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Synthesis and investigation of oligomers based on phenylalanine as interfacial agents in fibre-reinforced thermoplastic composite materials / Synthèse et évaluation d’oligomères contenant des phénylalanines en tant qu’agents interfaciaux pour matériaux composites thermoplastiques renforcés de fibresLouwsma, Jeroen 06 December 2018 (has links)
Le développement d’agents interfaciaux pour des matériaux composites renforcés de fibres est nécessaire afin d’obtenir des matériaux performants notamment pour l’industrie automobile. Le projet se concentre sur la synthèse d’oligomères à séquences contrôlées préparés par synthèse en phase solide par réaction d’amidification et de cycloaddition assistée par le cuivre entre un azoture et un alcyne pour introduire précisément des unités de phénylalanine et des groupes aliphatiques. Ces oligomères ont été testés comme agents interfaciaux pour des matériaux composites à base de polypropylène renforcés de fibres de Kevlar. Leur capacité à s’adsorber sur les fibres a été étudiée de façon qualitative par microscopie électronique à balayage et quantitative par analyse gravimétrique. Des expériences préliminaires sur des fibres de Kevlar traitées avec des oligomères synthétisés dans une matrice de polypropylène ont été réalisées pour estimer leur potentielle utilisation dans des matériaux composites. / The development of interfacial agents for fibre-reinforced composite materials is needed to obtain performant materials especially for the automotive industry. The project focused on the synthesis of sequence-controlled oligomers prepared by solid phase synthesis using amidation and copper-assisted alkyne-azide cycloaddition reactions to introduce precisely phenylalanine and aliphatic building blocks. These oligomers were evaluated as potential interfacial agents for Kevlar fibre-reinforced polypropylene composite materials. Their ability to adsorb on the fibres was investigated qualitatively by scanning electron microscopy and quantitatively by gravimetric analysis. Some preliminary experiments on the Kevlar fibres treated with some of the synthesised oligomers in a polypropylene matrix were conducted to estimate their potential use in composite materials.
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Synchrotron X-ray Scanning Tunneling Microscopy Investigation of Interfacial Properties of Nanoscale MaterialsChang, Hao January 2018 (has links)
No description available.
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Creation of crosslinkable interphases in polymer blends by means of novel coupling agentsSadhu, Veera Bhadraiah 24 June 2004 (has links)
The goal of the work is to study possibilities for the modification of interface in immiscible polymer blends, which determine to a large degree of the blend properties. For this purpose novel coupling agents (named SCA) containing 2-oxazoline, 2-oxazinone, and hydrosilane reactive sites have been prepared. In blends of amino- functional and carboxylic acid terminated polymers the oxazoline and oxazinone units of the SCA react selectively with one of the polymers and, therefore, the SCA should locate at the interface. The remaining hydrosilane sites can now be used for further modification, e.g. for crosslinking. In the thesis we discussed the effect of the SCA on the morphology and thermal and rheological properties of blends based on carboxylic acid terminated polystyrene (PS) and amino-terminated polyamide 12 (PA) or poly(methyl methacrylate) (PMMA). The morphology of the blends and the location of the SCA strongly depends on the processing conditions. The crosslinkability of the interface could be proven by changes in the solubility behavior of the blends.
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MODEL DEVELOPMENT AND DESIGN OPTIMIZATION FOR SPRING-DRIVEN AUTOINJECTORS AND CAVITATION BUBBLESXiaoxu Zhong (16385481) 18 June 2023 (has links)
<p>Autoinjectors are pen-like devices that typically deliver drug products of 2 mL or less. They shield the needle before and after use, reducing patient anxiety from needle phobia and mitigating the risk of needlestick injuries and accidental contamination. Additionally, automatic delivery ensures more consistent needle penetration depth and injection force than manual injection methods. </p>
<p><br></p>
<p>To optimize autoinjector design, this thesis presents experimentally validated computational models that describe the processes of needle insertion, drug delivery, and transport of subcutaneously administered therapeutic proteins in the body. A multi-objective optimization framework is also proposed to guide the design of autoinjectors.</p>
<p><br></p>
<p>This thesis focuses on spring-driven autoinjectors, the most common type of autoinjector. It begins with an overview of the interactions between the spring-driven autoinjector, tissue, and therapeutic proteins. Moving on to Chapter 2, a computational model is presented to accurately predict the kinematics of the syringe barrel and plunger during the needle insertion process.</p>
<p><br></p>
