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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

CAF-1 p150 and Ki-67 Regulate Nuclear Structure Throughout the Human Cell Cycle

Matheson, Timothy D. 09 January 2017 (has links)
The three-dimensional organization of the human genome is non-random in interphase cells. Heterochromatin is highly clustered at the nuclear periphery, adjacent to nucleoli, and near centromeres. These localizations are reshuffled during mitosis when the chromosomes are condensed, nucleoli disassembled, and the nuclear envelope broken down. After cytokinesis, heterochromatin is re-localized to the domains described above. However, the mechanisms by which this localization is coordinated are not well understood. This dissertation will present evidence showing that both CAF-1 p150 and Ki-67 regulate nuclear structure throughout the human cell cycle. Chromatin Assembly Factor 1 (CAF-1) is a highly conserved three-subunit protein complex which deposits histones (H3/H4)2 heterotetramers onto replicating DNA during S-phase of the cell cycle. The N-terminal domain of the largest subunit of CAF-1 (p150N) is dispensable for histone deposition, and instead regulates the localization of specific loci (Nucleolar-Associated Domains, or “NADs”) and several proteins to the nucleolus during interphase. One of the proteins regulated by p150N is Ki-67, a protein widely used as a clinical marker of cellular proliferation. Depletion of Ki-67 decreases the association of NADs to the nucleolus in a manner similar to that of p150. Ki-67 is also a fundamental component of the perichromosomal layer (PCL), a sheath of proteins that surrounds all condensed chromosomes during mitosis. A subset of p150 localizes to the PCL during mitosis, and depletion of p150 disrupts Ki-67 localization to the PCL. This activity was mapped to the Sumoylation Interacting Motif (SIM) within p150N, which is also required for the localization of NADs and Ki-67 to the nucleolus during interphase. Together, these studies indicate that p150N coordinates the three-dimensional arrangement of both interphase and mitotic chromosomes via Ki-67.
112

Fabrication Characterisation and Optimisation of Electrospun Scaffolds for Ligament Tissue Reconstruction. The Development of an Anterior Cruciate Ligament (ACL) Analogue using Electrospun PCL, PVA Hydrogel and Polyester Sutures

Agbabiaka, Oluwadamilola A. January 2022 (has links)
Year 2019, football, rugby, netball and skiing had most occurring ACL injuries, listed by United Kingdom National Ligament Report (NLR). The standard procedure treatment of complete laceration of the ACL, is performed by tissue autograft implantation designed from a patellar tendon, for replacement of damaged tissue using orthopaedic surgery. The aim of this thesis is to design and fabricate an ACL graft, attempting to mimic the natural ACL, for the purpose of tissue reconstruction. The desired graft analogues exhibited properties imitating native connective tissue, reducing pain through drug delivery with great biocompatibility and enhance suture mechanical strength. Various biomaterials were implemented into this study, utilising strategies; polymer solution fabrication, electrospinning, hydrogel synthesis, mechanical braiding and graft assembly to fabricate an ACL graft. The polymeric material poly (E- caprolactone) (PCL) was researched, utilising its ability to fabricate scaffolds. Results showed, three analogue ACL grafts (Braided PCL-BP, Braided PCL + Hydrogel-BPH & Braided PCL + Sutures-BPS) created utilising the properties of braiding, hydrogels and sutures, ultimately improving the versatility of electrospinning for tissue engineering and reconstruction. Graft analogues were tested and compared against patellar tendons producing similar tensile properties. Poly vinyl alcohol (PVA) hydrogels successfully held ibuprofen, revealing drug delivery characteristics, polyester threads improved mechanical properties of electrospun grafts and dry degradation showed that PCL did not lose significant mass over two months. Conclusion, tensile strength of patella tendon was 395x, 790x & 56x of analogue grafts (BP, BPH & BPS) respectively, having potential for improvement of tensile parameters for ligament reconstruction.
113

Synthesis and Protein Adsorption Studies of Pegylated-Polyester Nanoparticles with Different Peg Architectures

Montenegro-Galindo, Gladys Rocio January 2013 (has links)
No description available.
114

