2,779 research outputs found
Computing climate-smart urban land use with the Integrated Urban Complexity model (IUCm 1.0)
Gapless spin-liquid state in the structurally disorder-free triangular antiferromagnet NaYbO
We present the structural characterization and low-temperature magnetism of
the triangular-lattice delafossite NaYbO. Synchrotron x-ray diffraction and
neutron scattering exclude both structural disorder and crystal-electric-field
randomness, whereas heat-capacity measurements and muon spectroscopy reveal the
absence of magnetic order and persistent spin dynamics down to at least 70\,mK.
Continuous magnetic excitations with the low-energy spectral weight
accumulating at the -point of the Brillouin zone indicate the formation of a
novel spin-liquid phase in a triangular antiferromagnet. This phase is gapless
and shows a non-trivial evolution of the low-temperature specific heat. Our
work demonstrates that NaYbO practically gives the most direct experimental
access to the spin-liquid physics of triangular antiferromagnets.Comment: 6 pages, 4figure
Synthetic Routes to Crystalline Complex Metal Alkyl Carbonates and Hydroxycarbonates via SolâGel ChemistryâPerspectives for Advanced Materials in Catalysis
Metal alkoxides are easily available and versatile precursors for functional materials,
such as solid catalysts. However, the poor solubility of metal alkoxides in organic solvents usually
hinders their facile application in solâgel processes and complicates access to complex carbonate
or oxidic compounds after hydrolysis of the precursors. In our contribution we have therefore
shown three different solubilization strategies for metal alkoxides, namely the derivatization, the
hetero-metallization and CO2 insertion. The latter strategy leads to a stoichiometric insertion of CO2
into the metalâoxygen bond of the alkoxide and the subsequent formation of metal alkyl carbonates.
These precursors can then be employed advantageously in solâgel chemistry and, after controlled
hydrolysis, result in chemically defined crystalline carbonates and hydroxycarbonates. Cu- and
Zn-containing carbonates and hydroxycarbonates were used in an exemplary study for the synthesis
of Cu/Zn-based bulk catalysts for methanol synthesis with a final comparable catalytic activity to
commercial standard reference catalysts
Illusory Body Ownership Affects the Cortical Response to Vicarious Somatosensation
Fundamental human feelings such as body ownership (âthisâ body is âmyâ body) and vicariousness (first-person-like experience of events occurring to others) are based on multisensory integration. Behavioral links between body ownership and vicariousness have been shown, but the neural underpinnings remain largely unexplored. To fill this gap, we investigated the neural effects of altered body ownership on vicarious somatosensation. While recording functional brain imaging data, first, we altered participantsâ body ownership by robotically delivering tactile stimulations (âtactileâ stroking) in synchrony or not with videos of a virtual hand being brushed (âvisualâ stroking). Then, we manipulated vicarious somatosensation by showing videos of the virtual hand being touched by a syringeâs plunger (touch) or needle (pain). Only after the alteration of body ownership (synchronous visuo-tactile stroking) and specifically during late epochs of vicarious somatosensation, vicarious pain was associated with lower activation in premotor and anterior cingulate cortices with respect to vicarious touch. At the methodological level, the present study highlights the importance of the neural responseâs temporal evolution. At the theoretical level, it shows that the higher-level (cognitive) impact of a lower-level (sensory) body-related processing (visuo-tactile) is not limited to body ownership but also extends to other psychological body-related domains, such as vicarious somatosensation
Prazosin during threat discrimination boosts memory of the safe stimulus
The α-1 adrenoreceptor antagonist prazosin has shown promise in the treatment of post-traumatic stress disorder (PTSD) symptoms, but its mechanisms are not well understood. Here we administered prazosin or placebo prior to threat conditioning (day 1) and tested subsequent extinction (day 2) and reextinction (day 3) in healthy human participants. Prazosin did not affect threat conditioning but augmented stimulus discrimination during extinction and reextinction, via lower responding to the safe stimulus. These results suggest that prazosin during threat acquisition may have influenced encoding or consolidation of safety processing in particular, subsequently leading to enhanced discrimination between the safe and threatening stimuli
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