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Robert, Susan Amie. "The combined use of aluminium-tolerant cultivars and agroforestry prunings in alleviating the effects of soil acidity on maize production in Sierra Leone." Thesis, University of Reading, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506119.
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Xu, Xiaohan. "Acidity of Lanthanide Clusters." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619532111562154.
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Crowhurst, Lorna. "Acidity in ionic liquids." Thesis, Imperial College London, 2006. http://hdl.handle.net/10044/1/11301.
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Chagas, Junior Aloísio Freitas. "Características agronômicas e ecológicas de rizóbios isolados de solos ácidos e de baixa fertilidade da Amazônia." Universidade Federal do Amazonas, 2007. http://tede.ufam.edu.br/handle/tede/3094.
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To increase the rhizobia contribution to plants nutrition and development is necessary to develop researches for selecting more efficient nitrogen fixation strains. This research work had as objectives, to accomplish morphologic characterization of rhizobia isolated from Amazonian soils; laboratory evaluations about the tolerance to acidity and toxic Al, the capacity to solubilize calcium (P-Ca) and aluminum (P-Al) phosphates, the indole-acetic acid production (AIA); the ability of the isolates to induce nodulation and to fix nitrogen under the acidity and low fertility conditions of the regional soils in greenhouse experiment; to genetically characterize the isolated ones selected using the PCR-RFLP technique. The infectivity test showed that there was significant increase in the cowpea biomass. With relationship to the phenotypic characterization, the 200 isolates showed a great diversity. Among these, 165 and 127 presented high tolerance within the media with pH 4,5 and pH 4,5 + Al, respectively. From the 200 isolates, 68 solubilized P-Ca and 47 P-Al, and 32 isolates solubilized both P-Ca and P-Al. The AIA production significantly increased (p <0,01) with tryptophan quantities added in the medium for 19 of the 92 isolates tested in the experiment. It was observed production of dry matter and nodule number and mass superior simbiotic to the control treatment and similar to the fertilized treatment for various rhizobia isolates. The 20 selected isolates evaluated presented high genotypic diversity, with the derived dendrogram PCR-RFLP profiles showing that they can be divided inside two main genders, Rhizobium and Bradyrhizobium. Associating the results of simbiotic efficiency and nodulation, it was observed that the isolates of rhizobia from Amazonian soils presented good results, and they can be recommended for tests of agronomic efficiency for cowpea bean.
Para aumentar a contribuição de rizóbia na nutrição e desenvolvimento de plantas é necessário desenvolver pesquisas de seleção de estirpes mais eficientes quanto à fixação do N2. Este trabalho teve como objetivos, realizar a caracterização morfológica de isolados de rizóbio oriundos de solos amazônicos; avaliar em laboratório, a tolerância à acidez e Al tóxico, a capacidade de solubilização de fosfato de cálcio (P-Ca) e alumínio (P-Al), a produção de acido indol-acético (AIA); a capacidade de isolados em induzirem nodulação e fixarem nitrogênio sob as condições de acidez e baixa fertilidade dos solos regionais em casa-de-vegetação; caracterizar geneticamente os isolados selecionados usando a técnica de PCR-RFLP. Os testes de infectividade mostraram que houve aumento significativo na biomassa de caupi. Quanto à caracterização fenotípica, os 200 isolados mostraram uma grande diversidade. Dentre estes, 165 e 127 isolados apresentaram elevada tolerância nos meios de cultura com pH 4,5 e pH 4,5 + Al, respectivamente. Dos 200 isolados testados, 68 solubilizaram P-Ca e 47 P-Al, sendo que 32 solubilizaram tanto o P Ca quanto o P Al. A produção de AIA aumentou significativamente com as doses de triptofano adicionadas ao meio (p<0,01) para 19 dos 92 isolados testados no experimento. Observou-se produção de matéria seca, número e massa seca dos nódulos e acúmulo de nitrogênio superiores ao tratamento testemunha e similares ao tratamento adubado para vários isolados de rizóbia. Os 20 isolados selecionados e avaliados apresentaram alta diversidade genotípica, onde o dendrograma derivado de perfis de PCR-RFLP mostrou que podem ser divididos dentro de dois gêneros principais, Rhizobium e Bradyrhizobium. Associando-se os resultados de eficiência simbiótica e nodulação, observou-se que os isolados de rizóbio de solos da Amazônia apresentaram bom desempenho e podem ser recomendados para testes de eficiência agronômica em feijão caupi.
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Smallbone, Kieran. "The role of acidity in tumour development." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442910.
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Acidic pH is a common characteristic of human tumours. It has a significant impact on tumour progression and response to therapies. In this thesis, we utilise mathematical modelling to examine the role of acidosis in the interaction between normal and tumour cell populations. In the first section we investigate the cell–microenvironmental interactions that mediate somatic evolution of cancer cells. The model predicts that selective forces in premalignant lesions act to favour cells whose metabolism is best suited to respond to local changes in oxygen, glucose and pH levels. In particular the emergent cellular phenotype, displaying increased acid production and resistance to acid-induced toxicity, has a significant proliferative advantage because it will consistently acidify the local environment in a way that is toxic to its competitors but harmless to itself. In the second section we analyse the role of acidity in tumour growth. Both vascular and avascular tumour dynamics are investigated, and a number of different behaviours are observed. Whilst an avascular tumour always proceeds to a benign steady state, a vascular tumour may display either benign or invasive dynamics, depending on the value of a critical parameter. Extensions of the model show that cellular quiescence, or non-proliferation, may provide an explanation for experimentally observed cycles of acidity within tumour tissue. Analysis of both models allows assessment of novel therapies directed towards changing the level of acidity within the tumour. Finally we undertake a comparison between experimental tumour pH images and the models of acid dynamics set out in previous chapters. This analysis will allow us to assess and verify the previous modelling work, giving the mathematics a firm biological foundation. Moreover, it provides a methodology of calculating important diagnostic parameters from pH images.
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Jacob, Daniel J. Hoffmann Michael R. "The origins of inorganic acidity in fogs /." Diss., Pasadena, Calif. : California Institute of Technology, 1985. http://resolver.caltech.edu/CaltechETD:etd-01112005-133508.
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Ceciliani, Francesco. "Taster responses to acidity in white wines." Master's thesis, ISA-UL, 2017. http://hdl.handle.net/10400.5/13344.
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Mestrado Vinifera Euromaster - Instituto Superior de Agronomia - UL / Universitá degli Studi di UdineThe aim of this study was to evaluate the responses of a panel of tasters trained to acidity in white wines. The training of tastes and sensations of the mouth was performed in relation to the acidity, sweetness, bitterness and astringency. Next, the tasters were segmented according to vinotype, sensitivity to PROP (6-n-propylthiouracil) and saliva flow. This panel was used to determine the detection and recognition thresholds of tartaric, malic and lactic acids in white wine with 4.2 g / L of total acidity. The detection and recognition thresholds were 1.05 g/L and 1.32 g/L for tartaric acid, 0.85 g/L and 1.06 g/L for malic acid and 1.12 g/L and 1.30 g/L for lactic acid, respectively. These acids were added to an Arinto wine at concentrations 1.5 times higher than the recognition threshold, obtaining responses regarding the flavor effect considering intensity, persistence, salinity and appreciation. There were no differences (p<0.05) in relation to the first 3 parameters, while the appreciation was higher in relation to lactic and malic acids. The statistical treatment of the responses according to the segmentation revealed relationships (p<0.05) between saliva flow and sensitivity to PROP, and between saliva flow and the tartaric acid recognition threshold. The acidity appreciation was higher in men than in women. The results obtained can be used by the wine industry in the sense of adapting the white wines to the preference of the consumers, taking into account the recent trend towards the consumption of cold climate wines.
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Shoghi, Kalkhoran Elham. "Physico-Chemical Characterization of Drugs: Acidity and Solubility." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/98463.
