Thermal degradation of geomembranes after exposure to heat

HDPE and PVC geomembranes are sensitive to changes in their properties when in contact with high temperatures. The effects of hot temperature on polymeric geomembranes are assessed by the ASTM D794 and ASTM D5721.This paper brings an analysis of degradation of the Poly Vinyl Chloride (PVC) and High Density Poly Ethylene (HDPE) geomembranes when exposed to conventional and air oven after specific periods.. Mechanical and physical properties were evaluated. OIT tests were also performanced to evaluate the level of oxidation degradation occurred on the HDPE geomembranes. Geomembranes of two thicknesses were tested: 1.0, 2.0 nun (PVC) and 0.8, 2.5 mm, (HDPE). The results obtained show, for example, that after the last period of exposure, the PVC geomembranes (1.0, 2.0 mm) were more rigid and stiffer than fresh samples. The HDPE geomembranes, on the other hand, when exposed to heat presented increases in deformation. OIT tests showed efficient to detect some level of degradation on the HDPE geomembranes.

SPT-T: test procedure and applications

Ranzini (1988) proposed the Standard Penetration Test with torque measurement (SPT-T) and some geotechnical engineers in Brazil have been using it since 1991. This paper presents the state of the art on SPT-T testing, emphasizing what is already established as common knowledge in Brazilian engineering practice, besides a suggestion for test procedure, including equipment and practical aspects. In addition, the study of the shape of the torque versus rotation-degree angle curve obtained by an electric torquemeter used in several SPT-T tests carried out on six experimental research sites in the southeast region of Brazil is discussed here. Four different methods to predict pile capacity based on SPT-T test results are briefly presented and a comparison with load tests carried out on different types of piles, on those six experimental research sites, is presented.

Efficiency of geotextile filters in dewatering wastes (sludge) from water treatment works

This paper evaluates the efficiency of geotextile filters for sludge from a compact water treatment plant (WTP). The key aspects required in the methodology of selection and designing geotextile filters for sludge from dewatering was investigated based on laboratory tests results. The analyses were supported by the measured filtrated volume of water and turbidity resulting from variable head permeability tests carried out in two geotextiles and using the conventional granular filter (sand and gravel). The results of the present study showed that more than 75% of the dewatering sludge can be filtrated with low turbidity, which permits that this water can return to the treatment plan in order to be reuse in another cycle. The reduced volume of sludge retained by the geotextile that is transferred to the drying pound increases its efficiency by reducing the drying time. The low volume of the dry waste can be removed and the geotextile can be easily cleaned or replaced when needed. These procedures significantly reduce the volume of water needed in dewatering and also avoids waste discharges in the environment.

The influence of the physigraphic and geologic condition aspects on the environmental degradation in the city of Guaratingueta

The present paper deals with environmental degradation in the city of Guaratingueta, Brazil; as a result of disordered urban settlement and development. Three site areas in the city resting on different geologic units were selected for the analyses, i.e.: precambrian rocks, tertiary sedimentary basin, and recent quaternary soil deposits. It has been found that geological and geotechnical aspects are fundamental to form the basis for environmental preservation and urban planning.

Manifestações clínicas, bioquímicas, ultrassonográficas e metabólicas da síndrome dos ovários policísticos em adolescentes

PURPOSE: To evaluate the clinical, ultrasonographic, biochemical and metabolic alterations of adolescents with polycystic ovary syndrome (PCOS). METHODS: Retrospective observational study conducted on 44 adolescents aged 12 to 19 years, diagnosed with PCOS according to the Rotterdam Consensus. Metabolic changes were assessed according to the recommendations of the International Diabetes Federation, considering: waist circumference (WC) ≥90th percentile (10-15 years of age) or >80 cm (age >16 years), fasting glucose >100 mg/dL, triglycerides >150 mg/dL, HDL <40 mg/dL, and blood pressure ≥Hg 130/85 mm. RESULTS: Mean age was 16.7±2.2 years and age at menarche was 11.8±1.4 years. The menstrual irregularity most frequently observed was amenorrhea (72.7%) followed by oligomenorrhea (27.3%); hirsutism was observed in 86.4% and acne in 56.8%. Polycystic ovaries were observed by ultrasound only in 27.3%. Mean BMI was 30.3±6.6 kg/m2. According to BMI, 52.3% of adolescents were obese, 13.6% were overweight and 6.8% had a healthy weight. Increased waist circumference (63.6%, 28/44) and the reduction of HDL-C (34.1%, 15/44) were the metabolic changes most frequently observed. Increased triglycerides were observed in 27.3% (12/44) and increased blood pressure and impaired fasting glucose were found in 9.1% (4/44) and 4.5% (2/44) of cases, respectively. Acanthosis nigricans was observed in 52.3% and insulin resistance in 62.8% of the adolescents with PCOS. Metabolic syndrome was identified in six children (13.6%), all of them obese or overweight. CONCLUSION: In the adolescents with PCOS studied here, menstrual irregularity and hirsutism were the most common clinical manifestations, while the sonographic findings consistent with polycystic ovaries were less prevalent. Obesity associated with insulin resistance predisposes these adolescents to a higher frequency of metabolic disorders.