73 research outputs found
Superconductivity at 5 K in potassium doped phenanthrene
Organic materials are believed to be potential superconductor with high
transition temperature (TC). Organic superconductors mainly have two families:
the quasi-one dimensional (TMTSF)2X and two dimensional (BEDT-TTF)2X (Ref. 1
and 2), in which TMTSF is tetramethyltetraselenafulvalene (C10H12Se4) and
BEDT-TTF or "ET" is bis(ethylenedithio)tetrathiafulvalene (C10H8S8). One key
feature of the organic superconductors is that they have {\pi}-molecular
orbitals, and the {\pi}-electron can delocalize throughout the crystal giving
rise to metallic conductivity due to a {\pi}-orbital overlap between adjacent
molecules. The introduction of charge into C60 solids and graphites with
{\pi}-electron networks by doping to realize superconductivity has been
extensively reported3,4. Very recently, superconductivity in alkali-metal doped
picene with {\pi}-electron networks was reported5. Here we report the discovery
of superconductivity in potassium doped Phenanthrene with TC~5 K. TC increases
with increasing pressure, and the pressure of 1 GPa leads to an increase of 20%
in TC, suggesting that the potassium doped phenanthrene shows unconventional
superconductivity. Both phenanthrene and picene are polycyclic aromatic
hydrocarbons, and contain three and five fused benzene rings, respectively. The
ribbon of fused benzene rings is part of graphene. Therefore, the discovery of
superconductivity in K3Phenanthrene produces a novel broad class of
superconductors consisting of fused hydrocarbon benzene rings with
{\pi}-electron networks. The fact that TC increases from 5 K for KxPhenanthrene
with three benzene rings to 18 K for Kxpicene with five benzene rings suggests
that such organic hydrocarbons with long benzene rings is potential
superconductor with high TC.Comment: 20 pages, 3 figures, one supplementary information. submitted to
Nature Communication
Cognitive performance and leukocyte telomere length in two narrow age-range cohorts: a population study
The role of epigenetics in renal ageing
An ability to separate natural ageing processes from processes specific to morbidities is required to understand the heterogeneity of age-related organ dysfunction. Mechanistic insight into how epigenetic factors regulate ageing throughout the life course, linked to a decline in renal function with ageing, is already proving to be of value in the analyses of clinical and epidemiological cohorts. Noncoding RNAs provide epigenetic regulatory circuits within the kidney, which reciprocally interact with DNA methylation processes, histone modification and chromatin. These interactions have been demonstrated to reflect the biological age and function of renal allografts. Epigenetic factors control gene expression and activity in response to environmental perturbations. They also have roles in highly conserved signalling pathways that modulate ageing, including the mTOR and insulin/insulin-like growth factor signalling pathways, and regulation of sirtuin activity. Nutrition, the gut microbiota, inflammation and environmental factors, including psychosocial and lifestyle stresses, provide potential mechanistic links between the epigenetic landscape of ageing and renal dysfunction. Approaches to modify the renal epigenome via nutritional intervention, targeting the methylome or targeting chromatin seem eminently feasible, although caution is merited owing to the potential for intergenerational and transgenerational effects
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency–Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research
Hochdruck-Metamorphose in Gneisen und pelitischen Schiefern der �stlichen RhodopeZone, Nord-Griechenland
CCR2 Defines a Distinct Population of NK Cells and Mediates Their Migration during Influenza Virus Infection in Mice
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