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The aim of the present work was to contribute to establish robust and high throughput methodology of interest in the "Drug Discovery" step commonly done in pharmaceutical laboratories. This purpose involves the exploration of the possibilities of the potentiometric Sirius methodology to determine both acidity constants and solubilities of drugs and other bioactive compounds and also to do a study about how to improve bioavailability of a model drug, Amphotericine 8, by increasing its dissolution rate. In the first part of this project, the acidic dissociation enthalpies and constants of anilinium, protonated tris (hydroxymethyl)- aminomethane (HTris+), benzoic and acetic acids, have been determined at several temperatures in pure water and in methanol/water mixtures by potentiometry method. The pK(a) values determined by this technique are in accordance with those values determined by ITC method in our laboratory and also with those other values from literature. Also dissociation enthalpies can be obtained from potentiometric pK(a) values by means of the Van't Hoff approach and these obtained values are in agreement with those ones determined directly by calorimetry in our laboratory. In the second part, we focused on studying about solubility. The Chasing Equilibrium method offers an alternative to the classical procedures to measure the solubility of compounds with acid-base properties. The method is fast and yields accurate results. In this work, the solubility of several compounds including acids and bases was determined through the Chasing Equilibrium approach. A study of experimental conditions in terms of sample weight was performed to measure solubilities. The study shows that only a limited range of weights, depending on the nature and solubility of the compounds, is adequate to obtain reliable results. In the third part of this work, the solubility vs. pH profiles of five ionizable drugs of different nature (a monoprotic acid, a monoprotic base, a diprotic base and two amphoteric compounds showing a zwitterionic species each one) have been determined through two different methodologies: the classical Shake-Flask (S-F) and the potentiometric Cheqsol methods using in both instances the appropriate Henderson-Hasselbalch (H-H) or derived relationships. The results obtained independently from both approaches are consistent. A critical revision about the influence of the electrolyte used as buffering agent in the S-F method on the obtained solubility values is also performed. Thus, some deviations of the experimental points with respect the H-H profiles can be attributed to specific interactions between the buffering electrolyte and the drug due to the hydrotrophic character of citric and lactic acids. In other cases, the observed deviations are independent of the buffers used since they are caused by the formation of new species such as drug aggregates (cefadroxil) or the precipitation of a salt from a cationic species of the analysed compound (quetiapine). In the forth part, the objective was to compare the dissolution behavior of tablets prepared from solid dispersions prepared in DMSO dissolvent with and without drug-carrier and also with and without surfactants in aqueous and acidic solutions. Amphotericine B was used as a model drug. Two types of carriers were used; mannitol, inulin. Solid dispersions with two different drug loads were prepared by freeze drying method. It was found that the drug dissolution rate in aqueous and acidic solutions was significantly increased in the presence of drug-carrier and surfactants. X-ray powder diffraction revealed that all solid dispersions were fully amorphous.El objetivo del presente trabajo ha sido contribuir a establecer metodología robusta y de high throughput de interés en la etapa conocida como "Drug Discovery" que tiene lugar en los laboratorios farmacéuticos al inicio del proceso de desarrollo de nuevos fármacos. Este objetivo ha implicado la exploración de las posibilidades de la metodología potenciométrica establecida y comercializada por Sirius Analytical Ltd. para la determinación de las constantes de acidez y de la solubilidad de compuestos bioactivos y también un estudio sobre la mejora de la biodisponibilidad de un fármaco muy insoluble tomado como modelo mediante el aumento de su velocidad de disolución. En la primera parte de esta Tesis se han determinado potenciométricamente las constantes de disociación ácida y la variación de entalpía asociada de dos bases y dos ácidos tomados como modelo en agua pura y en mezclas de metanol/agua (0-60% w/w) a varias temperaturas (25-55°C). Esto ha implicado la puesta a punto de la estandarización del sistema potenciométrico en las condiciones de trabajo. Los valores de pK(a) determinados son concordantes con los que ofrece la literatura. Se han calculado también las entalpias de disociación en los distintos solventes binarios estudiados mediante la ecuación de Van't Hoff a partir de los valores experimentales de pK(a). La consistencia de los resultados obtenidos con los de la literatura, obtenidos directamente por calorimetría, confirma la robustez de la metodología. En la segunda parte de este trabajo, el estudio se centró sobre la determinación potenciométrica de la solubilidad de ácidos y bases mediante el método conocido como Chasing Equilibrium, como alternativa a los procedimientos clásicos de equilibración. El método es rápido y produce resultados precisos. Se ha realizado un estudio sobre las condiciones experimentales óptimas en términos de peso de la muestra para medir eficazmente la solubilidad. El estudio muestra que, en función de la naturaleza y solubilidad de los compuestos, existe un intervalo limitado de peso de muestra adecuado para obtener resultados fiables. En la tercera parte de la presente memoria, se estudian los perfiles de solubilidad en función del pH de cinco fármacos ionizables de naturaleza diferente, un ácido y una base monopróticos, una base diprótica y dos compuestos anfóteros que muestran una especie zwitteriónica cada uno. Se han determinado los perfiles de solubilidad mediante el método clásico de equilibración (Shake-Flak, S-F) y el potenciómétrico y, en ambos casos, se han utilizado las relaciones apropiadas de Henderson-Hasselbalch (H-H) o derivadas. Los resultados obtenidos de forma independiente por ambos métodos son consistentes. Se ha hecho un estudio crítico acerca de la influencia del electrolito utilizado como agente tampón en el método S-F en los valores de solubilidad obtenidos y se han observado algunas desviaciones de los puntos experimentales con respecto a los perfiles esperados que pueden ser debidas a interacciones específicas entre el electrolito tampón y el fármaco. En otros casos, las desviaciones observadas son independientes de los tampones utilizados y se pueden atribuir a la formación de nuevas especies tales como agregados iónicos del fármaco en estudio o la precipitación de una sal a partir de una especie catiónica del compuesto analizado. En la cuarta parte de esta memoria el objetivo ha sido estudiar la velocidad de disolución de comprimidos preparados a partir de dispersiones sólidas de un fármaco modelo con y sin portador del fármaco y también en presencia y en ausencia de tensioactivo en soluciones acuosas neutras y ácidas. Como fármaco modelo se estudió la Anfotericina B y se utilizaron como portadores manitol e inulina y como tensioactivos se ensayaron el deoxicolato de sodio (SDC) y el laurilsulfato de sodio (SLS). La difracción de rayos X reveló que el fármaco en estudio se hallaba en estado amorfo en todas las dispersiones sólidas estudiadas. Se puede concluir que la velocidad de disolución del fármaco se incrementa significativamente en presencia de portador y tensioactivo.
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Godsey, Chad B. "Managing soil acidity in no-till production systems /." Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.
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Halldin, Stenlid Karl Joakim. "Quantum chemical predictions of localelectrophilicity (and Lewis acidity)." Thesis, KTH, Skolan för kemivetenskap (CHE), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146040.
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Solaiman, Abu Rayhan Mohammad. "Influence of soil acidity factors on Lotus rhizobia." Thesis, Queen's University Belfast, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356972.
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Meredith, Will. "Geochemical controls on the acidity of crude oils." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394720.
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Soleimani, Mostafa. "Thick film sensors for engine oil acidity detection." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/364525/.
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Engine oil condition monitoring has attracted considerable interests from industries and general public over the years due to its critical role in maintaining the performance and longevity of cars and industrial engines. Lubricants degrade during the course of operation and can be costly or detrimental to the engine if oil change intervals are not optimised. However, on-line robust monitoring for oils has been very challenging since oil degradation process is often complicated and influenced by a number of parameters, such as the operating temperature and contamination. Due to the complexity of the oil chemistry and their degradation processes, there have not been any commercially available on-line sensors for oil chemical property monitoring reported. Oil acidity is traditionally measured through potentiometric or photometric/colorimetric titration methods. Recent attempts at miniaturising infrared (IR) and chronopotentiometric (CP) sensors based on solid-state devices for acidity/alkalinity determination of oil have not been very successful since the CP technology suffers from sensitivity and stability issues and IR sensors are still bulky and adversely susceptible to the engine‟s harsh environment. This project, sponsored by Shell Global Solutions, aims to develop robust chemical sensors that can detect oil acidity due to oil degradation. The initial comprehensive literature review has identified that thick film (TF) sensor technology offers compact and low cost mass production solutions and have been proved to be robust with good reproducibility for aqueous solutions acidity measurements. Their feasibility in detecting oil acidity was thus investigated in this study and experimental work has been carried out to fabricate TF electrodes and evaluate them in a range of oils to explain their performance in detecting acid content. Based on their performance in aqueous solutions in previous studies, this study has investigated the performance of one type of TF working electrode (Ruthenium Oxide (RuO2)) combined with various TF reference electrodes in order to develop the most suitable electrodes for oils. To simulate oil ageing, a fully formulated engine oil and a base oil were oxidised under controlled conditions. Also, different amount of nitric acid was added to a fully formulated oil to simulate the oil acidity changes. Acid number (AN) of the oil samples was obtained using conventional titration methods and viscosity and conductivity of the oil samples were measured using laboratory-based equipment in order to validate TF sensor measurements and establish a relationship between different properties of oil samples during their degradation process. Temperature effects on thick film electrodes as well as their long-term stability and repeatability were also investigated. The results show that, for the first time, TF sensors respond to the acidity changes in all oil types tested and linear correlation between the TF responses and the AN was found in the oxidised oils within certain ranges at the tested temperatures (50 °C and 80 °C). TF sensors can detect oil acidity up to AN of 28 mgKOH/g. Although oil conductivity and viscosity were affected by the oil oxidation process, but no direct relationship was found between them and the TF responses. Based on the experimental results, sensing mechanisms of the TF electrodes in oils are proposed.
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Sun, Xiaojiao. "Single molecule studies of acidity in heterogeneous catalysts." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16423.
