Enhanced interactions of interlayer excitons in free-standing heterobilayers.

Strong, long-range dipole-dipole interactions between interlayer excitons (IXs) can lead to new multiparticle correlation regimes1,2, which drive the system into distinct quantum and classical phases2-5, including dipolar liquids, crystals and superfluids. Both repulsive and attractive dipole-dipole interactions have been theoretically predicted between IXs in a semiconductor bilayer2,6-8, but only repulsive interactions have been reported experimentally so far3,9-16. This study investigated free-standing, twisted (51°, 53°, 45°) tungsten diselenide/tungsten disulfide (WSe2/WS2) heterobilayers, in which we observed a transition in the nature of dipolar interactions among IXs, from repulsive to attractive. This was caused by quantum-exchange-correlation effects, leading to the appearance of a robust interlayer biexciton phase (formed by two IXs), which has been theoretically predicted6-8 but never observed before in experiments. The reduced dielectric screening in a free-standing heterobilayer not only resulted in a much higher formation efficiency of IXs, but also led to strongly enhanced dipole-dipole interactions, which enabled us to observe the many-body correlations of pristine IXs at the two-dimensional quantum limit. In addition, we firstly observed several emission peaks from moiré-trapped IXs at room temperature in a well-aligned, free-standing WSe2/WS2 heterobilayer. Our findings open avenues for exploring new quantum phases with potential for applications in non-linear optics.

Thiacalix[4]arene Etching of an Anisotropic Cu70H22 Intermediate for Accessing Robust Modularly Assembled Copper Nanoclusters.

Atom-precise metal nanoclusters (NCs) with large bulk (nuclearity >60) are important species for insight into the embryonic phase of metal nanoparticles and their top-down etching synthesis. Herein, we report a metastable rod-shaped 70-nuclei copper-hydride NC, [Cl@Cu70H22(PhC≡C)29(CF3COO)16]2+ (Cu70), with Cl- as the template, in which the Cl@Cu59 kernel adopts a distinctive metal packing mode along the bipolar direction, and the protective ligand shell exhibits corresponding site differentiation. In terms of metal nuclearity, Cu70 is the largest alkynyl-stabilized Cu-hydride cluster to date. As a typical highly active intermediate, Cu70 could undergo a transformation into a series of robust modularly assembled Cu clusters (B-type Cu8, A-A-type Cu22, A-B-type Cu23, and A-B-A-type Cu38) upon etching by p-tert-butylthiacalix[4]arene (H4TC4A), which could not be achieved by "one-pot" synthetic methods. Notably, the patterns of A and B blocks in the Cu NCs could be effectively modulated by employing appropriate counterions and blockers, and the modular assembly mechanism was illustrated through comprehensive solution chemistry analysis using HR-ESI-MS. Furthermore, catalytic investigations reveal that Cu38 could serve as a highly efficient catalyst for the cycloaddition of propargylic amines with CO2 under mild conditions. This work not only enriched the family of high-nuclear copper-hydride NCs but also provided new insights into the growth mechanism of metal NCs.

Discovery and Manipulation of van der Waals Polarons in Sb2O3 Ultrathin Molecular Crystal.

Manipulating single electrons at the atomic scale is vital for mastering complex surface processes governed by the transfer of individual electrons. Polarons, composed of electrons stabilized by electron-phonon coupling, offer a pivotal medium for such manipulation. Here, using scanning tunneling microscopy and spectroscopy (STM/STS) and density functional theory (DFT) calculations, we report the identification and manipulation of a new type of polaron, dubbed van der Waals (vdW) polaron, within mono- to trilayer ultrathin films composed of Sb2O3 molecules that are bonded via vdW attractions. The Sb2O3 films were grown on a graphene-covered SiC(0001) substrate via molecular beam epitaxy. Unlike prior molecular polarons, STM imaging observed polarons at the interstitial sites of the molecular film, presenting unique electronic states and localized band bending. DFT calculations revealed the lowest conduction band as an intermolecular bonding state, capable of ensnaring an extra electron through locally diminished intermolecular distances, thereby forming an intermolecular vdW polaron. We also demonstrated the ability to generate, move, and erase such vdW polarons using an STM tip. Our work uncovers a new type of polaron stabilized by coupling with intermolecular vibrations where vdW interactions dominate, paving the way for designing atomic-scale electron transfer processes and enabling precise tailoring of electron-related properties and functionalities.

