Composite antiferromagnetic and orbital order with altermagnetic properties at a cuprate/manganite interface.

Heterostructures from complex oxides allow one to combine various electronic and magnetic orders as to induce new quantum states. A prominent example is the coupling between superconducting and magnetic orders in multilayers from high-Tc cuprates and manganites. A key role is played here by the interfacial CuO2 layer whose distinct properties remain to be fully understood. Here, we study with resonant inelastic X-ray scattering the magnon excitations of this interfacial CuO2 layer. In particular, we show that the underlying antiferromagnetic exchange interaction at the interface is strongly suppressed to J≈70 meV, when compared with J≈130 meV for the CuO2 layers away from the interface. Moreover, we observe an anomalous momentum dependence of the intensity of the interfacial magnon mode and show that it suggests that the antiferromagnetic order is accompanied by a particular kind of orbital order that yields a so-called altermagnetic state. Such a 2D altermagnet has recently been predicted to enable new spintronic applications and superconducting proximity effects.

Genome-wide identification of GH28 family and insight into its contributions to pod shattering resistance in Brassica napus L.

Rapeseed (Brassica napus L.), accounts for nearly 16% of vegetable oil, is the world's second produced oilseed. However, pod shattering has caused significant yield loses in rapeseed production, particularly during mechanical harvesting. The GH28 genes can promote pod shattering by changing the structure of the pod cell wall in Arabidopsis. However, the role of the GH28 gene family in rapeseed was largely unknown. Therefore, a genome-wide comprehensive analysis was conducted to classify the role of GH28 gene family on rapeseed pod shattering. A total of 37 BnaGH28 genes in the rapeseed genome were identified. These BnaGH28s can be divided into five groups (Group A-E), based on phylogenetic and synteny analysis. Protein property, gene structure, conserved motif, cis-acting element, and gene expression profile of BnaGH28 genes in the same group were similar. Specially, the expression level of genes in group A-D was gradually decreased, but increased in group E with the development of silique. Among eleven higher expressed genes in group E, two BnaGH28 genes (BnaA07T0199500ZS and BnaC06T0206500ZS) were significantly regulated by IAA or GA treatment. And the significant effects of BnaA07T0199500ZS variation on pod shattering resistance were also demonstrated in present study. These results could open a new window for insight into the role of BnaGH28 genes on pod shattering resistance in rapeseed.

Trapped O2 and the origin of voltage fade in layered Li-rich cathodes.

Oxygen redox cathodes, such as Li1.2Ni0.13Co0.13Mn0.54O2, deliver higher energy densities than those based on transition metal redox alone. However, they commonly exhibit voltage fade, a gradually diminishing discharge voltage on extended cycling. Recent research has shown that, on the first charge, oxidation of O2- ions forms O2 molecules trapped in nano-sized voids within the structure, which can be fully reduced to O2- on the subsequent discharge. Here we show that the loss of O-redox capacity on cycling and therefore voltage fade arises from a combination of a reduction in the reversibility of the O2-/O2 redox process and O2 loss. The closed voids that trap O2 grow on cycling, rendering more of the trapped O2 electrochemically inactive. The size and density of voids leads to cracking of the particles and open voids at the surfaces, releasing O2. Our findings implicate the thermodynamic driving force to form O2 as the root cause of transition metal migration, void formation and consequently voltage fade in Li-rich cathodes.

Evolution of the Magnetic Excitations in Electron-Doped La_{2-x}Ce_{x}CuO_{4}.

We investigated the high energy spin excitations in electron-doped La_{2-x}Ce_{x}CuO_{4}, a cuprate superconductor, by resonant inelastic x-ray scattering (RIXS) measurements. Efforts were paid to disentangle the paramagnon signal from non-spin-flip spectral weight mixing in the RIXS spectrum at Q_{∥}=(0.6π,0) and (0.9π,0) along the (1 0) direction. Our results show that, for doping level x from 0.07 to 0.185, the variation of the paramagnon excitation energy is marginal. We discuss the implication of our results in connection with the evolution of the electron correlation strength in this system.

Collective Nature of Orbital Excitations in Layered Cuprates in the Absence of Apical Oxygens.

We have investigated the 3d orbital excitations in CaCuO_{2} (CCO), Nd_{2}CuO_{4} (NCO), and La_{2}CuO_{4} (LCO) using high-resolution resonant inelastic x-ray scattering. In LCO they behave as well-localized excitations, similarly to several other cuprates. On the contrary, in CCO and NCO the d_{xy} orbital clearly disperses, pointing to a collective character of this excitation (orbiton) in compounds without apical oxygen. We ascribe the origin of the dispersion as stemming from a substantial next-nearest-neighbor (NNN) orbital superexchange. Such an exchange leads to the liberation of the orbiton from its coupling to magnons, which is associated with the orbiton hopping between nearest neighbor copper sites. Finally, we show that the exceptionally large NNN orbital superexchange can be traced back to the absence of apical oxygens suppressing the charge transfer energy.

