20 research outputs found
Electrocaloric polymers: different electric field cycles to increase their efficiency
International audienc
Impacts of River Water Consumption on Aquatic Biodiversity in Life Cycle AssessmentA Proposed Method, and a Case Study for Europe
In
the context of climate change and food provisioning for a growing
global population, the impacts of water consumption on aquatic biodiversity
(e.g., river water consumption for irrigation) should be considered
in Life Cycle Impact Assessment (LCIA). A previous LCIA method quantifying
the potential impacts of river water consumption on fish biodiversity,
using a species-discharge relationship (SDR), constituted an essential
first step. This method is however limited in terms of regionalization
and taxa considered, and predicts the potential risk of local species
loss only. Here, we address these shortcomings by developing region-specific
SDRs for Europe at various scales (continent, country, and eco-region),
and including macro-invertebrate biodiversity. SDR exponents vary
from 0.06 to 0.45 between regions, underlining the importance of such
regionalization. Furthermore, we provide a new regionalized method
which considers the location of water consumption within a river basin,
by integrating the concept of longitudinal river zonation. This involves
the use of a novel measure of potential loss of species richness,
standardizing local species loss to an equivalent of global extinction
and reflecting species vulnerability. The new method is applied in
a Swiss case-study. The consideration of the location of water consumption
within a basin was found to be of high importance in the assessment:
potential species loss varied between 4.22 × 10<sup>–3</sup> and 3.95 × 10<sup>–1</sup> species (2 orders of magnitude)
depending on location. This work thus provides enhancements in the
assessment of potential impacts of river water consumption on aquatic
biodiversity and contributes to the ecological relevance of the method
Impact of Molecular Flexibility on Double Polymorphism, Solid Solutions and Chiral Discrimination during Crystallization of Diprophylline Enantiomers
The polymorphic behavior of racemic
and enantiopure diprophylline
(DPL), a chiral derivative of theophylline marketed as a racemic solid,
has been investigated by combining differential scanning calorimetry,
powder X-ray diffraction, hot-stage microscopy and single-crystal
X-ray experiments. The pure enantiomers were obtained by a chemical
synthesis route, and additionally an enantioselective crystallization
procedure was developed. The binary phase diagram between the DPL
enantiomers was constructed and revealed a double polymorphism (i.e.,
polymorphism both of the racemic mixture and of the pure enantiomer).
The study of the various equilibria in this highly unusual phase diagram
revealed a complex situation since mixtures of DPL enantiomers can
crystallize either as a stable racemic compound, a metastable conglomerate,
or two distinct metastable solid solutions. Crystal structure analysis
revealed that the DPL molecules adopt different conformations in the
crystal forms suggesting that the conformational degrees of freedom
of the substituent that carries the only two H-bond donor groups might
be related to the versatile crystallization behavior of DPL. The control
of these equilibria and the use of a suitable solvent allowed the
design of an efficient protocol for the preparative resolution of
racemic DPL via preferential crystallization. Therefore, the resolution
of DPL enantiomers despite the existence of a racemic compound stable
at any temperature demonstrates that the detection of a stable conglomerate
is not mandatory for the implementation of preferential crystallization