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Harbin, Anne-Marie. "Inorganic nitrogen nutrients in natural waters." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240756.
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Dixon, G. K. "The inorganic nitrogen metabolism of marine dinoflagellates." Thesis, Swansea University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636452.
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Nitrogen-replete cells of <i>Amphidinium carterae</i> took up ammonium in the light at a rate 5 - 6 times that of nitrate even though exponential growth rates were similar on these two N-sources. <i>A. carterae</i> exhibited a capability for enhanced initial ammonium uptake, particularly when deprived of nitrogen. Enhanced initial rates of ammonium uptake were also observed in a natural population of <i>Gyrodinium aureolum</i>. Initially ammonium accumulated within the cells of <i>A. carterae</i> but was assimilated into organic-N within a matter of hours; increases in total cellular-N, total free amino acids, glutamine and cellular protein were observed 4 h after an ammonium addition. In comparison, very little nitrate was accumulated. Ammonium (250 μM) inhibited reversibly the uptake of nitrate; the rapidity of the response suggests a direct effect on uptake. Prior nitrogen deprivation of the cells did not affect this inhibition. Rates of ammonium uptake were similar in the light and dark but nitrate uptake was completely inhibited by darkness in nitrogen replete cells of <i>A. carterae</i> and in a natural population of G. aureolum. Dark uptake of nitrate was stimulated by a period of nitrogen deprivation. Ammonium uptake in darkness by <i>A. carterae</i> was accompanied by the utilization of cellular polysaccharide, mainly glucose polysaccharide. Most of this carbon was unavailable for the assimilation of nitrate in the dark. It is suggested that a control mechanism is in operation, via a product of ammonium assimilation, on one or more of the enzymes concerned with polysaccharide breakdown, e.g. α-amylase or phosphorylase. Ammonium addition caused a marked enhancement of dark CO<SUB>2</SUB> fixation in several nitrogen-replete dinoflagellates. Nitrate addition produced little enhancement in comparison. The amount of enhancement was dependent on species, age of culture and period of diel cycle. Nitrogen deprivation caused a 2-3 fold increase in enhancement in all species tested. The measurement of dark <SUP>14</SUP>CO<SUB>2</SUB> fixation shows promise as a technique for determining the nitrogen status of phytoplankton in both the laboratory and in the field. A natural population of <i>Gyrodinium aureolum</i> appeared to be slightly N-limited using this technique, an observation supported by other field data. The use of this technique as a tool to determine the nitrogen status of phytoplankton in culture and in the field is discussed.
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Saunders, Eleanor Margaret. "The effect of mineral nitrogen on ectomycorrhizas with special reference to nitrogen deposition." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299547.
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Wheildon, Andrew R. "Novel nitrogen chemistry." Thesis, University of Nottingham, 1999. http://eprints.nottingham.ac.uk/13326/.
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Chapter One contains a brief overview of zeolites, their structure, uses and synthesis. Chapter Two relates to the attempted synthesis of quinuclidines via a novel 6-endo-trig radical cyclisation. Chapter Three contains a review of the 'Zip reaction' and the attempted synthesis of triazacyclopentadecane derivatives. Chapter Four relates to the synthesis of pyrrolidines via retro-Cope cyclisation methodology. Reviews of the Cope and retro-Cope reactions, nitrone synthesis and nucleophilic addition of carbon nucleophiles to nitrones are included. The synthetic work is split into three sections relating to the electron withdrawing group used to stabilise the carbanion of the nucleophile - ester, sulphone and sulphoxide - and attempts to indicate the utility of the retro-Cope reaction in the diastereoselective synthesis of substituted pyrrolidines.
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Benítez, Juan Manuel González. "Quantification of atmospheric water soluble inorganic and organic nitrogen." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4635.
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The key aims of this project were: (i) investigation of atmospheric nitrogen deposition, focused on discrimination between bulk, wet and dry deposition, and between particulate matter and gas phase, (ii) accurate quantification of the contributions of dissolved organic and inorganic nitrogen to each type of deposition, and (iii) exploration of the origin and potential sources of atmospheric water soluble organic nitrogen (WSON). This project was particularly focused on the WSON fraction because, despite it being a potentially important source of bioavailable reactive nitrogen, a number of questions regarding its deposition mechanism (wet vs. dry), composition and origin (natural, anthropogenic or mixed) remain unanswered. There are two major difficulties in WSON determination: (i) the diversity of organic nitrogen compounds compared with the inorganic forms, and (ii) the lack of a direct determination method: the derivation of organic nitrogen concentrations in an aqueous sample involves the determination of the dissolved inorganic nitrogen (DIN) species concentration, comprising nitrate and ammonium, the determination of the total dissolved nitrogen (TDN) concentration, and the subtraction of the DIN concentrations from the TDN concentration. TDN determination requires a preparatory digestion step: high-temperature catalytic oxidation was the method used in this study. Ion chromatography (IC) was the method of choice for nitrate determination, whilst ammonium determination was by IC for rain samples, and by flow injection analysis for air samples collected into aqueous media. This thesis is structured in 3 main parts: the first part examines weekly rain data over a period of 22 months from June 2005 to March 2007 collected in 2 types of rain collector (bulk deposition and “dry+wet” deposition) located in a semi-rural area 15 km southwest of Edinburgh, UK (N55°51′44″, W3°12′19″). Bulk deposition collectors were the standard rain gauges used in the UK national network for monitoring precipitation composition. “Dry+wet” deposition collectors were flushing rain gauges equipped with a rain detector, a spray nozzle, a 2-way valve and two independent bottles to collect funnel washings (dry deposition) and true wet deposition. A key objective in this part of the work was the accurate quantification of inorganic and organic water-soluble nitrogen species contribution to each type of deposition. On average, for the 27 weekly samples with 3 valid replicates for the 2 types of collectors, DON represented 23% of the TDN in bulk deposition. Dry deposition of particles and gas on the funnel surface, rather than rain, contributed over half of all N-containing species (inorganic and organic). Some discrepancies were found between bulk and flushing rain gauges, for deposition of both TDN and DON, suggesting biological conversion and loss of inorganic N in the flushing samplers. The second stage of this project was the investigation of in situ atmospheric concentrations of WSN species, both organic and inorganic. Simultaneous daily measurements of ammonium, nitrate and WSON were made between July and November 2008 at the same semi-rural site in south-east Scotland. Discrimination between material from the gas and particle phases was achieved by means of Cofer scrubbers and PTFE membrane filters, respectively. Average concentrations of NH3 (determined as NH4+), NO2/HNO3 (determined as NO3-) and WSON in the gas phase were 82 ± 54 nmol N m-3, 2.6 ± 2.5 nmol N m-3 and 18 ± 12 nmol N m-3 respectively, and in the particle phase were 20 ± 24 nmol N m-3, 10 ± 9 nmol N m-3 and 8 ± 7 nmol N m-3 respectively (± represent standard deviation across all valid daily samples, not error of triplicate samples). Except for oxidised inorganic N, average concentrations in the gas phase were larger than in the particle phase. No evidence of solely agricultural or solely combustion sources of WSON was found, as no correlation in either phase between WSON and either NH4+ or NO3- could be established. The final stage of this project was to gain a broader picture of nitrogen deposition across Europe. Rain samples were analysed for TDN and DIN from a network of 21 different sampling locations, from the south of Portugal to the north of Finland. The average DON contribution across the 21 sampling sites was ~ 19% and, according to the data gathered in this study, DON species appeared largely unrelated specifically to agricultural or to combustion nitrogen sources, although the results varied widely from site to site. Overall, this work has shown that ON and its deposition comprises a significant component of total atmospheric reactive nitrogen.
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O'Neil, Paul Andrew. "Structural studies of some S-block nitrogen complexes." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335949.
