Thematische Bibliographien / Allophagie

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Auswahl der wissenschaftlichen Literatur zum Thema „Allophagie“

Autor: Grafiati

Veröffentlicht am 25. Mai 2024

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Zeitschriftenartikel zum Thema "Allophagie"

Parfitt, R. L. „Allophane and imogolite: role in soil biogeochemical processes“. Clay Minerals 44, Nr. 1 (März 2009): 135–55. http://dx.doi.org/10.1180/claymin.2009.044.1.135.

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AbstractThe literature on the formation, structure and properties of allophane and imogolite is reviewed, with particular emphasis on the seminal contributions by Colin Farmer. Allophane and imogolite occur not only in volcanic-ash soils but also in other environments. The conditions required for the precipitation of allophane and imogolite are discussed. These include pH, availability of Al and Si, rainfall, leaching regime, and reactions with organic matter. Because of their excellent water storage and physical properties, allophanic soils can accumulate large amounts of biomass. In areas of high rainfall, these soils often occur under rain forest, and the soil organic matter derived from the forest biomass is stabilized by allophane and aluminium ions. Thus the turnover of soil organicmatter in allophanicsoils is slower than that in non-allophanicsoils. The organic matter appears to be derived from the microbial by-products of the plant material rather than from the plant material itself. The growth of young forests may be limited by nitrogen supply but growth of older forests tends to be P limited. Phosphorus is recycled through both inorganic and organic pathways, but it is also strongly sorbed by Al compounds including allophane. When crops are grown in allophanic soils, large amounts of labile P are required and, accordingly, these soils have to be managed to counteract the large P sorption capacity of allophane and other Al compounds, and to ensure an adequate supply of labile P. Because of their physical and chemical properties, allophanic soils are excellent filters of heavy metals and pathogens.

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Parfitt, R. L., A. Parshotam und G. J. Salt. „Carbon turnover in two soils with contrasting mineralogy under long-term maize and pasture“. Soil Research 40, Nr. 1 (2002): 127. http://dx.doi.org/10.1071/sr00105.

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Total organic carbon (C) and natural 13C abundance were measured in adjacent allophanic soils (Andisols) and non-allophanic soils (Inceptisols) under maize (Zea mays L.) and ryegrass pasture (Lolium perenne L.) to assess the C turnover rate in soils of contrasting mineralogy and specific surface area. The allophanic soil contained more total C than the non-allophanic soil (139 v. 101 t C/ha in the upper 0–35 cm) but neither soil showed a significant difference in C content between pasture and maize, provided maize residue was retained and incorporated. The gross annual inputs under maize and pasture were both estimated to be about 9 t C/ha, consistent with the similar soil total C contents. Since the soil total C content did not appear to change with time, the gross C mineralisation was about 9 t C/ha each year. The proportion of old pasture C remaining in the soil after maize cropping for 25 years was about 78&percnt; in the allophanic soils and about 69&percnt; in the non-allophanic soils, reflecting the influence of both Al and allophane, with its high specific surface area, on the retention of old C. The maize C retained in 25 years was similar in both the allophanic soil and the non-allophanic soil (29 t/ha). Therefore, the higher total C content of the allophanic soil would appear to arise from stabilisation of old pasture and forest C by Al and allophane. clover, grass, New Zealand soils.

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Onodera, Yoshio, Takashi Iwasaki, Abhijit Chatterjee, Takeo Ebina, Toshio Satoh, Takashi Suzuki und Hitoshi Mimura. „Bactericidal allophanic materials prepared from allophane soil“. Applied Clay Science 18, Nr. 3-4 (März 2001): 123–34. http://dx.doi.org/10.1016/s0169-1317(00)00038-7.

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Onodera, Yoshio, Shunji Sunayama, Abhijit Chatterjee, Takashi Iwasaki, Toshio Satoh, Takashi Suzuki und Hitoshi Mimura. „Bactericidal allophanic materials prepared from allophane soil“. Applied Clay Science 18, Nr. 3-4 (März 2001): 135–44. http://dx.doi.org/10.1016/s0169-1317(00)00039-9.

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Perez del Villar, L., M. C. Moro und M. L. Cembranos. „Allophane in weathered zones of barite ore deposits (Vide de Alba and San Blas, Zamora, Spain): mineralogy and genesis“. Clay Minerals 27, Nr. 3 (September 1992): 309–23. http://dx.doi.org/10.1180/claymin.1992.027.3.04.

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AbstractThe allophane studied occurs in the weathered zones of the barite-sulphide-bearing dolomitic levels, interbedded in the barite ore deposits of Vide de Alba and San Bias (Province of Zamora). These ore deposits are interstratified in the Silurian-Devonian sulphide bearing volcano sedimentary materials of the Alcañices Synform. The allophanic samples have been studied by polarizing microscopy, SEM, XRD, DTA, TG, IRS, EMA and chemical analyses, the last after dissolving the samples by acid (HF + HNO3 + 3HCl + H3BO3) and alkaline digestion (0·5 m NaOH). It is suggested that allophane originates from the reaction of acid solutions released during the weathering of sulphides with acid volcanoclastic rocks. Silica-alumina gels were deposited in holes formed during earlier dissolution of the dolomite associated with the barite ores. Later processes of desilication partially transform allophane to gibbsite.

