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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Ultra propreté : des microgouttes aux nanoparticules / Ultra cleanliness : microdroplets with nanoparticles

Lallart, Adeline 07 June 2019 (has links)
Avec l’évolution de la microélectronique et la miniaturisation des différents composants à l’échelle nanométrique, la taille des particules critiques à éliminer lors du procédé de fabrication a été drastiquement réduite. En effet, cette taille critique est actuellement de l’ordre de 10nm. Les procédés de nettoyage doivent donc être capables de retirer ces particules sans endommager les surfaces. Afin de répondre à ce challenge, deux méthodes sont étudiées dans ce travail : l’utilisation d’un spray et l’application conjointe d’une couche de polymère et d’un spray.Le spray est utilisé depuis de nombreuses années dans le domaine de la microélectronique. Cependant, le mécanisme de détachement des particules par cette méthode n’est toujours pas assimilé. Le but de cette étude est de mieux le comprendre. Ainsi, différents paramètres vont être étudiés aboutissant à l’élaboration d’un modèle de détachement, faisant apparaître de nouvelles variables liées au procédé de nettoyage, à la contamination (nature et taille des particules) ou encore aux conditions de stockage des surfaces.De son côté, le procédé par utilisation conjointe de couche polymère et de spray est en plein essor mais peu d’informations sont aujourd’hui disponibles. Néanmoins de premières études ont démontré sa capacité à nettoyer des surfaces présentant des motifs et son efficacité quel que soit la taille de la contamination. Dans ce travail, différents procédés de retrait de la couche polymère seront comparés ainsi que certaines propriétés physico-chimiques propres à celle-ci. L’objectif étant de déceler des paramètres clefs influençant le retrait particulaire et de proposer une prémisse d’élucidation des mécanismes physiques mis en jeu. / With the evolution of microelectronics and the miniaturization of the various components at the nanoscale, the size of the critical particles to be removed during the manufacturing process has been drastically reduced. Indeed, this critical size is currently of the order of 10 nm. Cleaning processes must therefore be able to remove these particles without surfaces damage. In order to answer this challenge, two methods are studied in this work: the use of a spray and the joint application of a polymer layer and a spray.The spray has been used for many years in the microelectronics field. However, the mechanism of particles detachment by this method is still not assimilated. The purpose of this study is to better understand it. Thus, different parameters will be studied leading to the development of a detachment model, showing new variables related to the cleaning process, contamination (nature and particle size) or the storage conditions of surfaces.For its part, the process by using a combination of polymer layer and spray is in full development, but little information is available today. Nevertheless, early studies have demonstrated its ability to clean surfaces with patterns and its effectiveness regardless of the size of the contamination. In this work, different methods of the polymer layer removal will be compared as well as some physicochemical properties specific to it. The objective is to detect key parameters influencing particle removal and to propose a premise of elucidation of the physical mechanisms involved.
62

Synthesis of Multiple Polybetaine Block Copolymers and Analysis of Their Self-Assembly in Aqueous Media / ポリベタインブロックコポリマーの合成および水中での自己組織化の挙動解析

Lim, Jongmin 23 March 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22471号 / 工博第4732号 / 新制||工||1739(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 秋吉 一成, 教授 大内 誠, 准教授 松岡 秀樹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
63

DEVELOPMENT OF NOVEL LIQUID CHROMATOGRAPHY STATIONARY PHASES FOR IMPROVED CHARACTERIZATION OF BIOPHARMACEUTICALS

Cameron C Schwartz (11209392) 30 July 2021 (has links)
Monoclonal antibodies are large, complex biomolecules that can be difficult to characterize. Characterization is important because of the various post translational modifications that can occur during manufacturing, processing, and storage. Some modifications can lead to efficacy and safety issues and therefore are heavily monitored. A leading way to monitor various modifications is by using liquid chromatography. The high sensitivity, reproducibility, and ability to quantitate analytes makes it very attractive for monoclonal antibody characterization. The large molecular size of monoclonal antibodies (150 kDa) makes them challenging to separate efficiently and with high enough resolution to be helpful. New column technologies that would help improve protein separation efficiencies and slectivities would greatly help in this challenging process. In this thesis, three novel bonded phases are developed for the separation of monoclonal antibodies including a weak anion and cation exchanger (WAX, CEX) for the separation of charged species as well as a novel hydrophilic interaction chromatography (HILIC) for the separation of glycoforms. Column develop is achieved by optimizing selectivity and improving efficiency of separations by altering particle surface chemistry.
64

