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An argument by contradiction shows that the pseudogap state in the high-temperature superconducting cuprates is due to the superconducting pairing rather than being an independent or even competing state. Cuprates possess a large pseudogap that spans much of their phase diagram 1 , 2 . The origin of this pseudogap is as debated as the mechanism for high-temperature superconductivity. In one class of theories, the pseudogap arises from some instability not related to pairing, typically charge, spin or orbital current ordering. Evidence of this has come from a variety of measurements indicating symmetry breaking 3 , 4 , 5 , 6 . On the other side are theories where the pseudogap is associated with pairing. This ranges from preformed pairs 7 to resonating valence bond theories where spin singlets become charge coherent 8 . Here, we study pairing in the cuprates by constructing the pair vertex using spectral functions derived from angle-resolved photoemission data. Assuming that the pseudogap is not due to pairing, we find that the superconducting instability is strongly suppressed, in stark contrast to what is actually observed. We trace this suppression to the destruction of the BCS logarithmic singularity from a combination of the pseudogap and lifetime broadening. Our findings strongly support those theories of the cuprates where the pseudogap is instead due to pairing.

A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a finite amplitude and long-range phase coherence set in simultaneously at the CDW transition temperature T cdw . Here we investigate, using photoemission, X-ray scattering and scanning tunnelling microscopy, the canonical CDW compound 2 H -NbSe 2 intercalated with Mn and Co, and show that the conventional view is untenable. We find that, either at high temperature or at large intercalation, CDW order becomes short-ranged with a well-defined amplitude, which has impacts on the electronic dispersion, giving rise to an energy gap. The phase transition at T cdw marks the onset of long-range order with global phase coherence, leading to sharp electronic excitations. Our observations emphasize the importance of phase fluctuations in strongly coupled CDW systems and provide insights into the significance of phase incoherence in ‘pseudogap’ states. Charge density waves are described by a complex order parameter whose amplitude is expected to vanish at the transition temperature. This study shows that the transition in 2 H -NbSe 2 is driven by fluctuations of the phase of the order parameter, with a finite amplitude surviving in the disordered state.

In the traditional Bardeen–Cooper–Schrieffer theory of superconductivity, the amplitude for the propagation of a pair of electrons with momentum k and − k has a log singularity as the temperature decreases. This so-called Cooper instability arises from the presence of an electron Fermi sea. It means that an attractive interaction, no matter how weak, will eventually lead to a pairing instability. However, in the pseudogap regime of the cuprate superconductors, where parts of the Fermi surface are destroyed, this log singularity is suppressed, raising the question of how pairing occurs in the absence of a Fermi sea. Here we report Hubbard model numerical results and the analysis of angular-resolved photoemission experiments on a cuprate superconductor. In contrast to the traditional theory, we find that in the pseudogap regime the pairing instability arises from an increase in the strength of the spin–fluctuation pairing interaction as the temperature decreases rather than the Cooper log instability. Pairing interaction appears at room temperature in traditional superconductors with a Cooper instability in the Fermi sea. Here, Maier et al. report that in the pseudogap phase of cuprate, where this instability is absent, superconductivity arises from an increase in the strength of the spin fluctuation pairing interaction as the temperature decreases.

Protein kinase CK2 (also known as Caseine Kinase II) is an ubiquitous Ser/Thr protein kinase present in both the nucleus and cytoplasm of cells, targeting several key enzymes, growth factor receptors, transcription factors and cytoskeletal proteins. It is not only a key player in regulating cellular growth and proliferation, but also behaves as a potent suppressor of apoptosis. CK2 has been frequently found to be deregulated (mostly hyperactivated) in all cancers, prostate cancer being prominent of them. In the recent past, tumor suppressor PML (promyelocytic leukemia) has been shown to be a target of phosphorylation by CK2. This phosphorylation promotes the ubiquitin-mediated proteasomal degradation of PML thereby effectively curbing its role as a tumor suppressor. Among many others, PML has also been established to mediate its tumor suppressive role by mitigating the inactivation of active AKT (pAKT) inside the nucleus by assembling a dephosphorylating platform for nuclear pAKT. One of the immediate consequences, of this inactivation is the stabilization of FOXO3a, another well-established tumor suppressor, inside the nucleus and its downstream activities. Here, we propose a novel signaling axis apexed by deregulated CK2, dismantling the association of PML and PHLPP2 (we also report PHLPP2 to be a novel interacting partner of PML inside the nucleus), ultimately leading to the inactivation and nuclear exclusion of FOXO3a, thereby downregulating p21/p27/Bim in which degradation of PML and the concomitant stabilization of pAKT plays a cardinal part.