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Doctor of PhilosophyDepartment of Chemical Engineering
Keith L. Hohn
Amorphous silica-alumina is widely used as a solid acid catalyst for various reactions in oil refining and the petrochemical industry. The strength and the number of the acid sites in the material are most often believed to arise from the alumina atoms inserted into the silica lattice. The existence of the acidity distribution across the framework is a result of the local composition or the short-range interactions on the silica-alumina surface. Conventional techniques used to characterize silica-alumina provide effective information on the average acidity, but may not reflect the heterogeneity of surface acidity within the material. Recently, it is possible to study individual catalytic sites on solid catalysts by single molecule fluorescence microscopy with high time and space resolution. Fluorophores can be chosen that emit at different wavelengths depending on the properties of the local environment. By doping these fluorophores into a solid matrix at nanomolar concentrations, individual probe molecules can be imaged. Valuable information can be extracted by analyzing changes in the fluorescence spectrum of the guest molecules within a host matrix. In this research, silica-alumina thin films were studied with single molecule fluorescence microscopy. The samples were prepared by a sol-gel method and a wide-field fluorescence microscope was used to locate and characterize the fluorescent behaviors of pH sensitive probes. In mesoporous thin films, the ratio of the dye emission at two wavelengths provides an effective means to sense the effective pH of the microenvironment in which each molecule resides. The goal of this work was to develop methods to quantify the acidity of individual micro-environments in heterogeneous networks. Pure silica films treated with external phosphate solutions of different pH values were used to provide references of the fluorescence signals from individual dye molecules. SM emission data were obtained from mesoporous Al-Si films as a function of Al content in films ranging from 0% to 20% alumina. Histograms of the emission ratio revealed that films became more acidic with increasing Al content. The acidity on interior surfaces in zeolite pores was also of interest in this work. A microfluidic device was built to isolate the interior surface from the exterior surface. Some preliminary results showed the potential of using SM fluorescence method to study the acidic properties inside the pores of zeolite crystals.
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McGillen, Jessica Buono. "Mathematical modelling of metabolism and acidity in cancer." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:552f9ea8-ac6c-4413-9535-0318e855d85c.
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Human cancers exhibit the common phenotype of elevated glycolytic metabolism, which causes acidification of the tissue microenvironment and may facilitate tumour invasion. In this thesis, we use mathematical models to address a series of open problems underlying the glycolytic tumour phenotype and its attendant acidity. We first explore tissue-scale consequences of metabolically-derived acid. Incorporating more biological detail into a canonical model of acidity at the tumour-host interface, we extend the range of tumour behaviours captured by the modelling framework. We then carry out an asymptotic travelling wave analysis to express invasive tumour properties in terms of fundamental parameters, and find that interstitial gaps between an advancing tumour and retreating healthy tissue, characteristic of aggressive invasion and comprising a controversial feature of the original model, are less significant under our generalised formulation. Subsequently, we evaluate a potential role of lactate---historically assumed to be a passive byproduct of glycolytic metabolism---in a perfusion-dependent metabolic symbiosis that was recently proposed as a beneficial tumour behaviour. Upon developing a minimal model of dual glucose-lactate consumption in vivo and employing a multidimensional sensitivity analysis, we find that symbiosis may not be straightforwardly beneficial for our model tumour. Moreover, new in vitro experiments, carried out by an experimental collaborator, place U87 glioblastoma tumours in a weakly symbiotic parameter regime despite their clinical malignancy. These results suggest that intratumoural metabolic cooperation is unlikely to be an important role for lactate. Finally, we examine the complex pH regulation system that governs expulsion of metabolically derived acid loads across tumour cell membranes. This system differs from the healthy system by expression of only a few key proteins, yet its dynamics are non-intuitive in the crowded and poorly perfused in vivo environment. We systematically develop a model of tumour pH regulation, beginning with a single-cell scenario and progressing to a spheroid, within a Bayesian framework that incorporates information from in vitro data contributed by a second experimental collaborator. We predict that a net effect of pH regulation is a straightforward transmembrane pH gradient, but also that existing treatments are unable to disrupt the system strongly enough to cause tumour cell death. Taken together, our models help to elucidate previously unresolved features of glycolytic tumour metabolism, and illustrate the utility of a combined mathematical, statistical, and experimental approach for testing biological hypotheses. Opportunities for further investigation are discussed.
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Doherty, Sean Kevin. "Control of pH in chemical processes using artificial neural networks." Thesis, Liverpool John Moores University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247329.
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Moore, Jonathan D. "Synthetic studies on the Lewis acidity of diboron compounds." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396640.
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Pathak, Ravi Kant. "Acidity and sampling artifacts of PM2.5 in Hong Kong /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CENG%202004%20PATHAK.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 122-135). Also available in electronic version. Access restricted to campus users.
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Hadjifilippou, Irineos. "Characterizing the determinants of berry acidity in the grapevine." Master's thesis, ISA/UL, 2018. http://hdl.handle.net/10400.5/17938.
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Mestrado Vinifera Euromaster - Viticulture and Enology - Instituto Superior de AgronomiaGlobal warming is expected to be a major issue for grapevine productivity and sustainability in the long-term future. Major grapevine characteristics at berry level (physiological development and com-position) but also at the whole plant level (e.g. sugar accumulation, malic acid respiration, photosyn-thesis rate etc) are expected to be changed by elevated temperatures. In order to further decipher major berry physiology and development traits, data from two different experimental conditions and V.vinifera genotypes were used. The data set from experiment 1 was obtained from three genotypes (Merlot, G7 and G14 which are interspecific crossings of V. vinifera x V. rotundifolia, (macrovine) and possess the trait VDQA – “Vins de qualité à teneur réduite en alcool”, which produce wines with lower alcohol content. Plants were grown in open field conditions and berry development was mon-itored every week since early stages to over-ripeness providing a full berry development curve. In a second trial,76 genotypes were tested at two key stages, at green stage (just before ripening onset) and at ripe stage (maximum berry volume) to explore the diversity of primary metabolites and cations that exist in a progeny of microvine deriving from a cross. The progeny derived from a crossing of V3 microvine (female dwarf plant) with G14. Data analysis provided important information on berry development at limited number (8 berries maximum) and at large number (hundreds) scale for all parameters (glucose + fructose, tartartic acid,malic acid,potassium). In addition, complex berry pa-rameters such as titratable acidity were calculated on the basis of simple parameters (e.g. anions and cations). Finally, our results showed that the genetic variability of V. vinifera is potentially inter-esting to identify QTLs that can be used in breeding programs to develop new grapevine genotypes more suitable to climate change conditions
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Kidd, Petra Susan. "Aspects of soil acidity and their effect on plant growth." Thesis, University of Stirling, 1998. http://hdl.handle.net/1893/28841.
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The effects of low pH, AI, organic and phenolic acids on the growth of naturally occurring plant species were determined. The amelioration of Al toxicity by Si and organic acids was also investigated. Plants were grown from seeds in nutrient solutions simulating the ionic composition of soil solutions from five soil types ranging from acidic peat to calcareous soil. Soil solutions were extracted and analysed using centrifugation, with and without an immiscible displacent (1,1, I-trichloroethane), at both low (4000 rpm) and high speed (12000 rpm). Races of Holcus lanatus L. and Betula pendula Roth. from acidic soils (FM and SMM) grew better in low pH solutions (pH< 4.0). In acid-sensitive races Ca absorption was inhibited at low pH. Races of B.pendula from strongly to moderately acidic soils (FM, SMM, KP) were AI-tolerant and effectively excluded Al from shoots. Root elongation and leaf expansion were inhibited by all Al concentrations in races from calcareous soils (KR). Low concentrations of Al stimulated growth in some races of B.pendula (2 and 5 mg Al lˉ¹) and Anthoxanthum odoratum L. (1.3 and 2.7 mg Al lˉ¹). Al (25 and 35 mg lˉ¹) inhibited root and shoot growth in H.lanatus. Si (1500 and 2500 µM Si(OH)₄) addition to nutrient solutions alleviated AI-damage and restored nutrient uptake to values similar to those in plants grown with neither Al or Si. The ameliorative effects of Si were possibly achieved through AI/Si co-deposition in the root cell walls and maintenance of Golgi activity. Si at 1500 µM was beneficial but inhibited growth at 2500 µM. Al and hydroxyaluminosilicates at pH 5.6 were not toxic. Formic and tartaric acid ameliorated Al toxicity by reducing its availability. These organic acids on their own stimulated growth in H.lanatus and Deschampsia flexuosa (L.) Trin. Phenolic acids stimulated growth of H.lanatus in acidic solutions (pH 4.0) but not near-neutral solutions, particularly in races from soils high in phenolics. Addition of plant residue to acidic peats increased the growth of races from calcareous and acidic mineral soils.
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Amara, Holm. "Influence de l'aluminium et des sols acides sur la croissance du sapin de Douglas (Pseudotsuga menziesii, Mirb.) : rôle de la paroi dans les réponses au stress aluminique." Thesis, Limoges, 2020. http://aurore.unilim.fr/theses/nxfile/default/a59ed152-5cd0-4283-8056-5b8950a5f8d5/blobholder:0/2020LIMO0054.pdf.
