Silicone thiomers- conquerers of innovative drug delivery systems

eingereicht von Alexandra Partenhauser

Próteses para membro superior de alta definição em silicone

O interesse de Pillet em próteses cosméticas de mão, começou em 1950 com o reconhecimento que até mesmo a perda de um único dedo poderia ter um profundo efeito sobre a imagem corporal, auto-estima, e estado psicológico do amputado. A atitude comum naquela época era que, devido à prótese ser inerte e insensível, seria não-funcionais. No entanto, os 39 anos de experiência do autor na aplicação de mais de 6.000 próteses demonstra que o restabelecimento da aparência quase normal, muitas vezes melhora a função do paciente num sentido global, permitindo-lhe optimizar as funções residuais no complexo ambiente socioeconómico da sociedade de hoje. Além disso, ao fornecer uma parte da oposição para os dedos restantes ou o polegar, a prótese também pode fornecer alguma capacidade de preensão, que pode ser muito útil. A perda do membro superior ou parte deste pode ser mais catastrófico para o individuo do que a mais comum perda do membro inferior. A perda de ambas as mãos cria uma incapacidade apenas excedida por uma lesão vertebro-medular. Wedder-Burn comentou, em 1986, que “amputados parciais da mão são mais passíveis de rejeitar a protetização do que amputados a outro nível do membro superior. A Rejeição baseia-se na falta de sensibilidade, uma cosmética deficitária, ausência de ventilação da prótese e função limitada”. Como resultado muitos amputados parciais da mão preferem realizar as suas actividades diárias sem a prótese.

Investigating wetting characteristics on microstructured surfaces for superhydrophobicity and metal microcasting

The engineering of liquid behavior on surfaces is important for infrastructure, transportation, manufacturing, and sensing. Surfaces can be rendered superhydrophobic by microstructuring, and superhydrophobic devices could lead to practical corrosion inhibition, self-cleaning, fluid flow control, and surface drag reduction. To more fully understand how liquid interacts with microstructured surfaces, this dissertation introduces a direct method for determining droplet solid-liquid-vapor interfacial geometry on microstructured surfaces. The technique performs metrology on molten metal droplets deposited onto microstructured surfaces and then frozen. Unlike other techniques, this visualization technique can be used on large areas of curved and opaque microstructured surfaces to determine contact line. This dissertation also presents measurements and models for how curvature and flexing of microstructured polymers affects hydrophobicity. Increasing curvature of microstructured surfaces leads to decreased slide angle for liquid droplets suspended on the surface asperities. For a surface with regularly spaced asperities, as curvature becomes more positive, droplets suspended on the tops of asperities are suspended on fewer asperities. Curvature affects superhydrophobicity because microscopic curvature changes solid-liquid interaction, pitch is altered, and curvature changes the shape of the three phase contact line. This dissertation presents a model of droplet interactions with curved microstructured surfaces that can be used to design microstructure geometries that maintain the suspension of a droplet when curved surfaces are covered with microstructured polymers. Controlling droplet dynamics could improve microfluidic devices and the shedding of liquids from expensive equipment, preventing corrosion and detrimental performance. This dissertation demonstrates redirection of dynamic droplet spray with anisotropic microstructures. Superhydrophobic microstructured surfaces can be economically fabricated using metal embossing masters, so this dissertation describes casting-based microfabrication of metal microstructures and nanostructures. Low melting temperature metal was cast into flexible silicone molds which were themselves cast from microfabricated silicon templates. The flexibility of the silicone mold permits casting of curved surfaces, which this dissertation demonstrates by fabricating a cylindrical metal roller with microstructures. The metal microstructures can be in turn used as a reusable molding tool. This dissertation also describes an industrial investment casting process to produce aluminum molds having integrated microstructures. Unlike conventional micromolding tools, the aluminum mold was large and had complex curved surfaces. The aluminum was cast into curved microstructured ceramic molds which were themselves cast from curved microstructured rubber. Many structures were successfully cast into the aluminum with excellent replication fidelity, including circular, square, and triangular holes. This dissertation demonstrates molding of large, curved surfaces having surface microstructures using the aluminum mold. This work contributes a more full understanding of the phenomenon of superhydrophobicity and techniques for the economic fabrication of superhydrophobic microstructures.