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Davies, Craig Joseph. "Characterisation of rhodium complexes with nitrogen containing ligands." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337145.
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Griffith, G. A. "Transition metal fluoride derivatives with nitrogen-containing ligands." Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/33705.
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The reaction between WF6 and C6F5NH2 is found to proceed via iminolysis. 19F NMR analysis of acetonitrile (MeCN) solutions show the product to be a mixture containing [C6F5NH3]+[WF5(NC6F5)]-, [C6F5NH3]+[W2F9(NC6F5)2]-, [C6F5NH3]+F- and the unique mixed imido-, oxo-species [O=WF4-F-WF4(NC6F5)] - formed from traces of oxyfluoride impurities. The 19F nmr spectrum of a trifluoroacetic acid (TFA) solution showed the presence of the dimeric anion salt and fluorination products. An X-ray crystallographic study of a single crystal of [C6F5NH3]+[W2F9(NC6F5)2]-, grown from TFA, revealed the compound to adopt a triclinic (space group P1)structure, with two formula units in the unit cell, each with a slightly differing geometry about the bridging fluorine atom. The reaction of Me3SiNCO with MF6 (M= Mo,W) was examined. The products are assigned as MF5NCO3 from IR spectra recorded. The reaction between MoF6 and (Me3Si)2NH results in the formation of MoF4NH. Addition of MeCN to MoF4NH produces a 1:1 adduct, MoF4NH.MeCN. Analysis of the IR spectra of the two compounds indicates that MoF4NH adopts a cis-fluorine bridged chain structure, and MoF4NH.MeCN adopts a pseudo-octahedral (C4), monomeric stucture in the solid state. WOF4 reacts with Me3SiNCO to form WOF3NCO, identified from its mass spectrum. The hexafluorides MF6 (M= Mo,Re), when allowed to react with tetrakis-tri-methylsilylhydrazine (TTSH) undergo reduction to the pentafluoride in approximately 80% yield. Tungsten hexafluoride is believed to react with TTSH to form the diazene compound, WF4N-MWF4.
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Vargas, Gregory Wilda Ruhlandt-Senge Karin. "Nitrogen-based alkaline earth metal compounds syntheses, structures and applications /." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.
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Roberto, Dominique Marie. "Metal-catalyzed reactions of heterocyclic nitrogen compounds and related systems." Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5773.
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Huestis, Malcolm P. "Transition Metal-Catalyzed Preparation and Functionalization of Nitrogen-Containing Heterocycles." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28662.
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The formation of carbon-carbon bonds is the single most fundamentally important operation in synthetic organic chemistry. Arguably, the aldol and Diels-Alder reactions stand as the most significant advances in forging linkages between carbons of an sp3-hybridized nature.
Beginning in the early 1970s, seminal advances were made with respect to formation of carbon-carbon bonds between sp2 centers. These transformations, termed "cross-coupling" reactions, have undoubtedly changed the way synthetic organic chemistry is carried out, rendering the synthesis of carbon-carbon sp2 linkages a relatively trivial task. New synthetic technologies that utilize catalytic quantities of transition metals continue to be developed, and have paved the way to enable rapid increases in molecular complexity with far less effort than previously required.
The active ingredient in traditional cross-coupling reactions is a catalytic quantity of palladium. Provided that the two reactants to be cross-coupled have the appropriate functional groups for cross-coupling, they bind to the palladium and eliminate together, bound by a covalent Csp2 -Csp2 bond. These functional groups include halides, boronic acids and esters, and organometallic fragments.
Direct arylation is a recent advance in cross-coupling between aryl groups whereby one cross-coupling partner (usually the one bearing an organometallic fragment) is replaced by the simple arene (C-H bond).
In the first section, we describe our efforts in extending the direct arylation technique to azaindole compounds. Ultimately, this research led to two different palladium-based catalyst systems - one that performed the cross-coupling event on the azine ring of azaindole, and one that arylated the azole ring.
In the second section, we extend our work on a cross-coupling technique catalyzed by rhodium, wherein a five-membered azole ring is constructed oxidatively by reaction between an anilide and an alkyne. This reaction finds its precedent in the Larock indole synthesis, a reaction catalyzed by palladium that features the anilide possessing an ortho-iodo function.
In the final section, we demonstrate the direct coupling of two unactivated C-H bonds in an intramolecular sense. This methodology was particularly useful for synthesizing carbazoles, and the synthesis of several highly oxygenated, naturally-occurring carbazo1es is described.
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Dasgupta, Mohua. "Synthetic routes to phosphorus (III)- and nitrogen-containing dendritic polymers." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31216.
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The incorporation of phosphine or amine structural units into dendritic polymers offer significant potential in building macromolecular species with desired properties for heterogenizing homogeneous catalysis. To this end, synthetic methodologies based on the chemistry of acid-base hydrolysis of aminosilanes with molecules possessing hydroxyl end groups, and that of phosphorus halides/amides with alkynyl/alcohol monomers were explored as approaches to construct phosphorus(III)- and nitrogen-containing dendritic polymers. Attempted implementation of a three-step, divergent synthetic methodology led to the discovery of two new phosphorus(III)-based compounds, P[O(CH2) 2C≡CH]3 and P[O(CH2)2C≡CSn(CH 3)3]3. Efforts to execute a two-step, divergent synthetic route to nitrogen-containing dendrimers afforded first- and second-generation dendrimers, N4 and N10. Attempts to adapt this methodology to one-pot procedures for hyperbranched polyamines show promise. Finally, single-step and pseudo-single-step procedures for synthesizing hyperbranched polyphosphines were employed in the preparation of several phosphorus(III)-containing macromolecules. These materials were successfully functionalized with Rh(I) organometallic complexes.
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Chua, Zhijie. "Coordination chemistry of high oxidation nitrogen containing amides and heterocycles." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119473.
