The present investigation is focused on assessing the effect of a thermal treatment for grain coarsening on the low cycle fatigue damage evolution in two types of Lean Duplex Stainless Steels ...(LDSSs). The dislocation structure developed during cycling is observed by transmission electron microscopy (TEM). Additionally, a detailed analysis of short crack initiated and grown during low cycle fatigue (LCF) is performed by means of optical and scanning electron (SEM) microscopy in combination with automated electron back-scattered diffraction (EBSD) technique. Though in both coarse-grained LDSSs the short cracks nucleate in the ferrite phase, in each steels its origin is different. The embrittlement caused by the Cr2N precipitation and the plastic activity sustained by each phase can explain this difference. The propagation behavior of the short cracks present two alternative growing mechanisms: the crack grows along a favorable slip plane with high Schmid Factor (SF) or the crack alternates between two slip systems. In both cases, the crack follows the path with the smallest tilt angle (β) at a grain boundary.
Tibial spine avulsion fractures are mostly a paediatric injury which appropriate treatment is currently debated in literature. The choice between conservative and surgical treatment is based on the ...radiographic classification of Meyers-McKeever. The most diffused surgical techniques involve either internal fixation devices (screws) or bone tunnels fixation with resorbable sutures. Today, a third option is represented by resorbable magnesium screws which could combine the best features of the two classical systems. Objective of this study is to investigate the efficacy of these new devices in the surgical treatment of tibial spine avulsions.
Since 2014 we have seen seven patients with tibial eminence fracture. Patients underwent clinical and radiological examination (MRI, CT scan) before surgery. Only 3 patients that presented with a grade III or IV lesion were treated surgically with internal fixation with magnesium resorbable screws. In post-operative follow-up, functional recovery was evaluated at 1, 2, 4, 6 and 12 months, clinically and by X-ray. Lysholm and IKDC scores were submitted at 1, 2, 6 and 12 months. MRI was repeated at 6 and 12 months.
All three surgical patients showed progressive clinical and functional improvement during the follow-up period. The first case showed a quicker overall recovery rate, which might be due to the lower grade of the lesion. Radiographs and MRI evaluation showed regular healing of the injury. The devices appeared completely resorbed at the 6 months follow-up and replaced by newly formed bone at the 12 months follow-up.
The treatment of tibial spine avulsion fractures with arthroscopic reduction and internal fixation (ARIF) technique by magnesium resorbable screws seems to result in an excellent functional recovery without complications related to fixation devices, which were completely resorbed after 6 months and replaced by newly formed bone after 12 months. This new method could be considered as an alternative option to classic techniques by non resorbable fixation devices or bone tunnel fixation. Further studies are needed in order to evaluate the efficacy of these new devices in a wider group of patients.
Abstract
Pairing effects in non-uniform nuclear matter, surrounded by electrons, are studied in the protoneutron star early stage and in other conditions. The so-called nuclear pasta phases at ...subsaturation densities are solved in a Wigner–Seitz cell, within the Thomas–Fermi approximation. The solution of this problem is important for the understanding of the physics of a newly born neutron star after a supernova explosion. It is shown that the pasta phase is more stable than uniform nuclear matter on some conditions and the pairing force relevance is studied in the determination of these stable phases.
Tungsten is considered as one of the most promising materials for nuclear fusion reactor chamber applications. Wire + Arc Additive Manufacture has already demonstrated the ability to deposit ...defect-free large-scale tungsten structures, with considerable deposition rates. In this study, the microstructure of the as-deposited and heat-treated material has been characterized; it featured mainly large elongated grains for both conditions. The heat treatment at 1273 K for 6 h had a negligible effect on microstructure and on thermal diffusivity. Furthermore, the linear coefficient of thermal expansion was in the range of 4.5 × 10−6 μm m−1 K−1 to 6.8 × 10−6 μm m−1 K−1; the density of the deposit was as high as 99.4% of the theoretical tungsten density; the thermal diffusivity and the thermal conductivity were measured and calculated, respectively, and seen to decrease considerably in the temperature range between 300 K and 1300 K, for both testing conditions. These results showed that Wire + Arc Additive Manufacture can be considered as a suitable technology for the production of tungsten components for the nuclear sector.
•· It is possible to produce large-scale components in unalloyed tungsten using Wire + Arc Additive Manufacturing•· Unalloyed tungsten can be deposited via WAAM with a suitable level of integrity, to meet the requirements of the nuclear industry•· The microstructure of unalloyed tungsten deposited via WAAM is characterised by specular arrays of large columnar grains•· The thermal conductivity of tungsten components made by WAAM showed higher values compared to other manufacturing methods•· The thermal conductivity and the thermal diffusivity are not influenced by the direction of testing
Context.
The cyano radical (CN), one of the first detected interstellar molecular species, is a key molecule in many astrochemical chains. In particular, it is detected towards molecular cores, the ...birth places of stars, and it is involved in the rich chemistry that takes place at these sites.
Aims.
At present, there are not many studies on the emission of this molecular species at small spatial scales towards massive young stellar objects. We therefore present a high-angular resolution CN study towards a sample of massive protostars, with the aim of unveiling the spatial distribution at the small scale of the emission of this radical in relation to star-forming processes.
Methods.
The interstellar CN has a strong emission line at the rest frequency 226 874.764 MHz, thus we searched for observing projects in the Atacama Large Millimeter Array (ALMA) database regarding high-mass star-forming regions observed at Band 6. The used data set was observed in ALMA Cycle 3 with angular and spectral resolutions of 0.′′7 and 1.13 MHz, respectively. A sample of ten high-mass star-forming regions located in the first Galactic quadrant were selected on the basis that they present a clear emission of CN at the mentioned frequency.
