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Química Nova, Volume: 34, Issue: 10, Published: 2011
  • O sucesso do ano internacional da química no Brasil Editorial

    Rezende, Claudia Moraes de; Ferreira, Vitor F.
  • Dyes markers of fuels: legislation and analytical methods for detection Revisão

    Trindade, Magno Aparecido Gonçalves; Stradiotto, Nelson Ramos; Zanoni, Maria Valnice Boldrin

    Abstract in English:

    The use of dyes in the commercialization of fuel is usually associated with protection of the source and destination. It is used as "markers" to identify and guarantee the identity of the specific product of a particular manufacturer to discourage theft, tampering and disclosure of the quality of solvent or fuel. This work presents a critical analysis on the state of the art about the available analytical methods for identification and quantification of dyes used as markers of solvents and fuels, as well as evaluation of the physical-chemical staining and laws surrounding their use and commercialization.
  • Magnetic nanocomposites: potential for applications in Biomedicine Revisão

    Souza, Karynne Cristina de; Mohallem, Nelcy Della Santina; Sousa, Edésia Martins Barros de

    Abstract in English:

    The synthesis of magnetic materials such as nanostructured iron oxide has been intensively researched due to their broad applications in biomedicine. As these nanoparticles have high specific surface area, they are very reactive and can aggregate easily, and biodegrade when exposed to biological systems. Mesoporous silica is often employed as support matrix to protect the magnetic functional component, avoiding undesirable effects. In this context, this review describes various syntheses of silica-coated iron oxide nanoparticles, and their use in applications such as bioseparation, magnetic resonance imaging, hyperthermia and drug delivery systems showing the growing interest of these materials in biological area.
  • Current stage of development of GTL technology and perspectives for Brazil Revisão

    Ramos, André Luis Dantas; Marques, José Jailton; Santos, Vagner dos; Freitas, Lisiane dos Santos; Santos, Rosanne Graziele Vieira de Melo; Souza, Mariana de Mattos Vieira Mello

    Abstract in English:

    Although the production of liquid fuels from coal, natural gas (CTL and GTL processes) and other carbon sources has been discovered 90 years ago, the interest was renewed in the last years motivated by stranded gas reserves and by petroleum market instability. This review intends to show the scenario of these technologies nowadays, discussing the applied technologies, the steps in an industrial plant, the ways to produce syngas and liquid fuels, the catalysts used, the type of reactors and the operating plants with their respective capacities, besides the technical, economical and environmental viability, challenges and perspectives for Brazil.
  • Forensic chemistry: perspective of new analytical methods applied to documentoscopy, ballistic and drugs of abuse Revisão

    Romão, Wanderson; Schwab, Nicolas V; Bueno, Maria Izabel M. S; Sparrapan, Regina; Eberlin, Marcos N; Martiny, Andrea; Sabino, Bruno D; Maldaner, Adriano O

    Abstract in English:

    In this review recent methods developed and applied to solve criminal occurences related to documentoscopy, ballistic and drugs of abuse are discussed. In documentoscopy, aging of ink writings, the sequence of line crossings and counterfeiting of documents are aspects to be solved with reproducible, fast and non-destructive methods. In ballistic, the industries are currently producing ''lead-free'' or ''nontoxic'' handgun ammunitions, so new methods of gunshot residues characterization are being presented. For drugs analysis, easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to provide a relatively simple and selective screening tool to distinguish m-CPP and amphetamines (MDMA) tablets, cocaine and LSD.
  • Mechanisms involved in the biodegradation of lignocellulosic materials and related technological applications Revisão

    Aguiar, André; Ferraz, André

    Abstract in English:

    The biodegradation of lignocellulosic materials is an important natural process because it is responsible for the carbon recycling. When induced under controlled conditions, this process can be used for technological applications such as biopulping, biobleaching of cellulosic pulps, pre-treatment for subsequent saccharification and cellulosic-ethanol production, and increase of the digestibility in agroindustrial residues used for animal feed. In the present work, the enzymatic and non-enzymatic mechanisms involved in the biodegradation of lignocellulosic materials by fungi were reviewed. Furthermore, the technological applications of these extracellular metabolites are presented and discussed.
  • The intriguing biochemistry of the niacin: a critical review Revisão

    Maria, Carlos Alberto Bastos de; Moreira, Ricardo Felipe Alves

    Abstract in English:

    Niacin (nicotinamide, nicotinic acid) interferes on homeostasis, DNA regulation, signaling and longevity. Nicotinic acid reduces synthesis of lipoproteins-apo-B and increases HDL. Its antilipemic action in liver produces: 1) inhibition of DGAT2, with decreased triacylglycerol synthesis, 2) downregulation of the b-chain of adenosine triphosphate synthase, leading to reduced HDL-apo-A-I catabolism. Nicotinic acid could increase redox potential in vascular endothelium. HM74A receptor activation in macrophages would be responsible for the release of prostaglandins, causing flushing in epidermis. HM74A agonists could assist in identifying antilipemic agents. Extended release niacin in combination with statin appears to protect cardiovascular system of patients with low HDL.
  • Flow injection analysis with multiple pulse amperometric detection: potentialities and applications Revisão

    Santos, Wallans Torres Pio dos; Gimenes, Denise Tofanello; Richter, Eduardo Mathias; Angnes, Lúcio

    Abstract in English:

    The potentialities and applications of the Multiple Pulse Amperometric detection (MPA) coupled with Flow Injection Analysis (FIA) are evaluated. Important aspects as cleaning and activation of electrode surface, indirect and simultaneous analysis of electroactive compounds and the use of the internal standard method for quantifications utilizing FIA-MPA are presented. The main parameters concerning the detection of electroactive analytes by multiple pulse amperometric detection in flowing solutions were also discussed. In addition, aspects such as flow rate, sample volume, application time of the potential pulses and instrumentation necessary for implementing of the method were also addressed.
  • Solid lipid nanoparticles: classical methods of lab production Revisão

    Souto, Eliana B; Severino, Patrícia; Santana, Maria Helena A; Pinho, Samantha C

    Abstract in English:

    Solid lipid nanoparticles have been extensively investigated as drug delivery systems. These colloidal systems have major advantages compared to others more traditional. Reported advantages include sustained release, ability to solubilize lipophilic drugs, increased physical and chemical stability of labile molecules, decreased unwanted side-effects showing lower toxicity, and scale up facilities. This paper aims at reviewing the traditional methods of solid lipid nanoparticles production, such as fusion-emulsification (hot and cold), solvent evaporation-emulsification and microemulsion, dealing with the main technological parameters that influence the quality properties of solid lipid nanoparticles.
  • Integrating virtual and high-throughput screening: opportunities and challenges in drug research and development Revisão

    Ferreira, Rafaela S; Glaucius, Oliva; Andricopulo, Adriano D

    Abstract in English:

    High-throughput screening (HTS) and virtual screening (VS) are useful methods employed in drug discovery, allowing the identification of promising hits for lead optimization. The efficiency of these approaches depends on a number of factors, such as the organization of high quality databases of compounds and the parameterization of essential components of the screen process. This brief review presents the basic principles of the HTS and VS methods, as well as a perspective of the utility and integration of these drug design approaches, highlighting current opportunities and future challenges in medicinal chemistry.
  • The challenge of C-H activation in organic synthesis Revisão

    Azambuja, Francisco de; Correia, Carlos Roque Duarte

    Abstract in English:

    This review aims at to the presentation and discussion of the principal aspects of the C-H activation by transition metals. Representative examples were selected from the recent literature to illustrate these principles beginning with somewhat simple examples and moving up to more complex ones. The synthetic potential of the C-H activation, as well as the potential advantages and disadvantages of the methodology are highlighted with relevant recent examples, along with brief insights on the mechanism aspects of these reactions.
  • The "click" reaction in the synthesis of 1,2,3-triazoles: chemical aspects and applications Revisão

    Freitas, Luiza Baptista de Oliveira; Ruela, Fernando Armini; Pereira, Guilherme Rocha; Alves, Rosemeire Brondi; Freitas, Rossimiriam Pereira de; Santos, Leandro José dos

    Abstract in English:

    The Copper-catalyzed azide-alkyne cycloaddition (CuAAC), often referred to as "click" reaction, has become a very popular reaction in the last years. It affords exclusively 1,4-disubstituted 1,2,3-triazoles and has been widely used to connect readily accessible building blocks containing various functional groups. The great success of this reaction is based on the fact that it is general, virtually quantitative and very robuste. The scope of this copper-catalyzed synthesis is extraordinary and the reaction has found numerous applications in many research fields, including biological chemistry and materials science. In this review, the main chemical aspects and applications of the "click" reaction in the synthesis of 1,2,3-triazoles are presented.
  • Notions of future Chemistry professionals. axis I: research liberties and demands Educação

    Strack, Ricardo; Pino, José Claudio Del

    Abstract in English:

    During the schooling process, images are constructed about research and researcher activities. Based on that, a questionnaire has been structured based on three thematic axes that tend to represent some of the discussions about the translations that integrate the scientific activity collectively: freedom and demands from research, academia as a mediator and science disclosure. The objective of the instrument was to map some notions from entrants to the graduation course in Chemistry in the metropolitan region of Porto Alegre about what, based on the contributions by Bruno Latour, was called vascularizations of research.
  • Business games: application to quality management in undergraduate chemistry teaching Educação

