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In order to achieve a full mechanistic understanding of stress corrosion cracking (SCC), the key operating mechanisms need to be identified but also quantified. In this study, we summarize and rationalize key findings from the last 15 years of high-resolution characterization of SCC in our group. A comprehensive characterization of a set of austenitic alloys with different Ni content and constant Cr level, tested under simulated pressurized water reactor (PWR) primary water conditions at various temperatures, has revealed evidence for at least two operating mechanisms: one diffusion-related and the other deformation-related. For their relevance to the nuclear industry, two additional alloys with increased Cr content were also studied (A800 and A690). Key precursors for SCC initiation and propagation are identified and their effect on alloy degradation discussed. A list of key materials’ properties that ensure low SCC susceptibility is proposed.

Tungsten, given its high heat and neutron resistance, is often the material of choice for plasma-facing components in nuclear fusion reactors. However, understanding and predicting the behavior of hydrogen isotopes (deuterium and tritium) within tungsten’s lattice poses a significant challenge. The retention and diffusion of these isotopes, which are influenced by microstructural defects such as vacancies, can significantly impact the performance and safety of fusion devices. This article employs the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) simulation package to analyze the behavior of hydrogen isotopes in tungsten lattices with varying vacancy densities. Simple relationships between penetration depth and energy and mass of hydrogen isotope, as well as between reflection/penetration ratio, are found. The effect of vacancies on isotope diffusion and retention in the material and the role of temperature in this process are investigated.

When manufacturing W for fusion applications, it is crucial to consider microstructural features, such as grain shape and size, dislocation densities, distribution of defects, and impurities. These factors have a significant impact on a component’s lifetime in the fusion environment. This work provides valuable insights into the potential failure mechanisms that impact bulk W components. A bulk W lamella, which was manufactured for the JET divertor as part of the ITER-like wall (ILW) campaigns, was studied. A crack network had formed on the plasma-facing surface of the sample due to electrical discharge machining (EDM). The cracks predominantly propagated around larger grains due to grain misorientation and impurities. Notably, P and Fe were observed via atom probe tomography (APT), which appears to promote the diffusion of O. The results suggest that the initiation of crack propagation is linked to the nucleation of voids which exhibit behavior akin to KSiAl-doped W wires, involving diffusion-driven processes. O signal found inside some of the voids, confirmed by analytical transmission electron microscopy (TEM), suggests W oxide had formed on the internal surface, supporting the theory of oxidation-assisted void formation. It is, therefore, extremely important to consider the distribution of impurities and preexisting surface damage in W plasma-facing components (PFCs) before they are placed in the vessel.

• The morphologies of the internal oxide precipitates in a ferritic steel and an austenitic steel were investigated. • The internal oxide precipitates have a needle-like and a near-spherical morphology in a Fe-9Cr ferritic and a Fe-17Cr-9Ni austenitic steels. • The morphology of the internal oxide precipitates is controlled by the structure of the interfaces between the metal matrix and the internal oxide. • The interface structure is mainly affected by the crystallographic structure of the two phases and their orientation relationship. • There is potential to control the distribution, morphology, and interface structure of the internal oxide precipitates by selecting appropriate base metal and internal oxide-forming element. The internal oxide precipitates were supposed to be spherical in Wagner's original theory, while the following research demonstrated that this assumption is an exception rather than the truth, which caused deviations in the application of this theory. In this study, the internal oxide precipitates have a needle-like and a near-spherical morphology in a Fe-9Cr ferritic and a Fe-17Cr-9Ni austenitic steels after exposure to 600 °C deaerated steam for 600 h, respectively. The nano-to-atomic scale characterization shows that the morphology of the internal oxide precipitates is controlled by the structure of the interfaces between the metal matrix and the internal oxide, while the interface structure is mainly affected by the crystallographic structure of the two phases and their orientation relationship. In addition, the internal oxide precipitation-induced volume expansion and the outward Fe diffusion-induced volume shrink occur simultaneously during the oxidation process. The stress status in the internal oxidation zone (IOZ) is the competing result of the two factors, which could dynamically affect the high-temperature oxidation. The results obtained in this study suggest that there is potential to control the distribution, morphology, and interface structure of the internal oxide precipitates by selecting appropriate base metal and internal oxide-forming element, in order to obtain better high-temperature oxidation-resistant materials. [Display omitted] [ABSTRACT FROM AUTHOR]

