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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.
341

Nitinol shape memory alloy in flexor tendon repair

Karjalainen, T. (Teemu) 27 November 2012 (has links)
Abstract Early motion is crucial for tendon healing and functional results after flexor tendon repair in the fingers. Motion, however, causes stress in the repair site, which can result in failure of the repair. A flexor tendon repair is made with fine calibre sutures, which sets exceptional requirements for the suture materials used in flexor tendon repair. Nitinol (nickel-titanium alloy) is a shape memory alloy, which can exist in two temperature-dependent forms, soft martensite and stiff austenite. It is possible to fabricate a nitinol wire that is soft and pliable, yet has high tensile strength. It also has excellent biocompatibility. Therefore, it is a potential candidate flexor tendon repair suture material. This study evaluates biomechanical aspects of martensite nitinol wire as a flexor tendon repair suture material. The study hypothesis was that nitinol wire improves the strength of the repairs compared with the repairs made with conventional suture materials. It was found that nitinol core repairs and circumferential repairs performed significantly better when compared with repairs made with commonly used braided polyester and polypropylene of equal calibre. To further optimise the performance of the nitinol wire in tendon surgery, two experimental models were developed to study the suture-tendon interface. The aim was to prevent pull-out of the suture loop so that surgeons could have full advantage of the tensile strength of the nitinol suture. First, it was tested whether it is possible to improve the suture’s ability to grip the tendon tissue by changing the suture type from monofilament to multifilament. Multifilament suture loops reached higher pull-out strength when compared with round monofilament loops when a locking loop was used. Subsequently, the grip of four different previously reported core repair loops was tested. Based on their failure mechanism, two novel loops were developed. The novel loops demonstrated superior ability to grip the tendon. The novel loops can be useful with high tensile strength suture materials and in repairs, which are prone to suture pull-out. / Tiivistelmä Varhainen korjauksen jälkeinen aktiivinen kuntoutus on osoittautunut hyödylliseksi jänteen paranemiselle. Varhainen liike altistaa korjauksen kuormitukselle, joka voi johtaa korjauksen pettämiseen. Korjaukset tehdään ohuilla langoilla. Tämä asettaa erityisiä vaatimuksia jännekorjauksessa käytettävälle ommelainemateriaalille. Nikkeli-titaani (nitinoli) on nk. muistimetalli. Sillä on kaksi lämpötilariippuvaista muotoa: pehmeä martensiitti ja jäykkä austeniitti. Nitinolista voidaan valmistaa ohutta pehmeää ja taipuisaa lankaa, jonka vetolujuus on suuri. Nitinolin siedettävyys jännekudoksessa on todettu hyväksi, minkä vuoksi se on lupaava materiaali käytettäväksi jännekorjauksissa. Tässä tutkimuksessa kokeiltiin martensiittisen nitinolilangan käyttöä jänteen ydinompeleena ja pintaompeleena. Olettamuksena oli, että nitinolilangalla saadaan kestävämpiä korjauksia kuin nykyään käytössä olevilla langoilla. Tulosten mukaan nitinolilangalla tehdyt korjaukset olivat kestävämpiä, kun niitä verrattiin saman paksuiseen punottuun polyesteriin ja polypropyleeniin. Lisäksi kehitimme kaksi mallia, joiden tarkoituksena oli parantaa nitinolilankasilmukan pitoa jännekudoksesta. Tarkoituksena oli löytää keinoja, joilla langan otetta jännekudoksesta voidaan parantaa ja langan hyvät vetolujuusominaisuudet pääsevät oikeuksiinsa. Ensin muutimme langan muotoa perinteisestä yksisäikeisestä pyöreästä monisäikeiseen muotoon. Monisäikeisen langan läpileikkausvoima oli huomattavasti suurempi kuin yksisäikeisen pyöreän langan. Ero oli havaittavissa vain, kun käytettiin lukitsevaa silmukkaa. Tämän jälkeen testasimme neljän perinteisesti käytetyn korjaustekniikan silmukan pitokykyä ja tulosten perusteella kehitimme kaksi uutta silmukkaa. Työssä kehitetyt silmukat pitivät kiinni jänteestä huomattavasti paremmin kuin perinteiset silmukat. Työssä kehitetyillä silmukoilla voidaan optimoida vahvojen ommelainemateriaalien suorituskyky jännekirurgiassa.
342

