Scattering rate collapse driven by a van Hove singularity in the Dirac semi-metal PdTe2_{2}

We present optical measurements of the transition metal dichalcogenide PdTe$_{2}$. The reflectivity displays an unusual temperature and energy dependence in the far-infrared, which we show can only be explained by a collapse of the scattering rate at low temperature, resulting from the vicinity of a van Hove singularity near the Fermi energy. An analysis of the optical conductivity suggests that below 150 K a reduction in the available phase space for scattering takes place, resulting in long-lived quasiparticle excitations. We suggest that this reduction in phase space provides experimental evidence for a van Hove singularity close to the Fermi level. Our data furthermore indicates a very weak electron-phonon coupling. Combined this suggests that the superconducting transition temperature is set by the density of states associated with the van Hove singularity.Comment: 4 pages, 3 figure

Carrier density crossover and quasiparticle mass enhancement in a doped 5dd Mott insulator

High-temperature superconductivity in cuprates emerges upon doping the parent Mott insulator. Robust signatures of the low-doped electronic state include a Hall carrier density that initially tracks the number of doped holes and the emergence of an anisotropic pseudogap; the latter characterised by disconnected Fermi arcs, closure at a critical doping level $p^* \approx 0.19$, and, in some cases, a strongly enhanced carrier effective mass. In Sr$_2$IrO$_4$, a spin-orbit-coupled Mott insulator often regarded as a 5$d$ analogue of the cuprates, surface probes have revealed the emergence of an anisotropic pseudogap and Fermi arcs under electron doping, though neither the corresponding $p^*$ nor bulk signatures of pseudogap closing have as yet been observed. Here, we report electrical transport and specific heat measurements on Sr$_{2-x}$La$_x$IrO$_4$ over an extended doping range 0 $\leq x \leq$ 0.20. The effective carrier density $n_{\rm H}$ at low temperatures exhibits a crossover from $n_{\rm H} \approx x$ to $n_{\rm H} \approx 1+x$ near $x$ = 0.16, accompanied by \textcolor{blue}{a five-orders-of-magnitude increase in conductivity} and a six-fold enhancement in the electronic specific heat. These striking parallels in the bulk pseudogap phenomenology, coupled with the absence of superconductivity in electron-doped Sr$_2$IrO$_4$, disfavour the pseudogap as a state of precursor pairing and thereby narrow the search for the key ingredient underpinning the formation of the superconducting condensate in doped Mott insulators

Unravelling structure sensitivity in CO2 hydrogenation over nickel

Continuous efforts in the field of materials science have allowed us to generate smaller and smaller metal nanoparticles, creating new opportunities to understand catalytic properties that depend on the metal particle size. Structure sensitivity is the phenomenon where not all surface atoms in a supported metal catalyst have the same activity. Understanding structure sensitivity can assist in the rational design of catalysts, allowing control over mechanisms, activity and selectivity, and thus even the viability of a catalytic reaction. Here, using a unique set of well-defined silica-supported Ni nanoclusters (1–7 nm) and advanced characterization methods, we prove how structure sensitivity influences the mechanism of catalytic CO2 reduction, the nature of which has been long debated. These findings bring fundamental new understanding of CO2 hydrogenation over Ni and allow us to control both activity and selectivity, which can be a means for CO2 emission abatement through its valorization as a low- or even negative-cost feedstock on a low-cost transition-metal catalyst

Publisher Correction: Unravelling structure sensitivity in CO2 hydrogenation over nickel

Correction to: Nature Catalysis https://doi.org/10.1038/s41929-017-0016-y, published online 29 January 2018

A nurse-initiated pain protocol in the ED improves pain treatment in patients with acute musculoskeletal pain

While acute musculoskeletal pain is a frequent complaint, its management is often neglected. An implementation of a nurse-initiated pain protocol based on the algorithm of a Dutch pain management guideline in the emergency department might improve this. A pre–post intervention study was performed as part of the prospective PROTACT follow-up study. During the pre- (15 months, n = 504) and post-period (6 months, n = 156) patients’ self-reported pain intensity and pain treatment were registered. Analgesic provision in patients with moderate to severe pain (NRS ≥4) improved from 46.8% to 68.0%. Over 10% of the patients refused analgesics, resulting into an actual analgesic administration increase from 36.3% to 46.1%. Median time to analgesic decreased from 10 to 7 min (P &lt; 0.05), whereas time to opioids decreased from 37 to 15 min (P &lt; 0.01). Mean pain relief significantly increased to 1.56 NRS-points, in patients who received analgesic treatment even up to 2.02 points. The protocol appeared to lead to an increase in analgesic administration, shorter time to analgesics and a higher clinically relevant pain relief. Despite improvements, suffering moderate to severe pain at ED discharge was still common. Protocol adherence needs to be studied in order to optimize pain management.</p

Synthesis and preclinical evaluation of [C-11]MA-PB-1 for in vivo imaging of brain monoacylglycerol lipase (MAGL)

MAGL is a potential therapeutic target for oncological and psychiatric diseases. Our objective was to develop a PET tracer for in vivo quantification of MAGL. We report [11C]MA-PB-1 as an irreversible MAGL inhibitor PET tracer. The in vitro inhibitory activity, ex vivo distribution, brain kinetics and specificity of [11C]MA-PB-1 binding were studied. Ex vivo biodistribution and microPET showed good brain uptake which could be blocked by pretreatment with both MA-PB-1 and a structurally non-related MAGL inhibitor MJN110. These initial results suggest that [11C]MA-PB-1 is a suitable tracer for in vivo imaging of MAGL.publisher: Elsevier articletitle: Synthesis and preclinical evaluation of [11C]MA-PB-1 for in vivo imaging of brain monoacylglycerol lipase (MAGL) journaltitle: European Journal of Medicinal Chemistry articlelink: http://dx.doi.org/10.1016/j.ejmech.2017.04.066 content_type: article copyright: © 2017 Elsevier Masson SAS. All rights reserved.status: publishe

Synthesis and preclinical evaluation of [11C]MA-PB-1 for in\ua0vivo imaging of brain monoacylglycerol lipase (MAGL)

MAGL is a potential therapeutic target for oncological and psychiatric diseases. Our objective was to develop a PET tracer for in\ua0vivo quantification of MAGL. We report [C]MA-PB-1 as an irreversible MAGL inhibitor PET tracer. The in\ua0vitro inhibitory activity, ex\ua0vivo distribution, brain kinetics and specificity of [C]MA-PB-1 binding were studied. Ex\ua0vivo biodistribution and microPET showed good brain uptake which could be blocked by pretreatment with both MA-PB-1 and a structurally non-related MAGL inhibitor MJN110. These initial results suggest that [C]MA-PB-1 is a suitable tracer for in\ua0vivo imaging of MAGL