass partitioning. Sucrose is synthesized in the cytoplasm and may move cell to cell through plasmodesmata or may cross membranes to be compartmentalized or exported to the apoplasm for uptake into adjacent cells. As a relatively large polar compound, sucrose requires proteins to facilitate efficient membrane transport. Transport across the tonoplast by facilitated diffusion, antiport with protons, and symport with protons have been proposed; for transport across plasma membranes, symport with protons and a mechanism resembling facilitated diffusion are evident. Despite decades of research, only symport with protons is well established at the molecular level. This review aims to integrate recent and older studies on sucrose flux across membranes with principles of whole-plant carbon partitioning.

  7. Carbon partitioning between oil and carbohydrates in developing oat (Avena sativa L.) seeds.

    Science.gov (United States)

    Ekman, Asa; Hayden, Daniel M; Dehesh, Katayoon; Bülow, Leif; Stymne, Sten

    2008-01-01

    Cereals accumulate starch in the endosperm as their major energy reserve in the grain. In most cereals the embryo, scutellum, and aleurone layer are high in oil, but these tissues constitute a very small part of the total seed weight. However, in oat (Avena sativa L.) most of the oil in kernels is deposited in the same endosperm cells that accumulate starch. Thus oat endosperm is a desirable model system to study the metabolic switches responsible for carbon partitioning between oil and starch synthesis. A prerequisite for such investigations is the development of an experimental system for oat that allows for metabolic flux analysis using stable and radioactive isotope labelling. An in vitro liquid culture system, developed for detached oat panicles and optimized to mimic kernel composition during different developmental stages in planta, is presented here. This system was subsequently used in analyses of carbon partitioning between lipids and carbohydrates by the administration of 14C-labelled sucrose to two cultivars having different amounts of kernel oil. The data presented in this study clearly show that a higher amount of oil in the high-oil cultivar compared with the medium-oil cultivar was due to a higher proportion of carbon partitioning into oil during seed filling, predominantly at the earlier stages of kernel development.

  8. Carbon monoxide exchange and partitioning of a managed mountain meadow

    Science.gov (United States)

    Hammerle, Albin; Kitz, Florian; Spielmann, Felix; Gerdel, Katharina; Wohlfahrt, Georg

    2016-04-01

    With an average mole fraction of 100 ppb carbon monoxide (CO) plays a critical role in atmospheric chemistry and thus has an indirect global warming potential. While sources/sinks of CO on land at least partially cancel out each other, the magnitude of CO sources and sinks is highly uncertain. Even if direct CO fluxes from/to land ecosystems are very much likely clearly lower in magnitude compared to anthropogenic emissions, biomass burning, emissions from chemical precursors and the OH sink, it may be premature to neglect any direct contributions of land ecosystems to the CO budget. In addition, changes in global climate and resulting changes in global productivity may require re-evaluating older data and assumptions. One major reason for the large uncertainty is a general scarcity of empirical data. An additional factor contributing to the uncertainty is the lack of ecosystem-scale CO exchange measurements, i.e. CO flux data that encompass all sources and sinks within an ecosystem. Here we present data on continuous eddy covariance measurements of CO-fluxes above a managed mountain grassland in combination with soil chamber flux measurements, within- and above-canopy concentration profiles and an inverse Lagrangian analysis to disentangle sinks and sources of CO. Results show the grassland ecosystem to be a net source for CO during daytime, with increasing flux rates at higher solar radiation. At night, if at all, the meadow is a slight sink for CO. The same holds true regarding the soil flux measurements. Additionally, a two-month rainout experiment revealed hardly any differences in CO soil fluxes between rainout- and control-plots unless extremely dry conditions were reached.

  9. Partition and poliomyelitis: an investigation of the polio disparity affecting Muslims during India's eradication program.

    Directory of Open Access Journals (Sweden)

    Rashid S Hussain

    Full Text Available Significant disparities in the incidence of polio existed during its eradication campaign in India. In 2006, Muslims, who comprise 16% of the population in affected states, comprised 70% of paralytic polio cases. This disparity was initially blamed on the Muslims and a rumor that the vaccination program was a plot to sterilize their children. Using the framework of structural violence, this paper describes how the socio-political and historical context of Muslim populations in India shaped the polio disparity.A qualitative study utilizing methods of rapid ethnography was conducted from May-August 2009 in Aligarh, Uttar Pradesh, India. Field methods included participant observation of vaccination teams, historical document research, and 107 interviews with both Global Polio Eradication Initiative (GPEI stakeholders and families with vaccine-eligible children. Almost all respondents agreed that Aligarh was a highly segregated city, mostly due to riots after Partition and during the 1990s. Since the formation of segregated neighborhoods, most respondents described that "Muslim areas" had been underdeveloped compared to "Hindu areas," facilitating the physical transmission of poliovirus. Distrust of the government and resistance to vaccination were linked to this disparate development and fears of sterilization influenced by the "Family Planning Program" from 1976-1977.Ethnic violence and social marginalization since the Partition and during the rise of Hindu nationalism led to distrust of the government, the formation of segregated slums, and has made Muslims victims of structural violence. This led to the creation of disease-spreading physical environments, lowered vaccine efficacy, and disproportionately higher levels of resistance to vaccination. The causes of the polio disparity found in this study elucidate the nature of possible other health disparities affecting minorities in India.This study is limited by the manual coding of the

  10. Partition and Poliomyelitis: An Investigation of the Polio Disparity Affecting Muslims during India's Eradication Program

    Science.gov (United States)

    Hussain, Rashid S.; McGarvey, Stephen T.; Fruzzetti, Lina M.

    2015-01-01

    Background Significant disparities in the incidence of polio existed during its eradication campaign in India. In 2006, Muslims, who comprise 16% of the population in affected states, comprised 70% of paralytic polio cases. This disparity was initially blamed on the Muslims and a rumor that the vaccination program was a plot to sterilize their children. Using the framework of structural violence, this paper describes how the socio-political and historical context of Muslim populations in India shaped the polio disparity. Methods and Findings A qualitative study utilizing methods of rapid ethnography was conducted from May-August 2009 in Aligarh, Uttar Pradesh, India. Field methods included participant observation of vaccination teams, historical document research, and 107 interviews with both Global Polio Eradication Initiative (GPEI) stakeholders and families with vaccine-eligible children. Almost all respondents agreed that Aligarh was a highly segregated city, mostly due to riots after Partition and during the 1990s. Since the formation of segregated neighborhoods, most respondents described that "Muslim areas" had been underdeveloped compared to "Hindu areas," facilitating the physical transmission of poliovirus. Distrust of the government and resistance to vaccination were linked to this disparate development and fears of sterilization influenced by the "Family Planning Program" from 1976-1977. Conclusions Ethnic violence and social marginalization since the Partition and during the rise of Hindu nationalism led to distrust of the government, the formation of segregated slums, and has made Muslims victims of structural violence. This led to the creation of disease-spreading physical environments, lowered vaccine efficacy, and disproportionately higher levels of resistance to vaccination. The causes of the polio disparity found in this study elucidate the nature of possible other health disparities affecting minorities in India. Limitations This study is

  11. Carbon partitioning in Arabidopsis thaliana is a dynamic process controlled by the plants metabolic status and its circadian clock

    Science.gov (United States)

    Kölling, Katharina; Thalmann, Matthias; Müller, Antonia; Jenny, Camilla; Zeeman, Samuel C

    2015-01-01

    Abstract Plant growth involves the coordinated distribution of carbon resources both towards structural components and towards storage compounds that assure a steady carbon supply over the complete diurnal cycle. We used 14CO2 labelling to track assimilated carbon in both source and sink tissues. Source tissues exhibit large variations in carbon allocation throughout the light period. The most prominent change was detected in partitioning towards starch, being low in the morning and more than double later in the day. Export into sink tissues showed reciprocal changes. Fewer and smaller changes in carbon allocation occurred in sink tissues where, in most respects, carbon was partitioned similarly, whether the sink leaf assimilated it through photosynthesis or imported it from source leaves. Mutants deficient in the production or remobilization of leaf starch exhibited major alterations in carbon allocation. Low-starch mutants that suffer from carbon starvation at night allocated much more carbon into neutral sugars and had higher rates of export than the wild type, partly because of the reduced allocation into starch, but also because of reduced allocation into structural components. Moreover, mutants deficient in the plant’s circadian system showed considerable changes in their carbon partitioning pattern suggesting control by the circadian clock. This work focusses on the temporal changes in the allocation and transport of photoassimilates within Arabidopsis rosettes, helping to fill a gap in our understanding of plant growth. Using short pulses of 14C-labelled carbon dioxide, we quantified how much carbon is used for growth and how much is stored as starch for use at night. In source leaves, partitioning is surprisingly dynamic during the day, even though photosynthesis is relatively constant, while in sink leaves, utilisation is more constant. Furthermore, by analysing metabolic mutants and clock mutants, and by manipulating the growth conditions, we show that

  12. Polychlorinated biphenyls (PCBs) in industrial and municipal effluents: Concentrations, congener profiles, and partitioning onto particulates and organic carbon

    International Nuclear Information System (INIS)

    Wastewater effluent samples were collected in the summer of 2009 from 16 different locations which included municipal and industrial wastewater treatment plants and petrochemical industrial outfalls in the Houston area. The effluent samples were analyzed for all 209 polychlorinated biphenyls (PCBs) congeners using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) using the USEPA method 1668A. The total PCBs (∑ 209) concentration in the dissolved medium ranged from 1.01 to 8.12 ng/L and ranged from 2.03 to 31.2 ng/L in the suspended medium. Lighter PCB congeners exhibited highest concentrations in the dissolved phase whereas, in the suspended phase, heavier PCBs exhibited the highest concentrations. The PCB homolog concentrations were dominated by monochlorobiphenyls through hexachlorobiphenyls, with dichlorobiphenyls exhibiting the highest concentration amongst them at most of the effluent outfalls, in the suspended phase. Both total suspended solids (TSS) and various organic carbon fractions played an important role in the distribution of the suspended fractions of PCBs in the effluents. The log Koc values determined in the effluents suggest that effluent PCB loads might have more risk and impact than what standard partitioning models predict. - Highlights: • 209 PCB congeners were measured in 16 different municipal and industrial effluents. • PCB congener differences were elucidated for the various effluent types. • In addition to log Kow, organic carbon and TSS affect partitioning of PCBs. • High concentrations of homolog 2 maybe due to biotransformation of PCBs

  13. One-Step Quenching and Partitioning Heat Treatment of Medium Carbon Low Alloy Steel

    Science.gov (United States)

    Tariq, Fawad; Baloch, Rasheed Ahmed

    2014-05-01

    This paper presents the results of novel one-step quenching and partitioning (Q&P) heat treatment conducted on medium carbon low alloy steel sheet. Samples were austenitised at 1193 K followed by interrupted quenching at 473 K for different partitioning times and finally they were quenched in water. Dilatometry was employed for selection of treatment temperatures. Optical and scanning electron microscopy was carried out to examine the microstructural changes. Volume fraction of retained austenite was measured by x-ray diffraction technique. Resulting microstructures were correlated with the mechanical properties such hardness, tensile strength, elongation, impact absorbed energy, etc. The notch tensile and fracture toughness properties of Q&P steels are still lacking therefore notch tensile strength and plain strain fracture toughness tests were conducted and results are reported here. Results of Q&P treatments were also compared with the properties obtained by conventional Quenching and Tempering (Q&T) and normalizing treatments. Optimum strength-ductility balance of about 2000 MPa tensile strength with 11% elongation was achieved in samples quenched at 473 K and isothermally partitioned for 100 s. Higher ductility of Q&P steel was attributed to the presence of 6.8% film-type interlath retained austenite. Fine-grained martensitic structure with high density of interphase boundaries imparted ultrahigh strength. It was further noted that the impact toughness, notch tensile strength and fracture toughness of 1000 s partitioned samples was higher than 100 s partitioned samples. Possible reasons for high toughness are synergetic effect of recovery of dislocations, partial loss of martensite tetragonality and precipitation of fine transition carbides.

  14. Thallium occurrence and partitioning in soils and sediments affected by mining activities in Madrid province (Spain).

    Science.gov (United States)

    Gomez-Gonzalez, M A; Garcia-Guinea, J; Laborda, F; Garrido, F

    2015-12-01

    Thallium (Tl) and its compounds are toxic to biota even at low concentrations but little is known about Tl concentration and speciation in soils. An understanding of the source, mobility, and dispersion of Tl is necessary to evaluate the environmental impact of Tl pollution cases. In this paper, we examine the Tl source and dispersion in two areas affected by abandoned mine facilities whose residues remain dumped on-site affecting to soils and sediments of natural water courses near Madrid city (Spain). Total Tl contents and partitioning in soil solid phases as determined by means of a sequential extraction procedure were also examined in soils along the riverbeds of an ephemeral and a permanent streams collecting water runoff and drainage from the mines wastes. Lastly, electronic microscopy and cathodoluminescence probe are used as a suitable technique for Tl elemental detection on thallium-bearing phases. Tl was found mainly bound to quartz and alumino-phyllosilicates in both rocks and examined soils. Besides, Tl was also frequently found associated to organic particles and diatom frustules in all samples from both mine scenarios. These biogenic silicates may regulate the transfer of Tl into the soil-water system. PMID:26218566

  15. Thallium occurrence and partitioning in soils and sediments affected by mining activities in Madrid province (Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Gonzalez, M.A.; Garcia-Guinea, J. [National Museum of Natural Sciences, CSIC, Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Laborda, F. [Group of Analytical Spectroscopy and Sensors Group, Institute of Environmental Sciences, University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain); Garrido, F., E-mail: fernando.garrido@mncn.csic.es [National Museum of Natural Sciences, CSIC, Jose Gutierrez Abascal 2, 28006 Madrid (Spain)

    2015-12-01

    Thallium (Tl) and its compounds are toxic to biota even at low concentrations but little is known about Tl concentration and speciation in soils. An understanding of the source, mobility, and dispersion of Tl is necessary to evaluate the environmental impact of Tl pollution cases. In this paper, we examine the Tl source and dispersion in two areas affected by abandoned mine facilities whose residues remain dumped on-site affecting to soils and sediments of natural water courses near Madrid city (Spain). Total Tl contents and partitioning in soil solid phases as determined by means of a sequential extraction procedure were also examined in soils along the riverbeds of an ephemeral and a permanent streams collecting water runoff and drainage from the mines wastes. Lastly, electronic microscopy and cathodoluminescence probe are used as a suitable technique for Tl elemental detection on thallium-bearing phases. Tl was found mainly bound to quartz and alumino-phyllosilicates in both rocks and examined soils. Besides, Tl was also frequently found associated to organic particles and diatom frustules in all samples from both mine scenarios. These biogenic silicates may regulate the transfer of Tl into the soil-water system. - Highlights: • Abandoned mine residues are Tl sources in soils of Madrid catchment area. • Tl was associated to quartz and aluminosilicates in both rocks and soils. • Tl was frequently found associated to organic particles and diatom frustules. • Cathodoluminescence is a suitable technique for Tl detection on soils and rocks.

  16. Thallium occurrence and partitioning in soils and sediments affected by mining activities in Madrid province (Spain).

    Science.gov (United States)

    Gomez-Gonzalez, M A; Garcia-Guinea, J; Laborda, F; Garrido, F

    2015-12-01

    Thallium (Tl) and its compounds are toxic to biota even at low concentrations but little is known about Tl concentration and speciation in soils. An understanding of the source, mobility, and dispersion of Tl is necessary to evaluate the environmental impact of Tl pollution cases. In this paper, we examine the Tl source and dispersion in two areas affected by abandoned mine facilities whose residues remain dumped on-site affecting to soils and sediments of natural water courses near Madrid city (Spain). Total Tl contents and partitioning in soil solid phases as determined by means of a sequential extraction procedure were also examined in soils along the riverbeds of an ephemeral and a permanent streams collecting water runoff and drainage from the mines wastes. Lastly, electronic microscopy and cathodoluminescence probe are used as a suitable technique for Tl elemental detection on thallium-bearing phases. Tl was found mainly bound to quartz and alumino-phyllosilicates in both rocks and examined soils. Besides, Tl was also frequently found associated to organic particles and diatom frustules in all samples from both mine scenarios. These biogenic silicates may regulate the transfer of Tl into the soil-water system.

  17. Light Competition and Carbon Partitioning-Allocation in an improved Forest Ecosystem Model

    Science.gov (United States)

    Collalti, Alessio; Santini, Monia; Valentini Valentini, Riccardo

    2010-05-01

    . Hence, the presence of a cohort in a storey determines the amount of light received for the photosynthetic processes. The population density (numbers of trees per cell) represents a good competition index for determining the tree crown structure and tree crown dimension within a forest population. The tree crown tend to branch out horizontally to intercept as much light as possible. The model assess the structure of the tree crown both vertically and horizontally on the base of the population density and it up-scales the result to the whole stand. The canopy depth and the percentage of horizontal coverage determines moreover a crowding competition index that lead to a specific biomass partitioning-allocation ratio among the different tree components (foliage, roots and stem) and especially for the stem affecting Height-Diameter (at breast height) ratio. In this model, Height-Diameter ratio is used as an alternative competition index in determining the vigour and the strength of competition on free growth status of trees. The forest dominant vegetative cover affects moreover the presence of a dominated layer, it influences its yield and its Carbon stocking capacity and hence it influences the forest ecosystem CO2 carbon balance. From this model it is possible to simulate the impact of Climate Change on forests, the feedback of one or more dominated layers in terms of CO2 uptake in a forest stand and the effects of forest management activities for the next years.

  18. Carbon partitioning in Arabidopsis thaliana is a dynamic process controlled by the plants metabolic status and its circadian clock

    OpenAIRE

    Kölling, Katharina; Thalmann, Matthias; Müller, Antonia; Jenny, Camilla; Zeeman, Samuel C.

    2015-01-01

    Abstract Plant growth involves the coordinated distribution of carbon resources both towards structural components and towards storage compounds that assure a steady carbon supply over the complete diurnal cycle. We used 14CO2 labelling to track assimilated carbon in both source and sink tissues. Source tissues exhibit large variations in carbon allocation throughout the light period. The most prominent change was detected in partitioning towards starch, being low in the morning and more than...

  19. Microstructure, tensile and toughness properties after quenching and partitioning treatments of a medium-carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Paravicini Bagliani, E., E-mail: epbagliani@tenaris.com [Tenaris Dalmine R and D, Dalmine S.p.A., Piazza Caduti 6 luglio 1944 1, 24044 Dalmine, BG (Italy); Santofimia, M.J.; Zhao, L. [Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands); Materials Innovation Institute (M2i), Mekelweg 2, 2628 CD Delft (Netherlands); Sietsma, J. [Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands); Anelli, E. [Tenaris Dalmine R and D, Dalmine S.p.A., Piazza Caduti 6 luglio 1944 1, 24044 Dalmine, BG (Italy)

    2013-01-01

    The effect of different microstructures on the tensile and toughness properties of a low alloy medium carbon steel (0.28C-1.4Si-0.67Mn-1.49Cr-0.56Mo wt%) was investigated, comparing the properties obtained after the application of selected quenching and partitioning (Q and P) and quenching and tempering (Q and T) treatments. After Q and T the strength-toughness combination was the lowest, whereas the best combination was achieved by Q and P, as a result of the carbon depletion of the martensite and the high stabilization of the austenite. Nonetheless, the presence of islands of martensite/austenite (MA) constituents after Q and P treatments prevented the achievement of toughness levels comparable to the ones currently obtainable with other steels and heat treatments.

  20. Partitioning of organic carbon among density fractions in surface sediments of Fiordland, New Zealand

    Science.gov (United States)

    Cui, Xingqian; Bianchi, Thomas S.; Hutchings, Jack A.; Savage, Candida; Curtis, Jason H.

    2016-03-01

    Transport of particles plays a major role in redistributing organic carbon (OC) along coastal regions. In particular, the global importance of fjords as sites of carbon burial has recently been shown to be even more important than previously thought. In this study, we used six surface sediments from Fiordland, New Zealand, to investigate the transport of particles and OC based on density fractionation. Bulk, biomarker, and principle component analysis were applied to density fractions with ranges of 2.5 g cm-3. Our results found various patterns of OC partitioning at different locations along fjords, likely due to selective transport of higher density but smaller size particles along fjord head-to-mouth transects. We also found preferential leaching of certain biomarkers (e.g., lignin) over others (e.g., fatty acids) during the density fractionation procedure, which altered lignin-based degradation indices. Finally, our results indicated various patterns of OC partitioning on density fractions among different coastal systems. We further propose that a combination of particle size-density fractionation is needed to better understand transport and distribution of particles and OC.

  1. On the choice of the driving temperature for eddy-covariance carbon dioxide flux partitioning

    Directory of Open Access Journals (Sweden)

    G. Lasslop

    2012-07-01

    Full Text Available Networks that merge and harmonise eddy-covariance measurements from many different parts of the world have become an important observational resource for ecosystem science. Empirical algorithms have been developed which combine direct observations of the net ecosystem exchange of carbon dioxide with simple empirical models to disentangle photosynthetic (GPP and respiratory fluxes (Reco. The increasing use of these estimates for the analysis of climate sensitivities, model evaluation, and calibration demands a thorough understanding of assumptions in the analysis process and the resulting uncertainties of the partitioned fluxes. The semi-empirical models used in flux partitioning algorithms require temperature observations as input, but as respiration takes place in many parts of an ecosystem, it is unclear which temperature input – air, surface, bole, or soil at a specific depth – should be used. This choice is a source of uncertainty and potential biases.

    In this study we analysed the correlation between different temperature observations and nighttime NEE (which equals nighttime respiration across FLUXNET sites to understand the potential of the different temperature observations as input for the flux partitioning model. We found that the differences in the correlation between different temperature data streams and nighttime NEE are small and depend on the selection of sites. We investigated the effects of the choice of the temperature data by running two flux partitioning algorithms with air and soil temperature. We found the time lag (phase shift between air and soil temperatures explains the differences in the GPP and Reco estimates when using either air or soil temperatures for flux partitioning. The impact of the source of temperature data on other derived ecosystem parameters was estimated, and the strongest impact was found for the temperature sensitivity. Overall, this study suggests

  2. On the choice of the driving temperature for eddy-covariance carbon dioxide flux partitioning

    Directory of Open Access Journals (Sweden)

    G. Lasslop

    2012-12-01

    Full Text Available Networks that merge and harmonise eddy-covariance measurements from many different parts of the world have become an important observational resource for ecosystem science. Empirical algorithms have been developed which combine direct observations of the net ecosystem exchange of carbon dioxide with simple empirical models to disentangle photosynthetic (GPP and respiratory fluxes (Reco. The increasing use of these estimates for the analysis of climate sensitivities, model evaluation and calibration demands a thorough understanding of assumptions in the analysis process and the resulting uncertainties of the partitioned fluxes. The semi-empirical models used in flux partitioning algorithms require temperature observations as input, but as respiration takes place in many parts of an ecosystem, it is unclear which temperature input – air, surface, bole, or soil at a specific depth – should be used. This choice is a source of uncertainty and potential biases. In this study, we analysed the correlation between different temperature observations and nighttime NEE (which equals nighttime respiration across FLUXNET sites to understand the potential of the different temperature observations as input for the flux partitioning model. We found that the differences in the correlation between different temperature data streams and nighttime NEE are small and depend on the selection of sites. We investigated the effects of the choice of the temperature data by running two flux partitioning algorithms with air and soil temperature. We found the time lag (phase shift between air and soil temperatures explains the differences in the GPP and Reco estimates when using either air or soil temperatures for flux partitioning. The impact of the source of temperature data on other derived ecosystem parameters was estimated, and the strongest impact was found for the temperature sensitivity. Overall, this study suggests that the

  3. Partitioning of catchment water budget and its implications for ecosystem carbon exchange

    Directory of Open Access Journals (Sweden)

    D. Lee

    2009-12-01

    Full Text Available Spatially averaged annual carbon budget is one of the key information to understand ecosystem response and feedback to climate change. Water availability is a primary constraint of carbon uptake in many ecosystems and therefore the estimation of transpiration (T may serve as an alternative to quantify carbon budget. To apply this concept, we estimated long-term steady state water budget for the Han River basin (~26 000 km2 in Korea and examined its implication for catchment scale carbon exchange. For this, the catchment scale evapotranspiration (ET was derived from the long term precipitation (P and discharge (Q data. Then, using stable isotope data of P and Q along with hydrometeorological information, ET was partitioned into evaporation from soil and water surfaces (ES, evaporation from intercepted rainfall (El, and transpiration. ES was identified as a minor component of ET in the study areas regardless of the catchment scales. T was estimated from ET after accounting for El and ES. For the Han River basin, the estimated annual T from 1966 to 2007 was 22–31% of annual P and the proportion decreased with increasing P. Assuming that T further constrains catchment scale carbon uptake in terms of water use efficiency (WUE, we examined the possibility of using T as a relative measure for the strength and temporal changes of carbon uptake capacity. The proposed relations provide a simple and practical way to assess the distribution and strength of carbon sink.

  4. Application of ultrafiltration and stable isotopic amendments to field studies of mercury partitioning to filterable carbon in lake water and overland runoff

    Science.gov (United States)

    Babiarz, C.L.; Hurley, J.P.; Krabbenhoft, D.P.; Gilmour, C.; Branfireun, B.A.

    2003-01-01

    Results from pilot studies on colloidal phase transport of newly deposited mercury in lake water and overland runoff demonstrate that the combination of ultrafiltration, and stable isotope amendment techniques is a viable tool for the study of mercury partitioning to filterable carbon. Ultrafiltration mass balance calculations were generally excellent, averaging 97.3, 96.1 and 99.8% for dissolved organic carbon (DOC), total mercury (HgT), and methylmercury (MeHg), respectively. Sub nanogram per liter quantities of isotope were measurable, and the observed phase distribution from replicate ultrafiltration separations on lake water agreed within 20%. We believe the data presented here are the first published colloidal phase mercury data on lake water and overland runoff from uncontaminated sites. Initial results from pilot-scale lake amendment experiments indicate that the choice of matrix used to dissolve the isotope did not affect the initial phase distribution of the added mercury in the lake. In addition there was anecdotal evidence that native MeHg was either recently produced in the system, or at a minimum, that this 'old' MeHg partitions to the same subset of DOC that binds the amended mercury. Initial results from pilot-scale overland runoff experiments indicate that less than 20% of newly deposited mercury was transported in the filterable fraction (<0.7 ??m). There is some indication of colloidal phase enrichment of mercury in runoff compared to the phase distribution of organic carbon, but the mechanism of this enrichment is unclear. The phase distribution of newly deposited mercury can differ from that of organic carbon and native mercury, suggesting that the quality of the carbon (available ligands), not the quantity of carbon, regulates partitioning. Further characterization of DOC is needed to clarify the underlying mechanisms. ?? 2002 Elsevier Science B.V. All rights reserved.

  5. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States); Davidson, Eric [Univ. of Arizona, Tucson, AZ (United States); Finzi, Adrien [Boston Univ., MA (United States); Wehr, Richdard [Harvard Univ., Cambridge, MA (United States); Moorcroft, Paul [Harvard Univ., Cambridge, MA (United States)

    2016-01-28

    1. Objectives This project combines automated in situ observations of the isotopologues of CO2 with root observations, novel experimental manipulations of belowground processes, and isotope-enabled ecosystem modeling to investigate mechanisms of below- vs. aboveground carbon sequestration at the Harvard Forest Environmental Measurements Site (EMS). The proposed objectives, which have now been largely accomplished, include: A. Partitioning of net ecosystem CO2 exchange (NEE) into photosynthesis and respiration using long-term continuous observations of the isotopic composition of NEE, and analysis of their dynamics ; B. Investigation of the influence of vegetation phenology on the timing and magnitude of carbon allocated belowground using measurements of root growth and indices of belowground autotrophic vs. heterotrophic respiration (via trenched plots and isotope measurements); C. Testing whether plant allocation of carbon belowground stimulates the microbial decomposition of soil organic matter, using in situ rhizosphere simulation experiments wherein realistic quantities of artificial isotopically-labeled exudates are released into the soil; and D. Synthesis and interpretation of the above data using the Ecosystem Demography Model 2 (ED2). 2. Highlights Accomplishments: • Our isotopic eddy flux record has completed its 5th full year and has been used to independently estimate ecosystem-scale respiration and photosynthesis. • Soil surface chamber isotopic flux measurements were carried out during three growing seasons, in conjunction with a trenching manipulation. Key findings to date (listed by objective): A. Partitioning of Net Ecosystem Exchange: 1. Ecosystem respiration is lower during the day than at night—the first robust evidence of the inhibition of leaf respiration by light (the “Kok effect”) at the ecosystem scale. 2. Because it neglects the Kok effect, the standard NEE partitioning approach overestimates ecosystem photosynthesis (by ~25%) and

  6. Partitioning MOF-5 into Confined and Hydrophobic Compartments for Carbon Capture under Humid Conditions.

    Science.gov (United States)

    Ding, Nan; Li, Haiwei; Feng, Xiao; Wang, Qianyou; Wang, Shan; Ma, Li; Zhou, Junwen; Wang, Bo

    2016-08-17

    Metal-organic frameworks (MOFs), by virtue of their remarkable uptake capability, selectivity, and ease of regeneration, hold great promise for carbon capture from fossil fuel combustion. However, their stability toward moisture together with the competitive adsorption of water against CO2 drastically dampens their capacity and selectivity under real humid flue gas conditions. In this work, an effective strategy was developed to tackle the above obstacles by partitioning the channels of MOFs into confined, hydrophobic compartments by in situ polymerization of aromatic acetylenes. Specifically, polynaphthylene was formed via a radical reaction inside the channels of MOF-5 and served as partitions without altering the underlying structure of the framework. Compared with pristine MOF-5, the resultant material (PN@MOF-5) exhibits a doubled CO2 capacity (78 vs 38 cm(3)/g at 273 K and 1 bar), 23 times higher CO2/N2 selectivity (212 vs 9), and significantly improved moisture stability. The dynamic CO2 adsorption capacity can be largely maintained (>90%) under humid conditions during cycles. This strategy can be applied to other MOF materials and may shed light on the design of new MOF-polymer materials with tunable pore sizes and environments to promote their practical applications. PMID:27477091

  7. Partitioning MOF-5 into Confined and Hydrophobic Compartments for Carbon Capture under Humid Conditions.

    Science.gov (United States)

    Ding, Nan; Li, Haiwei; Feng, Xiao; Wang, Qianyou; Wang, Shan; Ma, Li; Zhou, Junwen; Wang, Bo

    2016-08-17

    Metal-organic frameworks (MOFs), by virtue of their remarkable uptake capability, selectivity, and ease of regeneration, hold great promise for carbon capture from fossil fuel combustion. However, their stability toward moisture together with the competitive adsorption of water against CO2 drastically dampens their capacity and selectivity under real humid flue gas conditions. In this work, an effective strategy was developed to tackle the above obstacles by partitioning the channels of MOFs into confined, hydrophobic compartments by in situ polymerization of aromatic acetylenes. Specifically, polynaphthylene was formed via a radical reaction inside the channels of MOF-5 and served as partitions without altering the underlying structure of the framework. Compared with pristine MOF-5, the resultant material (PN@MOF-5) exhibits a doubled CO2 capacity (78 vs 38 cm(3)/g at 273 K and 1 bar), 23 times higher CO2/N2 selectivity (212 vs 9), and significantly improved moisture stability. The dynamic CO2 adsorption capacity can be largely maintained (>90%) under humid conditions during cycles. This strategy can be applied to other MOF materials and may shed light on the design of new MOF-polymer materials with tunable pore sizes and environments to promote their practical applications.

  8. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Finzi, Adrien [Boston Univ., MA (United States)

    2016-01-28

    This project combines automated in situ observations of the isotopologues of CO2 with root observations, novel experimental manipulations of belowground processes, and isotope-enabled ecosystem modeling to investigate mechanisms of below- vs. aboveground carbon sequestration at the Harvard Forest Environmental Measurements Site (EMS). The proposed objectives, which have now been largely accomplished, include: (A) Partitioning of net ecosystem CO2 exchange (NEE) into photosynthesis and respiration using long-term continuous observations of the isotopic composition of NEE and analysis of their dynamics; (B) Investigation of the influence of vegetation phenology on the timing and magnitude of carbon allocated belowground using measurements of root growth and indices of belowground autotrophic vs. heterotrophic respiration (via trenched plots and isotope measurements); (C) Testing whether plant allocation of carbon belowground stimulates the microbial decomposition of soil organic matter, using in situ rhizosphere simulation experiments wherein realistic quantities of artificial isotopically-labeled exudates are released into the soil; and (D) Synthesis and interpretation of the above data using the Ecosystem Demography Model 2 (ED2).

  9. Partitioning of catchment water budget and its implications for ecosystem carbon exchange

    Science.gov (United States)

    Lee, D.; Kim, J.; Lee, K.-S.; Kim, S.

    2010-06-01

    Spatially averaged annual carbon budget is one of the key information needed to understand ecosystem response and feedback to climate change. Water availability is a primary constraint of carbon uptake in many ecosystems and therefore the estimation of ecosystem water use may serve as an alternative to quantify Gross Primary Productivity (GPP). To examine this concept, we estimated a long-term steady state water budget for the Han River basin (~26 000 km2) in Korea and examined its application for catchment scale carbon exchange. For this, the catchment scale evapotranspiration (ET) was derived from the long term precipitation (P) and discharge (Q) data. Then, using stable isotope data of P and Q along with other hydrometeorological information, ET was partitioned into evaporation from soil and water surfaces (ES), evaporation from intercepted rainfall (EI, and transpiration (T). ES was identified as a minor component of ET in the study areas regardless of the catchment scales. The annual T, estimated from ET after accounting for EI and ES for the Han River basin from 1966 to 2007, was 22~31% of annual P and the proportion decreased with increasing P. Assuming that T further constrains the catchment scale GPP in terms of water use efficiency (WUE), we examined the possibility of using T as a relative measure for the strength and temporal changes of carbon uptake capacity. The proposed relationship would provide a simple and practical way to assess the spatial distribution of ecosystem GPP, provided the WUE estimates in terms of GPP/T at ecosystem scale could be obtained. For carbon and water tracking toward a sustainable Asia, ascertaining such a spatiotemporally representative WUE and their variability is a requisite facing the flux measurement and modeling communities.

  10. Significance of black carbon in the sediment-water partitioning of organochlorine pesticides (OCPs) in the Indus River, Pakistan.

    Science.gov (United States)

    Ali, Usman; Bajwa, Anam; Chaudhry, Muhammad Jamshed Iqbal; Mahmood, Adeel; Syed, Jabir Hussain; Li, Jun; Zhang, Gan; Jones, Kevin C; Malik, Riffat Naseem

    2016-04-01

    This study was conducted with the aim of assessing the levels and black carbon mediated sediment-water partitioning of organochlorine pesticides (OCPs) from the Indus River. ∑OCPs ranged between 52-285 ng L(-1) and 5.6-29.2 ng g(-1) in water and sediment samples respectively. However, the ranges of sedimentary fraction of total organic carbon (f(TOC)) and black carbon (f(BC)) were 0.82-2.26% and 0.04-0.5% respectively. Spatially, OCPs concentrations were higher at upstream sites as compared to downstream sites. Source diagnostic ratios indicated the technical usage of HCH (α-HCH/γ-HCH>4) and significant presence of DDT metabolites with fresh inputs into the Indus River as indicated by the ratios of (DDE+DDD)/∑DDTs (0.27-0.96). The partitioning of OCPs between the sediments and water can be explained by two carbon Freundlich adsorption model which included both organic carbon and black carbon pools as partitioning media. PMID:26761782

  11. Defaunation affects carbon storage in tropical forests

    OpenAIRE

    Bello, Carolina; Galetti, Mauro; Pizo, Marco A.; Magnago, Luiz Fernando S.; Rocha, Mariana F; Lima, Renato A. F.; Peres, Carlos A.; Ovaskainen, Otso; Jordano, Pedro

    2015-01-01

    Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation, fire, and climate change have significant effects on tropical carbon stocks; however, an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, however many of these frugivores are ...

  12. Partitioning water and carbon fluxes in a Mediterranean oak woodland using stable oxygen isotopes

    Science.gov (United States)

    Dubbert, Maren; Piayda, Arndt; Cuntz, Matthias; Correia, Alexandra; Silva, Filipe Costa e.; Pereira, Joao; Werner, Christiane

    2014-05-01

    evaporation (Dubbert et al. 2013). Moreover, we found continuously strong deviations from isotopic steady-state in plant transpiration combined with large isoforcing on the atmosphere. This implies that assuming plant transpiration to be in the steady-state can have a huge impact at least for studies that distinguish relatively short time intervals (hours, e.g. partitioning studies). Finally. partitioning ecosystem ET and NEE into its three sources revealed a strong contribution of soil evaporation (E) and herbaceous transpiration (T) to ecosystem ET during spring and fall. In contrast, soil respiration (R) and herbaceous net carbon gain contributed to a lesser amount to ecosystem NEE during spring and fall, leading to consistently smaller water use efficiencies (WUE) of the herbaceous understory compared to the cork-oaks. Craig H, Gordon, LI. 1965. Deuterium and oxygen-18 variations in the ocean and the marine atmosphere. Paper presented at the Stable Isotopes in Oceanographic Studies and Paleotemperatures, Spoleto, Italy. Dubbert M, Cuntz M, Piayda A, Maguas C, Werner C, 2013: Partitioning evapotranspiration - Testing the Craig and Gordon model with field measurements of oxygen isotope ratios of evaporative fluxes. J Hydrol.

  13. Desorption, partitioning, and dechlorination characteristics of PCBs in sediments in interaction with reactive activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyeok, E-mail: hchoi@uta.edu [Department of Civil Engineering, The University of Texas at Arlington, 416 Yates Street, Arlington, TX 76019-0308 (United States); Environmental and Earth Sciences Program, The University of Texas at Arlington, 500 Yates Street, Arlington, TX 76019-0049 (United States); Lawal, Wasiu [Environmental and Earth Sciences Program, The University of Texas at Arlington, 500 Yates Street, Arlington, TX 76019-0049 (United States); Al-Abed, Souhail R. [National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268 (United States)

    2015-04-28

    Highlights: • Problematic aged real PCBs-contaminated sediment (WHS) was examined. • Performance of reactive activated carbon (RAC) impregnated with Pd–ZVI was tested. • Fate and transport of PCBs bound to WHS in the presence of RAC was fully traced. • Direct mixing configuration was compared with compartment configuration. • Results reflected real world complexities associated with slow desorption of PCBs. - Abstract: Sediment (WHS) in Waukegan Harbor, Illinois, heavily contaminated and aged with polychlorinated biphenyls (PCBs), was treated with reactive activated carbon (RAC) impregnated with palladized iron nanoparticles. Lab test proceeded in a direct mixing configuration of RAC and WHS. A compartment configuration, where RAC was physically separated from WHS, was also designed to trace the sequential transport and fate of PCBs, including desorption, adsorption, dechlorination, and re-partitioning. PCBs, once desorbed from WHS, were immediately sequestrated to RAC and subject to dechlorination. Direct mixing of WHS with RAC was one-order of magnitude more effective for dechlorination than compartment configuration. Compared to their desorption-followed by-adsorption route, direct physical contact of RAC with PCBs bound to WHS exhibited negligible contribution to the availability of PCBs for dechlorination reaction. Addition of RAC even in compartment configuration facilitated PCBs desorption from WHS. However, slow desorption of PCBs limited overall performance, resulting in a five-order of magnitude lower dechlorination yield when compared with treatment of purely aqueous PCBs. The low dechlorination yield reflected real world complexities in treating 3.19% organic carbon-containing WHS aged with PCBs for 40 years. These observations were further supported when compared with results on clean Cesar Creek sediment spiked with 2-chlorinated biphenyls.

  14. Defaunation affects carbon storage in tropical forests.

    Science.gov (United States)

    Bello, Carolina; Galetti, Mauro; Pizo, Marco A; Magnago, Luiz Fernando S; Rocha, Mariana F; Lima, Renato A F; Peres, Carlos A; Ovaskainen, Otso; Jordano, Pedro

    2015-12-01

    Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation, fire, and climate change have significant effects on tropical carbon stocks; however, an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, however many of these frugivores are threatened by hunting, illegal trade, and habitat loss. We used a large data set on tree species composition and abundance, seed, fruit, and carbon-related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores in 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion of large-seeded trees are extirpated. Although intergovernmental policies to reduce carbon emissions and reforestation programs have been mostly focused on deforestation, our results demonstrate that defaunation, and the loss of key ecological interactions, also poses a serious risk for the maintenance of tropical forest carbon storage.

  15. Defaunation affects carbon storage in tropical forests.

    Science.gov (United States)

    Bello, Carolina; Galetti, Mauro; Pizo, Marco A; Magnago, Luiz Fernando S; Rocha, Mariana F; Lima, Renato A F; Peres, Carlos A; Ovaskainen, Otso; Jordano, Pedro

    2015-12-01

    Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation, fire, and climate change have significant effects on tropical carbon stocks; however, an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, however many of these frugivores are threatened by hunting, illegal trade, and habitat loss. We used a large data set on tree species composition and abundance, seed, fruit, and carbon-related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores in 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion of large-seeded trees are extirpated. Although intergovernmental policies to reduce carbon emissions and reforestation programs have been mostly focused on deforestation, our results demonstrate that defaunation, and the loss of key ecological interactions, also poses a serious risk for the maintenance of tropical forest carbon storage. PMID:26824067

  16. Combined effect of carbon dioxide and sulfur on vapor-liquid partitioning of metals in hydrothermal systems

    Science.gov (United States)

    Kokh, Maria A.; Lopez, Mathieu; Gisquet, Pascal; Lanzanova, Aurélie; Candaudap, Frédéric; Besson, Philippe; Pokrovski, Gleb S.

    2016-08-01

    Although CO2 is a ubiquitous volatile in geological fluids typically ranging from a few to more than 50 wt%, its effect on metal vapor-liquid fractionation during fluid boiling and immiscibility phenomena in the Earth's crust remains virtually unknown. Here we conducted first experiments to quantify the influence of CO2 on the partition of different metals in model water + salt + sulfur + CO2 systems at 350 °C and CO2 pressures up to 100 bar, which are typical conditions of formation of many hydrothermal ore deposits. In addition, we performed in situ Raman spectroscopy measurements on these two-phase systems, to determine sulfur and carbon speciation in the liquid and vapor phases. Results show that, in S-free systems and across a CO2 concentration range of 0-50 wt% in the vapor phase, the absolute vapor-liquid partitioning coefficients of metals (Kvap/liq = Cvap/Cliq, where C is the mass concentration of the metal in the corresponding vapor and liquid phase) are in the range 10-6-10-5 for Mo; 10-4-10-3 for Na, K, Cu, Fe, Zn, Au; 10-3-10-2 for Si; and 10-4-10-1 for Pt. With increasing CO2 from 0 to 50 wt%, Kvap/liq values decrease for Fe, Cu and Si by less than one order of magnitude, remain constant within errors (±0.2 log unit) for Na, K and Zn, and increase by 0.5 and 2 orders of magnitude, respectively for Au and Pt. The negative effect of CO2 on the partitioning of some metals is due to weakening of hydration of chloride complexes of some metals (Cu, Fe) in the vapor phase and/or salting-in effects in the liquid phase (Si), whereas both phenomena are negligible for complexes of other metals (Na, K, Zn, Mo). The only exception is Pt (and in a lesser extent Au), which partitions significantly more to the vapor of S-free systems in the presence of CO2, likely due to formation of volatile carbonyl (CO) complexes. In the S-bearing system, with H2S content of 0.1-1.0 wt% in the vapor, Kvap/liq values of Cu, Fe, Mo, and Au are in the range 0.01-0.1, those of Pt 0

  17. Partitioning of catchment water budget and its implications for ecosystem carbon exchange

    Directory of Open Access Journals (Sweden)

    D. Lee

    2010-06-01

    Full Text Available Spatially averaged annual carbon budget is one of the key information needed to understand ecosystem response and feedback to climate change. Water availability is a primary constraint of carbon uptake in many ecosystems and therefore the estimation of ecosystem water use may serve as an alternative to quantify Gross Primary Productivity (GPP. To examine this concept, we estimated a long-term steady state water budget for the Han River basin (~26 000 km2 in Korea and examined its application for catchment scale carbon exchange. For this, the catchment scale evapotranspiration (ET was derived from the long term precipitation (P and discharge (Q data. Then, using stable isotope data of P and Q along with other hydrometeorological information, ET was partitioned into evaporation from soil and water surfaces (ES, evaporation from intercepted rainfall (EI, and transpiration (T. ES was identified as a minor component of ET in the study areas regardless of the catchment scales. The annual T, estimated from ET after accounting for EI and ES for the Han River basin from 1966 to 2007, was 22~31% of annual P and the proportion decreased with increasing P. Assuming that T further constrains the catchment scale GPP in terms of water use efficiency (WUE, we examined the possibility of using T as a relative measure for the strength and temporal changes of carbon uptake capacity. The proposed relationship would provide a simple and practical way to assess the spatial distribution of ecosystem GPP, provided the WUE estimates in terms of GPP/T at ecosystem scale could be obtained. For carbon and water tracking toward a sustainable Asia, ascertaining such a spatiotemporally representative WUE and their variability is a

  18. Work hardening behaviors of a low carbon Nb-microalloyed Si–Mn quenching–partitioning steel with different cooling styles after partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Ding, Hua, E-mail: hding2013@163.com [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Wang, Chao [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Zhao, Jingwei [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Ding, Ting [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China)

    2013-11-15

    In this paper, the strain hardening behaviors of a low carbon Nb-microalloyed Si–Mn quenching–partitioning (Q–P) steel were investigated. The microstructures were analyzed by the scanning electron microscope (SEM) and transmission electron microscope (TEM). Mechanical tests were used to evaluate the room temperature tensile properties of the steel. The work hardening behaviors of the tested specimens were analyzed using the Hollomon approach. The results showed that a two-stage work hardening behavior was observed during deformation processes. In the first stage, for the quenched samples, martensite deforms plastically and the hardening exponent decreased. For the air-cooled samples, however, the carbide-free ferrite deforms preferentially, and then, the carbide-free ferrite and martensite co-deform. In the second stage, due to the effect of transformation induced plasticity of retained austenite, the hardening exponent decreased slowly and plateaus were observed in the plots of n{sub i}–ε{sub t} until fracture. Variations of the work hardening behaviors were related to the martensite and the volume fraction of retained austenite in Q–P steels and the microstructural evolution during partitioning and following cooling process.

  19. Carbon Monoxide Affecting Planetary Atmospheric Chemistry

    Science.gov (United States)

    He, Chao; Horst, Sarah

    2016-10-01

    Atmospheric hazes are present in a range of solar system and extrasolar planetary atmospheres, and organic hazes, such as that in Titan's atmosphere, could be a source of prebiotic molecules.1 However, the chemistry occurring in planetary atmospheres and the resulting chemical structures are still not clear. Numerous experimental simulations2 have been carried out in the laboratory to understand the chemistry in N2/CH4 atmospheres, but very few simulations4 have included CO in their initial gas mixtures, which is an important component in many N2/CH4 atmospheres including Titan, Triton, and Pluto.3 Here we have conducted a series of atmosphere simulation experiments using AC glow discharge (cold plasma) as energy source to irradiate reactions in gas mixtures of CO, CH4, and N2 with a range of CO mixing ratios (from 0, 0.05%, 0.2%, 0.5%, 1%, 2.5%, to 5%) at low temperature (~100 K). Gas phase products are monitored during the reaction by quadrupole mass spectrometer (MS), and solid phase products are analyzed by solution-state nuclear magnetic resonance spectroscopy (NMR). MS results show that with the increase of CO in the initial gases, the production of nitrogenous organic molecules increases while the production of hydrogen molecules decreases in the gas phase. NMR measurements of the solid phase products show that with the increase of CO, hydrogen atoms bonded to nitrogen or oxygen in unsaturated structures increase while those bonded to saturated carbon decrease, which means more unsaturated species and less saturated species formed with the addition of CO. MS and NMR results demonstrate that the inclusion of CO affects the compositions of both gas and solid phase products, indicating that CO has an important impact on the chemistry occurring in our experiments and probably in planetary atmospheres.1. Hörst, S. M., et al. 2012, AsBio, 12, 8092. Cable, M. L., et al. 2012, Chem. Rev., 112, 18823. Lutz, B. L., et al. 1983, Sci, 220, 1374; Greaves, J. S., et al

  20. The atmospheric signal of terrestrial carbon isotopic discrimination and its implication for partitioning carbon fluxes

    International Nuclear Information System (INIS)

    The 13C/12C ratio in atmospheric carbon dioxide has been measured in samples taken in the NOAA/CMDL network since 1991. By examining the relationship between weekly anomalies in 13C and CO2 at continental sites in the network, we infer temporal and spatial values for the isotopic signature of terrestrial CO2 fluxes. We can convert these isotopic signatures to values of discrimination if we assume the atmospheric starting point for photosynthesis. The average discrimination in the Northern Hemisphere between 30 and 50 deg N is calculated to be 16.6 ± 0.2 per mil. In contrast to some earlier modeling studies, we find no strong latitudinal gradient in discrimination. However, we do observe that discrimination in Eurasia is larger than in North America, which is consistent with two modeling studies. We also observe a possible trend in the North American average of discrimination toward less discrimination. There is no apparent trend in the Eurasian average or at any individual sites. However, there is interannual variability on the order of 2 per mil at several sites and regions. Finally, we calculate the northern temperate terrestrial CO2 flux replacing our previous discrimination values of about 18 per mil with the average value of 16.6 calculated in this study. We find this enhances the terrestrial sink by about 0.4 GtC/yr

  1. Comparative transcriptome and metabolite analysis of oil palm and date palm mesocarp that differ dramatically in carbon partitioning

    OpenAIRE

    Bourgis, Fabienne; Kilaru, Aruna; Cao, Xia; Ngando-Ebongue, Georges-Frank; Drira, Noureddine; Ohlrogge, John B.; Arondel, Vincent

    2011-01-01

    Oil palm can accumulate up to 90% oil in its mesocarp, the highest level observed in the plant kingdom. In contrast, the closely related date palm accumulates almost exclusively sugars. To gain insight into the mechanisms that lead to such an extreme difference in carbon partitioning, the transcriptome and metabolite content of oil palm and date palm were compared during mesocarp development. Compared with date palm, the high oil content in oil palm was associated with much higher transcript ...

  2. Interactive effects of inorganic phosphate nutrition and carbon dioxide enrichment on assimilate partitioning in barley roots

    Energy Technology Data Exchange (ETDEWEB)

    Sicher, R.C. [Crops Systems and Global Change Lab., USDA, Agricultural Res. Service, beltsville, MD (United States)

    2005-02-01

    The combined effects of inorganic phosphate (Pi) insufficiency and CO{sub 2} enrichment on metabolite levels and carbon partitioning were studied using roots of 9-, 13- and 17-day-old barley seedlings (Hordeum vulgare L. cv. Brant). Plants were grown from seed in controlled environment chambers providing 36 {+-} 1 Pa (ambient) or 100 {+-} 2 Pa (elevated) CO{sub 2} and either 1.0 mM (Pi sufficient) or 0.05 mM (Pi insufficient) Pi. When values were combined for both Pi treatments, plants grown under enhanced CO{sub 2} showed increased root dry matter, adenylates (ATP + ADP), glutamine and non- structural carbohydrates other than starch. In contrast with shoots, enhanced CO{sub 2} partially reversed the inhibition of root dry matter formation imposed by Pi insufficiency. The Pi-insufficient treatment also increased sucrose, glucose and fructose levels in barley roots. The Pi and CO{sub 2} treatments were additive, so that the highest soluble carbohydrate levels were observed in roots of Pi-insufficient plants from the elevated CO{sub 2} treatment. Pi limitation decreased dry matter formation, acid-extractable Pi, nitrate, hexose-phosphates, glutamate, glutamine and acid invertase activity of barley roots in plants grown in both ambient and elevated CO{sub 2}. Adenylate levels in roots were unaffected by the moderate Pi insufficiency described here. Thus, the reduced hexose-phosphate levels of Pi-insufficient roots were not likely to be the result of low adenylate concentrations. The above results suggest that the capacity of barley roots to utilize carbohydrates from the shoot is inadequate under both Pi-insufficient and CO{sub 2}-enriched treatments. In addition, the Pi and CO{sub 2} treatments used here alter the nitrogen metabolism of barley roots. These findings further emphasize the importance of avoiding nutrient stress during CO{sub 2} enrichment experiments. (au)

  3. Factors affecting the carbon allowance market in the US

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Seok; Koo, Won W. [Center for Agricultural Policy and Trade Studies, Department of Agribusiness and Applied Economics, North Dakota State University, Dept 7610, P.O. Box 6050, Fargo, ND 58103-6050 (United States)

    2010-04-15

    The US carbon allowance market has different characteristic and price determination process from the EU ETS market, since emitting installations voluntarily participate in emission trading scheme. This paper examines factors affecting the US carbon allowance market. An autoregressive distributed lag model is used to examine the short- and long-run relationships between the US carbon allowance market and its determinant factors. In the long-run, the price of coal is a main factor in the determination of carbon allowance trading. In the short-run, on the other hand, the changes in crude oil and natural gas prices as well as coal price have significant effects on carbon allowance market. (author)

  4. Effects of shading and ethephon on carbon assimilates distribution partitioning in fruit limb of greenhouse-grown 'Dajiubao' peach

    International Nuclear Information System (INIS)

    The distribution of carbon assimilates and the relative sink strength were studied by 14C labeling in one-year-old fruiting limbs of greenhouse-grown 'Dajiubao' peach (Prunus persica L. Batsch), under 60% shading and 600 mg/L Ethephon treatment. After 10d shading treatment prior to pulsing of 14CO2 percent of assimilates translocation into fruit decreased significantly from fed shoot during fruit-ripening stage, but this partitioning patterns was not observed during stone-hardening stage, although less carbon allocated to seed within fruit components (mesocarp, endocarp and seed). The relative sink strength of each organ nearly followed the same variation trend as carbon assimilates distribution under shading treatment. Application of Ethephon to the surface of fruits under shading conditions promoted more carbon into fruits during fruit-ripening stage, with increasing their relative skink strength. (authors)

  5. Analysing the Relevance of Experience Partitions to the Prediction of Players’ Self-Reports of Affect

    DEFF Research Database (Denmark)

    Martínez, Héctor Pérez; Yannakakis, Georgios N.

    2011-01-01

    A common practice in modeling affect from physiological signals consists of reducing the signals to a set of statistical features that feed predictors of self-reported emotions. This paper analyses the impact of various time-windows, used for the extraction of physiological features, to the accur......A common practice in modeling affect from physiological signals consists of reducing the signals to a set of statistical features that feed predictors of self-reported emotions. This paper analyses the impact of various time-windows, used for the extraction of physiological features...

  6. Climate change affects carbon allocation to the soil in shrublands

    NARCIS (Netherlands)

    Gorissen, A.; Tietema, A.; Joosten, N.N.; Estiarte, M.; Peñuelas, J.; Sowerby, A.; Emmett, B.; Beier, J.C.

    2004-01-01

    Climate change may affect ecosystem functioning through increased temperatures or changes in precipitation patterns. Temperature and water availability are important drivers for ecosystem processes such as photosynthesis, carbon translocation, and organic matter decomposition. These climate changes

  7. How Glassy States Affect Brown Carbon Production?

    Science.gov (United States)

    Liu, P.; Li, Y.; Wang, Y.; Bateman, A. P.; Zhang, Y.; Gong, Z.; Gilles, M. K.; Martin, S. T.

    2015-12-01

    Secondary organic material (SOM) can become light-absorbing (i.e. brown carbon) via multiphase reactions with nitrogen-containing species such as ammonia and amines. The physical states of SOM, however, potentially slow the diffusion of reactant molecules in organic matrix under conditions that semisolids or solids prevail, thus inhibiting the browning reaction pathways. In this study, the physical states and the in-particle diffusivity were investigated by measuring the evaporation kinetics of both water and organics from aromatic-derived SOMs using a quartz-crystal-microbalance (QCM). The results indicate that the SOMs derived from aromatic precursors toluene and m-xylene became solid (glassy) and the in particle diffusion was significantly impeded for sufficiently low relative humidity ( urban atmospheres that ultimately influence the climate and tropospheric photochemistry.

  8. Microstructural evolution and consequent strengthening through niobium-microalloying in a low carbon quenched and partitioned steel

    International Nuclear Information System (INIS)

    In the present study the determining role of niobium (Nb) on significant enhancement in mechanical properties in a low-carbon quenched and partitioned steel is elucidated. The study indicates that solute drag and precipitation pinning effect of Nb suppressed the recrystallization during hot deformation, leading to grain size refinement of hot-rolled steels. The cold-rolled and final microstructure after Q–P treatment was also refined because of refined hot rolled microstructure. Additionally, the degree of refinement was enhanced with increase in Nb-content. The tensile strength of the experimental steels was increased with increase in Nb-content from 1130 MPa in steel without Nb to 1210 MPa in steel with 0.048 wt% Nb. However, the total elongation first increased to 18% followed by a small decrease to 15%. The decrease in ductility is attributed to the consumption of carbon by precipitating NbC, which decreased the enrichment of austenite by carbon during partitioning, with consequent decrease in the stability of austenite. The decrease in the stability of retained austenite ultimately reduced the volume fraction of retained austenite and led to reduction in elongation

  9. Microstructural evolution and consequent strengthening through niobium-microalloying in a low carbon quenched and partitioned steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Ding, Hua, E-mail: hding2013@163.com [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Misra, R.D.K. [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical and Materials Engineering, University of Texas at El Paso, 500W, University Avenue, El Paso, TX 79968 (United States); Wang, Chao [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China)

    2015-08-12

    In the present study the determining role of niobium (Nb) on significant enhancement in mechanical properties in a low-carbon quenched and partitioned steel is elucidated. The study indicates that solute drag and precipitation pinning effect of Nb suppressed the recrystallization during hot deformation, leading to grain size refinement of hot-rolled steels. The cold-rolled and final microstructure after Q–P treatment was also refined because of refined hot rolled microstructure. Additionally, the degree of refinement was enhanced with increase in Nb-content. The tensile strength of the experimental steels was increased with increase in Nb-content from 1130 MPa in steel without Nb to 1210 MPa in steel with 0.048 wt% Nb. However, the total elongation first increased to 18% followed by a small decrease to 15%. The decrease in ductility is attributed to the consumption of carbon by precipitating NbC, which decreased the enrichment of austenite by carbon during partitioning, with consequent decrease in the stability of austenite. The decrease in the stability of retained austenite ultimately reduced the volume fraction of retained austenite and led to reduction in elongation.

  10. Influential role of black carbon in the soil-air partitioning of polychlorinated biphenyls (PCBs) in the Indus River Basin, Pakistan.

    Science.gov (United States)

    Ali, Usman; Syed, Jabir Hussain; Mahmood, Adeel; Li, Jun; Zhang, Gan; Jones, Kevin C; Malik, Riffat Naseem

    2015-09-01

    Levels of polychlorinated biphenyls (PCBs) were assessed in surface soils and passive air samples from the Indus River Basin, and the influential role of black carbon (BC) in the soil-air partitioning process was examined. ∑26-PCBs ranged between 0.002-3.03 pg m(-3) and 0.26-1.89 ng g(-1) for passive air and soil samples, respectively. Lower chlorinated (tri- and tetra-) PCBs were abundant in both air (83.9%) and soil (92.1%) samples. Soil-air partitioning of PCBs was investigated through octanol-air partition coefficients (KOA) and black carbon-air partition coefficients (KBC-A). The results of the paired-t test revealed that both models showed statistically significant agreement between measured and predicted model values for the PCB congeners. Ratios of fBCKBC-AδOCT/fOMKOA>5 explicitly suggested the influential role of black carbon in the retention and soil-air partitioning of PCBs. Lower chlorinated PCBs were strongly adsorbed and retained by black carbon during soil-air partitioning because of their dominance at the sampling sites and planarity effect. PMID:25933089

  11. Climate change affects carbon allocation to the soil in shrublands

    DEFF Research Database (Denmark)

    Gorissen, A.; Tietema, A.; Joosten, N.N.;

    2004-01-01

    than or equal to 0.10. Drought clearly reduced carbon flow from the roots to the soil compartments. The fraction of the C-14 fixed by the plants and allocated into the soluble carbon fraction in the soil and to soil microbial biomass in Denmark and the UK decreased by more than 60%. The effects...... of warming were not significant, but, as with the drought treatment, a negative effect on carbon allocation to soil microbial biomass was found. The changes in carbon allocation to soil microbial biomass at the northern sites in this study indicate that soil microbial biomass is a sensitive, early indicator...... may affect the supply of carbon and energy to the soil microbial population and subsequently alter decomposition and mineralization, important ecosystem processes in carbon and nutrient cycling. In this study, carried out within the cross-European research project CLIMOOR, the effect of climate change...

  12. From dimers to collective dipoles: Structure and dynamics of methanol/ethanol partition by narrow carbon nanotubes

    Science.gov (United States)

    Garate, Jose A.; Perez-Acle, Tomas

    2016-02-01

    Alcohol partitioning by narrow single-walled carbon nanotubes (SWCNTs) holds the promise for the development of novel nanodevices for diverse applications. Consequently, in this work, the partition of small alcohols by narrow tubes was kinetically and structurally quantified via molecular dynamics simulations. Alcohol partitioning is a fast process in the order of 10 ns for diluted solutions but the axial-diffusivity within SWCNT is greatly diminished being two to three orders of magnitude lower with respect to bulk conditions. Structurally, alcohols form a single-file conformation under confinement and more interestingly, they exhibit a pore-width dependent transition from dipole dimers to a single collective dipole, for both methanol and ethanol. Energetic analyses demonstrate that this transition is the result of a detailed balance between dispersion and electrostatics interactions, with the latter being more pronounced for collective dipoles. This transition fully modifies the reorientational dynamics of the loaded particles, generating stable collective dipoles that could find usage in signal-amplification devices. Overall, the results herein have shown distinct physico-chemical features of confined alcohols and are a further step towards the understanding and development of novel nanofluidics within SWCNTs.

  13. Estimation of the soil-water partition coefficient normalized to organic carbon for ionizable organic chemicals

    DEFF Research Database (Denmark)

    Franco, Antonio; Trapp, Stefan

    2008-01-01

    The sorption of organic electrolytes to soil was investigated. A dataset consisting of 164 electrolytes, composed of 93 acids, 65 bases, and six amphoters, was collected from literature and databases. The partition coefficient log KOW of the neutral molecule and the dissociation constant pKa were...

  14. Partitioning of CH(4 and CO(2 production originating from rice straw, soil and root organic carbon in rice microcosms.

    Directory of Open Access Journals (Sweden)

    Quan Yuan

    Full Text Available Flooded rice fields are an important source of the greenhouse gas CH(4. Possible carbon sources for CH(4 and CO(2 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 δ(13C of RS. This procedure allowed to determine the carbon flux from each of the three sources (SOM, ROC, RS by determining the δ(13C of CH(4 and CO(2 in the different incubations and from the δ(13C of RS. Partitioning of carbon flux indicated that the contribution of ROC to CH(4 production was 41% at tillering stage, increased with rice growth and was about 60% from the booting stage onwards. The contribution of ROC to CO(2 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 CH(4 production and 11-31% for CO(2 production; while the contribution of SOM was calculated to be 23-35% for CH(4 production and 13-26% for CO(2 production. The results indicate that ROC was the major source of CH(4 though RS application greatly enhanced production and emission of CH(4 in rice field soil. Our results also suggest that data of CH(4 dissolved in rice field could be used as a proxy for the produced CH(4 after tillering stage.

