A produtividade dos autores sobre a Lei de Lotka

Estuda a produção estratificada dos autores produtores da literatura sobre a Lei de Lotka de 1922 a 2003 e analisa essa produtividade através dos modelos Poisson lognormal e Gauss Poisson inversa generalizada. Para tanto, faz uso dos três tipos de contagem da literatura produzida: contagem direta, contagem completa e contagem fracionada. Os dados da pesquisa são avaliados usando o teste qui-quadrado ao 0.05 nível de significância. Ambos os modelos ajustam-se muito bem à distribuição da literatura produzida, porém a distribuição Poisson Gauss inversa generalizada produz um chi-quadrado menor e prediz melhor o total de autores do que a distribuição Poisson Lognormal.

Crescimento da literatura e dos autores sobre a Lei de Lotka

Analisa o crescimento da literatura produzida sobre a Lei de Lotka, assim como o crescimento dos autores produtores dessa literatura, de 1922 a 2003. Nesse período o crescimento da literatura segue o modelo exponencial, com taxa média de crescimento de 7,5% ao ano e taxa de duplicação a cada 9,6 anos. Também o número de autores produtores da literatura cresce à proporção de 7,3% ao ano, com período de duplicação a cada 10 anos. A estatística indica bom ajuste ao modelo exponencial, com R² de 0,985 para a literatura e 0,992 para os autores, ambos a um nível de significância de 0,01.

A nova lei de patentes, a indústria química e a universidade

This paper aims to present some features of the Industrial Property Law now in force in Brazil, as far as they could be regarded to the activities of research and development in the field of Chemistry and related areas, not only in the chemical industry but also in the university. By means of analysis of the main articles and paragraphs, which could deal with the mentioned activities, the author points out the scope and limitations of that law and explains the meaning of common technical terms usually found in patent concerns. Ultimately, a brief discussion on the actual and the potential role of the Brazilian university in the sphere of the Industrial Property is made.

A formulação ab-initio da segunda lei da termodinâmica

This paper deals with Carathédory's formulation of the second law of thermodynamics. The material is presented in a didatical way, which allows a second year undergraduate student to follow the formalism. An application is made to an ideal gas with two independent variables. A criticism to Carnot formulation of the second law and an investigation of the historical origins of the Carathéodory formalism are also presented.

Sobre a primeira lei da termodinâmica

Entropy is a concept that has long stimulated human curiosity, resulting in an huge intelectual production. The same has not occurred for the first law of thermodynamics, perhaps because of its apparent obviousness. In this article the first law presentation, as displayed in most traditional physical chemistry textbooks, is criticized. An alternative view is suggested, in accordance with temporal thermodynamics. The time derivative local form of the second law is used to stress the entropy concept implications on the notion of internal energy.

Reflexões sobre a contribuição da Carnot à primeira lei da termodinâmica

The classical interpretations of Nicolas Léonard Sadi Carnot on some physical principles involved in the operation of heat engines were fundamental to the development and formulation of the Second Law of Thermodynamics. Moreover, an accurate historical survey clearly reveals that Carnot was, by that time, also well aware about some new concepts, which were further worked out by other scientists to lead to what was, some time later, known as the mechanical equivalent of heat and the conservation of energy. Benoit Paul Émile Clapeyron recognized these original concepts in the first of Carnot´s monographs, published in 1824, but no explicit citation is found in any post-Carnot classical texts dealing with the First Law of Thermodynamics, including those by Julius Robert Mayer, James Prescott Joule and Hermann Ludwig Ferdinand von Helmholtz. The main objective of the present work is to point out some historical evidences of the pioneering contribution of Carnot to the modern concept of the First Law of Thermodynamics.

Sobre a primeira lei da termodinâmica: as diferenciais do calor e do trabalho

We treat some subtleties concerning the First Law of Thermodynamics and discuss the inherent difficulties, namely the interpretation of the heat and the work differentials. By proposing a new differential equation for the First Law, which is written using both system and neighborhood variables, we overcome the mentioned difficulties and establish a criterion for the definition of heat and work.

A primeira lei da termodinâmica dos processos homogêneos

Thermodynamics of homogeneous processes, which corresponds to the very special situation in thermodynamics of continuous media, is used to discuss the first law. An important part of this work is the exposition of some typical mathematical errors, frequently found in the traditional presentation of thermodynamics. The concepts of state and process functions are discussed, as well as reverse and reversible processes, temporality and its implications on thermodynamics, energy reservoirs and symmetry. Our proposal is to present the first law by using a time dependent viewpoint coherent with mechanics and the foundations of that viewpoint.

Aumento da resposta analítica por meio da otimização do sistema de injeção sem divisão de fluxo em cromatografia gasosa empregando a lei dos gases ideais

This paper reports the development of an easy, fast and effective procedure for the verification of the ideal gas law in splitless injection systems in order to improve the response. Results of a group of pesticides were used to demonstrate the suitability of the approach. The procedure helps establish experimental parameters through theoretical aspects. The improved instrumental response allowed extraction with lower sample volumes, the minimization of time and costs and the simplification of sample preparation.

A segunda lei da termodinâmica

Considering intrinsic characteristics of the system exclusively, both statistical and information theory interpretations of the second law are used to provide more comprehensive meanings for the concepts of entropy, temperature, and Helmholtz and Gibbs energies. The coherence of Clausius inequality to these concepts is emphasized. The aim of this work is to re-discuss the second law of thermodynamics in accordance to homogeneous processes thermodynamics, a temporal science which is the very special oversimplification of continuum mechanics for spatially constant intensive properties.

A importância da lei de Gay-Lussac para a classificação dos compostos orgânicos

This article shows the genesis of the law of volumes of combining gases, formulated by Gay-Lussac in 1808, and how it allowed the expression of the composition of organic compounds in terms of whole numbers of volumes, thus leading to the first classification of organic compounds, formulated by Dumas and Boullay in 1828. It was from this work that Organic Chemistry began to shed its purely taxonomic nature, analogous to what prevailed in Natural History, and to then develop in a vigorous and continuous process, initiating what may be the most significant historical phenomenon in the History of Chemistry of the nineteenth century.