Weak signal extraction enabled by deep neural network denoising of diffraction data.

The removal or cancellation of noise has wide-spread applications in imaging and acoustics. In applications in everyday life, such as image restoration, denoising may even include generative aspects, which are unfaithful to the ground truth. For scientific use, however, denoising must reproduce the ground truth accurately. Denoising scientific data is further challenged by unknown noise profiles. In fact, such data will often include noise from multiple distinct sources, which substantially reduces the applicability of simulation-based approaches. Here we show how scientific data can be denoised by using a deep convolutional neural network such that weak signals appear with quantitative accuracy. In particular, we study X-ray diffraction and resonant X-ray scattering data recorded on crystalline materials. We demonstrate that weak signals stemming from charge ordering, insignificant in the noisy data, become visible and accurate in the denoised data. This success is enabled by supervised training of a deep neural network with pairs of measured low- and high-noise data. We additionally show that using artificial noise does not yield such quantitatively accurate results. Our approach thus illustrates a practical strategy for noise filtering that can be applied to challenging acquisition problems.

Genome-wide characterization of SDR gene family and its potential role in seed dormancy of Brassica napus L.

Rapeseed (Brassica napus L.) with short or no dormancy period are easy to germinate before harvest (pre-harvest sprouting, PHS). PHS has seriously decreased seed weight and oil content in B. napus. Short-chain dehydrogenase/ reductase (SDR) genes have been found to related to seed dormancy by promoting ABA biosynthesis in rice and Arabidopsis. In order to clarify whether SDR genes are the key factor of seed dormancy in B. napus, homology sequence blast, protein physicochemical properties, conserved motif, gene structure, cis-acting element, gene expression and variation analysis were conducted in present study. Results shown that 142 BnaSDR genes, unevenly distributed on 19 chromosomes, have been identified in B. napus genome. Among them, four BnaSDR gene clusters present in chromosome A04、A05、C03、C04 were also identified. These 142 BnaSDR genes were divided into four subfamilies on phylogenetic tree. Members of the same subgroup have similar protein characters, conserved motifs, gene structure, cis-acting elements and tissue expression profiles. Specially, the expression levels of genes in subgroup A, B and C were gradually decreased, but increased in subgroup D with the development of seeds. Among seven higher expressed genes in group D, six BnaSDR genes were significantly higher expressed in weak dormancy line than that in nondormancy line. And the significant effects of BnaC01T0313900ZS and BnaC03T0300500ZS variation on seed dormancy were also demonstrated in present study. These findings provide a key information for investigating the function of BnaSDRs on seed dormancy in B. napus.

Universal Stripe Symmetry of Short-Range Charge Density Waves in Cuprate Superconductors.

The omnipresence of charge density waves (CDWs) across almost all cuprate families underpins a common organizing principle. However, a longstanding debate of whether its spatial symmetry is stripe or checkerboard remains unresolved. While CDWs in lanthanum- and yttrium-based cuprates possess a stripe symmetry, distinguishing these two scenarios is challenging for the short-range CDW in bismuth-based cuprates. Here, high-resolution resonant inelastic x-ray scattering is employed to uncover the spatial symmetry of the CDW in Bi2 Sr2 - x Lax CuO6 + δ . Across a wide range of doping and temperature, anisotropic CDW peaks with elliptical shapes are found in reciprocal space. Based on Fourier transform analysis of real-space models, the results are interpreted as evidence of unidirectional charge stripes, hosted by mutually 90°-rotated anisotropic domains. This work paves the way for a unified symmetry and microscopic description of CDW order in cuprates.

Signature of quantum criticality in cuprates by charge density fluctuations.

The universality of the strange metal phase in many quantum materials is often attributed to the presence of a quantum critical point (QCP), a zero-temperature phase transition ruled by quantum fluctuations. In cuprates, where superconductivity hinders direct QCP observation, indirect evidence comes from the identification of fluctuations compatible with the strange metal phase. Here we show that the recently discovered charge density fluctuations (CDF) possess the right properties to be associated to a quantum phase transition. Using resonant x-ray scattering, we studied the CDF in two families of cuprate superconductors across a wide doping range (up to p = 0.22). At p* ≈ 0.19, the putative QCP, the CDF intensity peaks, and the characteristic energy Δ is minimum, marking a wedge-shaped region in the phase diagram indicative of a quantum critical behavior, albeit with anomalies. These findings strengthen the role of charge order in explaining strange metal phenomenology and provide insights into high-temperature superconductivity.