  15. Assessing the combined influence of TOC and black carbon in soil–air partitioning of PBDEs and DPs from the Indus River Basin, Pakistan

    International Nuclear Information System (INIS)

    Levels of polybrominated diphenyl ethers (PBDEs) and dechlorane plus (DPs) were investigated in the Indus River Basin from Pakistan. Concentrations of ∑PBDEs and ∑DPs were ranged between 0.05 and 2.38 and 0.002–0.53 ng g−1 in the surface soils while 1.43–22.1 and 0.19–7.59 pg m−3 in the passive air samples, respectively. Black carbon (fBC) and total organic carbon (fTOC) fractions were also measured and ranged between 0.73 and 1.75 and 0.04–0.2%, respectively. The statistical analysis revealed strong influence of fBC than fTOC on the distribution of PBDEs and DPs in the Indus River Basin soils. BDE's congener profile suggested the input of penta–bromodiphenylether (DE-71) commercial formulation in the study area. Soil–air partitioning of PBDEs were investigated by employing octanol-air partition coefficients (KOA) and black carbon-air partition coefficients (KBC−A). The results of both models suggested the combined influence of total organic carbon (absorption) and black carbon (adsorption) in the studied area. - Highlights: • Model based calculations of black carbon-air partition coefficients for PBDEs. • Soil and air levels of PBDEs and DPs reported first time for ecologically important sites of the Indus River Basin, Pakistan. • Both, fBC and fTOC showed combined influence on soil–air partitioning of PBDEs in the Indus River Basin, Pakistan. - BC and TOC showed combined influence on soil–air partitioning of POPs i-e., PBDEs in the Indus River Basin, Pakistan

  16. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States); Davidson, Eric [Univ. of Arizona, Tucson, AZ (United States); Finzi, Adrien [Univ. of Arizona, Tucson, AZ (United States); Wehr, Richard [Univ. of Arizona, Tucson, AZ (United States); Moorcroft, Paul [Univ. of Arizona, Tucson, AZ (United States)

    2016-01-28

    1. Objectives This project combines automated in situ observations of the isotopologues of CO2 with root observations, novel experimental manipulations of belowground processes, and isotope-enabled ecosystem modeling to investigate mechanisms of below- vs. aboveground carbon sequestration at the Harvard Forest Environmental Measurements Site (EMS). The proposed objectives, which have now been largely accomplished, include: A. Partitioning of net ecosystem CO2 exchange (NEE) into photosynthesis and respiration using long-term continuous observations of the isotopic composition of NEE, and analysis of their dynamics ; B. Investigation of the influence of vegetation phenology on the timing and magnitude of carbon allocated belowground using measurements of root growth and indices of belowground autotrophic vs. heterotrophic respiration (via trenched plots and isotope measurements); C. Testing whether plant allocation of carbon belowground stimulates the microbial decomposition of soil organic matter, using in situ rhizosphere simulation experiments wherein realistic quantities of artificial isotopically-labeled exudates are released into the soil; and D. Synthesis and interpretation of the above data using the Ecosystem Demography Model 2 (ED2). 2. Highlights Accomplishments: • Our isotopic eddy flux record has completed its 5th full year and has been used to independently estimate ecosystem-scale respiration and photosynthesis. • Soil surface chamber isotopic flux measurements were carried out during three growing seasons, in conjunction with a trenching manipulation. Key findings to date (listed by objective): A. Partitioning of Net Ecosystem Exchange: 1. Ecosystem respiration is lower during the day than at night—the first robust evidence of the inhibition of leaf respiration by light (the “Kok effect”) at the ecosystem scale. 2. Because it neglects the Kok effect, the standard NEE partitioning approach overestimates ecosystem

  17. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, Eric A. [Woods Hole Research Center, Falmouth, MA (United States); Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States); Savage, Kathleen [Woods Hole Research Center, Falmouth, MA (United States); Finzi, Adrien [Boston Univ., MA (United States); Moorcroft, Paul [Harvard Univ., Cambridge, MA (United States); Wehr, Richard [Univ. of Arizona, Tucson, AZ (United States)

    2016-02-18

    1. Project Summary and Objectives This project combines automated in situ observations of the isotopologues of CO2 with root observations, novel experimental manipulations of belowground processes, and isotope-enabled ecosystem modeling to investigate mechanisms of below- vs. aboveground carbon sequestration at the Harvard Forest Environmental Measurements Site (EMS). The proposed objectives, which have now been largely accomplished, include: A. Partitioning of net ecosystem CO2 exchange (NEE) into photosynthesis and respiration using long-term continuous observations of the isotopic composition of NEE, and analysis of their dynamics ; B. Investigation of the influence of vegetation phenology on the timing and magnitude of carbon allocated belowground using measurements of root growth and indices of belowground autotrophic vs. heterotrophic respiration (via trenched plots and isotope measurements); C. Testing whether plant allocation of carbon belowground stimulates the microbial decomposition of soil organic matter, using in situ rhizosphere simulation experiments wherein realistic quantities of artificial isotopically-labeled exudates are released into the soil; and D. Synthesis and interpretation of the above data using the Ecosystem Demography Model 2 (ED2).

  18. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States). Dept. of Ecology and Evolutionary Biology; Davidson, Eric [Woods Hole Research Center, Falmouth, MA (United States); Finzi, Adrien [Boston Univ., MA (United States). Dept. of Biology; Wehr, Richard [Univ. of Arizona, Tucson, AZ (United States); Moorcroft, Paul [Harvard Univ., Cambridge, MA (United States). Dept. of Organismic and Evolutionary Biology

    2016-01-28

    This project combines automated in situ observations of the isotopologues of CO2 with root observations, novel experimental manipulations of below ground processes, and isotope-enabled ecosystem modeling to investigate mechanisms of below- vs. above ground carbon sequestration at the Harvard Forest Environmental Measurements Site (EMS). The proposed objectives, which have now been largely accomplished, include: (A) Partitioning of net ecosystem CO2 exchange (NEE) into photosynthesis and respiration using long-term continuous observations of the isotopic composition of NEE, and analysis of their dynamics; (B) Investigation of the influence of vegetation phenology on the timing and magnitude of carbon allocated below ground using measurements of root growth and indices of below ground autotrophic vs. heterotrophic respiration (via trenched plots andisotope measurements); (C) Testing whether plant allocation of carbon below ground stimulates the microbial decomposition of soil organic matter, using in situ rhizosphere simulation experiments wherein realistic quantities of artificial isotopically-labeled exudates are released into the soil; and (D) Synthesis and interpretation of the above data using the Ecosystem Demography Model 2 (ED2).

  19. Potassium nutrition and water availability affect phloem transport of photosynthetic carbon in eucalypt trees

    Science.gov (United States)

    Epron, Daniel; Cabral, Osvaldo; Laclau, Jean-Paul; Dannoura, Masako; Packer, Ana Paula; Plain, Caroline; Battie-Laclau, Patricia; Moreira, Marcelo; Trivelin, Paulo; Bouillet, Jean-Pierre; Gérant, Dominique; Nouvellon, Yann

    2015-04-01

    Potassium fertilisation strongly affects growth and carbon partitioning of eucalypt on tropical soil that are strongly weathered. In addition, potassium fertilization could be of great interest in mitigating the adverse consequences of drought in planted forests, as foliar K concentrations influence osmotic adjustment, stomatal regulation and phloem loading. Phloem is the main pathway for transferring photosynthate from source leaves to sink organs, thus controlling growth partitioning among the different tree compartments. But little is known about the effect of potassium nutrition on phloem transport of photosynthetic carbon and on the interaction between K nutrition and water availability. In situ 13C pulse labelling was conducted on tropical eucalypt trees (Eucalyptus grandis L.) grown in a trial plantation with plots in which 37% of throughfall were excluded (about 500 mm/yr) using home-made transparent gutters (-W) or not (+W) and plots that received 0.45 mol K m-2 applied as KCl three months after planting (+K) or not (-K). Three trees were labelled in each of the four treatments (+K+W, +K-W, -K+W and -K-W). Trees were labelled for one hour by injecting pure 13CO2 in a 27 m3 whole crown chamber. We estimated the velocity of carbon transfer in the trunk by comparing time lags between the uptake of 13CO2 and its recovery in trunk CO2 efflux recorded by off axis integrated cavity output spectroscopy (Los Gatos Research) in two chambers per tree, one just under the crown and one at the base of the trunk. We analyzed the dynamics of the label recovered in the foliage and in the phloem sap by analysing carbon isotope composition of bulk leaf organic matter and phloem extracts using an isotope ratio mass spectrometer. The velocity of carbon transfer in the trunk and the initial rate 13C disappearance from the foliage were much higher in +K trees than in -K trees with no significant effect of rainfall. The volumetric flow of phloem, roughly estimated by multiplying

  20. Coupling carbon allocation with leaf and root phenology predicts tree-grass partitioning along a savanna rainfall gradient

    Science.gov (United States)

    Haverd, V.; Smith, B.; Raupach, M.; Briggs, P.; Nieradzik, L.; Beringer, J.; Hutley, L.; Trudinger, C. M.; Cleverly, J.

    2016-02-01

    The relative complexity of the mechanisms underlying savanna ecosystem dynamics, in comparison to other biomes such as temperate and tropical forests, challenges the representation of such dynamics in ecosystem and Earth system models. A realistic representation of processes governing carbon allocation and phenology for the two defining elements of savanna vegetation (namely trees and grasses) may be a key to understanding variations in tree-grass partitioning in time and space across the savanna biome worldwide. Here we present a new approach for modelling coupled phenology and carbon allocation, applied to competing tree and grass plant functional types. The approach accounts for a temporal shift between assimilation and growth, mediated by a labile carbohydrate store. This is combined with a method to maximize long-term net primary production (NPP) by optimally partitioning plant growth between fine roots and (leaves + stem). The computational efficiency of the analytic method used here allows it to be uniquely and readily applied at regional scale, as required, for example, within the framework of a global biogeochemical model.We demonstrate the approach by encoding it in a new simple carbon-water cycle model that we call HAVANA (Hydrology and Vegetation-dynamics Algorithm for Northern Australia), coupled to the existing POP (Population Orders Physiology) model for tree demography and disturbance-mediated heterogeneity. HAVANA-POP is calibrated using monthly remotely sensed fraction of absorbed photosynthetically active radiation (fPAR) and eddy-covariance-based estimates of carbon and water fluxes at five tower sites along the North Australian Tropical Transect (NATT), which is characterized by large gradients in rainfall and wildfire disturbance. The calibrated model replicates observed gradients of fPAR, tree leaf area index, basal area, and foliage projective cover along the NATT. The model behaviour emerges from complex feedbacks between the plant

  1. Linking water and carbon fluxes in a Mediterranean oak woodland using a combined flux and ?18O partitioning approach

    Science.gov (United States)

    Dubbert, M.; Piayda, A.; Costa e Silva, F.; Correia, A.; Pereira, J. S.; Cuntz, M.; Werner, C.

    2013-12-01

    Water is one of the key factors driving ecosystem productivity, especially in water-limited ecosystems, where global climate change is expected to intensify drought and alter precipitation patterns. One such ecosystem is the ';Montado', where two vegetation layers respond differently to drought: oak trees avoid drought due to their access to deeper soil layers and ground water while herbaceous plants, surviving the summer in the form of seeds. We aimed at 1) quantifying the impact of the understory herbaceous vegetation on ecosystem carbon and water fluxes throughout the year, 2) determining the driving environmental factors for evapotranspiration (ET) and net ecosystem exchange (NEE) and 3) disentangling how ET components of the ecosystem relate to carbon dioxide exchange. We present one year data set comparing modeled and measured stable oxygen isotope signatures (δ18O) of soil evaporation, confirming that the Craig and Gordon equation leads to good agreement with measured δ18O of evaporation (Dubbert et al. 2013). Partitioning ecosystem ET and NEE into its three sources revealed a strong contribution of soil evaporation (E) and herbaceous transpiration (T) to ecosystem ET during spring and fall. In contrast, soil respiration (R) and herbaceous net carbon gain contributed to a lesser amount to ecosystem NEE during spring and fall, leading to consistently smaller water use efficiencies (WUE) of the herbaceous understory compared to the cork-oaks. Here, we demonstrate that the ability to assess ET, NEE and WUE independent of soil evaporation dynamics enables the understanding of the mechanisms of the coupling between water and carbon fluxes and their responses to drought. Dubbert, M., Cuntz, M., Piayda, A., Maguas, C., Werner, C., 2013: Partitioning evapotranspiration - Testing the Craig and Gordon model with field measurements of oxygen isotope ratios of evaporative fluxes. J Hydrol. a) Oxygen isotope signatures of soil evaporation on bare soil plots calculated

  2. Possible role of growth regulators in adaptation to heat stress affecting partitioning of photosynthates in tomato plants

    Directory of Open Access Journals (Sweden)

    Zofia Starck

    2014-02-01

    Full Text Available Tomato plants of two cultivars: Roma - sensitive and Robin - tolerant to heat stress were grown in greenhouse up to the flowering stage and then under controlled environmen­tal conditions. The partitioning of recently fixed 14CO2 by mature tomato leaves was examined as a posteffect of 24-h heat stress (38/25°C day/night with the interaction of growth regulators (GR sprayed on the flowers with solution of β-naphthoxyacetic (NOA and gibberellic (GA3 acid (denoted as NG, or Zeatin + NOA + GA3 (denoted as ZNG. In both cuitivars GR strongly stimulated fruit growth and transport of 14C-photosynthates to the clusters at the expense of vegetative organs. Heat stress decreased export of 14C-phoiosynthates from the blades in plants not treated with GR, but even more in cv. Roma. In Roma plants not treated with GR (with very small fruitlets and fruits the heat stress retarded 14C-transport just in the petioles, diminishing the 14C-supply to the fruits. Reduction of the current photosynthate supplied to the fruits seems to be causally connected with inhibition of the specific activity of acid invertase in that organ. Growth regulators reduced the negative effect of high temperature - they alleviated depression of 14C-export from the blades and increased invertase activity. 14C-photosynthate transport to the fruits, presumably owing to their higher sink strength, was less affected by heat stress. In Robin plants (which had bigger fruits during the experiment high temperature depressed 14C-fruit supply only in the NG-series, in contrast to enhacement of 14C-Movement to that sink in the control and ZNG-series. In spite of these facts, after heat stress, the specific activity of acid invertase decreased in all the experimental series, but much less in the GR-treated series. Therefore, in the Robin cv. there was no relation between invertase activity and 14C-mobilization by fruits, as was observed in Roma plants. The possible explanation of the different

  3. CO{sub 2} enrichment and carbon partitioning to phenolics: do plant responses accord better with the protein competition or the growth differentiation balance models?

    Energy Technology Data Exchange (ETDEWEB)

    Mattson, W.J. [Forestry Sciences Lab., Rhinelander, WI (United States); Julkunen-Tiitto, R. [Univ. of Joensuu, Biology Dept., Joensuu (Finland); Herms, D.A. [Ohio State Univ., Dept. of Entmology, Wooster, OH (United States)

    2005-11-01

    Rising levels of atmospheric CO{sub 2} can alter plant growth and partitioning to secondary metabolites. The protein competition model (PCM) and the extended growth/differentiation balance model (GDB{sub e}) are similar but alternative models that address ontogenetic and environmental effects on whole-plant carbon partitioning to the phenylpropanoid biosynthetic pathway, making many divergentpredictins. To test the validity of the models, we compare plant responses to one key prediction: if CO{sub 2} enrichment simultaneously stimulates both photosynthesis and growth, then PCM predicts that partitioning to phenolic compounds will decline, whereas GDB{sub e} generally predicts the opposite. Elevated CO{sub 2} (at 548 ppm) increased the biomass growth (ca 23%) as well as the net photosynthesis (ca 13%) of 1-year-old potted paper birch, Betula papyrifera Marsch., in a free air carbon dioxide enrichment study (FACE) in northern Wisconsin. Concomitantly, elevated CO{sub 2} increased carbon partitioning to all measured classes of phenolics (Folin-Denis phenolics, HPLC low molecular weight phenolics (i.e. cinnamic acid derivatives, flavonol flycosides, and flavon-3-ols), condensed tannins, and acid-detergent lignin) in leaves. In stem tissues, tannins and lignin increased, but F-D phenolics did not. In root tissues, F-D phenolics, and tannins increased, but lignin did not. The data suggest that CO{sub 2} enrichment stimulated pathway-wide increase in carbon partitioning to phenylpropanoids. High CO{sub 2} plants had 11.8% more F-D phenolics, 19.3% more tannin, and 10% more lignin than ambient plants after adjusting for plant mass via analysis of covariance. In general, the results unequivocally support the predictions of the GDB{sub e} model. By way of contrast, results from many parallel studies on FACE trembling aspen, Populus tremuloides Michx., suggest that although 2 enrichment has consistently stimulated both photosynthesis and growth, it apparently did not

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

    OpenAIRE

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

    2009-01-01

    Overexpression of the Gossypium hirsutum sucrose synthase (SuSy) gene under the control of 2 promoters was examined in hybrid poplar (Populus alba × 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...

  5. Patterns of Carbon Partitioning in Leaves of Crassulacean Acid Metabolism Species during Deacidification.

    Science.gov (United States)

    Christopher, J. T.; Holtum, JAM.

    1996-09-01

    Carbohydrates stored during deacidification in the light were examined in 11 Crassulacean acid metabolism (CAM) species from widely separated taxa grown under uniform conditions. The hypothesis that NAD(P) malic enzyme CAM species store chloroplastic starch and glucans, and phosphoenolpyruvate carboxykinase species store extrachloroplastic sugars or polymers was disproved. Of the six malic enzyme species examined, Kalanchoe tubiflora, Kalanchoe pinnata, Kalanchoe daigremontiana, and Vanilla planifolia stored mainly starch. Sansevieria hahnii stored sucrose and Agave guadalajarana did not store starch, glucose, fructose, or sucrose. Of the five phosphoenolpyruvate carboxykinase species investigated, Ananus comosus stored extrachloroplastic carbohydrate, but Stapelia gigantea, Hoya carnosa, and Portea petropolitana stored starch, whereas Aloe vera stored both starch and glucose. Within families, the major decarboxylase was common for all species examined, whereas storage carbohydrate could differ both between and within genera. In the Bromeliaceae, A. comosus stored mainly fructose, but P. petropolitana stored starch. In the genus Aloe, A. vera stored starch and glucose, but A. arborescens is known to store a galactomannan polymer. We postulate that the observed variation in carbohydrate partitioning between CAM species is the result of two principal components: (a) constraints imposed by the CAM syndrome itself, and (b) diversity in biochemistry resulting from different evolutionary histories. PMID:12226397

  6. The QQS orphan gene regulates carbon and nitrogen partitioning across species via NF-YC interactions

    Science.gov (United States)

    The allocation of carbon and nitrogen resources to the synthesis of plant proteins, carbohydrates, and lipids is complex and under the control of many genes; much remains to be understood about this process. QQS (Qua Quine Starch, At3g30720), an orphan gene unique to Arabidopsis thaliana, regulates...

  7. On the choice of the driving temperature for eddy-covariance carbon dioxide flux partitioning

    NARCIS (Netherlands)

    Lasslop, G.; Migliavacca, M.; Bohrer, G.; Reichstein, M.; Bahn, M.; Ibrom, A.; Jacobs, C.M.J.; Kolari, P.; Papale, D.; Vesala, T.; Wohlfart, G.; Cescatti, A.

    2012-01-01

    Networks that merge and harmonise eddy-covariance measurements from many different parts of the world have become an important observational resource for ecosystem science. Empirical algorithms have been developed which combine direct observations of the net ecosystem exchange of carbon dioxide with

  8. Geological and hydrogeological features affecting migration, multi-phase partitioning and degradation of chlorinated hydrocarbons through unconsolidated porous media.

    OpenAIRE

    Filippini, Maria

    2015-01-01

    Chlorinated solvents are the most ubiquitous organic contaminants found in groundwater since the last five decades. They generally reach groundwater as Dense Non-Aqueous Phase Liquid (DNAPL). This phase can migrate through aquifers, and also through aquitards, in ways that aqueous contaminants cannot. The complex phase partitioning to which chlorinated solvent DNAPLs can undergo (i.e. to the dissolved, vapor or sorbed phase), as well as their transformations (e.g. degradation), depend on the...

  9. Assessing the combined influence of TOC and black carbon in soil-air partitioning of PBDEs and DPs from the Indus River Basin, Pakistan.

    Science.gov (United States)

    Ali, Usman; Mahmood, Adeel; Syed, Jabir Hussain; Li, Jun; Zhang, Gan; Katsoyiannis, Athanasios; Jones, Kevin C; Malik, Riffat Naseem

    2015-06-01

    Levels of polybrominated diphenyl ethers (PBDEs) and dechlorane plus (DPs) were investigated in the Indus River Basin from Pakistan. Concentrations of ∑PBDEs and ∑DPs were ranged between 0.05 and 2.38 and 0.002-0.53 ng g(-1) in the surface soils while 1.43-22.1 and 0.19-7.59 pg m(-3) in the passive air samples, respectively. Black carbon (fBC) and total organic carbon (fTOC) fractions were also measured and ranged between 0.73 and 1.75 and 0.04-0.2%, respectively. The statistical analysis revealed strong influence of fBC than fTOC on the distribution of PBDEs and DPs in the Indus River Basin soils. BDE's congener profile suggested the input of penta-bromodiphenylether (DE-71) commercial formulation in the study area. Soil-air partitioning of PBDEs were investigated by employing octanol-air partition coefficients (KOA) and black carbon-air partition coefficients (KBC-A). The results of both models suggested the combined influence of total organic carbon (absorption) and black carbon (adsorption) in the studied area. PMID:25795070

  10. Partitioning sources of recharge in environments with groundwater recirculation using carbon-14 and CFC-12

    Science.gov (United States)

    Bourke, Sarah A.; Cook, Peter G.; Dogramaci, Shawan; Kipfer, Rolf

    2015-06-01

    Groundwater recirculation occurs when groundwater is pumped from an aquifer onto the land surface, and a portion of that water subsequently infiltrates back to the aquifer. In environments where groundwater is recirculated, differentiation between various sources of recharge (e.g. natural rainfall recharge vs. recirculated water) can be difficult. Groundwater age indicators, in particular transient trace gases, are likely to be more sensitive tracers of recharge than stable isotopes or chloride in this setting. This is because, unlike stable isotopes or chloride, they undergo a process of equilibration with the atmosphere, and historical atmospheric concentrations are known. In this paper, groundwater age indicators (14C and CFC-12) were used as tracers of recharge by surplus mine water that is discharged to streams. Ternary mixing ratios were calculated based on 14C and CFC-12 concentrations measured along three transects of piezometers and monitoring wells perpendicular to the creeks, and from dewatering wells. Uncertainty in calculated mixing ratios was estimated using a Monte Carlo approach. Ternary mixing ratios in dewatering wells suggest that recharge by mine water accounted for between 10% and 87% of water currently abstracted by dewatering wells. The calculated mixing ratios suggest that recharge by mine water extends to a distance of more than 550 m from the creeks. These results are supported by seepage flux estimates based on the water and chloride balance along the creeks, which suggest that 85-90% of mine water discharged to the creeks recharges the aquifer and recharge by mine water extends between 110 and 730 m from the creeks. Mixing calculations based on gaseous groundwater age indicators could also be used to partition recharge associated with agricultural irrigation or artificial wetland supplementation.

  11. Martensitic transformation and stress partitioning in a high-carbon steel

    DEFF Research Database (Denmark)

    Villa, Matteo; Grumsen, Flemming Bjerg; Pantleon, Karen;

    2012-01-01

    Martensitic transformation in a high-carbon steel was investigated with (synchrotron) X-ray diffraction at sub-zero Celsius temperature. In situ angular X-ray diffraction was applied to: (i) quantitatively determine the fractions of retained austenite and martensite; and (ii) measure the evolution...... of the lattice strain in retained austenite. Ex situ (synchrotron) energy-dispersive X-ray diffraction was performed to assess the effects of the martensitic transformation on the development of stresses in austenite....

  12. Ecosystem carbon storage and partitioning in a tropical seasonal forest in Southwestern China

    DEFF Research Database (Denmark)

    Lü, Xiao-Tao; Yin, Jiang-Xia; Jepsen, Martin Rudbeck;

    2010-01-01

    in Malaysia. The variation of C storage in the tree layer among different plots was mainly due to different densities of large trees (DBH > 70 cm). The contributions of the shrub layer, herb layer, woody lianas, and fine litter each accounted for 1-2 t C ha-1 to the total carbon stock. The mineral soil C...... for conservation planning....

  13. Stand-level patterns of carbon fluxes and partitioning in a Eucalyptus grandis plantation across a gradient of productivity, in Sao Paulo State, Brazil.

    Science.gov (United States)

    Campoe, Otávio C; Stape, José Luiz; Laclau, Jean-Paul; Marsden, Claire; Nouvellon, Yann

    2012-06-01

    Wood production represents a large but variable fraction of gross primary production (GPP) in highly productive Eucalyptus plantations. Assessing patterns of carbon (C) partitioning (C flux as a fraction of GPP) between above- and belowground components is essential to understand mechanisms driving the C budget of these plantations. Better knowledge of fluxes and partitioning to woody and non-woody tissues in response to site characteristics and resource availability could provide opportunities to increase forest productivity. Our study aimed at investigating how C allocation varied within one apparently homogeneous 90 ha stand of Eucalyptus grandis (W. Hill ex Maiden) in Southeastern Brazil. We assessed annual above-ground net primary production (ANPP: stem, leaf, and branch production) and total belowground C flux (TBCF: the sum of root production and respiration and mycorrhizal production and respiration), GPP (computed as the sum of ANPP, TBCF and estimated aboveground respiration) on 12 plots representing the gradient of productivity found within the stand. The spatial heterogeneity of topography and associated soil attributes across the stand likely explained this fertility gradient. Component fluxes of GPP and C partitioning were found to vary among plots. Stem NPP ranged from 554 g C m(-2) year(-1) on the plot with lowest GPP to 923 g C m(-2) year(-1) on the plot with highest GPP. Total belowground carbon flux ranged from 497 to 1235 g C m(-2) year(-1) and showed no relationship with ANPP or GPP. Carbon partitioning to stem NPP increased from 0.19 to 0.23, showing a positive trend of increase with GPP (R(2) = 0.29, P = 0.07). Variations in stem wood production across the gradient of productivity observed at our experimental site were a result of the variability in C partitioning to different forest system components. PMID:22543478

  14. A genomics investigation of partitioning into and among flavonoid-derived condensed tannins for carbon sequestration in Populus

    Energy Technology Data Exchange (ETDEWEB)

    Harding, Scott, A; Tsai, Chung-jui; Lindroth, Richard, L

    2013-03-24

    The project set out to use comparative (genotype and treatment) and transgenic approaches to investigate the determinants of condensed tannin (CT) accrual and chemical variability in Populus. CT type and amount are thought to effect the decomposition of plant detritus in the soil, and thereby the sequestering of carbon in the soil. The stated objectives were: 1. Genome-wide transcriptome profiling (microarrays) to analyze structural gene, transcription factor and metabolite control of CT partitioning; 2. Transcriptomic (microarray) and chemical analysis of ontogenetic effects on CT and PG partitioning; and 3. Transgenic manipulation of flavonoid biosynthetic pathway genes to modify the control of CT composition. Objective 1: A number of approaches for perturbing CT content and chemistry were tested in Objective 1, and those included nitrogen deficit, leaf wounding, drought, and salicylic acid spraying. Drought had little effect on CTs in the genotypes we used. Plants exhibited unpredictability in their response to salicylic acid spraying, leading us to abandon its use. Reduced plant nitrogen status and leaf wounding caused reproducible and magnitudinally striking increases in leaf CT content. Microarray submissions to NCBI from those experiments are the following: GSE ID 14515: Comparative transcriptomics analysis of Populus leaves under nitrogen limitation: clone 1979. Public on Jan 04, 2010; Contributor(s) Harding SA, Tsai C GSE ID 14893: Comparative transcriptomics analysis of Populus leaves under nitrogen limitation: clone 3200. Public on Feb 19, 2009; Contributor(s) Harding SA, Tsai C GSE ID 16783 Wound-induced gene expression changes in Populus: 1 week; clone RM5. Status Public on Dec 01, 2009; Contributor(s) Harding SA, Tsai C GSE ID 16785 Wound-induced gene expression changes in Populus: 90 hours; clone RM5 Status Public on Dec 01, 2009; Contributor(s) Harding SA, Tsai C Although CT amount changed in response to treatments, CT composition was essentially

  15. Differential neural processing of unpleasant haptic sensations in somatic and affective partitions of the insula in non-suicidal self-injury (NSSI).

    Science.gov (United States)

    Bonenberger, Martina; Plener, Paul L; Groschwitz, Rebecca C; Grön, Georg; Abler, Birgit

    2015-12-30

    Altered perception and neural processing of pain have been observed during non-suicidal self-injury (NSSI). Evidence suggests that this phenomenon could be associated with the affective rather than the somatosensory dimension of pain. Sub-partitions of the insula have been suggested to process these different aspects differentially. In the present study, activation within the posterior, middle, and anterior partitions of the insula upon unpleasant electric stimulation was compared between subjects with a history of NSSI and healthy controls. Using functional magnetic resonance imaging (fMRI), we investigated a sample of 30 subjects, 14 of them with a lifetime history of NSSI. Unpleasant electric stimulation to the dorsum of the non-dominant hand was performed at four levels of increasing intensity. Significantly increasing posterior insula activation, which is likely to reflect the somatosensory aspects of unpleasant haptic sensations, was found upon parametrically increasing electric stimulation in both groups. By contrast, activation of the anterior insula, rather related to the more affective aspects of distressing stimuli, was significantly modulated only in the control group, but not in subjects with NSSI. These findings may support present hypotheses of altered processing of the more affective aspects of unpleasant or distressing experiences in NSSI, as a putatively relevant factor for understanding the etiology of this behavior.

  16. Comparative transcriptome and metabolite analysis of oil palm and date palm mesocarp that differ dramatically in carbon partitioning.

    Science.gov (United States)

    Bourgis, Fabienne; Kilaru, Aruna; Cao, Xia; Ngando-Ebongue, Georges-Frank; Drira, Noureddine; Ohlrogge, John B; Arondel, Vincent

    2011-07-26

    Oil palm can accumulate up to 90% oil in its mesocarp, the highest level observed in the plant kingdom. In contrast, the closely related date palm accumulates almost exclusively sugars. To gain insight into the mechanisms that lead to such an extreme difference in carbon partitioning, the transcriptome and metabolite content of oil palm and date palm were compared during mesocarp development. Compared with date palm, the high oil content in oil palm was associated with much higher transcript levels for all fatty acid synthesis enzymes, specific plastid transporters, and key enzymes of plastidial carbon metabolism, including phosphofructokinase, pyruvate kinase, and pyruvate dehydrogenase. Transcripts representing an ortholog of the WRI1 transcription factor were 57-fold higher in oil palm relative to date palm and displayed a temporal pattern similar to its target genes. Unexpectedly, despite more than a 100-fold difference in flux to lipids, most enzymes of triacylglycerol assembly were expressed at similar levels in oil palm and date palm. Similarly, transcript levels for all but one cytosolic enzyme of glycolysis were comparable in both species. Together, these data point to synthesis of fatty acids and supply of pyruvate in the plastid, rather than acyl assembly into triacylglycerol, as a major control over the storage of oil in the mesocarp of oil palm. In addition to greatly increasing molecular resources devoted to oil palm and date palm, the combination of temporal and comparative studies illustrates how deep sequencing can provide insights into gene expression patterns of two species that lack genome sequence information. PMID:21709233

  17. Coding Partitions

    Directory of Open Access Journals (Sweden)

    Fabio Burderi

    2007-05-01

    Full Text Available Motivated by the study of decipherability conditions for codes weaker than Unique Decipherability (UD, we introduce the notion of coding partition. Such a notion generalizes that of UD code and, for codes that are not UD, allows to recover the ``unique decipherability" at the level of the classes of the partition. By tacking into account the natural order between the partitions, we define the characteristic partition of a code X as the finest coding partition of X. This leads to introduce the canonical decomposition of a code in at most one unambiguouscomponent and other (if any totally ambiguouscomponents. In the case the code is finite, we give an algorithm for computing its canonical partition. This, in particular, allows to decide whether a given partition of a finite code X is a coding partition. This last problem is then approached in the case the code is a rational set. We prove its decidability under the hypothesis that the partition contains a finite number of classes and each class is a rational set. Moreover we conjecture that the canonical partition satisfies such a hypothesis. Finally we consider also some relationships between coding partitions and varieties of codes.

  18. Carbon, Nitrogen and Phosphorus Accumulation and Partitioning, and C:N:P Stoichiometry in Late-Season Rice under Different Water and Nitrogen Managements

    OpenAIRE

    Yushi Ye; Xinqiang Liang; Yingxu Chen; Liang Li; Yuanjing Ji; Chunyan Zhu

    2014-01-01

    Water and nitrogen availability plays an important role in the biogeochemical cycles of essential elements, such as carbon (C), nitrogen (N) and phosphorus (P), in agricultural ecosystems. In this study, we investigated the seasonal changes of C, N and P concentrations, accumulation, partitioning, and C:N:P stoichiometric ratios in different plant tissues (root, stem-leaf, and panicle) of late-season rice under two irrigation regimes (continuous flooding, CF; alternate wetting and drying, AWD...

  19. Carbon partitioning as validation methods for crop yields and CO2 sequestration monitoring in Asia using a photosynthetic-sterility model

    Science.gov (United States)

    Kaneko, Daijiro; Yang, Peng; Kumakura, Toshiro

    2010-10-01

    Sustainability of world crop production and food security has become uncertain. The authors have developed an environmental research system called Remote Sensing Environmental Monitor (RSEM) for treating carbon sequestration by vegetation, grain production, desertification of Eurasian grassland, and CDM afforestation/ reforestation to a background of climate change and economic growth in rising Asian nations. The RSEM system involves vegetation photosynthesis and crop yield models for grains, including land-use classification, stomatal evaluation by surface energy fluxes, and daily monitoring for early warning. This paper presents a validation method for RSEM based on carbon partitioning in plants, focusing in particular on the effects of area sizes used in crop production statistics on carbon fixation and on sterility-based corrections to accumulated carbon sequestration values simulated using the RSEM photosynthesis model. The carbonhydrate in grains has the same chemical formula as cellulose in grain plants. The method proposed by partitioning the fixed carbon in harvested grains was used to investigate estimates of the amounts of carbon fixed, using the satellite-based RSEM model.

  20. Partitioning between primary and secondary metabolism of carbon allocated to roots in four maize genotypes under water deficit and its effects on productivity

    Institute of Scientific and Technical Information of China (English)

    Alyne; Oliveira; Lavinsky; Paulo; César; Magalh?es; Roniel; Geraldo; ávila; Mariana; Melo; Diniz; Thiago; Corrêa; de; Souza

    2015-01-01

    Plants may respond to drought by altering biomass allocation to shoots and roots or by changing the metabolic activities in these organs. To determine how drought changes the partitioning of carbon allocated to growth and secondary metabolism in maize roots and how it affects photosynthesis(A) and productivity in maize, we evaluated leaf gas exchange, yield componentes, root morphology, and primary and secondary metabolites including total soluble sugars(TSS), starch(S), phenolics(PHE), and lignin(LIG). Data were collected from pot-grown plants of four maize genotypes: BRS 1010 and 2B710(sensitive genotypes) and DKB390 and BRS1055(tolerant genotypes) under two soil water tensions: field capacity(FC,-18 kP a) and water deficit(WD,-138 kP a). WD was applied at the pre-flowering stage for 12 days and then the water supply was restored and maintained at optimum levels until the end of the cycle. For genotype BRS 1055 under FC, the greatest A did not result in greater grain biomass(DGB) because the accumulated photoassimilates had already filled the cells, and thus the excessive TSS synthesized in leaves was allocated to roots in large amounts. However, the sharp decrease in A caused by WD imposition in this genotype did not affect the influx pressure of leaf TSS, which was due largely to conversion of primary metabolites to PHE compounds to increase the length of fine roots. In leaves of DKB390 under WD, both S and TSS were reduced, whereas PHE were increased to prevent excessive water loss and xylem cavitation. Under WD, both BRS1010 and2B710 genotypes displayed reduced allocation of biomass to shoots and roots and LIG content in leaves, as well as lower A and DGB values. In BRS1010 this response was coupled to S decrease in leaves and TSS increase in roots, whereas in 2B710 there was a concomitant S increase in roots.

  1. Partitioning between primary and secondary metabolism of carbon allocated to roots in four maize genotypes under water deficit and its effects on productivity

    Institute of Scientific and Technical Information of China (English)

    Alyne Oliveira Lavinsky; Paulo César Magalhães; Roniel Geraldo Ávila; Mariana Melo Diniz; Thiago Corrêa de Souza

    2015-01-01

    Plants may respond to drought by altering biomass allocation to shoots and roots or by changing the metabolic activities in these organs. To determine how drought changes the partitioning of carbon allocated to growth and secondary metabolism in maize roots and how it affects photosynthesis (A) and productivity in maize, we evaluated leaf gas exchange, yield componentes, root morphology, and primary and secondary metabolites including total soluble sugars (TSS), starch (S), phenolics (PHE), and lignin (LIG). Data were collected from pot-grown plants of four maize genotypes:BRS 1010 and 2B710 (sensitive genotypes) and DKB390 and BRS1055 (tolerant genotypes) under two soil water tensions:field capacity (FC,−18 kPa) and water deficit (WD,−138 kPa). WD was applied at the pre-flowering stage for 12 days and then the water supply was restored and maintained at optimum levels until the end of the cycle. For genotype BRS 1055 under FC, the greatest A did not result in greater grain biomass (DGB) because the accumulated photoassimilates had already filled the cells, and thus the excessive TSS synthesized in leaves was allocated to roots in large amounts. However, the sharp decrease in A caused by WD imposition in this genotype did not affect the influx pressure of leaf TSS, which was due largely to conversion of primary metabolites to PHE compounds to increase the length of fine roots. In leaves of DKB390 under WD, both S and TSS were reduced, whereas PHE were increased to prevent excessive water loss and xylem cavitation. Under WD, both BRS1010 and 2B710 genotypes displayed reduced allocation of biomass to shoots and roots and LIG content in leaves, as well as lower A and DGB values. In BRS1010 this response was coupled to S decrease in leaves and TSS increase in roots, whereas in 2B710 there was a concomitant S increase in roots.

  2. Partitioning between primary and secondary metabolism of carbon allocated to roots in four maize genotypes under water deficit and its effects on productivity

    Directory of Open Access Journals (Sweden)

    Alyne Oliveira Lavinsky

    2015-10-01

    Full Text Available Plants may respond to drought by altering biomass allocation to shoots and roots or by changing the metabolic activities in these organs. To determine how drought changes the partitioning of carbon allocated to growth and secondary metabolism in maize roots and how it affects photosynthesis (A and productivity in maize, we evaluated leaf gas exchange, yield componentes, root morphology, and primary and secondary metabolites including total soluble sugars (TSS, starch (S, phenolics (PHE, and lignin (LIG. Data were collected from pot-grown plants of four maize genotypes: BRS 1010 and 2B710 (sensitive genotypes and DKB390 and BRS1055 (tolerant genotypes under two soil water tensions: field capacity (FC, − 18 kPa and water deficit (WD, − 138 kPa. WD was applied at the pre-flowering stage for 12 days and then the water supply was restored and maintained at optimum levels until the end of the cycle. For genotype BRS 1055 under FC, the greatest A did not result in greater grain biomass (DGB because the accumulated photoassimilates had already filled the cells, and thus the excessive TSS synthesized in leaves was allocated to roots in large amounts. However, the sharp decrease in A caused by WD imposition in this genotype did not affect the influx pressure of leaf TSS, which was due largely to conversion of primary metabolites to PHE compounds to increase the length of fine roots. In leaves of DKB390 under WD, both S and TSS were reduced, whereas PHE were increased to prevent excessive water loss and xylem cavitation. Under WD, both BRS1010 and 2B710 genotypes displayed reduced allocation of biomass to shoots and roots and LIG content in leaves, as well as lower A and DGB values. In BRS1010 this response was coupled to S decrease in leaves and TSS increase in roots, whereas in 2B710 there was a concomitant S increase in roots.

  3. TOPOISOMERASE 6B is involved in chromatin remodelling associated with control of carbon partitioning into secondary metabolites and cell walls, and epidermal morphogenesis in Arabidopsis.

    Science.gov (United States)

    Mittal, Amandeep; Balasubramanian, Rajagopal; Cao, Jin; Singh, Prabhjeet; Subramanian, Senthil; Hicks, Glenn; Nothnagel, Eugene A; Abidi, Noureddine; Janda, Jaroslav; Galbraith, David W; Rock, Christopher D

    2014-08-01

    Plant growth is continuous and modular, a combination that allows morphogenesis by cell division and elongation and serves to facilitate adaptation to changing environments. The pleiotropic phenotypes of the harlequin (hlq) mutant, isolated on the basis of ectopic expression of the abscisic acid (ABA)- and auxin-inducible proDc3:GUS reporter gene, were previously characterized. Mutants are skotomorphogenic, have deformed and collapsed epidermal cells which accumulate callose and starch, cell walls abundant in pectins and cell wall proteins, and abnormal and reduced root hairs and leaf trichomes. hlq and two additional alleles that vary in their phenotypic severity of starch accumulation in the light and dark have been isolated, and it is shown that they are alleles of bin3/hyp6/rhl3/Topoisomerase6B. Mutants and inhibitors affecting the cell wall phenocopy several of the traits displayed in hlq. A microarray analysis was performed, and coordinated expression of physically adjacent pairs/sets of genes was observed in hlq, suggesting a direct effect on chromatin. Histones, WRKY and IAA/AUX transcription factors, aquaporins, and components of ubiquitin-E3-ligase-mediated proteolysis, and ABA or biotic stress response markers as well as proteins involved in cellular processes affecting carbon partitioning into secondary metabolites were also identified. A comparative analysis was performed of the hlq transcriptome with other previously published TopoVI mutant transcriptomes, namely bin3, bin5, and caa39 mutants, and limited concordance between data sets was found, suggesting indirect or genotype-specific effects. The results shed light on the molecular mechanisms underlying the det/cop/fus-like pleiotropic phenotypes of hlq and support a broader role for TopoVI regulation of chromatin remodelling to mediate development in response to environmental and hormonal signals. PMID:24821950

  4. Congener-specific organic carbon-normalized soil and sediment-water partitioning coefficients for the C1 through C8 perfluoroalkyl carboxylic and sulfonic acids.

    Science.gov (United States)

    Rayne, Sierra; Forest, Kaya

    2009-11-01

    Organic carbon-normalized soil and sediment-water partitioning coefficients (K(oc)) were estimated for all C(1) through C(8) perfluoroalkyl carboxylic (PFCA) and sulfonic (PFSA) acid congeners. The limited experimental K(oc) data set for the straight chain C(7) through C(10) PFCAs and C(8) and C(10) PFSAs was correlated to SPARC and ALOGPS computationally estimated octanol-water partitioning/distribution constants and used to predict K(oc) values for both branched and linear C(1) through C(8) isomers. Branched and linear congeners in this homologue range are generally expected to have K(oc) values > 1, leading to their accumulation in organic matter on sediments and soils, retardation during ground and pore water flow, and the preferential association with dissolved organic matter in aquatic systems. Both increasing perfluoroalkyl chain length and linearity increase K(oc) values with substantial intra- and inter-homologue variation and interhomologue mixing. Variability in K(oc) values among the PFCA and PFSA congeners will likely lead to an enrichment of more linear and longer-chain isomers in organic matter fractions, resulting in aqueous phases fractionated towards shorter-chain branched congeners. The expected magnitude of fractionation will require inclusion in source apportionment models and risk assessments. A comparison of representative established quantitative structure property relationships for estimating K(oc) values from octanol-water partitioning constants suggests that these equilibrium partitioning frameworks may be applicable towards modeling PFCA and PFSA environmental fate processes. PMID:20183495

  5. The Inter-Annual Variability Analysis of Carbon Exchange in Low Artic Fen Uncovers The Climate Sensitivity And The Uncertainties Around Net Ecosystem Exchange Partitioning

    Science.gov (United States)

    Blanco, E. L.; Lund, M.; Williams, M. D.; Christensen, T. R.; Tamstorf, M. P.

    2015-12-01

    An improvement in our process-based understanding of CO2 exchanges in the Arctic, and their climate sensitivity, is critical for examining the role of tundra ecosystems in changing climates. Arctic organic carbon storage has seen increased attention in recent years due to large potential for carbon releases following thaw. Our knowledge about the exact scale and sensitivity for a phase-change of these C stocks are, however, limited. Minor variations in Gross Primary Production (GPP) and Ecosystem Respiration (Reco) driven by changes in the climate can lead to either C sink or C source states, which likely will impact the overall C cycle of the ecosystem. Eddy covariance data is usually used to partition Net Ecosystem Exchange (NEE) into GPP and Reco achieved by flux separation algorithms. However, different partitioning approaches lead to different estimates. as well as undefined uncertainties. The main objectives of this study are to use model-data fusion approaches to (1) determine the inter-annual variability in C source/sink strength for an Arctic fen, and attribute such variations to GPP vs Reco, (2) investigate the climate sensitivity of these processes and (3) explore the uncertainties in NEE partitioning. The intention is to elaborate on the information gathered in an existing catchment area under an extensive cross-disciplinary ecological monitoring program in low Arctic West Greenland, established under the auspices of the Greenland Ecosystem Monitoring (GEM) program. The use of such a thorough long-term (7 years) dataset applied to the exploration in inter-annual variability of carbon exchange, related driving factors and NEE partition uncertainties provides a novel input into our understanding about land-atmosphere CO2 exchange.

  6. Effect of Lipid Partitioning on Predictions of Acute Toxicity of Oil Sands Process Affected Water to Embryos of Fathead Minnow (Pimephales promelas).

    Science.gov (United States)

    Morandi, Garrett D; Zhang, Kun; Wiseman, Steve B; Pereira, Alberto Dos Santos; Martin, Jonathan W; Giesy, John P

    2016-08-16

    Dissolved organic compounds in oil sands process affected water (OSPW) are known to be responsible for most of its toxicity to aquatic organisms, but the complexity of this mixture prevents use of traditional bottom-up approaches for predicting toxicities of mixtures. Therefore, a top-down approach to predict toxicity of the dissolved organic fraction of OSPW was developed and tested. Accurate masses (i.e., m/z) determined by ultrahigh resolution mass spectrometry in negative and positive ionization modes were used to assign empirical chemical formulas to each chemical species in the mixture. For each chemical species, a predictive measure of lipid accumulation was estimated by stir-bar sorptive extraction (SBSE) to poly(dimethyl)siloxane, or by partitioning to solid-supported lipid membranes (SSLM). A narcosis mode of action was assumed and the target-lipid model was used to estimate potencies of mixtures by assuming strict additivity. A model developed using a combination of the SBSE and SSLM lipid partitioning estimates, whereby the accumulation of chemicals to neutral and polar lipids was explicitly considered, was best for predicting empirical values of LC50 in 96-h acute toxicity tests with embryos of fathead minnow (Pimephales promelas). Model predictions were within 4-fold of observed toxicity for 75% of OSPW samples, and within 8.5-fold for all samples tested, which is comparable to the range of interlaboratory variability for in vivo toxicity testing. PMID:27420640

  7. Trace metal partitioning over a tidal cycle in an estuary affected by acid mine drainage (Tinto estuary, SW Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Hierro, A. [Department of Physics, Universitat Autònoma de Barcelona, 08193 Bellaterra (Spain); Department of Applied Physics, Facultad de Ciencias Experimentales, University of Huelva, Campus de El Carmen, Campus de Excelencia Internacional del Mar CEIMAR, 21071 Huelva (Spain); Olías, M., E-mail: manuel.olias@dgyp.uhu.es [Department of Geodynamics and Paleontology, Facultad de Ciencias Experimentales, University of Huelva, Campus de El Carmen, Campus de Excelencia Internacional del Mar CEIMAR, 21071 Huelva (Spain); Cánovas, C.R. [Department of Geodynamics and Paleontology, Facultad de Ciencias Experimentales, University of Huelva, Campus de El Carmen, Campus de Excelencia Internacional del Mar CEIMAR, 21071 Huelva (Spain); Martín, J.E.; Bolivar, J.P. [Department of Applied Physics, Facultad de Ciencias Experimentales, University of Huelva, Campus de El Carmen, Campus de Excelencia Internacional del Mar CEIMAR, 21071 Huelva (Spain)

    2014-11-01

    The Tinto River estuary is highly polluted with the acid lixiviates from old sulphide mines. In this work the behaviour of dissolved and particulate trace metals under strong chemical gradients during a tidal cycle is studied. The pH values range from 4.4 with low tide to 6.9 with high tide. Precipitation of Fe and Al is intense during rising tides and As and Pb are almost exclusively found in the particulate matter (PM). Sorption processes are very important in controlling the mobility (and hence bioavailability) of some metals and particularly affect Cu below pH 6. Above pH ∼ 6 Cu is desorbed, probably by the formation of Cu(I)–chloride complexes. Although less pronounced than Cu, also Zn desorption above pH 6.5 seems to occur. Mn and Co are affected by sorption processes at pH higher than ca. 6. Cd behaves conservatively and Ni is slightly affected by sorption processes. - Highlights: • The Tinto estuary shows strong pH gradients and high trace elements concentrations. • PM has a hysteretic relationship with tides and high contents of Fe, Al, As and Pb. • Co and Mn are controlled by river and sea water mixing and sorption processes. • Sorption processes strongly affect Cu below pH 6, above this value Cu is desorpted. • Cadmium behaves conservatively along the pH range studied (4.4–6.9)

  8. Trace metal partitioning over a tidal cycle in an estuary affected by acid mine drainage (Tinto estuary, SW Spain)

    International Nuclear Information System (INIS)

    The Tinto River estuary is highly polluted with the acid lixiviates from old sulphide mines. In this work the behaviour of dissolved and particulate trace metals under strong chemical gradients during a tidal cycle is studied. The pH values range from 4.4 with low tide to 6.9 with high tide. Precipitation of Fe and Al is intense during rising tides and As and Pb are almost exclusively found in the particulate matter (PM). Sorption processes are very important in controlling the mobility (and hence bioavailability) of some metals and particularly affect Cu below pH 6. Above pH ∼ 6 Cu is desorbed, probably by the formation of Cu(I)–chloride complexes. Although less pronounced than Cu, also Zn desorption above pH 6.5 seems to occur. Mn and Co are affected by sorption processes at pH higher than ca. 6. Cd behaves conservatively and Ni is slightly affected by sorption processes. - Highlights: • The Tinto estuary shows strong pH gradients and high trace elements concentrations. • PM has a hysteretic relationship with tides and high contents of Fe, Al, As and Pb. • Co and Mn are controlled by river and sea water mixing and sorption processes. • Sorption processes strongly affect Cu below pH 6, above this value Cu is desorpted. • Cadmium behaves conservatively along the pH range studied (4.4–6.9)

  9. A genomics investigation of partitioning into and among flavonoid-derived condensed tannins for carbon sequestration in Populus

    Energy Technology Data Exchange (ETDEWEB)

    Harding, Scott, A; Tsai, Chung-jui; Lindroth, Richard, L

    2013-03-24

    The project set out to use comparative (genotype and treatment) and transgenic approaches to investigate the determinants of condensed tannin (CT) accrual and chemical variability in Populus. CT type and amount are thought to effect the decomposition of plant detritus in the soil, and thereby the sequestering of carbon in the soil. The stated objectives were: 1. Genome-wide transcriptome profiling (microarrays) to analyze structural gene, transcription factor and metabolite control of CT partitioning; 2. Transcriptomic (microarray) and chemical analysis of ontogenetic effects on CT and PG partitioning; and 3. Transgenic manipulation of flavonoid biosynthetic pathway genes to modify the control of CT composition. Objective 1: A number of approaches for perturbing CT content and chemistry were tested in Objective 1, and those included nitrogen deficit, leaf wounding, drought, and salicylic acid spraying. Drought had little effect on CTs in the genotypes we used. Plants exhibited unpredictability in their response to salicylic acid spraying, leading us to abandon its use. Reduced plant nitrogen status and leaf wounding caused reproducible and magnitudinally striking increases in leaf CT content. Microarray submissions to NCBI from those experiments are the following: GSE ID 14515: Comparative transcriptomics analysis of Populus leaves under nitrogen limitation: clone 1979. Public on Jan 04, 2010; Contributor(s) Harding SA, Tsai C GSE ID 14893: Comparative transcriptomics analysis of Populus leaves under nitrogen limitation: clone 3200. Public on Feb 19, 2009; Contributor(s) Harding SA, Tsai C GSE ID 16783 Wound-induced gene expression changes in Populus: 1 week; clone RM5. Status Public on Dec 01, 2009; Contributor(s) Harding SA, Tsai C GSE ID 16785 Wound-induced gene expression changes in Populus: 90 hours; clone RM5 Status Public on Dec 01, 2009; Contributor(s) Harding SA, Tsai C Although CT amount changed in response to treatments, CT composition was essentially

  10. A new integration of hot pressing and carbon partition process to produce high strength steel components with better toughness

    OpenAIRE

    Zhang Shi-hong; Song Hong-wu; Zhang Fei-bao; Liu Wei-jie

    2015-01-01

    A novel one step method for hot pressing and quench & partition (Q&P) integration – hot Pressing-dynamic partitioning (HP-DP) process is presented, which can be processed by regular hot pressing equipment and process. The HP-DP formed steel is an upgrade of the existing hot pressed steel especially suitable for making high strength components with superior crashworthiness due to better toughness. Corresponding steel sheet based on conventional 22MnB5 is designed and prepared. After that, the ...

  11. Carbon, nitrogen and phosphorus accumulation and partitioning, and C:N:P stoichiometry in late-season rice under different water and nitrogen managements.

    Directory of Open Access Journals (Sweden)

    Yushi Ye

    Full Text Available Water and nitrogen availability plays an important role in the biogeochemical cycles of essential elements, such as carbon (C, nitrogen (N and phosphorus (P, in agricultural ecosystems. In this study, we investigated the seasonal changes of C, N and P concentrations, accumulation, partitioning, and C:N:P stoichiometric ratios in different plant tissues (root, stem-leaf, and panicle of late-season rice under two irrigation regimes (continuous flooding, CF; alternate wetting and drying, AWD and four N managements (control, N0; conventional urea at 240 kg N ha(-1, UREA; controlled-release bulk blending fertilizer at 240 kg N ha(-1, BBF; polymer-coated urea at 240 kg N ha(-1, PCU. We found that water and N treatments had remarkable effects on the measured parameters in different plant tissues after transplanting, but the water and N interactions had insignificant effects. Tissue C:N, N:P and C:P ratios ranged from 14.6 to 52.1, 3.1 to 7.8, and 76.9 to 254.3 over the rice growing seasons, respectively. The root and stem-leaf C:N:P and panicle C:N ratios showed overall uptrends with a peak at harvest whereas the panicle N:P and C:P ratios decreased from filling to harvest. The AWD treatment did not affect the concentrations and accumulation of tissue C and N, but greatly decreased those of P, resulting in enhanced N:P and C:P ratios. N fertilization significantly increased tissue N concentration, slightly enhanced tissue P concentration, but did not affect tissue C concentration, leading to a significant increase in tissue N:P ratio but a decrease in C:N and C:P ratios. Our results suggested that the growth of rice in the Taihu Lake region was co-limited by N and P. These findings broadened our understanding of the responses of plant C:N:P stoichiometry to simultaneous water and N managements in subtropical high-yielding rice systems.

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

    Science.gov (United States)

    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. PMID:22542133

  13. Stable oxygen isotope and flux partitioning demonstrates understory of an oak savanna contributes up to half of ecosystem carbon and water exchange

    Science.gov (United States)

    Dubbert, Maren; Piayda, Arndt; Cuntz, Matthias; Correia, Alexandra C.; Costa e Silva, Filipe; Pereira, Joao S.; Werner, Christiane

    2014-01-01

    Semi-arid ecosystems contribute about 40% to global net primary production (GPP) even though water is a major factor limiting carbon uptake. Evapotranspiration (ET) accounts for up to 95% of the water loss and in addition, vegetation can also mitigate drought effects by altering soil water distribution. Hence, partitioning of carbon and water fluxes between the soil and vegetation components is crucial to gain mechanistic understanding of vegetation effects on carbon and water cycling. However, the possible impact of herbaceous vegetation in savanna type ecosystems is often overlooked. Therefore, we aimed at quantifying understory vegetation effects on the water balance and productivity of a Mediterranean oak savanna. ET and net ecosystem CO2 exchange (NEE) were partitioned based on flux and stable oxygen isotope measurements and also rain infiltration was estimated. The understory vegetation contributed importantly to total ecosystem ET and GPP with a maximum of 43 and 51%, respectively. It reached water-use efficiencies (WUE; ratio of carbon gain by water loss) similar to cork-oak trees. The understory vegetation inhibited soil evaporation (E) and, although E was large during wet periods, it did not diminish WUE during water-limited times. The understory strongly increased soil water infiltration, specifically following major rain events. At the same time, the understory itself was vulnerable to drought, which led to an earlier senescence of the understory growing under trees as compared to open areas, due to competition for water. Thus, beneficial understory effects are dominant and contribute to the resilience of this ecosystem. At the same time the vulnerability of the understory to drought suggests that future climate change scenarios for the Mediterranean basin threaten understory development. This in turn will very likely diminish beneficial understory effects like infiltration and ground water recharge and therefore ecosystem resilience to drought. PMID

  14. Stable oxygen isotope and flux partitioning demonstrates understory of an oak savanna contributes up to half of ecosystem carbon and water exchange

    Directory of Open Access Journals (Sweden)

    Maren eDubbert

    2014-10-01

    Full Text Available Semi-arid ecosystems contribute about 40% to global net primary production (GPP even though water is a major factor limiting carbon uptake. Evapotranspiration (ET accounts for up to 95% of the water loss and in addition, vegetation can also mitigate drought effects by altering soil water distribution. Hence, partitioning of carbon and water fluxes between the soil and vegetation components is crucial to gain mechanistic understanding of vegetation effects on carbon and water cycling. However, the possible impact of herbaceous vegetation in savanna type ecosystems is often overlooked. Therefore, we aimed at quantifying understory vegetation effects on the water balance and productivity of a Mediterranean oak savanna. ET and net ecosystem CO2 exchange (NEE were partitioned based on flux and stable oxygen isotope measurements and also rain infiltration was estimated.The understory vegetation contributed importantly to total ecosystem ET and GPP with a maximum of 43% and 51%, respectively. It reached water-use efficiencies (WUE; ratio of carbon gain by water loss similar to cork-oak trees. The understory vegetation inhibited soil evaporation (E and, although E was large during wet periods, it did not diminish WUE during water-limited times. The understory strongly increased soil water infiltration, specifically following major rain events. At the same time, the understory itself was vulnerable to drought, which led to an earlier senescence of the understory growing under trees as compared to open areas, due to competition for water. Thus, beneficial understory effects are dominant and contribute to the resilience of this ecosystem. At the same time the vulnerability of the understory to drought suggests that future climate change scenarios for the Mediterranean basin threaten understory development. This in turn will very likely diminish beneficial understory effects like infiltration and ground water recharge and therefore ecosystem resilience to

  15. Stable oxygen isotope and flux partitioning demonstrates understory of an oak savanna contributes up to half of ecosystem carbon and water exchange.

    Science.gov (United States)

    Dubbert, Maren; Piayda, Arndt; Cuntz, Matthias; Correia, Alexandra C; Costa E Silva, Filipe; Pereira, Joao S; Werner, Christiane

    2014-01-01

    Semi-arid ecosystems contribute about 40% to global net primary production (GPP) even though water is a major factor limiting carbon uptake. Evapotranspiration (ET) accounts for up to 95% of the water loss and in addition, vegetation can also mitigate drought effects by altering soil water distribution. Hence, partitioning of carbon and water fluxes between the soil and vegetation components is crucial to gain mechanistic understanding of vegetation effects on carbon and water cycling. However, the possible impact of herbaceous vegetation in savanna type ecosystems is often overlooked. Therefore, we aimed at quantifying understory vegetation effects on the water balance and productivity of a Mediterranean oak savanna. ET and net ecosystem CO2 exchange (NEE) were partitioned based on flux and stable oxygen isotope measurements and also rain infiltration was estimated. The understory vegetation contributed importantly to total ecosystem ET and GPP with a maximum of 43 and 51%, respectively. It reached water-use efficiencies (WUE; ratio of carbon gain by water loss) similar to cork-oak trees. The understory vegetation inhibited soil evaporation (E) and, although E was large during wet periods, it did not diminish WUE during water-limited times. The understory strongly increased soil water infiltration, specifically following major rain events. At the same time, the understory itself was vulnerable to drought, which led to an earlier senescence of the understory growing under trees as compared to open areas, due to competition for water. Thus, beneficial understory effects are dominant and contribute to the resilience of this ecosystem. At the same time the vulnerability of the understory to drought suggests that future climate change scenarios for the Mediterranean basin threaten understory development. This in turn will very likely diminish beneficial understory effects like infiltration and ground water recharge and therefore ecosystem resilience to drought.

  16. Bioconcentration of Dissolved Organic Compounds from Oil Sands Process-Affected Water by Medaka (Oryzias latipes): Importance of Partitioning to Phospholipids.

    Science.gov (United States)

    Zhang, Kun; Wiseman, Steve; Giesy, John P; Martin, Jonathan W

    2016-06-21

    The complex mixture of dissolved organics in oil sands process-affected water (OSPW) is acutely lethal to fish at environmentally relevant concentrations, but few bioconcentration factors (BCFs) have been measured for its many chemical species. Japanese medaka (Oryzias latipes) were exposed to 10% OSPW, and measured BCFs were evaluated against predicted BCFs from octanol-water distribution ratios (DOW) and phospholipid membrane-water distribution ratios (DMW). Two heteroatomic chemical classes detected in positive ion mode (SO(+), NO(+)) and one in negative mode (O2(-), also known as naphthenic acids) had the greatest DMW values, as high as 10 000. Estimates of DMW were similar to and correlated with DOW for O(+), O2(+), SO(+), and NO(+) chemical species, but for O2(-) and SO2(-) species the DMW values were much greater than the corresponding DOW, suggesting the importance of electrostatic interactions for these ionizable organic acids. Only SO(+), NO(+), and O2(-) species were detectable in medaka exposed to OSPW, and BCFs for SO(+) and NO(+) species ranged from 0.6 to 28 L/kg, lower than predicted (i.e., 1.4-1.7 × 10(3) L/kg), possibly because of biotransformation of these hydrophobic substances. BCFs of O2(-) species ranged from 0.7 to 53 L/kg, similar to predicted values and indicating that phospholipid partitioning was an important bioconcentration mechanism. PMID:27224302

  17. How does forest thinning affect short- and long-term water partitioning in the semi-arid Santa Fe Municipal Watershed, and how do these changes compare to unmediated forest responses to climate change?

    Science.gov (United States)

    Dugger, A. L.; Tague, C.; Allen, C. D.; Ringler, T.

    2011-12-01

    In water-limited environments, water and vegetation systems are intrinsically linked. Vegetation exerts direct controls on water partitioning through transpiration and indirect controls on partitioning through radiation and precipitation interception, rooting effects on soil permeability, and litter effects on water capture and storage, among others. In semi-arid forest systems of the Southwest U.S. in particular, vegetation controls on water partitioning are often the most dominant after climate, so changes in vegetation structure, species type, and biomass can lead to large shifts in downstream water availability. We use a coupled ecologic-hydrologic, process-based model (RHESSys) to investigate how human- and nature-induced changes in vegetation biomass, structure, and spatial distribution affect the partitioning of water into evaporation (E), transpiration (T), groundwater recharge (GW), and streamflow (Q) in the Santa Fe Municipal Watershed in Northern New Mexico. Previous work at this site has shown that RHESSys can successfully capture observed seasonal streamflow patterns and inter-annual biomass dynamics (growth/mortality) in response to climate. In this study, we use sensitivity analysis of model vegetation parameterization to estimate the relative magnitude of responses in E, T, GW, and Q due to a range of different vegetation manipulation scenarios, including uniform changes in biomass, varying spatial patterns of vegetation thinning, increasing canopy cover gaps through thinning, and changes in litter and coarse woody debris. The dynamic vegetation model allows us to not only evaluate instantaneous changes in partitioning associated with these manipulations, but also how partitioning evolves over time. Finally, we compare model estimates of effects on water partitioning from forest treatment to effects from unmediated "natural" vegetation responses to climate warming.

  18. How does soil management affect carbon losses from soils?

    Science.gov (United States)

    Klik, A.; Trümper, G.

    2009-04-01

    Agricultural soils are a major source as well as a sink of organic carbon (OC). Amount and distribution of OC within the soil and within the landscape are driven by land management but also by erosion and deposition processes. At the other hand the type of soil management influences mineralization and atmospheric carbon dioxide losses by soil respiration. In a long-term field experiment the impacts of soil tillage systems on soil erosion processes were investigated. Following treatments were compared: 1) conventional tillage (CT), 2) conservation tillage with cover crop during the winter period (CS), and 3) no-till with cover crop during winter period (NT). The studies were carried out at three sites in the Eastern part of Austria with annual precipitation amounts from 650 to 900 mm. The soil texture ranged from silt loam to loam. Since 2007 soil CO2 emissions are measured with a portable soil respiration system in intervals of about one week, but also in relation to management events. Concurrent soil temperature and soil water content are measured and soil samples are taken for chemical and microbiological analyses. An overall 14-yr. average soil loss between 1.0 t.ha-1.yr-1 for NT and 6.1 t.ha-1.yr-1 for CT resulted in on-site OC losses from 18 to 79 kg ha-1.yr-1. The measurements of the carbon dioxide emissions from the different treatments indicate a high spatial variation even within one plot. Referred to CT plots calculated carbon losses amounted to 65-94% for NT plots while for the different RT plots they ranged between 84 and 128%. Nevertheless site specific considerations have to be taken into account. Preliminary results show that the adaptation of reduced or no-till management strategies has enormous potential in reducing organic carbon losses from agricultural used soils.

  19. Different carbon sources affect PCB accumulation by marine bivalves.

    Science.gov (United States)

    Laitano, M V; Silva Barni, M F; Costa, P G; Cledón, M; Fillmann, G; Miglioranza, K S B; Panarello, H O

    2016-02-01

    Pampean creeks were evaluated in the present study as potential land-based sources of PCB marine contamination. Different carbon and nitrogen sources from such creeks were analysed as boosters of PCB bioaccumulation by the filter feeder bivalve Brachidontes rodriguezii and grazer limpet Siphonaria lessoni. Carbon of different source than marine and anthropogenic nitrogen assimilated by organisms were estimated through their C and N isotopic composition. PCB concentration in surface sediments and mollusc samples ranged from 2.68 to 6.46 ng g(-1) (wet weight) and from 1074 to 4583 ng g(-1) lipid, respectively, reflecting a punctual source of PCB contamination related to a landfill area. Thus, despite the low flow of creeks, they should not be underestimated as contamination vectors to the marine environment. On the other hand, mussels PCB bioaccumulation was related with the carbon source uptake which highlights the importance to consider this factor when studying PCB distribution in organisms of coastal systems.

  20. Atomic scale effects of alloying, partitioning, solute drag and austempering on the mechanical properties of high-carbon bainitic–austenitic TRIP steels

    International Nuclear Information System (INIS)

    Understanding alloying and thermal processing at an atomic scale is essential for the optimal design of high-carbon (0.71 wt.%) bainitic–austenitic transformation-induced plasticity (TRIP) steels. We investigate the influence of the austempering temperature, chemical composition (especially the Si:Al ratio) and partitioning on the nanostructure and mechanical behavior of these steels by atom probe tomography. The effects of the austempering temperature and of Si and Al on the compositional gradients across the phase boundaries between retained austenite and bainitic ferrite are studied. We observe that controlling these parameters (i.e. Si, Al content and austempering temperature) can be used to tune the stability of the retained austenite and hence the mechanical behavior of these steels. We also study the atomic scale redistribution of Mn and Si at the bainitic ferrite/austenite interface. The observations suggest that either para-equilibrium or local equilibrium-negligible partitioning conditions prevail depending on the Si:Al ratio during bainite transformation.