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The catalytic reduction of nitrous oxide (N2O) to dinitrogen (N2) by nitrous oxide reductase (N2OR) is poorly understood. The N2O molecule is a poor ligand with relatively sparse coordination chemistry. We proposed the synthesis of probable nitrous oxide precursors which can be coordinated to transition metals prior to conversion to nitrous oxide. Nitramide, H2NNO2, 2-1, and the related nitrogen amide acids N-nitroamide 2-2, 2-3; N-nitrocarbamate 2-4, 2-5, N-nitrosocarbamate 2-6, 2-7; N-nitrosulfonamide 2-8 have been synthesized as possible nitrous oxide precursors for coordination studies with transition metals. The silver salts of the conjugate base of the nitrogen acids N-nitroamide 2-2Ag; N-nitrocarbamate 2-4Ag, 2-5Ag; N-nitrosocarbamate 2-6Ag; N-nitrosulfonamide 2-8Ag are synthesized from the reaction of the acids with Ag2CO3. Similarly the potassium salts of the nitrogen acids N-nitroamide 2-2K; N-nitrocarbamate 2-4K; N-nitrosocarbamate 2-6K; N-nitrosulfonamide 2-8K are synthesized from the reaction of the nitrogen acids with K2CO3 or CH3OK. To investigate the pi-acidity of the nitrogen acids, a series of Ir(I) complexes of the nitrogen acids, trans-Ir(η1-X)(CO)(PPh3)2, (X = nitrogen acid) N-nitroamide 3-3; N-nitrocarbamate 3-4, 3-5; N-nitrosocarbamate 3-6; N-nitrosulfonamide 3-7 are synthesized from the reaction of Vaska's complex, trans-Ir(Cl)(CO)(PPh3)2 (3-1) with the silver salts of the conjugate base of the nitrogen acids (N-nitroamide 2-2Ag; N-nitrocarbamate 2-4Ag, 2-5Ag; N-nitrosocarbamate 2-6Ag; N-nitrosulfonamide 2-8Ag). Comparative studies with the related amides, dinitramide and bistriflimide, have also been done.The oxidative addition of the nitrogen acids (N-nitroamide 2-2, 2-3; N-nitrocarbamate 2-4, 2-5) to trans-Ir(Cl)(N2)(PPh3)2 (3-2) afford the Ir(III) complexes of the nitrogen acids, Ir(η2-X)(H)(Cl)(PPh3)2, (X = nitrogen acid) N-nitroamide 3-11, 3-12; N-nitrocarbamate 3-13, 3-14. The 31P, 1H NMR and IR spectroscopic reaction monitoring profiles of the oxidative addition reactions give evidence of reaction intermediates that eventually convert to the final product. The reaction of 3-11 with CO and P(CH3)2Ph result in the formation of multiple isomers of the addition products and also phosphine substitution. Addition of methyl triflate to 3-11 in CH3CN is found to result in the substitution and loss of the nitrogen acid. The Re(I) complexes of the nitrogen acids , trans-Re(η2-X)(CO)2(PPh3)2, (X = nitrogen acid) N-nitroamide 4-8; N-nitrocarbamate 4-9; N-nitrosulfonamide 4-12 are synthesized from the reaction of trans-[Re(CH3CN)2(CO)2(PPh3)2](Y), (Y = ClO4: 4-3, BF4: 4-7) with the potassium salts of the conjugate base of the nitrogen acids 2-2K, 2-4K and 2-8K respectively. The reaction of 4-7 with N-nitrosocarbamate 2-6K at room temperature gives mostly the kinetic isomer trans-Re(η2-X)(CO)2(PPh3)2 (4-10). The same reaction at reflux conditions gives mostly a thermodynamic isomer Re(η2-X)(CO)2(PPh3)2 (4-11A). Complex 4-9 and 4-10 are found to crystallize in an unusual space group R-3 that gives a large unit cell with huge solvent channels between the Re complexes and CH2Cl2 solvate molecules. The Dimroth/amidine rearrangement of benzotriazoles has been shown to exist in solution for 5-1 by variable temperature 19F NMR. The reaction of 3-2 with the benzotriazoles 5-1 and 5-2 gives the new Ir(I) complex, trans-Ir(Cl)(η1-5-1)(PPh3)2 (5-7) and Ir(III) complex, trans-Ir(Cl)(η3-5-2)(PPh3)2 (5-8) respectively. Complex 5-7 undergoes addition and substitution reactions readily to give multiple isomers while 5-8 is inert towards nucleophiles.<br>La réduction de l'oxyde nitreux (N2O) en diazote (N2) par le réductase de l'oxyde nitreux (N2OR) est très peu comprise. La molécule N2O n'est pas un très bon ligand et à une coordination chimique limité. Nous proposons la synthèse de précurseurs de l'oxyde nitreux qui peuvent se coordonner aux métaux de transitions avant leurs conversions en oxyde nitreux. Nitramide, H2NNO2, 2-1, et les acides d'azotes amidés N-nitroamide 2-2, 2-3; N-nitrocarbamate 2-4, 2-5, N-nitrosocarbamate 2-6, 2-7; N-nitrosulfonamide 2-8 ont étés synthétisés en tant que de possible précurseurs de l'oxyde nitreux pour des études de coordination avec des métaux de transitions. Les sels d'argents des bases conjugués des acides d'azotes N-nitroamide 2-2Ag; N-nitrocarbamate 2-4Ag, 2-5Ag; N-nitrosocarbamate 2-6Ag; N-nitrosulfonamide 2-8Ag ont étés synthétisés par les réactions des ces acides avec Ag2CO3. Similairement, les sels de potassium des bases conjugués des acides d'azotes N-nitroamide 2-2K; N-nitrocarbamate 2-4K; N-nitrosocarbamate 2-6K; N-nitrosulfonamide 2-8K ont étés synthétisés par les réactions des ces acides soit avec K2CO3 ou CH3OK. Pour examiner l'acidité du système pi de ces acides d'azotes, des séries the complexes d'acides d'azotes d'Ir(I) trans-Ir(η1-X)(CO)(PPh3)2, (X = acide d'azote) N-nitroamide 3-3; N-nitrocarbamate 3-4, 3-5; N-nitrosocarbamate 3-6; N-nitrosulfonamide 3-7 ont étés étés synthétisés par les réactions du complexe de Vaska, trans-Ir(Cl)(CO)(PPh3)2 (3-1), avec les sels d'argents des bases conjugués des acides d'azotes (N-nitroamide 2-2Ag; N-nitrocarbamate 2-4Ag, 2-5Ag; N-nitrosocarbamate 2-6Ag; N-nitrosulfonamide 2-8Ag). Des études comparatives avec des amides reliés, dinitramide et bistriflimide, ont aussi étés faites. Les complexes de Re(I) des acides d'azotes, trans-Re(η2-X)(CO)2(PPh3)2, (X = acide d'azote) N-nitroamide 4-8; N-nitrocarbamate 4-9; N-nitrosulfonamide 4-12 ont étés synthétisés par les réactions de trans-[Re(CH3CN)2(CO)2(PPh3)2](Y), (Y = ClO4: 4-3, BF4: 4-7) aves les sels de potassium des bases conjugués des acides d'azotes 2-2K, 2-4K et 2-8K respectivement. La réaction de 4-7 avec N-nitrosocarbamate 2-6K à température de la pièce procure principalement l'isomère cinétique trans-Re(η2-X)(CO)2(PPh3)2 (4-10). La même réaction en condition de reflux procure principalement l'isomère thermodynamique Re(η2-X)(CO)2(PPh3)2 (4-11A). Les complexes 4-9 et 4-10 cristallisent dans un groupe d'espace insolite, soit R-3, qui à une grande unité cellulaire avec de larges canaux de solvant entre les complexes de Re et les molécules de solvant de CH2Cl2.Le réarrangement Dimroth/amidine des benzotriazoles ont démontré leur existence en solution pour 5-1 via la RMN 19F en température variable. Les réactions de 3-2 avec les benzotriazoles 5-1 et 5-2 donnent de nouveaux complexes d'Ir(I), trans-Ir(Cl)(η1-5-1)(PPh3)2 (5-7) et d'Ir(III), trans-Ir(Cl)(η3-5-2)(PPh3)2 (5-8) respectivement. Le complexe 5-7 subit facilement des réactions de substitution et d'addition pour donner de multiples isomères tandis que le complexe 5-8 est inerte envers les nucléophiles.
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Elder, Susan Margaret. "The coordination chemistry of some polydentate nitrogen-donor ligands." Thesis, University of Cambridge, 1990. https://www.repository.cam.ac.uk/handle/1810/272957.
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Palmer, Catherine Ann. "The coordination chemistry of some nitrogen-sulphur donor ligands." Thesis, University of Cambridge, 1990. https://www.repository.cam.ac.uk/handle/1810/272977.
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Reay, David S. "Temperature dependence of inorganic nitrogen utilisation by bacteria and microalgae." Thesis, University of Essex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265190.
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Van, Wijk Kim. "The effect of organic carbon and nitrogen additions on inorganic nitrogen uptake by phytoplankton and bacteria." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/18342.
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Bibliography: pages 76-89.<br>This study examines the effects of enrichment with organic carbon and nitrogen on inorganic nitrogen partitioning between phyto- and bacterio- plankton. Strongly preferential uptake of ammonium over nitrate was observed by both the phytoplanktonic and bacterial fractions, with RPINH4 values typically between 1 and 5. The bacterial fraction ( <0.8μm) was found to be responsible for as much as 48-75% of community uptake of ammonium; while the netplanktonic fraction was observed to take up approximately 50% of intact community uptake of nitrate. The addition of amino acids appeared to mediate bacterial competition for ammonium, indicating their preference for DON as a nitrogen source and allowing increased ammonium uptake by the nanoplanktonic fraction. The effect of glucose enrichment was complicated by the presence of protozoans, which appeared to be indirectly responsible for decreased ammonium uptake due to depletion of this substrate in the presence of added glucose. The nanoplankton appeared to be responsible for the least nitrogen uptake with respect to biomass, indicating that they may have been subject to competition pressure from both the bacterial and netplanktonic fractions.