The expression and prognostic value of disulfidptosis progress in lung adenocarcinoma.

Disulfidptosis is a new cell death model caused by accumulating intracellular disulfides bonding to actin cytoskeleton proteins. This study aimed to investigate the expression and prognostic value of disulfidptosis-related genes (DRGs) in lung adenocarcinoma (LUAD). The data of expression profiles and scRNA-seq were collected from TCGA and GEO databases. The different expressions of DRGs between normal and LUAD tissues were compared. The LASSO analysis and multivariate Cox regression analysis were utilized to develop a DRGs model for the prognosis evaluation in LUAD. The model's predictive accuracy was evaluated with the area under the receiver operating characteristic curve (AUC) and C-index. Survival analysis, univariate and multivariate Cox regression analysis were used to assessing the predictive value of the DRGs model. ScRNA-seq data were analyzed with "Seurat" and "Monocle 2" packages. There were significant differences in 22 DRGs between normal and tumor tissues. A model with five DRGs (ACTB, FLNB, NCKAP1, SLC3A2, SLC7A11) was constructed. The AUC and C-index of the model were significantly higher than that based on clinical parameters. Survival analysis, univariate and multivariate Cox regression analysis demonstrated risk score was an independent prognostic predictor. In the scRNA-seq study, we identified 14 clusters and 11 cell types. Clusters 2, 8, and 13 were annotated into Epithelial cells. SLC7A11 and SLC3A2, NCKAP1 and FLNB, ACTB expressed most abundantly in Epithelial cells, Endothelial cells, Naive CD4 T, respectively. We explored the expression of DRGs in LUAD and constructed a predictive DRGs model, which was stable and reliable for predicting LUAD prognosis.

Low-energy quasi-circular electron correlations with charge order wavelength in Bi2Sr2CaCu2O8+δ.

Most resonant inelastic x-ray scattering (RIXS) studies of dynamic charge order correlations in the cuprates have focused on the high-symmetry directions of the copper oxide plane. However, scattering along other in-plane directions should not be ignored as it may help understand, for example, the origin of charge order correlations or the isotropic scattering resulting in strange metal behavior. Our RIXS experiments reveal dynamic charge correlations over the qx-qy scattering plane in underdoped Bi2Sr2CaCu2O8+δ. Tracking the softening of the RIXS-measured bond-stretching phonon, we show that these dynamic correlations exist at energies below approximately 70 meV and are centered around a quasi-circular manifold in the qx-qy scattering plane with radius equal to the magnitude of the charge order wave vector, qCO. This phonon-tracking procedure also allows us to rule out fluctuations of short-range directional charge order (i.e., centered around [qx = ±qCO, qy = 0] and [qx = 0, qy = ±qCO]) as the origin of the observed correlations.

Chiral phonons in quartz probed by X-rays.

The concept of chirality is of great relevance in nature, from chiral molecules such as sugar to parity transformations in particle physics. In condensed matter physics, recent studies have demonstrated chiral fermions and their relevance in emergent phenomena closely related to topology1-3. The experimental verification of chiral phonons (bosons) remains challenging, however, despite their expected strong impact on fundamental physical properties4-6. Here we show experimental proof of chiral phonons using resonant inelastic X-ray scattering with circularly polarized X-rays. Using the prototypical chiral material quartz, we demonstrate that circularly polarized X-rays, which are intrinsically chiral, couple to chiral phonons at specific positions in reciprocal space, allowing us to determine the chiral dispersion of the lattice modes. Our experimental proof of chiral phonons demonstrates a new degree of freedom in condensed matter that is both of fundamental importance and opens the door to exploration of new emergent phenomena based on chiral bosons.

Magnetic excitations beyond the single- and double-magnons.

A photon carrying one unit of angular momentum can change the spin angular momentum of a magnetic system with one unit (ΔMs = ±1) at most. This implies that a two-photon scattering process can manipulate the spin angular momentum of the magnetic system with a maximum of two units. Herein we describe a triple-magnon excitation in α-Fe2O3, which contradicts this conventional wisdom that only 1- and 2-magnon excitations are possible in a resonant inelastic X-ray scattering experiment. We observe an excitation at exactly three times the magnon energy, along with additional excitations at four and five times the magnon energy, suggesting quadruple and quintuple-magnons as well. Guided by theoretical calculations, we reveal how a two-photon scattering process can create exotic higher-rank magnons and the relevance of these quasiparticles for magnon-based applications.

