A medição da grandeza practical peak voltage na prática radiológica

OBJETIVO: O objetivo deste trabalho foi estudar a grandeza practical peak voltage (PPV), determinada a partir da forma de onda de tensão aplicada a tubos radiológicos, e compará-la com algumas definições de kVp para diferentes tipos de geradores: monofásico (onda completa, clínico), trifásico (seis pulsos, clínico) e potencial constante (industrial). MATERIAIS E MÉTODOS: O trabalho envolveu a comparação do PPV medido invasivamente (utilizando um divisor de tensão) com a resposta de dois medidores comerciais não invasivos, além dos valores de outras grandezas usadas para medição da tensão de pico aplicada ao tubo de raios X, e a análise da variação do PPV com a ondulação percentual da tensão (ripple). RESULTADOS: Verificou-se que a diferença entre o PPV e as definições mais comuns de tensão de pico aumenta com o ripple. Os valores de PPV variaram em até 3% e 5%, respectivamente, na comparação entre medições invasivas e não invasivas feitas com os equipamentos trifásico e monofásico. CONCLUSÃO: Os resultados demonstraram que a principal grandeza de influência que afeta o PPV é o ripple da tensão. Adicionalmente, valores de PPV obtidos com medidores não invasivos devem ser avaliados considerando que eles dependem da taxa de aquisição e da forma de onda adquirida pelo instrumento.

Nitração do fenol, um método em escala semi-micro para disciplina prática de 4 horas

A procedure for the nitration of phenol in a semi-micro scale, followed by separation of the formed orto- and para-nitrophenol isomers by column chromatography, is described. All the experiment, including determination of the melting point of the isolated products, require a period of 4 hours, and it is suitable for organic chemistry laboratory undergraduate courses.

Los derechos de participación política y administrativa en la Constitución y en los Estatutos de Autonomía: especial referencia al Estatuto de Autonomía de Cataluña

[spa] El estudio afronta la regulación de los derechos de participación en los Estatutos de Autonomía de nueva generación. La novedad que representan estas normas respecto a sus predecesoras es la incorporación de una carta de derechos que vinculan de forma más explícita y detallada a los poderes públicos autonómicos. Los estatuyentes han interiorizado el creciente auge del fenómeno participativo regulando, junto a los tradicionales derechos de participación política, nuevos instrumentos y técnicas participativas, que se enmarcan en el concepto de democracia participativa. Significativa es, en este sentido, la voluntad política plasmada en la competencia que asumen algunos de ellos (Cataluña, Andalucía y Aragón)para la regulación de las consultas populares en cualquiera de sus modalidades ("encuestas, audiencias públicas, foros de participación") distintas el referéndum.

Espectros eletrônicos de alguns complexos de geometria octaédrica de Ni2+: uma introdução prática à teoria do campo cristalino no curso de graduação

The experiment introduces the undergraduate students to the crystal field theory. The electronic spectra of the octahedral complexes of [Ni(L)n]2+ (L = H2O, dmso, NH3 and en) obtained in the experiment are used to calculate 10Dq and B parameters. The experiment shows how the parameters can be calculated and correlated with the nature of the ligands and the field intensities produced.

Craqueamento térmico de alcanos: uma aula prática de química orgânica para a graduação

In this work we describe an experiment for the thermal cracking of octane and heptane and the qualitative analyses of the products using the Baeyer test for unsaturated compounds and gas chromatographic analyses. The experiment is very simple and requires one period of two hours and is suitable for undergraduate organic chemistry experimental courses.

Síntese de sulfadiazina e sulfadiazina de prata em escala semi-micro: prática experimental em síntese de fármacos

The total synthesis of sulfadiazine and silver sulfadiazine from readily available starting materials was adapted to semi-micro laboratory scale and is proposed as an experiment in drug synthesis for undergraduate courses.

Monitoramento atmosférico passivo de SO2, NO2 e O3 em áreas urbanas e de influência industrial como prática de química ambiental para alunos de graduação

This study is a result of undergraduate student participation in the Environmental Chemistry discipline provided by the Chemistry Institute/UFBA. The students were involved in the development of passive samplers, a project of the LAQUAM (Environmental Analytical Chemistry Laboratory). The students' residences and other neighborhoods were used to create a passive sampling network, allowing the measurement of atmospheric levels of pollutants in urban areas and in those under industrial influence. The assembly of the passive samplers, including impregnation of filters and chemical analysis were part of the students' practice tasks. The results were analyzed taking into consideration the Brazilian legislation.

Reatividade em reações de Diels-Alder: uma prática computacional

A computational quantum chemistry experiment is described of Diels-Alder reactions between 2-cycloenones and cyclopentadiene. The effects of FMO-Frontier Molecular Orbitals (HOMO-LUMO) and of the withdrawing nature of substituents at the C=C bond of cycloenones were evaluated. The calculations were made using HF/STO-3G and B3LYP/6-31+G(d,p) methods. The FMO based indexes are in agreement with the experimentally observed reactivity order. NBO - Natural Bond Orbitals - analysis was used to ascertain the effect of C=C substituents on the dienophile reactivity.