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Holland, Stephanie. "Synthesis, characterisation and transition metal complexes of nitrogen-containing ligands." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/8162.
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Stotereau, Peter James. "Complexation of transition metal ions with sulfur-nitrogen donor ligands." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292922.
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Togrou, Maria. "Iron, titanium and vanadium coordination chemistry related to nitrogen fixation." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364587.
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Diego, Derrick A. "Synthesis and characterization of iron dinitrosyl complexes with nitrogen containing chelating ligands." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527697.
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<p> Three new [Fe-N0]<sup>10</sup> complexes coordinated with nitrogen chelating ligands have been synthesized and characterized. The new synthesized complexes are dinitrosyl(2-2'-biquinoline )iron(O), dinitrosyl(2,2' -bipyridine 4,4' -dimethyl)iron(O), and dinitrosy 1(2,2'-bipyridine 4,4' -diphenyl)iron(O). Each complex is synthesized utilizing a common starting material, dinitrosyldicarbonyliron(O), (Fe(N0)<sub>2</sub>(C0)<sub>2</sub>). Reaction conditions are in an inert atmosphere at ambient temperature and pressure.</p><p> The characterizations of these molecules are done with ultraviolet visible spectroscopy, infrared spectroscopy, and single crystal X-ray diffraction. Ultraviolet visible spectroscopy display metal ligand charge transfers between 250-550 nm. Peaks below this are due to intraligand transitions from the chelating ligands. Infrared spectroscopy data reveal that NO stretching frequencies shift to lower wavenumbers when compared to Fe(N0)<sub>2</sub>(C0)<sub>2</sub> due to its better σ-donating abilities of the nitrogen chelating ligands. Single crystal X-ray diffraction data show that all complexes are pseudo tetrahedral in an attracto conformation.</p>
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Crossland, Justin L. 1982. "Iron coordination chemistry of nitrogen, diazene, hydrazin, and ammonia : Investigating the mechanism of nitrogen reduction to ammonia." Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10336.
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xvi, 233 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.<br>The coordination chemistry of iron with N 2 is becoming increasingly important as chemists try to find alternative routes to the production of ammonia. Current biological and industrial processes use iron to catalyze the formation of ammonia from N 2 ; however, huge amounts of energy are required for this conversion. Understanding how dinitrogen and other intermediates of dinitrogen reduction interact with iron could lead to energy efficient processes for the production of ammonia.
This dissertation explores the synthesis and reactivity of an iron dinitrogen complex that reacts with acid to produce ammonia at room temperature and pressure. This dissertation also explores the progress toward determining the mechanism of this reaction in hopes of improving the yields of ammonia.
Chapter I describes both the biological nitrogen fixation process and the industrial production of ammonia and provides an in-depth look at progress toward an alternative route to ammonia using iron complexes described in the literature thus far.
Chapter II details the synthesis, characterization, and reactivity of dihydrogen and dinitrogen complexes of iron. These complexes are precursors to the active ammonia producing complex and are among a handful of dihydrogen and dinitrogen complexes that have been structurally characterized. Chapter III explores the synthesis and stability of Fe(DMeOPrPE) 2 N 2 . This complex produces ammonia and hydrazine upon protonation with a strong acid. Optimizing the yield of ammonia from this protonation is also described.
Chapter IV discusses the synthesis and reactivity of several complexes of iron containing intermediates relevant to dinitrogen reduction, including diazene (N 2 H 2 ), hydrazine (N 2 H 4 ), and ammonia. By studying these intermediates, a mechanism of ammonia formation from the protonation of Fe(DMeOPrPE) 2 N 2 is proposed that may also provide insights into the mechanism of nitrogenase. Chapter V provides a summary of this research.
This dissertation includes previously published and unpublished co-authored material.<br>Committee in charge: Darren Johnson, Chairperson, Chemistry;
David Tyler, Advisor, Chemistry;
Michael Haley, Member, Chemistry;
Kenneth Doxsee, Member, Chemistry;
Scott Bridgham, Outside Member, Biology
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De, Souza Jaisa Soares. "Aspects of vanadium, iron and titanium chemistry related to nitrogen fixation." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283147.
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This project concerned the basic chemistry of VD, Vm and FeD (iJ because of interest in the role of vanadium and iron in the electron-transfer processes catalysed by the nitrogenases, and (iiJ to try to rationalise the fragmented data available on the chemistry of low-oxidation-state vanadium and its reactions with iron(II) compounds. In order to increase the range of FeD materials available for reaction with VD, the dinuclear complex [{FeCI(tmeda)h{Jt-Cl)2] and the mononuclear [FeCI2(tmeda)2] (tmeda = N,N,N',N'-tetramethylethylenediamine) were synthesised and characterised by chemical and physical methods including X-ray diffraction. The reaction between vanadium(II) or iron(II) compounds, such as [MCI2(tmeda)z], and chloride-abstracting agents (e.g. M~SiI or NaBPh4) afforded trinuclear ionic complexes containing [M3Cl3Y2(LL)3]+ , where M = FeDor VD, Y = chloride and LL = bidentate amine or phosphine; complexes containing Y = methoxide and M = yD were isolated from methanol solutions. The planar {M3CI3} core is highly stable and remains intact during substitution of the axial Y groups and the neutral ligands. Mixed clusters containing both vanadium(II) and iron(II) can also apparently be synthesised, but the similarity of the metal radii in oxidation state II makes characterisation by X-ray diffraction analysis difficult. Attempts to produce yD_ or ym -bridging N2 compounds containing the ligand 2- [(N,N-dimethylamino)methyl]ferrocenyl (L) were not successful. In order to obtain additional information on the reactivity of L towards early transition metals, the cyclopentadienyltitanium (IV) complexes [Cp2Ti(L)CI] and [CpTiLxCl3.J (x = 1-3) were prepared. X-ray diffraction analyses of [Cp2Ti(L)CI] and [CpTi(L)CIJ have shown that L can be monodentate or bidentate, depending on steric constraints about the metal atom. The complex [CpTi(L)(L')] has also been synthesised; L' is a tridentate ligand apparently generated upon heating by intramolecular C-H activation of a methyl substituent on one of the tertiary amino groups of [CpTi(L)3], followed by elimination of neutral [(N,N-dimethylamino)methyl] ferrocene. The complexity of this system and the formation oftrinuclear vanadium(II) complexes possibly account for some of our difficulties in understanding vanadium-dinitrogen chemistry.
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Melkamu, Teshome. "Intercropping in corn : soil physical quality and soil inorganic nitrogen levels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ44098.pdf.
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Young, Neil Graham Miller. "Inorganic nitrogen leaching and agronomic response of St Augustinegrass to nitrogen fertilization strategies under residential lawn conditions." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041328.
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Öhlund, Jonas. "Organic and inorganic nitrogen sources for conifer seedlings : abundance, uptake and growth /." Umeå : Dept. of Forest Genetics and Plant Physiology, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s312-ab.html.
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Holt, David Gary Lawton. "The preparation, reactivity and structures of low oxidation state vanadium complexes in relation to nitrogen fixation." Thesis, University of Surrey, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236926.
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Spencer, Robert G. M. "Biogeochemistry of dissolved organic matter and inorganic nitrogen in two N.E. UK estuaries." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423588.
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Silbiger, Nyssa Joy Lindquist Niels Lyle. "Impacts of sponge produced dissolved inorganic nitrogen on Caribbean coral reef seaweed communities." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2624.
