Dispersion engineering of highly nonlinear chalcogenide suspended-core fibers

Chalcogenide optical fibers are currently undergoing intensive investigation with the aim of exploiting the excellent glass transmission and nonlinear characteristics in the near- and mid-infrared for several applications. Further enhancement of these properties can be obtained, for a particular application, with optical fibers specifically designed that are capable of providing low effective area together with a properly tailored dispersion, matching the characteristics of the laser sources used to excite nonlinear effects. Suspended-core photonic crystal fibers are ideal candidates for nonlinear applications, providing small-core waveguides with large index contrast and tunable dispersion. In this paper, the dispersion properties of As2S3 suspended-core fibers are numerically analyzed, taking into account, for the first time, all the structural parameters, including the size and the number of the glass bridges. The results show that a proper design of the cladding struts can be exploited to significantly change the fiber properties, altering the maximum value of the dispersion parameter and shifting the zero-dispersion wavelengths over a range of 400 nm.

Ecfrasis: Escritura y pintura en el costumbrismo argentino

This dissertation examines the discursive practice of Argentine costumbrista texts from a novel perspective. In (re)reading the works of selected prominent writers from the late colonial period to the end of the Nineteenth Century, including those of Alonso Carrió de la Vandera, Emeric Essex Vidal, León Pallière, Lucio Vicente López, Lucio V. Mansilla, and Pastor Obligado we focus on the presence of ekphrastic enunciations with a view toward linking the plastic, painterly dimensions of the prose to parallel representations by artists of the same period. Thus the costumbristas are studied in tandem with the watercolors, oil paintings and lithographic compositions of artists such as Carlos Enrique Pellegrim, César Hipólito Bacle, Raymond Monvoisin and Hipólito Moulin. The resulting comparative study of the two arts---the verbal and the pictorial---illustrates the notion described by W. J. T. Mitchell that a literary text may well "represent a work of visual or graphic art." And thus, it provides us with visual, spatial motifs that enhance its powers of representation. ^ In developing our focus on ekphrastic representations we have followed the theoretic studies of Murray Krieger, Jean H. Hagstrum, James Hefferman, John Hollander, W. J. T. Mitchell, Johann Gottfried Herder, and Wendy Steiner among others, all of whom in various ways take their cue from Horace's Ut pictura poesis and the notion that poetry, that is literary discourse, can be likened to a panting and that in both arts there is a refractive quality that makes literature a spoken vehicle of expression and painting a silent, complementary voice. ^ In studying the literary and plastic discourses comparatively what becomes evident is that they share cultural and ideological concerns that center around the notion of self-definition, national identity, and the relation of the individual to the incipient national community (Benedict Anderson). These concerns are highlighted via the depiction of customs, mores, dress, work habits, professions, and social classes. In late colonial literature and painting and especially in the Nineteenth Century, which constitutes the defining period of Argentine political independence, the confluence of the two disciplinary discourses addresses, and underscores the issues of socio-political empowerment in the new Argentine nation. ^

[Poster] Friends of the Island

This poster presentation will exhibit the ongoing design work within two small islands adjacent to Diner Key Marina gifted by the City of Miami to the non-profit organization, Shake-A-Leg. This organization works to blur the lines between access, recreation, and skill, redefining what is possible. Abled and disabled children, adolescents, and young adults go to Shake-A-Leg to participate in a myriad of activities such as sailing, kayaking, swimming, painting, and socializing in these islands regardless of their inadequate walkways and installations. The users are people from different social statuses, physical and mental abilities. This poster will exhibit the design proposal to enhance the islands’ infrastructure to provide seamless access to all its visitors through the lush habitat in these islands. The proposed program challenges the disabilities of the person and helps them to mediate and transform them into new possibilities and abilities. The program proposes ten components which include a nature trail, restrooms, dinning center, art studio, and observation deck. The design of each space draws from the sailing boat to create solutions were the user will explore, participate and enjoy. The location encourages a feeling of challenge but at the same time it is a place for relief and freedom, allowing them to discover the diversity through experimentation and interaction with the environment. This poster presents design principles that value equal access and experience, celebrating the differences among users and the environment, blurring the lines between nature and access.

