Effects of TIG Reheating on Duplex Stainless Steel Weld Microstructure

Duplex stainless steels (DSS) gaining their excellent mechanical properties and corrosion resistance due to their austenitic-ferritic microstructure, ideally in the same amount. However, to keep this ideal phase ratio during arc welding is very difficult. Generally, the arc welding processes will result in more ferritic microstructure in the weld metal and in the heat affected zone, due to the rapid cooling. The ferritic microstructure can cause chromium-nitride precipitation, because the nitrogen solubility in ferrite phase is very low below 700 °C. These chromium-nitride precipitations can cause loss of corrosion resistance and mechanical properties. However, during sub-sequent reheating, the chromium-nitrides can dissolve and act as a secondary austenite nucleation site in the ferritic microstructure. In our research we welded DSS specimen autogenously, with tungsten inert gas welding using pure argon and 94 % argon + 6 % nitrogen as shielding gasses. In the first case the sub-sequent solid-state reheating caused 20 % increase in the austenite fraction of the weld metal but with the use of mixed shielding gas only 5 % increase

Interactions of CaO with pure Mg and Mg-Ca alloys—an in situ synchrotron radiation diffraction study

Data availability statement: The data cannot be made publicly available upon publication because no suitable repository exists for hosting data in this field of study. The data that support the findings of this study are available upon reasonable request from the authors.CaO additions are used as an inexpensive replacement for Ca in Mg alloys. CaO dissociation in Mg has been reported in literature without a clear mechanism as to why this occurs. In situ synchrotron radiation diffraction investigation of the melting and solidification of Mg with CaO shows, that the stability of CaO was overestimated in Mg melts compared with MgO. The experiments that were performed on the Mg-20CaO and Mg-xCa-6CaO (x = 6 and 16 wt.%) alloys, show the dissociation and formation of various phases during melting and solidification. The results indicate that Mg can reduce CaO even in the solid state, which is the opposite of that proposed by the Ellingham diagrams for stoichiometric reaction. Phase formations during the in situ experiment are compared with published thermodynamic calculations for the interaction between Mg-Ca alloys and oxides.The authors acknowledge the Deutsches Elektronen-Synchrotron (DESY) in Hamburg, Germany, for the provision of synchrotron radiation facilities within the framework of the proposal I-20130330 and the Federal Ministry for Economic Affairs and Energy (BMWi) for funding the project MagHyM (20K1107B)

Simulation of a research reactor reactivity transient with deterministic and GPU-assisted Monte Carlo reactor kinetics codes

Reactor kinetic codes are crucial in safety assessment. Validating spatial and high temporal resolution kinetic solvers without thermal feedback is problematic as measurements seldom involve detailed spatial and fine temporal resolution. Benchmarking of deterministic codes thus often resorts to code-to-code comparison against Monte Carlo codes, which can only recently treat direct time dependence. In this paper, we have attempted to compare results from the GUARDYAN directly time-dependent Monte Carlo code and the SEnTRi transient driver developed for the PARTISN deterministic transport code to low power transient measured at the BME Training Reactor. Code-to-measurement comparisons were successful, despite a major uncertainty in the actual timing of the reactivity insertion and withdrawal originating from the instrumentation of the pneumatic rabbit system. Code-to-code comparisons concluded that time dependence was correctly implemented in both GUARDYAN and SEnTRi; furthermore, a hypothetical scenario was set up involving an instantaneous insertion of a negative reactivity into the BME TR core in order to compare spatially and temporally dependent fluxes. The simulations demonstrated the appearance of higher-order modes, and results showed a relatively good match, although fidelity of the comparison could be further improved by reducing the statistical uncertainty of the results provided by GUARDYAN

Scaling behavior in crackle sound during lung inflation

During slow inflation of lung lobes, we measure a sequence of short explosive transient sound waves called "crackles," each consisting of an initial spike followed by ringing. The crackle time series is irregular and intermittent, with the number of spikes of size s following a power law, n(s)proportional to s(-alpha), with alpha = 2.77 +/- 0.05. We develop a model of crackle wave generation and propagation in a tree structure that combines the avalanchelike opening of airway segments with the wave propagation of crackles in a tree structure. The agreement between experiments and simulations suggests that (i) the irregularities are a consequence of structural heterogeneity in the lung, (ii) the intermittent behavior is due to the avalanchelike opening, and (iii) the scaling is a result of successive attenuations acting on the sound spikes as they propagate through a cascade of bifurcations along the airway tree. [S1063-651X(99)13810-8]

Fibromuscular Arterial Disease

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75604/1/j.1440-1673.1970.tb01633.x.pd

Reliability of Synaptic Transmission at the Synapses of Held In Vivo under Acoustic Stimulation