    Olivares, Igor R. B; Costa, Diana La Luna Bissetti; Queiroz, Salete Linhares

    Abstract in English:

    Business games have become a popular choice of pedagogical technique for teaching in higher education. The objective of a business game is to offer students the opportunity to learn by doing, engaging them in a simulated experience of the real-world. This paper discusses how a business game has been played by undergraduate chemistry students in a Quality Management course. The responses from the teaching evaluation questionnaires revealed that they not only improved their quality management practices, but also enjoyed working in teams. The level of participation by students was good and the classroom activities provided a meaningful learning experience.
  • Conceiving an experimental discipline: a contribution to general chemistry Educação

    Simoni, Deborah de Alencar; Andrade, João Carlos de; Simoni, José de Alencar

    Abstract in English:

    The purpose of this paper is to present a classification criterion for general chemistry experiments departing from a survey of 35 years of the experimental general chemistry discipline at the Chemistry Institute - UNICAMP. It is shown that by considering the most remarkable characteristics of an experiment and classifying it under Conceptual, Fundamental, Methodological or Quantitative criterion, teachers could better develop the discipline plan and prevent a subject superposition. Taking into account the system Fe3+/SCN- , the article also exemplify how is possible to modify an experimental approach and to conceive other procedures with different didactic purposes.
  • Effects of the thermal history on thermal properties of polymers: an experiment for thermal analysis education Educação

    Bannach, Gilbert; Perpétuo, Glauco Lini; Cavalheiro, Éder Tadeu Gomes; Cavalheiro, Carla Cristina Schmitt; Rocha, Rafael Rodrigo

    Abstract in English:

    Polyethilenetherephtalate (PET) is commonly used in manufacturing of beverage bottles representing a didactic appeal in thermal analysis education due to its presence in the student's day life. Additionally such polymer presents well defined thermal analytical curves and a well known thermal behavior. TGA curve is used to present the thermal stability. The thermal history effects in the thermal properties of a PET sample from a soft drink bottle are used to demonstrate the effect of different heating/cooling conditions on glass transition, melting, crystallization and crystalline degree using DSC curves.
  • Theoretical and experimental crystal field theory treatment in the inorganic synthesis course Educação

    Leal, Bárbara C; Luza, Leandro; Baibich, Ione M; Consorti, Crestina S

    Abstract in English:

    We describe herein the synthesis and characterization of the complexes KNiF3, [Ni(en)3]I2, [Ni(en)3]Cl2, [Ni(acac)2(H2O)2], [Ni(en)2(H2O)2]Cl2 and [Ni(NH3)6](BF4)2 (en = ethylenediamine, acac- = acetylacetonate) performed in the inorganic synthesis major course at the Chemistry Institute of UFRGS (Universidade Federal do Rio Grande do Sul). The compounds were characterized by infrared and electronic spectroscopy and the electrolytic conductivity was measured. The parameters 10Dq and B were obtained from the electronic spectra and the nefelauxetic and spectrochemical series were determined. The obtained spectrochemical series was F- < acac- < NH3 < en and the nefeulaxetic series was en < NH3 < acac- < F-.
  • Conceptual problems in the learning of chemical equilibrium through acid-base reactions Educação

    Bertotti, Mauro

    Abstract in English:

    Common student misunderstandings regarding chemical equilibrium are reported taking into account the response of freshman students to some typical questions involving acid-base reactions. Language has been shown to be one of the main issues associated with students' difficulties on this subject, such as in the case of concentration and amount of substance (mol). Another usual problem was observed in questions involving buffer solutions after addition of a reagent. A number of recommendations have emerged from the results presented in this work as an attempt to enhance the learning of this topic in general chemistry courses given to first-year students.
  • College-level chemistry education: reflections based on core organic chemistry concepts Educação

    Rodrigues, Salomão Bento de Vasconcelos; Da-Silva, Dayse Carvalho; Quadros, Ana Luiza de

    Abstract in English:

    We live in a context in which knowledge develops continuously and rapidly. This generates a social dynamics that demands constant adaptation from those living in society and also from educational institutions. Education for this new society needs to be rethought. Universities, anchored in tradition, still use a transmission/reception model of education. A data-collecting instrument applied to undergraduate chemistry students at the end of the course in organic chemistry investigated some concepts essential to the education of a chemist, such as interatomic and intermolecular interactions and Lewis structure. We observed that students have difficulty dealing with these concepts, and we believe that this is related to the type of class they had/have and to the way the concepts are presented in the college textbooks.
  • The electronegativity concept in the secondary education and in the university education Educação