The multi-scale chemical composition distribution and microstructure of Alloy 52M overlay on low alloy steel by hot wire plasma arc cladding (HWPC) were characterized. Stress corrosion cracking (SCC) growth rates were quantified in the dilution zone (DZ) near the fusion boundary and in the bulk of Alloy 52M using compact tension samples with a thickened cladding overlay. The DZ of the Alloy 52M side exhibited a single macroscopic dilution zone containing approximately 27-28 wt.% Cr and 50 wt.% Ni, in contrast to the multiple dilution zones observed in the DZ of Alloy 52M overlays or joints prepared using other welding technologies such as submerged arc welding (SMAW). The DZ of the HWPC overlay exhibited less dilution of Cr and Ni compared to SMAW weldment. This resulted in a shorter average SCC band and fewer local intergranular cracks in the DZ of HWPC, as observed from SCC crack growth rate specimens tested in simulated PWR primary water at 325 °C and 350 °C. These findings highlight the advantages of utilizing HWPC to enhance SCC resistance in the DZ of Alloy 52M overlays over conventional cladding technologies.

Background: Dimerization of the myeloid differentiation primary response 88 protein (MyD88) plays a pivotal role in the exacerbated response to innate immunity-dependent signaling in rheumatoid arthritis (RA). ST2825 is a highly specific inhibitor of MyD88 dimerization, previously shown to inhibit the pro-inflammatory gene expression in peripheral blood mononuclear cells from RA patients (RA PBMC). In this study, we elucidated the effect of disrupting MyD88 dimerization by ST2825 on the pathological properties of synovial fibroblasts from RA patients (RA SFs). Methods: RA SFs were treated with varying concentrations of ST2825 in the presence or absence of bacterial lipopolysaccharides (LPS) to activate innate immunity-dependent TLR signaling. The DNA content of the RA SFs was quantified by imaging cytometry to investigate the effect of ST2825 on different phases of the cell cycle and apoptosis. RNA-seq was used to assess the global response of the RA SF toward ST2825. The invasiveness of RA SFs in Matrigel matrices was measured in organoid cultures. SFs from osteoarthritis (OA SFs) patients and healthy dermal fibroblasts were used as controls. Results: ST2825 reduced the proliferation of SFs by arresting the cells in the G0/G1 phase of the cell cycle. In support of this finding, transcriptomic analysis by RNA-seq showed that ST2825 may have induced cell cycle arrest by primarily inhibiting the expression of critical cell cycle regulators Cyclin E2 and members of the E2F family transcription factors. Concurrently, ST2825 also downregulated the genes encoding for pain, inflammation, and joint catabolism mediators while upregulating the genes required for the translocation of nuclear proteins into the mitochondria and members of the mitochondrial respiratory complex 1. Finally, we demonstrated that ST2825 inhibited the invasiveness of RA SFs, by showing decreased migration of LPS-treated RA SFs in spheroid cultures. Conclusions: The pathological properties of the RA SFs, in terms of their aberrant proliferation, increased invasiveness, upregulation of pain and inflammation mediators, and disruption of mitochondrial homeostasis, were attenuated by ST2825 treatment. Taken together with the previously reported anti-inflammatory effects of ST2825 in RA PBMC, this study strongly suggests that targeting MyD88 dimerization could mitigate both systemic and synovial pathologies in a variety of inflammatory arthritic diseases.

In this paper, the simultaneous speciation of the Cr(VI) and Cr(III) ionic species in aqueous solutions was achieved by measuring the current of a cyclic voltammogram at determined potential, under mass transport limiting conditions, using a rotatory disk electrode. The influence of the sensor interface, the rotation speed, and the scan rate potential on the sensibility and time analysis were studied. Quantification of Cr(III) is related to the oxidation process to Cr(VI), while quantification of Cr(VI) is associated to reduction process to Cr(III). From the analysis of cyclic voltammograms at different rotation speed and scan rate, were determined that Cr(III) is controlled by electric charge transference, on the other hand, Cr(VI) is controlled by mass transference. The sensor was modified with ultra-low loading of Au nanoparticles on the carbon nanotubes (CNT), whose improve the quantification of Cr(VI) and Cr(III) compared with the conventional materials.