In vitro and in vivo delivery of the secretagogue diadenosine tetraphosphate from conventional and silicone hydrogel soft contact lenses

Purpose To evaluate the possible use of soft contact lenses (CL) to improve the secretagogue role of diadenosine tetraphosphate (Ap4A) promoting tear secretion. Methods Two conventional hydrogel CL (Omafilcon A and Ocufilcon D) and two silicone hydrogel (SiH) CL (Comfilcon A and Balafilcon A) were used. Ap4A was loaded into the lenses by soaking in a 1 mM Ap4A solution during 12 h. In vitro experiments were performed by placing the lenses in multi-wells during 2 h containing 1 ml of ultrapure water. 100 μl aliquots were taken at time zero and every minute for the first 10 min, and then every 15 min. In vivo experiments were performed in New Zealand rabbits and both the dinucleotide release from SiH and tear secretion were measured by means of Schirmer strips and high-pressure liquid chromatography (HPLC) analysis. Results Ap4A in vitro release experiments in hydrogel CL presented a release time 50 (RT50) of 3.9 ± 0.2 min and 3.1 ± 0.1 min for the non-ionic and the ionic CL, respectively. SiH CL released also Ap4A with RT50 values of 5.1 ± 0.1 min for the non-ionic and 2.7 ± 0.1 min for the ionic CL. In vivo experiments with SiH CL showed RT50 values of 9.3 ± 0.2 min and 8.5 ± 0.2 min for the non-ionic and the ionic respectively. The non-ionic lens Ap4A release was able to induce tear secretion above baseline tear levels for almost 360 min. Conclusion The delivery of Ap4A is slower and the effect lasts longer with non-ionic lenses than ionic lenses.

Taraxacum koksaghyz Rodin as an alternative source of natural rubber and inulin; agronomic advances and genetic linkage map

126 p. El contenido del capítulo 3 está sujeto a confidencialidad.

Dimensional stability of an addition silicone after disinfection/sterilization

Poster presented at the “From Basic Sciences to Clinical Research” – First International Congress of CiiEM. Egas Moniz, Caparica, Portugal, 27-28 November 2015

Leaf anatomy of rubber-tree clones

A seringueira é uma planta de fácil reconhecimento por ser lenhosa, de porte mediano a grande, que apresenta um padrão característico de desfolha e reenfolhamento e, sobretudo, pela produção de látex. O objetivo do trabalho foi efetuar um estudo anatômico e morfológico foliar, comparando os clones RRIM 600 e GT 1 de seringueira &91;Hevea brasiliensis (Wild. ex Adr. de Juss.) Muell.- Arg&93;, desenvolvidos sob as mesmas condições edáficas e climáticas, para obtenção de informações que possam fornecer subsídios para correlações com dados fisiológicos e também diferenciar os clones em relação ao conteúdo de fibras, espessamento de tecidos do parênquima paliçádico e do parênquima lacunoso, caracterização anatômica do pecíolo, número e tamanho de estômatos e fornecer dados referentes a morfologia foliolar. Foram realizadas secções transversais na região do mesófilo, nervura central e pecíolo, seguindo-se os métodos usuais de preparação de lâminas permanentes. Foram realizadas análises biométricas de extensões de tecidos dos parênquimas paliçádico e lacunoso e contagem do número de células do parênquima lacunoso. Paralelamente foram realizadas análises biométricas para aferições de estômatos. Não houve diferenças para a altura das células epidérmicas, altura e número de camadas do parênquima lacunoso e para o comprimento e para a maior largura do limbo foliolar. Porém houve variação para a espessura das células do parênquima paliçádico, sendo que GT 1 apresentou maior espessura em relação a RRIM 600. GT1 apresentou maior número de estômatos em relação a RRIM 600, porém com menor tamanho. GT1 apresentou maior diâmetro da nervura central da folha e do pecíolo e maior quantidade de fibras de esclerênquima que RRIM 600.

Microclimate, development and productivity of robusta coffee shaded by rubber trees and at full sun.

Existem poucos estudos sobre arborização de café conilon com seringueira. Objetivou-se avaliar o microclima, desenvolvimento e produtividade do cafeeiro conilon cultivado a pleno sol e sob sombreamento proporcionado pela seringueira. O experimento foi composto por uma lavoura de café conilon (Coffea canephora), cultivada a pleno sol e outra lavoura de café consorciada com seringueira (Hevea brasiliensis). A seringueira e o cafeeiro foram plantados no sentido Leste/Oeste, em Jaguaré, Espírito Santo, Brasil. Avaliou-se a luminosidade, temperatura e umidade relativa do ar, concentração foliar de nutrientes, medição dos internódios dos ramos plagiotrópicos e ortotrópicos, área foliar, índice relativo de clorofila, e a produtividade do cafeeiro. O sombreamento influenciou diretamente no microclima, reduzindo a temperatura do ar no verão e no inverno e aumentando a umidade relativa. A luminosidade no verão teve uma redução media de 905 lumens ft-2 ao longo de todo dia, equivalente a 72,49%, e no inverno de 1665 lumens ft-2, equivalente a 88,04%. O sombreamento proporcionou maior estiolamento dos ramos plagiotrópicos e ortotrópicos, bem como maior expansão foliar. A concentração foliar de Fe e Mn foram maiores no cafeeiro arborizado. A clorofila b e total estimada foram maior no cafeeiro cultivado a pleno sol. O denso sombreamento oferecido pela seringueira nas condições estudadas proporcionou perdas na produtividade do cafeeiro, contudo, ocorre a formação da seringueira.