    Santos, Camila Maria Andrade dos; Silva, Ricardo Alexandre Galdino da; Wartha, Edson José

    Abstract in English:

    The goal of this study was to examine the means used by textbook authors to introduce, define, and explain the electronegativity concept in high school and introductory college chemistry textbooks. Results obtained showed that most textbooks lacked history precedence and did not deal with the conceptual understanding and manifesting a strong standardization of characteristics that, from our point of view, do not favor the teaching-learning of the electronegativity concept.
  • Technology transfer process from university to industry: a case study involving of glycerol convertion Assuntos Gerais

    Silva, Adilson C; Oliveira, Luiz C. A; Nogueira, Francisco G. E; Nogueira, Andre E

    Abstract in English:

    Currently, public policy has encouraged innovation in universities and also transference of technology to the industry. Another important stage to be considered would be the registration or filing of a patent and the economical viability study. Government programs, such as the innovation incentive program, among others, should facilitate popularization and promote interest by industry. In this work we described the steps, from the conception of the idea to the scale up going through its interest by the industry. The case study is about the glycerol conversion utilizing modified niobia as catalysts.
  • Actions regarding the dissemination of chemistry at Casa da Descoberta - a scientific dissemination center of the Fluminense Federal University Assuntos Gerais

    Borges, Márcia N; Ribeiro, Carlos Magno R; Araripe, Denise R; Chacon, Eluzir P; Coutinho, Lucidéa G. R; Luz, Daisy M

    Abstract in English:

    This paper describes the main activities regarding scientific dissemination in the field of Chemistry at Casa da Descoberta (CD) - a Scientific Dissemination Center of the Fluminense Federal University. It presents a brief history of CD and discusses the difficulties concerning the dissemination of Chemistry at Scientific Dissemination Centers. This work also approaches some activities developed throughout the years: experiments performed in relation to the visitors' daily life, training of monitors to act as mediators in the non-formal teaching of Chemistry, production of dissemination materials, elaboration of books, as well as activities that relate formal to non-formal education.
  • Linear vs convergent synthetic pathway: which is greener? Assuntos Gerais

    Machado, Adélio A. S. C

    Abstract in English:

    A comparative study of a convergent and the linear synthetic pathway with respect to their relative greenish allowed the quantification of the advantages of the former with respect to atomic productivity as well as robustness. The calculations show that convergent pathways provide a decrease of costs together with a decrease of E factor and an increase of atomic economy which means that greenish is accompanied by an economic advantage. The influence of other features of the convergent pathways synthesis on the improvement of the synthesis greenish is discussed qualitatively.
  • Definition of shelf life for chemical product: the importance of a especific stability guide for the segment Assuntos Gerais

    Oriqui, Luciana R; Mori, Milton; Wongtschowski, Pedro; Freitas, Saulo R; Santos, José Guilherme M

    Abstract in English:

    The chemical industries worldwide are passing through a very particular moment of re-adaptation due to the implementation of an European regulation called, Registration, Evaluation, Authorization and Restriction of Chemicals (REACH). In Brazil, the Brazilian Chemical Industry needs urgently a specific guide of chemical products stability. The main purpose of this work is to present a proposal of a guide of stability for chemical products based on the reference guides of the International Conference on Harmonization (ICH). Thus, this work proposes an innovation in terms of methodology which will be useful for shelf life definition purpose for chemical industry products.
  • Mass spectrometry nomenclature in portuguese language Assuntos Gerais

    Vessecchi, Ricardo; Lopes, Norberto Peporine; Gozzo, Fábio Cesar; Dörr, Felipe Augusto; Murgu, Michael; Lebre, Daniel Temponi; Abreu, Renato; Bustillos, Oscar Vega; Riveros, José Manuel

    Abstract in English:

    In commemoration of the International Year of Chemistry this article presents the normalization and standardization of key terms used in mass spectrometry in Portuguese Language.
  • Historical aspects of Marie Sklodowska Curie visit to Belo Horizonte Assuntos Gerais

    Nascimento, Cássius Klay; Braga, João Pedro

    Abstract in English:

    In the year 2011 it is celebrated the Marie Sklodowska Curie Nobel Prize centenary and the International Year of Chemistry. However, it is not generally known that Marie Sklodowska Curie, one of the greatest scientists of all time, visited Belo Horizonte, state of Minas Gerais, Brazil. She arrived by train at Belo Horizonte city on 16 August 1926, coming from Rio de Janeiro and accompanied by her daughter Irène Joliot-Curie. The scientists visited the Institute of Radium of Belo Horizonte. The approach in this work emphasizes the presence of Marie Sklodowska Curie in Belo Horizonte, exploring the admiration and respect that people had for her.
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