Active center determination of ethylene polymerisation catalysts using a quenching method with tritiated methanol

The subject of this work is ethylene polymerisation using Kaminsky type catalysts: Cp2MR2=methylaluminoxane [M=Zr,W,Nb; R=Cl,CH3]. Active center determination and kinetic studies of the (Cp2WCl2 + methylaluminoxane) and Cp2ZrCl2 + methylaluminoxane) systems are described, using a quenching method with tritiated methanol. The activity of the polymer was determined by liquid scintillation counting. We have found 0.5% and 87% of active centers, respectively for W and Zr system. The catalytic activity of complexes Cp2WCl2 and Cp2NbCl2 was compared with that of Cp2ZrCl2. The W and Nb complexes are found to be less active than the Zr complex.info:eu-repo/semantics/publishedVersio

Synthesis of new pseudo‐C‐nucleosides containing pyrazole rings in their structure

Synthetic approaches to new 4-(furanos-4-C-yl)-1H-pyrazole and 3-(furanos-4-C-yl)-1H-pyrazole derivatives are described, including its pyrazole-5-carboxylate derivative, which is a pyrazofurin analogue. Preparation of related 5-acetoxy-1-acetyl-1H-pyrazole, 5-acetoxy-1H-pyrazole-1-carboxylate, and 4,5-dihydro-1-phenyl-1H-pyrazol-5-one derivatives is also reported. The formation of the pyrazole rings was accomplished either by reaction of enones and of 1,3-diketones with N-nucleophiles or by ring closure of a diazoketone.info:eu-repo/semantics/publishedVersio

A aptidão física de alunos de uma CERCI: Análise com a utilização do teste de Brockport

O trabalho foi realizado durante sensivelmente nove meses na instituição da CERCIESTA, onde lidei com pessoas de diferentes graus de deficiência intelectual (DI). A DI é caracterizada por limitações significativas no funcionamento intelectual e no comportamento adaptativo abrangendo as habilidades conceituais, sociais e práticas quotidianas, aparecendo nas pessoas antes dos 18 anos ("Frequently asked questions on intellectual disability,"). Durante a minha estadia na instituição participei em diferentes atividades, como a Educação Física (EF), a Natação e a Psicomotricidade. Mas o meu estudo baseou-se na análise da aptidão física em aluno que já realizavam atividade física regularmente, comparando-os entre gêneros e com os valores padrões apresentados pelo manual do Teste de Aptidão Física de Brockport (TAFB) (Winnick & Short, 2014). Com uma amostra de 13 elementos, utilizei o manual do TAFB (Winnick & Short, 2014) para realizar uma série de testes que abrangiam as componentes da flexibilidade, da força e resistência muscular, da resistência cardiorrespiratória, e da composição corporal dos diferentes alunos. Para tratar os dados retirados dos testes foi utilizado um programa estatístico, o Statistical Package for the Social Sciences (SPSS) versão 24, onde foram analisadas as estatísticas descritivas e inferenciais. Com o tratamento dos dados, permitiu concluir que: i) não existem diferenças significativas entre os gêneros; ii) o gênero feminino possui melhores valores na flexibilidade; iii) o gênero masculino possui melhores valores na força e resistência muscular; iv) ambos os gêneros apresentam valores baixos de resistência cardiorrespiratória; v) metade dos alunos necessitam de melhorias ao nível da composição corporal; vi) de um modo geral a aptidão física nesta população é fraca.The work was carried out during approximately nine months in the Institution of CERCIESTA, where I dealt with people of different degrees of intellectual disability. Intellectual disability is characterized by significant limitations in intellectual functioning and adaptive behavior encompassing everyday conceptual, social and practical skills, appearing in people before age 18 ("Frequently asked questions on intellectual disability,"). During my stay at the Institution I participated in different activities, such as Physical Education, Swimming and Psychomotricity. However, my study was based on the analysis of physical fitness in students who already performed physical activity regularly, comparing them between genders and with the standard values presented by the Brockport Physical Fitness Test Manual (Winnick & Short, 2014). With a sample of 13 elements, I used the Brockport Physical Fitness Test Manual (Winnick & Short, 2014) to perform a series of tests covering the components of flexibility, muscular strength and endurance, aerobic functioning and body composition of the different students. A statistical program, Statistical Package for the Social Sciences (SPSS), version 24, was used to treat the data taken from the tests, where the descriptive and inferential statistics were analyzed. With the data treatment, it was concluded that: i) there are no significant differences between genders; ii) the female gender has better values in flexibility; iii) male gender has better values in muscular strength and endurance; iv) both genders have low values of aerobic functioning; v) half of the students need improvements in body composition; vi) in general the physical fitness in this population is weak

Synthesis of phenylseleno sugars from epoxides and of α,β-unsaturated carbonyl derivatives for the study of their insecticidal activity

This work reports the synthesis of sugar epoxides and their derivatives obtained by reaction with the dianion of phenyl selenoacetic acid. Approaches to the introduction of α,β-unsaturated carbonyl units in pyranoid systems were investigated. Preparation of a protected D-glycero-hex-3-enepyranosid-2-ulose and of a D-erythro-hex-2-enono-1,5-lactone is described. Some of the synthesized compounds possess insecticidal activity against fruit flies, house flies, and white flies.Treaty of Windsor Programme, British Council, Ministério da Ciência e do Ensino Superiorinfo:eu-repo/semantics/publishedVersio