Adhesion performance of magnetically responsive surfaces under wet conditions.

Adhesion is the key functionality to pick-and-place objects in wet environments. Recently, various micropillars and external stimuli have been proposed to achieve reversible wet adhesion. However, their underlying mechanisms of liquid/solid regulations have not been sufficiently revealed. Herein, two kinds of magnetically responsive micropillar arrays with different terminals (pointed and flat) are developed using a spray self-assembly method. The coupling effect of geometric structures and external stimuli on the wet adhesion performance between a solid substrate and the developed surface is discussed. In situ observation and analysis of theoretical models demonstrate that changes in adhesive forces are mainly caused by the length of the liquid bridge and the apparent contact angle of the developed surface. The adhesion conversion efficiency in the presence of an on/off magnetic field can achieve a highest value of 72% for the micropillar arrays with flat terminals, which exceeds 3 times that of the micropillar arrays with pointed terminals. In addition, wet adhesion measurements during the process of repeatedly switching the magnetic field demonstrate the durability and cyclic reversibility of the magnetically responsive surface. Furthermore, the transportation of microcomponents verifies the application potential of the magnetically responsive surface, which may provide inspiration for transfer printing systems and wet climbing robots.

Constructing Novel High Dielectric Constant Polyimides Containing Dipolar Pendant Groups with Enhanced Orientational Polarization.

Polymer dielectrics with high dielectric constant are urgently demanded for potential electrical and pulsed power applications. The design of polymers with side chains containing dipolar groups is considered an effective method for preparing materials with a high dielectric constant and low loss. This study synthesizes and comprehensively compare the dielectric properties of novel polyimides with side chains containing urea (BU-PI), carbamate (BC-PI), and sulfonyl (BS-PI) functional groups. The novel polyimides exhibit relatively high dielectric constant and low dielectric loss values due to the enhanced orientational polarization and suppressed dipole-dipole interactions of dipolar groups. In particular, BU-PI containing urea pendant groups presents the highest dielectric constant of 6.14 and reasonably low dielectric loss value of 0.0097. The strong γ transitions with low activation energies derived from dielectric spectroscopy measurements have been further evaluated to demonstrate the enhanced free rotational motion of urea pendant dipoles. In energy storage applications, BU-PI achieves a discharged energy density of 6.92 J cm-3 and a charge-discharge efficiency above 83% at 500 MV m-1. This study demonstrates that urea group, as dipolar pendant group, can provide polymers with better dielectric properties than the most commonly used sulfonyl groups.

Neurosurgical clipping versus endovascular coiling for patients with ruptured anterior circulation aneurysms: A systematic review and meta-analysis.

To compare the safety and efficacy of clipping and coiling in patients with ruptured anterior circulation aneurysms. A systematic search of four databases (PubMed, Web of Science, Cochrane Library, and Embase) was conducted to identify comparative articles on endovascular coiling and surgical clipping in patients with ruptured anterior circulation aneurysms. Meta-analyses were conducted using random-effects models. Nineteen studies, including 1983 patients, were included. The meta-analysis showed that neurosurgical clipping was associated with a lower incidence of retreatment (OR:0.28, 95% CI (0.11, 0.70), P = 0.006) than endovascular coiling, which seemed to be a result of incomplete occlusion (OR:0.22, 95% CI (0.11, 0.45), P < 0.001). Neurosurgical clipping was associated with lower mortality (OR:0.45, 95% CI (0.25, 0.82), P = 0.009) at short-term follow-up than endovascular coiling. However, neurosurgical clipping showed a higher incidence of ischemic infarction (OR:2.28, 95% CI (1.44, 3.63), P < 0.001) and a longer length of stay (LOS) (WMD:6.12, 95% CI (4.19, 8.04), P < 0.001) after surgery than endovascular coiling. Furthermore, the pooled results showed no statistically significant differences between the two groups regarding poor outcome, long-term mortality, rebleeding, vasospasm, and hydrocephalus. Evidence from this systematic review illustrates that neurosurgical clipping may be superior to endovascular coiling for ruptured anterior circulation aneurysms. Large-scale RCTs should be conducted to verify these outcomes and provide results according to patient status.

