In Situ Formation of SnSe2/SnSe Vertical Heterostructures toward Polarization Selectable Band Alignments.

2D van der Waals (vdW) layered semiconductor vertical heterostructures with controllable band alignment are highly desired for nanodevice applications including photodetection and photovoltaics. However, current 2D vdW heterostructures are mainly obtained via mechanical exfoliation and stacking process, intrinsically limiting the yield and reproducibility, hardly achieving large-area with specific orientation. Here, large-area vdW-epitaxial SnSe2/SnSe heterostructures are obtained by annealing layered SnSe. These in situ Raman analyses reveal the optimized annealing conditions for the phase transition of SnSe to SnSe2. The spherical aberration-corrected transmission electron microscopy investigations demonstrate that layered SnSe2 epitaxially forms on SnSe surface with atomically sharp interface and specific orientation. Optical characterizations and theoretical calculations reveal valley polarization of the heterostructures that originate from SnSe, suggesting a naturally adjustable band alignment between type-II and type-III, only relying on the polarization angle of incident lights. This work not only offers a unique and accessible approach to obtaining large-area SnSe2/SnSe heterostructures with new insight into the formation mechanism of vdW heterostructures, but also opens the intriguing optical applications based on valleytronic nanoheterostructures.

Coupled hydraulics and carbon economy underlie age-related growth decline and revitalisation of sand-fixing shrubs after crown removal.

Crown removal revitalises sand-fixing shrubs that show declining vigour with age in drought-prone environments; however, the underlying mechanisms are poorly understood. Here, we addressed this knowledge gap by comparing the growth performance, xylem hydraulics and plant carbon economy across different plant ages (10, 21 and 33 years) and treatments (control and crown removal) using a representative sand-fixing shrub (Caragana microphylla Lam.) in northern China. We found that growth decline with plant age was accompanied by simultaneous decreases in soil moisture, plant hydraulic efficiency and photosynthetic capacity, suggesting that these interconnected changes in plant water relations and carbon economy were responsible for this decline. Following crown removal, quick resprouting, involving remobilisation of root nonstructural carbohydrate reserves, contributed to the reconstruction of an efficient hydraulic system and improved plant carbon status, but this became less effective in older shrubs. These age-dependent effects of carbon economy and hydraulics on plant growth vigour provide a mechanistic explanation for the age-related decline and revitalisation of sand-fixing shrubs. This understanding is crucial for the development of suitable management strategies for shrub plantations constructed with species having the resprouting ability and contributes to the sustainability of ecological restoration projects in water-limited sandy lands.

E3 ubiquitin ligase UBR5 modulates circadian rhythm by facilitating the ubiquitination and degradation of the key clock transcription factor BMAL1.

The circadian clock is the inner rhythm of life activities and is controlled by a self-sustained and endogenous molecular clock, which maintains a ~ 24 h internal oscillation. As the core element of the circadian clock, BMAL1 is susceptible to degradation through the ubiquitin-proteasome system (UPS). Nevertheless, scant information is available regarding the UPS enzymes that intricately modulate both the stability and transcriptional activity of BMAL1, affecting the cellular circadian rhythm. In this work, we identify and validate UBR5 as a new E3 ubiquitin ligase that interacts with BMAL1 by using affinity purification, mass spectrometry, and biochemical experiments. UBR5 overexpression induced BMAL1 ubiquitination, leading to diminished stability and reduced protein level of BMAL1, thereby attenuating its transcriptional activity. Consistent with this, UBR5 knockdown increases the BMAL1 protein. Domain mapping discloses that the C-terminus of BMAL1 interacts with the N-terminal domains of UBR5. Similarly, cell-line-based experiments discover that HYD, the UBR5 homolog in Drosophila, could interact with and downregulate CYCLE, the BMAL1 homolog in Drosophila. PER2-luciferase bioluminescence real-time reporting assay in a mammalian cell line and behavioral experiments in Drosophila reveal that UBR5 or hyd knockdown significantly reduces the period of the circadian clock. Therefore, our work discovers a new ubiquitin ligase UBR5 that regulates BMAL1 stability and circadian rhythm and elucidates the underlying molecular mechanism. This work provides an additional layer of complexity to the regulatory network of the circadian clock at the post-translational modification level, offering potential insights into the modulation of the dysregulated circadian rhythm.

Magnetic and Ferroelectric Manipulation of Valley Physics in Janus Piezoelectric Materials.

