Introduction: Conventional suture repair of peripheral nerves following injury is associated with several limitations such as technical difficulty, intra- and extra-neural scar formation, axonal escape and the leakage of neurotrophic factors. These limitations are particularly relevant following nerve grafting when regenerating axons must traverse two coaptation sites. Outcomes following suture repair are notoriously poor, providing large impetus for the development of alternative methods. Photochemical tissue bonding (PTB) uses visible light to create sutureless, non-thermal bonds between two closely apposed tissue surfaces stained with a photoactive dye. When used with a human amnion nerve wrap for end-to end nerve repair, this technique results in superior functional and histological outcomes in comparison to conventional epineurial suture. When initially applied to large gap injury and nerve grafting, outcomes were unsuccessful due to proteolytic degradation of amnion and photochemical bonds during extended periods of recovery. Chemical crosslinking of nerve wraps prior to PTB may improve wrap durability and efficacy of technique. This thesis provides a comprehensive three-phase assessment of the efficacy of this novel approach when applied to the repair of large gap injuries with nerve grafts. Phase 1 assesses the ex vivo biomechanical properties of nerve wraps and light activated bonds in addition to the in vivo performance of photochemically sealed crosslinked nerve wraps against several other clinically relevant fixation methods in a rodent sciatic nerve isograft model. Following major multi-limb injury and amputation, demand for autogenous nerve graft may exceed that which can be supplied by the patient. Acellular nerve allograft (ANA) is an alternative option in these circumstances although outcomes are typically inferior to autograft. Phase 2 assesses the performance of the optimum repair strategy from phase 1 against conventional epineurial suture when applied to ANA. Most studies investigating the efficacy of novel repair techniques tend to perform repairs immediately following injury, a situation that rarely occurs clinically. Delays of weeks or months are not uncommon and have been shown to have a detrimental effect on regeneration and outcome. Phase 3 assesses the efficacy of PTB when applied to delayed nerve grafting. Additional work investigating a novel imaging technique for visualizing nerve revascularisation following injury and repair has been included. Optical frequency domain imaging (OFDI) uses low power infrared light to provide real time in vivo imaging of tissue microvasculature and flow characteristics. Originally applied to the study of tumour biology, this technique may prove useful for outcome assessment in preclinical research and eventually for the assessment of nerve viability in the clinical setting. Experiments investigating the early development of a brain body interface system (BBI) for upper limb reanimation following spinal cord injury (SCI) have also been included. The ultimate aim of this project is to restore autonomous motor control in a non-human primate (NHP) using cortically driven stimulation of peripheral nerves via implantable nerve cuffs. The experiments reported in this thesis detail the development of a selective, reversible paralysis model of elbow flexion in a NHP and demonstrate selective fascicular stimulation using acute and chronically implanted nerve cuffs in rodent and murine models. Methods: Phase 1: Three candidate nerve wraps (human amnion (HAM), crosslinked human amnion (xHAM), crosslinked swine intestinal sub-mucosa (xSIS)) and 3 fixation methods (suture, fibrin glue, PTB) were investigated. Crosslinking was performed using (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS). Biomechanical tests were performed using a tensiometer. Ex vivo wrap durability was assessed using a type- 2 collagenase degradation assay. Under isoflurane anaesthesia, 110 inbred male Lewis rats had 15mm left sciatic nerve defects created and repaired with reversed isografts. 