Thesis (M. Sc.)--Acadia University, 1998. / Includes bibliographical references (leaves 34-39). Also available on the Internet via the World Wide Web.

Thesis (M. Sc.)--Acadia University, 1998. / Includes bibliographical references (leaves 34-39). Also available on the Internet via the World Wide Web.

Thesis (doctoral)--Friedricks-Universität Halle-Wittenberg, 1914. / Includes bibliographical references (p. [54]).

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Bacterial colonisation and biofilm formation onto total hip replacement femoral stems remain a serious complication detrimental to the success of total hip arthroplasty. Current treatment procedures are accompanied by a heavy financial burden and morbidity for the patient while failing to guarantee a successful outcome with no reinfection. In fact, infection rates after revision surgeries are typically higher than those for primary hip arthroplasties. This study investigates conceptual drug delivery channels to be incorporated within cementless femoral stems by applying additive manufacturing as enabler technology. Drug delivery from these features is aimed at both prophylaxis and treatment of infection, with the latter emphasising the concept of creating a reinforceable antimicrobial depot inside the implant. The novelty lies in facilitating the administration of multiple drug dosages from within the implant instead of the once-off implant-based release strategies currently employed. Samples containing internal channels were designed based on analogies to drug delivery studies reporting on the commercial antibiotic loaded bone cement, Palacos R+G loaded with gentamicin. These samples were manufactured by LaserCUSING® from Ti-6Al-4V ELI powder. For prophylactic proof of concept, testing the channels were filled with Palacos R+G and challenged with two clinical isolates of Staphylococcus aureus in a bacterial growth inhibition study. Gentamicin-susceptible S.aureus Xen 36 was prevented from colonising for a minimum of 72 hours, whereas gentamicin resistant S.aureus Xen 31 reached the material within 24 h, signifying the importance of drug selection according to pathogen. Hence, a solution of vancomycin in phosphate buffered saline pH 7.4 was used during in vitro reservoir release testing. Three dosage injections were made into each of six samples during a cumulative incubation period of 100 h. A biocompatible 5,000 Da molecular weight cut off polyethersulfone nanoporous membrane was employed as release rate-controlling device. Released vancomycin was quantified with reversed phase high performance liquid chromatography. The resulting release profile was characterised by means of the Korsmeyer-and-Peppas model for diffusion based drug delivery. Constraint diffusion was identified as the mechanism controlling release, implying interplay between Fickian diffusion and polymer relaxation for effecting vancomycin release from within the reservoir. The concept created in this study provides a basis towards the development of full scale intelligent implants with multiple dose in situ drug delivery capabilities. Implants incorporating this concept could aid in the perpetual struggle against infection by providing a new strategy for delivery of high level antibiotics directly to the site of infection. / AFRIKAANSE OPSOMMING: Kolonisering van bakterieë en die vorming van biofilms op totale heupvervanging femorale stamme bly ʼn ernstige komplikasie tot die sukses van ʼn totale heupvervanging. Huidige behandelingsprosedures gaan gepaard met ʼn swaar finansiële las en infeksies vir die pasiënt sonder versekering van ʼn suksesvolle uitkoms. Die voorkoms van infeksie is tipies hoër vir revisie prosedures as vir primêre heupvervangings. Hierdie studie ondersoek konseptuele dwelmvoorsieningskanale wat in sementvrye femorale stamme geïnkorporeer kan word deur middel van toevoegingsvervaardiging as bemagtigingstegnologie. Dwelmtoediening deur hierdie strukture is gemik op beide voorkoming en behandeling van infeksie met ʼn klem op die konsep van ʼn herlaaibare antimikrobiese depot in die implantaat. Die nuwigheid lê in die fasilitasie van toediening van veelvuldige dwelm dosisse vanaf binne die implantaat in plaas van die huidige eenmalige implantaatgebaseerde toedieningstrategieë. Die ontwerp van monsters wat interne kanale bevat is baseer op vergelykings met literatuur op kommersiële beensement, Palacos R+G, wat met gentamisien belaai is. Hierdie monsters is vervaardig met LaserCUSING® van Ti-6Al-4V ELI poeier. Kanale is gevul met Palacos R+G en uitgedaag met twee kliniese isolate van Staphylococcus aureus in ʼn bakteriële groei inhibisie studie. Gentamisien-sensitiewe S.aureus Xen 36 is verhoed tot kolonisasie vir ʼn minimum van 72 uur, terwyl gentamisien-weerstandige S.aureus Xen 31 die materiaal binne 24 uur bereik het. Vervolgens was ‘n oplossing van vankomisien in fosfaatbuffer soutoplossing pH 7.4 gebruik tydens in vitro vrystellingstoetse. Drie dosisse inspuitings is in elk van ses monsters oor ʼn inkubasietydperk van 100 uur toegedien. ʼn Biokompatibiele 5,000 Da molekulêre massa afsnypunt polietersulfoon nanoporeuse membraan is as vrystellingskoers regulerende apparaat gebruik. Vrygestelde vankomisien is gekwantifiseer met omgekeerde fase hoë verrigting vloeistof-chromatografie. Die vrystellingsprofiel is gekarakteriseer met die Korsmeyer-en-Peppas model vir diffusie gebaseerde dwelmtoediening. Beperkte diffusie is geïdentifiseer as die meganisme wat vrystelling beheer. Dit impliseer ʼn tussenspel in Fickiaanse diffusie en polimeer verslapping vir die tot stand bring van vankomisien vrystelling vanaf binne die reservoir. Hierdie konsep van die studie verskaf ʼn basis vir die ontwikkeling van volskaalse intelligente implantate met ʼn veelvuldige in situ dwelmtoedienings vermoë. Implantate met hierdie konseptuele strukture kan steun gee aan die voortdurende stryd teen infeksie deur ʼn nuwe strategie daar te stel vir die toediening van hoë vlak antibiotika direk by die infeksie area.

