Influence of the deep cryogenic treatment at the stabilization of martensitic transformation temperatures at the smart material alloy Cu-14Al-4Ni

DCT (deep cryogenic treatment) is commonly used in industry to improve the wear resistance characteristics of steels, especially. However, there are just a few researches about the effects on non-ferrous metals. The purpose of this work was to investigate how DCT affects the properties of Cu-14Al-4Ni alloy treated at different soak time and submitted to thermomechanical cycling. A comparative experimental analysis was performed of the thermal properties of alloys obtained on a vacuum furnace, treated by DCT and thermomechanically cyclized. The results indicates that thermomechanical cycling promoted the appearance and growth of the martensitic phase γ'1, less ductile than the martensitic phase β'1, which together with the induced hardening produced an increase in transformation temperatures and microhardness. The higher the number of cycles, the greater these effects. The DCT promoted an increase in the intensity of the diffraction peaks corresponding to the phase β'1 and the maintenance of them during the thermomechanical cycling of the material, which indicates that the DCT stabilizes the martensitic phase β'1 and, consequently, caused a reduction and stabilization of the martensitic transformation temperatures and the microhardness, when compared to the untreated material. The longer the soaking time of DCT, the greater these effects

Comparisson of recrystallization kinetics and grain growth in polycrystalline shape memory alloys

The non-ferrous SMAs (shape memory alloys) have, normally, two problems that hinder the use in industrial scale: the natural aging and grain growth. The first degrades the memory effect, while the second, observed during the alloy’s mechanical processing, modifies the phase transformation temperatures. Thus, the study of recrystallization kinetics is important for enabling the control of hardened state as a function of treatment time without allowing the exaggerated grain growth. The objective of this study is to determine the recrystallization kinetics in different SMAs (Cu-14Al-4Ni, Cu-12Al-0.5Be and Ni-42Ti), based on an empirical law of J-M-A (Johnson-Mehl-Avrami), as well as their activation energies for grain growth process according to the empirical Arrhenius law.Quantitative evaluations of the grain growth kinetics over a wide range of indicated DSC (differential scanning calorimetry) temperatures have been performed. The results show that the alloy less susceptible to aging in temperatures below the recrystallization peak is the Ni-42Ti, because it presented the highest activation energy, followed by the Cu-14Al-4Ni. The equations that describe the recrystallization kinetics follow the empirical law of J-M-A. The recrystallization kinetics accompanied by hardness variation was an important tool, working as an advisor for selection of treatment time as a function of temperature

Study of reinforcement distribution, adhesion between layers, and porosity induced by FDM

This study aims to understand the distribution of reinforcement material in the matrix, evaluate the adherence between layers, and determine the air gap between printing roads. We printed the specimen with two different composite materials, Polylactic Acid (PLA) reinforced with acrylic particles, and another filament reinforced with short carbon fibers. For the observations of the samples, we used a Confocal Microscope. We estimated the porosity of the material by comparing the expected mass with that achieved after manufacture. By pixel count, after binarization, we found the average percentage of acrylate particulate. They showed fair distribution through the PLA matrix even after the manufacturing process. The determination of fibers alignment was made by binarization of image, together with k-means and edge detection. This combination of methods allows estimating the fiber alignment by orientation straight lines. The manufacturing process did not offer good alignment of the fibers, even with the filament initially well aligned

Antinociceptive and Anti-Inflammatory Activity from Algae of the Genus Caulerpa

Marine natural products have been the focus of discovery for new products of chemical and pharmacological interest. The aim of this study was to evaluate the antinociceptive activity of the methanolic (ME), acetate (AE), hexanic (HE) and chloroform (CE) extracts obtained from Caulerpa mexicana, and ME, CE and HE obtained from Caulerpa sertularioides. These marine algae are found all over the world, mainly in tropical regions. Models such as the writhing test, the hot plate test and formalin-induced nociception test were used to evaluate antinociceptive activity in laboratory mice. In the writhing test, all the extracts were administered orally at a concentration of 100 mg/kg, and induced high peripheral antinociceptive activity, with a reduction in the nociception induced by acetic acid above 65%. In the hot plate test, treatment with extracts from C. sertularioides (100 mg/kg, p.o.) did not significantly increase the latency of response, although the ME, AE and HE from C. mexicana showed activity in this model. This result suggests that these extracts exhibit antinociceptive activity. In the formalin test, it was observed that ME, AE and HE obtained from C. mexicana reduced the effects of formalin in both phases. On the other hand only CE from C. sertularioides induced significant inhibition of the nociceptive response in the first phase. To better assess the potential anti-inflammatory activity of the extracts, the carrageenan-induced peritonitis test was used to test Caulerpa spp. extracts on cell migration into the peritoneal cavity. In this assay, all extracts evaluated were able to significantly inhibit leukocyte migration into the peritoneal cavity in comparison with carrageenan. These data demonstrate that extracts from Caulerpa species elicit pronounced antinociceptive and anti-inflamatory activity against several nociception models. However, pharmacological and chemical studies are continuing in order to characterize the mechanism(s) responsible for the antinociceptive action and also to identify the active principles present in the Caulerpa species