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Moro, M. C., M. L. Cembranos und A. Fernandez. „Allophane-like materials in the weathered zones of Silurian phosphate-rich veins from Santa Creu d'Olorda (Barcelona, Spain)“. Clay Minerals 35, Nr. 2 (April 2000): 411–21. http://dx.doi.org/10.1180/000985500546873.

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AbstractAllophane-like materials occur in the weathered zones of the phosphate-rich veins hosted in Silurian metasediments of the Catalonian Coastal Ranges. These metasediments also host sulphide and phosphate sedimentary mineralizations. Mineralogical and geochemical investigations of the allophanic samples indicate that they comprise Si-rich allophane, with a molar SiO2/Al2O3 ratio ranging between 1.19 and 2.23, with amorphous Al-(Ca) phosphate and hydroxylapatite as major minerals, and minor goethite and quartz. It is assumed that allophane, amorphous Al-(Ca) phosphate and hydroxylapatite come from the reaction of acid solutions, released during the weathering of sulphide interbedded in black shales, with phosphate-rich veins and volcano- sedimentary host rocks. Silica-alumina gels were deposited in fissures and cavities left by a previous dissolution of the phosphate-rich veins. Later the phosphate minerals filled the conchoidal microfractures and shrinkage microcracks of the allophane.

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Allbrook, RF. „Shrinkage of some New Zealand soils and its implications for soil physics“. Soil Research 31, Nr. 2 (1993): 111. http://dx.doi.org/10.1071/sr9930111.

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Aggregates from three New Zealand soils were used to produce shrinkage curves. Each soil had a clay mineralogy dominated by a different mineral, namely allophane, halloysite and kaolinite.The curves showed marked differences. Only the allophanic soil showed structural shrinkage, and only the halloysitic soil showed residual shrinkage. When the slope of the normal shrinkage line is about unity, this indicates the soil is liable to crack- this was only shown by the allophanic soil. The implication for soil physics is that, since all soils with at least a moderate clay content shrink, bulk densities change with moisture and this must be allowed for in such calculations as soil moisture on a volume basis.

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Chevallier, Tiphaine, Kenji Fujisaki, Olivier Roupsard, Florian Guidat, Rintaro Kinoshita, Elias de Melo Viginio Filho, Peter Lehner und Alain Albrecht. „Short-range-order minerals as powerful factors explaining deep soil organic carbon stock distribution: the case of a coffee agroforestry plantation on Andosols in Costa Rica“. SOIL 5, Nr. 2 (15.11.2019): 315–32. http://dx.doi.org/10.5194/soil-5-315-2019.

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Abstract. Soil organic carbon (SOC) constitutes the largest terrestrial C stock, particularly in the Andosols of volcanic areas. Quantitative information on distribution of SOC stocks is needed to construct a baseline for studying temporal changes in SOC. The spatial variation of soil short-range-order minerals such as allophane usually explains the variability of topsoil SOC contents, but SOC data for deeper soil layers are needed. We found that within a 1 km2 Costa Rican basin covered by coffee agroforestry, SOC stocks in the upper 200 cm of soil were highly variable (24 to 72 kg C m−2). Topsoil SOC stocks were not correlated with SOC stocks present in deeper layers. Diffuse-reflectance mid-infrared (MIR) spectroscopy made possible the analysis of a large number of samples (69 soil profiles, i.e. 598 soil samples) for ammonium-oxalate and sodium-pyrophosphate-extractable forms of Al, Fe, and Si, as well as SOC content and bulk density. Using the MIR spectra, we identified two different soil materials, which were identified as allophanic and halloysitic soil material. Allophanic soil occurred on top of the halloysitic soil. The thickness of the allophanic soil material, rich in SRO minerals and related to a young andic A horizon, explained the variability of SOC. This study illustrates that knowledge of topography and pedogenesis is needed to understand and extrapolate the distribution of SOC stocks at landscape scales.

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Parfitt, RL. „Surface charge in some New Zealand soils measured at typical ionic strength“. Soil Research 30, Nr. 3 (1992): 331. http://dx.doi.org/10.1071/sr9920331.

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The positive and negative surface charges of some New Zealand soils used for horticulture were measured at different pH values using 0.002 M CaCl2 solutions, Which have a similar ionic strength to soil solutions in New Zealand. The surface negative charge increased with pH for all soil samples including those containing mica and smectite. This behaviour was mainly due to the presence of organic matter and allophane both of which had an appreciable amount of variable negative charge. Allophanic soil B horizons had a higher positive charge than that of the Oxidic soils, which was less than 1 cmol kg-1 at pH 5.

