Modeling of surface phenomena of liquid Al-Ni alloys using molecular dynamics.

This work presents a study on the surface tension of liquid Aluminum-Nickel (Al-Ni) alloys. Obtaining adequate values of surface tension for this system is not a simple task as these alloys present the formation of atomic clusters with short-range order at certain compositions, which dramatically influences surface tension. The Compound Forming Model predicts the influence of these clusters on surface tension, but experimental limitations have obstructed its validation due to deficient thermodynamic data. This work attempts to overcome some of these limitations by using Molecular Dynamics (MD). By comparing the obtained results from MD simulations with those of an equivalent system without clusters, it was possible to infer the role of the atomic clusters on Al-Ni surface tension. It was found that these clusters increase surface tension by decreasing the Al content at the surface. They achieve this reduction in Al content at the surface by trapping Al atoms and hindering their travel to the surface.

In-situ electrical conductivity monitoring of slag solidification during continuous cooling for slag recycling.

Large volumes of steel slag are produced annually, leading to significant environmental protection and sustainable development issues. An online technology to monitor the solidification process of steel slag can assist in obtaining the right mineralogy to valorize these slags or render them harmless. For this purpose, we investigated the electrical properties and microstructural relationships of a CaO-Al2O3-SiO2-MgO (CASM) slag during cooling using an innovative setup. The electrical impedance was determined over the frequency range of 20 Hz to 300 kHz at two cooling rates, and the solidification behaviour was observed simultaneously by confocal scanning laser microscopy (CSLM). Four zones can be distinguished in the conductivity-temperature curves for the slag cooled at 10 °C/min, whereas only two distinct zones are visible at 100 °C/min. The liquid fraction of the slag has a significant impact on the slag conductivity during cooling. The electrical conductivity is, therefore, an accurate indicator of the solidification degree. Different theoretical and empirical models were evaluated on their ability to relate the bulk conductivity of the slag to the liquid fraction. The empirical Archie's model proved to be the most suitable model for relating the bulk conductivity of the slag to the liquid fraction. In-situ electrical conductivity measurements during cooling can provide an online assessment of the slag solidification process, including indicating the appearance of solid precipitates, monitoring the growth of crystals, indicating complete solidification when no liquid phase remains, and indicating the cooling rate.

An Innovated Application of Reutilize Copper Smelter Slag for Cement-based Electromagnetic Interference Composites.

In the present study, it has been attempted an innovated application, i.e., electromagnetic interference shielding material, to reutilize copper smelter slag, aiming at an alternative high value added product. Notably, a proof-of-concept experiment with an addition of a 45 wt.% of copper slag alone to the cement matrix boost the shielding effectiveness (SE) to approximately 7-8 dB in the 500 MHz-1.5 GHz frequency range, highlights the incident electromagnetic wave has been weakened by approximately 60 pct. This phenomenon is attributed to the iron silicate, fayalite, and magnetite embedded in the sample mixture serve as magnetic and dielectric loss absorbent, deriving from the copper slag. Copper slag with low value application, shows its competitive economic and social advantages as candidate infill for electromagnetic interference shielding materials.

Quantitative Study on Dissolution Behavior of Nd2O3 in Fluoride Melts.

The dissolution of rare earth oxides in molten fluorides is a critical step in the preparation of the corresponding rare earth metals by oxide-fluoride electrolysis. However, quantitatively understanding the nature of dissolution, especially in the case of molten salts, is usually difficult to be achieved by postmortem characterization. In this paper, the dissolution behavior of Nd2O3 particles in molten fluorides was studied via in situ observation with confocal scanning laser microscopy. Combining direct observation with thermodynamic analyses on the oxide dissolution, the rate-limiting step(s) and the effects of parameters like temperature, salt type, and composition on the dissolution rate are identified. This study provides a methodology to estimate the dissolution kinetics of rare earth oxides in molten fluorides during their primary and secondary processing.

Utilization of Stainless-steel Furnace Dust as an Admixture for Synthesis of Cement-based Electromagnetic Interference Shielding Composites.

Electromagnetic interference (EMI) shielding receives attention due to the increasing abundance of electronics. The Cement based material can obtain EMI shielding properties through the use of appropriate "fillers" such as carbon, metal, and ferrite. As the most important by-product of stainless steelmaking operations, through the metal droplets and ferrite that it contains, stainless-steel dust can be considered as a potential filler for EMI shielding applications. We have therefore utilized stainless-steel dust as an admixture for the synthesis of cement-based EMI shielding composites and show that it raises the EMI shielding effectiveness. In particular, a 45 mass pct of stainless-steel dust mixture of 5 mm thickness results in the enhancement of EMI shielding effectiveness to 6-9 dB as tested in the frequency range of 500 MHz-1.5 GHz.