An investigation of twentieth century observant Jewish fine artists

People of the Jewish faith base their belief on the written word of the Torah. Presented in this paper are fine artists that produce work within these laws. The Torah sets guidelines for life and morality. The belief system within this domain is that visual images have an impact on the viewers, and artists are accountable for what they produce. This is in opposition with art education, where freedom of expression takes precedence over morality. The results of this study will form the basis for a curriculum for the community college. The researcher's area of inquiry is directed to painting and sculpture made by artists of the Jewish faith who follow the Torah, meaning those who are observant of their faith and practices. Their skills and perceptions will be presented to educate the viewer about their visions. The research questions were posed to rabbinical authorities and artists in order to establish a clear and defined statement of what the Jewish law is regarding the fine arts. The evidence presented was obtained by questionnaires, personal interviews, articles, and opinions from Jewish scholars. Four rabbis were selected based on their erudition on Torah law, and their strong leadership positions in Jewish educational institutions. The ten artists were selected based on recommendations from art historians, and art and gallery directors. The artists and the rabbis were mailed questionnaires, which was followed by an interview. The conclusion from this study is that fine artists are encouraged to use their talents, this is supported by the Torah text, and rabbinic explanation. The restriction for the Jewish artist is in making a replication of a realistic full-scale figure, making a visual rendition of G-d, a nude, or violent image. Art is made by the observant Jew with the intention of enhancing the world with visions inspired by their belief in the Torah. A crucial belief in Judaism is that there is but one G-d, and all man-made images should reflect the majesty of G-d's creations.

LCD-OpenPACS: sistema integrado de telerradiologia com auxílio ao diagnóstico de nódulos pulmonares em exames de tomografia computadorizada

Lung cancer is one of the most common types of cancer and has the highest mortality rate. Patient survival is highly correlated with early detection. Computed Tomography technology services the early detection of lung cancer tremendously by offering aminimally invasive medical diagnostic tool. However, the large amount of data per examination makes the interpretation difficult. This leads to omission of nodules by human radiologist. This thesis presents a development of a computer-aided diagnosis system (CADe) tool for the detection of lung nodules in Computed Tomography study. The system, called LCD-OpenPACS (Lung Cancer Detection - OpenPACS) should be integrated into the OpenPACS system and have all the requirements for use in the workflow of health facilities belonging to the SUS (Brazilian health system). The LCD-OpenPACS made use of image processing techniques (Region Growing and Watershed), feature extraction (Histogram of Gradient Oriented), dimensionality reduction (Principal Component Analysis) and classifier (Support Vector Machine). System was tested on 220 cases, totaling 296 pulmonary nodules, with sensitivity of 94.4% and 7.04 false positives per case. The total time for processing was approximately 10 minutes per case. The system has detected pulmonary nodules (solitary, juxtavascular, ground-glass opacity and juxtapleural) between 3 mm and 30 mm.

Fabricação e caracterização de um compósito hibrido com resíduo lignocelulósico

This work aims to manufacture and characterize a hybrid plastic composite with the matrix isophthalic polyester resin base and having as reinforcing glass fiber and the dry endocarp of coconut (Coco nucifera Linn) in the form of particles as filler. The composite was made industrially in Tecniplas Industry and Trade LTDA. in the form of plate, and was manufactured process made by the manual lamination (Hand Lay Up). From the plate they were prepared test specimens for testing density, water absorption, uniaxial traction in dry and wet states, and testing of bending, as well as studies on the behavior of the generated fractures, macroscopic and microscopic, in mechanical tests through. All tests were performed in order to find the most viable applications the hybrid composite manufactured. The tensile and bending tests were analyzed last tensile properties, elasticity and deformation module. After the studies, it is observed that the percentage moisture absorbed was 3.03%. The presence of moisture in the tensile test meant a decrease of 19.77% from last stand, and 5.26% in the elastic modulus. For bending tests gave an average value of 69.13 MPa flexural strength. The results show the application of hybrid composite studied in lightweight structures, indoors, which require low / medium performance traction demands, and which involve flexural requests.