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He, Ming, und Yukiya Horikawa. „Stability of allophane, allophanic clay, and allophane-halloysite floc in aqueous solutions of an anionic exocellular heteropolysaccharide (Gum Xanthan) fromXanthomonas campestris“. Soil Science and Plant Nutrition 42, Nr. 3 (September 1996): 603–12. http://dx.doi.org/10.1080/00380768.1996.10416329.

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Dissertationen zum Thema "Allophagie"

Cailloce, Justine. „Identification des facteurs de reconnaissance des mitochondries spermatiques dans l’embryon de C. elegans, garants de l’hérédité mitochondriale uni-parentale maternelle“. Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS497.pdf.

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Les mitochondries sont des composants cellulaires essentiels, retrouvés dans le cytoplasme de la grande majorité des cellules des organismes eucaryotes. Elles interviennent dans plusieurs mécanismes garants du bon fonctionnement cellulaire comme l’apoptose ou le stockage du calcium. La principale fonction mitochondriale est portée par la membrane mitochondriale interne où sont situés des complexes protéiques permettant la production d’adénosine triphosphate ou ATP, source d’énergie pour nos cellules. Dans le règne animal les mitochondries sont les seuls autres organites, en plus du noyau, à posséder un génome, l’ADN mitochondrial ou ADNmt. Les 37 gènes portés par ce génome mitochondrial ne représentent qu’une faible part des gènes d’une cellule mais ils sont néanmoins vitaux. En effet, toutes les protéines codées par le génome mitochondrial sont indispensables à la production d’ATP. Les mitochondries sont donc au centre du fonctionnement cellulaire et l’on constate que des perturbations dans leur composition et leurs fonctions, générées par diverses mutations, sont délétères et à l’origine de nombreuses pathologies aux symptômes très variés. Lors de ma thèse je me suis intéressée à un aspect atypique de ces organites, leur mode d’hérédité. Si l’ADN nucléaire est hérité pour moitié de chaque parent, l’ADN mitochondrial est quant à lui, malgré quelques exceptions, hérité uniquement de la mère. On parle ainsi de transmission mitochondriale uni-parentale maternelle. Cet évènement de la reproduction sexuée est très conservé au cours de l’évolution, suggérant son intérêt majeur pour les différentes espèces animales et végétales. Cette hérédité uniparentale maternelle résulte d’une dégradation active des mitochondries paternelles qui pénètrent dans le cytoplasme de l’ovocyte lors de la fécondation. Cependant, les raisons de ce mode d’hérédité et les mécanismes le régulant ne sont pas complètement compris. Pour mes recherches, j’ai utilisé l’organisme modèle C. elegans qui présente également une hérédité mitochondriale uni-parentale maternelle. Profitant des avantages expérimentaux de ce nématode, mon objectif était particulièrement d’identifier des marques portées par les mitochondries spermatiques à l’origine de leur reconnaissance dans l’ovocyte. Dans un premier temps, par imagerie et par une approche gènes candidats, j’ai évalué le rôle des marques de poly-ubiquitylation dans le ciblage spécifique des mitochondries spermatiques dans l’embryon. L’absence de rôle évident de la poly-ubiquitylation m’a emmené à développer une approche globale et non biaisée de protéomique afin d’identifier des facteurs de reconnaissance de ces mitochondries. Cette méthode de marquage indirect de proximité par biotinylation m’a permis d’identifier l'interactome de LGG-1, une protéine majeure contrôlant les processus d’autophagie et impliquée dans la dégradation des mitochondries spermatiques dans l'embryon précoce de C. elegans. J’ai ainsi établi une liste de protéines candidates pouvant agir comme signal de dégradation de ces mitochondries. De manière plus générale, j’ai établi l’interactome d’une protéine majeure de l’autophagie dans l’embryon précoce de C. elegans. Enfin, j’ai participé au travail commun de l’équipe visant à établir un modèle d’hérédité biparentale. Dans ce but nous combinons les mutants connus comme impliquées dans la dégradation des mitochondries spermatiques et dans les processus de mitophagie somatique. L’établissement d’un tel génotype met en évidence la complexité des mécanismes impliqués dans l’hérédité uniparentale dont une partie reste à élucider
Mitochondria are essential cellular components, found in the cytoplasm of the vast majority of cells in eukaryotic organisms. They are involved in a number of mechanisms that ensure proper cell function, such as apoptosis and calcium storage. The main mitochondrial function is carried out by the inner mitochondrial membrane, where protein complexes are located, enabling the production of adenosine triphosphate or ATP, the energy source for our cells. In the animal kingdom, mitochondria are the only organelles other than the nucleus to possess a genome, the mitochondrial DNA or mtDNA. The 37 genes carried by this mitochondrial genome represent only a small proportion of a cell's genes, but they are vital nevertheless. Indeed, all the proteins encoded by the mitochondrial genome are required for energy production. Therefore, disturbances in mitochondria composition and function, caused by various mutations, have been shown to be deleterious and the source of many pathologies with a wide range of symptoms.During my thesis, I focused on an atypical aspect of these organelles: their mode of inheritance. Indeed, while nuclear DNA is inherited in equal parts from each parent, the mitochondrial DNA is inherited exclusively from the mother. This particular mode of inheritance is known as maternal uni-parental mitochondrial transmission. This event of sexual reproduction is highly conserved throughout evolution, suggesting its major interest for different animal and plant species, even though some exceptions exist. This maternal uniparental inheritance results from the active degradation by an autophagy dependent mechanism, of paternal mitochondria, which enter the oocyte cytoplasm during fertilization. However, the reasons for this mode of inheritance and the mechanisms regulating it are not fully understood. For my research, I used the model organism C. elegans, which also exhibits maternal uni-parental mitochondrial inheritance. Taking advantage of the experimental advantages of this model system, my particular aim was to identify the markers carried by sperm mitochondria which trigger their recognition in the oocyte. As a first step, using imaging and a candidate gene approach, I assessed the role of poly-ubiquitylation marks in the targeting of sperm mitochondria in the embryo. The lack of a clear role for poly-ubiquitylation led me to develop a comprehensive and unbiased proteomic approach to identify mitochondrial recognition factors. This method of indirect proximity labeling by biotinylation enabled me to identify in the early C. elegans embryo, the interactome of a major protein controlling the autophagy machinery. From this interactome, I then drew up a list of candidate proteins that could act as degradation signals for the degradation of sperm mitochondria in the early embryo of C. elegans. Finally, I took part in the team's common work to establish a model of biparental heredity. To this end, we are combining all existing mutants known to act in the sperm mitochondria degradation, as well as in somatic mitophagy processes. Establishing such a genotype highlights the complexity of the mechanisms involved in uniparental inheritance, some of which remain to be elucidated

