Biofunctionalization of titanium surfaces for dental implants: osteogenic, anti-microbial and tribocorrosion resistant surfaces

PhD thesis in Biomedical Engineering

Grafting of adipic anhydride to carbon nanotubes through a Diels-Alder cycloaddition/oxidation cascade reaction

Accepted Manuscript

Improving selective collection of urban waste using a business intelligence system

Today recovering urban waste requires effective management services, which usually imply sophisticated monitoring and analysis mechanisms. This is essential for the smooth running of the entire recycling process as well as for planning and control urban waste recovering. In this paper we present a business intelligence system especially designed and im- plemented to support regular decision-making tasks on urban waste management processes. The system provides a set of domain-oriented analytical tools for studying and characterizing poten- tial scenarios of collection processes of urban waste, as well as for supporting waste manage- ment in urban areas, allowing for the organization and optimization of collection services. In or- der to clarify the way the system was developed and the how it operates, particularly in process visualization and data analysis, we also present the organization model of the system, the ser- vices it disposes, and the interface platforms for exploring data.

Multi-temporal analysis of radiometric changes in satellite images of forest edges to infer selective-logging areas in the Amazon forest

Radiometric changes observed in multi-temporal optical satellite images have an important role in efforts to characterize selective-logging areas. The aim of this study was to analyze the multi-temporal behavior of spectral-mixture responses in satellite images in simulated selective-logging areas in the Amazon forest, considering red/near-infrared spectral relationships. Forest edges were used to infer the selective-logging infrastructure using differently oriented edges in the transition between forest and deforested areas in satellite images. TM/Landsat-5 images acquired at three dates with different solar-illumination geometries were used in this analysis. The method assumed that the radiometric responses between forest with selective-logging effects and forest edges in contact with recent clear-cuts are related. The spatial frequency attributes of red/near infrared bands for edge areas were analyzed. Analysis of dispersion diagrams showed two groups of pixels that represent selective-logging areas. The attributes for size and radiometric distance representing these two groups were related to solar-elevation angle. The results suggest that detection of timber exploitation areas is limited because of the complexity of the selective-logging radiometric response. Thus, the accuracy of detecting selective logging can be influenced by the solar-elevation angle at the time of image acquisition. We conclude that images with lower solar-elevation angles are less reliable for delineation of selecting logging.

Extensive admixture and selective pressure across the Sahel Belt

Genome-wide studies of African populations have the potential to reveal powerful insights into the evolution of our species, as these diverse populations have been exposed to intense selective pressures imposed by infectious diseases, diet, and environmental factors. Within Africa, the Sahel Belt extensively overlaps the geographical center of several endemic infections such as malaria, trypanosomiasis, meningitis, and hemorrhagic fevers. We screened 2.5 million single nucleotide polymorphisms in 161 individuals from 13 Sahelian populations, which together with published data cover Western, Central, and Eastern Sahel, and include both nomadic and sedentary groups. We confirmed the role of this Belt as a main corridor for human migrations across the continent. Strong admixture was observed in both Central and Eastern Sahelian populations, with North Africans and Near Eastern/Arabians, respectively, but it was inexistent in Western Sahelian populations. Genome-wide local ancestry inference in admixed Sahelian populations revealed several candidate regions that were significantly enriched for non-autochthonous haplotypes, and many showed to be under positive selection. The DARC gene region in Arabs and Nubians was enriched for African ancestry, whereas the RAB3GAP1/LCT/MCM6 region in Oromo, the TAS2R gene family in Fulani, and the ALMS1/NAT8 in Turkana and Samburu were enriched for non-African ancestry. Signals of positive selection varied in terms of geographic amplitude. Some genomic regions were selected across the Belt, the most striking example being the malaria-related DARC gene. Others were Western-specific (oxytocin, calcium, and heart pathways), Eastern-specific (lipid pathways), or even population-restricted (TAS2R genes in Fulani, which may reflect sexual selection).

Selective serotonin-reuptake inhibitor and norepinephrine dopamine reuptake inhibitor antidepressants do not affect natural killer cell activity in vitro

OBJECTIVE: This study aims to evaluate the citotoxic activity of two commonly used anti-depressants: paroxetine and bupropion. We also evaluated the in vitro natural killer activity (NKA) after incubating the blood samples with the antidepressants. METHODS: Peripheral blood samples from 15 healthy volunteers were collected and the mononuclear cells (PBMCs) were isolated and incubated for 24h with (or without = control cells) paroxetine and bupropion, in concentrations of 30, 100 and 1000 ng/ml. After the incubation period in both groups, the amount of dead cells was calculated using trypam blue technique. NKA was evaluated using the classic51Cr release assay. CONCLUSIONS: PBMCs dead cells occurred in both groups and in proportion to all pharmacological concentrations. Nevertheless, the NKA was not affected, even with the reduction in the number of effective cells.

