Presenting a low Ductile–Brittle transition temperature compared to other body-centered cubic structural steels, lath martensitic steels, such as 9Ni steels, are the most prominent high-strength ...steels proposed for low-temperature and cryogenic services. In the past couple of decades, broad access to tools and instrumentation required to map complex crystallographic relations allowed authors to draw several relations between the lath martensite microstructure and the mechanical properties of those steels. Recently, morphological heterogeneity of lath martensite microstructure has been pointed out as a microstructural feature responsible for the scattering in local yield strength within the microstructure, with coarse martensite laths acting as soft zones with enhanced deformation ability. The present work conducts an investigation covering macro- to micro-plasticity of 9Ni steel-welded joints, focusing on the heat-affected zone (HAZ) and the contribution of these coarse laths to the strain mechanisms of the microstructure. Tensile tests and Electron Backscatter Diffraction (EBSD) analyses were conducted over a selected area in tensile specimens at progressive strain levels. Local strain measurements revealed that the coarse-grained HAZ (CGHAZ) is the only HAZ region that experiences significant strain, with the Subcritically reheated CGHAZ (SC-CGHAZ) presenting the highest strain levels. Regarding the coarse lath contribution, EBSD analyses revealed that, up to 7 pct strain, these coarse constituents present a progressive increase in geometrically necessary dislocations density increasing rate, indicating that they may carry plasticity for even further stages of the plastic regime. However, at the beginning of plastic deformation, dislocation activity is mainly observed at thin lath areas due to the deformation-driven martensitic transformation of interlath austenite films.
Graphical Abstract
Flexible risers are critical equipment for the production of oil and gas in offshore fields around the world. The annulus region may condense acidic water containing H2S exposing the tensile armour ...steel wires to a sour environment, which may promote sulphide stress cracking (SSC) and/or hydrogen-induced cracking (HIC). This work aims to evaluate through electrochemical and constant displacement tests the effectiveness of thermal spray aluminium (TSA) coating to mitigate SSC and HIC in high strength steel used to manufacture the tensile armour of a flexible riser. Electrochemical tests confirmed the anodic behaviour of the coating against the steel and estimated a service life of 2.5 years. The constant displacement test indicated that the non-coated samples failed by SSC although some cracks were also found in the samples mid-section due to HIC. For Al-coated samples, no signs of SSC and HIC were observed. The TSA coating showed a dual barrier effect, hindering either corrosion of steel or hydrogen up-taking, and neither SSC nor HIC was observed. Samples with a coating defect were cathodically protected and no HIC was observed.
•Non-coated steel failured by sulphide stress cracking (SSC) and showed cracks associated to hydrogen-induced cracking (HIC);•Thermal spray aluminium (TSA) coating suppressed SSC due the barrier effect and the cathodic protection;•TSA limited the hydrogen diffusion which hindered the HIC.
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•We performed a fracture toughness assessment of two-pass FSW welded joints.•CTOD testing were performed at five temperatures and three different notch locations.•The stirred zone in ...both configuration presented high CTOD results until −20°C.•The hard zones presented an active role decreasing the toughness in low temperatures.
Friction stir welding (FSW) is a promising candidate for use in pipeline steels because it offers high productivity and sound welded joints. This study presents a fracture toughness assessment of FSW-welded two-pass butt joints, different regions within the joints and tests temperatures (25°C, −15°C, −20°C, −35°C, −40°C) were used. Base plates of API-X80 steel 12mm thick were FSW-welded using two different pass sequences, coincident and alternate directions. The results presented consistently high toughness values down to −20°C for all the assessed notches, which indicates that FSW may be suitable for general pipelines steels applications in that range of temperatures.
9Ni steels have been recently adopted in supercritical CO2 injection systems in deepwater oil fields. The manufacture of these reinjection systems involves multi-pass welding procedures, which ...produce an Heat-Affected Zone (HAZ) with a high heterogeneity level regarding the microstructural features and the local mechanical properties. An extensive microstructural and micromechanical characterisation was performed over the HAZ of three welded joints with different heat-input conditions to evaluate the effects of the reheating cycles and the welding parameters on the microconstituents. Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD) analyses were performed to identify microstructural features that correlate to the local mechanical responses evaluated through an extensive microhardness mapping. Regarding the Coarse Grained HAZ (CGHAZ), the highest microhardness values for all welding conditions are found at the Supercritically Reheated CGHAZ (SCR-CGHAZ), characterised by its refined microstructure and a quite low area fraction of coarse martensite laths. The Subcritically Reheated CGHAZ (SC-CGHAZ) and the Intercritically Reheated CGHAZ (IC-CGHAZ) – regions where wider martensite blocks and higher coarse martensite lath area fractions were observed – composed the softer zones of the microhardness map. It was also found that reheating at intercritical temperatures induces the formation of supersaturated fresh martensite and may contribute to retained/reversed austenite particles’ C-enrichment, which may degrade the mechanical properties at the IC-CGHAZ.