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Casimir, Al-Mario. „From volcanic ash to allophanic dust : understanding phosphorous behaviour in Dominican soils“. Thesis, Bangor University, 2015. https://research.bangor.ac.uk/portal/en/theses/from-volcanic-ash-to-allophanic-dust--understanding-phosphorous-behaviour-in-dominican-soils(cc56436e-015b-4489-b926-fd62dd25fb7c).html.

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The economy of the Commonwealth of Dominica is primarily agrarian based with banana production as one of the key export commodities, notwithstanding its preferential loss in the European Union market. However, banana productivity like most other crops has been severely impacted by a general low native soil nutrient status coupled with low application rates of phosphate (P) fertilizers in particular. The latter can be partly attributed to the low purchasing power on the international market as is evident in the long term trends of increaseprices for nitrogenous and phosphate fertilizers. The volcanic soils of the Commonwealth of Dominica were first studied in a relatively detailed way in 1967 with these soils showing high phosphate retention capacities. As a consequence, although P application is an integral part of profitable agricultural systems, improving soil fertility and plant nutrient management is a complex challenge. This challenge is amplified by the fact that a high ability to adsorb P is one of the characteristics of volcanic soils making P sparingly available for plant uptake. Hence although the world’s high reserves of phosphate ores are declining the demand for P fertilizers in the humid tropics are constantly increasing. If not managed properly, increase and continued input of P fertilizers and manure P may eventually lead to environmental rather than agronomic concerns. This research examines the influence of soil properties from some major agricultural soils in the Commonwealth of Dominica in order to obtain an improved comprehension of soil fertility limitations with the goal of developing nutrient management and farm developmental strategies geared towards increased crop production and overall farm productivity. In this regard special attention is given to the use of pyroligenous acid as a low molecular weight organic acid (LMWOA) in catalysing the dissolution of secondary P minerals. Hence the aim is to understand how native P stocks as well as applied fertilizer can potentially become more plant available thus reducing P fertilizer applications to a required minimum.

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Bauer, McNeill John. „Multivariate Analysis of Factors Regulating the Formation of Synthetic Allophane and Imogolite Nanoparticles“. Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/93330.

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Imogolite and allophane are nanosized aluminosilicates with high value in industrial and technological applications, however it remains unclear what factors control their formation and abundance in nature and in the lab. This work investigated the complex system of physical and chemical conditions that influence the formation of these nanominerals. Samples were synthesized and analyzed by powder x-ray diffraction, in situ and ex situ small angle x-ray scattering, and high-resolution transmission electron microscopy. Multivariate regression analysis combined with linear combination fitting of pXRD patterns was used to model the influence of different synthesis conditions including concentration, hydrolysis ratio and rate, and Al:Si elemental ratio on the particle size of the initial precipitate and on the phase abundances of the final products. The developed models described how increasing Al:Si ratio, particle size, and hydrolysis ratio increased the proportion of imogolite produced, while increasing the concentration of starting reagents decreased the final proportion. The model confidences were >99%, and explained 86 to 98% of the data variance. It was determined from the models that hydrolysis ratio was the strongest control on the final phase composition. The models also were able to consistently predict experimentally derived results from other studies. These results demonstrated the ability to use this approach to understand complex geochemical systems with competing influences, as well as provided insight into the formation of imogolite and allophane.
Master of Science
Allophane and imogolite are nanosized aluminosilicate minerals and strongly control the physical and chemical behavior of soil. They hold promise for use in technological applications. In nature, allophane and imogolite are often observed together in varying proportions. Similarly, laboratory synthesis by various methods usually does not result in pure phases. These observations suggest they form at the same time, at a wide range of solution chemical conditions. It remains unclear what factors determine how and when these phases form in solution, which limits our understanding of their occurrence in nature and the laboratory. The objective of this study is to understand and explain what solution chemical and physical conditions control the formation of synthetic imogolite and allophane. We did this by utilizing a unique approach where we systematically varied starting conditions of formation of these particles, and then used analytic and statistical methods to develop a model that describes the relationship between each of the starting conditions – concentration, size, pH, atomic ratios, and hydrolysis ratios, and how those affect the phase abundance of the particles.