More than Metadata: Where the Rubber Meets the Road in DLS Migration

This panel presentation provided several use cases that detail the complexity of large-scale digital library system (DLS) migration from the perspective of three university libraries and a statewide academic library services consortium. Each described the methodologies developed at the beginning of their migration process, the unique challenges that arose along the way, how issues were managed, and the outcomes of their work. Florida Atlantic University, Florida International University, and the University of Central Florida are members of the state's academic library services consortium, the Florida Virtual Campus (FLVC). In 2011, the Digital Services Committee members began exploring alternatives to DigiTool, their shared FLVC hosted DLS. After completing a review of functional requirements and existing systems, the universities and FLVC began the implementation process of their chosen platforms. Migrations began in 2013 with limited sets of materials. As functionalities were enhanced to support additional categories of materials from the legacy system, migration paths were created for the remaining materials. Some of the challenges experienced with the institutional and statewide collaborative legacy collections were due to gradual changes in standards, technology, policies, and personnel. This was manifested in the quality of original digital files and metadata, as well as collection and record structures. Additionally, the complexities involved with multiple institutions collaborating and compromising throughout the migration process, as well as the move from a consortial support structure with a vendor solution to open source systems (both locally and consortially supported), presented their own sets of unique challenges. Following the presentation, the speakers discussed commonalities in their migration experience, including learning opportunities for future migrations.

A finite element framework for the interplay between delamination and buckling of rubber-like bi-material systems and stretchable electronics

In this study, a finite element (FE) framework for the analysis of the interplay between buckling and delamination of thin layers bonded to soft substrates is proposed. The current framework incorporates the following modeling features: (i) geometrically nonlinear solid shell elements, (ii) geometrically nonlinear cohesive interface elements, and (iii) hyperelastic material constitutive response for the bodies that compose the system. A fully implicit Newton–Raphson solution strategy is adopted to deal with the complex simultaneous presence of geometrical and material nonlinearities through the derivation of the consistent FE formulation. Applications to a rubber-like bi-material system under finite bending and to patterned stiff islands resting on soft substrate for stretchable solar cells subjected to tensile loading are proposed. The results obtained are in good agreement with benchmark results available in the literature, confirming the accuracy and the capabilities of the proposed numerical method for the analysis of complex three-dimensional fracture mechanics problems under finite deformations.

Patterns of fitting cosmetically tinted contact lenses

Cosmetically tinted soft contact lenses are an attractive option for contact lens wearers. Data that we have gathered from annual contact lens fitting surveys demonstrate that those wearing tinted lenses are more likely to be female (4.6% of all soft lenses fitted vs. 1.6% for males; p < 0.0001) and younger (27 11 years vs. 33 13 years for those wearing non-tinted lenses; p < 0.0001). Tinted lenses tend to be worn more on a part-time basis and are replaced less frequently than non-tinted lenses. The decline in fitting tinted lenses over the past 12 years may be due to (a) the current limited availability of tinted lenses in silicone hydrogel materials and daily disposable replacement frequencies, which together represent a significant majority (78%) of new soft lenses fits today, (b) growing concerns among lens wearers and practitioners relating to the risks of complications associated with the wearing of tinted lenses, and (c) reduced promotion of such lenses by the contact lens industry.

Factors influencing the prescribing of hydrogel contact lenses

Despite the current market popularity of silicone hydrogel contact lenses, conventional hydrogel lenses still represent a significant proportion of the overall contact lens market. Data gathered from annual UK contact lens fitting surveys over the past 13 years indicate that 64% of hydrogel lenses prescribed during this period were of low/medium water content (<60% water). Whereas, in the past, practitioners would choose the water content of a hydrogel lens to meet specific clinical needs, this choice appears today to be largely governed by product availability.

Tear film surface quality with soft contact lenses using dynamic-area high-speed videokeratoscopy