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Thesis (M.S.)--University of North Carolina at Chapel Hill, 2009.<br>Title from electronic title page (viewed Oct. 5, 2009). "... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Marine Sciences." Discipline: Marine Sciences; Department/School: Marine Sciences.
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Edwards, V. R. "The yield of marine phytoplanckton chlorophyll from dissolved inorganic nitrogen under eutrophic conditions." Thesis, Edinburgh Napier University, 2001. http://researchrepository.napier.ac.uk/Output/1052660.
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During 1999 ex-situ microcosm experiments were carried out at Dunstaffnage Marine Laboratory, Oban using natural assemblages of microplankton (< 200 m in size) in a series of enrichment experiments using continuous culture techniques to determine q - the yield of chlorophyll from dissolved available inorganic nitrogen (DAH\I), during and after an enrichment event. The experiments lasted between 11 and 14 days and produced a time series of q after an enrichment of either 12 M ammonium or 12 M nitrate. Allother essential nutrients, vitamins and trace metals were added in excess so that only DAIN would limit chlorophyll synthesis. Experiments were carried out during Spring, Summer and Autumn and environmental regimes in the growth room were set-up tomimic ambient conditions at the sampling site for each season. Water samples were collected every 2 days and were analysed for chlorophylls a, b and c, chlorophyll a breakdown products, carotenoids, dissolved inorganic nutrients and particulate nitrogenand carbon. Identification and enumeration of microplankton was also undertaken. During 2 of the experiments nitrogen isotope techniques were used to determine uptake rates for nitrate and ammonium. The results indicated that the microplanktonic response to an enrichment event could be divided into 3 phases: Phase I q - a rapid uptake of DAINand the synthesis of large quantities of pigments; Phase H q - DAIN became limiting and there was a decline in q caused by nutrient limitation and an increase in grazing pressure; Phase II q - after declining q remained fairly stable. Nitrogen tied-up in autotrophicbiomass was transferred to the heterotrophs as grazing pressure and algal death increased accompanied by a calculated rise in dissolved organic nitrogen through degradation processes (assuming mass conservation of nitrogen was occurring in the microcosms),and, presumably, regenerated DAIN. There were seasonal differences in q caused by changing environmental conditions such as light, temperature and background nutrient concentrations. Seasonal changes in the community structure of microplankton collected from the sampling site could also have affected the value of q. During the Summer and Autumn Experiments ammonium enriched microcosms produced lower values of q compared to nitrate enriched microcosms but further investigation is needed to clarify the reasons for this. The method used to estimate chlorophyll or nitrogen had an effect on the value of q. Refined values of q have been produced for use in the screening model used to predict potential eutrophication in the UK.
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Wilson, J. M. "Natural abundance of '1'5N in soils : temporal and spatial variation in organic and inorganic N pools." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265428.
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Viktor, Aleysia. "Physiological and metabolic factors determining nitrogen use efficiency of tomato seedlings grown with elevated dissolved inorganic carbon and different nitrogen sources." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52999.
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Thesis (MSc)--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: The aim of this study was to determine (l) the influence of elevated dissolved inorganic carbon
(DIC) on the nitrogen use efficiencies (NUE) of tomato seedlings grown with different nitrogen
sources, (2) how changes in the regulation and activities of nitrate reductase (NR),
phosphoenolpyruvate carboxylase (PEPc), carbonic anhydrase (CA) and subsequent changes in
metabolites would account for observed changes in NUE, and (3) to what extent elevated DIC
contributed to the carbon budget of plants grown with different nitrogen sources. Lycopersicon
esculentum cv. Fl44 seedlings were grown in hydroponic culture (pH 5.8) with 2 mM of either
N03- or NH4 + and the solutions were aerated with either 0 ppm or 5000 ppm CO2 concentrations.
The similar NUEs of NH/-fed plants grown with either root-zone CO2 concentration were
largely due to their similar RGRs and N uptake rates. Elevated root-zone DIC had an initial
stimulatory effect on N~ + uptake rates, but it seems as if this effect of DIC physiological
processes was cancelled out by the toxic effect of unassimilated NH/. The NUE for N03--fed
plants supplied with 5000 ppm root-zone CO2 was higher relative to 0 ppm root-zone CO2 and it
was possibly due to the higher relative growth rates for similar N uptake rates of 5000 ppm
compared to 0 ppm root-zone CO2. Nitrate-fed plants grown with 5000 ppm compared to 0 ppm
root-zone CO2 had higher in vivo NR and in vitro NR and PEPc activities. These increases in
enzymes activities possibly lead to increases in organic acid synthesis, which could have been
used for biomass accumulation. This would account for the increased relative growth rates of
N03--fed plants grown with 5000 ppm compared to 0 ppm root-zone CO2. The increasing rootzone
CO2 concentrations resulted in the Ó15N values of NH/-plants becoming more positive
indicating an absence of enzymatic discrimination. This may have been due to the inhibitory
effect of DIC on Nll,+ uptake, causing plants to utilise both internal isotopes equally. The Ól3C
studies showed that PEPc contributed equally to both N03-- and NH/-fed plants over the long
term. From this it can be concluded that the lower NUE of NH/-compared to N03--fed plants
grown with 5000 ppm root-zone C02 was due to increased N uptake and exudation of organic compounds into the nutrient solution. Experiments with 813C also showed that at increasing rootzone
CO2 concentrations, PEPc made a bigger contribution to the carbon budget via the
anaplerotic reaction.<br>AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om (1) die invloed van verhoogde opgeloste anorganiese
koolstof dioksied (DIC) op die stikstofverbruiksdoeltreffenheid (NUE) van plante wat op
verkillende stikstofbronne gekweek is, te bepaal. (2) Veranderinge in die regulering van nitraat
reduktase (NR), fosfo-enolpirovaatkarboksilase (PEPc) en karboonsuuranhidrase (CA) is
bestudeer en gekorreleer met waargeneemde verskille in NUE. (3) 'n Beraming van die mate
waartoe verhoogde DIC bydra tot die koolstofbegroting van plante, gekweek op verskillende
stikstofbronne, word bespreek. Lycopersicon esculentum cv. F144 saailinge is in waterkultuur
(pH 5.8) met 2 mM N03- of NH/ gekweek en die oplossings is alternatiewelik met 0 ppm of
5000 ppm CO2 belug. Die NUEs van plante gekweek met NH/ en belug met albei C02
konsentrasies was vergelykbaar grootliks as gevolg van hulooreenkomstige relatiewe
groeitempo's en Nopname. DIC het aanvanklik NH/ opname gestimuleer, maar enige latere
stimulerende effek van DIC op fisiologiese prosesse was klaarblyklik uitgekanselleer deur N~ +
toksiteit veroorsaak deur vertraagde assimilasie. Die NUE van plante gekweek met N03- en 5000
ppm CO2 was hoër as dié van plante gekweek met N03- en 0 ppm CO2. Dit is moontlik gekoppel
aan hoër relatiewe groeitempo's teenoor onveranderde N opname tempo's. Plante gekweek met
N03- en 5000 ppm CO2 het hoër in vivo NR en in vitro NR en PEPc aktiwiteite getoon as plante
gekweek met N03- en 0 ppm CO2. Bogenoemde toenames in ensiem aktiwiteite word verbind
met biomassa toename deur verhoogde organiese suur sintese. Dit bied 'n moontlike verklaring
vir die hoër relatiewe groeitempo's van plante gekweek met N03- en 5000 ppm CO2 teenoor
plante gegroei met N03- en 0 ppm CO2. Die 015N waardes van plante gekweek met NH/ en
5000 ppm CO2 was meer positief as dié van plante gekweek met Nl-l,+ en 0 ppm CO2 wat gedui
het op die afwesigheid van ensiematiese diskriminasie. Dit kon as gevolg gewees het van die
vertragende effek van DIC op Nl-la + opname wat daartoe sou lei dat die plante beide isotope
eweveel inkorporeer. Eksperimente met ol3C het getoon dat PEPc oor 'n lang tydperk eweveel
begedra het tot die koolstofbegroting van plante gekweek met beide N03- and N~+. Hiervan kan afgelei word dat die laer NUE van plante gekweek met NH4 + en 5000 ppm C02 in vergelyking
met dié van plante gekweek met N03- en 5000 ppm CO2 die gevolg was van verhoogde NH/
opname en uitskeiding van aminosure in die voedingsoplossing. Eksperimente met 0"c het ook
getoon dat verhoogde DIe konsentrasies die bydrae van PEPc tot die plant se koolstofbegroting
laat toeneem.
