38 resultados para Paper chemicals
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The main objective of this work was to compare two methods to estimate the deposition of pesticide applied by aerial spraying. Hundred and fifty pieces of water sensitive paper were distributed over an area of 50 m length by 75 m width for sampling droplets sprayed by an aircraft calibrated to apply a spray volume of 32 L/ha. The samples were analysed by visual microscopic method using NG 2 Porton graticule and by an image analyser computer program. The results reached by visual microscopic method were the following: volume median diameter, 398±62 mum; number median diameter, 159±22 mum; droplet density, 22.5±7.0 droplets/cm² and estimated deposited volume, 22.2±9.4 L/ha. The respective ones reached with the computer program were: 402±58 mum, 161±32 mum, 21.9±7.5 droplets/cm² and 21.9±9.2 L/ha. Graphs of the spatial distribution of droplet density and deposited spray volume on the area were produced by the computer program.
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The contribution of the industrial activities to the environmental contamination phenomena is evident. Great efforts are dedicated to the establishment of methodologies which permits an adequate treatment of the produced effluents, as a manner of minimizing the environmental impact of these wastes. The methodologies based on photocatalytic processes are very promise alternatives, because permits degradation of a great number of chemical substances of high toxic potential, without the use of other chemicals. The present work is an overview about the principal environmental aspects related with the paper and cellulose industry and the main alternatives employed for the reduction of environmental impact produced for its residues. The principal results of the photocatalytic treatment of this kind of effluents using metallic semiconductors is also showed.
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This work presents a detailed routine applied to the identification of unknown chemicals and wastes. 786 specimens were analyzed during 20 months. Unknown materials fell into three basic classes: (i) commercial chemicals without labels or illegible ones; (ii) laboratory synthesis products; (iii) used solvents (including mixtures). Uranium and thorium were recovered form their wastes. Unknown chemicals were mainly inorganic compounds, many of which had never been opened. Alkaline salts were dominant, but also precious metal compounds were identified. Laboratory synthesis products were organic compounds. The final destination depended on the nature of the chemical. Most organic compounds were sent to incineration; inorganic salts were distributed among several public organizations, including secondary and technical schools. The work described in this paper greatly reduced the amount of wastes that had to be sent to disposal.
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Fumonisins are mycotoxins occurring worldwide, mainly in maize and maize-based food products, which could affect animal and human health. This paper reviews analytical methodologies for the determination of these fungal toxins in foods. It includes extraction, cleanup, derivatization procedures, detection, quantification, and confirmation procedures. Initial attempts at gas chromatographic methods and thin layer chromatography were supplanted by liquid chromatographic methods, mainly performed with fluorometric detection, or mass spectrometry detection, enabling the analysis of polar and thermolabile chemicals without chemical derivatization, which results in lower limits of detection. Alternative methods, such as enzyme linked immunosorbent assay or zone capillary zone electrophoresis, are also described.
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Catalysis by solid acids has received much attention due to its importance in petroleum refining and petrochemical processes. Relatively few studies have focused on catalysis by bases and even les on using basic molecular sieves. This paper deals with the potential application of micro and mesoporous molecular sieves in base catalysis reactions. The paper is divided in two parts, the first one dedicated to the design of the catalysts and the second to some relevant examples of catalytic reactions, which find a huge field of applications essentially in the synthesis of fine chemicals. Here, recent developments in catalysis by basic molecular sieves and the perspectives of applications in correlated catalytic processes are described.
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The presence of illicit drugs such as cocaine and marijuana in US paper currency is very well demonstrated. However, there is no published study describing the presence of cocaine and/or other illicit drugs in Brazilian paper currency. In this study, Brazilian banknotes were collected from nine cities, extracted and analyzed by capillary gas chromatography/mass spectrometry, in order to investigate the presence of cocaine. Bills were extracted with deionized water followed by ethyl acetate. Results showed that 93% of the bills presented cocaine in a concentration range of 2.38-275.10 µg/bill.
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ABSTRACT The main aim of this paper was to contribute to reflections in Brazil on the need to transfer knowledge held at universities and R&D institutions over to companies, i.e. to transfer scientific knowledge of chemistry to technology. It discusses how the competitiveness of countries is increasingly dependent on their technological capacity. The chemicals industry is a fundamental driver of social, environmental, economic and industrial indicators of sustainable development. In Brazil, the chemicals industry's deficit has grown over the last three decades. Patents are important sources of information because patent documents contain 75% of all technological information available. The National Institute of Industrial Property in Brazil has created a Technology Observatory with the purpose of identifying and analyzing technological information contained in patent documents within the ambit of partnerships with government entities or business associations, in order to support their technology-related decision-making processes. The paper gives examples of ethanol and biotechnology patent documents, including pharmaceuticals, of which there are very few in Brazil. However, a few of the patent applications identified are filed in Brazil, giving the country the opportunity to transform this scientific knowledge into technology by means of partnership agreements with companies. Finally, the paper presents information on the patent applications filed by the world's leading chemicals companies as measured by their revenues, and the respective numbers of patent applications in the last five years in organic chemistry and polymers, sectors in which Brazil is currently dependent on imports for over 50% of its needs. The patent assignees in these sectors in Brazil are also identified, and the paper concludes that Brazil needs to invest in the development of professionals, providing clearly-defined career paths in technology innovation teams at R&D institutions, and to foster more initiatives such as the creation of a new research and innovation entity, EMBRAPII, since investing in science and technology is a prerequisite for knowledge production, industrial property, economic development and, consequently, the competitiveness of the country.
