Дисертації з теми "Crystallization systems"
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Saleemi, Ali Nauman. "Strategic feedback control of pharmaceutical crystallization systems." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8530.
Повний текст джерелаSheikh, Ahmad Yahya. "Synthesis, optimisation and control of crystallization systems." Thesis, University College London (University of London), 1997. http://discovery.ucl.ac.uk/1317664/.
Повний текст джерелаMontenegro, Rivelino V. D. "Crystallization, biomimetics and semiconducting polymers in confined systems." Phd thesis, Universität Potsdam, 2003. http://opus.kobv.de/ubp/volltexte/2005/76/.
Повний текст джерелаKristallisation, Biomimetik und halbleitende Polymere in räumlich begrenzten Systemen:
Öl und Wasser mischen sich nicht, man kann aber aus beiden Flüssigkeiten Emulsionen herstellen, bei denen Tröpfchen der einen Flüssigkeit in der anderen Flüssigkeit vorliegen. Das heißt, es können entweder Öltröpfchen in Wasser oder Wassertröpfchen in Öl erzeugt werden. Aus täglichen Erfahrungen, z.B. beim Kochen weiß man jedoch, dass sich eine Emulsion durch Schütteln oder Rühren herstellen lässt, diese jedoch nicht besonders stabil ist. Mit Hilfe von hohen Scherenergien kann man nun sehr kleine, in ihrer Größe sehr einheitliche und außerdem sehr stabile Tröpfchen von 1/10000 mm erhalten. Eine solche Emulsion wird Miniemulsion genannt.
In der Dissertation wurden nun z.B. Miniemulsionen untersucht, die aus kleinen Wassertröpfchen in einem Öl bestehen. Es konnte gezeigt werden, dass das Wasser in diesen Tröpfchen, also in den räumlich begrenzten Systemen, nicht bei 0 °C, sondern bei -22 °C kristallisierte. Wie lässt sich das erklären? Wenn man einen Eimer Wasser hat, dann bildet sich normalerweise bei 0 °C Eis, da nämlich in dem Wasser einige (manchmal ganz wenige) Keime (z.B. Schutzteilchen, ein Fussel etc.) vorhanden sind, an denen sich die ersten Kristalle bilden. Wenn sich dann einmal ein Kristall gebildet hat, kann das Wasser im gesamten Eimer schnell zu Eis werden. Ultrareines Wasser würde bei -22 °C kristallisieren. Wenn man jetzt die Menge Wasser aus dem Eimer in kleine Tröpfchen bringt, dann hat man eine sehr, sehr große Zahl, nämlich 1017 Tröpfchen, in einem Liter Emulsion vorliegen. Die wenigen Schmutzpartikel verteilen auf sehr wenige Tröpfchen, die anderen Tröpfchen sind ultrarein. Daher kristallisieren sie erst bei -22 °C.
Im Rahmen der Arbeit konnte auch gezeigt werden, dass die Miniemulsionen genutzt werden können, um kleine Gelatine-Partikel, also Nanogummibärchen, herzustellen. Diese Nanogummibärchen quellen bei Erhöhung der Temperatur auf ca. 38 °C an. Das kann ausgenutzt werden, um zum Beispiel Medikamente zunächst in den Partikeln im menschlichen Körper zu transportieren, die Medikamente werden dann an einer gewünschten Stelle freigelassen. In der Arbeit wurde auch gezeigt, dass die Gelatine-Partikel genutzt werden können, um die Natur nachzuahnen (Biomimetik). Innerhalb der Partikel kann nämlich gezielt Knochenmaterial aufgebaut werden kann. Die Gelatine-Knochen-Partikel können dazu genutzt werden, um schwer heilende oder komplizierte Knochenbrüche zu beheben. Gelatine wird nämlich nach einigen Tagen abgebaut, das Knochenmaterial kann in den Knochen eingebaut werden.
LEDs werden heute bereits vielfältig verwendet. LEDs bestehen aus Halbleitern, wie z.B. Silizium. Neuerdings werden dazu auch halbleitende Polymere eingesetzt. Das große Problem bei diesen Materialien ist, dass sie aus Lösungsmitteln aufgebracht werden. Im Rahmen der Doktorarbeit wurde gezeigt, dass der Prozess der Miniemulsionen genutzt werden kann, um umweltfreundlich diese LEDs herzustellen. Man stellt dazu nun wässrige Dispersionen mit den Polymerpartikeln her. Damit hat man nicht nur das Lösungsmittel vermieden, das hat nun noch einen weiteren Vorteil: man kann nämlich diese Dispersion auf sehr einfache Art verdrucken, im einfachsten Fall verwendet man einfach einen handelsüblichen Tintenstrahldrucker.
The colloidal systems are present everywhere in many varieties such as emulsions (liquid droplets dispersed in liquid), aerosols (liquid dispersed in gas), foam (gas in liquid), etc. Among several new methods for the preparation of colloids, the so-called miniemulsion technique has been shown to be one of the most promising. Miniemulsions are defined as stable emulsions consisting of droplets with a size of 50-500 nm by shearing a system containing oil, water, a surfactant, and a highly water insoluble compound, the so-called hydrophobe
1. In the first part of this work, dynamic crystallization and melting experiments are described which were performed in small, stable and narrowly distributed nanodroplets (confined systems) of miniemulsions. Both regular and inverse systems were examined, characterizing, first, the crystallization of hexadecane, secondly, the crystallization of ice. It was shown for both cases that the temperature of crystallization in such droplets is significantly decreased (or the required undercooling is increased) as compared to the bulk material. This was attributed to a very effective suppression of heterogeneous nucleation. It was also found that the required undercooling depends on the nanodroplet size: with decreasing droplet size the undercooling increases.