9 groups (n=10) had isografts secured by one of the aforementioned wrap/fixation combinations. PTB repairs had nerve wraps and nerve ends stained with photoactive dye (Rose Bengal) and, once nerve ends were apposed and wrapped circumferentially, the interface was illuminated with a 532nm laser. Fibrin repairs had nerve ends apposed, wrapped circumferentially and secured with Tisseel fibrin glue. Suture repairs had nerve ends apposed, wrapped circumferentially and then secured with two 10-0 nylon sutures at each coaptation site (one either side of each repair). Positive and negative control groups (n=10) were repaired with graft+suture (10-0 nylon) and no repair respectively. Phase 2: 20 sciatic nerves were harvested from Sprague Dawley rats and sent to AxoGen Inc. for decellularisation. An additional 20 male inbred Lewis rats were randomized into 2 groups (n=10). All rats had 15mm left sciatic nerve defects created and repaired with processed ANA. 1 group had nerves secured using conventional epineurial suture. The remaining group had ANA secured using photochemically sealed amnion wraps. Phase 3: 40 inbred male Lewis rats were randomized into 4 groups (n=10). All 40 rats had 15mm left sciatic nerve gaps created and reconstructed with reversed isografts harvested from donor Sprague Dawley rats. In groups 1 and 2, nerve gaps were repaired immediately with either conventional epineurial suture or photochemically sealed amnion wraps, respectively. In groups 3 and 4, repair took place 30- days following injury using either conventional epineurial suture or photochemically sealed amnion wraps, respectively. All outcomes were assessed using walking track analysis and calculation of sciatic function index (SFI). Walking track analysis and SFI was performed pre-operatively, after the 30-day delay (phase 3) and at 30-day intervals following surgery. Following sacrifice after 5-months, left (experimental) and right (control) gastrocnemius muscles were excised and weighed for calculation of muscle mass retention. Nerves were excised for histomorphometric analysis including axon count, fiber diameter, axon diameter, myelin thickness and G-ratio. For all in vivo experiments, statistical analysis was performed using ANOVA, repeated measures ANOVA and the post hoc Bonferroni test. Optical Frequency Domain Imaging (OFDI) pilot study: eight rodents were randomized into 4 groups (n=2): (1) crush injury, (2) transection and end-to-end repair, (3) transection and repair of 10mm nerve gap using contralateral autograft, (4) transection and repair of 10mm nerve gap using ANA. Under ketamine/xylazine anaesthesia, all rodents had sciatic nerves exposed through hind limb dorsolateral incisions. Imaging was performed immediately pre-injury, immediately post-injury and on post-operative days 1, 3, 5 and 7. Rodents were secured firmly to polystyrene platforms in order to reduce movement artifact during imaging Brain-Body Interface (BBI) experiments: In the upper limb of a Rhesus macaque nonhuman primate, the median nerve branch to brachialis and radial nerve branch to brachioradialis were transected, leaving elbow flexion entirely reliant on the musculocutaneous nerve. The musculocutaneous nerve was transposed into a subcutaneous position. Ultrasound guided nerve block resulted in a highly selective, reversible paralysis of elbow flexion. Under ketamine/xylazine anaesthesia, Sprague Dawley rats (n=5) and C57 Black 6 mice (n=5) had sciatic nerves exposed through dorsolateral, muscle splitting incisions. 8-channel stimulating cuff electrodes were wrapped around sciatic nerves and connected to a Tucker14 Davies stimulation/recording system. Electromyography (EMG) needle electrodes were inserted into the tibialis anterior (TA) and gastrocnemius (G) muscles to record muscle activity.