  1. Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors

    Energy Technology Data Exchange (ETDEWEB)

    Marek, Michal V., E-mail: marek.mv@czechglobe.cz [Global Change Research Centres, Academy of Science of the Czech Republic, Belidla 4a CZ-60300 Brno (Czech Republic); Institute of Forest Ecology Forestry Faculty, Mendel University Brno, Zemedelska 3, CZ-614 00 (Czech Republic); Janous, Dalibor; Taufarova, Klara; Havrankova, Katerina; Pavelka, Marian; Kaplan, Veroslav [Global Change Research Centres, Academy of Science of the Czech Republic, Belidla 4a CZ-60300 Brno (Czech Republic); Markova, Irena [Institute of Forest Ecology Forestry Faculty, Mendel University Brno, Zemedelska 3, CZ-614 00 (Czech Republic)

    2011-05-15

    By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands. - Highlights: > Highest carbon sequestration potential in evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). > The final carbon gain of the grassland was negative (massive ecosystem respiration). > Climate is important factor of net primary productivity. > Carbon uptake is strongly affected by the ontogeny and a production strategy of ecosystem. - Identification of the apparent differences in the carbon storage by different ecosystem types.

  2. Multiwalled Carbon Nanotube Dispersion Methods Affect Their Aggregation, Deposition, and Biomarker Response

    Science.gov (United States)

    To systematically evaluate how dispersion methods affect the environmental behaviors of multiwalled carbon nanotubes (MWNTs), MWNTs were dispersed in various solutions (e.g., surfactants, natural organic matter (NOM), and etc.) via ultrasonication (SON) and long-term stirring (LT...

  3. Key biogeochemical factors affecting soil carbon storage in Posidonia meadows

    Science.gov (United States)

    Serrano, Oscar; Ricart, Aurora M.; Lavery, Paul S.; Mateo, Miguel Angel; Arias-Ortiz, Ariane; Masque, Pere; Rozaimi, Mohammad; Steven, Andy; Duarte, Carlos M.

    2016-08-01

    Biotic and abiotic factors influence the accumulation of organic carbon (Corg) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2-4 m depth) accumulated 3- to 4-fold higher Corg stocks (averaging 6.3 kg Corg m-2) at 3- to 4-fold higher rates (12.8 g Corg m-2 yr-1) compared to meadows closer to the deep limits of distribution (at 6-8 m depth; 1.8 kg Corg m-2 and 3.6 g Corg m-2 yr-1). In shallower meadows, Corg stocks were mostly derived from seagrass detritus (88 % in average) compared to meadows closer to the deep limit of distribution (45 % on average). In addition, soil accumulation rates and fine-grained sediment content (soils is influenced by interactions of biological (e.g., meadow productivity, cover and density), chemical (e.g., recalcitrance of Corg stocks) and physical (e.g., hydrodynamic energy and soil accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.

  4. Characterization of fly ash from low-sulfur and high-sulfur coal sources: Partitioning of carbon and trace elements with particle size

    Science.gov (United States)

    Hower, J.C.; Trimble, A.S.; Eble, C.F.; Palmer, C.A.; Kolker, A.

    1999-01-01

    Fly ash samples were collected in November and December of 1994, from generating units at a Kentucky power station using high- and low-sulfur feed coals. The samples are part of a two-year study of the coal and coal combustion byproducts from the power station. The ashes were wet screened at 100, 200, 325, and 500 mesh (150, 75, 42, and 25 ??m, respectively). The size fractions were then dried, weighed, split for petrographic and chemical analysis, and analyzed for ash yield and carbon content. The low-sulfur "heavy side" and "light side" ashes each have a similar size distribution in the November samples. In contrast, the December fly ashes showed the trend observed in later months, the light-side ash being finer (over 20 % more ash in the -500 mesh [-25 ??m] fraction) than the heavy-side ash. Carbon tended to be concentrated in the coarse fractions in the December samples. The dominance of the -325 mesh (-42 ??m) fractions in the overall size analysis implies, though, that carbon in the fine sizes may be an important consideration in the utilization of the fly ash. Element partitioning follows several patterns. Volatile elements, such as Zn and As, are enriched in the finer sizes, particularly in fly ashes collected at cooler, light-side electrostatic precipitator (ESP) temperatures. The latter trend is a function of precipitation at the cooler-ESP temperatures and of increasing concentration with the increased surface area of the finest fraction. Mercury concentrations are higher in high-carbon fly ashes, suggesting Hg adsorption on the fly ash carbon. Ni and Cr are associated, in part, with the spinel minerals in the fly ash. Copyright ?? 1999 Taylor & Francis.

  5. Black Carbon Vertical Profiles Strongly Affect its Radiative Forcing Uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Samset, B. H.; Myhre, G.; Schulz, M.; Balkanski, Y.; Bauer, Susanne E.; Berntsen, T.; Bian, Huisheng; Bellouin, N.; Diehl, T.; Easter, Richard C.; Ghan, Steven J.; Iversen, T.; Kinne, Stefan; Kirkevag, A.; Lamarque, J.-F.; Lin, G.; Liu, Xiaohong; Penner, Joyce E.; Seland, O.; Skeie, R. B.; Stier, P.; Takemura, T.; Tsigaridis, K.; Zhang, Kai

    2013-03-01

    The impact of black carbon (BC) aerosols on the global radiation balance is not well constrained. Here twelve global aerosol models are used to show that at least 20% of the present uncertainty in modeled BC direct radiative forcing (RF) is due to diversity in the simulated vertical profile of BC mass. Results are from phases 1 and 2 of the global aerosol model intercomparison project (AeroCom). Additionally, a significant fraction of the variability is shown to come from high altitudes, as, globally, more than 40% of the total BC RF is exerted above 5 km. BC emission regions and areas with transported BC are found to have differing characteristics. These insights into the importance of the vertical profile of BC lead us to suggest that observational studies are needed to better characterize the global distribution of BC, including in the upper troposphere.

  6. Carbon Partitioning and Allometric Relationships between Stem Diameter and Total Organic Carbon (TOC in Plant Components of Bruguiera gymnorrhiza (L. Lamk. and Lumnitzera racemosa Willd. in a Microtidal Basin Estuary in Sri Lanka

    Directory of Open Access Journals (Sweden)

    K.A.R.S. Perera

    2013-02-01

    Full Text Available Plants sequester carbon and this capacity depends on their net primary productivity and pattern of biomass/carbon partitioning within them which is less well studied for mangroves. Above (A to below (B-ground carbon ratio (A/B of both Bruguiera gymnorrhiza (L. Lamk. and Lumnitzera racemosa Willd. from where micro-tidal conditions prevail, Negombo estuary, Sri Lanka (7°11′42.18″ N ~ 79°50′47.50″ E was approximately 3, and it resembles that of terrestrial plants than that of mangroves in macro-tidal coasts. Relatively low inundation frequency, duration and depth apparently promote aerial growth than root production. Wet oxidation without external heating, followed by colorimetric method was adopted to determine total organic carbon (TOC of plant components. Except for leaves of L. racemosa, nearly half the biomass of all other components of the two species was composed of TOC. Statistically significant allometric relationships exist among TOC and dbh (diameter at breast height of trees. As 96.5% of TOC in L. racemosa was in sequestered form (in the wood it is superior to B. gymnorrhiza which accumulates carbon only 78.7% in sequestered form. Profuse branching of L. racemosa contributes to carbon sequestration capacity of the species.

  7. Does pro-environmental behaviour affect carbon emissions?

    International Nuclear Information System (INIS)

    The primary focus of this research is to explore the effect of pro-environmental behaviour on CO2 emissions in relation to heating, electricity and transport activities in the residential sector. Changing such behaviour has considerable potential for conserving energy and is an important target of environmental policies which are designed to decrease energy consumption. It is hypothesized that people who consciously act in a pro-environmental way do not necessarily have lower CO2 emissions more than those who do not undertake environmental activities. Data about residential energy use is based on a survey carried out in Hungary in 2010 with a sample of 1012 people. Latent cluster analysis (LCA) was conducted based on data about the reported pro-environmental behavior in the survey and four clusters were identified. Relevant sociostructural and structural factors were also inverstigated. Results of the data analysis show that no significant difference is found between the impacts of environmentally aware and environmentally unaware consumers, i.e. both ‘Brown’ and ‘Supergreen’ consumers consume approximately the same amount of energy and produce approximately the same amount of carbon emissions because the motivation-driven activities of ‘Supergreens’ are offset by structural factors

  8. Boron nutrition affects the carbon metabolism of silver birch seedlings.

    Science.gov (United States)

    Ruuhola, Teija; Keinänen, Markku; Keski-Saari, Sarita; Lehto, Tarja

    2011-11-01

    Boron (B) is an essential micronutrient whose deficiency is common both in agriculture and in silviculture. Boron deficiency impairs the growth of plants and affects many metabolic processes like carbohydrate metabolism. Boron deficiency and also excess B may decrease the sink demand by decreasing the growth and sugar transport which may lead to the accumulation of carbohydrates and down-regulation of photosynthesis. In this study, we investigated the effects of B nutrition on the soluble and storage carbohydrate concentrations of summer leaves and autumn buds in a deciduous tree species, Betula pendula Roth. In addition, we investigated the changes in the pools of condensed tannins between summer and autumn harvests. One-year-old birch seedlings were fertilized with a complete nutrient solution containing three different levels of B: 0, 30 and 100% of the standard level for complete nutrient solution. Half of the seedlings were harvested after summer period and another half when leaves abscised. The highest B fertilization level (B100) caused an accumulation of starch and a decrease in the concentrations of hexoses (glucose and fructose) in summer leaves, whereas in the B0 seedlings, hexoses (mainly glucose) accumulated and starch decreased. These changes in carbohydrate concentrations might be related to the changes in the sink demand since the autumn growth was the smallest for the B100 seedlings and largest for the B30 seedlings that did not accumulate carbohydrates. The autumn buds of B30 seedlings contained the lowest levels of glucose, glycerol, raffinose and total polyols, which was probably due to the dilution effect of the deposition of other substances like phenols. Condensed tannins accumulated in high amounts in the birch stems during the hardening of seedlings and the largest accumulation was detected in the B30 treatment. Our results suggest that B nutrition of birch seedlings affects the carbohydrate and phenol metabolism and may play an important

  9. Carbon transfer, partitioning and residence time in the plant-soil system: a comparison of two 13CO2 labelling techniques

    Science.gov (United States)

    Studer, M. S.; Siegwolf, R. T. W.; Abiven, S.

    2014-03-01

    Various 13CO2 labelling approaches exist to trace carbon (C) dynamics in plant-soil systems. However, it is not clear if the different approaches yield the same results. Moreover, there is no consistent way of data analysis to date. In this study we compare with the same experimental setup the two main techniques: pulse and continuous labelling. We evaluate how these techniques perform to estimate the C transfer time, the C partitioning along time and the C residence time in different plant-soil compartments. We used identical plant-soil systems (Populus deltoides × nigra, Cambisol soil) to compare the pulse labelling approach (exposure to 99 atom % 13CO2 for three hours, traced for eight days) with a continuous labelling (exposure to 10 atom % 13CO2, traced for 14 days). The experiments were conducted in climate chambers under controlled environmental conditions. Before label addition and at four successive sampling dates, the plant-soil systems were destructively harvested, separated into leaves, petioles, stems, cuttings, roots and soil and soil microbial biomass was extracted. The soil CO2 efflux was sampled throughout the experiment. To model the C dynamics we used an exponential function to describe the 13C signal decline after pulse labelling. For the evaluation of the 13C distribution during the continuous labelling we applied a logistic function. Pulse labelling is best suited to assess the minimum C transfer time from the leaves to other compartments, while continuous labelling can be used to estimate the mean transfer time through a compartment, including short-term storage pools. The C partitioning between the plant-soil compartments obtained was similar for both techniques, but the time of sampling had a large effect: shortly after labelling the allocation into leaves was overestimated and the soil 13CO2 efflux underestimated. The results of belowground C partitioning were consistent for the two techniques only after eight days of labelling, when the

  10. Microstructural Evolution of a Low-Carbon Steel during Application of Quenching and Partitioning Heat Treatments after Partial Austenitization

    NARCIS (Netherlands)

    Santofimia, M.J.; Zhao, L.; Sietsma, J.

    2008-01-01

    The “quenching and partitioning” (Q&P) process has been studied in a low-carbon steel containing 1.1 wt pct aluminum by heat treatments consisting of partial austenitization at 900 °C and subsequent rapid cooling to a quenching temperature in the range between 125 °C and 175 °C, followed by an isoth

  11. Carbon dioxide inhalation induces dose-dependent and age-related negative affectivity.

    Directory of Open Access Journals (Sweden)

    Eric J Griez

    Full Text Available BACKGROUND: Carbon dioxide inhalation is known to induce an emotion similar to spontaneous panic in Panic Disorder patients. The affective response to carbon dioxide in healthy subjects was not clearly characterized yet. METHODOLOGY/PRINCIPAL FINDINGS: Sixty-four healthy subjects underwent a double inhalation of four mixtures containing respectively 0, 9, 17.5 and 35% CO(2 in compressed air, following a double blind, cross-over, randomized design. Affective responses were assessed according to DSM IV criteria for panic, using an Electronic Visual Analogue Scale and the Panic Symptom List. It was demonstrated that carbon dioxide challenges induced a dose dependent negative affect (p<0.0001. This affect was semantically identical to the DSM IV definition of panic. Older individuals were subjectively less sensitive to Carbon Dioxide (p<0.05. CONCLUSIONS/SIGNIFICANCE: CO(2 induced affectivity may lay on a continuum with pathological panic attacks. Consistent with earlier suggestions that panic is a false biological alarm, the affective response to CO(2 may be part of a protective system triggered by suffocation and acute metabolic distress.

  12. Heterotrophic Soil Respiration in Warming Experiments: Using Microbial Indicators to Partition Contributions from Labile and Recalcitrant Soil Organic Carbon. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bradford, M A; Melillo, J M; Reynolds, J F; Treseder, K K; Wallenstein, M D

    2010-06-10

    The central objective of the proposed work was to develop a genomic approach (nucleic acid-based) that elucidates the mechanistic basis for the observed impacts of experimental soil warming on forest soil respiration. The need to understand the mechanistic basis arises from the importance of such information for developing effective adaptation strategies for dealing with projected climate change. Specifically, robust predictions of future climate will permit the tailoring of the most effective adaptation efforts. And one of the greatest uncertainties in current global climate models is whether there will be a net loss of carbon from soils to the atmosphere as climate warms. Given that soils contain approximately 2.5 times as much carbon as the atmosphere, a net loss could lead to runaway climate warming. Indeed, most ecosystem models predict that climate warming will stimulate microbial decomposition of soil carbon, producing such a positive feedback to rising global temperatures. Yet the IPCC highlights the uncertainty regarding this projected feedback. The uncertainty arises because although warming-experiments document an initial increase in the loss of carbon from soils, the increase in respiration is short-lived, declining to control levels in a few years. This attenuation could result from changes in microbial physiology with temperature. We explored possible microbial responses to warming using experiments and modeling. Our work advances our understanding of how soil microbial communities and their activities are structured, generating insight into how soil carbon might respond to warming. We show the importance of resource partitioning in structuring microbial communities. Specifically, we quantified the relative abundance of fungal taxa that proliferated following the addition of organic substrates to soil. We added glycine, sucrose, cellulose, lignin, or tannin-protein to soils in conjunction with 3-bromo-deoxyuridine (BrdU), a nucleotide analog. Active

  13. Factors affecting the strength and toughness of ultra-low carbon steel weld metal

    OpenAIRE

    Van Slyke, Jonathon J.

    1999-01-01

    The factors that affect strength and toughness often ultra-low carbon steel weld samples (HSLA-80 and HSLA-100), welded using the gas metal arc welding (GMAW) process and new ultra-low carbon consumable electrodes, were studied. The analysis was confined only to the weld metal, and the base metal was not considered. Analysis methods included optical microscopy, scanning electron microscopy, and transmission electron microscopy. Energy dispersive x- ray analysis was performed in the transmissi...

  14. The effect of flood events on the partitioning of labile and refractory carbon in the Missouri-Mississippi River system

    Science.gov (United States)

    Roe, K. M.; Rosenheim, B. E.; Kolker, A.; Allison, M. A.; Nittrouer, J. A.; Duncan, D. D.; Nyman, J. A.; Butcher, K. A.; Adamic, J. F.

    2009-12-01

    The Missouri-Mississippi River system (MMRS) transports over 40% (4.0 x 109 kg) of the United States's annual input of total organic carbon (OC) from land to the marine environment, yet it is challenging to assess the MMRS’s exact role in the global carbon cycle because of the system’s complexity and temporal variability (i.e. high discharge events and low flow regimes). Determining the relative proportion of labile OC to refractory OC entrained in the MMRS during high and mean flow conditions would lend to the understanding of the MMRS’s role in the flux of carbon between the biospheric and atmospheric reservoirs, which is central to determining the role of anthropogenic CO2 in the global carbon cycle and in climate change. In this study, we investigate the relative proportion of labile OC to refractory OC in the lower MMRS during high and near-mean flow conditions in the springs of 2008 and 2009, respectively. The 2008 spring flood discharged 105 km3 of water, the maximum amount of water ever allowed out of the main channel, at a maximum rate of 4.3 x 104 m3s-1. Events of this scale have occurred only nine times in the past 80 years. Additionally, during the spring 2008 flood, bedload sand and large particulate OC transport rates were observed to increase exponentially. The following spring, high discharge rates returned to near-mean values with a peak discharge of 3.6 x 103 m3s-1. Using radiocarbon age and the thermal stability of organic matter (OM) as a proxy for lability, we evaluate the spectra of ages of particulate OM transported in the lower MMRS during these two flow regimes using a programmed-temperature pyrolysis/combustion system (PTP/CS) coupled with 14C determination. The PTP/CS utilizes the differences in thermal stability of acid insoluble particulate organic matter (AIPOM) to separate different components from the bulk. Employing PTP/CS on bulk AIPOM can complement experiments measuring small proportions of total OM such as compound

  15. Mass and energy balance of the carbonization of babassu nutshell as affected by temperature

    Directory of Open Access Journals (Sweden)

    Thiago de Paula Protásio

    2014-03-01

    Full Text Available The objective of this work was to evaluate the carbonization yield of babassu nutshell as affected by final temperature, as well as the energy losses involved in the process. Three layers constituting the babassu nut, that is, the epicarp, mesocarp and endocarp, were used together. The material was carbonized, considering the following final temperatures: 450, 550, 650, 750, and 850ºC. The following were evaluated: energy and charcoal yields, pyroligneous liquid, non-condensable gases, and fixed carbon. The use of babassu nutshell can be highly feasible for charcoal production. The yield of charcoal from babassu nutshell carbonization was higher than that reported in the literature for Eucalyptus wood carbonization, considering the final temperature of 450ºC. Charcoal and energy yields decreased more sharply at lower temperatures, with a tendency to stabilize at higher temperatures. The energy yields obtained can be considered satisfactory, with losses between 45 and 52% (based on higher heating value and between 43 and 49% (based on lower heating value at temperatures ranging from 450 to 850ºC, respectively. Yields in fixed carbon and pyroligneous liquid are not affected by the final carbonization temperature.

  16. How Does the Partitioning of Evapotranspiration and Runoff between Different Processes Affect the Variability and Predictability of Soil Moisture and Precipitation?

    Institute of Scientific and Technical Information of China (English)

    Robert E. DICKINSON; Guiling WANG; Xubin ZENG; ZENG Qingcun(曾庆存)

    2003-01-01

    Water stored as part of the land surface is lost to evapotranspiration and runoff on different time scales,and the partitioning between these time scales is important for modeling soil water in a climate model.Different time scales are imposed on evapotranspiration primarily because it is derived from differentreservoirs with different storage capacities, from the very rapid evaporation of canopy stores to the slowremoval by transpiration of rooting zone soil moisture. Runoff likewise ranges in time scale from rapidsurface terms to the slower base-flow. The longest time scale losses of water determine the slow variationof soil moisture and hence the longer time scale effects of soil moisture on precipitation. This paper showswith a simple analysis how shifting the partitioning of evapotranspiration between the different reservoirsaffects the variability of soil moisture and precipitation. In particular, it is concluded that a shift toshorter time scale reservoirs shifts the variance of precipitation from that which is potentially predictableto unpredictable.

  17. Carbon and nitrogen partitioning during the post-anthesis period is conditioned by N fertilisation and sink strength in three cereals.

    Science.gov (United States)

    Aranjuelo, I; Cabrera-Bosquet, L; Araus, J L; Nogués, S

    2013-01-01

    Further knowledge of the processes conditioning nitrogen use efficiency (NUE) is of great relevance to crop productivity. The aim of this paper was characterise C and N partitioning during grain filling and their implications for NUE. Cereals such as bread wheat (Triticum aestivum L. cv Califa sur), triticale (× Triticosecale Wittmack cv. Imperioso) and tritordeum (× Tritordeum Asch. & Graebn line HT 621) were grown under low (LN, 5 mm NH(4) NO(3)) and high (HN, 15 mm NH(4)NO(3)) N conditions. We conducted simultaneous double labelling ((12)CO(2) and (15)NH(4) (15)NO(3)) in order to characterise C and N partitioning during grain filling. Although triticale plants showed the largest total and ear dry matter values in HN conditions, the large investment in shoot and root biomass negatively affected ear NUE. Tritordeum was the only genotype that increased NUE in both N treatments (NUE(total)), whereas in wheat, no significant effect was detected. N labelling revealed that N fertilisation during post-anthesis was more relevant for wheat and tritordeum grain filling than for triticale. The study also revealed that the investments of C and N in flag leaves and shoots, together with the 'waste' of photoassimilates in respiration, conditioned the NUE of plants, and especially under LN. These results suggest that C and N use by these plants needs to be improved in order to increase ear C and N sinks, especially under LN. It is also remarkable that even though tritordeum shows the largest increase in NUE, the low yield of this cereal limits its agronomic value. PMID:22672709

  18. Assimilate Partitioning and Plant Development

    Institute of Scientific and Technical Information of China (English)

    Yong-Ling Ruan; John W.Patrick; Hans Weber

    2010-01-01

    @@ It has been a pleasure to organize this special issue of Molecular Plant on 'Assimilate Partitioning and Plant Development'. Assimilate, a collective term describing organic carbon (C) and nitrogen (N), is of paramount importance for plant development and realization of crop productivity.

  19. Tracking the fingerprints and combined TOC-black carbon mediated soil-air partitioning of polychlorinated naphthalenes (PCNs) in the Indus River Basin of Pakistan.

    Science.gov (United States)

    Ali, Usman; Sánchez-García, Laura; Rehman, Muhammad Yasir Abdur; Syed, Jabir Hussain; Mahmood, Adeel; Li, Jun; Zhang, Gan; Jones, Kevin C; Malik, Riffat Naseem

    2016-01-01

    This study reports the first investigation of polychlorinated naphthalenes (PCNs) in air and soil samples from ecologically important sites of the Indus River Basin, Pakistan. The concentrations of ∑39-PCNs in air and soil were found in a range between 1-1588 pg m(-3) and 0.02-23 ng g(-1) while the mean TEQ values were calculated to be 5.4E(-04) pg TEQ m(-3) and 1.6E(+01) pg TEQ g(-1), respectively. Spatially, air and soil PCN concentrations were found to be high at Rahim Yar Khan (agricultural region). Lower-medium chlorinated PCNs (sum of tri-, tetra- and penta-CNs) predominated in both air and soil, altogether constituting 87 and 86% of total PCNs in the two environmental matrices, respectively. According to the data, soil-air partitioning of PCNs was interpreted to be similarly controlled by the combined effect of black carbon and organic matter in the Indus River Basin, with no preferential implication of the recalcitrant organic form. PMID:26613673

  20. High strength-elongation product of Nb-microalloyed low-carbon steel by a novel quenching-partitioning-tempering process

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, S. [Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, K.; Wang, Y. [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Gu, J.F. [Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240 (China); Rong, Y.H., E-mail: yhrong@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2011-10-15

    Highlights: {yields} As-treated Q-P-T steel covers a wide spectrum of strength and elongation. {yields} High strength results from martensite laths and NbC or {epsilon}-carbides in martensite matrix. {yields} Good ductility is attributed to TRIP effect from retained austenite flakes. {yields} Si can only suppress the formation of Fe{sub 3}C in short tempering time steel. {yields} Si cannot suppress the formation of {epsilon}-carbides in low tempering temperature. - Abstract: In this article, a novel quenching-partitioning-tempering (Q-P-T) process was applied to a Fe-0.25C-1.5Mn-1.2Si-1.5Ni-0.05Nb (wt%) hot-rolled steel, and its optimized parameters were obtained by a Gleeble-3500 thermal simulator and salt baths, respectively. Mechanical property results of the as-treated Q-P-T samples show that the Nb-microalloyed low-carbon steels subjected to Q-P-T processes cover a wide spectrum of strength (1200-1500 MPa) and elongation (14-18%), and exhibit excellent product of strength and elongation (21,000-22,000 MPa%). Microstructural characterization indicates that high strength results from dislocation-type martensite laths and dispersively distributed fcc NbC or hcp {epsilon}-carbides in martensite matrix and good ductility is attributed to transformation induced plasticity (TRIP) effect from plenty of retained austenite flakes between martensite laths.

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

    Science.gov (United States)

    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

  2. Linear solvation energy relationship of the limiting partition coefficient of organic solutes between water and activated carbon

    Science.gov (United States)

    Luehrs, Dean C.; Hickey, James P.; Nilsen, Peter E.; Godbole, K.A.; Rogers, Tony N.

    1995-01-01

    A linear solvation energy relationship has been found for 353 values of the limiting adsorption coefficients of diverse chemicals:  log K = −0.37 + 0.0341Vi − 1.07β + D + 0.65P with R = 0.951, s = 0.51, n = 353, and F = 818.0, where Vi is the intrinsic molar volume; β is a measure of the hydrogen bond acceptor strength of the solute; D is an index parameter for the research group which includes the effects of the different types of carbon used, the temperature, and the length of time allowed for the adsorption equilibrium to be established; and P is an index parameter for the flatness of the molecule. P is defined to be unity if there is an aromatic system in the molecule or if there is a double bond or series of conjugated double bonds with no more that one non-hydrogen atom beyond the double bond and zero otherwise. A slightly better fit is obtained if the two-thirds power of Vi is used as a measure of the surface area in place of the volume term:  log K = −1.75 + 0.227V2/3 − 1.10β + D + 0.60P with R = 0.954, s = 0.49, n = 353, and F = 895.39. This is the first quantitative measure of the effect of the shape of the molecule on its tendency to be adsorbed on activated carbon.

  3. Carbon use in root respiration as affected by elevated atmospheric O-2

    NARCIS (Netherlands)

    Lambers, H; Stulen, [No Value; vanderWerf, A

    1996-01-01

    The use of fossil fuel is predicted to cause an increase of the atmospheric CO2 concentration, which will affect the global pattern of temperature and precipitation. It is therefore essential to incorporate effects of temperature and water supply on the carbon requirement for root respiration of pla

  4. Repeated administrations of carbon nanotubes in male mice cause reversible testis damage without affecting fertility

    Science.gov (United States)

    Bai, Yuhong; Zhang, Yi; Zhang, Jingping; Mu, Qingxin; Zhang, Weidong; Butch, Elizabeth R.; Snyder, Scott E.; Yan, Bing

    2010-09-01

    Soluble carbon nanotubes show promise as materials for in vivo delivery and imaging applications. Several reports have described the in vivo toxicity of carbon nanotubes, but their effects on male reproduction have not been examined. Here, we show that repeated intravenous injections of water-soluble multiwalled carbon nanotubes into male mice can cause reversible testis damage without affecting fertility. Nanotubes accumulated in the testes, generated oxidative stress and decreased the thickness of the seminiferous epithelium in the testis at day 15, but the damage was repaired at 60 and 90 days. The quantity, quality and integrity of the sperm and the levels of three major sex hormones were not significantly affected throughout the 90-day period. The fertility of treated male mice was unaffected; the pregnancy rate and delivery success of female mice that mated with the treated male mice did not differ from those that mated with untreated male mice.

  5. Linear modeling of the soil-water partition coefficient normalized to organic carbon content by reversed-phase thin-layer chromatography.

    Science.gov (United States)

    Andrić, Filip; Šegan, Sandra; Dramićanin, Aleksandra; Majstorović, Helena; Milojković-Opsenica, Dušanka

    2016-08-01

    Soil-water partition coefficient normalized to the organic carbon content (KOC) is one of the crucial properties influencing the fate of organic compounds in the environment. Chromatographic methods are well established alternative for direct sorption techniques used for KOC determination. The present work proposes reversed-phase thin-layer chromatography (RP-TLC) as a simpler, yet equally accurate method as officially recommended HPLC technique. Several TLC systems were studied including octadecyl-(RP18) and cyano-(CN) modified silica layers in combination with methanol-water and acetonitrile-water mixtures as mobile phases. In total 50 compounds of different molecular shape, size, and various ability to establish specific interactions were selected (phenols, beznodiazepines, triazine herbicides, and polyaromatic hydrocarbons). Calibration set of 29 compounds with known logKOC values determined by sorption experiments was used to build simple univariate calibrations, Principal Component Regression (PCR) and Partial Least Squares (PLS) models between logKOC and TLC retention parameters. Models exhibit good statistical performance, indicating that CN-layers contribute better to logKOC modeling than RP18-silica. The most promising TLC methods, officially recommended HPLC method, and four in silico estimation approaches have been compared by non-parametric Sum of Ranking Differences approach (SRD). The best estimations of logKOC values were achieved by simple univariate calibration of TLC retention data involving CN-silica layers and moderate content of methanol (40-50%v/v). They were ranked far well compared to the officially recommended HPLC method which was ranked in the middle. The worst estimates have been obtained from in silico computations based on octanol-water partition coefficient. Linear Solvation Energy Relationship study revealed that increased polarity of CN-layers over RP18 in combination with methanol-water mixtures is the key to better modeling of

  6. Partitioning Net Ecosystem Carbon Exchange Into net Assimilation and Respiration With Canopy-scale Isotopic Measurements: an Error Propagation Analysis With Both 13C and 18O Data

    Science.gov (United States)

    Peylin, P.; Ogee, J.; Cuntz, M.; Bariac, T.; Ciais, P.; Brunet, Y.

    2003-12-01

    Stable CO2 isotope measurements are increasingly used to partition the net CO2 exchange between terrestrial ecosystems and the atmosphere in terms of non-foliar respiration (FR) and gross photosynthesis (FA). However the accuracy of the partitioning strongly depends on the isotopic disequilibrium between these two gross fluxes and a rigorous estimation of the errors on FA and FR is needed. In this study we account and propagate uncertainties on all terms in the mass balance equations for total and "labeled" CO2 in order to get precise estimates of the errors on FA and FR. We applied our method to a maritime pine forest in the Southwest of France. Using the δ 13C-CO2 and CO2 measurements, we show that the resulting uncertainty associated to the gross fluxes can be as large as 4 æmol m-2 s-1. In addition, even if we could get more precise estimates of the isoflux and the isotopic signature of FA we show that this error would not be significantly reduced. This is because the isotopic disequilibrium between FA and FR is around 2-3‰ , i.e. the order of magnitude of the uncertainty on the isotopic signature of FR (δ R). With δ 18O-CO2 and CO2 measurements, the uncertainty associated to the gross fluxes lies also around 4 æmol m-2 s-1. On the other hand, it could be dramatically reduced if we were able to get more precise estimates of the CO18O isoflux and the associated discrimination during photosynthesis. This is because the isotopic disequilibrium between FA and FR is large, of the order of 10-15‰ , i.e. much larger than the uncertainty on δ R. The isotopic disequilibrium between FA and FR or the uncertainty on δ R vary among ecosystems and over the year. Our approach may help to choose the best strategy to study the carbon budget of a given ecosystem using stable isotopes.

  7. The protein binding substance Ibuprofen does not affect the T1 time or partition coefficient in contrast-enhanced cardiovascular magnetic resonance

    Directory of Open Access Journals (Sweden)

    Kawel Nadine

    2012-10-01

    Full Text Available Abstract Background Contrast enhanced cardiovascular magnetic resonance (CMR with T1 mapping enables quantification of diffuse myocardial fibrosis. Various factors, however, can interfere with T1 measurements. The purpose of the current study was to assess the effect of co-medication with a typical protein binding drug (Ibuprofen on T1 values in vitro and in vivo. Methods 50 vials were prepared with different concentrations of gadobenate dimeglumine, Ibuprofen and human serum albumin in physiologic NaCl solution and imaged at 1.5T with a spin echo sequence at multiple TRs to measure T1 values and calculate relaxivities. 10 volunteers (5 men; 31±6.3 years were imaged at 1.5T. T1 values for myocardium and blood pool were determined for various time points after administration of 0.15mmol/kg gadobenate dimeglumine using a modified look-locker inversion-recovery sequence before and after administration of Ibuprofen over 24 hours. The partition coefficient was calculated as ΔR1myocardium/ΔR1blood, where R1=1/T1. Results In vitro no significant correlation was found between relaxivity and Ibuprofen concentration, neither in absence (r=−0.15, p=0.40 nor in presence of albumin (r=−0.32, p=0.30. In vivo there was no significant difference in post contrast T1 times of myocardium and blood, respectively and also in the partition coefficient between exam 1 and 2 (p>0.05. There was good agreement of the T1 times of myocardium and blood and the partition coefficient, respectively between exam 1 and 2. Conclusions Contrast enhanced T1 mapping is unaffected by co-medication with the protein binding substance Ibuprofen and has an excellent reproducibility.

  8. SOWING DATE MEDIATED HEAT STRESS AFFECTS THE LEAF GROWTH AND DRY MATTER PARTITIONING IN SOME SPRING WHEAT (TRITICUM AESTIVUM L.) CULTIVARS

    OpenAIRE

    Kamal Uddin Ahamed, Kamrun Nahar and Masayuki Fujita

    2010-01-01

    To observe the effect of high temperature stress on the leaf growth and dry matter partitioning of 5 wheat varieties (Sourav, Pradip, Sufi, Shatabdi and Bijoy) a field experiment was conducted with normal sowing (sowing at November 30) and late sowing (sowing at December 30) at the research field of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh. It was observed that stem dry weight was highest in Shatabdi under both normal (2.267 g) and heat stressed (1.801 g) environment and Pradi...

  9. Water level changes affect carbon turnover and microbial community composition in lake sediments

    Science.gov (United States)

    Weise, Lukas; Ulrich, Andreas; Moreano, Matilde; Gessler, Arthur; E. Kayler, Zachary; Steger, Kristin; Zeller, Bernd; Rudolph, Kristin; Knezevic-Jaric, Jelena; Premke, Katrin

    2016-01-01

    Due to climate change, many lakes in Europe will be subject to higher variability of hydrological characteristics in their littoral zones. These different hydrological regimes might affect the use of allochthonous and autochthonous carbon sources. We used sandy sediment microcosms to examine the effects of different hydrological regimes (wet, desiccating, and wet-desiccation cycles) on carbon turnover. 13C-labelled particulate organic carbon was used to trace and estimate carbon uptake into bacterial biomass (via phospholipid fatty acids) and respiration. Microbial community changes were monitored by combining DNA- and RNA-based real-time PCR quantification and terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA. The shifting hydrological regimes in the sediment primarily caused two linked microbial effects: changes in the use of available organic carbon and community composition changes. Drying sediments yielded the highest CO2 emission rates, whereas hydrological shifts increased the uptake of allochthonous organic carbon for respiration. T-RFLP patterns demonstrated that only the most extreme hydrological changes induced a significant shift in the active and total bacterial communities. As current scenarios of climate change predict an increase of drought events, frequent variations of the hydrological regimes of many lake littoral zones in central Europe are anticipated. Based on the results of our study, this phenomenon may increase the intensity and amplitude in rates of allochthonous organic carbon uptake and CO2 emissions. PMID:26902802

  10. Molecular insights into how a deficiency of amylose affects carbon allocation – carbohydrate and oil analyses and gene expression profiling in the seeds of a rice waxy mutant

    Directory of Open Access Journals (Sweden)

    Zhang Ming-Zhou

    2012-12-01

    Full Text Available Abstract Background Understanding carbon partitioning in cereal seeds is of critical importance to develop cereal crops with enhanced starch yields for food security and for producing specified end-products high in amylose, β-glucan, or fructan, such as functional foods or oils for biofuel applications. Waxy mutants of cereals have a high content of amylopectin and have been well characterized. However, the allocation of carbon to other components, such as β-glucan and oils, and the regulation of the altered carbon distribution to amylopectin in a waxy mutant are poorly understood. In this study, we used a rice mutant, GM077, with a low content of amylose to gain molecular insight into how a deficiency of amylose affects carbon allocation to other end products and to amylopectin. We used carbohydrate analysis, subtractive cDNA libraries, and qPCR to identify candidate genes potentially responsible for the changes in carbon allocation in GM077 seeds. Results Carbohydrate analysis indicated that the content of amylose in GM077 seeds was significantly reduced, while that of amylopectin significantly rose as compared to the wild type BP034. The content of glucose, sucrose, total starch, cell-wall polysaccharides and oil were only slightly affected in the mutant as compared to the wild type. Suppression subtractive hybridization (SSH experiments generated 116 unigenes in the mutant on the wild-type background. Among the 116 unigenes, three, AGP, ISA1 and SUSIBA2-like, were found to be directly involved in amylopectin synthesis, indicating their possible roles in redirecting carbon flux from amylose to amylopectin. A bioinformatics analysis of the putative SUSIBA2-like binding elements in the promoter regions of the upregulated genes indicated that the SUSIBA2-like transcription factor may be instrumental in promoting the carbon reallocation from amylose to amylopectin. Conclusion Analyses of carbohydrate and oil fractions and gene expression

  11. Unique Path Partitions

    DEFF Research Database (Denmark)

    Bessenrodt, Christine; Olsson, Jørn Børling; Sellers, James A.

    2013-01-01

    We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions.......We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions....

  12. Affectivity

    OpenAIRE

    Stenner, Paul; Greco, Monica

    2013-01-01

    The concept of affectivity has assumed central importance in much recent scholarship, and many in the social sciences and humanities now talk of an ‘affective turn’. The concept of affectivity at play in this ‘turn’ remains, however, somewhat vague and slippery. Starting with Silvan Tomkins’ influential theory of affect, this paper will explore the relevance of the general assumptions (or ‘utmost abstractions’) that inform thinking about affectivity. The technological and instrumentalist char...

  13. Permafrost-Affected Soils of the Russian Arctic and their Carbon Pools

    Science.gov (United States)

    Zubrzycki, S.; Kutzbach, L.; Pfeiffer, E.-M.

    2014-02-01

    Permafrost-affected soils have accumulated enormous pools of organic matter during the Quaternary Period. The area occupied by these soils amounts to more than 8.6 million km2, which is about 27% of all land areas north of 50° N. Therefore, permafrost-affected soils are considered to be one of the most important cryosphere elements within the climate system. Due to the cryopedogenic processes that form these particular soils and the overlying vegetation that is adapted to the arctic climate, organic matter has accumulated to the present extent of up to 1024 Pg (1 Pg = 1015 g = 1 Gt) of soil organic carbon stored within the uppermost three meters of ground. Considering the observed progressive climate change and the projected polar amplification, permafrost-affected soils will undergo fundamental property changes. Higher turnover and mineralization rates of the organic matter are consequences of these changes, which are expected to result in an increased release of climate-relevant trace gases into the atmosphere. As a result, permafrost regions with their distinctive soils are likely to trigger an important tipping point within the global climate system, with additional political and social implications. The controversy of whether permafrost regions continue accumulating carbon or already function as a carbon source remains open until today. An increased focus on this subject matter, especially in underrepresented Siberian regions, could contribute to a more robust estimation of the soil organic carbon pool of permafrost regions and at the same time improve the understanding of the carbon sink and source functions of permafrost-affected soils.

  14. Carbon storage potential by four macrophytes as affected by planting diversity in a created wetland.

    Science.gov (United States)

    Means, Mary M; Ahn, Changwoo; Korol, Alicia R; Williams, Lisa D

    2016-01-01

    Wetland creation has become a commonplace method for mitigating the loss of natural wetlands. Often mitigation projects fail to restore ecosystem services of the impacted natural wetlands. One of the key ecosystem services of newly created wetlands is carbon accumulation/sequestration, but little is known about how planting diversity (PD) affects the ability of herbaceous wetland plants to store carbon in newly created wetlands. Most mitigation projects involve a planting regime, but PD, which may be critical in establishing biologically diverse and ecologically functioning wetlands, is seldom required. Using a set of 34 mesocosms (∼1 m(2) each), we investigated the effects of planting diversity on carbon storage potential of four native wetland plant species that are commonly planted in created mitigation wetlands in Virginia - Carex vulpinoidea, Eleocharis obtusa, Juncus effusus, and Mimulus ringens. The plants were grown under the four distinctive PD treatments [i.e., monoculture (PD 1) through four different species mixture (PD 4)]. Plant biomass was harvested after two growing seasons and analyzed for tissue carbon content. Competition values (CV) were calculated to understand how the PD treatment affected the competitive ability of plants relative to their biomass production and thus carbon storage potentials. Aboveground biomass ranged from 988 g/m(2) - 1515 g/m(2), being greatest in monocultures, but only when compared to the most diverse mixture (p = 0.021). However, carbon storage potential estimates per mesocosm ranged between 344 g C/m(2) in the most diverse mesocosms (PD 4) to 610 g C/m(2) in monoculture ones with no significant difference (p = 0.089). CV of E. obtusa and C. vulpinoidea showed a declining trend when grown in the most diverse mixtures but J. effusus and M. ringens displayed no difference across the PD gradient (p = 0.910). In monocultures, both M. ringens, and J. effusus appeared to store carbon as biomass more

  15. Soil-Air Partitioning of Polychlorinated Biphenyls and Total Dichloro-Diphenyl-Trichloroethanes

    Institute of Scientific and Technical Information of China (English)

    Yaping Zhang; Erping Bi; Honghan Chen

    2014-01-01

    Soil-air partitioning is an important diffusive process that affects the environmental fate of organic compounds and human health. In this review, factors affecting the soil-air partitioning of polychlorinated biphenyls (PCBs) and total dichloro-diphenyl-trichloroethanes (p,p’-and o,p’-isomers of DDT, DDD, and DDE) are discussed. Hydrophobicity is an important factor that influences soil-air partition coefficients (KSA), and its effect can be explained through enthalpy of phase change for soil-air partitioning transfer (ΔHSA). For more hydrophobic compounds, a sharp increase in the KSA of PCBs and organochlorines can be seen in the early aging period. During the aging period, the temperature has a significant effect on the more hydrophobic organic compounds. The content and properties of soil or-ganic matter influence the KSA of the target compounds. Generally, KSA decreases with increasing rela-tive humidity in soils. The linear trend between KSA and temperature (T) changes at 0 °C. Freezing the air or soil in experiments would change the research results. On the basis of factors influencing soil-air partitioning, a multipleparameter (T, organic carbon fraction (fOC), and octanol-air partition coefficient (KOA)) model is put forward to predict the KSA values for PCBs and total DDTs.

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

    Science.gov (United States)

    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.

  17. Mineralization and carbon turnover in subarctic heath soil as affected by warming and additional litter

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Michelsen, Anders; Baath, Erland;

    2007-01-01

    was to assess how factorial warming and litter addition in a long-term field experiment on a subarctic heath affect resource limitation of soil microbial communities (measured by thymidine and leucine incorporation techniques), net growing-season mineralization of nitrogen (N) and phosphorus (P), and carbon...... the field incubation. The added litter did not affect the carbon content, but it was a source of nutrients to the soil, and it also tended to increase bacterial growth rate and net mineralization of P. The inorganic N pool decreased during the field incubation of soil cores, especially in the separate...... warming and litter addition treatments, while gross mineralized N was immobilized in the biomass of microbes and plants transplanted into the incubates soil cores, but without any significant effect of the treatments. The effects of warming plus litter addition on bacterial growth rates and of warming...

  18. Does consideration of water routing affect simulated water and carbon dynamics in terrestrial ecosystems?

    Science.gov (United States)

    Tang, G.; Schneiderman, E. M.; Band, L. E.; Hwang, T.; Pierson, D. C.; Pradhanang, S. M.; Zion, M. S.

    2013-10-01

    The cycling of carbon in terrestrial ecosystems is closely coupled with the cycling of water. An important mechanism connecting ecological and hydrological processes in terrestrial ecosystems is lateral flow of water along landscapes. Few studies, however, have examined explicitly how consideration of water routing affects simulated water and carbon dynamics in terrestrial ecosystems. The objective of this study is to explore how consideration of water routing in a process-based hydroecological model affects simulated water and carbon dynamics. To achieve that end, we rasterized the regional hydroecological simulation systems (RHESSys) and employed the rasterized RHESSys (R-RHESSys) in a forested watershed. We performed and compared two contrasting simulations, one with and another without water routing. We found that R-RHESSys is able to correctly simulate major hydrological and ecological variables regardless of whether water routing is considered. When water routing was neglected, however, soil water table depth and saturation deficit were simulated to be smaller and spatially more homogeneous. As a result, evaporation, forest productivity and soil heterotrophic respiration also were simulated to be spatially more homogeneous compared to simulation with water routing. When averaged for the entire watershed, however, differences in simulated water and carbon fluxes are not significant between the two simulations. Overall, the study demonstrated that consideration of water routing enabled R-RHESSys to better capture our preconception of the spatial patterns of water table depth and saturation deficit across the watershed. Because the spatial pattern of soil moisture is fundamental to water efflux from land to the atmosphere, forest productivity and soil microbial activity, ecosystem and carbon cycle models, therefore, need to explicitly represent water routing in order to accurately quantify the magnitudes and patterns of water and carbon fluxes in terrestrial

  19. Changes in Carbon Electrode Morphology Affect Microbial Fuel Cell Performance with Shewanella oneidensis MR-1

    Directory of Open Access Journals (Sweden)

    David V. P. Sanchez

    2015-03-01

    Full Text Available The formation of biofilm-electrodes is crucial for microbial fuel cell current production because optimal performance is often associated with thick biofilms. However, the influence of the electrode structure and morphology on biofilm formation is only beginning to be investigated. This study provides insight on how changing the electrode morphology affects current production of a pure culture of anode-respiring bacteria. Specifically, an analysis of the effects of carbon fiber electrodes with drastically different morphologies on biofilm formation and anode respiration by a pure culture (Shewanella oneidensis MR-1 were examined. Results showed that carbon nanofiber mats had ~10 fold higher current than plain carbon microfiber paper and that the increase was not due to an increase in electrode surface area, conductivity, or the size of the constituent material. Cyclic voltammograms reveal that electron transfer from the carbon nanofiber mats was biofilm-based suggesting that decreasing the diameter of the constituent carbon material from a few microns to a few hundred nanometers is beneficial for electricity production solely because the electrode surface creates a more relevant mesh for biofilm formation by Shewanella oneidensis MR-1.

  20. The addition of organic carbon and nitrate affects reactive transport of heavy metals in sandy aquifers

    KAUST Repository

    Satyawali, Yamini

    2011-04-01

    Organic carbon introduction in the soil to initiate remedial measures, nitrate infiltration due to agricultural practices or sulphate intrusion owing to industrial usage can influence the redox conditions and pH, thus affecting the mobility of heavy metals in soil and groundwater. This study reports the fate of Zn and Cd in sandy aquifers under a variety of plausible in-situ redox conditions that were induced by introduction of carbon and various electron acceptors in column experiments. Up to 100% Zn and Cd removal (from the liquid phase) was observed in all the four columns, however the mechanisms were different. Metal removal in column K1 (containing sulphate), was attributed to biological sulphate reduction and subsequent metal precipitation (as sulphides). In the presence of both nitrate and sulphate (K2), the former dominated the process, precipitating the heavy metals as hydroxides and/or carbonates. In the presence of sulphate, nitrate and supplemental iron (Fe(OH)3) (K3), metal removal was also due to precipitation as hydroxides and/or carbonates. In abiotic column, K4, (with supplemental iron (Fe(OH)3), but no nitrate), cation exchange with soil led to metal removal. The results obtained were modeled using the reactive transport model PHREEQC-2 to elucidate governing processes and to evaluate scenarios of organic carbon, sulphate and nitrate inputs. © 2010 Elsevier B.V.

  1. Effects of partial defoliation on carbon and nitrogen partitioning and photosynthetic carbon uptake by two-year-old cork oak (Quercus suber) saplings.

    Science.gov (United States)

    Cerasoli, S; Scartazza, A; Brugnoli, E; Chaves, M M; Pereira, J S

    2004-01-01

    At the end of the growing season in late July, 20-month-old cork oak (Quercus suber L.) saplings were partially defoliated (63% of leaf area) to evaluate their ability to recover leaf area after defoliation. At 18 and 127 days after defoliation, changes in starch and nitrogen pools were determined in leaves and perennial organs, and variations in photosynthetic carbon uptake were investigated. To determine the role of stored nitrogen in regrowth after defoliation, plant nitrogen was labeled in the previous winter by enriching the nutrient solution with 15N. Plants recovered the lost leaf area in 127 days. Although there was remobilization of starch and nitrogen from leaves and perennial organs, the availability of resources for growth in the following spring was not decreased by defoliation. On the contrary, starch concentration in coarse roots was higher in defoliated saplings than in control saplings, presumably as a result of the higher net CO2 exchange rate in newly developed leaves compared with pre-existing leaves.

  2. Carbon availability affects diurnally controlled processes and cell morphology of Cyanothece 51142.

    Directory of Open Access Journals (Sweden)

    Jana Stöckel

    Full Text Available Cyanobacteria are oxygenic photoautotrophs notable for their ability to utilize atmospheric CO2 as the major source of carbon. The prospect of using cyanobacteria to convert solar energy and high concentrations of CO2 efficiently into biomass and renewable energy sources has sparked substantial interest in using flue gas from coal-burning power plants as a source of inorganic carbon. However, in order to guide further advances in this area, a better understanding of the metabolic changes that occur under conditions of high CO2 is needed. To determine the effect of high CO2 on cell physiology and growth, we analyzed the global transcriptional changes in the unicellular diazotrophic cyanobacterium Cyanothece 51142 grown in 8% CO2-enriched air. We found a concerted response of genes related to photosynthesis, carbon metabolism, respiration, nitrogen fixation, ribosome biosynthesis, and the synthesis of nucleotides and structural cell wall polysaccharides. The overall response to 8% CO2 in Cyanothece 51142 involves different strategies, to compensate for the high C/N ratio during both phases of the diurnal cycle. Our analyses show that high CO2 conditions trigger the production of carbon-rich compounds and stimulate processes such as respiration and nitrogen fixation. In addition, we observed that high levels of CO2 affect fundamental cellular processes such as cell growth and dramatically alter the intracellular morphology. This study provides novel insights on how diurnal and developmental rhythms are integrated to facilitate adaptation to high CO2 in Cyanothece 51142.

  3. Growth rate controlled barium partitioning in calcite and aragonite

    Science.gov (United States)

    Goetschl, Katja Elisabeth; Mavromatis, Vasileios; Baldermann, Andre; Purgstaller, Bettina; Dietzel, Martin

    2016-04-01

    The barium (Ba) content and the Ba/Ca molar ratios in biogenic and abiotic carbonates have been widely used from the scientific community as a geochemical proxy especially in marine and early diagenetic settings. The Ba content of carbonate minerals has been earlier associated to changes in oceanic circulation that may have been caused by upwelling, changes in weathering regimes and river-runoff as well as melt water discharge. The physicochemical controls of Ba ion incorporation in the two most abundant CaCO3 polymorphs found in Earth's surface environments, i.e. calcite and aragonite, have adequately been studied only for calcite. These earlier studies (i.e. [1]) suggest that at increasing growth rate, Ba partitioning in calcite is increasing as well. In contrast, to date the effect of growth rate on the partitioning of Ba in aragonite remains questionable, despite the fact that this mineral phase is the predominant carbonate-forming polymorph in shallow marine environments. To shed light on the mechanisms controlling Ba ion uptake in carbonates in this study we performed steady-state Ba co-precipitation experiments with calcite and aragonite at 25°C. The obtained results for the partitioning of Ba in calcite are in good agreement with those reported earlier by [1], whereas those for aragonite indicate a reduction of Ba partitioning at elevated aragonite growth rates, with the partitioning coefficient value between solid and fluid to be approaching the unity. This finding is good agreement with the formation of a solid solution in the aragonite-witherite system, owing to the isostructural crystallography of the two mineral phases. Moreover, our data set provides new insights that are required for reconstructing the evolution of the Ba content of pristine marine versus diagenetically altered carbonate minerals commonly occurring in marine subfloor settings, as the thermodynamically less stable aragonite will transform to calcite enriched in Ba, whilst affecting

  4. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xiao [School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, 430030, Wuhan (China); Schluesener, Hermann J, E-mail: mornsmile@yahoo.com [Institute of Brain Research, University of Tuebingen, Calwerstrasse 3, D-72076, Tuebingen (Germany)

    2010-03-12

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  5. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    Science.gov (United States)

    Chen, Xiao; Schluesener, Hermann J.

    2010-03-01

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  6. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    International Nuclear Information System (INIS)

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  7. How surface fire in Siberian Scots pine forests affects soil organic carbon in the forest floor: Stocks, molecular structure, and conversion to black carbon (charcoal)

    OpenAIRE

    Czimczik, Claudia I; Preston, Caroline M; Schmidt, Michael W I; Schulze, Ernst-Detlef

    2003-01-01

    [1] In boreal forests, fire is a frequent disturbance and converts soil organic carbon (OC) to more degradation-resistant aromatic carbon, i.e., black carbon (BC) which might act as a long-term atmospheric-carbon sink. Little is known on the effects of fires on boreal soil OC stocks and molecular composition. We studied how a surface fire affected the composition of the forest floor of Siberian Scots pine forests by comparing the bulk elemental composition, molecular structure (13C-MAS NMR), ...

  8. Hanford soil partitioning and vapor extraction study

    International Nuclear Information System (INIS)

    This report describes the testing and results of laboratory experiments conducted to assist the carbon tetrachloride soil vapor extraction project operating in the 200 West Area of the Hanford Site in Richland, Washington. Vapor-phase adsorption and desorption testing was performed using carbon tetrachloride and Hanford Site soils to estimate vapor-soil partitioning and reasonably achievable carbon tetrachloride soil concentrations during active vapor extractions efforts at the 200 West Area. (CCl4 is used in Pu recovery from aqueous streams.)

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

    OpenAIRE

    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 sedim...

  10. Regenerative partition structures

    OpenAIRE

    Gnedin, Alexander; Pitman, Jim

    2004-01-01

    We consider Kingman's partition structures which are regenerative with respect to a general operation of random deletion of some part. Prototypes of this class are the Ewens partition structures which Kingman characterised by regeneration after deletion of a part chosen by size-biased sampling. We associate each regenerative partition structure with a corresponding regenerative composition structure, which (as we showed in a previous paper) can be associated in turn with a regenerative random...

  11. Partitioning net ecosystem carbon exchange into net assimilation and respiration using 13CO2 measurements: A cost-effective sampling strategy

    Science.gov (United States)

    OgéE, J.; Peylin, P.; Ciais, P.; Bariac, T.; Brunet, Y.; Berbigier, P.; Roche, C.; Richard, P.; Bardoux, G.; Bonnefond, J.-M.

    2003-06-01

    The current emphasis on global climate studies has led the scientific community to set up a number of sites for measuring the long-term biosphere-atmosphere net CO2 exchange (net ecosystem exchange, NEE). Partitioning this flux into its elementary components, net assimilation (FA), and respiration (FR), remains necessary in order to get a better understanding of biosphere functioning and design better surface exchange models. Noting that FR and FA have different isotopic signatures, we evaluate the potential of isotopic 13CO2 measurements in the air (combined with CO2 flux and concentration measurements) to partition NEE into FR and FA on a routine basis. The study is conducted at a temperate coniferous forest where intensive isotopic measurements in air, soil, and biomass were performed in summer 1997. The multilayer soil-vegetation-atmosphere transfer model MuSICA is adapted to compute 13CO2 flux and concentration profiles. Using MuSICA as a "perfect" simulator and taking advantage of the very dense spatiotemporal resolution of the isotopic data set (341 flasks over a 24-hour period) enable us to test each hypothesis and estimate the performance of the method. The partitioning works better in midafternoon when isotopic disequilibrium is strong. With only 15 flasks, i.e., two 13CO2 nighttime profiles (to estimate the isotopic signature of FR) and five daytime measurements (to perform the partitioning) we get mean daily estimates of FR and FA that agree with the model within 15-20%. However, knowledge of the mesophyll conductance seems crucial and may be a limitation to the method.

  12. Nocturnal Light Pulses Lower Carbon Dioxide Production Rate without Affecting Feed Intake in Geese.

    Science.gov (United States)

    Huang, De-Jia; Yang, Shyi-Kuen

    2016-03-01

    This study was conducted to investigate the effect of nocturnal light pulses (NLPs) on the feed intake and metabolic rate in geese. Fourteen adult Chinese geese were penned individually, and randomly assigned to either the C (control) or NLP group. The C group was exposed to a 12L:12D photoperiod (12 h light and 12 h darkness per day), whereas the NLP group was exposed to a 12L:12D photoperiod inserted by 15-min lighting at 2-h intervals in the scotophase. The weight of the feed was automatically recorded at 1-min intervals for 1 wk. The fasting carbon dioxide production rate (CO2 PR) was recorded at 1-min intervals for 1 d. The results revealed that neither the daily feed intake nor the feed intakes during both the daytime and nighttime were affected by photoperiodic regimen, and the feed intake during the daytime did not differ from that during the nighttime. The photoperiodic treatment did not affect the time distribution of feed intake. However, NLPs lowered (p<0.05) the mean and minimal CO2 PR during both the daytime and nighttime. Both the mean and minimal CO2 PR during the daytime were significantly higher (p<0.05) than those during the nighttime. We concluded that NLPs lowered metabolic rate of the geese, but did not affect the feed intake; both the mean and minimal CO2 PR were higher during the daytime than during the nighttime. PMID:26950871

  13. Elevated carbon dioxide affects behavioural lateralization in a coral reef fish.

    Science.gov (United States)

    Domenici, Paolo; Allan, Bridie; McCormick, Mark I; Munday, Philip L

    2012-02-23

    Elevated carbon dioxide (CO(2)) has recently been shown to affect chemosensory and auditory behaviour, and activity levels of larval reef fishes, increasing their risk of predation. However, the mechanisms underlying these changes are unknown. Behavioural lateralization is an expression of brain functional asymmetries, and thus provides a unique test of the hypothesis that elevated CO(2) affects brain function in larval fishes. We tested the effect of near-future CO(2) concentrations (880 µatm) on behavioural lateralization in the reef fish, Neopomacentrus azysron. Individuals exposed to current-day or elevated CO(2) were observed in a detour test where they made repeated decisions about turning left or right. No preference for right or left turns was observed at the population level. However, individual control fish turned either left or right with greater frequency than expected by chance. Exposure to elevated-CO(2) disrupted individual lateralization, with values that were not different from a random expectation. These results provide compelling evidence that elevated CO(2) directly affects brain function in larval fishes. Given that lateralization enhances performance in a number of cognitive tasks and anti-predator behaviours, it is possible that a loss of lateralization could increase the vulnerability of larval fishes to predation in a future high-CO(2) ocean.

  14. Carbon pools and fluxes in a Tibetan alpine Kobresia pygmaea pasture partitioned by coupled eddy-covariance measurements and ¹³CO₂ pulse labeling.

    Science.gov (United States)

    Ingrisch, Johannes; Biermann, Tobias; Seeber, Elke; Leipold, Thomas; Li, Maoshan; Ma, Yaoming; Xu, Xingliang; Miehe, Georg; Guggenberger, Georg; Foken, Thomas; Kuzyakov, Yakov

    2015-02-01

    The Tibetan highlands host the largest alpine grassland ecosystems worldwide, bearing soils that store substantial stocks of carbon (C) that are very sensitive to land use changes. This study focuses on the cycling of photoassimilated C within a Kobresia pygmaea pasture, the dominating ecosystems on the Tibetan highlands. We investigated short-term effects of grazing cessation and the role of the characteristic Kobresia root turf on C fluxes and belowground C turnover. By combining eddy-covariance measurements with (13)CO₂ pulse labeling we applied a powerful new approach to measure absolute fluxes of assimilates within and between various pools of the plant-soil-atmosphere system. The roots and soil each store roughly 50% of the overall C in the system (76 Mg C ha(-1)), with only a minor contribution from shoots, which is also expressed in the root:shoot ratio of 90. During June and July the pasture acted as a weak C sink with a strong uptake of approximately 2 g C m(-2) d(-1) in the first half of July. The root turf was the main compartment for the turnover of photoassimilates, with a subset of highly dynamic roots (mean residence time 20 days), and plays a key role for the C cycling and C storage in this ecosystem. The short-term grazing cessation only affected aboveground biomass but not ecosystem scale C exchange or assimilate allocation into roots and soil. PMID:25461119

  15. Carbon and nitrogen dynamics in early stages of forest litter decomposition as affected by nitrogen addition

    Institute of Scientific and Technical Information of China (English)

    DENG Xiao-wen; LIU Ying; HAN Shi-jie

    2009-01-01

    The effects of nitrogen (N) availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh litter samples including needle litter (Pinus koraiensis) and two types of broadleaf litters (Quercus mongolica and Tilia amurensis) were collected from a broadleaf-korean pine mixed forest in the northern slope of Changbai Mountain (China). Different doses of N (equal to 0, 30 and 50 kg·ha-1yr-1, respectively, as NH4NO3) were added to litter during the experiment period. The litter decomposition rate expressed as mass loss and respiration rate increased significantly with increasing N availability. The mass loss and cumulative CO2-C emission were higher in leaf litter compared to that in needle litter. The dissolved organic Carbon (DOC) concentrations in litter leachate varied widely between the species, but were not greatly affected by N treatments. Regardless of the N addition rate, both N treatments and species had no significant effect on dissolved organic N (DON) concentrations in litter leachate. About 52·78% of added N was retained in the litter. The percentage of N retention was positively correlated (R2=0.91, p<0.05) with the litter mass loss. This suggested that a forest floor with easily decomposed litter might have higher potential N sink strength than that with more slowly decomposed litter.

  16. Severe dry winter affects plant phenology and carbon balance of a cork oak woodland understorey

    Science.gov (United States)

    Correia, A. C.; Costa-e-Silva, F.; Dubbert, M.; Piayda, A.; Pereira, J. S.

    2016-10-01

    Mediterranean climates are prone to a great variation in yearly precipitation. The effects on ecosystem will depend on the severity and timing of droughts. In this study we questioned how an extreme dry winter affects the carbon flux in the understorey of a cork oak woodland? What is the seasonal contribution of understorey vegetation to ecosystem productivity? We used closed-system portable chambers to measure CO2 exchange of the dominant shrub species (Cistus salviifolius, Cistus crispus and Ulex airensis), of the herbaceous layer and on bare soil in a cork oak woodland in central Portugal during the dry winter year of 2012. Shoot growth, leaf shedding, flower and fruit setting, above and belowground plant biomass were measured as well as seasonal leaf water potential. Eddy-covariance and micrometeorological data together with CO2 exchange measurements were used to access the understorey species contribution to ecosystem gross primary productivity (GPP). The herbaceous layer productivity was severely affected by the dry winter, with half of the yearly maximum aboveground biomass in comparison with the 6 years site average. The semi-deciduous and evergreen shrubs showed desynchronized phenophases and lagged carbon uptake maxima. Whereas shallow-root shrubs exhibited opportunistic characteristics in exploiting the understorey light and water resources, deep rooted shrubs showed better water status but considerably lower assimilation rates. The contribution of understorey vegetation to ecosystem GPP was lower during summer with 14% and maximum during late spring, concomitantly with the lowest tree productivity due to tree canopy renewal. The herbaceous vegetation contribution to ecosystem GPP never exceeded 6% during this dry year stressing its sensitivity to winter and spring precipitation. Although shrubs are more resilient to precipitation variability when compared with the herbaceous vegetation, the contribution of the understorey vegetation to ecosystem GPP can

  17. Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

    Directory of Open Access Journals (Sweden)

    Corina Dörfer

    Full Text Available The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA and continuous permafrost (site Wudaoliang, WUD. Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (1.6 g cm(-3 of mineral associated organic matter (MOM. The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1. Higher SOC contents (320 g kg(-1 were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1. Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA and 22% (WUD to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth account for 10.4 kg m(-2, compared to 3.4 kg m(-2 in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

  18. Land use affects the resistance and resilience of carbon dynamics of mountain grassland to extreme drought

    Science.gov (United States)

    Ingrisch, Johannes; Karlowsky, Stefan; Hasibeder, Roland; Anadon-Rosell, Alba; Augusti, Angela; Scheld, Sarah; König, Alexander; Gleixner, Gerd; Bahn, Michael

    2015-04-01

    Climatic extremes like droughts are expected to occur more frequently and to be more severe in a future climate and have been shown to strongly affect the carbon (C) cycle. Few studies have so far explored how the management intensity of ecosystems and land-use changes alter C cycle responses to extreme climatic events. In many mountain areas land-use changes have been taking place at a rapid pace and have altered plant species composition and biogeochemical cycles. It is still unknown whether and how abandonment of mountain grasslands affects the resistance and the resilience of carbon dynamics to extreme drought. We carried out an in situ experiment to test the hypothesis that abandonment increases the resistance of grassland C dynamics to extreme drought, but decreases its resilience (i.e. post-drought recovery). In a common garden experiment at a mountain meadow in the Austrian Central Alps we exposed large intact monoliths from the meadow and a nearby abandoned grassland to extreme drought conditions during the main growth period in late spring. We measured above- and belowground productivity and net ecosystem exchange and its components over the course of the drought and during the recovery to assess and quantify their resistance and resilience. Furthermore, we analysed the coupling of the two major ecosystem CO2 fluxes, photosynthesis and soil respiration, as based on 13CO2 pulse labelling campaigns at peak drought and during post-drought recovery using isotope laser spectroscopy. Four weeks of early season drought induced a strong decrease of aboveground biomass at the mountain meadow, whereas no effect was observed for the abandoned grassland. At peak drought gross primary productivity was reduced at both grasslands compared to the respective controls, but with a stronger decrease at the meadow (80%) compared to the abandoned grassland (60%). The same pattern was observed for ecosystem respiration. However, the effect was less pronounced compared to carbon

  19. The role of initial affective impressions in responses to educational communications: The case of carbon capture and sequestration (CCS)

    OpenAIRE

    Bruine de Bruin, W.; Wong-Parodi, G

    2014-01-01

    Emerging technologies promise potential benefits at a potential cost. Developers of educational communications aim to improve people's understanding and to facilitate public debate. However, even relatively uninformed recipients may have initial feelings that are difficult to change. We report that people's initial affective impressions about carbon capture and sequestration (CCS), a low-carbon coal-based electricity-generation technology with which most people are unfamiliar, influences how ...