2. It is shown that the temperature of crystallization of other n-alkanes in nanodroplets is also significantly decreased as compared to the bulk material due to a very effective suppression of heterogeneous nucleation. A very different behavior was detected between odd and even alkanes. In even alkanes, the confinement in small droplets changes the crystal structure from a triclinic (as seen in bulk) to an orthorhombic structure, which is attributed to finite size effects inside the droplets. An intermediate metastable rotator phase is of less relevance for the miniemulsion droplets than in the bulk. For odd alkanes, only a strong temperature shift compared to the bulk system is observed, but no structure change. A triclinic structure is formed both in bulk and in miniemulsion droplets.
3. In the next part of the thesis it is shown how miniemulsions could be successfully applied in the development of materials with potential application in pharmaceutical and medical fields. The production of cross-linked gelatin nanoparticles is feasible. Starting from an inverse miniemulsion, the softness of the particles can be controlled by varying the initial concentration, amount of cross-link agent, time of cross-linking, among other parameters. Such particles show a thermo-reversible effect, e.g. the particles swell in water above 37 °C and shrink below this temperature. Above 37 °C the chains loose the physical cross-linking, however the particles do not loose their integrity, because of the chemical cross-linking. Those particles have potential use as drug carriers, since gelatin is a natural polymer derived from collagen.
4. The cross-linked gelatin nanoparticles have been used for the biomineralization of hydroxyapatite (HAP), a biomineral, which is the major constituent of our bones. The biomineralization of HAP crystals within the gelatin nanoparticles results in a hybrid material, which has potential use as a bone repair material.
5. In the last part of this work we have shown that layers of conjugated semiconducting polymers can be deposited from aqueous dispersion prepared by the miniemulsion process. Dispersions of particles of different conjugated semiconducting polymers such as a ladder-type poly(para-phenylene) and several soluble derivatives of polyfluorene could be prepared with well-controlled particle sizes ranging between 70 - 250 nm. Layers of polymer blends were prepared with controlled lateral dimensions of phase separation on sub-micrometer scales, utilizing either a mixture of single component nanoparticles or nanoparticles containing two polymers. From the results of energy transfer it is demonstrated that blending two polymers in the same particle leads to a higher efficiency due to the better contact between the polymers. Such an effect is of great interest for the fabrication of opto-electronic devices such as light emitting diodes with nanometer size emitting points and solar cells comprising of blends of electron donating and electron accepting polymers.
Succaw, Gary Lee. "Dynamics of crystal growth of self-assembling systems /." view abstract or download file of text, 2004. http://wwwlib.umi.com/cr/uoregon/fullcit?p3136448.
Повний текст джерелаTypescript. Includes vita and abstract. Includes bibliographical references (leaves 209-215). Also available for download via the World Wide Web; free to University of Oregon users.
Sultana, Mahmooda. "Microfluidic systems for continuous crystallization of small organic molecules." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59879.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references.
This thesis presents one of the first demonstrations of continuous crystallization in microfluidic devices, and illustrates their use for various applications related to crystallization of small organic molecules. Crystallization is an important process in a number of industries, including specialty chemicals, food, cosmetics, nutraceuticals and, most importantly, pharmaceuticals. Most small molecule pharmaceuticals are isolated in crystalline form, and more than ninety percent of all pharmaceutical products are formulated in particulate, mainly crystalline form. However, crystallization is not a completely understood process. The sensitivity of the process to synthesis conditions gives rise to serious reproducibility issues. The traditional batch crystallizers suffer from non-uniform process conditions across the reactor, and chaotic, poorly controlled mixing of the reagents, often resulting in polydisperse crystal size distribution and impure polymorphs. This makes it difficult to obtain reliable information on the process kinetics that can be used for scale-up, as well as to study the fundamentals of the process. Microfluidic systems offer a unique toolset for crystallization because of well-defined laminar flow profiles, enhanced heat and mass transfer, better control over the contact mode of the reagents, and optical access for in situ characterization. The better control over the synthesis conditions gives rise to the potential for controlling the crystal size, as well as the polymorphic form. In addition, low consumption of reagents makes it an attractive research tool for expensive pharmaceutical compounds. Some of the advantages of microfluidics have been demonstrated for crystallization in micro-batches, but so far not in continuous devices. Continuous crystallization is difficult to achieve in microchannels as uncontrolled nucleation, crystal growth, agglomeration and sedimentation of crystals easily clog the small channels. The interaction of crystals with channel walls may also contribute to channel plugging in these devices. This thesis has developed microfluidic devices for continuous crystallization of small organic molecules for the first time. We have decoupled nucleation and growth, the two key steps of crystallization, using reaction engineering principles, and have developed two separate continuous devices, one for each of these two processes. We have used seeded crystallization and reactor design to achieve controlled growth, as well as to suppress secondary nucleation, agglomeration and sedimentation of crystals. In addition, we have eliminated any significant interaction of crystals with channel walls by controlling the properties of channel surfaces. We have also integrated microscopy and spectroscopy tools with the device for in-situ characterization of crystal size and polymorphic form. We have illustrated the use of these devices to extract growth kinetics data for crystals of various shapes, including high aspect ratio systems such as that with acicular or plate-like habits. The reproducibility and control in our devices have allowed us to elucidate the growth mechanism and fundamentals of the growth process for difficult crystal systems. In addition, we have demonstrated that continuous microfluidic devices offer a unique advantage over the current state-of-the art technology to measure the size, size distribution and growth kinetics of high aspect ratio crystal systems more accurately. Moreover, we have demonstrated the use of microfluidic devices for understanding crystal habit modification in the presence of impurities. We take advantage of the high spatiotemporal resolution of microfluidic devices to study the evolution of crystal habit over time, and to obtain information on the kinetics of habit modification in the presence of different impurities. We have developed an understanding of the habit modification mechanism for alpha glycine in the presence of alpha amino acids. Such information may not only provide insights into impurity-crystal interactions, but also serve as a powerful tool for the design of impurities that can be deliberately added to improve the crystallization process. Furthermore, we have designed and developed a second microfluidic device for continuous supercritical crystallization for the first time. Using supercritical fluid as an antisolvent, we have demonstrated continuous spontaneous nucleation of acetaminophen. We have shown the ability to produce micron-sized crystals, which may be useful for increasing the bioavailability of drugs with lower solubility, as well as for inhalable and highly potent drugs with stringent size requirements. The developed platform can also be used as a high-throughput device for safely screening crystallization conditions in the supercritical domain. We have demonstrated such use by screening the effects of pressure and various solvents on the habit, size and polymorphic form of acetaminophen crystals.
