Hybrid materials for biomedical applications

The increased longevity of humans and the demand for a better quality of life have led to a continuous search for new implant materials. Scientific development coupled with a growing multidisciplinarity between materials science and life sciences has given rise to new approaches such as regenerative medicine and tissue engineering. The search for a material with mechanical properties close to those of human bone produced a new family of hybrid materials that take advantage of the synergy between inorganic silica (SiO4) domains, based on sol-gel bioactive glass compositions, and organic polydimethylsiloxane, PDMS ((CH3)2.SiO2)n, domains. Several studies have shown that hybrid materials based on the system PDMS-SiO2 constitute a promising group of biomaterials with several potential applications from bone tissue regeneration to brain tissue recovery, passing by bioactive coatings and drug delivery systems. The objective of the present work was to prepare hybrid materials for biomedical applications based on the PDMS-SiO2 system and to achieve a better understanding of the relationship among the sol-gel processing conditions, the chemical structures, the microstructure and the macroscopic properties. For that, different characterization techniques were used: Fourier transform infrared spectrometry, liquid and solid state nuclear magnetic resonance techniques, X-ray diffraction, small-angle X-ray scattering, smallangle neutron scattering, surface area analysis by Brunauer–Emmett–Teller method, scanning electron microscopy and transmission electron microscopy. Surface roughness and wettability were analyzed by 3D optical profilometry and by contact angle measurements respectively. Bioactivity was evaluated in vitro by immersion of the materials in Kokubos’s simulated body fluid and posterior surface analysis by different techniques as well as supernatant liquid analysis by inductively coupled plasma spectroscopy. Biocompatibility was assessed using MG63 osteoblastic cells. PDMS-SiO2-CaO materials were first prepared using nitrate as a calcium source. To avoid the presence of nitrate residues in the final product due to its potential toxicity, a heat-treatment step (above 400 °C) is required. In order to enhance the thermal stability of the materials subjected to high temperatures titanium was added to the hybrid system, and a material containing calcium, with no traces of nitrate and the preservation of a significant amount of methyl groups was successfully obtained. The difficulty in eliminating all nitrates from bulk PDMS-SiO2-CaO samples obtained by sol-gel synthesis and subsequent heat-treatment created a new goal which was the search for alternative sources of calcium. New calcium sources were evaluated in order to substitute the nitrate and calcium acetate was chosen due to its good solubility in water. Preparation solgel protocols were tested and homogeneous monolithic samples were obtained. Besides their ability to improve the bioactivity, titanium and zirconium influence the structural and microstructural features of the SiO2-TiO2 and SiO2-ZrO2 binary systems, and also of the PDMS-TiO2 and PDMS-ZrO2 systems. Detailed studies with different sol-gel conditions allowed the understanding of the roles of titanium and zirconium as additives in the PDMS-SiO2 system. It was concluded that titanium and zirconium influence the kinetics of the sol-gel process due to their different alkoxide reactivity leading to hybrid xerogels with dissimilar characteristics and morphologies. Titanium isopropoxide, less reactive than zirconium propoxide, was chosen as source of titanium, used as an additive to the system PDMS-SiO2-CaO. Two different sol-gel preparation routes were followed, using the same base composition and calcium acetate as calcium source. Different microstructures with high hydrophobicit were obtained and both proved to be biocompatible after tested with MG63 osteoblastic cells. Finally, the role of strontium (typically known in bioglasses to promote bone formation and reduce bone resorption) was studied in the PDMS-SiO2-CaOTiO2 hybrid system. A biocompatible material, tested with MG63 osteoblastic cells, was obtained with the ability to release strontium within the values reported as suitable for bone tissue regeneration.

Transformada wavelet aplicada a análise automática de oscilografias de curta duração em unidades geradoras

The focus of this work is the automatic analysis of disturbance records for electrical power generating units. The main proposition is a method based on wavelet transform applied to short-term disturbance records (waveform records). The goal of the method is to detect the time instants of recorded disturbances and extract meaningful information that characterize the faults. The result is a set of representative information of the monitored signals in power generators. This information can be further classified by an expert system (or other classification method) in order to classify the faults and other abnormal operating conditions. The large amount of data produced by digital fault recorders during faults justify the research of methods to assist the analysts in their task of analysing the disturbances. The literature review pointed out the state of the art and possible applications for oscillography records. The review of the COMTRADE standard and wavelet transform underlines the choice of the method for solving the problem. The conducted tests lead to the determination of the best mother wavelet for the segmentation process. The application of the proposed method to five case studies with real oscillographic records confirmed the accuracy and efficiency of the proposed scheme. With this research, the post-operation analysis of occurrences is improved and as a direct result is the reduction of the time that generators are offline.