The response of a material to external stimuli depends on its low-energy excitations. In conventional metals, these excitations are electrons on the Fermi surface—a contour in momentum ( k ) space that encloses all of the occupied states for non-interacting electrons. The pseudogap phase in the copper oxide superconductors, however, is a most unusual state of matter 1 . It is metallic, but part of its Fermi surface is ‘gapped out’ (refs  2 , 3 ); low-energy electronic excitations occupy disconnected segments known as Fermi arcs 4 . Two main interpretations of its origin have been proposed: either the pseudogap is a precursor to superconductivity 5 , or it arises from another order competing with superconductivity 6 . Using angle-resolved photoemission spectroscopy, we show that the anisotropy of the pseudogap in k -space and the resulting arcs depend only on the ratio T / T * ( x ), where T * ( x ) is the temperature below which the pseudogap first develops at a given hole doping x . The arcs collapse linearly with T / T * ( x ) and extrapolate to zero extent as T →0. This suggests that the T =0 pseudogap state is a nodal liquid—a strange metallic state whose gapless excitations exist only at points in k -space, just as in a d -wave superconducting state.

The amyloid-β peptide (Aβ) can generate cytotoxic oligomers, and their accumulation is thought to underlie the neuropathologic changes found in Alzheimer's disease. Known inhibitors of Aβ polymerization bind to undefined structures and can work as nonspecific aggregators, and inhibitors that target conformations that also occur in larger Aβ assemblies may even increase oligomer-derived toxicity. Here we report on an alternative approach whereby ligands are designed to bind and stabilize the 13-26 region of Aβ in an α-helical conformation, inspired by the postulated Aβ native structure. This is achieved with 2 different classes of compounds that also reduce Aβ toxicity to cells in culture and to hippocampal slice preparations, and that do not show any nonspecific aggregatory properties. In addition, when these inhibitors are administered to Drosophila melanogaster expressing human Aβ₁₋₄₂ in the central nervous system, a prolonged lifespan, increased locomotor activity, and reduced neurodegeneration is observed. We conclude that stabilization of the central Aβ α-helix counteracts polymerization into toxic assemblies and provides a strategy for development of specific inhibitors of Aβ polymerization.

Trends of present-day sea level anomaly (SLA) in western Maritime Continent based on the combination of global thermal expansion and ocean dynamics (steric/dynamic), simulated by Coupled Global Climate Models (CGCMs) under the Climate Model Intercomparison Project phase-5 and 6 (CMIP5/6), are evaluated by using satellite observation. Trends of SLA based on the steric/dynamic component of sea level underestimate the one observed by the satellite for the interior seas of western Maritime Continent. However, satellite observation is also known to overestimate the rate of sea level rise in this shallow basin. Thus, the actual trends of SLA in this area could be approximated based on its steric/dynamic component simulated by CGCMs such as ACCESS1-0 and MIROC-ESM.

The corrosion behaviour of heat treated Ti–13Zr–13Nb (TZN) and Ti–13Zr–13Nb–0.5B (TZNB) alloys in Hank’s solution has been investigated. The microstructure of the heat treated TZN alloy consisted of α, β or martensite. Addition of boron to TZN alloy led to the formation of dispersed TiB particles and modification of microstructure. In general, the furnace cooled TZN sample showed lower corrosion potential (E corr ) than the air cooled sample. Aging of water quenched samples decreased the E corr value. The passive current density of TZN samples varied within a narrow range. Presence of boron in TZN alloy decreased the corrosion potential and substantially increased the passive current density. Results showed that boron deteriorated the corrosion resistance of TZN alloy.

In the present study, a detailed investigation of mechanical and electrochemical properties of laser-surface-nitrided Ti-6Al-4V has been carried out. Laser treatment is carried out by melting the surface of Ti-6Al-4V substrate using a high power CW diode laser with nitrogen as shrouding environment. The effect of laser parameters (applied power and gas flow rate) on the properties of the nitrided surface was evaluated. The microhardness of the nitrided surface was improved to a maximum of 1175 VHN in the present set of laser processing conditions as compared to 280 VHN of as-received substrate. Surface nitriding increased the potential for pit formation ( E pit ) significantly as compared to as-received Ti-6Al-4V. Immersion in Hank’s solution showed calcium phosphate deposition from the solution. The optimum process parameters for laser surface nitriding were derived.