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Anderson, Donald Jared. „Understanding Soil Liquefaction of the 2016 Kumamoto Earthquake“. BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7135.

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The Kumamoto earthquake of April 2016 produced two foreshocks of moment magnitude 6.0 and 6.2 and a mainshock of 7.0, which should have been followed by widespread and intense soil liquefaction. A Geotechnical Extreme Events Reconnaissance team (GEER) led by Professor Rob Kayen of UC Berkley was dispatched to the Kumamoto Plain--which is in Kumamoto Prefecture, the southern main island of Japan--immediately following the earthquake. The Japanese and U.S. engineers in the GEER team observed mostly minor and sporadic liquefaction, which was unexpected as the local site geology, known soil stratigraphy, and intensity of the seismic loading made the Kumamoto Plain ripe for soil liquefaction. The paucity and limited scale of liquefaction shows a clear gap in our understanding of liquefaction in areas with volcanic soils. This study is a direct response to the GEER team's preliminary findings regarding the lack of significant liquefaction. An extensive literature review was conducted on the Kumamoto Plain and its volcanic soil. The liquefaction of the 2016 Kumamoto Earthquake was also researched, and several sites were selected for further analysis. Four sites were analyzed with SPT, CPT, and laboratory testing during the spring of 2017. A slope stability analysis and undisturbed testing were performed for specific sites. The results of the analysis show a general over-prediction of SPT and CPT methods when determining liquefaction hazard. The Youd et al. (2001) NCEES method was the most consistent and accurate in determining liquefaction. The soils in the area including sands and gravels had high levels of fines, plasticity, and organic matter due to the weathering of volcanic ash and pyroclastic material. The volcanically derived coarse-grained soils may also have exhibited some crushability, which gave lower resistance readings. Filled river channels had the worst liquefaction with natural levees and the Kumamoto flood plains having only minor liquefaction. Publicly available boring logs rarely showed laboratory test data of bore holes which led to a general inaccurate soil classification. Boring logs were also not updated with laboratory classifications and data. Undisturbed cyclic triaxial testing of soils at one site showed that volcanic soils had relatively high resistance to soil liquefaction, though drying of samples may have compromised the results. Embankment cracking at one test location was calculated a lateral spread and a seismic slope failure along the pyroclastic flow deposit.

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Kolka-Jonsson, Pall Valdimar. „CarbBirch (Kolbjörk): Carbon sequestration and soil development under mountain birch (Betula pubescens) in rehabilitated areas in southern Iceland“. The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1302113068.

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Creton, Benoît. „Étude par dynamique moléculaire du comportement d'aluminosilicates tubulaires hydratés : structure et dynamique du sytème eau-imogolite“. Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-Creton.pdf.

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La structure et la dynamique des molécules d'eau confinées dans des aluminosilicates de formes tubulaire (imogolite) et sphérique (allophane) ont été étudiées à l'échelle microscopique par la méthode de la dynamique moléculaire. Pour ce faire, des modèles structuraux de ces aluminosilicates ainsi que des modèles d'interactions ont été développés. La simulation de la dynamique vibrationnelle de l'imogolite fournit des résultats en accord avec ceux expérimentaux. Ainsi, certaines bandes des spectres infrarouge et Raman ont pu être attribuées. Les spectres Raman calculés pour ces structures montrent une bande située aux basses fréquences dont la position varie en fonction du diamètre du nanotube. Cette bande est attribuée à la vibration de respiration radiale de la structure. Les résultats des simulations sur les systèmes eau/imogolite montrent des caractères hydrophile et hydrophobe respectivement pour les surfaces interne et externe de l'imogolite. Par conséquent, les molécules d'eau proches de ces surfaces ont des comportements différents. Alors que les molécules d'eau entre les nanotubes se comportent de façon similaire aux molécules d'eau dans l'eau liquide, les caractéristiques structurales et dynamiques des molécules à l'intérieur de l'imogolite sont fortement influencées par la surface Bien que la composition chimique de la surface interne de l'imogolite et de l'allophane soit similaire, une plus grande mobilité des molécules d'eau est constatée dans le cas de la structure sphérique traduisant des interactions eau/surface plus faibles que pour le système eau/imogolite

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Maillet, Perrine. „Structure et croissance de nanotubes de Ge-imogolite simple et double-paroi“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00584846.

