Дисертації з теми "Salt formation"
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Lam, Ka Wing. "Pharmaceutical salt formation guided by phase diagrams /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CBME%202009%20LAM.
Повний текст джерелаCropper, Paul Edward. "A kinetic template effect in arylphosphonium salt formation." Thesis, Sheffield Hallam University, 1988. http://shura.shu.ac.uk/19513/.
Повний текст джерелаKonishi, Hirokazu. "Formation of Dy Alloy Films by Molten Salt Electrochemical Process." Kyoto University, 2003. http://hdl.handle.net/2433/149313.
Повний текст джерела0048
新制・課程博士
博士(エネルギー科学)
甲第9870号
エネ博第58号
新制||エネ||18(附属図書館)
UT51-2003-C638
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授 伊藤 靖彦, 教授 八尾 健, 教授 尾形 幸生
学位規則第4条第1項該当
Ren, Lirong. "Inorganic salt nanofibers as templates for the formation of oxide nanotubes." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974105651.
Повний текст джерелаChou, Tai-Li. "Kinetics of salt formation using terephthalic acid and N-methyl-2-pyrrolidinone." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/chou/ChouT04.pdf.
Повний текст джерелаElder, David. "Physicochemical and crystallographic investigations into the salt formation of two heterocyclic drugs." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/8721.
Повний текст джерелаIida, Takahisa. "Formation of Sm and Yb Alloy Films by Molten Salt Electrochemical Process." Kyoto University, 2003. http://hdl.handle.net/2433/148653.
Повний текст джерела0048
新制・課程博士
博士(エネルギー科学)
甲第10335号
エネ博第71号
新制||エネ||21(附属図書館)
UT51-2003-H756
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授 伊藤 靖彦, 教授 八尾 健, 教授 吉田 起國
学位規則第4条第1項該当
Rödner, Sandra. "Interfacial colloidal particle films and their structure formation." Licentiate thesis, KTH, Chemistry, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1505.
Повний текст джерелаAbstract toInterfacial colloidal particle films andtheir structure formation; a licentiate thesis, whichwill be presented by Sandra Rödner in Q2, 29 November 2002at 13.00.
Colloidal particles can be made to organise themselves intoordered arrays. These colloidal structures acquire interestingand useful properties, not only from their constituentmaterials but also from the spontaneous emergence of mesoscopicorder that characterises their internal structure. Orderedarrays of colloidal particles, with lattice constants rangingfrom a few nanometers to a few microns, have potentialapplications as optical computing elements and chemicalsensors, and also has an important influence on the mechanicalproperties and optical appearance of paint films and papercoatings.
The control of colloidal structure formation starts with theparticle interactions (attractive or repulsive) and colloidaldynamics, which is the topic of this thesis. To enable adetailed understanding of the different factors that controlthe formation of dense 2D colloidal films, a method forstructural characterisation was developed. The degree of orderin the hexagonal close-packed structure, displayed by thecolloidal films, was characterised by the size of ordereddomains and by the distribution of pore sizes. The size ofordered domains was obtained from the pair distributionfunction, and the distribution of pores from a Delaunaytriangulation procedure. These methods are based on theparticle positions in the film, which were determined by lightmicroscopy and processed digital images.
The two methods were used to study the effect of particleinteractions on the structure of colloidal monoparticulatefilms, formed at the air-liquid interface. The size of theordered domains decreased exponentially with increasing bondstrength, while the pore density increased. The transfer andsubsequent drying of the formed film on a solid substrateinduced structural changes; the capillary forces transformedsmall pores into triangular order while some of the largervoids and cracks increased in size.
The structural features of colloidal monolayers, formed bydrying a dilute silica suspension on a substrate, wereinvestigated. Addition of small amounts of salt resulted indrastic changes of the particle film structure. The size of theordered domains decreased exponentially with increasing amountsof added salt (0-2.9% NaCl/Silica ratio), with a simultaneousincrease of the concentration of large defects. This suggeststhat loss of colloidal stability and onset of particle adhesionto the substrate inhibit rearrangement and ordering. Theevaporation rate was controlled by varying the relativehumidity during drying. Colloidal monolayers with the largestordered domains and the lowest concentration of stacking faultswere formed at an intermediate humidity (55% RH).
The rearrangement process during drying of dilute silicasuspensions was followed in detail by studying the changes inthe structural features during growth of colloidal monolayers.Low crystal growth rate promoted the transition of squarelattice domains to a hexagonal close-packed structure. Additionof salt to the electrostatically stabilised dispersionincreased the formation of square structured regions at thecrystal-suspension interface, due to increasing adhesion to thesubstrate. The loss of colloidal stability inhibited therearrangement process, resulting in higher concentrations ofsquare lattice domains at large distances from the crystal edgecompared to systems without added salt.
Ziga, Jeffrey Michael. "The Moroni formation in Salt Creek Canyon Central, Utah: implications for paleogene topography." Connect to resource, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1149600004.
Повний текст джерелаRobbins, Michael. "Sedimentology and sedimentary tectonics of the Salt Wash Member, Morrison Formation, Western Colorado." Thesis, Boston College, 2009. http://hdl.handle.net/2345/658.
Повний текст джерелаThesis advisor: Noah P. Snyder
The Brushy Basin Member of the Morrison Formation records a time of increased volcanic activity in the North American Cordillera during the Late Jurassic. Sedimentological and petrographic observations in the Brushy Basin, in conjunction with findings of widespread plutonic intrusion in the source areas, point to a volcanic pulse within the Cordilleran magmatic arc. This study investigated the subjacent Salt Wash Member, for the purpose of better constraining the timing of the volcanic pulse. Petrographic and statistical analyses of the Salt Wash sandstone identified statistically significant upsection trends in volcanic rock fragment and plagioclase feldspar at one of the four study areas. The remaining three study areas showed no upsection trends in sandstone composition that would reflect a pulse in volcanism during Salt Wash Member time. It is more likely that the Salt Wash was deposited during a time of volcanic quiescence leading up to the post-Nevadan Orogeny volcanic reactivation. Sedimentology and cementation patterns of the Salt Wash Member were also studied. Cathodoluminescence indicates that the member was well-flushed with shallow formation waters, thus preventing any calcite optical zoning. Luminescence intensity suggests that the Salt Wash Member sediments were cemented at varying depths and within differing Eh-pH regimes. Field-based sedimentological observations support a model of braided stream channel deposition across a semi-arid landscape with streamflow entering the basin from both the south and west
Thesis (MS) — Boston College, 2009
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Geology and Geophysics
Raad, Fadl. "Balearic Promontory architecture and history during the formation of the Mediterranean Salt Giant." Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONG018.
