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Wood, Paul Thomas. "Phosphorus-sulphur and phosphorus-selenium heterocycles". Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47312.
Testo completo
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Hill, Micheal W. "Improving Phosphorus Use Efficiency Through Organically Bonded Phosphorus". BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3469.
Testo completoAbstract (sommario):
Current maximum efficiency of phosphorus (P) fertilizers that is utilized by plants in the same year of application ranges from near zero to thirty percent. Despite low utilization of P in crop production, yields are often limited by P deficiencies. Innovative technology is requisite to achieve greater efficiency as fertilizer demands are increasing, while phosphorus mineral resources are rapidly being depleted. A growing environmental concern for nutrient pollution of surface waters also carries significant weight. A novel new product, Carbond® P, is promising technology to increase P use efficiency. Research is needed to understand its capabilities and the functioning mechanisms imbedded within its technology. Several research studies were conducted to evaluate Carbond® P (CBP) against traditional fertilizers ammonium polyphosphate (APP) and monoammonium phosphate (MAP). A soil column leaching study was conducted to determine P mobility through three soils, at two rates (20 and 30 kg P ha-1) in either a banded or mixed soil application. Mobility of P was evaluated at 24, 48, 110 and 365 d after fertilization. CBP showed significantly greater total P leachate values across all soil types and application rates averaged across all readings taken until 365 daf for both application types. In the banded applications, CBP generally produced significantly greater solubility than MAP or APP up until 110 daf. For applications mixed with soil, CBP and MAP had greater solubility than APP at 24 days after application, but by the later evaluation dates (48 and 110 daf) the CBP was significantly higher than both MAP and APP. No statistical significance was found in the leachate P 365 daf in either the banded or mixed applications. One glasshouse study on maize (Zea mays L.) grown in three soils were conducted at 0, 5, 10, 20, 40, 80, and 160 kg P ha-1 comparing CBP and APP fertilizer impacts on early season growth. CBP produced significantly more biomass in two soils when averaged across rates (and at the 20 kg P ha-1 rate in a third soil), increased petiole P in one soil and thicker stems in another. Two field trials showed similar physiological advantages with CBP over APP at later growth stages. CBP maize responded with significantly more biomass and P uptake at the V12-V18 growth stages in one field, as well as plant height in another. At the R2-R3 growth stages, CBP also produced thicker stalks in both fields than APP. These growth enhancements were strongest in medium to highly calcareous soil (6-12 %) low in P (7 mg kg-1). These observations warrant the use of CBP and further investigation to understand its benefits and limitations.
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Jesiek, Julie B. "Phosphorus Management: An Analysis of the Virginia Phosphorus Index". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/41298.
Testo completoAbstract (sommario):
Excess phosphorus (P) that is transported into water bodies can cause water quality problems. A high potential for P delivery occurs when there is a high transport potential from erosion, runoff, and/or leaching coupled with high soil test P and/or high rate of fertilizer P application. A management tool is needed to identify those fields that have a high transport and source potential to deliver P to surface water. The Virginia P-Index is a mass-based tool that estimates the annual risk of delivery of P from a given field to surface water. Guidelines on P application rates are then given based on the level of risk. This is a new tool and additional research and testing are needed to determine the dependability and validity of the index.
The overall goal of the research was to contribute to the continued development of the Virginia P-Index as an effective P management tool. A sensitivity analysis was completed to identify the parameters to which the P-Index was most sensitive under a range of conditions. In low erosion and runoff conditions, the P-Index was most sensitive to P management factors including application rate. As erosion and runoff potential increased, the P-Index was most sensitive to the erosion risk factors including soil loss. Under conditions with subsurface leaching, the P-Index was most sensitive to the subsurface leaching factors and Mehlich I soil test P. A stochastic analysis was also conducted to determine the effects of parameter variability. Variability of the P-Index output was greater as the risk of P delivery increased and this could affect management recommendations.
A survey was completed to determine expert opinion as to the appropriateness of parameter estimation methods used in the Virginia P-Index. Thirty-eight surveys were returned, representing a diverse range of participants within and outside of Virginia. Comments from the respondents were used to evaluate the appropriateness of the parameter methods. All factors were determined to be appropriate given the state of the science. Estimation methods for the following factors were determined to be less appropriate than the other sub-factors by the survey respondents: soil texture/drainage class, subsurface dissolved reactive orthophosphate (DRP), runoff delivery, and sediment delivery. The Virginia P-Index was determined to be a well thought out management tool and implementation should identify fields with the greatest risk of P delivery to surface water. Recommendations for improvement were identified including a need for additional analysis and studies.Master of Science
4
Bradford, Marie E. "The relationship between chemically analysed phosphorus fractions and bioavailable phosphorus /". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66053.
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Huang, Qianwen. "Electrodeposition of Amorphous Alloys: Nickel Cobalt Phosphorus and Iron Phosphorus". Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1465574470.
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Yue, Chaoyang. "Phosphorus recovery from a membrane enhanced biological phosphorus removal (MEBPR) process". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/60775.
Testo completoAbstract (sommario):
Phosphorus is an essential yet limited element for sustaining life of human beings. Municipal wastewater contains rich phosphorus, which is not sufficiently recovered or recycled. This dissertation developed a system that could recover phosphorus from wastewater as struvite fertilizer (MgNH₄PO₄•6H₂O). Such a system included three major components — a membrane enhanced biological phosphorus removal (MEBPR) process, a side-stream unit to extract PO₄³⁻ and NH₄⁺ from wasted solids, and a struvite crystallizer. This dissertation focused on optimizing the first two steps through pilot- and bench-scale studies, respectively.
The MEBPR process was tested at increasing solids retention time (SRT) to increase total phosphorus (TP) concentration in mixed liquor (ML). The operation at SRT = 60 days proved to be technically feasible and achieved comparable phosphorus removal (95−96 %) and organic carbon removal (91−92 %) to that observed during operation at the control SRT (25 days). The 60-day SRT operation also removed 14 % more nitrogen, wasted 17 % less dry solids, more than doubled the TP concentration of aerobic zone ML, but did not increase membrane fouling rates. Cost analyses showed that the energy requirements were 0.94 and 2.1 kWh/m³ of permeate for SRT = 25 and 60 days, both within the reported range for full-scale membrane bioreactors.
To solve foaming problem in the MEBPR process, foam was characterized as an alternative resource for phosphorus recovery. Methods were assessed to extract phosphorus from ML and foam. With suitable conditions, microwave-based hydrogen peroxide advanced oxidation process (MW-H₂O₂ AOP) could extract > 90 % of TP as PO₄-P from foam, and anaerobic P-release could extract up to 60 % from ML. Anaerobic digestion could extract 44−46 % of TP under digestion pHs, 64−65 % with pH ≤ 5.5, and generate sufficient NH₄⁺ that matched the quantities of PO₄³⁻ extracted.
Finally, a system was proposed that included an MEBRP process operating at SRT = 60 days, and an anaerobic digester to extract both PO₄³⁻ and NH₄⁺. This system could recover about 60 % of the incoming phosphorus in the influent. To recover more phosphorus, MW-H₂O₂ AOP could be used after anaerobic digestion, whenever justified.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Haysom, Joan E. "Quantum well intermixing of indium gallium arsenide(phosphorus)/indium phosphorus heterostructures". Thesis, University of Ottawa (Canada), 2001. http://hdl.handle.net/10393/9400.
Testo completoAbstract (sommario):
This thesis studies several aspects of the interdiffusion of InGaAs(P)/InP quantum well (QW) heterostructures, from the fundamental defect mechanisms, through optimization of processing parameters, to novel device applications. Conclusions from each of these areas have been drawn which further the scientific understanding and the manufacturability of the technique. The thermal stability of a series of different wafers is studied to highlight how poor quality of growth can cause increased interdiffusion, and to review the requirements for achieving repeatable annealing. Purposeful and controlled interdiffusion is accomplished through the introduction of excess defects into layers above the QWs, which during a subsequent anneal, diffuse through the QWs and enhance interdiffusion of atoms of the QWs with atoms of the barriers. These excess defects are introduced using two different techniques, via growth at low temperatures (LT) using chemical beam epitaxy (CBE), and via implantation of phosphorus ions. The CBE LT growth technique is new, and reported for the first time in this thesis. Characterization of the as-grown layers leads us to believe that they have an excess of phosphorus. The diffusion rate of the mobile defects which cause the intermixing is also measured, and the interdiffusion is shown to occur predominantly on the group-V sublattice. Due to many similarities between this and the results of the implantation technique, it is proposed that these mobile defects are the same for both intermixing approaches, and that the behaviour can be explained by a phosphorus interstitial mechanism. Annealing recipes for the implantation-induced technique are optimized, and the sample-to-sample reproducibility of the blueshift for this method was found to be quite good (standard deviations of ∼6 meV on blueshifts of ∼70 meV). The lateral selectivity and refractive index changes are characterized, and used in combination to create novel buried waveguide devices.
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Billaid, Abdulbari Mohammed. "Factors affecting phosphorus availability and phosphorus-use efficiency in barley genotypes". Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=167708.
