High-temperature superconductivity in the cuprates is widely believed to originate from an antiferromagnetic parent Mott insulator when doped with charge carriers1. In terms of the electronic ...structure, the key question is how the large charge transfer gap evolves into the pseudogap and then the d-wave superconducting gap2, 3, 4, 5. However, whether superconductivity or some other symmetry-breaking state (such as charge or spin orders) emerges first on doping a Mott insulator is debatable. To address these issues, here we use scanning tunnelling microscopy to investigate the local electronic structure of lightly doped cuprates in the antiferromagnetic insulating regime. We show that the doped charge induces a spectral weight transfer from the high-energy Hubbard bands to low-energy states within the charge transfer gap. With increasing doping, a V-shaped density-of-state suppression reminiscent of the pseudogap occurs at the Fermi level, which is accompanied by the emergence of chequerboard charge order. Our data suggest that the cuprates first become a charge-ordered insulator on doping, and the Fermi surface and high-temperature superconductivity becomes manifest on further doping.r
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IJS, NUK, SBMB, UL, UM, UPUK
Electron-electron and electron-phonon interactions are two major driving forces that stabilize various charge-ordered phases of matter. In layered compound 1T-TaS2, the intricate interplay between ...the two generates a Mott-insulating ground state with a peculiar charge-density-wave (CDW) order. The delicate balance also makes it possible to use external perturbations to create and manipulate novel phases in this material. Here, we study a mosaic CDW phase induced by voltage pulses, and find that the new phase exhibits electronic structures entirely different from that of the original Mott ground state. The mosaic phase consists of nanometre-sized domains characterized by well-defined phase shifts of the CDW order parameter in the topmost layer, and by altered stacking relative to the layers underneath. We discover that the nature of the new phase is dictated by the stacking order, and our results shed fresh light on the origin of the Mott phase in 1T-TaS2.
Inflammatory bowel disease (IBD) mainly includes Crohn’s disease (CD) and ulcerative colitis (UC). Immune disorders play an essential role in the pathogenesis of these two IBDs, but the differences ...in the immune microenvironment of the colon and their underlying mechanisms remain poorly investigated. Here we examined the immunological features and metabolic microenvironment of untreated individuals with IBD by multiomics analyses. Modulation of CD-specific metabolites, particularly reduced selenium, can obviously shape type 1 T helper (Th1) cell differentiation, which is specifically enriched in CD. Selenium supplementation suppressed the symptoms and onset of CD and Th1 cell differentiation via selenoprotein W (SELW)-mediated cellular reactive oxygen species scavenging. SELW promoted purine salvage pathways and inhibited one-carbon metabolism by recruiting an E3 ubiquitin ligase, tripartite motif-containing protein 21, which controlled the stability of serine hydroxymethyltransferase 2. Our work highlights selenium as an essential regulator of T cell responses and potential therapeutic targets in CD.
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•Th1-like subpopulation and reduced selenium are identified in Crohn’s disease•Selenium suppresses Th1 differentiation in vitro and in vivo•Selenium-induced selenoprotein W inhibits Th1 polarization•Selenoprotein W regulates cellular ROS by altering the balance of purine synthesis
Immune disorders play an essential role in the onset of Crohn’s disease and ulcerative colitis, but the differences and underlying mechanisms between these two IBDs remain unclear. Huang et al. identify disease-specific features by multiomics analyses and highlight selenium as having a critical role in T cell responses in Crohn’s disease.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
One of the biggest puzzles concerning the cup- rate high temperature superconductors is what determines the maximum transition temperature （Tc,max）, which varies from less than 30 to above 130 K in ...different compounds. Despite this dramatic variation, a robust trend is that within each family, the double-layer compound always has higher Tc,max than the single-layer counterpart. Here we use scanning tunneling microscopy to investigate the electronic structure of four cuprate parent compounds belonging to two different families. We find that within each family, the double layer compound has a much smaller charge transfer gap size （ACT）, indicating a clear anticorrelation between AcT and Tc,max. These results suggest that the charge transfer gap plays a key role in the superconducting physics of cuprates, which shed important new light on the high To mechanism from doped Mott insulator perspective.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UL, UM, UPCLJ, UPUK, VKSCE, ZAGLJ, ZRSKP
Although the mechanism of superconductivity in the cuprates remains elusive, it is generally agreed that at the heart of the problem is the physics of doped Mott insulators. A crucial step for ...solving the high temperature superconductivity puzzle is to elucidate the electronic structure of the parent compound and the behaviour of doped charge carriers. Here we use scanning tunnelling microscopy to investigate the atomic-scale electronic structure of the Ca(2)CuO(2)Cl(2) parent Mott insulator of the cuprates. The full electronic spectrum across the Mott-Hubbard gap is uncovered for the first time, which reveals the particle-hole symmetric and spatially uniform Hubbard bands. Defect-induced charge carriers are found to create broad in-gap electronic states that are strongly localized in space. We show that the electronic structure of pristine Mott insulator is consistent with the Zhang-Rice singlet model, but the peculiar features of the doped electronic states require further investigations.
