995 resultados para Microbial Control
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Doctoral dissertation for Ph.D. degree in Sustainable Chemistry
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Memoria presentada para optar al grado de Doctor en Higiene, Salud y Seguridade en el Trabajo
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A school-based control program of intestinal helminths was undertaken among schoolchildren in the Low-Napo region, north-eastern Ecuador. Forty-eight percent of children were infected with one or more helminths at the first examination. The prevalence at the baseline was Ascaris 33.2% followed by hookworm 24.1% and Trichuris 6.5%. Sex was found to be a significant factor influencing the prevalence of hookworm and Trichuris. Prevalence was compared 9 months and 18 months after treatment. After 9 months, Ascaris and Trichuris prevalence had decreased but not hookworm. All of them increased after 18 months. The findings suggest that only a course of mebendazol had a minor effect on the control of helminth infections.
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Economics from the NOVA – School of Business and Economics
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The action of fenthion was studied in a 15% epicutaneous formulation upon Rhipicephalus sanguineus, which may transmit pathogens to men and other animals, such as Ehrlichia, Babesia and Ricketsia. Dogs were artificially infected for the trial. The fenthion bioassays were begun four months after artificial infestation. The test group, having a mean of 186 ticks per dog, received the formulation dosage according to body weight on the neck region. Tick counts were performed, considering diameters > or = 2mm, during 11 days of treatment, in the most affected body areas: back, ears and paws. Before the application of fenthion in the dogs, it were observed an average 43.3% ticks in the ears, 38.1% in the back area and 17.6% in the paws. The number of ticks in dogs decreased by 36.2%, 63.8%, 82.7%, 67%, 40% and 4.9%, respectively on days 1, 2, 3, 5, 7, 9 and 11 after treatment. R. sanguineus anti-tick activity, lower than that officially recommended, was verified. The number of ticks increased progressively after the 5th day, demonstrating residual insecticide inefficacy. The results obtained did not indicate the use of this formulation, at the tested dosage, as an elective measure for R. sanguineus control.
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Epidemiological surveillance activities were implemented in 1980 in Mambaí and Buritinópolis counties, Goiás State. Twenty years later the authors evaluated the impact of these vector control measures on Chagas' disease transmission, based on entomological indicators. Entomological investigation was conducted using the man-hour technique and covering all domiciles. In order to study vector food sources the stomach contents of triatomines were analyzed using the modified precipitins technique. Triatomines were shown to be present in 48 (71.6%) of the 67 locations. Peridomiciliary infestation rates in Mambaí and Buritinópolis were 8.7% and 12.1%, respectively, while intradomiciliary rates were 0.7% and 1.2%. Triatoma sordida was the species identified in 97.3% of all captured specimens. It was also the only species found to be naturally infected with Trypanosoma cruzi. Birds were the most frequent food source (45%) for Triatoma sordida. The most significant result was the complete absence of Triatoma infestans in the two counties.
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The proliferation of Aedes aegypti, a species of mosquito that is the vector of the dengue pathogen, is being augmented by the population's lack of care in allowing the formation of larval habitats. One form of controlling dengue is the distribution of information on the mosquito to improve awareness and to provide the means necessary for the elimination of its reproductive habitats. To evaluate a teaching method concerning the vector and dengue, students from the 5th and 6th years of primary education were compared before and after didactic intervention with a group of control students. The students who received intervention were more successful in identifying the stages of the cycle, biological and morphological characteristics of the adult insect and the importance of the mosquito in health issues. The didactic intervention was successful in developing knowledge leading to increased awareness of the importance of preventative measures that should be taken against the vector and the disease.
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This epidemiological investigation examines the impact of several environmental sanitation conditions and hygiene practices on diarrhea occurrence among children under five years of age living in an urban area. The case-control design was employed; 997 cases and 999 controls were included in the investigation. Cases were defined as children with diarrhea and controls were randomly selected among children under five years of age. After logistic regression adjustment, the following variables were found to be significantly associated with diarrhea: washing and purifying fruit and vegetables; presence of wastewater in the street; refuse storage, collection and disposal; domestic water reservoir conditions; feces disposal from swaddles; presence of vectors in the house and flooding in the lot. The estimates of the relative risks reached values up to 2.87. The present study revealed the feasibility of developing and implementing an adequate model to establish intervention priorities in the field of environmental sanitation.
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Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente Perfil de Engenharia de Sistemas Ambientais
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Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores
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Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica
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Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica
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Functional regeneration of organs upon injury is a key process for animals survival. Contrary to humans, some vertebrates are remarkably competent in regenerating after acute organ or appendage lesions. This advantageous skill allows overcoming limitations in repair even in adult stages, when tissues are fully developed, via a process of epimorphic regeneration. One such organism is the zebrafish, which can regenerate several organs, namely its heart, retina, spinal cord and fins. (...)
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Using a green methodology, 17 different poly(2-oxazolines) were synthesized starting from four different oxazoline monomers. The polymerization reactions were conducted in supercritical carbon dioxide under a cationic ring-opening polymerization (CROP) mechanism using boron trifluoride diethyl etherate as the catalyst. The obtained living polymers were then end-capped with different types of amines, in order to confer them antimicrobial activity. For comparison, four polyoxazolines were end-capped with water, and by their hydrolysis the linear poly(ethyleneimine) (LPEI) was also produced. After functionalization the obtained polymers were isolated, purified and characterized by standard techniques (FT-IR, NMR, MALDI-TOF and GPC). The synthesized poly(2-oxazolines) revealed an unusual intrinsic blue photoluminescence. High concentration of carbonyl groups in the polymer backbone is appointed as a key structural factor for the presence of fluorescence and enlarges polyoxazolines’ potential applications. Microbiological assays were also performed in order to evaluate their antimicrobial profile against gram-positive Staphylococcus aureus NCTC8325-4 and gram-negative Escherichia coli AB1157 strains, two well known and difficult to control pathogens. The minimum inhibitory concentrations (MIC)s and killing rates of three synthesized polymers against both strains were determined. The end-capping with N,N-dimethyldodecylamine of living poly(2- methyl-2-oxazoline) and poly(bisoxazoline) led to materials with higher MIC values but fast killing rates (less than 5 minutes to achieve 100% killing for both bacterial species) than LPEI, a polymer which had a lower MIC value, but took a longer time to kill both E.coli and S.aureus cells. LPEI achieved 100% killing after 45 minutes in contact with E. coli and after 4 hours in contact with S.aureus. Such huge differences in the biocidal behavior of the different polymers can possibly underlie different mechanisms of action. In the future, studies to elucidate the obtained data will be performed to better understand the killing mechanisms of the polymers through the use of microbial cell biology techniques.