Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2016. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-09-08T19:03:51Z No. of bitstreams: 1 2016_JaquelineAlvesRibeiro.pdf: 2612234 bytes, checksum: 1572b341382aba1a47d87ac82645b3c7 (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2017-01-30T21:48:56Z (GMT) No. of bitstreams: 1 2016_JaquelineAlvesRibeiro.pdf: 2612234 bytes, checksum: 1572b341382aba1a47d87ac82645b3c7 (MD5) / Made available in DSpace on 2017-01-30T21:48:56Z (GMT). No. of bitstreams: 1 2016_JaquelineAlvesRibeiro.pdf: 2612234 bytes, checksum: 1572b341382aba1a47d87ac82645b3c7 (MD5) / O crescente desenvolvimento tecnológico e os avanços no campo da medicina permitiram uma significativa melhoria na qualidade de vida da população. Como por exemplo, desenvolvimento de biomateriais, que são empregados para substituir total ou parcialmente tecidos orgânicos perdidos ou danificados, ou mesmo serem utilizados em contato direto e contínuo com o corpo para realização de tratamento não farmacológico. A disfunção oftálmica ambliopia, também conhecido popularmente como olho preguiçoso, consiste na baixa de visão em um olho por não ter se desenvolvido adequadamente na infância. O objetivo desse trabalho foi a obtenção e caracterização de membranas de borracha natural a fim de avaliar sua viabilidade de aplicação como uma membrana oclusora com propriedade de alterar a passagem de luz e estimular o olho amblíope. Trata-se de uma nova proposta para tratamento de pacientes amblíopes utilizando membranas de látex. As membranas de látex foram confeccionadas pelas técnicas de deposição e a técnica criada denominada de Van Gogh sendo caracterizadas através de métodos físicos e químicos, a fim de analisar as propriedades do látex in natura e das membranas de borracha natural, tratadas termicamente a 40 e 70 °C. Os métodos utilizados para a caracterização das amostras foram: microscopia eletrônica de varredura (MEV), medidas de fluorescência, difração de raios X (XRD), análises termogravimétricas (TG), calorimetria exploratória diferencial (DSC), análise de absorção em soro fisiológico, espectroscopia por FT-IR modo ATR, análise de componentes principais e análise de passagem de luz. Na caracterização das membranas foram analisadas as propriedades dos polímeros com o intuito de se obter dados sobre a viabilidade do uso de uma membrana de látex LENCOC® no tratamento de ambliopia com segurança e conforto para o usuário. Foi possível verificar a passagem de luz das membranas de Van Gogh M1 e M2 com a oclusão parcial e total, respectivamente. Conclui-se que, os ensaios utilizados na caracterização da membrana de látex LENCOC® mostraram-se satisfatórios e promissores para sua utilização no tratamento da ambliopia. / The growing technological development and the advancements in the field of medicine caused significant improvement in the quality of life of the population. One example is the development of biomaterials, which are used to completely or partially replace parts of lost or damaged organic tissues and are also used in direct and continuous contact with the body in non-pharmacological treatments. Amblyopia, an ophthalmic disorder commonly known as lazy eye, result in decreased vision in one eye that does not develop properly during childhood. The objective of this study was to obtain and characterize natural rubber membranes in order to evaluate the feasibility of its application as an occluder membrane with the capacity of changing the course of light and stimulating the amblyopic eye. This is a new proposal for treating amblyopic patients using latex membranes. The latex membranes were produced with the deposition technique and a new technique called Van Gogh. They were characterized using physical and chemical methods in order to analyze the properties of latex in natura and of the natural rubber membranes, thermally treated at 40 °C and 70 °C. The methods used to characterize the samples were: scanning electron microscopy (SEM), Fluorescence measurements, X-ray diffraction (XRD), thermogravimetric analyses (TG), differential scanning calorimetry (DSC), saline absorption analysis, FT-IR spectroscopy ATR mode, principal component analysis (PCA) and light crossing analysis. When characterizing the membranes, we analyzed the properties of the polymers with the goal of obtaining data on the feasibility of using a LENCOC® latex membrane in the treatment of amblyopia with safety and comfort for the patient. The light crossing analysis of the M1 and M2 Van Gogh membranes presented partial and total occlusion, respectively. We concluded that the tests used for characterizing the LENCOC® latex membrane were satisfactory and promising regarding its use for the treatment of amblyopia.