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En Europe, les forêts de résineux sont très répandues et connues pour modifier les caractéristiques physicochimiques des sols forestiers, essentiellement en termes d’acidité. A des pH inférieurs à 5,5, l’aluminium naturellement présent dans le sol est solubilisé et se retrouve sous une forme mobile (Al3+),biodisponible et par conséquent toxique pour les plantes. Les travaux menés ont porté plus particulièrement sur le sapin de Douglas (Pseudotsuga menziesii), un conifère largement répandu en France et particulièrement dans la région Limousin. Plusieurs conditions de culture différentes (conditions contrôlées in vitro et conditions semi contrôlées sous serre sur sols forestiers acides et riches en Al potentiellement phytodisponible), ont été utilisées pour étudier, à des stades de développement différents (stade plantules et stade jeunes arbres) et pour des périodes d’exposition différentes (2 et 11 mois) les réponses du sapin de Douglas suite à son exposition à l’Al. Les résultats ont montré que la croissance du sapin de Douglas et sa nutrition minérale sont perturbées quand les plantules sont exposées à des concentrations élevées en Al (500 μM AlCl3 in vitro ; environ 1 mg Al.g-1 sol sec avec des pH d’environ 5 sur sols forestiers). Les symptômes de toxicité concernent essentiellement les racines qui accumulent la majorité de l’Al absorbé par la plante, l’aluminium étant préférentiellement localisé dans les parois cellulaires des tissus de la pointe racinaire. Face à la toxicitéaluminique, le sapin de Douglas développe différentes stratégies. D’une part, la caractérisation chimique de la paroi cellulaire a mis en évidence des modifications quantitatives et qualitatives dans la composition polysaccharidique de la paroi notamment en pectines (plus riches en acides alacturonique et moins ramifiées) suite à une régulation de l’activité pectine méthylestérase, et en hémicelluloses (plus riches en glucomannanes), suggérant un processus de rétention de l’Al dans les structures pariétales. D’autre part, au niveau intracellulaire, les résultats ont montré une stimulation de l’activité guaïacol peroxydase, une enzyme clé dans la réduction des symptômes du stress oxydatif induit dans des conditions de stress aluminique ainsi qu’une accumulation de la proline, potentiellement capable de chélater l’Al à l’intérieur de la cellule. Ainsi, le sapin de Douglas présente un seuil de tolérance à l’Al relativement élevé comparable à celui d’autres conifères. Cette tolérance met en jeu une stratégie à l’échelle cellulaire basée à la fois sur l’exclusion au niveau pariétal mais aussi de façon complémentaire sur des mécanismes de chélation au niveau intracellulaireIn Europe, softwood forests are very abundant and are characterized by an acidic soil profile. In these conditions, when the soil pH drops below 5.5, aluminum is present in soils in a soluble and bioavailable form Al3+. This work was carried out on Douglas fir (Pseudotsuga menziesii), a coniferous tree, widely distributed in France and particularly in the Limousin region. In this study we used different cultivation methods (in vitro cultures with controlled conditions, and semi-controlled conditions in greenhouse on naturally acidic forest soils rich in Al). Plants were analyzed at different stages of development (seedling stage and young tree stage) and for different exposure periods (2 and 11 months). The results have shown that the growth of Douglas fir and its mineral nutrition were disturbed when exposed to high Al concentrations (500 μM AlCl3 in vitro, and about 1 mg Al.g-1 at pH 5 on forest soils). We showed that the roots exhibited severe symptoms of toxicity and accumulated the majority of the Al within the cell wall. It has been shown that, to cope with aluminum toxicity, Douglas fir developed different strategies. On one hand, the chemical characterization of the cell wall revealed quantitative and qualitative modifications in the polysaccharidic composition of the wall, in particular pectins (harboring a higher galacturonic acid content with less ramification) following regulation of pectin methylesterase activity, and hemicelluloses (richer in glucomannans), suggesting a trapping process of Al in the cell wall structures. On the other hand, at the intracellular level, the results showed a stimulation of a key enzyme activity involved in the reduction of oxidative stress induced under aluminum stress, as well as an accumulation of proline, potentially capable of chelating Al inside the cell. Therefore, Douglas fir plantlets showed a relative high tolerance level to Al equivalent to other coniferous species which can be explained at the cellular level by an exclusion process involving retention by the cell wall but also a complexation process in the intracellular compartment
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Li, Yue. "Analysis of acidity in oil-based matrices by infrared spectroscopy." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86906.
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The feasibility of employing a portable variable filter array (VFA) infrared spectrometer equipped with a transmission flow cell to quantitatively analyze edible oils for free fatty acids (FFA) was evaluated. The approach to FFA determination was based on a previously reported FTIR method that involves the extraction of FFAs into methanol containing the base sodium hydrogen cyanamide (NaHNCN), which converts the FFAs to their salts, followed by measurement of the carboxylate absorbance at 1571 cm-1 in the spectrum of the methanol phase. The VFA IR spectrometer, which had a relatively weak pulsed IR source, was found to provide insufficient energy for accurate measurement of the carboxylate absorption superimposed on the strong methanol absorption at 1450 cm-1. By changing the extraction solvent to ethanol, good spectra and calibrations having an overall SD of ±0.07% FFA could be obtained. This work in turn led to the investigation of an ethanol solution of NaHNCN as a signal transduction reagent for Acid Number (AN) analysis in mineral-based lubricants, whereby total acidity would be measured by monitoring the decrease of the νC≡N absorption of NaHNCN at 2109 cm-1 as a result of the acid/base reaction. The equivalent response of the νC≡N band to strong inorganic acids and oleic acid demonstrated that NaHNCN, a somewhat weaker base than KOH, fully ionizes organic acids. Calibration standards were prepared by direct addition of oleic acid to the NaHNCN/ethanol solution, and a calibration equation for the determination of AN was obtained by a quadratic fit of the concentration data to the FTIR νC≡N absorbance data. The AN values obtained for ethanolic NaHNCN extracts of used oils by the FTIR method correlated well with those produced by titration of these extracts. Comparison between FTIR and titrimetric AN values (obtained by ASTM Standard Method D664-89) for a set of used oils spanning an AN range of 0.3-5 mg KOH/g showed a reasonably good linear relatiLa praticabilité d'utiliser un spectromètre infrarouge portatif comportant un filtre variable superposé à une barrette de détecteurs (dénommé un spectromètre VFA IR) et équipé d'une cellule d'écoulement de transmission pour analyser quantitativement les huiles de table pour leur teneur en acide gras libre (AGL) a été évaluée. L'approche à la détermination de la teneur en AGL a été basée sur une méthode précédemment élaborée sur un spectromètre infrarouge à transformée de Fourier (IRTF) qui implique l'extraction des AGL dans le méthanol contenant le cyanamide d'hydrogène de sodium, qui convertit les AGL en leurs sels, suivie de la mesure de l'absorbance de carboxylate à 1571 cm-1 dans le spectre de la phase de méthanol. L'Énergie fournie par la source pulsée relativement faible du spectromètre VFA IR s'est avérée insuffisante pour la mesure précise de l'absorption de carboxylate superposée à l'absorption forte de méthanol à 1450 cm-1. En changeant le dissolvant d'extraction en éthanol, de bons spectres et des courbes d'étalonnage ayant un écart-type global de ±0.07% AGL ont pu être obtenus. Ce travail a à son tour mené à la recherche sur l'utilisation d'une solution d'éthanol et de NaHNCN comme réactif de transduction de signal pour une analyse de nombre acide (NA) en huiles lubrifiantes à base minérale, par lequel l'acidité totale soit mesurée par la diminution de l'absorption νC≡N du NaHNCN à 2109 cm-1 comme résultat de la réaction acide-base. La réponse équivalente de l'absorption νC≡N aux acides inorganiques forts et à l'acide oléique a démontré que le NaHNCN, une base légèrement plus faible que le KOH, ionise entièrement les acides organiques. Des solutions étalons ont été préparées par l'addition directe de l'acide oléique à la solution de NaHNCN/éthanol, et une équation de calibrage pour la détermination de NA a été obtenue par un ajustement quadratique des données de co
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Lee, Sze Chung. "The acidity and basicity of the atmosphere in Hong Kong /." access abstract and table of contents access full-text, 2006. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-bch-b21471411a.pdf.
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Thesis (Ph.D.)--City University of Hong Kong, 2006."Submitted to Department of Biology and Chemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy" Includes bibliographical references.
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Martin, Natasha Kaleta. "Mathematical modelling of tumour acidity : buffer therapy and stromal effects." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526083.
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Mohd, Saupi Hanim Salami Binti. "Investigation of the acidity of Brønsted acids in ionic liquids." Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/58941.
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The Hammett acidity functions (H0) of mixtures of Brønsted acids-ionic liquids were measured using a 13C NMR probe and several UV-Vis probes. Successful measurements for all of the systems were demonstrated using the UV-Vis probes. A suitable probe was chosen and used to measure each mixture with the estimation of H0 values from the 13C NMR probe. The 13C NMR probe can be used to calculate the acidity of the mixtures approximately while the UV-Vis probe gave more precise results. The H0 of Brønsted acids-ionic liquids systems with different acids were successfully measured using the 13C NMR probe. Additional measurements were done using the UV-Vis probe to get a full acidity measurements for each system that cannot be measured using the 13C NMR probe. Finally, the effect on acidity of the cation of the ionic liquid was found to depend on the strength of the acid mixed with ionic liquids. There is no difference in the acidity of mixtures with a weak acid.
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Gao, Xiangming. "Novel electrochemical methods for acidity monitoring : theory, design and application." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289710.