Conditional Enhanced Variational Autoencoder-Heterogeneous Graph Attention Neural Network: A Novel Fault Diagnosis Method for Electric Rudders Based on Heterogeneous Information.

In machine fault diagnosis, despite the wealth of information multi-sensor data provide for constructing high-quality graphs, existing graph data-driven diagnostic methods face challenges posed by handling these heterogeneous multi-sensor data. To address this issue, we propose CEVAE-HGANN, an innovative model for fault diagnosis based on the electric rudder, which can process heterogeneous data efficiently. Initially, we facilitate interaction between conditional information and the original features, followed by dimensional reduction via a conditional enhanced variational autoencoder, thereby achieving a more robust state representation. Subsequently, we define two meta-paths and employ both the Euclidean distance and Pearson coefficient in crafting an effective adjacency matrix to delineate the relationships among edges within the graph, thereby effectively representing the complex interrelations among these subsystems. Ultimately, we incorporate heterogeneous graph attention neural networks for classification, which emphasizes the connections among different subsystems, moving beyond the reliance on node-level fault identification and effectively capturing the complex interactions between subsystems. The experimental outcomes substantiate the superiority of the electric rudder-based CEVAE-HGANN model fault diagnosis.

Removal of Cu(II) by sodium hexametaphosphate and nano zero-valent iron modified calcium bentonite: characteristic, adsorption performance and mechanism.

Cu (II) is a toxic heavy metal commonly identified in groundwater contaminants. Bentonite-based cutoff wall is the most used method in isolating and adsorbing contaminants, while the bentonite in it easily to fail due to Cu(II) exchange. This study synthesized a novel material through the modification of calcium bentonite (CaB) utilizing sodium hexametaphosphate (SHMP) and nano zero-valent iron (NZVI). The characteristics, adsorption performance, and mechanism of the NZVI/SHMP-CaB were investigated comprehensively. The results showed that SHMP can disperse CaB and reduce flocculation, while NZVI can be further stabilized without agglomeration. The best adsorption performance of NZVI/SHMP-CaB could be obtained at the dosage of 2% SHMP and 4% NZVI. The NZVI/SHMP-CaB exhibited an outstanding removal efficiency of over 60% and 90% at a high Cu(II) concentration (pH = 6, Cu(II) = 300 mg/L) and acidic conditions (pH = 3-6, Cu(II) = 50 mg/L), respectively. The adsorption of Cu(II) by NZVI/SHMP-CaB followed a pseudo-second-order kinetic model, and fitting results from the Freundlich isothermal model suggested that the adsorption process occurred spontaneously. Besides the rapid surface adsorption on the NZVI/SHMP-CaB and ion exchange with interlayer ions in bentonite, the removal mechanism of Cu(II) also involved the chemical reduction to insoluble forms such as Cu0 and Cu2O. The generated FePO4 covered the surface of the homogenized NZVI particles, enhancing the resistance of NZVI/SHMP-CaB to acidic and oxidative environments. This study indicates that NZVI/SHMP-CaB is a promising alternative material which can be used for heavy metal removal from contaminated soil and water.

Co-encapsulation of curcumin and anthocyanins in bovine serum album-fucoidan nanocomplex with a two-step pH-driven method.