The road infrastructure industry consumes elevated economic resources and generates vast environmental impacts on the planet. Nevertheless, the construction and maintenance of pavements are necessary to guarantee the economic growth of the communities. In this way, finding novel methods, materials, and techniques is essential to achieve a more sustainable industry. One of the most promising alternatives is the implementation of Perpetual Pavements (PPs). Contrary to the Conventional Flexible Pavements (CFPs) and Conventional Rigid Pavements (CRPs), the PPs are designed for a long service life (even superior to 50 years). During this time, the PPs do not require major Maintenance and Rehabilitation (M&R) activities. Due to this characteristic, PPs could present greater sustainability attributes than conventional pavement structures. However, minimal literature is focused on examining these hypotheses since the state-of-the-art has concentrated on studying the mechanical behavior of materials and layers for PPs laying. Moreover, it is most worrying that few investigations have done this in the context of developing countries, where it is more decisive to perform better decisions in terms of economic-environmental sustainability. Consequently, this research conducts a case study on Barranquilla city (Colombia) to estimate the environmental burdens and monetary costs associated with the life cycle of three pavement alternatives, i.e., a PP, a CFP, and a CRP. The Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) methodologies were employed for these purposes. The results of this investigation demonstrated that PP provides less environmental damage and higher cost-efficiency than the CFP and CRP alternatives. Notably, the most significant contamination potential is provoked by the CRP structure. Meanwhile, the fewer financial profitability is caused by the CFP structure. Therefore, this study indicates that under the typical circumstances of underdeveloped nations, PPs are a more advantageous alternative than traditional ones regarding sustainability performance.

A supersaturated γphase microstructure is produced in Ni-based superalloys using laser powder bed fusion (L-PBF) – the cooling rate arising from the process is shown to suppress the solid-state precipitation of the γ′phase. The response of the material to a heat treatment therefore requires new understanding at the fundamental level, since the first population of γ′precipitate forms upon heating, in contrast to cooling from homogenisation above the γ′solvus. Here, we have interrogated two new nickel-based superalloys designed for the L-PBF technology, both in situand ex situ, at multiple length scales using advanced characterisation methods. First, we conducted in situsynchrotron X-ray diffraction during various heat treatments to trace the evolution of the γ′volume fraction with temperature. The first structural changes were detected at an unexpectedly low temperature of ∼445 °C. Second, the temperature for γ′nucleation and its sensitivity to heating rate was studied using an electrical resistivity method. Then, the γ′composition upon heating, isothermal holding and cooling is analysed using atom probe tomography (APT), the result is rationalised by further scanning-transmission electron microscopy and nanoscale secondary ion mass spectroscopy. Finally, static recrystallisation during isothermal exposure was investigated, which occurs within minutes. This work sheds light on a new strategy of tailoring microstructure for additively manufactured superalloys by manipulation of the γ′precipitate distribution upon heating.

Stress corrosion cracking (SCC) of steels and Ni-base alloys in the pressurized water reactor (PWR) primary circuit has been a cause for reactor outages for many decades. Although the nuclear industry has made a considerable research effort to understand and predict SCC in this system, this enterprise is complicated by the sheer number of interdependent variables that have a major influence on the degradation behavior. SCC is highly time-dependant and often only sets in after many years. Therefore, autoclave testing, even with accelerating conditions, is an expensive and time-consuming endeavor. However, the results collected by a great number of research groups over many years have identified the most important parameters and, in many cases, how they influence the degradation behavior. The community has been constantly working on the development of a general theory that encompasses the underlying mechanisms and is capable of describing and predicting the observed degradation behavior. In the last two decades, the focus of research has shifted from the traditional approach of autoclave testing (for susceptibility and crack growth rates) to high-resolution microscopy and chemical analysis. The newly available techniques are providing data on chemical and structural changes locally at the crack tip where SCC occurs. The techniques covered in this review can provide very high chemical sensitivity at atomic resolution, which is ultimately needed in the quest for a generalized theory.

Synthesis of a novel cathode of bimetallic Pt-Ir nanoparticles deposited on multiwall carbon nanotubes (MWCNT) by a microemulsion method is reported in this paper; the composite material was dispersed with Nafion to deposit a film onto Reticulated Vitreous Carbon (RVC), the modified electrode was used as catalyst in an electrochemical reactor for H2O2 generation. The bimetallic catalyst showed higher activity toward O2 reduction compared to Ir/MWCNT, Pt/MWCNT and MWCNT. The O2 reduction pathway was determined. Only the bimetallic catalyst was found to lead to the reduction of O2 to produce H2O2. A high H2O2 rate was produced with the bimetallic catalyst. This approach was employed to carry out the Fenton process. Experimental evidence for the generation of hydroxyl radicals (*OH) was provided by using coumarin and the fluorescence detection of its hydroxylated product (7-hydroxycoumarin). The Pt-Ir/MWCNT cathode showed very stable behavior and could be reused without decrease of the catalytic activity. This suggests its potential use in wastewater treatment application.

There is scant information on the prevalence and factors associated with preoperative anemia in patients undergoing transcatheter aortic valve implantation (TAVI) and whether it is associated with mortality. We sought to determine the prevalence and factors associated with preoperative anemia in addition to the prognostic effects of the various levels of preoperative hemoglobin level on mortality in patients undergoing TAVI.