Nos últimos anos, óxidos metálicos têm sido amplamente estudados para uma série de aplicações na indústria eletrônica e metalúrgica, sendo empregados em revestimentos anticorrosivos, sensores químicos, em dispositivos optoeletrônicos sensíveis, entre outros. Dentre os óxidos metálicos, o TiO2 (óxido de Titânio) tem enorme potencial em aplicações como sensor de gás, sensor de pH e em dispositivos fotossensíveis como células solares sensibilizadas por corante e para degradação fotocatalítica de compostos orgânicos. Há várias morfologias que podem ser obtidas para o TiO2, porém a de maior interesse atualmente é a de arranjos ordenados de nanotubos de TiO2 produzidos pelo processo de anodização do Ti, que por terem maior área superficial que outras morfologias como por exemplo, filmes finos, nanopilares e nanobastões, apresenta também maior sensibilidade à presença dos gases e/ou soluções a serem analisados, assim como maior absorção de fótons, além de uma menor recombinação de pares elétron-lacuna no material. Apesar destas várias vantagens, a atividade fotocatalítica do TiO2 é limitada por absorver apenas radiação ultravioleta devido a seu largo gap de aproximadamente 3,2 eV. Assim, neste trabalho foram produzidos nanotubos de TiO2 pelo processo de oxidação anódica do Ti, com diferentes parâmetros, correlacionando-os com a morfologia resultante. Com isso foi possível observar que o comprimento e diâmetro externo dos nanotubos de TiO2 crescem proporcionalmente com o aumento da tensão, sendo aproximadamente linear até um dado valor de saturação. A exceção a isto refere-se a nanotubos de TiO2 crescidos a partir de Ti depositado e substratos de vidro, no qual, há uma limitação de Ti a ser anodizado, de modo que após a conversão total do Ti em óxido não há mais o crescimento de nanotubos, porém os diâmetros gerados respeitam os mesmos valores para os casos em que não há essa limitação. Os nanotubos de TiO2 crescidos foram submetidos a processos de nitretação em um reator de deposição química a vapor assistida por plasma e os parâmetros foram avaliados com o intuito de encontrar as melhores condições para diminuição de seu gap, afim de aumentar sua atividade fotocatalítica. Pressão e potência de rádio frequência foram variados de 0,66 a 2,66 mBar (0,50 a 2,00 Torr) e 0,22 a 3,51 W/cm2 respectivamente. A maior diminuição no valor do gap, para 2,80 eV, foi obtida usando-se a pressão de 1,33 mBar (1,00 Torr), 1,75 W/cm2 de potência de rádio frequência durante um processo de 2 h a 320 °C, levando a uma diminuição de 14% no valor do gap e a um aumento de 25% na atividade fotocatalítica (redução de Azul de Metileno). Essa diminuição no valor do gap óptico dobra a abrangência de absorção de fótons de 5% para 10% do espectro solar. Os nanotubos de TiO2 nitretados produzidos com gap de 2,80 eV foram facilmente integrados a um microcanal de polidimetilsiloxano, produzindo um dispositivo fotocatalítico para estudo na fotodegradação de compostos orgânicos, podendo ser usado inclusive para redução de poluentes. O dispositivo fotocatalítico reduziu completamente 5 µL de solução de Azul de Metileno em cerca de 12 min, com uma taxa aproximadamente linear de 130 µM/h, enquanto os nanotubos de TiO2 como preparados apresentaram taxa de cerca de 115 µM/h. Logo, o dispositivo com nanotubos de TiO2 nitretados teve um aumento de 13% em sua eficiência de redução. / In recent years, metal oxides have been widely studied for a number of applications in the electronics and metallurgical industry, being used in anticorrosive coatings, chemical sensors, sensitive optoelectronic devices, among others. Among the metal oxides, TiO2 (titanium oxide) has enormous potential in applications such as gas sensor, pH sensor and in photosensitive devices such as dye sensitized solar cells and for photocatalytic degradation of organic compounds. There are several morphologies that can be obtained for TiO2, but the most interesting one today is ordered arrangements of TiO2 nanotubes produced by the Ti anodization process, which have a larger surface area than other morphologies such as thin films, nanopillars and nanobastones, also presents greater sensitivity to the presence of the gases and/or solutions to be analyzed, as well as greater absorption of photons, besides a smaller recombination of electron-hole pairs in the material. Despite these several advantages, the photocatalytic activity of TiO2 is limited by absorbing only ultraviolet radiation due to its wide gap of approximately 3.2 eV. Thus, in this work, TiO2 nanotubes were produced by the anodic oxidation process of Ti, with different parameters, correlating them with the resulting morphology. With this, it was possible to observe that the length and external diameter of the TiO2 nanotubes grow proportionally with the increase of the voltage, being approximately linear up to a given value of saturation. The exception to this relates to TiO2 nanotubes grown from Ti deposited and glass substrates, in which, there is a limitation of Ti to be anodized, so that after the total conversion of Ti to oxide, there is no longer growth of nanotubes, but the diameters generated respect the same values for cases in which there is no such limitation. The as grown TiO2 nanotubes were submitted to nitriding processes in a plasma assisted chemical vapor deposition reactor and the parameters were evaluated in order to find the best conditions to decrease their gap in order to increase their photocatalytic activity. Pressure and radio frequency power were varied from 0.66 to 2.66 mBar (0.50 to 2.00 Torr) and 0.22 to 3.51 W/cm2 respectively. The largest decrease in the gap value, to 2.80 eV, was obtained using the pressure of 1.33 mbar (1.00 Torr), 1.57 W/cm2 of radio frequency power during a process of 2 h in 320 °C, leading to a 14% decrease in gap value and a 25% increase in photocatalytic activity (reduction of Methylene Blue). This decrease in the value of the optical gap doubles the absorption range of photons from 5% to 10% of the solar spectrum. The nitrided TiO2 nanotubes produced with a gap of 2.80 eV were easily integrated into a microchannel of polydimethylsiloxane, producing a photocatalytic device for the study of photodegradation of organic compounds, and could be used to reduce pollutants. The photocatalytic device completely reduced 5 µL of Methylene Blue solution in about 12 min, with an approximately linear rate of 130 µM/h, whereas the TiO2 nanotubes as grown presented a rate of about 115 µM/h. Therefore, the device with nitrided TiO2 nanotubes had a 13% increase in its reduction efficiency.

