Experimental and Theoretical Studies on the Viscosity–Structure Correlation for High Alumina-Silicate Melts

Blast furnaces are encountering high Alumina (Al₂O₃ > 25 pct) in the final slag due to the charging of low-grade ores. To study the viscosity behavior of such high alumina slags, synthetic slags are prepared in the laboratory scale by maintaining a chemical composition of Al₂O₃ (25 to 30 wt pct) CaO/SiO₂ ratio (0.8 to 1.6) and MgO (8 to 16 wt pct). A chemical thermodynamic software FactSage 7.0 is used to predict liquidus temperature and viscosity of the above slags. Experimental viscosity measurements are performed above the liquidus temperature in the range of 1748 K to 1848 K (1475 °C to 1575 °C). The viscosity values obtained from FactSage closely fit with the experimental values. The viscosity and the slag structure properties are intent by Fourier Transform Infrared (FTIR) and Raman spectroscopy. It is observed that increase in CaO/SiO₂ ratio and MgO content in the slag depolymerizes the silicate structure. This leads to decrease in viscosity and activation energy (167 to 149 kJ/mol) of the slag. Also, an addition of Al₂O₃ content increases the viscosity of slag by polymerization of alumino-silicate structure and activation energy from 154 to 161 kJ/mol. It is witnessed that the activation energy values obtained from experiment closely fit with the Shankar model based on Arrhenius equation.     

Anti‐thrombotic therapy for atrial fibrillation in patients with chronic kidney disease: Current views

Chronic kidney disease (CKD) occurs in approximately one‐third of patients with non‐valvular atrial fibrillation (AF). The presence of CKD, particularly advanced CKD, confers increased risk of both thromboembolism and major bleeding in this group of patients who are already at risk for ischemic stroke and systemic embolism and at risk of bleeding due to anticoagulation. Studies assessing the effect of warfarin on risk of ischemic stroke, systemic embolism, and major bleeding have produced disparate results, particularly in patients with advanced CKD including those treated with hemodialysis. The direct oral anticoagulants (DOAC's) have been studied in patients with stage III (moderate) CKD and appear to be as effective or more effective (dabigatran 150 mg twice daily) than warfarin in preventing ischemic stroke or embolism in this group. Two of the DOAC's, apixaban and edoxaban, confer lower risk of major bleeding than warfarin with appropriate dose adjustments. Substantial gaps exist in our knowledge of anti‐thrombotic therapy in patients with AF and CKD, primarily due to exclusion of patients with advanced CKD from randomized controlled trials comparing DOAC's with warfarin.     

Influence of Asymmetric Cyclic Loading on Structural Evolution and Deformation Behavior of Cu-5 at.% Zr Alloy: An Atomistic Simulation-Based Study

Molecular dynamics (MD) simulation-based studies of tensile test and structural evolution of Cu-5 at.% Zr alloy under asymmetric cyclic loading (i.e., ratcheting behavior) considering various stress ratios such as ? 0.2, ? 0.4 and ? 0.6 for different temperatures, viz.≈ 100, 300 and 500 K have been performed using embedded atom model Finnis–Sinclair potential. According to obtained stress–strain response from MD calculation, Cu-5 at.% Zr alloy specimen is pristine in nature as sudden drop in stress just after yield stress and subsequent elastic type deformation are observed for this alloy. Predicted ratcheting strain by MD simulation for Cu-5 at.% Zr alloy varies from 4.5 to 5%. Significant increase in ratcheting strain has been observed with the increase in temperature. Slight reduction in crystallinity is identified at the middle of the each loading cycle from the performed radial distribution function analysis and cluster analysis.     

Dislocation and Structural Studies at Metal–Metallic Glass Interface at Low Temperature

In this paper, molecular dynamics (MD) simulation deformation studies on the Al (metal)–Cu₅₀Zr₅₀ (metallic glass) model interface is carried out based on cohesive zone model. The interface is subjected to mode-I loading at a strain rate of 10⁹ s^?1 and temperature of 100 K. The dislocations reactions and evolution of dislocation densities during the deformation have been investigated. Atomic interactions between Al, Cu and Zr atoms are modeled using EAM (embedded atom method) potential, and a timestep of 0.002 ps is used for performing the MD simulations. A circular crack and rectangular notch are introduced at the interface to investigate the effect on the deformation behavior and fracture. Further, scale size effect is also investigated. The structural changes and evolution of dislocation density are also examined. It is found that the dominant deformation mechanism is by Shockley partial dislocation nucleation. Amorphization is observed in the Al regions close to the interface and occurs at a lower strain in the presence of a crack. The total dislocation density is found to be maximum after the first yield in both the perfect and defect interface models and is highest in the case of perfect interface with a density of 6.31 × 10¹⁷ m^?2. In the perfect and circular crack defect interface models, it is observed that the fraction of Shockley partial dislocation density decreases, whereas that of strain rod dislocations increases with increase in strain.     

Memory failures in progressive idiopathic dementia.

14 patients with progressive idiopathic dementia (PID) were compared with 14 normal controls (average age 61.2 yrs) on psychometric and laboratory measures of cognitive processes. Patients had significantly lower scores than controls on the Wechsler Memory Scale and the WAIS Performance IQ, but not on WAIS Verbal or Full Scale IQ or Digit Span tests. Patients performed more poorly on learning and memory tasks than controls. Unlike the latter, patients' recall of categorized word lists was no better than their recall of unrelated words, and they did not consistently remember information that had been previously recalled. Patients also were unable to generate as many words that start with a given letter or that belong to a given category as controls did. Data show that while many intellectual functions are preserved, PID patients are unable to access structures in semantic memory and therefore fail to effectively encode episodic events so that they are memorable. Differences in cognitive dysfunction in PID and in depression are discussed. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)