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Les Imogolites (OH)3Al2O3Si(OH) sont des minéraux naturels découverts en 1962 dans des sols volcaniques japonais qui présentent une structure analogue à celle des nanotubes de carbone. Leur synthèse, décrite depuis 1977, permet l'obtention de tubes bien calibrés et monodisperses. La récente mise en évidence de la possibilité de synthétiser des analogues au germanium en grande quantité en a fait un matériau de choix dans le cadre de mon sujet de thèse visant à préparer des matériaux mésoporeux à base de nanoparticules anisotropes. Lors de la caractérisation de ces imogolites par diffusion de rayons X aux petits angles (SAXS) et microscopie électronique en transmission (MET) et à force atomique (AFM), nous avons montré que ces analogues d'Imogolite sont bien des nanotubes, mais qu'ils existent sous deux formes : des tubes à paroi unique mais également des tubes à paroi double jamais observés à ce jour. La concentration importante utilisée pour cette synthèse a également permis de mieux définir l'espèce précurseur de ces nanotubes appelée proto-imogolite et mal connue jusqu'ici. Après une identification du paramètre déterminant la formation de l'une ou l'autre des structures, nous avons étudié en détail le mécanisme et la cinétique de croissance de ces imogolites. Enfin, des premiers tests sur l'organisation de ces nanotubes en forte concentration ou au sein de microgouttes permettent d'observer leur tendance à s'organiser, propriété prometteuse pour le développement futur d'applications.

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Creton, Benoît. „Étude par dynamique moléculaire du comportement d'aluminosilicates tubulaires hydratés : structure et dynamique du système eau-imogolite“. Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2006. http://tel.archives-ouvertes.fr/tel-00270255.

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La structure et la dynamique des molécules d'eau confinées dans des aluminosilicates de formes tubulaire (imogolite) et sphérique (allophane) ont été étudiées à l'échelle microscopique par la méthode de la dynamique moléculaire. Pour ce faire, des modèles structuraux de ces aluminosilicates ainsi que des modèles d'interactions ont été développés. La simulation de la dynamique vibrationnelle de l'imogolite fournit des résultats en accord avec ceux expérimentaux. Ainsi, certaines bandes des spectres infrarouge et Raman ont pu être attribuées. Les spectres Raman calculés pour ces structures montrent une bande située aux basses fréquences dont la position varie en fonction du diamètre du nanotube. Cette bande est attribuée à la vibration de respiration radiale de la structure. Les résultats des simulations sur les systèmes eau/imogolite montrent des caractères hydrophile et hydrophobe respectivement pour les surfaces interne et externe de l'imogolite. Par conséquent, les molécules d'eau proches de ces surfaces ont des comportements différents. Alors que les molécules d'eau entre les nanotubes se comportent de façon similaire aux molécules d'eau dans l'eau liquide, les caractéristiques structurales et dynamiques des molécules à l'intérieur de l'imogolite sont fortement influencées par la surface. Bien que la composition chimique de la surface interne de l'imogolite et de l'allophane soit similaire, une plus grande mobilité des molécules d'eau est constatée dans le cas de la structure sphérique traduisant des interactions eau/surface plus faibles que pour le système eau/imogolite.

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Levard, Clément. „Nanoparticules naturelles : imogolites et allophanes. Structure, mécanismes de croissance et capacité de rétention des éléments traces métalliques“. Phd thesis, Université Paul Cézanne - Aix-Marseille III, 2008. http://tel.archives-ouvertes.fr/tel-00368753.

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Cette étude vise à déterminer le transfert et la mobilité d'éléments traces métalliques (ETM), dans des sols de la Réunion destinés à l'épandage de déchets urbains. En plus des fortes teneurs naturelles en ETM, ces sols ont la particularité d'avoir une minéralogie très spécifique avec la présence en abondance de nanoparticules naturelles, communément appelés "imogolites" (nanotubes) et "allophanes" (nanosphères, ovoïdes, amorphe ?). Ces aluminosilicates structurés à courte distance sont susceptibles de piéger les ETM pouvant ainsi limiter leur mobilité et leur biodisponibilité.

Dans un premier temps, une étude sur des composés synthétiques analogues aux aluminosilicates a permis d'approfondir nos connaissances sur la structure et les mécanismes de formation des imogolites et allophanes. La synthèse de nanotubes de type imogolite (Si-imogolite et Ge-imogolite) a pu être optimisée ouvrant ainsi les portes à de potentielles applications industrielles. Enfin, notre étude a permis de mettre en avant le rôle important des nanoparticules naturelles sur la dynamique du Ni dans un andosol de la Réunion. Ainsi, près de 80% du Ni est lié aux aluminosilicates structurés à courte distance.