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This thesis reports the design and development of novel voltammetric pH sensors for buffered, low-buffered and unbuffered media. pH sensors in stagnant and hydrodynamic environments were designed and developed for performing measurements using square wave voltammetry. Chapter 1 introduces the motivation of this project, the current development of electrochemical sensors, and the basic theory and techniques of electrochemistry concerned within the thesis. The existing development of carbon-based electrochemical sensors and the application of screen-printing technology in sensor fabrication are highlighted. Chapter 2 introduces the screen-printing technology and the fundamental methods of numerical simulation. In addition, reagents, equipment and software packages used in the thesis are listed in this chapter. In Chapter 3, a novel design of quinone derivative-based pH probes is presented for the application in stagnant weakly buffered media (< 1mM), based on previous studies of quinone compounds in buffered media. The results from the weakly buffered system is consistent with the results in buffered systems. To further extend the application of this design in unbuffered media, a numerical model of a pH-sensitive redox particle immobilised on an electrode was developed, which predicted that the accumulation of hydrogen ions near the electrode is the possible limiting factor for the performance of this design in unbuffered media. To develop a pH-monitoring technology for unbuffered media, Chapter 4 reports on the design, fabrication and testing of different electropolymerised-phenol derivative modified electrodes, which overcome the limitation of hydrogen ions accumulation. The results revealed that 2-(methylthio)phenol graphite resin electrodes have high accuracy (ca. 1% error) in unbuffered media, benchmarked by a commercial glass pH meter. This is the first detailed study on the v application of the economical and scalable technology in pH sensing in unbuffered environment. Chapter 5 presents a unique design of electrochemical pH sensors, free from the need to use a glass reference electrode. This design integrates a pH indicator and an internal reference electrode. Different designs of ferrocene screen-printed electrodes were tested as the internal reference electrode. The nafion-coated ferrocene screen-printed electrode showed stable peak potential in a wide pH range (pH 1 - 12) with good durability (stable in 500+ cycles of test). It was then cross connected with an alizarin electrode, forming the pH sensor free from a glass reference electrode. Chapter 6 describes novel designs of hydrodynamic pH sensors. The design of a microfluidic pH sensor modified by poly-sodium salicylate was firstly demonstrated. The sensor showed a Nernstian response in a wide pH range and, in hydrodynamic conditions, provided improved accuracy in unbuffered media compared to the stagnant state. For more convenient measurements, a novel rocking disc electrode was studied for pH sensing, modified with alizarin and poly-salicylic acid as pH indicators. The electrodes modified by both chemicals showed a Nernstian response in buffered media and the highest accuracy in unbuffered media was reached at 50 rpm.
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Lemishko, Tetiana. "Inelastic neutron scattering study of Brønsted acidity in LTA zeolite." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/119966.
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[ES] En esta tesis se realiza un estudio de acidez de zeolita LTA con la relación Si/Al 5 y 40 utilizando la técnica de dispersión inelástica de neutrones (INS) en combinación con otras tecnicas como la modelización computacional y la espectroscopía de resonancia magnética nuclear (RMN).
Las zeolitas son aluminosilicatos altamente cristalinos que forman parte de un grupo importante de los materiales funcionales. Las zeolitas son extremadamente útiles como catalizadores para muchas reacciones importantes con moléculas orgánicas. Las más importantes son craqueo, isomerización y síntesis de hidrocarburos.
Las propiedades catalíticas de una zeolita dependen principalmente de su acidez y ésta depende de tres factores: el número totál de los sitios ácidos, sus fuerzas individuales y su localización individual, estando estos tres factores relacionados. Los parámetros geométricos definidos por localización de los sitios ácidos (es decir, la longitud y los ángulos de enlaces entre los átomos alrededor del sitio ácido) contribuyen de una manera importante a la fuerza ácida.
En la literatura hay muchos trabajos de estudios de acidez en zeolita utilizando la espectrometría infrarroja (IR), sin embargo, con esta técnica es imposible medir las vibraciones de flexión (bending modes, 200-1200 cm-1), las bandas más sensibles al entorno local de los centros ácidos, ya que estas bandas se superponen con las bandas de vibración de la red de zeolite (300-1800 cm-1).
En esta tesis se realiza un estudio de acidez utilizando la tecnica de INS, que nos permite medir principalmente los modos de vibración de los átomos de H y también nos permite medir todas las bandas de vibración (incluido el bending).
Este estudio muestra que la combinación de la alta calidad de las muestras y la sensibilidad del instrumento utilizado permite detectar con alta precisión los sitios ácidos y obtener la información sobre su posición que a su vez nos perimte obtener la posición de los átomos de Al. Con el fin de interpretar los espectros INS se ha realizado un estudio computacional (cálculos ab-initio) con el objetivo de comparar los espectros cálculados con los resultados experimentales y definir el modelo que reproduce la posición mas probable de los centros ácidos en la muestra.[CAT] En aquesta tesi es realitza un estudi d'acidesa de zeolita LTA amb la relació Si / Al 5 i 40 utilitzant la tècnica de dispersió inelastica de neutrons (INS) en combinació d'altres tècniques com la modelització computacional i la espectroscòpia de ressonància magnètica nuclear (RMN ). Les zeolites són aluminosilicats altament cristal·lins que formen part d'un grup important dels materials funcionals. Les zeolites són extremadament útils com a catalitzadors per a moltes reaccions importants amb molècules orgàniques. Les més importants són craqueig, isomerització i síntesi d'hidrocarburs. Les propietats catalítiques d'una zeolita depenen principalment de la seva acidesa i aquesta depèn de tres factors: el nombre total dels llocs àcids, les seves forces individuals i la seva localització individual, estant aquests tres factors relacionats. Els paràmetres geomètrics definits per localització dels llocs àcids (és a dir, la longitud i els angles d'enllaços entre els àtoms al voltant del lloc àcid) contribueixen d'una manera important a la força àcida. En literatura hi ha molts treballs d'estudis d'acidesa en zeolita utilitzant l'espectrometria infraroja (IR), però és impossible mesurar les vibracions de flexió (bending modes, 200-1200 cm-1) amb aquesta tècnica ja que aquestes bandes es superposen amb les bandes de vibració de la xarxa de zeolita (300-1800 cm-1). La tècnica de dispersió inelastica de neutrons (Inelastic neutron scattering) ha estat utilitzada per estudiar l'acidesa de la zeolita LTA amb diferents relacions Si / Al (per tant diferents c.ontinguts de H en la zeolita). En aquesta tesi es realitza un estudi d'acidesa utilitzant la tècnica de INS, que ens permet mesurar principalment els modes de vibració dels àtoms d'H i també ens permet mesurar totes les bandes de vibració (inclòs el bending). Aquest estudi mostra que la combinació de l'alta qualitat de les mostres i la sensibilitat del instrument utilitzat permet detectar amb alta precisió els llocs àcids i obtenir la informació sobre la seva posició que en el seu lloc ens perimte obtenir la posició d'Al. Per tal de interpretar els espectres INS s'ha realitzat un estudi computacional (càlculs ab-initio) amb la comparació dels espectres calculats amb els resultats experimentals.
[EN] This thesis is dedicated to the study of acidity of LTA zeolites with Si/Al ratios 5 and 40 by using the technique of inelastic neutron scattering (INS) in combination with other techniques such as computational modeling and nuclear magnetic resonance (NMR) spectroscopy. Zeolites are crystalline and microporous aluminosilicates which form one of the most important groups of functional materials. Zeolites are widely used as solid acid catalysts for the wide range of important processes regarding organic molecules. The most important are cracking, isomerization reaction and synthesis of hydrocarbons. The catalytic properties of a zeolite depend strongly on its acidity, and this in turns depends on: the total number of acid sites, their individual strength, and their individual location. These three factors are strongly correlated. Geometric parameters that are defined by the location of the acid site (i.e., bond angles and lengths around the acid site) make a remarkable contribution to the acid strength. There are several studies, found in literatures, typically done by Infrared (IR) or Nuclear magnetic resonance (NMR) technique and dedicated to acidity of zeolites. However, the hydrogen bending modes (200-1200 cm-1), which are found to be more sensitive to local environment, cannot be observed by this technique, since these bands overlap with strong bands of the vibrations of zeolitic framework (300-1800 cm-1). INS technique used in this study allows to detect the bands of vibrations of hydrogen atoms in zeolites (including bending modes). Moreover, this study shows that the combination of an extremely high quality of the samples and the sensitivity of the instrument allows to detect with high precision the acid sites of both high-silica and low-silica zeolites and obtain information about their position. This in its turn gives us the possibility to obtain the aluminium location in zeolites. In order to fully understand the INS spectra we performed ab-initio calculations that allow to interpret the experimental bands and choose a structural model that reproduces the probable location of acid sites in the sample.
Lemishko, T. (2019). Inelastic neutron scattering study of Brønsted acidity in LTA zeolite [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/119966
TESIS
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Binti, Shafiee @. Ismail Nor Sahida. "Carboxylic acid composition and acidity in crude oils and bitumen." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2763.
