20 resultados para Cement composites. Waste tire rubber. Limestone gravel. Deformation

em Scielo Saúde Pública - SP


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The objective of the present study was to evaluate the effects of industrial solid waste (whitewash mud) on geotechnical properties considering the following engineering parameters: California Bearing Ratio (CBR), Atterberg limits and Permeability test. Seven soil samples derived from Alagoinhas, Bahia - Brazil, were classified by the Transportation Research Board (TRB) system. Two were selected as having a great geotecnical potential classified as A-3 (0) and A-2-4 (0), whitewash mud contents 10%, 15%, 20% and 25% dry weight and medium compaction effort were studied in the laboratory testing program. The results indicated the soil denominated good gravel as being the most promising one, when stabilized with whitewash mud, reaching the best results with the dosage of 20 and 25% of whitewash mud.

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The deep bedding is a swine alternative production, especially in the finishing phase, whose byproduct can be recycled, reducing the environmental impact. The objectives of this study were to characterize the ash coming from the controlled burning of the swine deep bedding (SDBA) based on rice husk, and to evaluate their performance in composites as a partial substitute for Portland cement (PC). To measure the differences between SDBA and rice husk ash (RHA) as a reference, we have characterized: particle size distribution, real specific density, x-ray diffraction, electrical conductivity, scanning electron microscopy, chemical analysis and loss on ignition. Samples were prepared for two experimental series: control, and another one with the partial replacement of 30% of SDBA in relation to the mass of the Portland cement. According to the results obtained for physical and mechanical characterization, the composites with SDBA can be used as a constructive element in the rural construction.

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Sisal fiber is an important agricultural product used in the manufacture of ropes, rugs and also as a reinforcement of polymeric or cement-based composites. However, during the fiber production process a large amount of residues is generated which currently have a low potential for commercial use. The aim of this study is to characterize the agricultural residues by the production and improvement of sisal fiber, called field bush and refugo and verify the potentiality of their use in the reinforcement of cement-based composites. The residues were treated with wet-dry cycles and evaluated using tensile testing of fibers, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Compatibility with the cement-based matrix was evaluated through the fiber pull-out test and flexural test in composites reinforced with 2 % of sisal residues. The results indicate that the use of treated residue allows the production of composites with good mechanical properties that are superior to the traditional composites reinforced with natural sisal fibers.

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OBJECTIVE: To estimate the seroprevalence of HIV, hepatitis B and C and syphilis and to describe risk behaviors associated to their transmission among recyclable waste collectors. METHODS: A seroepidemiological survey was carried out in the city of Santos, Southeastern Brazil, in 2005. A total of 315 individuals were enrolled in the survey, of which 253 subjects underwent serological testing HIV, hepatitis B and C and syphilis. Statistical analysis consisted of univariate and bivariate analyses (cross-tabulation and odds ratio) and multivariate analysis (by logistic regression), relating HIV infection with established risk behaviors and seropositivity. RESULTS: Overall seroprevalences were: HIV, 8.9%; hepatitis B, 34.4%; hepatitis C, 12.4%; and syphilis, 18.4%. Subjects were characterized by a predominance of males with low educational and economic levels, subjected to parenteral and sexual exposures to HIV and other sexually transmitted infections. Multivariate analysis results indicated that risk factors for both sexually and parenterally related exposure were significantly associated with HIV in this community. CONCLUSIONS: Seroprevalences found in the study were approximately 10 to 12 times higher than the national average. These communities are socially marginalized and generally not recognized by national programs as potentially endangered populations.

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Nowadays 70% of the world's rubber supply is synthesized artificially. The process involved in its manufacture is vulcanization which requires many chemical substances for speeding the process, as antioxidants to prevent deterioration of rubber, or others. These substances may constitute important sensitizers and thus be responsible for dermatological diseases like contact dermatitis. The objective of this study is to search for the main sensitizers among these rubber chemicals in a population mostly composed by women of a tropical country and compare the results with the ones obtained from previous studies which tested populations mainly composed by men and on different climates.