Повний текст джерелаThe Messinian Salinity Crisis (MSC; 5.97– 5.33 Ma) is one of the most controversial geological events that influenced the evolution of the Mediterranean Basin in the late Miocene, leaving behind an immense volume of evaporites known as the Mediterranean Salt Giant (MSG). Today, more than 90% of the MSG evaporitic deposits are located offshore, buried below thick sediments that are Pliocene to Quaternary in age, and have thus been studied mainly by marine seismic reflection imaging. The Balearic Promontory (BP), a prominent topographic high in the Western Mediterranean basin, contains a unique and tectonically poorly deformed MSC record that resembles the evaporitic record of other peri-Mediterranean marginal and intermediate basins.This PhD thesis was performed in the framework of the SaltGiant European Training Network (ETN), a cross-disciplinary project whose objective is to understand the formation of the MSG. The work of the thesis is focused on the MSC deposits of the BP. Multi-disciplinary approach was applied to answer some of the still open questions concerning the MSC event. As a first step, seismic interpretation of a wide seismic reflection dataset in the Western Mediterranean in general and in the BP in particular was performed, with the aim of refining the mapping of the Messinian units covering the area. To restitute the depositional history of the MSC evaporites of the BP, a detailed comparison with the Messinian evaporitic units of the Sicilian Caltanissetta Basin was carried out, in which a discussion on how this history matches the existing 3-stages chrono-stratigraphic ‘consensus model’ is illustrated. The next step consisted in the restoration of the paleo-bathymetry of the BP at the beginning of the MSC, focusing on the relatively less-deformed basin located in the central part of the BP and called the Central Mallorca Depression (CMD). To achieve this restoration, structural interpretation in the CMD area was done where the main post-MSC tectonic-related vertical movements that altered the MSC paleo-bathymetry were identified. Then 2D and pseudo-3D backstripping analysis were applied in collaboration with other colleagues from the SaltGiant project, to restore the paleo-bathymetry. In the final step, the paleo-bathymetry was used to model the deposition of the MSC evaporite volumes observed in the CMD using physics-based models built on strait hydraulic-control theory. The results show that the MSC units of the CMD could constitute an undeformed analog of those outcropping on-land in the Sicilian Caltanissetta Basin. Moderate post-MSC deformation acted along MSC strike-slip corridors in the CMD following the MSC evaporites deposition, thus altering only locally the paleo-bathymetry. A high amplitude drawdown (>850m) is required during the halite stage of the MSC. The results rise a series of doubts about the current consensus model, still widely accepted. Doubts concern the synchronous onset of salt at the basin scale, the maximum depth of deposition of the Primary Lower Gypsum (PLG) and the timing of formation of the Resedimented Lower Gypsum (RLG). All the results and discussions hint to the need of revision of the current MSC consensus model, as well as the importance of initiating drillings offshore over the BP area, which would help revealing many of the mysteries still buried with the MSG
Hall, Anne Marie. "The clay mineralogy of the lower San Andres formation, Palo Duro Basin, Texas." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/25880.
Повний текст джерелаFang, Qing. "Biostratigraphic and sequence stratigraphic analysis of the Yegua Formation, Houston salt embayment, northern Gulf of Mexico /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаSmith, Kristine A. "Stratigraphy, Geochronology, and Tectonics of the Salt Lake Formation (Tertiary) of Southern Cache Valley, Utah." DigitalCommons@USU, 1997. https://digitalcommons.usu.edu/etd/6546.
Повний текст джерелаProchnow, Shane J. Nordt Lee C. "Paleosols as an indicator of ancient landscapes, climates and stratal response during the Triassic the Salt Anticline Region of Utah /." Waco, Tex. : Baylor University, 2005. http://hdl.handle.net/2104/3017.
Повний текст джерелаRoma, Nuñez Maria. "Formation and subsequent inversion of extensional salt-detached ramp-syncline basins developed above ramp-flatramp faults." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/672461.
Повний текст джерелаL’extensió Juràssica – Cretàcica Inferior que va tenir lloc a l’Europa Occidental i al marge Nord Atlàntic va resultar en la formació de nombrosos sistemes de rift. Les conques associades a aquests rifts es mostres com a sinclinals amples, reomplerts per grans successions sedimentaries i desenganxats a un nivell salí (Pèrmic o Triàsic Superior). Aquestes conques rarament estan directament associades a falles, en canvi es troben limitades per estructures salines que generalment son paral∙leles a les estructures del basament. Per tant, la formació d’aquests sistemes extensionals requereix la presencia de i) una falla de basament extensiva amb diferents cabussaments i ii) una unitat evaporítica a sobre d’aquesta falla, la qual genera un desacoblament parcial o total respecte la conca i la falla extensiva. A més a més, la complexitat d’aquests contextos geològics augmenta quan algunes d’aquestes conques es troben parcialment invertides o fins i tot incorporades en cinturons de plecs i encavalcament durant el Cretaci Superior i Cenozoic.Les dades sísmiques i de camp permeten precisar la geometria d’aquestes conques sinclinals, però no la de les falles extensionals que las van originar. La geometria i la cinemàtica de las falles extensives associades ha aquestes conques, normalment s’ha establert utilitzant la geometria dels materials més superficials i assumint un acoblament total entre el basament i la cobertora. Aquestes interpretacions no consideren el paper que pot juga un nivell salí profund que clarament desacobla la deformació entre el basament i la cobertora.L’objectiu principal d’aquesta tesi es investigar els principals factors que controlen la formació i evolució de les conques sinclinals, utilitzant com a eina principal la modelització analògica. Per assolir aquest objectiu s’ha realitzat una revisió sobre conques sinclinals i una revisió de models analògics extensius realitzats fins ara. A partir d’aquests antecedents s’han realitzat dos programes experimentals. Els resultats d’aquests mostren com la formació i evolució de les conques sinclinals depenen de diversos factors que actuen simultàniament durant l’extensió i la posterior inversió.Aquesta tesi es pot utilitzar com a guia per reduir les incertes durant la interpretació de la geometria del basament associat a conques sinclinals desenvolupades en contextos salins, sobretot en els casos on les dades sísmiques disponibles no tenen bona resolució i cal utilitzar la geometria de la cobertora per reconèixer l’estructura del basament.
Lasser, Jana Verfasser], Lucas [Akademischer Betreuer] Goehring, Andreas [Gutachter] Tilgner, and Eberhard [Gutachter] [Bodenschatz. "Geophysical Pattern Formation of Salt Playa / Jana Lasser ; Gutachter: Andreas Tilgner, Eberhard Bodenschatz ; Betreuer: Lucas Goehring." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/118142741X/34.
Повний текст джерелаSwan, Alistair Michael. "Quantification of a distributive fluvial system : an example from the Salt Wash unit of the Morrison Formation, Utah." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=239012.
Повний текст джерелаEvans, Melissa Cheryl Foster. "Characterization and Formation of Particulate Nitrate in a Coastal Area." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000142.
Повний текст джерелаLi, Zhaoyang, and 李朝陽. "Novel strontium fortified calcium salt for enhancing bone formation: an in vitro and in vivo large animal modelstudy." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557108.
Повний текст джерелаRudolph, Wolfram W., and Gert Irmer. "Hydration and ion pair formation in common aqueous La(III) salt solutions: a Raman scattering and DFT study." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A36118.
