Spangolite: an s=1/2 maple leaf lattice antiferromagnet?

Spangolite, Cu6Al(SO4)(OH)12Cl.3H2O, is a hydrated layered copper sulphate mineral. The Cu2+ ions of each layer form a systematically depleted triangular lattice which approximates a maple leaf lattice. We present details of the crystal structure, which suggest that in spangolite this lattice actually comprises two species of edge linked trimers with different exchange parameters. However, magnetic susceptibility measurements show that despite the structural trimers, the magnetic properties are dominated by dimerization. The high temperature magnetic moment is strongly reduced below that expected for the six s=1/2 in the unit cell.Comment: Accepted for JPCM Frustrated Magnetism special issue, added reference [5] in replacemen

Probing photoinduced spin states in spin-crossover molecules with neutron scattering

We report a neutron scattering investigation of the spin crossover compound \rm [Fe(ptz)6](BF4)2 which undergoes an abrupt thermal spin-transition from high-spin (HS) S=2 to low-spin (LS) S=0 around 135 K. The HS magnetic state can be restored at low temperature under blue/green light irradiation. We have developed a specially designed optical setup for neutron scattering to address the magnetic properties of the light-induced HS state. By using neutron diffraction, we demonstrate that significant HS/LS ratios (of up to 60 \%) can be obtained with this experimental setup on a sample volume considered large (400 mg), while a complete recovery of the LS state is achieved using near infrared light. With inelastic neutron scattering (INS) we have observed, for the first time in a photo-induced phase, magnetic transitions arising from the metastable HS S=2 state split by crystal field and spin-orbit coupling. We interpret the INS data assuming a spin-only model with a zero-field splitting (ZFS) of the S=2 ground state. The obtained parameters are D \approx -1.28 \pm 0.03 meV and |E| \approx 0.08 \pm 0.03 meV. The present results show that in situ magnetic inelastic neutron scattering investigations on a broad range of photomagnetic materials are now possible

Modelling and analysis of direct air capture systems in different locations

Direct air capture is an important negative emission technology with the aim to reduce carbon dioxide emissions in the atmosphere and to face the current environmental problems such as global warming and climate change. This emerging technology can be based on an adsorption system affected by the used sorbent (physisorbents or chemisorbents). Efficiencies can be measured through the use of key performance indicators that allow a comparison among different processes. An independent analysis was conducted in our previous research to evaluate key performance indicators (total cost, energy consumption, environmental impact and capture capacity) for a direct air capture system based on adsorption using different sorbents (three metal organic frameworks and two amine functionalized sorbents). In this research, the same analysis was extended to several Countries around the world, changing the ambient air temperature according to the yearly average value of the location. Results show that by increasing the air temperature, the adsorption capacity decreases, in a more significant way for metal organic frameworks compared to amine functionalized sorbents. An opposite effect is for energy consumption. Moreover, by increasing the ambient air temperature, a higher environmental impact (in terms of climate change) is present. A trend with the air temperature was not found for total costs. Overall, locations with lower ambient air temperatures are preferred due to a lower environmental impact and energy consumption

The acute physiological and perceptual effects of recovery interval intensity during cycling‐based high‐intensity interval training

Purpose: The current study sought to investigate the role of recovery intensity on the physiological and perceptual responses during cycling-based aerobic high-intensity interval training. Methods: Fourteen well-trained cyclists (V˙O2peak: 62 ± 9 mL kg−1 min−1) completed seven laboratory visits. At visit 1, the participants’ peak oxygen consumption (V˙O2peak) and lactate thresholds were determined. At visits 2–7, participants completed either a 6 × 4 min or 3 × 8 min high-intensity interval training (HIIT) protocol with one of three recovery intensity prescriptions: passive (PA) recovery, active recovery at 80% of lactate threshold (80A) or active recovery at 110% of lactate threshold (110A).Results: The time spent at > 80%, > 90% and > 95% of maximal minute power during the work intervals was significantly increased with PA recovery, when compared to both 80A and 110A, during both HIIT protocols (all P ≤ 0.001). However, recovery intensity had no effect on the time spent at > 90% V˙O2peak (P = 0.11) or > 95% V˙O2peak (P = 0.50) during the work intervals of both HIIT protocols. Session RPE was significantly higher following the 110A recovery, when compared to the PA and 80A recovery during both HIIT protocols (P < 0.001).Conclusion: Passive recovery facilitates a higher work interval PO and similar internal stress for a lower sRPE when compared to active recovery and therefore may be the efficacious recovery intensity prescription