Inkjet is a digital printing process where the ink is ejected directly onto a substrate from a jet device driven by an electronic signal. Most inkjet inks have a low viscosity and a low surface tension, which put high demands on the coating layer’s porosity and absorbency characteristics. The aim of this study has been to gain an increased knowledge of the mechanisms that control the sorption and fixation of inkjet inks on coated papers. The focus has been on printability aspects of high print quality (although not photographic quality) laboratory-coated inkjet papers for printers using aqueous-based inks. Papers coated solely with polyvinyl alcohol (PVOH) and starch presented excellent gamut values and good print sharpness over the uncoated substrate, due to good film-forming characteristics observed by light microscopy and ESCA. ESEM analyses showed the complexity and variation of PVOH surface structures, which has probably explained the wide scatter in the colour-to-colour bleed results. Pure PVOH coatings also gave a surface with high gloss variations (2-8 times greater than that of commercial inkjet papers), prolonged ink drying time, and cracked prints when using pigmented inks. When an amorphous silica gel pigment (with broad pore size distribution) was used in combination with binder, a new structure was formed with large pores in and between the pigments and a macro-roughness generated by the large particles. The inkjet ink droplets could quickly penetrate into the large pores and the time for surface wicking was reduced, which was beneficial for the blurriness. However, the macro-roughness promoted bulk spreading in the coarse surface structure, and this tended to increase the line width. Finally, when the ink ends up within the coating, the colorant is partly shielded by the particles, and this reduced the gamut area to some extent. The binder demand of the silica pigments was strongly related to their pore size distributions. Silica gel required two to three times the amount of binder compared to novel surfactant-templated mesoporous silica pigments (with small pores and narrow pore size distribution). This finding was attributed to the significant penetration of PVOH binder into the pores in the silica gel, thereby, increasing its binder demand. Furthermore, this binder penetration reduced the effective internal pore volume available for rapid drainage of the ink vehicle. Consequently, the surfactant-templated pigments required significantly lower amounts of binder, and gave improvements in print quality relative to the commercial pigment.

Atherosclerosis is the number one cause of death in the United States and one of the most common treatments is the implantation of a stent. In order to eliminate the two most common complications - restenosis and thrombosis - a novel covered stent is investigated. A covered stent membrane should be able to undergo large stretch, prevent restenosis, and be relatively non-thrombogenic. Polyvinyl alcohol (PVA) cryogels are examined as a candidate material for covered stent membranes. Mechanical testing included uniaxial tensile testing, puncture testing, and the fabrication and expansion of PVA cryogel covered stents. Uniaxial testing showed PVA cryogels to have sufficient ultimate stretch which was similar to bare metal stents during deployment. Puncture testing revealed that PVA cryogels are not likely to puncture in vivo. No tears were seen in the PVA cryogel membrane after expansion of the covered stents. Finite element analysis was used to determine a PVA cryogel membrane's effect on artery wall stress. PVA cryogel covered stents reduced both artery wall stress and tissue prolapse when compared to equivalent uncovered stents. Migration assays were used to determine if PVA cryogels are able to block the smooth muscle cell migration seen during restenosis. PVA cryogels significantly reduced cellular migration in modified Boyden chambers - suggesting that they would be able to prevent restenosis in vivo. Thrombogenicity was tested in vitro with a gravity-fed flow loop using porcine blood and in vivo with a sheep model. PVA cryogels were found to be less thrombogenic than polyester controls with the flow loop system. The sheep study demonstrated the feasibility of implanting PVA cryogel covered stents and good early patency. After explantation, the PVA cryogel membranes were intact - providing in vivo evidence for the durability of PVA cryogel covered stents. Overall, this work provides evidence that covered stents made with PVA cryogels are a feasible device in terms of their mechanics, ability to prevent restenosis, and low thrombogenicity. This work represents a major advancement in the development of PVA cryogel covered stents and provides necessary safety and feasibility data for future clinical trials.