Повний текст джерелаCook, Ethan L. "Near-Salt Stratal Geometries and Implications for the Evolution of the Onion Creek Diapir Moab, UT." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6327.
Повний текст джерелаJochems, Andrew P. "Formation, Deformation, and Incision of Colorado River Terraces Upstream of Moab, Utah." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1754.
Повний текст джерелаHuang, Yan. "Micro- and Nanogel Formation through the Ionic Crosslinking of Polyelectrolytes." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1417781855.
Повний текст джерелаLi, Zhaoyang. "Novel strontium fortified calcium salt for enhancing bone formation an in vitro and in vivo large animal model study /." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557108.
Повний текст джерелаDavid, Sarah. "Improving the solubility and dissolution of poorly soluble drugs by salt formation and the consequent effect on mechanical properties." Thesis, Aston University, 2005. http://publications.aston.ac.uk/11026/.
Повний текст джерелаBrassieur, David Aaron. "An Investigation Into the Origin, Composition, and Commercial Significance of a Sedimentary Subsalt Formation: Keathley Canyon, Gulf of Mexico." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2245.
Повний текст джерелаProchaska, Lesley C. "Geochemical Evidence for Vertical Migration of Deep Formation Fluids through the Baton Rouge -Denham Springs Fault System." ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1561.
Повний текст джерелаZHANG, HUAN. "EFFECTS OF SOLUTION COMPOSITION (SALTS, PH, DIELECTRIC CONSTANT) ON POLYELECTROLYTE COMPLEX (PEC) FORMATION AND THEIR PROPERTIES." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1543848436422118.
Повний текст джерелаSaedtler, Marco [Verfasser], Lorenz [Gutachter] Meinel, and Ulrike [Gutachter] Holzgrabe. "Pharmaceutical formulation strategies for novel antibiotic substances utilizing salt formation and two- and three-dimensional printing techniques / Marco Saedtler ; Gutachter: Lorenz Meinel, Ulrike Holzgrabe." Würzburg : Universität Würzburg, 2021. http://d-nb.info/1225296013/34.
Повний текст джерелаLohse, Samuel E. 1981. "Direct Synthesis of Thiolate-Protected Gold Nanoparticles Using Bunte Salts as Ligand Precursors: Investigations of Ligand Shell Formation and Core Growth." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11531.
Повний текст джерелаApplications of ligand-protected nanoparticles have increased markedly in recent years, yet their controlled synthesis remains an under-developed field. Nanoparticle syntheses are highly specialized in their execution and often possess significant limitations. For example, the synthesis of thiol-stabilized gold nanoparticles (AuNPs) with core diameters greater than 5.0 nm is difficult to achieve using existing methods. This dissertation describes the development of a synthetic strategy for thiolate-stabilized AuNPs over a wide range of core sizes using alkyl thiosulfates (Bunte salts) as ligand precursors. The use of Bunte salts permits the synthesis of larger AuNPs than can be achieved using thiols by allowing the AuNP cores to grow to larger diameters before the formation of the thiolate ligand shell. Chapter II details the development of a direct synthesis strategy using Bunte salts as ligand precursors that produces AuNPs with diameters up to 20 nm. Chapter III describes an investigation of the ligand shell formation that occurs during these syntheses. The ligand shell formation involves the adsorption of the Bunte salt to the AuNP surface, where it is converted to the thiolate. This conversion requires an excess of sodium borohydride in the synthesis of >5 nm AuNPs, but not for the synthesis of smaller AuNPs. This synthetic strategy was adapted for use in flow reactors to attain simultaneous AuNP synthesis and characterization. Chapter IV demonstrates that thiol-stabilized AuNPs can be synthesized in a microfluidic device with product monitoring provided by UV-vis absorbance spectroscopy. The development of a capillary flow reactor that permits the incorporation of new monitoring techniques is presented in Chapter V. The incorporation of Small-Angle X-ray Scattering (SAXS) analysis provides quantitative
Committee in charge: Victoria De Rose Chairperson; James E. Hutchison, Advisor; Catherine Page, Member; Darren W. Johnson, Member; Miriam Deutsch, Outside Member
Brand, John Richard. "Structural and stratigraphic evolution of the central Mississippi Canyon Area: interaction of salt tectonics and slope processes in the formation of engineering and geologic hazards." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3327.
Повний текст джерелаOlivito, João Paulo Roncolatto. "Modelo deposicional dos reservatórios carbonáticos lacustres neocretácicos da Formação Coqueiros no norte da Bacia de Campos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/182027.
Повний текст джерелаRecent discoveries of giant hydrocarbon accumulations in coquinas and other lacustrine carbonate rocks of Rift and Post-Rift (pre-salt) supersequences of Campos and Santos Basins have stimulated a series of studies focused on understanding the genesis of these unique reservoirs. An integrated petrologic-sedimentologic-stratigraphic-seismic study of Coqueiros Formation allowed characterizing the depositional model and evolution of reworked bioclastic rocks and other associated rocks deposited on the external high in the north of Campos Basin during the transition between late rift and sag stages. Seven carbonatic facies were defined from analysis combining information from sidewall core and sedimentary structures interpreted in image logs, in addition to one siliciclastic, two magnesian, and three hybrids facies. Bioclastic rudstones and grainstones with moderate to high reworking of the shells represent 65% of the samples described. Several pieces of evidences point to a predominantly shallow lacustrine depositional environment, dominated by storm currents: (i) presence of rudstones with high-angle cross-bedding (>14°) and longshore paleocurrents; (ii) limited occurrence of muddy sediments interbedded with thick packages of amalgamated bioclastic rudstones, indicating environment subject to high energy currents, above the fairweather wave base (FWB); (iii) predominance of rudstones deposits devoid of matrix on the structural high, with great lateral continuity, consistent with processes of storms acting on large areas of shallow lake; (iv) deposits of massive rudstones, with disorganized shells, similar to the modern coastal bioclastic deposits of California and Shark Bay. Three sets of facies association are proposed: (i) high energy set, represented by bioclastic rudstones and grainstones devoid of matrix, deposited between the shoreface and berm regions, above the FWB; (ii) low energy set, formed by hybrid facies with muddy or peloidal matrix and other facies of grain-size finer than medium sand, deposited below the FWB or in protected shallow environments (backshore); (iii) and an alkaline set, formed mainly by magnesian clay ooids, whose control is given by the more alkaline composition of lake water. Block diagrams of each of the five seismic-stratigraphic units, established for the Coqueiros Formation in the study area allowed to infer the evolution of the facies associations over time, demonstrate the general falling of relative lake level culminating in the pre-Neo-Alagoas unconformity (DPA). Paleocurrents suggests the activity of more than one wind direction over the external high, the stronger coming from northwest and a milder one coming from southeast, resulting in clean matrix bioclastic facies with good reservoir potential on both flanks of the structural high. These proposed wind directions for the Eobarremian and Neoaptian in the north of Campos Basin is extremely important to predict the location of the best depositional facies of the Coqueiros Formation in other target areas for hydrocarbon exploration.
