5,261 research outputs found
Towards a sustainable business model for plastic shopping bag management in Sweden
From an environmental perspective, a separate collection and recycling system for post-consumer discards could contribute to improved environmental protection as well as economic benefits. This paper investigates the environmental potential of a business model proposed in Sweden in order to improve the utilization of plastic shopping bags. The business model aims to reduce the consumption of plastic shopping bags and to collect and recycle discarded bags more effectively. Results from a life cycle assessment show that the proposed system could significantly reduce the carbon, energy and water footprints of the current system, even for very pessimistic scenarios for bag purchase and recovery rates. However, wider implementation of the proposed business model depends on the accessibility of the deposit/collection system, acceptance of such a 'take-back' system by retail managers, greater environmental awareness among customers and regulatory mechanisms
Enhanced Raman and photoluminescence response in monolayer MoS due to laser healing of defects
Bound quasiparticles, negatively charged trions and neutral excitons, are
associated with the direct optical transitions at the K-points of the Brillouin
zone for monolayer MoS. The change in the carrier concentration,
surrounding dielectric constant and defect concentration can modulate the
photoluminescence and Raman spectra. Here we show that exposing the monolayer
MoS in air to a modest laser intensity for a brief period of time enhances
simultaneously the photoluminescence (PL) intensity associated with both trions
and excitons, together with 3 to 5 times increase of the Raman intensity
of first and second order modes. The simultaneous increase of PL from trions
and excitons cannot be understood based only on known-scenario of depletion of
electron concentration in MoS by adsorption of O and HO molecules.
This is explained by laser induced healing of defect states resulting in
reduction of non-radiative Auger processes. This laser healing is corroborated
by an observed increase of intensity of both the first order and second order
2LA(M) Raman modes by a factor of 3 to 5. The A mode hardens by
1.4 cm whereas the E mode softens by 1 cm.
The second order 2LA(M) Raman mode at 440 cm shows an increase in
wavenumber by 8 cm with laser exposure. These changes are a
combined effect of change in electron concentrations and oxygen-induced lattice
displacements.Comment: 15 pages, 5 figures, Journal of Raman Spectroscopy, 201
- …