Tese (doutorado)—Universidade de Brasília, Faculdade de Ciências da Saúde, Programa de Pós-Graduação em Ciências da Saúde, 2016. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-12-14T16:07:06Z No. of bitstreams: 1 2016_WashingtonMacedodeSantana.pdf: 38327426 bytes, checksum: e47568d236b31de6b770c1a68be8fc32 (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2017-01-25T19:04:10Z (GMT) No. of bitstreams: 1 2016_WashingtonMacedodeSantana.pdf: 38327426 bytes, checksum: e47568d236b31de6b770c1a68be8fc32 (MD5) / Made available in DSpace on 2017-01-25T19:04:10Z (GMT). No. of bitstreams: 1 2016_WashingtonMacedodeSantana.pdf: 38327426 bytes, checksum: e47568d236b31de6b770c1a68be8fc32 (MD5) / Objetivo: O propósito deste estudo foi observar histologicamente em defeitos criados em calvária de ratos, o potencial da aplicação local da sinvastatina na estimulação da formação óssea e avaliar os efeitos da asociação da sinvastatina com dois tipos de carreador: Fosfato de cálcio (BoneCeramic®) ou Esponja de colágeno (CollaTape® ) na neoformação óssea. Materiais e métodos: Defeitos bilaterais foram obtidos nas calvárias de 15 ratas jovens. Esses defeitos tinham 5 mm de diâmetro e foram divididos em 5 grupos de acordo com o tipo de tratamento recebido: grupo 1(C) – controle, sem tratamento; grupo 2 (BC) - tratados com 14 mg BoneCeramic®; grupo 3 (BCS) - tratados com 14 mg de BoneCeramic® combinado com 0,1 mg de sinvastatina em solução alcoólica; grupo 4 (EC) - tratados com esponja de colágeno (CollaTape®); e grupo 5 (ECS) - tratados com esponja de colágeno combinada com 0,1 mg de sinvastatina em solução alcoólica. Após 8 semanas os animais foram sacrificados e as regiões dos defeitos submetidas à coloração Hematoxilina/Eosina (HE), seguida de avaliação histomorfométrica. Além disso, no grupo (BCS) foram realizadas análises histoquímica por tricromio de Masson e picrosirius red para caracterizar o tecido neoformado. Resultados:. Os resultados histológicos mostraram que a utilização local da sinvastatina favoreceu à neoformação óssea. O melhor resultado quanto à neoformação óssea foi obtido no grupo tratado com BCS, seguido do grupo BC. No grupo tratado com BCS a quantidade de neoformação óssea foi maior do que no grupo tratado com BC, ECS, EC, e C, e essas diferenças foram estatisticamente significativas(BCS 12,71 ± 1,21; BC 9,04 ± 0,86; ECS 2,25 ± 0,61, EC 0,91 ± 0,86 e C 0,00 ± 0,00) Não houve diferenças na neoformação óssea nos grupos ECS, EC e C . Além disso, a análise histoquímica do grupo (BCS), evidenciou a presença de neoformação óssea com a neoformação de tecido osteóide imaturo pelo tricrômio de Masson, além de colágeno organizado tipo I ao redor das partículas do BoneCeramic. Conclusão: Os resultados sugerem que a sinvastatina localmente administrada na concentração pré-estabelecida de 0,1mg, quando associada ao Fosfato de Cálcio Bifásico (BoneCeramic®) osteocondutor, resultou em maior neoformação óssea, comparado ao uso do Fosfato de Cálcio (BoneCeramic®) isoladamente, ou a sinvastatina associado à esponja de colágeno. Portanto a combinação de sinvastatina e BoneCeramic® pode ter um grande potencial no tratamento de defeitos ósseos. / OBJECTIVE: The objective of the present study was to examine the potential of locally applied simvastatin on the induction of bone formation and to evaluate the combination of simvastatin with two different carriers: biphasic calcium phosphate (BoneCeramic®) or collagen sponge on stimulation of bone formation. Methods: Thirty defects of 5mm in diameter were created bilaterally with a trephine bur in the calvariae of fifteen Wistar rats. The defects were divided into 5 groups: group 1 - control, no treatment; group 2 (BC) treated with 14mg of BoneCeramic®; group 3 (BCS) treated with 14mg of BoneCeramic® + 0.1mg simvastatin in alcoholic solution; group 4 (EC) treated with a collagen sponge (CollaTape®); and group 5 (ECS) treated with a collagen sponge + 0.1mg simvastatin in alcoholic solution. After eight weeks the animals were euthanized and their calvariae were histologically processed. Hematoxylin and eosin-stained sections were subjected to histological and histomorphometrical analyses. The area of newly formed bone was calculated and compared between groups. Furthermore, the newly formed tissue in group BCS was histochemically analyzed by Masson and picrosirius red satinings to better characterize this tissue. Results: The histological findings showed that the local application of simvastatin induced bone neoformation. The greater amount of a bone-like tissue was formed around the carrier in group 3 (BCS) followed by group 2 (BC). In group BCS, the amount of newly formed bone was greater than groups BC, ECS, EC, and C and these differences were statiscally significant (BCS 12,71 ± 1,21; BC 9,04 ± 0,86; ECS 2,25 ± 0,61, EC 0,91 ± 0,86 e C 0,00 ± 0,00). There was no difference among groups ECS, EC and C. The histochemical analyses of the newly formed tissue from group BCS showed the presence of an osteoid tissue, as shown by the Masson’s trichrome staining. Besides, the presence of organized type I collagen was evidenced around the BoneCeramic particles. Conclusions: The results suggest that locally applied simvastatin at a concentration of 0,1mg combined with BoneCeramic® induced significantly greater amounts of newly formed bone as compared with BoneCeramic® alone or simvastatin combined with collagen sponge. Therefore, the combination of simvastatin and BoneCeramic® and has great potential for the healing of bone defects.