Propriedades psicométricas da Cocaine Selective Severity Assessment (CSSA) em mulheres usuárias de crack

Objetivo Este estudo teve como objetivo adaptar a Cocaine Selective Severity Assessment (CSSA) para o português do Brasil e verificar as propriedades psicométricas do instrumento em uma amostra de usuárias de crack. Métodos Após as etapas de tradução e adaptação, 125 mulheres usuárias de crack, internadas em uma unidade pública de desintoxicação, foram avaliadas. Para caracterização da amostra e análise das validades concorrente, de construto e preditiva, foram utilizados os seguintes instrumentos: SCID-I, ASI-6, BDI-II e CCQ-B. Resultados A análise fatorial exploratória identificou cinco fatores, com níveis adequados de consistência interna tanto para os fatores quanto para o escore geral da CSSA. Quanto à validade concorrente, a CSSA vai ao encontro de instrumentos já utilizados na clínica e em pesquisas. Em relação à validade de construto e preditiva, a CSSA pode ser sensível ao declínio dos sintomas de abstinência durante o processo de desintoxicação do crack. Conclusões Nossos achados foram além da tradução e adaptação da CSSA, proporcionando testes de validade e sugerindo que a CSSA é um instrumento confiável na avaliação dos sintomas de abstinência do crack.

Anaerobic oxidation of methane associated with sulfate reduction in a natural freshwater gas source

The occurrence of anaerobic oxidation of methane (AOM) and trace methane oxidation (TMO) was investigated in a freshwater natural gas source. Sediment samples were taken and analyzed for potential electron acceptors coupled to AOM. Long-term incubations with 13C-labeled CH4 (13CH4) and different electron acceptors showed that both AOM and TMO occurred. In most conditions, 13C-labeled CO2 (13CO2) simultaneously increased with methane formation, which is typical for TMO. In the presence of nitrate, neither methane formation nor methane oxidation occurred. Net AOM was measured only with sulfate as electron acceptor. Here, sulfide production occurred simultaneously with 13CO2 production and no methanogenesis occurred, excluding TMO as a possible source for 13CO2 production from 13CH4. Archaeal 16S rRNA gene analysis showed the highest presence of ANME-2a/b (ANaerobic MEthane oxidizing archaea) and AAA (AOM Associated Archaea) sequences in the incubations with methane and sulfate as compared with only methane addition. Higher abundance of ANME-2a/b in incubations with methane and sulfate as compared with only sulfate addition was shown by qPCR analysis. Bacterial 16S rRNA gene analysis showed the presence of sulfate-reducing bacteria belonging to SEEP-SRB1. This is the first report that explicitly shows that AOM is associated with sulfate reduction in an enrichment culture of ANME-2a/b and AAA methanotrophs and SEEP-SRB1 sulfate reducers from a low-saline environment.

Comparison of the effect of two HMG CoA reductase inhibitors on LDL susceptibility to oxidation

OBJECTIVE: To study the differences between fluvastatin and pravastatin regarding LDL susceptibility to oxidation, plasma levels of total cholesterol (TC), HDL-C, LDL-C and triglycerides (TG) in hypercholesterolemic patients with established coronary heart disease (CHD). METHODS: A double-blind randomized parallel study was conducted that included 41 hypercholesterolemic outpatients with CHD treated at the Instituto de Cardiologia do Rio Grande do Sul. The inclusion criteria were LDL-C above 100 mg/dL and triglycerides below 400 mg/dL based on 2 measures. After 4 weeks on a low cholesterol diet, those patients that fullfilled the inclusion criteria were randomized into 2 groups: the fluvastatin group (fluvastatin 40 mg/day) and the pravastatin group (pravastatin 20 mg/day), for 24 weeks of treatment. LDL susceptibility to oxidation was analyzed with copper-induced production of conjugated dienes (Cu2+) and water-soluble free radical initiator azo-bis (2'-2'amidinopropanil) HCl (AAPH). Spectroscopy nuclear magnetic resonance was used for determination of lipids. RESULTS: After 24 weeks of drug therapy, fluvastatin and pravastatin significantly reduced LDL susceptibility to oxidation as demonstrated by the reduced rate of oxidation (azo and Cu) and by prolonged azo-induced lag time (azo lag). The TC, LDL-C, and TG reduced significantly and HDL-C increased significantly. No differences between the drugs were observed. CONCLUSION: In hypercholesterolemic patients with CHD, both fluvastatin and pravastatin reduced LDL susceptibility to oxidation.