Investigations into the mechanics of connective tissue

Pritchard, Robyn January 2015 (has links)
This thesis presents work on investigations into the mechanical properties of connective tissue. A model system of hydrogels was used to investigate how volume change through water flow is coupled to relaxation. This was done using digital image correlation (DIC) and a custom built setup. It was found, in hydrogels, that water loss is directly coupled to an increase in tension and water intake is directly coupled to tension relaxation. The experimental setup was tested by investigating the mechanical properties of the well known material polydimethylsiloxane (PDMS) and the novel materials of carbon nanotube (CNT) elastomers, cholesteric liquid crystal elastomers (CLCEs), and 3D polydomain liquid crystal elastomers (3DLCEs). The setup accurately demonstrated the incompressibility of PDMS, even at short time scales, and demonstrated how DIC can map the inhomogeneity of material by locating clusters of CNTs in CNT elastomers by how they deform. Novel results for 3DLCEs were also found, where it was discovered that there is a softening of the bulk modulus at small time scales resulting in a volume increase following deformation, the bulk modulus then recovers and there is over all no volume change. This is in stark contrast to the typical case, where it is the shear modulus that becomes comparable to the bulk modulus, resulting in increased volume. A theoretical investigation was carried out into critical damping in viscoelastic oscillators, where the aim was to apply to the findings to connective tissue. The fractional Maxwell model and zener model where both solved for, where it was found that damping decreases as the material becomes more solid and the peak of critical damping becomes broader. Finally, investigations into how strain relates to the viscoelastic properties of connective tissue were carried out on horse tendon and rat fascia. How relaxation changes was determined through the relaxation constant, where a large constant means it takes the sample longer to relax and it is more solid like. It was found, that in general, the relaxation constant increases quickly with an imposed strain and then either stabilises or increases more slowly. This growth of relaxation constant also occurs during the initial stages of tissue injury, where irreversible deformation occurs.
343

Efeitos agudos e crônicos da combinação dos treinamentos de força e vibração sobre o desempenho neuromuscular e a excitabilidade das vias reflexas / Acute and chronic effects of combined strength and vibration training on neuromuscular performance and excitability of spinal pathways reflexes

