Development of Craniofacial Bone Defect Reconstruction Implant Based on Fibre-Reinforced Composite with Photopolymerisable Resin Systems. Experimental studies in vitro and in vivo.

Reconstruction of defects in the craniomaxillofacial (CMF) area has mainly been based on bone grafts or metallic fixing plates and screws. Particularly in the case of large calvarial and/or craniofacial defects caused by trauma, tumours or congenital malformations, there is a need for reliable reconstruction biomaterials, because bone grafts or metallic fixing systems do not completely fulfill the criteria for the best possible reconstruction methods in these complicated cases. In this series of studies, the usability of fibre-reinforced composite (FRC) was studied as a biostable, nonmetallic alternative material for reconstructing artificially created bone defects in frontal and calvarial areas of rabbits. The experimental part of this work describes the different stages of the product development process from the first in vitro tests with resin-impregnated fibrereinforced composites to the in vivo animal studies, in which this FRC was tested as an implant material for reconstructing different size bone defects in rabbit frontal and calvarial areas. In the first in vitro study, the FRC was polymerised in contact with bone or blood in the laboratory. The polymerised FRC samples were then incubated in water, which was analysed for residual monomer content by using high performance liquid chromatography (HPLC). It was found that this in vitro polymerisation in contact with bone and blood did not markedly increase the residual monomer leaching from the FRC. In the second in vitro study, different adhesive systems were tested in fixing the implant to bone surface. This was done to find an alternative implant fixing system to screws and pins. On the basis of this study, it was found that the surface of the calvarial bone needed both mechanical and chemical treatments before the resinimpregnated FRC could be properly fixed onto it. In three animal studies performed with rabbit frontal bone defects and critical size calvarial bone defect models, biological responses to the FRC implants were evaluated. On the basis of theseevaluations, it can be concluded that the FRC, based on E-glass (electrical glass) fibres forming a porous fibre veil enables the ingrowth of connective tissues to the inner structures of the material, as well as the bone formation and mineralization inside the fibre veil. Bone formation could be enhanced by using bioactive glass granules fixed to the FRC implants. FRC-implanted bone defects healed partly; no total healing of defects was achieved. Biological responses during the follow-up time, at a maximum of 12 weeks, to resin-impregnated composite implant seemed to depend on the polymerization time of the resin matrix of the FRC. Both of the studied resin systems used in the FRC were photopolymerised and the heat-induced postpolymerisation was used additionally.

Taajuusmuttajan vanheneminen syklisissä käytöissä

Tässä työssä tarkastellaan taajuusmuuttajan vanhenemista syklisissä käytöissä puolijohdetehokomponenttien osalta. Laitteiden vikaantumisprosessien analysoimiseksi työssä suunnitellaan syklinen kestotestausjärjestelmä, joka mahdollistaa useamman taajuusmuuttajan yhtäaikaisen vanhentamisen. Jaksottaisesti toistuvat kuormitussyklit rasittavat termomekaanisesti taajuusmuuttajan tehomoduulin sisäisiä rakenteita suurten lämpötilavaihtelujen johdosta. Teoriaosuuden pääpaino kohdistuu puolijohdetehokomponenttien rakenteeseen, vikaantumisprosesseihin ja eliniän kartoittamiseen. Työssä käydään läpi yleisimpien pienijännitteisten moottorinohjausinverttereiden tehomoduulien mekaaniset rakenteet, tyypillisemmät syklisestä kuormituksesta johtuvat vikaantumisprosessit sekä puolijohdetehokomponenttivalmistajien käyttämät syklisen eliniän testausmenetelmät. Loppuosassa työtä suunnitellaan taajuusmuuttajan syklinen kestotestausjärjestelmä laitteiden keinotekoista vanhentamista varten. Testausjärjestelmällä voidaan kuormittaa useampaa taajuusmuuttajaa vuorottain mielivaltaisella kuormitusvirtaprofiililla. Laitteita vanhennettiin kaksi testierää kuormittamalla niitä jaksottaisesti hissikäytön tyypillisellä kuormitusprofiililla. Puolijohdetehokomponentin vanhenemisen edistystä seurattiin termisen impedanssiketjun mittausmenetelmällä, joka perustuu IGBT:n kollektoriemitterijännitteen lämpötilariippuvuuteen. Testilaitteiden puolijohdetehokomponentit hajosivat syklisen eliniän päättymiseen teoriassa esitettyjen vikaantumisprosessien seurauksesta. Tehomoduulien vika-analyysi osoittaa syklisen kestotestausjärjestelmän soveltuvaksi menetelmäksi tutkia erilaisten kuormitusprofiilien vaikutusta taajuusmuuttajan vanhenemiseen.