Preparation and Biocompatibility of Electrospun Zwitterionic Poly(Sulfobetaine Methacrylate) for Wound Dressing Applications

Lalani, Reza 09 May 2013 (has links)
No description available.
65

Advancement of the Hydrophobic-Hydrophilic Separation Process

Jones, Alan Wayne III 19 April 2019 (has links)
Froth flotation has long been regarded as the best available technology for ultrafine particles separation. However, froth flotation has extreme deficiencies for recovering ultrafine particles that are less than 30-50 μm in size for coal and 10-20 μm for minerals. Furthermore, dewatering of flotation products is difficult and costly using currently available technologies. Due to these problems, coal and mineral fines are either lost to tailings streams inadvertently or discarded purposely prior to flotation. In light of this, researchers at Virginia Tech have developed a process called hydrophobic-hydrophilic separation (HHS), which is based originally on a concept known as dewatering by displacement (DbD). The process uses non-polar solvents (usually short-chain alkanes) to selectively displace water from particle surfaces and to agglomerate fine coal particles. The resulting agglomerates are subsequently broken (or destabilized) mechanically in the next stage of the process, whereby hydrophobic particles are dispersed in the oil phase and water droplets entrapped within the agglomerates coalesce and exit by gravity along with the hydrophilic particles dispersed in them. In the present work, further laboratory-scale tests have been conducted on various coal samples with the objective of commercial deployment of the HHS process. Test work has also been conducted to explore the possibility of using this process for the recovery of ultrafine minerals such as copper and rare earth minerals. Ultrafine streams produced less than 10% ash and moisture consistently, while coarse coal feed had no observable degradation to the HHS process. Middling coal samples were upgraded to high-value coal products when micronized by grinding. All coal samples performed better with the HHS process than with flotation in terms of separation efficiency. High-grade rare earth mineral concentrates were produced with the HHS process ranging from 600-2100 ppm of total rare earth elements, depending on the method and reagent. Additionally, the HHS process produced copper concentrates assaying greater than 30% Cu for both artificial and real feed samples, as well as, between 10-20% Cu for waste samples, which all performed better than flotation. / Master of Science / Froth flotation has long been regarded as the best available technology for separating fine particles. Due to limitations in particle size with froth flotation, and high downstream dewatering costs, a new process has been developed called the hydrophobic-hydrophilic separation (HHS) process. This process was originally based on a concept known as dewatering by displacement (DbD) which was developed by researchers at Virginia Tech in 1995. The process uses hydrocarbon oils, like pentane or heptane, to selectively collect hydrophobic particles, such as coal, for which it was originally developed. In coal preparation plants, a common practice is to purposefully discard the ultrafine stream that flotation cannot recover and has an increased dewatering cost. The HHS process can effectively recovery this waste stream and produce highgrade salable product, with significantly reduced cost of dewatering. In the work presented, laboratory-scale tests have been conducted on various coal samples with the objective of commercial deployment of the HHS process. In this respect, several varying plant streams have been tested apart from the traditional discard stream. Additionally, test work has expanded into mineral commodities such as copper and rare earth minerals. In this work, salable high-value coal products were achievable with the HHS process. Ultrafine streams consistently produced less than 10% ash and moisture. Coarse coal feeds had no observable degradation to the HHS process and were able to produce single digit ash and moisture values. Middling coal samples were upgraded to high-value coal products when micronized by grinding. All coal samples performed better with the HHS process than with flotation in terms of separation efficiency. High-grade rare earth mineral concentrates were produced with the HHS process ranging from 600- 2100 ppm of total rare earth elements depending on the method and reagent. Additionally, the HHS process produced copper concentrates assaying greater than 30% Cu for an artificial and feed samples, as well as, between 10-20% Cu for waste samples, which all performed better than flotation.
66

