Role of configurational entropy in body-centred cubic or face-centred cubic phase formation in high entropy alloys

This study examines the comparative phase stability of transition and late transition element based high entropy alloys in body-centred cubic (BCC) or face-centred cubic (FCC) forms using a combined classical molecular dynamics and statistical mechanics based approach. Multi-configurational sampling was carried out using a hybrid genetic algorithm-molecular dynamics (GA-MD) based method. The calculations demonstrate that comparative BCC or FCC phase stability is influenced by configurational entropy. The present study also provides a theoretical explanation of the recently reported occurrence of BCC phase in CoCrFeNi HEA, where the high temperature structure may be retained

Electron spin mediated distortion in metallic systems

The deviation of positions of atoms from their ideal lattice sites in crystalline solid state systems causes distortion and it causes variation in structural [1] and functional properties [2]. Severe lattice distortion has been proposed to be one of the core-effect in high-entropy alloys. But the fundamental mechanism of distortion at atomic scale is missing for real three-dimensional metallic systems. The present investigation aims to develop mechanistic understanding of atomic scale distortion in metallic systems in terms of the magneto-volume effects. The correlation between charge-disproportion, spin fluctuations, magneto-volume effects and Fermi surface nesting has been highlighted

Phase stability and distortion in high-entropy oxides

The present investigation demonstrates how configurational entropy stabilises rock-salt type single phase multi-component solid solution oxides. Classical simulations have been used to extensively sample the configurational landscape of such oxides using both random and genetic algorithm sampling strategies. The thermodynamic properties including the enthalpy and free energy of various oxide mixes have been calculated to show the influence of the chemical identity of the oxides on the phase stability. Additionally, a distance analysis between all the cation-cation and cation-anion pairs has been carried out in order to quantify the distortion in the lattice. The correlation between the multiplicity of cations in such systems with consequent enthalpy and configurational entropy has been enumerated and its relation with emergent distortion has been analysed

Matrix metalloproteinase-9 in relation to patients with complications after colorectal surgery: a systematic review

Purpose: Anastomotic leakage (AL) is the most severe complication following colorectal resection and is associated with increased mortality. The main group of enzymes responsible for collagen and protein degradation in the extracellular matrix is matrix metalloproteinases. The literature is conflicting regarding anastomotic leakage and the degradation of extracellular collagen by matrix metalloproteinase-9 (MMP-9). In this systematic review, the

Cytokines as early markers of colorectal anastomotic leakage: A systematic review and meta-analysis

Purpose. Colorectal anastomotic leakage (CAL) is one of the most severe complications after colorectal surgery. This meta-analysis evaluates whether systemic or peritoneal inflammatory cytokines may contribute to early detection of CAL. Methods. Systematic literature search was performed in the acknowledged medical databases according to the PRISMA guidelines to identify studies evaluating systemic and peritoneal levels of TNF, IL-1β, IL-6, and IL-10 for early detection of CAL. Means and standard deviations of systemic and peritoneal cytokine levels were extracted, respectively, for patients with and without CAL. The meta-analysis of the mean differences was carried out for each postoperative day using Review Manager. Results. Seven articles were included. The meta-analysis was performed with 5 articles evaluating peritoneal cytokine levels. Peritoneal levels of IL-6 were significantly higher in patients with CAL compare

A multicentre cohort study of serum and peritoneal biomarkers to predict anastomotic leakage after rectal cancer resection

Aim: Anastomotic leakage (AL) is one of the most feared complications after rectal resection. This study aimed to assess a combination of biomarkers for early detection of AL after rectal cancer resection. Method: This study was an international multicentre prospective cohort study. All patients received a pelvic drain after rectal cancer resection. On the first three postoperative days drain fluid was collected daily and C-reactive protein (CRP) was measured. Matrix metalloproteinase-2 (MMP2), MMP9, glucose, lactate, interleukin 1-beta (IL1β), IL6, IL10, tumour necrosis factor alpha (TNFα), Escherichia coli, Enterococcus faecalis, lipopolysaccharide-binding protein and amylase were measured in the drain fluid. Prediction models for AL were built for each postoperative day using multivariate penalized logistic regression. Model performance was estimated by the c-index for discrimination. The model with the best performance was visualized with a nomogram and calibration was plotted. Results: A total of 292 patients were analysed; 38 (13.0%) patients suffered from AL, with a median interval to diagnosis of 6.0 (interquartile ratio 4.0–14.8) days. AL occurred less often after partial than after total mesorectal excision (4.9% vs 15.2%, P = 0.035). Of all patients with AL, 26 (68.4%) required reoperation. AL was more often treated by reoperation in patients without a diverting ileostomy (18/20 vs 8/18, P = 0.03). The prediction model for postoperative day 1 included MMP9, TNFα, diverting ileostomy and surgical technique (c-index = 0.71). The prediction model for postoperative day 2 only included CRP (c-index = 0.69). The prediction model for postoperative day 3 included CRP and MMP9 and obtained the best model performance (c-index = 0.78). Conclusion: The combination of serum CRP and peritoneal MMP9 may be useful for earlier prediction of AL after rectal cancer resection. In clinical practice, this combination of biomarkers should be interpreted in the clinical context as with any other diagnostic tool

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society