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Polymer laser powder bed fusion (PBF-LB/P) is an additive manufacturing technology that is sustainable due to the possibility of recycling the powder multiple times and allowing the fabrication of gears without the aid of support structures and subsequent assembly. However, there are constraints in the process that negatively affect its adoption compared to other additive technologies such as material extrusion to produce gears. This study aims to demonstrate that it is possible to overcome the problems due to the physics of the process to produce accurate mechanism.

Technological aspects such as orientation, wheel-shaft thicknesses and degree of powder recycling were examined. Furthermore, the evolving tooth profile was considered as a design parameter to provide a manufacturability map of gear-based mechanisms.

Results show that there are some differences in the functioning of the gear depending on the type of powder used, 100% virgin or 50% virgin and 50% recycled for five cycles. The application of a groove on a gear produced with 100% virgin powder allows the mechanism to be easily unlocked regardless of the orientation and wheel-shaft thicknesses. The application of a specific evolutionary profile independent of the diameter of the reference circle on vertically oriented gears guarantees rotation continuity while preserving the functionality of the assembled mechanism.

In the literature, there are various studies on material aging and reuse in the PBF-LB/P process, mainly focused on the powder deterioration mechanism, powder fluidity, microstructure and mechanical properties of the parts and process parameters. This study, instead, was focused on the functioning of gears, which represent one of the applications in which this technology can have great success, by analyzing the two main effects that can compromise it: recycled powder and vertical orientation during construction.

Although various studies have shed light on why cities are a primary source of environmental pollution and how it affects climate change, the effects of city-level environmental deterioration on company ownership have yet to be investigated. In this context, our main objective is to investigate environmental pollution's impact on the ownership of informal enterprises in Indian metro cities (1 million or more population). This study considers micro (entrepreneurship-level) and macro (city-level) factors for the analysis by using mainly National Sample Survey unit-level data on ‘Unincorporated Non-Agricultural Enterprises’ in 2015–2016. Micro-level factors include access to toilet facilities, provision for solid waste management, provision for liquid waste management, etc. On the other hand, macro-level factors are the total number of registered motor vehicles (two-wheelers, cars, jeeps, tractors, omnibuses, trucks, taxis, buses, passenger autos and light motor vehicles) and air pollution (e.g. sulphur dioxide, nitrogen dioxide and particular matter emissions). The study explored the impact of environmental pollution on the differences in gender business ownership. According to the findings, both male- and female-owned proprietorships suffer from environmental degradation. Environmental contamination, however, puts female-owned businesses at greater risk than their male counterparts. Because of this, it is crucial to lessen environmental pollution by lowering air pollution and providing improved toilets, water and solid and liquid waste management systems. By reducing poverty and inequality, advancing a society that values equality between the sexes is necessary. Finally, we propose important policies to enable the city environment to improve entrepreneurship activities for sustainable economic development.