Mauro Alexandre Benites Batista 16 April 2010 (has links)
Tem sido sugerido que combinar o treinamento de força (TF) com o treinamento com vibração (TV) pode ser mais vantajoso do que realizar o TF isolado. OBJETIVOS: Foi objetivo deste estudo avaliar os efeitos da combinação do TF com o TV (TF+V) sobre o desenvolvimento de hipertrofia e os desempenhos da força máxima dinâmica de membros inferiores (FMD) e do salto vertical (SV). Investigou-se também se os benefícios proporcionados pelo treinamento são acompanhados por alterações agudas e crônicas na excitabilidade das vias reflexas. METÓDOS: Foram realizados dois experimentos. No primeiro, foram avaliados os efeitos de uma sessão de treinamento sobre o desempenho do SV e excitabilidade das vias reflexas. Doze sujeitos do sexo masculino foram submetidos a quatro condições experimentais. Na condição TF, realizaram cinco séries de 10 repetições do exercício agachamento, com 90% da massa corporal. Nas condições TF+V30 e TF+V50, o TF foi realizado sobre a plataforma vibratória nas freqüências de 30 Hz (2-4 mm) e 50 Hz (4-6 mm), respectivamente. Na condição controle (C), os sujeitos permaneceram em repouso. Antes e depois de todas as condições experimentais, foram mensurados o desempenho do SV, e os reflexos de Hoffmann (H com amplitude de 20% da onda M máxima, H20%) e tendíneo máximo (Tmáx), no músculo sóleo. No segundo experimento, 29 sujeitos do sexo masculino foram divididos aleatoriamente nos grupos TF, TF+V30 e TF+V50. Os três grupos realizaram entre 3-5 séries de 6-12 RM do exercício agachamento, duas vezes por semana, durante dez semanas. Os grupos TF+V30 e TF+V50 fizeram o agachamento sobre a plataforma vibratória nas freqüências de 30 Hz (amplitude de 2-4 mm) e 50 Hz (amplitude de 4-6 mm), respectivamente. Antes e depois do período de treinamento, foram avaliados a área de secção transversa do quadríceps femoral (ASTQ), os desempenhos da FMD e do SV, os reflexos H e T máximos (Hmáx e Tmáx) e a onda M máxima (Mmáx), no músculo sóleo. RESULTADOS: No primeiro experimento, não foram verificadas alterações significantes na amplitude de H20% em nenhuma das condições (p>0,05). Houve diminuições significantes na amplitude das ondas Tmáx, nas condições TF (-7,4%) e TF+V50 (-11,1%), no primeiro minuto, em comparação ao período antes da intervenção (p<0,001). Foram verificadas diminuições significantes na altura do SV após a realização de todas as condições (C= -11,8%, TF= -6,6%, TF+V30= -7,7% e TF+V50= -7,4%) (p<0, 001). Não houve diferenças significantes entre grupos em nenhuma das variáveis (p>0,05). No segundo experimento, após as dez semanas de treinamento, foram verificados aumentos significantes na ASTQ (TF= 9,8%, TF+V30= 11,7%, TF+V50= 12,9%); na FMD (TF= 16,9%, TF+V30= 15,2%, TF+V50= 16,6%) e na altura do SV (TF= 6,0%, TF+V30= 7,2%, TF+V50= 6,0%) para os três grupos (p<0,05). Não houve diferença significante entre grupos em nenhuma das três variáveis. O período de treinamento não causou alterações significantes nas razões Hmáx/Mmáx (TF = +28%, TF+V30 = -16,3%, TF+V50 = -14%) e Tmáx/Mmáx (TF = -30,3%, TF+V30 = -38,2%, TF+V50 = -28,1%) (p>0,05). Contudo, foi verificado efeito principal de tempo significante para a razão Tmáx/Mmáx (-48,9%) (p<0,05). CONCLUSÕES: A realização de uma sessão de treinamento de força causa uma breve redução da atividade dos fusos musculares. Essa redução não é ampliada quando o TF é combinado com vibração. Realizar um período de TF sobre a plataforma de vibração não proporciona qualquer aumento adicional na ASTQ ou nos desempenhos da FMD e do SV, em relação ao que pode ser conseguido através do TF / It has been suggested that the combination of strength and vibration training may be advantageous when compared with strength training alone. OBJECTIVES: The aim of this study was to assess the effects of combined strength training and vibration (ST+V) on lower limb hypertrophy and on maximal dynamic strength (MDS) and vertical jump (VJ) performances. In addition, we investigate if the training-induced adaptations were in agreement to acute and chronic changes on spinal reflex excitability. METHODS: Two experiments were performed. In the first experiment, the effects of a single training session on VJ performance and spinal reflexes excitability were assessed. Twelve young male undertook four experimental conditions. On ST condition, subjects performed five sets with 10 repetitions on squat exercise with load of 90% body mass. On both ST+V30 and ST+V50 conditions, subjects performed the ST on a vibration platform at 30 Hz (2-4 mm) and 50 Hz (4-6 mm), respectively. In C condition, subjects were only assessed. Vertical jumping performance and Hoffman (at 20% of maximal M wave, H20%) and maximal tendon soleus reflexes (Tmáx) were measured before and after all experimental conditions. In the second experiment, twenty nine young male were randomized into three groups. All groups performed 3-5 sets with 6-12 RM on squat exercise, twice a week, for ten weeks. The ST+V30 and ST+V50 groups performed the squat exercise on the vibration platform at 30 Hz (2-4 mm) and 50 Hz (4-6 mm), respectively. Quadriceps cross sectional area (QCSA), MDS and VJ performances, maximal soleus H- and T- reflexes and maximal M wave (Mmáx) were assessed before and after the 10-week training period. RESULTS: in the first experiment, no significant changes were found in H20% amplitude in any experimental condition (p>0,05). Significant decrease on Tmáx amplitude was found after ST+V30 (-7.4%) and ST+V50 (-11.1%) conditions, after the first minute, compared to before intervention assessment. VJ decreased in all experimental conditions (C= -11.8%, ST= -6.6%, ST+V30= -7.7% and ST+V50= -7.4%) (p<0.001). There were no significant changes between groups in any variable measured (p>0.05). In the second experiment, significant increases were found in QCSA (ST= 9.8%, ST+V30= 11.7%, ST+V50= 12.9%); MDS (ST= 16.9%, ST+V30= 15.2%, ST+V50= 16.6%) and VJ height (ST= 6.0%, ST+V30= 7.2%, ST+V50= 6.0%) in all groups (p<0.05). There were no significant changes between groups in any variable measured (p>0.05). The training period did not induce significant changes in Hmáx/ Mmáx (ST = +28%, ST+V30 = -16,3%, ST+V50 = -14%) and Tmáx/ Mmáx ratios (ST = -30,3%, ST+V30 = -38,2%, ST+V50 = -28,1%) (p>0.05). However it was found a significant time effect for Tmáx/ Mmáx ratio (-48.9%) (p<0,05).CONCLUSION: A single strength training session induces a brief impairment on muscle spindle activity. This impairment is not greater if ST is combined with vibration. Performing ST on a vibration platform did not additionally increase QCSA, MDS and VJ performance compared with ST alone
344