The realization of multiferroic materials offers the possibility of multifunctional electronic device design. However, the coupling between the multiferroicity and piezoelectricity in Janus materials is rarely reported. In this study, we propose a mechanism for manipulating valley physics by magnetization reversing and ferroelectric switching in multiferroic and piezoelectric material. The ferromagnetic VSiGeP4 monolayer exhibits a large valley polarization up to 100 meV, which can be effectively operated by reversing magnetization. Interestingly, the antiferromagnetic VSiGeP4 bilayers with AB and BA stacking configurations allow the coexistence of valley polarization and ferroelectricity, supporting the proposed strategy for manipulating valley physics via ferroelectric switching and interlayer sliding. In addition, the VSiGeP4 monolayer contains remarkable tunable piezoelectricity regulated by electron correlation U. This study proposes a feasible idea for regulating valley polarization and a general design idea for multifunctional devices with multiferroic and piezoelectric properties, facilitating the miniaturization and integration of nanodevices.

Highly Conductive Topologically Chiral Molecular Knots as Efficient Spin Filters.

Knot-like structures were found to have interesting magnetic properties in condensed matter physics. Herein, we report on topologically chiral molecular knots as efficient spintronic chiral material. The discovery of the chiral-induced spin selectivity (CISS) effect opens the possibility of manipulating the spin orientation with soft materials at room temperature and eliminating the need for a ferromagnetic electrode. In the chiral molecular trefoil knot, there are no stereogenic carbon atoms, and chirality results from the spatial arrangements of crossings in the trefoil knot structures. The molecules show a very high spin polarization of nearly 90%, a conductivity that is higher by about 2 orders of magnitude compared with that of other chiral small molecules, and enhanced thermal stability. A plausible explanation for these special properties is provided, combined with model calculations, that supports the role of electron-electron interaction in these systems.

Xylem hydraulics strongly influence the niche differentiation of tree species along the slope of a river valley in a water-limited area.

Xylem hydraulic characteristics govern plant water transport, affecting both drought resistance and photosynthetic gas exchange. Therefore, they play critical roles in determining the adaptation of different species to environments with various water regimes. Here, we tested the hypothesis that variation in xylem traits associated with a trade-off between hydraulic efficiency and safety against drought-induced embolism contributes to niche differentiation of tree species along a sharp water availability gradient on the slope of a unique river valley located in a semi-humid area. We found that tree species showed clear niche differentiation with decreasing water availability from the bottom towards the top of the valley. Tree species occupying different positions, in terms of vertical distribution distance from the bottom of the valley, showed a strong trade-off between xylem water transport efficiency and safety, as evidenced by variations in xylem structural traits at both the tissue and pit levels. This optimized their xylem hydraulics in their respective water regimes. Thus, the trade-off between hydraulic efficiency and safety contributes to clear niche differentiation and, thereby, to the coexistence of tree species in the valley with heterogeneous water availability.

Early autoimmunity and outcome in virus encephalitis: a retrospective study based on tissue-based assay.

To explore the autoimmune response and outcome in the central nervous system (CNS) at the onset of viral infection and correlation between autoantibodies and viruses. METHODS: A retrospective observational study was conducted in 121 patients (2016-2021) with a CNS viral infection confirmed via cerebrospinal fluid (CSF) next-generation sequencing (cohort A). Their clinical information was analysed and CSF samples were screened for autoantibodies against monkey cerebellum by tissue-based assay. In situ hybridisation was used to detect Epstein-Barr virus (EBV) in brain tissue of 8 patients with glial fibrillar acidic protein (GFAP)-IgG and nasopharyngeal carcinoma tissue of 2 patients with GFAP-IgG as control (cohort B). RESULTS: Among cohort A (male:female=79:42; median age: 42 (14-78) years old), 61 (50.4%) participants had detectable autoantibodies in CSF. Compared with other viruses, EBV increased the odds of having GFAP-IgG (OR 18.22, 95% CI 6.54 to 50.77, p<0.001). In cohort B, EBV was found in the brain tissue from two of eight (25.0%) patients with GFAP-IgG. Autoantibody-positive patients had a higher CSF protein level (median: 1126.00 (281.00-5352.00) vs 700.00 (76.70-2899.00), p<0.001), lower CSF chloride level (mean: 119.80±6.24 vs 122.84±5.26, p=0.005), lower ratios of CSF-glucose/serum-glucose (median: 0.50[0.13-0.94] vs 0.60[0.26-1.23], p=0.003), more meningitis (26/61 (42.6%) vs 12/60 (20.0%), p=0.007) and higher follow-up modified Rankin Scale scores (1 (0-6) vs 0 (0-3), p=0.037) compared with antibody-negative patients. A Kaplan-Meier analysis revealed that autoantibody-positive patients experienced significantly worse outcomes (p=0.031). CONCLUSIONS: Autoimmune responses are found at the onset of viral encephalitis. EBV in the CNS increases the risk for autoimmunity to GFAP.