Espectroscopia no infravermelho e método quimiométrico para a pesquisa de antimicrobianos em leite da microrregião de Pato Branco - PR

Considering the social and economic importance that the milk has, the objective of this study was to evaluate the incidence and quantifying antimicrobial residues in the food. The samples were collected in dairy industry of southwestern Paraná state and thus they were able to cover all ten municipalities in the region of Pato Branco. The work focused on the development of appropriate models for the identification and quantification of analytes: tetracycline, sulfamethazine, sulfadimethoxine, chloramphenicol and ampicillin, all antimicrobials with health interest. For the calibration procedure and validation of the models was used the Infrared Spectroscopy Fourier Transform associated with chemometric method based on Partial Least Squares regression (PLS - Partial Least Squares). To prepare a work solution antimicrobials, the five analytes of interest were used in increasing doses, namely tetracycline from 0 to 0.60 ppm, sulfamethazine 0 to 0.12 ppm, sulfadimethoxine 0 to 2.40 ppm chloramphenicol 0 1.20 ppm and ampicillin 0 to 1.80 ppm to perform the work with the interest in multiresidues analysis. The performance of the models constructed was evaluated through the figures of merit: mean square error of calibration and cross-validation, correlation coefficients and offset performance ratio. For the purposes of applicability in this work, it is considered that the models generated for Tetracycline, Sulfadimethoxine and Chloramphenicol were considered viable, with the greatest predictive power and efficiency, then were employed to evaluate the quality of raw milk from the region of Pato Branco . Among the analyzed samples by NIR, 70% were in conformity with sanitary legislation, and 5% of these samples had concentrations below the Maximum Residue permitted, and is also satisfactory. However 30% of the sample set showed unsatisfactory results when evaluating the contamination with antimicrobials residues, which is non conformity related to the presence of antimicrobial unauthorized use or concentrations above the permitted limits. With the development of this work can be said that laboratory tests in the food area, using infrared spectroscopy with multivariate calibration was also good, fast in analysis, reduced costs and with minimum generation of laboratory waste. Thus, the alternative method proposed meets the quality concerns and desired efficiency by industrial sectors and society in general.

Estudo da intercalação de fontes de potássio em caulinita pura, com tratamento térmico e ativação ácida

The chemical changes in clay minerals has been widely studied in order to improve its properties for use in various applications. However kaolinite has strong hydrogen bonds between their adjacent layers hindering the process changes in its structure. With the objective to facilitate the process of intercalation monobasic potassium phosphate, bibasic potassium phosphate and potassium acetate we was performed on kaolinite heat treatment at 600 °C and activated acidic with phosphoric acid and 5 to 10 mol L-1. The samples they were characterized by energy dispersive spectroscopy (EDS), X-Ray Diffraction (XRD), Infrared Spectroscopy Fourier Transform (FTIR) and Thermogravimetric Analysis (TG) and Differential Thermal Analysis (DTG) and the superficial and textural changes the samples with heat treatment and acid activation they were characterized by scanning electron microscopy (SEM) and Textural Analysis of Adsorption/desorption N2. With the help of the techniques found that, the heat treatment becomes more susceptible to acid activation kaolinite making the samples with two treatments show larger amounts of phosphorus. It was also found that bibasic potassium phosphate binds more strongly the structure of kaolinite by having a structure with two-coordinating oxygens and intercalation with potassium acetate in acid-activated kaolin increases the interlayer distance of the kaolinite and the intercalation occurs with higher response index (RI) for samples with acid activation to 5 mol /L.

Estudo da influência da morfologia de nanopartículas de sílica mesoporosa na liberação do anticancerígeno indol-3-carbinol

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Ceilândia, Programa de Pós-graduação em Ciências e Tecnologias em Saúde, 2015.

Desenvolvimento de um biossensor para monitorização de acetilcolina, um biomarcador associado à Doença de Alzheimer