Allred, Isaac John. "Spatial Trends and Facies Distribution of the High-Energy Alluvial Cutler Formation, Southeastern Utah." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6253.
Повний текст джерелаJohnson, Graham Richard. "The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16117/1/Graham_Johnson_Thesis.pdf.
Повний текст джерелаJohnson, Graham Richard. "The Formation and Growth of Marine Aerosols and the Development of New Techniques for their In-situ Analysis." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16117/.
Повний текст джерелаShah, Manoj Kumar. "Characterizing the Impact of Stress Exposure on Survival of Foodborne Pathogens." Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/29389.
Повний текст джерелаKergaravat, Charlie. "Dynamique de formation et de déformation de minibassins en contexte compressif : exemple du bassin de Sivas, Turquie Approche terrain et implications structurales multiéchelles." Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3005/document.
Повний текст джерелаThis doctoral work studies the interaction between withdrawal of minibasins and regional shortening during evolution of a foreland fold-and-thrust belt. This is achieved by a multiscale structural analysis of the Sivas Basin (Turkey). Extensive field work and regional seismic lines interpretations helped to build a new and detailed geologic map of the central Sivas Basin and to provide a new tectonosedimentary framework highlighting the influence of salt tectonics and the regional shortening, starting in the Late Eocene by the autochthonous evaporite deposition. This level is remobilized by the northward migrating sedimentary load, shortening and tilting of the basin southern margin during propagation of the foreland fold-and-thrust belt. Evaporite flow is recorded by the withdrawal of a primary generation of continental Oligocene minibasins which are then covered by an evaporite canopy. The canopy extending northward allows the development of second generation of continental to shallow marine mini-basins from Oligocene to Middle Miocene. Secondary minibasins initiation in the central part of the Basin, is characterized by sub-circular minibasins surrounded by polygonal diapirs and walls. Flanking these minibasins, a large variety of halokinetic structures is described: halokinetic sequences (hooks and wedges), composite halokinetic sequences and megaflaps. Preliminary sand-box modeling study suggests the development of thesehalokinetic structures both with and without shortening. Furthermore, minibasins geometries are closely similar to those imaged or mapped in other salt provinces suggesting that mini-basin withdrew is first control by sedimentary load, probably due to decoupling by the salt. However, the fractures and anisotropy of magnetic susceptibility analyses suggests the record of shortening since the minibasins initiation. The increase influence of regional shortening on the minibasins domain is expressed by salt walls and diapirs squeezing inducing: (i) the development of linear mini-basins perpendicular to the shortening direction, (ii) salt sheet emplacement and (iii) the translation/rotation of minibasins. The minibasins province produces a discontinuity for the fold-and-thrust belt propagation. Indeed, the minibasins province accommodates the shortening deformation along the polygonal network of salt walls and diapirs forming multidirectional structures. Furthermore, the regional shortening accommodation by salt structures squeezing produce an evaporitic remobilization and migration of a salt canopy toward the foreland basin
Bu doktora tezi/çalışması, bir önülke kıvrım ve bindirme kuşağının evrimi sırasında minihavzaların çekilmesi ve bölgesel kısalma arasındaki etkileşimi konu edinir. Çoklu ölçekteki bu yapısal analiz Sivas Havzası (Türkiye) ölçeğinde gerçekleştirilmiştir. Kapsamlı saha çalışması ve bölgesel olarak sismik kesitlerden ortaya çıkarılan yorumlamalar, Sivas Havzası’nın orta kesiminde detaylı bir jeolojik haritalama yapımına yardımcı olmuş ve otokton evaporit depolanmasının başladığı Geç Eosen’den başlayarak havza için tuz tektoniği ve bölgesel kısalmanın etkisindeki yeni bir tektono-sedimanter çatının ortaya çıkarılmasına neden olmuştur. Söz konusu seviye, önülke kıvrım ve bindirme kuşağının ilerlemesisüresince kuzeye doğru sedimanter dolgunun göçüyle birlikte havzanın güney kenarında kısalıma uğrayarak ve eğim kazanarak remobilize olmuştur. Evaporit akışı, kıtasal Oligosen minihavzalarının ilksel olarak oluşumundan sonra çekilmesine bağlı olarak gözlenmiş ve sonrasında evaporit yaygılarıyla örtülmüştür. Kuzeye kadar uzanan bu yaygı, Oligosen-Orta Miyosen arasında kıtasaldan sonra sığ denizel tipteki ikincil minihavzaların gelişimine de neden olmuştur.Havzanın orta kesimindeki ikincil minihavza başlangıcı, poligonal diyapir ve duvarlar tarafından çevrelenen dairesel minihavzalarla karakterize olur. Bu minihavzaların kanatlarında halokinetik yapılar tanımlanmıştır. Kanca (hook) ve kama (wedge) tiplerde olmak üzere halokinetik seriler, kompozit halokinetik seriler ve megaflaplar bu yapılar arasında sayılabilir. Çalışmanın başlangıcında yapılan kum kutusu model deneyi, bu halokinetik yapıların kısalmayla veya kısalma olmaksızın geliştiğini göstermiştir. Buna ek olarak minihavzaların geometrisi, muhtemelen tuzun ayrışmasından dolayı tortul yükün ilkkontrolünden dolayı çekilen diğer tuz bölgelerinde önerilen haritalanmış minihavzalara benzerdir. Bununla birlikte kırık ve manyetik suseptibilite analizleri, minihavzaların başlangıcından itibaren kısalmanın kayıt edilebilmesi hakkında fikir vermektedir. Minihavza bölgelerindeki bölgesel kısalımın artışı, tuz duvarları ve diyapirlerin sıkışmasıyla birlikte(i) kısalma yönüne dik durumdaki çizgisel minihavzaların gelişimi, (ii) tuz örtülerinin yerleşimi ve (iii) minihavzaların yer değiştirmesi veya dönmesiyle açıklanır. Minihavzalar bölgesi, kıvrım ve bindirme kuşağının gelişimi için bir süreksizlik üretir. Aslında, minihavzalar birçok yönde yapılar oluşturarak tuz duvarları ve diyapirlerin polygonal şekildeki yerleşimi boyunca kısalma deformasyonuna eşlik eder. Üstelik, tuz yapılarının eşlik ettiği bölgesel kısalma önülke havzalarına doğru evaporitik bir göçe de neden olmaktadır
Holzammer, Christine [Verfasser], Andreas [Akademischer Betreuer] Bräuer, Andreas [Gutachter] Bräuer, and Markus [Gutachter] Richter. "Raman spectroscopic study of the effect of aqueous salt solutions on the formation and dissociation behavior of CO2 gas hydrates / Christine Holzammer ; Gutachter: Andreas Bräuer, Markus Richter ; Betreuer: Andreas Bräuer." Freiberg : Technische Universität Bergakademie Freiberg, 2020. http://d-nb.info/1220636916/34.