GUIMARÃES, Anderson Vieira. Mecanismos de fratura em materiais multifásicos. 2014. 75 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2014. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2014-08-29T19:55:57Z No. of bitstreams: 1 2014_dis_avguimaraes.pdf: 11579215 bytes, checksum: f6245c912d49cbd6300b532985e1ab7d (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2014-08-29T20:31:04Z (GMT) No. of bitstreams: 1 2014_dis_avguimaraes.pdf: 11579215 bytes, checksum: f6245c912d49cbd6300b532985e1ab7d (MD5) / Made available in DSpace on 2014-08-29T20:31:04Z (GMT). No. of bitstreams: 1 2014_dis_avguimaraes.pdf: 11579215 bytes, checksum: f6245c912d49cbd6300b532985e1ab7d (MD5) Previous issue date: 2014 / The understanding about the fractures processes in materials has a big importance for physics and civil construction industries. Through the fractures processes, we can better understand the materials’ elastics properties as its macroscopic Young module, rupture tension and rigidity module. We can define the fractures processes as those which divide a system into two or more parts, destroying the global connection of the elements that constitute it. In this context, in the first chapter, we can find a mathematical description of continuum mechanics equations. The second chapter discusses the model of Discrete Element(DEM), which is a numerical method capable of describing the mechanical behavior of granular materials. In the third chapter, we built the computational model for studying the mechanicals properties of three types of samples, crystalline, amorphous and multiphase. The computational model showed itself quite interesting and presented results which we can consider satisfactory. / O entendimento sobre os processos de fraturas em materiais é de grande importância para a física e indústrias da construção civil. Através dos processos de fraturas podemos compreender melhor as propriedades elásticas dos materiais, como seu módulo de Young macroscópico, tensão de ruptura e módulo de rigidez. Podemos definir os processos de fraturas como sendo aqueles que dividem um sistema em duas ou mais partes, destruindo a conexão global dos elementos que o constituem. Nesse contexto, no primeiro capítulo é feito uma descrição matemática das equações da mecânica do contínuo, no segundo capítulo aborda-se o modelo de elementos discretos (DEM) que é um método numérico capaz de descrever o comportamento mecânico de materiais granulados. No terceiro capítulo, construímos o modelo computacional para estudar, as propriedades mecânicas de 3 tipos de amostras, cristalina, amorfa e multifásica. O modelo computacional utilizado se mostrou bastante interessante e apresentou resultados que podemos considerar como sendo satisfatórios.