  20. Thinning Invariant Partition Structures

    CERN Document Server

    Starr, Shannon

    2011-01-01

    A partition structure is a random point process on $[0,1]$ whose points sum to 1, almost surely. In the case that there are infinitely many points to begin with, we consider a thinning action by: first, removing points independently, such that each point survives with probability $p>0$; and, secondly, rescaling the remaining points by an overall factor to normalize the sum again to 1. We prove that the partition structures which are "thinning divisible" for a sequence of $p$'s converging to 0 are mixtures of the Poisson-Kingman partition structures. We also consider the property of being "thinning invariant" for all $p \\in (0,1)$.

  1. Improved model calculation of atmospheric CO2 increment in affecting carbon stock of tropical mangrove forest

    OpenAIRE

    Jana, Tapan Kumar; Ray, Raghab; Chowdhury, Chumki; Majumder, Natasha; Dutta, Manab Kumar; Mukhopadhyay, Sandip Kumar

    2013-01-01

    Because of the difficulties in setting up arrangements in the intertidal zone for free-air carbon dioxide enrichment experimentation, the responses to increasing atmospheric carbon dioxide in mangrove forests are poorly studied. This study applied box model to overcome this limitation, and the relative changes in present level of reservoirs organic carbon contents in response to the future increase of atmospheric carbon dioxide were examined in the Avicennia-dominated mangrove forest at the l...

  2. Factors affecting exposure to nicotine and carbon monoxide in adult cigarette smokers.

    Science.gov (United States)

    Muhammad-Kah, Raheema; Liang, Qiwei; Frost-Pineda, Kimberly; Mendes, Paul E; Roethig, Hans J; Sarkar, Mohamadi

    2011-10-01

    Exposure to cigarette smoke among smokers is highly variable. This variability has been attributed to differences in smoking behavior as measured by smoking topography, as well as other behavioral and subjective aspects of smoking. The objective of this study was to determine the factors affecting smoke exposure as estimated by biomarkers of exposure to nicotine and carbon monoxide (CO). In a multi-center cross-sectional study of 3585 adult smokers and 1077 adult nonsmokers, exposure to nicotine and CO was estimated by 24h urinary excretion of nicotine and five of its metabolites and by blood carboxyhemoglobin, respectively. Number of cigarettes smoked per day (CPD) was determined from cigarette butts returned. Puffing parameters were determined through a CreSS® micro device and a 182-item adult smoker questionnaire (ASQ) was administered. The relationship between exposure and demographic factors, smoking machine measured tar yield and CPD was examined in a statistical model (Model A). Topography parameters were added to this model (Model B) which was further expanded (Model C) by adding selected questions from the ASQ identified by a data reduction process. In all the models, CPD was the most important and highest ranking factor determining daily exposure. Other statistically significant factors were number of years smoked, questions related to morning smoking, topography and tar yield categories. In conclusion, the models investigated in this analysis, explain about 30-40% of variability in exposure to nicotine and CO.

  3. Study on laser welded heat-affected zone in new ultralow carbon bainitic steel

    Institute of Scientific and Technical Information of China (English)

    Lin Zhao; Wuzhu Chen; Xudong Zhang; Jiguo Shan

    2007-01-01

    800 MPa grade ultralow carbon bainitic (NULCB) steel is the recently developed new generation steel, which was produced by thermo mechanical controlled processing & relaxation-precipitation controlling transformation (TMCP&RPC) technique. The microstructure and the mechanical properties of the heat-affected zone (HAZ) in NULCB steel under laser welding conditions were investigated by using a Gleeble-1500 thermal simulator. The experimental results indicate that the simplex microstructure in the HAZ is granular bainite that consists of bainite-ferrite (BF) lath and M-A constituent when the cooling time from 800 to 500°C (t8/5) is 0.3-30 s, and the M-A constituent consists of twinned martensite and residual austenite. As t8/5 increases, the hardness and tensile strength of HAZ decreases, but they are higher than that of the base metal, indicating the absence of softened zone after laser welding. The impact toughness of HAZ increases at first and then decreases when tw increases. The impact energy of HAZ is much higher than that of the base metal when t8/5 is between 3 and 15 s. It indicates that excellent low temperature toughness can be obtained under appropriate laser welding conditions.

  4. Polymers as Reference Partitioning Phase: Polymer Calibration for an Analytically Operational Approach To Quantify Multimedia Phase Partitioning.

    Science.gov (United States)

    Gilbert, Dorothea; Witt, Gesine; Smedes, Foppe; Mayer, Philipp

    2016-06-01

    Polymers are increasingly applied for the enrichment of hydrophobic organic chemicals (HOCs) from various types of samples and media in many analytical partitioning-based measuring techniques. We propose using polymers as a reference partitioning phase and introduce polymer-polymer partitioning as the basis for a deeper insight into partitioning differences of HOCs between polymers, calibrating analytical methods, and consistency checking of existing and calculation of new partition coefficients. Polymer-polymer partition coefficients were determined for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) by equilibrating 13 silicones, including polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) in methanol-water solutions. Methanol as cosolvent ensured that all polymers reached equilibrium while its effect on the polymers' properties did not significantly affect silicone-silicone partition coefficients. However, we noticed minor cosolvent effects on determined polymer-polymer partition coefficients. Polymer-polymer partition coefficients near unity confirmed identical absorption capacities of several PDMS materials, whereas larger deviations from unity were indicated within the group of silicones and between silicones and LDPE. Uncertainty in polymer volume due to imprecise coating thickness or the presence of fillers was identified as the source of error for partition coefficients. New polymer-based (LDPE-lipid, PDMS-air) and multimedia partition coefficients (lipid-water, air-water) were calculated by applying the new concept of a polymer as reference partitioning phase and by using polymer-polymer partition coefficients as conversion factors. The present study encourages the use of polymer-polymer partition coefficients, recognizing that polymers can serve as a linking third phase for a quantitative understanding of equilibrium partitioning of HOCs between any two phases. PMID:27115830

  5. Polymers as Reference Partitioning Phase: Polymer Calibration for an Analytically Operational Approach To Quantify Multimedia Phase Partitioning.

    Science.gov (United States)

    Gilbert, Dorothea; Witt, Gesine; Smedes, Foppe; Mayer, Philipp

    2016-06-01

    Polymers are increasingly applied for the enrichment of hydrophobic organic chemicals (HOCs) from various types of samples and media in many analytical partitioning-based measuring techniques. We propose using polymers as a reference partitioning phase and introduce polymer-polymer partitioning as the basis for a deeper insight into partitioning differences of HOCs between polymers, calibrating analytical methods, and consistency checking of existing and calculation of new partition coefficients. Polymer-polymer partition coefficients were determined for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) by equilibrating 13 silicones, including polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) in methanol-water solutions. Methanol as cosolvent ensured that all polymers reached equilibrium while its effect on the polymers' properties did not significantly affect silicone-silicone partition coefficients. However, we noticed minor cosolvent effects on determined polymer-polymer partition coefficients. Polymer-polymer partition coefficients near unity confirmed identical absorption capacities of several PDMS materials, whereas larger deviations from unity were indicated within the group of silicones and between silicones and LDPE. Uncertainty in polymer volume due to imprecise coating thickness or the presence of fillers was identified as the source of error for partition coefficients. New polymer-based (LDPE-lipid, PDMS-air) and multimedia partition coefficients (lipid-water, air-water) were calculated by applying the new concept of a polymer as reference partitioning phase and by using polymer-polymer partition coefficients as conversion factors. The present study encourages the use of polymer-polymer partition coefficients, recognizing that polymers can serve as a linking third phase for a quantitative understanding of equilibrium partitioning of HOCs between any two phases.

  6. Bosonic Partition Functions

    CERN Document Server

    Kellerstein, M; Verbaarschot, J J M

    2016-01-01

    The behavior of quenched Dirac spectra of two-dimensional lattice QCD is consistent with spontaneous chiral symmetry breaking which is forbidden according to the Coleman-Mermin-Wagner theorem. One possible resolution of this paradox is that, because of the bosonic determinant in the partially quenched partition function, the conditions of this theorem are violated allowing for spontaneous symmetry breaking in two dimensions or less. This goes back to work by Niedermaier and Seiler on nonamenable symmetries of the hyperbolic spin chain and earlier work by two of the auhtors on bosonic partition functions at nonzero chemical potential. In this talk we discuss chiral symmetry breaking for the bosonic partition function of QCD at nonzero isospin chemical potential and a bosonic random matrix theory at imaginary chemical potential and compare the results with the fermionic counterpart. In both cases the chiral symmetry group of the bosonic partition function is noncompact.

  7. In Situ Study of CO2 and H2O Partitioning Between Na-Montmorillonite and Variably Wet Supercritical Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Loring, John S.; Ilton, Eugene S.; Chen, Jeffrey; Thompson, Christopher J.; Martin, Paul F.; Benezeth, Pascale; Rosso, Kevin M.; Felmy, Andrew R.; Schaef, Herbert T.

    2014-06-03

    Shale formations play fundamental roles in large-scale geologic carbon sequestration (GCS) aimed primarily to mitigate climate change, and in smaller-scale GCS targeted mainly for CO2-enhanced gas recovery operations. In both technologies, CO2 is injected underground as a supercritical fluid (scCO2), where interactions with shale minerals could influence successful GCS implementation. Reactive components of shales include expandable clays, such as montmorillonites and mixed-layer illite/smectite clays. In this work, we used in situ X-ray diffraction (XRD) and in situ infrared (IR) spectroscopy to investigate the swelling/shrinkage and water/CO2 sorption of a pure montmorillonite, Na-SWy-2, when the clay is exposed to variably hydrated scCO2 at 50 °C and 90 bar. Measured interlayer spacings and sorbed water concentrations at varying levels of scCO2 hydration are similar to previously reported values measured in air at ambient pressure over a range of relative humidities. IR spectra show evidence of both water and CO2 intercalation, and variations in peak shapes and positions suggest multiple sorbed types with distinct chemical environments. Based on the intensity of the asymmetric CO stretching band of the CO2 associated with the Na-SWy-2, we observed a significant increase in sorbed CO2 as the clay expands from a 0W to a 1W state, suggesting that water props open the interlayer so that CO2 can enter. However, as the clay transitions from a 1W to a 2W state, CO2 desorbs sharply. These observations were placed in the context of two conceptual models concerning hydration mechanisms for expandable clays and were also discussed in light of recent theoretical studies on CO2-H2O-clay interactions. The swelling/shrinkage of expandable clays could affect solid volume, porosity, and permeability of shales. Consequently, the results from this work could aid predictions of shale caprock integrity in large-scale GCS, as well as methane transmissivity in enhanced gas recovery

  8. Vertical partitioning and controlling factors of gradient-based soil carbon dioxide fluxes in two contrasted soil profiles along a loamy hillslope

    Science.gov (United States)

    Wiaux, F.; Vanclooster, M.; Van Oost, K.

    2015-08-01

    In this study we aim to elucidate the role of physical conditions and gas transfer mechanism along soil profiles in the decomposition and storage of soil organic carbon (OC) in subsoil layers. We use a qualitative approach showing the temporal evolution and the vertical profile description of CO2 fluxes and abiotic variables. We assessed soil CO2 fluxes throughout two contrasted soil profiles (i.e. summit and footslope positions) along a hillslope in the central loess belt of Belgium. We measured the time series of soil temperature, soil moisture and CO2 concentration at different depths in the soil profiles for two periods of 6 months. We then calculated the CO2 flux at different depths using Fick's diffusion law and horizon specific diffusivity coefficients. The calculated fluxes allowed assessing the contribution of different soil layers to surface CO2 fluxes. We constrained the soil gas diffusivity coefficients using direct observations of soil surface CO2 fluxes from chamber-based measurements and obtained a good prediction power of soil surface CO2 fluxes with an R2 of 92 %. We observed that the temporal evolution of soil CO2 emissions at the summit position is mainly controlled by temperature. In contrast, at the footslope, we found that long periods of CO2 accumulation in the subsoil alternates with short peaks of important CO2 release. This was related to the high water filled pore space that limits the transfer of CO2 along the soil profile at this slope position. Furthermore, the results show that approximately 90 to 95 % of the surface CO2 fluxes originate from the first 10 cm of the soil profile at the footslope. This indicates that soil OC in this depositional context can be stabilized at depth, i.e. below 10 cm. This study highlights the need to consider soil physical properties and their dynamics when assessing and modeling soil CO2 emissions. Finally, changes in the physical environment of depositional soils (e.g. longer dry periods) may affect the

  9. Fire affects root decomposition, soil food web structure, and carbon flow in tallgrass prairie

    Science.gov (United States)

    Shaw, E. Ashley; Denef, Karolien; Milano de Tomasel, Cecilia; Cotrufo, M. Francesca; Wall, Diana H.

    2016-05-01

    Root litter decomposition is a major component of carbon (C) cycling in grasslands, where it provides energy and nutrients for soil microbes and fauna. This is especially important in grasslands where fire is common and removes aboveground litter accumulation. In this study, we investigated whether fire affects root decomposition and C flow through the belowground food web. In a greenhouse experiment, we applied 13C-enriched big bluestem (Andropogon gerardii) root litter to intact tallgrass prairie soil cores collected from annually burned (AB) and infrequently burned (IB) treatments at the Konza Prairie Long Term Ecological Research (LTER) site. Incorporation of 13C into microbial phospholipid fatty acids and nematode trophic groups was measured on six occasions during a 180-day decomposition study to determine how C was translocated through the soil food web. Results showed significantly different soil communities between treatments and higher microbial abundance for IB. Root decomposition occurred rapidly and was significantly greater for AB. Microbes and their nematode consumers immediately assimilated root litter C in both treatments. Root litter C was preferentially incorporated in a few groups of microbes and nematodes, but depended on burn treatment: fungi, Gram-negative bacteria, Gram-positive bacteria, and fungivore nematodes for AB and only omnivore nematodes for IB. The overall microbial pool of root-litter-derived C significantly increased over time but was not significantly different between burn treatments. The nematode pool of root-litter-derived C also significantly increased over time, and was significantly higher for the AB treatment at 35 and 90 days after litter addition. In conclusion, the C flow from root litter to microbes to nematodes is not only measurable but also significant, indicating that higher nematode trophic levels are critical components of C flow during root decomposition, which, in turn, is significantly affected by fire. Not

  10. Burning management in the tallgrass prairie affects root decomposition, soil food web structure and carbon flow

    Science.gov (United States)

    Shaw, E. A.; Denef, K.; Milano de Tomasel, C.; Cotrufo, M. F.; Wall, D. H.

    2015-09-01

    Root litter decomposition is a major component of carbon (C) cycling in grasslands, where it provides energy and nutrients for soil microbes and fauna. This is especially important in grasslands where fire is a common management practice and removes aboveground litter accumulation. In this study, we investigated whether fire affects root decomposition and C flow through the belowground food web. In a greenhouse experiment, we applied 13C-enriched big bluestem (Andropogon gerardii) root litter to intact tallgrass prairie soil cores collected from annually burned (AB) and infrequently burned (IB) treatments at the Konza Prairie Long Term Ecological Research (LTER) site. Incorporation of 13C into microbial phospholipid fatty acids and nematode trophic groups was measured on six occasions during a 180-day decomposition study to determine how C was translocated through the soil food web. Results showed significantly different soil communities between treatments and higher microbial abundance for IB. Root decomposition occurred rapidly and was significantly greater for AB. Microbes and their nematode consumers immediately assimilated root litter C in both treatments. Root litter C was preferentially incorporated in a few groups of microbes and nematodes, but depended on burn treatment: fungi, Gram-negative bacteria, Gram-positive bacteria, and fungivore nematodes for AB and only omnivore nematodes for IB. The overall microbial pool of root litter-derived C significantly increased over time but was not significantly different between burn treatments. The nematode pool of root litter-derived C also significantly increased over time, and was significantly higher for the AB treatment at 35 and 90 days after litter addition. In conclusion, the C flow from root litter to microbes to nematodes is not only measurable, but significant, indicating that higher nematode trophic levels are critical components of C flow during root decomposition which, in turn, is significantly

  11. Poisson-Kingman partitions

    OpenAIRE

    Pitman, Jim

    2002-01-01

    This paper presents some general formulas for random partitions of a finite set derived by Kingman's model of random sampling from an interval partition generated by subintervals whose lengths are the points of a Poisson point process. These lengths can be also interpreted as the jumps of a subordinator, that is an increasing process with stationary independent increments. Examples include the two-parameter family of Poisson-Dirichlet models derived from the Poisson process of jumps of a stab...

  12. Partitioning of biocides between water and inorganic phases of render

    DEFF Research Database (Denmark)

    Urbanczyk, Michal; Bollmann, Ulla E.; Bester, Kai

    , and tebuconazole towards minerals were studied. A mixture of biocides listed above was used to estimate partitioning constants between water and five different minerals, commonly used as fillers in renders: barite, calcium carbonate, kaolinite, mica and talc. The resulting Kd values for all minerals analysed were...... compared. The partitioning constants for calcium carbonate varied between 0.1 (isoproturon) and 1.1 (iodocarb) and 84.6 (dichlorooctylisothiazolinone), respectively. The results for barite, kaolinite and mica were in a similar range and usually the compounds with high partitioning constants for one mineral...

  13. HENRY'S LAW CONSTANTS AND MICELLAR PARTITIONING OF VOLATILE ORGANIC COMPOUNDS IN SURFACTANT SOLUTIONS

    Science.gov (United States)

    Partitioning of volatile organic compounds (VOCs) into surfactant micelles affects the apparent vapor-liquid equilibrium of VOCs in surfactant solutions. This partitioning will complicate removal of VOCs from surfactant solutions by standard separation processes. Headspace expe...

  14. Integrating spot short-term measurements of carbon emissions and backward dietary energy partition calculations to estimate intake in lactating dairy cows fed ad libitum or restricted.

    Science.gov (United States)

    Pereira, A B D; Utsumi, S A; Dorich, C D; Brito, A F

    2015-12-01

    The objective of this study was to use spot short-term measurements of CH4 (QCH4) and CO2 (QCO2) integrated with backward dietary energy partition calculations to estimate dry matter intake (DMI) in lactating dairy cows. Twelve multiparous cows averaging 173±37d in milk and 4 primiparous cows averaging 179±27d in milk were blocked by days in milk, parity, and DMI (as a percentage of body weight) and, within each block, randomly assigned to 1 of 2 treatments: ad libitum intake (AL) or restricted intake (RI=90% DMI) according to a crossover design. Each experimental period lasted 22d with 14d for treatments adaptation and 8d for data and sample collection. Diets contained (dry matter basis): 40% corn silage, 12% grass-legume haylage, and 48% concentrate. Spot short-term gas measurements were taken in 5-min sampling periods from 15 cows (1 cow refused sampling) using a portable, automated, open-circuit gas quantification system (GreenFeed, C-Lock Inc., Rapid City, SD) with intervals of 12h between the 2daily samples. Sampling points were advanced 2h from a day to the next to yield 16 gas samples per cow over 8d to account for diurnal variation in QCH4 and QCO2. The following equations were used sequentially to estimate DMI: (1) heat production (MJ/d)=(4.96 + 16.07 ÷ respiratory quotient) × QCO2; respiratory quotient=0.95; (2) metabolizable energy intake (MJ/d)=(heat production + milk energy) ± tissue energy balance; (3) digestible energy (DE) intake (MJ/d)=metabolizable energy + CH4 energy + urinary energy; (4) gross energy (GE) intake (MJ/d)=DE + [(DE ÷ in vitro true dry matter digestibility) - DE]; and (5) DMI (kg/d)=GE intake estimated ÷ diet GE concentration. Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) and Fit Model procedure in JMP (α=0.05; SAS Institute Inc.). Cows significantly differed in DMI measured (23.8 vs. 22.4kg/d for AL and RI, respectively). Dry matter intake estimated using QCH4 and QCO2 coupled with

  15. Genome-scale modeling of light-driven reductant partitioning and carbon fluxes in diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142.

    Science.gov (United States)

    Vu, Trang T; Stolyar, Sergey M; Pinchuk, Grigoriy E; Hill, Eric A; Kucek, Leo A; Brown, Roslyn N; Lipton, Mary S; Osterman, Andrei; Fredrickson, Jim K; Konopka, Allan E; Beliaev, Alexander S; Reed, Jennifer L

    2012-01-01

    Genome-scale metabolic models have proven useful for answering fundamental questions about metabolic capabilities of a variety of microorganisms, as well as informing their metabolic engineering. However, only a few models are available for oxygenic photosynthetic microorganisms, particularly in cyanobacteria in which photosynthetic and respiratory electron transport chains (ETC) share components. We addressed the complexity of cyanobacterial ETC by developing a genome-scale model for the diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142. The resulting metabolic reconstruction, iCce806, consists of 806 genes associated with 667 metabolic reactions and includes a detailed representation of the ETC and a biomass equation based on experimental measurements. Both computational and experimental approaches were used to investigate light-driven metabolism in Cyanothece sp. ATCC 51142, with a particular focus on reductant production and partitioning within the ETC. The simulation results suggest that growth and metabolic flux distributions are substantially impacted by the relative amounts of light going into the individual photosystems. When growth is limited by the flux through photosystem I, terminal respiratory oxidases are predicted to be an important mechanism for removing excess reductant. Similarly, under photosystem II flux limitation, excess electron carriers must be removed via cyclic electron transport. Furthermore, in silico calculations were in good quantitative agreement with the measured growth rates whereas predictions of reaction usage were qualitatively consistent with protein and mRNA expression data, which we used to further improve the resolution of intracellular flux values.

  16. The role of snow cover and soil freeze/thaw cycles affecting boreal-arctic soil carbon dynamics

    Directory of Open Access Journals (Sweden)

    Y. Yi

    2015-07-01

    Full Text Available Northern Hemisphere permafrost affected land areas contain about twice as much carbon as the global atmosphere. This vast carbon pool is vulnerable to accelerated losses through mobilization and decomposition under projected global warming. Satellite data records spanning the past 3 decades indicate widespread reductions (∼ 0.8–1.3 days decade−1 in the mean annual snow cover extent and frozen season duration across the pan-Arctic domain, coincident with regional climate warming trends. How the soil carbon pool responds to these changes will have a large impact on regional and global climate. Here, we developed a coupled terrestrial carbon and hydrology model framework with detailed 1-D soil heat transfer representation to investigate the sensitivity of soil organic carbon stocks and soil decomposition to changes in snow cover and soil freeze/thaw processes in the Pan-Arctic region over the past three decades (1982–2010. Our results indicate widespread soil active layer deepening across the pan-Arctic, with a mean decadal trend of 6.6 ± 12.0 (SD cm, corresponding with widespread warming and lengthening non-frozen season. Warming promotes vegetation growth and soil heterotrophic respiration, particularly within surface soil layers (≤ 0.2 m. The model simulations also show that seasonal snow cover has a large impact on soil temperatures, whereby increases in snow cover promote deeper (≥ 0.5 m soil layer warming and soil respiration, while inhibiting soil decomposition from surface (≤ 0.2 m soil layers, especially in colder climate zones (mean annual T ≤ −10 °C. Our results demonstrate the important control of snow cover in affecting northern soil freeze/thaw and soil carbon decomposition processes, and the necessity of considering both warming, and changing precipitation and snow cover regimes in characterizing permafrost soil carbon dynamics.

  17. The Ecohydrological Consequences of Woody Plant Encroachment: How Accessibility to Deep Soil Water Resources Affects Ecosystem Carbon and Water Exchange

    Science.gov (United States)

    Scott, R. L.; Huxman, T. E.; Barron-Gafford, G.; Jenerette, D.; Young, J. M.

    2013-12-01

    Woody plant encroachment into grassland systems, a process that has increased rapidly over the last century, has potentially broad ecohydrological consequences by affecting the way ecosystems use water and cycle carbon. This study examines the influence of precipitation- and groundwater-derived water availability by comparing eddy covariance measurements of water vapor and carbon dioxide fluxes over a riparian grassland, shrubland, and woodland, and an upland grassland site in southeastern Arizona USA. Compared to the upland grassland, the riparian sites exhibited greater net carbon uptake (NEP) and higher evapotranspiration (ET) across a longer portion of the year. Among the riparian sites, however, the grassland was less able to take advantage of the stable groundwater supply. Increasing woody plant density facilitated greater water and carbon exchange that became increasingly decoupled from incident precipitation (P). How groundwater accessibility affected NEP was more complex than ET. Respiration (Reco) costs were higher for the riparian grassland so, while it had a similar ET and gross carbon uptake (GEP) to the shrubland, its NEP was substantially less. Also, riparian grassland fluxes were much more variable due to flooding that occurred at the site, which could stimulate or inhibit NEP. Woodland NEP was largest but surprisingly similar to the less mature and dense shrubland even while having much greater GEP. Woodland NEP responded negatively to P, due to the stimulation of Reco likely due to greater amounts of aboveground and soil carbon. With many areas of the world experiencing woody plants encroachment, encroachment into areas where there are additional deep soil water sources, such as in riparian settings or in areas of deep soil moisture recharge, will likely increase carbon sequestration but at the expense of higher water use.

  18. Land Use Affects Carbon Sources to the Pelagic Food Web in a Small Boreal Lake.

    Science.gov (United States)

    Rinta, Päivi; van Hardenbroek, Maarten; Jones, Roger I; Kankaala, Paula; Rey, Fabian; Szidat, Sönke; Wooller, Matthew J; Heiri, Oliver

    2016-01-01

    Small humic forest lakes often have high contributions of methane-derived carbon in their food webs but little is known about the temporal stability of this carbon pathway and how it responds to environmental changes on longer time scales. We reconstructed past variations in the contribution of methanogenic carbon in the pelagic food web of a small boreal lake in Finland by analyzing the stable carbon isotopic composition (δ13C values) of chitinous fossils of planktivorous invertebrates in sediments from the lake. The δ13C values of zooplankton remains show several marked shifts (approx. 10 ‰), consistent with changes in the proportional contribution of carbon from methane-oxidizing bacteria in zooplankton diets. The results indicate that the lake only recently (1950s) obtained its present state with a high contribution of methanogenic carbon to the pelagic food web. A comparison with historical and palaeobotanical evidence indicates that this most recent shift coincided with agricultural land-use changes and forestation of the lake catchment and implies that earlier shifts may also have been related to changes in forest and land use. Our study demonstrates the sensitivity of the carbon cycle in small forest lakes to external forcing and that the effects of past changes in local land use on lacustrine carbon cycling have to be taken into account when defining environmental and ecological reference conditions in boreal headwater lakes. PMID:27487044

  19. Affected zone generated around the erosion pit on carbon steel surface at the incipient stage of vibration cavitation

    Institute of Scientific and Technical Information of China (English)

    CHEN HaoSheng; LI Jiang; LIU ShiHan; CHEN DaRong; WANG JiaDao

    2008-01-01

    The characteristics of erosion pits on a carbon steel surface were investigated at the incipient stage of cavitation erosion. After a 5-minute experiment performed in an ultrasonic vibration system, needle-like erosion pits appeared on the polished steel surface, and a specially affected zone was formed around the pit. The shape of the pit and the plastic deformation of the affected zone indicate that the me-chanical impaction on the surface is the main reason for the cavitation damage. On the other hand, the iridescent color, the decreased surface hardness and the precipitated carbides on the affected zone prove that the affected zone has experienced a tempering process with the temperature higher than 300℃. The lack of oxygen in the affected zone also proves that it is not a chemical oxygen result. A special phenomenon that a carbon ring forms in the affected zone is explained as a result of the tor-oidal bubbles' heating effect at the final stage of the bubble collapse.

  20. Elevated pressure of carbon dioxide affects growth of thermophilic Petrotoga sp.

    Science.gov (United States)

    Rakoczy, Jana; Gniese, Claudia; Schippers, Axel; Schlömann, Michael; Krüger, Martin

    2014-05-01

    Carbon capture and storage (CCS) is considered a promising new technology which reduces carbon dioxide emissions into the atmosphere and thereby decelerates global warming. During CCS, carbon dioxide is captured from emission sources (e.g. fossil fuel power plants or other industries), pressurised, and finally stored in deep geological formations, such as former gas or oil reservoirs as well as saline aquifers. However, with CCS being a very young technology, there are a number of unknown factors that need to be investigated before declaring CCS as being safe. Our research investigates the effect of high carbon dioxide concentrations and pressures on an indigenous microorganism that colonises a potential storage site. Growth experiments were conducted using the thermophilic thiosulphate-reducing bacterium Petrotoga sp., isolated from formation water of the gas reservoir Schneeren (Lower Saxony, Germany), situated in the Northern German Plain. Growth (OD600) was monitored over one growth cycle (10 days) at different carbon dioxide concentrations (50%, 100%, and 150% in the gas phase), and was compared to control cultures grown with 20% carbon dioxide. An additional growth experiment was performed over a period of 145 days with repeated subcultivation steps in order to detect long-term effects of carbon dioxide. Cultivation over 10 days at 50% and 100% carbon dioxide slightly reduced cell growth. In contrast, long-term cultivation at 150% carbon dioxide reduced cell growth and finally led to cell death. This suggested a more pronounced effect of carbon dioxide at prolonged cultivation and stresses the need for a closer consideration of long-term effects. Experiments with supercritical carbon dioxide at 100 bar completely inhibited growth of freshly inoculated cultures and also caused a rapid decrease of growth of a pre-grown culture. This demonstrated that supercritical carbon dioxide had a sterilising effect on cells. This effect was not observed in control cultures

  1. Partition density functional theory

    Science.gov (United States)

    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.

  2. Response of oxidative enzyme activities to nitrogen deposition affects soil concentrations of dissolved organic carbon

    Science.gov (United States)

    Waldrop, M.P.; Zak, D.R.

    2006-01-01

    Recent evidence suggests that atmospheric nitrate (NO3- ) deposition can alter soil carbon (C) storage by directly affecting the activity of lignin-degrading soil fungi. In a laboratory experiment, we studied the direct influence of increasing soil NO 3- concentration on microbial C cycling in three different ecosystems: black oak-white oak (BOWO), sugar maple-red oak (SMRO), and sugar maple-basswood (SMBW). These ecosystems span a broad range of litter biochemistry and recalcitrance; the BOWO ecosystem contains the highest litter lignin content, SMRO had intermediate lignin content, and SMBW leaf litter has the lowest lignin content. We hypothesized that increasing soil solution NO 3- would reduce lignolytic activity in the BOWO ecosystem, due to a high abundance of white-rot fungi and lignin-rich leaf litter. Due to the low lignin content of litter in the SMBW, we further reasoned that the NO3- repression of lignolytic activity would be less dramatic due to a lower relative abundance of white-rot basidiomycetes; the response in the SMRO ecosystem should be intermediate. We increased soil solution NO3- concentrations in a 73-day laboratory incubation and measured microbial respiration and soil solution dissolved organic carbon (DOC) and phenolics concentrations. At the end of the incubation, we measured the activity of ??-glucosidase, N-acetyl-glucosaminidase, phenol oxidase, and peroxidase, which are extracellular enzymes involved with cellulose and lignin degradation. We quantified the fungal biomass, and we also used fungal ribosomal intergenic spacer analysis (RISA) to gain insight into fungal community composition. In the BOWO ecosystem, increasing NO 3- significantly decreased oxidative enzyme activities (-30% to -54%) and increased DOC (+32% upper limit) and phenolic (+77% upper limit) concentrations. In the SMRO ecosystem, we observed a significant decrease in phenol oxidase activity (-73% lower limit) and an increase in soluble phenolic concentrations

  3. PDF Weaving - Linking Inventory Data and Monte Carlo Uncertainty Analysis in the Study of how Disturbance Affects Forest Carbon Storage

    Science.gov (United States)

    Healey, S. P.; Patterson, P.; Garrard, C.

    2014-12-01

    Altered disturbance regimes are likely a primary mechanism by which a changing climate will affect storage of carbon in forested ecosystems. Accordingly, the National Forest System (NFS) has been mandated to assess the role of disturbance (harvests, fires, insects, etc.) on carbon storage in each of its planning units. We have developed a process which combines 1990-era maps of forest structure and composition with high-quality maps of subsequent disturbance type and magnitude to track the impact of disturbance on carbon storage. This process, called the Forest Carbon Management Framework (ForCaMF), uses the maps to apply empirically calibrated carbon dynamics built into a widely used management tool, the Forest Vegetation Simulator (FVS). While ForCaMF offers locally specific insights into the effect of historical or hypothetical disturbance trends on carbon storage, its dependence upon the interaction of several maps and a carbon model poses a complex challenge in terms of tracking uncertainty. Monte Carlo analysis is an attractive option for tracking the combined effects of error in several constituent inputs as they impact overall uncertainty. Monte Carlo methods iteratively simulate alternative values for each input and quantify how much outputs vary as a result. Variation of each input is controlled by a Probability Density Function (PDF). We introduce a technique called "PDF Weaving," which constructs PDFs that ensure that simulated uncertainty precisely aligns with uncertainty estimates that can be derived from inventory data. This hard link with inventory data (derived in this case from FIA - the US Forest Service Forest Inventory and Analysis program) both provides empirical calibration and establishes consistency with other types of assessments (e.g., habitat and water) for which NFS depends upon FIA data. Results from the NFS Northern Region will be used to illustrate PDF weaving and insights gained from ForCaMF about the role of disturbance in carbon

  4. Matrix string partition function

    CERN Document Server

    Kostov, Ivan K; Kostov, Ivan K.; Vanhove, Pierre

    1998-01-01

    We evaluate quasiclassically the Ramond partition function of Euclidean D=10 U(N) super Yang-Mills theory reduced to a two-dimensional torus. The result can be interpreted in terms of free strings wrapping the space-time torus, as expected from the point of view of Matrix string theory. We demonstrate that, when extrapolated to the ultraviolet limit (small area of the torus), the quasiclassical expressions reproduce exactly the recently obtained expression for the partition of the completely reduced SYM theory, including the overall numerical factor. This is an evidence that our quasiclassical calculation might be exact.

  5. Effect of partitioning procedure on microstructure and mechanical properties of a hot-rolled directly quenched and partitioned steel

    International Nuclear Information System (INIS)

    Hot-rolling direct quenching and partitioning (HDQP) processes distinguished by the dynamical partitioning procedures and the isothermal partitioning procedures were applied to a low-carbon steel to investigate the differences in the microstructure and the mechanical properties. Microstructures were characterized by means of EPMA, EBSD, TEM and XRD. Mechanical properties were measured by uniaxial tensile tests. Results show that the microstructures of the HDQP sheets are characterized by lath martensite and film-like inter-lath retained austenite. The dynamically partitioned sheets possess narrower martensite laths with higher dislocation densities, compared with the isothermally partitioned sheets. The martensite lath broadening, the dislocation density reduction and the carbide coarsening exist with decreased cooling rate or with prolonged partitioning time. The coarse carbides appearing in the sheet partitioned longer than 5 min promote the decomposition of austenite. X-ray diffraction (XRD) detection results of the specimens with different plastic strains indicate that the retained austenite with the carbon concentration below 1.5 wt% can perform a better transformation behavior with the plastic strain under 5%. The isothermal partitioning processes can improve the average concentration and homogeneity of carbon in the retained austenite but make up part of the retained austenite too stable. Mechanical property results show that the dynamically partitioned sheets possess higher strengths about 1500–1600 MPa and similar elongations about 14–16% with excellent products of strength and elongation (PSE) about 22,000–25,000 MPa%. It is concluded that a dynamical partitioning procedure is preferable for obtaining a HDQP steel with excellent mechanical properties

  6. Effect of partitioning procedure on microstructure and mechanical properties of a hot-rolled directly quenched and partitioned steel

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Xiaodong; Xu, Yunbo, E-mail: yunbo_xu@126.com; Yang, Xiaolong; Liu, Ziquan; Wu, Di

    2014-01-31

    Hot-rolling direct quenching and partitioning (HDQP) processes distinguished by the dynamical partitioning procedures and the isothermal partitioning procedures were applied to a low-carbon steel to investigate the differences in the microstructure and the mechanical properties. Microstructures were characterized by means of EPMA, EBSD, TEM and XRD. Mechanical properties were measured by uniaxial tensile tests. Results show that the microstructures of the HDQP sheets are characterized by lath martensite and film-like inter-lath retained austenite. The dynamically partitioned sheets possess narrower martensite laths with higher dislocation densities, compared with the isothermally partitioned sheets. The martensite lath broadening, the dislocation density reduction and the carbide coarsening exist with decreased cooling rate or with prolonged partitioning time. The coarse carbides appearing in the sheet partitioned longer than 5 min promote the decomposition of austenite. X-ray diffraction (XRD) detection results of the specimens with different plastic strains indicate that the retained austenite with the carbon concentration below 1.5 wt% can perform a better transformation behavior with the plastic strain under 5%. The isothermal partitioning processes can improve the average concentration and homogeneity of carbon in the retained austenite but make up part of the retained austenite too stable. Mechanical property results show that the dynamically partitioned sheets possess higher strengths about 1500–1600 MPa and similar elongations about 14–16% with excellent products of strength and elongation (PSE) about 22,000–25,000 MPa%. It is concluded that a dynamical partitioning procedure is preferable for obtaining a HDQP steel with excellent mechanical properties.

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

    OpenAIRE

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

    2015-01-01

    The release of organic compounds from roots is a key process influencing soil carbon (C) dynamics and nutrient availability in terrestrial ecosystems. Through this process, plants stimulate microbial activity and soil organic matter (SOM) mineralization thus releasing nitrogen (N) that sustains gross and net primary production (GPP and NPP, respectively). Root inputs also contribute to SOM formation. In this study, we quantified the annual net root-derived C input to soil (Net-Croot) across s...

  8. Bioanalytical effect-balance model to determine the bioavailability of organic contaminants in sediments affected by black and natural carbon.

    Science.gov (United States)

    Bräunig, Jennifer; Tang, Janet Y M; Warne, Michael St J; Escher, Beate I

    2016-08-01

    In sediments several binding phases dictate the fate and bioavailability of organic contaminants. Black carbon (BC) has a high sorptive capacity for organic contaminants and can limit their bioavailability, while the fraction bound to organic carbon (OC) is considered to be readily desorbable and bioavailable. We investigated the bioavailability and mixture toxicity of sediment-associated contaminants by combining different extraction techniques with in vitro bioanalytical tools. Sediments from a harbour with high fraction of BC, and sediments from remote, agricultural and urban areas with lower BC were treated with exhaustive solvent extraction, Tenax extraction and passive sampling to estimate total, bioaccessible and bioavailable fractions, respectively. The extracts were characterized with cell-based bioassays that measure dioxin-like activity (AhR-CAFLUX) and the adaptive stress response to oxidative stress (AREc32). Resulting bioanalytical equivalents, which are effect-scaled concentrations, were applied in an effect-balance model, consistent with a mass balance-partitioning model for single chemicals. Sediments containing BC had most of the bioactivity associated to the BC fraction, while the OC fraction played a role for sediments with lower BC. As effect-based sediment-water distribution ratios demonstrated, most of the bioactivity in the AhR-CAFLUX was attributable to hydrophobic chemicals while more hydrophilic chemicals activated AREc32, even though bioanalytical equivalents in the aqueous phase remained negligible. This approach can be used to understand the fate and effects of mixtures of diverse organic contaminants in sediments that would not be possible if single chemicals were targeted by chemical analysis; and make informed risk-based decisions concerning the management of contaminated sediments. PMID:27176940

  9. Carbon Availability Affects Diurnally Controlled Processes and Cell Morphology of Cyanothece 51142

    OpenAIRE

    Jana Stöckel; Elvitigala, Thanura R.; Michelle Liberton; Pakrasi, Himadri B.

    2013-01-01

    Cyanobacteria are oxygenic photoautotrophs notable for their ability to utilize atmospheric CO2 as the major source of carbon. The prospect of using cyanobacteria to convert solar energy and high concentrations of CO2 efficiently into biomass and renewable energy sources has sparked substantial interest in using flue gas from coal-burning power plants as a source of inorganic carbon. However, in order to guide further advances in this area, a better understanding of the metabolic changes that...

  10. How will conversion to organic cereal production affect carbon stocks in Swedish agricultural soils?

    OpenAIRE

    Andrén, Olof; Kätterer, Thomas; Kirchmann, Holger

    2008-01-01

    Soil carbon changes were modelled over 30 years with the focus on cereal crops, since leys are often managed similarly in organic and conventional agriculture. Other crops were not considered due to difficulties in large-scale cropping of oilseed rape and potatoes organically because of pest problems. Four scenarios were used: 0%, 8% (current), 20% and 100% organic cereal production. Conversion to organic cereal crop production was found to reduce the amount of carbon stored as organic matter...

  11. Generating Primes Using Partitions

    OpenAIRE

    Pittu, Ganesh Reddy

    2015-01-01

    This paper presents a new technique of generating large prime numbers using a smaller one by employing Goldbach partitions. Experiments are presented showing how this method produces candidate prime numbers that are subsequently tested using either Miller Rabin or AKS primality tests.

  12. Partitions with Initial Repetitions

    Institute of Scientific and Technical Information of China (English)

    George E. ANDREWS

    2009-01-01

    A variety of interesting connections with modular forms, mock theta functions and Rogers-Ramanujan type identities arise in consideration of partitions in which the smaller integers are repeated as summands more often than the larger summands. In particular, this concept leads to new interpre-tations of the Rogers-Selberg identities and Bailey's modulus 9 identities.

  13. Carbon Cycling in Alpine and Arctic watersheds affected by permafrost degradation: An insight from Sweden

    Science.gov (United States)

    Roehm, C. L.; Giesler, R.; Karlsson, J.

    2009-05-01

    Linking the processes and dynamics acting within and between terrestrial and aquatic ecosystems is crucial in order to understand the impacts of environmental change on the re-distribution and transformation of energy within watersheds. Nearly 1300 Pg of carbon are stored in permafrost soils in boreal and arctic ecosystems. Permafrost degradation can result in the loss of significant amounts of terrestrial carbon, both through the release to the atmosphere in the form of carbon dioxide and methane, or through export downstream to lakes and rivers. The fate and effects of this carbon in lake ecosystems is poorly understood. We investigated the capacity of lake bacteria to utilize carbon from different adjacent mire soils in a discontinuous permafrost region of northern Sweden. We, additionally, studied other lake ecosystems by using organic matter quality as a proxy for the state of permafrost degradation within the watershed. Finally, we propose simple predictive models for the bioavailability of soils to aquatic bacteria. Our study identified three distinctive time sensitive pools of bacterial respiration whose carbon availability varied according to chemical characteristics. Soil dissolved organic carbon (DOC) was rapidly consumed by lake bacteria with nearly 85% consumed within the first 24 hours. Bacterial production was higher in the soil bioassays and increased in a lag fashion relative to bacterial respiration, resulting in increasing bacterial growth efficiencies over time as a function of C pool and soil type. The mean DOC consumption by lake bacteria was 0.087 mg C L-1 d-1 and varied between 0.382 mg L-1 d-1 and 0.491 mg L-1 d-1 when supplied with terrestrial DOC. The lake water bacterial respiration could explain a varying degree of pCO2 saturation in lakes as a function of both carbon quality and course. Carbon quality and end members can be used as proxies for the degree of permafrost degradation within the watershed. The data clearly show that export

  14. Microstructural evolution and mechanical properties of heat affected zones for 9Cr2WVTa steels with different carbon contents

    International Nuclear Information System (INIS)

    Highlights: • The weldability of 9Cr2WVTa steel with different carbon contents was studied. • The HAZs of the 9Cr2WVTa steel include three characteristic regions. • Residual delta-ferrite significantly deteriorates the impact property of HAZs. • The twin martensite deteriorates the impact toughness as a whole. • The 9Cr2WVTa steel with 0.14–0.17 wt.% carbon content has good weldability. - Abstract: The microstructures and mechanical properties of heat affected zones (HAZs) by Gas Tungsten Arc Welding (GTAW) were studied for 9Cr2WVTa steels with carbon content varying from 0.07 wt.% to 0.25 wt.%. Enlarged HAZs samples with 8 mm to 10 mm wide uniform temperature zone were prepared by the thermal–mechanical physical simulator Gleeble 1500 based on the Finite Element Method (FEM) numerical simulation and experimental measurement for the welding thermal cycle process and weld profile. The microstructures were observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). In addition, the mechanical properties tests including micro-hardness test, tensile test and impact test were carried out to investigate the effects of the carbon content and the welding thermal cycle. The results show that the big blocky delta ferrite in 9Cr2WVTa steel with lower carbon content deteriorates the impact property. On the other hand, the quenched martensite, especially for the twin martensite in 9Cr2WVTa steel with higher carbon content, deteriorates the impact toughness as well. The weldability of 9Cr2WVTa steel can be improved by adjusting the carbon content between 0.14 wt.% and 0.17 wt.%

  15. Fabrication variables affecting the structure and properties of supported carbon molecular sieve membranes for hydrogen separation

    KAUST Repository

    Briceño, Kelly

    2012-10-01

    A high molecular weight polyimide (Matrimid) was used as a precursor for fabricating supported carbon molecular sieve membranes without crack formation at 550-700°C pyrolysis temperature. A one-step polymer (polyimide) coating method as precursor of carbon layer was used without needing a prior modification of a TiO 2 macroporous support. The following fabrication variables were optimized and studied to determine their effect on the carbon structure: polymeric solution concentration, solvent extraction, heating rate and pyrolysis temperature. Two techniques (Thermogravimetric analysis and Raman spectroscopy) were used to determine these effects on final carbon structure. Likewise, the effect of the support was also reported as an additional and important variable in the design of supported carbon membranes. Atomic force microscopy and differential scanning calorimetry quantified the degree of influence. Pure gas permeation tests were performed using CH 4, CO, CO 2 and H 2. The presence of a molecular sieving mechanism was confirmed after defects were plugged with PDMS solution at 12wt%. Gas selectivities higher than Knudsen theoretical values were reached with membranes obtained over 650°C, showing as best values 4.46, 4.70 and 10.62 for H 2/N 2, H 2/CO and H 2/CH 4 ratio, respectively. Permeance values were over 9.82×10 -9mol/(m 2Pas)during pure hydrogen permeation tests. © 2012 Elsevier B.V.

  16. Factors affecting stress assisted corrosion cracking of carbon steel under industrial boiler conditions

    Science.gov (United States)

    Yang, Dong

    Failure of carbon steel boiler tubes from waterside has been reported in the utility boilers and industrial boilers for a long time. In industrial boilers, most waterside tube cracks are found near heavy attachment welds on the outer surface and are typically blunt, with multiple bulbous features indicating a discontinuous growth. These types of tube failures are typically referred to as stress assisted corrosion (SAC). For recovery boilers in the pulp and paper industry, these failures are particularly important as any water leak inside the furnace can potentially lead to smelt-water explosion. Metal properties, environmental variables, and stress conditions are the major factors influencing SAC crack initation and propagation in carbon steel boiler tubes. Slow strain rate tests (SSRT) were conducted under boiler water conditions to study the effect of temperature, oxygen level, and stress conditions on crack initation and propagation on SA-210 carbon steel samples machined out of boiler tubes. Heat treatments were also performed to develop various grain size and carbon content on carbon steel samples, and SSRTs were conducted on these samples to examine the effect of microstructure features on SAC cracking. Mechanisms of SAC crack initation and propagation were proposed and validated based on interrupted slow strain tests (ISSRT). Water chemistry guidelines are provided to prevent SAC and fracture mechanics model is developed to predict SAC failure on industrial boiler tubes.

  17. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    Science.gov (United States)

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-06-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg‑1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  18. On partitions avoiding right crossings

    OpenAIRE

    Yan, Sherry H. F.; Xu, Yuexiao

    2011-01-01

    Recently, Chen et al. derived the generating function for partitions avoiding right nestings and posed the problem of finding the generating function for partitions avoiding right crossings. In this paper, we derive the generating function for partitions avoiding right crossings via an intermediate structure of partial matchings avoiding 2-right crossings and right nestings. We show that there is a bijection between partial matchings avoiding 2-right crossing and right nestings and partitions...

  19. [Carbon source metabolic diversity of soil microbial community under different climate types in the area affected by Wenchuan earthquake].

    Science.gov (United States)

    Zhang, Guang-Shuai; Lin, Yong-Ming; Ma, Rui-Feng; Deng, Hao-Jun; Du, Kun; Wu, Cheng-Zhen; Hong, Wei

    2015-02-01

    The MS8.0 Wenchuan earthquake in 2008 led to huge damage to land covers in northwest Sichuan, one of the critical fragile eco-regions in China which can be divided into Semi-arid dry hot climate zone (SDHC) and Subtropical humid monsoon climate zone (SHMC). Using the method of Bilog-ECO-microplate technique, this paper aimed to determine the functional diversity of soil microbial community in the earthquake-affected areas which can be divided into undamaged area (U), recover area (R) and damaged area without recovery (D) under different climate types, in order to provide scientific basis for ecological recovery. The results indicated that the average-well-color-development (AWCD) in undamaged area and recovery area showed SDHC > SHMC, which was contrary to the AWCD in the damaged area without recovery. The AWCD of damaged area without recovery was the lowest in both climate zones. The number of carbon source utilization types of soil microbial in SHMC zone was significantly higher than that in SDHC zone. The carbon source utilization types in both climate zones presented a trend of recover area > undamaged area > damaged area without recovery. The carbon source metabolic diversity characteristic of soil microbial community was significantly different in different climate zones. The diversity index and evenness index both showed a ranking of undamaged area > recover area > damaged area without recovery. In addition, the recovery area had the highest richness index. The soil microbial carbon sources metabolism characteristic was affected by soil nutrient, aboveground vegetation biomass and vegetation coverage to some extent. In conclusion, earthquake and its secondary disasters influenced the carbon source metabolic diversity characteristic of soil microbial community mainly through the change of aboveground vegetation and soil environmental factors. PMID:26031097

  20. Nitrogen and Carbon Cycling in a Grassland Community Ecosystem as Affected by Elevated Atmospheric CO2

    OpenAIRE

    Torbert, H.A.; Johnson, H. B.; H. W. Polley

    2012-01-01

    Increasing global atmospheric carbon dioxide (CO2) concentration has led to concerns regarding its potential effects on terrestrial ecosystems and the long-term storage of carbon (C) and nitrogen (N) in soil. This study examined responses to elevated CO2 in a grass ecosystem invaded with a leguminous shrub Acacia farnesiana (L.) Willd (Huisache). Seedlings of Acacia along with grass species were grown for 13 months at CO2 concentrations of 385 (ambient), 690, and 980 μmol mol−1. Elevated CO2 ...

  1. The impact of Carbonic Anhydrase on the partitioning of leaf and soil CO18O and COS gas exchange across scales

    Science.gov (United States)

    Wingate, L.; Wehr, R. A.; Commane, R.; Ogee, J.; Sauze, J.; Jones, S.; Launois, T.; Wohl, S.; Whelan, M.; Meredith, L. K.; Genty, B.; Gimeno, T.; Kesselmeier, J.; Bosc, A.; Cuntz, M.; Munger, J. W.; Nelson, D. D.; Saleska, S. R.; Wofsy, S. C.; Zahniser, M. S.

    2015-12-01

    Photosynthesis (GPP), the largest CO2 flux to the land surface, is currently estimated with considerable uncertainty at between 100-175 Pg C yr-1. More robust estimates of global GPP could be obtained from the atmospheric budgets of other valuable tracers, such as carbonyl sulfide (COS) or the oxygen isotopic composition (δ18O) of atmospheric CO2. However, quantifying GPP using these tracers hinges on a better understanding of how soil micro-organisms modify the atmospheric concentrations of CO18O and COS at large scales. In particular, understanding better the role and activity of the enzyme Carbonic Anhydrase (CA) in soil micro-organisms is critical. We present novel datasets and model simulations demonstrating the progress in the collection of multi-tracer field datasets and how a new generation of multi-tracer land surface models can provide valuable constraints on photosynthesis and respiration across scales.

  2. Factors affecting pH change in alkaline waste water treatment - II: Carbon dioxide production

    NARCIS (Netherlands)

    Lijklema, L.

    1971-01-01

    The carbon dioxide produced during biological oxidation of wastewater has a pronounced influence upon the pH that is attained in the activated sludge process. The quantity produced is proportional to the COD removed, its degree of oxidation and depends also on the oxidation level of the substrate. A

  3. Processes Affecting Carbon Fluxes of Grassland Ecosystems Under Elevated CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Owensby, C.E.; Ham, J.M.; Rice, C.W.; Knapp, A.K.

    1998-03-14

    Final report of a project which exposed native tallgrass prairie to twice-ambient atmospheric CO{sub 2}. Improved water use efficiency increased biomass production and increased soil organic matter. Twice ambient CO{sub 2} decreased canopy evapotranspiration by 22%, but, maintained an increased net carbon sequestration.

  4. Investigating the Fundamental Scientific Issues Affecting the Long-term Geologic Storage of Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Spangler, Lee [Montana State Univ., Bozeman, MT (United States); Cunningham, Alfred [Montana State Univ., Bozeman, MT (United States); Barnhart, Elliot [Montana State Univ., Bozeman, MT (United States); Lageson, David [Montana State Univ., Bozeman, MT (United States); Nall, Anita [Montana State Univ., Bozeman, MT (United States); Dobeck, Laura [Montana State Univ., Bozeman, MT (United States); Repasky, Kevin [Montana State Univ., Bozeman, MT (United States); Shaw, Joseph [Montana State Univ., Bozeman, MT (United States); Nugent, Paul [Montana State Univ., Bozeman, MT (United States); Johnson, Jennifer [Montana State Univ., Bozeman, MT (United States); Hogan, Justin [Montana State Univ., Bozeman, MT (United States); Codd, Sarah [Montana State Univ., Bozeman, MT (United States); Bray, Joshua [Montana State Univ., Bozeman, MT (United States); Prather, Cody [Montana State Univ., Bozeman, MT (United States); McGrail, B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Oldenburg, Curtis [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wagoner, Jeff [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pawar, Rajesh [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-12-19

    The Zero Emissions Research and Technology (ZERT) collaborative was formed to address basic science and engineering knowledge gaps relevant to geologic carbon sequestration. The original funding round of ZERT (ZERT I) identified and addressed many of these gaps. ZERT II has focused on specific science and technology areas identified in ZERT I that showed strong promise and needed greater effort to fully develop.

  5. How sea level rise affects sedimentation, plant growth, and carbon accumulation on coastal salt marshes

    Science.gov (United States)

    Mudd, S. M.; Howell, S. M.; Morris, J. T.

    2009-12-01

    The rate of accretion on coastal salt marshes depends on feedbacks between flow, macrophyte growth, and sedimentation. Under favourable conditions, marsh accretion rates will keep pace with the local rate of sea level rise. Marsh accretion is driven by both organic and inorganic sedimentation; mineral rich marshes will need less organic sedimentation to keep pace with sea level rise. Here we use a numerical model of marsh accretion, calibrated by sediment cores, to explore the relationship between sea level rise and carbon sequestration on salt marshes in the face of differing supplies of inorganic sediment. The model predicts that changes in carbon storage resulting from changing sediment supply or sea-level rise are strongly dependant on the background sediment supply: if inorganic sediment supply is reduced in an already sediment poor marsh the storage of organic carbon will increase to a far greater extent than in a sediment-rich marsh, provided that the rate of sea-level rise does not exceed a threshold. These results imply that altering sediment supply to estuaries (e.g., by damming upstream rivers or altering littoral sediment transport) could lead to significant changes in the carbon budgets of coastal salt marshes.

  6. Soil aggregation and the stabilization of organic carbon as affected by erosion and deposition

    NARCIS (Netherlands)

    X. Wang; E.L.H. Cammeraat; C. Cerli; K. Kalbitz

    2014-01-01

    The importance of soil aggregation in determining the dynamics of soil organic carbon (SOC) during erosion, transportation and deposition is poorly understood. Particularly, we do not know how aggregation contributes to the often-observed accumulation of SOC at depositional sites. Our objective was

  7. Activated carbon addition affects soil pH and germination of six plant species

    NARCIS (Netherlands)

    Kabouw, P.; Nab, M.R.; Van Dam, N.M.

    2010-01-01

    Activated carbon (AC) is widely used in ecological studies for neutralizing allelopathic compounds. However, it has been suggested that AC has direct effects on plants because it alters substrate parameters such as nutrient availability and pH. These side-effects of AC addition may interfere with al

  8. Activated carbon addition affects substrate pH and germination of six plant species

    NARCIS (Netherlands)

    Kabouw, P.; Nab, M.; Dam, van M.

    2010-01-01

    Activated carbon (AC) is widely used in ecological studies for neutralizing allelopathic compounds. However, it has been suggested that AC has direct effects on plants because it alters substrate parameters such as nutrient availability and pH. These side-effects of AC addition may interfere with al

  9. Salinity, dissolved organic carbon and water hardness affect peracetic acid (PAA) degradation in aqueous solutions

    DEFF Research Database (Denmark)

    Liu, Dibo; Steinberg, Christian E.W.; Straus, David L.;

    2014-01-01

    -degradation of three commercial products, Wofasteril® E400, Wofasteril® E250 and Wofasteril® Lspez, at a nominal concentration of 1 mg L−1 in relation to two levels of salinity, water hardness, or dissolved organic carbon (DOC). The results showed that salinity and DOC stimulate PAA-degradation, while water hardness...

  10. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    Science.gov (United States)

    Yang, X M; Drury, C F; Reynolds, W D; Yang, J Y

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg(-1) soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg(-1), but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

  11. Partitional clustering algorithms

    CERN Document Server

    2015-01-01

    This book summarizes the state-of-the-art in partitional clustering. Clustering, the unsupervised classification of patterns into groups, is one of the most important tasks in exploratory data analysis. Primary goals of clustering include gaining insight into, classifying, and compressing data. Clustering has a long and rich history that spans a variety of scientific disciplines including anthropology, biology, medicine, psychology, statistics, mathematics, engineering, and computer science. As a result, numerous clustering algorithms have been proposed since the early 1950s. Among these algorithms, partitional (nonhierarchical) ones have found many applications, especially in engineering and computer science. This book provides coverage of consensus clustering, constrained clustering, large scale and/or high dimensional clustering, cluster validity, cluster visualization, and applications of clustering. Examines clustering as it applies to large and/or high-dimensional data sets commonly encountered in reali...

  12. The Fibonacci partition triangles

    CERN Document Server

    Fahr, Philipp

    2011-01-01

    In two previous papers we have presented partition formulae for the Fibonacci numbers motivated by the appearance of the Fibonacci numbers in the representation theory of the 3-Kronecker quiver and its universal cover, the 3-regular tree. Here we show that the basic information can be rearranged in two triangles. They are quite similar to the Pascal triangle of the binomial coefficients, but in contrast to the additivity rule for the Pascal triangle, we now deal with additivity along hooks, or, equivalently, with additive functions for valued translation quivers. As for the Pascal triangle, we see that the numbers in these Fibonacci partition triangles are given by evaluating polynomials. We show that the two triangles can be obtained from each other by looking at differences of numbers, it is sufficient to take differences along arrows and knight's moves.

  13. Partitioning net ecosystem carbon exchange into net assimilation and respiration with canopy-scale isotopic measurements: An error propagation analysis with 13CO2 and CO18O data

    Science.gov (United States)

    OgéE, J.; Peylin, P.; Cuntz, M.; Bariac, T.; Brunet, Y.; Berbigier, P.; Richard, P.; Ciais, P.

    2004-06-01

    Stable CO2 isotope measurements are increasingly used to partition the net CO2 exchange between terrestrial ecosystems and the atmosphere in terms of nonfoliar respiration (FR) and net photosynthesis (FA) in order to better understand the variations of this exchange. However, the accuracy of the partitioning strongly depends on the isotopic disequilibrium between these two gross fluxes, and a rigorous estimation of the errors on FA and FR is needed. In this study, we account for and propagate uncertainties on all terms in the mass balance and isotopic mass balance equations for CO2 in order to get accurate estimates of the errors on FA and FR. We apply our method to a maritime pine forest in the southwest of France. Nighttime Keeling plots are used to estimate the 13C and 18O isotopic signature of FR (δR), and for both isotopes the a priori uncertainty associated with this term is estimated to be around 2‰ at our site. Using δ13C-CO2 and [CO2] measurements, we then show that the uncertainty on instantaneous values of FA and FR can be as large as 4 μmol m-2 s-1. Even if we could get more accurate estimates of the net CO2 flux, the isoflux, and the isotopic signatures of FA and FR, this uncertainty would not be significantly reduced because the isotopic disequilibrium between FA and FR is too small, around 2-3‰. With δ18O-CO2 and [CO2] measurements the uncertainty associated with the gross fluxes lies also around 4 μmol m-2 s-1 but could be dramatically reduced if we were able to get more accurate estimates of the CO18O isoflux and the associated discrimination during photosynthesis. This is because the isotopic disequilibrium between FA and FR is large, of the order of 12-17‰. The isotopic disequilibrium between FA and FR and the uncertainty on δR vary among ecosystems and over the year. Our approach should help to choose the best strategy to study the carbon budget of a given ecosystem using stable isotopes.

  14. BKP plane partitions

    Energy Technology Data Exchange (ETDEWEB)

    Foda, Omar; Wheeler, Michael [Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3010 (Australia)

    2007-01-15

    Using BKP neutral fermions, we derive a product expression for the generating function of volume-weighted plane partitions that satisfy two conditions. If we call a set of adjacent equal height-h columns, h > 0, an h-path, then 1. Every h-path can assume one of two possible colours. 2. There is a unique way to move along an h-path from any column to another.

  15. BKP plane partitions

    OpenAIRE

    Foda, O.; Wheeler, M.

    2006-01-01

    Using BKP neutral fermions, we derive a product expression for the generating function of volume-weighted plane partitions that satisfy two conditions. If we call a set of adjacent equal height-h columns, h > 0, an h-path, then 1. Every h-path can assume one of two possible colours. 2. There is a unique way to move along an h-path from any column to another.

  16. BKP plane partitions

    International Nuclear Information System (INIS)

    Using BKP neutral fermions, we derive a product expression for the generating function of volume-weighted plane partitions that satisfy two conditions. If we call a set of adjacent equal height-h columns, h > 0, an h-path, then 1. Every h-path can assume one of two possible colours. 2. There is a unique way to move along an h-path from any column to another

  17. Effect of localized nitrogen availability to soybean half-root systems on photosynthate partitioning to roots and nodules

    International Nuclear Information System (INIS)

    Soybean (Glycine max [L.] Merr. cv Davis) was grown in a split-root growth system designed to maintain control of the root atmosphere. Two experiments were conducted to examine how 80% Ar:20%, O2 (Ar:O2) and air (Air) atmospheres affected N assimilation (NH4NO3 and N2 fixation) and the partitioning of photosynthate to roots and nodules. Application of NH4NO3 to nonnodulated half-root systems enhanced root growth and root respiration at the site of application. A second experiment applied Ar:O2 or air to the two sides of nodulated soybean half-root systems for 11 days in the following combinations: (a) Air to both sides (Air/Air); (b) Air to one side, Ar:O2 to the other (Air/Ar:O2), and (c) Ar:O2 to both sides (Ar:O2/Ar:O2). Results indicated that dry matter and current photosynthate (14C) were selectively partitioned to nodules and roots where N2 was available. Both root and nodule growth on the Air side of Air/Ar:O2 plants was significantly greater than the Ar:O2 side. The relative partitioning of carbon and current photosynthate between roots and nodules on a half-root system was also affected by N2 availability. The Ar:O2 sides partitioned relatively more current photosynthate to roots (57%) than nodules (43%), while N2-fixing root systems partitioned 36 and 64% of the carbon to roots and nodules, respectively. The Ar:O2 atmosphere decreased root and nodule respiration by 80% and nitrogenase activity by 85% compared to half-root systems in Air while specific nitrogenase activity in Ar:O2 was 50% of nodules supplied Air. Results indicated that nitrogen assimilation, whether from N2 fixation or inorganic sources, had a localized effect on root development

  18. Latitudinal Variation in Carbon Storage Can Help Predict Changes in Swamps Affected by Global Warming

    Science.gov (United States)

    Middleton, Beth A.; McKee, Karen

    2004-01-01

    Plants may offer our best hope of removing greenhouse gases (gases that contribute to global warming) emitted to the atmosphere from the burning of fossil fuels. At the same time, global warming could change environments so that natural plant communities will either need to shift into cooler climate zones, or become extirpated (Prasad and Iverson, 1999; Crumpacker and others, 2001; Davis and Shaw, 2001). It is impossible to know the future, but studies combining field observation of production and modeling can help us make predictions about what may happen to these wetland communities in the future. Widespread wetland types such as baldcypress (Taxodium distichum) swamps in the southeastern portion of the United States could be especially good at carbon sequestration (amount of CO2 stored by forests) from the atmosphere. They have high levels of production and sometimes store undecomposed dead plant material in wet conditions with low oxygen, thus keeping gases stored that would otherwise be released into the atmosphere (fig. 1). To study the ability of baldcypress swamps to store carbon, our project has taken two approaches. The first analysis looked at published data to develop an idea (hypothesis) of how production levels change across a temperature gradient in the baldcypress region (published data study). The second study tested this idea by comparing production levels across a latitudinal range by using swamps in similar field conditions (ongoing carbon storage study). These studies will help us make predictions about the future ability of baldcypress swamps to store carbon in soil and plant biomass, as well as the ability of these forests to shift northward with global warming.