Resposta de ovinos naturalmente infectados por nematoides gastrintestinais em pastos de capim-massai

The aim of this study was to evaluate the crossbred sheep Santa Ines response to natural infections by gastrointestinal nematodes in Panicum maximum cv. pastures Massai at different times of grazing. For this it was used 36 crossbred sheep Santa Inês, divided into four groups and randomly distributed in massai-grass pickets naturally infected by gastrointestinal nematodes. In the period from October 2013 to May 2014, the animals were weekly monitored for hematology tests (packed cell volume) and parasitological (egg counts per gram of feces and fecal culture) in order to monitor the level of infection of sheep and they were assessed for weight, body condition score and staining ocular mucosa by FAMACHA© method. Furthermore infective larvae was recovery from pasture in times of pre-and post-grazing pasture. At 35 kg body weight, the animals were slaughtered and necropsied to collect the contents of the abomasum and small and large intestines to recover the adult parasites, carrying out the count and identification. The animals on pasture with a height of 40 cm pre-grazing obtained low nematode eggs in feces (1608 eggs / g) and 33 cm those in pre-grazing the highest average (2,539 eggs / g). The animals in different groups showed mean values of packed cell volume less than 23% (P> 0.05). Regarding to FAMACHA, the animals belonging to the groups 40 and 50 cm pre-grazing remained over 50% of individuals between FAMACHA 1 and 2 , and those to 33 and 45 cm pre-grazing showed mostly between FAMACHA 3, 4 and 5 (69.06% and 58.93%, respectively). In the culture of larvae in feces and recovery of pasture larvae before and after grazing the following genera were found, in order of prevalence: Haemonchus, Trichostrongylus, Oesophagostomum and Strongyloides. The pasture with 33 cm of pre-grazing provided the highest number of larvae recovered both in the pre and post-grazing (1,081 and 715 L3 / 100 g of green matter, respectively). Among the different groups, the sheep had an average weight of between 23 and 26 kg and variation between the body 1 and 3 scores with scores greater frequency of 1.5 to 2.It can be observed that the animals kept at different times of grazing got different answers on the parasite load. Animals kept in 40 cm pre-grazing expressed a satisfactory answer than the other groups (33, 45 and 50 cm), best supporting the action of endoparasites. Moreover, this same height, was recovered fewer infective larvae on pasture in pre and post-grazing.

On the Origin of Natural Antibody

Natural IgM (nIgM) is constitutively present in the serum, where it aids in the early control of viral and bacterial expansions. nIgM also plays a significant role in the prevention of autoimmune disease by promoting the clearance of cellular debris. However, the cells that maintain high titers of nIgM in the circulation had not yet been identified. Several studies have linked serum nIgM with the presence of fetal-lineage B cells, and others have detected IgM secretion directly by B1a cells in various tissues. Nevertheless, a substantial contribution of undifferentiated B1 cells to nIgM titers is doubtful, as the ability to produce large quantities of antibody (Ab) is a function of the phenotype and morphology of differentiated plasma cells (PCs). No direct evidence exists to support the claim that a B1-cell population directly produces the bulk of circulating nIgM. The source of nIgM thus remained uncertain and unstudied.

In the first part of this study, I identified the primary source of nIgM. Using enzyme-linked immunosorbent spot (ELISPOT) assay, I determined that the majority of IgM Ab-secreting cells (ASCs) in naïve mice reside in the bone marrow (BM). Flow cytometric analysis of BM cells stained for intracellular IgM revealed that nIgM ASCs express IgM and the PC marker CD138 on their surface, but not the B1a cell marker CD5. By spinning these cells onto slides and staining them, following isolation by fluorescence-activated cell sorting (FACS), I found that they exhibit the typical morphological characteristics of terminally differentiated PCs. Transfer experiments demonstrated that BM nIgM PCs arise from a progenitor in the peritoneal cavity (PerC), but not isolated PerC B1a, B1b, or B2 cells. Immunoglobulin (Ig) gene sequence analysis and examination of B1-8i mice, which carry an Ig knockin that prohibits fetal B-cell development, indicated that nIgM PCs differentiate from fetal-lineage B cells. BrdU uptake experiments showed that the nIgM ASC compartment contains a substantial fraction of long-lived plasma cells (LLPCs). Finally, I demonstrated that nIgM PCs occupy a survival niche distinct from that used by IgG PCs.