Estudio de la factibilidad del uso de bioindicadores pasivos para la detección selectiva de contaminantes orgánicos. Feasibility study of the use of pasive biomonitors for the selective detection of organic pollutants.

En Argentina, existe escasa información sobre las características y concentración de sustancias orgánicas en la atmósfera y, en particular, la información referida a compuestos polifluorados (como por ej. Ácidos perfluorocarboxílicos, PFCA) es prácticamente nula. Los niveles de concentración de estos compuestos están aumentando de manera alarmante en todo el mundo. Se conoce la elevada toxicidad de algunos de ellos debido a que son bioacumulativos, persistentes en el ambiente y potencialmente cancerígenos. En estos momentos se está investigando cuales son los precursores de estos compuestos en el medio ambiente y los mecanismos involucrados en la generación de los PFCA.El uso de biomonitores constituye una excelente alternativa al monitoreo instrumental automático, especialmente para países en desarrollo porque no requieren la aplicación de tecnologías complicadas y son de muy bajo costo. Con este fin se pretende evaluar la factibilidad del empleo de bioindicadores pasivos para la detección de sustancias orgánicas, entre ellos, alcoholes fluoroteloméricos y ácidos perfluorados y estimar el daño que estos compuestos provocan en los organismos expuestos. Se emplearán dos especies autóctonas de epífitas del género Tilandsia para evaluar modificaciones quimico-fisiológicas provocadas por la exposición a concentraciones conocidas de estos compuestos y la especie Tradescantia pallida para evaluar efectos genotóxicos. Se espera, además estimar las concentraciones ambientales de los compuestos bajo estudio mediante el empleo de biomonitores. En este contexto, el desarrollo de este proyecto tendrá un impacto favorable sobre el medio ambiente ya que sus resultados permitirán conocer la capacidad bioindicadora de especies biomonitoras autóctonas, con el fin de emplearlas para identificar ambientes contaminandos con compuestos orgánicos polifluorados y en un futuro extenderla a la mayor variedad de contaminantes atmosféricos orgánicos posibles. Además, la calibración de biomonitores servirá para realizar seguimientos temporales de este tipo de contaminantes en distintos ambientes en Argentina, o en el lugar donde exista el problema de contaminación.

Desarrollo de sistemas nano/micro-particulados con aplicación en la fotodegradación selectiva de contaminantes orgánicos en solución. Development of nano / micro-particles systems with application to selective photodegradation of organic pollutants in solution.