Повний текст джерелаPei, Hongxia. "Bead Modeling of Transport Properties of Macromolecules in Free Solution and in a Gel." Digital Archive @ GSU, 2010. http://digitalarchive.gsu.edu/chemistry_diss/49.
Повний текст джерелаValenza, Jeffery Michael. "Redbeds of the Upper Entrada Sandstone, Central Utah: Facies Analysis and Regional Implications of Interfingered Sabkha and Fluvial Terminal Splay Sediments." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6112.
Повний текст джерелаDippenaar, Alwyn Bernard. "Hydrate formation in pharmaceutically relevant salts." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95979.
Повний текст джерелаENGLISH ABSTRACT: A theoretical and experimental study was performed in order to identify factors that influence the propensity of compounds containing anionic functional groups that are commonly found on pharmaceutical drug compounds to form hydrates. A Cambridge Structural Database (CSD) survey was initially undertaken to determine the propensity of different pharmaceutically acceptable anions to form hydrates. The results showed that hydrate formation will take place more regularly when the polarity of the functional group increases. Furthermore, if the charge distribution is very concentrated over the polar groups, hydrate formation will occur more readily. This observation was further investigated by performing a series of potential energy surface (PES) scans for the hydrogen bond (H-bond) in the structure of N-(aminoiminomethyl)-N-methylglycine monohydrate (creatine monohydrate) with various Density Functional Theory (DFT) and Wave Functional Theory (WFT) methods. WFT is often also referred to as ab initio, which refers to the construction of the wave function from first principles when this theory is applied. The scans revealed that several strong and directional H-bonds with different geometrical parameters between the carboxylate group and the water molecule are possible, which suggests that the H-bond plays an important role in driving the formation of pharmaceutical hydrates. A total of 44 hydrate structures were identified that have pharmaceutically acceptable functional groups. Optimisations in the gas phase and in an implicit solvent polarisable continuum solvent model with a variety of solvents showed that there is a significant dependence of the H-bond interaction energy on the anionic group as well as the steric density of surrounding substituents. It was found that the M06-2X method utilising the 6-311++G(d,p) basis set outperformed the other methods that were tested when compared to optimisations performed with the benchmark MP2/aug-cc-pVTZ level of theory. Furthermore, the strength of the H-bond was measured in the 44 experimentally determined structures by using a total of five generalized gradient approximation (GGA) methods, of which two methods contained the DFT-D3 correction. The results of these DFT methods were subsequently compared to results obtained at the benchmark MP2/aug-cc-pVTZ level of theory. The M06-2X method was identified as the most economical method to calculate H-bond energies. It was also found that the H-bond interaction energy shows a substantial dependence on the electrostatic environment. This was observed by a significant decrease in H-bond strength as the relative permittivity of the solvent increases. The effect of steric density on the H-bond interaction energy was investigated by performing hydrogen bond propensity calculations. These values were then compared to the interaction energies of each structure and the results showed that the presence of large bulky substituents can lead to an increase in bond energy by forcing the anionic functional group closer to the water molecule. Contrastingly, the bulky group can also push the anionic group away from the water molecule and result in a decrease in bond energy. Approximate values for the amount of stabilisation offered to the H-bonding system by the surrounding crystalline environment were calculated by optimising the H-bond geometrical parameters of selected compounds with a combination of the M06-2X and MP2 methods utilising the 6-311++G(d,p) basis set. The H-bond interaction energies were then calculated at the M06-2X/6-311++G(d,p) level of theory and compared to the H-bond interaction energies in geometries that have been fully optimised. After these energies were compared and the crystal packing of each structure was investigated, it was found that the packing of some structures within the crystalline environment limits the number of H-bonds that can be formed between the water and the compound of interest. Full optimisation calculations result in structures with cooperative stabilisation, such that more than one H-bond is found between the two fragments. The effect of substituents on H-bond interaction energy was investigated by the addition of six electron-donating and electron-withdrawing groups on four aromatic compounds with different anionic functional groups, namely carboxylate, nitrogen dioxide, sulfonate and phosphonate. It should also be mentioned that the nitrogen dioxide is not an anionic functional group, but it was included as it is a neutral radical that often forms hydrogen bonds. A total of 80 structures were optimised with a combination of the M06-2X and MP2 methods utilising the 6-311++G(d,p) basis set. This was followed by counterpoise corrected single point calculations at the M06-2X/6-311++G(d,p) level of theory. The results showed that the H-bond interaction energy bears no relationship to the inductive strength or the inductive ability of the substituents, but rather the ability of these substituents to rotate the anionic functional group and allow cooperative stabilisation of the H-bond. Furthermore, AIM analysis was performed for the substituted H-bonded aromatic structure. The results showed that electron-donating groups that are placed at the para position yield stronger H-bonds, which is once again accompanied by cooperative stabilisation. Electron-withdrawing groups with sufficient inductive effects can result in a weaker H-bond when placed at the meta position. The effect of water activity (aw) on the hydrate crystal formation was investigated experimentally by performing a series of crystallisations in various solvent mixtures. These mixtures consisted of water mixed with acetone, ethanol and ethyl acetate. A total of three organic acids were used in crystal formation, namely pyridine-4-carboxylic acid (isonicotinic acid), N-amino-iminomethyl-N-methylglycine (creatine) and benzene-1,3,5-tricarboxylic acid. It was found that water activity affects the formation of the hydrate as well as the anhydrous product. Additionally, nucleation and super saturation plays a large role in crystal formation and can serve as an effective technique when the formation of crystals of an appropriate shape and size is required for further analysis.