BACKGROUND:The giant synapses of Held play an important role in high-fidelity auditory processing and provide a model system for synaptic transmission at central synapses. Whether transmission of action potentials can fail at these synapses has been investigated in recent studies. At the endbulbs of Held in the anteroventral cochlear nucleus (AVCN) a consistent picture emerged, whereas at the calyx of Held in the medial nucleus of the trapezoid body (MNTB) results on the reliability of transmission remain inconsistent. In vivo this discrepancy could be due to the difficulty in identifying failures of transmission. METHODS/FINDINGS:We introduce a novel method for detecting unreliable transmission in vivo. Based on the temporal relationship between a cells' waveform and other potentials in the recordings, a statistical test is developed that provides a balanced decision between the presence and the absence of failures. Its performance is quantified using simulated voltage recordings and found to exhibit a high level of accuracy. The method was applied to extracellular recordings from the synapses of Held in vivo. At the calyces of Held failures of transmission were found only rarely. By contrast, at the endbulbs of Held in the AVCN failures were found under spontaneous, excited, and suppressed conditions. In accordance with previous studies, failures occurred most abundantly in the suppressed condition, suggesting a role for inhibition. CONCLUSIONS/SIGNIFICANCE:Under the investigated activity conditions/anesthesia, transmission seems to remain largely unimpeded in the MNTB, whereas in the AVCN the occurrence of failures is related to inhibition and could be the basis/result of computational mechanisms for temporal processing. More generally, our approach provides a formal tool for studying the reliability of transmission with high statistical accuracy under typical in vivo recording conditions

As cast microstructures on the mechanical and corrosion behaviour of ZK40 modified with Gd and Nd additions

The microstructure of ZK40, ZK40 with 2 wt% of Nd and Gd (ZK40-2Nd and ZK40-2Gd, respectively) were investigated with optical, scanning and transmission electron microscopy, X-ray diffraction and Scanning Kelvin Probe Force Microscopy. The mechanical properties and the corrosion behaviour were correlated with the microstructure. The 2 wt% Gd addition enhanced the ductility, while the Nd addition resulted in deterioration in mechanical properties. The corrosion behaviour was also enhanced with the addition of Gd.The authors acknowledge the Deutsches Elektronen-Synchrotron (DESY) for the provision of facilities within the framework of proposal I-20130434. RHB acknowledges University of Sao Paulo for granting the fellowship ´Bolsa Empreendedorismo´. MM acknowledges the Alexander von Humboldt foundation for the provision of financial support in the form of post-doctoral fellowship

Fluid challenges in intensive care: the FENICE study A global inception cohort study

Fluid challenges (FCs) are one of the most commonly used therapies in critically ill patients and represent the cornerstone of hemodynamic management in intensive care units. There are clear benefits and harms from fluid therapy. Limited data on the indication, type, amount and rate of an FC in critically ill patients exist in the literature. The primary aim was to evaluate how physicians conduct FCs in terms of type, volume, and rate of given fluid; the secondary aim was to evaluate variables used to trigger an FC and to compare the proportion of patients receiving further fluid administration based on the response to the FC.This was an observational study conducted in ICUs around the world. Each participating unit entered a maximum of 20 patients with one FC.2213 patients were enrolled and analyzed in the study. The median [interquartile range] amount of fluid given during an FC was 500 ml (500-1000). The median time was 24 min (40-60 min), and the median rate of FC was 1000 [500-1333] ml/h. The main indication for FC was hypotension in 1211 (59 %, CI 57-61 %). In 43 % (CI 41-45 %) of the cases no hemodynamic variable was used. Static markers of preload were used in 785 of 2213 cases (36 %, CI 34-37 %). Dynamic indices of preload responsiveness were used in 483 of 2213 cases (22 %, CI 20-24 %). No safety variable for the FC was used in 72 % (CI 70-74 %) of the cases. There was no statistically significant difference in the proportion of patients who received further fluids after the FC between those with a positive, with an uncertain or with a negatively judged response.The current practice and evaluation of FC in critically ill patients are highly variable. Prediction of fluid responsiveness is not used routinely, safety limits are rarely used, and information from previous failed FCs is not always taken into account

Dental Health and Mortality in People With End-Stage Kidney Disease Treated With Hemodialysis: A Multinational Cohort Study

Background Dental disease is more extensive in adults with chronic kidney disease, but whether dental health and behaviors are associated with survival in the setting of hemodialysis is unknown. Study Design Prospective multinational cohort. Setting & Participants 4,205 adults treated with long-term hemodialysis, 2010 to 2012 (Oral Diseases in Hemodialysis [ORAL-D] Study). Predictors Dental health as assessed by a standardized dental examination using World Health Organization guidelines and personal oral care, including edentulousness; decayed, missing, and filled teeth index; teeth brushing and flossing; and dental health consultation. Outcomes All-cause and cardiovascular mortality at 12 months after dental assessment. Measurements Multivariable-adjusted Cox proportional hazards regression models fitted with shared frailty to account for clustering of mortality risk within countries. Results During a mean follow-up of 22.1 months, 942 deaths occurred, including 477 cardiovascular deaths. Edentulousness (adjusted HR, 1.29; 95% CI, 1.10-1.51) and decayed, missing, or filled teeth score ≥ 14 (adjusted HR, 1.70; 95% CI, 1.33-2.17) were associated with early all-cause mortality, while dental flossing, using mouthwash, brushing teeth daily, spending at least 2 minutes on oral hygiene daily, changing a toothbrush at least every 3 months, and visiting a dentist within the past 6 months (adjusted HRs of 0.52 [95% CI, 0.32-0.85], 0.79 [95% CI, 0.64-0.97], 0.76 [95% CI, 0.58-0.99], 0.84 [95% CI, 0.71-0.99], 0.79 [95% CI, 0.65-0.95], and 0.79 [95% CI, 0.65-0.96], respectively) were associated with better survival. Results for cardiovascular mortality were similar. Limitations Convenience sample of clinics. Conclusions In adults treated with hemodialysis, poorer dental health was associated with early death, whereas preventive dental health practices were associated with longer survival