Green Polymer Chemistry: The Role of Candida Antarctica Lipase B in Polymer Functionalization

Castano Gil, Yenni Marcela 16 May 2014 (has links)
No description available.
115

Desarrollo y optimización de formulaciones industriales basadas en poli(3-hidroxibutirato) (PHB) mediante sistemas de mezclado y plastificación

García García, Daniel 13 June 2019 (has links)
Tesis por compendio / "Desarrollo y optimización de formulaciones industriales basadas en poli(3-hidroxibutirato) (PHB) mediante sistemas de mezclado y plastificación" El principal objetivo de la presente tesis ha sido el desarrollo y caracterización de diferentes formulaciones a partir de poli(3-hidroxibutirato) (PHB) con el fin de mejorar sus propiedades. El PHB es un polímero sintetizado mediante fermentación bacteriana por diferentes tipos de bacterias, que se caracteriza por ser biodegradable, biocompatible y por presentar unas propiedades mecánicas que lo hacen un polímero interesante como sustituto de los polímeros de uso común obtenidos a partir del petróleo. Sin embargo, a día de hoy, el PHB presenta una serie de inconvenientes que hacen que no sea competitivo con los polímeros de uso común y, por tanto, dificultan su introducción a nivel industrial. Entre dichos inconvenientes se encuentra su elevado coste, su elevada fragilidad debida a su alta cristalinidad y su estrecha ventana de procesado, ya que su degradación térmica se inicia a temperaturas cercanas a la de su fusión. Por ello, en la presente tesis se han llevado a cabo diferentes tecnologías de modificación del PHB, todas ellas encaminadas a reducir sus inconvenientes con el objetivo de mejorar su funcionalidad y ampliar su uso a nivel industrial. Una de dichas estrategias de mejora ha consistido en la plastificación del polímero biodegradable mediante el empleo de plastificantes derivados de aceites vegetales, como son el aceite de linaza epoxidado (ELO), el aceite de soja epoxidado (ESBO), el aceite de linaza maleinizado (MLO) y los ésteres de ácidos grasos epoxidados (EFAE). La segunda de las estrategias empleadas ha sido el desarrollo de formulaciones mediante la mezcla física o "blending" del PHB con otro polímero biodegradable como es la poli(e-caprolactona) (PCL), así como la mejora de la miscibilidad entre ambos polímeros mediante el empleo de un agente compatibilizante, el peróxido de dicumilo (DCP). La última de las estrategias seguidas ha consistido en la incorporación de pequeñas cantidades de nanocargas en la mezcla de PHB/PCL sin compatibilizar y compatibilizada con DCP. Concretamente, se ha estudiado el efecto de la incorporación de nanotubos de haloisita sin tratar y tratados superficialmente con silano (3-glicidoxipropiltrimetoxisilano) y con ácido cafeico en la mezcla de PHB/PCL compatibilizada con DCP. Además, también se ha analizado el efecto de diferentes cantidades de nanocristales de celulosa obtenidos y optimizados a partir de un residuo forestal, como son las piñas de los pinos, en la mezcla de PHB/PCL sin compatibilizar. De forma general, la presente tesis muestra diferentes alternativas para la mejora de las propiedades del PHB. Estas alternativas permiten obtener formulaciones más económicas y con propiedades mejoradas, aumentando así su competitividad a nivel industrial. Además, dichas modificaciones amplían el rango de aplicaciones del polímero biodegradable en sectores como el del envase y el embalaje o el sector médico. / "Development and optimization of industrial formulations based on poly(3-hydroxybutyrate) (PHB) by blending and plasticization" The main aim of the present doctoral thesis is the development and characterization of several formulations from poly(3-hydroxybutyrate) (PHB) with the main purpose of improving its properties. PHB is synthesized from bacterial fermentation by several bacteria. It is characterized by being biodegradable, biocompatible and it also shows interesting mechanical properties that make it an interesting alternative to commodity plastics derived from petroleum. Nevertheless, up today, PHB still shows some drawbacks that are responsible for its low competitiveness versus commodity plastics thus restricting its industrial applications. Among these drawbacks, it is worthy to note its high cost, its high brittleness due to high crystallinity and its extremely narrow processing window. In fact, thermal degradation starts at a temperature near the end of the melt process. For these reasons, several technologies to modify PHB have been addressed in this doctoral thesis, with the main aim of overcoming the above-mentioned drawbacks and, hence, improve its functionality and potential industrial applications. The first strategy has consisted on plasticization of the biodegradable polymer