In this work a model system has been developed to quantitatively study esterification of cellulosic material during drying and heating in which solid-state conditions can be said to predominate. The formation of ester cross-links in cellulosic or lignocellulosic composite materials during drying and heating is of interest for production of paper and wood composite boards, for wood modification and in giving cotton materials improved characteristics. The results support the hypothesis that direct ester formation, without anhydride intermediate, occurs between carboxylic acids of suitable structure and cellulosic hydroxyls at elevated temperatures even after such short reaction times as 5 minutes. Ester formation has been observed at temperatures ranging from 90°C to 180°C. Another important conclusion is that a hydroxy or keto group in alpha position of the carboxylic acids seems to favour ester formation. A critical parameter for ester formation is pH, and the results indicate that pH 5-6. In the experiments, low moisture content, higher temperatures and longer reaction times also favour ester formation, with some exceptions. Another interesting finding is that three pyrrolidine structures are produced after esterification and aminolysis of 2- ketobutyric acid. One of the structures indicates that 2-ketobutyric acid is reactive in two positions and could therefore be a potential cross- linker. Esterifications of five structurally different carboxylic acids-2(R)- hydroxybutyric acid, 2-ketobutyric acid, 3-hydroxybutyric acid, hexanoic acid and veratric acid have been studied. The carboxylic acids and moisture were added to ordinary cellulosic filter paper. Samples were heated at temperatures ranging from 22°C to 180°C between 5 and 45 minutes. Quantitative analysis of ester formation, in this case between the monocarboxylic acids and the cellulose's hydroxyl groups, was performed using aminolysis/gas chromatography. / <p>Godkänd; 2006; 20070109 (haneit)</p>

Computed tomography (CT) can be used to study wood-water interactions in differentways, such as by determining wood moisture content (MC). The determination of MCrequires two CT images: one at the unknown moisture distribution and a second one ata known reference MC level, usually oven-dry MC. The two scans are then compared.If the goal is to determine the MC in local regions, when studying moisture gradients forinstance, wood shrinkage must be taken into account during the data processing of theimages. The anisotropy of wood shrinkage creates an obstacle, however, since theshrinkage is not uniform throughout the wood specimen. The objective of this thesis was to determine the shrinkage in wood in each pixel of aCT image. The work explores two different methods that estimate from CT images, thelocal shrinkage of a wood specimen between two different MC levels. The first methoddetermines shrinkage for each pixel using digital image correlation (DIC) and isembedded in a wider method to estimate the MC, which is the parameter verifiedagainst a reference. It involves several steps in different pieces of software, making ittime-consuming and creating many sources of possible experimental errors. The MCdetermined by this method showed a strong correlation with the gravimetricallymeasured MC, showing an R2 of 0.93 and the linear regression model predicted MCwith a RMSE of 1.4 MC percentage points. The second method uses the displacement information generated from the spatialalignment of the CT images in order to compute wood shrinkage in the radial andtangential directions. All the required steps are combined into a single computeralgorithm, which reduces the sources of error and facilitates the process. The RMSEbetween this method and the determination of shrinkage measured in the CT imagesusing CAD has shown acceptable small differences. Both methods have proved to be useful tools to deal with shrinkage in different ways byusing CT images. In one case MC was successfully estimated, being the shrinkagecalculation a necessary step in the process, and in the other case the radial and tangentialshrinkages were successfully estimated for each pixel. Nevertheless, the difficulty incomparing the shrinkage coefficient calculated for local regions with a reference valuesuggest that more research must be carried out in order to be able to draw reliableconclusions.