by Mahmooda Sultana.
Ph.D.
Chavez, Krystle J. "Crystallization of pseudopolymorphic forms of sodium naproxen in mixed solvent systems." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29759.
Повний текст джерелаCommittee Chair: Rousseau, Ronald; Committee Member: Meredith, Carson; Committee Member: Prausnitz, Mark; Committee Member: Teja, Amyn; Committee Member: Wilkinson, Angus. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Antonello, Alice [Verfasser]. "Crystallization of complex inorganic systems within the confinement of miniemulsion droplets / Alice Antonello." Mainz : Universitätsbibliothek Mainz, 2017. http://d-nb.info/1136638776/34.
Повний текст джерелаShank, Dale. "Evaluating carbon dioxide as a causative agent of otolith crystallization in recirculating aquaculture systems." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1603716784275007.
Повний текст джерелаBöbel, Alexander [Verfasser], and Gregor [Akademischer Betreuer] Morfill. "Crystallization and demixing: morphological structure analysis in many-body systems / Alexander Böbel ; Betreuer: Gregor Morfill." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2018. http://d-nb.info/1173616233/34.
Повний текст джерелаCarr, Joel Matthew. "CONFINED LAYERED POLYMERIC SYSTEMS FOR PACKAGING ANDCAPACITOR APPLICATIONS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1363104386.
Повний текст джерелаSimone, Elena. "Application of process analytical technology (PAT) tools for the better understanding and control of the crystallization of polymorphic and impure systems." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/20098.
Повний текст джерелаHu, Yushan. "OXYGEN TRANSPORT AS A STRUCTURE PROBE FOR HETEROGENEOUS POLYMERIC SYSTEMS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1112902488.
Повний текст джерелаErdiller, Emrah Salim. "Investigation Of Solidification And Crystallization Of Iron Based Bulk Amorphous Alloys." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/1096585/index.pdf.
Повний текст джерела#65533
Based bulk amorphous alloys, to synthesize Fe &
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based multicomponent glassy alloys by using the predictions of the theoretical study, and to analyze the influence of crystallization and solidification kinetics on the microstructural features of this amorphous alloys. For this purpose, first, glass forming ability of Fe &
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(Mo, B, Cr, Nb, C) &
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X ( X = various alloying elements, selected from the periodic table) ternary alloy systems were simulated for twenty different alloy compositions by using the electronic theory of alloys in pseudopotential approximation and regular solution theory. Then, by using the results of the theoretical study, systematic casting experiments were performed by using centrifugal casting method. The alloying elements were melted with induction under argon atmosphere in alumina crucibles and casted into copper molds of different shapes. Characterization of the cast specimens were performed by using DSC, XRD, SEM, and optical microscopy. Comparison of equilibrium and nonequilibrium solidification structures of cast specimens were also performed so as to verify the existence of the amorphous phase. Good agreement of the results of experimental work, with the predictions of the theoretical study, and the related literature was obtained.
Lundin, Josefin. "Investigation of How Different Fat Systems and Other Ingredients Affect the Properties of Whipping Creams Based on Vegetable Fat." Thesis, Linnéuniversitetet, Institutionen för kemi och biomedicin (KOB), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-27209.
Повний текст джерелаClogston, Jeffrey. "Applications of the lipidic cubic phase from controlled release and uptake to in meso crystallization of membrane proteins /." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1117564268.
Повний текст джерелаTitle from first page of PDF file. Document formatted into pages; contains xxii, 352 p.; also includes graphics. Includes bibliographical references (p. 346-352). Available online via OhioLINK's ETD Center
Vialetto, Jacopo. "Interface-driven soft matter systems : from 2D particle crystallization and light-responsive assemblies to magnet-guided fluid transport." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS358.