Radiell eller fokuserad stötvågsbehandling vid akillestendinopati : En systematisk litteraturöversikt / Radial versus Focused Shockwave Therapy for Achilles Tendinopathy : A Systematic Review

Andersson, Anton January 2021 (has links)
Syftet med denna systematiska litteraturöversikt var att jämföra radiell mot fokuserad stötvågsbehandling samt att undersöka effekten utav stötvågsbehandling för att reducera smärta och återfå fysisk funktion vid Akillestendinopati. Litteraturöversikten har följt checklistan PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis). Inklusionskriterier till litteraturöversikten är utformade efter PICO (population, intervention, control, outcome) och databaser som använts är PubMed, SPORTDiscus, CINAHL, Scopus och Web of Science. Data har analyserats narrativt och tillförlitligheten hos utfallen har bedömts med GRADE.Sju studier inkluderades till litteraturöversikten varav fyra studier som utfört radiell och tre studier som utfört fokuserad stötvågsbehandling som intervention. En signifikant skillnad för smärtreduktion sågs i två av studierna för båda behandlingarna. När radiell stötvågsbehandling användes hade interventionsgrupperna en högre smärtreduktion än kontrollgrupperna och när fokuserad stötvågsbehandling användes hade kontrollgrupperna en högre smärtreduktion än interventionsgrupperna. En signifikant skillnad för återställande utav den fysiska funktionen i ankeln sågs i tre studier för radiell stötvågsbehandling och två studier för fokuserad stötvågsbehandling. Där radiell stötvågsbehandling användes hade interventionsgrupperna en större ökad fysisk funktion än kontrollgrupperna och där fokuserad stötvågsbehandling användes hade kontrollgrupperna en större ökad fysisk funktion än interventionsgrupperna.Radiell stötvågsbehandling verkar kunna fungera för att reducera smärta och öka fysisk funktion vid Akillestendinopati. Tillförlitligheten för utfallen vid fokuserad stötvågsbehandling är för låg för att kunna dra någon slutsats om vilken typ av stötvågsbehandling som är mest effektiv. Ifall det varit känt vilken typ av stötvågsbehandling som ger bäst resultat hade det varit en bra vägledning för vårdpersonal som arbetar med stötvågsbehandling. / The purpose of this review was to compare radial versus focused shock wave therapy and to review shock wave therapies usage to reduce pain and increase physical function for the Achilles tendinopathy.The review has followed PRISMA’s checklist while using PubMed, SPORTDiscus, CINAHL, Scopus and Web of Science databases. Data has been analyzed narratively and the evidence of the outcomes has been assessed.A significant difference in pain reduction was seen within two studies for both interventions. Where radial shock wave therapy was administered the intervention groups had a higher pain reduction than the control group. Where focused shock wave therapy was administered the control group had a higher pain reduction than the intervention group. A significant difference in the restoration of physical function was seen within three studies for radial shock wave therapy and two studies for focused shock wave therapy. Where radial shock wave therapy was administered the intervention groups had a greater increased physical function than the control groups and where focused shock wave treatment was administered the control groups had a greater increased physical function than the intervention groups.Radial shock wave therapy seems to be effective to reduce pain and increase physical function in the Achilles tendinopathy. The evidence of the results for focused shock wave therapy is too low to draw any conclusion, or allow us to compare the two methods. Had the studies allowed for a direct comparison between the two methods, this could have led to a guide for healthcare professionals.
345

Do cells contribute to tendon and ligament biomechanics?

