Y3Al5O12:Ce3+ (YAG:Ce3+) transparent ceramic phosphors (TCPs) are regarded as the most promising luminescent converter for laser‐driven (LD) lighting. High‐quality YAG:Ce3+ TCPs are still urgent for high efficiency LD lighting devices. YAG:Ce3+ TCPs in a vacuum ambience by using nano‐sized raw materials are prepared. Controlling defects by adding nano‐sized MgO and SiO2 simultaneously enables a high transmittance nearly 80%. After annealing in air furthermore, the luminous efficiency is enhanced greatly from 106 to 223 lm W−1, which is the best result reported now for LD lighting. These results demonstrate that the optimizing YAG:Ce3+ TCPs in a fitting strategy will brighten once again in the next‐generation LD lighting. Based on scanning electron microscopy (SEM) coupled with a cathodoluminescence system, defects and Ce3+ distributions in grains are identified directly for the first time.

FeSe exhibits a novel ground state in which superconductivity coexists with a nematic order in the absence of any long-range magnetic order. Here we report an angle-resolved photoemission study on the superconducting gap structure in the nematic state of FeSe 0.93 S 0.07 , without the complication caused by Fermi surface reconstruction induced by magnetic order. We found that the superconducting gap shows a pronounced 2-fold anisotropy around the elliptical hole pocket near the Z point of the Brillouin zone, with gap minima at the endpoints of its major axis, while no detectable gap was observed around the zone center and zone corner. The large anisotropy and nodal gap distribution demonstrate the substantial effects of the nematicity on the superconductivity, and thus put strong constraints on the current theories. PACS numbers: 74.70.Xa, 74.25.Jb, 74.20.Mn The pairing mechanism underlying unconventional superconductivity is often related to the quantum fluctuations of nearby orders. In most Fe-based superconductors, both magnetic and nematic orders appear simultaneously near the superconducting state. Accordingly, both spin-fluctuationmediated and orbital-fluctuation-mediated superconducting pairing mechanisms have been proposed [1][2][3][4][5]. Although intense experimental studies have been conducted [6][7][8][9][10][11][12][13], the exact pairing mechanism of Fe-based superconductors is still under heated debate.FeSe is a unique material with a novel superconducting state. Orbital order develops in the nematic state of FeSe without breaking the translational symmetry as shown by angle resolved photoemission spectroscopy (ARPES) studies [14,15]. The superconductivity coexists with the nematic order without any long range magnetic order [16], thus disentangling the magnetic and orbital orders. Moreover, recent results suggest that FeSe is a quantum paramagnet [4] with coexisting Néel and stripe antiferromagnetic interactions [17,18]. The novel ground state in FeSe provides a fresh perspective for studying the effect of nematic order on the superconducting gap structure in the absence of the Fermi surface reconstruction induced by magnetic order, which helps to reveal the roles of spin and orbital degrees of freedom in unconventional superconductivity. A nodeless superconducting gap structure in FeSe was suggested by previous reports on specific heat [19], Andreev reflection spectroscopy [20], and thermal conductivity measurements [21]. In contrast, scanning tunnelling spectroscopy (STS) studies on FeSe films [22] and transport measurements on bulk FeSe/FeSe 1−x S x crystals with improved quality [23,24] all demonstrate a nodal gap structure. However, due to the low T c and small gap size of FeSe/FeSe 1−x S x single crystals, the gap distribution in momentum-space is still unknown.In this work, we studied the superconducting gap structure of high-quality FeSe 0.93 S 0.07 single crystals (T c = 10 K) with high resolution ARPES [25]. At 6.3 K, both the nematic electronic structure and the superconducting gap ...

At the interface between monolayer FeSe films and SrTiO3 substrates the superconducting transition temperature (Tc) is unexpectedly high, triggering a surge of excitement. The mechanism for the Tc enhancement has been the central question, as it may present a new strategy for seeking out higher Tc materials. To reveal this enigmatic mechanism, by combining advances in high quality interface growth, 16O 18O isotope substitution, and extensive data from angle resolved photoemission spectroscopy, we provide striking evidence that the high Tc in FeSe/SrTiO3 is the cooperative effect of the intrinsic pairing mechanism in the FeSe and interactions between the FeSe electrons and SrTiO3 phonons. Furthermore, our results point to the promising prospect that similar cooperation between different Cooper pairing channels may be a general framework to understand and design high-temperature superconductors.

No abstract

Perovskite SrIrO3 has long been proposed as an exotic semimetal induced by the interplay between the spin-orbit coupling and electron correlations. However, its low-lying electronic structure is still lacking. We synthesize high-quality perovskite SrIrO3 (100) films by means of oxide molecular beam epitaxy, and then systemically investigate their low energy electronic structure using in-situ angle-resolved photoemission spectroscopy. We find that the hole-like bands around R and the electron-like bands around U(T) intersect the Fermi level simultaneously, providing the direct evidence of the semimetallic ground state in this compound. Comparing with the density functional theory, we discover that the bandwidth of states near Fermi level is extremely small, and there exists a pronounced mixing between the Jeff = 1/2 and Jeff = 3/2 states. Moreover, our data reveal that the predicted Dirac degeneracy protected by the mirror-symmetry, which was theoretically suggested to be the key to realize the non-trivial topological properties, is actually lifted in perovskite SrIrO3 thin films. Our findings pose strong constraints on the current theoretical models for the 5d iridates.