One of the key issues in unraveling the mystery of high TC superconductivity in the cuprates is to understand the normal state outside the superconducting dome. Here we perform scanning tunneling ...microscopy and spectroscopy measurements on a heavily overdoped, non-superconducting (Bi, Pb)2Sr2CuO6+δ cuprate. Spectroscopic imaging reveals dispersive quasiparticle interferences (QPIs) and the Fourier transforms uncover the evolution of momentum space topology. More interestingly, we observe nanoscale patches of static charge order with 2 × 2 periodicity. Both the dispersive QPI and static charge order can be qualitatively explained by theoretical calculations, which reveal the unique electronic structure of strongly overdoped cuprate.
Monolayer transition metal dichalcogenides MX2 (M = Mo, W; X = S) exhibit remarkable electronic and optical properties, making them candidates for application within flexible nano-optoelectronics. ...The ability to achieve a high optical signal, while quantitatively monitoring strain in real-time is the key requirement for applications in flexible sensing and photonics devices. Surface-enhanced Raman scattering (SERS) allows us to achieve both simultaneously. However, the SERS depends crucially on the size and shape of the metallic nanoparticles (NPs), which have a large impact on its detection sensitivity. Here, we investigated the SERS of monolayer MX2, with particular attention paid to the effect of the distribution of the metallic NPs. We show that the SERS depends crucially on the distribution of the metallic NPs and also the phonon mode of the MX2. Moreover, strong coupling between MX2 and metallic NPs, through surface plasmon excitation, results in splitting of the and modes and an additional peak becomes apparent. For a WS2-Ag system the intensity of the additional peak increases exponentially with local strain, which opens another interesting window to quantitatively measure the local strain using SERS. Our experimental study may be useful for the application of monolayer MX2 in flexible nano-optoelectronics.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A novel technique, high temperature headspace liquid-phase microextraction (HS-LPME) with room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate (C
4MIMPF
6) as ...extractant, was developed for the analysis of dichlorodiphenyltrichloroethane (
p,
p′-DDT and
o,
p′-DDT) and its metabolites including 4,4′-dichlorodiphenyldichloroethylene (
p,
p′-DDE) and 4,4′-dichlorodiphenyldichloroethane (
p,
p′-DDD) in water samples by high performance liquid chromatography with ultraviolet detection. The parameters such as salt content, sample pH and temperature, stirring rate, extraction time, microdrop volume, and sample volume, were found to have significant influence on the HS-LPME. The conditions optimized for extraction of target compounds were as follows: 35% NaCl (w/v), neutral pH condition, 70
°C, 800
rpm, 30
min, 10
μL C
4MIMPF
6, and 25
mL sample solutions. Under the optimized conditions, the linear range, detection limit (S/N
=
3), and precision (R.S.D.,
n
=
6) were 0.3–30
μg
L
−1, 0.07
μg
L
−1, and 8.0% for
p,
p′-DDD, 0.3–30
μg
L
−1, 0.08
μg
L
−1, and 7.1% for
p,
p′-DDT, 0.3–30
μg
L
−1, 0.08
μg
L
−1, and 7.2% for
o,
p′-DDT, and 0.2–30
μg
L
−1, 0.05
μg
L
−1, and 6.8% for
p,
p′-DDE, respectively. Water samples including tap water, well water, snow water, reservoir water, and wastewater were analyzed by the proposed procedure and the recoveries at 5
μg
L
−1 spiked level were in the range of 86.8–102.6%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This paper is intended to review advances in the botanical, phytochemical, traditional uses and pharmacological studies of the genus
. Until now, 138 chemical constituents have been isolated and ...characterized from these plants, particularly from
and
. Among these compounds, lignans, triterpenoids, and flavonoids are the major bioactive constituents. Studies have shown that plants from the genus
exhibit an extensive range of pharmacological properties both in vivo and in vitro, including anti-inflammatory, analgesic, antitumor, antiviral and antibacterial activities. In Traditional Chinese Medicine (TCM) culture, drugs that include
stems have been used to cure rheumatism, gonarthritis, backache and pharyngitis, although there are few reports concerning the clinical use and toxicity of these plants. Further attention should be paid to gathering information about their toxicology data, quality-control measures, and the clinical value of the active compounds from genus
.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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