Alographia dos álkalis... de Frei Conceição Veloso: um manual de química industrial para produção da potassa no Brasil colonial

Potassium carbonate, or potash, was the most important industrial chemical of the 18th century. It was essential for producing glass, soap, saltpeter, dyes, several drugs, and also used for bleaching linens, paper, and sugar. We examine here a book in which Brazilian author José Mariano da Conceição Veloso gathered his translations into Portuguese of English and French articles, letters, patents, and pamphlets with instructions on how to prepare potash. We discuss especially his version of Richard Watson's essay entitled 'Of saline substances', and Veloso's own 'Flora Alographica', a description of the Brazilian plants that could be used to prepare potash.

Avaliação da pós-graduação da área de química na CAPES e a internacionalização das revistas da Sociedade Brasileira de Química: Journal of the Brazilian Chemical Society e Química Nova

This paper discusses of the use of the Impact Factor in the evaluation of chemistry graduate courses by CAPES and the internationalization of the Journal of the Brazilian Chemical Society and Química Nova.

Hidrolisado protéico de pescado obtido por vias química e enzimática a partir de corvina (Micropogonias furnieri)

The fish proteins has the advantage of a high sensibility to the hydrolysis and also a balanced composition in aminoacids. The production of protein hydrolyzed from by-products of fish process industry has been receiving more attention on the last years. The aim of this work was to evaluate the production of protein hydrolyzed from Micropogonias furnieri through chemical and enzymatic methods, verifying some functional properties. The results showed that the production of the hydrolyzed improved some functional properties of the proteins found in the filet and in the waste, what is desirable for a subsequent application.

A formação em Química discutida com base nos modelos proposto por estudantes de pós-graduação para o fenômeno de dissolução

Mental models play an important role in the evolution of an individual's so-called knowledge. Using such representations, students can explain, foresee, and attribute causality to observed phenomena. In the case of Chemistry, the ability to work mentally with models assumes great importance, due to the microscopic component that is characteristic of this science. With the objective of exploring students' ability to work with models, 27 students of the Chemistry Institute of UNESP were asked to describe the mechanisms of dissolution, in water, of NaCl, HCl and HCN, as well as the partial dissolution of I2. Due to difficulties of access to complex descriptors of these processes, each student was asked to explain the phenomena using words and drawings. The results of these investigations were analyzed, and enabled construction of a framework representing the Chemistry students' theoretical training, especially with respect to their most important transferred skill: an ability to model the physical world.

Composição química e atividade biológica de extrato oleoso de própolis: uma alternativa ao extrato etanólico

Propolis is mostly used as hydroalcoholic extract. Recently there has been a growing number of patents dealing with new solvents for preparing propolis extracts. This study aimed to prepare edible oil propolis extracts and compare their chemical composition and biological activity with ethanolic propolis extracts. ESI-MS and spectrophotometric methods were used for qualitative and quantitative analyses, respectively. Antibacterial activity was evaluated by diffusion in agar. Cytotoxicity was tested by MTT assay using tumor cell lines. The oil is able to extract bioactive compounds from propolis. Further studies are needed to improve extraction efficiency and to characterize the active components.

Artigos científicos como recurso didático no ensino superior de Química

Chemistry teachers increasingly use research articles in their undergraduate courses. This trend arises from current pedagogical emphasis on active learning and scientific process. In this paper, we describe some educational experiences on the use of research articles in chemistry higher education. Additionally, we present our own conclusions on the use of such methodology applied to a scientific communication course offered to undergraduate chemistry students at the University of São Paulo, Brazil.

Um panorama sobre a abordagem ambiental no currículo de cursos de formação inicial de professores de química da região sudeste

This work analysed the contents of 701 disciplines from 22 chemistry courses that prepare chemistry teachers in 16 public Universities in Southeastern Brazil. Only a small number (23) of disciplines showed an explicit relationship between human activities and the environment. A total of 11 theoretical and 193 experimental disciplines explored to some extent scientific and technological aspects related to the environment, but did not include their relationship with society. As the experimental disciplines supposedly include some kind of waste treatment, this may explain why secondary school chemistry teachers work mainly on recycling programs and waste issues at their schools. The aim of this work is to provide information on which to base a much needed discussion about how to better prepare our chemistry teachers to act as Environmental Educators at school, as the Brazilian Education Legislation requires.

Determinação potenciométrica da concentração micelar crítica de surfactantes: uma nova aplicação metodológica no ensino de Química

The participation of the students in the planning, execution and discussion of experimental results is important for the valuation of the role of them in the construction of the chemical knowledge implicited in the approach between education and research. This work relates either the construction of selective membrane electrodes for surfactants and its application in the potenciometric determination of the critical micellar concentration of the sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) surfactants. In adition it´s possible to discuss the potenciometric results in matching with the data valued for the tensiometric and condutimetric traditionally used in the physical-chemistry lessons.