AFRIKAANSE OPSOMMING: 'n Teoretiese en eksperimentele studie was uitgevoer om faktore te identifiseer wat die geneigdheid van verbindings met anioniese funksionele groepe wat algemeen gevind word op farmaseutiese dwelm verbindings om die hidraat produk te vorm, affekteer. 'n Opname van strukture in die Cambridge Strukturele Databasis (CSD) is onderneem om die geneigdheid van verskillende farmaseutiese aanvaarbare anione om hidrate te vorm te bepaal. Die resultate het getoon dat hidraatvorming meer gereeld plaasvind indien die polariteit van die funksionele groepe toeneem. Verder is daar ook opgemerk dat 'n gekonsentreerde ladingsverspreiding op die polêre groepe ook tot 'n toename in hidraat vorming sal lei. Hierdie waarneming is verder ondersoek deur 'n reeks potensiële energie oppervlak (PES) skanderings van die waterstof binding (H-binding) vir die struktuur van N-amino-iminometiel-N-metielglisien monohidraat (kreatien monohidraat) met verskeie Digtheids-Funksionele Teorie (DFT) en Golffunksie Teorie (WFT) metodes uit te voer. Die skanderings het getoon dat verskeie sterk, gerigte H-bindings met verskillende geometriese parameters tussen die karboksilaatgroep en die watermolekule kan vorm. Hierdie bevindinge lê klem op die belangrike rol wat H-bindings in die vorming van farmaseutiese koolhidrate speel. 'n Totaal van 44 hidraat strukture met farmaseutiese aanvaarbare funksionele groepe was geïdentifiseer. Optimaliserings is in die gas fase asook in 'n implisiete kontinuum polariseerbare oplosmiddel model met 'n verskeidenheid oplosmiddels uitgevoer. Die resultate het 'n beduidende afhanklikheid van die H-binding interaksie-energie op die anioniese groep asook die steriese afkskerming van omringende groepe getoon. Daar is bepaal dat die M06-2X metode wat saam met die 6-311++G(d,p) basisstel die mees akkuraatste resultate gelewer het in vergelyking met die ander DFT metodes asook die MP2/aug-cc-pVTZ maatstaf. Die H-binding se sterkte is vir hierdie strukture bereken deur vyf GGA metodes te gebruik, waarvan twee metodes van die DFT-D3 korreksie gebruik maak. Die resultate van die berekeninge met hierdie DFT metodes is daarna vergelyk met resultate verkry met die MP2/aug-cc-pVTZ maatstaf. Daar is gevolglik bepaal dat die M06-2X metode die mees ekonomiese metode is om H-binding energië te bereken. Die H-binding interaksie energie toon 'n aansienlike afhanklikheid op die diëlektriese konstante van die oplosmiddel aan. Hierdie waarneming is op grond van 'n beduidende afname in die H-binding interaksie-energie indien die relatiewe permittiwiteit van die oplosmiddel verhoog word gemaak. Die effek van steriese digtheid is ondersoek deur waterstofbindinggeneigdheid waardes te bereken. Hierdie waardes is met die interaksie-energië van elke struktuur vergelyk. Die resultate dui daarop dat steries digte groepe tot 'n toename in interaksie energie kan lei wanneer die anioniese funksionele groep nader aan die water molekule gestoot word. Verder is dit ook moontlik vir hierdie steries digte groepe om die anioniese groep weg van die water molekule te stoot en gevolglik 'n afname in interaksie energie te veroorsaak. Benaderde waardes vir die hoeveelheid stabilisering wat die omringende kristallyne omgewing aan die H-binding bied is bereken deur die H-binding geometriese parameters van geselekteerde verbindings met die M06-2X en MP2 metodes en die 6-311++G (d,p) basisstel te optimaliseer. Die H-binding interaksie-energië is gevolglik by die M06-2X/6-311++G(d,p) vlak van teorie bereken en met die H-binding energië in strukture wat volledige optimaliseer is vergelyk. Nadat hierdie waardes vergelyk is, is daar gevind dat die pakking van strukture in the kristallyne omgewing verhoed dat sekere H-bindings tussen die water molekule en die verbinding van belang kan vorm. Strukture wat volledig optimaliseer is, lei tot strukture wat in staat is om koöperatiewe stabilisering te ondergaan. Koöperatiewe stabilisering word gekenmerk deur die vorming van meer as een H-binding tussen twee fragmente. Die effek van substituente op die H-binding interaksie energie is ondersoek deur die bevoeging van ses elektrondonor- en elektronontrekkendegroepe op vier aromatiese verbindings, naamlike die karboksilaatgroep , stikstofdioksied , sulfonaat en fosfonaat. Dit moet ook genoem word dat stikstofdioksied nie 'n anioniese funksionele groep is nie, maar dit was wel ingesluit omdat dit ‘n neutrale radikaal groep is wat dikwels waterstofbindings vorm. 'n Totaal van 80 strukture optimiserings was uitgevoer met 'n kombinasie van die M06-2X en MP2 metodes wat gebruik maak van die 6-311++G(d,p) basisstel. Dit is gevolg deur interaksie-energie berekeninge op die M06-2X/6-311++G(d,p) vlak van teorie. Die resultate het getoon dat daar geen verband tussen die induktiewe vermoë van die substituente en die sterkte van die H-binding is nie, dit is eerder die vermoë van hierdie substituente om die anioniese funksionele groep te laat roteer wat toelaat dat koöperatiewe stabilisering van die H-binding kan geskied. Die AIM analise is op 'n gesubstitueerde H-binding struktuur toegepas. Die resultate het getoon dat elektrondonorgroepe wat by die para posisie geplaas word tot sterker H-bindings sal lei, wat weereens met koöperatiewe stabilisering vergesel word. Elektrononttrekkendegroepe met sterk induktiewe effekte kan tot 'n swakker H-binding lei indien hulle by die meta posisie geplaas word. Die effek van water aktiwiteit (𝑎w) op hidraatkristalvorming is deur die uitvoering van 'n reeks kristallisasies in verskeie oplosmiddelmengsels ondersoek. Hierdie oplosmiddel mengsels bestaan uit water met asetoon, etanol of etielasetaat gemeng. Kristallisasies is vir drie organiese sure, naamlik piridien-4-karboksielsuur, N-amino-iminometiel-N-metielglisien monohidraat en 1,3,5-benseen tri-karboksielsuur uitgevoer. Daar is gevind dat water aktiwiteit 'n invloed op die vorming van die hidraat en watervrye produkte kan hê. Daarbenewens, speel water aktiwiteit 'n belangrike rol in die nukleasie fase van kristalvorming en kan as 'n effektiewe tegniek dien om kristalle van 'n toepaslike vorm en grootte vir verdere analise te verkry.
Håpnes, Mats. "Drilling in Salt Formations and Rate of Penetration Modelling." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25584.
Повний текст джерелаALMEIDA, LUIZ FELIPPE MEDEIROS DE. "THERMOMECHANICAL MODELING OF ANNULAR PRESSURE BUILD UP IN SALT FORMATIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=30456@1.
Повний текст джерелаEste trabalho apresenta uma modelagem numérica termo-mecânica para investigação da influência da presença da rocha salina no acréscimo de pressão em anulares confinados (APB). O fenômeno de APB é resultado da expansão térmica do fluido de perfuração trapeado nos anulares do poço, induzida pelo aquecimento gerado pela produção de hidrocarbonetos em temperatura superior ao restante do poço. Os evaporitos são formações que possuem um comportamento mecânico viscoelástico, apresentando deformação contínua a partir de uma tensão constante, processo conhecido como fluência. Este comportamento do sal não é atualmente considerado pelos simuladores utilizados pela indústria do petróleo durante o projeto de poços, no que tange dimensionamento para esta carga de pressão proveniente do APB. O objetivo deste trabalho é alcançado pelo desenvolvimento uma metodologia de cálculo do fenômeno de APB frente a formações salinas, através de um modelo numérico construído no software ABAQUS, utilizando o método dos elementos finitos. Diversas simulações foram realizadas com configurações distintas de litologia, temperatura e fluidos de perfuração, para analisar a influência do comportamento viscoelástico da rocha salina no crescimento de pressão em anulares confinados. Após análise de resultados obtidos, se concluiu que a rocha salina pode agir como aliviador da pressão gerada pela expansão térmica do fluido de perfuração confinado nos anulares do poço. As tensões geradas pelo APB levam a deformações de fluência que aumentam o diâmetro do poço e consequentemente o volume anular, acomodando parte do acréscimo de pressão gerado.