Повний текст джерелаSoft materials interacting at/with liquid interfaces are of great scientific interest because of the multiple weak forces at play that dictate their, often surprising, arrangement and behaviour. In this thesis, we studied novel phenomena and actuating principles for the control of the structure (organization) and dynamics (motion) of soft matter systems at liquid interfaces, from the directed assembly of thousands of solid particles, to the manipulation of small floating drops. We established the first method to both adsorb and crystallise nm- to µm-sized particles at air/water interface, evidencing a new role of surfactants to control two-dimensional (2D) particle organization at extremely low surfactant concentration. We then programmed such 2D assemblies in order to control particle organization with light stimulation, devising two innovative strategies. Using light-absorbing particles allowed us to construct reconfigurable ordered structures (light-controlled inter-particle distance and disassembly). With ordinary particles and photosensitive surfactant, we demonstrated a new kind of dissipative 2D crystals (light-induced organization through continuous consumption of energy). In parallel, we conceived a novel magnetic actuation method for the manipulation of small liquid entities (drops, liquid marbles) by means of deformable paramagnetic liquid substrates, shaping the liquid surface with small permanent magnets and in turn directing the motion of water and oil drops in a user-defined fashion
Esposito, Rosario. "Studies of volatile evolution in magmatic systems using melt inclusions." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28287.
Повний текст джерелаPh. D.
Sharma, Satyajeet. "AMORPHOUS PHASE FORMATION IN MECHANICALLY ALLOYED FE-BASED SYSTEMS." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2484.
Повний текст джерелаPh.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science & Engr PhD
Lucas, Bruce. "Fundamental Modeling of Solid-State Polymerization Process Systems for Polyesters and Polyamides." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29378.
Повний текст джерелаPh. D.
Shah, Zulfiqar Hussain. "Synthesis and Characterizations of Fe-based Metallic Glassy Systems." Thesis, KTH, Materialvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37395.
Повний текст джерелаTam, Le Minh [Verfasser]. "Designing crystallization based-enantiomeric separation for chiral compound-forming systems in consideration of polymorphism and solvate formation / Le Minh Tam." München : Verlag Dr. Hut, 2014. http://d-nb.info/1052374735/34.
Повний текст джерела[Verfasser], Le-Minh-Tam. "Designing crystallization based-enantiomeric separation for chiral compound-forming systems in consideration of polymorphism and solvate formation / Le Minh Tam." München : Verlag Dr. Hut, 2014. http://nbn-resolving.de/urn:nbn:de:101:1-2014062022375.
Повний текст джерелаHernandez, Lindsey Danielle. "Magma Plumbing Systems along the Juan de Fuca Ridge." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587630136962186.
Повний текст джерелаQuerniard, Florian. "Thermodynamic study of organic heterogeneous systems : improvement of discontinuous isoperibolic thermal analysis, and use of phase diagrams to design enantiomeric resolutions by crystallization." Rouen, 2010. http://www.theses.fr/2010ROUES026.
Повний текст джерелаThe work presented consists of thermodynamic study of organic heterogeneous systems. Discontinuous Isoperibolic Thermal Analysis (DITA), an experimental technique dedicated to phase diagram investigation has been improved in three aspects. First, it has been demonstrated that the sign of slope breaks, which are characteristic of phase domain boundary crossing, indicates the direct or retrograde behaviour of these boundaries. Then, the uncertainty of DITA results has been estimated through an inventory of error sources and repeatability tests. Finally, a new automation and processing software has been developed to make the technique more accessible. The influence of resolving agent amount on enantiomer resolution by diastereomeric salts has been studied based on phase diagrams. It has been demonstrated that on favourable cases, the amount of resolving agent can be reduced to less than a half equivalent without efficiency loss. This reduction comes with an economy of solvent and reactor size. The resolution of (±)-CF361H by various amount of αMBA in ethanol is given as experimental example. A new resolution route for phencyphos has been found through preferential crystallization of its monohydrate. This new process has been designed and optimized with the help of phase diagram knowledge. It has been upscaled successfully to 35 litres. 30kg of each enantiomer have been produced
[Verfasser], Le-Minh-Tam, and Andreas [Akademischer Betreuer] Seidel-Morgenstern. "Designing crystallization based-enantiomeric separation for chiral compound-forming systems in consideration of polymorphism and solvate formation / Tam Le Minh. Betreuer: Andreas Seidel-Morgenstern." Magdeburg : Universitätsbibliothek, 2014. http://d-nb.info/105791391X/34.
Повний текст джерелаBai, Xianming. "Thermodynamics and Kinetics of Phase Transitions during Supercooling and Superheating: A Theoretical and Computational Investigation in Model Lennard-Jones Systems." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-11132006-110828/.
Повний текст джерелаMartha A. Gallivan, Committee Member ; Andrei G. Fedorov, Committee Member ; Christopher Summers, Committee Member ; Thomas H. Sanders, Jr., Committee Member ; Mo Li, Committee Chair.
Zago, Gustavo Pereira. "Estudo da co-cristalização em sistema ternário NaCI-CaSO4-H2O para dessalinização de água." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-15012018-132007/.