Numerical simulations of Mach shock reflections have shown that the Mach stem can bifurcate as a result of the slip line jetting forward. Numerical simulations were conducted in this study which determined that these bifurcations occur when the Mach number is high, the ramp angle is high, and specific heat ratio is low. It was clarified that the bifurcation is a result of a sufficiently large velocity difference across the slip line which drives the jet. This bifurcation phenomenon has also been observed after triple point collisions in detonation simulations. A triple point reflection was modelled as an inert shock reflecting off a wedge, and the accuracy of the model at early times after reflection indicates that bifurcations in detonations are a result of the shock reflection process. Further investigations revealed that bifurcations likely contribute to the irregular structure observed in certain detonations.

No description available.

O entendimento sobre os processos de fraturas em materiais à de grande importÃncia para a fÃsica e indÃstrias da construÃÃo civil. AtravÃs dos processos de fraturas podemos compreender melhor as propriedades elÃsticas dos materiais, como seu mÃdulo de Young macroscÃpico, tensÃo de ruptura e mÃdulo de rigidez. Podemos definir os processos de fraturas como sendo aqueles que dividem um sistema em duas ou mais partes, destruindo a conexÃo global dos elementos que o constituem. Nesse contexto, no primeiro capÃtulo à feito uma descriÃÃo matemÃtica das equaÃÃes da mecÃnica do contÃnuo, no segundo capÃtulo aborda-se o modelo de elementos discretos (DEM) que à um mÃtodo numÃrico capaz de descrever o comportamento mecÃnico de materiais granulados. No terceiro capÃtulo, construÃmos o modelo computacional para estudar, as propriedades mecÃnicas de 3 tipos de amostras, cristalina, amorfa e multifÃsica. O modelo computacional utilizado se mostrou bastante interessante e apresentou resultados que podemos considerar como sendo satisfatÃrios. / O entendimento sobre os processos de fraturas em materiais à de grande importÃncia para a fÃsica e indÃstrias da construÃÃo civil. AtravÃs dos processos de fraturas podemos compreender melhor as propriedades elÃsticas dos materiais, como seu mÃdulo de Young macroscÃpico, tensÃo de ruptura e mÃdulo de rigidez. Podemos definir os processos de fraturas como sendo aqueles que dividem um sistema em duas ou mais partes, destruindo a conexÃo global dos elementos que o constituem. Nesse contexto, no primeiro capÃtulo à feito uma descriÃÃo matemÃtica das equaÃÃes da mecÃnica do contÃnuo, no segundo capÃtulo aborda-se o modelo de elementos discretos (DEM) que à um mÃtodo numÃrico capaz de descrever o comportamento mecÃnico de materiais granulados. No terceiro capÃtulo, construÃmos o modelo computacional para estudar, as propriedades mecÃnicas de 3 tipos de amostras, cristalina, amorfa e multifÃsica. O modelo computacional utilizado se mostrou bastante interessante e apresentou resultados que podemos considerar como sendo satisfatÃrios. / The understanding about the fractures processes in materials has a big importance for physics and civil construction industries. Through the fractures processes, we can better understand the materialsâ elastics properties as its macroscopic Young module, rupture tension and rigidity module. We can define the fractures processes as those which divide a system into two or more parts, destroying the global connection of the elements that constitute it. In this context, in the first chapter, we can find a mathematical description of continuum mechanics equations. The second chapter discusses the model of Discrete Element(DEM), which is a numerical method capable of describing the mechanical behavior of granular materials. In the third chapter, we built the computational model for studying the mechanicals properties of three types of samples, crystalline, amorphous and multiphase. The computational model showed itself quite interesting and presented results which we can consider satisfactory. / The understanding about the fractures processes in materials has a big importance for physics and civil construction industries. Through the fractures processes, we can better understand the materialsâ elastics properties as its macroscopic Young module, rupture tension and rigidity module. We can define the fractures processes as those which divide a system into two or more parts, destroying the global connection of the elements that constitute it. In this context, in the first chapter, we can find a mathematical description of continuum mechanics equations. The second chapter discusses the model of Discrete Element(DEM), which is a numerical method capable of describing the mechanical behavior of granular materials. In the third chapter, we built the computational model for studying the mechanicals properties of three types of samples, crystalline, amorphous and multiphase. The computational model showed itself quite interesting and presented results which we can consider satisfactory.