by using several vegetable oil-derived plasticizers such as epoxidized linseed oil (ELO), epoxidized soybean oil (ESBO), maleinized linseed oil (MLO) and epoxidized fatty acid esters (EFAE). The second strategy has been the development of industrial formulations by physical blending PHB with other biodegradable polymer, i.e., poly(e-caprolactone) (PCL), as well as the improvement of the miscibility between these two polymers by reactive extrusion with dicumyl peroxide (DCP) which produces compatibilization. The last strategy has consisted on the addition of small amounts of nanofillers into the PHB/PCL blend both non-compatibilized and compatibilized with DCP. In particular, the effect of the addition of halloysite nanotubes (HNTs), without treatment and with a silane (3-glycidoxypropyltrimethoxysilane) and caffeic acid surface treatment, to the PHB/PCL blend compatibilized with DCP has been studied. In addition, the effect of different cellulose nanocrystals (CNCs) obtained and optimized from forestry wastes, i.e., pine cones, on the PHB/PCL blend has been studied. As a general conclusion, this doctoral thesis shows different approaches to improve the overall properties of PHB. These approaches allow to obtain cost-effective formulations with improved properties, thus increasing their competitiveness at industrial scale. These formulations broadens the potential use of PHB in sectors such as packing or medical. / "Desenvolupament i optimització de formulacions industrials derivades de poli(3-hidroxibutirat) (PHB) mitjançant sistemes de mescla i plastificació" El principal objectiu de la present tesi ha sigut el desenvolupament i caracterització de diferents formulacions a partir de poli(3-hidroxibutirat) (PHB) amb la finalitat de millorar les seues propietats. El PHB és un polímer sintetitzat mitjançant fermentació bacteriana per diferents bacteris, que es caracteritza per ser biodegradable, biocompatible i per presentar unes propietats mecàniques que el fan molt atractiu com a substitut dels anomenats "plàstics d'ús comú" obtinguts del petroli. Malgrat això, a dia de hui, el PHB presenta una sèrie d'inconvenients que fan que no siga competitiu amb aquests "plàstics d'ús comú" i, per tant, dificulten la seua introducció a nivell industrial. Entre aquests inconvenients destaca el seu elevat cost, la seua elevada fragilitat deguda a una elevada cristal·linitat i una estreta finestra de processat, ja que la seua degradació tèrmica comença a temperatures molt properes a la de fusió. És per això, que en aquesta tesi s'han dut a terme diferents tecnologies de modificació de PHB, totes elles encaminades a reduir els seus inconvenients amb l'objectiu de millorar la seua funcionalitat i ampliar el seu ús a nivell industrial. Una de les esmentades estratègies de millora ha consistit en la plastificació del polímer biodegradable mitjançant la utilització de plastificants derivats d'olis vegetals, com són l'oli de lli epoxidat (ELO), l'oli de soja epoxidat (ESBO), l'oli de lli maleinitzat (MLO) i els ésters d'àcids grassos epoxidats (EFAE). La segona de les estratègies empleades ha sigut el desenvolupament de formulacions mitjançant la mescla física o "blending" del PHB amb altre polímer biodegradable com és la poli(e-caprolactona) (PCL), així com la millora de la miscibilitat entre ambdós polímers mitjançant la utilització d'un agent compatibilitzant, el peròxid de dicumil (DCP). L'última de les estratègies seguides ha consistit en la incorporació de petites quantitats de nanocàrregues en la mescla de PHB/PCL sense compatibilitzar i compatibilitzada amb DCP. En particular, s'ha estudiat l'efecte de la incorporació de nanotubs d'hal·loysita sense tractar i tractats superficialment amb un silà (3-glicidoxipropiltrimetoxisilà) i amb àcid cafeic a la mescla de PHB/PCL compatibilitzada amb DCP. A més a més, també s'ha considerat l'efecte de diferents quantitats de nanocristalls de cel·lulosa obtinguts i optimitzats a partir d'un residu forestal, com ara les pinyes dels pins, en la mescla de PHB/PCL sense compatibilitzar. De forma general, la present tesi mostra diferents alternatives per a la millora de les propietats del PHB. Aquestes alternatives permeten obtenir formulacions més econòmiques i amb propietats millorades, augmentant així la seua competitivitat a nivell industrial. A més a més, les esmentades modificacions amplien el rang d'aplicacions del polímer biodegradable en sectors com ara l'envàs i embalatge o bé, el sector mèdic. / García García, D. (2018). Desarrollo y optimización de formulaciones industriales basadas en poli(3-hidroxibutirato) (PHB) mediante sistemas de mezclado y plastificación [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/105868 / Compendio
116