Повний текст джерелаThe accelerated growth of the world population and the consequent increase in the production of consumer goods, has driven to a crisis in the availability of natural resources, especially water. Due to the scarcity of water resources, industrial and domestic wastewater treatment processes that aim the Zero Liquid Discharge (ZLD) have been increasingly studied. Nowadays, several processes have been used for this purpose. However, in all of them, there is still the generation of a brine composed of a concentrated salt solution, concomitantly with the recovered water, whose composition is normally constituted by different types of inorganic salts. One way to achieve the ZLD is through the implementation of an additional separation process, for which the evaporative crystallization is considered technically viable for this purpose. The use of this process is limited to the control of the morphological characteristics of the particles obtained, since this influences directly the separation effectiveness of the downstream processes to crystallization (filtration, centrifugation). Besides, industrial effluents are complex solutions and its crystallization involves the presence of more than one salt in solution (cocrystallization). This process is still not well investigated on scientific literature, thus, the determination of process conditions aiming to control the characteristics of these particles is not trivial. In this work, the effect of the evaporation rate and the presence of seeds on the morphology, composition, size and habit of sodium chloride and calcium sulfate particles obtained by batch evaporative co-crystallization were studied. The results were used to determine the operating parameters for the cocrystallization in order to obtain particles with high average size and narrow dispersion of sizes. High evaporation rates favored the obtaining of agglomerated particles. The presence of calcium sulfate in solution resulted in larger particles, less polydisperse and with less degree of agglomeration. Such result was considered positive, since, these characteristics are desirable for the separation of the crystals from the solution. Seeds of hemihydrate inhibited the agglomeration of the NaCl crystals. The increase in seed load of hemihydrate culminated in obtaining less agglomerated particles, but there was an increase in particle size distributions. In the experiments in which seeds of both salts were used, the same effect in the agglomeration was observed. In all experiments with seeds of hemihydrate, agglomeration of this salt with NaCl was observed, which was intensified with increasing evaporation rate and increasing seed amount. It was identified the possibility of recovery of both salts and, for certain conditions, obtaining more than 90% of NaCl with up to 99.50% purity.
Angelin, Marcus. "Discovery-Oriented Screening of Dynamic Systems: Combinatorial and Synthetic Applications." Doctoral thesis, KTH, Organisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12524.
Повний текст джерелаQC 20100628
Lin, JiaCheng, and HaoRan Teng. "Influence of Nucleation Techniques on the Degree of Supercooling and Duration of Crystallization for Sugar Alcohol as Phase Change Material : Investigation on erythritol-based additiveenhanced Composites." Thesis, KTH, Energiteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-257758.
Повний текст джерелаAtt använda fasändringsmaterial (PCM) för termisk energilagring i form av latent värme (LTES) har tidigare extensivt forskats och undersökts som en lösning för att minska utsläppen av växthusgaser från energiförbrukning. För att utnyttja spillvärme från industriella processer för LTES-ändamål uppstod en efterfrågan på PCM som ändrar fas i temperaturer mellan 100 °C - 200 °C. Detta krav på högre temperatur gjorde att de flesta av de tidigare aktuella materialen inte kunde tillämpas eftersom de hade mycket lägre smält- och kristalliseringstemperaturer. Med detta i åtanke har en ny generation av PCM bestående av sockeralkoholer (SA) föreslagits. Erytritol ses som ett särskilt lovande SA med goda egenskaper för LTES-ändamål. Den har dock visat sig drabbas av svår underkylning, vilket gör den opålitligt i verkliga tillämpningar. För att utrota detta problem blandades två tillsatser, Graphene Oxide (GO) och Polyvinylpyrrolidone (PVP) vid olika massfraktioner med ren erytritol för att bilda en komposit som studerades med metoden Temperature-history (T-history) för att bestämma dess effektivitet på att minska underkylningen. Resultaten visar att GO på sin mest effektiva massfraktion minskar underkylningen med 28 o C och tillsats av PVP lyckats minska den med som mest 31 o C. Påverkningarna på varaktighet av kristallisering dokumenterades och analyserades med samma metod. Det var observerad att varaktigheten av kristallisering ökades med ökande massfraktioner av tillsatserna. Även andra viktiga egenskaper hos kompositerna studerades för att avgöra rimligheten att använda dessa för industriella tillämpningar. Det inkluderar analys av lagringskapaciteten genom latent värme, förändringar i viskositet tillsammans med påverkan på kompositernas termiska diffusivitet.
Oak, Milind Prabhakar. "Virtual customer driven product design crystallization." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91722.
Повний текст джерелаÁlvarez, Marimón Mª Elena. "Structural studies of Heteromeric Amino acid Transporters (HATs): Validation of the first 3D structural model of a HAT (human 4F2hc/LAT2) and identification of new HAT targets for 3D‐crystallization." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284082.
Повний текст джерелаLos transportadores heteroméricos de aminoácidos (HAT) median el transporte de aminoácidos a través de la membrana plasmática. Representan el único ejemplo de transportadores de solutos formado por dos subunidades distintas unidas por un puente disulfuro. Debido a su gran relevancia en fisiología (asociados a aminoacidurias, infección por virus, cáncer,…) el estudio de su estructura-función resulta clave. Debido a su naturaleza, son proteínas difíciles de cristalizar, de las que sólo se conoce la estructura atómica del ectodominio de 4F2hc humano. En este escenario la tesis se centró en la validación del primer modelo 3D a baja resolución de un HAT humano (4F2hc/LAT2), mediante experimentos de crosslinking entre subunidades, e identificación de nuevos candidatos para cristalización 3D. Para ello se seleccionaron 24 subunidades ligeras de distintas especies eucariotas y se testaron en un proceso de selección para determinar el/los mejores candidatos. El primer objetivo de la tesis concluyó con la determinación de residuos concretos en 4F2hc y LAT2 cercanos a una distancia de 3-14 Å mediante la utilización de crosslinkings de cisteínas. Finalmente, tres líneas distintas: el modelo 3D obtenido por microscopía electrónica de transmisión y tinción negativa de partículas individuales (en colaboración con Dr. Fotiadis), los experimentos de crosslinking, y el docking generado en colaboración con Dr. Fdz-Recio, demostraron que 4F2hc-ED cubre, casi completamente, la superficie extracelular de LAT2. Además, se demostró que el ectodominio de 4F2hc es suficiente para estabilizar LAT2. Como resultados del segundo objetivo, tres subunidades ligeras fueron seleccionadas, tras adaptar el protocolo desarrollado por Drew et al.,2008, como mejores candidatas para estudios de cristalización 3D. Posteriormente, distintas estrategias se siguieron para mejorar la estabilidad de la mejor candidata: eliminación de la cisteína reactiva, adición de lípidos a la muestra, cambio de sistema de expresión para aumentar su expresión a células de insecto Sf9. Además, se generaron mutantes delecionados en N y C terminal para reducir su flexibilidad y aumentar la probabilidad de cristalización. Se concluyó en encontrar un buen candidato para estudios de cristalización.
