Platinum deposition on functionalised graphene for corrosion resistant oxygen reduction electrodes

Graphene-related materials are promising supports for electrocatalysts due to their stability and high surface area. Their innate surface chemistries can be controlled and tuned via functionalisation to improve the stability of both the carbon support and the metal catalyst. Functionalised graphenes were prepared using either aryl diazonium functionalisation or non-destructive chemical reduction, to provide groups adapted for platinum deposition. XPS and TGA-MS measurements confirmed the presence of polyethyleneglycol and sulfur-containing functional groups, and provided consistent values for the extent of the reactions. The deposited platinum nanoparticles obtained were consistently around 2 nm via reductive chemistry and around 4 nm via the diazonium route. Although these graphene-supported electrocatalysts provided a lower electrochemical surface area (ECSA), functionalised samples showed enhanced specific activity compared to a commercial platinum/carbon black system. Accelerated stress testing (AST) showed improved durability for the functionalised graphenes compared to the non-functionalised materials, attributed to edge passivation and catalyst particle anchoring

Langzeitergebnisse nach endovaskulärem Aortenstent

<div><div><div><p>A major roadblock in realizing the large-scale production of hydrogen via electrochemical water splitting is the lack of cost-effective and highly efficient catalysts for the oxygen evolution reaction (OER). In this regard, computational research has driven important developments in the understanding and the design of heterogeneous OER catalysts by establishing linear scaling relations. These relations are of paramount importance since they drastically reduce the amount of time required to traverse the vast chemical search space of potential OER materials. In this work, we interrogate 17 of the most active molecular OER catalysts known to date based on different transition metals (M= Ru, Mn, Fe, Co, Ni, and Cu), and show that they obey the linear scaling relations established for metal oxides. This demonstrates that the conventional OER descriptor established for heterogeneous systems can also be applied to rapidly screen novel molecular catalysts. However, we find that this descriptor underestimates the activity of some of the most active OER complexes as it does not consider the additional one-electron oxidation that these undergo prior to O–O bond formation. Importantly, we show that this additional step allows certain molecular catalysts to circumvent the “overpotential wall” observed for heterogeneous systems (i.e. 370 mV), leading to an enhanced performance in agreement with experimental observations. To describe the activity of such highly active catalysts, we propose a new OER descriptor that opens up the possibility of designing molecular catalysts exhibiting zero theoretical overpotential. With all this knowledge, we establish the fundamental principles for the rational design of ideal OER catalysts to advance the development of water splitting technologies.</p></div></div></div

A Selective Interplay between Aberrant EPSPKA and INaP Reduces Spike Timing Precision in Dentate Granule Cells of Epileptic Rats

Spike timing precision is a fundamental aspect of neuronal information processing in the brain. Here we examined the temporal precision of input–output operation of dentate granule cells (DGCs) in an animal model of temporal lobe epilepsy (TLE). In TLE, mossy fibers sprout and establish recurrent synapses on DGCs that generate aberrant slow kainate receptor–mediated excitatory postsynaptic potentials (EPSPKA) not observed in controls. We report that, in contrast to time-locked spikes generated by EPSPAMPA in control DGCs, aberrant EPSPKA are associated with long-lasting plateaus and jittered spikes during single-spike mode firing. This is mediated by a selective voltage-dependent amplification of EPSPKA through persistent sodium current (INaP) activation. In control DGCs, a current injection of a waveform mimicking the slow shape of EPSPKA activates INaP and generates jittered spikes. Conversely in epileptic rats, blockade of EPSPKA or INaP restores the temporal precision of EPSP–spike coupling. Importantly, EPSPKA not only decrease spike timing precision at recurrent mossy fiber synapses but also at perforant path synapses during synaptic integration through INaP activation. We conclude that a selective interplay between aberrant EPSPKA and INaP severely alters the temporal precision of EPSP–spike coupling in DGCs of chronic epileptic rats

Whole-Exome Sequencing and Homozygosity Analysis Implicate Depolarization-Regulated Neuronal Genes in Autism

Although autism has a clear genetic component, the high genetic heterogeneity of the disorder has been a challenge for the identification of causative genes. We used homozygosity analysis to identify probands from nonconsanguineous families that showed evidence of distant shared ancestry, suggesting potentially recessive mutations. Whole-exome sequencing of 16 probands revealed validated homozygous, potentially pathogenic recessive mutations that segregated perfectly with disease in 4/16 families. The candidate genes (UBE3B, CLTCL1, NCKAP5L, ZNF18) encode proteins involved in proteolysis, GTPase-mediated signaling, cytoskeletal organization, and other pathways. Furthermore, neuronal depolarization regulated the transcription of these genes, suggesting potential activity-dependent roles in neurons. We present a multidimensional strategy for filtering whole-exome sequence data to find candidate recessive mutations in autism, which may have broader applicability to other complex, heterogeneous disorders

The Palmerston plan 1997

tag=1 data=The Palmerston plan 1997 tag=2 data=Coulter, Barry%Burke, Denis tag=3 data=Country Liberal Party - Party Policy tag=6 data=^d22^mAug ^y1997 tag=8 data=POLITICAL PARTIES-CLP%PALMERSTON tag=10 data=Palmerston policy for election 1997. tag=15 data=POLPalmerston policy for election 1997