Summary In early seedlings, the primary root adapts rapidly to environmental changes through the modulation of endogenous hormone levels. The phytohormone ethylene inhibits primary root elongation, but the underlying molecular mechanism of how ethylene‐reduced root growth is modulated in environmental changes remains poorly understood. Here, we show that a novel rice (Oryza sativa) DOF transcription factor OsDOF15 positively regulates primary root elongation by regulating cell proliferation in the root meristem, via restricting ethylene biosynthesis. Loss‐of‐function of OsDOF15 impaired primary root elongation and cell proliferation in the root meristem, whereas OsDOF15 overexpression enhanced these processes, indicating that OsDOF15 is a key regulator of primary root elongation. This regulation involves the direct interaction of OsDOF15 with the promoter of OsACS1, resulting in the repression of ethylene biosynthesis. The control of ethylene biosynthesis by OsDOF15 in turn regulates cell proliferation in the root meristem. OsDOF15 transcription is repressed by salt stress, and OsDOF15‐mediated ethylene biosynthesis plays a role in inhibition of primary root elongation by salt stress. Thus, our data reveal how the ethylene‐inhibited primary root elongation is finely controlled by OsDOF15 in response to environmental signal, a novel mechanism of plants responding to salt stress and transmitting the information to ethylene biosynthesis to restrict root elongation.

BackgroundThe hygiene hypothesis suggests that helminth infections prevent a range of autoimmune diseases.Methodology/Principal FindingsTo investigate the effects of S. japonicum infection on collagen-induced arthritis (CIA), male DBA/1 mice were challenged with unisexual or bisexual S. japonicum cercariae two weeks prior to bovine type II collagen (CII) immunization or at the onset of CIA. S. japonicum infection prior to CII immunization significantly reduced the severity of CIA. ELISA (enzyme linked immunosorbent assay) showed that the levels of anti-CII IgG and IgG2a were reduced in prior schistosome-infected mice, while anti-CII IgG1 was elevated. Splenocyte proliferation against both polyclonal and antigen-specific stimuli was reduced by prior schistosome infection as measured by tritiated thymidine incorporation (3H-TdR). Cytokine profiles and CD4+ T cells subpopulation analysis by ELISA and flow cytometry (FCM) demonstrated that prior schistosome infection resulted in a significant down-regulation of pro-inflammatory cytokines (IFN-γ, TNF-α, IL-1β and IL-6) and Th1 cells, together with up-regulation of the anti-inflammatory cytokine IL-10 and Th2 cells. Interestingly, the expansion of Treg cells and the reduction of Th17 cells were only observed in bisexually infected mice. In addition, prior schistosome infection notably reduced the expression of pro-inflammatory cytokines and receptor activator of NF-κB ligand (RANKL) in the inflamed joint. However, the disease was exacerbated at one week after infection when established CIA mice were challenged with bisexual cercariae.Conclusion/SignificanceOur data provide direct evidence that the Th2 response evoked by prior S. japonicum infection can suppress the Th1 response and pro-inflammatory mediator and that bisexual infection with egg-laying up-regulates the Treg response and down-regulates the Th17 response, resulting in an amelioration of autoimmune arthritis. The beneficial effects might depend on the establishment of a Th2-dominant response rather than the presence of the eggs. Our results suggest that anti-inflammatory molecules from the parasite could treat autoimmune diseases.

We report the surface electronic structure of niobium phosphide NbP single crystal on (001) surface by vacuum ultraviolet angle-resolved photoemission spectroscopy. Combining with our first principle calculations, we identify the existence of the Fermi arcs originated from topological surface states. Furthermore, the surface states exhibit circular dichroism pattern, which may correlate with its non-trivial spin texture. Our results provide critical evidence for the existence of the Weyl Fermions in NbP, which lays the foundation for further investigations.PACS numbers: 71.55. Ak, 74.20.Pq, 74.25.Jb, In the past few years, great progress has been witnessed in the study of quantum materials with non-trivial topological electronic structures. By introducing topological orders, insulators can be further classified into trivial one and non-trivial one, that is, topological insulators (TIs) [1,2]. Due to their unique physical properties and great potential in applications, TIs have been one of the central research subject of condensed matter physics in the last decade.The recent proposal that Weyl fermions can be realized in the so-called topological Weyl semi-metals (TWSMs) broadens the classification of topological phases of matter beyond TIs [3][4][5][6][7]. The low energy excitations in this new type of topological quantum matter are described by the Weyl equation [8]. Thus, in the bulk, the conduction and valence bands disperse linearly cross pairs of discrete points (the Weyl points) along all three momentum directions. The Weyl points are associated with a chiral charge that protects gapless surface states (SSs) on the boundary of a bulk sample. These topological SSs take the form of unclosed curves connecting the Weyl points of opposite chirality [4], leading to the existence of the unique Fermi arcs on the surface. Due to the novel physical phenomena related to the Weyl fermions such as negative magneto-resistivity, quantum anomalous Hall effect and non-local quantum oscillations, the search of TWSMs have attracted worldwide attentions [9][10][11][12][13][14].In principle, by breaking either time reversal or spacial inversion symmetry of a Dirac semi-metal (DSM) to remove the spin degeneracy of the bands [15][16][17][18][19][20][21][22][23], the otherwise degenerate bulk Dirac point will be split into a pair of Weyl points of opposite chirality, leading to the realization of the TWSM. Early predictions of the TWSMs focus on magnetic materials, e.g. R 2 Ir 2 O 7 , HgCr 2 Se 4 , which naturally break the time reversal symmetry [4,5]. However, due to the intricate Y