<p>In Chapter 3, we present a quasi-steady model for the drug delivery process, which considers the rheology of therapeutic proteins. The Carreau model is adopted to describe protein viscosity, and explicit relationships between flow rate and pressure drop in the needle are derived. Furthermore, the applicable regime for the power-law model for protein viscosity is identified.</p>
<p><br></p>
<p>Chapter 4 quantifies the impact of sloshing and cavitation on therapeutic proteins in the syringe. Additionally, a workflow is presented to integrate available simulation tools to predict the performance of spring-driven autoinjectors. The influence of each design parameter of spring-driven autoinjectors on their performance is also discussed. </p>
<p><br></p>
<p>The spring-driven autoinjector delivers therapeutic proteins through subcutaneous administration. To gain insights into the transport process of therapeutic proteins, Chapter 5 presents a physiologically-based pharmacokinetic model that has been validated against experimental data for humans and rats. The lymph flow rate significantly affects the bioavailability of therapeutic proteins. This finding highlights the importance of studying the transport of therapeutic proteins in the lymphatic system in future research.</p>
<p><br></p>
<p>Chapter 6 provides a multi-objective design optimization framework for the spring-driven autoinjector. The computational model is replaced with an accurate deep neural network surrogate to improve the computational efficiency. Using this surrogate model, we conduct a sensitivity analysis to identify essential design parameters. After that, we perform multi-objective optimization to find promising design candidates.</p>
<p><br></p>
<p>Chapter 7 presents a model for bubble dynamics in a protein solution. An explicit expression for the bubble dissolution rate is derived, enabling extraction of the interfacial properties of the protein-coated interface from the measured bubble radii. Moreover, analytical solutions for the response of a protein-coated bubble to an imposed acoustic pressure are derived. This work provides insight into protein-coated bubbles, which are used as vehicles to deliver drugs, as active miniature tracers to probe the rheology of soft and biological materials, or as contrast agents to enhance the ultrasound backscatter in ultrasonic imaging.</p>
<p><br></p>
<p>At last, in Chapter 8, we introduce a model for laser-induced cavitation that considers several key factors, such as liquid compressibility, heat transfer, and non-equilibrium evaporation and condensation. Our model's predictions for the time-course of bubble radii have been validated with experimental data. Moreover, our model reveals that the reduction of the bubble's oscillation amplitude is primarily due to a decrease in the number of vapor molecules inside the bubble, highlighting the crucial role of phase change in laser-induced cavitation bubbles.</p>
<p><br></p>
<p>The developed computational models and framework provide crucial insights into the development of spring-driven autoinjectors and cavitation bubbles. These studies can also enhance the efficacy and safety of the delivery of therapeutic proteins, ultimately improving patient outcomes.</p>
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Interfacial Synthesis of Layer-Oriented 2D Conjugated Metal-Organic Framework Films towards Directional Charge TransportWang, Zhiyong, Walter, Lisa S., Wang, Mao, St. Petkov, Petko, Liang, Baokun, Qi, Haoyuan, Nguyen, Nguyen Ngan, Hambsch, Mike, Zhong, Haixia, Wang, Mingchao, Park, SangWook, Renn, Lukas, Watanabe, Kenji, Taniguchi, Takashi, Mannsfeld, Stefan C. B., Heine, Thomas, Kaiser, Ute, Zhou, Shengqiang, Weitz, Ralf Thomas, Feng, Xinliang, Dong, Renhao 15 August 2022 (has links)
The development of layer-oriented two-dimensional conjugated metal-organic frameworks (2D c-MOFs) enables an access to direct charge transport, dial-in lateral/vertical electronic devices and unveil transport mechanisms, but remains a significant synthetic challenge. Here we report the novel synthesis of metal-phthalocyanine-based p-type semiconducting 2D c-MOF films (Cu2[PcM-O8], M=Cu or Fe) with an unprecedented edge-on layer-orientation at the air/water interface. The edge-on structure for-mation is guided by the pre-organization of metal-phthalocyanine ligands, whose basal plane is perpendicular to the water surface due to their π-π interaction and hydrophobicity. Benefiting from the unique layer orientation, we are able to investigate the lateral and vertical conductivities by DC methods, and thus demonstrate an anisotropic charge transport in the resulting Cu2[PcCu-O8] film. The directional conductivity studies combined with theoretical calculation identify that the intrinsic conductivity is dominated by charge transfer along the interlayer pathway. Moreover, a macroscopic (cm2-size) Hall-effect measurement reveals a Hall mobility of ~4.4 cm2 V-1 s-1 for the obtained Cu2[PcCu-O8] film. The orientation control in semiconducting 2D c-MOFs will enable the develop-ment of various optoelectronic applications and the exploration of unique transport properties.