Hammer, Niels, Huster, Daniel, Schmidt, Peter, Fritsch, Sebastian, Wagner, Martin Franz-Xaver, Hädrich, Carsten, Koch, Holger, Boldt, Andreas, Sichting, Freddy January 2014 (has links)
Introduction: Acellular scaffolds are increasingly used for the surgical repair of tendon injury and ligament tears. Despite this increased use, very little data exist directly comparing acellular scaffolds and their native counterparts. Such a comparison would help establish the effectiveness of the acellularization procedure of human tissues. Furthermore, such a comparison would help estimate the influence of cells in ligament and tendon stability and give insight into the effects of acellularization on collagen. Material and Methods: Eighteen human iliotibial tract samples were obtained from nine body donors. Nine samples were acellularized with sodium dodecyl sulphate (SDS), while nine counterparts from the same donors remained in the native condition. The ends of all samples were plastinated to minimize material slippage. Their water content was adjusted to 69%, using the osmotic stress technique to exclude water content-related alterations of the mechanical properties. Uniaxial tensile testing was performed to obtain the elastic modulus, ultimate stress and maximum strain. The effectiveness of the acellularization procedure was histologically verified by means of a DNA assay. Results: The histology samples showed a complete removal of the cells, an extensive, yet incomplete removal of the DNA content and alterations to the extracellular collagen. Tensile properties of the tract samples such as elastic modulus and ultimate stress were unaffected by acellularization with the exception of maximum strain. Discussion: The data indicate that cells influence the mechanical properties of ligaments and tendons in vitro to a negligible extent. Moreover, acellularization with SDS alters material properties to a minor extent, indicating that this method provides a biomechanical match in ligament and tendon reconstruction. However, the given protocol insufficiently removes DNA. This may increase the potential for transplant rejection when acellular tract scaffolds are used in soft tissue repair. Further research will help optimize the SDS-protocol for clinical application.
346

Oberflächenentigen- und Sehnenmarkerexpression equiner multipotenter mesenchymaler Stromazellen