BACKGROUND: Curcumin (CUR) and anthocyanins (ACN) are recommended due to their bioactivities. However, their nutritional values and health benefits are limited by their low oral bioavailability. The incorporation of bioactive substances into polysaccharide-protein composite nanoparticles is an effective way to enhance their bioavailability. Accordingly, this study explored the fabrication of bovine serum albumin (BSA)-fucoidan (FUC) hybrid nanoparticles using a two-step pH-driven method for the delivery of CUR and ACN. RESULTS: Under a 1:1 weight ratio of BSA to FUC, the point of zero charge moved from pH ⁓ 4.7 for BSA to around 2.5 for FUC-coated BSA, and the formation of BSA-FUC nanocomplex was pH-dependent by showing the maximum CUR emission wavelength shifting from 546 nm (CUR-loaded BSA-FUC at pH 4.7) and 544 nm (CUR/ACN-loaded BSA-FUC nanoparticles at pH 4.7) to 540 nm (CUR-loaded BSA-FUC at pH 6.0) and 539 nm (CUR/ACN-loaded BSA-FUC nanoparticles at pH 6.0). Elevated concentrations of NaCl from 0 to 2.5 mol L-1 caused particle size increase from about 250 to about 800 nm, but showing no effect on the encapsulation efficiency of CUR. The CUR and ACN entrapped, respectively, in the inner and outer regions of the BSA-FUC nanocomplex were released at different rates. After incubation for 10 h, more than 80% of ACN was released, while less than 25% of CUR diffused into the receiving medium, which fitted well to Logistic and Weibull models. CONCLUSION: In summary, the BSA-FUC nanocomposites produced by a two-step pH-driven method could be used for the co-delivery of hydrophilic and hydrophobic nutraceuticals. © 2023 Society of Chemical Industry.

Biogenetic Vesicle-Based Cancer Vaccines with Tunable Surface Potential and Immune Potency.

Cancer vaccines are designed to motivate antigen-specific immune responses and facilitate tumor regression with minimal side effects. To fully exert the potential of vaccines, rationally designed formulations that effectively deliver antigens and trigger potent immune reactions are urgently needed. This study demonstrates a simple and controllable vaccine-developing strategy that assembles tumor antigens into bacterial outer membrane vesicles (OMVs), natural delivery vehicles with intrinsic immune adjuvant properties, via electrostatic interaction. This OMV-delivered vaccine (OMVax) stimulated both innate and adaptive immune responses, leading to enhanced metastasis inhibition and prolonged survival of tumor-bearing mice. Moreover, the influence of different surface charged OMVax on antitumor immunity activation is investigated and declined immune response activation occurred with increased positive surface charge. Together, these findings suggest a simple vaccine formulation that can be enhanced by optimizing the surface charges of vaccine formulations.

Molecular Insights into the Stability of Titanium in Electrolytes Containing Chlorine and Fluorine Ions.

Titanium and its alloys are protected by a compact and stable passive film, which confers resistance to corrosion by the primary halogen chloride (Cl-) while being less effective against fluoride (F-). Although researchers have recognized different macroscopic corrosion effects of these halide ions on titanium, the underlying mechanisms remain largely unexplored. In this work, the bonding of Cl-/F- with stable passive films was studied in neutral and acidic (pH = 2.3) conditions. The synergistic effect between the interfacial hydrogen bond (HB) structure and halogens on titanium corrosion was first revealed using first-principles calculation and Raman spectroscopy. F- forms more stable halogen-Ti bonds than Cl-, resulting in titanium degradation. The proton combined with F- exhibits a specific synergistic effect, causing corrosion of the passive film. The water hydrogen bond transformation index (HBTI) at the titanium/aqueous interface was 1.88 in an acidic solution containing F-, significantly higher than that in neutral/acid solutions containing Cl- (1.80/1.81) and a neutral solution containing F- (1.81). This work clarifies the structure-activity relationship between HBTI and the destruction of titanium passive films. We propose that the microstructure of the interfacial HB is an undeniable factor in the corrosion of titanium.

Access to Benzocyclic Boronates via Light-Promoted Intramolecular Arylborylation of Alkenes.

