Orientador: Marcos Akira D'Ávila / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-28T14:33:17Z (GMT). No. of bitstreams: 1 Segundo_JoaodeDeusPereiradeMoraes_M.pdf: 7452357 bytes, checksum: ad3c155a2b3b137e6642655d1af1ef0f (MD5) Previous issue date: 2015 / Resumo: A eletrofiação é uma das principais técnicas para produzir fibras poliméricas ultrafinas na escala nano e submicrométrica. A poli ('épsilon'-caprolactona) (PCL) é um polímero sintético biodegradável bastante utilizado na área médica. Fibras de PCL obtidas por eletrofiação formam mantas porosas propícias para aplicações biomédicas como na engenharia tecidual. Em algumas aplicações as fibras alinhadas de PCL são de interesse, pois conferem melhorias em determinadas propriedades quando comparadas com fibras aleatórias. A PCL é considerada um polímero moderadamente hidrofóbico e a eletrofiação aumenta a hidrofobicidade das mantas. Os surfactantes têm a capacidade de modificar a superfície das fibras poliméricas aumentando a sua molhabilidade. Este trabalho versa sobre a influência da adição de surfactantes catiônico (CTAB), aniônico (SDS) e não-iônico (Triton X-100) na morfologia e no alto alinhamento de fibras de PCL obtidas por eletrofiação com coletor rotativo. Preparou-se solução de PCL contendo clorofórmio e acetona como solventes. As concentrações em massa de surfactantes utilizadas foram: 0,05; 0,1; 0,5; 1,0 e 1,5 wt%. As soluções foram caracterizadas através de medições de tensão superficial, condutividade elétrica e reologia. As morfologias das fibras foram analisadas com Microscópio Eletrônico de Varredura (MEV) juntamente com o software imageJ e o plugin OrientationJ. As fibras foram caracterizadas quanto às propriedades térmicas (DSC), análise química (FTIR) e molhabilidade (ângulo de contato). Através dos resultados obtidos, observou-se que a condutividade elétrica das soluções foi aumentada de acordo com o tipo de surfactante. A reologia foi alterada com os tipos e as concentrações, enquanto a tensão superficial não apresentou mudança significativa com a adição dos surfactantes. Os surfactantes CTAB e SDS alteraram o alinhamento das fibras de PCL e, dependendo da concentração, melhoraram a uniformidade dos diâmetros das fibras. Os surfactantes foram capazes de melhorar a molhabilidade das mantas, enquanto as propriedades térmicas foram mantidas / Abstract: The electrospinning is one of the main techniques to produce ultrafine polymeric fibers in the nano and submicron scale. Poly ('épsilon'-caprolactone) (PCL) is a biodegradable synthetic polymer widely used in the medical field. Electrospun PCL fibers form porous mats favorable for biomedical applications such as in tissue engineering. PCL aligned fibers are of interest since it expand the applications of these fibers and confer improvements in certain properties when compared with random fibers. PCL considered a moderately hydrophobic polymer and the electrospinning increases the hydrophobicity of the mats. Surfactants have the ability to modify the surface of polymeric fibers increasing its wettability. This work is concerned with the study of the effects of adding cationic (CTAB), anionic (SDS) and nonionic (Triton X-100) surfactants in the morphology and alignment PCL fibers obtained by electrospinning used a rotating collector. Poly ('épsilon'-caprolactone) (PCL) solutions with chloroform and acetone as solvent were prepared and different concentrations of surfactants were used: 0.05; 0.1; 0.5; 1.0; and 1,5 wt% in mass. Solutions characterized by measurements of surface tension, electric conductivity and viscosity. The morphology of the fibers analyzed by Scanning Electron Microscopy (SEM) together with the ImageJ software and OrientationJ plugin. The fibers characterized by differential scanning calorimetry (DSC), infrared spectroscopy (FTIR) and wettability (contact angle). Through the results obtained, the electrical conductivity of the solutions increased according to the type of surfactant. The rheology changed with the types and concentrations, while the surface tension did not change significantly with the addition of surfactants. The presence of surfactants CTAB and SDS influence the alignment of the PCL fibers, and depending on the concentration, improve the uniformity of fiber diameters. The surfactants were able to improve the wettability of mats, while the thermal properties maintained / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