This dissertation presents a thermo-mechanical numerical modeling to investigate the influence of the presence of salt rock on annular pressure build-up (APB). The APB phenomenon is a result of thermal expansion of confined drilling fluid in the well annulus, induced by heat generated by the production of hydrocarbons at temperatures above the remainder of the well. The evaporite formations have a viscoelastic mechanical behavior, with continuous deformation at constant stress, known as creep. This salt behavior is not currently considered by simulators used by the oil industry for the design of wells, with respect to this pressure load from APB. The objective is achieved by developing a methodology for calculating the APB effect for wells with saline formations, using a numerical model built in ABAQUS software, using the finite element method. Several simulations were performed with different configurations of lithology, temperature and drilling fluids, to analyze the influence of the viscoelastic behavior of the salt rock on pressure growth in confined annuli. After analyzing the results, it was concluded that the rock salt may act as a relief for the pressure generated by thermal expansion of the confined drilling fluid in the well annulus. The stresses generated by the APB lead to creep strains that increase the well diameter and consequently the annular volume, accommodating part of the generated pressure increase.
Li, Bo. "Tidal channel meandering and salt marsh development in a marine transgressed incised valley system the Great Marsh at Lewes, Delaware /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 710 p, 2006. http://proquest.umi.com/pqdweb?did=1208133431&sid=9&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Повний текст джерелаMorales, Daniel. "Importancia de las Salinas de San Blas durante el Periodo Formativo en la sierra central del Perú." Pontificia Universidad Católica del Perú, 2012. http://repositorio.pucp.edu.pe/index/handle/123456789/113588.
Повний текст джерелаBasado en excavaciones en el sitio de San Blas en 1974, el autor presenta una secuencia desde el Periodo Arcaico Tardío al Periodo Intermedio Temprano, complementada con una breve descripción del tardío estilo San Blas (tardío Periodo Intermedio Temprano al Horizonte Tardío) usando analogías de fuentes etnohistóricas. Discute la importancia de la producción de sal y la conexión con otras áreas como Kotosh, Huánuco, y el flanco oriental de los Andes (Palcamayo, Tarma, Chanchamayo) mostrando que la zona de Chinchaycocha no estaba aislada sino más bien conectada de forma estrecha a sistemas más amplios.
Yee, James Gee Ken. "Carbon-carbon bond formation : reactions of alkenyltrimethylstannanes mediated by copper(I) salts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/NQ56649.pdf.
Повний текст джерелаBlomqvist, Torbjörn. "Karolinsk Stridstaktik : artilleriets och pikens roll 1700-1712 samt bataljonens stridsformering." Thesis, Högskolan på Gotland, Institutionen för humaniora och samhällsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208514.
Повний текст джерелаCarvalho, Elvio de. "A sala de aula de filosofia como espaço de vivências transformadoras: interculturalidade e amorosidade na formação docente." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/12049.
Повний текст джерелаO tema desta investigação está centrado na formação do professor de Filosofia tendo como base da mesma aspectos da interculturalidade e da amorosidade como vivências significativas no processo de formação docente. Tal perspectiva aponta para o desenvolvimento de uma prática pedagógica emancipadora entre professor/aluno. O espaço investigativo é determinado como sendo o contexto da sala de aula de uma Escola Pública Estadual da cidade de Rosário do Sul - RS. Nesse sentido, evidenciamos a necessidade de se refletir sobre a ação do professor de Filosofia, fazendo-se necessário um entendimento acerca dos saberes e fazeres que a academia está proporcionando a esse profissional da educação. Diante de tais considerações, apontamos como elemento significativo as limitações de uma prática pedagógica que desconsidera a cultura e as vivências de vida do aluno, visto que, para a construção do conhecimento, o desejo pelo aprendizado é necessário. Dessa forma, o reconhecimento e a relação afetiva é condição básica para uma emancipação pessoal e social do sujeito. A afetividade nesse contexto de investigação é percebida como uma significação mais ampla, referindo-se às vivências dos indivíduos e às formas de expressão mais complexas e essencialmente humanas. Além disso, compreendemos que o professor precisa desenvolver uma visão crítica para auxiliar na construção de um educar a partir do real, da cultura, do cognitivo e do afetivo. Entendemos que a emancipação está calcada no saber e no fazer docente, nas relações de afeto, respeito e reconhecimento como possibilidades de reconstruir e reinventar a história e o conhecimento como parte fundamental à liberdade.
Hasa, Dritan. "Innovative systems for drug delivery: pharmacokinetic and technological aspects." Doctoral thesis, Università degli studi di Trieste, 1985. http://hdl.handle.net/10077/9503.
Повний текст джерелаNowadays, the main objective of pharmaceutical companies is to develop innovative oral dosage forms for both prolonged and immediate drug releases. In fact, oral delivery has the peculiar advantage of being highly versatile dosage-wise. However, actives suffering from low oral bioavailability may not always be administered by using traditional dosage forms or common controlled release devices, due to the bioavailability’s strict dependence on both drug solubility in gastrointestinal fluids and on drug permeability through the cellular membranes. Recently, both conventional and modified release oral dosage forms have been developed by applying innovative technologies such as a) melt extrusion, and b) solid-state mechanochemistry. a) Melt extrusion Melt extrusion is a viable technology since it allows the production of a final dosage form having the desired shape and dimension. This is achieved by means of suitable thermoplastic polymeric carriers or by using non-polymeric carriers capable of softening or melting during the process. The loaded drug can be dissolved or dispersed in both crystalline and amorphous forms. Despite the efforts of the scientific community, this process still requires an adequate technology transfer, due to the high number of physical, chemical, physicochemical, mechanical and pharmacokinetics variables influencing the melt extruded product. In this context, the first part of the thesis (Chapter 2) presents an innovative contribution, i.e., the production of unconventional melt helical shaped extrudates with a ram extruder. These extrudates, based on mixtures of microcrystalline wax and theophylline, were characterized in terms of morphology (by Scanning Electron Microscopy (SEM)), of in vitro dissolution, of solid- state (by means of Differential Scanning Calorimetry (DSC) and X-Ray Powder Diffraction (XRPD)) and by checking the presence of the drug on the surface (by Photoelectron Spectroscopy (XPS)). Finally, an ad hoc in vitro-vivo modeling, suitably describing, and predicting the drug release and absorption from such kind of systems, was designed. b) Mechanochemistry Mechanochemical activation has been successfully employed to ameliorate the oral performance of drugs having scarce solubility, and therefore, low bioavailability. Through this solvent-free solid-state process, drug-carrier composites containing the drug in a highly available form are obtained thanks to the modification of its physicochemical properties (e.g. in an amorphous or nanocrystalline drug). This is the objective of the first part of Chapter 3, where mechanochemical process has been applied to improve dissolution performance, and therefore, absorption, of two scarcely soluble highly crystalline actives, namely, vinpocetine and vincamine. The drugs were subjected to mechochemical treatment in a lab scale planetary mill, using crosslinked polyvinylpyrrolidone as a carrier for vinpocetine, and sodium crosscarmellose or crosslinked polyvinylpyrrolidone as carriers for vincamine. These studies demonstrated the suitability of these materials to the mechanochemical process, the influence of these carriers on the disruption of the crystalline lattice, and the positive influence of the carriers on the dissolution performances and in vivo absorption. The drug-carrier coground composites were then characterized by means of transmission electron microscopy (TEM), solid-state nuclear magnetic resonance (SSNMR), DSC, PXRD, and Raman spectroscopy/imaging. A second possibility of application of the mechanochemical process is the mechanochemical synthesis: this is the focus of the second part of Chapter 3, where the mechanochemical synthesis is employed, under suitable experimental conditions, to promote the solid-state salification of both vinpocetine and vincamine. Citric acid was selected as a reagent, while crosslinked polyvinylpyrrolidone and sodium cross carmellose were chosen as fillers and process adjuvants in the case of vinpocetine and vincamine, respectively. In both cases, several cogrounds (differing from one another in terms of grinding time, active–to-citric acid molar ratio, presence, or absence of the filler) were prepared. This way, by means of a proper experimental design, the influence of the above mentioned formulation and process variables were studied. XPS and high-resolution TEM were used to obtain qualitative and quantitative information about the produced salt forms and to get some insight into the salification mechanism.