In the second part of this dissertation, I characterized the unique survival niche of nIgM LLPCs, which maintain constitutive high titers of nIgM in the serum. By using genetically deficient or Ab-depleted mice, I found that neither T cells, type 2 innate lymphoid cells, nor mast cells, the three major hematopoietic producers of IL-5, were required for nIgM PC survival in the BM. However, IgM PCs associate strongly with IL-5-expressing BM stromal cells, which support their survival in vitro when stimulated. In vivo neutralization of IL-5 revealed that, like individual survival factors for IgG PCs, IL-5 is not the sole supporter of IgM PCs, but is likely one of several redundant molecules that together ensure uninterrupted signaling. Thus, the long-lived nIgM PC niche is not composed of hematopoietic sources of IL-5, but a stromal cell microenvironment that provides multiple redundant survival signals.

In the final part of my study, I identified and characterized the precursor of nIgM PCs, which I found in the first project to be resident in the PerC, but not a B1a, B1b, or B2 cell. By transferring PerC cells sorted based on expression of CD19, CD5, and CD11b, I found that only the CD19+CD5+CD11b- population contained cells capable of differentiating into nIgM PCs. Transfer of decreasing numbers of unfractionated PerC cells into Rag1 knockouts revealed an order-of-magnitude drop in the rate of serum IgM reconstitution between stochastically sampled pools of 106 and 3x105 PerC cells, suggesting that the CD19+CD5+CD11b- compartment comprises two cell types, and that interaction between the two necessary for nIgM-PC differentiation. By transferring neonatal liver, I determined that the early hematopoietic environment is required for nIgM PC precursors to develop. Using mice carrying a mutation that disturbs cKit expression, I also found that cKit appears to be required at a critical point near birth for the proper development of nIgM PC precursors.

The collective results of these studies demonstrate that nIgM is the product of BM-resident PCs, which differentiate from a PerC B cell precursor distinct from B1a cells, and survive long-term in a unique survival niche created by stromal cells. My work creates a new paradigm by which to understand nIgM, B1 cell, and PC biology.

Geochemistry of Chixulub ejecta in ODP Leg 207 holes

An up to 2-cm thick Chicxulub ejecta deposit marking the Cretaceous-Paleogene (K-Pg) boundary (the "K-T" boundary) was recovered in six holes drilled during ODP Leg 207 (Demerara Rise, tropical western Atlantic). Stunning features of this deposit are its uniformity over an area of 30 km2 and the total absence of bioturbation, allowing documentation of the original sedimentary sequence. High-resolution mineralogical, petrological, elemental, isotopic (Sr-Nd), and rock magnetic data reveal a distinct microstratigraphy and a range of ejecta components. The deposit is normally graded and composed predominantly of rounded, 0.1- to max. 1-mm sized spherules. Spherules are altered to dioctahedral aluminous smectite, though occasionally relict Si-Al-rich hydrated glass is also present, suggesting acidic precursor lithologies. Spherule textures vary from hollow to vesicle-rich to massive; some show in situ collapse, others include distinct Fe-Mg-Ca-Ti-rich melt globules and lath-shaped Al-rich quench crystals. Both altered glass spherules and the clay matrix (Site 1259B) display strongly negative epsilon-Nd (T=65Ma) values (-17) indicating uptake of Nd from contemporaneous ocean water during alteration. Finally, Fe-Mg-rich spherules, shocked quartz and feldspar grains, few lithic clasts, as well as abundant accretionary and porous carbonate clasts are concentrated in the uppermost 0.5-0.7 mm of the deposit. The carbonate clasts display in part very unusual textures, which are interpreted to be of shock-metamorphic origin. The preservation of delicate spherule textures, normal grading with lack of evidence for traction transport, and sub-millimeter scale compositional trends provide evidence for this spherule deposit representing a primary air-fall deposit not affected by significant reworking. The ODP Leg 207 spherule deposit is the first known dual-layer K-Pg boundary in marine settings; it incorporates compositional and stratigraphic aspects of both proximal and distal marine sites. Its stratigraphy strongly resembles the dual-layer K-Pg boundary deposits in the terrestrial Western Interior of North America (although there carbonate phases are not preserved). The occurrence of a dual ejecta layer in these quite different sedimentary environments - separated by several thousands of kilometers - provides additional evidence for an original sedimentary sequence. Therefore, the layered nature of the deposit may document compositional differences between ballistic Chicxulub ejecta forming the majority of the spherule deposit, and material falling out from the vapor (ejecta) plume, which is concentrated in the uppermost part.