Blood transfusion is associated with acute kidney injury (AKI) after transcatheter aortic valve implantation (TAVI). We sought to elucidate in more detail the relation between blood transfusion and AKI and its effects on short- and long-term mortality.

Abstract

In this work, electrochemical generation of ferrate ion (FeO4-2) using a prototype of batch electrochemical reactor with agitation was studied. The anode used was a piece of steel tube (ASTM-A53) of 2 inches of nominal diameter and the cathode used was a steel bar of 0.5 inches. In the electrochemical reactor we did not use membranes, in order to diminish production costs and to make it a much more competitive and attractive process. Two different electrolytes were tested as reactant medium in the system: NaOH (10 M) and KOH (10 M). A current density of 53.62 mA/cm2 was applied with respect to the anode during a period of time of two hours. Afterwards the concentration of ferrate was determined in function of time using a spectroscopy method. It was found that the concentration of ferrate is higher in NaOH as reactant medium than KOH.

The main factor that affects the performance of the arsenic removal from water is its oxidation state. It is known that As (III) is harder to be removed than As(V) due to the fact that H3AsO3 is a nonionic compound with a pK1 = 9.22 while H3AsO4 (As(V)) dissociates ready with a pK1 = 2.25. In the oxygen- poor environment like in groundwater, arsenic exists mainly as As(III). For the purpose of obtaining a higher degree of removal of arsenic from contaminated groundwater, it is necessary to oxidize the As(III) to As(V) prior to the other treatment processes. In this work an electrochemical reactor, having an anode made from reticulated vitreous carbon of 100 pores per inch (100 ppi), was used to oxidize As(III) to As (V), this eliminates the need of adding more chemical substances to the treatment system. The performance of this special designed electrochemical reactor was evaluated at various applied cell voltages, reaction time, the concentration of the supporting electrolyte (NaCl), flow rate of the arsenic (As(III)) contaminated water through the electrochemical reactor and the pH of the aqueous media. Our experimental results indicated that for an aqueous solution containing 1.0 ppm in As(III) and at 3.0 volts applied cell potential with a flow rate at 10 mL/min and 0.10 M in NaCl, the percentage of oxidation of As(III) to As(V) was closer to 100%.

To develop a mathematical model to examine the factors that control the directionality of menstrual flow.

This article presents a new assembling for 2 degrees-of-freedom (DOFs) parallel robots for executing rapid pick-and-place operations with low energy consumption. A conventional design of 2-DOF parallel robots is based on five-bar mechanisms. Collisions between links are highly possible, restricting the end-effector workspace and/or increasing the trajectory time to avoid collisions. In this article, an alternative assembling for preventing collisions is presented. This novel assembling allows exploring the difference between the four five-bar mechanism configurations for the same position of the end-effector. Some of these configurations yield to lower time and/or lower energy consumption for the same motorization. First, a dynamic model of the robot has been developed using matlab® and simulink® and validated by comparison with the results obtained by adams® software. A robust cascade PD regulator for controlling joint coordinates has been tuned providing a high accurate end-effector positioning. Finally, simulation results of four configurations are presented for executing controlled maneuvers. The obtained results demonstrate that the conventional configuration is the worst one in terms of trajectory time or energy consumption and, conversely, the best one corresponds to an uncommonly used configuration. A workspace map where all configurations provide faster maneuvers has been obtained in terms of Jacobian matrix and mechanism elbows distance. The results presented here allow designing a rapid manipulator for pick-and-place operations.

The main factor that affects the performance of the arsenic removal from water is its oxidation state. It is known that As (III) is harder to be removed than As(V) due to the fact that H3AsO3 is a nonionic compound with a pK1 = 9.22 while H3AsO4 (As(V)) dissociates ready with a pK1 = 2.25. In the oxygen- poor environment like in groundwater, arsenic exists mainly as As(III). For the purpose of obtaining a higher degree of removal of arsenic from contaminated groundwater, it is necessary to oxidize the As(III) to As(V) prior to the other treatment processes. In this work an electrochemical reactor, having an anode made from reticulated vitreous carbon of 100 pores per inch (100 ppi), was used to oxidize As(III) to As (V), this eliminates the need of adding more chemical substances to the treatment system. The performance of this special designed electrochemical reactor was evaluated at various applied cell voltages, reaction time, the concentration of the supporting electrolyte (NaCl), flow rate of the arsenic (As(III)) contaminated water through the electrochemical reactor and the pH of the aqueous media. Our experimental results indicated that for an aqueous solution containing 1.0 ppm in As(III) and at 3.0 volts applied cell potential with a flow rate at 10 mL/min and 0.10 M in NaCl, the percentage of oxidation of As(III) to As(V) was closer to 100%.