PINHEIRO, LUCAS B. "Síntese e caracterização de compósitos de NiO-YSZ-CeOsub(2) com tratamento hidrotermal assistido por micro-ondas." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10574.
Повний текст джерелаMade available in DSpace on 2014-10-09T14:04:41Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Ibrahim, Mohamed Asim Y. "Co-processing of drugs and co-crystal formers and its effect on pharmaceutical dosage-form performance. Co-crystallization of urea/ 2-methoxybenzamide, caffeine/ malonic acid, caffeine/ oxalic acid and theophylline/ malonic acid systems: Solid-state characterization including imaging, thermal, X-ray and Raman spectroscopic techniques with subsequent evaluation of tableting behaviour." Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/12760.
Повний текст джерелаIslamic University of Omdurman and the Ministry of Higher Education in Sudan
Ibrahim, Mohamed Asim Yousif. "Co-processing of drugs and co-crystal formers and its effect on pharmaceutical dosage-form performance : co-crystallization of urea/2-methoxybenzamide, caffeine/malonic acid, caffeine/oxalic acid and theophylline/malonic acid systems : solid-state characterization including imaging, thermal, X-ray and Raman spectroscopic techniques with subsequent evaluation of tableting behaviour." Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/12760.
Повний текст джерелаWollmann, Georgia. "Crystallization Fields of Polyhalite and its Heavy Metal Analogues." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2010. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-32906.
Повний текст джерелаBoulay, Emilie. "Amorphous phase separation and crystallization in the BaO-TiO2-SiO2 system: experimental approach and thermodynamic study." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209133.
Повний текст джерелаThe first system BaO-TiO2-SiO2 has gathered interest from the interesting properties of fresnoite (Ba2TiSi2O8): piezo and pyroelectricity, second harmonic generation and blue/white photoluminescence. Many studies on the stoichiometric composition were conducted to understand and improve those promising properties. However, it was recently suggested that the photoluminescence can be improved with composition exhibiting phase separation. This indicates that the photoluminescence intensity can be improved through a microstructural control. The possible role of a prior amorphous phase separation on the subsequent crystallization has been however the topic of vigorous debates over the last decades and has not yet been clarified, especially regarding the role of the interfaces created by the phase separation. In this PhD, the effect of phase separation on fresnoite crystallization was studied. This had to pass through the calculation of the liquid-liquid immiscibility in the phase diagram in order to select suitable compositions to compare in a systematic study. The systematic study concludes to a surface crystallization mechanism for all non- stoichiometric compositions and shows no influence between amorphous droplets and matrix crystallization. This study was also completed with the investigation of the effect of composition (i.e. SiO2-excess), annealing temperature and prior heat treatment, i.e. heating rate, cooling rate or a prior isothermal step before annealing. It is shown that specific microstructures are obtained depending on the process parameters. Finally, selected compositions and heat treatment show how photoluminescence intensity can be improved by a microstructural control. The highest intensity is obtained with a high crystallization fraction and a maximization of the number of interfaces.
The results obtained in the study of the BaO-TiO2-SiO2 system are extended to the soda-lime-silica system in order to study the effect of phase separation on crystallization. It is shown that cristobalite forma- tion from the surface cannot be avoided and that the involved composition shift inhibits phase separation. It is consequently difficult to observe an interplay. Those studies lead to a general discussion about the criteria allowing to observe an interplay between phase separation and crystallization in oxide glasses.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Zeng, Jianming. "Constrained crystallization and depletion in the polymer medium for transdermal drug delivery system." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5102.
Повний текст джерелаKim, Seong-Jin. "Directional crystallization in the bismuth-strontium-calcium-copper-oxygen system: Effect of phase separation." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/186040.
Повний текст джерелаTaylor, Donald Fulton. "Measurement of binary phase equilibria and ternary/quaternary gas antisolvent (GAS) system measurement and analysis." Thesis, Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-07112004-194307/unrestricted/taylor%5Fonald%5Ff%5F200407%5FMS.pdf.
Повний текст джерелаCharles Eckert, Committee Chair ; Amyn Teja, Committee Member ; Pete Ludovice, Committee Member. Includes bibliographical references.
Getson, Jacqueline. "Effect of plagioclase crystallization on liquid and magma viscosity in the Anorthite-diopside-dorsterite-quartz system." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4628.
Повний текст джерелаThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (June 25, 2007) Includes bibliographical references.