Critical role of hydrogen for superconductivity in nickelates.

The newly discovered nickelate superconductors so far only exist in epitaxial thin films synthesized by a topotactic reaction with metal hydrides1. This method changes the nickelates from the perovskite to an infinite-layer structure by deintercalation of apical oxygens1-3. Such a chemical reaction may introduce hydrogen (H), influencing the physical properties of the end materials4-9. Unfortunately, H is insensitive to most characterization techniques and is difficult to detect because of its light weight. Here, in optimally Sr doped Nd0.8Sr0.2NiO2H epitaxial films, secondary-ion mass spectroscopy shows abundant H existing in the form of Nd0.8Sr0.2NiO2Hx (x ≅ 0.2-0.5). Zero resistivity is found within a very narrow H-doping window of 0.22 ≤ x ≤ 0.28, showing unequivocally the critical role of H in superconductivity. Resonant inelastic X-ray scattering demonstrates the existence of itinerant interstitial s (IIS) orbitals originating from apical oxygen deintercalation. Density functional theory calculations show that electronegative H- occupies the apical oxygen sites annihilating IIS orbitals, reducing the IIS-Ni 3d orbital hybridization. This leads the electronic structure of H-doped Nd0.8Sr0.2NiO2Hx to be more two-dimensional-like, which might be relevant for the observed superconductivity. We highlight that H is an important ingredient for superconductivity in epitaxial infinite-layer nickelates.

Sodium hydrosulfide alleviates aluminum toxicity in Brassica napus through maintaining H2S, ROS homeostasis and enhancing aluminum exclusion.

Hydrogen sulfide (H2S) is a gaseous mediator that plays versatile roles in plant growth and stress responses. However, the regulatory functions of H2S in plant responses to aluminum (Al) stress remain elusive. We observed that application of 20 µM of NaHS (H2S donor) or 0.2 mM of hypotaurine (HT, H2S scavenger) significantly mitigated the inhibition of rapeseed root growth caused by Al stress (150 µM). Exposure to Al for 6 h induced significant H2S accumulation and high levels were maintained thereafter, owing to the elevation of cysteine (83.73 %), L-cysteine desulfhydrase (LCD, 92.32 %), and cyanoalanine synthase (CAS, 11.23 %), and the inhibition of O-Acetyl-l-serine (thiol) lyase (OAS-TL, 15.13 %). Addition of HT significantly scavenged the prolonged H2S accumulation caused by Al stress. Exogenous NaHS maintained the H2S homeostasis through increasing OAS-TL activity (34.99 %) and inhibiting LCD activity (25.72 %), and cysteine level (39.53 %). Moreover, exogenous NaHS mitigated oxidative damage by enhancing antioxidant enzyme activity (SOD 26.27 %, POD 28.62 %, CAT 400.5 % and APX 92.68 %) and proline content (19.85 %). It also decreased root cell wall Al accumulation (20.52 %) by decreasing PME activity (24.64 %) and facilitating pectin methylation (16.74 %). Similar alleviative effects were observed when HT was added. These results suggest that H2S functions differential roles in Al stress response in rapeseed seedlings, depending on its local concentration and duration. Prolonged high H2S emissions might contribute to Al toxicity, while moderate exogenous H2S improves Al tolerance through controlling H2S and ROS accumulation and enhancing Al exclusion through replenishing antioxidant reservoirs and facilitating pectin methylation. It is therefore important that further study investigates how to orchestrate endogenous H2S levels and improve plant stress tolerance.

Correlation driven near-flat band Stoner excitations in a Kagome magnet.

Among condensed matter systems, Mott insulators exhibit diverse properties that emerge from electronic correlations. In itinerant metals, correlations are usually weak, but can also be enhanced via geometrical confinement of electrons, that manifest as 'flat' dispersionless electronic bands. In the fast developing field of topological materials, which includes Dirac and Weyl semimetals, flat bands are one of the important components that can result in unusual magnetic and transport behaviour. To date, characterisation of flat bands and their magnetism is scarce, hindering the design of novel materials. Here, we investigate the ferromagnetic Kagomé semimetal Co3Sn2S2 using resonant inelastic X-ray scattering. Remarkably, nearly non-dispersive Stoner spin excitation peaks are observed, sharply contrasting with the featureless Stoner continuum expected in conventional ferromagnetic metals. Our band structure and dynamic spin susceptibility calculations, and thermal evolution of the excitations, confirm the nearly non-dispersive Stoner excitations as unique signatures of correlations and spin-polarized electronic flat bands in Co3Sn2S2. These observations serve as a cornerstone for further exploration of band-induced symmetry-breaking orders in topological materials.