  19. Carbon capture and sequestration: how much does this uncertain option affect near-term policy choices?

    OpenAIRE

    Bosetti, Valentina; Gilotte, Laurent

    2006-01-01

    Policy makers as well as many economists recognize geological Carbon Capture and Sequestration (CCS) as a key option to avoid costly emission reduction. While an extreme perspective is to envision CCS as a magic bullet to solve the issue of climate change, the economics perspective is more balanced and see it as a part of a portfolio of mitigation actions. Besides, as any novel mitigation technology, CCS can be implemented with a twofold purpose; on one side it can substitute some other techn...

  20. Atmospheric Deposition of Organic Carbon in Pennsylvania as Affected by Climatic Factors

    Science.gov (United States)

    Iavorivska, L.; Boyer, E. W.; Grimm, J.; Fuentes, J. D.

    2014-12-01

    Organic matter which is usually expressed through measurements of dissolved organic carbon (DOC) is ubiquitous in atmospheric water. It plays an important role in cloud formation processes, and contributes to organic acidity of precipitation. Rain and snow deposited to the landscape is a source of nutrient enrichment to ecosystems and water bodies, and is especially important as an input of carbon in coastal regions. Since DOC is highly chemically reactive and bioavailable it influences rates of primary and secondary productivity in aquatic ecosystems. Despite the significance of DOC to many ecosystem processes, knowledge about its contributions to landscapes in precipitation remains limited. Here, we quantified the removal of DOC from the atmosphere via precipitation over space and time in order to assess the magnitude of wet deposition as a link between terrestrial and aquatic components of the carbon cycle. Further, we consider the predictability of organic matter in precipitation as a function of hydro-chemical and climatic variables. We measured DOC concentration and composition in storm events both sequentially (hourly during events) and seasonally (weekly over the year). Data on the chemical composition of precipitation, along with meteorological back-trajectory analyses help clarify how an interplay between emission sources, atmospheric transport and climatic conditions determine the abundance of rainwater DOC across Pennsylvania.

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

    Directory of Open Access Journals (Sweden)

    Alberti G

    2015-04-01

    Full Text Available The release of organic compounds from roots is a key process influencing soil carbon (C dynamics and nutrient availability in terrestrial ecosystems. Through this process, plants stimulate microbial activity and soil organic matter (SOM mineralization thus releasing nitrogen (N that sustains gross and net primary production (GPP and NPP, respectively. Root inputs also contribute to SOM formation. In this study, we quantified the annual net root-derived C input to soil (Net-Croot across six high fertility 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. Belowground C accumulation and GPP were inversely related to soil C:N, but not to climate or stand age. Soil C content and C:N were also related to soil texture. At these high fertility sites, biomass growth did not change with soil C:N; however, biomass growth-to-GPP ratio significantly increased with increasing soil C:N. This was true for both our six forest sites and for another 23 high fertility sites selected at a global scale. We suggest that, at high fertility sites, plant N demand interacts with soil C:N stoichiometry and microbial activity, resulting in higher allocation of C to above ground tree biomass with increasing soil C:N ratio. 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, thereby 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 low soil C:N promotes microbial C use efficiency and new SOM formation and stabilization on clay particles.

  2. Shifts in vegetation affect organic carbon quality in a coastal marsh along the Hudson River Estuary

    Science.gov (United States)

    Zhang, A. H.; Corbett, J. E.; Tfaily, M. M.; Martin, I.; Ho, L.; Sun, E.; Sevilla, L.; Vincent, S.; Newton, R.; Peteet, D. M.

    2015-12-01

    To better understand carbon storage in coastal salt marshes, samples were collected from Piermont Marsh, NY (40 ̊00' N, 73 ̊55'W) located within the Hudson River Estuary. Porewater from three different vegetation sites was analyzed to compare the quality of the dissolved organic carbon. Sites contained either native or invasive vegetation with variations in live plant root depth. Porewater was taken from 0-3m in 50cm intervals, and sites were dominated either by invasive Phragmites australis, native Eleocharis , or native mixed vegetation (Spartina patens, Scirpus, and Typha angustifolia). Sites dominated by invasive Phragmites australis were found to have lower dissolved organic carbon (DOC) concentrations, lower cDOM absorption values, and more labile organic carbon compounds. The molecular composition of the DOC was determined with Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR-MS). Labile DOC components were defined as proteins, carbohydrates, and amino sugars while recalcitrant DOC components were defined as lipids, unsaturated hydrocarbons, lignins, tannins, and condensed hydrocarbons. For the Phragmites, Eleocharis, and mixed vegetation sites, average DOC concentrations with depth were found to be 1.71 ± 1.06, 4.64 ± 1.73, and 4.62 ± 3.5 (mM), respectively and cDOM absorption values with depth were found to be 13.22 ± 4.81, 49.42 ± 10.8, and 35.74 ± 17.49 (m-1). Additionally, DOC concentrations increased with depth in the mixed vegetation and Eleocharis sites, but remained relatively constant in the Phragmites site. The percent of labile compounds in the surface samples were found to be 19.02, 14.64, and 14.07% for the Phragmites, Eleocharis, and mixed vegetation sites, respectively. These findings suggest that sites dominated by Phragmites may have more reactive DOC substrates than sites dominated by native vegetation. These results indicate that the carbon storage in marshes invaded by Phragmites would be expected to decrease over time.

  3. Temporal dynamics of groundwater-dissolved inorganic carbon beneath a drought-affected braided stream: Platte River case study

    Science.gov (United States)

    Boerner, Audrey R.; Gates, John B.

    2015-05-01

    Impacts of environmental changes on groundwater carbon cycling are poorly understood despite their potentially high relevance to terrestrial carbon budgets. This study focuses on streambed groundwater chemistry during a period of drought-induced river drying and consequent disconnection between surface water and groundwater. Shallow groundwater underlying vegetated and bare portions of a braided streambed in the Platte River (Nebraska, USA) was monitored during drought conditions in summer 2012. Water temperature and dissolved inorganic carbon (dominated by HCO3-) in streambed groundwater were correlated over a 3 month period coinciding with a decline in river discharge from 35 to 0 m3 s-1. Physical, chemical, and isotopic parameters were monitored to investigate mechanisms affecting the HCO3- trend. Equilibrium thermodynamic modeling suggests that an increase of pCO2 near the water table, coupled with carbonate mineral weathering, can explain the trend. Stronger temporal trends in Ca2+ and Mg2+ compared to Cl- are consistent with carbonate mineral reequilibria rather than evaporative concentration as the primary mechanism of the increased HCO3-. Stable isotope trends are not apparent, providing further evidence of thermodynamic controls rather than evaporation from the water table. A combination of increased temperature and O2 in the dewatered portion of the streambed is the most likely driver of increased pCO2 near the water table. Results of this study highlight potential linkages between surface environmental changes and groundwater chemistry and underscore the need for high-resolution chemical monitoring of alluvial groundwater in order to identify environmental change impacts.

  4. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

    Directory of Open Access Journals (Sweden)

    Yan X Ow

    Full Text Available Under future ocean acidification (OA, increased availability of dissolved inorganic carbon (DIC in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2, and three light treatments (35, 100, 380 μmol m(-2 s(-1 for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3- use inhibitors (carbonic anhydrase inhibitor, acetazolamide and TRIS buffer (pH 8.0. We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax and efficiency (α more in C. serrulata grown under lower light levels (36-60% increase than for those in high light (4% increase. However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA.

  5. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

    Science.gov (United States)

    Ow, Yan X; Uthicke, Sven; Collier, Catherine J

    2016-01-01

    Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m(-2) s(-1)) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36-60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA. PMID:26938454

  6. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

    Science.gov (United States)

    Ow, Yan X; Uthicke, Sven; Collier, Catherine J

    2016-01-01

    Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m(-2) s(-1)) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36-60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA.

  7. Oceanic acidification affects marine carbon pump and triggers extended marine oxygen holes.

    Science.gov (United States)

    Hofmann, Matthias; Schellnhuber, Hans-Joachim

    2009-03-01

    Rising atmospheric CO(2) levels will not only drive future global mean temperatures toward values unprecedented during the whole Quaternary but will also lead to massive acidification of sea water. This constitutes by itself an anthropogenic planetary-scale perturbation that could significantly modify oceanic biogeochemical fluxes and severely damage marine biota. As a step toward the quantification of such potential impacts, we present here a simulation-model-based assessment of the respective consequences of a business-as-usual fossil-fuel-burning scenario where a total of 4,075 Petagrams of carbon is released into the atmosphere during the current millennium. In our scenario, the atmospheric pCO(2) level peaks at approximately 1,750 microatm in the year 2200 while the sea-surface pH value drops by >0.7 units on global average, inhibiting the growth of marine calcifying organisms. The study focuses on quantifying 3 major concomitant effects. The first one is a significant (climate-stabilizing) negative feedback on rising pCO(2) levels as caused by the attenuation of biogenic calcification. The second one is related to the biological carbon pump. Because mineral ballast, notably CaCO(3), is found to play a dominant role in carrying organic matter through the water column, a reduction of its export fluxes weakens the strength of the biological carbon pump. There is, however, a third effect with severe consequences: Because organic matter is oxidized in shallow waters when mineral-ballast fluxes weaken, oxygen holes (hypoxic zones) start to expand considerably in the oceans in our model world--with potentially harmful impacts on a variety of marine ecosystems. PMID:19218455

  8. STUDY ON THE FACTORS AFFECTING REDUCTION CAPACITIES OF ACTIVATED CARBON FIBERS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The reduction adsorption of silver diamminonitrate on different kinds of activated carbonfibers (ACF) has been studied in this paper. The effect of different parameters, including adsorptiontemperature, concentrations of activation agents, and activation time on the silver adsorptioncapacities of activated carbon fibers has been investigated The results show that higher temperaturein which the silver complex interacts with ACF. or higher concentration of activation agent, will makehigher reduction adsorption capacities of ACFs. More over, ACFs activated with phosphoric acidhave higher reduction capacities than those activated with zinc chloride or steam.

  9. Nitrogen and Carbon Cycling in a Grassland Community Ecosystem as Affected by Elevated Atmospheric CO2

    Directory of Open Access Journals (Sweden)

    H. A. Torbert

    2012-01-01

    Full Text Available Increasing global atmospheric carbon dioxide (CO2 concentration has led to concerns regarding its potential effects on terrestrial ecosystems and the long-term storage of carbon (C and nitrogen (N in soil. This study examined responses to elevated CO2 in a grass ecosystem invaded with a leguminous shrub Acacia farnesiana (L. Willd (Huisache. Seedlings of Acacia along with grass species were grown for 13 months at CO2 concentrations of 385 (ambient, 690, and 980 μmol mol−1. Elevated CO2 increased both C and N inputs from plant growth which would result in higher soil C from litter fall, root turnover, and excretions. Results from the incubation indicated an initial (20 days decrease in N mineralization which resulted in no change in C mineralization. However, after 40 and 60 days, an increase in both C and N mineralization was observed. These increases would indicate that increases in soil C storage may not occur in grass ecosystems that are invaded with Acacia over the long term.

  10. Partitioning Uncertain Workflows

    CERN Document Server

    Huberman, Bernardo A

    2015-01-01

    It is common practice to partition complex workflows into separate channels in order to speed up their completion times. When this is done within a distributed environment, unavoidable fluctuations make individual realizations depart from the expected average gains. We present a method for breaking any complex workflow into several workloads in such a way that once their outputs are joined, their full completion takes less time and exhibit smaller variance than when running in only one channel. We demonstrate the effectiveness of this method in two different scenarios; the optimization of a convex function and the transmission of a large computer file over the Internet.

  11. Lipid metabolism and nutrient partitioning strategies.

    Science.gov (United States)

    Morris, A M; Calsbeek, D J; Eckel, R H

    2004-10-01

    The increasing prevalence of overweight and obesity worldwide is daunting and requires prompt attention by the affected, health care profession, government and the pharmaceutical industry. Because overweight/obesity are defined as an excess of adipose tissue mass, all approaches in prevention and treatment must consider redirecting lipid storage in adipose tissue to oxidative metabolism. Lipid partitioning is a complex process that involves interaction between fat and other macronutrients, particularly carbohydrate. In an isocaloric environment, when fat is stored carbohydrate is oxidized and vice versa. Processes that influence fat partitioning in a manner in which weight is maintained must be modified by changes in organ-specific fat transport and metabolism. When therapy is considered, however, changes in lipid partitioning alone will be ineffective unless a negative energy balance is also achieved, i.e. energy expenditure exceeds energy intake. The intent of this review is to focus on molecules including hormones, enzymes, cytokines, membrane transport proteins, and transcription factors directly involved in fat trafficking and partitioning that could be potential drug targets. Some examples of favorably altering body composition by systemic and/or tissue specific modification of these molecules have already been provided with gene knockout and/or transgenic approaches in mice. The translation of this science to humans remains a challenging task. PMID:15544448

  12. Fertilization Affects Biomass Production of Suaeda salsa and Soil Organic Carbon Pool in East Coastal Region of China

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-feng; YANG Jing-song; YAO Rong-jiang; LIU Guang-ming; YU Shi-peng

    2013-01-01

    Land use practice significantly affects soil properties. Soil is a major sink for atmospheric carbon, and soil organic carbon (SOC) is considered as an essential indicator of soil quality. The objective of this study was to assess the effects of N and P applied to Suaeda salsa on biomass production, SOC concentration, labile organic carbon (LOC) concentration, SOC pool and carbon management index (CMI) as well as the effect of the land use practice on soil quality of coastal tidal lands in east coastal region of China. The study provided relevant references for coastal exploitation, tidal land management and related study in other countries and regions. The field experiment was laid out in a randomized complete block design, consisting of four N-fertilization rates (0 (N0), 60 (N1), 120 (N2) and 180 kg ha-1 (N3)), three P-fertilization rates (0 (P0), 70 (P1) and 105 kg ha-1 (P2)) and bare land without vegetation. N and P applied to S. salsa on coastal tidal lands significantly affected biomass production (above-ground biomass and roots), bulk density (ρb), available N and P, SOC, LOC, SOC pool and CMI. Using statistical analysis, significantly interactions in N and P were observed for biomass production and the dominant factor for S. salsa production was N in continuous 2-yr experiments. There were no significant interactions between N and P for SOC concentration, LOC concentration and SOC pool. However, significant interaction was obtained for CMI at the 0-20 cm depth and N played a dominant role in the variation of CMI. There were significant improvements for soil measured attributes and parameters, which suggested that increasing the rates of N and P significantly decreasedρb at the 0-20 cm depth and increased available N and P, SOC, LOC, SOC pool as well as CMI at both the 0-20 and 20-40 cm depth, respectively. By correlation analysis, there were significantly positive correlations between biomass (above-ground biomass and roots) and SOC as well as LOC in

  13. Decreased carbon limitation of litter respiration in a mortality-affected piñon–juniper woodland

    Directory of Open Access Journals (Sweden)

    E. Berryman

    2013-03-01

    Full Text Available Microbial respiration depends on microclimatic variables and carbon (C substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon–juniper ecosystems in southwestern North America, may affect C substrate availability in several ways, for example, via litterfall pulses and loss of root exudation. To determine piñon mortality effects on C and water limitation of microbial respiration, we applied field amendments (sucrose and water to two piñon–juniper sites in central New Mexico, USA: one with a recent (2 flux on the girdled site and a non-significant increase on the control. We speculate that the reduction may have been driven by water-induced carbonate dissolution, which serves as a sink for CO2 and would reduce the net flux. Widespread piñon mortality may decrease labile C limitation of litter respiration, at least during the first growing season following mortality.

  14. Partition of polycyclic aromatic hydrocarbons on organobentonites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A series of organobentonites synthesized by exchanging organiccation 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 Foundation item: 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 2.621x105, 2.106x105, 2.247x104,5.085x104, 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 lgKoc and 1gkow, 1gKoc and 1gS for PAHs in the system of water

  15. Do microorganism stoichiometric alterations affect carbon sequestration in paddy soil subjected to phosphorus input?

    Science.gov (United States)

    Zhang, ZhiJian; Li, HongYi; Hu, Jiao; Li, Xia; He, Qiang; Tian, GuangMing; Wang, Hang; Wang, ShunYao; Wang, Bei

    2015-04-01

    Ecological stoichiometry provides a powerful tool for integrating microbial biomass stoichiometry with ecosystem processes, opening far-reaching possibilities for linking microbial dynamics to soil carbon (C) metabolism in response to agricultural nutrient management. Despite its importance to crop yield, the role of phosphorus (P) with respect to ecological stoichiometry and soil C sequestration in paddy fields remains poorly understood, which limits our ability to predict nutrient-related soil C cycling. Here, we collected soil samples from a paddy field experiment after seven years of superphosphate application along a gradient of 0, 30, 60, and 90 (P-0 through P-90, respectively) kg.ha-1.yr-1 in order to evaluate the role of exogenous P on soil C sequestration through regulating microbial stoichiometry. P fertilization increased soil total organic C and labile organic C by 1-14% and 4-96%, respectively, while rice yield is a function of the activities of soil β-1,4-glucosidase (BG), acid phosphatase (AP), and the level of available soil P through a stepwise linear regression model. P input induced C limitation, as reflected by decreases in the ratios of C:P in soil and microbial biomass. An eco-enzymatic ratio indicating microbial investment in C vs. P acquisition, i.e., ln(BG): ln(AP), changed the ecological function of microbial C acquisition, and was stoichiometrically related to P input. This mechanism drove a shift in soil resource availability by increasing bacterial community richness and diversity, and stimulated soil C sequestration in the paddy field by enhancing C-degradation-related bacteria for the breakdown of plant-derived carbon sources. Therefore, the decline in the C:P stoichiometric ratio of soil microorganism biomass under P input was beneficial for soil C sequestration, which offered a "win-win" relationship for the maximum balance point between C sequestration and P availability for rice production in the face of climate change. PMID

  16. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow.

    Directory of Open Access Journals (Sweden)

    Shu Liao

    Full Text Available Dissolved organic carbon (DOC and total dissolved nitrogen (TDN are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage and the growing season (early and late. After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes.

  17. Factors affecting carbon-14 activity of unsaturated zone CO2 and implications for groundwater dating

    Science.gov (United States)

    Wood, Cameron; Cook, Peter G.; Harrington, Glenn A.; Meredith, Karina; Kipfer, Rolf

    2014-11-01

    Unsaturated zone processes may influence the carbon-14 (14C) activity of infiltrating groundwater and thus introduce error in derived groundwater residence times. However unsaturated zone 14C activities are rarely measured and there is little understanding of how they may vary spatially in a groundwater basin. In this study we measured 14C activity in unsaturated zone gas at five sites with different watertable depths (8.2-31.5 m) in the arid Ti Tree Basin, central Australia. We observed a relatively uniform decrease in 14C activity of unsaturated zone gas with depth at most sites, with variation in unsaturated zone depths leading to variation in 14C activities directly above the watertable at each site (ranging from 54 to 106 percent Modern Carbon (pMC)). Through modelling we show that the profiles are influenced by CO2 production at different depths from sources with different isotopic ratios, including production of ‘modern' CO2 in the root zone and production of ‘old' CO2 above the watertable. Scenario modelling showed that these processes are independent of recharge when recharge is low (0-10 mm y-1) but that higher recharge rates (>100 mm y-1) result in more advective transport of atmospheric CO2 to the watertable. The variation in 14C above the watertable was more sensitive to watertable depth and shallow and deep CO2 production rates. These findings offer insight into how unsaturated zone 14C activities may vary spatially and provide guidance as to when 14C depletion in unsaturated zone CO2 may become important for groundwater dating, particularly in arid settings.

  18. How Seasonal Drought Affect Carbon and Water Fluxes of Alternative Energy Crops in the US?

    Science.gov (United States)

    Joo, E.; Hussain, M. Z.; Zeri, M.; Masters, M.; Gomez-Casanovas, N.; DeLucia, E. H.; Bernacchi, C.

    2014-12-01

    The cellulosic biomass of Switchgrass (Panicum virgatum L.), Miscanthus (Miscanthus giganteus) and native prairie are considered candidate second-generation biofuels, potentially resulting in partial replacement annual row crops within the Midwestern US. There is an increasing focus to study the environmental impact of agricultural crops, however not much is known on the influence on the energy, carbon and water cycles of energy crops, especially under drought conditions. This study compares the impact of drought episodes (in 2011 and 2012) on evapotranspiration (ET), net ecosystem productivity (NEP) and water use efficiency (WUE; equals to NEP/ET) for Switchgrass (SW), Miscanthus (MXG), Maize (MZ) and native prairie (NP) grown in Central Illinois using the eddy covariance technique. Due to the prolonged drought and the rapid growth development with increasing ET of MXG in 2012, large water deficit (precipitation-ET) was observed for each species up to the highest deficit of -360 mm for this species. The gross primary production (GPP) of MZ was radically decreased by the drought in 2011 and 2012, while SW and NP were not influenced. MXG increased NEP throughout the typically wet and drought years, mainly due to the decrease in respiration and by the largest GPP upon the drought in 2012. Despite having the largest water deficit, MXG showed an enhanced WUE of 12.8 and 11.4 Kg C ha-1mm-1 in 2011 and 2012, respectively, in comparison to years typical to the region with WUE of 3.7-7.3 Kg C ha-1mm-1. Other species did not show a significant enhancement of WUE. Therefore we conclude that out of the studied species, MXG has more access to water, and uses this water the most efficiently to store carbon, under drought conditions.

  19. On Partitions of Goldbach's Conjecture

    OpenAIRE

    Woon, Max S. C.

    2000-01-01

    An approximate formula for the partitions of Goldbach's Conjecture is derived using Prime Number Theorem and a heuristic probabilistic approach. A strong form of Goldbach's conjecture follows in the form of a lower bounding function for the partitions of Goldbach's conjecture. Numerical computations suggest that the lower and upper bounding functions for the partitions satisfy a simple functional equation. Assuming that this invariant scaling property holds for all even integer $n$, the lower...

  20. Soluble organic carbon and pH of organic amendments affect metal mobility and chemical speciation in mine soils.

    Science.gov (United States)

    Pérez-Esteban, Javier; Escolástico, Consuelo; Masaguer, Alberto; Vargas, Carmen; Moliner, Ana

    2014-05-01

    We evaluated the effects of pH and soluble organic carbon affected by organic amendments on metal mobility to find out the optimal conditions for their application in the stabilization of metals in mine soils. Soil samples (pH 5.5-6.2) were mixed with 0, 30 and 60 th a(-1) of sheep-horse manure (pH 9.4) and pine bark compost (pH 5.7). A single-step extraction procedure was performed using 0.005 M CaCl2 adjusted to pH 4.0-7.0 and metal speciation in soil solution was simulated using NICA-Donnan model. Sheep-horse manure reduced exchangeable metal concentrations (up to 71% Cu, 75% Zn) due to its high pH and degree of maturity, whereas pine bark increased them (32% Cu, 33% Zn). However, at increasing dose and hence pH, sheep-horse manure increased soluble Cu because of higher soluble organic carbon, whereas soluble Cu and organic carbon increased at increasing dose and correspondingly decreasing pH in pine bark and non-amended treatments. Near the native pH of these soils (at pH 5.8-6.3), with small doses of amendments, there was minimum soluble Cu and organic carbon. Pine bark also increased Zn solubility, whereas sheep-horse manure reduced it as soluble Zn always decreased with increasing pH. Sheep-horse manure also reduced the proportion of free metals in soil solution (from 41% to 4% Cu, from 97% to 94% Zn), which are considered to be more bioavailable than organic species. Sheep-horse manure amendment could be efficiently used for the stabilization of metals with low risk of leaching to groundwater at low doses and at relatively low pH, such as the native pH of mine soils.

  1. Partitioning of PAHs in pore water from mangrove wetlands in Shantou, China.

    Science.gov (United States)

    Cao, Qi min; Wang, Hua; Qin, Jian qiao; Chen, Gui zhu; Zhang, Yong bei

    2015-01-01

    To investigate the trend of selected polycyclic aromatic hydrocarbons (PAHs) partitioning, fifteen pore water samples collected from the sediments of three mangrove wetlands were analyzed, and the partition coefficients and the partition model for the PAHs were determined by the correlation between K(oc) and octanol-water partition coefficient (K(ow)). The results revealed that the mean Kp values in inner mangrove wetlands were between 143 and 1031 L /Kg; the particulate organic carbon (POC) could strongly adsorb low-ring PAHs; the PAHs partitioning was on a obvious trend transported to particle phase. We suggest that the classic equilibrium model of organic carbon normalized (K(p)=K(oc)f(oc)) may be used to predict the trend of the selected PAHs partitioning. PMID:25450913

  2. Development of partitioning method

    International Nuclear Information System (INIS)

    A partitioning method has been developed under the concepts of separating radioactive nuclides from a high-level waste according to their half lives and radioactive toxicity, and of disposing the waste safely. The partitioning test using about 18 liters (--220Ci) of the fuel reprocessing waste prepared at PNC has been started in October of 1982. In this test the behavior of radioactive nuclides was made clear. The present paper describes chemical behavior of non-radioactive elements contained in the high-level liquid waste in the extraction with di-isodecyl phosphoric acid (DIDPA). Distribution ratios of most of metal ions for DIDPA were less than 0.05, except that those of Mo, Zr and Fe were higher than 7. Ferric ion could not be back-extracted with 4 M HNO3, but with 0.5 M (COOH)2. In the extractiion with DIDPA, the third phase, which causes closing the settling banks or the flow paths in a mixer settler, was formed when the ferric ion concentration was over 0.02 M. This unfavorable phenomenon, however, was found to be suppressed by diluting the ferric ion concentration to lower than 0.01 M or by reducing ferric ion to ferrous ion. (author)

  3. The overexpression of the pine transcription factor PpDof5 in Arabidopsis leads to increased lignin content and affects carbon and nitrogen metabolism.

    Science.gov (United States)

    Rueda-López, Marina; Cañas, Rafael A; Canales, Javier; Cánovas, Francisco M; Ávila, Concepción

    2015-12-01

    PpDof 5 is a regulator of the expression of glutamine synthetase (GS; EC 6.3.1.2) genes in photosynthetic and non-photosynthetic tissues of maritime pine. We have used Arabidopsis thaliana as a model system to study PpDof 5 function in planta, generating transgenic lines overexpressing the pine transcription factor. The overexpression of PpDof 5 resulted in a substantial increase of lignin content with a simultaneous regulation of carbon and nitrogen key genes. In addition, partitioning in carbon and nitrogen compounds was spread via various secondary metabolic pathways. These results suggest pleiotropic effects of PpDof 5 expression on various metabolic pathways of carbon and nitrogen metabolism. Plants overexpressing PpDof 5 exhibited upregulation of genes encoding enzymes for sucrose and starch biosynthesis, with a parallel increase in the content of soluble sugars. When the plants were grown under nitrate as the sole nitrogen source, they exhibited a significant regulation of the expression of genes involved mainly in signaling, but similar growth rates to wild-type plants. However, plants grown under ammonium exhibited major induction of the expression of photosynthetic genes and differential expression of ammonium and nitrate transporters. All these data suggest that in addition to controlling ammonium assimilation, PpDof 5 could be also involved in the regulation of other pathways in carbon and nitrogen metabolism in pine trees. PMID:26333592

  4. Climate, soil texture, and soil types affect the contributions of fine-fraction-stabilized carbon to total soil organic carbon in different land uses across China.

    Science.gov (United States)

    Cai, Andong; Feng, Wenting; Zhang, Wenju; Xu, Minggang

    2016-05-01

    Mineral-associated organic carbon (MOC), that is stabilized by fine soil particles (i.e., silt plus clay, organic carbon (SOC) persistence and sequestration, due to its large contribution to total SOC (TSOC) and long turnover time. Our objectives were to investigate how climate, soil type, soil texture, and agricultural managements affect MOC contributions to TSOC in China. We created a dataset from 103 published papers, including 1106 data points pairing MOC and TSOC across three major land use types: cropland, grassland, and forest. Overall, the MOC/TSOC ratio ranged from 0.27 to 0.80 and varied significantly among soil groups in cropland, grassland, and forest. Croplands and forest exhibited significantly higher median MOC/TSOC ratios than in grassland. Moreover, forest and grassland soils in temperate regions had higher MOC/TSOC ratios than in subtropical regions. Furthermore, the MOC/TSOC ratio was much higher in ultisol, compared with the other soil types. Both the MOC content and MOC/TSOC ratio were positively correlated with the amount of fine fraction (silt plus clay) in soil, highlighting the importance of soil texture in stabilizing organic carbon across various climate zones. In cropland, different fertilization practices and land uses (e.g., upland, paddy, and upland-paddy rotation) significantly altered MOC/TSOC ratios, but not in cropping systems (e.g., mono- and double-cropping) characterized by climatic differences. This study demonstrates that the MOC/TSOC ratio is mainly driven by soil texture, soil types, and related climate and land uses, and thus the variations in MOC/TSOC ratios should be taken into account when quantitatively estimating soil C sequestration potential of silt plus clay particles on a large scale. PMID:26905446

  5. Climate, soil texture, and soil types affect the contributions of fine-fraction-stabilized carbon to total soil organic carbon in different land uses across China.

    Science.gov (United States)

    Cai, Andong; Feng, Wenting; Zhang, Wenju; Xu, Minggang

    2016-05-01

    Mineral-associated organic carbon (MOC), that is stabilized by fine soil particles (i.e., silt plus clay, organic carbon (SOC) persistence and sequestration, due to its large contribution to total SOC (TSOC) and long turnover time. Our objectives were to investigate how climate, soil type, soil texture, and agricultural managements affect MOC contributions to TSOC in China. We created a dataset from 103 published papers, including 1106 data points pairing MOC and TSOC across three major land use types: cropland, grassland, and forest. Overall, the MOC/TSOC ratio ranged from 0.27 to 0.80 and varied significantly among soil groups in cropland, grassland, and forest. Croplands and forest exhibited significantly higher median MOC/TSOC ratios than in grassland. Moreover, forest and grassland soils in temperate regions had higher MOC/TSOC ratios than in subtropical regions. Furthermore, the MOC/TSOC ratio was much higher in ultisol, compared with the other soil types. Both the MOC content and MOC/TSOC ratio were positively correlated with the amount of fine fraction (silt plus clay) in soil, highlighting the importance of soil texture in stabilizing organic carbon across various climate zones. In cropland, different fertilization practices and land uses (e.g., upland, paddy, and upland-paddy rotation) significantly altered MOC/TSOC ratios, but not in cropping systems (e.g., mono- and double-cropping) characterized by climatic differences. This study demonstrates that the MOC/TSOC ratio is mainly driven by soil texture, soil types, and related climate and land uses, and thus the variations in MOC/TSOC ratios should be taken into account when quantitatively estimating soil C sequestration potential of silt plus clay particles on a large scale.

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

    Science.gov (United States)

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

    2014-07-01

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

  7. Coated or doped carbon nanotube network sensors as affected by environmental parameters

    Science.gov (United States)

    Li, Jing (Inventor)

    2011-01-01

    Methods for using modified single wall carbon nanotubes ("SWCNTs") to detect presence and/or concentration of a gas component, such as a halogen (e.g., Cl.sub.2), hydrogen halides (e.g., HCl), a hydrocarbon (e.g., C.sub.nH.sub.2n+2), an alcohol, an aldehyde or a ketone, to which an unmodified SWCNT is substantially non-reactive. In a first embodiment, a connected network of SWCNTs is coated with a selected polymer, such as chlorosulfonated polyethylene, hydroxypropyl cellulose, polystyrene and/or polyvinylalcohol, and change in an electrical parameter or response value (e.g., conductance, current, voltage difference or resistance) of the coated versus uncoated SWCNT networks is analyzed. In a second embodiment, the network is doped with a transition element, such as Pd, Pt, Rh, Ir, Ru, Os and/or Au, and change in an electrical parameter value is again analyzed. The parameter change value depends monotonically, not necessarily linearly, upon concentration of the gas component. Two general algorithms are presented for estimating concentration value(s), or upper or lower concentration bounds on such values, from measured differences of response values.

  8. Socioeconomic Factors Affecting Farmers’ Awareness of Clean Development Mechanism Projects: Case of Smallholder Forest Carbon Projects

    Directory of Open Access Journals (Sweden)

    Oscar I. Ayuya

    2011-05-01

    Full Text Available The objective of the study was to identify the socio-economic and institutional factors which influence the level of awareness of Clean Development Mechanism (CDM projects and in so doing to highlight the policy implications for the stakeholders when designing clean development mechanism projects among smallholder farmers. Findings shows that 23% of the farmers were correctly aware of the project and the results of the ordered logit model indicate that age, gender, education level, group membership, existence of tree farming and contact with extension services was found to influence awareness level of smallholder forest Carbon projects. To assist the community to adapt to climate change and produce sufficiently on a sustainable basis and achieve the desired food security under climate change challenges, the study recommends policies to increase awareness of such agro-environmental initiatives and that of extension providers should distinguish their clientele anchored on vital demographic characteristics such as age and gender. If the probability of younger farmers to be aware this initiative is higher, extension communications should be directed to such age group, particularly during initial stages project information dissemination.

  9. Black carbon absorption at the global scale is affected by particle-scale diversity in composition

    Science.gov (United States)

    Fierce, Laura; Bond, Tami C.; Bauer, Susanne E.; Mena, Francisco; Riemer, Nicole

    2016-09-01

    Atmospheric black carbon (BC) exerts a strong, but uncertain, warming effect on the climate. BC that is coated with non-absorbing material absorbs more strongly than the same amount of BC in an uncoated particle, but the magnitude of this absorption enhancement (Eabs) is not well constrained. Modelling studies and laboratory measurements have found stronger absorption enhancement than has been observed in the atmosphere. Here, using a particle-resolved aerosol model to simulate diverse BC populations, we show that absorption is overestimated by as much as a factor of two if diversity is neglected and population-averaged composition is assumed across all BC-containing particles. If, instead, composition diversity is resolved, we find Eabs=1-1.5 at low relative humidity, consistent with ambient observations. This study offers not only an explanation for the discrepancy between modelled and observed absorption enhancement, but also demonstrates how particle-scale simulations can be used to develop relationships for global-scale models.

  10. Biochar affects carbon composition and stability in soil: a combined spectroscopy-microscopy study

    Science.gov (United States)

    Hernandez-Soriano, Maria C.; Kerré, Bart; Kopittke, Peter M.; Horemans, Benjamin; Smolders, Erik

    2016-04-01

    The use of biochar can contribute to carbon (C) storage in soil. Upon addition of biochar, there is a spatial reorganization of C within soil particles, but the mechanisms remain unclear. Here, we used Fourier transformed infrared-microscopy and confocal laser scanning microscopy to examine this reorganization. A silty-loam soil was amended with three different organic residues and with the biochar produced from these residues and incubated for 237 d. Soil respiration was lower in biochar-amended soils than in residue-amended soils. Fluorescence analysis of the dissolved organic matter revealed that biochar application increased a humic-like fluorescent component, likely associated with biochar-C in solution. The combined spectroscopy-microscopy approach revealed the accumulation of aromatic-C in discrete spots in the solid-phase of microaggregates and its co-localization with clay minerals for soil amended with raw residue or biochar.The co-localization of aromatic-C:polysaccharides-C was consistently reduced upon biochar application. We conclude that reduced C metabolism is an important mechanism for C stabilization in biochar-amended soils.

  11. The microbe-mediated mechanisms affecting topsoil carbon stock in Tibetan grasslands.

    Science.gov (United States)

    Yue, Haowei; Wang, Mengmeng; Wang, Shiping; Gilbert, Jack A; Sun, Xin; Wu, Linwei; Lin, Qiaoyan; Hu, Yigang; Li, Xiangzhen; He, Zhili; Zhou, Jizhong; Yang, Yunfeng

    2015-09-01

    Warming has been shown to cause soil carbon (C) loss in northern grasslands owing to accelerated microbial decomposition that offsets increased grass productivity. Yet, a multi-decadal survey indicated that the surface soil C stock in Tibetan alpine grasslands remained relatively stable. To investigate this inconsistency, we analyzed the feedback responses of soil microbial communities to simulated warming by soil transplant in Tibetan grasslands. Whereas microbial functional diversity decreased in response to warming, microbial community structure did not correlate with changes in temperature. The relative abundance of catabolic genes associated with nitrogen (N) and C cycling decreased with warming, most notably in genes encoding enzymes associated with more recalcitrant C substrates. By contrast, genes associated with C fixation increased in relative abundance. The relative abundance of genes associated with urease, glutamate dehydrogenase and ammonia monoxygenase (ureC, gdh and amoA) were significantly correlated with N2O efflux. These results suggest that unlike arid/semiarid grasslands, Tibetan grasslands maintain negative feedback mechanisms that preserve terrestrial C and N pools. To examine whether these trends were applicable to the whole plateau, we included these measurements in a model and verified that topsoil C stocks remained relatively stable. Thus, by establishing linkages between microbial metabolic potential and soil biogeochemical processes, we conclude that long-term C loss in Tibetan grasslands is ameliorated by a reduction in microbial decomposition of recalcitrant C substrates. PMID:25689025

  12. Nutrient omission in Bt cotton affects soil organic carbon and nutrients status

    Science.gov (United States)

    Aladakatti, Y. R.; Biradar, D. P.; Satyanarayana, T.; Majumdar, K.; Shivamurthy, D.

    2012-04-01

    Studies carried out at the University of Agricultural Sciences, Dharwad, India, in medium black soils assessed the effect of nutrient omission in Bt cotton and its effect on the soil organic carbon (SOC) and available nutrients at the end of second consecutive year of nutrient omission. The study also assessed the extent of contribution of the macro and micronutrients towards seed cotton yield. The experiment consisting 11 treatments omitting a nutrient in each treatment including an absolute control without any nutrients was conducted in a Randomised Block Design with three replications. Cotton crop sufficiently fertilized with macro and micro nutrients (165 : 75 : 120 NPK kg ha-1 and 20 kg each of CaSO4, and MgSO4, 10 kg of S, 20 kg each of ZnSO4, FeSO4 and 0.1 per cent Boron twice as foliar spray) was taken as a standard check to assess the contribution of each nutrient in various nutrient omission treatments. Soils of each treatment were analysed initially and after each crop of cotton for SOC and available nutrient status. Results indicated that the SOC decreased after each crop of cotton in absolute control where no nutrients were applied (0.50 % to 0.38 %) and also in the N omission treatment (0.50 % to 0.35 %). But there was no significant impact of omission of P, K and other nutrients on soil organic carbon. Soil available N, P and K in the soil were reduced as compared to the initial soil status after first and second crop of cotton in the respective treatment where these nutrients were omitted. The soil available N, P and K were reduced to the extent of 61 kg ha-1, 7.1 kg ha-1 and 161.9 kg ha-1 in the respective nutrient omission treatment at end of second crop of cotton as compared to the initial status of these nutrients in the soil. This might be due to the mining of these nutrients from the soil nutrient pool with out addition of these nutrients extraneously. The nutrient status of N, P and K remained almost similar in omission of other nutrients

  13. Does temperature of charcoal creation affect subsequent mineralization of soil carbon and nitrogen?

    Science.gov (United States)

    Pelletier-Bergeron, S.; Bradley, R.; Munson, A. D.

    2012-04-01

    Forest fire is the most common form of natural disturbance of boreal forest ecosystems and has primordial influence on successional processes. This may be due in part to the pre-disturbance vegetation development stage and species composition, but these successional pathways could also vary with differences in fire behavior and consequently in fire intensity, defined as the energy released during various phases of a fire. Fire intensity may also affect soil C and N cycling by affecting the quality of the charcoal that is produced. For example, the porosity of coal tends to increase with increasing temperature at which it is produced Higher porosity would logically increase the surface area to which dissolved soil molecules, such as tannins and other phenolics, may be adsorbed. We report on a microcosm study in which mineral and organic soils were jointly incubated for eight weeks with a full factorial array of treatments that included the addition of Kalmia tannins, protein, and wood charcoal produced at five different temperatures. A fourth experimental factor comprised the physical arrangement of the material (stratified vs. mixed), designed to simulate the effect of soil scarification after fire and salvage harvest. We examined the effects of these treatments on soil C and N mineralisation and soil microbial biomass. The furnace temperature at which the charcoal was produced had a significant effect on its physico-chemical properties; increasing furnace temperatures corresponded to a significant increase in % C (P<0.001), and a significant decrease in %O (P<0.001) and %H (P<0.001). Temperature also had significant impacts on microporosity (surface area and volume). Temperature of production had no effect (P=0.1355) on soil microbial biomass. We observed a linear decreasing trend (P<0.001) in qCO2 with increasing temperature of production, which was mainly reflected in a decline in basal respiration. Finally, we found a significant interaction (P=0.010) between

  14. India and Pakistan: Partition Lessons

    DEFF Research Database (Denmark)

    Kaur, Ravinder

    2007-01-01

    The violent territorial rupture of 1947 and its legacy reveal partition to be conceptually flawed and historically ill-grounded as a solution to political antagonism, says Ravinder Kaur.......The violent territorial rupture of 1947 and its legacy reveal partition to be conceptually flawed and historically ill-grounded as a solution to political antagonism, says Ravinder Kaur....

  15. Distribution of organic carbon in physical fractions of soils as affected by agricultural management

    Energy Technology Data Exchange (ETDEWEB)

    Sindhu, Jagadamma [Oak Ridge National Laboratory (ORNL); Lal, Dr. Rattan [Ohio State University, The, Columbus

    2010-08-01

    Soil organic carbon (SOC) is distributed heterogeneously among different-sized primary particles and aggregates. Further, the SOC associated with different physical fractions respond differently to managements. Therefore, this study was conducted with the objective to quantify the SOC associated with all the three structural levels of SOC (particulate organic matter, soil separates and aggregate-size fractions) as influenced by long-term change in management. The study also aims at reevaluating the concept that the SOC sink capacity of individual size-fractions is limited. Long-term tillage and crop rotation effects on distribution of SOC among fractions were compared with soil from adjacent undisturbed area under native vegetation for the mixed, mesic, Typic Fragiudalf of Wooster, OH. Forty five years of no-till (NT) management resulted in more SOC accumulation in soil surface (0 7.5 cm) than in chisel tillage and plow tillage (PT) treatments. However, PT at this site resulted in a redistribution of SOC from surface to deeper soil layers. The soils under continuous corn accumulated significantly more SOC than those under corn soybean rotation at 7.5 45 cm depth. Although soil texture was dominated by the silt-sized particles, most of the SOC pool was associated with the clay fraction. Compared to PT, the NT treatment resulted in (i) significantly higher proportion of large macroaggregates (>2,000 m) and (ii) 1.5 2.8 times higher SOC concentrations in all aggregate-size classes. A comparative evaluation using radar graphs indicated that among the physical fractions, the SOC associated with sand and silt fractions quickly changed with a land use conversion from native vegetation to agricultural crops. A key finding of this study is the assessment of SOC sink capacity of individual fractions, which revealed that the clay fraction of agricultural soils continues to accumulate more SOC, albeit at a slower rate, with progressive increase in total SOC concentration

  16. Decreased carbon limitation of litter respiration in a mortality-affected piñon-juniper woodland

    Directory of Open Access Journals (Sweden)

    E. Berryman

    2012-10-01

    Full Text Available Microbial respiration depends on microclimatic variables and carbon (C substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon-juniper ecosystems in Southwestern North America, may affect C substrate availability in several ways; for example, via litterfall pulses and loss of root exudation. To determine piñon mortality effects on C and water limitation of microbial respiration, we applied field amendments (sucrose and water to two piñon-juniper sites in central New Mexico, USA: one with a recent (< 1 yr, experimentally-induced mortality event and a nearby site with live canopy. We monitored the respiration response to water and sucrose applications to the litter surface and to the underlying mineral soil surface, testing the following hypotheses: (1 soil respiration in a piñon-juniper woodland is water- and labile C-limited in both the litter layer and mineral soil; (2 water and sucrose applications increase temperature sensitivity of respiration; (3 the mortality-affected site will show a reduction in C limitation in the litter; (4 the mortality-affected site will show an enhancement of C limitation in the mineral soil. Litter respiration at both sites responded to increased water availability, yet surprisingly, mineral soil respiration was not limited by water. Temperature sensitivity was enhanced by some of the sucrose and water treatments. Consistent with hypothesis 3, C limitation of litter respiration was lower at the recent mortality site compared to the intact canopy site. Results following applications to the mineral soil suggest the presence of abiotic effects of increasing water availability, precluding our ability to measure labile C limitation in soil. Widespread piñon mortality may decrease labile C limitation of litter respiration, at least during the first growing season following mortality.

  17. Dissolved organic carbon and nitrogen mineralization strongly affect co2 emissions following lime application to acidic soil

    International Nuclear Information System (INIS)

    Emission of greenhouse gases from agricultural soils has main contribution to the climatic change and global warming. Dynamics of dissolved organic carbon (DOC) and nitrogen mineralization can affect CO/sub 2/ emission from soils. Influence of DOC and nitrogen mineralization on CO/sub 2/ emissions following lime application to acidic soil was investigated in current study. Laboratory experiment was conducted under aerobic conditions with 25% moisture contents (66% water-filled pore space) at 25 degree C in the dark conditions. Different treatments of lime were applied to acidic soil as follows: CK (control), L (low rate of lime: 0.2g lime / 100 g soil) and H (high rate of lime: 0.5g lime /100g soil). CO/sub 2/ emissions were measured by gas chromatography and dissolved organic carbon, NH4 +-N, NO/sub 3/ --N and soil pH were measured during incubation study. Addition of lime to acidic soil significantly increased the concentration of DOC and N mineralization rate. Higher concentrations of DOC and N mineralization, consequently, increased the CO/sub 2/ emissions from lime treated soils. Cumulative CO/sub 2/ emission was 75% and 71% higher from L and H treatments as compared to CK. The results of current study suggest that DOC and N mineralization are critical in controlling gaseous emissions of CO/sub 2/ from acidic soils following lime application. (author)

  18. The role of initial affective impressions in responses to educational communications: the case of carbon capture and sequestration (CCS).

    Science.gov (United States)

    Bruine de Bruin, Wändi; Wong-Parodi, Gabrielle

    2014-06-01

    Emerging technologies promise potential benefits at a potential cost. Developers of educational communications aim to improve people's understanding and to facilitate public debate. However, even relatively uninformed recipients may have initial feelings that are difficult to change. We report that people's initial affective impressions about carbon capture and sequestration (CCS), a low-carbon coal-based electricity-generation technology with which most people are unfamiliar, influences how they interpret previously validated education materials. As a result, even individuals who had originally self-identified as uninformed persisted in their initial feelings after reading the educational communication-though perseverance of feelings about CCS was stronger among recipients who had originally self-identified as relatively informed (Study 1). Moreover, uninformed recipients whose initial feelings were experimentally manipulated by relatively uninformative pro-CCS or anti-CCS arguments persisted in their manipulated feelings after reading the educational communication, due to evaluating the educational communication in line with their manipulated impressions (Study 2). Hence, our results suggest that educational communications will have more impact if they are disseminated before people form strong feelings about the topic under consideration, especially if these are based on little to no factual understanding. PMID:24708355

  19. Interactions between Bifidobacterium and Bacteroides species in cofermentations are affected by carbon sources, including exopolysaccharides produced by bifidobacteria.

    Science.gov (United States)

    Rios-Covian, David; Arboleya, Silvia; Hernandez-Barranco, Ana M; Alvarez-Buylla, Jorge R; Ruas-Madiedo, Patricia; Gueimonde, Miguel; de los Reyes-Gavilan, Clara G

    2013-12-01

    Cocultures of strains from two Bifidobacterium and two Bacteroides species were performed with exopolysaccharides (EPS) previously purified from bifidobacteria, with inulin, or with glucose as the carbon source. Bifidobacterium longum NB667 and Bifidobacterium breve IPLA20004 grew in glucose but showed poor or no growth in complex carbohydrates (inulin, EPS E44, and EPS R1), whereas Bacteroides grew well in the four carbon sources tested. In the presence of glucose, the growth of Bacteroides thetaiotaomicron DSM-2079 was inhibited by B. breve, whereas it remained unaffected in the presence of B. longum. Ba. fragilis DSM-2151 contributed to a greater survival of B. longum, promoting changes in the synthesis of short-chain fatty acids (SCFA) and organic acids in coculture with respect to monocultures. In complex carbohydrates, cocultures of bifidobacterium strains with Ba. thetaiotaomicron did not modify the behavior of Bacteroides nor improve the poor growth of bifidobacteria. The metabolic activity of Ba. fragilis in coculture with bifidobacteria was not affected by EPS, but greater survival of bifidobacteria at late stages of incubation occurred in cocultures than in monocultures, leading to a higher production of acetic acid than in monocultures. Therefore, cocultures of Bifidobacterium and Bacteroides can behave differently against fermentable carbohydrates as a function of the specific characteristics of the strains from each species. These results stress the importance of considering specific species and strain interactions and not simply higher taxonomic divisions in the relationship among intestinal microbial populations and their different responses to probiotics and prebiotics. PMID:24077708

  20. CO2-induced shift in microbial activity affects carbon trapping and water quality in anoxic bioreactors

    Science.gov (United States)

    Kirk, Matthew F.; Santillan, Eugenio F. U.; Sanford, Robert A.; Altman, Susan J.

    2013-12-01

    Microbial activity is a potentially important yet poorly understood control on the fate and environmental impact of CO2 that leaks into aquifers from deep storage reservoirs. In this study we examine how variation in CO2 abundance affected competition between Fe(III) and SO42--reducers in anoxic bioreactors inoculated with a mixed-microbial community from a freshwater aquifer. We performed two sets of experiments: one with low CO2 partial pressure (∼0.02 atm) in the headspace of the reactors and one with high CO2 partial pressure (∼1 atm). A fluid residence time of 35 days was maintained in the reactors by replacing one-fifth of the aqueous volume with fresh medium every seven days. The aqueous medium was composed of groundwater amended with small amounts of acetate (250 μM), phosphate (1 μM), and ammonium (50 μM) to stimulate microbial activity. Synthetic goethite (1 mmol) and SO42- (500 μM influent concentration) were also available in each reactor to serve as electron acceptors. Results of this study show that higher CO2 abundance increased the ability of Fe(III) reducers to compete with SO42- reducers, leading to significant shifts in CO2 trapping and water quality. Mass-balance calculations and pyrosequencing results demonstrate that SO42- reducers were dominant in reactors with low CO2 content. They consumed 85% of the acetate after acetate consumption reached steady state while Fe(III) reducers consumed only 15% on average. In contrast, Fe(III) reducers were dominant during that same interval in reactors with high CO2 content, consuming at least 90% of the acetate while SO42- reducers consumed a negligible amount (bioreactors enhanced CO2 solubility trapping relative to the low-CO2 bioreactors by increasing alkalinity generation (6X). Hence, the shift in microbial activity we observed was a positive feedback on CO2 trapping. More rapid Fe(III) reduction degraded water quality, however, by leading to high Fe(II) concentration.

  1. Enhancement of Heat-Affected Zone Toughness of a Low Carbon Steel by TiN Particle

    Science.gov (United States)

    Zhang, Yu; Li, Xiaobao; Ma, Han

    2016-08-01

    Enhancement of heat-affected zone toughness of a weight percentage of 0.014 pct Ti-bearing low carbon steel by TiN particle was investigated. An increase in nitrogen weight percentage from 0.0031 to 0.0083 pct results in increasing of number density of TiN precipitates from 4 × 103 to 3 × 105/mm2, and reduces prior austenite grain size from 850 to 350 μm with a soaking of 1673 K (1400 °C) for 2000 seconds. Effective refinement of austenite grain prohibits formation of ferrite side plate and/or upper bainite, and densely distributed TiN particles promote intra-granular ferrite formation, which is accompanied by an increase of 40 K to 60 K (40 °C to 60 °C) in austenite decomposition temperature during continuous cooling process. The changes in transformed products improved impact toughness of heat-affected zone efficiently, ex., increase absorbed energy of less than 42 J to more than 320 J with a simulated t 8/5 of 550 seconds.

  2. Climatic Versus Biotic Constraints on Carbon and Water Fluxes in Seasonally Drought-affected Ponderosa Pine Ecosystems. Chapter 2

    Science.gov (United States)

    Schwarz, P. A.; Law, B. E.; Williams, M.; Irvine, J.; Kurpius, M.; Moore, D.

    2005-01-01

    We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (50%), and intermediate at the YS (climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE.

  3. Enhancement of Heat-Affected Zone Toughness of a Low Carbon Steel by TiN Particle

    Science.gov (United States)

    Zhang, Yu; Li, Xiaobao; Ma, Han

    2015-11-01

    Enhancement of heat-affected zone toughness of a weight percentage of 0.014 pct Ti-bearing low carbon steel by TiN particle was investigated. An increase in nitrogen weight percentage from 0.0031 to 0.0083 pct results in increasing of number density of TiN precipitates from 4 × 103 to 3 × 105/mm2, and reduces prior austenite grain size from 850 to 350 μm with a soaking of 1673 K (1400 °C) for 2000 seconds. Effective refinement of austenite grain prohibits formation of ferrite side plate and/or upper bainite, and densely distributed TiN particles promote intra-granular ferrite formation, which is accompanied by an increase of 40 K to 60 K (40 °C to 60 °C) in austenite decomposition temperature during continuous cooling process. The changes in transformed products improved impact toughness of heat-affected zone efficiently, ex., increase absorbed energy of less than 42 J to more than 320 J with a simulated t 8/5 of 550 seconds.

  4. Developing Key Parameters for Green Performance of Partition Wall Blocks

    Directory of Open Access Journals (Sweden)

    Goh Cheng Siew

    2016-01-01

    Full Text Available To promote sustainable construction, it is important to consider green performance of construction materials throughout the life cycle. Selecting inappropriate materials could not only affect the functional performance but also preclude the achievement of green building performance as a whole. Green performance of construction materials has therefore been one of the primary considerations of green building assessment systems. Using partition wall blocks as an example, this paper examines green performance of building materials primarily from the cradle to gate boundaries. Nine key parameters are proposed for the green performance of partition wall blocks. Apart from environmental features, technical performance of partition wall blocks is also taken into consideration since it is the determinant of the lifecycle performance. This paper offers a roadmap to decision makers to make environmentally responsible choices for their materials of internal walls and partitions, and hence provides a potential sustainable solution for green buildings.

  5. Present status of partitioning developments

    International Nuclear Information System (INIS)

    Evolution and development of the concept of partitioning of high-level liquid wastes (HLLW) in nuclear fuel reprocessing are reviewed historically from the early phase of separating useful radioisotopes from HLLW to the recent phase of eliminating hazardous nuclides such as transuranium elements for safe waste disposal. Since the criteria in determining the nuclides for elimination and the respective decontamination factors are important in the strategy of partitioning, current views on the criteria are summarized. As elimination of the transuranium is most significant in the partitioning, various methods available of separating them from fission products are evaluated. (auth.)

  6. Square Partitions and Catalan Numbers

    OpenAIRE

    Bennett, Matthew; Chari, Vyjayanthi; Dolbin, R. J.; Manning, Nathan

    2009-01-01

    For each integer $k\\ge 1$, we define an algorithm which associates to a partition whose maximal value is at most $k$ a certain subset of all partitions. In the case when we begin with a partition $\\lambda$ which is square, i.e $\\lambda=\\lambda_1\\ge...\\ge\\lambda_k>0$, and $\\lambda_1=k,\\lambda_k=1$, then applying the algorithm $\\ell$ times gives rise to a set whose cardinality is either the Catalan number $c_{\\ell-k+1}$ (the self dual case) or twice the Catalan number. The algorithm defines a t...

  7. Partitioning ecosystems for sustainability.

    Science.gov (United States)

    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.

  8. Incentives for partitioning, revisited

    International Nuclear Information System (INIS)

    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

  9. Partitioning ecosystems for sustainability.

    Science.gov (United States)

    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. PMID:27209800

  10. Biomass partitioning and its relationship with the environmental factors at the alpine steppe in Northern Tibet.

    Directory of Open Access Journals (Sweden)

    Jianbo Wu

    Full Text Available Alpine steppe is considered to be the largest grassland type on the Tibetan Plateau. This grassland contributes to the global carbon cycle and is sensitive to climate changes. The allocation of biomass in an ecosystem affects plant growth and the overall functioning of the ecosystem. However, the mechanism by which plant biomass is allocated on the alpine steppe remains unclear. In this study, biomass allocation and its relationship to environmental factors on the alpine grassland were studied by a meta-analysis of 32 field sites across the alpine steppe of the northern Tibetan Plateau. We found that there is less above-ground biomass (M A and below-ground biomass (M B in the alpine steppe than there is in alpine meadows and temperate grasslands. By contrast, the root-to-shoot ratio (R:S in the alpine steppe is higher than it is in alpine meadows and temperate grasslands. Although temperature maintained the biomass in the alpine steppe, precipitation was found to considerably influence M A , M B , and R:S, as shown by ordination space partitioning. After standardized major axis (SMA analysis, we found that allocation of biomass on the alpine steppe is supported by the allometric biomass partitioning hypothesis rather than the isometric allocation hypothesis. Based on these results, we believe that M A and M B will decrease as a result of the increased aridity expected to occur in the future, which will reduce the landscape's capacity for carbon storage.

  11. Bidentate organophosphorus solvent extraction process for actinide recovery and partition

    Science.gov (United States)

    Schulz, Wallace W.

    1976-01-01

    A liquid-liquid extraction process for the recovery and partitioning of actinide values from acidic nuclear waste aqueous solutions, the actinide values including trivalent, tetravalent and hexavalent oxidation states is provided and includes the steps of contacting the aqueous solution with a bidentate organophosphorous extractant to extract essentially all of the actinide values into the organic phase. Thereafter the respective actinide fractions are selectively partitioned into separate aqueous solutions by contact with dilute nitric or nitric-hydrofluoric acid solutions. The hexavalent uranium is finally removed from the organic phase by contact with a dilute sodium carbonate solution.

  12. Flux Partitioning by Isotopic Eddy Covariance

    Science.gov (United States)

    Wehr, R.; Munger, J. W.; Nelson, D. D.; McManus, J. B.; Zahniser, M. S.; Wofsy, S. C.; Saleska, S. R.

    2011-12-01

    Net ecosystem-atmosphere exchange of CO2 is routinely measured by eddy covariance at sites around the world, but studies of ecosystem processes are more interested in the gross photosynthetic and respiratory fluxes that comprise the net flux. The standard method of partitioning the net flux into these components has been to extrapolate nighttime respiration into daytime based on a relationship between nighttime respiration, temperature, and sometimes moisture. However, such relationships generally account for only a small portion of the variation in nighttime respiration, and the assumption that they can predict respiration throughout the day is dubious. A promising alternate method, known as isotopic flux partitioning, works by identifying the stable isotopic signatures of photosynthesis and respiration in the CO2 flux. We have used this method to partition the net flux at Harvard Forest, MA, based on eddy covariance measurements of the net 12CO2 and 13CO2 fluxes (as well as measurements of the sensible and latent heat fluxes and other meteorological variables). The CO2 isotopologues were measured at 4 Hz by an Aerodyne quantum cascade laser spectrometer with a δ13C precision of 0.4 % in 0.25 sec and 0.02 % in 100 sec. In the absence of such high-frequency, high-precision isotopic measurements, past attempts at isotopic flux partitioning have combined isotopic flask measurements with high-frequency (total) CO2 measurements to estimate the isoflux (the EC/flask approach). Others have used a conditional flask sampling approach called hyperbolic relaxed eddy accumulation (HREA). We 'sampled' our data according to each of these approaches, for comparison, and found disagreement in the calculated fluxes of ~10% for the EC/flask approach, and ~30% for HREA, at midday. To our knowledge, this is the first example of flux partitioning by isotopic eddy covariance. Wider use of this method, enabled by a new generation of laser spectrometers, promises to open a new window

  13. Affecting the morphology of silver deposition on carbon nanotube surface: From nanoparticles to dendritic (tree-like) nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Forati-Nezhad, Mohsen [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Mir Mohamad Sadeghi, Gity, E-mail: gsadeghi@aut.ac.ir [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Yaghmaie, Frank [Northern California Nanotechnology Center, University of California, Davis, CA 95616 (United States); Alimohammadi, Farbod [Young Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2015-01-01

    Chemical reduction was used to synthesize silver crystals on the surface of multiwall carbon nanotubes (MWCNTs) in the presence of acetone, N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone, and isopropyl alcohol as solvent. DMF and sodium dodecyl sulfate were used as a reducing and a stabilizing agent, respectively. The structure and nature of hybrid MWCNT/silver were characterized by Raman spectroscopy, FTIR spectroscopy, transmission electron microscopy (TEM), and field emission scanning electron microscope (FESEM). The presence of silver crystals on the nanotubes was confirmed by XRD. The results show the formation of silver crystals on the MWCNT surface and indicate that the morphology of silver crystals can be control by changing the solvent. The type of solvent is an effective parameter that affects the particle size and morphological transition from nanoparticles to silver trees. - Highlights: • The silver crystals are grown on the CNT surface by chemical reduction method. • The morphology of silver crystals is controlled by changing the solvent. • Silver nanoparticles and dendritic nanostructures on CNT surface are achieved. • Any change in structure and surface defects by synthesis condition is investigated.

  14. Granular activated carbon for simultaneous adsorption and biodegradation of toxic oil sands process-affected water organic compounds.

    Science.gov (United States)

    Islam, Md Shahinoor; Zhang, Yanyan; McPhedran, Kerry N; Liu, Yang; Gamal El-Din, Mohamed

    2015-04-01

    Naphthenic acids (NAs) released into oil sands process-affected water (OSPW) during bitumen processing in Northern Alberta are problematic for oil sands industries due to their toxicity in the environment and resistance to degradation during conventional wastewater treatment processes. Granular activated carbon (GAC) has shown to be an effective media in removing biopersistent organics from wastewater using a combination of adsorption and biodegradation removal mechanisms. A simultaneous GAC (0.4 g GAC/L) adsorption and biodegradation (combined treatment) study was used for the treatment of raw and ozonated OSPW. After 28 days of batch treatment, classical and oxidized NAs removals for raw OSPW were 93.3% and 73.7%, and for ozonated OSPW were 96.2% and 77.1%, respectively. Synergetic effects of the combined treatment process were observed in removals of COD, the acid extractable fraction, and oxidized NAs, which indicated enhanced biodegradation and bioregeneration in GAC biofilms. A bacteria copy number >10(8) copies/g GAC on GAC surfaces was found using quantitative real time polymerase chain reaction after treatment for both raw and ozonated OSPW. A Microtox(®) acute toxicity test (Vibrio fischeri) showed effective toxicity removal (>95.3%) for the combined treatments. Therefore, the simultaneous GAC adsorption and biodegradation treatment process is a promising technology for the elimination of toxic OSPW NAs.

  15. Study of the Factors Affecting the Abundance of Organic Matter in Jurassic Carbonate Rocks in Qiangtang Basin, Tibet

    Institute of Scientific and Technical Information of China (English)

    文志刚; 胡明毅; 龚文平; 肖传桃

    2004-01-01

    Field and laboratory analyses of carbonate rock samples from the Qiangtang Basin,Tibet, indicate that carbonate source rocks are mainly developed in the Middle Jurassic Xiali Formation and Upper Jurassic Suowa Formation. Comprehensive studies showed that the Suowa Formation carbonate source rocks have a favorable hydrocarbon-generating potential. The abundance of organic matter in the carbonate rocks is controlled mainly by sedimentary environment and inorganic compounds in the rocks, which is higher in the restricted platform facies than in the open platform facies. Organic carbon contents decrease with increasing CaO contents in the source rocks.

  16. Classification algorithms using adaptive partitioning

    KAUST Repository

    Binev, Peter

    2014-12-01

    © 2014 Institute of Mathematical Statistics. Algorithms for binary classification based on adaptive tree partitioning are formulated and analyzed for both their risk performance and their friendliness to numerical implementation. The algorithms can be viewed as generating a set approximation to the Bayes set and thus fall into the general category of set estimators. In contrast with the most studied tree-based algorithms, which utilize piecewise constant approximation on the generated partition [IEEE Trans. Inform. Theory 52 (2006) 1335.1353; Mach. Learn. 66 (2007) 209.242], we consider decorated trees, which allow us to derive higher order methods. Convergence rates for these methods are derived in terms the parameter - of margin conditions and a rate s of best approximation of the Bayes set by decorated adaptive partitions. They can also be expressed in terms of the Besov smoothness β of the regression function that governs its approximability by piecewise polynomials on adaptive partition. The execution of the algorithms does not require knowledge of the smoothness or margin conditions. Besov smoothness conditions are weaker than the commonly used Holder conditions, which govern approximation by nonadaptive partitions, and therefore for a given regression function can result in a higher rate of convergence. This in turn mitigates the compatibility conflict between smoothness and margin parameters.