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As the world’s demand for crude oil increases and the amount of conventional reserves decline, the proportion of high acidity oils being produced is increasing, but this acidity can cause corrosion problems during production and refining. Total Acid Number (TAN) values are often used to predict whether a crude oil may cause corrosion problems and thus affect the value of the oil, although the relationship between TAN and the organic acid composition of oils is not fully understood. This thesis investigate the types of acidic compounds that contribute to acidity in crude oils and the geochemical factors that influence the compositions and concentrations of these compound classes in a suite of oils and bitumens from a variety of different locations, including the North Sea, Venezuela, Canada and California. This work in this thesis includes the development of a modified ASTM D664 titrimetric assay method for measuring acid numbers on small samples of heavy crude oil, core extracts and also isolated maltene and asphaltene fractions. The TAN values in the crude oils and their fractions analysed ranges from 0.04 to 21.24 (mg KOH/g). The results show that in general, the maltene fraction contributes most to the acidity in crude oils, however in some samples a large proportion of the oil TAN is contributed by the asphaltenes, even though they are quantitatively a small percentage of the oil. The geological reasons for the occurrence of oils with these highly acidic asphaltenes are not currently known. The analysis of isolated carboxylic acid fractions from ten oils of different origins, including those from different source depositional environments, levels of biodegradation and thermal maturity, using a gas chromatographic method, showed that the concentrations of total carboxylic acids corresponded well with TAN and biodegradation, indicating that these acidic compounds may be a major control on the acidity in crude oils and that the concentration of these were in turn controlled by the extent of biodegradation. ii Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) was used to characterise a set of North Sea crude oils with TAN values ranging from 0.11 to 7.58 (mg KOH/g oil). This showed that the O2 compound class (assumed to be mainly carboxylic acid “COOH” species) appeared as the dominant compound class under the analytical conditions used, with a strong correlation (r2 = 0.989) of the O2/N ratio with the TAN values of the oils, indicating that these compounds may control the TAN in these samples. This observation also applied to their maltene and asphaltene fractions. The dominant acid species in the high acidity North Sea oils, maltenes and asphaltenes were three and four ringed naphthenic acids. As the TAN of the oils increased, the double bond equivalent (DBE) distributions shifted to higher values indicating that their molecular structures became more highly aromatic. Fourier Transform Infrared (FTIR) spectroscopy potentially offers a much more rapid analysis of acids in oils compared to the ASTM D664 method. This study included the development of a rapid method for the determination of TAN by FTIR spectroscopy of conventional and heavy crude oils using single bounce attenuated total reflectance (ATR) and multi bounce horizontal HATR accessories. Using multivariate data analysis software, a multivariate model that correlates infrared spectra with the TAN value was developed using carbonyl (C=O) absorption bands ranging from 1770 to1650 cm-1. It was found that the correlation of FTIR measured TAN versus ASTM D664 measurements, obtained by multi bounce HATR (r2 = 0.943) were better than correlations produced by single bounce ATR (r2 = 0.812). Based on these findings, the measurement of oil acidity and TAN using FTIR is simpler and faster and also allows the analysis of small sample sizes and avoids other problematic issues such as the fouling of electrodes that can be experienced using the ASTM D664 standard method.
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Sood, Dhiraj S. "The role of strongly acidic media on the formylation of toluene." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/10090.
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Kitto, Abdul-Massih N. "Physico-chemical investigation of acidic and basic gaseous and particulate pollutants in the troposphere." Thesis, University of Essex, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292093.
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Potts, Malcolm. "Desiccation tolerance." Thesis, Durham University, 1995. http://etheses.dur.ac.uk/9528/.
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Despite the fundamental significance of desiccation in determining the distributions and activities of living organisms, there is virtually no insight as to the state of the cytoplasm of an air-dried, or even a wet, cell. In bacterial cells that have been subjected to air-drying the evaporation of free cytoplasmic water (Vf) can be instantaneous, and an equilibrium between cell-bound water (VQ and the environmental water (vapor) potential (Ψwv)) may be achieved very rapidly. In the air-dried state some bacteria survive only for seconds, others can tolerate desiccation for thousands, perhaps for millions, of years. The means by which certain cells, the anhydrobiotes, overcome and then tolerate acute water deficit remains one of the most intractable problems in cell biology. One such anhydrobiote, the cyanobacterium Nostoc commune, is cosmopolitan, its colonies form visually-conspicuous and abundant growths in situ, and it constitutes an ecologically-significant component of terrestial nitrogen-fixing communities. The cyanobacteria are phylogenetically-significant organisms that provide model systems for the study of a broad range of problems in cell biology. The studies described in this thesis established the molecular ecology and cell biology of Nostoc commune, and they provide a chronicle of the development of this microorganism as the prokaryotic model for the anhydrobiotic cell. In the design of experiments to investigate this problem the bias was, and remains, this: to understand desiccation tolerance, understand an organism that tolerates desiccation. The thesis documents an investigation into the consequences of acute cell-water deficit and the cellular basis for desiccation tolerance. An eclectic approach has been adopted to study desiccation tolerance and it includes the application of techniques of cell biology, biochemistry, microbiology, molecular biology, structural biology and biophysics.
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Shehabi, Murtaza Kaium. "Cost tolerance optimization for piecewise continuous cost tolerance functions." Ohio : Ohio University, 2002. http://www.ohiolink.edu/etd/view.cgi?ohiou1174937670.
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Söderman, Fredrik. "Comparative Population Ecology in Moor Frogs with Particular Reference to Acidity." Doctoral thesis, Uppsala University, Department of Ecology and Evolution, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6828.
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This thesis is an attempt to describe how different environmental factors influence life history traits in different populations, sexes and developmental stages in the moor frog, Rana arvalis. The studied populations are located along 1100 km latitudinal gradient, with pH varying between 4.0 and 8.5. I have used data from both natural populations and common garden experiments.
Reproducing moor frogs were larger and older at high latitudes, indicating a selective advantage of large size at high latitudes and/or earlier reproduction at low latitudes. When controlling for age I found that frogs were older and smaller at low pH, which may be a result of a reduced growth rate due to acid stress. The both sexes respond differently to different environments, with the lowest sexual dimorphism in body size found in the acid environments. This is possibly caused by a trade-off between growth and reproduction. Being large is considered to be advantageous, in females due to increased fecundity, and in males due to higher ability to compete for mates, while the cost of high growth is a reduced possibility to survive until the next mating season. Moor frog embryos originating from an acid population survived better under acid stress than embryos from a neutral population. Using quantitative genetic techniques I found strong maternal effects and small additive genetic variation for the traits in acid and non acid populations. The variation in acid stress tolerance owed largely to non-genetic effects. Females from acid localities lay larger eggs, which probably improves the performance of tadpoles under acid conditions. The trade-off between egg size and fecundity was stronger in acid populations indicating that females in acid populations reduced fecundity to increase offspring size. Finally, frogs from acidified environments were more asymmetric in skeletal traits further indicating the developmental stress created by acidification.
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Fölster, Jens. "Catchment hydrochemical processes controlling acidity and nitrogen in forest stream water /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6074-3.pdf.
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Stone, Carol E. "Rhizobium strain selection by white clover under conditions of acidity stress." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335442.
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Bishop, Kevin Harold. "Episodic increases in stream acidity, catchment flow pathways and hydrograph separation." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239601.
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Brooks, Jenkins Gareth. "Amelioration of acidity in fresh waters : individual to ecosystem level responses." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8981.
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The extensive acidification of fresh waters across Europe and North America during the 20th century led to extensive and widespread loss of species, which fundamentally changed the structure of resident communities. While attempts to limit or halt acidifying emissions have been successful in reversing the chemical consequences of acidification, any corresponding biological recovery has been patchy at best. The main aim of this thesis was to investigate potential ecological constraints on this biological recovery, ranging from interactions between individuals to ecosystem-level processes, using a model stream system that has been extensively studied for over 40 years. I used a combination of long-term survey data and experiments, both in the field and the laboratory, to provide evidence that the lag in recovery of acidified aquatic communities is due to intrinsic resistance to re-colonisation by acid-sensitive species, as a result of both direct and indirect interactions between predators and prey. However, there is also evidence of recovery at an ecosystem level, with rates of microbial decomposition increasing – a key link in the transfer of energy to higher trophic levels, which could be facilitating population increases in large-bodied predators. These findings increase our understanding of the drivers which govern the structure and function of ecological networks in response to an important climatic stressor. This is especially relevant given the rapid industrialisation of countries such as India and China, which could well soon experience anthropogenic acidification on a significant scale.
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Weber, Reinier Willem. "The characterization and elimination of the external acidity of ZSM-5." Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/18301.
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The zeolite ZSM-5 is well-known for its unique intersecting channel system. This channel system has a great bearing on the shape-selective properties and the long life-times of ZSM-5. In this study, ZSM-5 was modified in various ways to eliminate the external acidity of the catalyst to further improve these properties, and the success and effects of these modifications were investigated primarily using temperature programmed desorption techniques. The internal surface of ZSM-5, a medium pore zeolite, plays a major role in the shape selective properties of this catalyst, due to the diffusional restrictions imposed by the channel system on bulky molecules. Even though the number of acid sites on the external surface is small compared to the total number of acid sites, these easily accessible and non-shape selective acid sites may provide a high turnover rate for non-shape selective reactions. Furthermore, the main cause of deactivation of ZSM-5 is thought to be the formation of polyaromatic molecules on the external surface, which block access to the channels of the catalyst.
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Wood, Douglas M. (Douglas Michael). "Discriminative Stimulus Properties of Cocaine: Tolerance and Cross-Tolerance Characteristics." Thesis, North Texas State University, 1985. https://digital.library.unt.edu/ark:/67531/metadc500536/.