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Design, Development and Structure of Liquid and Solid Electrolytes for Lithium BatteriesAl-Salih, Hilal 11 September 2023 (has links)
Energy storage is crucial for intermittent renewable energy sources, electric vehicles, and portable devices. The continuously increasing energy consumption in these industries necessitates the enhancement of commercial lithium-ion batteries (LIB), especially regarding their safety and energy density. Historically, aqueous electrolytes were the norm in the battery industry. Prior to the development of lithium batteries, most commercially significant batteries used water as the solvent. In the past decade, "highly concentrated" electrolytes resurrected the notion of an aqueous lithium-ion battery (ALIB). Significant efforts have been made since then to comprehend the interfacial stability of these high-concentration electrolytes, and make them suitable for use in batteries especially high voltage ones. Another candidate for future batteries is All-Solid-State Batteries (ASSB) as they have the potential to double, or even triple, the energy density figures we currently achieve in LIBs mainly due to their ability to utilize lithium metal anode which has the highest specific capacity among anodes (3860 mAh g⁻¹), lowest reduction potential (-3.04 V vs SHE), and low density (0.53 g cm⁻³).
This thesis first proposes a phenomenological model to describe the microstructure of aqueous electrolyte and the relation between their phase diagrams with ionic conductivity; highlighting a common correlation between the eutectic composition and peak ionic conductivity in conductivity isotherms. we then propose an empirical model correlating ionic conductivity with both molar concentration and temperature. The aim of this portion of the thesis is to provide an in depth understanding of aqueous electrolytes' physical properties in a way that can help researchers optimize the energy density and the cost of ALIBs.
Moving further, the thesis presents two novel composite solid electrolytes (CSE) that were developed and fully characterized. Both of which were composed of the following four components; polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, lithium lanthanum titanate (LLTO) perovskite inorganic ceramic and the polymer plasticizer succinonitrile (SN). The careful formulation of these CSEs was based on the trade-off between film forming ability and ionic conductivity. The optimized polymer rich CSE proved to have better characteristics when compared to its ceramic rich alternative. ASSBs employing both CSEs were successfully charged and discharged when coupled with lithium metal anode and in-lab prepared composite cathode. The developed thin and flexible CSEs could be utilized in small applications (Wh-KWh) such as in consumer electronics and flexible biomedical devices (e.g., pacemakers) or larger applications (kWh-MWh) such as in EVs and large format storage for the electrical grid.
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[pt] EFEITO DO QUEROSENE NAS PROPRIEDADES INTERFACIAIS E NA ESTABILIDADE DA EMULSÃO DE UM ÓLEO PESADO BRASILEIRO / [en] EFFECT OF KEROSENE ON INTERFACIAL PROPERTIES AND EMULSION STABILITY OF A BRAZILIAN HEAVY OILLINA MERCEDES DAZA BARRANCO 02 October 2023 (has links)
[pt] A alta viscosidade dos óleos pesados e o elevado teor de asfaltenos contribuem para
a formação de emulsões água-em-óleo (A/O) altamente estáveis, dificultando a separação
óleo/água e aumentando os custos de produção e transporte. Para reduzir a viscosidade,
técnicas de diluição são comuns com solventes simples. Portanto, pouca pesquisa foi
realizada sobre o impacto dos compostos aromáticos nas propriedades interfaciais e na
estabilidade das emulsões, de solventes complexos, como o querosene. Neste estudo,
investigou-se o efeito da segregação dos compostos aromáticos do querosene nas
propriedades bulk e interfaciais e na estabilidade dos asfaltenos e das emulsões A/O. Além
disso, foram analisadas as correlações desses efeitos com a desemulsificação química.
Inicialmente, foram avaliadas as propriedades interfaciais de frações de surfactantes
naturais, extraídas de um óleo pesado brasileiro, em relação à sua capacidade de estabilizar
emulsões água-querosene. Os resultados indicaram que a estabilidade dessas emulsões
decorre do efeito sinérgico entre as resinas e os asfaltenos, resultando na formação de
filmes interfaciais mais flexíveis, que evitam ou retardam a coalescência das gotas.
Entretanto, quando o querosene foi utilizado como diluente do óleo pesado (HO) na fase
oleosa, observou-se a floculação e precipitação dos asfaltenos. Esses resultados foram
correlacionados com a composição química de dois tipos de querosene: um composto
apenas por saturados (KeS) e outro contendo 30 por cento massa de compostos aromáticos (KeSA).
Verificou-se que a composição química dos querosenes afeta a estabilidade coloidal dos
asfaltenos, a estabilidade da emulsão e as propriedades interfaciais. KeSA apresentou maior
solubilização e dispersão dos asfaltenos em comparação ao KeS. Além disso, a
viscoelasticidade interfacial diminuiu quando o teor de querosene foi maior ou igual a 30 por cento massa,
indicando a formação de filmes interfaciais menos rígidos. Porém, o módulo de
elasticidade nos sistemas contendo KeSA aumentou gradualmente com o tempo, sugerindo
uma melhor solubilidade dos asfaltenos e uma adsorção controlada pela difusão facilitada
na interface. A concentração de aromáticos do solvente (KeSA) mantém a estabilidade do
filme interfacial durante a diluição de HO, compensando assim a perda de asfaltenos com
o aumento do teor de querosene na fase óleo. Os resultados também destacaram o papel
crucial da aromaticidade do querosene na quebra das emulsões A/O contendo 20 por cento massa
de Ke na fase oleosa. Diferentes desemulsificantes químicos, comumente utilizados como
bases para desemulsificantes comerciais, bem como compostos modelo, foram testados.