Atazanavir and Cardiovascular Risk Among Human Immunodeficiency Virus-Infected Patients: A Systematic Review.

INTRODUCTION: Patients with human immunodeficiency virus (HIV) infection have an increased risk of cardiovascular disease (CVD). While viral suppression with antiretroviral therapy decreases CVD risk overall, several studies have suggested that certain antiretrovirals, particularly certain protease inhibitors, may be associated with an increased relative risk of CVD. In AIDS Clinical Trials Group 5260 s, ritonavir-boosted atazanavir (ATV) was associated with slower atherosclerosis progression compared to ritonavir-boosted darunavir and raltegravir, potentially due to hyperbilirubinemia. Although hyperbilirubinemia may lead to increased rates of treatment discontinuation, it may also contribute to a favorable cardiovascular (CV) profile for ATV. To fully elucidate the effect of ATV on CVD risk among HIV-infected patients, a systematic review of the literature was performed. METHODS: A systematic search of the PubMed and Embase databases was conducted on August 26, 2015, using terms to identify papers that discuss ATV, HIV, and CVD. Articles were limited to English-language publications of randomized-controlled or observational studies investigating adult humans. The primary outcome was the incidence of CVD. Articles describing surrogate markers of CVD were also included. RESULTS: Ten studies were included in this qualitative analysis: six reported CVD outcomes, two reported data on atherosclerosis as assessed by carotid intima-media thickness (cIMT), and two reported outcomes related to endothelial function. The studies reporting the incidence of myocardial infarction (MI) among HIV-infected patients showed that ATV (boosted and unboosted) was not associated with an increased risk of acute MI. Other CV endpoints were similarly unaffected by treatment with ATV. Compared with non-ATV-based regimens, ATV had beneficial effects on cIMT progression in the publications identified, with no apparent impact on endothelial function. CONCLUSIONS: This analysis showed that there was no increased risk or occurrence of adverse CV events among HIV-infected patients receiving ATV. Markers of atherosclerosis were improved, suggesting a possible antioxidant effect of ATV, and endothelial function was not affected. FUNDING: Bristol-Myers Squibb (article processing charges and medical writing support).

Crystal structure of apatite type Ca2.49Nd7.51(SiO4)6O1.75.

The title compound, Ca2+x Nd8-x (SiO4)6O2-0.5x (x = 0.49), was synthesized at 1873 K and rapidly quenched to room temperature. Its structure has been determined using single-crystal X-ray diffraction and compared with results reported using neutron and X-ray powder diffraction from samples prepared by slow cooling. The single-crystal structure from room temperature data was found to belong to the space group P63/m and has the composition Ca2.49Nd7.51(SiO4)6O1.75 [dicalcium octa-neodymium hexa-kis-(ortho-silicate) dioxide], being isotypic with natural apatite and the previously reported Ca2Nd8(SiO4)6O2 and Ca2.2Nd7.8(SiO4)6O1.9. The solubility limit of calcium in the equilibrium state at 1873 K was found to occur at a composition of Ca2+x Nd8-x (SiO4)6O2-0.5x , where x = 0.49.

Gas-solid reaction kinetics of ZnFe2O4 formation from 907 to 1100 °C.

The reaction kinetics of Zn vapor with Fe3O4 (magnetite) were studied from 907 to 1100 °C using a new experimental setup that only allows contact between the reactants through a gas-solid reaction. Hematite was used to create the reaction pellets. Because of the reducing atmosphere in the setup, a magnetite layer is formed on the outside of the pellet, which in turn reacts with the Zn vapor. After reaction, Zn concentration profiles were measured in the reacted magnetite layer using field-emission gun electron probe microanalysis. The reaction was confirmed to be diffusion-controlled. The effect of both volume and grain-boundary diffusion was observed in each experiment. The temperature dependence of both the volume and grain-boundary diffusion coefficients was obtained along with the activation energies of the diffusion coefficients. This study provides crucial information for the development of technologies that are dependent on the reaction. One example is the in-process separation technology for the separation of Zn vapor from electric arc furnace off-gas.