Psykometrisk prövning av PG-13; ett självskattningsinstrument för ihållande sorg

Alexandersson, Pelle January 2010 (has links)
Frågan om ”normal” respektive ”patologisk” sorg har under en lång tid varit ett omdiskuterat ämne inom psykologin och psykiatrin. En grupp forskare har tagit fram kriterier på ett syndrom som fått benämningen ihållande sorg (”prolonged grief”). Studier har visat på att ihållande sorg är ett distinkt syndrom separat från depression, posttraumatisk stressyndrom och generaliserat ångestsyndrom. Ihållande sorg föreslås ingå som en diagnos i de kommande versionerna av de diagnostiska manualerna DSM och ICD. Syftet med denna studie var att översätta självskattningsinstrumentet Prolonged Grief Disorder (PG-13) till svenska, och undersöka dess reliabilitet och validitet genom bland annat en explorativ och konfirmatorisk faktoranalys. Studien genomfördes på ett annonsrekryterat heterogent sample (n=162 varav 90 % var kvinnor) vad gäller typ av dödsfall och relation till den avlidne. Respondenterna besvarade en webb- eller pappersenkät som bestod av 75 items. PG-13 bedöms ha en hög reliabilitet, god begrepps- och samtidig validitet samt en måttlig diskriminativ validitet.
117

