ABSTRACT
The clinical challenge of bone defects in the craniomaxillofacial region, which can lead to significant physiological dysfunction and psychological distress, persists due to the complex and unique anatomy of craniomaxillofacial bones. These critical-sized defects require the use of bone grafts or substitutes for effective reconstruction. However, current biomaterials and methods have specific limitations in meeting the clinical demands for structural reinforcement, mechanical support, exceptional biological performance, and aesthetically pleasing reconstruction of the facial structure. These drawbacks have led to a growing need for novel materials and technologies. The growing development of 3D printing can offer significant advantages to address these issues, as demonstrated by the fabrication of patient-specific bioactive constructs with controlled structural design for complex bone defects in medical applications using this technology. Poly (ether ether ketone) (PEEK), among a number of materials used, is gaining recognition as a feasible substitute for a customized structure that closely resembles natural bone. It has proven to be an excellent, conformable, and 3D-printable material with the potential to replace traditional autografts and titanium implants. However, its biological inertness poses certain limitations. Therefore, this review summarizes the distinctive features of craniomaxillofacial bones and current methods for bone reconstruction, and then focuses on the increasingly applied 3D printed PEEK constructs in this field and an update on the advanced modifications for improved mechanical properties, biological performance, and antibacterial capacity. Exploring the potential of 3D printed PEEK is expected to lead to more cost-effective, biocompatible, and personalized treatment of craniomaxillofacial bone defects in clinical applications.
ABSTRACT
College students in China are among the main consumers of online shopping and the corrugated cartons used to ship items are piling up on campus. However, the generation characteristics of waste corrugated cartons (WCCs) in universities and the environmental consequences along their recycling pathway remain to be addressed. Taking Nanjing University (NJU) as an example, this study conducted a questionnaire survey on campus to analyze the generation characteristics of WCCs and evaluated the life cycle environmental impacts of their recycling process using the Life Cycle Assessment (LCA) method. The results showed that WCC generation on campus varied by educational level, sex, grade and major, with doctoral students and female students being more active in online shopping and thus generating more WCCs. It was further estimated that a total of 0.27 Mt of WCCs were generated by college students in China in 2020, of which recycling would result in 0.31 Mt of CO2 eq of GHG emissions. Pulping and papermaking processes are the main contributors to the life cycle environmental impacts of WCC recycling, together accounting for at least 77% of the total. This study suggests the need for joint efforts from universities, students, and recycling enterprises to reduce WCC generation in Chinese universities and to make its recycling chain more environmentally sustainable.
