RESUMEN
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.
Asunto(s)
Reciclaje , Administración de Residuos , China , Comercio , Ambiente , Femenino , Humanos , Internet , Masculino , Estudiantes , Universidades , Administración de Residuos/métodosRESUMEN
Chiral molecules that do not superimpose on their mirror images are the foundation of all life forms on earth. Chiral molecules exhibit chiroptical responses, i.e., they have different electromagnetic responses to light of different circular polarizations. However, chiroptical responses in natural materials, such as circular dichroism and optical rotation dispersion, are intrinsically small because the size of a chiral molecule is significantly shorter than the wavelength of electromagnetic wave. Conventional technology for enhancing chiroptical signal entails demanding requirements on precise alignment of the chiral molecules to certain nanostructures, which however only leads to a limited performance. Herein, we show a new approach towards enhancement of chiroptical effects through a Fabry-Pérot (FP) cavity formed by two handedness-preserving metamirrors operating in the GHz region. We experimentally show that the FP cavity resonator can enhance the optical activity of the chiral molecule by an order of magnitude. Our approach may pave the way towards state-of-the-art chiral sensing applications.