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„The Effects of Chemical Weathering on Thermal-Infrared Spectral Data and Models: Implications for Aqueous Processes on the Martian Surface“. Doctoral diss., 2011. http://hdl.handle.net/2286/R.I.9320.

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abstract: Chemical and mineralogical data from Mars shows that the surface has been chemically weathered on local to regional scales. Chemical trends and the types of chemical weathering products present on the surface and their abundances can elucidate information about past aqueous processes. Thermal-infrared (TIR) data and their respective models are essential for interpreting Martian mineralogy and geologic history. However, previous studies have shown that chemical weathering and the precipitation of fine-grained secondary silicates can adversely affect the accuracy of TIR spectral models. Furthermore, spectral libraries used to identify minerals on the Martian surface lack some important weathering products, including poorly-crystalline aluminosilicates like allophane, thus eliminating their identification in TIR spectral models. It is essential to accurately interpret TIR spectral data from chemically weathered surfaces to understand the evolution of aqueous processes on Mars. Laboratory experiments were performed to improve interpretations of TIR data from weathered surfaces. To test the accuracy of deriving chemistry of weathered rocks from TIR spectroscopy, chemistry was derived from TIR models of weathered basalts from Baynton, Australia and compared to actual weathering rind chemistry. To determine how specific secondary silicates affect the TIR spectroscopy of weathered basalts, mixtures of basaltic minerals and small amounts of secondary silicates were modeled. Poorly-crystalline aluminosilicates were synthesized and their TIR spectra were added to spectral libraries. Regional Thermal Emission Spectrometer (TES) data were modeled using libraries containing these poorly-crystalline aluminosilicates to test for their presence on the Mars. Chemistry derived from models of weathered Baynton basalts is not accurate, but broad chemical weathering trends can be interpreted from the data. TIR models of mineral mixtures show that small amounts of crystalline and amorphous silicate weathering products (2.5-5 wt.%) can be detected in TIR models and can adversely affect modeled plagioclase abundances. Poorly-crystalline aluminosilicates are identified in Northern Acidalia, Solis Planum, and Meridiani. Previous studies have suggested that acid sulfate weathering was the dominant surface alteration process for the past 3.5 billion years; however, the identification of allophane indicates that alteration at near-neutral pH occurred on regional scales and that acid sulfate weathering is not the only weathering process on Mars.
Dissertation/Thesis
Ph.D. Geological Sciences 2011

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Bücher zum Thema "Allophagie"

Su, Chunming. Surface charge characteristics and thermodynamic stability of imogolite and allophane. 1992.

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Buchteile zum Thema "Allophagie"

Hangay, George, Severiano F. Gayubo, Marjorie A. Hoy, Marta Goula, Allen Sanborn, Wendell L. Morrill, Gerd GÄde et al. „Allophagic Speciation“. In Encyclopedia of Entomology, 134. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6359-6_160.

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Hewitt, Allan E., Megan R. Balks und David J. Lowe. „Allophanic Soils“. In The Soils of Aotearoa New Zealand, 21–39. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-64763-6_2.

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Koji, Wada. „Allophane and Imogolite“. In SSSA Book Series, 1051–87. Madison, WI, USA: Soil Science Society of America, 2018. http://dx.doi.org/10.2136/sssabookser1.2ed.c21.

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Harsh, James, Jon Chorover und Egide Nizeyimana. „Allophane and Imogolite“. In Soil Mineralogy with Environmental Applications, 291–322. Madison, WI, USA: Soil Science Society of America, 2018. http://dx.doi.org/10.2136/sssabookser7.c9.

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Dahlgren, R. A. „Quantification of Allophane and Imogolite“. In Quantitative Methods in Soil Mineralogy, 430–51. Madison, WI, USA: Soil Science Society of America, 2015. http://dx.doi.org/10.2136/1994.quantitativemethods.c14.

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Huang, Yu-Tuan, David J. Lowe, G. Jock Churchman, Louis A. Schipper, Nicolas J. Rawlence und Alan Cooper. „Carbon Storage and DNA Adsorption in Allophanic Soils and Paleosols“. In Soil Carbon, 163–72. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04084-4_17.

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Hiradate, S., und K. Inoue. „Interactions of Mugineic Acid with Allophane, Imogolite, Montmorillonite and Gibbsite“. In Effect of Mineral-Organic-Microorganism Interactions on Soil and Freshwater Environments, 89–96. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-4683-2_9.

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Juo, Anthony S. R., und Kathrin Franzluebbers. „Properties and Management of Allophanic Soils“. In Tropical Soils. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195115987.003.0017.