This dissertation 1) described prevalence and correlates of poly-tobacco use among US youth and young adults; 2) addressed positive and negative transitions of e-cigarettes among US youth and adults and 3) examined the 2-year transition of dual e-cigarette/cigarette use among US adults in relation to nicotine dependence (ND) symptoms, interest in quitting, and cardiovascular disease (CVD) factors. Data from 2013-2016 of the Population Assessment of Tobacco and Health Study were used. In the first study, 3.6% of youth (12-17years) and 18.3% of young adults (18-34years) were current poly-tobacco users between 2013-2014. Common poly-tobacco products combination was cigarettes and e-cigarettes for youth and young adults. Among youth, heavy drinking was associated with higher odds of poly-tobacco use. Factors associated with higher odds of poly-tobacco use among young adults included males, younger adults (18-24years), those with lower levels of educational attainment, residing in the South, heavy drinking, and marijuana use. In the second study, between 2013-2016, e-cigarette use increased only in youth. Young e-cigarette users were more likely to be never cigarette smokers compared to older users. Among youth e-cigarette users at each wave, the proportion of never cigarette smokers rose from 24.1% in Wave 1 to 42.6% in Wave 3 (p=0.0001 for trends). Among adult e-cigarette dual users in Wave 1, 8.8% transitioned to no tobacco use at Wave 3, 6.2% to mono e-cigarette use, while 85% either relapsed to cigarettes (53.5%) or continued dual use (31.5%). In the final study, among 1,870 adult dual tobacco users from Wave 1, 25·8% (95% CI 23·5-28·3) remained dual users 2 years later, 11·9% (95% CI 10·5-13·5) reported no tobacco use (cessation transition), 7·0% (95% CI 5·5-8·7) reported e-cigarette mono use (harm reduction transition), and 55·3% (95% CI 52·6-58·0) reported cigarette mono use (relapse transition). In the adjusted regression analysis, ND severity was associated with lower odds of cessation (OR 0·36; 95% CI 0·15-0·88) and harm reduction (OR 0·18; 95% CI 0·04-0·82) transitions. Interest in quitting and CVD factors were not associated with cessation or harm reduction. Collectively, our study findings emphasize the need for stricter tobacco regulatory policies to prevent another tobacco epidemic.

This diploma thesis was focused on the preparation and characterization of biodegradable composites based on poly-3-hydroxybutyrate (PHB) and spent coffee grounds (SCG). The aim was to prepare biocomposites based on PHB and coffee grounds. Biocomposites were prepared by solution casting in chloroform. Films with a thickness of about 150-200 µm were prepared with the addition of 20% unmodified and modified coffee grounds. The PHB/SCG films were modified by an addition of a plasticizer and a crosslinking agent or by blending with polybutylene adipate terephthalate (PBAT). The thermal properties of the films were determined by differential scanning calorimetry. The compatibility filler/polymer matrix compatibility was assessed morphologically with the naked eye. It has been found that the direct addition of spent coffee grounds to the PHB is not suitable due to the deterioration of the morphology of the film surfaces and the formation of aggregates. The compatibility between the spent coffee grounds and the PHB was improved after the addition of the plasticizer and the crosslinking agent. However, the highest compatibility between SCG and PHB was achieved in the case of esterified coffee grounds. Another way to improve the resulting morphological properties of the films thus prepared was to use coffee grounds fractions.

This diploma thesis deals with the characterization of rheological properties and biodegradation of a poly(3-hydroxy-co-4-hydroxybutyrate), a copolymer produced by a strain of Cupriavidus malaysiensis. The theoretical part focuses on the rheology and degradation of polymers in general. It also contains the basic characteristics of polyhydroxyalkanoates and deals in more details with the description of the studied copolymer, its properties, synthesis, decomposition and possibilities of its applications. In the experimental part, the given copolymer was investigated in its native form and also in the form of copolymer mixtures filaments, which were enriched with additives (stabilizers and plasticizers). In terms of rheology, the samples showed pseudoplastic behaviour, which was slightly limited by the plasticization of the material. The highest thermal stability observed as a function of changes in complex viscosity over time was observed in a sample of a copolymer mixture containing stabilizers and plasticizer Citrofol BII. The plasticization also caused significant changes in thermal properties, especially crystallinity, which decreased compared to the native copolymer. In vitro degradation studies of samples in the form of films prepared by dissolving copolymer mixtures in chloroform were performed in phosphate buffer with lipase, in simulated body fluid and in synthetic gastric juice. The course of the process itself was characterized by the method of determining the molecular weight (SEC-MALLS) and the weight loss over time (gravimetrically). The results showed that the analysed samples are subject to degradation in all used environments. The most considerable molecular weight loss after 105 days (76 %) was observed in the sample containing stabilizers and plasticizer Citrofol BII in the environment of synthetic gastric juice. The most extensive gravimetric weight loss was attributed to the sample with stabilizers and without plasticizers, in the environment of phosphate buffer with lipase, specifically by 79%.