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Deininger, Anne. "Effects of inorganic nitrogen and organic carbon on pelagic food webs in boreal lakes." Doctoral thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-130340.
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Anthropogenic activities are increasing inorganic nitrogen (N) loadings to lakes in the northern hemisphere. In many boreal lakes phytoplankton are N limited, wherefore enhanced N input may affect the productivity of pelagic food webs. Simultaneously, global change causes increased inflows of terrestrial dissolved organic carbon (DOC) to boreal lakes. Between clear and humic lakes, whole lake primary and consumer production naturally differs. However, research is inconclusive as to what controls pelagic production in these lakes. Further, it is unclear how DOC affects the response of the pelagic food web to enhanced inorganic N availability. The overarching goal of this thesis was to study the effects of inorganic N and organic C for pelagic food webs in boreal lakes. In the thesis, I first identified the main drivers of pelagic production during summer in eight non-manipulated Swedish boreal lakes with naturally low or high DOC. Then I investigated how increased N availability affects the pelagic food chain, and how the response differs with DOC. Therefore, whole lake inorganic N fertilization experiments were conducted in six Swedish boreal lakes across a DOC gradient (low, medium, high) divided into three lake pairs (control, N enriched) with one reference and two impact years. In each lake, I also investigated the response of zooplankton growth using in situ mesocosm experiments excluding planktivores. I found that humic boreal lakes had lower phytoplankton production and biomass than clear water lakes. Further, phytoplankton community composition and food quality differed with DOC. However, high DOC did not reduce pelagic energy mobilization or zooplankton biomass, but promoted a higher dominance of cladoceran relative to copepod species. N addition clearly enhanced phytoplankton biomass and production in the experimental lakes. However, this stimulating N effect decreased with DOC as caused by light limitation. Further, the newly available phytoplankton energy derived from N addition was not efficiently transferred to zooplankton, which indicates a mismatch between producer energy supply and consumer energy use. Indeed, the mesocosm experiment revealed that decreased food quality of phytoplankton in response to N addition resulted in reduced food web performance, especially in clearer lakes. In humic lakes, zooplankton production and food web efficiency were clearly more resilient to N addition. In summary, my thesis suggests that any change in the landscape that enhances inorganic N availability will especially affect pelagic food webs in clear water lakes. In contrast, brownification will result in more lakes being resilient to eutrophication caused by enhanced N deposition.
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Cai, Yanbing. "Synthesis and Characterization of Nitrogen-rich Calcium α-Sialon Ceramics". Doctoral thesis, Stockholms universitet, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8568.
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In this thesis, a synthesis concept has been developed, which uses nitrogen-rich liquid phases for sintering of Ca-α-sialon ceramics. First, keeping the Si/Al ratios constant, the effects of N/O ratio on the properties and microstructure were investigated through a liquid phase sintering process. Second, nitrogen-rich Ca-α-sialon ceramics, with nominal compositions: CaxSi12-2xAl2xN16, x < 2.0, was synthesized and characterized. Third, mechanical and thermal properties of nitrogen-rich Ca-α-sialons were investigated in terms of high temperature deformation resistance,reaction mechanism, phase stability and oxidation resistance, and further correlated to their phase assemblage and microstructure observation. It has been found that increasing the N/O and Ca/Al ratio simultaneously in the materials could result in development of a microstructure with well shaped, high-aspect-ratio Ca-α-sialon grains, and an improvement in both toughness and hardness. For the nitrogen-rich Ca-α-sialon, mono-phasic α-sialon ceramics were obtained for 0.51 ≤ x ≤ 1.32. The obtained Ca-α-sialon ceramics with elongated-grain microstructures show a combination of high hardness and high fracture toughness. Compared with the oxygen-rich Ca-α-sialons, the nitrogen-rich Ca-α-sialons exhibited approximately 150 oC higher deformation onset temperatures and decent properties even after the deformation. The α-sialon phase was first observed at 1400 oC, however the phase pure Ca-α-sialon ceramics couldn’t be obtained until 1800 oC. The nitrogen-rich Ca-α-sialons were thermal stable, no phase transformation observed in the temperatures range1400-1600 oC. In general, mixed α/β-sialon showed better oxidation resistance than pure α-sialon in the low temperature range (1250-1325 oC), while α-sialons with compositions located at α/β-sialon border-line showed significant weight gains over the entire temperature range (1250-1400 oC).
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Gokmen, Mustafa. "Dissolved Inorganic Nitrogen Removal Efficiency Of The Reed Beds Surrounding Lake Mogan Using Modeling Approaches." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604800/index.pdf.
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In this study, yearly and seasonally nitrogen retention dynamics of reed beds surrounding Lake Mogan were investigated by comparing surface aerial nitrogen load and in-lake concentrations. The analyses were performed separately for nitrate-N, ammonium-N and dissolved inorganic nitrogen (sum of nitrate-N and ammonium-N) to reveal differences between them in terms of retention dynamics. 1998, 1999 and 2002 were relatively high-load years in terms of DIN-input to reed beds surrounding Lake Mogan, compared with the DIN-loadings of 1997, 2000 and 2001. A significant difference was observed between NO3-N input and output for the relatively high-load years to Lake Mogan reed beds indicating significantly high NO3-N retention rates for that periods, while no significant difference was observed in the relatively low-load years. Also, a clear linear relationship (R2 = 0.975) was found between amount of NO3-N retention and amount of NO3-N input to the system. NH4-N input and output were not significantly different in none of the study years.
Then, a dynamic Wetland Nitrogen Model was utilized to model dissolved inorganic nitrogen removal capacity of the reed beds surrounding Lake Mogan. The model was firstly calibrated and validated using data sets of different study years and then used for prediction under wet and dry year scenarios. The model predictions revealed that NO3-N retention efficiency was distinctively higher in wet rather than the dry year conditions since the reed beds might have limited denitrification capacity in dry years due to unavailability of enough NO3-N load.
Finally, the land-use changes occurred in the closer catchment of Lake Mogan and the potential risk areas for non-point nitrogen input to Lake Mogan were determined using aerial photos of the region and Geographical Information Systems (GIS). It was observed that highest potential risk area for non-point nitrogen input around the lake was north-east of the lake whereas, north end of the lake was least potential risk area.
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Song, Weining. "Some aspects of the utilization of inorganic nitrogen compounds and carbon compounds by "Nitrobacter hamburgensis" /." Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09A/09as724.pdf.
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English, Jason B. "Electronic structure investigations of multiple bonding between atoms: From metal-nitrogen triple bonds to metal-metal triple and quadruple bonds." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280021.