Measurement of electromagnetic pulses generated during interactions of high power lasers with solid targets

A target irradiated with a high power laser pulse, blows off a large amount of charge and as a consequence the target itself becomes a generator of electromagnetic pulses (EMP) owing to high return current flowing to the ground through the target holder. The first measurement of the magnetic field induced by the neutralizing current reaching a value of a few kA was performed with the use of an inductive target probe at the PALS Laser Facility (Cikhardt et al. Rev. Sci. Instrum. 85 (2014) 103507). A full description of EMP generation should contain information on the spatial distribution and temporal variation of the electromagnetic field inside and outside of the interaction chamber. For this reason, we consider the interaction chamber as a resonant cavity in which different modes of EMP oscillate for hundreds of nanoseconds, until the EMP is transmitted outside through the glass windows and EM waves are attenuated. Since the experimental determination of the electromagnetic field distribution is limited by the number of employed antennas, a mapping of the electromagnetic field has to be integrated with numerical simulations. Thus, this work reports on a detailed numerical mapping of the electromagnetic field inside the interaction chamber at the PALS Laser Facility (covering a frequency spectrum from 100 MHz to 3 GHz) using the commercial code COMSOL Multiphysics 5.2. Moreover we carried out a comparison of the EMP generated in the parallelepiped-like interaction chamber used in the Vulcan Petawatt Laser Facility at the Rutherford Appleton Laboratory, against that produced in the spherical interaction chamber of PALS.

Enhancing Quality of Life for People who are Blind or Low Vision Using Computing Technology

Thesis (Ph.D.)--University of Washington, 2016-08

Doppelgänger

Catalogue and invitation card for Exhibition at Eagle Gallery, London. 16 June – 16 July 2016 “My paintings are like ghost schema, assemblages of images and surfaces that generate spectral encounters.” James Fisher’s paintings are carefully calibrated. They explore dualities and employ complex visual palimpsests to construct images that are rich with association. Abstract and figurative motifs are laid on different layers of their surfaces, covered over, and re-discovered through sanding back the paint. As a former British School at Rome Scholar, Fisher’s early work was influenced by the study of fresco painting and he retains an approach that allows for time and chance to enter the process of painting. Fabrication – in the sense both of making things and making things up – produces enigmatic and mysterious results. Many of Fisher’s recent paintings are titled after notable, now forgotten women, or after characters from folklore and comic books. The range of subject matter allows him to conflate biography with fiction, and to borrow from a wide range of visual sources for patterned elements that formally hold in place the more fugitive suggestions of the images. Fisher’s fourth solo exhibition at the Eagle Gallery coincides with the selection of two works in this year’s Royal Academy Summer Exhibition, and his inclusion in Towards Night – a forthcoming exhibition at the Towner, Eastbourne.