Testo completoAbstract (sommario):
Sorption/desorption equilibria control the concentrations of P in the soil solution and thereby both its chemical and bioavailability. Apart from the equilibrium phosphorus dynamic, which has been used to determine buffer power and the equilibrium concentration for the studied soils at Cruden Bay, Balmedie, Blairton Wood and Newburgh, the buffer power and equilibrium concentration were affected by the fertiliser incubation period. The differences in PBP and EPC were observed between the soils with high constituents of organic matter and clay in their texture and those which had sandy and sandy loam textures. The glasshouse study was conducted to evaluate the relationship between soil phosphorus availability and two contrasting spring barley genotypes. Both genotypes: Tocada and Natasha responded to added phosphate fertiliser in all treatments. The vegetative growth variations among the genotypes did not appear at different phosphorus levels for most of the studied soils. However, the study has revealed the differences in the root system of Tocada and Natasha in low phosphorus conditions. Tocada was prone to forming large root biomass when compared to Natasha in insufficient phosphorus conditions. Natasha behaved in the opposite way in sufficient phosphorus conditions. The findings of this study confirm that phosphorus use efficiency and root architecture of these genotypes are correlated with each other to exploit more available phosphorus in the rhizosphere. Both Agronomic and physiology Phosphorus use efficiency have been tested. Although the difference in agronomic phosphorus use efficiency among the genotypes was not recorded, some different observations in physiological phosphorus use efficiency among the genotypes were noticeable in some cases.
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Bhandari, Ammar B. "Improving phosphorus loss assessment with the apex model and phosphorus index". Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32721.
Testo completoAbstract (sommario):
Doctor of PhilosophyAgronomy
Nathan O. Nelson
Agricultural fields contribute phosphorus (P) to water bodies, which can degrade water quality. The P index (PI) is a tool to assess the risk of P-loss from agricultural fields. However, due to limited measured data, P indices have not been rigorously evaluated. The Agricultural Policy/Environmental Extender (APEX) model could be used to generate P-loss datasets for P index evaluation and revision. The objectives of the study were to i) determine effects of APEX calibration practices on P-loss estimates from diverse management systems, ii) determine fertilizer and poultry litter management effects on P-loss, iii) evaluate and update the Kansas PI using P-loss simulated by APEX and iv) determine appropriate adsorption isotherms with advection-dispersion equation with column leaching experiment. Runoff data from field studies in Franklin and Crawford counties were used to calibrate and validate APEX. Poultry litter and inorganic fertilizer application timing, rate, method, and soil test P concentration effects on P loss were analyzed using location-specific models. A column leaching laboratory study was also conducted to test the adsorption isotherms. Location-specific model satisfactorily simulated runoff, total P (TP) and dissolved P (DP) loss meeting minimum model performance criteria for 2/3 of the tests whereas management-specific models only met the criteria in 1/3 of the tests. Applying manure or fertilizer during late fall resulted in relatively lower TP loss compared to spring applications before planting. The Kansas-PI rating and the APEX simulated P-loss were correlated with r² of 0.40 (p<0.001). Adjusting the weighting factors for Prate, soil test P, and erosion improved the correlation (r² = 0.46; p<0.001. Using a component PI structure and determining the weighting factors by multiple linear regression substantially improved the correlation between the PI and TP loss (r² = 0.69; p<0.001). In the P-leaching experiment, both the linear and nonlinear adsorption isotherms did not fit the experimental data. A multi-reactional advection-dispersion model that better describes all the P processes and complexities in soils should be included in the future. These procedures can provide a roadmap for others interested P transport in soils and using computer models in evaluation, and modifying their PI.
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Murby, Fredrika. "Phosphorus reduction in wastewater using microalgae with different phosphorus starvation periods". Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-82778.
Testo completoAbstract (sommario):
Anthropogenic induced nutrients in the Baltic Sea have led to 97% of it being eutrophic. Phosphorus is regarded the main regulating nutrient, and nearly 25% of the nutrients coming to the Baltic Sea originate from wastewater treatment plants. To reduce the nutrient concentrations in the effluents from treatment plants, tertiary treatment methods based on chemical dosing have been the principal answer. The chemicals create a sludge in addition to remediating the water, which needs disposal. Methods for remediating secondary wastewater with microalgae exist but are not common in conventional wastewater treatment. However, using microalgae could be beneficial, since they use inorganic carbon (from the atmosphere and wastewater) and inorganic nutrients, while producing biomass and oxygen. The biomass in turn has a potential to be used in production of bioenergy, food, and fertilizers. This thesis investigated whether pre-phosphorus starvation of five different microalgae strains enhanced the removal rate of phosphorus from secondary wastewater. The aim was to determine the optimal starvation period of different algae strains and to achieve wastewater effluent concentrations below 0.1 mg/L at the shortest possible time. Algae were transferred to a phosphorus-free media for five, three, one and zero days before entering the wastewater in a batch reactor at a temperature of 27°C and a 16:8 hours light and dark regime. Phosphate and nitrate concentrations as well as biomass production were monitored during a period of ten days. The experiment was repeated three times using Chlorella Vulgaris and two times using Tetradesmus Obliquus, Ankistrodesmus Falcatus, Botryococcus Braunii and one time using Desmodesmus Communis. The secondary wastewater was obtained from a small wastewater treatment plant from the village Roja in Latvia. Prior to the experiments, it was filtered three times through filters with different pore sizes (the smallest pore size was 0.2 µm), and the average nitrate and phosphate concentrations were 21.3 ± 1.1 mg/L and 17.8 ± 0.56 mg/L, respectively. The nitrate to phosphate ratio was 1.8:1. It was possible to remove the inorganic phosphorus to concentrations below 0.1 mg/L within ten days, although it did not happen in all the reactors. It was found that in most cases pre-phosphorus-starvation increased the removal rate of phosphorus. For two of the strains, Chlorella Vulgaris and Ankistrodesmus Falcatus, the three-day of pre-starvation period was optimal, while two to three days was optimal for Tetradesmus Obliquus, compared to other pre-starvation periods. For Botryococcus Braunii the one-day and the zero-days starved batches removed the phosphorus most efficiently. For Chlorella Vulgaris and Ankistrodesmus falcatus nearly a 100% of the phosphorus was removed within seven days after three days of pre-starvation. Without pre-starvation, these strains achieved the same result after ten days. It was also found that the nitrogen was the limiting nutrient in the wastewater and that the different strains responded differently to the changes in environment brought on by the experiment. When using microalgae in wastewater treatment, the choice of strain greatly impacts the removal rate, as the likeliness for them to survive in a specific environment varies among strains. It was concluded that using microalgae as a wastewater treatment method could pose great benefits. However, more experiments with colder climate, non-pre-filtered wastewater, a less nutrient rich media, greater initial biomass concentrations and pilot tests are recommended. Another insight from this thesis was that the method for transferring algae between different media needs to be refined to reach the target concentration in a reactor (or other setup).
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Wijesundara, Sunetra M. "Relationships of soil test phosphorus with soil properties and phosphorus forms". Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151136/.
Testo completo
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Dreyfuss, Sébastien. "Utilisation de phosphore blanc et d'aminophosphines pour la formation de nanocristaux d'InP". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30100/document.
Testo completoAbstract (sommario):
Ce travail de thèse porte sur la synthèse de nanocristaux de phosphure d'indium (InP) et en particulier sur l'utilisation de précurseurs phosphorés tels que le phosphore blanc et les aminophosphines. Les nanocristaux d'InP sont des matériaux semi-conducteurs prometteurs dans le cadre d'applications biologiques et optoélectroniques grâce à leur faible toxicité et à leurs spectres d'absorption et de fluorescence dans le visible. En outre, le phosphore blanc, allotrope le plus réactif du phosphore, est un produit industriel fabriqué à très grande échelle. Il est en effet à l'origine de tous les produits phosphorés à bas degrés d'oxydation tels que les phosphines. Sa fonctionnalisation directe visant à former des espèces chimiques nouvelles ou valorisables est un domaine de recherche actif. Alors que les nanocristaux d'InP sont traditionnellement synthétisés en utilisant une silylphosphine comme précurseur phosphoré, une nouvelle méthodologie reposant sur l'utilisation d'aminophosphines a émergé. Les aminophosphines étant plus facilement accessibles et manipulables que les silylphosphines, il s'agit d'une avancée importante pour le développement des nanocristaux d'InP. C'est pourquoi nous avons étudié précisément le mécanisme de formation de ces nanocristaux, en nous appuyant notamment sur la RMN, la spectrométrie de masse et les calculs DFT. Cette compréhension fine du mécanisme a permis l'optimisation de la synthèse des nanocristaux d'InP.L'utilisation du phosphore blanc pour former des nanocristaux d'InP repose sur la formation de nanoparticules d'indium monodisperses puis sur l'incorporation du phosphore à l'intérieur des nanoparticules. En partant d'une méthodologie de synthèse de nanoparticules d'indium de la littérature, nous avons découvert le paramètre central de la synthèse : la présence d'une quantité bien précise d'eau dans le solvant. Les nanoparticules d'indium ainsi formées sont oxydées en surface et doivent être activées afin de réagir avec le phosphore blanc.Enfin, la fonctionnalisation moléculaire du phosphore blanc avec des borohydrures pour former des liaisons P-H et par voie radicalaire pour former des silylphosphines est présentéeCe travail de thèse porte sur la synthèse de nanocristaux de phosphure d'indium (InP) et en particulier sur l'utilisation de précurseurs phosphorés tels que le phosphore blanc et les aminophosphines. Les nanocristaux d'InP sont des matériaux semi-conducteurs prometteurs dans le cadre d'applications biologiques et optoélectroniques grâce à leur faible toxicité et à leurs spectres d'absorption et de fluorescence dans le visible. En outre, le phosphore blanc, allotrope le plus réactif du phosphore, est un produit industriel fabriqué à très grande échelle. Il est en effet à l'origine de tous les produits phosphorés à bas degrés d'oxydation tels que les phosphines. Sa fonctionnalisation directe visant à former des espèces chimiques nouvelles ou valorisables est un domaine de recherche actif. Alors que les nanocristaux d'InP sont traditionnellement synthétisés en utilisant une silylphosphine comme précurseur phosphoré, une nouvelle méthodologie reposant sur l'utilisation d'aminophosphines a émergé. Les aminophosphines étant plus facilement accessibles et manipulables que les silylphosphines, il s'agit d'une avancée importante pour le développement des nanocristaux d'InP. C'est pourquoi nous avons étudié précisément le mécanisme de formation de ces nanocristaux, en nous appuyant notamment sur la RMN, la spectrométrie de masse et les calculs DFT. Cette compréhension fine du mécanisme a permis l'optimisation de la synthèse des nanocristaux d'InP.L'utilisation du phosphore blanc pour former des nanocristaux d'InP repose sur la formation de nanoparticules d'indium monodisperses puis sur l'incorporation du phosphore à l'intérieur des nanoparticules. En partant d'une méthodologie de synthèse de nanoparticules d'indium de la littérature, nous avons découvert le paramètre central de la synthèse : la présence d'une quantité bien précise d'eau dans le solvant. Les nanoparticules d'indium ainsi formées sont oxydées en surface et doivent être activées afin de réagir avec le phosphore blanc.Enfin, la fonctionnalisation moléculaire du phosphore blanc avec des borohydrures pour former des liaisons P-H et par voie radicalaire pour former des silylphosphines est présentée
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Nadeem, Muhammad. "Remobilization of seed phosphorus reserves and exogenous phosphorus uptake during germination and early growth stages of maize (Zea mays L.)". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14439/document.
