Fatores químicos e físicos que afetam a contaminação por chumbo e cobre em água potável: uma abordagem para o estudo de caso em química analítica

Lead and copper concentrations in drinking water increase considerably on going from municipality reservoirs to the households sampled in Ribeirão Preto (SP-Brazil). Flushing of only 3 liters of water reduced metal concentrations by more than 50%. Relatively small changes in water pH rapidly affected corrosion processes in lead pipes, while water hardness appeared to have a long-term effect. This approach aims to encourage University teachers to use its content as a case study in disciplines of Instrumental Analytical Chemistry and consequently increase knowledge about drinking water contamination in locations where no public monitoring of trace metals is in place.

Defesa química: histórico, classificação dos agentes de guerra e ação dos neurotóxicos

Chemical agents are substances used for their toxic effects on humans, animals and plants. The main objective of chemical defense is to develop systems that reduce these effects while minimizing impact on the operational capacity of military troops. In this work, a report on the development of chemical warfare agents since the First World War and their classification is presented. Special attention is given to neurotoxic agents, the most lethal group of chemical agents known to date.

Química sem fronteiras

The main objective of this paper is to start and stimulate reflection, discussion and proposing actions that allow Chemistry in Brazil contribute to a prosperous, safer and better future for the nation.

Caracterização através de análise química da escultura portuguesa sobre madeira de produção erudita e de produção popular da época barroca

Making use of several analytical techniques, four erudite and four popular Portuguese baroque wooden sculptures were studied. The materials and techniques employed were identified and the relationship between their artistic quality and the materials used was investigated. In general, the pigments were common at the time, but one pigment discovered in the beginning of the 18th century and two rare arsenic pigments were also identified. In popular sculptures cost-saving was detected, particularly concerning the gold leaf. Regarding some technical procedures identified, recommendations found in historical documents did not seem to have been entirely followed, neither in erudite nor in popular sculptures.

Síntese e hidrólise de azalactonas de Erlenmeyer-Plöchl mediadas por radiação micro-ondas em aparelhos doméstico e dedicado: experimentos de química orgânica para a graduação

This work describes a green chemistry experiment for the synthesis of Erlenmeyer-Plöchl azalactones mediated by microwave irradiation, employing both dedicated and domestic equipment. Hippuric acid was reacted with equimolar amounts of benzaldehyde, p-chloro-benzaldehyde or p-N,N-dimethyl-benzaldehyde in acetic anhydride as the solvent. Acid hydrolysis of obtained 4-benzylidene-2-phenyloxazol-5(4H)-one under microwave and convectional heating afforded Z-α-(benzoylamino)cinnamic acid at a 51-61.5% yield. The UV-Vis molecular spectra of 4-benzylidene-2-phenyloxazol-5(4H)-one and 4-(4'-N,N-dimethylbenzylidene)-2-phenyloxazol-5(4H)-one were obtained in ethanol, CH2Cl2 and DMSO and bathochromic shift was observed for the latter azalactone.

Drogas de abuso em águas naturais e residuárias urbanas: ocorrência, determinação e aplicações forenses

Drugs of abuse are commonly used outside medical or legal settings where their production, marketing and consumption are subject to legal summons and/or intervention. Classified as emerging contaminants, these substances have been recently detected in samples of environmental concern, such as waters and wastewaters. This review presents the state-of-the-art on the methodological approaches used in sample preparation, the main techniques applied in analytical determination at trace levels, as well as the use of information related to the drug or its metabolite concentration in sewage samples to empirically estimate the consumption of drugs of abuse in a city or region.

Preparação de derivados do lapachol em meio ácido e em meio básico: uma proposta de experimentos para a disciplina de Química Orgânica Experimental

In this educational paper we describe the extraction of lapachol from its natural source according to acid-base concepts in organic chemistry and the use of its derivatives β-lapachone and hydroxy-hydrolapachol to exemplify intramolecular cyclization, carbocation stability, Michael addition reaction and chromatography. The experiments were performed during three different undergraduate organic chemistry laboratory classes using low cost material, while avoiding color reagents for TLC visualization, as well as small-scale column chromatography to isolate the mixture of lapachol and β-lapachone.