Oxygen Plasma Surface Activation of Polynorbornene for Bonding to Glass with Applications to Microfluidic Systems

Smith, Russell Lynn 02 May 2011 (has links)
No description available.
67

Characterization of Low Weber Number Post-Impact Drop-Spread Dynamics by a Damped Harmonic System Model

Gande, Sandeep K. 26 September 2011 (has links)
No description available.
68

A novel oral dosage form with drug independent formulation and variable controlled release

Owaisat, Suzan January 2015 (has links)
A unique dosage form which uses a hydrophilic polymer was developed to provide for a predicable release of several drugs. This drug release could be optimized for controlled release using erosion. It can also be designed to release drug utilizing electrochemical processes. The accuracy of drug delivery in terms of dose and timing is of utmost importance for the patient’s health status and compliance. A well-designed drug delivery technology offers many advantages to the patient. These advantages include: reduction in dose frequency, reduction of drug side effects, reduced unwanted fluctuations in circulating drug levels, and a more uniform effect of the drug over time. The practice of drug delivery has been dramatically developed in the last decade including electronic controlled release innovative dosage forms. In this study the iontophoretic flux of ibuprofen was investigated using side- by-side diffusion cells. Iontophoresis is the process where electric current is applied to enhance transportation of drugs across the skin. The pH change was found to be an important factor in increasing the diffusion of the drug. The principle of using electric current as a driving force to control the drug release was initially demonstrated on an initial setup. Subsequently, a calcium binding polymer was the hydrogel used as a matrix to develop a new electric oral dosage form. The calcium binding polymer is produced in different forms. The production process of these forms suffers several limitations. In order to apply electric current in a practical way to the calcium binding polymer matrix a novel method was developed. The novel method also allowed for addressing the limitations related to the production process of the conventional dosage form made with this polymer. More uniform gel tablets in shape and size were produced. Different formulations were developed. Ibuprofen was the model drug initially used to investigate the factors that affected the release profiles of these tablets. A two-level, three-factor statistical design of experiments (DOE) was performed to evaluate the effect of those factors on certain responses. These responses included the release rate, time needed to release 80% of the model drug, and lag-time. A new formulation with certain adjuvants was developed. This formulation had the ability to release different kinds of drugs in a uniform release rate. A fail-safe tablet that can only release less than 20% of the drug in 24 hours was developed. The drug release was initiated only when the electric current was applied. This new electric dosage form was aimed to overcome the disadvantages related to conventional dosage forms such as the inability to supply drugs on demand. / Pharmaceutical Sciences
69

Development and Testing of a Mobile Pilot Plant for the Advancement and Scale-up of the  Hydrophobic-Hydrophilic Separation Process