This thesis deals with modular robotics and self-reconfigurable robotic systems. At the beginning are systems defined and classified, the main emphasis is on Molecubes. After that, similar system is designed with a focus on the actual construction of the modules. In conclusion, several sample assemblies was made.

This research aimed to develop technology and processes to further beneficiate two southern African bentonites for applications in polymer/clay nanotechnology. The bentonites were from the Koppies mine in South Africa, and the Boane mine in Mozambique. The work was divided into two parts: (i) preparation of organomodified nanoparticulate smectite clays, and (ii) preparation of their poly(ethylene-co-vinylacetate) nanocomposites. Nanoparticulate organobentonites were prepared using purified bentonites. The conventional organomodification process uses a very low concentration of bentonites at 80 oC. In this study, a novel method was developed: concentrated slurries of naturally occurring Ca-bentonite partially activated with soda ash in the presence of a proprietary dispersant were contacted at ambient temperature with quaternary ammonium surfactants. A known amount of bentonite dispersion was placed in a planetary mixer before the mixture. Likewise, a known amount of surfactant, up to 50% excess, based on the estimated cation exchange capacity (CEC) of the bentonites, was added while mixing the dispersion. The surfactants added were either in solution or in powdered form. The intercalated bentonite was recovered by centrifugation and washed repeatedly with water until halide ions could not be detected using a 1M silver nitrate solution. The solids were dried at ambient temperature and humidity, and then crushed and milled into a fine powder using a mortar and pestle. Several instrumental techniques were used to characterise and examine the properties of the bentonite samples before and after organic treatment.The X-ray diffraction (XRD) results were consistent with: (i) paraffin-type extended chain intercalation; and (ii) interdigitated monolayer intercalation of the C12 and C14 single-chain alkyl surfactants and bilayer intercalation of the single-chain C16 surfactant and the surfactants with double alkyl chains. Fourier transform infrared (FTIR) spectroscopy analysis of the organobentonite powders confirmed disordered chain conformations. XRD also detected significant amounts of cristobalite in the samples of Boane bentonite (from Mozambique). This impurity could not be removed cost-effectively. The onset decomposition temperature ofthe present organobentonites was around 200 ºC, which is within the typical range of polymer/organoclay processing temperatures. The thermal stability of the organobentonites was independent of both the number of alkyl chain substituents and their length, and also independent of the degree of clay intercalation. SURFACTANT INTERCALATED KOPPIES AND BOANE BENTONITES FOR POLYMER NANOTECHNOLOGY ii Poly(ethylene-co-vinylacetate) nanocomposites were prepared with South African Koppies bentonite, organomodified with single-chain C12 (and polar 2-hydroxyethyl side chain) and double-chains C18 alkyl ammonium cationic surfactants. The later surfactant was intercalated both below and above the clay CEC. Nanocomposites were prepared by twin-screw melt compounding. Transmission electron microscopy (TEM) indicated the presence of mixed nanoand micron-sized clay morphologies. XRD studies revealed that the crystallinity of the particles improved and that the d-spacing values increased on incorporation of the modified bentonites in the polymer matrix. It is postulated that, rather than indicating polymer co-intercalation, this was caused by further intercalation of either excess surfactants or surfactant residues that were released by shear delamination of the clays during compounding. Improved mechanical properties were realised, especially when using the bentonite containing the longer double-chains surfactant intercalated at levels in excess of the CEC of the clay. The nanocomposites showed improved tensile modulus and elongation at break values at the expense of a reduction in impact strength, while tensile strength was about the same as for the neat polymer. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Chemistry / unrestricted

>Magister Scientiae - MSc / Peptides are among the main drugs which attract much attention because of their great potential in treating sexually transmitted diseases and other chronic diseases. There has been a major challenge of delivering these drugs in mucosal sites with low pH environment. The aim of this study is to synthesize acidic pH stable peptide loaded chitosan nanoparticles gels that could penetrate mucus layers covering the epithelial cells and kill HIV virus. Chitosan nanoparticles were synthesized by crosslinking method called Ionic gelation with Sodium tripolyphosphateTPP. / 2023