The interest in Wood-thermoplastic composites (WPCs) has increased during the last decades. WPCs are commonly used as building material for decking and railing because of its low need of maintenance. Wood is a renewable resource of good mechanical properties and this make wood fibers interesting to use as reinforcement in a thermoplastic composite. A drawback with this type of composite is the poor long-term mechanical properties which limit its field of applications. The objective of this work was to optimize the process and understand structure-property relations of silane-crosslinked WPCs produced in a one-step reactive extrusion. The specific goal of crosslinking the composite was to improve the interfacial strength and stabilize the polymer matrix in order to improve these composites long-term mechanical properties.Silane-crosslinked WPC was produced by adding wood flour, polyethylene and a silane-peroxide solution to a compounding extruder. The composites were thereafter conditioned in different environments to promote the formation of silane-crosslinks. Parameters like wood flour moisture content, amount/composition of silane-peroxide solution and different general types of polyethylene was studied and related to the efficiency of the process.It was found that silane-technology applied to WPCs can be optimized in terms of processability and achieved property improvements. All crosslinked composites in this study have improved in strength, toughness and creep resistance but it was shown that the tested parameters have affect on both processing and properties. A gentle use of peroxides in the process was concluded to be positive for both processability and resulting property improvements. The unintentional crosslinking in the extrusion process is a drawback but was limited by lower peroxide concentrations. The use of low density polyethylene as polymer matrix lead to twice as high crosslinking rate compared to a high density polyethylene matrix. However, too excessive moisture uptake in the composites appears to lower the efficiency of crosslinking. Future studies should evaluate long-term load behavior more thoroughly and also investigate the conditioning step more carefully. / Godkänd; 2009; 20090922 (grubb)

Wood as a raw material is useful for many purposes even though some properties are less than optimal, for example, dimensional stability and durability. These characteristics can however be improved by different treatment methods. Environmental awareness has led to an increased demand for environmentally friendly processes like thermal modification that does not add any chemicals to the wood in contrast to, for example, CCA-impregnated wood.This thesis mainly focuses on thermally modified wood from species such as pine, spruce and birch. The thesis present studies of physical attributes such as color, and chemical analysis of water-soluble compounds and degradation products. Treatment intensity is compared between two different industrial processes referred as Thermowood and WTT, which use respectively superheated steam and pressurized steam as heating media.Thermal modification processes darken the color of wood throughout its cross-section. The formation of darker color is related to a degradation processes that takes place during thermal modification. During thermal modification wood is exposed to temperatures between 160 - 220°C, and the temperature causes physical and chemical transformations that change some of the wood properties. Dimensional stability and durability are typically improved, but mechanical strength properties are usually negatively affected by the treatment.The studied wood species were Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L.) and Birch (Betula pendula L.). Treatments using pressurized steam were carried out under temperatures of 160°C, 170°C and 180°C, and treatments using superheated steam at normal air pressure were carried out at temperatures of 190°C and 212°C. Results showed that similar L* (lightness) can be reached at lower temperatures using pressurized steam compared to superheated steam. The residual moisture content after completed thermal modification was approximately 10% higher in wood treated with the pressurized steam process. It was found that despite an approximately 25°C lower treatment temperature, birch modified in pressurized steam was more acidic compared to birch modified in superheated steam. This will likely have further consequences, requiring more research concerning surface treatment and fixation.The thesis also includes the development of an industrial-quality control procedure based on nondestructive color measurements verified in industrial environment. Treatment intensity in industry is today certified by inspection of documented process schedule and measuring the temperature and time of the process. Quality control in this context refers to the measurement of wood color as an indirect measure of treatment intensity. The color in our study was measured using L*C*H color space. The study shows that it is possible for quality control purposes to measure the color of thermally modified wood from the surfaces of planed boards instead of sawdust or board cross sections that have been used in other studies.The thesis has a final section about academia-industry collaboration that describes how trust building was established through a fruitful relationship involving academia and regional wood products industry in northern Sweden. The study presents an example of a successful research and development alliance between university and a group of small- and medium-sized enterprises (SMEs). This alliance has been a great example on international collaboration involving researchers originating from Finland, China, Bangladesh, Spain, Russia and Sweden. Through an in-depth multi-year study of how the research cooperation developed, the paper describes how the involved companies successfully entered into a new segment of the market. / För godkännande; 2016; 20160314 (olahof); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Ola Dagbro Ämne: Träfysik/Wood Physics Avhandling: Studies on Industrial-Scale Thermal Modification of Wood Opponent: Associate Professor Lidia Gurau, Faculty of Wood Engineering, Transilvania University, Brasov, Romania. Ordförande: Professor Diego Elustondo, Avd för träteknologi, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet, Luleå. Tid: Torsdag 16 juni, 2016 kl 10.00 Plats: Luleå tekniska universitet, Campus Skellefteå