Μελέτη μιγμάτων αλειφατικών/αρωματικών πολυεστέρων

Μοσχοπούλου, Ελένη 08 July 2011 (has links)
Αντικείμενο της παρούσας διατριβής αποτέλεσε η μελέτη μιγμάτων αλειφατικών/αρωματικών πολυεστέρων. Αρχικά υπήρχε η πρόθεση να επικεντρωθούμε στη μελέτη της βιοαποικοδόμησης μίγματος ενός αλειφατικού και ενός αρωματικού πολυεστέρα. Για τη διερεύνηση όμως της αναμειξιμότητάς τους εστιάσαμε στην έμμεση μελέτη του μοριακού προσανατολισμού μονοαξονικά εφελκυσμένων μιγμάτων αλειφατικών/αρωματικών πολυεστέρων, με τη χρήση πολωμένων φασμάτων δόνησης. Πιο συγκεκριμένα, εξετάστηκε η σύγχρονη παρουσία σ’ ένα μόνο πολωμένο φάσμα Raman της μη-συμβατικής συμπεριφοράς της δόνησης τάσης της χαρακτηριστικής ομάδας του καρβονυλίου (C=O) των αρωματικών πολυεστέρων με την αντίστοιχη συμβατική συμπεριφορά της ίδιας ομάδας των αλειφατικών πολυεστέρων. Μετά από πολλές προσπάθειες διαφόρων παρεμφερών μιγμάτων στα οποία παρουσιάστηκαν διάφορα προβλήματα, κυρίως αναμειξιμότητας, καταλήξαμε στο μίγμα του βιοαποικοδομήσιμου αλειφατικού πολυεστέρα L-PLA με τον αρωματικό πολυεστέρα PBT. Παρασκευάστηκαν φιλμ των ομοπολυμερών L-PLA και PBT καθώς και του μίγματος L-PLA/PBT, με ανάμιξη των συστατικών σε τήγμα και στη συνέχεια μορφοποίησή τους σε υδραυλική θερμοπρέσα. Για τον προσδιορισμό των θερμικών ιδιοτήτων των υλικών χρησιμοποιήθηκε η τεχνική Διαφορικής Θερμιδομετρίας Σάρωσης (DSC). Δοκίμια των ομοπολυμερών και του μίγματος εφελκύστηκαν μονοαξονικά σε θερμοκρασίες μεγαλύτερες από τη μετάβαση υάλου τους και ο προσανατολισμός τους εκτιμήθηκε με τη χρήση πολωμένων φασμάτων Raman. Σε κάθε περίπτωση, επειδή παρά τις πολλές προσπάθειες δεν ήταν δυνατό κυρίως και πάλι λόγω προβλημάτων αναμειξιμότητας να συνεχιστεί μια τέτοια μελέτη και στο επίπεδο της βιοαποικοδόμησης ενός αλειφατικού και ενός αρωματικού πολυεστέρα, αποφασίσαμε να συνεχίσουμε με ένα αναμείξιμο σε κάθε αναλογία μίγμα, ενός βιοαποικοδομήσιμου και ενός μη-αποικοδομίσιμου πολυμερούς. Το μίγμα αυτό των πολυμερών ήταν το PCL/PVC με το οποίο και συνεχίστηκε και ολοκληρώθηκε η παρούσα διατριβή εξειδίκευσης. Το ενδιαφέρον επικεντρώθηκε στη μελέτη μιγμάτων PCL/PVC διαφόρων συστάσεων, δύο πολυμερών τα οποία είναι αναμίξιμα σε όλο το εύρος των αναλογιών τους. Το ομοπολυμερές του αλειφατικού πολυεστέρα PCL και τα μίγματα που προέκυψαν μελετήθηκαν ως προς τις θερμικές τους ιδιότητες και χαρακτηρίστηκαν φασματικά με Raman. Επιπλέον, επιχειρήθηκε η μελέτη της βιοαποικοδόμησης τόσο της PCL όσο και των μιγμάτων της με PVC, μετά από εμβάπτιση σε φυσιολογικό ορό για χρονικό διάστημα άνω των 3 μηνών. Για τον προσδιορισμό των θερμικών ιδιοτήτων των μιγμάτων PCL/PVC και του ομοπολυμερούς PCL χρησιμοποιήθηκε η τεχνική DSC, στη συνέχεια χαρακτηρίστηκαν με τη δονητική φασματοσκοπία Raman ενώ ακολούθησαν πειράματα Χρωματογραφίας Διαπιδύσεως μέσω Πηκτής (GPC) και Δυναμικής Σκέδασης Φωτός (DLS) ώστε να προσδιοριστεί η βιοαποικοδόμηση των υλικών. Η βιοποικοδόμηση των PCL/PVC και κατ’ επέκταση της PCL μελετήθηκε υπό διαφορετικές συνθήκες (θερμοκρασίας, χρόνου, συγκέντρωσης) και σε διαφορετικό βαθμό. / The aim of this dissertation was the study of aliphatic/aromatic copolyesters. At the beginning, the main purpose was to investigate the biodegradation behavior of an aliphatic/aromatic polyester blend. In order to examine the miscibility of the two polymers comprising the blend we have studied the molecular orientation of melt blends utilizing polarized vibrational spectroscopy. After plenty of essays on resembling blends and due to the problems that we have faced (mainly miscibility problems) we decided to study the polymer blend of the biodegradable aliphatic polyester Poly(L-lactic acid) (L-PLA) and the aromatic polyester Poly(butylene terephthalate) (PBT). In particular, the interest centered to the peculiar and unexpected behavior of the C=O stretching carbonyl Raman band of the aromatic polyesters (in case PBT) comparing to the corresponding conventional behavior of the aliphatic polyesters, (in case L-PLA). L-PLA/PBT blends were prepared through reaction extrusion (melt mixing). Films prepared by melt pressing have been uniaxially hot drawn. Polarized laser Raman spectroscopy has been used to estimate the molecular orientation of drawn films of L-PLA and PBT homopolymers and L-PLA/PBT polymer blends. The crystallization behavior of the samples was investigated by using a differential scanning calorimeter (DSC). Finally, the polymers L-PLA and PBT have found to be partially miscible so we took the decision of studying another totally miscible blend consisted of PCL and PVC, a mixture of an aliphatic biodegradable polyester and a non-biodegradable thermoplastic polymer. Blends of PCL and PVC are under development with various potential applications in view, including controlled delivery of agrichemicals, and it is important to investigate their biodegradation behavior. The thermal properties of the homopolymer PCL and PVC blends were investigated under nitrogen by using DSC. Samples of the homopolymer PCL and PCL/PVC blends were placed in glass bottles with serum for more than 3 months. Raman Spectroscopy, Gel Permeation Chromatography and Dynamic Light Scattering have been used to estimate the biodegradation of the samples.
118