Avaliação da porosidade de microcápsulas contendo proteína bioativa por porosimetria de mercúrio e adsorção de nitrogênio

Microcapsules containing lactoferrin were produced by spray drying using dextrin:octenylsuccinate starch, as wall materials. Porosity characteristics of spray-dried microcapsules were investigated by mercury intrusion porosimetry and nitrogen adsorption. The outer and inner structures of microcapsules were studied by Scanning Electron Microscopy and sizes were determined by Laser Diffraction. Results indicate that all microcapsules presents adsorption isotherm of type II and that micropores on the microcapsules surface will be very few or none. Our results show that microstructure, surface area and size of microcapsules are affected by dextrin: octenylsuccinate starch proportion. Pore characteristics for various microcapsules are found to be different.

Effects of Synthesis Conditions on the Nanostructure of Hybrid Sols Produced by the Hydrolytic Condensation of (3-Methacryloxypropyl)trimethoxysilane

Polysilsesquioxanes containing methacrylate pendant groups were prepared by the sol-gel process through hydrolysis and condensation of (3-methacryloxypropyl)trimethoxysilane (MPTS) dissolved in a methanol/methyl methacrylate (MMA) mixture. The effects of different water, MMA, and methanol contents, as well as of pH, on the nanoscopic and local structures of the system, at advanced stages of the condensation reaction, were studied by small-angle X-ray scattering (SAXS) and (29)Si nuclear magnetic resonance (NMR) spectroscopy, respectively. SAXS results indicate that the nanoscopic features of the hybrid sol could be described by a hierarchical model composed of two levels, namely (i) silsesquioxane (SSQO) nanoparticles Surrounded by the methacrylate pendant groups and the methanol/MMA mixture. and (ii) aggregation zones or islands containing correlated SSQO nanoparticles, embedded in the liquid medium. The (29)Si NMR results Show that the inner Structures of SSQO nanoparticles produced at pH 1 and 3 were built Up of polyhedral structures. mainly cagelike octamers and small linear oligomers, respectively. Irrespective of MMA and methanol contents, for a [H(2)O]/[MPTS] ratio higher than or equal to 1, the SSQO nailoparticles produced at pH I exhibit an average condensation degree (CD approximate to 69-87%) and average radius of gyration (R(g) approximate to 2.5 angstrom) larger than those produced at pH 3 (CD approximate to 48-67% and R(g) approximate to 1.5 angstrom). Methanol appears to act as a redispersion agent, by decreasing the number of particles inside the aggregation zones, while the addition of MMA induces a swelling of the aggregation zones.

Estudo do inter-relacionamento dos problemas humanos e organizacionais.

Este estudo-piloto é uma tentativa de abordar a questão do inter-relacionamento entre os problemas humanos e organizacionais, centrando-se a análise na descoberta dos fatores que facilitam ou impedem a satisfação no trabalho, em uma empresa de prestação de serviços públicos a todo o estado do Rio de Janeiro. Já o modelo de análise organizacional proposto considera a organização e o indivíduo como um sistema permeável às características da sociedade tornando-se, desse modo, fundamental que se determina-se há inter-relações entre os fatores socioeconômicos, mais diretamente ligados à estrutura social, e os fatores motivacionais, mais diretamente ligados à estrutura interna do indivíduo e da empresa. Através da discussão dos resultados, alguns subsídios foram dados à empresa para fazer frente aos complexos problemas que surgiram em face da modificação de seu meio-ambiente (interno e externo). Várias considerações foram feitas quanto ao problema da "medida" da satisfação no trabalho, tendo sido discutida, no último capítulo, a viabilidade de se estender a presente pesquisa a toda a organização.