Oggi, l’obiettivo principale dell’industria farmaceutica consiste nel progettare forme farmaceutiche innovative convenzionali a rilascio immediato e/o protratto, adatte per uso orale, poiché i vantaggi di questo tipo di somministrazione consistono nella versatilità del dosaggio. Tuttavia, questa strategia fallisce quando si trattano principi attivi con una bassa biodisponibilità e che quindi non possono essere somministrati in forma classica, o con i normali metodi di rilascio controllato; dove la stessa biodisponibilità è legata a parametri chiave, tra cui la solubilità del farmaco nei fluidi gastrointestinali e la sua permeabilità attraverso le membrane cellulari. Con lo scopo di migliorare sia la biodisponibilità dei principi attivi poco solubili, che di ottenere forme a rilascio controllato, recentemente, l’applicazione di tecnologie innovative, quali l’estrusione per fusione e l’attivazione meccanochimica allo stato solido, hanno permesso la realizzazione di diverse forme farmaceutiche orali convenzionali e quelle non convenzionali. L’estrusione per fusione è un processo vantaggioso perché, utilizzando opportuni leganti basso-fondenti, consente la realizzazione di prodotti farmaceutici dotati di forma e dimensioni omogenee; tutto ciò è possibile poiché con l’estrusione si sfruttano sia la termoplasticità dei polimeri sia il rammollimento o la fusione dei carrier non polimerici, per dare origine a matrici all’interno delle quali il farmaco può esser disciolto, intrappolato o disperso sotto forma cristallina. Purtroppo, benché grandi sforzi siano stati intrapresi dalla comunità scientifica per il trasferimento tecnologico del suddetto processo, rimane ancora un compito parzialmente irrisolto a causa del numero elevato di variabili fisiche, chimiche, farmacocinetiche e meccaniche correlate al processo stesso. In correlazione a questo, la prima parte di tesi (Capitolo 2) ha valuto portare un contributo innovativo, dove la preparazione di forme farmaceutiche solide per uso orale ad azione protratta, consiste nella progettazione, formulazione e caratterizzazione di estrusi con una forma non convenzionale, cioè elicoidale, in un estrusore a pistone, composti da teofillina e cera microcristallina come agente matriciale. Gli estrusi ottenuti, sono stati in seguito caratterizzati in vitro, effettuando studi morfologici mediante microscopia elettronica a scansione (SEM), test di dissoluzione, studio dello stato solido utilizzando la calorimetria a scansione differenziale (DSC), la difrattometria a raggi X per polveri (XRPD), analisi del farmaco in superficie mediante spettroscopia di fotoemissione (XPS) e una modellizzazione in vitro-vivo, che si è dimostrata adeguata alla descrizione e alla previsione del meccanismo di rilascio e di assorbimento. Per ciò che concerne l’attivazione meccano-chimica allo stato solido, quest’ultima si basa su processi che consentono di migliorare le “performance” dei principi attivi, caratterizzati da una scarsa solubilità e quindi bassa biodisponibilità. Tale tecnologia consente, infatti, di realizzare la miglior combinazione tra un principio attivo e un materiale “trasportatore”, che permette la realizzazione di materiali compositi, così da aumentarne la biodisponibilità e quindi l’efficacia del prodotto. Nel processo non si utilizzano solventi (processo allo stato solido), ma vengono migliorate le proprietà chimico-fisiche, dove un principio attivo cristallino viene trasformato in amorfo e/o nanocristallo. Una prima applicazione della suddetta tecnologia è stata trattata nella prima parte del Capitolo 3, dove allo scopo di migliorare le performance dissolutive e conseguente assorbimento, due principi attivi cristallini poco solubili quali la vinpocetina e la vincamina sono stati sottoposti ad un processo di comacinazione, in un mulino planetario, in presenza del polivinilpirrolidone reticolato per la vinpocetina, mentre sia del polivinilpirrolidone reticolato che della sodiocarbossimetilcellulosa reticolata per la vincamina. Tale strategia ha permesso di riscontrare l’attitudine di tali materiali al processo di attivazione meccanochimica, l’influenza dei carrier sulla destrutturazione del reticolo cristallino nonché la positiva influenza dei due polimeri sulle proprietà dissolutive e sull’assorbimento per via orale. I compositi ottenuti sono stati caratterizzati mediante microscopia e trasmissione elettronica (TEM), spettroscopia di risonanza magnetica nucleare allo stato solido (SSNMR), DSC, XRPD, Raman spectroscopy/imaging. Una seconda possibile applicazione del processo meccanochimico, a cui viene introdotto il lettore nella seconda parte del Capitolo 3, è la sintesi meccano-chimica allo stato solido. In questo caso tale processo è stato impiegato al fine di promuovere mediante comacinazione in un molino planetario, in opportune condizioni sperimentali, la salificazione della vinpocetina e della vincamina usando quale reagente l’acido citrico. Veniva inoltre valutata la presenza in qualità di diluente adiuvante il polivinilpirrolidone reticolato nel caso della vinpocetina, e della sodio carbossimetilcellulosa per la vincamina. E’ stata preparata un’ampia serie di comacinati, in diverse condizioni sperimentali (differente durata della comacinazione, rapporto molare principio attivo/acido citrico, presenza assenza del diluente) e l’influenza di quest’ultime variabili sul processo di salificazione è stata stimata mediante opportuni design sperimentali, dove la spettroscopia di fotoemissione (XPS) e la microscopia a trasmissione elettronica ad alta risoluzione (HRTEM) hanno permesso di fornire non solo informazioni qualitative e quantitative sul prodotto salificato, ma anche quelle sul meccanismo della reazione di salificazione stessa.
XXV Ciclo
1985