Benzocyclic boronates have attracted increasing research interest in drug chemistry and organic synthesis in recent years. Herein, we report a facile access to benzocyclic boronates through photopromoted intramolecular arylborylation of allyl aryldiazonium salts. This simple protocol features a broad scope, allowing the formation of variously functionalized borates bearing dihydrobenzofuran, dihydroindene, benzothiophene, and indoline skeletons under mild and sustainable conditions.

New P,Nsp3 ligands for palladium-catalyzed asymmetric allylic substitutions.

New P,Nsp3 bidentate ligands containing two chiral carbon centers were developed and applied to palladium-catalyzed asymmetric allylic substitution reactions. Good generalities with various nucleophiles, including carbon, nitrogen and oxygen containing nucleophiles, were achieved with up to 96% ee and 98% yield. This reaction provides an efficient method for the asymmetric formation of C-C, C-N and C-O bonds.

Pigment epithelium-derived factor maintains tight junction stability after myocardial infarction in rats through inhibition of the Wnt/ß-catenin signaling pathway.

PURPOSE: The impairment of the coronary microcirculatory barrier caused by acute myocardial infarction (AMI) is closely related to poor prognosis. Recently, pigment epithelial-derived factor (PEDF) has been proven to be a promising cardiovascular protective drug. In this study, we demonstrated the protective role of PEDF in endothelial tight junctions (TJs) and the vascular barrier in AMI. MATERIALS AND METHODS: 2, 3, 5-triphenyltetrazolium chloride (TTC), echocardiography and immunofluorescence staining were used to observe the size of infarcted myocardium area and cardiac function in myocardial tissue, and the distribution of TJ proteins in human coronary endothelial cells (HCAEC). Dextran leakage assay and Transwell were used to assess the extent of vascular and HCAEC leakage. Polymerase chain reaction (PCR) and Western blot were used to detect TJ-related mRNA and protein, and signaling pathway protein expression. RESULTS: PEDF effectively reduced the infarction area and improved cardiac function in AMI rats, and lowered the leakage in AMI rats' angiocarpy and oxygen-glucose deprivation (OGD)-treated HCAEC. Furthermore, PEDF upregulated the expression of TJ mRNA and proteins in vivo and vitro. Mechanistically, PEDF inhibited the expression of phosphorylated low-density lipoprotein receptor-related protein 6 (p-LRP6) and active ß-catenin under OGD, thus suppressing the activation of the classical Wnt pathway. CONCLUSIONS: These novel findings demonstrated that PEDF maintained the expression of TJ proteins and endothelial barrier integrity by inhibiting the classical Wnt pathway during AMI.

Pyrite coupled with biochar alleviating the toxicity of silver nanoparticles on pollutants removal in constructed wetlands.

Silver nanoparticles (AgNPs) has been widely detected in the substrates of constructed wetlands (CWs), posing threaten to pollutants removal efficiency of CWs. However, the way to alleviate the toxicity of AgNPs on CWs is unclear. In this study, the gravel (GR), biochar (BC), pyrite (PY) and pyrite coupled with biochar matrix (PYBC) were selected as substrates to restore the pollutants removal efficiency of CWs under the exposure to the environment (0.2 mg/L) and accumulation (10 mg/L) concentration of AgNPs. Results showed that the BC and PY showed limited mitigation effects, while the PYBC alleviated the toxicity significantly. Especially in the exposure to the accumulation concentration of AgNPs, the removal of NH4+-N, TN, COD and TP in the PYBC were 10.2%, 8.3%, 9.4% and 10.7% higher than that in the GR, respectively. Mechanism analysis verified that AgNPs were transformed into Ag-Fe-S core shell aggregates (size >200 nm) decreasing bioavailability and the damage to cytomembrane. The PYBC restored the nitrogen removal efficiency by increasing the abundance of Nitrospira and Geothrix, which these bacteria were defined as nitrifiers and Feammox bacteria. This study provides a promising strategy to mitigate AgNPs' toxicity on the pollutant removal efficiency in CWs.

Effects of a Pirin-like protein on strain growth and spinosad biosynthesis in Saccharopolyspora spinosa.

