Synthesis and Characterization of Copolymers with Fluorene-di-2-thienyl-2,1,3-benzothiadiazole Units for Application in Optoelectronic Devices.

Conjugated donor-acceptor (D-A) copolymers are widely used in optoelectronic devices due to their influence on the resulting properties. This study focuses on the synthesis and characterization of the conjugated D-A copolymer constructed with fluorene and di-2-thienyl-2,1,3-benzothiadiazole units, resulting in Poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4,7-di(2-thienyl)-2,1,3-benzothiadiazole)] (PFDTBT). The synthesis associated with reaction times of 48 and 24 h, the latter incorporating the phase-transfer catalyst Aliquat 336, was investigated.

Technological evaluation of stones from the eastern region of the state of São Paulo, Brazil, for railway ballast.

The correct choice of a stone aggregate for railway ballast is directly related to the stability, safety, efficiency, and maintenance costs of the track. The aggregate must meet several criteria to ensure it is the most appropriate material. Thus, the present study aimed to evaluate four distinct stones: two granites, a diabase, and a basalt, all mined in the eastern region of the state of São Paulo, Brazil, regarding their applicability as ballast.

Biogeographical Distribution of River Microbial Communities in Atlantic Catchments.

Microbes inhabit virtually all river ecosystems, influencing energy flow and playing a key role in global sustainability and climate change. Yet, there is uncertainty about how various taxonomic groups respond to large-scale factors in river networks. We analysed microbial community richness and composition across six European Atlantic catchments using environmental DNA sequencing.

Survey of parasitic fauna data from wild animals through coproparasitological diagnosis in Southern Brazil.

Background: The proximity between people and their domestic animals with wild animal populations can result in the spread of diseases with a significant impact on public health. Infection by parasites in wildlife is considered an important bioindicator of the current state of ecosystems, and studying the epidemiology of these infections is essential for a better understanding of natural foci. However, research on parasites in southern Brazil, especially in Rio Grande do Sul (RS), is considered incipient.

Effect of Sand Addition on Laterite Soil Stabilization.

Lateritic soils, particularly abundant in tropical regions, have been successfully used in the construction of unbound layers of flexible pavements in Brazil since the 1970s. Despite their potential, these soils are often discarded or only recommended after stabilization processes, based on traditional parameters such as gradation requirements and Atterberg limits. This study investigates the mechanical characteristics of a lateritic soil from Roraima, focusing on its resilient modulus and permanent deformation properties, assessed through repeated load triaxial tests.