Estudo do processamento e da degradação térmica do poli (Hidroxibutirato) e suas blenadas com poli (Caprolactona)

Duarte, Márcia Adriana Tomaz 10 March 2004 (has links)
Made available in DSpace on 2016-12-08T17:19:36Z (GMT). No. of bitstreams: 1 Marcia Adriana Tomaz.pdf: 5577367 bytes, checksum: c8f9d4ee034ae6bd90f26bb87ca29b3c (MD5) Previous issue date: 2004-03-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Aiming the development of high-performance biodegradable polymeric materials, the properties and the processing behavior of poly(3-hydroxibutyrate), PHB, and their blends with poly(ε-caprolactone), PCL, have been investigated. Two sample of PHB obtaneid from sugarcane and characterized by infrared spectroscopy and X-ray diffraction, with molecular weights of 2,4 x 105 g.mol 1, PHB(A) and 3,0 x 105 g.mol 1,PHB(B), were used. Differential scanning calorimetry (DSC) showed that the sample were different regarding the crystallinity degree, 49% for the PHB(A) and 60% for the PHB(B), the glass transition temperature (Tg), 2,0oC (A) and 4,4 oC (B), and the melting temperature, 178oC (A) and 171oC (B). The samples have been processed through high-pressure compacting,solid state extrusion, and injection molding. Cylindrical billets of PHB prepared by compaction at 200 MPa showed high shore hardness, 71,3 (±0,9) D, and compression strength, 51,7 (± 1,0) MPa. The solid state processing was carried out by uniaxial compression, at temperature between the Tg and the melting point, through conical dies with extrusion draw ratio of 25 . It has produced extremely fragile materials with very high crystalline degrees (ca. 90%). Specimens of PHB(B) obtaneid by injection molding showed tensile strength, 24.53 (±0,77) MPa, and modulus ,3.82 (± 0,06) GPa, compatible to diverse type of applications. A small decrease on the tensile strength, 21,88 (± 0,40) MPa, and modulus, 2,17 (±0,25) GPa, and a high increase on the elongation at break, 86.7% (±20,0) were noted for PHB(B)/PCL (70/30) blends prepared by injection molding. DSC analyses of this blend showed two Tg´s, at 10,6oC for the PHB matrix, and at 62,9 oC for the PCL domains. The significant decrease on the Tg of PHB in the blend is possibly related to a partial miscibility of PCL in PHB. Thermal degradation studies of PHB were carried out by thermogravimetric methods, showing that the degradations occurs in only one step and that the presence of oxygen does not interfere in the degradation process. / Visando o desenvolvimento de materiais poliméricos biodegradáveis de alta performance estudaram-se as propriedades e o processamento de poli(3-hidroxibutirato), PHB, e de suas blendas com poli(ε-caprolactona), PCL. Foram utilizadas duas amostras de PHB, obtidas a partir de cana de açúcar,com massas molares de 2,4 x 105 g mol-1, PHB(A) e 3,0 x 105 g mol-1, PHB(B), cujas identidades foram confirmadas por espectroscopia na região do infravermelho. A calorimetria diferencial exploratória (DSC) mostrou que as amostras se diferenciam quanto ao grau de cristalinidade, 49% para o PHB(A) e 60% para o PHB(B), e em relação às temperaturas de transição vítrea, que variaram de 2 oC a 4,4oC, e de fusão, de 178 oC a 171 oC. Os materiais foram processados por compactação a alta pressão, extrusão em estado sólido e injeção em molde. O material compactado a 200 MPa apresentou elevada dureza, 71,30 (±0,9) unidades Shore D, e alta resistência à compressão, 51,7 (± 1,0) MPa. Observou-se que o processamento no estado sólido com razão de extrusão de 25 e em temperaturas até 175oC geram materiais extremamente frágeis, sendo que a caracterização por microscopia eletrônica de varredura mostra que o material não estava consolidado. A análise de DSC deste material revelou um alto grau de cristalinidade (93%), o que provavelmente está relacionado com a grande dificuldade de se obter PHB ou suas blendas com PCL por extrusão sólida. Corpos de prova de PHB(B) obtidos por injeção em molde apresentaram valores de resistência à tração, 24,53 (± 0,77) MPa,compatíveis com diversos tipos de aplicações, enquanto que as blendas de PHB(B)/PCL (70/30) injetadas apresentaram módulo de elasticidade igual a 2,17 (± 0,25) GPa e resistência à tração de 21,88 (± 0,40) MPa. A análise de DSC da blenda apresentou duas Tg´s, uma em -10,6 oC, da matriz de PHB, e outra a 62,9 oC, referente aos domínios de PCL. A diminuição acentuada na Tg do PHB(B) pode estar associada a uma provável solubilidade do PCL em PHB. Estudos da degradação térmica do PHB(B) por análise termogravimétrica, mostram que a degradação ocorre em apenas uma etapa e que a presença de oxigênio não interfere na degradação. Na análise da blenda de PHB(B)/PCL (70/30) é possível observar dois estágios de degradação provenientes do PHB(B) e do PCL e uma diminuição nas temperaturas de início de degradação do PCL e do PHB, quando comparadas com as dos materiais não processados.
119

