A characteristic of the fracture and cleavage experiments is that they are usually intrinsically destructive. Cracks do not completely heal in an unstressed system, even in crystals such as mica. Here, we used magneti...A characteristic of the fracture and cleavage experiments is that they are usually intrinsically destructive. Cracks do not completely heal in an unstressed system, even in crystals such as mica. Here, we used magnetic solids composed of magnetic strips for the non-destructive cleavage and brittle fracture experiments. Between the magnetic strips materials with different mechanical characteristics can be inserted, such as Teflon or foam strips, to change the mechanical properties of the solid. For the cleavage experiments, we developed an apparatus where parameters such as the main involved force can be measured easily. By inserting flaws, the magnetic solid can be used in dynamic fracture experiments, with the advantages of simulating macroscopically a non-destructive experiment in an easier way, that happen in real materials with much higher velocities. The apparatus and the used magnetic solid may be useful for demonstrations of fractures in classes.展开更多
The production of plastics has exponentially increased over time such that the observation of microplastics in the oceans has become a major concern given how frequently these particles and marine biota may interact.M...The production of plastics has exponentially increased over time such that the observation of microplastics in the oceans has become a major concern given how frequently these particles and marine biota may interact.Microplastics can be ingested by diverse species,including invertebrates,which can lead to physical damage due to their small size and potentially chemical damage related to the ingestion of monomers,polymeric additives,or adsorbed chemicals.This study reports on the first evidence of microplastics in Mnemiopsis leidyi.Microplastics were described by type,quantified,and had their chemical composition identified.In total,328 samples of microplastic(MP)candidates were observed:blue fibers were the most abundant,followed by black,red,and green fibers as well as blue fragments.Three types of microplastics were chemically identified as polyurethane,unplasticized polyvinylchloride,and polyethylene polylauryllactam.Overall,this study demonstrated that Mnemiopsis leidyi have the capacity to incorporate microplastics.Although more studies are needed,Mnemiopsis leidyi is relatively abundant on the Atlantic coast and should be recommended for use as a bioindicator for microplastics.展开更多
基金supported by the Brazilian agencies CNP_q,CAPES and FINEP,and by Petrobras.
文摘A characteristic of the fracture and cleavage experiments is that they are usually intrinsically destructive. Cracks do not completely heal in an unstressed system, even in crystals such as mica. Here, we used magnetic solids composed of magnetic strips for the non-destructive cleavage and brittle fracture experiments. Between the magnetic strips materials with different mechanical characteristics can be inserted, such as Teflon or foam strips, to change the mechanical properties of the solid. For the cleavage experiments, we developed an apparatus where parameters such as the main involved force can be measured easily. By inserting flaws, the magnetic solid can be used in dynamic fracture experiments, with the advantages of simulating macroscopically a non-destructive experiment in an easier way, that happen in real materials with much higher velocities. The apparatus and the used magnetic solid may be useful for demonstrations of fractures in classes.
基金supported by FAPES/VALE/FAPERJ[grant number 01/2015].
文摘The production of plastics has exponentially increased over time such that the observation of microplastics in the oceans has become a major concern given how frequently these particles and marine biota may interact.Microplastics can be ingested by diverse species,including invertebrates,which can lead to physical damage due to their small size and potentially chemical damage related to the ingestion of monomers,polymeric additives,or adsorbed chemicals.This study reports on the first evidence of microplastics in Mnemiopsis leidyi.Microplastics were described by type,quantified,and had their chemical composition identified.In total,328 samples of microplastic(MP)candidates were observed:blue fibers were the most abundant,followed by black,red,and green fibers as well as blue fragments.Three types of microplastics were chemically identified as polyurethane,unplasticized polyvinylchloride,and polyethylene polylauryllactam.Overall,this study demonstrated that Mnemiopsis leidyi have the capacity to incorporate microplastics.Although more studies are needed,Mnemiopsis leidyi is relatively abundant on the Atlantic coast and should be recommended for use as a bioindicator for microplastics.