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Coal, oil, natural gas, and shale gas are biomass that is formed millions of years ago. These are non-renewable and depleting, even considering the recent discovery of new sources of oil in the presalt and new technologies for the exploitation of shale deposits. Currently, these raw materials are used as a source of energy production and are also important for the production of fine chemicals. Since these materials are finite and their (oil) price is increasing, it is clear that there will be a progressive increase in the chemical industry to use renewable raw materials as a source of energy, an inevitable necessity for humanity. The major challenge for the society in the twenty first century is to unite governments, universities, research centers, and corporations to jointly act in all areas of science with one goal of finding a solution to global problems, such as conversion of biomass into compounds for the fine chemical industry.Non-renewable raw materials are used in the preparation of fuels, chemical intermediates, and derivatives for the fine chemical industry. However, their stock in nature has a finite duration, and their price is high and will likely increase with their depletion. In this scenario, the alternative is to use renewable biomass as a replacement for petrochemicals in the production of fine chemicals. As the production of biomass-based carbohydrates is the most abundant in nature, it is judicious to develop technologies for the generation of chain products (fuels, chemical intermediates, and derivatives for the fine chemicals industry) using this raw material. This paper presents some aspects and opportunities in the area of carbohydrate chemistry toward the generation of compounds for the fine chemical industry.
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The chemistry of natural products has been remarkably growing in the past few decades in Brazil. Aspects related to the isolation and identification of new natural products, as well as their biological activities, have been achieved in different laboratories working on this subject in the country. More recently, the introduction of new molecular biology tools has strongly influenced the research on natural products, mainly those produced by microorganisms, creating new possibilities to assess the chemical diversity of secondary metabolites. This paper describes some ideas on how the research on natural products can have a considerable input from molecular biology in the generation of chemical diversity. We also explore the role of microbial natural products in mediating interspecific interactions and their relevance to ecological studies. Examples of the generation of chemical diversity are highlighted by using genome mining, mutasynthesis, combinatorial biosynthesis, metagenomics, and synthetic biology, while some aspects of microbial ecology are also discussed. The idea to bring up this topic is linked to the remarkable development of molecular biology techniques to generate useful chemicals from different organisms. Here, we focus mainly on microorganisms, even though similar approaches have also been applied to the study of plants and other organisms. Investigations in the frontier of chemistry and biology require interactions between different areas, characterizing the interdisciplinarity of this research field. The necessity of a real integration of chemistry and biology is pivotal to finding correct answers to a number of biological phenomena. The use of molecular biology tools to generate chemical diversity and control biosynthetic pathways is largely explored in the production of important biologically active compounds. Finally, we briefly comment on the Brazilian organization of research in this area, the necessity of new strategies for the graduation programs, and the establishment of networks as a way of organization to overcome some of the problems faced in the area of natural products.
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Chlorine, one of the most frequent elements on earth and most important key chemicals, is indispensable in the syllabi of school and university courses in Inorganic Chemistry. However, its toxicity and high volatility preclude experimental demonstration of its properties in secondary and high schools and most university labs. This paper summarises the industrial role of chlorine and presents miniaturised experiments demonstrating some of the processes used in Industrial Inorganic Chemistry. Furthermore, experiments illustrating important concepts of Inorganic Chemistry such as Ion Bonding and Molecular Orbital Theory are describe.
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Acacia mearnsii de Wild (black wattle) is one of the most important trees planted in Southern Brazil for tannin extraction and charcoal production. The pyrolysis of the black wattle wood used for obtaining charcoal is performed in brick ovens, with the gas fraction being sent directly into the environment. The present study examines the condensable compounds present in the liquor produced from black wattle wood at different thermal degradation conditions, using gas chromatography coupled with mass spectrometry (GC/MS). Branches of black wattle were thermally degraded at controlled ambient and temperature conditions. Overall, a higher variety of compounds were obtained under atmospheric air pressure than under synthetic air pressure. Most of the tentatively identified compounds, such as carboxylic acids, phenols, aldehydes, and low molecular mass lignin fragments, such as guayacol, syringol, and eugenol, were products of lignin thermoconversion. Substituted aromatic compounds, such as vanillin, ethyl vanillin, and 2-methoxy-4-propeny-phenol, were also identified. At temperatures above 200 ºC, furan, 2-acetylfuran, methyl-2-furoate, and furfural, amongst others, were identified as polysaccharide derivatives from cellulose and hemicellulose depolymerization. This study evidences the need for adequate management of the condensable by-products of charcoal production, both for economic reasons and for controlling their potential environmental impact.