Liu, Lei. "The link between convection and crystallization in a sub-axial magma chamber and heat output in a seafloor hydrothermal system." Thesis, Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-07072007-142506/.
Повний текст джерелаRowland-Smith, Andrea. "The 1630 AD eruption of Furnas Volcano, São Miguel, Azores (Portugal): chemical variations and magmatic processes." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1186143145.
Повний текст джерелаStanojevic, Sanja [Verfasser], and Ralf [Akademischer Betreuer] Busch. "Processing, crystallization and oxidation of the Ni-Nb(-Sn) refractory alloy glass system / Sanja Stanojevic. Betreuer: Ralf Busch." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2013. http://d-nb.info/1053681666/34.
Повний текст джерелаXiao, Yi. "Structural study of ExsA, the regulator of Type III Secretion System of Pseudomonas aeruginosa." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/50944.
Повний текст джерелаMaster of Science
Mina-Mankarios, George. "Crystallization kinetics of sodium sulphate in a salting out MSMPR crystallizer system Na₂SO₄/H₂S0₄/H₂O/MeOH /." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/42007.
Повний текст джерелаApplied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
Zheltonozhskaya, T. B., S. V. Partsevskaya, D. O. Klymchuk, and V. F. Gorchev. "Specific Interactions and Crystallization of Drug-Loaded Micelles in the System: Prednisolon/PAAm-b-PEO-b-PAAm Micellar Solutions." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35235.
Повний текст джерелаGallo, Leonardo Sant'ana. "Microstructure and mechanical properties of glass-ceramics from the MgO-Al₂O₃-SiO₂ system for ballistic protection." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S063/document.
Повний текст джерелаIn situ experiments were conducted on a glass dubbed 75-25, of the MgO-Al2O3-SiO2 (MAS) system, using TiO2 as the main nucleating agent, in order to examine the evolution of Young’s modulus (E), shear modulus (G) and Poisson's ratio, and the sequence of the crystalline phases formed during a double-stage heat treatment. The effects of crystallization on hardness and fracture toughness were also examined. High temperature X-ray diffraction experiments revealed the presence of spinel (MgO.Al2O3), rutile (TiO2), karooite (MgO.2TiO2), sillimanite (Al2O3.SiO2) and sapphirine (4MgO.5Al2O3.2SiO2) after crystallization. The elastic and shear moduli of the glass-ceramics (GC) were approximately 20% larger than those of the parent glass. Hardness values were close to 10 GPa and KIC close to 1.2 MPa.m1/2. Aiming to obtain transparent and colorless GC, new formulations, dubbed ZT1B4, 75-25/ZT and 75-25/25Ti, with lower titania content and higher zirconia content, were proposed and crystallized. Formulation ZT1B4 yielded a transparent GC with hardness of up to 8 GPa and an indentation fracture toughness (IFT) about 40% higher than that of the parent glass. Formulations 75-25/ZT and 75-25/25Ti yielded transparent GC with hardness values of up to 9 GPa and an IFT up to 35% higher than that of the parent glass. A series of glasses were also melted using metallic Ag as nucleating agent instead of ZrO2 and TiO2. The applied heat treatments generated non-homogeneous GC, which became warped due to the high crystallization temperatures. These new precursor glasses were therefore discarded. Transmittance in the ultraviolet to visible range was measured in the glass and GC samples of formulations 75-25, 75-25/ZT and 75-25/25Ti. Formulation 75-25/ZT presented the highest transmittance in both glass and GC states. It was concluded that among the new compositions, formulation 75-25/ZT is the most suitable one for use as ballistic protection when transparency to visible light is required
Araújo, Hugo Valença 1988. "Simulação e análise do desempenho termodinâmico de sistemas de refrigeração por absorção com diferentes configurações." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266566.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-23T08:54:55Z (GMT). No. of bitstreams: 1 Araujo_HugoValenca_M.pdf: 2457535 bytes, checksum: cf5a800ee51a5605b7d2cd69248ef52c (MD5) Previous issue date: 2013
Resumo: A refrigeração e o condicionamento de ar representam um campo tecnológico em potencial para a adoção de medidas de economia de eletricidade. Nesse sentido, Sistemas de Refrigeração por Absorção (SRAs) figuram como uma opção interessante por serem adequados à produção de frio mediante um gasto significativamente menor de energia elétrica em comparação a Sistemas de Refrigeração por Compressão Mecânica (SRCMs) de vapor. Com a finalidade de gerar o efeito de refrigeração, o SRCM realiza uma compressão mecânica de vapor à custa do consumo de trabalho elétrico em um compressor; em contrapartida, a compressão no SRA é de natureza termofísica/química e promovida por energia térmica. No segmento de açúcar e álcool brasileiro, a etapa determinante da produção de etanol a partir da cana consiste na fermentação alcoólica do mosto em dornas. Tal etapa é exotérmica e, uma vez que a elevação descontrolada da temperatura desfavorece a produção de álcool, há a necessidade de remover o calor gerado por meio do resfriamento do meio em fermentação. Dessa forma, o objetivo geral do presente trabalho foi simular e analisar o desempenho termodinâmico (energético, COP, e exergético, ?ex) de SRAs com diferentes configurações, trabalhando com o par água/brometo de lítio (H2O/LiBr) e que satisfaçam a carga de refrigeração demandada por um processo fermentativo. Adicionalmente, um dos objetivos específicos foi investigar o risco de ocorrência da cristalização do LiBr, a qual resulta em depósitos, com o auxílio da curva de equilíbrio sólido-líquido (solubilidade) do par H2O/LiBr. As análises dos efeitos de variáveis de projeto e operação (realizadas no software Engineering Equation Solver - EES) demonstraram que os valores de COP das configurações de SRAs de duplo efeito são significativamente maiores do que aquele da configuração de simples efeito; no entanto, as eficiências exergéticas de todas as configurações são equiparáveis, o