Towards Night

Sixty artists explore the nocturnal. Curated by Tom Hammick. The evening hour too gives us the irresponsibility which darkness and lamplight bestow. We are no longer quite ourselves. – Virginia Woolf, Street Haunting: A London Adventure, 1930 Towards Night is an exhibition exploring the nocturnal through paintings, prints and drawings by over sixty artists. Drawing on the nineteenth century European Romantic tradition, the show surveys contemporary and historical connections to wonderment and dystopia at dusk, twilight, night and dawn. Towards Night juxtaposes key paintings and prints by Constable, Friedrich, Munch, Nolde, Palmer and Turner, some of the best known visionaries of the Romantic tradition with contemporary artists who work with the transformative aspects of nightfall to convey emotional responses of awe, anxiety and solitude, love and loss, revelry, insomnia, and journey’s end. The exhibition opens with direct and positive responses to the natural world; Marc Chagall’s exotic dreamlike evening in The Poet Reclining (1915) sits close to eighteenth century Indian miniatures depicting brightly painted figures offset against darkening monsoon clouds, and William Crozier’s Balcony at Night, Antibes (2007), of a plant, blue and iridescent against the cool night sky. As the exhibition progresses, the dystopias become darker and more disturbing, and the connections between artists and works intensify: Emma Stibbon’s Rome Aqueduct (2011) takes on a heightened sense of pathos alongside Caspar David Friedrich’s Winter Landscape (1811); Peter Doig’s cinematic Echo Lake (1998) conjures up an increased sense of contemporary angst; and Prunella Clough’s False Flower (1993), a magical tree defying brutalism by growing out of concrete, becomes more miraculous near Night Shift (2015) Nick Carrick’s tomblike high rise. Tom Hammick’s Violetta Alone (2015) and Michael Craig Martin’s Ash Tray (2015), reinforce hedonistic aspects of night-time revelry alongside Four AM, Betsy Dadd’s young woman drinking in the early hours of the morning and L.S. Lowry’s drunken people in a pub in The Crowd (1922). In the final room, a cluster of works explores dreams and insomnia, from Louise Bourgeois’ Spirals (2010) to Munch’s lovers embracing in The Kiss (1902). Tom Hammick, curator of the show said “This exhibition has grown way beyond its original conception, to become a magnificent survey of painting and printmaking from over two hundred years based around the central tenet of night. The exhibition is a kind of painterly response to the way figurative artists use their artistic heroes as starting points for their own work, both compositionally and emotionally.” Artists featured in Towards Night: Christiane Baumgarter, Michael Craig-Martin, Julian Opie, Will Gill, Merlin James, Howard Hodgkin, WillIam Scott, Patrick Caulfield, George Shaw, Stephen Chambers, Basil Beattie, Betsy Dadd, Christopher Le Brun, L.S Lowry, Andrew Cranston, David Willetts, James Fisher, Emma Stibbon, Vija Celmins, William Blake, William Crozier, Tom Hammick, Georgia Keeling, Helen Turner, Humphrey Ocean, Julian Bell, Craigie Aitchison, Mark Wright, Ken Kiff, Matthew Burrows, Andrzej Jackowski, Sarah Raphael, Nick Bodimeade, Nick Carrick, Mary Newcomb, Hurvin Anderson, Peter Doig, Phoebe Unwin, Danny Markey, Sara Lee, Simon Burton, Susie Hamilton, Marc Chagall, Alfred Wallis, Emil Nolde, J.M.W. Turner, Prunella Clough, Samuel Palmer, Louise Bourgeois, Caspar David Friedrich, Alex Katz, Ewan Gibbs, Susie Hamilton, Andrzej Jackowski, Amanda Vesey, Edward Stott, Gertrude Hermes, Rose Wylie, Sidney Nolan, John Constable, J.M.W. Turner, Emil Nolde, Hiroshige, Edvard Munch, Samuel Palmer, Eileen Cooper, Charles Neame-Spencer, Samantha Cary.

Die Feldspatgehalte quartärzeitlicher Sande Niedersachsens

The feldspar contents of 373 samples from quaternary sands of Lower Saxony (West Germany) were determined. The samples were taken in all parts of Lower Saxony and represent a selec- tion of quaternary Sediments of different age and genetic origin. 7 different methods of investigation were tested to determine the content of feldspar both qualitative and quantitative. Polarizing mioroscopy, x-ray diffractometry, Chemical analysis and staining fit these aims best. The most important results of these investigations are: - The quarternary Lower Saxonian sands have an average content of 4.4 weight-% potassium feldspars and 0.8 weight-% plagio- clase. - All tested samples have a similar qualitative feldspar compo- sition. There are monocline, tricline and - more rare - per- thitic potassium feldspars with a rather high (greater 80 %) KAlSi3O8 content. From the plagioclase feldspars only albite, oligoclase and little andesine were indicated. - The potassium feldspar content is higher in each sample than the plagioclase content. - The feldspar content depends on age and genetic origin of each sand. Generally spoken the feldspar content lessens with increasing age. Glaciofluviatile and basin sands usually have a higher feldspar content than fluvial or aeolian sands of the same age. - The feldspar content is highly influenced by grain size com- position. A minimum of feldspar content lies between 0.4 and 1 .0 mm grain size. Fine sands usually have a higher feldspar content than coarse sands. The reason for this phenomenon is weathering. - There are no regional differences in the amount of feldspar content. - The feldspar content is not high enough for commercial mining.