  17. Sediment-water interaction in a water reservoir affected by acid mine drainage : experimental and modeling

    OpenAIRE

    Torres Sánchez, Ester

    2013-01-01

    The discharge of acid mine drainage into a water reservoir may seriously affect the water quality. In this setting, sediment is commonly thought to act as a sink for pollutants. However, redox oscillations in the bottom water promoted by stratification-turnover events may significantly alter the metal cycling. A new sequential extraction procedure has been developed to study the metal partitioning in the sediment. The new scheme for iron, sulfur and organic carbon rich sediments was evaluated...

  18. Soil organic carbon sequestration as affected by afforestation: the Darab Kola forest (north of Iran) case study.

    Science.gov (United States)

    Kooch, Yahya; Hosseini, Seyed Mohsen; Zaccone, Claudio; Jalilvand, Hamid; Hojjati, Seyed Mohammad

    2012-09-01

    Following the ratification of the Kyoto Protocol, afforestation of formerly arable lands and/or degraded areas has been acknowledged as a land-use change contributing to the mitigation of increasing atmospheric CO(2) concentration in the atmosphere. In the present work, we study the soil organic carbon sequestration (SOCS) in 21 year old stands of maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C.A. Mey.), and red pine (Pinus brutia Ten.) in the Darab Kola region, north of Iran. Soil samples were collected at four different depths (0-10, 10-20, 20-30, and 30-40 cm), and characterized with respect to bulk density, water content, electrical conductivity, pH, texture, lime content, total organic C, total N, and earthworm density and biomass. Data showed that afforested stands significantly affected soil characteristics, also raising SOCS phenomena, with values of 163.3, 120.6, and 102.1 Mg C ha(-1) for red pine, oak and maple stands, respectively, vs. 83.0 Mg C ha(-1) for the control region. Even if the dynamics of organic matter (OM) in soil is very complex and affected by several pedo-climatic factors, a stepwise regression method indicates that SOCS values in the studied area could be predicted using the following parameters, i.e., sand, clay, lime, and total N contents, and C/N ratio. In particular, although the chemical and physical stabilization capacity of organic C by soil is believed to be mainly governed by clay content, regression analysis showed a positive correlation between SOCS and sand (R = 0.86(**)), whereas a negative correlation with clay (R = -0.77(**)) was observed, thus suggesting that most of this organic C occurs as particulate OM instead of mineral-associated OM. Although the proposed models do not take into account possible changes due to natural and anthropogenic processes, they represent a simple way that could be used to evaluate and/or monitor the potential of each forest plantation in immobilizing organic C in soil (thus

  19. Soil organic carbon sequestration as affected by afforestation: the Darab Kola forest (north of Iran) case study.

    Science.gov (United States)

    Kooch, Yahya; Hosseini, Seyed Mohsen; Zaccone, Claudio; Jalilvand, Hamid; Hojjati, Seyed Mohammad

    2012-09-01

    Following the ratification of the Kyoto Protocol, afforestation of formerly arable lands and/or degraded areas has been acknowledged as a land-use change contributing to the mitigation of increasing atmospheric CO(2) concentration in the atmosphere. In the present work, we study the soil organic carbon sequestration (SOCS) in 21 year old stands of maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C.A. Mey.), and red pine (Pinus brutia Ten.) in the Darab Kola region, north of Iran. Soil samples were collected at four different depths (0-10, 10-20, 20-30, and 30-40 cm), and characterized with respect to bulk density, water content, electrical conductivity, pH, texture, lime content, total organic C, total N, and earthworm density and biomass. Data showed that afforested stands significantly affected soil characteristics, also raising SOCS phenomena, with values of 163.3, 120.6, and 102.1 Mg C ha(-1) for red pine, oak and maple stands, respectively, vs. 83.0 Mg C ha(-1) for the control region. Even if the dynamics of organic matter (OM) in soil is very complex and affected by several pedo-climatic factors, a stepwise regression method indicates that SOCS values in the studied area could be predicted using the following parameters, i.e., sand, clay, lime, and total N contents, and C/N ratio. In particular, although the chemical and physical stabilization capacity of organic C by soil is believed to be mainly governed by clay content, regression analysis showed a positive correlation between SOCS and sand (R = 0.86(**)), whereas a negative correlation with clay (R = -0.77(**)) was observed, thus suggesting that most of this organic C occurs as particulate OM instead of mineral-associated OM. Although the proposed models do not take into account possible changes due to natural and anthropogenic processes, they represent a simple way that could be used to evaluate and/or monitor the potential of each forest plantation in immobilizing organic C in soil (thus

  20. Stratification and Storage of Soil Organic Carbon and Nitrogen as Affected by Tillage Practices in the North China Plain

    Science.gov (United States)

    Zhang, Xiang-Qian; Kong, Fan-Lei; Chen, Fu; Lal, Rattan; Zhang, Hai-Lin

    2015-01-01

    Tillage practices can redistribute the soil profiles, and thus affects soil organic carbon (SOC), and its storage. The stratification ratio (SR) can be an indicator of soil quality. This study was conducted to determine tillage effects on the profile distribution of certain soil properties in winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) systems in the North China Plain (NCP). Three tillage treatments, including no till (NT), rotary tillage (RT), and plow tillage (PT), were established in 2001 in Luancheng County, Hebei Province. The concentration, storage, and SR of SOC and soil total nitrogen (TN) were assessed in both the wheat and maize seasons. Compared with RT and PT, the mean SRs for all depth ratios of SOC under NT increased by 7.85% and 30.61% during the maize season, and by 14.67% and 30.91% during the wheat season, respectively. The SR of TN for 0–5:30–50 cm increased by 140%, 161%, and 161% in the maize season, and 266%, 154%, and 122% in the wheat season compared to the SR for 0–5:5–10 cm under NT, RT and PT, respectively. The data indicated that SOC and TN were both concentrated in the surface-soil layers (0–10 cm) under NT but were distributed relatively evenly through the soil profile under PT. Meanwhile, the storage of SOC and TN was higher under NT for the surface soil (0–10 cm) but was higher under PT for the deeper soil (30–50 cm). Furthermore, the storage of SOC and TN was significantly related to SR of SOC and TN along the whole soil profile (P<0.0001). Therefore, SR could be used to explain and indicate the changes in the storage of SOC and TN. Further, NT stratifies SOC and TN, enhances the topsoil SOC storage, and helps to improve SOC sequestration and soil quality. PMID:26075391

  1. Stratification and Storage of Soil Organic Carbon and Nitrogen as Affected by Tillage Practices in the North China Plain.

    Science.gov (United States)

    Zhao, Xin; Xue, Jian-Fu; Zhang, Xiang-Qian; Kong, Fan-Lei; Chen, Fu; Lal, Rattan; Zhang, Hai-Lin

    2015-01-01

    Tillage practices can redistribute the soil profiles, and thus affects soil organic carbon (SOC), and its storage. The stratification ratio (SR) can be an indicator of soil quality. This study was conducted to determine tillage effects on the profile distribution of certain soil properties in winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) systems in the North China Plain (NCP). Three tillage treatments, including no till (NT), rotary tillage (RT), and plow tillage (PT), were established in 2001 in Luancheng County, Hebei Province. The concentration, storage, and SR of SOC and soil total nitrogen (TN) were assessed in both the wheat and maize seasons. Compared with RT and PT, the mean SRs for all depth ratios of SOC under NT increased by 7.85% and 30.61% during the maize season, and by 14.67% and 30.91% during the wheat season, respectively. The SR of TN for 0-5:30-50 cm increased by 140%, 161%, and 161% in the maize season, and 266%, 154%, and 122% in the wheat season compared to the SR for 0-5:5-10 cm under NT, RT and PT, respectively. The data indicated that SOC and TN were both concentrated in the surface-soil layers (0-10 cm) under NT but were distributed relatively evenly through the soil profile under PT. Meanwhile, the storage of SOC and TN was higher under NT for the surface soil (0-10 cm) but was higher under PT for the deeper soil (30-50 cm). Furthermore, the storage of SOC and TN was significantly related to SR of SOC and TN along the whole soil profile (Psoil quality.

  2. Gentile statistics and restricted partitions

    Indian Academy of Sciences (India)

    C S Srivatsan; M V N Murthy; R K Bhaduri

    2006-03-01

    In a recent paper (Tran et al, Ann. Phys. 311, 204 (2004)), some asymptotic number theoretical results on the partitioning of an integer were derived exploiting its connection to the quantum density of states of a many-particle system. We generalise these results to obtain an asymptotic formula for the restricted or coloured partitions $p_{k}^{s} (n)$, which is the number of partitions of an integer into the summand of th powers of integers such that each power of a given integer may occur utmost times. While the method is not rigorous, it reproduces the well-known asymptotic results for = 1 apart from yielding more general results for arbitrary values of .

  3. Extremal sizes of subspace partitions

    CERN Document Server

    Heden, Olof; Nastase, Esmeralda; Sissokho, Papa

    2011-01-01

    A subspace partition $\\Pi$ of $V=V(n,q)$ is a collection of subspaces of $V$ such that each 1-dimensional subspace of $V$ is in exactly one subspace of $\\Pi$. The size of $\\Pi$ is the number of its subspaces. Let $\\sigma_q(n,t)$ denote the minimum size of a subspace partition of $V$ in which the largest subspace has dimension $t$, and let $\\rho_q(n,t)$ denote the maximum size of a subspace partition of $V$ in which the smallest subspace has dimension $t$. In this paper, we determine the values of $\\sigma_q(n,t)$ and $\\rho_q(n,t)$ for all positive integers $n$ and $t$. Furthermore, we prove that if $n\\geq 2t$, then the minimum size of a maximal partial $t$-spread in $V(n+t-1,q)$ is $\\sigma_q(n,t)$.

  4. The Partition Ensemble Fallacy Fallacy

    CERN Document Server

    Nemoto, K; Nemoto, Kae; Braunstein, Samuel L.

    2002-01-01

    The Partition Ensemble Fallacy was recently applied to claim no quantum coherence exists in coherent states produced by lasers. We show that this claim relies on an untestable belief of a particular prior distribution of absolute phase. One's choice for the prior distribution for an unobservable quantity is a matter of `religion'. We call this principle the Partition Ensemble Fallacy Fallacy. Further, we show an alternative approach to construct a relative-quantity Hilbert subspace where unobservability of certain quantities is guaranteed by global conservation laws. This approach is applied to coherent states and constructs an approximate relative-phase Hilbert subspace.

  5. Partial domain wall partition functions

    OpenAIRE

    Foda, O.; Wheeler, M.

    2012-01-01

    We consider six-vertex model configurations on an n-by-N lattice, n =< N, that satisfy a variation on domain wall boundary conditions that we define and call "partial domain wall boundary conditions". We obtain two expressions for the corresponding "partial domain wall partition function", as an (N-by-N)-determinant and as an (n-by-n)-determinant. The latter was first obtained by I Kostov. We show that the two determinants are equal, as expected from the fact that they are partition functions...

  6. Strain Partitioning and Load Transfer in Constituent Phases in Dual-Phase Steels

    Science.gov (United States)

    Varshney, A.; Sangal, S.; Mondal, K.

    2016-09-01

    In this investigation, a new approach is proposed to calculate in situ true stress and strain in the constituent phases of dual-phase steel during deformation. The model incorporates modified law of mixture and constitutive equations. The model proposes that the deformation of martensite is pseudoelastic, and on little permanent deformation within the martensite allows the locked-in dislocation to release in the ferrite at the interface region of the ferrite and martensite. On application of the model to a set of dual-phase steels with varying microstructural parameters, it is established that the amount of strain partitioning is affected by the strength and amount of the hard phase, as well as grain size, work hardening ability, and yield strength of the softer phase. On the other hand, grain size, carbon content, and fraction and strength of martensite are the main factors controlling the load transfer among the phases.

  7. Pulmonary exposure to single-walled carbon nanotubes does not affect the early immune response against Toxoplasma gondii

    Directory of Open Access Journals (Sweden)

    Swedin Linda

    2012-05-01

    Full Text Available Abstract Background Single-walled carbon nanotubes (SWCNT trigger pronounced inflammation and fibrosis in the lungs of mice following administration via pharyngeal aspiration or inhalation. Human exposure to SWCNT in an occupational setting may occur in conjunction with infections and this could yield enhanced or suppressed responses to the offending agent. Here, we studied whether the sequential exposure to SWCNT via pharyngeal aspiration and infection of mice with the ubiquitous intracellular parasite Toxoplasma gondii would impact on the immune response of the host against the parasite. Methods C57BL/6 mice were pre-exposed by pharyngeal administration of SWCNT (80 + 80 μg/mouse for two consecutive days followed by intravenous injection with either 1x103 or 1x104 green fluorescence protein and luciferase-expressing T. gondii tachyzoites. The dissemination of T. gondii was monitored by in vivo bioluminescence imaging in real time for 7 days and by plaque formation. The inflammatory response was analysed in bronchoalveolar lavage (BAL fluid, and by assessment of morphological changes and immune responses in lung and spleen. Results There were no differences in parasite distribution between mice only inoculated with T. gondii or those mice pre-exposed for 2 days to SWCNT before parasite inoculum. Lung and spleen histology and inflammation markers in BAL fluid reflected the effects of SWCNT exposure and T. gondii injection, respectively. We also noted that CD11c positive dendritic cells but not F4/80 positive macrophages retained SWCNT in the lungs 9 days after pharyngeal aspiration. However, co-localization of T. gondii with CD11c or F4/80 positive cells could not be observed in lungs or spleen. Pre-exposure to SWCNT did not affect the splenocyte response to T. gondii. Conclusions Taken together, our data indicate that pre-exposure to SWCNT does not enhance or suppress the early immune response to T. gondii in mice.

  8. Symbiodinium community composition in scleractinian corals is not affected by life-long exposure to elevated carbon dioxide.

    Directory of Open Access Journals (Sweden)

    Sam H C Noonan

    Full Text Available Ocean acidification (OA is expected to negatively affect coral reefs, however little is known about how OA will change the coral-algal symbiosis on which reefs ultimately depend. This study investigated whether there would be differences in coral Symbiodinium types in response to OA, potentially improving coral performance. We used denaturing gradient gel electrophoresis (DGGE of the internal transcribed spacer 2 (ITS2 region of ribosomal DNA to investigate the dominant types of Symbiodinium associating with six species of scleractinian coral that were exposed to elevated partial pressures of carbon dioxide (pCO2 in situ from settlement and throughout their lives. The study was conducted at three naturally occurring volcanic CO2 seeps (pCO2 ∼500 to 900 ppm, pHTotal 7.8 - 7.9 and adjacent control areas (pCO2 ∼390 ppm, pHTotal ∼8.0 - 8.05 in Papua New Guinea. The Symbiodinium associated with corals living in an extreme seep site (pCO2 >1000 ppm were also examined. Ten clade C types and three clade D types dominated the 443 coral samples. Symbiodinium types strongly contrasted between coral species, however, no differences were observed due to CO2 exposure. Within five species, 85 - 95% of samples exhibited the same Symbiodinium type across all sites, with remaining rare types having no patterns attributable to CO2 exposure. The sixth species of coral displayed site specific differences in Symbiodinium types, unrelated to CO2 exposure. Symbiodinium types from the coral inhabiting the extreme CO2 seep site were found commonly throughout the moderate seeps and control areas. Our finding that symbiotic associations did not change in response to CO2 exposure suggest that, within the six coral hosts, none of the investigated 13 clade C and D Symbiodinium types had a selective advantage at high pCO2. Acclimatisation through changing symbiotic association therefore does not seem to be an option for Indo-Pacific corals to deal with future OA.

  9. Photosynthate Partitioning and Fermentation in Hot Spring Microbial Mat Communities

    OpenAIRE

    Nold, S C; Ward, D M

    1996-01-01

    Patterns of (sup14)CO(inf2) incorporation into molecular components of the thermophilic cyanobacterial mat communities inhabiting hot springs located in Yellowstone National Park and Synechococcus sp. strain C1 were investigated. Exponentially growing Synechococcus sp. strain C1 partitioned the majority of incorporated (sup14)CO(inf2) into protein, low-molecular-weight metabolites, and lipid fractions (45, 22, and 18% of total incorporated carbon, respectively). In contrast, mat cores from va...

  10. Resource partitioning among top predators in a Miocene food web

    OpenAIRE

    Domingo, M. Soledad; Domingo, Laura; Badgley, Catherine; Sanisidro, Oscar; Morales, Jorge

    2013-01-01

    The exceptional fossil sites of Cerro de los Batallones (Madrid Basin, Spain) contain abundant remains of Late Miocene mammals. From these fossil assemblages, we have inferred diet, resource partitioning and habitat of three sympatric carnivorous mammals based on stable isotopes. The carnivorans include three apex predators: two sabre-toothed cats (Felidae) and a bear dog (Amphicyonidae). Herbivore and carnivore carbon isotope (δ13C) values from tooth enamel imply the presence of a woodland e...

  11. Photosynthate partitioning in alfalfa before harvest and during regrowth

    International Nuclear Information System (INIS)

    During the harvest regrowth cycle of alfalfa (Medicago sativa L.) plants, factors such as source to sink distance, sink size, and inter-organ competition continually change. However, consequent changes in the pattern of photosynthate partitioning from leaves to other organs are poorly understood. The authors objective was to examine photosynthate partitioning from upper and lower alfalfa leaves at intervals before herbage harvest and during regrowth after harvest. The uppermost or lowest fully expanded leaf on the longest or dominant stem was labeled with 14CO2. After a 24-h translocation period, the plants were divided into various organs to determine distribution of the radiocarbon. At that time, the upper leaf preferentially partitioned photosynthate to the shoot apex, unexpanded leaves and auxillary shoots of the dominant shoot, whereas the lower leaf preferentially distributed photosynthate to the crown shoots, crown, root, and nodules. Expressions of 14C partitioning were affected differently by organ mass. While the smallest organs such as nodules and unexpanded leaves always ranked higher for 14C based on relative specific activity, the largest organs such as roots and crown shoots accumulated the largest percentage of total plant recovered radioactivity. The results illustrate the importance of growth stage and leaf position in photosynthate partitioning in alfalfa and the dominance of herbage meristems for current photosynthate during regrowth

  12. Do soil organic carbon levels affect potential yields and nitrogen use efficiency? An analysis of winter wheat and spring barley field trials

    DEFF Research Database (Denmark)

    Oelofse, Myles; Markussen, Bo; Knudsen, Leif;

    2015-01-01

    Soil organic carbon (SOC) is broadly recognised as an important parameter affecting soil quality, and can therefore contribute to improving a number of soil properties that influence crop yield. Previous research generally indicates that soil organic carbon has positive effects on crop yields, but...... in many studies it is difficult to separate the effect of nutrients from the effect of SOC in itself. The aim of this study was to analyze whether the SOC content, in itself, has a significant effect on potential yields of commonly grown cereals across a wider range of soil types in Denmark. The...... yield, the yield with no fertiliser N application and the N use efficiency would be positively affected by SOC level. A statistical model was developed to explore relationships between SOC and potential yield, yields at zero N application and N use efficiency (NUE). The model included a variety of...

  13. On free fermions and plane partitions

    OpenAIRE

    Foda, O.; Wheeler, M.; Zuparic, M.

    2008-01-01

    We use free fermion methods to re-derive a result of Okounkov and Reshetikhin relating charged fermions to random plane partitions, and to extend it to relate neutral fermions to strict plane partitions.

  14. Non-deforestation fire vs. fossil fuel combustion: the source of CO2 emissions affects the global carbon cycle and climate responses

    OpenAIRE

    Landry, Jean-Sébastien; Matthews, H. Damon

    2016-01-01

    Non-deforestation fire – i.e., fire that is typically followed by the recovery of natural vegetation – is arguably the most influential disturbance in terrestrial ecosystems, thereby playing a major role in carbon exchanges and affecting many climatic processes. The radiative effect from a given atmospheric CO2 perturbation is the same for fire and fossil fuel combustion. However, major differences exist per unit of CO2 emitted between the effects of non-defor...

  15. Inversion of hematocrit partition at microfluidic bifurcations.

    Science.gov (United States)

    Shen, Zaiyi; Coupier, Gwennou; Kaoui, Badr; Polack, Benoît; Harting, Jens; Misbah, Chaouqi; Podgorski, Thomas

    2016-05-01

    Partitioning of red blood cells (RBCs) at the level of bifurcations in the microcirculatory system affects many physiological functions yet it remains poorly understood. We address this problem by using T-shaped microfluidic bifurcations as a model. Our computer simulations and in vitro experiments reveal that the hematocrit (ϕ0) partition depends strongly on RBC deformability, as long as ϕ0<20% (within the normal range in microcirculation), and can even lead to complete deprivation of RBCs in a child branch. Furthermore, we discover a deviation from the Zweifach-Fung effect which states that the child branch with lower flow rate recruits less RBCs than the higher flow rate child branch. At small enough ϕ0, we get the inverse scenario, and the hematocrit in the lower flow rate child branch is even higher than in the parent vessel. We explain this result by an intricate up-stream RBC organization and we highlight the extreme dependence of RBC transport on geometrical and cell mechanical properties. These parameters can lead to unexpected behaviors with consequences on the microcirculatory function and oxygen delivery in healthy and pathological conditions.

  16. Inversion of hematocrit partition at microfluidic bifurcations

    CERN Document Server

    Shen, Zaiyi; Kaoui, Badr; Polack, Benoît; Harting, Jens; Misbah, Chaouqi; Podgorski, Thomas

    2016-01-01

    Partitioning of red blood cells (RBCs) at the level of bifurcations in the microcirculatory system affects many physiological functions yet it remains poorly understood. We address this problem by using T-shaped microfluidic bifurcations as a model. Our computer simulations and in vitro experiments reveal that the hematocrit ($\\phi_0$) partition depends strongly on RBC deformability, as long as $\\phi_0 <20$% (within the normal range in microcirculation), and can even lead to complete deprivation of RBCs in a child branch. Furthermore, we discover a deviation from the Zweifach-Fung effect which states that the child branch with lower flow rate recruits less RBCs than the higher flow rate child branch. At small enough $\\phi_0$, we get the inverse scenario, and the hematocrit in the lower flow rate child branch is even higher than in the parent vessel. We explain this result by an intricate up-stream RBC organization and we highlight the extreme dependence of RBC transport on geometrical and cell mechanical p...

  17. The Effect of pH Difference Between Two Phases on the Partition of Lysozyme in Aqueous Two-Phase System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases, and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.

  18. On Packing Densities of Set Partitions

    OpenAIRE

    Goyt, Adam M.; Pudwell, Lara K.

    2013-01-01

    We study packing densities for set partitions, which is a generalization of packing words. We use results from the literature about packing densities for permutations and words to provide packing densities for set partitions. These results give us most of the packing densities for partitions of the set $\\{1,2,3\\}$. In the final section we determine the packing density of the set partition $\\{\\{1,3\\},\\{2\\}\\}$.

  19. Effects of Sequence Partitioning on Compression Rate

    OpenAIRE

    Alagoz, B. Baykant

    2010-01-01

    In the paper, a theoretical work is done for investigating effects of splitting data sequence into packs of data set. We proved that a partitioning of data sequence is possible to find such that the entropy rate at each subsequence is lower than entropy rate of the source. Effects of sequence partitioning on overall compression rate are argued on the bases of partitioning statistics, and then, an optimization problem for an optimal partition is defined to improve overall compression rate of a...

  20. Solving set partitioning problems using lagrangian relaxation

    NARCIS (Netherlands)

    van Krieken, M.G.C.

    2006-01-01

    This thesis focuses on the set partitioning problem. Given a collection of subsets of a certain root set and costs associated to these subsets, the set partitioning problem is the problem of finding a minimum cost partition of the root set. Many real-life problems, such as vehicle routing and crew s

  1. Modelling trace metal partitioning in forest floors of northern soils near metal smelters

    International Nuclear Information System (INIS)

    Trace metal (TM) mobility and toxicity varies with changing soil conditions. Geochemical models can account for the influence of soil characteristics on TM behaviour. We tested the effectiveness of the Stockholm humic model (SHM), and the NICA-Donnan model (NDM) to estimate partitioning coefficients (log Kd) in 26 forest floor horizons of podzolic soils enriched in trace metals from deposition by metal smelters. We wanted to know if a consistent approach could be applied to model metal partitioning in forest floors without optimizing each individual soil. When optimized, the SHM reproduced the partitioning of Cd, Cu and Zn but not Pb. It was necessary to revise the affinity constants for the NDM to simultaneously simulate the partitioning of the four metals. Revised affinity constants for the NDM model based on a fixed definition of soil organic carbon, i.e., a fixed ratio of fulvic and humic acids per unit carbon, reproduced metal partitioning more effectively in an independent data set of 16 soils than the use of generic affinity constants available for these models. From the perspective of the applicability of these models to risk assessment, this result suggests geochemical models using affinity constants that have been verified and/or modified against multiple soils from a region can provide good estimates of metal partitioning on a regional scale. - The solid-solution partitioning of trace metals in forest floors contaminated by smelter emissions can be modelled using a single set of model parameters for soil organic matter

  2. High toughness in the intercritically reheated coarse-grained (ICRCG) heat-affected zone (HAZ) of low carbon microalloyed steel

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jun, E-mail: hujunral@163.com [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Du, Lin-Xiu [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Wang, Jian-Jun [Institute of Materials Research, School of Material and Metallurgy, Northeastern University, Shenyang 110819 (China); Xie, Hui; Gao, Cai-Ru [The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Misra, R.D.K. [Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, University of Louisiana at Lafayette, Lafayette, LA 70504-4130 (United States)

    2014-01-10

    Motivated by the small lattice mismatch between ferrite and vanadium nitride (VN), we describe here the welding thermal cycle simulation that provides high toughness in the ICRCG HAZ of low carbon V–N steel. This unique behavior is attributed to the formation of ultra-fine grained ferrite along prior austenite grain boundaries generated by the first pass welding thermal cycle with high misorientation boundaries, where V(C, N) precipitates provide potential nucleation sites for ferrite, leading to extraordinary refinement of martensite/austenite (M/A) constituent. Nitrogen stimulates the precipitation behavior of V(C, N). The nucleation of high density of V(C, N) precipitates consumes carbon-content in the austenite, leading to decrease in the carbon-content in the M/A constituent, with consequent decrease in hardness. The increase in toughness is explained in terms of Griffith's crack propagation theory.

  3. High toughness in the intercritically reheated coarse-grained (ICRCG) heat-affected zone (HAZ) of low carbon microalloyed steel

    International Nuclear Information System (INIS)

    Motivated by the small lattice mismatch between ferrite and vanadium nitride (VN), we describe here the welding thermal cycle simulation that provides high toughness in the ICRCG HAZ of low carbon V–N steel. This unique behavior is attributed to the formation of ultra-fine grained ferrite along prior austenite grain boundaries generated by the first pass welding thermal cycle with high misorientation boundaries, where V(C, N) precipitates provide potential nucleation sites for ferrite, leading to extraordinary refinement of martensite/austenite (M/A) constituent. Nitrogen stimulates the precipitation behavior of V(C, N). The nucleation of high density of V(C, N) precipitates consumes carbon-content in the austenite, leading to decrease in the carbon-content in the M/A constituent, with consequent decrease in hardness. The increase in toughness is explained in terms of Griffith's crack propagation theory

  4. Graph partitioning advance clustering technique

    CERN Document Server

    Madhulatha, T Soni

    2012-01-01

    Clustering is a common technique for statistical data analysis, Clustering is the process of grouping the data into classes or clusters so that objects within a cluster have high similarity in comparison to one another, but are very dissimilar to objects in other clusters. Dissimilarities are assessed based on the attribute values describing the objects. Often, distance measures are used. Clustering is an unsupervised learning technique, where interesting patterns and structures can be found directly from very large data sets with little or none of the background knowledge. This paper also considers the partitioning of m-dimensional lattice graphs using Fiedler's approach, which requires the determination of the eigenvector belonging to the second smallest Eigenvalue of the Laplacian with K-means partitioning algorithm.

  5. Ontology Partitioning: Clustering Based Approach

    Directory of Open Access Journals (Sweden)

    Soraya Setti Ahmed

    2015-05-01

    Full Text Available The semantic web goal is to share and integrate data across different domains and organizations. The knowledge representations of semantic data are made possible by ontology. As the usage of semantic web increases, construction of the semantic web ontologies is also increased. Moreover, due to the monolithic nature of the ontology various semantic web operations like query answering, data sharing, data matching, data reuse and data integration become more complicated as the size of ontology increases. Partitioning the ontology is the key solution to handle this scalability issue. In this work, we propose a revision and an enhancement of K-means clustering algorithm based on a new semantic similarity measure for partitioning given ontology into high quality modules. The results show that our approach produces meaningful clusters than the traditional algorithm of K-means.

  6. On higher spin partition functions

    CERN Document Server

    Beccaria, M

    2015-01-01

    We observe that the partition function of the set of all free massless higher spins s=0,1,2,3,... in flat space is equal to one: the ghost determinants cancel against the "physical" ones or, equivalently, the (regularized) total number of degrees of freedom vanishes. This reflects large underlying gauge symmetry and suggests analogy with supersymmetric or topological theory. The Z=1 property extends also to the AdS background, i.e. the 1-loop vacuum partition function of Vasiliev theory is equal to 1 (assuming a particular regularization of the sum over spins); this was noticed earlier as a consistency requirement for the vectorial AdS/CFT duality. We find that Z=1 is also true in the conformal higher spin theory (with higher-derivative d^{2s} kinetic terms) expanded near flat or conformally flat S^4 background. We also consider the partition function of free conformal theory of symmetric traceless rank s tensor field which has 2-derivative kinetic term but only scalar gauge invariance in flat space. This non...

  7. A partitioned central solar receiver

    International Nuclear Information System (INIS)

    Else of solar energy as substitute for conventional fuels at a competitive cost requires efficient conversion from solar radiation to usable forms of energy. In solar thermal or thermochemical applications, high efficiency usually re- quires high temperature and high concentration of incoming radiation. The main form of energy loss from high temperature solar central receivers is thermal emission ('re radiation'), at an effective temperature close to the maximum receiver temperature. This loss is reduced if the aperture is divided into segments, most of which are maintained at lower temperatures. A two-stage partitioned receiver demonstrating this concept is under construction at the Weizman Solar Tower. The high-temperature stage is the DIAPR (Directly Irradiated Annular Pressurized Receiver). The low-temperature stage is made of tubular cavity receivers of simpler design. Preliminary optical and thermal design of the partitioned receiver is presented. For the design exit temperature of 1500 K, the aperture size of the partitioned receiver is about 60% of the equivalent single-stage receiver, indicating a significant increase of conversion efficiency. The exit temperature of the low-temperature stage is around 1100 K, allowing simpler design and inexpensive construction. (authors)

  8. Genetic Factors in Rhizobium Affecting the Symbiotic Carbon Costs of N2 Fixation and Host Plant Biomass Production

    DEFF Research Database (Denmark)

    Skøt, L.; Hirsch, P. R.; Witty, J. F.

    1986-01-01

    The effect of genetic factors in Rhizobium on host plant biomass production and on the carbon costs of N2 fixation in pea root nodules was studied. Nine strains of Rhizobium leguminosarum were constructed, each containing one of three symbiotic plasmids in combination with one of three different...... the lowest carbon costs of N2 fixation (7.10–8.10 μmol C/μmol N2), but shoot dry weight of those plants was also smaller than that of plants nodulated by strains with the background of B151 or JI8400. Nodules formed by these two strain types had carbon costs of N2 fixation varying between 11.26 and 13.......95 μmol C/μmol N2. The effect of symbiotic plasmids on the carbon costs was relatively small. A time-course experiment demonstrated that nodules formed by a strain derived from JI6015 were delayed in the onset of nitrogenase activity and had a lower rate of activity compared to nodules induced by a strain...

  9. Soil Carbon and Nitrogen Stock as Affected by Agricultural Wastes in a Typic Haplusult of Owerri, Southeastern Nigeria

    Directory of Open Access Journals (Sweden)

    Stanley Uchenna Onwudike

    2016-07-01

    Full Text Available We evaluated the effect of saw dust ash (SDA and poultry droppings (PD on soil physico-chemical properties, soil carbon and nitrogen stock and their effects on the growth and yield of okra (Abelmoshus esculentus on a typic haplusult in Owerri, Imo State Southeastern Nigeria. The experiment was a factorial experiment consisted of saw dust ash applied at the rates of 0, 5 and 10 t/ha and poultry droppings applied at the rates of 0, 5 and 10 t/ha. The treatments were laid out in a randomized complete block design and replicated four times. Results showed that plots amended with 10 t/ha PD + 10 t/ha SDA significantly reduced soil bulk density from 1.37 – 1.07 g/cm3, increased soil total porosity from 48.4 – 59.7% and the percentage of soil weight that is water (soil gravimetric moisture content was increased by 68.4%. There were significant improvements on soil chemical properties with plots amended with 10 t/ha PD + 10 t/ha SDA recording the highest values on soil organic carbon, soil total nitrogen and exchangeable bases. Plots amended with 10 t/ha PD + 10 t/ha SDA significantly increased soil carbon stock by 24% and soil nitrogen stock by 49.5% more than other treatments. There was significant increase in the growth of okra when compared to the un-amended soil with application of 10 t/ha PD + 10 t/ha SDA increasing the fresh okra pod yield by 78.5%. Significant positive correlation existed between SCS and organic carbon (r = 0.6128, exchangeable Mg (r= 0.5035, total nitrogen (r = 0.6167 and soil pH (r = 0.5221. SNS correlated positively with organic carbon (r = 0.5834, total nitrogen (r= 0.6101 and soil pH (r = 5150. Therefore applications of these agro-wastes are effective in improving soil properties, increasing soil carbon and nitrogen stock. From the results of the work, application of 10 t/ha PD + 10 t/ha SDA which was the treatment combination that improved soil properties and growth performances of okra than other treatments studied is

  10. Effect of varying the rate of partitioning of phenanthrene in nonaqueous-phase liquids on biodegradation in soil slurries

    OpenAIRE

    Ortega Calvo, J. J.; Birman, I.; M. Alexander

    1995-01-01

    A study was conducted to determine the influence of varying the rates of partitioning of phenanthrene from nonaqueous-phase liquids to water on its biodegradation. Partitioning rates from dibutyl phthalate and 2,2,4,4,6,8,8-heptamethylnonane were rapid in slurries of soil or aquifer solids that were shaken and were affected by the identity and volume of the non-aqueous-phase liquid. Concentrations of the surfactant Alfonic 810-60 that increased partitioning inhibited biodegradation. The rates...

  11. FACTORS AFFECTING THE REMOVAL OF A BASIC AND AN AZO DYE FROM ARTIFICIAL SOLUTIONS BY ADSORPTION USING ACTIVATED CARBON

    OpenAIRE

    Albroomi, H I; ElSayed, Mohamed; Baraka, A.; Abdelmaged, M A

    2014-01-01

    Decolourisation of wastewater, particularly from textile industries, is one of the major environmental concerns these days. Current methods for removing dyes from wastewater are costly and cannot effectively be used to treat wide range of such wastewater. This work describes the use of commercial available granular activated carbon (GAC) as an efficient adsorbent material for dyes removal. Aqueous solutions of various basic dye Methylene Blue (MB) and azo-dye Tartrazine with concentrations 5-...

  12. Non-deforestation fire vs. fossil fuel combustion: the source of CO2 emissions affects the global carbon cycle and climate responses

    Science.gov (United States)

    Landry, Jean-Sébastien; Damon Matthews, H.

    2016-04-01

    Non-deforestation fire - i.e., fire that is typically followed by the recovery of natural vegetation - is arguably the most influential disturbance in terrestrial ecosystems, thereby playing a major role in carbon exchanges and affecting many climatic processes. The radiative effect from a given atmospheric CO2 perturbation is the same for fire and fossil fuel combustion. However, major differences exist per unit of CO2 emitted between the effects of non-deforestation fire vs. fossil fuel combustion on the global carbon cycle and climate, because (1) fossil fuel combustion implies a net transfer of carbon from geological reservoirs to the atmospheric, oceanic, and terrestrial pools, whereas fire occurring in terrestrial ecosystems does not; (2) the average lifetime of the atmospheric CO2 increase is longer when originating from fossil fuel combustion compared to fire, due to the strong vegetation regrowth following fire disturbances in terrestrial ecosystems; and (3) other impacts, for example on land surface albedo, also differ between fire and fossil fuel combustion. The main purpose of this study is to illustrate the consequences from these fundamental differences between fossil fuel combustion and non-deforestation fires using 1000-year simulations of a coupled climate-carbon model with interactive vegetation. We assessed emissions from both pulse and stable fire regime changes, considering both the gross (carbon released from combustion) and net (fire-caused change in land carbon, also accounting for vegetation decomposition and regrowth, as well as climate-carbon feedbacks) fire CO2 emissions. In all cases, we found substantial differences from equivalent amounts of emissions produced by fossil fuel combustion. These findings suggest that side-by-side comparisons of non-deforestation fire and fossil fuel CO2 emissions - implicitly implying that they have similar effects per unit of CO2 emitted - should therefore be avoided, particularly when these comparisons

  13. A carbon sink pathway increases carbon productivity in cyanobacteria.

    Science.gov (United States)

    Oliver, John W K; Atsumi, Shota

    2015-05-01

    The burning of fossil reserves, and subsequent release of carbon into the atmosphere is depleting the supply of carbon-based molecules used for synthetic materials including plastics, oils, medicines, and glues. To provide for future society, innovations are needed for the conversion of waste carbon (CO2) into organic carbon useful for materials. Chemical production directly from photosynthesis is a nascent technology, with great promise for capture of CO2 using sunlight. To improve low yields, it has been proposed that photosynthetic capacity can be increased by a relaxation of bottlenecks inherent to growth. The limits of carbon partitioning away from growth within the cell and the effect of partitioning on carbon fixation are not well known. Here we show that expressing genes in a pathway between carbon fixation and pyruvate increases partitioning to 2,3-butanediol (23BD) and leads to a 1.8-fold increase in total carbon yield in the cyanobacterium Synechococcus elongatus PCC 7942. Specific 2,3-butanediol production increases 2.4-fold. As partitioning increases beyond 30%, it leads to a steep decline in total carbon yield. The data suggests a local maximum for carbon partitioning from the Calvin Benson cycle that is scalable with light intensity.

  14. Correspondence of bubble size and frother partitioning in flotation

    Institute of Scientific and Technical Information of China (English)

    张炜

    2014-01-01

    The size of bubbles created in the flotation process is of great importance to the efficiency of the mineral separation achieved. Meanwhile, it is believed that frother transport between phases is perhaps the most important reason for the interactive nature of the phenomena occurring in the bulk and froth phases in flotation, as frother adsorbed in the surface of rising bubbles is removed from the bulk phase and then released into the froth as a fraction of the bubbles burst. This causes the increased concentration in the froth compared to the bulk concentration, named as frother partitioning. Partitioning reflects the adsorption of frother on bubbles and how to influence bubble size is not known. There currently exists no such a topic aiming to link these two key parameters. To fill this vacancy, the correspondence between bubble size and frother partitioning was examined. Bubble size was measured by sampling-for-imaging (SFI) technique. Using total organic carbon (TOC) analysis to measure the frother partitioning between froth and bulk phases was determined. Measurements have shown, with no exceptions including four different frothers, higher frother concentration is in the bulk than in the froth. The results also show strong partitioning giving an increase in bubble size which implies there is a compelling relationship between these two, represented byCFroth/CBulk andD32. TheCFroth/CBulk andD32 curves show similar exponential decay relationships as a function of added frother in the system, strongly suggesting that the frother concentration gradient between the bulk solution and the bubble interface is the driving force contributing to bubble size reduction.

  15. Flow Partitioning in Fully Saturated Soil Aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaofan; Richmond, Marshall C.; Scheibe, Timothy D.; Perkins, William A.; Resat, Haluk

    2014-03-30

    Microbes play an important role in facilitating organic matter decomposition in soils, which is a major component of the global carbon cycle. Microbial dynamics are intimately coupled to environmental transport processes, which control access to labile organic matter and other nutrients that are needed for the growth and maintenance of microorganisms. Transport of soluble nutrients in the soil system is arguably most strongly impacted by preferential flow pathways in the soil. Since the physical structure of soils can be characterized as being formed from constituent micro aggregates which contain internal porosity, one pressing question is the partitioning of the flow among the “inter-aggregate” and “intra-aggregate” pores and how this may impact overall solute transport within heterogeneous soil structures. The answer to this question is particularly important in evaluating assumptions to be used in developing upscaled simulations based on highly-resolved mechanistic models. We constructed a number of diverse multi-aggregate structures with different packing ratios by stacking micro-aggregates containing internal pores and varying the size and shape of inter-aggregate pore spacing between them. We then performed pore-scale flow simulations using computational fluid dynamics methods to determine the flow patterns in these aggregate-of-aggregates structures and computed the partitioning of the flow through intra- and inter-aggregate pores as a function of the spacing between the aggregates. The results of these numerical experiments demonstrate that soluble nutrients are largely transported via flows through inter-aggregate pores. Although this result is consistent with intuition, we have also been able to quantify the relative flow capacity of the two domains under various conditions. For example, in our simulations, the flow capacity through the aggregates (intra-aggregate flow) was less than 2% of the total flow when the spacing between the aggregates

  16. Partitioning of organic production in marine plankton communities

    DEFF Research Database (Denmark)

    Conan, P.; Søndergaard, Morten; Kragh, T.;

    2007-01-01

    as a function of the plankton communities. Between 22% and 33% of the net production accumulated as new DOC. The higher values were found in the N-limited bags. The production of new dissolved organic nitrogen (DON) was variable over time, and short periods of positive production were followed by removal...... N limitation or forced the plankton communities to P limitation. Per added limiting nutrient, the diatom-dominated bags produced more particulate (POC) and dissolved organic carbon (DOC) than the other bags. However, the relative partitioning of net production to POC and DOC did not differ...... (negative production). Between 6% and 22% of the assimilated N was recovered as new DON in the N-replete bags, while the DON production was very low during N limitation. The community structure had no effects on nitrogen partitioning. Diatom dominance (+Si bags) resulted in P sequestration to particles...

  17. Atmospheric phenanthrene pollution modulates carbon allocation in red clover (Trifolium pratense L.)

    Energy Technology Data Exchange (ETDEWEB)

    Desalme, Dorine, E-mail: dorine.desalme@univ-fcomte.fr [Universite de Franche-Comte, CNRS, UMR 6249, Chrono-environnement, BP 71427, F-25211 Montbeliard Cedex (France); Binet, Philippe [Universite de Franche-Comte, CNRS, UMR 6249, Chrono-environnement, BP 71427, F-25211 Montbeliard Cedex (France); Epron, Daniel [Nancy Universite, UMR 1137, Ecologie et Ecophysiologie Forestieres, Faculte des Sciences, BP 70239, F- 54506 Vandoeuvre-les-Nancy Cedex (France); INRA, UMR 1137, Ecologie et Ecophysiologie Forestieres, Centre INRA de Nancy, F- 54280 Champenoux (France); Bernard, Nadine; Gilbert, Daniel; Toussaint, Marie-Laure [Universite de Franche-Comte, CNRS, UMR 6249, Chrono-environnement, BP 71427, F-25211 Montbeliard Cedex (France); Plain, Caroline [Nancy Universite, UMR 1137, Ecologie et Ecophysiologie Forestieres, Faculte des Sciences, BP 70239, F- 54506 Vandoeuvre-les-Nancy Cedex (France); INRA, UMR 1137, Ecologie et Ecophysiologie Forestieres, Centre INRA de Nancy, F- 54280 Champenoux (France); Chiapusio, Genevieve, E-mail: genevieve.chiapusio@univ-fcomte.fr [Universite de Franche-Comte, CNRS, UMR 6249, Chrono-environnement, BP 71427, F-25211 Montbeliard Cedex (France)

    2011-10-15

    The influence of atmospheric phenanthrene (PHE) exposure (160 {mu}g m{sup -3}) during one month on carbon allocation in clover was investigated by integrative (plant growth analysis) and instantaneous {sup 13}CO{sub 2} pulse-labelling approaches. PHE exposure diminished plant growth parameters (relative growth rate and net assimilation rate) and disturbed photosynthesis (carbon assimilation rate and chlorophyll content), leading to a 25% decrease in clover biomass. The root-shoot ratio was significantly enhanced (from 0.32 to 0.44). Photosynthates were identically allocated to leaves while less allocated to stems and roots. PHE exposure had a significant overall effect on the {sup 13}C partitioning among clover organs as more carbon was retained in leaves at the expense of roots and stems. The findings indicate that PHE decreases root exudation or transfer to symbionts and in leaves, retains carbon in a non-structural form diverting photosynthates away from growth and respiration (emergence of an additional C loss process). - Highlights: > Atmospheric PHE decreased growth, biomass partitioning and C allocation in clover. > C allocation was modified in favor of leaves but at the expense of roots and stems. > In roots, a decreased carbon exudation or allocation to symbionts was proposed. > In leaves, carbon was retained in a non-structural form as secondary metabolites. > BVOC emission was suggested as another loss process than respiration and exudation. - Exposure of clover to atmospheric PHE affected not only its growth, but also biomass partitioning and C allocation among its organs.

  18. Schmidt games and Markov partitions

    International Nuclear Information System (INIS)

    Let T be a C2-expanding self-map of a compact, connected, C∞, Riemannian manifold M. We correct a minor gap in the proof of a theorem from the literature: the set of points whose forward orbits are nondense has full Hausdorff dimension. Our correction allows us to strengthen the theorem. Combining the correction with Schmidt games, we generalize the theorem in dimension one: given a point x0 in M, the set of points whose forward orbit closures miss x0 is a winning set. Finally, our key lemma, the no matching lemma, may be of independent interest in the theory of symbolic dynamics or the theory of Markov partitions

  19. Methodology for optimally sized centrifugal partition chromatography columns.

    Science.gov (United States)

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

    2015-04-01

    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.

  20. Partitioning of copy-number genotypes in pedigrees

    Directory of Open Access Journals (Sweden)

    Andelfinger Gregor U

    2010-05-01

    Full Text Available Abstract Background Copy number variations (CNVs and polymorphisms (CNPs have only recently gained the genetic community's attention. Conservative estimates have shown that CNVs and CNPs might affect more than 10% of the genome and that they may be at least as important as single nucleotide polymorphisms in assessing human variability. Widely used tools for CNP analysis have been implemented in Birdsuite and PLINK for the purpose of conducting genetic association studies based on the unpartitioned total number of CNP copies provided by the intensities from Affymetrix's Genome-Wide Human SNP Array. Here, we are interested in partitioning copy number variations and polymorphisms in extended pedigrees for the purpose of linkage analysis on familial data. Results We have developed CNGen, a new software for the partitioning of copy number polymorphism using the integrated genotypes from Birdsuite with the Affymetrix platform. The algorithm applied to familial trios or extended pedigrees can produce partitioned copy number genotypes with distinct parental alleles. We have validated the algorithm using simulations on a complex pedigree structure using frequencies calculated from a real dataset of 300 genotyped samples from 42 pedigrees segregating a congenital heart defect phenotype. Conclusions CNGen is the first published software for the partitioning of copy number genotypes in pedigrees, making possible the use CNPs and CNVs for linkage analysis. It was implemented with the Python interpreter version 2.5.2. It was successfully tested on current Linux, Windows and Mac OS workstations.

  1. Unsupervised segmentation of MRI knees using image partition forests

    Science.gov (United States)

    Marčan, Marija; Voiculescu, Irina

    2016-03-01

    Nowadays many people are affected by arthritis, a condition of the joints with limited prevention measures, but with various options of treatment the most radical of which is surgical. In order for surgery to be successful, it can make use of careful analysis of patient-based models generated from medical images, usually by manual segmentation. In this work we show how to automate the segmentation of a crucial and complex joint -- the knee. To achieve this goal we rely on our novel way of representing a 3D voxel volume as a hierarchical structure of partitions which we have named Image Partition Forest (IPF). The IPF contains several partition layers of increasing coarseness, with partitions nested across layers in the form of adjacency graphs. On the basis of a set of properties (size, mean intensity, coordinates) of each node in the IPF we classify nodes into different features. Values indicating whether or not any particular node belongs to the femur or tibia are assigned through node filtering and node-based region growing. So far we have evaluated our method on 15 MRI knee images. Our unsupervised segmentation compared against a hand-segmented gold standard has achieved an average Dice similarity coefficient of 0.95 for femur and 0.93 for tibia, and an average symmetric surface distance of 0.98 mm for femur and 0.73 mm for tibia. The paper also discusses ways to introduce stricter morphological and spatial conditioning in the bone labelling process.

  2. Partitioning of some volatile organic compounds between air and waste water from 288 To 303 K

    International Nuclear Information System (INIS)

    This study investigated effects of temperature and organic content in wastewater on the air-liquid partitions of isopropanol, acetone and p-xylene. A supernatant obtained from centrifugation of activated sludge as the test liquid. Dimensionless Henry's law constants (KH) in a deionized water and dimensionless apparent Henry's law constants (KH) in the supernatant containing one of the VOCs were measured at 288 to 303 K. KH for all the three VOCs decrease with an increase in the dissolved total organic carbon (TOC) concentration in the wastewater. A model correlating KH with the organic carbon-water partition coefficient, TOC concentration and temperature was derived

  3. On the partition dimension of trees

    CERN Document Server

    Rodriguez-Velazquez, Juan A; Lemanska, Magdalena

    2011-01-01

    Given an ordered partition $\\Pi =\\{P_1,P_2, ...,P_t\\}$ of the vertex set $V$ of a connected graph $G=(V,E)$, the \\emph{partition representation} of a vertex $v\\in V$ with respect to the partition $\\Pi$ is the vector $r(v|\\Pi)=(d(v,P_1),d(v,P_2),...,d(v,P_t))$, where $d(v,P_i)$ represents the distance between the vertex $v$ and the set $P_i$. A partition $\\Pi$ of $V$ is a \\emph{resolving partition} of $G$ if different vertices of $G$ have different partition representations, i.e., for every pair of vertices $u,v\\in V$, $r(u|\\Pi)\

  4. On the partition dimension of unicyclic graphs

    CERN Document Server

    Rodriguez-Velazquez, Juan A; Fernau, Henning

    2011-01-01

    Given an ordered partition $\\Pi =\\{P_1,P_2, ...,P_t\\}$ of the vertex set $V$ of a connected graph $G=(V,E)$, the \\emph{partition representation} of a vertex $v\\in V$ with respect to the partition $\\Pi$ is the vector $r(v|\\Pi)=(d(v,P_1),d(v,P_2),...,d(v,P_t))$, where $d(v,P_i)$ represents the distance between the vertex $v$ and the set $P_i$. A partition $\\Pi$ of $V$ is a \\emph{resolving partition} if different vertices of $G$ have different partition representations, i.e., for every pair of vertices $u,v\\in V$, $r(u|\\Pi)\

  5. Soil-Gas Identification of Environmental Factors Affecting CO2 Concentrations Beneath a Playa Wetland: Implications for Soil-Gas Monitoring at Carbon Storage Sites

    Science.gov (United States)

    Romanak, K.; Bennett, P.

    2009-12-01

    significant carbonate dissolution resulting from reaction of CO2 with infiltrating water and soil carbonate. Results of the study show that the degree of carbon reactivity within a near-surface environment limits the effectiveness of shallow subsurface and surface-flux soil-gas monitoring at engineered carbon repositories. When carbon reactivity is at a maximum, CO2 cycling is complex and input of exogenous CO2 into the system is difficult to constrain and quantify. A summary of the factors that define carbon reactivity and their affects on near-surface soil-gas monitoring at geologic carbon storage sites is presented, along with recommendations for site evaluation with regard to near-surface monitoring.

  6. Energy Partitioning and Thyroid Hormone Levels During Salmonella enteritidis Infections in Pullets with High or Low Residual Feed Intake

    NARCIS (Netherlands)

    Eerden, van E.; Brand, van den H.; Heetkamp, M.J.W.; Decuypere, M.P.; Kemp, B.

    2006-01-01

    This experiment was conducted to investigate whether feed efficiency, as measured by residual feed intake as a phenotypic trait, affects energy partitioning in pullets that have received Salmonella inoculation as an immune challenge. In each of 8 trials, energy partitioning was measured during 5 wk

  7. Study of variables affecting extraction of organic solvents from solid sorbent sampling media using supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, R.A. [Dept. of Health and Human Services, U.S. Public Health Service, Centers for Disease Control and Prevention, National Inst. for Occupational Safety and Health, Div. of Physical Sciences and Engineering, Cincinnati, OH (United States); Shulman, S.A. [Dept. of Health and Human Services, U.S. Public Health Service, Centers for Disease Control and Prevention, National Inst. for Occupational Safety and Health, Div. of Physical Sciences and Engineering, Cincinnati, OH (United States)

    1996-06-01

    The extraction of our solvents from three sorbents, using supercritical carbon dioxide was studied. Toluene and isooctane were extracted from Anasorb 747{sup R}, a synthetic carbon; 1-butanol from silica gel; and 2-nitropropane from Anasorb 727{sup R}, a porous organic polymer. Preliminary experiments indicated that dynamic extraction was required; these experiments also fixed the duration of extraction of the analytes. All extractions were performed at 1.0 mL min{sup -1}. The temperature and density of the supercritical extraction fluid were then varied, according to a fractional factorial statistical design. The amounts remaining on the sorbent were determined via solvent desorption of the analytes and gas chromatography of the eluents. The fraction extracted data were modeled as a function of temperature and density according to a thermodynamic approach that permitted computation of constant-density enthalpies of desorption. This study indicates a significant temperature- and density-dependence for quantitative extraction of isooctane and toluene from Anasorb 747{sup R} and 1-butanol from silica gel, with no measurable temperature- or density-dependence for extraction of 2-nitropropane from Anasorb 727{sup R}. The extracted analytes were also collected via cryotrapping; only higher level masses of 1-butanol were quantitativley recovered. The dependence of the extraction efficiency on the thimble volumes passed over the matrix is discussed. (orig.)

  8. Scheduling Driven Partitioning of Heterogeneous Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    1998-01-01

    In this paper we present an algorithm for system level hardware/software partitioning of heterogeneous embedded systems. The system is represented as an abstract graph which captures both data-flow and the flow of control. Given an architecture consisting of several processors, ASICs and shared...... busses, our partitioning algorithm finds the partitioning with the smallest hardware cost and is able to predict and guarantee the performance of the system in terms of worst case delay....

  9. The partitioning of iodides into steam

    International Nuclear Information System (INIS)

    In order to estimate the likely releases of radioactive iodine during steam generator tube rupture (SGTR) faults, it is necessary to know the relevant partition coefficients as a function of temperature and solution composition. It has been suggested previously that, under SGTR fault conditions, partitioning of free or ion-paired I- into the steam may be more extensive than that for molecular HI. This report uses available information on the partitioning of iodides and other salts to provide a means of estimating the partition coefficient of the iodide ion as a function of boric acid concentration and temperature. (author)

  10. Generating Milton Babbitt's all-partition arrays

    DEFF Research Database (Denmark)

    Bemman, Brian; Meredith, David

    2016-01-01

    In most of Milton Babbitt's (1916–2011) works written since the early 1960s, both the pitch and rhythmic content is organized according to a highly constrained structure known as the all-partition array. The all-partition array provides a framework that ensures that as many different forms of a...... algorithm to generate the specific all-partition arrays used in three of Babbitt’s works. Finally, we evaluate the algorithm and the heuristics in terms of how well they predict the sequences of integer partitions used in two of Babbitt’s works. We also explore the effect of the heuristics on the...

  11. Enumeration of Cylindric Plane Partitions - part I

    CERN Document Server

    Langer, Robin

    2012-01-01

    Cylindric plane partitions may be thought of as a natural generalization of reverse plane partitions. A generating series for the enumeration of cylindric plane partitions was recently given by Borodin. The first result of this paper is a $(q,t)$-analog of Borodin's identity which extends previous work by Okada in the reverse plane partition case. Our proof uses commutation relations for $(q,t)$-vertex operators acting on Macdonald polynomials as given by Garsia, Haiman and Tesla. The second result of this paper is an explicit combinatorial interpreation of the $(q,t)$-Macdonald weight in terms of a non-intersecting lattice path model on the cylinder.

  12. Hemlock woolly adelgid (Adelges tsugae) infestation affects water and carbon relations of eastern hemlock (Tsuga canadensis) and Carolina hemlock (Tsuga caroliniana).

    Science.gov (United States)

    Domec, Jean-Christophe; Rivera, Laura N; King, John S; Peszlen, Ilona; Hain, Fred; Smith, Benjamin; Frampton, John

    2013-07-01

    Hemlock woolly adelgid (HWA) is an exotic insect pest causing severe decimation of native hemlock trees. Extensive research has been conducted on the ecological impacts of HWA, but the exact physiological mechanisms that cause mortality are not known. Water relations, anatomy and gas exchange measurements were assessed on healthy and infested eastern (Tsuga canadensis) and Carolina (Tsuga caroliniana) hemlock trees. These data were then used in a mechanistic model to test whether the physiological responses to HWA infestation were sufficiently significant to induce changes in whole-plant water use and carbon uptake. The results indicated coordinated responses of functional traits governing water relations in infested relative to healthy trees. In response to HWA, leaf water potential, carbon isotope ratios, plant hydraulic properties and stomatal conductance were affected, inducing a reduction in tree water use by > 40% and gross primary productivity by 25%. Anatomical changes also appeared, including the activation of traumatic cells. HWA infestation had a direct effect on plant water relations. Despite some leaf compensatory mechanisms, such as an increase in leaf hydraulic conductance and nitrogen content, tree water use and carbon assimilation were diminished significantly in infested trees, which could contribute to tree mortality.

  13. Carbon nanotubes affect the toxicity of CuO nanoparticles to denitrification in marine sediments by altering cellular internalization of nanoparticle

    Science.gov (United States)

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

    2016-06-01

    Denitrification is an important pathway for nitrate transformation in marine sediments, and this process has been observed to be negatively affected by engineered nanomaterials. However, previous studies only focused on the potential effect of a certain type of nanomaterial on microbial denitrification. Here we show that the toxicity of CuO nanoparticles (NPs) to denitrification in marine sediments is highly affected by the presence of carbon nanotubes (CNTs). It was found that the removal efficiency of total NOX--N (NO3--N and NO2--N) in the presence of CuO NPs was only 62.3%, but it increased to 81.1% when CNTs appeared in this circumstance. Our data revealed that CuO NPs were more easily attached to CNTs rather than cell surface because of the lower energy barrier (3.5 versus 36.2 kT). Further studies confirmed that the presence of CNTs caused the formation of large, incompact, non-uniform dispersed, and more negatively charged CuO-CNTs heteroaggregates, and thus reduced the nanoparticle internalization by cells, leading to less toxicity to metabolism of carbon source, generation of reduction equivalent, and activities of nitrate reductase and nitrite reductase. These results indicate that assessing nanomaterial-induced risks in real circumstances needs to consider the “mixed” effects of nanomaterials.

  14. A meta-analysis of carbon nanotube pulmonary toxicity studies--how physical dimensions and impurities affect the toxicity of carbon nanotubes.

    Science.gov (United States)

    Gernand, Jeremy M; Casman, Elizabeth A

    2014-03-01

    This article presents a regression-tree-based meta-analysis of rodent pulmonary toxicity studies of uncoated, nonfunctionalized carbon nanotube (CNT) exposure. The resulting analysis provides quantitative estimates of the contribution of CNT attributes (impurities, physical dimensions, and aggregation) to pulmonary toxicity indicators in bronchoalveolar lavage fluid: neutrophil and macrophage count, and lactate dehydrogenase and total protein concentrations. The method employs classification and regression tree (CART) models, techniques that are relatively insensitive to data defects that impair other types of regression analysis: high dimensionality, nonlinearity, correlated variables, and significant quantities of missing values. Three types of analysis are presented: the RT, the random forest (RF), and a random-forest-based dose-response model. The RT shows the best single model supported by all the data and typically contains a small number of variables. The RF shows how much variance reduction is associated with every variable in the data set. The dose-response model is used to isolate the effects of CNT attributes from the CNT dose, showing the shift in the dose-response caused by the attribute across the measured range of CNT doses. It was found that the CNT attributes that contribute the most to pulmonary toxicity were metallic impurities (cobalt significantly increased observed toxicity, while other impurities had mixed effects), CNT length (negatively correlated with most toxicity indicators), CNT diameter (significantly positively associated with toxicity), and aggregate size (negatively correlated with cell damage indicators and positively correlated with immune response indicators). Increasing CNT N2 -BET-specific surface area decreased toxicity indicators.

  15. HPAM: Hirshfeld partitioned atomic multipoles

    Science.gov (United States)

    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

  16. Assimilate partitioning during reproductive growth

    International Nuclear Information System (INIS)

    Leaves having various phyllotactic relationships to fruitlets were labeled for 1 hour with 10/sub r/Ci of 14CO2. Fruitlets were also labeled. Fruitlets did fix 14CO2. 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

  17. Comportement des déchets graphite en situation de stockage : Relâchement et répartition des espèces organiques et inogarniques du carbone 14 et du tritium en milieu alcalin

    OpenAIRE

    Vende, Ludivine

    2012-01-01

    23000 tons of graphite wastes will be generated during dismantling of the first generation of French reactors (9 gas cooled reactors). These wastes are classified as Long Lived Low Level wastes (LLW-LL). As requested by the law, the French National Radioactive Waste Management Agency (Andra) is studying concepts of low-depth disposals.In this work we focus on carbon 14, the main long-lived radionuclide in graphite waste (5730y), but also on tritium, which is the main contributor to the radioa...

  18. Substitution of valine for histidine 265 in carbon monoxide dehydrogenase from Rhodospirillum rubrum affects activity and spectroscopic states.

    Science.gov (United States)

    Spangler, N J; Meyers, M R; Gierke, K L; Kerby, R L; Roberts, G P; Ludden, P W

    1998-02-13

    In carbon monoxide dehydrogenase (CODH) from Rhodospirillum rubrum, histidine 265 was replaced with valine by site-directed mutagenesis of the cooS gene. The altered form of CODH (H265V) had a low nickel content and a dramatically reduced level of catalytic activity. Although treatment with NiCl2 and CoCl2 increased the activity of H265V CODH by severalfold, activity levels remained more than 1000-fold lower than that of wild-type CODH. Histidine 265 was not essential for the formation and stability of the Fe4S4 clusters. The Km and KD for CO as well as the KD for cyanide were relatively unchanged as a result of the amino acid substitution in CODH. The time-dependent reduction of the [Fe4S4]2+ clusters by CO occurred on a time scale of hours, suggesting that, as a consequence of the mutation, a rate-limiting step had been introduced prior to the transfer of electrons from CO to the cubanes in centers B and C. EPR spectra of H265V CODH lacked the gav = 1.86 and gav = 1.87 signals characteristic of reduced forms of the active site (center C) of wild-type CODH. This indicates that the electronic properties of center C have been modified possibly by the disruption or alteration of the ligand-mediated interaction between the nickel site and Fe4S4 chromophore. PMID:9461598

  19. Changes in foliar carbon isotope composition and seasonal stomatal conductance reveal adaptive traits in Mediterranean coppices affected by drought

    Institute of Scientific and Technical Information of China (English)

    Giovanni Di Matteo; Luigi Perini; Paolo Atzori; Paolo De Angelis; Tiziano Mei; Giada Bertini; Gianfranco Fabbio; Giuseppe Scarascia Mugnozza

    2014-01-01

    We estimated water-use efficiency and potential photosyn-thetic assimilation of Holm oak (Quercus ilex L.) on slopes of NW and SW aspects in a replicated field test examining the effects of intensifying drought in two Mediterranean coppice forests. We used standard tech-niques for quantifying gas exchange and carbon isotopes in leaves and analyzed total chlorophyll, carotenoids and nitrogen in leaves collected from Mediterranean forests managed under the coppice system. We pos-tulated that responses to drought of coppiced trees would lead to differ-ential responses in physiological traits and that these traits could be used by foresters to adapt to predicted warming and drying in the Mediterra-nean area. We observed physiological responses of the coppiced trees that suggested acclimation in photosynthetic potential and water-use effi-ciency:(1) a significant reduction in stomatal conductance (p<0.01) was recorded as the drought increased at the SW site;(2) foliarδ13C increased as drought increased at the SW site (p<0.01);(3) variations in levels of carotenoids and foliar nitrogen, and differences in foliar morphology were recorded, and were tentatively attributed to variation in photosyn-thetic assimilation between sites. These findings increase knowledge of the capacity for acclimation of managed forests in the Mediterranean region of Europe.

  20. Solar regeneration of powdered activated carbon impregnated with visible-light responsive photocatalyst: factors affecting performances and predictive model.

    Science.gov (United States)

    Yap, Pow-Seng; Lim, Teik-Thye

    2012-06-01

    This study demonstrated a green technique to regenerate spent powdered activated carbon (AC) using solar photocatalysis. The AC was impregnated with a photocatalyst photoexcitable under visible-light irradiation to yield a solar regenerable composite, namely nitrogen-doped titanium dioxide (N-TiO(2)/AC). This composite exhibited bifunctional adsorptive-photocatalytic characteristics. Contaminants of emerging environmental concern, i.e. bisphenol-A (BPA), sulfamethazine (SMZ) and clofibric acid (CFA) which exhibited varying affinities for AC were chosen as target pollutants. The adsorption of BPA and SMZ by the N-TiO(2)/AC was significantly higher than that of CFA. The performance of solar photocatalytic regeneration (SPR) of the spent N-TiO(2)/AC composite generally increased with light intensity, N-TiO(2) loading and temperature. The regeneration efficiency (RE) for CFA-loaded spent composite was the highest compared to the other pollutant-loaded spent composites, achieving 77% within 8h of solar irradiation (765 W m(-2)). The rate-limiting process was pollutant desorption from the interior AC sorption sites. A kinetic model was developed to predict the transient concentration of the sorbate remaining in the spent composite during SPR. Comparison studies using solvent extraction technique indicated a different order of RE for the three pollutants, attributable to their varying solubilities in the aqueous and organic solvents. PMID:22464146

  1. Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China.

