Use of admixtures in organic-contaminated cement-clay pastes

In this work microstructure, porosity and hydration degree of cement-based solidified/stabilized wasteforms were studied before assessing their leaching behaviour. 2-Chloroaniline was chosen as a model liquid organic pollutant and included into cement pastes, which were also modified with different admixtures for concrete: a superplasticizer based on acrylic-modified polymer, a synthetic rubber latex and a waterproofing agent. An organoclay, modified with an ammonium quaternary salt (benzyl-dimethyl-tallowammonium, BDMTA), was added to the pastes as pre-sorbent agent of the organic matter. All the samples were dried up to constant weight in order to stop the hydration process at different times during the first 28 days of curing, typically, after 1 day (1d), 7 days (7d) and 28 days. Then, the microstructure of the hardened cement-clay pastes was investigated by powder X-ray diffraction (XRD). The hydration degree and porosity were studied by thermal analysis (TG/DTA) and mercury intrusion porosimetry (MIP), respectively. For samples cured for 28 days a short-term leach test set by Italian regulation for industrial waste recycling (D.M. 5 February 1998) was performed. The best results showed a 5% release of the total initial amount of organic pollutant.     

Mangrove health in an arid environment encroached by urban development--a case study

Urban development will soon encroach upon several protected and largely unspoiled arid climate mangroves ecosystems located along the lagoon called Ensenada de La Paz in Baja California Sur, Mexico. Many of these mangroves are located on a large sandbar that separates the lagoon on the south side from Bahía de La Paz to the north. A general evaluation of the current status of these mangroves was conducted to establish biological and physicochemical indicators of the health of these mangroves to serve as a natural or predevelopment baseline in future management. The following parameters were measured in the feeding channels of the mangroves and at the mouth of the channels: vegetation coverage, species and health, and levels of dissolved oxygen, pH, salinity, total nitrogen, ammonium, nitrates and nitrites, phosphorus ions, and organic matter in sediments and seawater. The microbiological elements that were studied included aerobic bacteria, N2-fixing bacteria, inorganic phosphate solubilizers, coliform, and phytoplankton diversity. Bird populations were counted, with special attention to migratory and resident birds and protected and endangered species. A comprehensive analysis of all the elements indicated that the health of the sandbar mangrove populations is good despite the proximity of a modest urban center. It also demonstrated that several biological and physicochemical parameters used in this study, including the birds, can serve as indicators of mangrove health and as a baseline for future management of mangroves in regions with arid climates.     

Brazilian scientific production in science education

In the present study we analyzed the Brazilian scientific production in the area of science education. The study was structured on: data by research groups registered in Conselho Nacional de Desenvolvimento Científico e Tecnológico; analysis of the post-graduate strictu sensu programs; analysis of theses and dissertations linked to post-graduate programs; and papers in international databases. Our research was conducted strictly via world wide web, from December 2009 to September 2010. It was found that both number of research groups, researchers, post-graduate programs, thesis, dissertations and papers presented a marked increase, especially in the last decade (from 2000 onwards). The major research centers were found to be located in public universities from Brazilian southeast and south regions. However, it was observed a tendency of decentralization, due to a recent investment in new public universities in the other Brazilian regions. So, this study sought to present an overview of the scientific production about science education and we expect that this information can help to expand the vision about the development of this research area in Brazil.     

New carbon composite adsorbents for the removal of textile dyes from aqueous solutions: Kinetic,equilibrium, and thermodynamic studies

New carbon composite materials were prepared by pyrolysis of mixture of coffee wastes and red mud at 700 °C with the inorganic: organic ratios of 1.9 (CC-1.9) and 2.2 (CC-2.2). These adsorbents were used to remove reactive orange 16 (RO-16) and reactive red 120 (RR-120) textile dyes from aqueous solution. The CC-1.9 and CC-2.2 materials were characterized using Fourier transform infrared spectroscopy, Nitrogen adsorption/desorption curves, scanning electron Microscopy and X-ray diffraction. The kinetic of adsorption data was fitted by general order kinetic model. A three-parameter isotherm model, Liu isotherm model, gave the best fit of the equilibrium data (298 to 323 K). The maximum amounts of dyes removed at 323 K were 144.8 (CC-1.9) and 139.5 mg g^?1 (CC-2.2) for RO-16 dye and 95.76 (CC-1.9) and 93.80 mg g^?1 (CC-2.2) for RR-120 dye. Two simulated dyehouse effluents were used to investigate the application of the adsorbents for effluent treatment.     

On the Measurement of Thickness of Ice Layers on Power Transmission Lines

In this paper, measurement of ice and ice/water layer thickness on power transmission lines using Goubau modes at 1, 2.54 and 10 GHz is analyzed, simulated and discussed. Ice layer thicknesses change the phase and attenuation of Goubau mode propagation over a given line length. It is found feasible to determine layer thickness by measuring the phase and attenuation of the Goubau mode at a few GHz. In addition to the thickness, it is also possible, to determine the composition of the layer by measuring the different dielectric properties of ice, water and their mixture over a wide bandwidth to develop a database for comparison with measured data. The sensitivity of suggested instrumentation is sufficient for short line lengths (up to 1 m) or long lengths (several km). The implementation of instrumentation on long lines is still to be done but no major obstacles are foreseen. The decision to de-ice transmission line using any given and established techniques is facilitated if average ice thickness on transmission line between supporting transmission line towers can be measured.     

Morphological description of the immature stages of Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae)

In the dipteran genus Hermetia, only 6 of the 78 valid species have documented immature stages: H. albitarsis Fabricius, 1805, H. aurata Bellardi, 1859, H. concinna Williston, 1900, H. illucens (Linnaeus, 1758), H. panamensis Greene, 1940 and H. pulchra Weidemann, 1830. In particular, H. illucens stands out due to its reported applicability for forensic, medical and economic purposes. Here, we described the morphology of eggs and immature stages of this species, with a view to detecting differences between instars and in the pupal stage, which should eventually help properly identifying larval age. We utilized both optical and scanning electron microscopy tools. The eggs are elliptical and elongated, and color varies from cream white to yellowish. The larvae are apodal, hemichephalic and holopneustic, flattened dorso‐ventrally and may be recognized by the head elongated, dorsal and ventral chaetotaxy of the cephalic capsule, thoracic and abdominal segments, and the morphology of the anterior and posterior spiracles. The pupae are adecticous and coarctate, tegument dark brown and pruinescence varying from brown to golden. The overall morphology across instars is similar, but marked variations were observed in the shape of the antennal articuli and the shape of the setae (first instar compared to the others). Our results supplement the biological information on Hermetia illucens and should aid the proper identification and aging of juveniles in the field, as a way to minimize errors in the calculation of the post‐mortem interval.     

Influence of Testing Temperature on the Corrosion Behavior of API 5L X70 Pipeline Steel

It is known that localized corrosion attack takes a preponderant role in the onset of stress corrosion cracking of pipeline steels in high pH conditions. Carbonate/bicarbonate solutions can be employed to study the localized corrosion behavior of these materials. In addition to the presence of chloride ions in the electrolyte, the solution temperature is also of prime importance to the onset of pitting corrosion. The aim of this work is to evaluate the influence of the testing temperature on the corrosion behavior of the API 5L X70 pipeline steel which is a standard material for gas pipelines in Brazil. Samples were exposed to a solution consisting of Na2CO3, NaHCO3 and NaCl at three different temperatures： RT （room temperature）, 40 ℃ and 60 ℃. The corrosion morphology was observed using SEM （scanning electron microscopy）. The results showed that pitting corrosion became facilitated when the steel was immersed at higher temperatures.