Ferramenta computacional para avaliação de kerma no ar em aplicações de radioproteção em áreas de internação de pacientes: proposição de um método simples para avaliação experimental

OBJETIVO: Apresentar uma ferramenta de análise de dados que pode ser utilizada para proteção de pacientes e trabalhadores em áreas de uso de equipamentos móveis. MATERIAIS E MÉTODOS: Foi desenvolvida uma ferramenta, em planilha ativa Excel®, que utiliza medidas de exposição para gerar um banco de dados de fatores de forma e calcular o kerma no ar ao entorno de um leito. O banco de dados inicial foi coletado com três equipamentos móveis. Um espalhador não antropomórfico foi utilizado, sendo realizadas medidas de exposição em uma malha de (4,2 × 4,2) m², ao passo de 0,3 m. RESULTADOS: A ferramenta calcula o kerma no ar (associado à exposição de pacientes expostos e ao equivalente de dose ambiente) à radiação secundária. Para distâncias inferiores a 60,0 cm, valores acima do limite máximo de equivalente de dose ambiente definido para área livre (0,5 mSv/ano) foram verificados. Os dados coletados a 2,1 m foram sempre inferiores a 12% do referido limite. CONCLUSÃO: A ferramenta é capaz de auxiliar na proteção radiológica de pacientes e trabalhadores, quando associada à coleta de dados adequada, pois possibilita a determinação de áreas livres ao entorno de leitos em áreas onde equipamentos móveis geradores de radiação X são utilizados.

Sulfitos duplos contendo cobre (I) e um metal de transição M(II) tipo Cu2SO3.M(II)SO3.2H 2O [M(II) = Cu(II), Fe(II), Mn(II) e Cd(II)]: preparação e seletividade na incorporação de M(II)

The metal-catalyzed autooxidation of S(IV) has been studied for more than a century without a consensus being obtained as to reaction rates, rate laws or mechanisms. The main objective in this work was to explore the reaction between Cu(II) and SO2 in the presence of M(II), paying special attention to the formation of double sulfites like Cu2SO3.M(II)SO3.2H 2O. The two principal aspects studied were: i) a new way to prepare double sulfites with high purity degree and the selectivity in the M(II) incorporation during the salt formation.

Um método simples para preparação de metalocenos sensíveis ao ar

A simple laboratory technique is described for the synthesis of cyclopentadienylthallium and methylcyclopentadienylthallium and their use in the preparation of air sensitive metallocenes in solution. It does not use manifold, drybox or any other special glassware and was applied to the synthesis of cobaltocene, nickelocene and their methyl substituted analogs.

A qualidade do ar de interiores e a química

In Brazil, very little experimental work on measurements of indoor air pollutant levels has been done. Nowadays, increasing attention is being given to indoor air quality and the health problems associated with buildings and the indoor work environment. The scope of this paper is to review the major pollutants found in indoor environments and their sources. Subsequently, exposure to indoor air pollutants and health effects are considered. The review concludes by briefly addressing assessment of indoor air quality in Brazil and research needs.

Presença de compostos carbonílicos no ar em ambientes internos na cidade de São Paulo

The presence of low carbonyl compounds (C1-C4) and glutaraldehyde was observed in 14 work-locations in São Paulo city, Brazil, during January to July 1997 period. The quantification of other carbonyls was not possible due to a sampling artifact caused probably by undesirable reactions between the ambient ozone and the organic substract of C18 cartridge used to collect carbonyls. High indoor concentrations, compared to outdoor levels, were observed for all compounds. Formaldehyde was the most abundant species (29 ppb) followed by acetone and acetaldehyde (25 and 17 ppb) with a small contribution of propanal, crotonaldehyde and C4 isomers (0.7 to 1.5 ppb) when related to the total indoor carbonyls level. Glutaraldehyde was observed only in two different occupational locations in a hospital at high concentrations (121 ppb). In general, high individual carbonyl levels as well as total carbonyls levels found in several locations indicated an unpropitious air quality for the occupants of these non-industrial sites.

Peptídeos de conformação restrita induzida pela incorporação de unidades (aza)lactâmicas

Conformational constraint is an approach which can be used to restrict the flexibility of peptide molecules and to provide information on the topographical requirements of receptors. The incorporation of conformationally constrained units in a peptide can lead to peptide analogues that present numerous advantages such as the potentialization of the pharmacological activity and the decrease of enzymatic degradation. This review discusses the peptide analogues containing a lactam or azalactam unit in their sequences. Of particular interest has been the replacement of a dipeptide motif in a peptide that simulates a beta-turn.

Geração eletroquímica do hidreto de selênio em sistema de injeção em fluxo com detecção por espectrometria de absorção atômica com chama Ar-Glp

This paper presents a system for electrochemical hydride generation using flow-injection and atomic absorption spectrometry to determine selenium in biological materials. The electrolytic cell was constructed by assembling two reservoirs, one for the sample and the other for the electrolytic solution separated by a Nafion membrane. Each compartment had a Pt electrode. The sample and electrolyte flow-rates, acidic media, and applied current were adjusted to attain the best analytical performance and ensure the membrane lifetime. The atomisation system used a T quartz tube in an air-LPG flame. The composition of the flame, the observation height, and the argon flow rate used to carry the hydrides were critically investigated. The system allowed to perform thirty determinations per hour with a detection limit of 10 mug L-1 of Se. Relative standard deviations were in general lower than 1.5% for a solution containing 20.0 and 34.0 mug L-1 of Se in a typical sample digest. Accuracy was assessed analysing the certified materials: rice flour (NIST-1568) from National Institute of Standard and Technology and dried fish (MA-A-2), whole animal blood (A-2/1974) from the International Atomic Energy Agency.