Effects of Synthesis Conditions on the Nanostructure of Hybrid Sols Produced by the Hydrolytic Condensation of (3-Methacryloxypropyl)trimethoxysilane

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Compressed sensing in digital tomosynthesis reconstruction

In this work we study a model for the breast image reconstruction in Digital Tomosynthesis, that is a non-invasive and non-destructive method for the three-dimensional visualization of the inner structures of an object, in which the data acquisition includes measuring a limited number of low-dose two-dimensional projections of an object by moving a detector and an X-ray tube around the object within a limited angular range. The problem of reconstructing 3D images from the projections provided in the Digital Tomosynthesis is an ill-posed inverse problem, that leads to a minimization problem with an object function that contains a data fitting term and a regularization term. The contribution of this thesis is to use the techniques of the compressed sensing, in particular replacing the standard least squares problem of data fitting with the problem of minimizing the 1-norm of the residuals, and using as regularization term the Total Variation (TV). We tested two different algorithms: a new alternating minimization algorithm (ADM), and a version of the more standard scaled projected gradient algorithm (SGP) that involves the 1-norm. We perform some experiments and analyse the performance of the two methods comparing relative errors, iterations number, times and the qualities of the reconstructed images. In conclusion we noticed that the use of the 1-norm and the Total Variation are valid tools in the formulation of the minimization problem for the image reconstruction resulting from Digital Tomosynthesis and the new algorithm ADM has reached a relative error comparable to a version of the classic algorithm SGP and proved best in speed and in the early appearance of the structures representing the masses.

Tissue fusion, a new opportunity for sutureless bypass surgery

Microsurgical suturing is the standard for cerebral bypass surgery, a technique where temporary occlusion is usually necessary. Non-occlusive techniques such as excimer laser-assisted non-occlusive anastomosis (ELANA) have certainly widened the spectrum of treatment of complex cerebrovascular situations, such as giant cerebral aneurysms, that were otherwise non-treatable. Nevertheless, the reduction of surgical risks while widening the spectrum of indications, such as a prophylactic cerebral bypass, is still a main aim, that we would like to pursue with our sutureless tissue fusion research. The primary concern in sutureless tissue fusion- and especially in tissue fusion of cerebral vessels- is the lack of reproducibility, often caused by variations in the thermal damage of the vessel. This has prevented this novel fusion technique from being applicable in daily surgical use. In this overview, we present three ways to further improve the laser tissue soldering technique.In the first section entitled "Laser Tissue Soldering Using a Biodegradable Polymer," a porous polymer scaffold doped with albumin (BSA) and indocyanine green (ICG) is presented, leading to strong and reproducible tensile strengths in tissue soldering. Histologies and future developments are discussed.In the section "Numerical Simulation for Improvement of Laser Tissue Soldering," a powerful theoretical simulation model is used to calculate temperature distribution during soldering. The goal of this research is to have a tool in hand that allows us to determine laser irradiation parameters that guarantee strong vessel fusion without thermally damaging the inner structures such as the intima and endothelium.In a third section, "Nanoparticles in Laser Tissue Soldering," we demonstrate that nanoparticles can be used to produce a stable and well-defined spatial absorption profile in the scaffold, which is an important step towards increasing the reproducibility. The risks of implanting nanoparticles into a biodegradable scaffold are discussed.Step by step, these developments in sutureless tissue fusion have improved the tensile strength and the reproducibility, and are constantly evolving towards a clinically applicable anastomosis technique.