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The nature of multiple bonding involving transition metal atoms has been explored via photoelectron spectroscopic and computational studies of molecules containing metal-metal quadruple and triple bonds as well as of molecules containing formal metal-nitrogen triple bonds. The principles governing the nature of the multiple bonding in these systems are similar whether the multiple bonding occurs between two transition metals or between a transition metal and a nitrogen atom. First, the electronic structures of the R₃M≡N molecules, where R = ᵗBuO (Cr, Mo, W); iPrO (Mo); (CH₃)₂CF₃CO (Mo); and Cl (Mo), are examined by photoelectron spectroscopy in conjunction with density functional calculations. To assign the features seen in the photoelectron spectra, close attention is paid to the effects of (1) metal substitution and (2) alkoxide (or Cl) substitution. Examination of the photoelectron spectra of the full series of alkoxide-substituted molecules allows the relative positions of the ionizations from the M≡N σ and π orbitals to be identified. Of great importance to the electronic structure of these molecules are the alkoxide orbital combinations that mix strongly with the M≡N σ and π orbitals. The importance of the ancillary ligand combinations is clearly demonstrated by the photoelectron spectroscopic and computational studies of Cl₃Mo≡N. The replacement of the alkoxide ligand with chlorides greatly simplifies the resultant photoelectron spectrum, allowing all of the valence ionizations to be assigned. Next, the bonding in the M₂X₄(PMe₃)₄ molecules, where M = Mo (X = Cl, Br); W (X = Cl); and Re (X = Cl, Br, I), is explored by photoelectron spectroscopic investigations in conjunction with electronic structure calculations. From these investigations, the ionizations from the metal-based orbitals as well as several ligand-based orbitals have been assigned. The first ionization energies of both the molybdenum (δ) and rhenium (δ*) molecules decrease as the electronegativity of the halide increases. The origin of this inverse halide effect is explored. Finally, the nature of the quadruple metal-metal bond in the M₂(chp)₄ molecules (M = Cr, Mo, W; chp = 2-chloro-6-oxo-pyridinate) is probed. For all three metal systems, an ionization from the M₂ δ orbital can be seen. This is only the second time a distinct ionization feature has been noted for ionization of the delta orbital from a dichromium molecule. Comparisons with the previously studied M₂(mhp)₄ molecules (mhp = 6-methyl-2-oxo-pyridinate) allow for a better understanding of the electronic structure of these molecules.
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Kelley, Matthew Ryan. "Guanidinato and amidinato complexes of iridium(I): synthesis O2 and S8 reactivity, and (alkene)peroxo- and (alkene)persulfidoiridium(III) intermediates." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/2913.
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A variety of mononuclear alkene complexes, [Ir{ArNC(NR2)NAr}(cod)], and dicarbonyl complexes, [Ir{ArNC(NR2)NAr}(CO)2] (where R = Me or Et; Ar = Ph, 4-MeC6H4, 4-MeOC6H4, 2,6-Me2C6H3 or 2,6-iPr2C6H3; and cod = 1,5-cyclooctadiene), were synthesized from the neutral N,N-dialkyl-N',N"-diarylguanidines via deprotonation and transmetalation. These complexes were fully characterized by spectroscopic techniques and single-crystal X-ray diffraction. The single-crystal structure determinations show the guanidinato(1—) ligands coordinate the low valent d8 iridium(I) center in an N,N'-chelating binding mode, and the C—N bond lengths indicate a high degree of π-electron delocalization over the CN3 core. The 13C NMR chemical shifts of the alkene carbon atoms in the IrI(cod) complexes and the average CO stretching frequencies for the IrI(CO)2 complexes suggest that the guanidinato ligands function as stronger donors than related monoanionic, bidentate nitrogen-donor ligands. Intermediates in the reactions of the [Ir{ArNC(NR2)NAr}(cod)] complexes with O2 were identified and characterized as (alkene)peroxoiridium(III) species, [Ir{ArNC(NR2)NAr}(cod)(O2)], using multi-dimensional NMR and IR spectroscopy. The (alkene)persulfidoiridium(III) intermediate [Ir{PhNC(NMe2)NPh}(cod)(S2)] was identified and characterized in the reaction of [Ir{PhNC(NMe2)NPh}(cod)] with S8. It was determined that these intermediates are able to transfer oxygen or sulfur to simple organic molecules such as PPh3. The self-decay of the (alkene)peroxoiridium(III) intermediates leads to C—O bond formation and alkene oxidation, and upon addition of excess cod release of 4-cycloocten-1-one was observed. In addition, a mononuclear alkene complex, [Ir{PhNC(Me)NPh}(cod)], and a dinuclear tetracarbonyl complex, [{Ir(CO)2}2{π-PhNC(Me)NPh-κN:κN'}2], with an amidinato ligand, were synthesized and characterized. In the reaction of the IrI(cod) complex with O2, the corresponding (alkene)peroxoiridium(III) intermediate [Ir{PhNC(Me)NPh}(cod)(O2)] was observed. The reactivity of this intermediate and its decay products is similar to that of [Ir{ArNC(NR2)NAr}(cod)(O2)], with the formation of 4-cycloocten-1-one being observed upon addition of cod. Mononuclear (alkene)rhodium(I) complexes, [Rh{PhNC(NMe2)NPh}(cod)] and [Rh{PhNC(Me)NPh}(cod)], and a dinuclear complex, [{Rh(nbd)}2{π-PhNC(NMe2)NPh-κN:κN'}2], were synthesized and characterized (where nbd = norbornadiene or bicyclo[2.2.1]hepta-2,5-diene). Investigation of the reactivity of these complexes with O2 show they react very slowly or not at all.
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Blad, Sofia. "Torkat bioavfall som jordförbättringsmedel." Thesis, Uppsala University, Department of Earth Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88831.
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<p>The main project Dry preservation of source-separated organic household wastes involves a new technique for treatment of biowaste through drying. Investigations are going on to determine how the dried biowaste best can be used to close the natural circular flow of nutrients. The objective of this degree project is to determine if the dried biowaste can be used as a soil conditioner. By restoring the nutrients in the material to the ground, the natural circular flow is closed. A declaration of contents, including the nutrient levels, C/N ratio, pH and the electrical conductivity of the dried biowaste, was constructed and a germination test was done to make sure that the material did not inhibit sprouting. Further on a method was developed to study the decomposition process, and in particular the nitrogen mineralization of the dried biowaste. This method was then used practically.</p><p>The results of this degree project indicate that the decomposition capacity of the dried biowaste is very good. The germination test showed that the material in a diluted form (up to 50 % dried biowaste) did not inhibit sprouting. The examination of the nitrogen mineralization showed a fast liberalisation of nutrients available to plants, with only a shorter period of nitrogen immobilization. Together these results imply that the dried material could function well as a soil conditioner.</p><br><p>Projektet Torrkonservering av matavfall från hushåll innefattar en helt ny teknik för behandling av bioavfall genom torkning. Undersökningar pågår angående hur det torkade bioavfallet bäst kan användas för att sluta det naturliga kretsloppet. Examensarbetets huvudsyfte var, som ett led i dessa undersökningar, att utreda om det torkade bioavfallet kan användas som ett jordförbättringsmedel. Genom att tillföra bioavfallet till jord så återförs näringen i materialet till marken och kretsloppet sluts. En varudeklaration, med materialets näringshalter, C/N-kvot, pH och elektrisk konduktivitet, togs fram och ett groningstest utfördes för att kontrollera att bioavfallet inte var groningshämmande. Vidare utvecklades en metod för att studera det torkade bioavfallets nedbrytningsegenskaper i form av dess kvävemineralisering. Denna metod användes därefter praktiskt.</p><p>Resultatet av detta examensarbete tyder på att torkat bioavfall har mycket goda nedbrytningsegenskaper. Groningsförsöket visade att materialet i utspädd form (upp till 50 % torkat bioavfall) inte är groningshämmande, och mineraliseringsförsöket visade på en snabb frigörelse av växttillgängligt kväve, och en immobiliseringsperiod på ett par veckor. Tillsammans indikerar dessa resultat att det torkade materialet kan fungera väl som ett jordförbättringsmedel.</p>
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Calderón, Silvia Margarita. "Estimation of the particle and gas scavenging contributions to wet deposition of organic and inorganic nitrogen." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001538.
