Micro-abrasion-corrosion interactions of Ni-Cr/WC based coatings : approaches to construction of tribo-corrosion maps for the abrasion-corrosion synergism

The process of micro-abrasion-corrosion has been the subject of much research in recent years due to the fact that the action of micron sized particles, typically less than 10 um in diameter, can cause significant degradation of materials in many diverse environments involving aqueous corrosion. Cermet based coatings are often used to combat micro-abrasion-corrosion, but has been little work carried out to characterize the performance of such coatings exposed to micro-abrasion-corrosion or to provide a basis for coating optimisation. In addition, a basis for defining the various micro-abrasion-corrosion interactions has not been suggested to date. In this study the micro-abrasion-corrosion performance of a Ni-Cr/WC coating was assessed and compared to the performance of the steel substrate. The results were used to identify regimes of micro-abrasion as a function of applied load and pH of the solution. In addition, micro-abrasion-corrosion maps were constructed based on the results, showing the variation between micro-abrasion-corrosion regimes, as a function of applied load and pH of the solution

Properties and occurrence rates of KeplerKepler exoplanet candidates as a function of host star metallicity from the DR25 catalog

Correlations between the occurrence rate of exoplanets and their host star properties provide important clues about the planet formation processes. We studied the dependence of the observed properties of exoplanets (radius, mass, and orbital period) as a function of their host star metallicity. We analyzed the planetary radii and orbital periods of over 2800 $Kepler$ candidates from the latest $Kepler$ data release DR25 (Q1-Q17) with revised planetary radii based on $Gaia$~DR2 as a function of host star metallicity (from the Q1-Q17 (DR25) stellar and planet catalog). With a much larger sample and improved radius measurements, we are able to reconfirm previous results in the literature. We show that the average metallicity of the host star increases as the radius of the planet increases. We demonstrate this by first calculating the average host star metallicity for different radius bins and then supplementing these results by calculating the occurrence rate as a function of planetary radius and host star metallicity. We find a similar trend between host star metallicity and planet mass: the average host star metallicity increases with increasing planet mass. This trend, however, reverses for masses $> 4.0\, M_\mathrm{J}$: host star metallicity drops with increasing planetary mass. We further examined the correlation between the host star metallicity and the orbital period of the planet. We find that for planets with orbital periods less than 10 days, the average metallicity of the host star is higher than that for planets with periods greater than 10 days.Comment: 14 pages, 13 Figures, Accepted for publication in The Astronomical Journa

Structure and lattice dynamics of the wide band gap semiconductors MgSiN2_{2} and MgGeN2_{2}

We have determined the structural and lattice dynamical properties of the orthorhombic, wide band gap semiconductors MgSiN$_{2}$ and MgGeN$_{2}$ using density functional theory. In addition, we present structural properties and Raman spectra of a MgSiN$_{2}$ powder. The structural properties and lattice dynamics of the orthorhombic systems are compared to wurtzite AlN. We find clear differences in the lattice dynamics between MgSiN$_{2}$, MgGeN$_{2}$ and AlN, for example we find that the highest phonon frequency in MgSiN$_{2}$ is about 100~cm$^{-1}$ higher than the highest frequency in AlN and that MgGeN$_{2}$ is much softer. We also provide the Born effective charge tensors and dielectric tensors of MgSiN$_{2}$, MgGeN$_{2}$ and AlN. Phonon related thermodynamic properties, such as the heat capacity and entropy, are in very good agreement with available experimental results.Comment: 9 pages, 11 figures, 6 table

Design of a low-noise aeroacoustic wind tunnel facility at Brunel University

This paper represents the design principle of a quiet, low turbulence and moderately high speed aeroacoustic wind tunnel which was recently commissioned at Brunel University. A new hemi-anechoic chamber was purposely built to facilitate aeroacoustic measurements. The wind tunnel can achieve a maximum speed of about 80 ms-1. The turbulence intensity of the free jet in the potential core is between 0.1–0.2%. The noise characteristic of the aeroacoustic wind tunnel was validated by three case studies. All of which can demonstrate a very low background noise produced by the bare jet in comparison to the noise radiated from the cylinder rod/flat plate/airfoil in the air stream.The constructions of the aeroacoustic wind tunnel and the hemi-anechoic chamber are financially supported by the School of Engineering and Design at Brunel University

Using Noninvasive Brain Measurement to Explore the Psychological Effects of Computer Malfunctions on Users during Human-Computer Interactions

In today’s technologically driven world, there is a need to better understand the ways that common computer malfunctions affect computer users. These malfunctions may have measurable influences on computer user’s cognitive, emotional, and behavioral responses. An experiment was conducted where participants conducted a series of web search tasks while wearing functional nearinfrared spectroscopy (fNIRS) and galvanic skin response sensors. Two computer malfunctions were introduced during the sessions which had the potential to influence correlates of user trust and suspicion. Surveys were given after each session to measure user’s perceived emotional state, cognitive load, and perceived trust. Results suggest that fNIRS can be used to measure the different cognitive and emotional responses associated with computer malfunctions. These cognitive and emotional changes were correlated with users’ self-report levels of suspicion and trust, and they in turn suggest future work that further explores the capability of fNIRS for the measurement of user experience during human-computer interactions

Evaluation of insulin and C-peptide in diabetic patients undergoing renal dialysis