This paper explores gender differences in learning and presents findings from a qualitative study into the effectiveness of teaching methods as regards boys’ learning. The applied part of the paper uses site-specific data collected from a state primary school in northern Italy which suggests that the methods employed by teachers is teacher-centered rather than student-centered. The data collected through observation, interview and questionnaire was measured against criteria formulated from experts in the field of boys’ education and analyzed through both an historical and cultural lens. The historical and social factors reveal noteworthy parallels between the approach to pedagogy and Italian culture. The results of the analysis indicate that the Italian methods observed were at times effective while also deficient. This same approach which continues in the middle and high schools is less effective as the other factors in the school arrangement change. The paper concludes with reasons for modifying the teaching method from strictly content, teacher-centered to one which also taps into additional intelligences and takes a more student-centered approach in order to raise motivation and effectiveness of learning which will in turn raise international performance levels and give the Italian student a competitive edge in the international academic arena.

Equality is part of the European policy and legislation. However there are still evident signs of women being treated unequally in the labour market. The aim of the thesis is to answer the question if women are more vulnerable to economic shocks in terms of wage distribution. The focus will be on women in Spain in the context of the financial crisis of 2008. The thesis examines the evolution of the salary structure in the period 2002-2014 using the microdata of the Structural Earning Survey. The taste-based and the statistical discrimination theory are going to be described in order to explain the causes of gender wage discrimination. The methods applied in this paper are the Mincer method, which explains the human capital theory and the Oaxaca-Blinder decompositions, which separates the gender wage gap into explained and unexplained parts. The results from the study suggest that there is a decrease in the gender wage gap in Spain following the situation before and after the crisis.

This paper studies the gap in wealth between male and female single households using 2010 Household Finance and Consumption Survey data for eight European countries. In the raw data, a large gap emerges at the upper end of the unconditional distribution. While OLS estimates show no difference in average net wealth levels, quantile regressions at the 95th percentile yield mixed evidence for the gender wealth gap in different specifications. Labour market characteristics and participation in asset and debt categories largely explain the differences between male and female single households. We show that the gender gap in net wealth is driven by gender gaps in gross wealth and its components, but is attenuated in four countries by gender gaps in (collateralized) debt. In the full specification, the unexplained gap in gross wealth amounts to 27% in Slovakia, 33% in France, 44% in Austria, 45% in Germany, and 48% in Greece. A robustness check using person-level pension wealth confirms the presence of a gender gap for the full population. / Series: Department of Economics Working Paper Series

This paper studies the gap in wealth between male and female single households using 2010 Household Finance and Consumption Survey data for eight European countries. In the raw data, a large gap emerges at the upper end of the unconditional distribution. While OLS estimates show no difference in average net wealth levels, quantile regressions at the 95th percentile yield mixed evidence for the gender wealth gap in different specifications. Labour market characteristics and participation in asset and debt categories largely explain the differences between male and female single households. The gender gap in net wealth is driven by gaps in gross wealth and its components, but is attenuated in four countries by gender gaps in (collateralized) debt. In the full specification, the unexplained gap in gross wealth amounts to 27 percent in Slovakia, 33 percent in France, 44 percent in Austria, 45 percent in Germany, and 48 percent in Greece.

>Magister Scientiae - MSc / Tellurium is a member of the chalcogen group in the periodic table and is known to be a better semiconductor material when compared to sulfur and selenium. By introducing tellurium into the kesterite structure there would be an improvement in the semiconducting property of the kesterite material. This research focused on incorporating tellurium into kesterite structure in order to reduce its band-gap thereby improving its light absorption and ultimately lead to a more efficient photovoltaic effect. For a typical synthesis, kesterite nanoparticles were synthesized by anion hot injection process which involved the injection of the anion precursor comprising of sulfur, selenium and tellurium in diethylene glycol into a solution containing the cation precursor which are copper (II) chloride, Zinc chloride and tin (II) chloride which are dissolved in diethylene glycol. The synthesized nanoparticles were copper zinc tin sulfide (CZTS), copper zinc tin sulfide selenide telluride (CZTSSeTe) and copper zinc tin sulfide telluride (CZTSTe). Morphological characterization of the synthesized nanoparticles was carried out by high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM) to obtain the shape of the surface and internal structure of the nanoparticles respectively. The micrograph obtained from HRSEM shows that all synthesized nanoparticles had a flower-like surface appearance which is a common morphology obtained for non-vacuum synthesized kesterite nanoparticles. The micrograph obtained from TEM showed that all nanoparticles were agglomerated and had a black surface covering which attributable to the solvent used during synthesis, washing and centrifugation. The internal structure of the synthesized nanoparticles was obtained through small angle x-ray scattering (SAXS) plot of the shapes. The shape obtained for the nanoparticles were core shell hollow sphere for CZTS, core shell dumb-bell for CZTSSeTe and solid sphere for CZTSTe.

