Coatings Functionalization via Laser versus Other Deposition Techniques for Medical Applications: A Comparative Review

The development of new biological devices in response to market demands requires continuous efforts for the improvement of products’ functionalization based upon expansion of the materials used and their fabrication techniques. One viable solution consists of a functionalization substrate covered by layers via an appropriate deposition technique. Laser techniques ensure an enhanced coating’s adherence to the substrate and improved biological characteristics, not compromising the mechanical properties of the functionalized medical device. This is a review of the main laser techniques involved. We mainly refer to pulse laser deposition, matrix-assisted, and laser simple and double writing versus some other well-known deposition methods as magnetron sputtering, 3D bioprinting, inkjet printing, extrusion, solenoid, fuse-deposition modeling, plasma spray (PS), and dip coating. All these techniques can be extended to functionalize surface fabrication to change local morphology, chemistry, and crystal structure, which affect the biomaterial behavior following the chosen application. Surface functionalization laser techniques are strictly controlled within a confined area to deliver a large amount of energy concisely. The laser deposit performances are presented compared to reported data obtained by other techniques.

Comparative Review of Aerobic and Anaerobic Composting for the Reduction of Organic Waste

Composting is a self-heating, aerobic, bio-decomposition process of organic waste that has advantages over other disposal strategies since it reduces waste volume by 40-50% and kills pathogens by the heat generated during the thermophilic phase. This process uses organic waste (food scraps, grass chipping, etc.), water, soil (for added microbes) and either incorporation of air by turning the compost (aerobic) or lack of air within the compost (anaerobic). This study is designed to comparatively assess aerobic and anaerobic composting mechanisms on the productivity rate and analyse the different variables influencing the process. Based on the results obtained the time taken to completely compost the organic materials might not always be the same, because composting time is dependent on the percentage of microorganisms, water content, temperature and C:N ratio present in the pile at the said time along with the amount of material to be composted. Finally, this study will not only help farmers but also the general public in choosing a cost-effective and environmentally friendly way of reducing organic waste from landfills and reduction of greenhouse gases in the ozone layer.

A Survey on LoRaWAN Technology: Recent Trends, Opportunities, Simulation Tools and Future Directions

Low-power wide-area network (LPWAN) technologies play a pivotal role in IoT applications, owing to their capability to meet the key IoT requirements (e.g., long range, low cost, small data volumes, massive device number, and low energy consumption). Between all obtainable LPWAN technologies, long-range wide-area network (LoRaWAN) technology has attracted much interest from both industry and academia due to networking autonomous architecture and an open standard specification. This paper presents a comparative review of five selected driving LPWAN technologies, including NB-IoT, SigFox, Telensa, Ingenu (RPMA), and LoRa/LoRaWAN. The comparison shows that LoRa/LoRaWAN and SigFox surpass other technologies in terms of device lifetime, network capacity, adaptive data rate, and cost. In contrast, NB-IoT technology excels in latency and quality of service. Furthermore, we present a technical overview of LoRa/LoRaWAN technology by considering its main features, opportunities, and open issues. We also compare the most important simulation tools for investigating and analyzing LoRa/LoRaWAN network performance that has been developed recently. Then, we introduce a comparative evaluation of LoRa simulators to highlight their features. Furthermore, we classify the recent efforts to improve LoRa/LoRaWAN performance in terms of energy consumption, pure data extraction rate, network scalability, network coverage, quality of service, and security. Finally, although we focus more on LoRa/LoRaWAN issues and solutions, we introduce guidance and directions for future research on LPWAN technologies.