Godkänd; 1998; 20070404 (ysko)

Improved understanding of moisture and mechanical behaviour is an international objective for wood drying research. The main objective of this licentiate thesis work was to develop an experimental method suitable for collecting valuable response data related to the moisture and mechanical behaviour of drying wood. Another objective was to provide an example on how multivariate methods can be used to analyse response data. A method for simultaneous non contact measuring of two dimensional surface deformations and interior densities have been developed. This was done using Digital Speckle Photography, DSP, and X-ray Computerised Tomography (CT). Displacements and densities were used for calculation of strains and moisture contents using a custom software developed in Matlab. Experimental tests of the measuring method were made on cross sections of Scots pine. The following accuracy was stated for different properties: - Displacements measured with DSP could be measured with a random error down to 0.01 pixels. A more typical calculated displacement error of approximately 10 micrometres, was found in paper I. - Strains derived from the displacements had a maximal error of 1.11 mstrain in an experimental test in paper II. - Accuracy in density measurements was expected to be less than +-6 kg/m3 for wet wood with moisture contents ranging from 6-100% and less than +-2 kg/m3 in dry wood, at a significance level of 0.05. This was estimated for a 2x2x1.5 mm3 measuring volume. - Moisture content measuring accuracy was estimated by simulations in paper II, which resulted in a measuring accuracy of +-1.8% moisture content at a significance level of 0.05 in a measuring volume with the approximate size of 2x2x1.5 mm3. A multivariate analysing method has been used to present an example on multivariate modelling of shrinkage behaviour in Radiata pine. The method was found to be an easy-to-use tool and useful for valid prediction of radial, tangential, longitudinal and volume shrinkage in the moisture range between 0% and 22% moisture content of the studied wood. The method also proved to be effective for untangling relationships between variables and generating information out of data. Finally, it can be stated that the developed measuring technique and the tested multivariate analysing method will be of use to improve the understanding of the behaviour of drying wood, focusing on moisture and mechanical properties. / Godkänd; 2002; 20070222 (ysko)

Carbon is a necessary reductant in steel production to convert iron ore to metallic iron. The use of coal and coke causes CO2 emissions to be released into the environment. Using bio-based carbon sources has the potential to offset these emissions and reduce cokemaking overall carbon footprint. The use of biomaterial in coal blends reduces the fossil fuel requirements but to what capacity and type of biocarbon can replace coal is unknown. The full effects of coal and coke characterization from the addition of biomaterial are unknown. In this work, raw biomaterials available to industrial users were evaluated for substitution at low amounts in operational coal blends. Physically, the optical properties of carbon coke forms can provide insight into the strength, reactivity, and performance in the blast furnace, resulting from coal rank and type. The interaction of the biomaterial substitutions with coal during the coking process is evaluated to better understand the reduction in coke strength after reaction (CSR). For this purpose, a series of the pilot oven and sole heated oven tests were performed. When coal was substituted with low amounts of raw biomaterials, the most notable changes in coke texture analysis were to incipient and circular textures. In this work, data from a series of pilot oven and sole heated oven tests showed that fine coke textures and overall inerts increased. The changes in coke textures can be linked to decreases in coke strength after reaction (CSR). / Thesis / Master of Applied Science (MASc) / Metallurgical coke remains the main fuel and reductant source for ironmaking by blast furnace operation. Quality metallurgical coal, a fossil fuel, is required to produce coke. This work continues ongoing steel industry research investigating biomaterial substitution of coal as a more sustainable option. Coal is considered a new release of greenhouse gas (GHG) emissions when used in the steelmaking process compared to a biomaterial which is regarded as a GHG neutral replacement. Three raw biomaterials, available to industrial users, were evaluated for substitution at low amounts and compared to an operational coal blend. The substitution could allow for GHG emissions of the cokemaking processes to be reduced if quality coke can be produced. The interaction of the biomaterial substitutions with coal during the coking process is evaluated in this work to better understand the resultant coke textures related to reduction in coke strength from the substitution.