Testo completoAbstract (sommario):
Le phosphore (P) est un élément indispensable pour la croissance des plantes. De nombreux travaux montrent des réponses très précoces à une limitation de la disponibilité en P. Pendant la germination et la croissance juvénile, la demande en P des plantules peut être satisfaite par la remobilisation des réserves en P des graines et le prélèvement racinaire. Les objectifs de la thèse sont d’étudier la contribution respective de la remobilisation des réserves en P des graines et du prélèvement racinaire de P à l’alimentation en P des plantules de maïs, et les interactions entre ces deux processus. Différentes expériences ont été conduites pour i) étudier les cinétiques de la remobilisation des réserves en P des graines, ii) identifier précisément le début du prélèvement de P exogène par les racines, iii) quantifier la contribution relative de ces flux à l’alimentation en P de la plantule, iv) comprendre les interactions entre ces flux. Des graines riches et des graines pauvres en P on été cultivées à différents niveaux de disponibilités P exogènes pendant quatre semaines. Le traçage isotopique du P exogène (32P) a été utilisé pour quantifier le flux de prélèvement et calculer le flux de remobilisation du P des graines. Initialement, 86% du P sous forme phytate et 13% du C de la graine est localisé dans le scutellum indépendamment du niveau de richesse en P de la graine. 4 jours après le semis, 98% des phytates des graines sont hydrolysés. La cinétique d’hydrolyse des phytates est indépendante de la richesse en P des graines et de la disponibilité en P dans le milieu. Le P issu de l’hydrolyse des phytates est stocké temporairement dans la graine avant d’être transporté vers les organes en croissance de la plantule. Le prélèvement de P exogène commence dès l’émergence de la radicule (4ième jour) et dépend de la disponibilité en P dans le milieu. L’initiation du prélèvement et son intensité ne dépend pas du flux de remobilisation des réserves en P de la graine. Le P issu de la remobilisation et du prélèvement est distribué dans les mêmes proportions entre les parties ariennes et racinaires. Un bilan de P à l’échelle de la plantule entière et de la graine a permis de mettre en évidence un efflux de P depuis la graine vers l’extérieur pendant la phase d’hydrolyse des phytates. La modélisation des flux de P pendant la germination et la croissance précoce permet de rendre compte des observations sous l’hypothèse d’absence d’interaction entre les flux de remobilisation et de prélèvement de P bien que ces deux processus se chevauchent dans le temps. Nos résultats démontrent l’importance de la disponibilité locale en P dans le milieu pendant les stades précoces indépendamment du niveau de richesse en P des grainesPhosphorus (P) is an essential element for plant growth. Many studies have shown a very early seedling response to the limitation on the availability of P. During germination and early growth, the seedling P demand may be satisfied by the remobilization of seed P reserves and exogenous P uptake by developing roots. The objective of the thesis was to study the relative contribution of remobilization of seed P reserves, the exogenous P uptake by seedling roots and the interaction between these two processes. Various experiments were conducted to i) study the kinetics of the remobilization of seed P reserves, ii) identify precisely the beginning of exogenous P uptake by seedling roots, iii) quantify the relative contribution P fluxes in developing seedlings and iv) the interaction between these two P fluxes. Seeds with low and high P reserves were cultivated at different levels of exogenous P availability for the growth period of four weeks. The exogenous P was labelled with radioactive P (32P) to identify and quantify the P flux in young seedlings coming from exogenous P uptake and seed P reserves remobilization. Initially, 86% of P in the form of phytate and 13% C of seed reserves is localised in scutellum regardless of P initial seed P reserves. Four days after germination, 98% of seed phytate reserves are hydrolyzed. The kinetics of seed phytate hydrolysis was independent of seed P reserves and exogenous P availability. The hydrolyzed forms of phytate were temporarily stored in the seed before being translocated towards newly growing seedling compartments. The exogenous P uptake started soon after the radicle emergence (4th day) and depend mainly on the availability of exogenous P in the growth medium. The beginning of exogenous P uptake and its intensity was not influenced by the seed P reserves remobilization. The proportion of distribution of remobilized seed P reserves and the exogenous P uptake was similar among seedling shoot and roots. The whole seed and seedling P budget showed the significant P losses from germinating seeds by P efflux with the beginning of phytate hydrolysis in seeds. We proposed a model for the seed P remobilization and exogenous P uptake during germination and early growth. Assuming no interaction between seed P reserves remobilization and exogenous P uptake, the simulations were found to be in close agreement with experimental data. Our results showed the importance of exogenous P availability in growth medium during early growth stages regardless of seed P reserves
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Cauduro, John, e john cauduro@dpi vic gov au. "In vitro testing of inorganic phosphorus sources for phosphorus availability in swine". RMIT University. Applied Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090401.141751.
Testo completoAbstract (sommario):
This research project compares different chemical and spectroscopic techniques aimed at finding a quick and cheap replacement for the measurement of digestibility of phosphorus (P) in different inorganic feed additives for pigs. This research yielded a comparison of the digestibility of different feed additives. P digestibility was determined from in vivo studies of pigs. The animal feed in the in vivo studies contained P levels below the nutrient requirements. The basal diet was a corn soybean meal base. Assessment was performed on 6 different inorganic P sources, rock phosphate (tricalcium phosphate (TCP)), meat and bone meal (MBM), mono/dicalcium phosphate (MDCP) and three different dicalcium phosphates (DCPs). Eight pigs where selected and placed into separate pens. Two were given basal diets and the other 6 diets were randomly selected and supplied with the different inorganic P sources. P digestibility was calculated by difference. The apparent P digestibility of the sources were: TCP at 46 %, the MBM at 85 %, MDCP at 71 % and three DCPs ranged from 49 % to 73 %. This substantiated that the apparent P digestibility in the major inorganic sources of P is significantly less than 100%. The in vitro or chemical methods of assessing phosphorus availability in animal feed included the commonly used feed extraction methods of water solubility and 2 % citric acid. These two methods showed significant differences between each other. Other chemical methods used included calcium chloride, ammonium acetate, sodium bicarbonate extractions, and a double extraction using hydrochloric acid (HCl) followed by sodium bicarbonate. The chemical methods showed non-significant correlation coefficients when compared to in vivo P digestibility of the six phosphate ingredients used. Infra-red spectroscopy is now commonly used in feed production for many other nutritional tests. NIR, although being able to obtain an R2 above 0.999 for correlation curves and factor prediction curves, could not obtain a self prediction of the calcium phosphates due to the large Mahalanobis Distance. P digestibility predicted by MIR showed close agreement with the in vivo P digestibility. Again due to the small number of ingredients tested in the pig trial, the prediction of digestibility using MIR could only be compared to it self. Hence MIR can only be used as an estimate until more data can be obtained. The P31 SS-MAS-NMR indicated one of the DCPs was made up of 3 or more P compounds by displaying 3 major peaks. All the P chemical shifts from the faeces had different positions to the P peaks in the ingredients, indicating some sort of change in the P form. Overall the chemical methods were unable to predict P digestibility, and while the spectroscopic techniques showed promise, they still require more work to examine many more feed additives.Invitro, invivo, phosphorus, digestibility, swine, infra-red spectroscopy, solid state NMR
15
Brownlie, Will. "Assessing the role of domestic phosphorus emissions in the human phosphorus footprint". Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2782.
Testo completoAbstract (sommario):
Societal phosphorus (P) use is unsustainable; P is vital for food security and its increase in the ecosphere is the single greatest cause of water quality degradation on the planet. The following thesis focuses on the role domestic P emissions play in the human P cycle with an aim to support management in reducing the individual P footprint. Measurement of the P composition of private sewage system (PSS) effluent was used to assess domestic P emissions from properties located within the Loch Leven catchment, in East Scotland, UK. This thesis shows PSS treatment type (i.e. level of additional treatment further to a single settling tank) does not reduce effluent P concentration, challenging the efficacy of policies aiming to reduce P pollution from PSS by technological solutions. Using a questionnaire, assessment of domestic and PSS maintenance behaviours of 156 PSS users indicated reductions in P emissions may be achieved through behavioural change. To understand the impact of behaviour on the human P footprint, a novel method using 31P nuclear magnetic resonance (NMR) spectroscopy was successfully developed to identify P compounds related to human behaviour (e.g. washing machine use) in PSS effluent. An assessment of the impact of behaviours on the human P footprint of ten individual households was conducted. Thesis findings conclude PSS desludging reduces concentrations of orthophosphate in PSS effluent; 85% of the variation in total soluble P in PSS effluent can be explained by ‘desludging frequency’ and ‘washing machine use’. Furthermore, PSS users feel responsible for correctly maintaining their PSS, but are potentially not maintaining them effectively or have poorly installed or inadequate systems, and do not know how to reduce domestic P emissions. A need for better public education on PSS maintenance and how to reduce domestic P emissions is required. This work highlights a critical need to integrate social sciences with natural sciences to tackle unsustainable P use.