AR 117: viviendas en Alcázar de San Juan

Postprint (published version)

Avaliação dos métodos analíticos para a determinação de metabólitos do benzeno como potenciais biomarcadores de exposição humana ao benzeno no ar

Increasing attention is being paid to the use of biomarkers for determining the exposure of humans to air toxics. Biomarkers include the nonreacted toxic substance, their metabolites, or the reaction products of these toxics with naturally substances in the body. Significant progress has been made in the measurement of biomarkers during the past several years. Much of this progress has been because of the development of advanced analytical techniques for identification and quantification of the chemical species in complex matrix, such as biological fluids. The assessment of the potential cancer risk associated with exposure to benzene at occupational and non-occupational ambient is necessary because of the toxicological implications of this air pollutant. Thus, in this review, the analytical methodologies used to determine the benzene metabolites, in special, urinary muconic acid and S-phenylmercapturic acid, are described and several problems affecting the precision of these procedures are discussed. Finally, in view of the difficulty pointed out for selecting the more adequate biomarker, further studies to evaluate the human exposure levels to benzene should be done.

Gota suspensa para avaliação de aldeído total no ar interno e externo do ambiente

A sensitive and simple system was proposed for the in situ measurement of total aldehyde in outdoor or indoor ambient. The method is based on the use of a reagent drop as an useful interface to preconcentrate the sample prior to determination of total aldehyde as formaldehyde. The drop is formed at the tip of a cylindrical tube that contains two optical fibers placed on opposite sides and in contact with the reagent solution. One optical fiber carries the red light to the drop form a light emitting diode (LED). The transmitted light is measured by a second optical fiber/photodiode system. The analytical signal is read and converted into absorbance. The reagent solution of 3-methyl-2-benzothiazoline hydrazone (MBTH) forms a blue cation during reaction with formaldehyde that can be measured at 660 nm. Some aspects of kinetics reaction formation of dye were reevaluated. The formaldehyde reacts with MBTH and forms the azine in about 12 min. The oxidation of MBTH by Fe (III) and the formation of dye requires 3 min. The absorbance of the reagent drop is proportional to the sampling time and to the analyte concentration. The absorbance signal increases with increased sample gas flow until a maximum is reached then decreases until it forms a plateau. The proposed method was evaluated using both outdoor and indoor samples, and it was shown to viable provide an accurate measure of total aldehyde.

Avaliação de poluição do ar por chumbo particulado: uma abordagem geoquímica

High lead concentrations up to 5478 mg kg-1 were detected in dry atmospheric precipitations in Rio Grande city and adjacent area. Lead anomalies cover up to 30% of the study area. Lead concentration measurement in dry atmospheric precipitation and suspended particulate matter provides a possibility to detect concentrations above lead threshold in the air. The most impacted areas are fishermen's villages. The most possible source of lead in the air is uncontrolled sub industrial activity of local population

Impacto dos catalisadores automotivos no controle da qualidade do ar

Advanced industrialized nations have experienced severe pollution problems over the past forty years, caused mainly by carbon monoxide, hydrocarbons and nitrogen oxide emissions from automobiles. Catalyst technology has played a major part in minimizing these emissions as required by even more restrictive laws. The catalyst has been optimized over the years to meet the requirements of high activity and long life. The oxidation of hydrocarbon and carbon monoxide are in advanced development stage while that of NOx catalysts is far less advanced. In the future, catalyst technology is expected to contribute to overcome the challenges to get a cleaner air.

Poluição química relacionada ao ar de interiores no Brasil

During the last two decades there has been increasing concern within the scientific community related to the effects of indoor air quality on health. Changes in building design devised to improve energy efficiency and new synthetic building materials have contributed to increase pollutant concentrations. These factors have generated poor air quality and caused the development of a lot of symptoms known as Sick Building Syndrome (SBS). In Brazil, there are few studies in this area, collected in this review to support researches and awareness of the need to adopt preventive measures to reach a better quality for the Indoor Environment.

Amostragem de compostos orgânicos voláteis no ar utilizando a técnica de microextração em fase sólida

The sampling of volatile organic compounds using solid phase microextraction is reviewed and its principles are described. The development and application of solid phase microextraction in the sampling of VOCs are presented and discussed.

Estimativa do fluxo de amônia na interface ar-mar na Baía de Guanabara: estudo preliminar

In the begining of April 2004, concentrations of NHx (NH3 + NH4+) were measured in surface waters of the Guanabara Bay. Concentrations varied from 2 to 143 mmol L-1. Ammonia exchange at the air-sea interface was quantified using a numerical model. No measurement of NH3 concentration in air (c air) was performed. Thus, calculations of NH3 flux were based on the assumptions of c air = 1 and 5 µg m-3. Fluxes were predominantly from the water to the atmosphere and varied from -20 to almost 3500 µg N m-2 h-1.