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Estudo da cinetica de recristalizacao da liga de aluminio AA8011 na condicao H18

A liga AA 8011 é uma das mais versáteis ligas comerciais de alumínio. A diversidade de suas aplicações depende não só de sua composição química, mas, principalmente, das transformações microestruturais que ela venha a sofrer. Nesse contexto, o estudo da cinética de recristalização assume um papel relevante por possibilitar o controle do estado encruado em função do tempo de tratamento. O objetivo deste trabalho é determinar as cinéticas de recristalização para cada propriedade considerada e estudar seus mecanismos. Para tanto, foram realizadas, inicialmente, análises dinâmicas em DSC para determinação da temperatura de recristalização da liga encruada para cada composição analisada. Em seguida, diferentes amostras foram recozidas em temperaturas próximas à de pico da curva DSC em tempos que variaram de 5 a 180 minutos. Depois de tratadas, as amostras foram submetidas a ensaios mecânicos (dureza Vickers e tração uniaxial) para levantamento das curvas Propriedades versus Tempo. Os valores das propriedades mecânicas foram relacionados biunivocamente aos da fração transformada para determinação da cinética de recristalização. Para a caracterização do processo e de seus mecanismos, foram realizadas análises em raios-x, microscopia óptica e eletrônica de transmissão MET. Os resultados mostraram que a equação da fração recristalizada segue a lei empírica de formação prevista por Jonhson-Mehl-Avrami para qualquer propriedade considerada, assim como, as modificações microestruturais que ocorrem, excluindo-se a recristalização, são decorrentes da decomposição spinodal e influenciam significativamente a plasticidade do material. Concluímos que a cinética de recristalização tem um comportamento anisotrópico, no qual o do sentido longitudinal expressa-se diferentemente do transversal, e anômalo no que diz respeito à evolução das propriedades nos domínios elástico e plástic

Influência do tratamento criogênico profundo nas temperaturas de transformação de fase e na estabilização da capacidade de recuperação de forma da liga CU-14AL-4NI com efeito memória de forma

O tratamento criogênico profundo (TCP) é normalmente utilizado na indústria para melhorar as características de resistência ao desgaste dos aços-ferramenta. No entanto, pouco se sabe sobre os seus efeitos nos metais não ferrosos. O objetivo deste trabalho foi investigar como o TCP afeta as propriedades e o comportamento da liga Cu-14Al-4Ni tratada em diferentes tempos de encharque e submetidas a ciclagens termomecânicas. Foi realizada análise experimental comparativa das temperaturas de transformação, microdureza e capacidade de recuperação de forma da liga obtida por fundição, tratada por TCP e ciclada termomecanicamente. Os resultados mostraram que as ciclagens termomecânicas propiciaram o surgimento e crescimento da fase martensítica (g’ 1 ), menos dúctil que a fase martensítica (β’1 ), e produziram um aumento das temperaturas de transformação martensíticas e da microdureza do material, além da redução da capacidade de recuperação de forma, dificultando o efeito memória de forma do material. O TCP propiciou a estabilização da fase martensítica (β’1 ) e, por consequência, a manutenção das temperaturas de transformação de fase e da capacidade de recuperação de forma do efeito memória de forma da liga.Deep cryogenic treatment (TCP) is commonly used in industry to improve the wear resistance characteristics of tool steels. However, little is knows about its effects on non-ferrous metals. The objective of this work was to investigate how the TCP affects the properties and behavior of the Cu-14Al4Ni alloy treated at different immersion times and submitted to thermomechanical cycling. A comparative experimental analysis of transformation temperatures, microhardness and recovery capacity in the alloy obtained by casting was carried out, treated by TCP and cycled thermomechanically. The results showed that thermomechanical cycling provided the appearance and growth of the phase martensitic (γ’1), less ductile than the martensitic phase (β’1), and produced an increase of martensitic transformation temperatures and of material microhardness, in addition to the reduction the shape recovery capacity, making the memory effect of the material difficult. TCP provided the stabilization of the martensitic phase (β’1) and, consequently, the maintenance of phase transformation temperatures and of the shape recovery capacity of the alloy shape memory effect

Neotropical freshwater fisheries : A dataset of occurrence and abundance of freshwater fishes in the Neotropics

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications