Nodal s± pairing symmetry in an iron-based superconductor with only hole pockets

The origin of high-temperature superconductivity in iron-based superconductors is still not understood; determination of the pairing symmetry is essential for understanding the superconductivity mechanism. In the iron-based superconductors that have hole pockets around the Brillouin zone centre and electron pockets around the zone corners, the pairing symmetry is generally considered to be s±, which indicates a sign change in the superconducting gap between the hole and electron pockets. For the iron-based superconductors with only hole pockets, however, a couple of pairing scenarios have been proposed, but the exact symmetry is still controversial. Here we determine that the pairing symmetry in KFe2As2—which is a prototypical iron-based superconductor with hole pockets both around the zone centre and around the zone corners—is also of the s± type. Our laser-based angle-resolved photoemission measurements have determined the superconducting gap distribution and identified the locations of the gap nodes on all the Fermi surfaces around the zone centres and the zone corners. These results unify the pairing symmetry in hole-doped iron-based superconductors and point to spin fluctuation as the pairing glue in generating superconductivity

<i>Trans</i>-vaccenic acid reprograms CD8⁺ T cells and anti-tumour immunity

Diet-derived nutrients are inextricably linked to human physiology by providing energy and biosynthetic building blocks and by functioning as regulatory molecules. However, the mechanisms by which circulating nutrients in the human body influence specific physiological processes remain largely unknown. Here we use a blood nutrient compound library-based screening approach to demonstrate that dietary trans-vaccenic acid (TVA) directly promotes effector CD8+ T cell function and anti-tumour immunity in vivo. TVA is the predominant form of trans-fatty acids enriched in human milk, but the human body cannot produce TVA endogenously. Circulating TVA in humans is mainly from ruminant-derived foods including beef, lamb and dairy products such as milk and butter, but only around 19% or 12% of dietary TVA is converted to rumenic acid by humans or mice, respectively. Mechanistically, TVA inactivates the cell-surface receptor GPR43, an immunomodulatory G protein-coupled receptor activated by its short-chain fatty acid ligands. TVA thus antagonizes the short-chain fatty acid agonists of GPR43, leading to activation of the cAMP–PKA–CREB axis for enhanced CD8+ T cell function. These findings reveal that diet-derived TVA represents a mechanism for host-extrinsic reprogramming of CD8+ T cells as opposed to the intrahost gut microbiota-derived short-chain fatty acids. TVA thus has translational potential for the treatment of tumours

Computer-Aided Drug Design in Epigenetics

Epigenetic dysfunction has been widely implicated in several diseases especially cancers thus highlights the therapeutic potential for chemical interventions in this field. With rapid development of computational methodologies and high-performance computational resources, computer-aided drug design has emerged as a promising strategy to speed up epigenetic drug discovery. Herein, we make a brief overview of major computational methods reported in the literature including druggability prediction, virtual screening, homology modeling, scaffold hopping, pharmacophore modeling, molecular dynamics simulations, quantum chemistry calculation, and 3D quantitative structure activity relationship that have been successfully applied in the design and discovery of epi-drugs and epi-probes. Finally, we discuss about major limitations of current virtual drug design strategies in epigenetics drug discovery and future directions in this field

experimentalstudyonconversionefficiencyofafloatingowcpentagonalbackwardbentductbuoywaveenergyconverter

Wave tank tests were carried out to evaluate the total efficiency of a floating OWC Pentagonal Backward Bent Duct Buoy (PBBDB). Two kinds of turbine generators were used in tests. The incident wave power, pneumatic power and electricity were measured. The test results show that the primary efficiency can reach up to 185.98% in regular waves and 85.86% in irregular waves. The total efficiency from wave to wire with Wells turbine-generator set is 33.43% in regular waves and 15.82% in irregular waves. The peak total efficiency of the PBBDB with check valves equipped with the impulse turbine-generator set is 41.68% in regular waves and 27.10% in irregular waves. The efficiency of the turbine-generator set is about 30% in the tests. Obviously, the total efficiency can be further improved with the increasing of turbine efficiency

BBDB wave energy conversion technology and perspective in China

In this paper, the development of Backward Bent Duct Buoy (BBDB) wave energy conversion technology in China is summarized. Novel ideas, new testing data and the improved performance of the BBDB conversion technology are presented. The latest large-scale model experimental results show that the peak wave-to-wire conversion efficiency of a new BBDB device is 42.0% under regular waves and it is 27.1% under random waves with the load of the battery. By comparison with the experimental and sea trial results of Japan's "Mighty Whale", the BBDB prototypes based on the experimental results of the new BBDB model present many advantages. If equipped with the latest air turbine, the conversion efficiency from pneumatic power to electric power of which is nearly 60% in sea trial, the efficiency from wave to wire of the new BBDB converter has the potential to exceed 50% in real sea waves, which is much higher than that of many other wave energy conversion technologies

The Phoenix-like Noble Metal: Cu

Copper is one of the least reactive metals under atmospheric conditions. By heating copper in air to hundreds of degrees centigrade, its surface is oxidized to black CuO. Interestingly, the black CuO surface layer peels off automatically when the temperature of the sample is lowered to room temperature. Three-dimensional red self-assembled Cu₂O nanostructures are observed in the new exposed surface (this phenomenon is compared to a phoenix reborn from the ashes). A simple extension of the spinodal decomposition to single phase system is proposed to account quantitatively for the self-assembled behavior of Cu₂O nanostructures. The presented analysis is also useful to understand similar behaviors of other single phase systems

Excellent field emission properties of vertically oriented CuO nanowire films

Oriented CuO nanowire films were synthesized on a large scale using simple method of direct heating copper grids in air. The field emission properties of the sample can be enhanced by improving the aspect ratio of the nanowires just through a facile method of controlling the synthesis conditions. Although the density of the nanowires is large enough, the screen effect is not an important factor in this field emission process because few nanowires sticking out above the rest. Benefiting from the unique geometrical and structural features, the CuO nanowire samples show excellent field emission (FE) properties. The FE measurements of CuO nanowire films illustrate that the sample synthesized at 500 °C for 8 h has a comparatively low turn-on field of 0.68 V/μm, a low threshold field of 1.1 V/μm, and a large field enhancement factor β of 16782 (a record high value for CuO nanostructures, to the best of our knowledge), indicating that the samples are promising candidates for field emission applications

Top-Seeded Solution Growth and Optical Properties of Deep-UV Birefringent Crystal Ba₂Ca(B₃O₆)₂

Single crystals of the birefringent material Ba₂Ca­(B₃O₆)₂ (BCBO) with dimensions up to 40 × 28 × 10 mm³ were successfully grown by top-seeded solution growth (TSSG) method from B₂O₃–NaF flux. It exhibits high transmittance in the range of 190–3000 nm with UV cutoff of 178 nm, which is much shorter than that (189 nm) of the commercial UV birefringent crystal, the high-temperature phase of BaB₂O₄ (α-BBO). Meanwhile, BCBO crystal has large birefringence (Δ<i>n</i> = <i>n</i>_o – <i>n</i>_e = 0.2524–0.0862) in the wavelength range from 178 to 3000 nm and without phase transition from room temperature to the melting point. A prototype of Glan–Taylor polarizer made from BCBO crystal showed an optical extinction ratio of 10⁴:1, which is comparable to those of commercial birefringence crystals. The experimental results demonstrate that the BCBO crystal can be a new promising birefringent crystal for UV, especially the sub-200 nm deep-UV range