    Science.gov (United States)

    Su, Hongxin; Feng, Jinchao; Axmacher, Jan C; Sang, Weiguo

    2015-01-01

    We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning. PMID:25766381

  2. Partitioning of resveratrol between pentane and DMSO

    DEFF Research Database (Denmark)

    Shen, Chen; Stein, Paul C.; Klösgen-Buchkremer, Beate Maria

    2015-01-01

    Partitioning of trans-3,5,4′-trihydroxy-stilbene (resveratrol) between n-pentane and DMSO was investigated as a contribution to understand the interaction between resveratrol and biomembranes. In order to determine the partition coefficient P* of resveratrol between pentane and DMSO, resveratrol...

  3. Partition functions for supersymmetric black holes

    NARCIS (Netherlands)

    J. Manschot

    2008-01-01

    This thesis presents a number of results on partition functions for four-dimensional supersymmetric black holes. These partition functions are important tools to explain the entropy of black holes from a microscopic point of view. Such a microscopic explanation was desired after the association of a

  4. Plasmid and chromosome partitioning: surprises from phylogeny

    DEFF Research Database (Denmark)

    Gerdes, Kenn; Møller-Jensen, Jakob; Bugge Jensen, Rasmus

    2000-01-01

    and chromosomes from prokaryotic organisms. All known plasmid-encoded par loci specify three components: a cis-acting centromere-like site and two trans-acting proteins that form a nucleoprotein complex at the centromere (i.e. the partition complex). The proteins are encoded by two genes in an operon...... that is autoregulated by the par-encoded proteins. In all cases, the upstream gene encodes an ATPase that is essential for partitioning. Recent cytological analyses indicate that the ATPases function as adaptors between a host-encoded component and the partition complex and thereby tether plasmids and chromosomal...... origin regions to specific subcellular sites (i.e. the poles or quarter-cell positions). Two types of partitioning ATPases are known: the Walker-type ATPases encoded by the par/sop gene family (type I partitioning loci) and the actin-like ATPase encoded by the par locus of plasmid R1 (type II...

  5. Determination of partition behavior of organic surrogates between paperboard packaging materials and air.

    Science.gov (United States)

    Triantafyllou, V I; Akrida-Demertzi, K; Demertzis, P G

    2005-06-01

    The suitability of recycled paperboard packaging materials for direct food contact applications is a major area of investigation. Chemical contaminants (surrogates) partitioning between recycled paper packaging and foods may affect the safety and health of the consumer. The partition behavior of all possible organic compounds between cardboards and individual foodstuffs is difficult and too time consuming for being fully investigated. Therefore it may be more efficient to determine these partition coefficients indirectly through experimental determination of the partitioning behavior between cardboard samples and air. In this work, the behavior of organic pollutants present in a set of two paper and board samples intended to be in contact with foods was studied. Adsorption isotherms have been plotted and partition coefficients between paper and air have been calculated as a basis for the estimation of their migration potential into food. Values of partition coefficients (Kpaper/air) from 47 to 1207 were obtained at different temperatures. For the less volatile surrogates such as dibutyl phthalate and methyl stearate higher Kpaper/air values were obtained. The adsorption curves showed that the more volatile substances are partitioning mainly in air phase and increasing the temperature from 70 to 100 degrees C their concentrations in air (Cair) have almost doubled. The analysis of surrogates was performed with a method based on solvent extraction and gas chromatographic-flame ionization detection (GC-FID) quantification. PMID:15988989

  6. Ecosystem partitioning of 15N-glycine after long-term climate and nutrient manipulations, plant clipping and addition of labile carbon in a subarctic heath tundra

    DEFF Research Database (Denmark)

    Sørensen, Pernille Lærkedal; Michelsen, Anders; Jonasson, Sven Evert

    2008-01-01

    Low temperatures and high soil moisture restrict cycling of organic matter in arctic soils, but also substrate quality, i.e. labile carbon (C) availability, exerts control on microbial activity. Plant exudation of labile C may facilitate microbial growth and enhance microbial immobilization......, microorganisms and plants. There were few effects of long-term warming and fertilization on soil and plant pools. However, fertilization increased soil and plant N pools and increased pool dilution of the added 15N label. In all treatments, microbes immobilized a major part of the added 15N shortly after label...... addition. However, plants exerted control on the soil inorganic N concentrations and recovery of total dissolved 15N (TD15N), and likewise the microbes reduced these soil pools, but only when fed with labile C. Soil microbes in clipped plots were primarily C limited, and the findings of reduced N...

  7. Subterranean ventilation: a key but poorly known process affecting the carbon balance of semi-arid ecosystems

    Science.gov (United States)

    López Ballesteros, Ana; Sánchez Cañete, Enrique P.; Serrano Ortiz, Penélope; Kowalski, Andrew S.; Oyonarte, Cecilio; Domingo, Francisco

    2016-04-01

    Subterranean ventilation, conceived as the advective transport of CO2-rich air from the vadose zone to the atmosphere through a porous media (i.e. soil or snow; Sánchez-Cañete et al., 2013), has arisen as an important process contributing to the carbon (C) balance of Mediterranean ecosystems (Kowalski et al., 2008; Sánchez-Cañete et al., 2011; Serrano-Ortiz et al., 2014), apart from other well-known biotic processes (i.e. plant photosynthesis, autotrophic and heterotrophic respiration). Recent studies have linked this subterranean CO2 release to fluctuations in the friction velocity or wind speed under drought conditions when water-free soil pores enable air transport (Rey et al., 2012a, 2013), however, barometric pressure variations has been suggested as another important driver (Sánchez-Cañete et al., 2013). In this study, we investigate this process in newly studied semi-arid grassland located in SE Spain, as the ideal ecosystem to do so given the great length of the dry season and the slight biotic activity limited to the winter season. Preliminary results, based on unpublished analyzed eddy covariance data and subterranean CO2 molar fraction measurements, confirm the presence of ventilation events from May to October for seven years 2009-2015. During these events, increases in the friction velocity correlates with sizeable CO2 emissions of up to ca.10 μmol m‑2 s‑1, and CO2 molar fraction regularly drops 2000-3000 ppm just after the turbulence peak, at several depths below the soil surface (0.15 and 1.5 m). Additionally, during the driest period (July-August), the friction velocity explains from 37% to 57% of the net C emission variability. On the other hand, the model residuals do not show a significant relationship, neither with air pressure nor with soil water content. Overall, the results found in this newly monitored site demonstrate, as shown by past research, the relevance of subterranean ventilation as a key process in the C balance of

  8. Self-complementary plane partitions by Proctor's minuscule method

    OpenAIRE

    Kuperberg, Greg

    1994-01-01

    A method of Proctor [European J. Combin. 5 (1984), no. 4, 331-350] realizes the set of arbitrary plane partitions in a box and the set of symmetric plane partitions as bases of linear representations of Lie groups. We extend this method by realizing transposition and complementation of plane partitions as natural linear transformations of the representations, thereby enumerating symmetric plane partitions, self-complementary plane partitions, and transpose-complement plane partitions in a new...

  9. Five-year changes in soil organic carbon and total nitrogen in coastal wetlands affected by flow-sediment regulation in a Chinese delta

    Science.gov (United States)

    Wang, Junjing; Bai, Junhong; Zhao, Qingqing; Lu, Qiongqiong; Xia, Zhijian

    2016-01-01

    Changes in the sources and sinks of soil organic carbon (SOC) and total nitrogen (TN) in wetland soils as indicators of soil quality and climate change have received attention worldwide. Soil samples were collected in 2007 and 2012 in the coastal wetlands of the Yellow River Delta and the SOC and TN were determined to investigate a five-year change in their content and stock in these wetlands as affected by flow-sediment regulation. Our results revealed that the soils in 2007 exhibited greater electrical conductivities, SOC content and density, and ammonium nitrogen (NH4+-N) levels in the top 10 cm soils (p < 0.05) compared with the soils in 2012. In general, the SOC and TN contents decreased with increasing soil depth. However, the highest ratios of soil organic carbon and total nitrogen (molar C/N ratios) were observed in the 30–40 cm soil layer. A significant SOC loss occurred (p < 0.05) in top 10 cm soils, but only a small change in SOC in the top 50 cm soils. Comparatively, TN levels did not show significant differences in the study period. PMID:26879008

  10. Partitioning Gas Tracer Technology for Measuring Water in Landfills

    Science.gov (United States)

    Briening, M. L.; Jakubowitch, A.; Imhoff, P. T.; Chiu, P. C.; Tittlebaum, M. E.

    2002-12-01

    Unstable landfills can result in significant environmental contamination and can become a risk to public health. To reduce this risk, water may be added to landfills to ensure that enough moisture exists for biodegradation of organic wastes. In this case risks associated with future breaks in the landfill cap are significantly reduced because organic material is degraded more rapidly. To modify moisture conditions and enhance biodegradation, leachate is typically collected from the bottom of the landfill and then recirculated near the top. It is difficult, though, to know how much leachate to add and where to add it to achieve uniform moisture conditions. This situation is exacerbated by the heterogeneous nature of landfill materials, which is known to cause short circuiting of infiltrating water, a process that has been virtually impossible to measure or model. Accurate methods for measuring the amount of water in landfills would be valuable aids for implementing leachate recirculation systems. Current methods for measuring water are inadequate, though, since they provide point measurements and are frequently affected by heterogeneity of the solid waste composition and solid waste compaction. The value of point measurements is significantly reduced in systems where water flows preferentially, such as in landfills. Here, spatially integrated measurements might be of greater value. In this research we are evaluating a promising technology, the partitioning gas tracer test, to measure the water saturation within landfills, the amount of free water in solid waste divided by the volume of the voids. The partitioning gas tracer test was recently developed by researchers working in the vadose zone. In this methodology two gas tracers are injected into a landfill. One tracer is non-reactive with landfill materials, while the second partitions into and out of free water trapped within the pore space of the solid waste. Chromatographic separation of the tracers occurs

  11. DYNAMIC TASK PARTITIONING MODEL IN PARALLEL COMPUTING

    Directory of Open Access Journals (Sweden)

    Javed Ali

    2012-04-01

    Full Text Available Parallel computing systems compose task partitioning strategies in a true multiprocessing manner. Such systems share the algorithm and processing unit as computing resources which leads to highly inter process communications capabilities. The main part of the proposed algorithm is resource management unit which performs task partitioning and co-scheduling .In this paper, we present a technique for integrated task partitioning and co-scheduling on the privately owned network. We focus on real-time and non preemptive systems. A large variety of experiments have been conducted on the proposed algorithm using synthetic and real tasks. Goal of computation model is to provide a realistic representation of the costs of programming The results show the benefit of the task partitioning. The main characteristics of our method are optimal scheduling and strong link between partitioning, scheduling and communication. Some important models for task partitioning are also discussed in the paper. We target the algorithm for task partitioning which improve the inter process communication between the tasks and use the recourses of the system in the efficient manner. The proposed algorithm contributes the inter-process communication cost minimization amongst the executing processes.

  12. Reinforcement learning with partitioning function system

    Institute of Scientific and Technical Information of China (English)

    李伟; 叶庆泰; 朱昌明

    2004-01-01

    The size of state-space is the limiting factor in applying reinforcement learning algorithms to practical cases. A reinforcement learning system with partitioning function (RLWPF) is established, in which statespace is partitioned into several regions. Inside the performance principle of RLWPF is based on a Semi-Markov decision process and has general significance. It can be applied to any reinforcement learning with a large statespace. In RLWPF, the partitioning module dispatches agents into different regions in order to decrease the state-space of each agent. This article proves the convergence of the SARSA algorithm for a Semi-Markov decision process, ensuring the convergence of RLWPF by analyzing the equivalence of two value functions in two Semi-Markov decision processes before and after partitioning. This article can show that the optimal policy learned by RLWPF is consistent with prior domain knowledge. An elevator group system is devised to decrease the average waiting time of passengers. Four agents control four elevator cars respectively. Based on RLWPF, a partitioning module is developed through defining a uniform round trip time as the partitioning criteria, making the wait time of most passengers more or less identical then elevator cars should only answer hall calls in their own region. Compared with ordinary elevator systems and reinforcement learning systems without partitioning module, the performance results show the advantage of RLWPF.

  13. Exposure to ultrafine carbon particles at levels below detectable pulmonary inflammation affects cardiovascular performance in spontaneously hypertensive rats

    Directory of Open Access Journals (Sweden)

    Bader Michael

    2008-12-01

    Full Text Available Abstract Background Exposure to particulate matter is a risk factor for cardiopulmonary disease but the underlying molecular mechanisms remain poorly understood. In the present study we sought to investigate the cardiopulmonary responses on spontaneously hypertensive rats (SHRs following inhalation of UfCPs (24 h, 172 μg·m-3, to assess whether compromised animals (SHR exhibit a different response pattern compared to the previously studied healthy rats (WKY. Methods Cardiophysiological response in SHRs was analyzed using radiotelemetry. Blood pressure (BP and its biomarkers plasma renin-angiotensin system were also assessed. Lung and cardiac mRNA expressions for markers of oxidative stress (hemeoxygenase-1, blood coagulation (tissue factor, plasminogen activator inhibitor-1, and endothelial function (endothelin-1, and endothelin receptors A and B were analyzed following UfCPs exposure in SHRs. UfCPs-mediated inflammatory responses were assessed from broncho-alveolar-lavage fluid (BALF. Results Increased BP and heart rate (HR by about 5% with a lag of 1–3 days were detected in UfCPs exposed SHRs. Inflammatory markers of BALF, lung (pulmonary and blood (systemic were not affected. However, mRNA expression of hemeoxygenase-1, endothelin-1, endothelin receptors A and B, tissue factor, and plasminogen activator inhibitor showed a significant induction (~2.5-fold; p Conclusion Our finding shows that UfCPs exposure at levels which does not induce detectable pulmonary neutrophilic inflammation, triggers distinct effects in the lung and also at the systemic level in compromised SHRs. These effects are characterized by increased activity of plasma renin-angiotensin system and circulating white blood cells together with moderate increases in the BP, HR and decreases in heart rate variability. This systemic effect is associated with pulmonary, but not cardiac, mRNA induction of biomarkers reflective of oxidative stress; activation of vasoconstriction

  14. In situ synchrotron study on the interplay between martensite formation, texture evolution and load partitioning in low-alloyed TRIP steels

    International Nuclear Information System (INIS)

    Highlights: → In situ probing the micromechanical response of TRIP steels using high-energy X-rays. → Link between metastable austenite evolution in bulk and material mechanical response. → Higher aluminium content yields larger austenite transformation range and formability. → The austenite stability depends strongly on grain orientation. → Load partitioning between constituent phases is affected by the transformation. - Abstract: We have studied the micromechanical behaviour of two low-alloyed multiphase TRIP steels with different aluminium contents by performing in situ high-energy X-ray diffraction experiments at a synchrotron source under increasing tensile stress levels. A detailed analysis of the two-dimensional diffraction data has allowed us to unravel the interplay between the martensite formation, the texture evolution and the load partitioning, and to correlate the observed behaviour to the macroscopic response of the material. The high aluminium content TRIP steel grade presents a higher volume fraction of retained austenite at room temperature that transforms more gradually into martensite under deformation, providing a larger uniform elongation. The comparison between the observed transformation behaviour and the texture evolution indicates that the component along the loading direction corresponds to a low critical stress for the transformation. The evolution of the elastic strains revealed the occurrence of a significant load partitioning before reaching the macroscopic yield strength, which becomes more pronounced in the plastic regime due to the progressive yielding of the different grains in the polycrystalline material. This opens the door to tailor the austenite stability by altering the distribution in grain size, local carbon content, and grain orientation in order to produce the optimal load partitioning and work hardening for improved combinations of strength and formability in low-alloyed TRIP steels.

  15. Polymers as reference partitioning phase: polymer calibration for an analytically operational approach to quantify multimedia phase partitioning

    DEFF Research Database (Denmark)

    Gilbert, Dorothea; Witt, Gesine; Smedes, Foppe;

    2016-01-01

    Polymers are increasingly applied for the enrichment of hydrophobic organic chemicals (HOCs) from various types of samples and media in many analytical partitioning-based measuring techniques. We propose using polymers as a reference partitioning phase and introduce polymer-polymer partitioning...... as the basis for a deeper insight into partitioning differences of HOCs between polymers, calibrating analytical methods, and consistency checking of existing and calculation of new partition coefficients. Polymer-polymer partition coefficients were determined for polychlorinated biphenyls (PCBs), polycyclic...

  16. An Algebraic Hardware/Software Partitioning Algorithm

    Institute of Scientific and Technical Information of China (English)

    秦胜潮; 何积丰; 裘宗燕; 张乃孝

    2002-01-01

    Hardware and software co-design is a design technique which delivers computer systems comprising hardware and software components. A critical phase of the co-design process is to decompose a program into hardware and software. This paper proposes an algebraic partitioning algorithm whose correctness is verified in program algebra. The authors introduce a program analysis phase before program partitioning and develop a collection of syntax-based splitting rules. The former provides the information for moving operations from software to hardware and reducing the interaction between components, and the latter supports a compositional approach to program partitioning.

  17. PARTITION PROPERTY OF DOMAIN DECOMPOSITION WITHOUT ELLIPTICITY

    Institute of Scientific and Technical Information of China (English)

    Mo Mu; Yun-qing Huang

    2001-01-01

    Partition property plays a central role in domain decomposition methods. Existing theory essentially assumes certain ellipticity. We prove the partition property for problems without ellipticity which are of practical importance. Example applications include implicit schemes applied to degenerate parabolic partial differential equations arising from superconductors, superfluids and liquid crystals. With this partition property, Schwarz algorithms can be applied to general non-elliptic problems with an h-independent optimal convergence rate. Application to the time-dependent Ginzburg-Landau model of superconductivity is illustrated and numerical results are presented.

  18. Convex Regression with Interpretable Sharp Partitions

    Science.gov (United States)

    Petersen, Ashley; Simon, Noah; Witten, Daniela

    2016-01-01

    We consider the problem of predicting an outcome variable on the basis of a small number of covariates, using an interpretable yet non-additive model. We propose convex regression with interpretable sharp partitions (CRISP) for this task. CRISP partitions the covariate space into blocks in a data-adaptive way, and fits a mean model within each block. Unlike other partitioning methods, CRISP is fit using a non-greedy approach by solving a convex optimization problem, resulting in low-variance fits. We explore the properties of CRISP, and evaluate its performance in a simulation study and on a housing price data set.

  19. Energy partitioning schemes: a dilemma.

    Science.gov (United States)

    Mayer, I

    2007-01-01

    Two closely related energy partitioning schemes, in which the total energy is presented as a sum of atomic and diatomic contributions by using the "atomic decomposition of identity", are compared on the example of N,N-dimethylformamide, a simple but chemically rich molecule. Both schemes account for different intramolecular interactions, for instance they identify the weak C-H...O intramolecular interactions, but give completely different numbers. (The energy decomposition scheme based on the virial theorem is also considered.) The comparison of the two schemes resulted in a dilemma which is especially striking when these schemes are applied for molecules distorted from their equilibrium structures: one either gets numbers which are "on the chemical scale" and have quite appealing values at the equilibrium molecular geometries, but exhibiting a counter-intuitive distance dependence (the two-center energy components increase in absolute value with the increase of the interatomic distances)--or numbers with too large absolute values but "correct" distance behaviour. The problem is connected with the quick decay of the diatomic kinetic energy components. PMID:17328441

  20. Energy partitioning schemes: a dilemma.

    Science.gov (United States)

    Mayer, I

    2007-01-01

    Two closely related energy partitioning schemes, in which the total energy is presented as a sum of atomic and diatomic contributions by using the "atomic decomposition of identity", are compared on the example of N,N-dimethylformamide, a simple but chemically rich molecule. Both schemes account for different intramolecular interactions, for instance they identify the weak C-H...O intramolecular interactions, but give completely different numbers. (The energy decomposition scheme based on the virial theorem is also considered.) The comparison of the two schemes resulted in a dilemma which is especially striking when these schemes are applied for molecules distorted from their equilibrium structures: one either gets numbers which are "on the chemical scale" and have quite appealing values at the equilibrium molecular geometries, but exhibiting a counter-intuitive distance dependence (the two-center energy components increase in absolute value with the increase of the interatomic distances)--or numbers with too large absolute values but "correct" distance behaviour. The problem is connected with the quick decay of the diatomic kinetic energy components.

  1. Lipid partitioning during cardiac stress.

    Science.gov (United States)

    Kolwicz, Stephen C

    2016-10-01

    It is well documented that fatty acids serve as the primary fuel substrate for the contracting myocardium. However, extensive research has identified significant changes in the myocardial oxidation of fatty acids during acute or chronic cardiac stress. As a result, the redistribution or partitioning of fatty acids due to metabolic derangements could have biological implications. Fatty acids can be stored as triacylglycerols, serve as critical components for biosynthesis of phospholipid membranes, and form the potent signaling molecules, diacylglycerol and ceramides. Therefore, the contribution of lipid metabolism to health and disease is more intricate than a balance of uptake and oxidation. In this review, the available data regarding alterations that occur in endogenous cardiac lipid pathways during the pathological stressors of ischemia-reperfusion and pathological hypertrophy/heart failure are highlighted. In addition, changes in endogenous lipids observed in exercise training models are presented for comparison. This article is part of a Special Issue entitled: Heart Lipid Metabolism edited by G.D. Lopaschuk. PMID:27040509

  2. Partial domain wall partition functions

    CERN Document Server

    Foda, O

    2012-01-01

    We consider six-vertex model configurations on a rectangular lattice with n (N) horizontal (vertical) lines, and "partial domain wall boundary conditions" defined as 1. all 2n arrows on the left and right boundaries point inwards, 2. n_u (n_l) arrows on the upper (lower) boundary, such that n_u + n_l = N - n, also point inwards, 3. all remaining n+N arrows on the upper and lower boundaries point outwards, and 4. all spin configurations on the upper and lower boundaries are summed over. To generate (n-by-N) "partial domain wall configurations", one can start from A. (N-by-N) configurations with domain wall boundary conditions and delete n_u (n_l) upper (lower) horizontal lines, or B. (2n-by-N) configurations that represent the scalar product of an n-magnon Bethe eigenstate and an n-magnon generic state on an N-site spin-1/2 chain, and delete the n lines that represent the Bethe eigenstate. The corresponding "partial domain wall partition function" is computed in construction {A} ({B}) as an N-by-N (n-by-n) det...

  3. Reproductive allocation in plants as affected by elevated carbon dioxide and other environmental changes: a synthesis using meta-analysis and graphical vector analysis.

    Science.gov (United States)

    Wang, Xianzhong; Taub, Daniel R; Jablonski, Leanne M

    2015-04-01

    Reproduction is an important life history trait that strongly affects dynamics of plant populations. Although it has been well documented that elevated carbon dioxide (CO2) in the atmosphere greatly enhances biomass production in plants, the overall effect of elevated CO2 on reproductive allocation (RA), i.e., the proportion of biomass allocated to reproductive structures, is little understood. We combined meta-analysis with graphical vector analysis to examine the overall effect of elevated CO2 on RA and how other environmental factors, such as low nutrients, drought and elevated atmospheric ozone (O3), interacted with elevated CO2 in affecting RA in herbaceous plants. Averaged across all species of different functional groups and environmental conditions, elevated CO2 had little effect on RA (-0.9%). RA in plants of different reproductive strategies and functional groups, however, differed in response to elevated CO2. For example, RA in iteroparous wild species decreased by 8%, while RA in iteroparous crops increased significantly (+14%) at elevated CO2. RA was unaffected by CO2 in plants grown with no stress or in low-nutrient soils. RA decreased at elevated CO2 and elevated O3, but increased in response to elevated CO2 in drought-stressed plants, suggesting that elevated CO2 could ameliorate the adverse effect of drought on crop production to some extent. Our results demonstrate that elevated CO2 and other global environmental changes have the potential to greatly alter plant community composition through differential effects on RA of different plant species and thus affect the dynamics of natural and agricultural ecosystems in the future.

  4. Carbon Nanotubes Filled with Different Ferromagnetic Alloys Affect the Growth and Development of Rice Seedlings by Changing the C:N Ratio and Plant Hormones Concentrations

    OpenAIRE

    Hao, Yi; Yu, Feifan; Lv, Ruitao; Ma, Chuanxin; Zhang, Zetian; Rui, Yukui; Liu, Liming; Cao, Weidong; Xing, Baoshan

    2016-01-01

    The aim of this study was to investigate the phytotoxicity of thin-walled carbon nanotubes (CNTs) to rice (Oryza sativa L.) seedlings. Three different CNTs, including hollow multi-walled carbon nanotubes (MWCNTs), Fe-filled carbon nanotubes (Fe-CNTs), and Fe-Co-filled carbon nanotubes (FeCo-CNTs), were evaluated. The CNTs significantly inhibited rice growth by decreasing the concentrations of endogenous plant hormones. The carbon to nitrogen ratio (C:N ratio) significantly increased in rice r...

  5. Expanding the REE Partitioning Database for Lunar Materials

    Science.gov (United States)

    Rapp, Jennifer F.; Draper, David S.

    2014-01-01

    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. This is taken as evidence of a large-scale differentation 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 later derived. However, the extent of the Eu anomaly in lunar rocks is variable. Some plagioclase grains in a lunar impact rock (60635) have been reported to display a negative Eu anomaly, or in some cases single grains display both positive and neagtive anomalies. Cathodoluminescence images reveal that some crystals have a negative anomaly in the core and positive at the rim, or vice versa, and the negative anomalies are not associated with crystal overgrowths. Oxygen fugacity is known to affect Eu partitioning into plagioclase, as under low fO2 conditions Eu can be divalent, and has an ionic radius similar to Ca2+ - significant in lunar samples where plagioclase compositions are predominantly anorthitic. However, there are very few experimental studies of rare earth element (REE) partitioning in plagioclase relevant to lunar magmatism, with only two plagioclase DEu measurements from experiments using lunar materials, and little data in low fO2 conditions relevant to the Moon. We report on REE partitioning experiments on lunar compositions. We investigate two lunar basaltic compositions, high-alumina basalt 14072 and impact melt breccia 60635. These samples span a large range of lunar surface bulk compositions. The experiments are carried out at variable fO2 in 1 bar gas mixing furnaces, and REE are analysed by and LA-ICP-MS. Our results not only greatly expand the existing plagioclase DREE database for lunar compositions, but also investigate the significance of fO2 in Eu partitioning, and in the interpretation of Eu anomalies in lunar materials.

  6. Spatially Partitioned Embedded Runge--Kutta Methods

    KAUST Repository

    Ketcheson, David I.

    2013-10-30

    We study spatially partitioned embedded Runge--Kutta (SPERK) schemes for partial differential equations (PDEs), in which each of the component schemes is applied over a different part of the spatial domain. Such methods may be convenient for problems in which the smoothness of the solution or the magnitudes of the PDE coefficients vary strongly in space. We focus on embedded partitioned methods as they offer greater efficiency and avoid the order reduction that may occur in nonembedded schemes. We demonstrate that the lack of conservation in partitioned schemes can lead to nonphysical effects and propose conservative additive schemes based on partitioning the fluxes rather than the ordinary differential equations. A variety of SPERK schemes are presented, including an embedded pair suitable for the time evolution of fifth-order weighted nonoscillatory spatial discretizations. Numerical experiments are provided to support the theory.

  7. Incompatibility boundaries for properties of community partitions

    CERN Document Server

    Browet, Arnaud; Sarlette, Alain

    2016-01-01

    We prove the incompatibility of certain desirable properties of community partition quality functions. Our results generalize the impossibility result of [Kleinberg 2003] by considering sets of weaker properties. In particular, we use an alternative notion to solve the central issue of the consistency property. (The latter means that modifying the graph in a way consistent with a partition should not have counterintuitive effects). Our results clearly show that community partition methods should not be expected to perfectly satisfy all ideally desired properties. We then proceed to show that this incompatibility no longer holds when slightly relaxed versions of the properties are considered, and we provide in fact examples of simple quality functions satisfying these relaxed properties. An experimental study of these quality functions shows a behavior comparable to established methods in some situations, but more debatable results in others. This suggests that defining a notion of good partition in communitie...

  8. Connections between groundwater flow and transpiration partitioning.

    Science.gov (United States)

    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. PMID:27463671

  9. OPTIMAL PARTITIONS OF DATA IN HIGHER DIMENSIONS

    Data.gov (United States)

    National Aeronautics and Space Administration — OPTIMAL PARTITIONS OF DATA IN HIGHER DIMENSIONS BRADLEY W. JACKSON*, JEFFREY D. SCARGLE, AND CHRIS CUSANZA, DAVID BARNES, DENNIS KANYGIN, RUSSELL SARMIENTO, SOWMYA...

  10. Connections between groundwater flow and transpiration partitioning

    Science.gov (United States)

    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.

  11. The mathematics of lecture hall partitions

    OpenAIRE

    Savage, Carla D.

    2016-01-01

    Over the past twenty years, lecture hall partitions have emerged as fundamental combinatorial structures, leading to new generalizations and interpretations of classical theorems and new results. In recent years, geometric approaches to lecture hall partitions have used polyhedral geometry to discover further properties of these rich combinatorial objects. In this paper we give an overview of some of the surprising connections that have surfaced in the process of trying to understand the lect...

  12. Geographical partition for distributed web crawling

    OpenAIRE

    Exposto, José; Macedo, Joaquim; Pina, António; Alves, Albano; Rufino, José

    2005-01-01

    This paper evaluates scalable distributed crawling by means of the geographical partition of the Web. The approach is based on the existence of multiple distributed crawlers each one responsible for the pages belonging to one or more previously identified geographical zones. The work considers a distributed crawler where the assignment of pages to visit is based on page content geographical scope. For the initial assignment of a page to a partition we use a simple heuristic that marks a page ...

  13. Actinide and fission product partitioning and transmutation

    International Nuclear Information System (INIS)

    The fourth international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Mito City in Japan, on 111-13 September 1996. The proceedings are presented in six sessions: the major programmes and international cooperation, the partitioning and transmutation programs, feasibility studies, particular separation processes, the accelerator driven transmutation, and the chemistry of the fuel cycle. (A.L.B.)

  14. Actinide and fission product partitioning and transmutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-01

    The fourth international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Mito City in Japan, on 111-13 September 1996. The proceedings are presented in six sessions: the major programmes and international cooperation, the partitioning and transmutation programs, feasibility studies, particular separation processes, the accelerator driven transmutation, and the chemistry of the fuel cycle. (A.L.B.)

  15. Congruences involving F-partition functions

    Directory of Open Access Journals (Sweden)

    James Sellers

    1994-01-01

    Full Text Available The primary goal of this note is to prove the congruence ϕ3(3n+2≡0(mod3, where ϕ3(n denotes the number of F-partitions of n with at most 3 repetitions. Secondarily, we conjecture a new family of congruences involving cϕ2(n, the number of F-partitions of n with 2 colors.

  16. A Gray path on binary partitions

    CERN Document Server

    Colthurst, Thomas

    2009-01-01

    A binary partition of a positive integer $n$ is a partition of $n$ in which each part has size a power of two. In this note we first construct a Gray sequence on the set of binary partitions of $n$. This is an ordering of the set of binary partitions of each $n$ (or of all $n$) such that adjacent partitions differ by one of a small set of elementary transformations; here the allowed transformatios are replacing $2^k+2^k$ by $2^{k+1}$ or vice versa (or addition of a new +1). Next we give a purely local condition for finding the successor of any partition in this sequence; the rule is so simple that successive transitions can be performed in constant time. Finally we show how to compute directly the bijection between $k$ and the $k$th term in the sequence. This answers a question posed by Donald Knuth in section 7.2.1 of The Art of Computer Programming.

  17. Welding-induced local maximum residual stress in heat affected zone of low-carbon austenitic stainless steel with machined surface layer and its influential factors

    International Nuclear Information System (INIS)

    In this study, the effects of work-hardening and pre-existing stress in the machined surface layer of low-carbon austenitic stainless steel on the welding-induced residual stress were experimentally investigated through the use of weld specimens with three different surface layers; as-cutout, mechanically-polished and electrolytically-polished. The high tensile and compressive stresses exist in the work-hardened surface layer of the as-cutout and mechanically-polished specimens, respectively. Meanwhile, no stress and work-hardened surface layer exist in the electrolytically-polished specimen. TIG bead-on-plate welding under the same welding heat input conditions was performed to introduce the residual stress into these specimens. Using these welded specimens, the distributions of welding-induced residual stress were measured by the X-ray diffraction method. Similarly, the distributions of hardness in welds were estimated by the Vickers hardness test. And then, these distributions were compared with one another. Based on the results, the residual stress in the weld metal (WM) is completely unaffected by the machined surface layer because the work-hardened surface layer disappears through the processes of melting and solidification during welding. The local maximum longitudinal tensile residual stress in the heat affected zone (HAZ) depends on the work-hardening but not on the existing stress, regardless of whether tensile or compressive, in the machined surface layer before welding. At the base metal far from WM and HAZ, the residual stress is formed by the addition of the welding-induced residual stress to the pre-existing stress in the machined surface layer before welding. The features of the welding-induced residual stress in low-carbon austenitic stainless steel with the machined surface layer and their influential factors were thus clarified. (author)

  18. Wavelet Space Partitioning for Symbolic Time Series Analysis

    Institute of Scientific and Technical Information of China (English)

    Venkatesh Rajagopalan; Asok Ray

    2006-01-01

    @@ A crucial step in symbolic time series analysis (STSA) of observed data is symbol sequence generation that relies on partitioning the phase-space of the underlying dynamical system. We present a novel partitioning method,called wavelet-space (WS) partitioning, as an alternative to symbolic false nearest neighbour (SFNN) partitioning.While the WS and SFNN partitioning methods have been demonstrated to yield comparable performance for anomaly detection on laboratory apparatuses, computation of WS partitioning is several orders of magnitude faster than that of the SFNN partitioning.

  19. Game Theoretic Iterative Partitioning for Dynamic Load Balancing in Distributed Network Simulation

    CERN Document Server

    Kurve, Aditya; Miller, David J; Kesidis, George

    2011-01-01

    High fidelity simulation of large-sized complex networks can be realized on a distributed computing platform that leverages the combined resources of multiple processors or machines. In a discrete event driven simulation, the assignment of logical processes (LPs) to machines is a critical step that affects the computational and communication burden on the machines, which in turn affects the simulation execution time of the experiment. We study a network partitioning game wherein each node (LP) acts as a selfish player. We derive two local node-level cost frameworks which are feasible in the sense that the aggregate state information required to be exchanged between the machines is independent of the size of the simulated network model. For both cost frameworks, we prove the existence of stable Nash equilibria in pure strategies. Using iterative partition improvements, we propose game theoretic partitioning algorithms based on the two cost criteria and show that each descends in a global cost. To exploit the d...

  20. Free atmospheric CO2 enrichment increased above ground biomass but did not affect symbiotic N2-fixation and soil carbon dynamics in a mixed deciduous stand in Wales

    Directory of Open Access Journals (Sweden)

    A. R. Smith

    2011-02-01

    Full Text Available Through increases in net primary production (NPP, elevated CO2 is hypothesized to increase the amount of plant litter entering the soil. The fate of this extra carbon on the forest floor or in mineral soil is currently not clear. Moreover, increased rates of NPP can be maintained only if forests can escape nitrogen limitation. In a Free atmospheric CO2 Enrichment (FACE experiment near Bangor, Wales, 4 ambient and 4 elevated [CO2] plots were planted with patches of Betula pendula, Alnus glutinosa and Fagus sylvatica on a former arable field. After 4 years, biomass averaged for the 3 species was 5497 (se 270 g m−2 in ambient and 6450 (se 130 g m−2 in elevated [CO2] plots, a significant increase of 17% (P = 0.018. During that time, only a shallow L forest floor litter layer had formed due to intensive bioturbation. Total soil C and N contents increased irrespective of treatment and species as a result of afforestation. We could not detect an additional C sink in the soil, nor were soil C stabilization processes affected by elevated [CO2]. We observed a decrease of leaf N content in Betula and Alnus under elevated [CO2], while the soil C/N ratio decreased regardless of CO2 treatment. The ratio of N taken up from the soil and by N2-fixation in Alnus was not affected by elevated [CO2]. We infer that increased nitrogen use efficiency is the mechanism by which increased NPP is sustained under elevated [CO2] at this site.

  1. Life-cycle assessment of lightweight textile membrane partition walls

    OpenAIRE

    Neiva, Sara Daniela Oliveira; Mateus, Ricardo; Macieira, Mónica; Mendonça, Paulo, ed. lit.; Bragança, L.

    2012-01-01

    This paper analyze the environmental, functional and economical performances of some conceptual lightweights textiles membranes partitions walls and to compare one of them with two technologies present in Portuguese market: i) the heavyweight conventional hollow brick partition wall; and ii) the lightweight reference plasterboard partition wall. Advantages of use textile/ fibrous/ membrane based materials in partition walls are focused and they may contribute for the development of new partit...

  2. Water treatment by H2O2 and/or UV affects carbon nanotube (CNT) properties and fate in water and tannic acid solution.

    Science.gov (United States)

    Czech, Bożena; Oleszczuk, Patryk; Wiącek, Agnieszka Ewa; Barczak, Mariusz

    2015-12-01

    The objective of the study was to estimate how water treatment (stimulation of real conditions) by H2O2 and/or UV affects carbon nanotube (CNT) properties and fate (stability/aggregation) in water and tannic acid solution. The processes studied had only a slight effect on SBET, porosity, and surface composition of CNTs. There was a change in the morphology of CNTs. After H2O2 and/or UV treatment, CNTs underwent shortening, opening up of their ends, and exfoliation. Treatment with H2O2 increased the content of oxygen in CNTs. A decrease was observed in the surface charge and in the mobility of CNTs, which caused an increase in their stability. UV irradiation of CNTs led to an increased incidence of defects that were manifested by both an increase of zeta potential and an increased mobility of CNT, whereas the presence of H2O2 during UV irradiation had only a slight effect on the parameters of the porous structure of nanotubes.

  3. Effects of progressive drought on photosynthesis and partitioning of absorbed light in apple trees

    Institute of Scientific and Technical Information of China (English)

    MA Ping; BAI Tuan-hui; MA Feng-wang

    2015-01-01

    To understand how drought stress affects CO2 assimilation and energy partitioning in apple (Malus domestica Borkh.), we investigated photosynthesis and photo-protective mechanisms when irrigation was withheld from potted Fuji trees. As the drought progressing, soil relative water content (SRWC) decreased from 87 to 24%in 15 d;this combined the decreasing in leaf relative water content (LRWC), net photosynthesis rate (Pn) and stomatal conductance (Gs). However, the concen-trations of chlorophyl s (Chl) remained unchanged while Pn values were declining. Photochemistry reactions were slightly down-regulated only under severe drought. Rubisco activity was signiifcantly decreased as drought conditions became more severe. The actual efifciency of photosystem II (ΦPSI ) was diminished as drought became more intense. Consequently, xanthophyl-regulated dissipation of thermal energy was greatly enhanced. Simultaneously, the ratio ofΦPSI to the quantum yield of carbon metabolism, which is measured under non-photorespiratory conditions, increased in paral el with drought severity. Our results indicate that, under progressive drought stress, the reduction in photosynthesis in apple leaves can be attributed primarily to stomatal limitations and the inhibited capacity for CO2 ifxation. Xanthophyl cycle-dependent ther-mal dissipation and the Mehler reaction are the most important pathways for dispersing excess energy from apple leaves during periods of drought stress.

  4. Thermodynamics of phenanthrene partition into solid organic matter from water

    Institute of Scientific and Technical Information of China (English)

    CHEN Bao-liang; ZHU Li-zhong; TAO Shu

    2005-01-01

    The thermodynamic behavior of organic contaminants in soils is essential to develop remediation technologies and assess risk from alternative technologies. Thermodynamics of phenanthrene partition into four solids (three soils and a bentonite) from water were investigated. The thermodynamics parameters (Δ H, Δ G°, Δ S°, ) were calculated according to experimental data. The total sorption heats of phenanthrene to solids from water ranged from - 7.93 to - 17.1 kJ/mol, which were less exothermic than the condensation heat of phenanthrene-solid(i.e., - 18.6 k J/mol). The partition heats of phenanthrene dissolved into solid organic matter ranged from 23.1 to 32.2k J/mol, which were less endothermic than the aqueous dissolved heat of phenanthrene(i. e., 40.2 kJ/mol), and were more endothermic than the fusion heat of phenanthrene-solid (i. e., 18.6 kJ/mol). The standard free energy changes, Δ G°, are all negative which suggested that phenanthrene sorption into solid was a spontaneous process. The positive values of standard entropy changes,ΔS° , show a gain in entropy for the transfer of phenanthrene at the stated standard state. Due to solubility-enhancement of phenanthrene,the partition coefficients normalized by organic carbon contents decrease with increasing system temperature(i. e., In Koc = -0.284In S +9.82( n =4, r2 = 0.992)). The solubility of phenanthrene in solid organic matter increased with increasing temperatures. Transports of phenanthrene in different latitude locations and seasons would be predicted according to its sorption thermodynamics behavior.

  5. Orality and the Archive: Teaching the Partition of India through Oral Histories

    Directory of Open Access Journals (Sweden)

    Gaana Jayagopalan

    2016-07-01

    Full Text Available This article is a reflection on how select oral histories and witness accounts about the partition of India and Pakistan, especially those by Urvashi Butalia and Veena Das were used in a graduate seminar in Bengaluru. The article explores the strength of oral archives as repositories of radical enquiry that may be used in classrooms to understand the complex nature of history, historiography, and interrogate the State’s archival processes. The article explores how students began to see the potency in oral archives as a space that embodies the victimhood of partition victims as opposed to an effacement of the sufferers in most state archives of the event. It observes how the memorialisation of Partition is different in the State’s construction of partition: to the victims who recount their stories, it is the ‘everyday’ that becomes predominant as opposed to State archives that seek to represent the differences between the two nations as paramount in its processes of memorialisation. The note concludes by emphasising the need to put such oral histories to use in classroom, especially to understand the nature of suffering. Through a reading of such stories, it is proposed, an affective literacy is enabled in students’ modes of enquiry about trauma, memory and suffering.   Keywords: Partition of India, affective literacy, archives, oral histories, witness narratives.

  6. Computational prediction of solubilizers' effect on partitioning.

    Science.gov (United States)

    Hoest, Jan; Christensen, Inge T; Jørgensen, Flemming S; Hovgaard, Lars; Frokjaer, Sven

    2007-02-01

    A computational model for the prediction of solubilizers' effect on drug partitioning has been developed. Membrane/water partitioning was evaluated by means of immobilized artificial membrane (IAM) chromatography. Four solubilizers were used to alter the partitioning in the IAM column. Two types of molecular descriptors were calculated: 2D descriptors using the MOE software and 3D descriptors using the Volsurf software. Structure-property relationships between each of the two types of descriptors and partitioning were established using partial least squares, projection to latent structures (PLS) statistics. Statistically significant relationships between the molecular descriptors and the IAM data were identified. Based on the 2D descriptors structure-property relationships R(2)Y=0. 99 and Q(2)=0.82-0.83 were obtained for some of the solubilizers. The most important descriptor was related to logP. For the Volsurf 3D descriptors models with R(2)Y=0.53-0.64 and Q(2)=0.40-0.54 were obtained using five descriptors. The present study showed that it is possible to predict partitioning of substances in an artificial phospholipid membrane, with or without the use of solubilizers.

  7. Effect partitioning under interference in two-stage randomized vaccine trials.

    Science.gov (United States)

    Vanderweele, Tyler J; Tchetgen Tchetgen, Eric J

    2011-07-01

    In the presence of interference, the exposure of one individual may affect the outcomes of others. We provide new effect partitioning results under interferences that express the overall effect as a sum of (i) the indirect (or spillover) effect and (ii) a contrast between two direct effects.

  8. Partitioning of unstructured meshes for load balancing

    International Nuclear Information System (INIS)

    Many large-scale engineering and scientific calculations involve repeated updating of variables on an unstructured mesh. To do these types of computations on distributed memory parallel computers, it is necessary to partition the mesh among the processors so that the load balance is maximized and inter-processor communication time is minimized. This can be approximated by the problem, of partitioning a graph so as to obtain a minimum cut, a well-studied combinatorial optimization problem. Graph partitioning algorithms are discussed that give good but not necessarily optimum solutions. These algorithms include local search methods recursive spectral bisection, and more general purpose methods such as simulated annealing. It is shown that a general procedure enables to combine simulated annealing with Kernighan-Lin. The resulting algorithm is both very fast and extremely effective. (authors) 23 refs., 3 figs., 1 tab

  9. Partition functions and graphs: A combinatorial approach

    CERN Document Server

    Solomon, A I; Duchamp, G; Horzela, A; Penson, K A; Solomon, Allan I.; Blasiak, Pawel; Duchamp, Gerard; Horzela, Andrzej; Penson, Karol A.

    2004-01-01

    Although symmetry methods and analysis are a necessary ingredient in every physicist's toolkit, rather less use has been made of combinatorial methods. One exception is in the realm of Statistical Physics, where the calculation of the partition function, for example, is essentially a combinatorial problem. In this talk we shall show that one approach is via the normal ordering of the second quantized operators appearing in the partition function. This in turn leads to a combinatorial graphical description, giving essentially Feynman-type graphs associated with the theory. We illustrate this methodology by the explicit calculation of two model examples, the free boson gas and a superfluid boson model. We show how the calculation of partition functions can be facilitated by knowledge of the combinatorics of the boson normal ordering problem; this naturally gives rise to the Bell numbers of combinatorics. The associated graphical representation of these numbers gives a perturbation expansion in terms of a sequen...

  10. Parallel Graph Partitioning for Complex Networks

    CERN Document Server

    Meyerhenke, Henning; Schulz, Christian

    2014-01-01

    Processing large complex networks like social networks or web graphs has recently attracted considerable interest. In order to do this in parallel, we need to partition them into pieces of about equal size. Unfortunately, previous parallel graph partitioners originally developed for more regular mesh-like networks do not work well for these networks. This paper addresses this problem by parallelizing and adapting the label propagation technique originally developed for graph clustering. By introducing size constraints, label propagation becomes applicable for both the coarsening and the refinement phase of multilevel graph partitioning. We obtain very high quality by applying a highly parallel evolutionary algorithm to the coarsened graph. The resulting system is both more scalable and achieves higher quality than state-of-the-art systems like ParMetis or PT-Scotch. For large complex networks the performance differences are very big. For example, our algorithm can partition a web graph with 3.3 billion edges ...

  11. Phase partitioning of trace metals in a contaminated estuary influenced by industrial effluent discharge.

    Science.gov (United States)

    Wang, Wenhao; Wang, Wen-Xiong

    2016-07-01

    Severe trace metal pollution due to industrial effluents releases was found in Jiulong River Estuary, Southern China. In this study, water samples were collected during effluent release events to study the dynamic changes of environmental conditions and metal partitioning among dissolved, particulate and colloidal phases controlled by estuarine mixing. Intermittent effluent discharges during low tide caused decreasing pH and dissolved oxygen, and induced numerous suspended particulate materials and dissolved organic carbon to the estuary. Different behaviors of Cu, Zn, Ni, Cr and Pb in the dissolved fraction against the conservative index salinity indicated different sources, e.g., dissolved Ni from the intermittent effluent. Although total metal concentrations increased markedly following effluent discharges, Cu, Zn, Cr, Pb were predominated by the particulate fraction. Enhanced adsorption onto particulates in the mixing process resulted in elevated partitioning coefficient (Kd) values for Cu and Zn, and the particle concentration effect was not obvious under such anthropogenic impacts. Colloidal proportion of these metals (especially Cu and Zn) showed positive correlations with dissolved or colloidal organic carbon, suggesting the metal-organic complexation. However, the calculated colloidal partitioning coefficients were relatively constant, indicating the excess binding capacity. Overall, the intermittent effluent discharge altered the particulate/dissolved and colloidal/soluble phase partitioning process and may further influence the bioavailability and potential toxicity to aquatic organisms. PMID:27061473

  12. Partitioning and purification of extracellular β-1,3-1,4-glucanase in aqueous two-phase systems

    Institute of Scientific and Technical Information of China (English)

    HE Guo-qing; ZHANG Xiu-yan; TANG Xing-jun; CHEN Qi-he; RUAN Hui

    2005-01-01

    The partition behaviors of β-1,3-1,4-glucanase, α-amylase and neutral proteases from clarified and whole fermentation broths of Bacillus subtilis ZJF-1A5 were investigated. An aqueous two-phase system (polyethylene glycol (PEG)/MgSO4)was examined with regard to the effects of PEG molecular weight (MW) and concentration, MgSO4 concentration, pH and NaCl concentration on enzyme partition and extraction. The MW and concentration of PEG were found to have significant effects on enzyme partition and extraction with low MW PEG showing the greatest benefit in the partition and extraction of β-glucanase with the PEG/MgSO4 system. MgSO4 concentration influenced the partition and extraction of β-glucanase significantly. pH had little effect on β-glucanase or proteases partition but affected α-amylase partition when pH was over 7.0. The addition of NaCl had little effect on the partition behavior of β-glucanase but had very significant effects on the partitioning of α-amylase and on the neutral proteases. The partition behaviors of β-glucanase, α-amylase and proteases in whole broth were also investigated and results were similar to those obtained with clarified fermentation broth. A two-step process for purifying β-glucanase was developed, which achieved β-glucanase recovery of 65.3% and specific activity of 14027 U/mg, 6.6 times improvement over the whole broth.

  13. Crescimento e partição de matéria seca e de carbono no mamoeiro em resposta à nutrição nitrogenada Growth and dry matter and carbon partition in papaya plants in response to nitrogen nutrition

    Directory of Open Access Journals (Sweden)

    Jailson Lopes Cruz

    2004-12-01

    ended sixty-four days after sowing. It was shown that total dry matter production of stem, leaf and roots, as well as the values of leaf area, leaf area/leaf mass ratio, stem mass and specific leaf area were smaller for plants grown under lower nitrogen availability. However, the root/shoot ratio did not show differences among treatments, indicating that there was no adjustment in carbon partition between these plant parts. The concentrations of total soluble sugars (TSS, reducing sugars (RS and not reducing sugars (NRS increased with the increase of NO-3 in solution. An opposing trend was noted for starch concentration, higher for plants grown under NO-3 deficiency. The starch/NRS ratio was higher for plants grown under lower NO-3 availability, suggesting that there was a reduction of export levels of assimilates produced.

  14. Carbon and other light element contents in the Earth's core based on first-principles molecular dynamics.

    Science.gov (United States)

    Zhang, Yigang; Yin, Qing-Zhu

    2012-11-27

    Carbon (C) is one of the candidate light elements proposed to account for the density deficit of the Earth's core. In addition, C significantly affects siderophile and chalcophile element partitioning between metal and silicate and thus the distribution of these elements in the Earth's core and mantle. Derivation of the accretion and core-mantle segregation history of the Earth requires, therefore, an accurate knowledge of the C abundance in the Earth's core. Previous estimates of the C content of the core differ by a factor of ∼20 due to differences in assumptions and methods, and because the metal-silicate partition coefficient of C was previously unknown. Here we use two-phase first-principles molecular dynamics to derive this partition coefficient of C between liquid iron and silicate melt. We calculate a value of 9 ± 3 at 3,200 K and 40 GPa. Using this partition coefficient and the most recent estimates of bulk Earth or mantle C contents, we infer that the Earth's core contains 0.1-0.7 wt% of C. Carbon thus plays a moderate role in the density deficit of the core and in the distribution of siderophile and chalcophile elements during core-mantle segregation processes. The partition coefficients of nitrogen (N), hydrogen, helium, phosphorus, magnesium, oxygen, and silicon are also inferred and found to be in close agreement with experiments and other geochemical constraints. Contents of these elements in the core derived from applying these partition coefficients match those derived by using the cosmochemical volatility curve and geochemical mass balance arguments. N is an exception, indicating its retention in a mantle phase instead of in the core. PMID:23150591

  15. The largest singletons of set partitions

    OpenAIRE

    Sun, Yidong; Wu, Xiaojuan

    2010-01-01

    Recently, Deutsch and Elizalde studied the largest and the smallest fixed points of permutations. Motivated by their work, we consider the analogous problems in set partitions. Let $A_{n,k}$ denote the number of partitions of $\\{1,2,\\dots, n+1\\}$ with the largest singleton $\\{k+1\\}$ for $0\\leq k\\leq n$. In this paper, several explicit formulas for $A_{n,k}$, involving a Dobinski-type analog, are obtained by algebraic and combinatorial methods, many combinatorial identities involving $A_{n,k}$...

  16. Partitioning and transmutation. Annual Report 1997

    Energy Technology Data Exchange (ETDEWEB)

    Enarsson, Aa.; Landgren, A.; Liljenzin, J.O.; Skaalberg, M.; Spjuth, L. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Nuclear Chemistry

    1997-12-01

    The current research project on partitioning and transmutation at the Dept. of Nuclear Chemistry, CTH, has the primary objective to investigate separation processes useful in connection with transmutation of long-lived radionuclides in high level nuclear waste. Partitioning is necessary in order to recover and purify the elements before and after each irradiation in a P and T treatment. In order to achieve a high transmutation efficiency the chemical separation process used must have small losses to various waste streams. At present, only aqueous based separation processes are known to be able to achieve the high recovery and separation efficiencies necessary for a useful P and T process. Refs, figs, tabs.

  17. Partition signed social networks via clustering dynamics

    Science.gov (United States)

    Wu, Jianshe; Zhang, Long; Li, Yong; Jiao, Yang

    2016-02-01

    Inspired by the dynamics phenomenon occurred in social networks, the WJJLGS model is modified to imitate the clustering dynamics of signed social networks. Analyses show that the clustering dynamics of the model can be applied to partition signed social networks. Traditionally, blockmodel is applied to partition signed networks. In this paper, a detailed dynamics-based algorithm for signed social networks (DBAS) is presented. Simulations on several typical real-world and illustrative networks that have been analyzed by the blockmodel verify the correctness of the proposed algorithm. The efficiency of the algorithm is verified on large scale synthetic networks.

  18. Advanced Coarsening Schemes for Graph Partitioning

    CERN Document Server

    Safro, Ilya; Schulz, Christian

    2012-01-01

    The graph partitioning problem is widely used and studied in many practical and theoretical applications. The multilevel strategies represent today one of the most effective and efficient generic frameworks for solving this problem on large-scale graphs. Most of the attention in designing the multilevel partitioning frameworks has been on the refinement phase. In this work we focus on the coarsening phase, which is responsible for creating structurally similar to the original but smaller graphs. We compare different matching- and AMG-based coarsening schemes, experiment with the algebraic distance between nodes, and demonstrate computational results on several classes of graphs that emphasize the running time and quality advantages of different coarsenings.

  19. Partitioning SAT Instances for Distributed Solving

    Science.gov (United States)

    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.

  20. Evolution of Holographic n-partite Information

    CERN Document Server

    Alishahiha, Mohsen; Tanhayi, Mohammad Reza

    2014-01-01

    We study various scaling behaviors of n-partite information during a process of thermalization after a global quantum quench for n disjoint system consisting of n parallel strips whose widths are much larger than the separation between them. By making use of the holographic description for entanglement entropy we explore holographic description of the n-partite information by which we show that it has a definite sign: it is positive for even n and negative for odd n. This might be thought of as an intrinsic property of a field theory which has gravity dual.

  1. Dynamics and sources of reduced sulfur, humic substances and dissolved organic carbon in a temperate river system affected by agricultural practices.

    Science.gov (United States)

    Marie, Lauriane; Pernet-Coudrier, Benoît; Waeles, Matthieu; Gabon, Marine; Riso, Ricardo

    2015-12-15

    Although reduced organic sulfur substances (RSS) as well as humic substances (HS) are widely suspected to play a role in, for example, metal speciation or used as a model of dissolved organic carbon (DOC) in laboratory studies, reports of their quantification in natural waters are scarce. We have examined the dynamics and sources of reduced sulfur, HS and DOC over an annual cycle in a river system affected by agricultural practices. The new differential pulse cathodic stripping voltammetry was successfully applied to measure glutathione-like compounds (GSHs), thioacetamide-like compounds (TAs) and the liquid chromatography coupled to organic detector to analyze HS and DOC at high frequency in the Penzé River (NW France). The streamflow-concentration patterns, principal components analysis and flux analysis allowed discrimination of the source of each organic compound type. Surprisingly, the two RSS and HS detected in all samples, displayed different behavior. As previously shown, manuring practice is the main source of DOC and HS in this watershed where agricultural activity is predominant. The HS were then transferred to the river systems via runoff, particularly during the spring and autumn floods, which are responsible of >60% of the annual flux. TAs had a clear groundwater source and may be formed underground, whereas GSHs displayed two sources: one aquagenic in spring and summer probably linked to the primary productivity and a second, which may be related to bacterial degradation. High sampling frequency allowed a more accurate assessment of the flux values which were 280 tC y(-1) for DOC representing 20 kg C ha(-1) y(-1). HS, TAs and GSHs fluxes represented 60, 13, and 4% of the total annual DOC export, respectively. PMID:26278374

  2. Carbon-to-nitrogen ratio affects the biomass composition and the fatty acid profile of heterotrophically grown Chlorella sp. TISTR 8990 for biodiesel production.

    Science.gov (United States)

    Singhasuwan, Somruethai; Choorit, Wanna; Sirisansaneeyakul, Sarote; Kokkaew, Nakhon; Chisti, Yusuf

    2015-12-20

    Chlorella sp. TISTR 8990 was cultivated heterotrophically in media with various initial carbon-to-nitrogen ratios (C/N ratio) and at different agitation speeds. The production of the biomass, its total fatty acid content and the composition of the fatty acids were affected by the C/N ratio, but not by agitation speed in the range examined. The biomass production was maximized at a C/N mass ratio of 29:1. At this C/N ratio, the biomass productivity was 0.68gL(-1)d(-1), or nearly 1.6-fold the best attainable productivity in photoautotrophic growth. The biomass yield coefficient on glucose was 0.62gg(-1) during exponential growth. The total fatty acids (TFAs) in the freeze-dried biomass were maximum (459mgg(-1)) at a C/N ratio of 95:1. Lower values of the C/N ratio reduced the fatty acid content of the biomass. The maximum productivity of TFAs (186mgL(-1)d(-1)) occurred at C/N ratios of 63:1 and higher. At these conditions, the fatty acids were mostly of the polyunsaturated type. Allowing the alga to remain in the stationary phase for a prolonged period after N-depletion, reduced the level of monounsaturated fatty acids and the level of polyunsaturated fatty acids increased. Biotin supplementation of the culture medium reduced the biomass productivity relative to biotin-free control, but had no effect on the total fatty acid content of the biomass.

  3. The effect of sulphur in silicate melt on partitioning of Ni and other trace elements

    Science.gov (United States)

    Wood, Bernard; Kiseeva, Ekaterina; Wohlers, Anke

    2016-04-01

    It has been suggested that variations in the sulphur contents of silicate melts affect the partitioning of trace chalcophile elements, particularly Ni, between silicate melt and crystalline phases such as olivine [1]. The general idea is that Ni (and other elements) complex with sulphur dissolved in the melt, thereby stabilising Ni in the melt and reducing the olivine-melt partition coefficient DNi. More recent experiments lead to the assertion that any sulphur effect, if present is small and can be ignored [2]. Experiments aimed at addressing this problem have, however, struggled with the difficulty that the maximum S contents of olivine- precipitating melts do not exceed ~0.5% even at sulphide saturation. Any effect is therefore difficult to establish unequivocally. Here we have taken advantage of the fact that experiments under strongly reducing conditions, where FeO activity in the silicate melt is very low lead to much higher concentrations of S than those associated with olivine precipitation. We have therefore investigated partitioning between sulphide melts and haplobasaltic silicate melt at concentrations of FeO between 0.3 and 10 weight% in order to investigate the "sulphur-effect" on partitioning. At the lowest FeO contents we are able to drive the S content of the melt to 10 weight% enabling the effects to be unequivocally established. We find that partitioning of strongly lithophile elements Nb, Ta, U, REE partition more strongly out of silicate melt as its S content increases. The effect is, surprisingly, predominantly due to the effect of S on the activity coefficient of FeO in the melt. In contrast strongly chalcophile Ni, Cu, Ag partition more strongly into the melt as its S content increases. This is due to a dramatic lowering of the activity coefficients of these elements in the silicate as S increases. Elements which show little effect of S include Pb, Co and In. The results enable us to predict the effects of sulphur on olivine-melt and

  4. Optimization of thread partitioning parameters in speculative multithreading based on artificial immune algorithm

    Institute of Scientific and Technical Information of China (English)

    Yu-xiang LI; Yin-liang ZHAO‡; Bin LIU; Shuo JI

    2015-01-01

    Thread partition plays an important role in speculative multithreading (SpMT) for automatic parallelization of ir-regular programs. Using unified values of partition parameters to partition different applications leads to the fact that every ap-plication cannot own its optimal partition scheme. In this paper, five parameters affecting thread partition are extracted from heuristic rules. They are the dependence threshold (DT), lower limit of thread size (TSL), upper limit of thread size (TSU), lower limit of spawning distance (SDL), and upper limit of spawning distance (SDU). Their ranges are determined in accordance with heuristic rules, and their step-sizes are set empirically. Under the condition of setting speedup as an objective function, all com-binations of five threshold values form the solution space, and our aim is to search for the best combination to obtain the best thread granularity, thread dependence, and spawning distance, so that every application has its best partition scheme. The issue can be attributed to a single objective optimization problem. We use the artificial immune algorithm (AIA) to search for the optimal solution. On Prophet, which is a generic SpMT processor to evaluate the performance of multithreaded programs, Olden bench-marks are used to implement the process. Experiments show that we can obtain the optimal parameter values for every benchmark, and Olden benchmarks partitioned with the optimized parameter values deliver a performance improvement of 3.00%on a 4-core platform compared with a machine learning based approach, and 8.92%compared with a heuristics-based approach.

  5. A Partition Temperley-Lieb Algebra

    OpenAIRE

    Juyumaya, Jesús

    2013-01-01

    We introduce a generalization of the Temperley--Lieb algebra. This generalization is defined by adding certain relations to the algebra of braids and ties. A specialization of this last algebra corresponds to one small Ramified Partition algebra, this fact is the motivation for the name of our generalization.

  6. Actinide and fission product partitioning and transmutation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-01

    The third international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Cadarache France, on 12-14 December 1994. The proceedings are presented in six sessions : an introduction session, the major programmes and international cooperation, the systems studies, the reactors fuels and targets, the chemistry and a last discussions session. (A.L.B.)

  7. Baxter Algebras, Stirling Numbers and Partitions

    OpenAIRE

    Guo, Li

    2004-01-01

    Recent developments of Baxter algebras have lead to applications to combinatorics, number theory and mathematical physics. We relate Baxter algebras to Stirling numbers of the first kind and the second kind, partitions and multinomial coefficients. This allows us to apply congruences from number theory to obtain congruences in Baxter algebras.

  8. Actinide and fission product partitioning and transmutation

    International Nuclear Information System (INIS)

    The third international information exchange meeting on actinide and fission product partitioning and transmutation, took place in Cadarache France, on 12-14 December 1994. The proceedings are presented in six sessions : an introduction session, the major programmes and international cooperation, the systems studies, the reactors fuels and targets, the chemistry and a last discussions session. (A.L.B.)

  9. Protium, an Infrastructure for Partitioned Applications

    NARCIS (Netherlands)

    Mullender, S.J.; Young, C.; Szymanski, T.; Reppy, J.; Presotto, D.; Pike, R.; Narlikar, G.

    2001-01-01

    Remote access feels different from local access. The major issues are consistency (machines vary in GUIs, applications, and devices) and responsiveness (the user must wait for network and server delays). Protium attacks these by partitioning programs into local viewers that connect to remote service

  10. Validation of planar partitions using constrained triangulations

    NARCIS (Netherlands)

    Ledoux, H.; Meijers, B.M.

    2010-01-01

    Planar partitions—full tessellations of the plane into non-overlapping polygons—are frequently used in GIS to model concepts such as land cover, cadastral parcels or administrative boundaries. Since in practice planar partitions are often stored as a set of individual objects (polygons) to which att

  11. Partition Function of Interacting Calorons Ensemble

    CERN Document Server

    Deldar, Sedigheh

    2015-01-01

    We present a method for computing the partition function of a caloron ensemble taking into account the interaction of calorons. We focus on caloron-Dirac string interaction and show that the metric that Diakonov and Petrov offered works well in the limit where this interaction occurs. We suggest computing the correlation function of two polyakov loops by applying Ewald's method.

  12. Partition function of interacting calorons ensemble

    Science.gov (United States)

    Deldar, S.; Kiamari, M.

    2016-01-01

    We present a method for computing the partition function of a caloron ensemble taking into account the interaction of calorons. We focus on caloron-Dirac string interaction and show that the metric that Diakonov and Petrov offered, works well in the limit where this interaction occurs. We suggest computing the correlation function of two polyakov loops by applying Ewald's method.

  13. Virasoro constraint for Nekrasov instanton partition function

    CERN Document Server

    Kanno, Shoichi; Zhang, Hong

    2012-01-01

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

  14. Set Partitions and the Multiplication Principle

    Science.gov (United States)

    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…

  15. Fair Partitions of Polygons: An Elementary Introduction

    Indian Academy of Sciences (India)

    R Nandakumar; N Ramana Rao

    2012-08-01

    We introduce the question: Given a positive integer , can any 2D convex polygonal region be partitioned into convex pieces such that all pieces have the same area and the same perimeter? The answer to this question is easily `yes’ for =2. We give an elementary proof that the answer is `yes’ for =4 and generalize it to higher powers of 2.