IDENTIFICACIÓN DEL PROBLEMA DE ESTUDIO. Las sustancias orgánicas solubles en agua no biodegradables tales como ciertos herbicidas, colorantes industriales y metabolitos de fármacos de uso masivo son una de las principales fuentes de contaminación en aguas subterráneas de zonas agrícolas y en efluentes industriales y domésticos. Las reacciones fotocatalizadas por irradiación UV-visible y sensitizadores orgánicos e inorgánicos son uno de los métodos más económicos y convenientes para la descomposición de contaminantes en subproductos inocuos y/o biodegradables. En muchas aplicaciones es deseable un alto grado de especificidad, efectividad y velocidad de degradación de un dado agente contaminante que se encuentra presente en una mezcla compleja de sustancias orgánicas en solución. En particular son altamente deseables sistemas nano/micro -particulados que formen suspensiones acuosas estables debido a que estas permiten una fácil aplicación y una eficaz acción descontaminante en grandes volúmenes de fluidos. HIPÓTESIS Y PLANTEO DE LOS OBJETIVOS. El objetivo general de este proyecto es desarrollar sistemas nano/micro particulados formados por polímeros de impresión molecular (PIMs) y foto-sensibilizadores (FS). Un PIMs es un polímero especialmente sintetizado para que sea capaz de reconocer específicamente un analito (molécula plantilla) determinado. La actividad de unión específica de los PIMs en conjunto con la capacidad fotocatalizadora de los sensibilizadores pueden ser usadas para lograr la fotodescomposición específica de moléculas “plantilla” (en este caso un dado contaminante) en soluciones conteniendo mezclas complejas de sustancias orgánicas. MATERIALES Y MÉTODOS A UTILIZAR. Se utilizaran técnicas de polimerización en mini-emulsión para sintetizar los sistemas nano/micro PIM-FS para buscar la degradación de ciertos compuestos de interés. Para caracterizar eficiencias, mecanismos y especificidad de foto-degradación en dichos sistemas se utilizan diversas técnicas espectroscópicas (estacionarias y resueltas en el tiempo) y de cromatografía (HPLC y GC). Así mismo, para medir directamente distribuciones de afinidades de unión y eficiencia de foto-degradación se utilizaran técnicas de fluorescencia de molécula/partícula individual. Estas determinaciones permitirán obtener resultados importantes al momento de analizar los factores que afectan la eficiencia de foto-degradación (nano/micro escala), tales como cantidad y ubicación de foto- sensibilizadores en las matrices poliméricas y eficiencia de unión de la plantilla y los productos de degradación al PIM. RESULTADOS ESPERADOS. Los estudios propuestos apuntan a un mejor entendimiento de procesos foto-iniciados en entornos nano/micro-particulados para aplicar dichos conocimientos al diseño de sistemas optimizados para la foto-destrucción selectiva de contaminantes acuosos de relevancia social; tales como herbicidas, residuos industriales, metabolitos de fármacos de uso masivo, etc. IMPORTANCIA DEL PROYECTO. Los sistemas nano/micro-particulados PIM-FS que se propone desarrollar en este proyecto se presentan como candidatos ideales para tratamientos específicos de efluentes industriales y domésticos en los cuales se desea lograr la degradación selectiva de compuestos orgánicos. Los conocimientos adquiridos serán indispensables para construir una plataforma versátil de sistemas foto-catalíticos específicos para la degradación de diversos contaminantes orgánicos de interés social. En lo referente a la formación de recursos humanos, el proyecto propuesto contribuirá en forma directa a la formación de 3 estudiantes de postgrado y 2 estudiantes de grado. En las capacidades institucionales se contribuirá al acondicionamiento del Laboratorio para Microscopía Óptica Avanzada (LMOA) en el Dpto. de Química de la UNRC y al montaje de un sistema de microscopio de fluorescencia que permitirá la aplicación de técnicas avanzadas de espectroscopia de fluorescencia de molecula individual. Water-soluble organic molecules such as certain non-biodegradable herbicides, industrial dyes and metabolites of widespread use drugs are a major source of pollution in groundwater from agricultural areas and in industrial and domestic effluents. Photo-catalytic reactions by UV-visible irradiation and organic sensitizers are one of the most economical and convenient methods for the decomposition of pollutants into harmless byproducts. In many applications it is highly desirable a high degree of specificity, effectiveness and speed of degradation of specific pollutants present in a complex mixture. In particular nano/micro-particles systems that form stable aqueous suspensions are highly desirable because they allow for easy application and effective decontamination of large volumes of fluids. Herein we propose the development of nano/micro particles composed by molecularly imprinted polymers (MIP) and photo-sensitizers (PS). The specific binding of MIP and the photo-catalytic ability of the sensitizers are used to achieve the photo-decomposition of specific "template" molecules in complex mixtures. Mini-emulsion polymerization techniques will be used to synthesize nano/micro MIP-FS systems. Spectroscopy (steady-state and time resolved) and chromatography (GC and HPLC) will be used to characterize efficiency, mechanisms and specificity of photo-degradation in these systems. In addition single molecule/particle fluorescence spectroscopy techniques will be used to directly measure distributions of binding affinities and photo-degradation efficiency in individual particles. The proposed studies point to a more detailed understanding of the factors affecting the photo-degradation efficiency in nano/micro-particles and to apply that knowledge in the design of optimized systems for photo-selective destruction of socially relevant aqueous pollutants.

Experimental study on n-butane partial oxidation to maleic anhydride in a solid electrolyte membrane reactor

n-Butane, Partial oxidation, Maleic anhydride, electrochemical oxygen pumping, solid electrolyte membrane reactor

Channel estimation and ICI cancellation for adaptive OFDM systems in doubly selective channels

Magdeburg, Univ., Fak. für Elektrotechnik und Informationstechnik, Diss., 2010

Spektroskopische in situ-Untersuchungen der katalytischen CO-Oxidation an oxidmodifizierten Platinmetalloberflächen

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2010

Electrochemical oxidation of H 2, CO gas mixtures in polymer-electrolyte-membrane fuel cells

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2014