RESUMO
Background and Aims: Multiple sources of medical oxygen, namely liquid medical oxygen (LMO) tanks, pressure swing adsorption (PSA) plants, concentrators, and gaseous cylinders, are available at different healthcare facilities. These sources of oxygen have varying installation and operational costs. In low-resource settings, it is imperative to utilise these assets optimally. This study investigated the operational costs of multiple oxygen sources available at a healthcare facility. Methods: A Microsoft (MS) Excel-based model was developed to analyse and compare the oxygen manufacturing costs (in â¹/m3) using PSA plants and procurement costs (in â¹/m3) of LMO and third-party vendor-refilled cylinders. Results: The oxygen manufacturing costs for PSA plants of different capacities and running times on electricity and diesel generators (DGs) as a power source were calculated. This study highlights the cost-benefit of using PSA plants over LMO and third-party vendor-refilled cylinders as a source of oxygen. PSA plants are most economical when they are of higher capacity and used to their maximum capacity on electricity as the power source. On the contrary, they are most expensive when used on a DG set as a power source. Furthermore, this study provides evidence of PSA plants being more cost-effective for refilling cylinders using a booster compressor unit when compared to third-party vendor-cylinder refilling. Conclusion: Given their cost-effectiveness and low third-party dependence, they should be utilised to their maximum capacity as medical oxygen sources at healthcare facilities.
RESUMO
Bioengineering of tissues and organs has the potential to generate functional replacement organs. However, achieving the full-thickness vascularization that is required for long-term survival of living implants has remained a grand challenge, especially for clinically sized implants. During the pre-vascular phase, implanted engineered tissues are forced to metabolically rely on the diffusion of nutrients from adjacent host-tissue, which for larger living implants results in anoxia, cell death, and ultimately implant failure. Here it is reported that this challenge can be addressed by engineering self-oxygenating tissues, which is achieved via the incorporation of hydrophobic oxygen-generating micromaterials into engineered tissues. Self-oxygenation of tissues transforms anoxic stresses into hypoxic stimulation in a homogenous and tissue size-independent manner. The in situ elevation of oxygen tension enables the sustained production of high quantities of angiogenic factors by implanted cells, which are offered a metabolically protected pro-angiogenic microenvironment. Numerical simulations predict that self-oxygenation of living tissues will effectively orchestrate rapid full-thickness vascularization of implanted tissues, which is empirically confirmed via in vivo experimentation. Self-oxygenation of tissues thus represents a novel, effective, and widely applicable strategy to enable the vascularization living implants, which is expected to advance organ transplantation and regenerative medicine applications.
RESUMO
A variety of natural or synthetic calcium phosphate (CaP)-based scaffolds are currently produced for dental and orthopaedic applications. These scaffolds have been shown to stimulate bone formation due to their biocompatibility, osteoconductivity and osteoinductivity. The release of the [Formula: see text] ions from these scaffolds is of great interest in light of the aforementioned properties. It can depend on a number of biophysicochemical phenomena such as dissolution, diffusion and degradation, which in turn depend on specific scaffold characteristics such as composition and morphology. Achieving an optimal release profile can be challenging when relying on traditional experimental work alone. Mathematical modelling can complement experimentation. In this study, the in vitro dissolution behaviour of four CaP-based scaffold types was investigated experimentally. Subsequently, a mechanistic finite element method model based on biophysicochemical phenomena and specific scaffold characteristics was developed to predict the experimentally observed behaviour. Before the model could be used for local [Formula: see text] ions release predictions, certain parameters such as dissolution constant ([Formula: see text]) and degradation constant ([Formula: see text]) for each type of scaffold were determined by calibrating the model to the in vitro dissolution data. The resulting model showed to yield release characteristics in satisfactory agreement with those observed experimentally. This suggests that the mathematical model can be used to investigate the local [Formula: see text] ions release from CaP-based scaffolds.