Päbst, Felicitas Miriam Thekla 22 March 2016 (has links)
1. Einleitung Multipotente mesenchymale Stromazellen (MSC) stellen eine interessante Therapieoption in der regenerativen Medizin verschiedener Erkrankungen dar. Aufgrund ihrer Herkunft aus mesodermalem Gewebe ist ihr Einsatz in der Therapie von Sehnenerkrankungen als günstig anzusehen, wo sie bei Pferden bereits erfolgreich verwendet werden. Da dieser Erkrankungskomplex mit degenerativen Veränderungen der Achillessehne des Menschen vergleichbar ist, wäre eine Translation der gewonnenen Ergebnisse in die Humanmedizin wünschenswert. Die zugrunde liegenden Wirkmechanismen bei der Sehnenregeneration sind allerdings bis zum heutigen Tage noch nicht vollständig geklärt. Unter anderem wird eine tenogene Differenzierung der MSC mit nachfolgender Produktion von extrazellulärer Matrix (EZM) diskutiert. Als Nachweis hierfür wird die Genexpression von Matrixproteinen sowie Transkriptionsfaktoren angesehen. Die Isolation von MSC ist aus verschiedenen Geweben möglich; allerdings haben Untersuchungen deutliche Unterschiede in den in-vitro-Charakteristika zwischen den Zellquellen aufgezeigt. Trotz dieser unterschiedlichen Eigenschaften fasst die International Society for Cellular Therapy (ISCT) seit 2006 humane MSC als plastikadhärente Zellen mit tripotentem Differenzierungspotential sowie einem definierten Antigenprofil zusammen. Um eine Vergleichbarkeit equiner und humaner MSC und somit eine bessere Übertragbarkeit gewonnener Erkenntnisse aus der Pferdemedizin zu erreichen, steht aktuell die Untersuchung der geforderten Antigenexpression noch aus. 2. Ziele der Untersuchung In der vorliegenden Arbeit sollte daher erstmalig eine vollständige Charakterisierung des geforderten Antigenprofils equiner MSC aus fünf verschiedenen Quellen durchgeführt werden, um einen Vergleich mit humanen Zellen zu ermöglichen. Zudem sollte eine vergleichende Darstellung der Sehnenmarkerexpression durchgeführt werden, welche das Wissen um die in-vitro-Eigenschaften von MSC erweitern und in Folge zur Auswahl einer optimal für die Therapie von Sehnenerkrankungen geeigneten Zellquelle beitragen soll. 3. Materialien und Methoden In der ersten Studie wurden equine MSC aus Knochenmark, Fettgewebe, Nabelschnurblut, Nabelschnurgewebe und Sehnengewebe bis zur Passage 3 kultiviert und anschließend mittels Durchflusszytometrie auf das Vorkommen der Antigene CD 29, CD 44, CD 73, CD 90 und CD 105 sowie das Fehlen der Antigene CD 14, CD 34, CD 45, CD 79α und MHC II untersucht. In der zweiten Studie wurde eine Genexpressionsanalyse der Sehnenmarker Kollagen 1A2, Kollagen 3A1, Decorin, Tenascin-C und Skleraxis vergleichend mittels Echtzeitpolymerasekettenreaktion an den isolierten Zellen durchgeführt. In beiden Studien wurde eine Probenzahl von n= 6 für jede Zellquelle untersucht. 4. Ergebnisse Keine der untersuchten Zellquellen erfüllte die MSC-Definition der ISCT bezüglich des Antigenprofils. Insbesondere durch den fehlenden Nachweis CD 73 (< 3,07 %) in allen untersuchten Proben unterscheiden sich equine und humane MSC. Die einzigen stabil exprimierten Antigene sind die zusätzlich untersuchten Proteine CD 29 (37,5 % - 65,42 %) und CD 44 (32,2 % - 97,18 %). Das Vorkommen CD 105 konnte in MSC aus Fett- und Sehnengewebe belegt werden. Zusätzlich war ein Nachweis von CD 90 in MSC aus Fettgewebe möglich, welche somit die größte Ähnlichkeit mit der humanen Zellpopulation aufweisen. Die Studie zur Genexpressionsanalyse weist auf eine Basisexpression von Kollagen 1A2, 3A1 und Decorin in MSC aus verschiedenen Quellen hin, welche über der von nativem Sehnengewebe liegt. Auch hier weisen wiederum MSC aus Fettgewebe die höchste Expression auf. 5. Schlussfolgerungen Die vorliegende Arbeit leistet einen Beitrag zu einer vertiefenden in-vitroCharakterisierung equiner MSC. Das Antigenprofil equiner MSC ist nicht vollständig mit dem humaner identisch. Eine abschließende Beurteilung sollte durch Untersuchungen mit spezies-spezifischen Antikörpern erfolgen. Die Ergebnisse der Genexpressionsanalyse unterstützen die Theorie, dass MSC die Sehnenheilung durch Produktion von extrazellulärer Matrix beeinflussen. Der Einsatz von MSC aus Fettgewebe in der Therapie von Sehnenerkrankungen sollte forciert werden, da ihre hohe Sehnenmarkerexpression einen Hinweis auf eine Verbesserung der Sehnenregeneration darstellt.
347

SPÄNNKABLAR I REAKTORINNESLUTNINGEN : Utredning kring olika konstruktionstyper av Reaktorinneslutningar / Pre-stressed cables in the Reactor Containment : Investigation of different structure types of reactor containments