KeSA apresentou maior robustez e resistência à quebra das emulsões. Esse efeito decorre
da segregação interfacial dos compostos aromáticos do querosene. Esses resultados
enfatizam a importância da composição química do querosene quando é usado na diluição
de óleos pesados, o qual tem efeito significativo na estabilidade e quebra das emulsões
A/O. / [en] The high viscosity of heavy oils and the high content of asphaltenes contribute to the
formation of highly stable water-in-heavy oil (W/O) emulsions, making oil/water
separation difficult and increasing production and transportation costs. To reduce viscosity,
dilution techniques with simple solvents are common. Therefore, slight research has been
conducted on the impact of aromatic compounds on interfacial properties and emulsion
stability from complex solvents, such as kerosene. In this study, we investigated the effect
of segregation of aromatic compounds in kerosene on the bulk and interfacial properties
and stability of asphaltenes and W/O emulsions. Furthermore, we analyzed the correlations
of these effects with chemical demulsification. Initially, we evaluated the interfacial
properties of natural surfactants fractions extracted from Brazilian heavy oil regarding their
ability to stabilize water-kerosene emulsions. The results indicated that the stability of
these emulsions was related to the synergistic effect between resins and asphaltenes,
resulting in the formation of more flexible interfacial films that prevent or delay the
coalescence of the droplets. However, when kerosene was used as diluent of heavy oil
(HO) in the oil phase, flocculation and precipitation of asphaltenes were observed. These
results were correlated with the chemical composition of two kerosene types: one
composed only of saturates (KeS) and another containing saturates and 30 percent wt. of aromatic
compounds (KeSA). It was found that the chemical composition of the kerosene affects the
colloidal asphaltenes stability, emulsion stability, and interfacial properties. KeSA showed
greater solubilization and dispersion of asphaltenes compared to KeS. Additionally,
interfacial viscoelasticity decreased when the kerosene content was bigger or equal 30 wt. percent, indicating
the formation of less rigid interfacial films. However, the interfacial elastic modulus in
systems containing KeSA gradually increased over time, suggesting better solubility of
asphaltenes and diffusion-controlled adsorption at the interface. The concentration of
solvent aromatics (KeSA) maintains interfacial film stability during HO dilution, thus
compensating for the loss of asphaltenes with increasing kerosene content in the oil phase.
The results also revealed the crucial role of kerosene s aromaticity in the breaking of W/O
emulsions containing 20 wt. percent of kerosene in the oil phase. Various chemical demulsifiers
commonly used as bases for commercial demulsifiers, as well as model compounds, were
tested. The presence of KeSA exhibited greater robustness and resistance to emulsion
breaking. This effect was attributed to interfacial segregation of aromatic compounds from
kerosene. These results emphasize the importance of kerosene s chemical composition
when used for diluting heavy oils, as it has a significant effect on the stability and breaking
of W/O emulsions, particularly in the case of the Brazilian heavy oil used in this study.
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Extending the Boundaries of Ambient Mass Spectrometry through the Development of Novel Ion Sources for Unique ApplicationsSahraeian, Taghi January 2022 (has links)
No description available.
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Analysis of Weighted Fraction of Length for Interfacial Gap in Cervical Composite Restorations as a Function of the Number of B-Scans of OCT Volume ScansSchneider, Hartmut, Meißner, Tobias, Rüger, Claudia, Haak, Rainer 26 April 2023 (has links)
In dental research, the morphometric assessment of restorations is a challenge. This also applies to the assessment of the length of interfacial adhesive defects in composite restorations as a measure of tooth-restoration bond failure. The determined mean fractions of interfacial gap length on enamel and dentin interfaces deviate from the true means (N → ∞), depending on the number (Ni) of object layers assessed. Cervical composite restorations were imaged with spectral domain optical coherence tomography (SD-OCT). The mean fractions of interfacial gap length on enamel and dentin were determined for an increasing number of OCT cross-sectional images (B-scans) per restoration and were graphically displayed as a function of the number of B-scans. As the number of B-scans increased, the calculated object means approached a range of ±2.5%. This analysis is appropriate for displaying the relationship between the determined mean fraction of interfacial gap length at the enamel/dentin-restoration interface and the number of B-scans.
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A Numerical Analysis of the Influence of Korteweg Stresses on the Flow and Mixing of Miscible FluidsWilson, Raymond Gary 07 April 2004 (has links)
No description available.
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