Passando da doutrina à prática: Ezequiel Corrêa dos Santos e a farmácia nacional

This article presents a sample of the activities of apothecary Ezequiel Corrêa dos Santos. He was notable not only for his professional career, but also for his political militancy, making an important contribution to the development of pharmaceutical sciences in Brazil, in the XIXth century.

Aplicatiu per gestionar la informació administrativa, tècnica i comptable per una empresa constructora

Les tendencies del mercat actual i futur obliguen a les empreses a ser cada vegada més competitives. Tota empresa que desitgi competir en el mercat actual ha de considerar la informació com un dels seus principals actius. Per aquesta raó, és necessari que l’empresa disposi dels sistemes d’informació adequats per ser gestionada. En les pimes ( petites i mitjanes empreses ), i en la majoria dels casos, la seva informació es troba repartida en diversos aplicatius informàtifcs. Això comporta principalment una duplicitat de dades, costos de manteniment i possibles errades en la informació. Dins del sector de les pimes, es troben empreses contructores d’un volum petit o mig, les quals enmagatzemen molta informació tècnica i de planificació per desemvolupar els seus projectes. Aquesta necessitat els hi suposa, tenir un aplicatiu eficient per la gestió i seguiment de la producció de les seves tasques i per altra banda l’aplicatiu necessari com qualsevol pime a nivell administratiu i comptable. L’objectiu principal d’aquest treball és generar un aplicatiu que integri la informació administrativa, comptable i tècnica per una empresa constructora. Amb l’assoliment d’aquest objectiu l’empresa constructora guanya temps en l’entrada i accés a les dades, evita la seva duplicitat i redueix el seu manteniment. En resum, redueix els costos de l’empresa i augmenta la seva seguretat en la informació. Un el mercat, existeixen aplicatius anomenats ERP ( Enterprise resource planning o sistemes de planificació de recursos ) els quals la seva gran virtud es la integració de les dades. Aprofitant aquests aplicatius i seleccionant-ne el més adequat, s’ha generat la part de gestió i planificació necessària per l’empresa constructora integrant-la i personalitzant-la en els processos existents de l’aplicació ( comptabilitat, ventes, compres, recursos humans, magatzems, etc… ) Entre les conclusions més rellevants obtingudes en aquest treball, voldriem destacar la millora i reducció d’entrada, accés i manteniment de la informació, l’històric que proporciona l’eina i per tan la millora de la gestío i planificació de l’empresa.

Educação ambiental nas escolas da região de Ribeirão Preto (SP): concepções orientadoras da prática docente e reflexões sobre a formação inicial de professores de química

During short courses, 95 secondary school teachers from 49 state schools and 421 students from the Ribeirão Preto region (in Sao Paulo state, Brazil, with a population of 530,000) were asked to fill in different questionnaires. The points raised in the teacher's questionnaire were used as a guide to establish a continuous dialogue during the short courses. Most of the schools claimed to have some kind of environmental education (EE). Based on the questionnaires and dialogues we analyzed how the teachers' perceptions on EE reflect on the views secondary students hold about their own responsibility for preserving the environment. The role of universities in the preparation of chemistry teachers capable of effectively approaching EE is also discussed.

O espaço da prática de ensino e do estágio curricular nos cursos de formação de professores de química das ies públicas paulistas

The literature presents a new understanding of the teaching practice and the supervised internship.Mutual interaction between them is expected one providing subsidies to the other.The present article shows the conceptions prevailing at the São Paulo state universities regarding these activities.Students,when interviewed, report difficulties in dealing with classroom situations. It is possible to observe that chemists wish to prepare new chemists deviating from the objectives of a Chemistry course leading to teaching credentials .

A prática docente na formação do pós-graduando em química

The present work describes how a group of chemistry graduate students have improved their teaching skills by teaching extension courses. It is suggested that future teachers have much to be gained by sharing the insights they have whilst teaching with their peers and students. This work explores the implications in teaching and learning and the relationship between teachers and students. This relationship requires mutual respect of ideas as well as continuous critical evaluation in both directions.

Sistemas tampão: uma estrutura didática teórico-prática

Courses with practical and theoretical classes are potentially didactic structures for the development of motor and complex cognitive skills when operated in an integrated manner. When worked aligned, theory and practice enable a clearer view of the issue, opening scope for introducing concepts from other disciplines and for the development of lab skills. This paper presents a methodology for biochemistry labwork that promotes the teaching of the buffering systems contents together with to the development of scientific research practice concepts in an interdisciplinary perspective that integrates theory and practice.