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Introduction: The collection of recyclable waste materials is a widespread activity among the urban poor. Today, this occupation attracts an increasingly large number of individuals. Despite its economic and environmental importance, this activity is associated with unsafe and unhealthy working conditions. The aim of this study was to investigate the seroepidemiological profile of hepatitis B virus (HBV) infection in a population of recyclable waste collectors in central Brazil. Methods: Recyclable waste collectors from all 15 recycling cooperatives in Goiânia City were invited to participate in the study. The participants (n = 431) were interviewed and screened for hepatitis B surface antigen (HBsAg) and antibodies against HBsAg (anti-HBs) and hepatitis B core antigen (anti-HBc) by enzyme-linked immunosorbent assay (ELISA). HBsAg- and anti-HBc-positive samples were tested for HBV DNA and genotyped. Results: The overall prevalence of HBV infection (HBsAg- and/or anti-HBc-positive) was 12.8%. An age over 40 years and illicit drug use were associated with HBV infection. HBV DNA was detected in 2/3 HBsAg-positive samples and in 1/52 anti-HBc-positive/HBsAg-negative samples (an occult HBV infection rate of 1.9%), in which the genotypes/subgenotypes A/A1, D/D3 and F/F2 were identified. Only 12.3% of the recyclable waste collectors had serological evidence of previous HBV vaccination. Conclusions: These findings highlight the vulnerability of recyclable waste collectors to HBV infection and reinforce the importance of public health policies that address the health and safety of this socially vulnerable population.

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The blue rubber nevus syndrome consists of multiple venous malformations in the skin and gastrointestinal tract associated with intestinal hemorrhage and iron deficiency anemia. Other organs may be involved. The causes of this syndrome are unknown. Its most common presentation is in the form of sporadic cases, but dominant autosomal inheritance has been described. It is a condition that affects both sexes equally, and its occurrence is rare in the black race. We present a case of this syndrome diagnosed in a 11-year-old patient. He had severe anemia and a venous swelling on the trunk. Similar lesions were found in the stomach, bowel, and on his foot. We emphasize the main clinical aspects: intestine, eyes, nasopharynx, parotids, lungs, liver, spleen, heart, brain, pleura, peritoneum, pericardium, skeletal muscles, bladder, and penis lesions, systemic complications that may occur to these patients which are thrombosis and calcification, as well as consumptive coagulopathy and thrombocytopenia that may occur within the nevi.

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The case of a patient with blue rubber bleb nevus syndrome who is infected by acquired immunodeficiency syndrome virus due to multiple blood transfusions is presented. This case shows that although it is a rare systemic disorder, blue rubber bleb nevus syndrome has to be considered in the differential diagnosis of chronic anemia or gastrointestinal bleeding. Patients should be investigated by endoscopy, which is the most reliable method for detecting these lesions. The patient underwent gastroscopy and enteroscopy via enterotomy with identification of all lesions. Minimal resection of the larger lesions and string-purse suture of the smaller ones involving all the layers of the intestine were performed. The string-purse suture of the lesions detected by enteroscopy proved to be an effective technique for handling these lesions, avoiding extensive intestinal resection and stopping the bleeding. Effective management of these patients demands aggressive treatment and should be initiated as soon as possible to avoid risks involved in blood transfusions, as occurred in this case.

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The purpose of this study is to evaluate in vitro the color stability of composite resins when exposed to beverages with high coloring contents from the Amazon region. 240 samples from four different composite brands (Natural Look, Z350, 4Seasons and Opallis) of hue A3 were fabricated using an acrylic matrix. The samples were stored in distilled water at 37ºC for 24 hours. The initial color (T0) was registered using a Canon EOS Rebel XTi 10 mp camera, and then the samples were divided into four groups (n=15): G1 (coffee), G2 (açaí juice), G3 (energetic guaraná) and G4 (control - distilled water). The samples were exposed to solutions of DES (6hs) and RE (18hs) and placed in a double boiler under constant agitation, at 37ºC for 30 days. The samples were immersed in the coloring solutions for 15 minutes daily. After 7, 15 and 30 days, new photographic registers were made (T1, T2 and T3). The images were analyzed using Corel PHOTO-PAINT 12 software to identify the colors through the HSB system. The Kruskal-Wallis and t tests (p<0.05) demonstrated significant differences in color (hue, saturation and brightness). The results revealed that none of the tested composites showed color stability when exposed to coloring solutions, and that the Amazon region beverages (açaí juice and energetic guaraná) showed to be less coloring than coffee.

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Used vehicle tires are a source of mosquito vectors and a means of their introduction and expansion. With the aim of assessing the effects of urbanisation on the main mosquito vectors in temperate Argentina, the infestation levels of Aedes aegypti (L.) and Culex pipiens L. were studied in used tires from highly urbanised cities to low-urbanised small towns in Buenos Aires. Immatures of both species accounted for 96% of the 9,722 individuals collected; the total individuals collected represented seven species. The percentage of water-filled tires containing mosquitoes [container index (CI)] was 33% and the percentage of infested sites [site index (SI)] was 65.2%. These indexes decreased significantly from low to high urbanisation levels for both mosquito species. The relative abundance (RA) of Ae. aegypti immatures was slightly higher toward large cities, but showed no difference for Cx. pipiens. The CI of shaded tires was significantly higher than the CI of exposed tires for both mosquito species. There was no difference in RA values between shaded and sunlit tires. The CI and the SI were highest during the summer across the urbanisation levels, except for Cx. pipiens, which continued to increase during the autumn in small towns. Results related to urbanisation gradient, sunlit exposure and seasonality are discussed.

