Remote Patient Monitoring (RPM) is a method of healthcare that allows monitoring and patient care to be done in locations outside of the clinical setting. RPM has many benefits: intrinsic convenience of service, reduction of medical costs, and improved quality of care. However, along with the use of RPM, there is an increase in concern about the secure transmission of data and its storage. There have been advancements in the secure transmission of data but the storage still needs to be improved since many current medical systems still use a centralized architecture for storage. A solution for this problem might be found in Distributed Ledger Technology, specifically blockchain. However, implementing blockchain in the context of IoMT or RPM is difficult and comes with complications. Recently, there has been a new approach for the DLT framework called the agent-centric approach, a more generalized version of the data-centric approach blockchain uses. In this study, we will use the agent-centric approach to create an RPM system to see if it's a better storage solution than its blockchain counterparts.

With the increasing demand for scandium in the green technology sector and the prevailing scarcity of its reliable sources, the valorization of secondary and unconventional resources is currently being explored. Ongoing studies in ironmaking in the Philippines have shown substantial scandium concentrations in lateritic slags produced through a simulated blast furnace process. In this study, the recovery of scandium from basic lateritic blast furnace slag through leaching was explored using varied combination settings of diluted HCl concentrations, leaching temperatures, and %solids, optimized using Response Surface Methodology following a Box Behnken Design. Results of the statistical analysis indicate an optimum leaching parameter combination of 2.90 M HCl, 80.00 °C, and 4.00% solids, achieving a theoretical recovery of 64.76% Sc, with impurities of 65.27% Fe, 54.73% Ti, 56.22% Al, and 18.04% Si. Sc leaching was primarily affected by the %solids, followed by the quadratic effect of HCl concentration, and the main effect of leaching temperature, while the main and quadratic effects of %solids and HCl concentration generally influenced the dissolution of the other impurities. By obtaining the solution Eh-pH, the stable species present in the leaching system were identified, further confirming the metal dissolution mechanisms in acidic conditions. The kinetics of the diluted HCl leaching of Sc was found to conform to the Avrami-Erofeev model, wherein the leaching rate of Sc starts rapidly and gradually slows down over time. The rate-determining step of the mechanism is a mixed-face chemical reaction and diffusion-controlled, with an apparent activation energy of 15.26 kJ/mol and a model equation of X_(Sc^(3+)) = 1 - exp [154.97 exp (-15259.60/(8.314 T)) t^(-0.129)]. Furthermore, the leaching residue was characterized by granular aggregates, voids, and cracks, along with some faceted crystals surrounding an unreacted zone, suggesting the disappearance and/or transformation of aluminosilicates and iron-rich minerals initially present in the slag. Results show that diluted HCl leaching of lateritic slag is an effective method for extracting scandium, with relatively minimized silicon impurities.

Titanium dioxide (TiO2) has been extensively researched for diverse applications, especially in photocatalysis, owing to its stability, non-toxicity, and strong photocatalytic capabilities. Thin films of TiO2, produced by sputter deposition, are mechanically robust and effective for wastewater treatment. However, their dense nature limits surface accessibility, which is crucial for efficient photocatalysis. Oblique angle deposition (OAD) provides a simple method for creating highly porous nanostructured columnar films, enhancing surface area accessibility. TiO2 exhibits activity in the ultraviolet range due to its large band gap. Incorporating noble metals, such as silver (Ag), has shown promise in enhancing TiO2 activity, shifting it towards visible light.

In this study, Ag-decorated TiO2 nanocolumnar films (Ag-TiO2 NCFs) were synthesized using a custom-built magnetron sputter deposition setup, using OAD with substrates positioned at different angles (0°, 35°, 70°) relative to the target. Sputtering was carried out with a gas ratio of 90:10 Argon (Ar): oxygen (O2) at 2 Pa and 110 W DC power, followed by annealing at 450°C for 2 hours to achieve the desired crystallinity. The films were then coupled with metallic Ag nanoparticles through wet impregnation in silver nitrate (AgNO3) solution and subsequent plasma reduction utilizing a modified version of the same plasma system.

