Search

Summary: Despite good rigidity, braced frames have weak nonlinear behavior and inadequate distribution of ductility in stories, which cause significant structural damage. In this research, a seismic resistant system called coupled concentrically braced frame (CCBF) is developed to enhance the performance of braced frames by coupling them with a beam. In this case, the coupling beams are the primary source for ductility of the system, and after their yielding in more severe earthquakes, the structure continues to benefit from the ductility of the braces as the secondary source; therefore, the system has two‐level behavior caused by different probable seismic excitations. In this case, in addition to maintaining the stiffness of the two concentrically braced frames, the coupling beams resist against the movement of the braced frames, and as a result, the stiffness of the system is increased. Therefore, lighter elements can be used to resist lateral loads. Linear and nonlinear analyses of CCBF, and its comparison with other braced frames, indicate that participation of the coupling beams provides an adequate stiffness and ductility. These frames have more stable nonlinear behavior than conventional ones and continue their nonlinear behavior even after fracture of coupling beams in severe earthquakes. [ABSTRACT FROM AUTHOR]

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The contamination of groundwater resources by heavy metals, especially arsenic (As), is a significant hazard that threatens human health and the environment. In the present study, As contamination and its probable origin were investigated in the groundwater resources of the Sirjan Plain, Iran. For this purpose, groundwater samples were taken from 22 exploitation wells and analyzed for As, Cd, Mo, Se, Fe, Al, Ca2+, Na+, Mg2+, K+, Cl-, SO42-, HCO3-, TDS, EC, TH, and pH in June 2017. The results showed that As had a variation ranging from 1 μg/L to 195 μg/L. In this regard, 68.1% of the groundwater samples contained As concentrations more greater than the 10 μg/L threshold proposed by the World Health Organization. The highest As concentrations were detected in the northeastern and central parts of the plain.Meanwhile, a declining trend was observed in the samples from the north and south of the plain. In the next step, correlation analysis and multivariate statistical analysis, including principal component analysis and cluster analysis, were carried out to extract associations among the studied parameters. The results showed that As from Fe and Al oxyhydroxides surfaces under oxidizing conditions was a significant factor causing As contamination in the Sirjan Plain. The knowledge gained from this study helps to better understand the mechanisms of As contamination, which is useful for decisionmakers regularly monitoring As concentrations in the Sirjan area's groundwater. It is concluded that multivariate statistical techniques are helpful tools in the current dataset and the study area. [ABSTRACT FROM AUTHOR]

BACKGROUND: As the population grows, there is further need to food, and fish is not an exception. Several fish species are potential sources of common parasites between humans and fish. One of the important diseases common between human and fish is Anisakiasis. The parasitic agent of this disease is the larval stage of the Anisakid family nematodes, including Pseudoterranova and Anisakis. OBJECTIVES: In this study, Epinephelus fish, one of the edible and commercial valuable fishes of the Oman Sea, was examined for the presence of nematodes of the Anizakidae family. METHODS: Fifteen out of the 26 specimens were infected with Nematodes. Nematodes were isolated from fish abdominal area. For morphological study, each nematode sample was first clarified with lactophenol. Subsequently, it was examined using an optical microscope. After morphological examination of these nematodes, DNA extraction was performed. Using primers related to a part of cytochrome oxidase subunit 1 (Cox1), PCR products were 710 bp for PCR reaction. Finally, the amplified fragment was sequenced. RESULTS: The larvae were about 1 to 3 cm long, white, and often twisted. At the anterior end of the parasite, a button was seen, and in some larvae, a terminal spine was observed. In certain larvae, a small abdomen at the end of the esophagus can be seen. Out of the obtained 26 nematode specimens, eight Anisakis specimens were identified following morphological analysis. These specimens had terminal spines and three anterior lips. After sequencing, Pseudoterranova nematode was identified to belong to aniakidae family. Separate clad tree showed paraphylitic for isolated Pseudoterranova. CONCLUSIONS: Morphological examination categorized isolated larvae as the Anizakidae family. Other molecular results of this nematode showed Pseudoterranova krabbei. The results of sequencing this parasite were recorded in the gene bank under the Accession number: MK317965. This nematode was initially isolated from the Oman Sea Epinephelus fish. [ABSTRACT FROM AUTHOR]