Diese Arbeit liefert die Grundlage für intelligente Beschichtungen aus kovalent gebundenen Polymeren, sogenannten Polymerbürsten, mit Schichtdicken von wenigen Nanometern. Durch ihre Fähigkeit die Oberflächeneigenschaften je nach Umgebungstemperatur, pH Wert und Zusammensetzung zu ändern, kann die Adsorption von Biomolekülen auf eine einzigartige Art und Weise kontrolliert und reguliert werden. Die zusätzliche Modifizierung der Polymerbürsten mit Elektronenstrahlen ermöglicht die Generierung von Gradienten und erweitert die Anwendungsmöglichkeiten in vielfältigen Bereichen der interdisziplinären Forschung, wie z.B. in Hinblick auf das Lab-on-Chip Design oder die Biomedizin. / Polymer brushes represent sensitive coatings with thicknesses of few nanometres and are interesting for interdisciplinary scientific research, e.g. for intelligent lab-on-chip design or biotechnology. It is demonstrated in this work, that polymer brushes are able to change their surface properties depending on the ambient conditions like solvent quality, temperature or pH value. This sensitivity highly influenced the adsorption of bio molecules. Especially mixed polymer brushes enabled the tuning of the adsorbed amount of various proteins and cells. To create surface gradients or structures in the different polymer brush surfaces, controlled electron beam modification was applied.

The regulation of gene expression is achieved at many levels. Chromatin-based gene regulation has been the central focus of many decades of research; however, posttranscriptional control mechanisms are emerging as a fundamental complement to direct protein synthesis. This thesis is focused on a specific mechanism of posttranscriptional control - the translational regulation of mRNAs in the cell cytoplasm. This control is a consequence of the balance between translational repression and activation and hinges on the selective recognition of regulated mRNAs by RNA-binding proteins and their ability to recruit RNA modifying proteins. In this thesis, Caenorhabditis elegans germline was used to study translational control of the germ cell-enriched gene, gld-2. Mutants of known RNA-binding proteins of the PUF and CPB protein families were analyzed by performing Western blots, using anti-GLD-2 antibodies. Yeast 3-Hybrid system was used to identify the cis-regulatory sites in the gld-2 mRNA conferring translational regulation by members of PUF and CPB protein families. Potential autoregulatory loop of gld-2 gene expression was also investigated. This thesis shows that FBF proteins positively regulate expression of gld-2 and bind to a conserved sequence in the 3'UTR of its mRNA. Mutations of gld-2 negatively affect...

Background: Patients with pre-existing vascular disease are known to have worse outcomes after acute myocardial infarction (AMI). However, there is limited data for outcomes stratified by type and number of vascular territories involved. Methods: Using the Nationwide Inpatient Sample (2015–2017), we examined outcomes of AMI in patients with pre-existent vascular disease stratified by number as well as types of diseased beds including all five major vascular sites: cardiac, cerebrovascular, renal, aortic and peripheral vascular disease (PVD). Multivariable logistic regression was used to determine the adjusted odds ratios (aOR) of adverse outcomes and invasive procedure utilization. Results: Out of 2,184,614 AMI admissions, 49.7% had pre-existent vascular disease. The odds of major adverse cardiovascular and cerebrovascular events (MACCE), mortality, ischemic stroke and major bleeding incrementally increased and was highest in those with ≥3 vascular sites involved (aOR for MACCE 1.16, CI 1.13–1.19; mortality 1.3, CI 1.26–1.34; stroke 1.15, CI 1.1–1.2; major bleeding 1.21, CI 1.16–1.25). Amongst those with a single pre-existent diseased vascular bed, the adjusted odds of MACCE appeared to be higher in those with PVD (1.28, CI 1.26–1.31), aortic disease (1.24, CI 1.19–1.29), and cerebrovascular disease (1.22, CI 1.2–1.25). Patients with pre-existent vascular disease had a lower overall likelihood of undergoing invasive revascularization procedures. Conclusions: Approximately half of the population presenting with AMI have pre-existent vascular disease. There is an incremental increase in adverse outcomes with increasing number of diseased vascular beds, with further differences in outcomes and utilization of invasive procedures based on sub-types of sites involved.