In the field of biofabrication, biopolymer-based hydrogels are often used as bulk materials with defined structures or as bioinks. Despite their excellent biocompatibility, biopolymers need chemical modification to fulfill mechanical stability. In this thesis, the primary alcohol of hyaluronic acid was oxidized using TEMPO/TCC oxidation to generate aldehyde groups without ring-opening mechanism of glycol cleavage using sodium periodate. For crosslinking reaction of the aldehyde groups, adipic acid dihydrazide was used as bivalent crosslinker for Schiff Base chemistry. This hydrogel system with fast and reversible crosslinking mechanism was used successfully as bulk hydrogel for chondrogenic differentiation with human mesenchymal stem cells (hMSC). Gelatin was modified with pentenoic acid for crosslinking reaction via light controllable thiol-ene reaction, using thiolated 4-arm sPEG as multivalent crosslinker. Due to preservation of the thermo responsive property of gelatin by avoiding chain degradation during modification reaction, this gelatin-based hydrogel system was successfully processed via 3D printing with low polymer concentration. Good cell viability was achieved using hMSC in various concentrations after 3D bioprinting and chondrogenic differentiation showed promising results. / Im Bereich der Biofabrikation werden Hydrogele auf Biopolymerbasis häufig als Bulkmaterial mit definierten Strukturen oder als Biotinten verwendet. Obwohl Biopolymere eine hervorragende Biokompatibilität aufweisen, müssen sie jedoch chemisch modifiziert werden, um gewisse mechanische Stabilität für den Einsatz in der Biofabrikation zu erreichen. In dieser Arbeit wurde der primäre Alkohol der Hyaluronsäure mit Hilfe der TEMPO/TCC-Oxidation oxidiert, um Aldehydgruppen zu generieren. Dabei findet kein Ringöffnungsmechanismus statt, wie er bei der Glykolspaltung mit Natriumperiodat vorkommt. Für die Vernetzungsreaktion der Aldehydgruppen wurde Adipinsäuredihydrazid als bivalenter Vernetzer für die Bildung der Schiffschen Base verwendet. Dieses Hydrogelsystem mit schnellem und reversiblem Vernetzungsmechanismus wurde erfolgreich als Bulkhydrogel für die chondrogene Differenzierung mit humanen mesenchymalen Stammzellen (hMSC) erfolgreich eingesetzt. Als Mikrogele könnte das System in künftigen Forschungsarbeiten auf seine Verdruckbarkeit getestet werden. Gelatine wurde mit Pentensäure modifiziert, um die Vernetzungsreaktion über eine lichtkontrollierbare Thiol-En-Reaktion durchzuführen, bei der thioliertes 4-armiges sPEG als multivalenter Vernetzer verwendet wurde. Da die thermoresponsive Eigenschaft der Gelatine erhalten blieb, indem der Kettenabbau während der Modifizierungsreaktion vermieden wurde, konnte dieses Hydrogelsystem auf Gelatinebasis erfolgreich im 3D-Druck mit niedriger Polymerkonzentration verarbeitet werden. Mit hMSC in verschiedenen Konzentrationen wurde nach dem 3D-Biodruck eine gute Zellviabilität erreicht und die chondrogene Differenzierung zeigte vielversprechende Ergebnisse.