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Rats were trained to discriminate an injection of cocaine, 5.0 mg/kg, from an injection of saline, using a two-lever choice paradigm: one lever was correct after cocaine injection, the other lever was correct after a saline injection. After training, cocaine and methamphetamine were generalized to the cocaine lever, but phenethylamine (PEA) was only partially generalized. Cocaine was injected every 8 hrs, 20.0 mg/kg, and the discriminability of 5.0 mg/kg was tested every other day. Redetermination of the cocaine generalization curve after 6 days of chronic administration showed a shift to the right, from an ED50 of 4.1 mg/kg in the pre-chronic condition to 10.0 mg/kg. Tolerance did not develop to the behavioral effects of cocaine, measured by time to the first reinforcement and response rate. There was cross-tolerance to methamphetamine; however, no evidence for cross-tolerance to PEA was obtained. Following the acquisition of tolerance, chronic administration of cocaine was terminated, and the discriminability of 5.0 mg/kg was tested every other day for loss of tolerance. After 8 days the ED50 returned to 5.0 mg/kg.
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Wade, Andrew John. "Assessment and modelling of water chemistry in a large catchment, River Dee, NE Scotland." Thesis, University of Aberdeen, 1999. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU133417.
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This thesis describes the water chemistry of the River Dee and its tributaries, and the potential water chemistry changes that may occur under acid deposition and land use change scenarios. Historic water quality and flow records were collated and supplemented with new water chemistry data. These data were analysed in relation to catchment geography and river flow using both mathematical modelling and novel, GIS based techniques. This analysis established the importance of diffuse inputs and highlighted differences between upland and lowland regions in the catchment. In headwater streams, different geological types create hydrochemical source areas that strongly influence stream chemistry whilst in lowland tributaries, agricultural sources are particularly important. In the upland region most major ions were diluted as flows increased, further emphasizing the influence of deeper geological sources on baseflow chemistry, but showing soilwater controls on stormflow composition. The headwaters, which drain predominantly acid rocks, are presently oligotrophic but threatened by the impact of acid deposition and land use change (re-afforestation). In some of the lowland tributaries, increased NO3-N concentrations have resulted from more intensive land management. The potential impacts of acid deposition and land use change were simulated in both upland and lowland catchments by considering existing and new models within a Functional Unit Network. For upland regions this consisted of developing a new, two component hydrochemical mixing model to simulate the spatial and flow-related variations in streamwater acidity. The mixing model was based on End Member Mixing Analysis (EMMA), and site specific end members (alkalinity and Ca) could be predicted from emergent catchment characteristics (soil and land use) using linear regression.
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Crockford, Andrew. "Deciphering tetraploid tolerance." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1475158/.
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Chromosomal instability and aneuploidy are common features of human malignancies, which fuel genetic heterogeneity and can lead to inaccurate diagnosis and treatment failure. Tetraploidy has been shown as an intermediate of aneuploidy and, thus, understanding the molecular mechanisms governing tetraploid tolerance is of great importance. A frequent tolerance mechanism observed in experimental systems and human tumours is loss of TP53, highlighting its central role in the tetraploidy checkpoint. However, despite this association, more than half of genome-doubled tumours are TP53 wild-type. The aim of this project was to understand how tetraploid cells could tolerate the polyploidy phenotype with a functional p53/p21 axis. Firstly, tetraploidy tolerance was investigated in an isogenic HCT-116 diploid and tetraploid system. The HCT-116 tetraploids showed functional p53, in response to DNA damage and segregation error induction, while also displayed elevated basal level of both proteins. Despite this, the tetraploid clones could proliferate and showed no evidence of cell cycle arrest, suggesting the p53/p21 tetraploidy checkpoint response had been overridden. Quantitative proteomics revealed cyclin D1 overexpression in the tetraploid clones. As cyclin D1 can sequester p21, their relationship was investigated and validated in the HCT-116 system. To further test if elevated cyclin D1 could affect tolerance, cytokinesis failure was pharmacologically induced in RPE cells, where cyclin D1 overexpression promoted tetraploidy tolerance across multiple assays. In addition, bioinformatics analysis revealed that D-type cyclins were overexpressed in TP53, CDKN1A and RB1 wild-type, genome-doubled testicular germ cell tumours (TGCT). These findings indicate that D-type cyclin overexpression can provide tetraploidy tolerance in vitro and may be implicated in TGCT genome-doubling and pathogenesis.
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Mpoeleng, Dimane. "From crash tolerance to Byzantine tolerance : fail signalling dependable distributed systems." Thesis, University of Newcastle Upon Tyne, 2005. http://hdl.handle.net/10443/2142.
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Many fault-tolerant group communication middleware systems have been implemented assuming crash failure semantics. While this assumption is not unreasonable, it becomes hard to justify when applications are required to meet high reliability requirements and are built using commercial off the shelf (COTS) components. This thesis implements new techniques to deal with Byzantine faults in a distributed group communication system. This thesis proposes a technique by which a process is duplicated into two replicas such that the process is turned into a self-checking pair with the two replicas communicating synchronously over a reliable network, but two different replicas from different processes can be connected asynchronously. The proposed approach is based on the replicas obeying state machine replication (SMR). SMR is utilised to assure signal-on-failure (fail-signal) semantics. One or both of the two replicas always issues a signal to other entities whenever there is a failure between and within the entities. This way, dependable activities such as group member failure detection, liveliness and security are removed from the upper layer of group communication service down to the two-replica pairs. With most of failure detection and security activities confined between the two replicas, semantics of a group communication are simplified and the number of phases and rounds of group communication protocols is reduced. The thesis demonstrates the fail-signalling concept by converting a group communication system member, through duplication of each group member, into a self checking pair. Security is augmented to the replicas' fail signalling capabilities to tolerate even more serious Byzantine faults. Performance results of the traditional group communication system are compared with results of a group system with duplicated fail signalling group members. The thesis has proven that the fail signalling group communication has the advantage of detecting failures faster without suspicions and that resulted in better group communication semantics, better dealing with member failures and faster formation of new group views.
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Divekar, Rohit Dilip Zaghouani Habib. "Two aspects of peripheral immune tolerance systemic and mucosal tolerance mechanisms /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/6868.
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The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on April 1, 2010). Vita. Thesis advisor: Habib Zaghouani. "May 2008" Includes bibliographical references.
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Séron, Fabienne. "L'economie psychosomatique des transplantes renaux - une tolerance immunologique, une tolerance psychologique ?" Paris 5, 1987. http://www.theses.fr/1987PA05H067.
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Dans cette recherche, nous formulons une question fondamentale : quels sont les facteurs intervenant dans la reussite d'une transplantation renale ? une double tolerance (immunologique et psychologique) concourt au maintien de l'equilibre homeostatique ou de l'economie psychosomatique, toujours singuliere selon les sujets. Nous postulons l'existence d'un lien particulier unissant l'organisation mentale d'un greffe a la valeur fonctionnelle du greffon. Des situations traumatiques precipitent frequemment la survenue d'une maladie. La maniere de vivre et d'elaborer celle-ci s'avere bien specifique, selon les caracteristiques d'organisation mentale. Les sujets porteurs d'une meme affection somatique ne presentent pas les memes particularites de fonctionnement mental. De multiples parametres en interaction favorisent ou non la tolerance immunologique et psychologique du greffon : la capacite de developper une symptomatologie mentale assure une certaine protection du corps. La richesse fantasmatique, la possibilite de negocier les conflits et de tolerer une angoisse determinent en partie la tolerance immunologique. Nous soulignons les apports fondamentaux de l'environnement exterieur pour certains sujets, tres carences sur le plan de l'organisation mentale. Leur equilibre psychosomatique se maintient a la faveur des contre-investissements externes (medicaux, chimiotherapiques, relationnels). Ceci exerce une fonction pare-excitante prenant le relais des systemes defensifs defaillants. L'homeostasie globale de ces sujets depend de la configuration d'un cadre de vie privilegie. Pour les patients plutot bien mentalises, la greffe realise une situation de crise psychologique commandant : l'exacerbation d'angoisses, de defenses et de conflits specifiques selon l'histoire ou le developpement libidinal de chacun. Ces manifestations symptomatiques ou defensives favorisent la "metabolisation" et l'elaboration mentale de la transplantation renale. La greffe permet alors l'installation d'un relatif palier de reorganisation et une reprise evolutive somatique comme psychiqueIn this paper, we have elaborated a fundamental question : what are the factors which contribute towards the success of a kidney transplant ? a dual tolerance (immunological and psychological) works towards maintaining homeostatic balance or "psychosomatic economy", always specific to each subject. We have suggested that there is a precise relationship between the mental organization of a transplant patient and the functional value of the transplanted organ itself. Traumatic situations frequently accelerate the outbreak of an illness. The way it is lived and mentally elaborated is very specific, depending on mental characteristics. Subjects who suffer from the same somatic trouble do not present the same mental characteristics. Numerous interactive parameters either encourage or do not encourage the immunological and psychological tolerance of the transplanted organ : the ability to develop a mental symptomatology ensures a certain protection of the body. The abundance of fantasies, the ability to overcome conflicts and to tolerate anxiety, partly determine immunological tolerance. We have emphasized the fundamental contribution of the external environment in the case of subjects who are very deficients as regards their mental organization. They maintain their psychosomatic balance on account of an external counteraction (medical, chemotherapic, relational). This has the function of preventing excessive excitation, thus compensating for deficient defense systems. The global homeostasis of such subjects depends on the configuration of privileged life conditions. In patients with rather good mental organization, the transplant creates a situation of psychological crisis, which leads to the exacerbation of anxieties, defences and specific conflicts depending on individual history or libido evolution. Such symptomatic or defensive manifestations encourage the mental metabolization and elaboration of the kidney transplant. The transplant thus allows the setting up of a relative stage of re-organization and a somatic, as well as psychic, evolutive re-start
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Wu, Xianchun. "Acidity and catalytic activity of zeolite catalysts bound with silica and alumina." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/561.