Fast ray-tracing algorithm for circumstellar structures (FRACS) II. Disc parameters of the B[e] supergiant CPD-57 degrees 2874 from VLTI/MIDI data

Context. B[e] supergiants are luminous, massive post-main sequence stars exhibiting non-spherical winds, forbidden lines, and hot dust in a disc-like structure. The physical properties of their rich and complex circumstellar environment (CSE) are not well understood, partly because these CSE cannot be easily resolved at the large distances found for B[e] supergiants (typically greater than or similar to 1 kpc). Aims. From mid-IR spectro-interferometric observations obtained with VLTI/MIDI we seek to resolve and study the CSE of the Galactic B[e] supergiant CPD-57 degrees 2874. Methods. For a physical interpretation of the observables (visibilities and spectrum) we use our ray-tracing radiative transfer code (FRACS), which is optimised for thermal spectro-interferometric observations. Results. Thanks to the short computing time required by FRACS (<10 s per monochromatic model), best-fit parameters and uncertainties for several physical quantities of CPD-57 degrees 2874 were obtained, such as inner dust radius, relative flux contribution of the central source and of the dusty CSE, dust temperature profile, and disc inclination. Conclusions. The analysis of VLTI/MIDI data with FRACS allowed one of the first direct determinations of physical parameters of the dusty CSE of a B[e] supergiant based on interferometric data and using a full model-fitting approach. In a larger context, the study of B[e] supergiants is important for a deeper understanding of the complex structure and evolution of hot, massive stars.

The expression of fibroblast growth factors and their receptors in the embryonic and neonatal mouse inner ear

Four different fibroblast growth factor receptors (FGFR) are known, three of which have splice variants (known as the b and c variants) in the FGF-binding domain, to give different patterns of sensitivity to the different FGFs. The expression of the b and c variants of the FGF receptors. together with the expression of the ligands FGF1. FGF2, FGF3, FGF7, FGF8b and FGF8c, was determined by quantitative reverse transcription-polymerase chain reaction in developing whole mouse inner ears, and in dissected components of the postnatal mouse inner ear. At embryonic age (E)10.5 days, when the otocyst is a simple closed sac, the receptor most heavily expressed was FGFR2b, relative to the postnatal day 0 level. Over the period E10.5-E12.5. during which the structures of the inner ear start to form, the expression of the different FGF receptors increased 10(2)-10(4) fold per unit of tissue, and there was a gradual switch towards expression of the 'c' splice variants of FGFR2 and FGFR3 rather than the 'b' variants. At E10.5, the ligands most heavily expressed, relative to the postnatal day 0 level, were FGF3, FGF8b and FGF8c. In the postnatal inner eat. the patterns of expression of receptors and ligands tended to be correlated, such that receptor variants were expressed in the same regions as the ligands that are known to activate them effectively. The neural/sensory region expressed high levels of FGFR3c, and high levels of the ligand FGF8b. The same area also expressed high levels of FGFR1b and FGFR2b, and high levels of FGF3. The lateral wall of the cochlea (including the stria vascularis and the spiral ligament) expressed high levels of FGFR1c and FGF1. 11 is suggested that the different FGF receptors and ligands are expressed in a spatially coordinated pattern to selectively program cochlear development. (C) 2001 Elsevier Science B.V. All rights reserved.

Complementary and layered expression of Ephs and Ephrins in developing mouse inner ear

The distributions of the Eph-class receptors EphA4 and EphB 1, and their ligands ephrin-A2, ephrin-B1, and ephrin-B2, were analysed by immunostaining in the mouse inner ear. Complementary patterns of EphA4 and its potential ligand ephrin-A2 were found, with ephrin-A2 in many of the structures lining the cochlear duct and within the cochlear nerve cells, and EphA4 in the deeper structures underlying the cochlear duct and in the cells lining the nerve pathway. EphB1 and its potential ligands ephrin-B1 and ephrin-B2 showed a segregated layered expression in the lateral wall of the cochlear duct (the external sulcus), which together with EphA4 expressed in the area, form a four-layered structure with an alternating pattern of receptors and ligands in the different layers. This arrangement gives the potential for different bidirectional Eph-mediated interactions between each of the layers. The results suggest that the Eph system in the cochlea may have a role in maintaining cell segregation during phases of cochlear development. (C) 2002 Wiley-Liss, Inc.