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Calderón, Silvia Margarita. "Estimation of the particle and gas scavenging contributions to wet deposition of organic and inorganic nitrogen." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/2469.
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Atmospheric deposition of nitrogen species represents an additional nutrient source to natural environments, and can alter the nitrogen cycle by increasing nutrient levels beyond the requirements of organisms. In Tampa Bay, atmospheric deposition of dissolved inorganic nitrogen species (DIN) has been found to be the second largest nitrogen source, but little is known about dissolved organic nitrogen species (DON). The research goal was to improve the dry and wet deposition estimates by inclusion of the DON contribution. In the atmospheric chemistry field a standard method to measure DON in atmospheric samples has not been agreed upon. This research proposes the use of the ultraviolet (UV)-photolysis method and presents the optimal settings for its application on atmospheric samples. Using a factorial design scheme, experiments on surrogate nitrogen compounds, typically found in the atmosphere, indicated that DON can be xviii measured with no biases if optimal settings are fixed to be solution pH 2 with a 24-hr irradiance period. DIN species (NH4 +, NO2 -, NO3 -) and DON concentrations were determined in fine (PM2.5) and coarse particles (PM10-2.5) as well as in rainwater samples collected at Tampa Bay. The estimates of wet deposition fluxes for NH4 +, NO3 - and DON were 1.40, 3.18 and 0.34 kg-N ha-1yr-1, respectively. Hourly-measured gas concentrations and 24-hr integrated PM10 concentrations were used in conjunction with a below-cloud scavenging model to explain DIN and DON concentration in rainwater samples. Scavenging of aerosol-phase DON contributed only 0.9 ± 0.2% to rainwater DON concentrations, and therefore gas scavenging should be responsible for 99%. These results confirmed the existence of negative biases in the dry and wet deposition fluxes over Tampa Bay. There is increasing interest in simulating wet deposition fluxes, and the proposed below-cloud scavenging model offers a new computational approach to the problem. It integrates the typical gas and particle collection functions and the concept of the deposition-weighted average concentrations. The model uses mass balance to describe the time-dependent cumulative contribution of all droplets in the rain spectrum to the rainwater concentration, giving predictions closer to experimental values and better estimations than those reported in the literature for similar cases.
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Magalhães, Catarina Maria Pinto Mora Pinto de. "Inorganic nitrogen dynamics in intertidal rocky biofilms and sediments of the Douro estuary : Processes and communities." Doctoral thesis, Universidade do Porto. Reitoria, 2005. http://hdl.handle.net/10216/10594.
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Herman, Melissa. "Inorganic fertilizer vs. cattle manure as nitrogen sources for maize (Zea mays L.) in Kakamega, Kenya." Connect to resource, 2009. http://hdl.handle.net/1811/37260.
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Magalhães, Catarina Maria Pinto Mora Pinto de. "Inorganic nitrogen dynamics in intertidal rocky biofilms and sediments of the Douro estuary : Processes and communities." Tese, Universidade do Porto. Reitoria, 2005. http://hdl.handle.net/10216/10594.
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Dupuis, Eartha M. "Poultry manure and inorganic fertiliser effects on soil fertility and microbial communities in wheat and corn agroecosystems." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97946.
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Many producers in North America are finding it profitable to make the transition from conventional farming to organic agriculture. Organic fertilisers may affect crop production and soil quality differently than inorganic fertilisers. The objectives of this study conducted in Ste.-Anne-de-Bellevue. Quebec were to examine crop yield, grain quality, soil fertility and microbial community parameters in wheat and corn agroecosystems receiving poultry manure or inorganic fertiliser. Wheat grain yield declined and corn grain yield did not increase with higher N rates, suggesting that increased N supply did not encourage grain production. Soil analyses demonstrated high inherent soil fertility at the study site, and fertilisation led to an environmentally undesirable increase in residual soil NO3 concentrations. Microbial biomass and respiration in corn agroecosystems were greater with poultry manure amendments than inorganic fertiliser, but not in wheat agroecosystems due to significant variation among field replicates. Phospholipid fatty acid analysis revealed significant differences between wheat and corn soil microbial community composition, but differences due to fertilisation were less evident. Further work is needed to uncover the relationships among N fertilisation, crop nutrition and soil microbiology in organic agroecosystems.
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Downward, Alan Murray. "Photo-activated Cytotoxins." Thesis, University of Canterbury. Chemistry, 2010. http://hdl.handle.net/10092/4179.
Full textAbstract:
The thesis addresses the potential application of ruthenium(II)-cobalt(III) heterodinuclear complexes as a new selective cancer treatment. The selectivity is to be achieved through the use of visible light to trigger activation of the drug.
The majority of work conducted relates to the design and synthesis of the bridging ligand for the final ruthenium(II)-cobalt(III) heterodinuclear complex. In Chapter 2, a potential bridging ligand based on a functionalised terpyridine is described. The intention was to bind the ruthenium(II) metal centre to the terpyridine end of the bridging ligand and have a secondary binding domain available for coordination of the cobalt(III) metal centre. However, a reductive step in the synthetic pathway failed to produce the desired product and this potential bridging ligand had to be abandoned.
In Chapter 3, two series of bridging ligands are described. The first of these series is based on Jurgen Sauer’s ‘LEGO’ system. In addition to describing the free synthesis of these ligands, their synthesis on a ruthenium(II) metal centre is described. The second series is based on disubstituted-1,2,4,5-tetrazines. These compounds are only able to be directly synthesised as the non-coordinated ligand. Coordination of these ligands to a single ruthenium(II) metal centre is then described. Ruthenium(II) complexes of both ligand series are then exposed to several transition metals and their ability to coordinate a second metal centre investigated.
The formation of ruthenium(II)-cobalt(III) heterodinuclear complexes, using the ligand series detailed in Chapter 3, is described in Chapter 4. These complexes are formed by reacting the ruthenium(II) complex of the bridging ligand with either [Co(en)₂(OTf)₂](OTf) or [Co(tren)(OTf)₂](OTf). These heterodinuclear complexes exhibit photo-activated ligand release, which makes them candidates for development as a potential cancer treatment.
The non-bridging ligands coordinated to the cobalt(III) metal centre in Chapter 4 were not cytotoxic. In order to make the system biologically active these ligands need to be changed. Chapter 5 describes how nitrogen mustards (a class of cytotoxic DNA alkylators) could be introduced as the non-bridging ligands. This involves the synthetic strategy of forming the cobalt(III) complex of the alcohol precursor of a nitrogen mustard. This precursor complex is then converted into the nitrogen mustard complex and coordinated to the ruthenium(II) bound bridging ligand.
The synthetic strategies outlined in this thesis can be applied to a wide range of potential bridging ligands and could potentially lead to a large number of ruthenium(II)-cobalt(III) heterodinuclear complexes being synthesised.
One journal article based on this research has been accepted for publication, in the Australian Journal of Chemistry. Three more articles are in preparation.
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Kalifa, Ali Mukael. "Effects of inorganic nitrogen and polyamines on growth and development of potato (solanium tubersum L.) in vitro." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410334.
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Mabasa, Stanford. "Nitrogen and the control of Striga asiatica on maize : timing and dose of organic and inorganic forms." Thesis, University of Sheffield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289599.
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Neikirk, Betty Berry. "Exchanges of Dissolved Inorganic Nitrogen and Dissolved Organic Carbon between Salt Marsh Sediments and Overlying Tidal Water." W&M ScholarWorks, 1996. https://scholarworks.wm.edu/etd/1539617714.
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Fulvio, Pasquale Fernando. "Synthesis and Characterization of Ordered Mesoporous Inorganic Nanocomposite Materials." Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1258990927.
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