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Zeolites ZSM-5 (SiO2/Al2O3=30~280) and Y(SiO2/Al2O3=5.2~80) are bound with silica gel (Ludox HS-40 and Ludox AS-40) and alumina (γ- Al2O3 and boehmite) by different binding methods, namely, gel-mixing, powder-mixing and powder-wet-mixing methods. The acidities of the bound catalysts and the zeolite powder are determined by NH3-TPD and FTIR. The textures of these catalysts are analyzed on a BET machine with nitrogen as a probe molecule. The micropore surface area and micropore volume are determined by t-plot method. Micropore volume distribution is determined by Horvath-Kawazoe approach with a cylindrical pore model. Mesopore volume distribution is determined by BJH method from the nitrogen desorption isotherm. Silica from the binder may react with extra-framework alumina in zeolites to form a new protonic acid. SiO2-bound catalysts have less strong acidity, Bronsted acidity and Lewis acidity than the zeolite powder. Also, the strength of strong acid sites of the zeolites is reduced when silica is embedded. Micropore surface area and micropore volume are reduced by about 19% and 18%, respectively, indicating some micropores of ZSM-5 are blocked on binding with silica. SiO2-bound ZSM-5 catalysts have less catalytic activity for butane transformation (cracking and disproportionation) and ethylene oligomerization than ZSM-5 powder. When alumina is used as a binder, both the total acid sites and Lewis acid sites are increased. Micropore surface area and micropore volume of ZSM-5 powder are reduced by 26% and 23%, respectively, indicating some micropores of ZSM-5 are blocked by the alumina binder. Alumina-bound catalysts showed a lower activity for butane transformation and ethylene oligomerization than ZSM-5 powder. Alkaline metals content in the binder is a crucial factor that influences the acidity of a bound catalyst. The metal cations neutralize more selectively Bronsted acid sites than Lewis acid sites. Alkaline metal cations in the binder and micropore blockage cause the bound catalysts to have a lower catalytic activity than the zeolite powder.
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Islam, Mohammed Anowarul. "Responses of accessions of Austrodanthonia spp. to factors associated with soil acidity." University of Sydney. Food and Natural Resources, 2002. http://hdl.handle.net/2123/502.
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Pasture plants already adapted to acidic soil conditions are required as part of an integrated approach (with lime amelioration) to managing acid soils on the Tablelands of New South Wales, Australia. The objective of this thesis is to evaluate the usefulness of Austrodanthonia species for this purpose. The material evaluated in this study was collected during a previous survey of the distribution of Austrodanthonia on the Central, Southern and Monaro Tablelands of New South Wales. It was hypothesised that the genus Austrodanthonia has a wide range of tolerance to acid soils. A series of experiments that provided information on the growth and physiology of Austrodanthonia in relation to soil acidity, with a view to the identification and eventual domestication of the most promising plant material have been conducted through pot, hydroponics and field investigations. Firstly, soils were acidified or limed to obtain a range of soil pH and Al concentrations. This experiment showed that adding aluminium sulfate and calcium carbonate followed by washing excess salts with water is a simple, rapid and convenient method for adjusting soil pH for pot experiments. The pH of the amended soils remained relatively unchanged eight months after treatment. The experimental set-up also resulted in a wide range of soluble Al (2-52 mg/kg) across the soils. The relative Al-tolerance of 183 accessions from 15 Austrodanthonia species was tested in a pot experiment using a range of soil pH. Emergence, survival and growth of all accessions were drastically reduced by high soil acidity (pH 3.9, P < 0.001). About 11% of plants emerged at pH 3.9, whereas at pH 4.4 and 5.3, ~72% of plants emerged. Accessions exhibited large variation within and between species in their tolerance to soil acidity. From the species/accessions tested, 49 accessions from eight species were selected for further study (on the basis of being more acid tolerant). Hydroponic experiments conducted in the glasshouse evaluated: (i) formulation of nutrient solution with a stable pH, (ii) effectiveness of the formulation using tap water and deionised water and (iii) estimation of free ion activities of Al and Mn in the nutrient solution and their effects on Austrodanthonia growth. These experiments showed that a NO3-N/NH4-N ratio of 9:4 is the most appropriate ratio to obtain a stable pH 4.0 without affecting plant growth; that there was little difference between tap water and deionised water on the ionic effects of Al and Mn, and plant-size did not play a role on accession survival and that accessions of Austrodanthonia could grow well within a wide range of pH (3.5-5.5), Al (50-250 �M) and Mn (100-2000 �M). Growth of Austrodanthonia accessions declined under high acidity (pH < 3.5) and Al (300 �M), but tolerated high concentrations of Mn (2000 �M). Root-tips stained with hematoxylin grouped accessions in a similar way to the pot and hydroponic experiments for most of the accessions tested. The intensity of root staining with hematoxylin and the differential distribution of Al in the shoots and roots provided an indication that different tolerance mechanisms may be involved with Austrodanthonia accessions. It appears that both exclusion and internal mechanisms may operate for Al- and Mn-tolerance. A field experiment was conducted at Carcoar (33037�S, 149013�E, elevation 800 m) using gradients in soil pH and Al available on-site to grow selected accessions of Austrodanthonia. The accessions exhibited a range of responses to soil acidity. The accession responses to acidity from the pot and hydroponic experiments were similar to those obtained in the field, especially where Al was present as a low Al-challenge. Overall, this study shows that Austrodanthonia exhibits a wide range of acid tolerance between species and accessions within species. Among the species tested, A. duttoniana and A. fulva appeared to have the greatest commercial potential, because of their productivity and acid tolerance. The variability that exists in the accessions may be exploitable in breeding and selection programs for improved cultivars.
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Andrews, Marilyn Mockus 1958. "Characterization of the surface acidity of passivated iron particles by flow microcalorimetry." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276614.
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The characteristics of passivated iron particles have been examined with flow microcalorimetry to determine the acidic nature of the surface sites. The molar heat of adsorption of pyridine from hexane was measured with a FMC and a differential refractive index detector, at 23 and 40°C. The adsorption data were found to obey the assumptions of the Freundlich isotherm. The adsorption densities at different temperatures were used to calculate the isosteric heat of adsorption. The molar heat of adsorption of triethylamine from hexane was also measured and combined with the data for pyridine in order to calculate the Drago constants for the iron particles. A static adsorption method was used for the adsorption of pyridine from hexane onto the iron particles, for comparison with the dynamic method. The heat of wetting for the iron particles, with hexane, has also been measured. The iron particles were examined with X-ray diffraction. Mossbauer spectroscopy, XPS, SEM, TEM, and electrophoresis to characterize the surface layer. These techniques have revealed that the iron particles are coated with ferric oxide and this surface is amphoteric in aqueous solutions.
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Pasteris, Daniel R. "A continuous method for measurement of pH and acidity in ice cores." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1464455.
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Smith, Carol M. S. "Assessment of critical loads of acidity for selected U.K. upland organic soils." Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU555089.
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The use of critical loads of acidity to quantify damage to sensitive components of terrestrial and aquatic ecosystems has developed rapidly over the last decade. While much work has focused on defining damage to forested ecosystems, surface waters and groundwaters, there has been little work done on defining critical loads of acidity for ombrotrophic and minerotrophic peat. This thesis presents a modelling approach to quantify damage to ombrotrophic peat ecosystems, since such damage can result in a decline in both surface water quality and the ability of peat to act as an absorbent to aerial pollutants. Initial investigations were concerned with the factors which could be included in investigations of critical loads of N and acidity to the surface organic horizons of forest and moorland soils. The modelling approach was then developed from a series of laboratory-based simulation experiments to investigate the effect of contents of H&'43 , Ca2&'43 and Mg2&'43 in rainfall upon the chemistry of the peat ion exchange complex. The basic tenet of the modelling approach was that ion exchange equilibria for peat is rapid, mineral input to the surface of ombrotrophic peat from mineral weathering is negligible and that atmospheric inputs of wet and dry deposition will dominate the peat chemistry. These simulation experiments provided peat pH values resulting from equilibration with the simulated rainfall. By combining these with databases of atmospheric depositon for the U.K., critical loads of acidity and the present day peat pH were calculated and mapped. The critical load values for peat thus obtained were incorporated in the U.K. Critical Load mapping program, which was used to support the on-going European negotiations of emission reduction within the United Nations Convention on Long-range Transboundary Air Pollution (U.N. E.C.E. C.L.T.A.P.).
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Hasegawa, Makoto. "Studies on Efficient Reactions Using π-Lewis Acidity of Cationic Metalloporphyrin Complexes." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225612.
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