16
Williams, Gareth Rhys. "The synthesis and applications of new organo-phosphorus and organofluorine-phosphorus compounds". Thesis, University of Manchester, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528265.
Testo completo
17
Foreman, Mark Russell StJohn. "Organo-sulfur phosphorus chemistry". Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/27934.
Testo completoAbstract (sommario):
P-organo-substituted dithiadiphosphetane disulfides have been prepared by the reaction of ferrocene and arenes with P4S10. Reaction of these compounds and Lawesson's reagent with alkenes, 2,3-dimethylbutadiene and other compounds gave organo-sulfur phosphorus compounds including 1,2-thiaphosphetane-2-sulfides such as P-ferrocenyl 1,2,5,5,7,8-hexamethyltricyclo[3,2,5,2,0]-3-thia-4-phospho-oct-7-ene-4-sulfide and a thiaphosphorine sulfide (P-ferrocenyl 4,5-dimethyl-3H,6H-1,2-thiaphosphinine-2-sulfide). Treatment of P-ferrocenyl thiaphosphorine sulfide with BuLi followed by carbon containing electrophiles (such as benzyl bromide or 2,4-dinitrochlorobenzene) gave ring-opened products. In addition treatment of dithiadiphosphetane disulfides with organic carbonyl compounds, including ketones, gave thiocarbonyl compounds. Platinum complexes were formed from the dithiadiphosphetane disulfides.
18
Homan, Christopher David. "Phosphorus derivatives of carbohydrates". Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239564.
Testo completo
19
Edwards, Christopher. "Phosphorus functionalised polymeric supports". Thesis, University of Warwick, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342700.
Testo completo
20
Leute, Maria. "Macromolecules with phosphorus functionalities". [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-60833.
Testo completo
21
Schönberger, Stefanie. "Phosphorus, sulfur and pyridine". Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-166120.
Testo completoAbstract (sommario):
The synthesis of distinct neutral or anionic P,S compounds in solution provides a
great challenge for chemists. Due to the similarity in the energies of the P–P, P–S and
S–S bonds nearly solely a mixture of compounds with different composition and
charge is obtained. Our interest focuses on the system consisting of phosphorus,
sulfur and pyridine, with the aim of a greater selectivity of P,S compounds in solution.
The combination of these three components offers the opportunity of stabilizing
unusual P,S compounds as pyridine adducts or pyridinium salts, integration of main
group and transition metals (formation of metal-thiophosphates) and the investigation
of many more reactions of this class of compounds in a basic environment.
22
Wikberg, Karl Anders. "Phosphorus Balance of Sweden". Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263424.
Testo completoAbstract (sommario):
Phosphorus (P) is an essential element for all life on our planet. During the past century anthropogenic consumption of P has reached critically unsustainable levels, the mining of finite phosphate rock and the dispersion of this resource could lead to resource scarcity in the future. The need to increase knowledge and understanding for the P system is an essential part of sustainable decision making. In this thesis the P balance of Sweden is characterised and quantified using material flow analysis methodology. Furthermore, the study provides a solid foundation of knowledge and understanding of the current state of P balance in Sweden. Major challenges are highlighted and further improvement potential is established for the Swedish flows of P. The major identified contributors to the Swedish P balance are the consumption of mineral fertilizers, the consumption patterns in society and the waste management. Moreover, there is a need to reduce the emissions of P to the environment in order to preserve natural state. The most effective ways of reducing the emissions are to reduce inputs to the system and improve the system efficiency through technical solutions, political tools and financial incentives. It is important to reduce emissions without shifting of burdens onto others. The anthropogenic activities in Sweden have a significant impact on the environment, this is due to Sweden importing P fertilizer that is added to the system. Nevertheless, there is a large potential for improvement of P resource management, where recycling and reuse of P is highlighted. Furthermore, Sweden has historically proven that political action and financial incentives are effective in reducing emissions.Fosfor (P) är ett väsentligt element för allt liv på vår planet. Under det senaste århundradet har den antropogena förbrukningen av P uppnått kritiskt ohållbara nivåer, brytning av begränsade mängder fosfatmalm som finns och spridningen av denna resurs kan leda till resursbrist i framtiden. Behovet av att öka kunskapen och förståelsen för P systemet är en väsentlig del av hållbart beslutsfattande. I denna avhandling karakteriseras och kvantifieras P balansen i Sverige med hjälp av metoder för materialflödesanalys. Dessutom ger studien en stadig grund för kunskap och förståelse för det nuvarande tillståndet för fosforbalansen i Sverige. Viktiga utmaningar lyfts upp och ytterligare förbättringspotentialer fastställs för de svenska flödena av P. De viktigaste identifierade påverkningsfaktorerna till den svenska P-balansen är konsumtion av mineralgödsel, konsumtionsmönstren i samhället och avfallshanteringen. Utöver detta, finns det ett behov av att minska utsläppen av P till miljön för att bevara ett naturligt tillstånd. De mest effektiva sätten att minska utsläppen är att minska tillförseln av P till systemet och förbättra systemeffektiviteten genom tekniska lösningar, politiska verktyg och ekonomiska incitament. Det är viktigt att minska utsläppen utan att förskjuta bördorna på andra. Den antropogena verksamheten i Sverige har en betydande påverkan på miljön, detta beror på att Sverige importerar P gödsel som läggs till systemet. Ändå finns det en stor potential för förbättring av P resurshanteringen, där återvinning och återanvändning av P framlyfts. Dessutom har Sverige historiskt bevisat att politiska åtgärder och ekonomiska incitament är effektiva för att minska utsläppen.
23
Cordell, Dana. "The Story of Phosphorus : Sustainability implications of global phosphorus scarcity for food security". Doctoral thesis, Linköping : Department of Water and Environmental Studies, [The Tema Institute], Linköping University, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-53430.
Testo completo
24
Challa, J. "Phosphorus and calcium metabolism in growing calves with special emphasis on phosphorus homeostasis". Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371434.
Testo completo
25
Soltani, Morteza. "Strength, fracture morphology, and polymorphic phase transformations in phosphate-bonded high-alumina refractory compositions". Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/19060.
Testo completo
26
Maghraoui, Tasnime. "Diversité génotypique et fonctionnelle des rhizobia associés aux cultures mixtes Fève-Blé en conditions limitantes de phosphore au Maroc". Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT147.
Testo completoAbstract (sommario):
Cette étude a pour principal objectif de mettre en évidence le rôle des bactéries solubilisatrices de phosphate (rhizobia) dans une meilleure gestion des systèmes de cultures associant la fève (légumineuse) et le blé (céréale) en monoculture et en cultures mixtes sous des conditions de déficience en P. Cent neuf souches de rhizobia ont été isolées à partir des nodules racinaires des plantes de V. faba dans la région de Marrakech. Les analyses phylogénétiques basées sur les gènes 16S rDNA, recA et nodD montrent que les souches étudiées sont proches phylogénétiquement de R. leguminosarum biovar viciae, de R. laguerreae et de Ensifer meliloti. Nous avons également décelé la présence du gène pqqC qui est impliqué dans la solubilisation du phosphate (pyrroloquinoline quinone synthase C) chez 15 souches de rhizobia. 22% de ces souches ont été identifiées comme étant capables de solubiliser le phosphate minéral. Ensuite, nous avons montré que l’inoculation avec certaines souches de rhizobia ayant la capacité de solubiliser le P in vitro améliore la croissance des plants de fève et de blé en serre (en monoculture et culture mixte). Nous avons aussi noté des réponses différentes à l’effet de l’inoculation selon les combinaisons symbiotiques étudiées fève-rhizobia. Nous avons également montré que les souches de rhizobia peuvent stimuler le transfert d'azote fixé de la fève au blé, ce qui pourrait contribuer de manière significative au processus de facilitation plante-plante dans les cultures en association dans des conditions de sols carencés en phosphore. En plus de ces avantages de l’association, cette pratique culturale n’est pas limitée à un effet trophique (amélioration de la nutrition azotée des plantes), mais pourrait résulter d'interactions microbiennes qui peuvent agir directement sur la croissance du blé (effet PGPR). Les résultats des expérimentations menées en serre et au champ montrent, en effet, que les cultures mixtes stimulent la croissance du blé ainsi que sa nutrition minérale (N et P).Ces résultats soulignent l'utilité de développer ce type de pratiques culturales associant les légumineuses et les céréales et d'utiliser les ressources microbiennes locales dans les agro-écosystèmes afin d’améliorer la production agricole, en réduisant l’utilisation des intrants chimiques coûteux et néfastes pour l'environnementThe main purpose of this study is to evaluate the role of phosphate solubilizing rhizobial strains in promoting faba bean (legume) and wheat (cereal) growth in mono and mixed cultures under phosphorus deficiency conditions. 109 rhizobial strains have been isolated from nodules of V. faba plants in Marrakech region. Phylogenetic analysis based on 16S rDNA, recA and nodD genes showed that the studied strains are close to Rhizobium leguminosarum biovar viciae, R. laguerreae and Ensifer meliloti. We detected the presence of pqqC gene which is implicated on phosphate solubilization (Pyrroloquinoline-quinone synthase C) in 15 rhizobia strains. 22 % of isolated strains were found to be able to solubilize mineral phosphate. We have demonstrated that the inoculation with some of rhizobial strains with PSolubilization capacity in vitro, improved the growth of fava bean and wheat plants in greenhouse (both in mono and mixed cultures). We noticed different reactions to the inoculation's effect, depending on the symbiotic combinations faba bean-rhizobia studied. We also showed that rhizobial strains can stimulate the transfer of fixed nitrogen from the bean to the wheat, which could contribute significantly to the plant-plant facilitation process in associated cultures with phosphorus deficiency conditions. Besides this association advantages, this cultural practice is not limited to a trophic effect (improvement of the nitrogenous nutrition of plants), but could engender microbial interactions which can directly enhance the wheat growth (PGPR effect). The results of the experiments conducted in greenhouse and on field show that mixed cultures stimulate wheat growth and its mineral nutrition (N and P). These results underline the utility of developing this kind of cultural practices associating legumes and cereals, and to use the local microbial resources in the agro-ecosystems to improve the agricultural production by reducing the use of agricultural improvers among others expensive artificial fertilizers which represent a threat to the environment
27
Shanklin, Rachel Kristina. "Effect of Form and Amount of Phosphorus and Phytase Supplementation on Phosphorus Utilization by Ruminants". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34316.