Lipid Nanoparticle (LNP) Chemistry Can Endow Unique In Vivo RNA Delivery Fates within the Liver That Alter Therapeutic Outcomes in a Cancer Model.

Within the field of lipid nanoparticles (LNPs) for RNA delivery, the focus has been mainly placed on organ level delivery, which can mask cellular level effects consequential to therapeutic applications. Here, we studied a pair of LNPs with similar physical properties and discovered how the chemistry of the ionizable amino lipid can control the endogenous LNP identity, affecting cellular uptake in the liver and altering therapeutic outcomes in a model of liver cancer. Although most LNPs accumulate in the liver after intravenous administration (suggesting that liver delivery is straightforward), we observed an unexpected behavior when comparing two similar LNP formulations (5A2-SC8 and 3A5-SC14 LNPs) that resulted in distinct RNA delivery within the organ. Despite both LNPs possessing similar physical properties, ability to silence gene expression in vitro, strong accumulation within the liver, and a shared pKa of 6.5, only 5A2-SC8 LNPs were able to functionally deliver RNA to hepatocytes. Factor VII (FVII) activity was reduced by 87%, with 5A2-SC8 LNPs carrying FVII siRNA (siFVII), while 3A5-SC14 LNPs carrying siFVII produced baseline FVII activity levels comparable to the nontreatment control at a dosage of 0.5 mg/kg. Protein corona analysis indicated that 5A2-SC8 LNPs bind apolipoprotein E (ApoE), which can drive LDL-R receptor-mediated endocytosis in hepatocytes. In contrast, the surface of 3A5-SC14 LNPs was enriched in albumin but depleted in ApoE, which likely led to Kupffer cell delivery and detargeting of hepatocytes. In an aggressive MYC-driven liver cancer model relevant to hepatocytes, 5A2-SC8 LNPs carrying let-7g miRNA were able to significantly extend survival up to 121 days. Since disease targets exist in an organ- and cell-specific manner, the clinical development of RNA LNP therapeutics will require an improved understanding of LNP cellular tropism within organs. The results from our work illustrate the importance of understanding the cellular localization of RNA delivery and incorporating further checkpoints when choosing nanoparticles beyond biochemical and physical characterization, as small changes in the chemical composition of LNPs can have an impact on both the biofate of LNPs and therapeutic outcomes.

Gapped Collective Charge Excitations and Interlayer Hopping in Cuprate Superconductors.

We use resonant inelastic x-ray scattering to probe the propagation of plasmons in the electron-doped cuprate superconductor Sr_{0.9}La_{0.1}CuO_{2}. We detect a plasmon gap of ∼120 meV at the two-dimensional Brillouin zone center, indicating that low-energy plasmons in Sr_{0.9}La_{0.1}CuO_{2} are not strictly acoustic. The plasmon dispersion, including the gap, is accurately captured by layered t-J-V model calculations. A similar analysis performed on recent resonant inelastic x-ray scattering data from other cuprates suggests that the plasmon gap is generic and its size is related to the magnitude of the interlayer hopping t_{z}. Our work signifies the three dimensionality of the charge dynamics in layered cuprates and provides a new method to determine t_{z}.

Charge density waves in infinite-layer NdNiO2 nickelates.

In materials science, much effort has been devoted to the reproduction of superconductivity in chemical compositions, analogous to cuprate superconductors since their discovery over 30 years ago. This approach was recently successful in realising superconductivity in infinite-layer nickelates1-6. Although differing from cuprates in electronic and magnetic properties, strong Coulomb interactions suggest that infinite-layer nickelates have a propensity towards various symmetry-breaking orders that populate cuprates7-10. Here we report the observation of charge density waves (CDWs) in infinite-layer NdNiO2 films using Ni L3 resonant X-ray scattering. Remarkably, CDWs form in Nd 5d and Ni 3d orbitals at the same commensurate wavevector (0.333, 0) reciprocal lattice units, with non-negligible out-of-plane dependence and an in-plane correlation length of up to ~60 Å. Spectroscopic studies reveal a strong connection between CDWs and Nd 5d-Ni 3d orbital hybridization. Upon entering the superconducting state at 20% Sr doping, the CDWs disappear. Our work demonstrates the existence of CDWs in infinite-layer nickelates with a multiorbital character distinct from cuprates, which establishes their low-energy physics.