A kinetic approach to homogeneous Ziegler type polymerization. Transient state

In this paper we present a kinetic approach to the analysis of transient-state homogeneous Ziegler-Natta polymerization activity data. The main features of the experimental data are discussed and fitted to transient kinetic models.info:eu-repo/semantics/publishedVersio

Polymerization of ethylene using metallocene and aluminoxane systems

This paper describes ethylene polymerization using a number of metal-locene and aluminoxane catalyst systems, Cp2MR2 and methylaluminoxane [M = Zr, W, Nb; R = Cl, CH3]. Two types of methylaluminoxane, MAO (1) and MAO (2), were used as cocatalysts. The polymerization activities of the complexes Cp2WCl2 and Cp2NbCl2 were compared with that of Cp2ZrCl2. The Nb and W complexes were found to be less active than the Zr complex. Polyethylene characterization was also carried out by the following methods: gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR).info:eu-repo/semantics/publishedVersio

Homogeneous Ziegler-Natta polymerisation: A kinetic approach .2. Transient-state kinetics

An integrated view is presented of several possible mechanisms applicable to the interpretation of homogeneous Ziegler-Natta polymerisation. In this paper, the transient aspects related to the kinetics of Ziegler-Natta polymerisation are investigated. Extensive data are used to construct kinetic profiles (rM vs. t) from a theoretical approach. Special attention is given to the duration of the transient period as a function of the different kinetic parameters. The kinetic models developed are fitted to experimental data, either directly obtained by the authors or published in the literature. These general models have a broad range of application.info:eu-repo/semantics/publishedVersio

Análisis FODA y matriz GUT para la gestión empresarial y la resolución de problemas: una aplicación en un caso de estudio brasileño

[EN] The present research aims to use SWOT analysis to identify strategic problems of small business companies (SBCs) from the automotive selling parts of a brazilian city and use the GUT matrix for identifying a Priority Level (PL) result of each problem listed. This case-study is expected to bring improvements to the automotive pole in territory, as a way to quantify and prioritize the actions focused on the weaknesses and threats identified though the SWOT analysis (an acronym for strengths, weaknesses, opportunities, and threats and is a structured method that evaluates those four elements on a strategic way), the GUT matrix (technique for priorization and decision making) will be used according its aspects of severity, urgency and tendency. It finds that solving problems of “Low cooperation between the companies” and increase the level of interaction between the companies will increase generation of information. Solve “infrastructure deficiency and accessibility to the Pole” problems will increase the Association’s recognition and representativeness, bringing closer and enabling the gradual implementation of a more adequate governance.[ES] La presente investigación tiene como objetivo utilizar el análisis FODA para identificar problemas estratégicos de pequeñas empresas (SBC) relativos a la venta de automóviles en una ciudad brasileña, y utilizar la matriz GUT para identificar un resultado sobre el Nivel de Prioridad (PL) de cada problema enumerado. Se espera que este caso de estudio traiga mejoras al polo automotriz en el territorio, de tal manera que se cuantifiquen y prioricen las acciones centradas en las debilidades y amenazas identificadas a través del análisis FODA (acrónimo de fortalezas, debilidades, oportunidades y amenazas, el cuál es un método estructurado que evalúa esos cuatro elementos de manera estratégica), y se utilice la matriz GUT (técnica de priorización y toma de decisiones), según aspectos de severidad, urgencia y tendencia. Se considera que resolver problemas de «Baja cooperación entre las empresas» y aumentar el nivel de interacción entre las empresas aumentará la generación de información. Por otro lado, resolver los problemas de «deficiencia de infraestructura y accesibilidad al Polo» aumentará el reconocimiento y la representatividad de la Asociación, acercando y posibilitando la implementación paulatina de una gobernanza más adecuada

Neutron activation analysis of some biological environmental materials

Some biological candidate reference materials were recently or are now being certified for use in quality control of trace element analysis in environmental studies. In this work, the elemental concentration was determined by instrumental neutron activation analysis (INAA) for the materials lichen, poplar leaves, oak tree leaves, eucalyptus leaves and pine needles. As an application of pollution studies, samples of soil and strawberry plants treated with methylbromide as a disinfectant were analysed by INAA. The results evidence contamination with bromide; after several treatments the soil accumulates bromide giving rise to phytoxicity

A new dihydroxysterol from the marine phytoplankton Diacronema sp.

Diacronema sp. was cultured and its sterols were separated by column chromatography on silica gel. The new sterol 24-ethyl-4α-methyl-cholestane-3,20-diol (1) was characterised by NMR and MS spectrometry, as well as (22E)-24-ethyl-4α-methyl-5α-cholest-22-en-3β-ol (2) and β-sitosterol, the major components of the sterol fractions. Neither the biosynthetic origin of the new dihydroxysterol nor its role in the biochemistry of Diacronema is known.info:eu-repo/semantics/publishedVersio