Mechanical Polarization Switching in Hf0.5Zr0.5O2 Thin Film.

HfO2-based films with high compatibility with Si and complementary metal-oxide semiconductors (CMOS) have been widely explored in recent years. In addition to ferroelectricity and antiferroelectricity, flexoelectricity, the coupling between polarization and a strain gradient, is rarely reported in HfO2-based films. Here, we demonstrate that the mechanically written out-of-plane domains are obtained in 10 nm Hf0.5Zr0.5O2 (HZO) ferroelectric film at room temperature by generating the stress gradient via the tip of an atomic force microscope. The results of scanning Kelvin force microscopy (SKPM) exclude the possibility of flexoelectric-like mechanisms and prove that charge injection could be avoided by mechanical writing and thus reveal the true polarization state, promoting wider flexoelectric applications and ultrahigh-density storage of HZO thin films.

Presence of Delocalized Ti 3d Electrons in Ultrathin Single-Crystal SrTiO3.

Strontium titanate (STO), with a wide spectrum of emergent properties such as ferroelectricity and superconductivity, has received significant attention in the community of strongly correlated materials. In the strain-free STO film grown on the SrRuO3 buffer layer, the existing polar nanoregions can facilitate room-temperature ferroelectricity when the STO film thickness approaches 10 nm. Here we show that around this thickness scale, the freestanding STO films without the influence of a substrate show the tetragonal structure at room temperature, contrasting with the cubic structure seen in bulk form. The spectroscopic measurements reveal the modified Ti-O orbital hybridization that causes the Ti ion to deviate from its nominal 4+ valency (3d0 configuration) with excess delocalized 3d electrons. Additionally, the Ti ion in TiO6 octahedron exhibits an off-center displacement. The inherent symmetry lowering in ultrathin freestanding films offers an alternative way to achieve tunable electronic structures that are of paramount importance for future technological applications.

Pericytes Regulate Cerebral Perfusion through VEGFR1 in Ischemic Stroke.

Neurons in the penumbra (the area surrounding ischemic tissue that consists of still viable tissue but with reduced blood flow and oxygen transport) may be rescued following stroke if adequate perfusion is restored in time. It has been speculated that post-stroke angiogenesis in the penumbra can reduce damage caused by ischemia. However, the mechanism for neovasculature formation in the brain remains unclear and vascular-targeted therapies for brain ischemia remain suboptimal. Here, we show that VEGFR1 was highly upregulated in pericytes after stroke. Knockdown of VEGFR1 in pericytes led to increased infarct area and compromised post-ischemia vessel formation. Furthermore, in vitro studies confirmed a critical role for pericyte-derived VEGFR1 in both endothelial tube formation and pericyte migration. Interestingly, our results show that pericyte-derived VEGFR1 has opposite effects on Akt activity in endothelial cells and pericytes. Collectively, these results indicate that pericyte-specific expression of VEGFR1 modulates ischemia-induced vessel formation and vascular integrity in the brain.

Characteristics of the gut microbiota in pregnant women with fetal growth restriction.

BACKGROUND: Fetal growth restriction (FGR) in utero leads to failure of fetus to reach the genetically normal growth potential. Currently available means of treating FGR are limited. And it remains unknown how pregnant women who give birth to FGR fetus differ in gut microbiota composition from normal pregnant women. METHODS: In this case-control study, fecal samples were obtained from maternal rectum in the operation room by an obstetrician under strict aseptic conditions. We compared gut microbiota of 14 pregnant women with FGR and 18 normal controls by performing 16S rDNA amplicon sequencing. RESULTS: We identified significant differences in ß-diversity between the FGR and control groups (P < 0.05). At genus level, Bacteroides, Faecalibacterium and Lachnospira were highly abundant in the FGR subjects, which are significantly enriched in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to glycometabolism. CONCLUSION: These findings demonstrated that the distinct composition of the gut microbiota between FGR and normal pregnant women could contribute to an improved understanding of the prevention and treatment of FGR.