Al-Mukdadi, Saja, Khaleda, Yeasmeen January 2014 (has links)
Frågor kring kärnkraftverk har alltid varit ett omdiskuterat ämne. Kärnkraftens betydelse varierar stort mellan olika länder. Av 441 reaktorer i världen tillhör 10 av dem till Sverige. Kärnkraftverk i Oskarshamn är en av dem. Företaget OKG har beslutat att genomföra en övergripande utredning kring olika konstruktionstyper av reaktorinneslutningar med detta examensarbete. Arbetet begränsas till att göra en litteraturundersökning. En viss genomgång av både nationella och internationella rapporter har gjorts. Det primära syftet med detta examensarbete är uppdelat i två huvuddelar. Den första delen av utredningen visar olika konstruktionstyper av reaktorinneslutning i hela världen. Den andra delen visar de reaktorinneslutningarna som har en liknande konstruktion som på OKG d.v.s. betong som är förspänd med cementinjekterade spännkablar. En liknande konstruktion finns bl.a. i Finland och Frankrike. Vi har också diskuterat kontroller för andra konstruktionstyper där spännkablarna är omgivna av luft eller fettinjekterade. I utredningen redovisas en del inträffade skador och incidenter i Svenska och utländska kärnkraftverk reaktorer. Företaget har två övriga frågeställningar som undersöktes i senare skedet av arbetsgång. Spännkrafter minskar med tiden på grund av krympning och krypning i spännarmerade konstruktioner vilket påverkar säkerheten av konstruktionen negativt. Som en del av detta arbete utfördes undersökningar om det finns metoder att bestämma spännkrafter där spännkablarna inte är åtkomliga. I det slutliga skedet av utredningen undersöktes metoder som Trafikverket följer för att kontrollera sina broar d.v.s. utföra huvudinspektioner/ besiktningar. Huvudsyftet av examensarbetet har uppfyllts men vissa delar är begränsade på grund av mesta informationer av olika kärnkraftverk är konfidentiella och inte tillgängliga på nätet. Och alla våra undersökningar var webbaserade som innebär att vi hade inte möjlighet att hitta rätt informationer direkt från webben. Samtidigt kontakta de olika utländska kärnkraftverken var inte så lätt på kort varsel. Strålsäkerhetsmyndighet (SSM) hjälpte oss att få kontaktinformation av 3 olika länder. I slutet av rapporten ges analys och diskussion kring utredningen. / Questions regarding Nuclear Power Plants have always been a controversial subject. Nuclear power's importance varies between countries. Of the 441 reactors in the world 10 of them belongs to Sweden. Oskarshamn Nuclear Power Plant is one of them. OKG has decided to conduct a comprehensive investigation of this thesis work around some issues. The main purpose of this thesis work is to make a literature investigation about bracing cables in reactor containment. A specific review of national and international reports has been made and formed a collective basis with the company issues. The introductory part of this thesis is divided into two main parts. The first review of this report considers different structural types of reactor containment in the world. Most nuclear reactors are enclosed by a pre-stressed concrete containment and some have steel reactor containment. In both Sweden and Finland, the enclosure is designed as a concrete cylinder, which is pre-stressed both vertically and horizontally. The second review describes about those reactor containments, which has a similar construction to the OKG (the tendons are placed in the casing that after chucking was injected with cement mortar). A similar construction can be found in Finland and France. The investigation also reveals the damage and accidents in Swedish and foreign nuclear power reactors in recent years. Furthermore, company has two other issues, which were implemented in the later stages of the work. Due to shrinkage and creep in the concrete and relaxation in the tendons, the prestressed capacity decreases with time which affects the structure negatively. The objective of this thesis is to investigate if there are methods for determining tensile forces where the tendons are not accessible. Methods are divided into two different types: one is cement grouting method, same as OKG and another one is oil-injection method. The final review of report is to investigate about TRAFIKVERKET methods to check/inspection the bridges. It can be concluded that the main expectations of this thesis has been fulfilled but some parts are still missing due to limitation of proper information. To contact with the various foreign nuclear power plants was not so easy within this short time. All our experiments were web-based and there were many confidential matters which is unreachable. Swedish Radiation Safety authority (SSM) helped us to get contact details of 3 different countries. The discussions about the reviews are summarized at the end of the report.
348

Temperature induced stresses in a reactor containment building : A case study of Forsmark F1 / Temperaturinducerade spänningar i en reaktorinneslutning : En fallstudie av Forsmark F1