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Fungi require special substrates for their isolation, vegetative growth and sporulation. In experiments conducted in the laboratory, the influence of substrates, light, filter paper and pH on the sporulation of Cercospora sojina conidia, the causal agent of soybean frogeye leaf spot, was assessed. The media potato sucrose agar, V-8 agar, tomato extract agar, soybean leaf extract agar, soybean seed extract agar, soybean meal agar, soybean flour agar and wheat flour agar were tested, added on the surface, with and without filter paper and under two light regimes, with 12 h light at 25°± 2°C and in the dark. A triple factorial 8x2x2 (substrates x light/dark x with/without filter paper) design with four replicates was used. V-8 agar medium was employed and the pH was adjusted with HCl 0.1N or NaOH 0.1N before autoclaving to the values: 3, 4, 5, 6, 7 and 8, and the pH of V-8 agar medium is 6.7. The evaluation was done on the seventh day of incubation. Data underwent regression analysis. Sporulation was maximized on the agar media V-8, seed extract, oat flour, tomato extract, and potato sucrose in the presence of filter paper and 12h light. On V-8 medium, maximal sporulation was obtained with pH 6.7.
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A biodiversidade existente no cerrado está seriamente ameaçada pela devastação, pois muitas das espécies que aí ocorrem possuem distribuição geográfica restrita. Pela posição central do cerrado no continente sul-americano, ocorrem associações entre a vegetação do cerrado e outras formações, dentre estas a floresta paludícola. Os objetivos deste trabalho foram conhecer a flora e descrever a comunidade arbustivo-arbórea de um cerradão e da transição entre esse cerradão e uma floresta paludícola em Brotas, e investigar as similaridades e diferenças florísticas entre levantamentos realizados em fisionomias similares no estado de São Paulo. No fragmento ocorreram 125 espécies de 91 gêneros e 49 famílias. Myrtaceae e Leguminosae foram as famílias mais ricas em espécies, um padrão consistente com o encontrado em outros levantamentos nos cerrados paulistas. Somente em Brotas, Lauraceae e Euphorbiaceae apresentaram alta riqueza específica. No levantamento fitossociológico, em 1,0 ha, foram amostrados 3.787 indivíduos com DAS > 3 cm (H' = 3,378 nats.indivíduo-1). As espécies de maior importância sociológica foram Xylopia aromatica, Vochysia tucanorum, Ocotea pulchella, Gochnatia polymorpha e Myrcia albo-tomentosa. Não foi encontrada correlação significativa entre a similaridade florística e a distância geográfica entre as 10 áreas de cerrado analisadas, devido à grande proporção de espécies comuns. Essa grande proporção de espécies comuns corrobora resultados de outros autores, de que o estado de São Paulo se localiza num centro de diversidade do cerrado, cuja composição florística é diferente de outros centros de diversidade no Brasil.
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F1-antigen purified from Yersinia pestis was covalently linked to 5-mm diameter filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde. These discs were used both for ELISA and dot-ELISA for the detection of anti-F1 IgG in rabbits. The best conditions were achieved using 1.25 µg of F1 antigen/disc, 3% w/v skim milk in PBS as blocking agent, anti-IgG peroxidase conjugate diluted 12,000 times, and serum from rabbits immunized or not against Y. pestis, diluted 6,400 times. The absorbance values obtained from the comparative study between this procedure and conventional ELISA were not significantly different but the low cost of the reagents employed in ELISA using the filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde makes this method economically attractive.
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The paper-and-pencil digit-comparison task for assessing negative priming (NP) was introduced, using a referent-size-selection procedure that was demonstrated to enhance the effect. NP is indicated by slower responses to recently ignored items, and proposed within the clinical-experimental framework as a major cognitive index of active suppression of distracting information, critical to executive functioning. The digit-comparison task requires circling digits of a list with digit-asterisk pairs (a baseline measure for digit-selection), and the larger of two digits in each pair of the unrelated (with different digits in successive digit-pairs) and related lists (in which the smaller digit subsequently became a target). A total of 56 students (18-38 years) participated in two experiments that explored practice effects across lists and demonstrated reliable NP, i.e., slowing to complete the related list relative to the unrelated list, (F(2, 44) = 52.42, P < 0.0001). A 3rd experiment examined age-related effects. In the paper-and-pencil digit-comparison task, NP was reliable for the younger (N = 8, 18-24 years) and middle-aged adults (N = 8, 31-54 years), but absent for the older group (N = 8, 68-77 years). NP was also reduced with aging in a computer-implemented digit-comparison task, and preserved in a task typically used to test location-specific NP, accounting for the dissociation between identity- and spatial-based suppression of distractors (Rao R(3, 12) = 16.02, P < 0.0002). Since the paper-and-pencil digit-comparison task can be administered easily, it can be useful for neuropsychologists seeking practical measures of NP that do not require cumbersome technical equipment.