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The prevalence of hepatitis C virus (HCV) in a population of recyclable waste collectors (n = 431) was assessed using a cross-sectional survey in all 15 cooperatives in the city of Goiânia, Central-West Brazil. The HCV prevalence was 1.6% (95% confidence interval: 0.6-3.6) and a history of sexually transmitted infections was independently associated with this infection. HCV RNA (corresponding to genotype 1; subtypes 1a and 1b) was detected in five/seven anti-HCV-positive samples. Although the study population reported a high rate (47.3%) of sharps and needle accidents, HCV infection was not more frequent in recyclable waste collectors than in the general Brazilian population.

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Life cycle of Tenuipalpus heveae Baker (Acari, Tenuipalpidae) on leaflets from three rubber tree clones. The biological cycle of Tenuipalpus heveae Baker, 1945 (Tenuipalpidae), a potential rubber tree pest mite, was studied by the observation of individuals reared on leaflets of the clones GT 1, PB 235 and RRIM 600, in controlled environmental conditions. Three daily observations were done of 60 eggs on leaflets from each clone in order to verify the development of immature stages and the female oviposition. The fertility life table was constructed based in the collected data. Mites reared on PB 235 had faster rate of development, requiring less time in days, to double its population in number (TD), and had the highest values for egg production, female longevity, net reproductive rate (Ro), intrinsic rate of natural increase (r m) and finite rate of increase (λ). Lower reproductive values and the longest time necessary to reach adult stage were recorded for the mites on GT 1. In all studied clones, the deutonymphal phase had the highest viability, while the larval phase had the lowest, highlighted by the survivorship curve that indicated high mortality during this life stage. The clone PB 235 allowed the most suitable conditions for the development of T. heveae, followed by RRIM 600, while GT 1 was the less suitable substratum to rear this mite species.

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Sarcosaprophagous macroinvertebrates (earthworms, termites and a number of Diptera larvae) enhance changes in the physical and chemical properties of organic matter during degradation and stabilization processes in composting, causing a decrease in the molecular weights of compounds. This activity makes these organisms excellent recyclers of organic matter. This article evaluates the succession of insects associated with the decomposition of solid urban waste separated at the source. The study was carried out in the city of Medellin, Colombia. A total of 11,732 individuals were determined, belonging to the classes Insecta and Arachnida. Species of three orders of Insecta were identified, Diptera, Coleoptera and Hymenoptera. Diptera corresponding to 98.5% of the total, was the most abundant and diverse group, with 16 families (Calliphoridae, Drosophilidae, Psychodidae, Fanniidae, Muscidae, Milichiidae, Ulidiidae, Scatopsidae, Sepsidae, Sphaeroceridae, Heleomyzidae, Stratiomyidae, Syrphidae, Phoridae, Tephritidae and Curtonotidae) followed by Coleoptera with five families (Carabidae, Staphylinidae, Ptiliidae, Hydrophilidae and Phalacaridae). Three stages were observed during the composting process, allowing species associated with each stage to be identified. Other species were also present throughout the whole process. In terms of number of species, Diptera was the most important group observed, particularly Ornidia obesa, considered a highly invasive species, and Hermetia illuscens, both reported as beneficial for decomposition of organic matter.

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Tannery residues and coal mine waste are heavily polluting sources in Brazil, mainly in the Southern States of Rio Grande do Sul and Santa Catarina. In order to study the effects of residues of chrome leather tanning (sludge and leather shavings) and coal waste on soybean and maize crops, a field experiment is in progress since 1996, at the Federal University of Rio Grande do Sul Experimental Station, county of Eldorado do Sul, Brazil. The residues were applied twice (growing seasons 1996/97 and 1999/00). The amounts of tannery residues were applied according to their neutralizing value, at rates of up to 86.8 t ha-1, supplying from 671 to 1.342 kg ha-1 Cr(III); coal waste was applied at a total rate of 164 t ha-1. Crop yield and dry matter production were evaluated, as well as the nutrients (N, P, K, Ca, Mg, Cu and Zn) and Cr contents. Crop yields with tannery sludge application were similar to those obtained with N and lime supplied with mineral amendments. Plant Cr absorption did not increase significantly with the residue application. Tannery sludge can be used also to neutralize the high acidity developed in the soil by coal mine waste.