Philosophiae Doctor - PhD / The continuous increase in energy consumption and decrease in fossil fuels reserves are a primary concern worldwide; especially for South Africa. Therefore, there is an urgent need for alternative energy resources that will be sustainable, and environmentally friendly in order to tackle the ecological degradation generated by the use of fossil fuels. Among many energy ‘niches’, solar energy appears to be one of the most promising and reliable for the African continent because of the constant availability of sun light. Organic conjugated polymers have been identified as suitable materials to ensure proper design and fabrication of flexible, easy to process and cost-effective solar cells. Their tendency to exhibit good semiconducting properties and their capability to absorb photons from the sunlight and convert it into electrical energy are important features that justify their use in organic photovoltaic cells. Many different polymers have been investigated as either electron donating or electron accepting materials. Among them, poly(3-hexylthiophene) is one of the best electron donor materials that have been used in organic photovoltaic cells. It is a good light absorber and its Highest Occupied Molecular Orbital (HOMO) energy level is suitable to allow electron transfer into an appropriate electron acceptor. On the other hand, the molecular ordering found in dendrimers attracted some interest in the field of photovoltaics as this feature can ensure a constant flow of charges. In this work, I hereby report for the first time, the chemical synthesis of a highly crystalline dendritic star copolymer generation 1 poly(propylene thiophenoimine)-co-poly(3-hexylthiophene) (G1PPT-co-P3HT) with high molecular weight and investigate its application as donating material in bulk heterojunction organic photovoltaics.

Varje dag ser vi en kraftig marknadsföring av olika spel på marknaden, därolika typer av spel har egna program, reklam som sänds på de bästasändningstiderna och populära ungdomsprogram är sponsrade av olikaspelbolag. Spelmarknaden försöker locka spelare med höga vinster, vilketleder till att kunderna återkommer i hopp om att vinna. Spelbolagen försökertillfredställa kundernas behov genom att få kunderna att bli lojala tillföretaget. Dagens spelmarknad har utvecklats vilket har gjort attspelbranschen har blivit mer beroende av tekniken. Den nya teknologin harbidragit till en stor kontaktenhet mellan företag och konsumenter som gerföretagen en möjlighet att hitta nya sätt att möta kundbehoven på.Vår undersökning handlar om vilka faktorer som är betydelsefulla för attreducera gapet mellan förväntningar och upplevelser för spelprodukter samten jämförelse mellan Svenska Spel och utländska aktörer. Vi har ävenundersökt hur utvecklingen av teknologin har påverkat utbudet av spel, därundersökningen har utförts genom en kvalitativ studie, där intervjuerna hargjorts med Svenska spel, Betsson och Unibet.De slutsatser vi har kommit fram till är att budskapet i reklamen är det somkan reducera gapet mellan upplevelse och förväntningarna genom attreklamen ska vara trovärdig på det sättet att kunderna vet att det finns enmöjlighet att vinna. Skillnaden mellan Svenska spel och de utländskaaktörerna är att Svenska spel är statligt reglerad, anledningen till monopoletär att det uppfyller sociala skäl då pengar går tillbaka till samhällsnytta. Deutländska aktörerna är privatägda och då går pengarna tillbaka tillaktieägarna. Internetanvändandet har blivit en del av människans vardag ochspelbolagen har gjort det bekvämt för kunderna då de kan sitta hemma ochanvända deras tjänster på nätet. Att de är tillgängliga för sina kunder dygnetrunt bidrar till att de kan skaffa sig nya kunder. / Uppsatsnivå: C

In this thesis we examine the prevailing dilemma concerning fast fashion and an increased attitude-behaviour gap. Many previous studies have explored the subject of fast fashion and also tried to solve the problem with the attitude-behaviour gap. We want to take this a step further by investigating what influence fast fashion may have on consumers' perception of value. By exploring this we hope to gain further knowledge concerning the attitude-behavior gap.Our focus is on young female consumers, since previous studies show the likelihood of the gap between intent and action being the largest in this consumer group. To a certain extent it can be explained by their frequent purchase of fast fashion, but also the fact that younger consumers are more influenced by fashion press and celebrity culture. This study is foremost based on qualitative research and is completed with the use of two focus groups, as well as a more quantitative research in the form of a content analysis of the Swedish fashion magazine, Sofis Mode. The study has a deductive approach.The theoretical perspectives consist of theories concerning value; value in relation to price and the concept of value. We also present a redefined model of perceived value. The results show evidence of increased focus and exposure of low priced fashion and that the low perceived monetary price has a significant impact of consumers‟ perceived value of clothing. The focus on selling low price instead of value inclines that clothes have lost its intrinsic value, as a result making clothes easily replaceable. Our study further shows a smaller attitude-behaviour gap among consumers with a high knowledge of textiles and textile production. / Program: Master in Fashion Management with specialisation in Fashion Marketing and Retailing