Detekce a vizualizace specifických rysů v mračnu bodů / Detection and Vizualization of Features in a Point Cloud

Kratochvíl, Jiří Jaroslav January 2018 (has links)
The point cloud is an unorganized set of points with 3D coordinates (x, y, z) which represents a real object. These point clouds are acquired by the technology called 3D scanning. This scanning technique can be done by various methods, such as LIDAR (Light Detection And Ranging) or by utilizing recently developed 3D scanners. Point clouds can be therefore used in various applications, such as mechanical or reverse engineering, rapid prototyping, biology, nuclear physics or virtual reality. Therefore in this doctoral Ph.D. thesis, I focus on feature detection and visualization in a point cloud. These features represent parts of the object that can be described by the well--known mathematical model (lines, planes, helices etc.). The points on the sharp edges are especialy problematic for commonly used methods. Therefore, I focus on detection of these problematic points. This doctoral Ph.D. thesis presents a new algorithm for precise detection of these problematic points. Visualization of these points is done by a modified curve fitting algoritm with a new weight function that leads to better results. Each of the proposed methods were tested on real data sets and compared with contemporary published methods.
120

Metody přípravy buněčných transplantátů v kardiologii / Cell transplantation methods in cardiology

Kukhta, Dziyana January 2019 (has links)
Tato diplomová práce se zabývá tkáňovým inženýrstvím, zejména tvorbou homogenní, izotropní a planární vrstvy buněk srdečního svalu pomocí dvou technologii:”scaffold-based” a ”scaffold-free”. Nejprve popsaný histologie srdeční stěny, buňky srdečního svalu a buněčné kultury. Následuje popis tkáňového inženýrství, který zahrnuje technologii “cell sheet” a tkáňové inženýrství na bázi scaffoldů. Na konci teoretické části je popsána aplikace tkáňového inženýrství a buněčná vizualizace. Praktická část věnovaná tvorbě planární buněčné vrstvy z kardiomyocytů a fibroblastů s využitím informací z teoretické části.

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