LncRNA SLC16A1-AS1 contributes to the progression of hepatocellular carcinoma cells by modulating miR-411/MITD1 axis.

BACKGROUND: Hepatocellular carcinoma (HCC) is a common malignancy with high morbidity. The current study aimed to explore the molecular mechanism of lncRNA SLC16A1-AS1 in the tumorigenesis of HCC. MATERIAL AND METHODS: The expression of SLC16A1-AS1 and miR-411 was examined in clinical HCC tissues. HCC cell lines Hep3B and Huh-7 were employed and transfected with si-SLC16A1-AS1. The correlation between SLC16A1-AS1 and miR-411 was verified by luciferase reporter assay. Cell viability was detected by CCK-8 assay. Cell migration and invasion capacity were examined by transwell assay. The protein level of MITD1 was analyzed by western blotting. RESULTS: The expression of SLC16A1-AS1 markedly increased in HCC tissues and cell lines. Subsequent studies identified SLC16A1-AS1 as a downstream target of miR-411. In addition, SLC16A1-AS1 knockdown and miR-411 overexpression significantly stagnated the progression of HCC cells. SLC16A1-AS1 knockdown also downregulated MITD1 levels. CONCLUSION: Our findings showed that SLC16A1-AS1 was overexpressed in HCC cells and tissues. SLC16A1-AS1 promoted the malignant characteristics of HCC cells and acted as an oncogene. Its regulatory effect may be associated with miR-411/MITD1 axis. Therefore, SLC16A1-AS1 has the potential to be used as a biomarker or therapeutic target for the treatment of HCC.

Increased Circulating Osteoprotegerin Levels in Type 1 Diabetes Mellitus: A Systematic Review and Meta-analysis Based on Observational Studies.

Objectives: Type 1 diabetes mellitus (T1D) has been disclosed to be associated with an elevated risk of cardiovascular disease (CVD), as well as increased risks of losing bone mass and progression of osteoporosis (OP). Osteoprotegerin (OPG), as a decoy receptor, has been demonstrated to play a critical role in bone metabolism homeostasis and vascular atherosclerotic diseases. This meta-analysis aimed to investigate the associations between OPG levels and T1D. Methods: Related literatures were searched and identified from the database of the Cochrane Library database, PubMed and EMbase inception to August 3, 2019 in English. The pooled standard mean difference (SMD) with its 95% confidence interval (CI) was calculated in using random-effect model analysis. Chi-square Q statistic and I2 test were performed to evaluate and quantified the presence of heterogeneity. Results: Twelve studies with 1288 subjects (794 T1D patients and 494 healthy controls) were finally included. The incorporated results indicated that T1D patients have higher plasma/serum OPG levels than in healthy individuals (SMD = 0.64, 95% CI: 0.06, 1.22). Subgroup analyses suggested that Caucasian and glycosylated hemoglobin A1c (HbA1c) <8.5% groups showed higher OPG levels, however, there was no significant differences of OPG levels regarding subgroups of BMI ≥ or <25, children-adolescents or adults and HbA1c ≥8.5%. Conclusions: The current evidence suggested that circulating OPG levels are significantly higher in T1D than in healthy controls, and the increase of OPG levels are influenced by factors of race and HbA1c.

Strain-engineering on GeSe: Raman spectroscopy study.

Among the IV-VI compounds, GeSe has wide applications in nanoelectronics due to its unique photoelectric properties and adjustable band gap. Even though modulation of its physical characteristics, including the band gap, by an external field will be useful for designing novel devices, experimental work is still rare. Here, we report a detailed anisotropic Raman response of GeSe flakes under uniaxial tension strain. Based on theoretical analysis, the anisotropy of the phonon response is attributed to a change in anisotropic bond length and bond angle under in-plane uniaxial strain. An enhancement in anisotropy and band gap is found due to strain along the ZZ or AC directions. This study shows that strain-engineering is an effective method for controlling the GeSe lattice, and paves the way for modulating the anisotropic electric and optical properties of GeSe.

Electrically induced 2D half-metallic antiferromagnets and spin field effect transistors.