Hybrid materials for biomedical applications

The increased longevity of humans and the demand for a better quality of life have led to a continuous search for new implant materials. Scientific development coupled with a growing multidisciplinarity between materials science and life sciences has given rise to new approaches such as regenerative medicine and tissue engineering. The search for a material with mechanical properties close to those of human bone produced a new family of hybrid materials that take advantage of the synergy between inorganic silica (SiO4) domains, based on sol-gel bioactive glass compositions, and organic polydimethylsiloxane, PDMS ((CH3)2.SiO2)n, domains. Several studies have shown that hybrid materials based on the system PDMS-SiO2 constitute a promising group of biomaterials with several potential applications from bone tissue regeneration to brain tissue recovery, passing by bioactive coatings and drug delivery systems. The objective of the present work was to prepare hybrid materials for biomedical applications based on the PDMS-SiO2 system and to achieve a better understanding of the relationship among the sol-gel processing conditions, the chemical structures, the microstructure and the macroscopic properties. For that, different characterization techniques were used: Fourier transform infrared spectrometry, liquid and solid state nuclear magnetic resonance techniques, X-ray diffraction, small-angle X-ray scattering, smallangle neutron scattering, surface area analysis by Brunauer–Emmett–Teller method, scanning electron microscopy and transmission electron microscopy. Surface roughness and wettability were analyzed by 3D optical profilometry and by contact angle measurements respectively. Bioactivity was evaluated in vitro by immersion of the materials in Kokubos’s simulated body fluid and posterior surface analysis by different techniques as well as supernatant liquid analysis by inductively coupled plasma spectroscopy. Biocompatibility was assessed using MG63 osteoblastic cells. PDMS-SiO2-CaO materials were first prepared using nitrate as a calcium source. To avoid the presence of nitrate residues in the final product due to its potential toxicity, a heat-treatment step (above 400 °C) is required. In order to enhance the thermal stability of the materials subjected to high temperatures titanium was added to the hybrid system, and a material containing calcium, with no traces of nitrate and the preservation of a significant amount of methyl groups was successfully obtained. The difficulty in eliminating all nitrates from bulk PDMS-SiO2-CaO samples obtained by sol-gel synthesis and subsequent heat-treatment created a new goal which was the search for alternative sources of calcium. New calcium sources were evaluated in order to substitute the nitrate and calcium acetate was chosen due to its good solubility in water. Preparation solgel protocols were tested and homogeneous monolithic samples were obtained. Besides their ability to improve the bioactivity, titanium and zirconium influence the structural and microstructural features of the SiO2-TiO2 and SiO2-ZrO2 binary systems, and also of the PDMS-TiO2 and PDMS-ZrO2 systems. Detailed studies with different sol-gel conditions allowed the understanding of the roles of titanium and zirconium as additives in the PDMS-SiO2 system. It was concluded that titanium and zirconium influence the kinetics of the sol-gel process due to their different alkoxide reactivity leading to hybrid xerogels with dissimilar characteristics and morphologies. Titanium isopropoxide, less reactive than zirconium propoxide, was chosen as source of titanium, used as an additive to the system PDMS-SiO2-CaO. Two different sol-gel preparation routes were followed, using the same base composition and calcium acetate as calcium source. Different microstructures with high hydrophobicit were obtained and both proved to be biocompatible after tested with MG63 osteoblastic cells. Finally, the role of strontium (typically known in bioglasses to promote bone formation and reduce bone resorption) was studied in the PDMS-SiO2-CaOTiO2 hybrid system. A biocompatible material, tested with MG63 osteoblastic cells, was obtained with the ability to release strontium within the values reported as suitable for bone tissue regeneration.