A química orgânica na consolidação dos conceitos de átomo e molécula

The present work discusses the appearance of the concepts of valence and molecular structure, and describes the appropriation and evolution of the concept of molecule in the period following the publication of Avogadro's Hypothesis. The point of reference is the development of what became known as Organic Chemistry, which encompassed Pharmacy, Physiological Chemistry, Animal and Plant Chemistry, Chemistry of Dyestuffs, Agricultural Chemistry, and the fledgling Organic Synthesis industry in the early 19th century. The theories formulated in these areas and the quest for accurate atomic weights led to those concepts of valence and molecular structure and to a precise differentiation between atom and molecule.

Aproveitamento sustentável de biomassa e de recursos naturais na inovação química

Increased production of biomass is currently the only immediately accessible alternative for large-scale carbon sequestration and it can produce large amounts of food, fuel and raw materials for the chemical industry that can in turn growingly replace oil as a source of organic building blocks and also of hydrogen and sulfur. Development of processes for biomass and abundant minerals transformation into chemical raw materials should now benefit from large inputs from nanotechnologies, biotechnologies, information and micro-reactor technologies. Success in R&D&Innovation along this line can yield new products and processes needed to perform desirable functions within a sustainable development paradigm.

Potencialidades e oportunidades na química da sacarose e outros açúcares

Non-renewable biomass, such as coal, oil and natural gas are not only energy sources but also important starting materials for the production of a variety of chemicals ranging from gasoline, diesel oil and fine chemicals. In this regard, carbohydrates, the most abundant class of enantiopure organic compounds, are very suitable for generation of chemicals of great practical value. Their bulk-scale availability associated with low cost make them unique starting materials for organic preparative purpose. They are a most attractive alternative for construction of enantiopure target molecules by asymmetric synthesis. This review addresses, in addition to the use of low molecular weight carbohydrates, issues related to renewable biomass from photosynthesis and alternatives for the production of bulk and fine chemicals.

Aplicações de fibras lignocelulósicas na química de polímeros e em compósitos

The use of lignocellulosic fibers and their constituents, as raw materials in the production of polymeric and composite materials, represent an exceptional opportunity of sustainable technological development. In the present report works that discuss promising alternatives of obtaining and use of materials such as cellulose, hemicellulose, lignin, cellulose nanocrystals and biocomposites were revised. The advance in the use of biomass can be, in a near future, capable of going beyond the application difficulties of these vast materials, especially in relation to the economical unviability, by the production of high performance polymeric and composite materials. This advance would represent a higher profitability to some areas of agrobusiness, especially the sector of biofuels, which produces elevated amounts of biomass waste.

Modificação química de argilas: desafios científicos e tecnológicos para obtenção de novos produtos com maior valor agregado

Chemical modification of clays is possible due to their ion-exchange and adsorption capacities, which allows the adjustment of the physicochemical properties of the surfaces of their layers. This modification makes possible the use of clays to produce a great number of new materials, which range from coarse applications such as oil based drilling fluids to refined applications such as pharmaceutical products. This article intends to expose where there is still space for research and investment aiming at the performance improvement of clay-based materials.

Interesterificação química de óleo de soja e óleo de soja totalmente hidrogenado: influência do tempo de reação

Chemical interesterification is an important alternative to produce zero trans fats. In practice, however, excessive reaction times are used to ensure complete randomization. This work evaluated the influence of the reaction time on the interesterification of soybean oil/fully hydrogenated soybean oil blend, carried out in the following conditions: 100 ºC, 500 rpm stirring speed, 0.4% (w/w) sodium methoxide catalyst. The triacylglycerol composition, solid fat content and melting point analysis showed that the reaction was very fast, reaching the equilibrium within 5 min. This result suggests the interesterification can be performed in substantially lower times, with reduction in process costs.

Biofouling e biodeterioração química de argamassa de cimento portland em reservatório de usina hidroelétrica

Last decade Brazilian rivers experimented progressive biofouling of Limnoperna fortunei communities and Cordylophora caspia hydroids. The microhabitat is so favorable that in around 1.5 years L. fortunei increased from 0.39 to nearby 149,000 units/m². Ten Portland cement mortar samples were produced with 1: 3.5: 0.4 dosages and installed for 1 year at Salto Caxias Brazilian Power Plant reservoir in 0.5 m and 1.0 m deep to investigate the biofouling influence on hydraulic civil structures. SEM, EDS, visual investigation and XRF results indicate none direct chemical interrelationships between L. fortunei and the mortar samples. However C. caspia diminished the mortar surface resistance and caused cement paste leaching.