Engineering the electronic band structure of material systems enables the unprecedented exploration of new physical properties that are absent in natural or as-synthetic materials. Half metallicity, an intriguing physical property arising from the metallic nature of electrons with singular spin polarization and insulating for oppositely polarized electrons, holds a great potential for a 100% spin-polarized current for high-efficiency spintronics. Conventionally synthesized thin films hardly sustain half metallicity inherited from their 3D counterparts. A fundamental challenge, in systems of reduced dimensions, is the almost inevitable spin-mixed edge or surface states in proximity to the Fermi level. Here, we predict electric field-induced half metallicity in bilayer A-type antiferromagnetic van der Waals crystals (i.e., intralayer ferromagnetism and interlayer antiferromagnetism), by employing density functional theory calculations on vanadium diselenide. Electric fields lift energy levels of the constituent layers in opposite directions, leading to the gradual closure of the gap of singular spin-polarized states and the opening of the gap of the others. We show that a vertical electrical field is a generic and effective way to achieve half metallicity in A-type antiferromagnetic bilayers and realize the spin field effect transistor. The electric field-induced half metallicity represents an appealing route to realize 2D half metals and opens opportunities for nanoscale highly efficient antiferromagnetic spintronics for information processing and storage.

Current Situation of Methamphetamine Abuse and Related Research Progress.

Drug problem is a major social and public security problem in the world. Drug abuse poses a great threat to economic development, social stability and public health. In recent years, synthetic drugs represented by methamphetamine have surpassed traditional drugs such as morphine, heroin, ketamine and become one of the most abused drugs in the world. In order to solve the problem of drug abuse, it is of great theoretical value and practical significance to carry out all-round and multi-level scientific research on drug-related issues. Based on the current situation of drug abuse, this article reviews research progresses on the epidemiology of methamphetamine abuse, the monitoring technology, the basic researches on toxicity damage, the withdrawal drug screening, the related clinical comorbidity and the testing technologies, comprehensively presenting the development trend of methamphetamine abuse related issues.

Fluorescent Recognition of 4-Amino-2,6-dinitrotoluene by a Cerium-Based Metal-Organic Tetrahedron.

A cerium-based metal-organic tetrahedron has been developed as a highly selective and sensitive fluorescence sensor for the recognition of 4-amino-2,6-dinitrotoluene (4-ADNT). The redox-active tetrahedron could encapsulate 4-ADNT through weak interaction and spatial stereoselectivity, resulting in an enhanced fluorescence. The tetrahedral sensor Ce-ZPS is capable of realizing fluorescent sensing in urine and in cells and thus has the potential to detect 4-ADNT in organisms.

Ultra-wide temperature electronic synapses based on self-rectifying ferroelectric memristors.

Memristors have been intensively studied in recent years as promising building blocks for next-generation nonvolatile memory, artificial neural networks and brain-inspired computing systems. However, most memristors cannot simultaneously function in extremely low and high temperatures, limiting their use for many harsh environment applications. Here, we demonstrate that the memristors based on high-Curie temperature ferroelectrics can resolve these issues. Excellent synaptic learning and memory functions can be achieved in BiFeO3 (BFO)-based ferroelectric memristors in an ultra-wide temperature range. Correlation between electronic transport and ferroelectric properties is established by the coincidence of resistance and ferroelectricity switch and the direct visualization of local current and domain distributions. The interfacial barrier modification by the reversal of ferroelectric polarization leads to a robust resistance switching behavior. Various synaptic functions including long-term potentiation/depression, consecutive potentiation/depression and spike-timing dependent plasticity have been realized in the BFO ferroelectric memristors over an extremely wide temperature range of -170 °C âˆ¼ 300 °C, which even can be extended to 500 °C due to the robust ferroelectricity of BFO at high temperatures. Our findings illustrate that the BFO ferroelectric memristors are promising candidates for ultra-wide temperature electronic synapse in extreme or harsh environments.

Ultrafast Giant Photostriction of Epitaxial Strontium Iridate Film with Superior Endurance.

Photostriction, optical stimulus driven mechanical deformation in materials, provides a solution toward next-generation technology. Here, the giant photostriction (∼2% change of lattice) of epitaxial strontium iridate (SrIrO3) films under illumination at room temperature is revealed via power-dependent Raman scattering, which is significantly larger as compared to conventional inorganic materials. The time scale and mechanism of this giant photostriction in SrIrO3 are further studied through time-resolved transient reflectivity measurements. The main mechanism is determined to be the electron-phonon coupling. In addition, we find that such an exotic behavior happens within few picoseconds and remains up to 107 cyclic on/off operations. The observation of giant photostriction in SrIrO3 films with superior endurance promises the advance of shape responsive solids that are sensitive to environmental stimuli, which could be widely utilized for multifunctional optoelectronics and optomechanical devices.