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  • Author or Editor: C. Almeida x
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Abstract  

Commercial light-cured dental composites were used in this study. Two laboratorial composites, Resilab (Wilcos/Brazil), Epricord (Kuraray/Japan) were compared under cured and uncured conditions. Thermal analysis, infrared spectroscopy and scanning electron microscopy were used to evaluate the dental composites. The mass change and heat flow signals (TG–DSC) were recorded simultaneously by using STA 409 PC Luxx (NETZSCH), in the 25–800 °C temperature range at a heating rate of 10 °C/min under nitrogen atmosphere (70 mL/min). Employing thermo-microbalance TG 209 C F1 Iris (NETZSCH) coupled to the BRUKER Optics FTIR TENSOR, the samples were analyzed by combined thermogravimetric and spectroscopic methods (TG–FTIR). The initial sample mass was about ~12 mg, the data collection have been done in the 35–800 °C temperature range at a heating rate of 20 K/min in nitrogen atmosphere (flow rate: 40 mL/min). Finally, superficial topographic was analyzed by scanning electron microscopy (SEM). Dental composite evaluation suggests a high thermal stability and inorganic content in RES D sample. Degrees of conversion (DC) values were almost the same and there was no direct relationship between DC and amount of particles and size. Similar compositions were found in all samples.

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Abstract  

A Gent stacked filter unit sampler was used to collect air particulate matter (APM) in separate coarse (PM2.5–10) and fine (PM2.5) size fractions, at a sub-urban site in Lisbon, Portugal. The sampling was done during the year 2001 and two daily samples were taken per week. The filters were analyzed for particulate mass by instrumental neutron activation analysis (INAA). The chemical analysis of APM levels and the study of the atmospheric dynamics by back-trajectories showed that most of the PM2.5 and PM2.5–10 peaks events were associated with air masses transport from the Saharan desert. High mineral load in ambient particulate matter levels were registered during the Saharan dust outbreaks. The accuracy of INAA to measure Fe, Sc and Sm was evaluated by NIST filter standards, revealing results with an agreement of ± 10%. This method constituted an important tool to identify these events.

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Abstract  

The Portuguese Research Reactor (RPI) is a 1 MW swimming pool type reactor, operating since the early 1960s. The fuel is MTR type, with flat plates of U-Al alloy enriched to 93% in 235U. As the core configuration changed in April 2000, it became essential to characterise the neutron field in the most useful irradiation positions of RPI, in order to guarantee the accuracy in the application of k 0-neutron activation analysis (k 0-NAA). Experimental values of the thermal to epithermal neutron flux ratio (f) and of the deviation of the epithermal neutron spectrum from the 1/E shape (a) were determined using the Cd-ratio for multi-monitor method. The neutron temperature (T n) was obtained from co-irradiation of Lu with 1/v monitors. The results for several irradiation positions are presented and discussed in this work. Some element concentrations are determined based on the parameters obtained in this work, and compared with the certified reference material concentrations.

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Abstract  

Total particulate matter (TPM) was passively collected inside two classrooms of each of five elementary schools in Lisbon, Portugal. TPM was collected in polycarbonate filters with a 47 mm diameter, placed inside of uncovered plastic petri dishes. The sampling period was from 19 May to 22 June 2009 (35 days exposure) and the collected TPM masses varied between 0.2 mg and 0.8 mg. The major elements were Ca, Fe, Na, K, and Zn at μg level, while others were at ng level. Pearson′s correlation coefficients above 0.75 (a high degree of correlation) were found between several elements. Soil-related, traffic soil re-suspension and anthropogenic emission sources could be identified. Blackboard chalk was also identified through Ca large presence. Some of the determined chemical elements are potential carcinogenic. Quality control of the results showed good agreement as confirmed by the application of u-score test.

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Abstract  

Leachate samples from a sanitary landfill of Araraquara city and composting usine of Vila Leopoldina, São Paulo, Brazil were lyophilized to remove the water content. TG/DTG curves at different heating rates were recorded. The second step of the thermal decomposition of leachate from the Araraquara landfill (CB1), from the composting usine from Vila Leopoldina (CB2) from the organic phase extracted (FO) and aqueous phase (FA) were all kinetically evaluated using the non-isothermal method. By Flynn-Wall isoconversional method the following values were obtained: E=234±3.65 kJ mol−1 and logA=29.7±0.58 min−1 for CB1; E=129±1.66 kJ mol−1 and logA=11.8±0.10 min−1 for CB2; E=51.6±1.35 kJ mol−1 and logA=6.09±0.09 min−1 for FO and E=76.91±6.33 kJ mol−1 and logA=8.88±0.7 min−1 for FA with 95% confidence level. Applying the procedures of Málek and Koga, SB kinetic model (Šesták-Berggren) is the most appropriate to describe the decomposition of CB1, CB2, FO and FA.

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Abstract  

The analysis of airborne particulate matter (APM) by k 0-NAA was assessed using: (1) BCR reference material (RM) simulated air-filters, (2) synthetic air-filters prepared by spiking blank filters with standard solutions, and (3) real APM filters. k 0-INAA is a suitable technique for the analysis of APM, delivering accurate and precise results. However, the quality assessment of APM analysis appears to be a difficult task.

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Abstract  

In 2006, elementary schools of inner-city Lisbon, Portugal were given questionnaires to identify respiratory problems. In 1,175 children aged 5–10 years, 27.7% reported rhinitis, 2.5% reported hay fever and 25.9% reported asthma symptoms. April and August were the months with higher incidence of rhinitis, with a considerable difference nonetheless (10.5% and 2.3%, respectively.). The former trends are addressed here by using meteorological data, PM2.5, and its elemental speciation. Mann-Whitney U-tests were applied to the data sets. Significantly higher values were found for humidity, K+, NH4 +, Sb and Zn in April, and for temperature, Cl, Mg2+ and Na+ in August. Commuter and heavy-duty traffic may contribute to rhinitis episodes.

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Summary  

This paper presents the first measurement of the elemental composition of the suspended particulate matter in the atmosphere of Londrina city (Paraná State, Brazil). The sampling was accomplished in the summer of 2003 and in the winter of 2002, with a stacker filter holder, collecting simultaneously the fine particulates (PM2.5) and the coarse particulates (PM10). The concentration of K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb associated with particulate matter was determined by energy dispersive X-ray fluorescence. The results of the grouping analysis suggested that the elements in the aerosol particles came from two sources: soil re-suspension and industrial or anthropogenic activities.

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Summary  

A major concern with leaking petroleum is the environmental contamination by the toxic and water-soluble components such as benzene, toluene and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. All BTX compounds are depressants to the central nervous system. Consequently, BTX are priority pollutants and their occurrence has led to the development of several physical, chemical and biological methods for their removal. The use of nuclear technology for protection and conservation of the environment, by the destruction of toxic organic compounds present in the environmental, drinking water, soils and industrial sewage has been the object of study of several authors in Brazil and in the world. The objective of this paper is to present the preliminary results of the study of contamination of the seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene and xylene, and their removal by the exposure to the ionizing radiation.

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Abstract  

The number of children reporting rhinitis by month is compared with air pollutant concentrations in Lisbon, where they live and attend school. INAA, ionic exchange chromatography and data accessed through the internet were statistically processed with the children rhinitis data. Association between rhinitis and atmospheric variables are processed using Spearman non-parametric statistics and principal component analysis. It is pointed out that traffic, soil resuspension from traffic, meteorological conditions, and industry air pollutants contribute to respiratory trends. Ir (Pt group), a vehicle catalyst, may have some contribution.

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