Diversos estudos de anatomia vegetal abordaram as variações cambiais frequentemente presentes nos caules de lianas de Sapindaceae, mas trabalhos que se baseiam na análise das raízes ainda são pouco frequentes na literatura. Por essa razão, a presente dissertação procura atender a dois objetivos, assim distribuídos. No primeiro capítulo, foi realizada uma análise comparada macroscópica de raízes e caules de 14 espécies lianescentes de cinco gêneros de Sapindaceae para verificar se os dois órgãos apresentam os mesmos tipos de variações cambiais e se a anatomia do xilema secundário é semelhante. No segundo capítulo, analisaram-se detalhadamente, em termos macro e microscópicos, as raízes da espécie Serjania caracasana para observar anatomicamente a configuração do xilema e floema secundários e as variações cambiais, além de verificar se existem conexões entre os cilindros vasculares periféricos neoformados e o cilindro central. Os resultados, em síntese, evidenciaram que: I. O principal tipo de variação cambial caulinar está ausente nas raízes; II. O xilema e o floema secundário das raízes amostradas são macro e microscopicamente similares aos dos caules; III. Xilema interrompido por cunhas de floema e neoformações de cilindros vasculares periféricos foram observados em raízes e caules em estágio avançado de desenvolvimento; IV. Conexões vasculares entre os cilindros neoformados e o cilindro vascular original aparecem em diversos pontos das raízes de Serjania caracasana. / A number of studies in plant anatomy have explored the cambial variants present in the stems of Sapindaceae lianas, while works based on root analysis are still meagre in the literature. Therefore, the present dissertation aims to fulfil two objectives, distributed as follow. In the first chapter, a macroscopic comparative analysis of stems and roots of 14 lianescent species from five genera of Sapindaceae was carried to check whether the two organs presented the same types of cambial variants and whether the secondary xylem anatomy was similar. In the second chapter, roots of Serjania caracasana are analysed in detail under macro and microscopic perspectives, in order to anatomically explore the secondary xylem and phloem configuration and the cambial variants, in addition to verify whether there are connections between the neoformed peripheral vascular cylinders and the central vascular cylinder. The results, in synthesis, evidence that: I. The main type of cambial variant present in the stem is absent in the roots; II. The secondary xylem and phloem of the roots are macro and microscopically similar to those of the stem; III. Xylem furrowed by phloem wedges and neoformations of peripheral vascular cylinders was encountered in roots and stems in mature stages of development; IV. Vascular connections between the neoformed vascular cylinders and the central vascular cylinder appear in many parts of the roots of Serjania caracasana.