  16. Domain wall partition functions and KP

    International Nuclear Information System (INIS)

    We observe that the partition function of the six-vertex model on a finite square lattice with domain wall boundary conditions is (a restriction of) a KP τ function and express it as an expectation value of charged free fermions (up to an overall normalization)

  17. Domain wall partition functions and KP

    CERN Document Server

    Foda, O; Zuparic, M

    2009-01-01

    We observe that the partition function of the six vertex model on a finite square lattice with domain wall boundary conditions is (a restriction of) a KP tau function and express it as an expectation value of charged free fermions (up to an overall normalization).

  18. Thermal partition of two asymmetric discrete heat sources by cold air curtain

    Institute of Scientific and Technical Information of China (English)

    DENG Quan-wei; DENG Qi-hong

    2005-01-01

    A partition solution implemented by a cold air curtain for two asymmetric discrete heat sources in a twodimensional rectangular enclosure was numerically studied. Main attentions were focused on the effects of Reynolds number, Grashof number, separation distance between heat sources, and buoyancy ratio. It is found that the airflow and heat transfer are not only determined by governing parameters, but also affected by boundary conditions. It is also found that nearly symmetry of flow structure corresponds to nearly thermal partition, and the symmetry can be enhanced when Reynolds number, separation distance and buoyancy ratio increase. In addition, it is observed that there is a minimum Reynolds number for obtaining nearly thermal partition, which increases when Grashof number increases.

  19. Correlations for the partition behavior of proteins in aqueous two-phase systems

    DEFF Research Database (Denmark)

    Schmidt, A.S.; Andrews, B.A.; Asenjo, J.A.

    1996-01-01

    was lower than that of subtilisin which was probably due to its higher hydrophobicity and, hence, a stronger salting-out effect. The protein concentration in each of the two phases was correlated with a ''saturation''-type equation. The partition coefficient could be satisfactorily predicted, as a function...... of the overall protein concentration, by the ratio between the ''saturation'' equations of the two individual phases. Better correlations were obtained when an empirical sigmoidal Boltzmann equation was fitted to the data, since in virtually all cases the partition coefficient is constant at low protein...... with 3% w/w NaCl was used for alpha-amylase. The concentration of the protein in each of the phases affected its partition behavior. The pattern for the individual proteins was dependent on their physicochemical properties. In the top phase, maximum protein concentration was determined mainly by a steric...

  20. Partition Behavior of Penicillin in Three-liquid-phase Extraction System

    Institute of Scientific and Technical Information of China (English)

    谭显东; 季清荣; 常志东

    2006-01-01

    Partition behavior of penicillins G and V was studied in a novel three-liquid-phase extraction system, which is composed of butyl acetate (BA), polyethylene glycol (PEG), ammonia sulfate [(NH4)2SO4] and water (H2O). The main components in the top, middle and bottom phases are butyl acetate, polyethylene glycol aqueous solution and ammonia sulfate aqueous solution, respectively. Some parameters such as partition coefficients Di/j and mass fractions Ei ofpenicillins G and V were determined at the room temperature, respectively. Experimental efforts have been made to investigate the partition behavior of penicillin in the three-liquid-phase extraction system, including initial concentrations of phase-forming components [PEG and (NH4)2SO4], PEG molecular weight, pH, initial concentration of penicillin. The results indicated that penicillins G and V have the similar partition behavior. They preferentially distribute into the middle phase with the increase of initial concentration of phase-forming components and into the top phase with the decrease of pH, while partition coefficient Dm/b is hardly affected by pH value. The variation of PEG molecular weight has little effect on mass fractions of penicillin. The increase of initial concentration of penicillins G and V could lead to the increase of Dt/b, Dm/b and the decrease of Dt/m, while their mass fractions in all phases were almost independent on their initial concentrations.

  1. An Energy Balance Model to Predict Chemical Partitioning in a Photosynthetic Microbial Mat

    Science.gov (United States)

    Hoehler, Tori M.; Albert, Daniel B.; DesMarais, David J.

    2006-01-01

    Studies of biosignature formation in photosynthetic microbial mat communities offer potentially useful insights with regards to both solar and extrasolar astrobiology. Biosignature formation in such systems results from the chemical transformation of photosynthetically fixed carbon by accessory microorganisms. This fixed carbon represents a source not only of reducing power, but also energy, to these organisms, so that chemical and energy budgets should be coupled. We tested this hypothesis by applying an energy balance model to predict the fate of photosynthetic productivity under dark, anoxic conditions. Fermentation of photosynthetically fixed carbon is taken to be the only source of energy available to cyanobacteria in the absence of light and oxygen, and nitrogen fixation is the principal energy demand. The alternate fate for fixed carbon is to build cyanobacterial biomass with Redfield C:N ratio. The model predicts that, under completely nitrogen-limited conditions, growth is optimized when 78% of fixed carbon stores are directed into fermentative energy generation, with the remainder allocated to growth. These predictions were compared to measurements made on microbial mats that are known to be both nitrogen-limited and populated by actively nitrogen-fixing cyanobacteria. In these mats, under dark, anoxic conditions, 82% of fixed carbon stores were diverted into fermentation. The close agreement between these independent approaches suggests that energy balance models may provide a quantitative means of predicting chemical partitioning within such systems - an important step towards understanding how biological productivity is ultimately partitioned into biosignature compounds.

  2. Three-way partitioning with two C isotopes: A field study of pyrogenic C, soil organic C, and plant root C and their interactions

    Science.gov (United States)

    Whitman, T.; Lehmann, J.

    2013-12-01

    Soils hold a globally important stock of organic carbon (C). The cycling of this stock both affects and is affected by climatic changes. One predicted effect of global climate change is changes to fire regimes. As well as releasing large quantities of CO2 through combustion, fires generate pyrogenic C (pyC), which is relatively stable chemically. PyC not only contributes directly to total soil C stocks, but also can affect the cycling of non-pyC and plant growth. These non-linear three-way interactions are challenging to predict, partly because it is methodologically challenging to distinguish the three sources of C in a single system using traditional isotopic partitioning approaches. One solution would be to use 12C, 13C, and radioactive 14C to partition the three C sources. However, radioisotope work can be expensive and is tightly regulated. In a 2x2 experimental design (here, with pyC additions and plant presence as the two treatments), it is possible to use only the stable isotopes (12C and 13C) to separate the three emission sources, given certain conditions. Our approach is based on the inclusion of a fifth treatment, which is a mirror of the three-part treatment (soil with pyC and with plants), but with one component (here, pyC) having a different 13C signature. This approach is most robust when the third source is an external input that can be produced in a controlled manner, which is the case for pyC. We describe our application of this system to a field trial in upstate NY. The soil was developed primarily under C3 plants (∂13C = -23‰), the plant is sorghum-sudan grass (∂13C = -12.6‰), and the pyC was produced from 13C labeled maize at 350°C (∂13C = +35.6‰ and +106.6‰). CO2 flux data are collected daily initially, then bi-weekly, over three months. Gas samples for isotopic partitioning are collected at three timepoints, using an isotopic forced diffusion chamber technique. We discuss the implications of our findings for carbon cycling as

  3. The importance of applying an appropriate data partitioning

    CERN Document Server

    Dimitrov, Gancho; The ATLAS collaboration

    2015-01-01

    In this presentation are described specific technical solutions put in place in various database applications of the ATLAS experiment at LHC where we make use of several partitioning techniques available in Oracle 11g. With the broadly used range partitioning and its option of automatic interval partitioning we add our own logic in PLSQL procedures and scheduler jobs to sustain data sliding windows in order to enforce various data retention policies. We also make use of the new Oracle 11g reference partitioning in the ATLAS Nightly Build System to achieve uniform data segmentation. However the most challenging was to segment the data of the new ATLAS Distributed Data Management system, which resulted in tens of thousands list type partitions and sub-partitions. Partition and sub-partition management, index strategy, statistics gathering and queries execution plan stability are important factors when choosing an appropriate physical model for the application data management. The so-far accumulated knowledge wi...

  4. The importance of having an appropriate data segmentation (partitioning)

    CERN Document Server

    Dimitrov, Gancho; The ATLAS collaboration

    2014-01-01

    In this presentation will be shown real life examples from database applications in the ATLAS experiment @ LHC where we make use of many Oracle partitioning techniques available in Oracle 11g. With the broadly used range partitioning and its option of automatic interval partitioning we add our own logic in PLSQL for sustaining data sliding windows in order to enforce various data retention policies. We also make use of the reference partitioning in some use cases, however the most challenging was to segment the data of a large bookkeeping system which resulted in tens of thousands list partitions and list sub-partitions. Partition and sub-partition management, index strategy, statistics gathering and queries execution plan stability are important factors when choosing an appropriate for the use case data management model. The gained experience with all of those will be shared with the audience.

  5. Open software tools for eddy covariance flux partitioning

    Science.gov (United States)

    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...

  6. Effect of Quenching and Partitioning Process on MA Constituent in Nb-Bearing HSLA Steel

    Institute of Scientific and Technical Information of China (English)

    YU Wei; CHEN Tao; JIAO Duotian; WU Huibin

    2012-01-01

    The effect of quenching-partitioning (Q-P) process on martensite-austenite (MA) constituent is investigated by the thermo-analysis simulator for a niobium-bearing HSLA steel.The process includes quenching from 950 ℃ to the intermediate temperature of 350-550 ℃ at the rate of 30 ℃/s and subsequent reheating at the rate of 20-50 ℃/s and partitioning at 660-800 ℃.The microstructure is characterized by nano probe,EBSD,colored metallograph,optical microscope and graphic analytic method.The results show that the improvement of distribution homogeneity of MA in microstructure,the diminishment of the MA average grain size and increment of the MA volume fraction is caused by the intermediate temperature decrease,the reheating rate increase and a proper partitioning temperature.The volume fraction of MA is up to 7.9% while the sample is quenched to 450 ℃,reheated at 50 ℃/s and partitioned at 750 ℃.The grain is granular or equiaxed in shape and the average grain size of MA is about 0.77-1.48 μm after treated by Q&P process.The grains tend to be coarse and with sharpy-angle as the intermediate temperature is up and the reheating rate and the partitioning temperature rises.The MA volume fraction depends on the untransformed austenite volume fraction after quenching and carbon diffusion time and temperature during partitioning process.

  7. Capacity of US Forests to Maintain Existing Carbon Sequestration will be affected by Changes in Forest Disturbances and to a greater extent, the Economic and Societal Influences on Forest Management and Land Use

    Science.gov (United States)

    Joyce, L. A.; Running, S. W.; Breshears, D. D.; Dale, V.; Malmsheimer, R. W.; Sampson, N.; Sohngen, B.; Woodall, C. W.

    2012-12-01

    Increasingly the value of US forest carbon dynamics and carbon sequestration is being recognized in discussions of adaptation and mitigation to climate change. Past exploitation of forestlands in the United States for timber, fuelwood, and conversion to agriculture resulted in large swings in forestland area and terrestrial carbon dynamics. The National Climate Assessment explored the implications of current and future stressors, including climate change, to the future of forest carbon dynamics in the United States. While U.S forests and associated harvested wood products sequestered roughly 13 percent of all carbon dioxide emitted in the United States in 2010, the capacity of forests to maintain this amount of carbon sequestration will be affected by the effects of climate change on forest disturbances, tree growth and mortality, changes in species composition, and to a greater extent, the economic and societal influences on forest management and forestland use. Carbon mitigation through forest management includes three strategies: 1) land management to increase forest area (afforestation) and/or avoid deforestation; 2) carbon management in existing forests; and 3) use of wood in place of materials that require more carbon emissions to produce, in place of fossil fuels to produce energy or in wood products for carbon storage. A significant financial incentive facing many private forest owners is the value of their forest lands for conversion to urban or developed uses. In addition, consequences of large scale die-off and wildfire disturbance events from climate change pose major challenges to forestland area and forest management with potential impacts occurring up to regional scales for timber, flooding and erosion risks, other changes in water budgets, and biogeochemical changes including carbon storage. Options for carbon management on existing forests include practices that increase forest growth such as fertilization, irrigation, switch to fast

  8. Dynamic State Space Partitioning for External Memory Model Checking

    DEFF Research Database (Denmark)

    Evangelista, Sami; Kristensen, Lars Michael

    2009-01-01

    We describe a dynamic partitioning scheme usable by model checking techniques that divide the state space into partitions, such as most external memory and distributed model checking algorithms. The goal of the scheme is to reduce the number of transitions that link states belonging to different ...... partitions, and thereby limit the amount of disk access and network communication. We report on several experiments made with our verification platform ASAP that implements the dynamic partitioning scheme proposed in this paper....

  9. Hyper-Graph Based Database Partitioning for Transactional Workloads

    OpenAIRE

    Cao, Yu; Guo, Xiaoyan; Todd, Stephen

    2013-01-01

    A common approach to scaling transactional databases in practice is horizontal partitioning, which increases system scalability, high availability and self-manageability. Usu- ally it is very challenging to choose or design an optimal partitioning scheme for a given workload and database. In this technical report, we propose a fine-grained hyper-graph based database partitioning system for transactional work- loads. The partitioning system takes a database, a workload, a node cluster and part...

  10. Optimising query execution time in LHCb Bookkeeping System using partition pruning and Partition-Wise joins

    Science.gov (United States)

    Mathe, Zoltan; Charpentier, Philippe

    2014-06-01

    The LHCb experiment produces a huge amount of data which has associated metadata such as run number, data taking condition (detector status when the data was taken), simulation condition, etc. The data are stored in files, replicated on the Computing Grid around the world. The LHCb Bookkeeping System provides methods for retrieving datasets based on their metadata. The metadata is stored in a hybrid database model, which is a mixture of Relational and Hierarchical database models and is based on the Oracle Relational Database Management System (RDBMS). The database access has to be reliable and fast. In order to achieve a high timing performance, the tables are partitioned and the queries are executed in parallel. When we store large amounts of data the partition pruning is essential for database performance, because it reduces the amount of data retrieved from the disk and optimises the resource utilisation. This research presented here is focusing on the extended composite partitioning strategy such as range-hash partition, partition pruning and usage of the Partition-Wise joins. The system has to serve thousands of queries per minute, the performance and capability of the system is measured when the above performance optimization techniques are used.

  11. Optimising query execution time in LHCb Bookkeeping System using partition pruning and Partition-Wise joins

    International Nuclear Information System (INIS)

    The LHCb experiment produces a huge amount of data which has associated metadata such as run number, data taking condition (detector status when the data was taken), simulation condition, etc. The data are stored in files, replicated on the Computing Grid around the world. The LHCb Bookkeeping System provides methods for retrieving datasets based on their metadata. The metadata is stored in a hybrid database model, which is a mixture of Relational and Hierarchical database models and is based on the Oracle Relational Database Management System (RDBMS). The database access has to be reliable and fast. In order to achieve a high timing performance, the tables are partitioned and the queries are executed in parallel. When we store large amounts of data the partition pruning is essential for database performance, because it reduces the amount of data retrieved from the disk and optimises the resource utilisation. This research presented here is focusing on the extended composite partitioning strategy such as range-hash partition, partition pruning and usage of the Partition-Wise joins. The system has to serve thousands of queries per minute, the performance and capability of the system is measured when the above performance optimization techniques are used

  12. GPU Acceleration of Graph Matching, Clustering, and Partitioning

    NARCIS (Netherlands)

    Fagginger Auer, B.O.

    2013-01-01

    We consider sequential algorithms for hypergraph partitioning and GPU (i.e., fine-grained shared-memory parallel) algorithms for graph partitioning and clustering. Our investigation into sequential hypergraph partitioning is concerned with the efficient construction of high-quality matchings for hyp

  13. Hydrological regulations, land use and a mud volcano affecting the sediment and carbon load of the tropical Brantas River, Java, Indonesia

    Science.gov (United States)

    Jennerjahn, Tim; Jänen, Ingo

    2014-05-01

    Intensive human uses of the coastal zone and increasing extreme events are more and more endangering the integrity of coastal ecosystems during the Anthropocene. This is of particular importance in SE Asia where large parts of the population live in the coastal zone and economically depend on its resources. Intensive tectonic activity in the circum-Pacific 'Ring of fire' exposes the region to extreme natural events like volcano eruptions, earthquakes and occasionally following tsunamis. The Indonesian island of Java is a prime example in this respect because of its location on an active continental margin and a population density >1,000 inhabitants km-2. Its second largest river, the Brantas, empties into the shallow Madura Strait through two major branches, the Wonokromo and the Porong, the latter being responsible for 80 % of the discharge. Major land use in the catchment is agriculture (61 %) and the hydrology and sediment load of the river is regulated by 8 large dams and numerous weirs. The estuarine lowlands in the prograding delta were once covered by mangroves which were to a large extent replaced by aquaculture ponds. The eruption of a mud volcano near the Porong in 2006 added another factor affecting the amount and composition of the dissolved and particulate river loads. Concentrations of total suspended sediments (TSM) and particulate organic carbon (POC) displayed large seasonal variations in the Brantas before its diversion into the Porong and the Wonokromo as well as in the latter two with maxima during the wet season (Nov-April). High concentrations in the Porong during both seasons were mainly due to the constantly high input from the mud volcano. Favourable weathering conditions and agriculture as the predominant land use are responsible for high erosion rates of 4-14 mm yr-1 in the catchment. The 8 major dams and numerous weirs built between the 1970s and the 1990s retain a large amount of that sediment leading to an overall low sediment yield of

  14. Comparison of the composition and gas/particle partitioning of organic acids in monoterpene and isoprene dominated environments

    Science.gov (United States)

    Thompson, S.; Yatavelli, L. R.; Stark, H.; Kimmel, J.; Krechmer, J.; Hu, W.; Palm, B. B.; Campuzano Jost, P.; Day, D. A.; Isaacman, G. A.; Goldstein, A. H.; Khan, M. H.; Holzinger, R.; Lopez-Hilfiker, F.; Mohr, C.; Thornton, J. A.; Jayne, J. T.; Worsnop, D. R.; Jimenez, J. L.

    2013-12-01

    Gas and particle-phase organic acids measurements from two different regions with different biogenic volatile organic compound emissions are used to understand gas/particle partitioning principles. A Chemical Ionization High Resolution Time-of-Flight Mass Spectrometer (HRToF-CIMS), with acetate (CH3COO-) as the reagent ion was used to selectively detect acids. Hundreds of gas and particle-phase organic acids were measured in both locations, a monoterpene and MBO-dominated environment (ponderosa pine forest in Colorado, BEACHON-RoMBAS 2011) and isoprene and terpene-dominated environment (mixed deciduous and pine forest in Alabama, SOAS 2013). Time series of gas/particle partitioning for ions consistent with tracers for isoprene oxidation such as methacrylic acid epoxide (MAE) and isoprene epoxydiol (IEPOX) and tracers for α-pinene oxidation such as pinic and pinonic acid will be presented. Gas/particle partitioning, represented as the fraction of each species in the particle-phase, Fp, was calculated for C1-C18 alkanoic acids and biogenic VOC oxidation tracers and compared to an absorptive partitioning model. These results are compared with those of two other instruments that can also quantify gas/particle partitioning with high time resolution: a Semivolatile Thermal Desorption Aerosol GC/MS (SV-TAG) and a Thermal Desorption Proton Transfer Time-of-Flight Mass Spectrometer (TD-PTRMS). Data from both environments were consistent with the values and trends predicted by the absorptive partitioning model for the tracer acids. However, for low carbon number alkanoic acids we report a higher fraction in the particle phase than predicted by the model. The Fp for the bulk-averaged acids and its relationship to the degree of oxidation and carbon number will also be presented. Temporal patterns and correlations with atmospheric conditions and composition will be explored for individual and bulk acids. We will discuss atmospheric implications of the gas/particle partitioning

  15. Spectral partitioning of random regular blockmodels

    CERN Document Server

    Barucca, Paolo

    2016-01-01

    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 random graphs with regular block structure is introduced, for which analytical results can be obtained. In particular, the spectral density of such random regular blockmodels is computed exactly for a modular, bipartite and core-periphery structure. McKay's law for random regular graphs is found analytically to apply also for regular modular and bipartite structures when blocks are homogeneous. In core-periphery structures, where blocks are intrinsically heterogeneous, a new law is found to apply for the spectral density. Exact solution to the inference problem is provided for the models discussed. All analytical results show perfect agreement with numerical experiments. Final discussion summarizes results and outlines the relevance of the results for the solution of graph partitioning problems in other graph en...

  16. Mantle Mineral/Silicate Melt Partitioning

    Science.gov (United States)

    McFarlane, E. A.; Drake, M. J.

    1992-07-01

    Introduction: The partitioning of elements among mantle phases and silicate melts is of interest in unraveling the early thermal history of the Earth. It has been proposed that the elevated Mg/Si ratio of the upper mantle of the Earth is a consequence of the flotation of olivine into the upper mantle (Agee and Walker, 1988). Agee and Walker (1988) have generated a model via mass balance by assuming average mineral compositions to generate upper mantle peridotite. This model determines that upper mantle peridotite could result from the addition of 32.7% olivine and 0.9% majorite garnet into the upper mantle, and subtraction of 27.6% perovskite from the upper mantle (Agee and Walker, 1988). The present contribution uses experimental data to examine the consequences of such multiple phase fractionations enabling an independent evaluation of the above mentioned model. Here we use Mg-perovskite/melt partition coefficients from both a synthetic and a natural system (KLB-1) obtained from this laboratory. Also used are partition coefficient values for majorite garnet/melt, beta spinel/melt and olivine/melt partitioning (McFarlane et al., 1991b; McFarlane et al., 1992). Multiple phase fractionations are examined using the equilibrium crystallization equation and partition coefficient values. The mineral proportions determined by Agee and Walker (1988) are converted into weight fractions and used to compute a bulk partition coefficient value. Discussion: There has been a significant debate concerning whether measured values of trace element partition coefficients permit large-scale fractionation of liquidus phases from an early terrestrial magma ocean (Kato et al., 1988a,b; Walker and Agee, 1989; Drake, 1989; Drake et al., 1991; McFarlane et al., 1990, 1991). It should be noted that it is unclear which, if any, numerical values of partition coefficients are appropriate for examining this question, and certainly the assumptions for the current model must be more fully

  17. Data Partitioning for Parallel Entity Matching

    CERN Document Server

    Kirsten, Toralf; Hartung, Michael; Groß, Anika; Köpcke, Hanna; Rahm, Erhard

    2010-01-01

    Entity matching is an important and difficult step for integrating web data. To reduce the typically high execution time for matching we investigate how we can perform entity matching in parallel on a distributed infrastructure. We propose different strategies to partition the input data and generate multiple match tasks that can be independently executed. One of our strategies supports both, blocking to reduce the search space for matching and parallel matching to improve efficiency. Special attention is given to the number and size of data partitions as they impact the overall communication overhead and memory requirements of individual match tasks. We have developed a service-based distributed infrastructure for the parallel execution of match workflows. We evaluate our approach in detail for different match strategies for matching real-world product data of different web shops. We also consider caching of in-put entities and affinity-based scheduling of match tasks.

  18. Non-parametric partitioning of SAR images

    Science.gov (United States)

    Delyon, G.; Galland, F.; Réfrégier, Ph.

    2006-09-01

    We describe and analyse a generalization of a parametric segmentation technique adapted to Gamma distributed SAR images to a simple non parametric noise model. The partition is obtained by minimizing the stochastic complexity of a quantized version on Q levels of the SAR image and lead to a criterion without parameters to be tuned by the user. We analyse the reliability of the proposed approach on synthetic images. The quality of the obtained partition will be studied for different possible strategies. In particular, one will discuss the reliability of the proposed optimization procedure. Finally, we will precisely study the performance of the proposed approach in comparison with the statistical parametric technique adapted to Gamma noise. These studies will be led by analyzing the number of misclassified pixels, the standard Hausdorff distance and the number of estimated regions.

  19. Sifting Function Partition for the Goldbach Problem

    CERN Document Server

    Song, Fu-Gao

    2008-01-01

    All sieve methods for the Goldbach problem sift out all the composite numbers; even though, strictly speaking, it is not necessary to do so and which is, in general, very difficult. Some new methods introduced in this paper show that the Goldbach problem can be solved under sifting out only some composite numbers. In fact, in order to prove the Goldbach conjecture, it is only necessary to show that there are prime numbers left in the residual integers after the initial sifting! This idea can be implemented by using one of the three methods called sifting function partition by integer sort, sifting function partition by intervals and comparative sieve method, respectively. These are feasible methods for solving both the Goldbach problem and the problem of twin primes. An added bonus of the above methods is the elimination of the indeterminacy of the sifting functions brought about by their upper and lower bounds.

  20. Number Partitioning via Quantum Adiabatic Computation

    Science.gov (United States)

    Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)

    2002-01-01

    We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.

  1. Partitioning Complete Graphs by Heterochromatic Trees

    Institute of Scientific and Technical Information of China (English)

    Ze-min JIN; Xue-liang LI

    2012-01-01

    A heterochromatic tree is an edge-colored tree in which any two edges have different colors.The heterochroratic tree partition number of an r-edge-colored graph G,denoted by tr(G),is the minimum positive integer p such that whenever the edges of the graph G are colored with r colors,the vertices of G can be covered by at most p vertex-disjoint heterochromatic trees.In this paper we determine the heterochromatic tree partition number of r-edge-colored complete graphs.We also find at most tr(Kn) vertex-disjoint heterochromatic trees to cover all the vertices in polynomial time for a given r-edge-coloring of Kn.

  2. Nested partitions method, theory and applications

    CERN Document Server

    Shi, Leyuan

    2009-01-01

    There is increasing need to solve large-scale complex optimization problems in a wide variety of science and engineering applications, including designing telecommunication networks for multimedia transmission, planning and scheduling problems in manufacturing and military operations, or designing nanoscale devices and systems. Advances in technology and information systems have made such optimization problems more and more complicated in terms of size and uncertainty. Nested Partitions Method, Theory and Applications provides a cutting-edge research tool to use for large-scale, complex systems optimization. The Nested Partitions (NP) framework is an innovative mix of traditional optimization methodology and probabilistic assumptions. An important feature of the NP framework is that it combines many well-known optimization techniques, including dynamic programming, mixed integer programming, genetic algorithms and tabu search, while also integrating many problem-specific local search heuristics. The book uses...

  3. Supersymmetric partition functions on Riemann surfaces

    CERN Document Server

    Benini, Francesco

    2016-01-01

    We present a compact formula for the supersymmetric partition function of 2d N=(2,2), 3d N=2 and 4d N=1 gauge theories on $\\Sigma_g \\times T^n$ with partial topological twist on $\\Sigma_g$, where $\\Sigma_g$ is a Riemann surface of arbitrary genus and $T^n$ is a torus with n=0,1,2, respectively. In 2d we also include certain local operator insertions, and in 3d we include Wilson line operator insertions along $S^1$. For genus g=1, the formula computes the Witten index. We present a few simple Abelian and non-Abelian examples, including new tests of non-perturbative dualities. We also show that the large N partition function of ABJM theory on $\\Sigma_g \\times S^1$ reproduces the Bekenstein-Hawking entropy of BPS black holes in AdS4 whose horizon has $\\Sigma_g$ topology.

  4. Analysis of fractals with combined partition

    Science.gov (United States)

    Dedovich, T. G.; Tokarev, M. V.

    2016-03-01

    The space—time properties in the general theory of relativity, as well as the discreteness and non-Archimedean property of space in the quantum theory of gravitation, are discussed. It is emphasized that the properties of bodies in non-Archimedean spaces coincide with the properties of the field of P-adic numbers and fractals. It is suggested that parton showers, used for describing interactions between particles and nuclei at high energies, have a fractal structure. A mechanism of fractal formation with combined partition is considered. The modified SePaC method is offered for the analysis of such fractals. The BC, PaC, and SePaC methods for determining a fractal dimension and other fractal characteristics (numbers of levels and values of a base of forming a fractal) are considered. It is found that the SePaC method has advantages for the analysis of fractals with combined partition.

  5. Partition-DFT on the Water Dimer

    CERN Document Server

    Gómez, Sara; Restrepo, Albeiro; Wasserman, Adam

    2016-01-01

    As is well known, the ground-state symmetry group of the water dimer switches from its equilibrium $C_{s}$-character to $C_{2h}$-character as the distance between the two oxygen atoms of the dimer decreases below $R_{\\rm O-O}\\sim 2.5$ \\AA{}. For a range of $R_{\\rm O-O}$ between 1 and 5 \\AA{}, and for both symmetries, we apply Partition Density Functional Theory (PDFT) to find the unique monomer densities that sum to the correct dimer densities while minimizing the sum of the monomer energies. We calculate the work involved in deforming the isolated monomer densities and find that it is slightly larger for the $C_s$ geometry for all $R_{\\rm O-O}$. We discuss how the PDFT densities and the corresponding partition potentials support the orbital-interaction picture of hydrogen-bond formation.

  6. Development of partitioning method. Back-extraction of uranium from DIDPA solvent

    International Nuclear Information System (INIS)

    A partitioning method has been developed under the concepts of separation of elements in high level liquid waste generated from nuclear fuel reprocessing according to their half lives and radiological toxicity and of disposal of them by suitable methods. In the partitioning process developed in JAERI solvent, extraction with DIDPA (di-isodecyl phosphoric acid) was adopted for actinide separation. The present paper describes the results of study on back-extraction of hexavalent uranium from DIDPA. Most experiments were carried out to select a suitable reagent for back-extraction of U (VI) extracted from 0.5M nitric acid with DIDPA. The experimental results show that distribution ratios of U (VI) is less than 0.1 in the back-extractions with 1.5M sodium carbonate-15 vol% alcohol or 20wt% hydrazine carbonate-10 vol% alcohol. Uranium in the sodium carbonate solution were recovered by anion-exchange with strong-base resins and eluted by NH4NO3 and other reagents. The results of the present study confirm the validity of the DIDPA extraction process; U, Pu, Np, Am and Cm in HLW are extracted simultaneously with DIDPA, and they are recovered from DIDPA with various reagent: nitric acid for Am and Cm, oxalic acid for Np and Pu, and sodium carbonate or hydrazine carbonate for U. (author)

  7. Vacuole Partitioning during Meiotic Division in Yeast

    OpenAIRE

    Roeder, A D; Shaw, J.M.

    1996-01-01

    We have examined the partitioning of the yeast vacuole during meiotic division. In pulse-chase experiments, vacuoles labeled with the lumenal ade2 fluorophore or the membrane-specific dye FM 4-64 were not inherited by haploid spores. Instead, these fluorescent markers were excluded from spores and trapped between the spore cell walls and the ascus. Serial optical sections using a confocal microscope confirmed that spores did not inherit detectable amounts of fluorescently labeled vacuoles. Mo...

  8. Subsets of configurations and canonical partition functions

    DEFF Research Database (Denmark)

    Bloch, J.; Bruckmann, F.; Kieburg, M.;

    2013-01-01

    We explain the physical nature of the subset solution to the sign problem in chiral random matrix theory: the subset sum over configurations is shown to project out the canonical determinant with zero quark charge from a given configuration. As the grand canonical chiral random matrix partition f...... function is independent of the chemical potential, the zero-quark-charge sector provides the full result. © 2013 American Physical Society....

  9. Space partitioning without territoriality in gannets

    OpenAIRE

    Wakefield, Ewan D.; Bodey, Thomas W.; Bearhop, Stuart; Blackburn, Jez; Colhoun, Kendrew; Davies, Rachel; Dwyer, Ross G.; Green, Jonathan A; Gremillet, David; Jackson, Andrew L.; Jessopp, Mark J; Kane, Adam; Langston, Rowena H.W.; Lescroel, Amélie; Murray, Stuart

    2013-01-01

    Colonial breeding is widespread among animals. Some, such as eusocial insects, may use agonistic behavior to partition available foraging habitat into mutually exclusive territories; others, such as breeding seabirds, do not. We found that northern gannets, satellite-tracked from twelve neighboring colonies, nonetheless forage in largely mutually exclusive areas and that these colony-specific home ranges are determined by density-dependent competition. This segregation may be enhanced by indi...

  10. Efficient partitioning strategies for distributed Web crawling

    OpenAIRE

    Exposto, José; Macedo, Joaquim; Pina, António; Alves, Albano; Rufino, José

    2007-01-01

    This paper presents a multi-objective approach to Web space partitioning, aimed to improve distributed crawling efficiency. The in- vestigation is supported by the construction of two different weighted graphs. The first is used to model the topological communication infras- tructure between crawlers and Web servers and the second is used to represent the amount of link connections between servers’ pages. The values of the graph edges represent, respectively, computed RTTs and pages links bet...

  11. Biogeography of time partitioning in mammals

    OpenAIRE

    J Bennie; JP Duffy; R Inger; KJ Gaston

    2014-01-01

    The majority of mammal species are nocturnal, but many are diurnal (active during the day), crepuscular (active mostly during twilight), or cathemeral (active during hours of daylight and darkness). These different strategies for regulating activity over a 24-h cycle are associated with suites of adaptations to light or semidarkness. The biogeography of these time partitioning strategies is, however, poorly understood. We show that global patterns in mammal diversity with different diel activ...

  12. Innovative masonry blocks for partition walls

    OpenAIRE

    Vasconcelos, Graça; Poletti, Elisa; Medeiros, Pedro; Mendonça, Paulo; Carvalho, Pedro; Cunha, Sandra Raquel Leite; Camões, Aires; Lourenço, Paulo B.

    2010-01-01

    This paper intends to propose a non structural system of partition walls with monolithic blocks based on a composite material resulting from an admixture of cork and textile fibers combined with a non cement binder, gypsum. These blocks consist of two half blocks which have to be connected during laying process. The developed blocks were first tested under compressive and flexural loading in order to derive their mechanical behaviour. Different curing conditions were applied to the blocks dur...

  13. Recursive Partitioning Method on Competing Risk Outcomes

    OpenAIRE

    Xu, Wei; Che, Jiahua; KONG, QIN

    2016-01-01

    In some cancer clinical studies, researchers have interests to explore the risk factors associated with competing risk outcomes such as recurrence-free survival. We develop a novel recursive partitioning framework on competing risk data for both prognostic and predictive model constructions. We define specific splitting rules, pruning algorithm, and final tree selection algorithm for the competing risk tree models. This methodology is quite flexible that it can corporate both semiparametric m...

  14. Carbon Solubility in Core Melts in Shallow Magma Ocean Environment and its bearing on Distribution of Carbon between Deep Earth Reservoirs

    Science.gov (United States)

    Dasgupta, R.; Walker, D.

    2007-12-01

    Carbon affects the melting phase relations of mantle rocks [1] and core metal [2], influences the physical properties of molten silicates and metals, and also has significant effect on partitioning of other key elements between various deep Earth phases. But the carbon budget of Earth's deep mantle and core is poorly constrained due to lack of knowledge of behavior of carbon during core formation. In order to determine the storage capacity of dissolved carbon in metallic core melts and to put constraints on partitioning of carbon between silicate mantle and metallic core, we have determined the solubility of carbon in molten core metal at P- T conditions relevant for a shallow magma ocean.Experiments are performed at 2 GPa and to 2500 °C using a piston cylinder apparatus. Pure Fe-rod or a mixture of Fe-5.2%Ni loaded into graphite capsules were used as starting materials. Al coated run products are analyzed by EMP. Carbon concentration of 5.8 ± 0.4 wt.% at 2000 °C, 6.5 ± 0.9 wt.% at 2250 °C, and 7.5 ± 1.2 wt.% at 2500 °C are measured in quenched iron melt saturated with graphite. The trend of C solubility versus temperature for Fe-5.2 wt.% Ni melt, within analytical uncertainties, is similar to that of pure Fe.We have compared our solubility data and an estimate of the current carbon content of the mantle with the carbon content of core melts and residual mantle silicates respectively, derived from equilibrium batch or fractional segregation of core liquids, to constrain the partition coefficient of carbon between silicate and metallic melts in a magma ocean, DC. Translation of the limits of DC, derived from our solubility data, on calculation of carbon content of the residual silicate shows that the observed mantle concentration of carbon is too low to be matched by the process of shallow magma ocean fractionation of carbon between metal and silicate in a chondritic protoearth. If carbon solubility in liquid Fe does not change strongly as a function of

  15. SCORE SETS IN ORIENTED 3-PARTITE GRAPHS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Let D(U, V, W) be an oriented 3-partite graph with |U|=p, |V|=q and |W|= r. For any vertex x in D(U, V, W), let d+x and d-x be the outdegree and indegree of x respectively. Define aui (or simply ai) = q + r + d+ui - d-ui, bvj(or simply bj) = p + r + d+vj - d-vj and Cwk (or simply ck) = p + q + d+wk - d-wk as the scores of ui in U, vj in V and wk in Wrespectively. The set A of distinct scores of the vertices of D(U, V, W) is called its score set. In this paper, we prove that if a1 is a non-negative integer, ai(2≤i≤n - 1) are even positive integers and an is any positive integer, then for n≥3, there exists an oriented 3-partite graph with the score set A = {a1,2∑i=1 ai,…,n∑i=1 ai}, except when A = {0,2,3}. Some more results for score sets in oriented 3-partite graphs are obtained.

  16. 省域碳排放影响因素比较研究%Comparative Study on the Factors Affecting the Provincial Carbon Emissions

    Institute of Scientific and Technical Information of China (English)

    欧元明; 周少甫

    2014-01-01

    分析碳排放情况,本文发现人均碳排放和碳排放密度之间没有必然联系;碳排放密度存在明显的空间群集效应。基于 LMDI 方法分解,发现人均产出起拉动作用,而能源效率和能源消费碳排放强度则主要是抑制作用。基于 STIRPAT 模型分析,发现人均总产出水平、单位产出的化石能源消耗量、煤炭消费占比均对碳排放有显著的强化作用。建议:大力发展便捷的公共交通、倡导绿色出行,减轻交通对大城市碳排放的压力;通过改变能源结构,通过电力能源生产外迁等方式降低排放密度超高的地区碳排放压力、开发清洁能源,降低二氧化碳高排放能源消费占比;对高能耗产业逐步实施“产能总量控制---限制出口---进口替代”路径的产业优化措施,逐步减轻“输入性碳排放”压力。%Based on descriptive statistics analysis method to analyze the 30 provinces and autonomous regions and the country’s car-bon dioxide emissions ,this paper found : per capita carbon emissions and carbon emissions density are not necessarily linked , secondary energy output region’s per capita carbon emissions are high ,and the density of carbon emissions is low ;carbon emissions density had obvi-ously spatial clustering effect .The LMDI method is used to decompose on the driving factors based on carbon emissions per capita ,found that per capita output has stimulating effect ,while energy efficiency and carbon intensity of energy consumption are inhibited .Based on analysis of influencing factors by STIRPAT model ,we found that per capita output ,fossil energy consumption per unit of output ,coal con-sumption accounted for carbon emissions have a significant strengthening effect .Thus it recommends to vigorously develop the convenient public transportation ,promote green travel ,and reduce traffic pressure on the city carbon emissions ; as supplementary carbon trading ,by changing

  17. Effect of Mg Addition on Inhibiting Austenite Grain Growth in Heat Affected Zones of Ti-Bearing Low Carbon Steels%Effect of Mg Addition on Inhibiting Austenite Grain Growth in Heat Affected Zones of Ti-Bearing Low Carbon Steels

    Institute of Scientific and Technical Information of China (English)

    ZHU Kai; YANG Jian; WANG Rui-zhi; YANG Zhen-guo

    2011-01-01

    To study the effect of Mg addition on inhibiting weld heat affected zones (HAZ) austenite grain growth of Ti-bearing low carbon steels, two steels with and without Mg treated were prepared using a laboratory vacuum. The welding testing was simulated by Gleeble 3500 thermomechanical simulator. The performance of HAZ was investiga ted that the toughness was improved from 3.3 to 185 J by adding 0. 005%Mg (in mass percent) to the steel, and the fracture mechanism changed from cleavage fracture to toughness fracture. Through in-situ observation by a confocal scanning laser microscope, a significant result was found that the austenite grain of the steel with Mg treated was still keeping fine-grained structure after holding at 1 400℃ and lasting for 300 s. This inhibition of austenite grain growth was mainly attributed to the formation of pinning particles after the addition of Mg. The obtained results pro pose a potential method for improving HAZ toughness of structure steels.

  18. Safety-Critical Partitioned Software Architecture: A Partitioned Software Architecture for Robotic

    Science.gov (United States)

    Horvath, Greg; Chung, Seung H.; Cilloniz-Bicchi, Ferner

    2011-01-01

    The flight software on virtually every mission currently managed by JPL has several major flaws that make it vulnerable to potentially fatal software defects. Many of these problems can be addressed by recently developed partitioned operating systems (OS). JPL has avoided adopting a partitioned operating system on its flight missions, primarily because doing so would require significant changes in flight software design, and the risks associated with changes of that magnitude cannot be accepted by an active flight project. The choice of a partitioned OS can have a dramatic effect on the overall system and software architecture, allowing for realization of benefits far beyond the concerns typically associated with the choice of OS. Specifically, we believe that a partitioned operating system, when coupled with an appropriate architecture, can provide a strong infrastructure for developing systems for which reusability, modifiability, testability, and reliability are essential qualities. By adopting a partitioned OS, projects can gain benefits throughout the entire development lifecycle, from requirements and design, all the way to implementation, testing, and operations.

  19. Polyacrylate–water partitioning of biocidal compounds: Enhancing the understanding of biocide partitioning between render and water

    DEFF Research Database (Denmark)

    Bollmann, Ulla E.; Ou, Yi; Mayer, Philipp;

    2014-01-01

    between the polymer - in this case polyacrylate - and water were studied using glass fibre filters coated with polyacrylate. The polyacrylate-water partition constants (logKAcW) of ten biocides used in construction material varied between 1.66 (isoproturon) and 3.57 (dichloro-N-octylisothiazolinone). The...... correlation of the polyacrylate-water partition constants with the octanol-water partition constants is significant, but the polyacrylate-water partition constants were predominantly below octanol-water partition constants (Kow). The comparison with render-water distribution constants showed that estimating...

  20. Determination of Aroma Compound Partition Coefficients in Aqueous, Polysaccharide, and Dairy Matrices Using the Phase Ratio Variation Method: A Review and Modeling Approach.

    Science.gov (United States)

    Heilig, Andrej; Sonne, Alina; Schieberle, Peter; Hinrichs, Jörg

    2016-06-01

    The partition of aroma compounds between a matrix and a gas phase describes an individual compound's specific affinity toward the matrix constituents affecting orthonasal sensory perception. The static headspace phase ratio variation (PRV) method has been increasingly applied by various authors to determine the equilibrium partition coefficient K in aqueous, polysaccharide, and dairy matrices. However, reported partition coefficients are difficult to relate and compare due to different experimental conditions, e.g., aroma compound selection, matrix composition, equilibration temperature. Due to its specific advantages, the PRV method is supposed to find more frequent application in the future, this Review aims to summarize, evaluate, compare, and relate the currently available data on PRV-determined partition coefficients. This process was designed to specify the potentials and the limitations as well as the consistency of the PRV method, and to identify open fields of research in aroma compound partitioning in food-related, especially dairy matrices. PMID:27182770

  1. LHCb: Optimising query execution time in LHCb Bookkeeping System using partition pruning and partition wise joins

    CERN Multimedia

    Mathe, Z

    2013-01-01

    The LHCb experiment produces a huge amount of data which has associated metadata such as run number, data taking condition (detector status when the data was taken), simulation condition, etc. The data are stored in files, replicated on the Computing Grid around the world. The LHCb Bookkeeping System provides methods for retrieving datasets based on their metadata. The metadata is stored in a hybrid database model, which is a mixture of Relational and Hierarchical database models and is based on the Oracle Relational Database Management System (RDBMS). The database access has to be reliable and fast. In order to achieve a high timing performance, the tables are partitioned and the queries are executed in parallel. When we store large amounts of data the partition pruning is essential for database performance, because it reduces the amount of data retrieved from the disk and optimises the resource utilisation. This research presented here is focusing on the extended composite partitioning strategy such as rang...

  2. Free atmospheric CO2 enrichment did not affect symbiotic N2 - Fixation and soil carbon dynamics in a mixed deciduous stand in Wales

    NARCIS (Netherlands)

    Hoosbeek, M.R.; Lukac, M.; Velthorst, E.J.; Godbold, D.

    2010-01-01

    Through increases in net primary production (NPP), elevated CO2 is hypothesizes to increase the amount of plant litter entering the soil. The fate of this extra carbon on the forest floor or in mineral soil is currently not clear. Moreover, increased rates of NPP can be maintained only if forests ca

  3. Modeling the cathode in a proton exchange membrane fuel cell using density functional theory How the carbon support can affect durability and activity of a platinum catalyst

    Science.gov (United States)

    Groves, Michael Nelson

    The current global energy and environmental challenges need to be addressed by developing a new portfolio of clean power producing devices. The proton exchange membrane fuel cell has the potential to be included and can fit into a variety of niches ranging from portable electronics to stationary residential applications. One of the many barriers to commercial viability is the cost of the cathode layer which requires too much platinum metal to achieve a comparable power output as well as would need to be replaced more frequently when compared to conventional sources for most applications. Using density functional theory, an ab initio modeling technique, these durability and activity issues are examined for platinum catalysts on graphene and carbon nanotube supports. The carbon supports were also doped by replacing individual carbon atoms with other second row elements (beryllium, boron, nitrogen, and oxygen) and the effect on the platinum-surface interaction along with the interaction between the platinum and the oxygen reduction reaction intermediates are discussed. Keywords: proton exchange membrane fuel cell, density functional theory, platinum catalyst, oxygen reduction reaction, doped carbon surfaces

  4. The EGFR mutation status affects the relative biological effectiveness of carbon-ion beams in non-small cell lung carcinoma cells.

    Science.gov (United States)

    Amornwichet, Napapat; Oike, Takahiro; Shibata, Atsushi; Nirodi, Chaitanya S; Ogiwara, Hideaki; Makino, Haruhiko; Kimura, Yuka; Hirota, Yuka; Isono, Mayu; Yoshida, Yukari; Ohno, Tatsuya; Kohno, Takashi; Nakano, Takashi

    2015-06-11

    Carbon-ion radiotherapy (CIRT) holds promise to treat inoperable locally-advanced non-small cell lung carcinoma (NSCLC), a disease poorly controlled by standard chemoradiotherapy using X-rays. Since CIRT is an extremely limited medical resource, selection of NSCLC patients likely to benefit from it is important; however, biological predictors of response to CIRT are ill-defined. The present study investigated the association between the mutational status of EGFR and KRAS, driver genes frequently mutated in NSCLC, and the relative biological effectiveness (RBE) of carbon-ion beams over X-rays. The assessment of 15 NSCLC lines of different EGFR/KRAS mutational status and that of isogenic NSCLC lines expressing wild-type or mutant EGFR revealed that EGFR-mutant NSCLC cells, but not KRAS-mutant cells, show low RBE. This was attributable to (i) the high X-ray sensitivity of EGFR-mutant cells, since EGFR mutation is associated with a defect in non-homologous end joining, a major pathway for DNA double-strand break (DSB) repair, and (ii) the strong cell-killing effect of carbon-ion beams due to poor repair of carbon-ion beam-induced DSBs regardless of EGFR mutation status. These data highlight the potential of EGFR mutation status as a predictor of response to CIRT, i.e., CIRT may show a high therapeutic index in EGFR mutation-negative NSCLC.

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

    Science.gov (United States)

    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.

  6. Simulation of land-use patterns affecting the global carbon cycle. [Reconstruction and projection of CO/sub 2/ scenarios from 1860 to 2460

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Y.H.; Olson, J.S.; Emanuel, W.R.

    1979-01-01

    Past increase of atmospheric CO/sub 2/ involves significant ntributions from both fossil and nonfossil (biospheric) sources. A simulation model was used to reconstruct changes since 1860 and project four hypothetical future scenarios of CO/sub 2/ injection to 2460. Nineteen compartments and their exchanges of carbon were considered. Areal extent of tropical forests, other wooded ecosystems, and nonforests were incorporated into the model. Rapidly and slowly exchanging pools of carbon per unit area, and net primary production for each pool and exosystem group, were projected by integrating income-loss differential equations numerically using CSMP programming language. Estimated cumulative releases of CO/sub 2/ from fossil fuels (plus cement) near 120 Gtons of carbon (1 Gton = 10/sup 9/ metric tons) from 1860 to 1970 were assumed to equal prompt and delayed releases from forest clearing. Limits of exploitable forest area and biomass were evaluated and found to contribute much less future CO/sub 2/ than the usable coal, oil, gas, and oil shale. Ultimate release from the latter (7500 +- 2500 x 10/sup 9/ tons of C) could increase atmospheric CO/sub 2/ manyfold: doubling the assumed 1860 levels as early as (1) year 2025 for assumed nominal scenario (expanding releases slightly less rapidly than at present), (2) year 2033 for a delayed expansion scenario that would prolong use of fossil reserves (lowering peak carbon release rate from approx. 43 to approx. 28 Gtons/year), (3) year 2087 for a slow burner scenario (increasing very slowly from present levels), and (4) year 2290 for a combination scenario (which assumes low fossil-fuel use, high carbon storage, and high net primary production of forested exosystems).

  7. Hydroturbine operating region partitioning based on analyses of unsteady flow field and dynamic response

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The operating states of hydroelectric generating units vary widely as the operating condition change. The details of the operating characteristics and the operating region partitioning method are discussed for two types of large Francis turbines in the Wanjiazhai Hydropower Plant and two same type large Kaplan turbines in the Shuikou Hydropower Plant. For the Wanjiazhai Hydropower units, the most critical factor affecting the operating stability is the hydraulic pressure fluctuations caused by the vortex rope in the draft tube. For Shuikou Hydropower units, the dynamic stresses as in the piston rod and the blade and the hydraulic thrust on the runner induced by the pressure fluctuations in the flow passage should be used to partition the operating regions. Analyzing the distribution cloud of operating characteristic factors which affects the operating stability in the hill-chart for each individual unit, the forbidden, stable and transient operating regions can be obtained.

  8. Partition of some key regulating services in terrestrial ecosystems: Meta-analysis and review.

    Science.gov (United States)

    Viglizzo, E F; Jobbágy, E G; Ricard, M F; Paruelo, J M

    2016-08-15

    Our knowledge about the functional foundations of ecosystem service (ES) provision is still limited and more research is needed to elucidate key functional mechanisms. Using a simplified eco-hydrological scheme, in this work we analyzed how land-use decisions modify the partition of some essential regulatory ES by altering basic relationships between biomass stocks and water flows. A comprehensive meta-analysis and review was conducted based on global, regional and local data from peer-reviewed publications. We analyzed five datasets comprising 1348 studies and 3948 records on precipitation (PPT), aboveground biomass (AGB), AGB change, evapotranspiration (ET), water yield (WY), WY change, runoff (R) and infiltration (I). The conceptual framework was focused on ES that are associated with the ecological functions (e.g., intermediate ES) of ET, WY, R and I. ES included soil protection, carbon sequestration, local climate regulation, water-flow regulation and water recharge. To address the problem of data normality, the analysis included both parametric and non-parametric regression analysis. Results demonstrate that PPT is a first-order biophysical factor that controls ES release at the broader scales. At decreasing scales, ES are partitioned as result of PPT interactions with other biophysical and anthropogenic factors. At intermediate scales, land-use change interacts with PPT modifying ES partition as it the case of afforestation in dry regions, where ET and climate regulation may be enhanced at the expense of R and water-flow regulation. At smaller scales, site-specific conditions such as topography interact with PPT and AGB displaying different ES partition formats. The probable implications of future land-use and climate change on some key ES production and partition are discussed. PMID:27096628

  9. Resource Partitioning between Bacteria, Fungi, and Protists in the Detritusphere of an Agricultural Soil

    Science.gov (United States)

    Kramer, Susanne; Dibbern, Dörte; Moll, Julia; Huenninghaus, Maike; Koller, Robert; Krueger, Dirk; Marhan, Sven; Urich, Tim; Wubet, Tesfaye; Bonkowski, Michael; Buscot, François; Lueders, Tillmann; Kandeler, Ellen

    2016-01-01

    The flow of plant-derived carbon in soil is a key component of global carbon cycling. Conceptual models of trophic carbon fluxes in soil have assumed separate bacterial and fungal energy channels in the detritusphere, controlled by both substrate complexity and recalcitrance. However, detailed understanding of the key populations involved and niche-partitioning between them is limited. Here, a microcosm experiment was performed to trace the flow of detritusphere C from substrate analogs (glucose, cellulose) and plant biomass amendments (maize leaves, roots) in an agricultural soil. Carbon flow was traced by rRNA stable isotope probing and amplicon sequencing across three microbial kingdoms. Distinct lineages within the Actinobacteria, Bacteroidetes, Gammaproteobacteria, Basidiomycota, Ascomycota as well as Peronosporomycetes were identified as important primary substrate consumers. A dynamic succession of primary consumers was observed especially in the cellulose treatments, but also in plant amendments over time. While intra-kingdom niche partitioning was clearly observed, distinct bacterial and fungal energy channels were not apparent. Furthermore, while the diversity of primary substrate consumers did not notably increase with substrate complexity, consumer succession and secondary trophic links to bacterivorous and fungivorous microbes resulted in increased food web complexity in the more recalcitrant substrates. This suggests that rather than substrate-defined energy channels, consumer succession as well as intra- and inter-kingdom cross-feeding should be considered as mechanisms supporting food web complexity in the detritusphere. PMID:27725815

  10. Glycosylation-mediated phenylpropanoid partitioning in Populus tremuloides cell cultures

    Directory of Open Access Journals (Sweden)

    Babst Benjamin A

    2009-12-01

    Full Text Available Abstract Background Phenylpropanoid-derived phenolic glycosides (PGs and condensed tannins (CTs comprise large, multi-purpose non-structural carbon sinks in Populus. A negative correlation between PG and CT concentrations has been observed in several studies. However, the molecular mechanism underlying the relationship is not known. Results Populus cell cultures produce CTs but not PGs under normal conditions. Feeding salicyl alcohol resulted in accumulation of salicins, the simplest PG, in the cells, but not higher-order PGs. Salicin accrual reflected the stimulation of a glycosylation response which altered a number of metabolic activities. We utilized this suspension cell feeding system as a model for analyzing the possible role of glycosylation in regulating the metabolic competition between PG formation, CT synthesis and growth. Cells accumulated salicins in a dose-dependent manner following salicyl alcohol feeding. Higher feeding levels led to a decrease in cellular CT concentrations (at 5 or 10 mM, and a negative effect on cell growth (at 10 mM. The competition between salicin and CT formation was reciprocal, and depended on the metabolic status of the cells. We analyzed gene expression changes between controls and cells fed with 5 mM salicyl alcohol for 48 hr, a time point when salicin accumulation was near maximum and CT synthesis was reduced, with no effect on growth. Several stress-responsive genes were up-regulated, suggestive of a general stress response in the fed cells. Salicyl alcohol feeding also induced expression of genes associated with sucrose catabolism, glycolysis and the Krebs cycle. Transcript levels of phenylalanine ammonia lyase and most of the flavonoid pathway genes were reduced, consistent with down-regulated CT synthesis. Conclusions Exogenous salicyl alcohol was readily glycosylated in Populus cell cultures, a process that altered sugar utilization and phenolic partitioning in the cells. Using this system, we

  11. Lattice points and simultaneous core partitions

    OpenAIRE

    Johnson, Paul

    2015-01-01

    We observe that for a and b relatively prime, the "abacus construction" identifies the set of simultaneous (a,b)-core partitions with lattice points in a rational simplex. Furthermore, many statistics on (a,b)-cores are piecewise polynomial functions on this simplex. We apply these results to rational Catalan combinatorics. Using Ehrhart theory, we reprove Anderson's theorem that there are (a+b-1)!/a!b! simultaneous (a,b)-cores, and using Euler-Maclaurin theory we prove Armstrong's conjecture...

  12. A heating partition for a coking furnace

    Energy Technology Data Exchange (ETDEWEB)

    Strelov, K.K.; Ivanova, A.V.; Kaufman, A.A.; Kuznetsov, G.I.; Likhogub, Ye.P.; Turman, D.S.; Varshavskiy, T.P.; Volfovskiy, G.M.

    1983-01-01

    A coking furnace heating partition (OPKT) is proposed in order to increase reliability by increasing its strength. The proposal includes equipping with a vertical wall (St) made of Dinas brick and positioning it along the longitudinal axis of the coking furnace heating panel. The dividing walls are made of Dinas brick and their faces are disposed between the bricks of the wall of the coking chamber (KK). The surface of the coking chamber wall is made from magnesite or corundum brick which makes up 70 to 80 percent of the operational surface (Pv) of the wall. The presence of the vertical wall in combination with the

  13. Space partitioning without territoriality in gannets.

    Science.gov (United States)

    Wakefield, Ewan D; Bodey, Thomas W; Bearhop, Stuart; Blackburn, Jez; Colhoun, Kendrew; Davies, Rachel; Dwyer, Ross G; Green, Jonathan A; Grémillet, David; Jackson, Andrew L; Jessopp, Mark J; Kane, Adam; Langston, Rowena H W; Lescroël, Amélie; Murray, Stuart; Le Nuz, Mélanie; Patrick, Samantha C; Péron, Clara; Soanes, Louise M; Wanless, Sarah; Votier, Stephen C; Hamer, Keith C

    2013-07-01

    Colonial breeding is widespread among animals. Some, such as eusocial insects, may use agonistic behavior to partition available foraging habitat into mutually exclusive territories; others, such as breeding seabirds, do not. We found that northern gannets, satellite-tracked from 12 neighboring colonies, nonetheless forage in largely mutually exclusive areas and that these colony-specific home ranges are determined by density-dependent competition. This segregation may be enhanced by individual-level public information transfer, leading to cultural evolution and divergence among colonies. PMID:23744776

  14. Fractal in the statistics of Goldbach partition

    OpenAIRE

    Liang, Wang; Yan, Huang; Zhi-cheng, Dai

    2006-01-01

    Some interesting chaos phenomena have been found in the difference of prime numbers. Here we discuss a theme about the sum of two prime numbers, Goldbach conjecture. This conjecture states that any even number could be expressed as the sum of two prime numbers. Goldbach partition r(n) is the number of representations of an even number n as the sum of two primes. This paper analyzes the statistics of series r(n) (n=4,6,8,...). The familiar 3 period oscillations in histogram of difference of co...

  15. Zero-sum partition theorems for graphs

    Directory of Open Access Journals (Sweden)

    Y. Caro

    1994-01-01

    Full Text Available Let q=pn be a power of an odd prime p. We show that the vertices of every graph G can be partitioned into t(q classes V(G=⋃t=1t(qVi such that the number of edges in any induced subgraph 〈Vi〉 is divisible by q, where t(q≤32(q−1−(2(q−1−1124+98, and if q=2n, then t(q=2q−1.

  16. Fractal Dimension Computation From Equal Mass Partitions

    CERN Document Server

    Shiozawa, Yui; Rouet, Jean-Louis

    2015-01-01

    While the numerical methods which utilizes partitions of equal-size, including the box-counting method, remain the most popular choice for computing the generalized dimension of multifractal sets, two mass- oriented methods are investigated by applying them to the one-dimensional generalized Cantor set. We show that both mass-oriented methods generate relatively good results for generalized dimensions for important cases where the box-counting method is known to fail. Both the strengths and limitations of the methods are also discussed.

  17. A framework to assess biogeochemical response to ecosystem disturbance using nutrient partitioning ratios

    Science.gov (United States)

    Kranabetter, J. Marty; McLauchlan, Kendra K.; Enders, Sara K.; Fraterrigo, Jennifer M.; Higuera, Philip E.; Morris, Jesse L.; Rastetter, Edward B.; Barnes, Rebecca; Buma, Brian; Gavin, Daniel G.; Gerhart, Laci M.; Gillson, Lindsey; Hietz, Peter; Mack, Michelle C.; McNeil, Brenden; Perakis, Steven

    2016-01-01

    Disturbances affect almost all terrestrial ecosystems, but it has been difficult to identify general principles regarding these influences. To improve our understanding of the long-term consequences of disturbance on terrestrial ecosystems, we present a conceptual framework that analyzes disturbances by their biogeochemical impacts. We posit that the ratio of soil and plant nutrient stocks in mature ecosystems represents a characteristic site property. Focusing on nitrogen (N), we hypothesize that this partitioning ratio (soil N: plant N) will undergo a predictable trajectory after disturbance. We investigate the nature of this partitioning ratio with three approaches: (1) nutrient stock data from forested ecosystems in North America, (2) a process-based ecosystem model, and (3) conceptual shifts in site nutrient availability with altered disturbance frequency. Partitioning ratios could be applied to a variety of ecosystems and successional states, allowing for improved temporal scaling of disturbance events. The generally short-term empirical evidence for recovery trajectories of nutrient stocks and partitioning ratios suggests two areas for future research. First, we need to recognize and quantify how disturbance effects can be accreting or depleting, depending on whether their net effect is to increase or decrease ecosystem nutrient stocks. Second, we need to test how altered disturbance frequencies from the present state may be constructive or destructive in their effects on biogeochemical cycling and nutrient availability. Long-term studies, with repeated sampling of soils and vegetation, will be essential in further developing this framework of biogeochemical response to disturbance.

  18. Factors affecting the indoor concentrations of carbonaceous aerosols of outdoor origin

    Energy Technology Data Exchange (ETDEWEB)

    Lunden, Melissa M.; Kirchstetter, Thomas W.; Thatcher, Tracy L.; Hering, Susanne V.; Brown, Nancy J.

    2007-06-25

    A field study was conducted in an unoccupied single story residence in Clovis, California to provide data to address issues important to assess the indoor exposure to particles of outdoor origin. Measurements of black and organic carbonaceous aerosols were performed using a variety of methods, resulting in both near real-time measurements as well as integrated filter based measurements. Comparisons of the different measurement methods show that it is crucial to account for gas phase adsorption artifacts when measuring organic carbon (OC). Measured concentrations affected by the emissions of organic compounds sorbed to indoor surfaces imply a higher degree of infiltration of outdoor organic carbon aerosols into the indoor environment for our unoccupied house. Analysis of the indoor and outdoor data for black carbon (BC) aerosols show that, on average, the indoor concentration of black carbon aerosols behaves in a similar manner to sulfate aerosols. In contrast, organic carbon aerosols are subject to chemical transformations indoors that, for our unoccupied home, resulted in lower indoor OC concentrations than would be expected by physical loss mechanisms alone. These results show that gas to particle partitioning of organic compounds, as well as gas to surface interactions within the residence, are an important process governing the indoor concentration to OC aerosols of outdoor origin.

  19. Salinity and nutrient contents of tidal water affects soil respiration and carbon sequestration of high and low tidal flats of Jiuduansha wetlands in different ways.

    Science.gov (United States)

    Hu, Yu; Wang, Lei; Fu, Xiaohua; Yan, Jianfang; Wu, Jihua; Tsang, Yiufai; Le, Yiquan; Sun, Ying

    2016-09-15

    Soils were collected from low tidal flats and high tidal flats of Shang shoal located upstream and Xia shoal located downstream with different tidal water qualities, in the Jiuduansha wetland of the Yangtze River estuary. Soil respiration (SR) in situ and soil abiotic and microbial characteristics were studied to clarify the respective differences in the effects of tidal water salinity and nutrient levels on SR and soil carbon sequestration in low and high tidal flats. In low tidal flats, higher total nitrogen (TN) and lower salinity in the tidal water of Shang shoal resulted in higher TN and lower salinity in its soils compared with Xia shoal. These would benefit β-Proteobacteria and Anaerolineae in Shang shoal soil, which might have higher heterotrophic microbial activities and thus soil microbial respiration and SR. In low tidal flats, where soil moisture was high and the major carbon input was active organic carbon from tidal water, increasing TN was a more important factor than salinity and obviously enhanced soil microbial heterotrophic activities, soil microbial respiration and SR. While, in high tidal flats, higher salinity in Xia shoal due to higher salinity in tidal water compared with Shang shoal benefited γ-Proteobacteria which might enhance autotrophic microbial activity, and was detrimental to β-Proteobacteria in Xia shoal soil. These might have led to lower soil microbial respiration and thus SR in Xia shoal compared with Shang shoal. In high tidal flats, where soil moisture was relatively lower and the major carbon input was plant biomass that was difficult to degrade, soil salinity was the major factor restraining microbial activities, soil microbial respiration and SR. PMID:27208721

  20. Niche Partitioning of Feather Mites within a Seabird Host, Calonectris borealis

    Science.gov (United States)

    Stefan, Laura M.; Gómez-Díaz, Elena; Elguero, Eric; Proctor, Heather C.; McCoy, Karen D.; González-Solís, Jacob

    2015-01-01

    According to classic niche theory, species can coexist in heterogeneous environments by reducing interspecific competition via niche partitioning, e.g. trophic or spatial partitioning. However, support for the role of competition on niche partitioning remains controversial. Here, we tested for spatial and trophic partitioning in feather mites, a diverse and abundant group of arthropods. We focused on the two dominant mite species, Microspalax brevipes and Zachvatkinia ovata, inhabiting flight feathers of the Cory’s shearwater, Calonectris borealis. We performed mite counts across and within primary and tail feathers on free-living shearwaters breeding on an oceanic island (Gran Canaria, Canary Islands). We then investigated trophic relationships between the two mite species and the host using stable isotope analyses of carbon and nitrogen on mite tissues and potential host food sources. The distribution of the two mite species showed clear spatial segregation among feathers; M. brevipes showed high preference for the central wing primary feathers, whereas Z. ovata was restricted to the two outermost primaries. Morphological differences between M. brevipes and Z. ovata support an adaptive basis for the spatial segregation of the two mite species. However, the two mites overlap in some central primaries and statistical modeling showed that Z. ovata tends to outcompete M. brevipes. Isotopic analyses indicated similar isotopic values for the two mite species and a strong correlation in carbon signatures between mites inhabiting the same individual host suggesting that diet is mainly based on shared host-associated resources. Among the four candidate tissues examined (blood, feather remains, skin remains and preen gland oil), we conclude that the diet is most likely dominated by preen gland oil, while the contribution of exogenous material to mite diets is less marked. Our results indicate that ongoing competition for space and resources plays a central role in