The present study investigated the fauna of metazoan parasites of a Geophagus proximus population from the lower Tapajós River, in the state of Pará, northern Brazil. A total of 137 monogeneans were collecte...The present study investigated the fauna of metazoan parasites of a Geophagus proximus population from the lower Tapajós River, in the state of Pará, northern Brazil. A total of 137 monogeneans were collected from the gills of G. proximus, including Sciadicleithrum kritskyi, Sciadicleithrum paranaensis and Sciadicleithrum geophagi, while 119 Raphidascaris (Sprentascaris) lanfrediae nematodes and 28 metacercariaes of digenea undetermined were collected from the intestine. Hosts harboring four species of parasites were predominant. The parasites had an aggregated dispersion pattern. The present study represents the first record of S. geophagi parasitizing G. proximus, increasing the geographic distribution of these parasite species to the Tapajós River basin.展开更多
This paper records the first occurrence of Epistylis sp. on the body surface of Argulus sp. parasitizing Hoplias aimara from the upper Araguari River, in the eastern Amazon region, in the north of Brazil. Of the 16 sp...This paper records the first occurrence of Epistylis sp. on the body surface of Argulus sp. parasitizing Hoplias aimara from the upper Araguari River, in the eastern Amazon region, in the north of Brazil. Of the 16 specimens of H. aimara examined, 93.7% had their pelvic, caudal and pectoral fins and tegument infested by Argulus sp. (n = 73), which in turn were infested by Epistylis sp. The specimens of Epistylis sp. from the body surface of Argulus sp. were analyzed using Scanning Electron Microscopy (SEM). The present study also identified a widening of the geographic distribution of these two species of ectoparasites to the eastern Amazon region of Brazil.展开更多
The thermal stability, structural and dielectric properties of the (CaTiO<sub>3</sub>)<sub>1-x</sub>(Cr<sub>3/4</sub>Fe<sub>5/4</sub>O<sub>3</sub>)<sub>...The thermal stability, structural and dielectric properties of the (CaTiO<sub>3</sub>)<sub>1-x</sub>(Cr<sub>3/4</sub>Fe<sub>5/4</sub>O<sub>3</sub>)<sub>x</sub> ceramic composites with x = 0, 0.1, 0.5, 0.9 and 1 have been examined in microwave region. The samples were produced via the solid-state reaction. The orthorhombic structural phase of CaTiO<sub>3</sub> and trigonal structural phase of Cr<sub>3/4</sub>Fe<sub>5/4</sub>O<sub>3</sub> were confirmed by the X-Ray Powder Diffraction (XRPD). The XRPD patterns for composites reveal the quantities of each original phase present. The infrared spectra of the samples reinforce this structural verification indicating no or minimal occurrence of unwanted reactions. The first sample (x = 0) and last sample (x = 1) in this series exhibit the maximum and the minimum of the relative dielectric permittivity and values range from 140.1 to 8.3 respectively. The measured temperature coefficient of the matrix CaTiO<sub>3</sub> was +921 ppm·℃<sup>-1</sup> and for the matrix Cr<sub>3/4</sub>Fe<sub>5/4</sub>O<sub>3</sub> was -56 ppm·℃<sup>-</sup><sup>1</sup>. With the study of series of composites, it was possible to make a mathematical prediction for a composition reach the temperature coefficient near zero. The proposed ceramic has potential use as thermostable material in the microwave region and can be applied to resonators, low-noise amplifiers, filters, and so on.展开更多
文摘The present study investigated the fauna of metazoan parasites of a Geophagus proximus population from the lower Tapajós River, in the state of Pará, northern Brazil. A total of 137 monogeneans were collected from the gills of G. proximus, including Sciadicleithrum kritskyi, Sciadicleithrum paranaensis and Sciadicleithrum geophagi, while 119 Raphidascaris (Sprentascaris) lanfrediae nematodes and 28 metacercariaes of digenea undetermined were collected from the intestine. Hosts harboring four species of parasites were predominant. The parasites had an aggregated dispersion pattern. The present study represents the first record of S. geophagi parasitizing G. proximus, increasing the geographic distribution of these parasite species to the Tapajós River basin.
文摘This paper records the first occurrence of Epistylis sp. on the body surface of Argulus sp. parasitizing Hoplias aimara from the upper Araguari River, in the eastern Amazon region, in the north of Brazil. Of the 16 specimens of H. aimara examined, 93.7% had their pelvic, caudal and pectoral fins and tegument infested by Argulus sp. (n = 73), which in turn were infested by Epistylis sp. The specimens of Epistylis sp. from the body surface of Argulus sp. were analyzed using Scanning Electron Microscopy (SEM). The present study also identified a widening of the geographic distribution of these two species of ectoparasites to the eastern Amazon region of Brazil.
文摘The thermal stability, structural and dielectric properties of the (CaTiO<sub>3</sub>)<sub>1-x</sub>(Cr<sub>3/4</sub>Fe<sub>5/4</sub>O<sub>3</sub>)<sub>x</sub> ceramic composites with x = 0, 0.1, 0.5, 0.9 and 1 have been examined in microwave region. The samples were produced via the solid-state reaction. The orthorhombic structural phase of CaTiO<sub>3</sub> and trigonal structural phase of Cr<sub>3/4</sub>Fe<sub>5/4</sub>O<sub>3</sub> were confirmed by the X-Ray Powder Diffraction (XRPD). The XRPD patterns for composites reveal the quantities of each original phase present. The infrared spectra of the samples reinforce this structural verification indicating no or minimal occurrence of unwanted reactions. The first sample (x = 0) and last sample (x = 1) in this series exhibit the maximum and the minimum of the relative dielectric permittivity and values range from 140.1 to 8.3 respectively. The measured temperature coefficient of the matrix CaTiO<sub>3</sub> was +921 ppm·℃<sup>-1</sup> and for the matrix Cr<sub>3/4</sub>Fe<sub>5/4</sub>O<sub>3</sub> was -56 ppm·℃<sup>-</sup><sup>1</sup>. With the study of series of composites, it was possible to make a mathematical prediction for a composition reach the temperature coefficient near zero. The proposed ceramic has potential use as thermostable material in the microwave region and can be applied to resonators, low-noise amplifiers, filters, and so on.
