Author: Diana K. Denzer
Publisher:
ISBN:
Category : Metallic glasses
Languages : en
Pages : 316

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Author: Hemlata Senapati
Publisher:
ISBN:
Category : Crystallization
Languages : en
Pages : 158

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Author: Wade H. Shafer
Publisher: Springer
ISBN: 9780306416613
Category : Science
Languages : en
Pages : 354

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Book Description
This series lists applicable thesis titles published in the United States and Canada. Volume 40 covers thesis year 1995. All back volumes are still available.

Author:
Publisher:
ISBN:
Category : Nuclear energy
Languages : en
Pages : 1144

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Author: University of Wisconsin. Engineering Experiment Station
Publisher:
ISBN:
Category :
Languages : en
Pages : 164

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Author: Mark Stringe
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: University of Wisconsin--Madison. Engineering Experiment Station
Publisher:
ISBN:
Category : Engineering
Languages : en
Pages : 408

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Author: American Ceramic Society
Publisher: Columbus, Ohio : American Ceramic Society
ISBN:
Category : Crystallization
Languages : en
Pages : 140

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Author: S Steeb
Publisher: Elsevier
ISBN: 0444601112
Category : Technology & Engineering
Languages : en
Pages : 1163

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Book Description
Rapidly Quenched Metals, Volume I covers the proceedings of the Fifth International Conference on Rapidly Quenched Metals, held in Wurzburg, Germany on September 3-7, 1984. The book focuses on amorphous and crystalline metals formed by rapid quenching from the melt. The selection first covers the scope and trends of developments in rapid solidification technology, rapid solidification, and undercooling of liquid metals by rapid quenching. Discussions focus on experimental method, powders, strip, particulate production, consolidation, and alloys and alloy systems. The text then examines the solidification of undercooled liquid alloys entrapped in solid; crystallization kinetics in undercooled droplets; and grain refinement in bulk undercooled alloys. The manuscript tackles the undercooling of niobium-germanium alloys in a 100 meter drop tube; influence of process parameters on the cooling rate of the meltspinning process; and the mechanism of ribbon formation in melt-spun copper and copper-zirconium. The formation and structure of thick sections of rapidly-solidified material by incremental deposition and production of ultrafine dispersions of rare earth oxides in Ti alloys using rapid solidification are also mentioned. The selection is a valuable reference for physicists, chemists, physical metallurgists, and engineers.

Author: Guadalupe Natalia Ruiz
Publisher:
ISBN:
Category :
Languages : en
Pages : 162

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Book Description
Glassy phases play an important role in our daily life and in many industries such as the food, pharmaceutical, and construction and are responsible for certain vital mechanisms in living species. Whereas crystals are solid phases that show periodicity of the constituent atoms or molecules, glasses are disordered solids that lack long-range positional order but behave mechanically like solids. Chapter 1 of the current thesis presents an introduction to the characteristics and dynamics of glassy phases. How they are derived from the liquid phase, and how they transform into the crystalline solid phase, thermodynamically more stable. The temperature at which a liquid transforms to the amorphous (glassy) phase is called the glass transition temperature, Tg. Along this thesis the relaxation dynamics of prilocaine (PLC) and stiripentol (STP), and the isothermal crystallization process of the latter have been experimentally studied. Both PLC and STP are drugs used in medical applications mainly as anesthesia and for the treatment of epilepsy, respectively. The studied materials have been analyzed by Broadband Dielectric Spectroscopy (BDS), Differential Scanning Calorimetry, X-Ray diffraction, Raman and I.R spectroscopy and confocal microscopy. The physical principles of BDS, the main experimental tool employed, are presented in Chapter 2. The details of the experimental set-ups are stated in Chapter 3. In the case of a pharmaceutical product, being able to control and foresee the aggregation phase and dissolution rate of the substance is vital. Many drugs are poorly soluble in water and thus, in biological media. The glass state of a drug is a non-equilibrium state that presents higher free energy than the crystal. This implies, that a glassy drug dissolves more rapidly and can be absorbed in larger amounts. Nevertheless, the higher free energy of glassy phases represents at the same time a major problem for shelf-life, since metastable phases are prone to spontaneously transforming into the stable crystalline state. This is a major problem, since wrong dosage or agglomeration of a drug could render it useless or toxic for the human body. Understanding the glass and crystallization dynamics of drugs, and their interaction with water is key to develop more efficient products. Water is the universal biological solvent. For most materials the addition of water leads to a decrease in viscosity, or equivalently, an increase of molecular mobility, resulting in a lower glass transition temperature Tg (the higher the water content the lower the Tg). This is referred to as the plasticizing effect of water. Chapter 4 presents a detailed analysis of both pure and hydrated prilocaine. Results show that the addition of water to PLC leads to the formation of PLC-water complexes, possibly water-bridged monomers or dimers that increase Tg. This antiplasticizing effect of water on the molecular mobility of a simple glass former represents a significant exception to the alleged universality of water as drug plasticizer. The physico-chemical origins of this behavior have been confirmed by studying the effect of confinement of the pure and hydrated drug in the pores of a nonporous structure (Chapter 5). In the case of STP, not only the glassy dynamics were studied, but also the crystallization process (Chapter 6). A sublinear correlation between the characteristic crystal-growth time and the relaxation time of the cooperative relaxation dynamics of stiripentol was found. This correlation was observed also in other substances, which suggests that it is a general correlation at temperatures above Tg. This may allow predicting a substance's crystallization time as a function of temperature. The results of this thesis provide valuable insight into the kinetics and relaxation dynamics, as well as the phase stability, of both studied drugs that could be general to other amorphous drugs. Global conclusions are outlined in Chapter 7.