que pode ser atribuído à quantidade e à qualidade da energia térmica consumida nos respectivos geradores de primeiro efeito. Baixos desempenhos de Segunda Lei são devidos principalmente ao absorvedor, pois esse equipamento apresenta os maiores defeitos de eficiência em todos os SRAs estudados. Adicionalmente, avaliou-se a dependência do desempenho termodinâmico quanto às efetividades de trocadores de calor intermediários, a diferenças de pressão operacional e à cessão direta de calor externo a geradores de segundo efeito. Entre outros resultados, observou-se a existência de máximos do COP e da ?ex em função da temperatura no gerador de primeiro efeito. No que se refere à possibilidade de precipitação do LiBr, verificou-se menor iminência no SRA de duplo efeito com fluxo em paralelo. Em particular, observou-se que aumentos excessivos da temperatura no gerador de primeiro efeito, além de não favorecerem o desempenho termodinâmico, tornam o risco de cristalização do LiBr mais significativo
Abstract: Refrigeration and air conditioning represent a potential technological field for the adoption of measures to save electricity. In this way, Absorption Refrigeration Systems (ARSs) are an interesting option because they are suitable for the production of cold utilities with a significantly lower cost of electric power compared to Mechanical Compression Refrigeration Systems (MCRSs). In order to generate the cooling effect, the MCRS performs a mechanical vapor compression at the expense of the consumption of electrical work in a compressor. On the other side, the nature of the compression in ARSs is thermo physical/chemical and this process is promoted by thermal energy. In the Brazilian sugar and ethanol industry, the main stage of ethanol production from sugarcane is the alcoholic fermentation in vats. This stage is exothermic and since the uncontrolled elevation of temperature results in disadvantages to the ethanol production, it is necessary to remove the heat generated by the cooling of the fermentation medium. Thus, the general objective of this study was to simulate and analyze the thermodynamic performance (energy, COP, and exergy, ?ex) of ARSs with different configurations, working with the water/lithium bromide (H2O/LiBr) mixture, and satisfying the cooling load demanded by a fermentation process. Additionally, one of the specific objectives was to investigate the risk of LiBr crystallization, resulting in deposits, with the aid of the solid-liquid equilibrium (solubility) curve of the H2O/LiBr mixture. Analyses of the effects of design and operating variables (executed in the software Engineering Equation Solver - EES) have shown that the values of COP of the double effect configurations are significantly greater than that of the simple effect configuration; however, the exergetic efficiencies of all configurations are comparable, which can be attributed to the quantity and the quality of the energy consumed in the respective first effect generators. Low Second Law performances are mainly due to the absorber because this equipment has the highest efficiency defects in all ARSs studied. Additionally, it was evaluated the dependence of the thermodynamic performance regarding to the effectivenesses of intermediate heat exchangers, the differences in operating pressures and the direct supply of external heat to second effect generators. Among other findings, it was observed the existence of maximums of COP and ?ex as functions of the temperature in the first effect generator. With regard to the possibility of LiBr precipitation, it was verified lower imminence in the double effect ARS with parallel flow. In particular, it was observed that excessive rises in the temperature in the first effect generator, besides not favor the thermodynamic performance, makes the risk of LiBr crystallization more significant
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
Vicard, Céline. "Étude et modélisation de la synthèse du polyamide 6 pour la mise en œuvre de composites thermoplastiques par voie liquide réactive." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2018. http://www.theses.fr/2018EMAC0001/document.
Повний текст джерелаLiquid type processes (RTM, LRI) for thermoplastic composites manufacturing is one of the most promising routes to overcome the limitations due to the high viscosity of thermoplastic polymers. In this process, the matrix is obtained via in situ polymerization of its low-viscosity monomer after impregnation of the fibrous reinforcement. This study focused on polyamide 6 (PA6) obtained by anionic ring-opening polymerization of ε-caprolactam. The distinctive aspect of this reaction resides in the coupling between chains polymerization and their crystallization, both thermo-dependent, exothermic and driving the viscosity of the reactive mixture.The kinetic characterization of this coupling by DSC allowed for a better understanding of phenomena interaction, revealing notably a specific crystallization kinetic at low temperature. This database, complemented by a study of physicochemical properties of synthesized PA6, has been used to model the underlying phenomena. A new coupling equation has been proposed to take into account the crystallization dependence on the polymerization kinetic, allowing to edit Time-Temperature-Transformation (TTT) diagrams of the PA6 synthesis. Simulations of the thermokinetic coupling with a source term have been performed, highlighting the impact of these exothermic phenomena on thermal and kinetic gradient in the thickness of a part. To reproduce the conditions of the composite manufacturing process, kinetics have also been studied in the presence of glass fibers and in a rheometer. The presence of fibers leads to slower kinetics and the rheokinetic behavior revealed gelation. These observations have to be considered to simulate the reactive system flow in a reinforcement
Zhang, Kun. "Contrôle de l'évolution d'un procédé de cristallisation en batch gouverné par des équations aux dérivées partielles." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00965757.
Повний текст джерела