Sechrist, Chad Michael 03 June 2024 (has links)
Fine particle separation is a grand challenge in the mining and mineral processing industry. The industry standard process, froth flotation, is extremely robust and adaptable; however, it is inefficient for particles less than 20 microns. Owing to this limitation, some mining sectors, such as coal, opt to discard the ultrafine particles to waste impoundments as the costs to recover and dewater these materials are prohibitive. The Hydrophilic Hydrophobic Process (HHS) is one alternative to flotation that uses a recyclable solvent, rather than air bubbles, to selectively recover fine hydrophobic particles. Prior laboratory, proof-of-concept, and demonstration-scale testing has shown that the HHS process is extremely efficient, having no effective size limitation. The purpose of this research was to continue the development and improvement of the HHS process, through the design, construction, and testing of a mobile pilot plant. The pilot plant would in turn be used to demonstrate the robustness of the HHS process through a systemic study of multiple coal sources and ranks. In addition, the pilot plant would serve as a testbed for inquiry-based process intensification, the development and evaluation of design criteria for the various unit operation. Through the course of this research, a 50 lb./hr. (product rate) pilot plant was constructed and commissioned. Initial investigations focused on the shakedown and design of key unit operations, including the agglomeration and de-emulsification (i.e. Morganizing) steps. Studies showed that the initial design of these units, namely pump induced mixing in agglomeration and packed bed emulsification in the Morganizer, were not adequate to meet production demands, and as such, these stages were redesigned after appropriate fundamental evaluations. After implementing the design changes, the pilot plant was successfully operated over a 7-month period, routinely producing bituminous products with less than6% ash and less than 10% moisture as well as anthracite products with less than 3% ash and less than 4% moisture. This study also evaluated a new approach to de-emulsification using a jig based Morganizer in place of the standard oscillating column Morganizer. The jig utilizes a pulsing mechanism to move liquid to break up agglomerates versus the mechanical disk stack. Preliminary results showed that the jig Morganizer was comparable to the oscillating unit at more than half the size. This new design provides a pathway for reduced cost, footprint, and improved scalability. Lastly, this study evaluated both the HHS process and dual-scan X-ray based particle sorting as means of increasing the REE content of coal-based materials. Data from a pilot-scale x-ray sorter showed the unit was capable of preconcentrating REEs to over 300 ppm, while data from the HHS similarly showed the process was capable of REE recoveries of 85-90% and of preconcentrating REEs above 300 ppm. Altogether, these results indicate That both of these technologies are capable of efficiently and cost effectively preconcentrate REEs from wastes streams at operating coal preparation plants. / Doctor of Philosophy / The mining sector has traditionally been a large producer of waste, with the vast majority of this waste being ultrafine particles that are unable to be recovered using conventional technologies. These particles are often disposed of in large surface impoundments, which are an environmental and social liability in many mining districts. This study has evaluated a novel method of fine particle separation, the hydrophobic-hydrophilic separation (HHS) process. The HHS process uses a recyclable oil to selectively agglomerate fine particles, which are subsequently dispersed and recovered. The oil is then filtered and recycled within the process creating an approach that is both efficient and environmentally friendly. In this study, a mobile pilot HHS plant was constructed and tested, with the results showing that the HHS can effectively recover fine carbon from waste coals, thus turning an environmental liability into a potential value stream for high-end applications. In addition, the study showed that the process can be further improved to reduce costs while improving overall efficiency. Overall, this study has provided the data needed to further commercialize the HHS process. If widely deployed, the HHS process has the potential to both reduce the current amount of waste fines being generated and reclaim the existing impoundments.
70

The Production of Low Ash Coals Using the Hydrophobic-Hydrophilic Separation Process with Novel Developments

Youmans, Nathan Charles 06 June 2023 (has links)
Master of Science / Froth flotation is a common method in mineral processing to separate material based on hydrophobicity. This process becomes less efficient, however, as particle size is reduced. Because of this ultrafine particles are often discarded prior to froth flotation, and contributes to a substantial amount of coal waste in impoundments. An impoundment is a dam built using coarse reject to hold fine reject in slurry. Because of the land-use and risk of an impoundment failure, these impoundments pose an environmental liability. To address ultrafine coal rejection, researchers at Virginia Tech development the hydrophobic-hydrophilic separation (HHS) process. Unlike in froth flotation, HHS uses an organic solvent to separate and dewater hydrophobic particles from hydrophilic minerals. Past work on the HHS process yielded promising results. In particular, the HHS process has produced a low-ash (<2%) and low moisture (<8%) product, which makes it viable for a feed stock for carbon products. With this in mind, the goal of this work is to make the HHS process more robust by improving the understanding of the effects of auxiliary processes, such as grinding, pre-concentration, and reagent conditioning, on the HHS process. This work also contains work on the interaction between two primary unit operations in the HHS process: oil agglomeration and de-emulsification. Lastly, to make the HHS process more viable for commercial scale-up, a novel unit operation called enhanced liquid flotation (ELF) was developed and tested that performs comparably to the current HHS process, but with less unit operations.

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