No abstract

A bibliometric analysis using the Web of Science database was performed on the green synthesis of nanomaterials published between 2003 and 2017, obtaining a sample with a total of 159 publications. The number of citations of each paper, thematic areas, sources of publication and countries of origin were quantified. The ten most cited papers were described in further detail, listing the precursor materials, the kind of material produced among other characteristics. There is a variety of precursors listed in the literature, including fungi, bacteria, plants, extracts from plants and fruits. Although United States was a pioneer and is influent in this line of research, India is taking the lead due to government incentives and the presence of natural resources having a total of 44.65% of the analyzed works. Silver oxides is the material most produced by this method, according to the most cited works and are commonly applied in antibacterial activity. The main areas of discussion at WoS for this topic are the Chemistry and Science Technology categories with 55 papers each. The main sources of publication are the Colloids and Surfaces B - biointerfaces and RSC Advances with 3,774% in each journal in relation to the study sample. Potentialities of the new nanomaterials production method that could be exploited by other researchers from the use of new precursors, including solid agroindustrial wastes, with the opportunity to add value to the biomass and consequently to reduce environmental impact generated by by-products.

O presente artigo tem como objetivo discutir as barreiras existentes para a expansão da logística reversa de Óleos lubrificantes usados e contaminados – Oluc, avaliando a eficiência na coleta dos mesmos. O método da pesquisa foi um estudo de caso, delineado por uma pesquisa documental e de campo, a fim de identificar gargalos existentes no gerenciamento de resíduos de empresas do setor de troca de óleo no município de São Mateus-ES.  Apesar do avanço da legislação aplicada ao setor, o estudo evidenciou que em algumas empresas, o descarte do Oluc e dos seus resíduos contaminados ainda é realizada de maneira inadequada, principalmente devido à falta de fiscalização, tributação complexa e à falta de credibilidade do óleo reaproveitado.

In this article a bibliometric analysis of spinel ferrite production was carried out, with the purpose of  to expanding the knowledge management on the research area, also identify future perspectives turned to the application of such structures and light to dry research. The study was designed based on a statistical and qualitative analysis of Web of Science (WoS) database documents from 1995-2017, using as an additional tool the CiteSpace software, which allows the expansion of the domain of knowledge on the subject With the acquirement of a set of bibliographic records of relevant publications, with subsequent identification of interlinked research groups (clusters). The CiteSpace software provides a set of empirical parameters, among them the so-called Betweenness Centrality (BC), which describes the influence of a given article on the transfer of information between the set of publications under study. Through the results it was possible to identify significant growth in the number of publications and citations. The countries with the highest number of publications are India (946), China (483) and the United States (247), with the US having the largest centrality parameter (BC), which reflects its prominent role in transmitting, information about spinel type ferrite. When analyzing the de-composition of WoS categories in large groups or clusters, we observed the predominance of three areas according to the number of co-citations: magnetic properties, electromagnetic properties and effect had electrocatalysis properties, which reflects the main objectives of research on this topic. Among the main keywords, “cobalt ferrite” has the largest BC parameter, revealing greater interest of the scientific community in Cobalt ferrite. The results of the clusters were corroborated from the identification of the main applications of spinel type ferrite in the last two years, in which the performance of these materials was observed predominantly in effluent treatment, magnetic devices, sensors and medical applications.

RESUMO: Aços inoxidáveis duplex (AID's) apresentam uma combinação de alta resistência à corrosão e boas propriedades mecânicas, tendo aplicações nas indústrias petroquímicas ou de celulose. Entretanto, tratamentos térmicos em determinadas temperaturas acarretam a precipitação de fases intermetálicas como sigma e chi que degradam propriedades mecânicas e químicas. Assim, torna-se importante identificar a influência dos parâmetros de ciclos térmicos nos AID's. Desse modo, visando estudar um tratamento térmico apropriado ao aço duplex UNS S32205, tem-se como objetivo avaliar a variação da porcentagem volumétrica das fases a partir de distintas temperaturas de tratamento de envelhecimento entre 800 e 950°C, bem como de solubilização entre 1000 e 1150°C, com tempo de encharque de 30 minutos seguido de resfriamento em água. Os resultados revelaram que entre 800 e 950°C ocorre a precipitação da fase sigma, com maior incidência na temperatura de 850°C (8%). Adicionalmente, para os tratamentos acima de 1000°C, tem-se somente a presença das fases ferrita e austenita, com a obtenção de maiores porcentagens da fase ferrita para as maiores temperaturas de tratamento térmico. Ademais, observou-se que a precipitação da fase sigma aumentou substancialmente a dureza das amostras.