Cardiovascular disease is the leading cause of death in the United States with approximately 49% of the cardiovascular related deaths attributed to coronary heart disease (CHD). CHD is the accumulation of plaque resulting in the narrowing of the vessel lumen and a decrease in blood flow to the downstream heart muscle. In order to restore blood flow, arterial by-pass procedures can be undertaken. However, the patient's own arteries/veins may not be suitable for use as a vessel replacement, and synthetic grafts lack the compliancy and durability needed for these small diameter locations (<5 mm). Therefore, the goal of this research is to develop a nanofibrous material that can be used in vascular applications such as this. In this study, we fabricate coaxial electrospun nanofibers with gelatin in the shell and polyvinyl alcohol (PVA) in the core using 1 Gelatin: 1 PVA and 3 Gelatin: 1 PVA mass ratios. Gelatin, derived from collagen, is highly bioactive while PVA, a synthetic polymer, has appealing mechanical properties. Therefore, by combining these materials in a core-shell structure, we hypothesize that the resulting nanofibers will have enhanced mechanical properties, cellular growth and migration, as well as minimal platelet deposition and activation compared to scaffolds composed solely of gelatin or PVA. First, the coaxial scaffolds exhibited an enhanced Young's modulus and ultimate strength compared to scaffolds composed of PVA or gelatin alone. Endothelial cells had high proliferation and migration on the coaxial electrospun scaffolds with higher migration seen on the stiffer, coaxial scaffolds. The smooth muscle cells had less proliferation and lower migration rates on the coaxial scaffolds than the endothelial cells. Using a modified prothrombinase assay, the coaxial scaffolds had minimal platelet activation. Lastly, when pre-seeding the coaxial scaffolds with endothelial cells or smooth muscle cells, the platelet deposition decreased in comparison to platelet deposition with no cell pre-seeding. Overall, the 1 Gel: 1 PVA coaxial scaffolds promoted endothelial cell growth and migration, minimized smooth muscle cell growth and migration, and had minimal platelet activation. Therefore, the 1 Gel: 1 PVA coaxial nanofibers are an intriguing material for use in vascular applications.

No description available.

Polyvinyl alcohol (PVA) desize effluent is a high COD contributor to towel manufacturing plant's Primary Oxygenation Treatment of Water operation, and being non-biodegradable, is a threat to the environment. When all-PVA/wax size is used in weaving, significant incentives exist to recover the synthetic polymer material from the desize wash water stream and reuse it. A new technology that would eliminate the disadvantages of the current Reverse Osmosis Ultrafiltration (UF) PVA recovery process is Vacuum Flash Evaporation (VFE). This research adapts the VFE process to the recovery and reuse of all-PVA size emanating from towel manufacturing, and compares the economics of its implementation in a model plant to current plant systems that use PVA/starch blend sizes with no materials/water recovery. After bench scale research optimized the VFE PVA recovery process from the desize effluent and determined the mass of virgin PVA that was required to be added to the final, recycled PVA size formulations. The physical changes in the recycled size film and yarn composite properties from those of the initial (conventional) slashing were determined using a number of characterization techniques, including DSC, TGA, SEM, tensile testing, viscometry, number of abrasion cycles to first yarn breaks, microscopy and contact angle measurements. Cotton chemical impurities extracted from the yarns during desizing played an important role in the recovered PVA film physical properties. The recovered PVA improved the slashed yarn weave ability. Along with recovered PVA, pure hot water was recovered from the VFE. Virgin wax adds to the final, recycled size formulations were determined to be unnecessary, as the impurities extracted into the desize effluent stream performed the same functions in the size as the wax. Using the bench results, the overall VFE process was optimized and demonstrated to be technically viable through six cycles, proof-of-concept trials conducted on a Webtex Continuous Pilot Slasher. Based on the pilot scale trials, comparative economics were developed. Incorporation of the VFE technology for PVA size recovery and recycling resulted in ~$3.2M/year in savings over the conventional PVA/starch/wax process, yielding a raw ROI of less than one year based on a $3M turnkey capital investment.