Examining the substrate angles through scanning electron microscopy revealed a greater degree of porosity in the structure as the substrate angles increased. Analysis of confocal laser scanning microscopy images indicated an elevation in surface roughness with substrate tilting. This increase in porosity and surface roughness positively influenced the photocatalytic activity of TiO2 NCFs by creating additional sites for chemical interactions. Energy-dispersive spectroscopy and X-ray diffraction (XRD) analysis confirmed the anatase phase of TiO2 post-annealing. Plasma treatment revealed a shift from Ag oxide peaks to metallic Ag peaks in the XRD pattern. Raman spectroscopy indicated an increase in the intensity of the characteristic peaks TiO2 after the incorporation of Ag due to the SPR effect. Reflectance spectra estimated the optical bandgap (Eg) of TiO2 and Ag-TiO2 NCFs, with Eg decreasing from 3.2-3.4 eV for TiO2 NCFs to 2.9-3.2 eV for Ag-TiO2 NCFs, suggesting sensitivity to longer wavelengths in the visible region. Photocatalytic performance was assessed by degrading methylene blue (MB) under white light using these catalysts. The results demonstrated a degradation efficiency that exceeded 70% for 5 hours when Ag was coupled with TiO2 due to the surface plasmon resonance effect. Substrates tilted to 70° exhibited a higher MB degradation efficiency up to 90%, attributed to the high porosity and the large surface area of the films.

The rapid depletion of easily extracted gold ores raised difficulties in using conventional cyanidation for gold extraction. Refractory gold containing gold particles locked in sulfides require pretreatment before gold leaching to achieve favorable gold recoveries. Hypochlorite (OCl-1) solution has been explored in processing refractory gold because it can oxidize the sulfides as pretreatment and dissolve gold with less impact on safety, health, and environment than cyanidation. In this study, hypochlorite solution is used for two-stage leaching of a refractory gold- molybdenum concentrate involving sulfide oxidation in the first stage and gold dissolution in the second stage. Effect of sulfide oxidation time, liquid-to-solid ratio (L:S), hypochlorite and sodium hydroxide concentrations on gold dissolution was examined. Optimization of these factors was done and reaction mechanism was inferred using the solution Eh and pH. It was observed that there is a significant increase in gold dissolution with increasing reaction time, liquid-to-solid (L:S) ratio, and OCl-1 concentration, and with decreasing sodium hydroxide (NaOH) concentration in the sulfide oxidation stage. Gold dissolution of 93.51% was achieved at oxidation of 6 hours, L:S of 13, and 1.89 M OCl-1. Molybdenum dissolution of 88.54% was also attained in this condition. In hypochlorite leaching, sulfides are oxidized by hypochlorite ions in alkaline condition in the first stage while gold is dissolved by hypochlorous acid at pH 6 in the second stage. Based on the shrinking-core model, rate-determining step for sulfide oxidation is diffusion control with an amorphous oxide forming as the product layer. Results show that the use of hypochlorite solution can be a potential eco-friendly and more simplified alternative for gold extraction of refractory gold-molybdenum concentrates. The promising gold and molybdenum dissolutions indicate that hypochlorite solution can be used to dissolve gold and molybdenum from the concentrate.

The increasing complexity of copper ores poses a challenge in processing and production of copper which is further exacerbated by the presence of arsenic. Hydrometallurgical techniques in selectively removing arsenic have shown to be effective and more environmentally benign compared to conventional processes. In this study, alkaline leaching was employed to remove arsenic from copper ores. The ore being studied contained 4% enargite (Cu3AsS4) and 1% scorodite (FeAsO4.2H2O) as the main arsenic minerals and 80% quartz (SiO2) as the main gangue. Additionally, other copper sulfide minerals were in trace amounts which further confirmed the need for removal of arsenic to obtain the valuable copper. Three solvents including Na2S, NaHS and NaClO under alkaline conditions were investigated and showed potential in selective removal of As. Both Na2S and NaHS systems provide a reducing condition to allow S2- from the solvent to be stable and react with enargite to produce thioarsenate (AsS43-) in solution. NaClO leaching provides an oxidizing condition for ClO- to react with enargite and produce arsenate (AsO43-). It was also observed that scorodite was dissolved at alkaline conditions without the addition of a solvent. In Na2S leaching, As dissolution increased with increased temperature and reduced particle size but decreased with increased solvent concentration. For NaHS, As dissolution was favored by high solvent concentration and temperature and reduced particle size. For NaClO, dissolution increased with increased solvent concentration and reduced particle size but decreased with increased temperature due to accelerated decomposition of ClO-. Na2S and NaHS solvents were significantly affected by the particle size of the ore while NaClO was strongly affected by solvent concentration. Leaching using Na2S resulted in the highest As dissolution at 96%, followed by 88% and 85% As using NaHS and NaClO, respectively. Minimal copper dissolution was noted for Na2S and NaHS indicating selectivity. Initial leaching rate was fast as more soluble forms of arsenic were dissolved. But as leaching progressed, the rate significantly decreased due to the consumption of more refractory forms of arsenic. The results showed that the leaching kinetics conformed to the Avrami model. The activation energy for Na2S-NaOH and NaHS-NaOH leaching were calculated to be 21.2 kJ/mol and 18.1 kJ/mol, respectively, indicating that the As leaching using these media were controlled by a mix of diffusion and chemical reaction.