Könönen, Mattias January 2012 (has links)
Målen med denna uppsats var att studera två aspekter av temperatur inducerade spänningar med referens till kärnkraftsanläggningen Forsmark F1. Ena aspekten inkluderade den termiska kyleffekten av de ventilerade spännkabelrören i cylinderväggen. Det var av intresse att studera om den termiska kyleffekten av de ventilerade spännkabelrören hade en positiv global effekt som var relevant att beakta i globala tredimensionella modeller. Den andra aspekten inkluderade inverkan av ingjutet stål i den övreringplattan. Med syftet att studera om ingjutet stål var en aspekt som ansågs nödvändigt att beakta i transienta analyser.   Huvudanalyseringsverktyg var finita element metoden (FEM), genom användning av det kommersiellt tillgängliga finita element programmet SOLVIA.   Inverkan av den termiska kyleffekten av de ventilerade spännkabelrören indikerade en spännings reducerande effekt, med reducerade zoner av sprucken betong i cylinderväggen vid förhöjda temperaturer. Inverkan av ingjutet stål indikerade ökade temperaturskillnader mellan det ingjutna stålet och den omgivande betongen, med sprucken betong lokalt mellan stålet och betongen vid förhöjda temperaturer. Den termiska kyleffekten av de ventilerade spännkabelrören ansågs relevant att beakta i globala tredimensionella modeller. Ingjutet stål ansågs vara nödvändigt att inkludera i transienta analyser. / The aims of this thesis were to study two aspects of temperature induced stresses with reference to the nuclear power plant Forsmark F1. One aspect included the thermal cooling effect of the ventilated tendon ducts in the cylinder wall. It was of interest to study if the thermal cooling effect of the ventilated tendon ducts had a positive global effect which was relevant to consider in global three-dimensional models. The other aspect included the influence of embedded steel in the upper ring slab. With the purpose to study if embedded steel was an aspect that was considered necessary to include in transient analyses.   The used main analysis tool was the finite element method (FEM), through the use of the commercially available finite element program SOLVIA.   The influence of the thermal cooling effect of the ventilated tendon ducts indicated a stress reducing effect, with reduced cracked concrete in the cylinder wall at elevated temperatures. The influence of embedded steel indicated increased temperature differences between the embedded steel and the surrounding concrete, with cracked concrete locally between the steel and the concrete at elevated temperatures. The thermal cooling effect of the ventilated tendon ducts was considered relevant to consider in global three-dimensional models. Embedded steel was considered necessary to include in transient analyses.
349

Cyclic tensile tests of Shetland pony superficial digital flexor tendons (SDFTs) with an optimized cryo-clamp combined with biplanar high-speed fluoroscopy

Wagner, Franziska Carolin, Reese, Sven, Gerlach, Kerstin, Böttcher, Peter, Mülling, Christoph K. W. 05 March 2022 (has links)
Background: Long-term cyclic tensile testing with equine palmar/plantar tendons have not yet been performed due to problems in fixing equine tendons securely and loading them cyclically. It is well established that the biomechanical response of tendons varies during cyclic loading over time. The aim of this study was to develop a clamping device that enables repetitive cyclic tensile testing of equine superficial digital flexor tendon for at least 60 loading cycles and for 5 min. Results: A novel cryo-clamp was developed and built. Healthy and collagenase-treated pony SDFTs were mounted in the custom-made cryo-clamp for the proximal tendon end and a special clamping device for the short pastern bone (os coronale). Simultaneously with tensile testing, we used a biplanar high-speed fluoroscopy system (FluoKin) to track tendon movement. The FluoKin system was additionally validated in precision measurements. During the cyclic tensile tests of the SDFTs, the average maximal force measured was 325 N and 953 N for a length variation of 2 and 4 % respectively. The resulting stress averaged 16 MPa and 48 MPa respectively, while the modulus of elasticity was 828 MPa and 1212 MPa respectively. Length variation of the metacarpal region was, on average, 4.87 % higher after incubation with collagenase. The precision of the FluoKin tracking was 0.0377 mm, defined as the standard deviation of pairwise intermarker distances embedded in rigid bodies. The systems accuracy was 0.0287 mm, which is the difference between the machined and mean measured distance. Conclusion: In this study, a good performing clamping technique for equine tendons under repetitive cyclic loading conditions is described. The presented cryo-clamps were tested up to 50 min duration and up to the machine maximal capacity of 10 kN. With the possibility of repetitive loading a stabilization of the time-force-curve and changes of hysteresis and creep became obvious after a dozen cycles, which underlines the necessity of repetitive cyclical testing. Furthermore, biplanar high-speed fluoroscopy seems an appropriate and highly precise measurement tool for analysis of tendon behaviour under repetitive load in equine SDFTs.
350

A Biomechanical Investigation of Collagen, Platelet-rich Plasma, and Mesenchymal Stromal Cells on the Achilles Tendon in a Rat Model

Austin, Brittany Logan 28 May 2019 (has links)
No description available.

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