Objectives. To evaluate the performance of the dynamic-area high-speed videokeratoscopy technique in the assessment of tear film surface quality with and without the presence of soft contact lenses on eye. Methods. Retrospective data from a tear film study using basic high-speed videokeratoscopy, captured at 25 frames per second, (Kopf et al., 2008, J Optom) were used. Eleven subjects had tear film analysis conducted in the morning, midday and evening on the first and seventh day of one week of no lens wear. Five of the eleven subjects then completed an extra week of hydrogel lens wear followed by a week of silicone hydrogel lens wear. Analysis was performed on a 6 second period of the inter-blink recording. The dynamic-area high-speed videokeratoscopy technique uses the maximum available area of Placido ring pattern reflected from the tear interface and eliminates regions of disturbance due to shadows from the eyelashes. A value of tear film surface quality was derived using image rocessing techniques, based on the quality of the reflected ring pattern orientation. Results. The group mean tear film surface quality and the standard deviations for each of the conditions (bare eye, hydrogel lens, and silicone hydrogel lens) showed a much lower coefficient of variation than previous methods (average reduction of about 92%). Bare eye measurements from the right and left eyes of eleven individuals showed high correlation values (Pearson’s correlation r = 0.73, p < 0.05). Repeated measures ANOVA across the 6 second period of measurement in the normal inter-blink period for the bare eye condition showed no statistically significant changes. However, across the 6 second inter-blink period with both contact lenses, statistically significant changes were observed (p < 0.001) for both types of contact lens material. Overall, wearing hydrogel and silicone hydrogel lenses caused the tear film surface quality to worsen compared with the bare eye condition (repeated measures ANOVA, p < 0.0001 for both hydrogel and silicone hydrogel). Conclusions. The results suggest that the dynamic-area method of high-speed videokeratoscopy was able to distinguish and quantify the subtle, but systematic worsening of tear film surface quality in the inter-blink interval in contact lens wear. It was also able to clearly show a difference between bare eye and contact lens wearing conditions.

PDMS spreading morphological patterns on substrates of different hydrophilicity in air vacuum and water

In paper has been to investigate the morphological patterns and kinetics of PDMS spreading on silicon wafer using combination of techniques like ellipsometry, atomic force microscope (AFM), scanning electron microscope (SEM) and optical microscopy. A macroscopic silicone oil drops as well as PDMS water based emulsions were studied after deposition on a flat surface of silicon wafer in air, water and vacuum. our own measurements using an imaging ellipsometer, which also clearly shows the presence of a precursor film. The diffusion constant of this film, measured with a 60 000 cS PDMS sample spreading on a hydrophilic silicon wafer, is Df = 1.4  10-11 m2/s. Regardless of their size, density and method of deposition, droplets on both types of wafer (hydrophilic and hydrophobic) flatten out over a period of many hours, up to 3 days. During this process neighbouring droplets may coalesce, but there is strong evidence that some of the PDMS from the droplets migrates into a thin, continuous film that covers the surface in between droplets. The thin film appears to be ubiquitous if there has been any deposition of PDMS. However, this statement needs further verification. One question is whether the film forms immediately after forced drying, or whether in some or all cases it only forms by spreading from isolated droplets as they slowly flatten out.

Vibration of ship structures and its control

Noise and vibration in complex ship structures are becoming a prominent issue for ship building industry and ship companies due to the constant demand of building faster ships of lighter weight, and the stringent noise and libration regulation of the industry. In order to retain the full benefit of building faster ships without compromising too much on ride comfort and safety, noise and vibration control needs to be implemented. Due to the complexity of ship structures, the coupling of different wave types and multiple wave propagation paths, active control of global hull modes is difficult to implement and very expensive. Traditional passive control such as adding damping materials is only effective in the high frequency range. However, most severe damage to ship structures is caused by large structural deformation of hull structures and high dynamic stress concentration at low frequencies. The most discomfort and fatigue of passengers and the crew onboard ships is also due to the low frequency noise and vibration. Innovative approaches are therefore, required to attenuate the noise and vibration at low frequencies. This book was developed from several specialized research topics on vibration and vibration control of ship structures, mostly from the author's own PhD work at the University of Western Australia. The book aims to provide a better understanding of vibration characteristics of ribbed plate structures, plate/plate coupled structures and the mechanism governing wave propagation and attenuation in periodic and irregular ribbed structures as well as in complex ship structures. The book is designed to be a reference book for ship builders, vibro-acoustic engineers and researchers. The author also hopes that the book can stimulate more exciting future work in this area of research. It is the author's humble desire that the book can be some use for those who purchase it. This book is divided into eight chapters. Each chapter focuses on providing solution to address a particular issue on vibration problems of ship structures. A brief summary of each chapter is given in the general introduction. All chapters are inter-dependent to each other to form an integration volume on the subject of vibration and vibration control of ship structures and alike. I am in debt to many people in completing this work. In particular, I would like to thank Professor J. Pan, Dr N.H. Farag, Dr K. Sum and many others from the University of Western Australia for useful advices and helps during my times at the University and beyond. I would also like to thank my wife, Miaoling Wang, my children, Anita, Sophia and Angela Lin, for their sacrifice and continuing supports to make this work possible. Financial supports from Australian Research Council, Australian Defense Science and Technology Organization and Strategic Marine Pty Ltd at Western Australia for this work is gratefully acknowledged.