Lianas possuem uma arquitetura anatômica altamente especializada em seus caules, com características que lhes permitem uma condutividade e mobilidade eficientes. O conjunto dessas características é denominado de “síndrome vascular lianescente”, e compõe-se de variações cambiais (formação de tecidos secundários de forma não-usual), dimorfismo de vasos (coocorrência de vasos de grande calibre e vasos de menor calibre, muitas vezes associados), poucas fibras ou fibras de paredes delgadas, presença de raios altos e largos, e maior quantidade de parênquima (esporadicamente não lignificado, tanto axial quanto radial), quando comparadas com as de espécies autossuportantes relacionadas. Em Bignoniaceae, a maior parte das lianas estão compreendidas na tribo Bignonieae, um grande clado neotropical, morfologicamente diverso, onde a variação cambial do tipo “xilema interrompido por cunhas de floema” representa uma sinapomorfia do grupo. A anatomia caulinar de lianas é bastante conhecida, entretanto dados sobre a anatomia de raízes são raros. Nas raízes de algumas espécies de Bignonieae, sabe-se da presença de variações cambiais, mas sem maiores informações acerca de outros atributos da estrutura secundária. Desse modo, essa dissertação tem como objetivo elucidar algumas questões, dividindo as análises em duas partes. No primeiro capítulo, visa-se verificar a presença de variações cambiais em raízes e caules, e possíveis atributos relacionados à síndrome vascular lianescente nas raízes. No segundo capítulo analisa-se, anatomicamente, as configurações do xilema secundário de raízes e caules, à fim de observar possíveis diferenças entre os órgãos. Os resultados obtidos são, em síntese, os que seguem: (i) raízes apresentam variação cambial semelhante à dos caules, mas as cunhas de floema iniciais se formam intercaladas e em mesmo número que os polos de protoxilema; (ii) em Amphilophium, as cunhas de floema inclusas, características do gênero, são incluídas no floema secundário, além do xilema; (iii) presença de neoformações vasculares em Amphilophium, formadas pela porção não condutora do floema secundário, ampliando a área condutora; (iv) presença de dimorfismo de vasos e raios altos e largos, além da variação cambial, como características da síndrome vascular lianescente, nas raízes das espécies analisadas, semelhantes aos seus caules; (v) as características qualitativas do xilema são semelhantes entre raízes e caules, assim como as quantitativas, estatisticamente. Estudos são necessários no campo do controle gênico e hormonal, visando entender porque a síndrome lianescente ocorre em órgãos submetidos a condições de crescimento tão diferentes / Lianas have stems with a very specialized anatomical architecture, with attributes that allows efficient conductivity and flexibility. Among the suite of features, collectively named “lianescent vascular syndrome”, we can quote the presence of cambial variants (which are unusual patterns of secondary growth), vessel dimorphism (presence of wide and narrow vessel co-occurring, sometimes associated), fewer fibres or thin-walled fibres, tall and large rays, and abundant parenchyma (occasionally non-lignified, both on axial and radial axis) when compared with related self-supporting species. Most of lianas in Bignoniaceae are comprised in the tribe Bignonieae, a large and orphologically diverse neotropical clade, possessing the cambial variant “furrowed xylem” as synapomorphy. The stem anatomy of Bignonieae lianas is well known, but data about root anatomy are scarce. It is known that cambial variants occur in roots of some Bignonieae, but there is no information about other features of the secondary structure. Thus, the aim of this study is to elucidate some questions, dividing the analysis in two parts. In the first chapter, we intent to verify the presence of cambial variants in roots and stems, and possible attributes related to vascular lianescent syndrome in roots. In the second chapter we analyze the anatomical settings of secondary xylem in roots and stems, in order to verify possible differences between them. The key results obtained are here synthetized: (i) roots have cambial variants similar to stems, but the phloem wedges form interspersed and in same number as the protoxylem poles; (ii) in Amphilophium the included phloem wedges, a characteristic of the genus, are also included in secondary phloem, besides the xylem; (iii) presence of vascular neoformations in Amphilophium, formed by cells in nonconducting portion of the phloem, increasing the conductive area; (iv) presence of vessel dimorphism and tall and large rays, plus cambial variant, characteristic of vascular lianescent syndrome in the roots of the analyzed species, similar to stems; (v) the qualitative features of the xylem are similar between roots and stems, as are statistically similar the quantitative features. We believe that more studies are necessary in the genetic and hormonal field, aiming to understand why the lianescent syndrome occurs in organs subjected to different growth conditions