Background: Patients with kidney failure associated with diabetes mellitus have disturbed responses of several glucoregulatory hormones. Diabetic nephropathy is the leading cause of end stage renal disease (ESRD). Renal failure is the progressive loss of function of kidney and patient requires a long renal replacement therapy, during which body’s waste products including urea, creatinine, glucoregulatory hormones and excess water are removed. Objectives of the study were to evaluate insulin and c-peptide concentrations in diabetic patients on renal dialysis and to compare the concentration of insulin, c-peptide, random blood glucose, urea and creatinine in pre and post dialysis samples of both controlled and uncontrolled diabetic patients.Methods: The study was conducted in 30 patients with diabetic kidney disease undergoing renal dialysis. The patients were grouped as controlled diabetics and uncontrolled diabetics based on their HbA1c levels.  Pre and post dialysis blood samples were collected from patients. Concentration of insulin and c-peptide were analyzed by using ELISA methods. Random blood glucose (RBG), urea and creatinine were estimated by standard methods.Results: The patients were divided into 2 groups depending on their HbA1c levels as controlled and uncontrolled diabetes mellitus. The concentration of insulin, c-peptide, RBG, serum urea and creatinine showed statistically significant reduction in post dialysis samples when compared to pre dialysis in uncontrolled diabetics. But in case of controlled diabetes mellitus reduction was observed in the levels of insulin and c- peptide in post dialysis samples as compared to pre dialysis samples, but, the difference was not statistically significant.Conclusions: There are alterations in the levels of insulin, c-peptide and the glycemic status in diabetic patients during dialysis. This significant reduction may affect glucose metabolism in diabetic patients on dialysis. Hence, glycemic status should be continuously monitored in these patients

Emergence of cosmic space in Tsallis modified gravity from equilibrium and non-equilibrium thermodynamic perspective

The profound connection between the law of emergence and the thermodynamic laws provides a new thermodynamic perspective on the accelerated expansion of the universe. In this paper, we explore this connection in the context of Tsallis entropy in both equilibrium and non-equilibrium perspectives. From an equilibrium perspective, we derive the law of emergence by considering Tsallis entropy as the horizon entropy from the unified first law of thermodynamics and the Clausius relation and is found to be consistent with the earlier proposals \cite{SHEYKHI2018118,Chen2022}. However, when one uses Tsallis entropy as the horizon entropy, the thermal evolution of the system becomes non-equilibrium \cite{10.1093/mnras/stab2671}, which results in the generation of additional entropy, and the first law of thermodynamics will get modified accordingly compared to its usual equilibrium version. We obtained the law of emergence from this modified form of the first law of thermodynamics. The law of emergence thus obtained have a simple form, which explains the emergence of the universe, in terms of the rate of change of the areal volume of the horizon, instead of the effective volume as in the equilibrium case. We have further shown that the law of emergence also satisfies the condition of the maximization of entropy; thus, the entropy of the universe evolves to a bounded value in the asymptotic future.Comment: 20 page

Leveraging OpenStack and Ceph for a Controlled-Access Data Cloud

While traditional HPC has and continues to satisfy most workflows, a new generation of researchers has emerged looking for sophisticated, scalable, on-demand, and self-service control of compute infrastructure in a cloud-like environment. Many also seek safe harbors to operate on or store sensitive and/or controlled-access data in a high capacity environment. To cater to these modern users, the Minnesota Supercomputing Institute designed and deployed Stratus, a locally-hosted cloud environment powered by the OpenStack platform, and backed by Ceph storage. The subscription-based service complements existing HPC systems by satisfying the following unmet needs of our users: a) on-demand availability of compute resources, b) long-running jobs (i.e., $> 30$ days), c) container-based computing with Docker, and d) adequate security controls to comply with controlled-access data requirements. This document provides an in-depth look at the design of Stratus with respect to security and compliance with the NIH's controlled-access data policy. Emphasis is placed on lessons learned while integrating OpenStack and Ceph features into a so-called "walled garden", and how those technologies influenced the security design. Many features of Stratus, including tiered secure storage with the introduction of a controlled-access data "cache", fault-tolerant live-migrations, and fully integrated two-factor authentication, depend on recent OpenStack and Ceph features.Comment: 7 pages, 5 figures, PEARC '18: Practice and Experience in Advanced Research Computing, July 22--26, 2018, Pittsburgh, PA, US

Ruptured gallbladder as the first presentation of breast cancer

<p>Abstract</p> <p>Background</p> <p>Perforation of the gall bladder as a first presentation of breast cancer has not been reported.</p> <p>Case presentation</p> <p>Here we present a case of an elderly lady with acute abdomen with evidence of possible perforation of gall bladder on CT scan. Histopathology of the cholecystectomy specimen revealed invasive lobular breast cancer.</p> <p>Her metastatic breast cancer with right sided primary discovered subsequent to her presentation with acute abdomen is managed successfully with Anastrozole.</p> <p>Conclusion</p> <p>We present a rare case of gall bladder perforation from metastatic breast cancer.</p

Improved mechanical and microstructural performance of high-density polyethylene-chitosan-hydroxyapatite composites as potential bone implant materials

High-density polyethylene (HDPE)-chitosan-hydroxyapatite hybrid composite series with varying concentration of hydroxyapatite were prepared and compared with its corresponding HDPE-chitosan binary composite. The microstructural and mechanical characterizations of the prepared composites were studied. A 12% increase for the composite system with 8 wt% hydroxyapatite (HA4) has been noted when compared with its corresponding binary system and has been optimized for further applications. The structural characterization and miscibility of the components in the composite system were studied by using Fourier transform infrared spectroscopy and X-ray diffractometry. Positron annihilation lifetime spectroscopy studies showed that the free holes are formed in the range of similar to 115.8 angstrom(3). Contact angle studies and sorption studies were further correlated with the biocompatibility analysis to study cell adhesion and protein absorption on the surface of the composites. MC3T3 E1 cell lines showed good cell proliferation on the optimized systems. The presence of micropores along with chitosan and hydroxyapatite promoted cell growth in the prepared composites. The current research study presents the development of an improved hybrid biocomposite material that has potential in biomedical implants. (C) 2022 Elsevier Ltd. All rights reserved