A presente dissertação teve como objetivo o desenvolvimento e caracterização de sensores potenciométricos com base em polímeros de impressão molecular (MIP, do inglês, Molecularly Imprinted Polymer) para a determinação da molécula alvo, a acetilcolina. A acetilcolina (ACh) é um neurotransmissor que está associado à doença de Alzheimer. Os materiais biomiméticos desenvolvidos para a interação com a ACh foram obtidos por polimerização em bulk, recorrendo a uma combinação de nanotubos de carbono com monómeros de anilina, dispersos em solvente plastificante oNFOE e PVC. Para aferir sobre o efeito da impressão de ACh na resposta dos materiais MIP, foram igualmente preparados e avaliados materiais de controlo, ou seja, materiais sem impressão molecular (NIP). O controlo da constituição química destes materiais foi realizado recorrendo a Espectroscopia de Raman e Espectroscopia de Infravermelho com transformada de Fourier (FTIR, do inglês Fourier Transformed Infrared Spectroscopy). Os materiais desenvolvidos foram integrados em membranas seletivas de ião, preparadas com ou sem aditivo iónico lipófilo, de carga negativa ou positiva. A avaliação das características gerais das membranas baseou-se na comparação das caraterísticas dos diversos elétrodos. Estas caraterísticas foram obtidas a partir de curvas de calibração, conseguidas para valores de pH diferentes. Em meio ácido, mais precisamente para pH 4, as membranas com materiais impressos e aditivo aniónico foram as que apresentaram as melhores características analíticas, quer em termos de sensibilidade (+83,86 mV década-1) quer em gama de linearidade (de 3,52×10-5 a 1,73×10-3 M). O estudo de seletividade realizado aos sensores revelou que os elétrodos cuja membrana possuía aditivo aniónico apresentavam menores valores de log KPOT. A presença desse constituinte fez com que a seletividade aumentasse nesses mesmos elétrodos. A espécie menos interferente foi a creatina e a mais interferente a creatinina. Os elétrodos foram, ainda, aplicados em amostras de soro sintético. A qualidade dos resultados obtidos dependeu do nível de concentração em estudo, sendo possível identificar uma região onde os resultados foram exatos e precisos. De uma forma geral, os biossensores com MIP e aditivo aniónico apresentaram um desempenho adequado à prossecução deste estudo em amostras reais.

FTIR, a potential tool to dementia diagnosis trough analysis of plasma

Nowadays it is still difficult to perform an early and accurate diagnosis of dementia, therefore many research focus on the finding of new dementia biomarkers that can aid in that purpose. So scientists try to find a noninvasive, rapid, and relatively inexpensive procedures for early diagnosis purpose. Several studies demonstrated that the utilization of spectroscopic techniques, such as Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy could be an useful and accurate procedure to diagnose dementia. As several biochemical mechanisms related to neurodegeneration and dementia can lead to changes in plasma components and others peripheral body fluids, blood-based samples and spectroscopic analyses can be used as a more simple and less invasive technique. This work is intended to confirm some of the hypotheses of previous studies in which FTIR was used in the study of plasma samples of possible patient with AD and respective controls and verify the reproducibility of this spectroscopic technique in the analysis of such samples. Through the spectroscopic analysis combined with multivariate analysis it is possible to discriminate controls and demented samples and identify key spectroscopic differences between these two groups of samples which allows the identification of metabolites altered in this disease. It can be concluded that there are three spectral regions, 3500-2700 cm -1, 1800-1400 cm-1 and 1200-900 cm-1 where it can be extracted relevant spectroscopic information. In the first region, the main conclusion that is possible to take is that there is an unbalance between the content of saturated and unsaturated lipids. In the 1800-1400 cm-1 region it is possible to see the presence of protein aggregates and the change in protein conformation for highly stable parallel β-sheet. The last region showed the presence of products of lipid peroxidation related to impairment of membranes, and nucleic acids oxidative damage. FTIR technique and the information gathered in this work can be used in the construction of classification models that may be used for the diagnosis of cognitive dysfunction.

A influência da incorporação de ácido α-eleosteárico, purificado e isolado do óleo de tungue, na dinâmica molecular de lipossomos

Este trabalho descreve o isolamento e purificação do ácido α-eleosteárico (α-ESA) a partir do óleo de tungue e sua caracterização por espectroscopia de infravermelho com transformada de Fourier (FTIR), cromatografia gasosa acoplada com espectrometria de massas (GC-MS) e espectroscopia de ressonância magnética nuclear (RMN) de 1H e 13C. O α-ESA apresenta atividades biológicas (antitumorais, anti-inflamatórias e antioxidantes), tornando-se importante compreender sua interação com membranas lipídicas. Assim, este trabalho também descreve resultados referentes ao efeito da incorporação de α-ESA na dinâmica molecular de lipossomos compostos por fosfatidilcolina. O sistema lipossomal puro e contendo α-ESA foi caracterizado através do uso de espectroscopia de UV-visível, FTIR, RMN e calorimetria de varredura diferencial (DSC). Como resultados da purificação do α-ESA, obtivemos uma pureza de 95,9% utilizando acetona como solvente de recristalização em detrimento dos 92,2% em solução etanólica. Na incorporação em lipossomos, observou-se uma maior interação do α-ESA com a parte polar, de interface e os primeiros metilenos da região apolar da fosfatidilcolina. Além disso, α-ESA apresentou um efeito de redução da fluidez de lipossomos. Os resultados contribuem para a geração de conhecimento para o desenvolvimento de novos sistemas farmacológicos.