Testo completoAbstract (sommario):
The use of animal manures to replace commercial fertilizer has increased the economic and environmental sustainability of agriculture. However, this practice has resulted in excess P being applied to the soil in some areas. Excess P may run-off into surface water and leach in the ground, causing eutrophication. Decreasing the amount of P fed and improving the utilization of P are two possible nutritional solutions to this problem. Two experiments were conducted to investigate the effects of levels of dietary P, chemical form of P, and phytase supplementation in ruminants. For Exp. 1, 24 steers (average BW = 229 kg) were allotted to two diets containing 0.12 and 0.19% dietary P for a 112-d growth trial. The steers were individually full-fed, weighed every 14 d, and blood samples were collected every 28 d. The steers fed the 0.12% P diet had increased (P<0.02) ADG during the first 28 d, after which there were no differences. They also had higher (P<0.05) feed intake. By d 56 serum P for the 0.12% P group was lower (P<0.01), and this difference continued for the remainder of the trial. For Exp. 2, 18 wether lambs (average BW = 23 kg) were allotted to the following six diets for each of two metabolism trials: 1) a negative control diet deficient in P, 2) control diet supplemented with inorganic P, 3) control diet supplemented with phytic acid, 4) control diet supplemented with phytic acid and phytase, 5) control diet supplemented with cottonseed meal, and 6) control diet supplemented with cottonseed meal and phytase. Each metabolism trial was preceded by a 5 wk depletion phase in which the lambs were fed a low-P diet. The metabolism trials consisted of a 10 d preliminary period followed by a 10-d collection of feces and urine. On the final day ruminal fluid, blood, and saliva were collected. At the end of the second metabolism trial 10th rib bones were collected from each lamb. Absorption of P was lowest (P<0.0001) for the low-P treatment, compared to the other treatments. There was no treatment effect on saliva P. Ruminal fluid P was higher (P<0.05) for lambs receiving P supplementation. Within supplementation treatments, ruminal fluid P was higher (P<0.05) for lambs fed organic P than for those fed inorganic P. Feeding CSM resulted in higher (P<0.001) ruminal fluid P than phytic acid. The addition of phytase to the diets with organic P resulted in more (P<0.04) P in the ruminal fluid. There was a decrease (P<0.003) in serum P associated with the low-P treatment. There was no difference in bone ash or breaking strength.Master of Science
28
Smith, Lydia. "Missisquoi Bay Sediment Phosphorus Cycling: the Role of Organic Phosphorus and Seasonal Redox Fluctuations". ScholarWorks @ UVM, 2009. http://scholarworks.uvm.edu/graddis/217.
Testo completoAbstract (sommario):
Missisquoi Bay, Lake Champlain is a eutrophic, northern shallow freshwater bay that experiences toxic cyanobacteria blooms during the summer months, largely as result of high nutrient (P and N) loading from the agricultural watershed. The sediments, which contain minerals that readily sorb P, can act as a sink or source of water column nutrients. Phosphorus, both inorganic and some organic forms, sorbs to metal oxides at neutral pH in the sediment, thus P release into overlying and pore water can be significantly affected by the reduction and subsequent solubilization of these oxides. This study addresses novel aspects of nutrient cycling in lake sediments as part of a larger study to better understand the link between phosphorus forms, mobility, and cyanobacteria blooms. These aspects include: 1) diel and seasonal sediment redox fluctuations and 2) the role of organic P (Porg) in overall P mobility within sediments as a function of depth and time. Missisquoi Bay sediment porewater redox chemistry was monitored across diel and seasonal cycles over the course of two summers (May-October, 2007 and 2008) by using in-situ voltammetry. Redox chemistry was monitored at the sediment-water interface (SWI) continuously over diel cycles, and the vertical concentration profiles of several key redox species (O2, Mn2+, Fe2+, and FeS(aq)) were obtained from cores collected at different times. The sediments were then analyzed for Total P (TP), Reactive P (RP), Porg, Mn, Fe, Ca, Al, Total Organic C and N. A bloom did not occur in Missisquoi Bay during the summer of 2007, but did in summer of 2008, providing an opportunity to compare the sediment chemistry between non-bloom and bloom conditions. Increasingly anoxic SWI conditions across summer 2008 were observed but the SWI remained oxic for the duration of summer 2007. Significant changes in diel cycle redox chemistry at the SWI were also detected in both summers. Reactive P in the surface sediments decreased across the 2008 season but not in 2007. A strong correlation found between RP and RFe (operationally defined as Fe(III)OOH) suggests that a significant portion of sediment P (30-40%) is closely associated with Fe(III)OOHs, which are susceptible to reduction in anoxic conditions. Phosphorus mobility from the sediment into the water column can be limited by the amount of Fe(III)OOH at the surface, thus P flux from the sediments would be greatest when reducing conditions promote solubilization of these minerals. Completely anoxic surface sediments were only observed during the presence of a bloom, explaining the loss of RP in the surface sediments in 2008 in the late summer. Organic P species represent 18-26% of the P in sediments and the lack of a definite, consistent trend of Porg fractionation across the season suggests that there is variable mobility and degradation of these complex organic compounds on small timescales. The loss of RP from the sediment in 2008 could have contributed to an estimated water column P increase on the order of thousands of μg/L, which in addition to measured increases in NH4+ gradients and subsequent N flux estimates in the upper sediment, could have sustained the bloom for an extended period of time. The relationship between the bloom and reducing sediment conditions suggest that bloom dynamics enhance nutrient release from the sediments, allowing for proliferation and sustainability of the bloom.
29
Qiu, Jieru. "Dendrons phosphorés fluorescents amphiphiles : synthèse, caractérisation, applications en oncologie". Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30274.
Testo completoAbstract (sommario):
Les nanotechnologies ont le grand potentiel de révolutionner des technologies classiques variées, dû au développement de nombreux nanodispositifs et ont été intensément étudiées durant la dernière décade. Parmi les nanoparticules utilisées, les dendrimères et dendrons appartiennent à ce "nano-monde" en vertu de leur taille nanométrique, qui peut être modifiée à volonté, ainsi que par exemple leur multivalence et leurs charges. A l'intérieur de l'espace dendrimère, les dendrimères phosphorés apparaissent comme étant parmi les systèmes dendritiques les plus utiles, grâce à l'extraordinaire réactivité et adaptabilité de la chimie du phosphore. Dans ce mémoire nous décrivons la synthèse de plusieurs familles de dendrons phosphorés fluorescent amphiphiles potentiellement intéressants dans les domaines des nanomatériaux et de la nanomédecine. L'hexachlorocyclotriphosphazene utilisé comme cœur a été substitué par cinq groupements hydroxybenzaldehyde et un monomère tel que le pyrene ou un dérivé maleimide comme entité fluorescente ou l'azabisdimethylphosphonate comme groupement non fluorescent. Ces dendrons ont été préparés jusqu'à la génération 2 selon une voie divergente. La dernière étape a consisté en un greffage d'aminopyrrolidine ou aminopipéridine, suivi par protonation par HCl des groupements amines cycliques terminaux conduisant à la formation de dendrons phosphorés amphiphiles. La caractérisation physico-chimique a été réalisée par tout un ensemble de techniques : RMN, UV, CMC, diffusion dynamique de la lumière, potentiel zéta, microscopie électronique à transmission, fluorescence, dichroïsme circulaire, thermogravimétrie. L'étape suivante a consisté en l'étude des propriétés biologiques. Leur cytotoxicité a été déterminée en utilisant des tests MTT et Alamar Blue, effectués sur onze lignées cancéreuses ou saines (HL-60, HCT-116, A549, MCF7, PC3, U87, K562, K562R, MCR5, MDA-MB231 and HT-29). Des tests d'hémolyse ont été effectués pour tester l'effet des dendrons sur la membrane des cellules. Leur habilité à s'associer à du matériel génétique tels que les petits ARN interférents (siRNA siBCL-xL) a été mise en évidence par des expériences notamment d'électrophorèse sur gel. L'internalisation de ces associations (dendriplexes) dans les cellules tumorales a été suivie par cytométrie en flux. Dans le but de moduler les propriétés anticancéreuses des dendrons fluorescents amphiphiles, des quantum dots de carbone (CQDs) ont été associés avec les dendrons pyrene en présence d'un agent cytotoxique comme la doxorubicine encapsulée dans les micelles formées par les dendron pyrene et les CQDs. [...]Nanotechnologies have the high potential to revolutionize various other classical technologies in many fields, due to the development of numerous nanodevice types, and have been intensively studied over the last decade. Among these nanoparticles, dendrimers and dendrons pertain to the "nano-world" by virtue of their size. Their nanometric sizes can be tailored as well, for instance, their multivalency and charges. Within the dendrimer space, phosphorus dendrimers and dendrons appear to be among the most useful dendritic systems due to the extraordinary reactivity and versatility of the phosphorus chemistry. In this thesis, we designed several families of original amphiphilic fluorescent phosphorus dendrons with interesting potential in the fields of nanomaterials and nanomedicine. Hexachlorocyclotriphosphazene used as a core was linked with five 4-hydroxybenzaldehyde and one monomer (pyrene and maleimide derivatives as fluorescent monomers and azabisdimethylphosphonate derivatives as non-fluorescent monomer). The dendrons were prepared up to generation 2 by a divergent method. The last step is the grafting of amino pyrrolidine or amino piperidine following by protonation with HCl to get the expected cationic amphiphilic fluorescent phosphorus dendrons. Their physical characterization were evaluated through numerous technics: NMR, UV, critical micelle concentration (CMC), dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), fluorescent spectra, circular dichroism and thermogravimetry. In a next step, the biological properties of the dendrons have been examined. The cytotoxicity of dendrons was determined using MTT test and Alamar Blue assay performed on eleven cells lines including both cancer cells and healthy cells (HL-60, HCT-116, A549, MCF7, PC3, U87, K562, K562R, MCR5, MDA-MB231 and HT-29 cells line). Hemolysis assays were used to test the effect of dendrons on the cell membrane. Their ability to bind genetic material was studied by gel electrophoresis using fluorescein-labeled small interference RNA siBCL-xL. Flow cytometry method was used to study the internalization of dendriplexes into tumor cells. In order to modulate the anticancer properties of the fluorescent dendrons, carbon quantum dots (CQDs) were chosen to conjugate with the pyrene dendrons in the presence of a cytotoxic agent like doxorubicin (DOX), physically loaded into 'micelles'. [...]