Results.
We found that the CN traces both molecular condensations and the diffuse and extended gas surrounding them. In general, the molecular condensations traced by the maximums of the CN emission do not spatially coincide with the peaks of the continuum emission at 1.3 mm, which trace the molecular cores where massive stars are born. Based on the presence or lack of near-IR emission associated with such cores, we suggest that our sample is composed of sources at different stages of evolution. The CN is present in all sources, suggesting that this radical may be ubiquitous along the different star formation stages, and hence it may be involved in different chemical reactions occurring during the period of star formation. Additionally, other molecules such as CH
3
OCHO and CH
2
CHCN were detected towards the continuum peaks of some of the analysed cores. We found that the missing flux coming from extended spatial scales that are filtered out by the interferometer is an important issue to take into account in the analysis of some spectral features and the spatial distribution of the emission.
An innovative way of producing large-scale unalloyed tantalum parts, based on the Wire + Arc Additive Manufacturing process, has been developed in this study. Two different unalloyed tantalum wires ...have been used to deposit 200-mm-long structures in tantalum. The effect of the wire chemistry on microstructure, hardness, porosity, mechanical properties and strain localisation has been investigated. The deposits showed high integrity and excellent mechanical properties, with yield strength, ultimate tensile strength and elongation as high as 234 MPa, 261 MPa, and 36%, respectively. Indeed, yield strength was higher than commercially available tantalum, even though, in this study, the grains were large and had a high aspect ratio. Wire + Arc Additive Manufacture has clearly shown the potential to produce tantalum components with relatively low cost and reduced lead time, thus offering a new robust and viable manufacturing route.
•Wire + Arc Additive Manufacture is a suitable technique for the production of unalloyed tantalum components•The chemistry of the tantalum feedstock has a marked effect on porosity, hardness and mechanical properties•The microstructure was characterised by macroscopic bands, caused by the removal of dispersed fine oxide particles•The tensile properties of the deposited walls were comparable to those of the substrate material, unlike the total elongation•Thermal straining and repetitive thermal cycles had a visible effect on hardness and tensile properties
Very low birth weight (VLBW) infants may be at risk for late-onset circulatory collapse (LCC) where otherwise stable infants develop hypotension resistant to vasoactive agents. The risk factors for ...LCC development are poorly defined, and it has been theorized that it may be in part due to withdrawal from exogenous prenatal steroids. The goal of this study was to define the clinical characteristics of LCC and investigate its association with antenatal steroid administration.
This is a retrospective cohort study of infants born ≤1500 g. LCC was retrospectively diagnosed in infants requiring glucocorticoids for circulatory instability at >1 week of life. Demographic and clinical characteristics were compared between groups using Mann-Whitney test.
Three hundred and ten infants were included; 19 (6.1%) developed LCC. Infants with LCC were born at a median 4.6 weeks' lower gestation, 509 g lower birth weight than those without LCC. There was no difference in antenatal steroid delivery between the groups.
LCC occurs in a distinct subset of VLBW infants, suggesting the need for monitoring in this high-risk population. Antenatal steroids did not significantly increase the risk of LCC development in this study.
Late-onset circulatory collapse (LCC) is a life-threatening clinical entity occurring in around 6% in VLBW infants and is likely underdiagnosed in the United States. Targeting specific demographic characteristics such as birth weight (<1000 g) and gestational age at birth (<26 weeks) may allow for early identification of high-risk infants, allowing close monitoring and prompt treatment of LCC. No significant association was found between antenatal steroid administration and LCC development, suggesting that the theoretical risks of antenatal steroids on the fetal HPA axis does not outweigh the benefits of antenatal steroids in fetal lung maturity. To date, no studies characterizing LCC have originated outside of Asia. Therefore, providing a description of LCC in a U.S.-based cohort will provide insight into both its prevalence and presentation to inform clinicians about this potentially devastating disorder and foster early diagnosis and treatment. This study validates LCC characteristics and prevalence previously outlined by Asian studies in a single-center U.S.-based cohort while also identifying potential risk factors for LCC development. This manuscript will provide education for U.S. physicians about the risk factors and clinical presentation of LCC to facilitate early diagnosis and treatment, potentially decreasing neonatal mortality. With prompt recognition and treatment of LCC, infants may have decreased exposure to vasoactive medications that have significant systemic effects.
Excessive and prolonged activity of inflammatory monocytes is a hallmark of many diseases with an inflammatory component. In such conditions, precise targeting of these cells could be therapeutically ...beneficial while sparing many essential functions of the innate immune system, thus limiting unwanted effects. Inflammatory monocytes-but not the noninflammatory subset-depend on the chemokine receptor CCR2 for localization to injured tissue. Here we present an optimized lipid nanoparticle and a CCR2-silencing short interfering RNA that, when administered systemically in mice, show rapid blood clearance, accumulate in spleen and bone marrow, and localize to monocytes. Efficient degradation of CCR2 mRNA in monocytes prevents their accumulation in sites of inflammation. Specifically, the treatment attenuates their number in atherosclerotic plaques, reduces infarct size after coronary artery occlusion, prolongs normoglycemia in diabetic mice after pancreatic islet transplantation, and results in reduced tumor volumes and lower numbers of tumor-associated macrophages.
PDF