No description available.

Orientadores: Vitor Baranauskas, William Dias Belangero / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-18T04:41:56Z (GMT). No. of bitstreams: 1 Rodrigues_AnaAmelia_D.pdf: 6206304 bytes, checksum: 977d7fa603d9906b66ff83abcb8b5466 (MD5) Previous issue date: 2011 / Resumo: O hidrogel de polivinil álcool puro e reforçado com duas diferentes nanopartículas de carbono, produzidas pelo método de deposição química a partir da fase vapor, foi avaliado por ensaios in vitro e in vivo, para verificar seu potencial de uso para tratamento de defeitos osteocondrais. A caracterização das nanopartículas foi feita por microscópio Raman, microscopia eletrônica por emissão de campo e microscopia eletrônica de alta transmissão. Foi avaliada a citotoxicidade dos materiais com células do Vero do tipo fibroblasto e células-tronco mesenquimais derivadas da medula óssea de ratos Wistar-kyoto por ensaios de viabilidade e análise citoquimica e a diferenciação osteogênica pela atividade da enzima fosfatase alcalina e corante vermelho de alizarina. Os materiais foram implantados por 3 e 12 semanas em defeitos osteocondrais de ratos Wistar e analisados por microscopia eletrônica de varredura, microscopia óptica, ensaio mecânico de indentação e espectrometria de fluorescência de raios X. Os resultados sugerem que os materiais não interferiram na viabilidade e morfologia de nenhum tipo celular. Foi identificada a atividade da enzima fosfatase alcalina e formação de matriz orgânica mineralizada. Após implante os materiais não apresentaram sinais de desgaste ou mudança de cor. A região de interface apresentou tecido conjuntivo denso e ósseo neoformado após 3 e 12 semanas. Foi observado aumento do módulo de fluência e maior concentração de cálcio nos materiais ao longo do tempo. Os resultados indicaram que os hidrogéis com nanopartículas de carbono não interferiram na atividade metabólica de ambas as células e na diferenciação osteogênica das células mesenquimais. O desempenho destes materiais pode ser considerado melhor que o hidrogel sem nanopartículas / Abstract: Poly(vinyl alcohol) hydrogel pure and reinforced with two different carbon nanoparticles, produced by hot-filament chemical vapor deposition method, was evaluated by in vitro and in vivo assays, to assess its potential employment for the treatment of osteochondral defects. Nanoparticles characterization was done by Raman microscope, field emission scanning electron microscopy and high-resolution transmission electron microscopy. It evaluated the cytotoxicity of the materials with Vero fibroblast-type cellular and mesenchymal stem cells derived from bone marrow of Wistar-Kyoto rats by assays of viability and citochemistry analyses and osteogenic differentiation by alkaline phosphatase activity and alizarin red staining. The materials were implanted by 3 and 12 weeks in the osteochondral defects of Wistar rats and analyzed by scanning electron microscopy, optical microscopy, creep indentation and X-ray fluorescence spectroscopy. The results suggest that the materials didn't interfere in the viability and morphology of any cell type. Alkaline phosphatase activity and nodules of mineralized organic matrix formation was identified. After implantation the materials did not showed signs of wear or color change. The interface region showed connective dense tissue and bone tissue neoformed after 3 and 12 weeks. It was observed increased of creep module and more concentration of calcium of samples over time. The results indicate that the hydrogels with carbon nanoparticles not interfere in metabolic activity of both cells and osteogenic mesenchymal differentiation. The performance of these materials can be considered better than the hydrogel without nanoparticles / Doutorado / Eletrônica, Microeletrônica e Optoeletrônica / Doutor em Engenharia Elétrica

The rheological behavior analysis of Engineered Cementitious Composites (ECC) is key to understand how the different preparation techniques affect the composite mechanical performance. However, the rheological assessment of reinforced materials becomes more complex since fibers usually cause flow disturbances not found in nonreinforced cementitious materials. Besides that, simple workability measurement techniques are not able to fully understand the composite behavior in the fresh state creating the need for more precise techniques to be employed. The main objectives of this study were to evaluate the ECC rheological behavior using different rheometer devices (Vane system and Ball measuring system) and investigate the influence of mixing processes on the fiber homogenization and rheological behavior. Additionally to this, a link between rheological behavior and mechanical performance was investigated. In the end, the ball measuring system revealed to be more efficient than the vane system when evaluating the composite rheological behavior. In addition, the mixing process influenced the rheological behavior of PVA-ECC especially regarding the moment which fibers are added. Fiber addition after mortar mixture improved fibers homogenization and reduced mixing energy by around 8%. Moreover, a correlation between rheological and mechanical properties showed that a 2-times variation in either yield stress or viscosity can lead to a variation of more than 50% in flexural strength without significantly affecting the composite compressive strength. It was also found that the lower the composite yield stress and viscosity the higher was its ultimate strain. To conclude, all those parameters contributed to understand the composite rheological behavior and globally optimize its performance. / Sem resumo

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2018-10-31T18:19:56Z No. of bitstreams: 1 Larissa_Bortoli_2017.pdf: 2081912 bytes, checksum: 9d603950fbde6861b979910220779d8b (MD5) / Made available in DSpace on 2018-10-31T18:19:56Z (GMT). No. of bitstreams: 1 Larissa_Bortoli_2017.pdf: 2081912 bytes, checksum: 9d603950fbde6861b979910220779d8b (MD5) Previous issue date: 2017-03-13 / Recent studies have shown that silver nanoparticles (AgNPs) can bring potential health and environmental risks. Its growing production on large scale and wide incorporation into several products increases the risks of this nanomaterial of reaching different ecosystems, impacting the environment and human health. Facing this panorama, this work has as main objective, evaluating the efficiency of the treatment by electrocoagulation of different synthetic industrial effluents of AgNPs. Therefore, distinct AgNPs dispersions were developed in aqueous medium by chemical reduction, using silver nitrate (AgNO3) as a precursor, sodium borohydride (NaBH4) as a reducer, and stabilizers in concentrations of 1 and 3% (m/v), sodium carboxymethylcellulose (CMC), polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), resulting in dispersions designated as AgNPs-CMC1 and AgNPs-CMC3, AgNPs-PVA1 and AgNPs-PVA3 and AgNPs-PVP1 and AgNPs-PVP3, respectively. Synthesized, the nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscopy (TEM), pH, conductivity and turbidity. The UV-Vis absorption spectra of the AgNPs obtained by different synthesis reactions were similar, presenting bands in the 400 nm region, typical of spherical-shaped AgNPs. The predominantly spherical morphological appearance of the AgNPs of the different dispersions was confirmed by transmission electron microscopy. In the treatment by electrocoagulation with aluminum electrodes, the dispersions containing CMC as a stabilizing agent proved to be difficult to treat by electrocoagulation. The dispersions AgNPs-CMC1 and AgNPs-CMC3 obtained a reduction in total silver concentration of 71.72 and 52.15%, respectively, after 15 min of electrolysis. While the dispersions AgNPs-PVA1, AgNPs-PVP1 and AgNPs-PVP3 obtained a reduction in total silver concentration above 99.90% in 10 minutes of treatment, and AgNPs-PVP3 route dispersion reduction of total silver of 99.98% at 20 min of electrocoagulation. From these results, it was possible to observe that the elimination of AgNPs from effluents is possible and that the efficiency of the treatment by electrocoagulation is directly related to the physicochemical characteristics acquired by the dispersions of AgNPs when stabilized with different compounds. Finally, through the toxicity analysis with the test organism Vibrio fischeri, and according to the IAP Ordinance No. 019/2006, it was possible to verify that only the dispersions that used PVP as a protective agent became suitable for disposal after treatment by electrocoagulation. / Estudos recentes têm demonstrado que nanopartículas de prata (AgNPs) podem trazer riscos potenciais a saúde e ao meio ambiente. A crescente produção em escala industrial e ampla incorporação em diversos produtos aumentam os riscos desse nanomaterial alcançar os diferentes ecossistemas e, assim, causar impactos nesses ambientes e na saúde humana. Diante deste panorama, este trabalho teve como objetivo principal avaliar a eficiência do tratamento por eletrocoagulação de diferentes efluentes industriais sintéticos de AgNPs. Para isto, sintetizou-se distintas dispersões de AgNPs em meio aquoso por redução química, utilizando nitrato de prata (AgNO3) como precursor, borohidreto de sódio (NaBH4) como redutor, e os estabilizantes nas concentrações 1 e 3%, carboximetilcelulose sódica (CMC), álcool polivinílico (PVA) e polivinilpirrolidona (PVP), resultando nas dispersões denominadas AgNPs-CMC1 e AgNPs-CMC3, AgNPs-PVA1 e AgNPs-PVA3 e AgNPs-PVP1 e AgNPs-PVP3, respectivamente. Sintetizadas, as nanopartículas foram caracterizadas por espectroscopia UV-Vis, microscopia eletrônica de transmissão (MET), conversão reacional, pH, condutividade e turbidez. Os espectros de absorção UV-Vis das AgNPs obtidas pelas diferentes reações de síntese foram similares, apresentando bandas na região de 400 nm, característico de AgNPs com formato esférico. A aparência morfológica predominantemente esférica das AgNPs das diferentes dispersões foi confirmada pela microscopia eletrônica de transmissão. No tratamento por eletrocoagulação com eletrodos de alumínio as dispersões contendo CMC como agente estabilizante se demonstraram dificilmente tratáveis por eletrocoagulação. Após 15 min de eletrólise a dispersão AgNPs-CMC1 apresentou uma redução de 71,72% na concentração de prata total e a dispersão AgNPs-CMC3 52,15%. As dispersões AgNPs-PVA1, AgNPs-PVP1 e AgNPs-PVP3 obtiveram redução na concentração de prata total acima de 99,90% em 10 min de tratamento, e a dispersão AgNPs-PVP3 redução de prata total de 99,98% aos 20 min de eletrocoagulação. Destes resultados foi possível observar que a eliminação de AgNPs de efluentes é possível, e que a eficiência do tratamento por eletrocoagulação se relaciona diretamente com às características físico-químicas adquiridas pelas suspensões de AgNPs quando estabilizadas com diferentes compostos. Por fim, através das análises de toxicidade com o organismo- teste Vibrio fischeri, e de acordo com a Portaria IAP n° 019/2006 foi possível constatar que somente as dispersões que utilizaram PVP como agente protetor se tornaram aptas ao descarte após tratamento por eletrocoagulação.

