Universidade Positivo

About: Universidade Positivo is a education organization based out in Curitiba, Brazil. It is known for research contribution in the topics: Population & Biodiversity. The organization has 1290 authors who have published 1237 publications receiving 9335 citations. The organization is also known as: Positive University.

Macrofauna Edáfica e Atributos Físicos e Químicos em Sistemas de Uso do Solo no Planalto Catarinense

Abstract: O uso do solo pode alterar processos como decomposicao da materia orgânica, ciclagem de nutrientes e agregacao das particulas e, com isso, influenciar a ocorrencia da macrofauna. Objetivou-se com este estudo relacionar os sistemas de uso do solo e os efeitos deles sobre a distribuicao de grupos da macrofauna do solo, bem como a relacao desses com os atributos fisicos e quimicos do solo. Os sistemas de uso do solo avaliados foram: floresta nativa, reflorestamento de eucalipto, pastagem, integracao lavoura-pecuaria e lavoura com sistema plantio direto. As amostras foram coletadas em uma grade de amostragem de 3 × 3, totalizando nove pontos, distanciados entre si em 30 m, no inverno e verao, em tres municipios do Planalto Sul-catarinense, considerados replicas verdadeiras. As avaliacoes foram de atributos fisicos e quimicos do solo e da abundância e diversidade da macrofauna, coletada pelo metodo Tropical Soil Biology and Fertility (TSBF). Os organismos do solo sao pertencentes a 16 grupos taxonomicos, com 4.702 individuos m-2 no inverno e 7.438 individuos m-2 no verao. Houve interacao entre epoca e sistemas de uso do solo, com flutuacao populacional dos organismos dependente do uso e com relacao aos atributos fisicos e quimicos do solo, evidenciada pela analise de redundância, que apresentou alta correlacao entre variaveis ambientais e fauna do solo. As mudancas na composicao da macrofauna do solo foram observadas nos seus sistemas de uso, que tiveram maior intervencao antropica. Floresta nativa, reflorestamento de eucalipto e pastagem sao mais estaveis em termos de biodiversidade da macrofauna do solo, quando comparados com areas agricolas com plantio direto e integracao lavoura-pecuaria.

Harmonised framework for ecological risk assessment of sediments from ports and estuarine zones of North and South Atlantic.

Abstract: This paper presents a harmonised framework of sediment quality assessment and dredging material characterisation for estuaries and port zones of North and South Atlantic. This framework, based on the weight-of-evidence approach, provides a structure and a process for conducting sediment/dredging material assessment that leads to a decision. The main structure consists of “step 1” (examination of available data); “step 2” (chemical characterisation and toxicity assessment); “decision 1” (any chemical level higher than reference values? are sediments toxic?); “step 3” (assessment of benthic community structure); “step 4” (integration of the results); “decision 2” (are sediments toxic or benthic community impaired?); “step 5” (construction of the decision matrix) and “decision 3” (is there environmental risk?). The sequence of assessments may be interrupted when the information obtained is judged to be sufficient for a correct characterisation of the risk posed by the sediments/dredging material. This framework brought novel features compared to other sediment/dredging material risk assessment frameworks: data integration through multivariate analysis allows the identification of which samples are toxic and/or related to impaired benthic communities; it also discriminates the chemicals responsible for negative biological effects; and the framework dispenses the use of a reference area. We demonstrated the successful application of this framework in different port and estuarine zones of the North (Gulf of Cadiz) and South Atlantic (Santos and Paranagua Estuarine Systems).

Influence of the interposition of ceramic spacers on the degree of conversion and the hardness of resin cements

Abstract: This study evaluated: I) the effect of photo-activation through ceramics on the degree of conversion (DC) and on the Knoop hardness (KHN) of light- and dual-cured resin cements; and II) two different protocols for obtaining the spectra of uncured materials, to determine the DC of a dual-cured resin cement. Thin films of cements were photo-activated through ceramics [feldspathic porcelain (FP); lithium disilicate glass-ceramics of low translucency (e.max-LT), medium opacity (e.max-MO) and high translucency (e.max-HT); glass-infiltrated alumina composite (IC) and polycrystalline zirconia (ZR)] with thicknesses of 1.5 and 2.0 mm. DC was analyzed by Fourier transform infrared (FTIR) spectroscopy. Two protocols were used to obtain the spectra of the uncured materials: I) base and catalyst pastes were mixed, and II) thin films of base and catalyst pastes were obtained separately, and an average was obtained. KHN assessment was performed with cylindrical specimens. The results were analyzed by ANOVA and Tukey's test (α= 0.05). The light-cured cement showed higher DC (61.9%) than the dual-cured cement (55.7%). The DC varied as follows: FP (65.4%), e.max-HT (65.1%), e.max-LT (61.8%), e.max-MO (60.9%), ZR (54.8%), and IC (44.9%). The light-cured cement showed lower KHN (22.0) than the dual-cured (25.6) cement. The cements cured under 1.5 mm spacers showed higher KHN (26.2) than when polymerized under 2.0 mm ceramics (21.3). Regarding the two protocols, there were significant differences only in three groups. Thus, both methods can be considered appropriate. The physical and mechanical properties of resin cements may be affected by the thickness and microstructure of the ceramic material interposed during photo-activation.