Aging is a degenerative process marked by recognized functional, physiological, and metabolic impairments, such as dynapenia and diminished cognitive capacity. Therefore, the search for innovative ...strategies to prevent/delay these physiological and cognitive disorders is essential to guarantee the independence and life quality of an elderly population. The aim of this work is to verify the effect of a 12-week resistance exercise program on the general physical aptitude and cognitive capacities of elderly and sedentary women. Twenty-nine women (65.87±5.69 years) were divided into two groups. The control group was composed of eight elderly women who met the same inclusion criteria of the study and the strength training group was composed of 29 elderly women who were subjected to a resistance exercise program defined by 12 upper and lower limb exercises combined in 3×10 repetitions with 1-minute interval between repetitions and two resting minutes between exercises (three times/week). Weight loads were fixed between 60% and 75% of the apparent 1 repetition maximum, which was estimated by the test of 10 maximum repetitions. The direct curl was performed for upper body strength evaluation with 2.3 kg dumbbells for 30 seconds, whereas the chair test was used for lower body evaluation (total sit-stand movements in 30 seconds). The cognitive capacities of subjects were evaluated by "The Montreal Cognitive Assessment" questionnaire. After 12 weeks, the elderly group showed significant increases in the average upper body strength (58%), lower body strength (68%), and cognitive capacity (19%). The present study demonstrated that regular resistance exercises could provide significant gains on the upper and lower body strength concomitant to positive improvements on cognitive capacities of elderly women, bringing enhanced life quality.
Heme crystallization as hemozoin represents the dominant mechanism of heme disposal in blood feeding triatomine insect vectors of the Chagas disease. The absence of drugs or vaccine for the Chagas ...disease causative agent, the parasite Trypanosoma cruzi, makes the control of vector population the best available strategy to limit disease spread. Although heme and redox homeostasis regulation is critical for both triatomine insects and T. cruzi, the physiological relevance of hemozoin for these organisms remains unknown. Here, we demonstrate that selective blockage of heme crystallization in vivo by the antimalarial drug quinidine, caused systemic heme overload and redox imbalance in distinct insect tissues, assessed by spectrophotometry and fluorescence microscopy. Quinidine treatment activated compensatory defensive heme-scavenging mechanisms to cope with excessive heme, as revealed by biochemical hemolymph analyses, and fat body gene expression. Importantly, egg production, oviposition, and total T. cruzi parasite counts in R. prolixus were significantly reduced by quinidine treatment. These effects were reverted by oral supplementation with the major insect antioxidant urate. Altogether, these data underscore the importance of heme crystallization as the main redox regulator for triatomine vectors, indicating the dual role of hemozoin as a protective mechanism to allow insect fertility, and T. cruzi life-cycle. Thus, targeting heme crystallization in insect vectors represents an innovative way for Chagas disease control, by reducing simultaneously triatomine reproduction and T. cruzi transmission.
Termites are considered one of the most efficient decomposers of lignocelluloses on Earth due to their ability to produce, along with its microbial symbionts, a repertoire of carbohydrate-active ...enzymes (CAZymes). Recently, a set of Pro-oxidant, Antioxidant, and Detoxification enzymes (PAD) were also correlated with the metabolism of carbohydrates and lignin in termites. The lower termite
is considered the main urban pest in Brazil, causing damage to wood constructions. Recently, analysis of the enzymatic repertoire of
unveiled the presence of different CAZymes. Because the gene profile of CAZy/PAD enzymes endogenously synthesized by
and also by their symbiotic protists remains unclear, the aim of this study was to explore the eukaryotic repertoire of these enzymes in worker and soldier castes of
. Our findings showed that worker and soldier castes present similar repertoires of CAZy/PAD enzymes, and also confirmed that endo-glucanases (GH9) and beta-glucosidases (GH1) were the most important glycoside hydrolase families related to lignocellulose degradation in both castes. Classical cellulases such as exo-glucanases (GH7) and endo-glucanases (GH5 and GH45), as well as classical xylanases (GH10 and GH11), were found in both castes only taxonomically related to protists, highlighting the importance of symbiosis in
. Moreover, our analysis revealed the presence of Auxiliary Activity enzyme families (AAs), which could be related to lignin modifications in termite digestomes. In conclusion, this report expanded the knowledge on genes and proteins related to CAZy/PAD enzymes from worker and soldier castes of lower termites, revealing new potential enzyme candidates for second-generation biofuel processes.
Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong ...biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year‐on‐year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non‐vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its ‘Minimal Information for Studies of Extracellular Vesicles’, which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly.
Bone sporotrichosis is rare. The metropolitan region of Rio de Janeiro is hyperendemic for zoonotic sporotrichosis and the bone presentations are increasing.
We studied a retrospective cohort of 41 ...cases of bone sporotrichosis, diagnosed from 1999-2016. The inclusion criteria was fungal culture isolation from any clinical specimen associated to bone involvement (radiography and/or computed tomography) compatible with fungal osteomyelitis or histopathological findings of bone material compatible with sporotrichosis. Molecular identification was performed when possible.
Male patients represented 58.5% of the cases, with a cohort median age of 43 years. Immunosuppressive conditions were present in 68.3% of the patients, mostly HIV coinfection (51.2%). Multifocal bone involvement (more than one anatomical segment) was diagnosed in 61% of the patients, while 39% presented unifocal involvement. The bones of the hands were the most affected (58.5%), followed by the feet (41.5%) and tibia (26.8%). Multifocal group was characterized by a higher proportion of males (p = 0.0045) with immunosuppressive conditions (p = 0.0014). Amphotericin B followed by oral itraconazole was the main treatment, with a median time of 16.7 months (1.5 to 99.2 months), and cure of 53.7% of the patients (84.6% of immunocompetent and 39.3% of immunocompromised patients). Sequelae occurred in 12.2% of the patients-amputations (7.3%) and ankylosis (4.9%), while 22% died in the course of the disease. Sporothrix brasiliensis was the causative agent in all the 9 (22%) performed cases.
Bone sporotrichosis is a chronic, challenging condition with prolonged treatment, often with poor results and sequelae.
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