Orientador: Orlando Petrucci Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-11T21:17:28Z (GMT). No. of bitstreams: 1 Oliveira_PedroPauloMartinsde_D.pdf: 3207291 bytes, checksum: 643cd7870725684beed7998d60351274 (MD5) Previous issue date: 2008 / Resumo: Introdução: Reoperações representam cerca de 20% das cirurgias cardíacas, quase na totalidade com esternotomia, onde há a formação de aderências entre o coração, esterno e estruturas adjacentes. Lesões das câmaras cardíacas e grandes vasos pela serra esternal ou na dissecção dessas estruturas resultam em aumento da morbimortalidade e do sangramento perioperatório. Vários autores propuseram o uso de substitutos pericárdicos biológicos e sintéticos na tentativa de diminuir o risco de acidentes nas reoperações, porém sem resultados consistentes em longo prazo. A membrana de poli (álcool vinílico) - PVAl reticulado formam um hidrogel bastante estudado como biomaterial, com boa biocompatibilidade e características favoráveis ao seu emprego como substituto pericárdico. Objetivo: Caracterizar a membrana de PVAl quanto à capacidade de absorção de água, calcificação e citotoxidade e estudar o comportamento biológico da mesma como substituto pericárdico. Metodologia: Foram utilizadas amostras da membrana de PVAl reticulada por irradiação e realizados ensaios de citotoxicidade em culturas de células VERO, da capacidade de absorção de água e de calcificação após o implante in vivo. Ratos da Raça Wistar foram divididos em quatro grupos: Grupo controle - pericardiotomia. Grupo Talco - colocação de talco sobre o epicárdio. Grupo PVAl - colocada membrana de PVAl circundando o coração. Grupo PVAl + Talco - colocado talco sobre o epicárdio e a membrana de PVAl circundando o coração. Após oito semanas foi realizada análise macroscópica e histológica dos corações. Avaliação estatística foi realizada com análise de variância (ANOVA) e teste de Dunnett com significância p<0,05. Resultados: A membrana de PVAl não apresentou citotoxicidade, sua capacidade de absorção de água foi de 42,4 ± 0,89% e mostrou valor médio de 0,00422± 0,00256% de cálcio da massa total do material analisado. Na análise macroscópica observou-se maior aderência no grupo Talco. Na análise histológica o grupo PVAl + Talco apresentou maior espessura epicárdica. Os grupos T e PVAl + Talco apresentaram maior número de células inflamatórias. Conclusão: A membrana não é citotóxica, apresentou boa capacidade de hidratação, a absorção de cálcio foi desprezível, não induziu formação de aderências pericárdicas, não provocou aumento da espessura epicárdica e não induziu aumento de migração de células de resposta inflamatória para o epicárdio, mostrando-se interessante para a aplicação desejada. / Abstract: Background: Cardiac surgery reoperations represent around 20% of all surgical procedures. The main incision is sternotomy and after the first operation there are adherences joining the heart, sternum and neighboring structures. Cardiac chambers and great vessels lesions caused by sternal saw increase morbidity and mortality as well as perioperatory bleeding. Several authors had tried pericardial replacement with biological or synthetic materials in order to decrease risks at reoperations, however with no significant results on long term. Polyvinyl alcohol (PVAl) is a well-known hydrogel, with good biocompatibility and favorable properties as a pericardium replacement. Objective: Describe the biological PVAl behavior as a pericardial replacement. Methodology: PVAl samples were reticulated by radiation. Cytotoxicity direct and indirect tests with VERO cells were performed. We tested absorption water capability and in vivo calcification. Wistar rats were divided in four groups: Control - pericardium abrasion; Talc - talc insertion surrounding the heart; PVAl membrane - PVAl surrounding the heart; PVAl + talc - talc and PVAl membrane insertion surrounding the heart. All animals were kept for 8 weeks and euthanized for study. Macroscopic and microscopic analyses were performed. Statistical analyses were performed with ANOVA and Dunnett post test. Results: The PVAl membrane showed no cytotoxicity. The water absorption capability was 42,4 ± 0,89%. The calcification test showed only 0.00422± 0.00256% of calcium in the total mass of analyzed material. Macroscopic analysis showed higher adherences in the talc group. Histological analysis showed higher epicardium thickness in the PVAl + talc group, higher inflammatory cells in the talcum and PVAl + talc groups. Conclusion: The PVAl membrane hasn't cytotoxicity. It has good water absorption capability and calcification was insubstantial. The membrane showed neither adherences formation nor inflammatory response ...Note: The complete abstract is available with the full electronic digital thesis or dissertations. / Doutorado / Pesquisa Experimental / Doutor em Cirurgia