30
Gill, Stephen. "Phosphorus liberation by aquatic microorganisms /". Electronic version (Microsoft Word), 2006. http://dl.uncw.edu/etd/2006/gills/stephengill.doc.
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31
Davis, Clare Elizabeth. "Phosphorus dynamics in shelf seas". Thesis, University of Liverpool, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569162.
Testo completoAbstract (sommario):
Shelf seas are highly productive regions of the world's ocean. Contributing 16 - 30 % to global ocean carbon fixation while representing a mere 7 % of the area, their importance in the carbon cycle is disproportionate to their size. This high productivity has econonimical significance, supporting over 90 % of global fishery yields (Pauly et al., 2002). Shelf seas are also physically dynamic regions. On an annual cycle, the water column in shelf seas is fully mixed in winter and thermally stratified in summer in deeper regions, with enhanced mixing along the shelf-edge. In addition, shelf seas act as a buffer between the land and coastal seas, and the open ocean. However, the processes that transform nutrients within the shelf sea are poorly understood. More so, the role of physical processes in both transporting nutrients, as well as their interaction with the biological processes that govern nutrient concentrations and partitioning are currently unresolved. Here, nutrient dynamics, with a specific focus on phosphorus, were assessed within the Celtic Sea, part of the northwest European shelf. The distribution and partitioning of phosphorus between the particulate (PPhos) and dissolved organic (DOP) and inorganic (DIP) phases was determined over various temporal and spatial scales. The concentration of labile DOP (phosphomonoesters, PME) and its rate of turnover were determined using enzyme rate assays. The microbes involved in PME hydrolysis were identified using enzyme labelled fluorescence techniques. The influence of physical processes, including spring-neap tidal cycle, mixing over topography and storm enhanced mixing on the vertical distribution of phosphorus in the water column were also assessed. DOP accumulated in the surface layer of the thermally stratified shelf waters and at the shelf edge. DOP production was enhanced at the shelf edge and during storm events due to enhanced mixing and fluxes of phosphate, which were rapidly shunted into the DOP pool through enhanced primary production. However, during mixing there was a counteracting downward flux of DOP exported to the bottom waters. Profiles of PME concentrations revealed a relatively labile component to bottom layer DOP, which had turnover times in the order of days. Comparison of observations in the Celtic Sea and Porcupine Bank region demonstrated that the accumulation of DOP on the shelf and at the shelf edge relative to the adjacent slope and oceanic regions is a persistent feature of the western European continental margin. Through a number of shelf-edge exchange processes, including wind mixing on short time scales, tidal mixing on fortnightly timescales and seasonal winter mixing, the Celtic Sea was identified as a potential source of DOP to the North Atlantic, where production is thought to be phosphorus limited (Mather et al., 2008).
32
Hogan, Erika. "Nitrogen-phosphorus relationships in lichens". Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10906/.
Testo completoAbstract (sommario):
Nitrogen enrichment promotes phosphomonoesterase (PME) activity in the common heathland lichen Cladonia portentosa. This is associated with a marked increase in thallus N:P mass ratio and significant up-regulation of inorganic phosphate uptake capacity, evidencing a shift from N-limited to P-limited growth. Phosphomonoesterase activity in C. portentosa responds rapidly to change in N deposition load, with a significant increase in activity recorded within 6 months of transplantation from a low-N to high-N site. The location of PME activity in C. portentosa was revealed using a fluorescent marker and was found to be concentrated on both the outer and inner surfaces of the hollow ‘tube-like’ thallus branches. Activity appeared to be associated exclusively with the mycobiont and was located within the hyphal-lumina, consistent with a membrane bound ecto-enzyme. High PME activity in axenic mycobiont cultures of C. portentosa provided further evidence of a fungal location and confirmed that rates of activity in this lichen are amongst the highest reported for any other plant/fungal system in the literature. Different classes of phosphatases were assayed in a range of N2-fixing and non-N2-fixing lichens in an oligotrophic subarctic environment. No relationship was found between the capacities for nitrogenase and PME activities. Maximum rates of PME activity were recorded in fruticose mat-forming lichens which capture nutrients predominantly from atmospheric deposits. 5´ nucleotide phosphodiesterase activity was readily detected in N2-fixing lichens and was particularly high in rhizine-rich regions of foliose terricolous lichen thalli, consistent with the utilisation of organic phosphates from soil and litter sources.
33
Wilkes, Philip John. "NMR of phosphorus-containing solids". Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6666/.
Testo completoAbstract (sommario):
The purpose of this work has been the determination of structure in solids using the technique of solid-state nuclear magnetic resonance spectroscopy. High-resolution (^31) p NMR spectra have been obtained for a range of phosphate species. A number of techniques have been applied to these systems including cross-polarization, magic angle spinning, and high power proton decoupling. Characterisation using additional NMR techniques such as (^1) H cramps has been carried out wherever possible. The results obtained yield molecular and crystallographic information consistent with data from X-ray diffraction when known. Shielding tensor components were determined from static and/or spinning spectra wherever possible. The phosphate species studied include a series of precipitated calcium phosphates. A particular model for the structure of amorphous calcium phosphate is favoured in the light of (^31) p NMR measurements. One sample showed NMR evidence for changes in composition whilst in the solid state. The origins of (^31) p NMR line widths in high-resolution solid-state spectra have been considered in some detail. Variation of (^31) p NMR linewidth as function of spinning rate has been noted for a number phosphate compounds. Multiple pulse techniques have been applied on the phosphorus channel with pleasing improvements in spectral resolution. Five solid binary phosphorus sulphides have also been studied using phosphorus MAS NMR, and the results compared to solution state data wherever possible. A number of anomalies between solution and solid-state data have been noted and discussed.
34
Cooper, S. J. "Phosphorus metabolism in environmental microorganisms". Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438177.
Testo completo
35
Prastka, Katherine. "Phosphorus cycling in intertidal sediments". Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320776.
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36
Root, A. "NMR of phosphorus containing compounds". Thesis, University of East Anglia, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372798.
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37
Kleemann, Rosanna. "Sustainable phosphorus recovery from waste". Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809963/.
Testo completoAbstract (sommario):
Phosphorus (P) is an essential non-substitutable nutrient for all living organisms, but it is also a dwindling non-renewable resource. Approximately two-thirds of the world’s supply of phosphate rock is located in China, Morocco, and the USA. Phosphate rock is included in the EU list of ‘critical raw materials’ and is ranked 20th in an index of commodity price volatility. P recovery from waste water can help alleviate reliance on imported phosphate and reduce vulnerability to fluctuating prices. This project explored the options for P recovery from wastes produced across Thames Water’s waste water treatment plants (WWTPs), the main foci being sludge dewatering liquors and incineration/pyrolysis residues. The research focussed specifically on the Slough WWTP and the operation of a newly installed Ostara system for recovery of P as struvite from dewatering liquors. The Ostara process is designed to operate with centrate PO4-P concentrations above 100 mg/l; to obtain these concentrations chemical coagulant dosing in the enhanced biological nutrient removal process must be reduced. Centrate monitoring following this change showed that Fe concentrations must measure consistently below 1.5 mg/l for PO4-P concentrations to remain steadily above 100mg/l. Following these changes onsite, operational savings and revenue can be produced onsite. Significant operational and maintenance savings totalling to £113K can be made in the first year of operation of the P recovery system in Slough WWTP. Sale of P rich struvite fertiliser produces annual revenue of £20K. Moving beyond the local benefits of P recovery, national benefits of P recovery were quantified. In a national context, a total of 28±1 kt P/year can be recovered from all WWTP waste streams, reducing P fertiliser imports by 36±1%. P recovery from WWTP influent and incinerated sewage sludge ash would reduce P losses to water bodies by 22±2%. Sewage sludge may be incinerated, producing incinerated sewage sludge ash (ISSA), or alternatively pyrolysed to produce sewage sludge char (PSSC). The possibility of recovering P from these residual solids was also investigated. PSSC samples contained significantly more nitrogen and lower heavy metal concentrations than ISSA samples due to the process conditions. The % P extractions from both ISSA and PSSC plateaus at 0.6M and 0.8M H2SO4 acid concentrations, respectively, due to the formation of gypsum on the particles, so that further increase in acid concentrations does not increase P recovery. The knowledge gained through this research has been used to improve the understanding and efficiency of the P recovery system at Slough WWTP. The information learned about pyrolysis residues will be used by Thames Water to develop a novel P recovery process from PSSC. Combined, these findings can impact the industry by creating incentives and inform policies regarding P recovery.
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Thomas, Stephen Patrick. "Phosphorus mediated asymmetric cyclopropane synthesis". Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613118.
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39
Garland, Jacqueline M. "Studies in phosphorus-selenium chemistry". Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3688.
Testo completoAbstract (sommario):
Phosphorus-Selenium chemistry has seen a surge in development over the last five to ten years thanks to the optimisation of the synthesis of 2,4-diphenyl-1,3,2,4-diselenadiphosphetane-2,4-diselenide, Woollins' Reagent. This selenium analogue of the well known Lawesson's Reagent has proved itself to be a valuable asset to modern inorganic chemistry, providing a route to novel heterocycles, as well as acting as a selenation reagent with a wide range of functional groups. A series of new ammonium phenylphosphonamidodiselenoate ligands were synthesised via the reaction of Woollins' Reagent with a range of amines. The products were obtained in high yields and could be used as ligands for the synthesis of novel metal complexes. The reaction of diisopropylamine N-isopropyl-P-phenylphosphonamidodiselenoate with nickel(II) acetate produces a dimeric structure, whilst the reaction with copper(II) acetate yields a beautiful cluster of the form Cu₆Se₃L₆. The phenylphosphonamidodiselenoate ligands were further reacted with a range of cis-Pt(PR₃)₂Cl₂ complexes to form a library of 20 novel compounds, which were studied by ³¹P{¹H}, ⁷⁷Se{¹H} and ¹⁹⁵Pt{¹H} NMR spectroscopy. The X-ray crystal structure of one of these compounds was obtained, which confirmed the atom connectivity and spatial arrangement of the complexes and the geometry around the platinum centre. During investigations into the above-mentioned platinum complexes, it was postulated that an increase in steric bulk of the phosphine ligands would aid crystallisation of the products. As such, trimesityl-, dimesitylphenyl- and mesityldiphenyl phosphine were synthesised and reacted with elemental sulfur and selenium and hydrogen peroxide, as well as Pt(cod)Cl₂ and K₂[PtCl₄], yielding nine new structures, all of which were characterised by X-ray crystallography, ³¹P{¹H}, ¹³C{¹H} and ¹H NMR spectroscopy. Finally Woollins' Reagent was reacted directly with a selection of metal complexes, yielding some new insights into its reactivity with inorganic moieties, which has been relatively sparsely reported until now.
40
Brown, Martyn A. "Phosphorus and arsenic carbohydrate derivatives". Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU552502.
Testo completoAbstract (sommario):
A series of O-diphenylphosphinyl monosaccharide derivatives, e.g. 1,2:5,6-di-O-cyclohexylidene-3-O-diphenyl phosphinyl--D-glucofuranose [60], has been synthesised by reaction of a free hydroxy group in a sugar with Ph_2PCl. C-Diphenylphosphinyl and diphenylarsino derivatives, e.g. methyl 4,6-O-benzylidene-3-deoxy-3-C-diphenylarsino--D-altropyranoside [89], were synthesised via reaction of Ph2PLi or Ph2AsLi with p-tosyl, mesyl, epoxy or carbonyl substituted sugar reagents. Steric factors play a large part in determining the reactivity of the precursor sugars towards the phosphorous or arsenic nucleophilic reagents. Conformations of the arsenic and phosphorus derivatives were assigned from the 13C, 1H and 31P NMR spectra. Analogous phosphinyl and arsino derivatives have the same conformations in solution. Generally, the pyranosides prefer the 4C1 conformation in solution while the furanoses and furanosides prefer a symmetrical twist. Ribofuranosides [52], [67] and [83], prefer the 2T3 conformation as to the mannofuranosides [56], [57], [58], [63] and [64], whereas xylofuranose derivatives [53] and [86] prefer the 3T2. The solid state NMR of [65] and [89] were also obtained and compared with the solution NMR. No major conformational differences were evident. The following alicyclic carbohydrate derivatives were also synthesised - 1,4:3,6-dianhydro-2,5-dideoxy-2,5-bis-C-diphenylarsino-L-iditol [99], 1,4:3,6-dianhydro-5-deoxy-5-C-diphenylarsino-2-O-p-tosyl-L-gulitol [100], 1,4:3,6-dianhydro-2-deoxy-2-C-diphenylarsino-L-iditol [97] and the 2-O- p -tosyl derivative [98] and 1,4:3,6-dianhydro-5-C-diphenyl-phosphinyl-2-O- p -tosyl-L-iditol [81]. Reactions of the carbohydrate derivatives with transition metal hexacarbonyls were also carried out. Methyl 4,6-O-benzylidene-2-deoxy-2-C-diphenylarsino--D-altropyranoside [88] gave a tetracarbonyl complex [114] on reaction with Cr(CO)_6 and two products from W(CO)_6, viz W_2(CO)_8(AsPh_2)_2 [111] and the dimer [W_2(CO)_9(H)L]. - [112]. The bridged dimer W_2(CO)_10(AsPh_2)_2 [113] was obtained from the reactions of the bis-diphenylarsino derivatives of L-iditol [99] and diisopropylidene-D-galactose [82]. The complex [Rh(1,5-cyclooctadiene)L]. &'43 BF_4. - [116] was synthesised on reaction of the chlororhodium dimer [Rh(COD)Cl]_2 with the bis-diphenylarsino-L-iditol derivative [L&'61 99].
41
Creekmore, Cathy E., e J. L. Stroehlein. "Phosphorus Response in Wine Grapes". College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/215732.
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42
Dean, Kyla. "Phosphorus runoff to Clear Creek". Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/943.
Testo completoAbstract (sommario):
Phosphorus is a nutrient crucial to row crop production, but phosphorus runoff from fields to nearby surface waters is a persistent problem that threatens the quality of rivers and streams. This is especially true for Iowa with its abundance of agricultural practices. In order to better understand the phosphorus dynamics of a watershed with agricultural land use, Clear Creek in Iowa was studied. Total, dissolved, and suspended reactive phosphorus concentrations were measured and mass fluxes were calculated. Through this research it was determined that most of the mass of phosphorus in Clear Creek is transferred during high flow events and is attached to solids. The headwaters area of this stream was found to be a major source of phosphorus due to the abundance of row crops and steeply sloped land.
43
Micheletti, Gabriele <1977>. "Abiotic and prebiotic phosphorus chemistry". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3841/1/Micheletti_Gabriele_tesi.pdf.
Testo completoAbstract (sommario):
The chief obstacle to understand the metabolic origin of life or RNA-based life is to identify a plausible mechanism for overcoming the clutter wrought by abiotic chemistry. Probably trough simple abiotic and then prebiotic reactions we could arrive to simple pre-RNA molecules.
Here we report a possible preibiotic synthesis for heterocyclic compounds, and a self-assembling process of adenosine phosphates a constituent of RNA. In these processes we use a simple and prebiotic phosphorus cyclic compounds, as P4O10 and its derivatives. The processes are driven by the formation of hypercoordinated species that activate the processes by a factor of 106-8.
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Micheletti, Gabriele <1977>. "Abiotic and prebiotic phosphorus chemistry". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3841/.
Testo completoAbstract (sommario):
The chief obstacle to understand the metabolic origin of life or RNA-based life is to identify a plausible mechanism for overcoming the clutter wrought by abiotic chemistry. Probably trough simple abiotic and then prebiotic reactions we could arrive to simple pre-RNA molecules.
Here we report a possible preibiotic synthesis for heterocyclic compounds, and a self-assembling process of adenosine phosphates a constituent of RNA. In these processes we use a simple and prebiotic phosphorus cyclic compounds, as P4O10 and its derivatives. The processes are driven by the formation of hypercoordinated species that activate the processes by a factor of 106-8.
45
Capacci, Chiara <1989>. "Nickel-Phosphorus Homoleptic Carbonyl Clusters". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/7927/1/Capacci_Chiara_Tesi.pdf.
Testo completoAbstract (sommario):
This project is focused on the synthesis, the characterisation, and the study of the reactivity of a novel group of carbonyl clusters - nickel-phosphorus homoleptic carbonyl clusters.
The interest in this couple of elements has risen because of their peculiar characteristics - in the past years nickel-phosphorus binary phases and nanoparticles have been widely used both as hydroprocessing catalysts and for their ceramic properties. In fact, by now nickel is the best transition metal to use in form of phosphide if a catalytic behaviour is expected. A further investigation on nickel-phosphorus molecular compounds could help in understanding how these materials operate.
The first part of the work concerns the syntheses of new nickel-phosphorus homoleptic carbonyl clusters, and their structural and spectroscopical characterisations. Several new species will be introduced, as [Ni11P(CO)18]3-, [Ni14P2(CO)22]2-, [Ni23-xP2(CO)30-x]4- (x = 0, 1), [Ni23-xP2(CO)30-x]6- (x = 0, 1), [HNi31P4(CO)39]5-, [H2Ni31P4(CO)39]4-, [Ni29P5(PO)(CO)36]4-, [Ni39P3(CO)39]6-.
The second part of the work examines the reactivity and the behaviour of the new nickel-phosphorus homoleptic carbonyl clusters. The species were tested regarding their possible redox properties, their acid-base properties, and their response towards various reactants, and the corresponding results will be reported.
Eventually, a further structural analysis will be proposed, which was specifically designed for the comparison of these new nickel-phosphorus homoleptic carbonyl clusters with other heteroatomical nickel clusters, as well as with other transition metal-phosphorus clusters.
The collected data will be used to draw some conclusions concerning the characteristics of this novel family of compounds, as well as their possible future applications.
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Thompson, Christopher. "The Effect of Phosphorous Placement & Rate on Phosphorus Uptake, & Growth & Yield of Tomatoes". TopSCHOLAR®, 1990. https://digitalcommons.wku.edu/theses/2931.
Testo completoAbstract (sommario):
Research was undertaken in the summer of 1989 to determine the effect of phosphorus placement on the yield and quality of field grown tomatoes Lycopersicon esculentum. A subsequent study was undertaken in the winter of 1989 to determine the effect of phosphorus rate and placement on the early growth and phosphorus uptake of young tomatoes in the greenhouse.
The purpose of this study was to attempt to find the most efficient placement and rate of supplemental phosphorus when growing tomatoes. It has been shown that placing phosphorus in a concentrated zone in contact with plant roots results in more growth and fruit yield. The current trial involved the application of phosphorus at different rates and use of different methods of application. The methods of application included broadcasting phosphorus, placing phosphorus in a concentrated band, and combinations of the two.
It is of great interest to the tomato producer to know the most efficient rate and placement of fertilizer phosphorus. Availability of phosphorus is necessary for the proper development of the tomato and a good supply is needed for adequate yield and quality. If improved application methods are developed, perhaps higher yields and improved fruit quality can be realized. This could possibly result in higher production for the producer and more satisfaction for consumers.
The results of the field study were not statistically significant. One reason for the lack of any yield response was the greatly reduced yields caused by hail damage and fungal disease.
Surprisingly, the greenhouse study showed that significant growth increase resulted from phosphorus broadcast treatments. One explanation may be the small volume of soil used in this study. The plant roots were distributed throughout the entire soil volume in contrast to the situation with widely spaced field grown tomatoes. Thus, the broadcast treatments achieved more root-fertilizer contact in the greenhouse pot cultures.
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OSAFO, NANA. "Phosphorus in the sediment of L. Hällerstadsjön: spatial distribution, fractions and release to the water volume". Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-131757.
Testo completoAbstract (sommario):
: In freshwater systems phosphorus (P) is the limiting element in the cause of eutrophication. In many Swedish lakes, causes of eutrophication have been attributed to more of internal loading than external since the external loading has been fairly well managed. Internal loading is linked to the mobility of sediment P, which are known to be Bioavailable P (BAP). Sediments from Lake Hällerstadsjön in Sweden was studied to know the BAP concentration and its possible release into the water column under reduced conditions. Sediments were sampled at two different depths, 0-5 cm and 5-10cm. BAP was determined by a phosphorus fractionation scheme. Sediments were incubated under oxic and anoxic conditions in the laboratory to evaluate sediment P release. Spatial variation in the distribution of P forms across the lake was also studied, in order to examine possible local patterns, particularly along a transect from the main inlet to the outlet. Fractionation analyses showed a trend of; Residual-P > NaOH-P > HCl-P > BD-P > Loosely bound P. The fractions constituting the BAP was higher at the 0-5 cm sediment depth than 5-10 cm. Sediment P flux was recorded for anoxic but not oxic sediment. BAP correlated significantly with sediment P flux (P= 0.01). Spatially, the P distribution varied both at depths and along a latitudinal transect, from the main inlet to the outlet. Dredging of the surface sediments with high BAP content would possibly be an effective means of preventing eutrophication of the lake.
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Broomhead, Jonathan. "Calcium and phosphorus requirements in turkeys and an in vitro procedure for predicting phosphorus release /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3164491.
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Carliell-Marquet, Cynthia. "The effect of phosphorus enrichment on fractionation of metals and phosphorus in anaerobically digested sludge". Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/17074.
Testo completoAbstract (sommario):
In designated nutrient-sensitive areas, phosphorus must be removed from sewage before it is discharged to the receiving water body. Phosphorus-rich sludge is generated, which is usually digested anaerobically prior to disposal. This research investigated the effect of phosphorus enrichment on metal and phosphorus fractionation in anaerobically digested sludge. The use of two complementary sequential chemical extraction procedures to measure phosphorus and metal fractionation, was a key focus of the research. The fractionation procedures were tested by sequentially extracting inorganic compounds (phosphates, sulphides and carbonates) which showed that the operationally defined metal and phosphorus fractions were not always representative of precise metal phases. Species were tentatively assigned to metal and phosphorus fractions using model compound results. Laboratory-scale batch anaerobic digestion experiments were performed, in which model compounds were used to simulate conditions of soluble and insoluble phosphorus enrichment. Soluble phosphorus at concentrations of 500 mg/l or greater was found to retard volatile solids removal and methane production in the laboratory digesters. Soluble phosphorus enrichment facilitated precipitation of calcium, magnesium and manganese but increased trace metal solubility, particularly that of chromium. Enrichment of digesters with Na2HP04 and MgCb caused struvite to precipitate in digesters containing 1000 mg/l of additional phosphorus. FeP04 enrichment of digested sludge showed that ferric iron was reduced to ferrous iron, releasing soluble phosphorus into the digester. Most of the phosphorus was reprecipitated as ferrous phosphate, causing co-precipitation of magnesium, manganese and cobalt. By contrast, A1P04 added to the digesters was stable in the sludge. Full-scale CPR sludge digestion (Fe2(S04)3 dosing) caused soluble phosphorus in the digester to decrease below 0.05 mg/l. Phosphorus remained associated with iron in the sludge fraction but soluble calcium and magnesium concentrations in the full-scale digester increased as a result of CPR sludge digestion. Comparison of laboratory and full-scale results showed that the fate of iron-precipitated phosphorus in digested sludge was primarily dependent pn the molar ratio of Fe:P in the sludge. Full-scale BPR sludge digestion showed high concentrations of soluble phosphorus in the digester and some struvite precipitation, although phosphorus was precipitated primarily as calcium phosphate, as was found to occur in the laboratory digesters simulating BPR sludge digestion.
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Carr, Stephen Thomas David. "Investigation into phosphorus removal by iron ochre for the potential treatment of aquatic phosphorus pollution". Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/7663.
Testo completoAbstract (sommario):
Phosphorus (P) pollution of waterbodies is a global issue with detrimental environmental, social and economic impacts. Low-cost and sustainable P removal technologies are therefore required to tackle P pollution, whilst also offering a technique for reclaiming P. Ochre, a waste product from minewater treatment plants (MWTPs), has been proposed as a suitable material for the removal of P from enriched waters due to a high content of Fe, Al, Ca and Mg, which have high affinities for P removal. Whilst a range of studies have been conducted investigating ochre as a P adsorbent, most of these are large-scale field experiments and lack understanding of the underlying processes of P removal by ochre. There have also been very few detailed comparisons of different ochre types. The primary focus of this thesis is thus to provide a process-based understanding of P removal by various ochres, in order to investigate the optimal conditions for the use of ochres in the treatment of aquatic P pollution. Seven ochres from six MWTPs in the UK and Ireland were investigated, one of which was in a pelleted form. The ochres were largely comprised of Al, Ca, Fe and Mg (42-68 % by dry weight), had a high B.E.T. surface area, 56-243 m2 g-1, and contained mineral surfaces with a high affinity for P adsorption, such as goethite and calcite. A novel batch experiment methodology was utilised to calculate the adsorption characteristics of ochre at discrete pH conditions. The variation of these characteristics with pH indicates the importance and requirement for such a method to study adsorption by materials at the expected pH conditions of application. At the pH conditions of wastewater streams (~pH 7), the P adsorption capacities of the ochres, determined from fitting adsorption isotherms, was 11.8–43.1 mg P g-1. Results of P adsorption batch experiments were modelled in ORCHESTRA, wherein P removal by the ochres was described well by adsorption onto hydrous ferric oxides. Three of the ochres contain relatively high calcite contents and due to a poor fit of the model to the observed datasets at high pH conditions, with equilibrium P concentrations lower in the batch experiments than the modelled result, adsorption onto calcite is suggested as a P removal mechanism for these ochres at pH > 7. Environmental application of ochre filters will require P removal under flow-through transport conditions. Column experiments were therefore conducted using two ochres, coarse-grained Polkemmet ochre and Acomb pellets (column volume 1055 cm3, pore space 490-661 cm3, typical pore volumes of experiments: 220-400). P removal efficiency increased with contact time, and the presence of competing ions had only marginal effects on P removal. Resting the column substrate for 48 hours between P applications greatly increased the P removal efficiency of a packed column of Polkemmet ochre, resulting in 81 % of influent P removed over 1000 pore volumes of operation (7.68 mg P g-1). Acomb pellets had a lower P removal efficiency than Polkemmet ochre. It is suggested that the high calcium content of the pellets, as a result of the pelletisation process, has created a substrate where the dominant P removal mechanism at neutral pH conditions is adsorption to calcite, which has slower reaction kinetics than adsorption onto goethite. Therefore, this pelleted ochre requires a higher contact time for adsorption reactions to occur. It is suggested that ochre filters are most suitable for application in situations where flow rate is constant or can be controlled e.g. septic tank effluent. Ochres which dry to a coarse particle size are preferred for use as a substrate as pelletisation requires capital, expertise and can produce substrates with slower P sorption kinetics. Resting the filter substrate between P application regenerates surface sites for adsorption, and filters should be run in parallel to maximise P removal efficiency. Acomb pellets, which are a mix of iron hydroxides and alkaline materials, may have potential application as a permeable reactive barrier substrate to treat P enriched ground waters. Further research utilising fine-grained ochres as an additive to P rich fertilisers or for use in continuously stirred tank reactors is recommended.