Expression of ephs and ephrins in developing mouse inner ear

Levels of expression of mRNAs encoding the different Ephs and ephrins were measured by semi-quantitative reverse-transcription polymerase chain reaction in developing mouse whole inner ears, and in dissected fractions of the neonatal mouse inner ear. Nineteen of the 24 known Ephs and ephrins were surveyed. The results showed that between embryonic age (E) 11.5 days and E12.5, levels increased 10-300 times per unit of tissue. In neonatal mice, the fraction containing combined organ of Corti and spiral ganglion showed relatively strong expression of EphA4, EphB3, ephrin-A3, ephrin-B2 and ephrin-B3. In the lateral wall, EphA4, ephrin-A3 and ephrin-B2 were strongly expressed, while ephrin-A3 was particularly strongly expressed in utricular and saccular sensory epithelia. The results suggest that the Ephs and ephrins are likely to play a part in the differentiation of the structures of the inner ear, and show which Ephs and ephrins are most likely to play important roles in the different structures. (C) 2003 Elsevier Science B.V. All rights reserved.

Free-breathing inner-volume black-blood imaging of the human heart using two-dimensionally selective local excitation at 3 T.

Black-blood fast spin-echo imaging is a powerful technique for the evaluation of cardiac anatomy. To avoid fold-over artifacts, using a sufficiently large field of view in phase-encoding direction is mandatory. The related oversampling affects scanning time and respiratory chest motion artifacts are commonly observed. The excitation of a volume that exclusively includes the heart without its surrounding structures may help to improve scan efficiency and minimize motion artifacts. Therefore, and by building on previously reported inner-volume approach, the combination of a black-blood fast spin-echo sequence with a two-dimensionally selective radiofrequency pulse is proposed for selective "local excitation" small field of view imaging of the heart. This local excitation technique has been developed, implemented, and tested in phantoms and in vivo. With this method, small field of view imaging of a user-specified region in the human thorax is feasible, scanning becomes more time efficient, motion artifacts can be minimized, and additional flexibility in the choice of imaging parameters can be exploited.

Phenolics of the Inner Bark of Silver Birch: Characterization and Intraspecific Variation

This thesis describes work related to the in-depth characterization of the phenolic compounds of silver birch (Betula pendula) inner bark. Phenolic compounds are the most ubiquitous class of plant secondary compounds. The unifying feature of this structurally diverse group is an aromatic ring containing at least one hydroxyl group. Due to the structural diversity, phenolics have various roles in the plant defense against biotic and abiotic stresses. In addition, they can confer several health-promoting properties to humans. Furthermore, the structural diversity of this class of compounds causes challenges for their analysis. The study species in the present work, silver birch, is economically the most important hard wood species in northern Europe. Its inner bark contains a high level of phenolic compounds and it has shown one of the strongest antioxidant activities among 92 Finnish plant materials. The literature review surveys the diversity and organ specific distribution of phenolic compounds in silver birch as well as the proposed ecological functions of phenolic compounds in nature. In addition, the basis for the characterization of phenolics by mass spectrometry (MS), nuclear magnetic resonance spectroscopy (NMR), and circular dichroism spectroscopy (CD) are reviewed. The objective of the experimental work was to extract, purify, characterize, and quantify the inner bark phenolic compounds. Overall 36 compounds were characterized by MS and ultraviolet spectroscopy (UV). 24 compounds were isolated and their structures confirmed by NMR and CD spectroscopy. Five novel natural compounds were identified. Special emphasis was placed on the establishment of a method for the characterization of proanthocyanidins (PAs). Hydrophilic interaction liquid chromatography (HILIC) was utilized because of its high resolution power and predictable elution order of oligomeric and polymeric PAs according to an increasing degree of polymerization. The combination of HILIC and high-resolution MS detection allowed the identification of procyanidin (PC) polymers up to the degree of polymerization of 22. In addition, a series of oligomeric and polymeric PC monoxylosides were observed for the first time in nature. Season and genotype influenced the quantities of the main inner bark phenolics, yet qualitative differences were not observed. However, manual wounding of the inner bark induced the production of ellagitannins (ETs) in the wounded tissues, i.e. callus. Since ETs were not detected in the intact inner bark, this finding may reflect the capacity of silver birch to exploit ellagitannins in its defense.