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Allophanic soils are dark-colored young soils derived mainly from volcanic ash. These soils typically have a low bulk density (< 0.9 Mg/m3), a high water retention capacity (100% by weight at field capacity), and contain predominantly allophanes, imogolite, halloysite, and amorphous Al silicates in the clay fraction. These soils are found in small, restricted areas with volcanic activity. Worldwide, there are about 120 million ha of allophanic soils, which is about 1% of the Earth's ice-free land surface. In tropical regions, allophanic soils are among the most productive and intensively used agricultural soils. They occur in the Philippines, Indonesia, Papua New Guinea, the Caribbean and South Pacific islands, East Africa, Central America, and the Andean rim of South America. Allophanic soils are primarily Andisols and andic Inceptisols, Entisols, Mollisols, and Alfisols according to the Soil Taxonomy classification. Allophanic soils generally have a dark-colored surface soil, slippery or greasy consistency, a predominantly crumb and granular structure, and a low bulk density ranging from 0.3 to 0.8 Mg/m3. Although allophanic soils are apparently well-drained, they still have a very high water content many days after rain. When the soil is pressed between fingers, it gives a plastic, greasy, but non-sticky sensation of a silty or loamy texture. When dry, the soil loses its greasiness and becomes friable and powdery. The low bulk density of allophanic soils is closely related to the high soil porosity. For example, moderately weathered allophanic soils typically have a total porosity of 78%, with macro-, meso-, and micropores occupying 13%, 33%, and 32%, respectively. Water retained in the mesopores is readily available for plant uptake. Water retained in the micropores is held strongly by soil particles and is not readily available for plant use. The macropores provide soil aeration and facilitate water infiltration. The high water retention capacity is also associated with the high soil porosity. In allophanic soils formed under a humid climate, especially those containing large amounts of allophane, the moisture content at field capacity can be as high as 300%, calculated on a weight basis. Such extremely high values of water content seem misleading.

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„allophanic, adj.²“. In Oxford English Dictionary. 3. Aufl. Oxford University Press, 2023. http://dx.doi.org/10.1093/oed/7028187270.

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„allophanic, adj.¹“. In Oxford English Dictionary. 3. Aufl. Oxford University Press, 2023. http://dx.doi.org/10.1093/oed/3349524229.

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Konferenzberichte zum Thema "Allophagie"

Tunega, Daniel, Maria Rechberger, Vivian Remlinger, Katharina Lenhardt, Thilo Rennert, Harald Rennhofer, Max Willinger, Franz Zehetner und Martin Gerzabek. „Glyphosate adsorption on allophane and halloysite“. In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.20148.

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Sang, Hongji, Zhengcheng Gu, Zheng Cui, Ruoxue Zou und Yan Wu. „Preparation and Properties of Ceramic Solidified Product Containing Cs and Sr“. In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-92765.

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Abstract 137Cs and 90Sr in high level liquid waste, with high radioactivity, large heat-generating and relatively long half-life. In order to solve the problem of final disposal of 137Cs and 90Sr, natural mineral allophane was chosen as the base materials to synthesize the silicate ceramic solidified products with cold pressing/sintering method. The microstructure, phase composition and surface element distribution of the solidified products were analyzed. The solidification mechanism of the solidified products was also discussed. The surface of the solidified products appeared melting phenomenon after sintering, and the structure was more compact. CsAlSiO4, Sr2Al2SiO7 and SrAl2Si2O8, which can stably solidify Cs and Sr, were formed in the solidified products. The content of allophane in the solidified product has an important influence on the immobilization ratio of Cs and Sr. And at the sintering condition of 1 h duration time at 1200 °C, the immobilization ratios of Cs and Sr can reach 100 %. By increasing the content of cured substrate, the surface characteristics and crystallization properties of the solidified product can be improved, and the volume reduction effect was more obvious.

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Matsuura, Yoko, Fumitoshi Iyoda, Shuhei Hayashi, Shuichi Arakawa, Masami Okamoto und Hidetomo Hayashi. „DNA adsorption characteristics of hollow spherical allophane nano-particles“. In PROCEEDINGS OF PPS-29: The 29th International Conference of the Polymer Processing Society - Conference Papers. American Institute of Physics, 2014. http://dx.doi.org/10.1063/1.4873773.

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Jeute, Thomas J., Leslie L. Baker, Janice L. Bishop, Elizabeth B. Rampe und Zaenal Abidin. „CHARACTERIZING NANOPHASE MATERIALS ON MARS: SPECTROSCOPIC STUDIES OF ALLOPHANE AND IMOGOLITE“. In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-303855.

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Pranoto, Santika Kunti Prabawani und Nurul Fatimah. „Optimation of allophane clay and sugar palm fiber waste as Fe adsorbent“. In THE 3RD INTERNATIONAL SEMINAR ON CHEMISTRY: Green Chemistry and its Role for Sustainability. Author(s), 2018. http://dx.doi.org/10.1063/1.5082444.

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Dharmawan, Christian Adi, Cari, Pranoto und Prabang Setyono. „Effectiveness of combined activated allophane and effective microorganisms attached bioball to reduce phenol concentration in water“. In THE 3RD INTERNATIONAL SEMINAR ON CHEMISTRY: Green Chemistry and its Role for Sustainability. Author(s), 2018. http://dx.doi.org/10.1063/1.5082449.

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