Patenteamento em nanotecnologia no Brasil: desenvolvimento, potencialidades e reflexões para o meio ambiente e a saúde humana

Nanotechnology developments continue to be produced at exponential rates for a wide and diverse range of applications. In this paper was done a study of technological forecasting in nanotechnology applied to health, based on information drawn in Brazil from 1991 to 2010. The longitudinal evolutions of the number of patent applications, their topics, and their respective patent families have been evaluated for the total global activity. There were obtained 1352 patent applications in this period. It were analyzed the legal nature of the depositors, the year of deposit, depositors' home countries and processes. It has been a goal subsidizes the policy-makers to adapt and modernize the regulatory framework on nanotechnology and risks involving health as a strategic area in the politics of Science.

Inventário de agrotóxicos e risco de contaminação química dos recursos hídricos no semiárido cearense

The first diagnosis of risk of environmental contamination was conducted for an area of intense agricultural activity in the semiarid cearense (Baixo Jaguaribe and Litoral de Aracati area). We verified the use of 201 rural products (pesticides) in the region, comprising 151 active ingredients. Regarding the active ingredients evaluated, 15.9% were associated with sediment and 29.8% were dissolved in surface water. The study showed that 13.2% to 36.4% of the active ingredients evaluated were classified as potential contaminants of groundwater resources. The study also revealed the most abundant pesticides and which environmental compartment must be evaluated.

Avaliação do conhecimento sobre periodicidade química em uma turma de química geral do ensino a distância

This work describes the software Quiptabela, suggests a teaching activity, and analyses responses of general chemistry students from the Biological Sciences distance course at the Federal University of Tocantins. The software was described according to its educational potential, featuring the creation of dozens of charts or tables correlating physicochemical properties of the elements, being Brazilian, and free distribution. The teaching activities suggested analyzed students' ability to create and analyze tables and charts correlating the properties of chemical elements. Some 41% of students tested could define the term "periodic", but failed to use the concept to explain and differentiate changes in mass or atomic radius with the atomic number of elements.

O tempo de pega em gelatinas comerciais: uma experiência da disciplina de quimiometria para estudantes de graduação em Química

The aim of this paper is to describe a chemometrics experiment for undergraduate chemistry students using basic concepts of experimental design to determine setting-time of commercial gelatins.

Química Nova Interativa - QNInt - o portal do conhecimento da SBQ: conectando ciência e educação

The Química Nova Interativa (QNInt) portal was launched in 2009 by the Brazilian Chemical Society (SBQ) to offer free quality content for broad audiences. QNInt provides peer-reviewed articles from SBQ journals on science & society, chemical concepts, classroom activities and educational research. With 3,000,000 visits, QNInt also offers a unique library of interactive molecules. In the International Year of Chemistry QNInt served for distributing pH kits and registering data from IUPAC's Global Water Experiment, yielding Brazil the largest share of the global pH data set. The portal performance makes QNInt a valuable resource for connecting science to education.

Visualização no ensino de química: apontamentos para a pesquisa e desenvolvimento de recursos educacionais

Visualization is a fast-growing field in science education. This review covers 171 articles published between 2001 and 2010 in 14 science education journals. Major findings include: i - despite the predominance of English speaking countries, interest in the topic has increased in several countries; ii - qualitative research is increasing, but quantitative methodologies prevail; iii - the role of peer interaction in group activities is little investigated; iv - research on the way students and teachers use visualization tools is increasing, but most publications focus on the tools; v - structure of matter remains the most common subject covered.

A abordagem de questões ambientais: contribuições de formadores de professores de componentes curriculares da área de ensino de química

This paper presents the results of a study involving current teachers of the chemistry teaching curricular components of twelve Chemistry licentiate courses at state universities in the South and South-east of Brazil. The aim was to analyse how these curricular components can work together to address environmental issues in Chemistry teacher-training. From analysis of the interviews, it can be ascertained for example that environmental themes in the curricular components analysed are treated with differing levels of intensity and perspectives, and in some cases, have a more illustrative character regarding chemistry concepts.