webQDA: manual de utilização rápida

A investigação nas ciências humanas e sociais em geral e em educação de forma particular tem passado por muitas transformações ao longo das últimas décadas. Como todos os ramos das ciências, estas também influenciaram e foram influenciadas pelos desenvolvimentos específicos da área e das tecnologias. Há mais de 30 anos que aplicações informáticas ajudam os utilizadores a fazerem análise qualitativa de dados não-numéricos e não-estruturados, apresentando aos utilizadores resultados em forma de matrizes numéricas, trianguladas, com discurso descritivo de cariz qualitativo, que os apoia nas suas interpretações (Neri de Souza, Costa, & Moreira, 2010). O webQDA é um software de análise de texto, vídeo, áudio e imagem que funciona num ambiente colaborativo e distribuído com base na internet. O webQDA procura suprir essa necessidade, principalmente porque os projetos de investigação são cada vez mais desenvolvidos no âmbito multidisciplinar e com o envolvimento de utilizadores dispersos geograficamente. Também supre a lacuna de muitos programas que “obrigam” o(a) utilizador(a) a esperar que o(a) colega desenvolva a “sua parte do projeto”, para que lhe seja enviado o ficheiro e somente então poder inserir a sua contribuição, processo que se poderá perder num trabalho realmente colaborativo. (...)

Alteration of the bone tissue material properties in type 1 diabetes mellitus: A Fourier transform infrared microspectroscopy study

International audience

Detección de antígenos de Helicobacter pylori por el método de prueba rápida en estudiantes de Bachillerato Técnico Vocacional Atención Primaria en Salud del Instituto Nacional de Usulután, municipio y departamento de Usulután

Helicobacter pylori es una bacteria gram negativa capaz de sobrevivir a la acidez gástrica provocando gastritis crónica, úlcera péptica y cáncer gástrico; las técnicas empleadas para la detección de esta bacteria se dividen en invasivas y no invasivas que brindan un diagnóstico confiable a la población en estudio. OBJETIVO: Detectar la presencia de antígenos de Helicobacter pylori por el método de prueba rápida inmunocromatográfica en heces en los estudiantes de Bachillerato Técnico Vocacional Atención Primaria en Salud del Instituto Nacional de Usulután. METODOLOGÍA: El estudio fue: prospectivo, transversal, descriptivo y de laboratorio; la información de la población en estudio se dio a conocer por medio de una cédula de entrevista; la población en estudio estuvo conformada por 167 alumnos que cursan Bachillerato Técnico Vocacional Atención Primaria en Salud del Instituto Nacional de Usulután tanto en jóvenes que presentaron sintomatología como los que no la presentaron, se le tomó una muestra de heces para la detección de antígenos de Helicobacter pylori. RESULTADO: 66 estudiantes de Bachillerato Técnico Vocacional Atención Primaria en Salud del Instituto Nacional de Usulután presentaron pruebas positivas a antígenos de Helicobacter pylori en muestras fecales y 101 resultaron negativos a la prueba. CONCLUSIÓN: la positividad a antígenos de Helicobacter pylory 39.5%, el síntoma más frecuente en los estudiantes fue reflujo gástrico con 63.2%.

Nonuniform Depth Distribution Selection with Discrete Fourier Transform

info:eu-repo/semantics/inPress

Modelagem da propagação sonora em dutos : abordagem matemática no domínio da frequência e do tempo utilizando transformada de laplace

Dissertação (mestrado)—Universidade de Brasília, Faculdade UnB Gama, Faculdade de Tecnologia, Programa de Pós-graduação em Integridade de Materiais da Engenharia, 2016.

Ecuaciones diferenciales

El libro consta de 8 capítulos, en el capítulo 1 se hace una reseña histórica de las ecuaciones diferenciales y se dan algunas generalidades de estas incluyendo la existencia de la solución de una ecuación diferencial. En los capítulos 2, 3, y 4 se hace un estudio de las ecuaciones diferenciales de primer orden y de ecuaciones de orden superior, que con una transformación se pueden solucionar como ecuaciones diferenciales de primer orden, y se dan aplicaciones varias de estas ecuaciones. En los capítulos 5 y 6 se estudian las ecuaciones diferenciales de orden superior incluyendo algunas ecuaciones no lineales y se dan algunas aplicaciones de estas. El capítulo 7 está dedicado a la transformada de Laplace y el capítulo 8 a series de Fourier y una introducción a las ecuaciones diferenciales parciales.