Pirin family proteins perform a variety of biological functions and widely exist in all living organisms. A few studies have shown that Pirin family proteins may be involved in the biosynthesis of antibiotics in actinomycetes. However, the function of Pirin-like proteins in S. spinosa is still unclear. In this study, the inactivation of the sspirin gene led to serious growth defects and the accumulation of H2O2. Surprisingly, the overexpression and knockout of sspirin slightly accelerated the consumption and utilization of glucose, weakened the TCA cycle, delayed sporulation, and enhanced sporulation in the later stage. In addition, the overexpression of sspirin can enhance the ß-oxidation pathway and increase the yield of spinosad by 0.88 times, while the inactivation of sspirin hardly produced spinosad. After adding MnCl2, the spinosad yield of the sspirin overexpression strain was further increased to 2.5 times that of the wild-type strain. This study preliminarily revealed the effects of Pirin-like proteins on the growth development and metabolism of S. spinosa and further expanded knowledge of Pirin-like proteins in actinomycetes. KEY POINTS: • Overexpression of the sspirin gene possibly triggers carbon catabolite repression (CCR) • Overexpression of the sspirin gene can promote the synthesis of spinosad • Knockout of the sspirin gene leads to serious growth and spinosad production defects.

BER performance of an FSOC system over atmospheric turbulence channels based on computational temporal ghost imaging.

In a free space optical communication (FSOC) system, atmospheric turbulence will increase the bit error ratio (BER) and impair FSOC link reliability. Since computational temporal ghost imaging (CTGI) has anti-interference, we present an FSOC system over atmospheric turbulence based on CTGI. The simulation results show that the BER performance of CTGI is better than on-off keying under different atmospheric turbulence regimes. To improve the performance of the CTGI scheme, the influence of the number of transmission samples and code length is analyzed. It is shown that BER performance improves with the increment of the number of samples, while code length has no impact. This scheme provides an idea for reliable communication over atmospheric turbulence and an important reference for improving wireless optical communication in an extreme environment.

Highly accurate OAM mode detection network for ring Airy Gaussian vortex beams disturbed by atmospheric turbulence based on interferometry.

Atmospheric turbulence reduces the detection accuracy of orbital angular momentum (OAM) modes, which affects the performance of OAM optical communication. In this paper, we propose a method based on interferometry and a residual network (ResNet) to detect the OAM modes of ring Airy Gaussian vortex beams (RAGVBs) disturbed by atmospheric turbulence. The RAGVBs first interfere with spherical waves to obtain the sign features of the OAM modes, and then ResNet is employed to recognize OAM modes from the interferograms. The results demonstrate that the detection accuracy is higher than that of the OAM spectrum method under different turbulence strengths. The detection accuracy can even reach over 99% under strong fluctuations. Our research provides a reference for improving the performance of OAM optical communication through atmospheric turbulence.

PEDF Protects Endothelial Barrier Integrity during Acute Myocardial Infarction via 67LR.

Maintaining the integrity and protecting the stability of tight junctions in endothelial cells is a potential therapeutic strategy against myocardial ischaemia. Laminin receptors (67LR) are highly expressed on endothelial cell membranes and are associated with endothelial barrier function. Herein, we sought to demonstrate the direct effects of pigment epithelial-derived factor (PEDF) on tight junctions between endothelial cells via 67LR during acute myocardial infarction (AMI) and elucidate its underlying mechanisms. We detected that PEDF directly increased the level of the tight junction protein zonula occludens protein 1 (ZO-1) after overexpression in vitro and in vivo using Western blotting. Evans Blue/TTC staining showed that PEDF significantly reduced the size of the infarcted myocardium. Immunofluorescence and the transwell cellular experiments suggested that PEDF significantly upregulated PI3K-AKT permeability and the distribution of ZO-1 between endothelial cells under OGD conditions. Interestingly, PEDF significantly upregulated the phosphorylation levels of PI3K-AKT-mTOR under oxygen and glucose deprivation conditions but had no significant effects on the total protein expression. The protective effect of PEDF on ZO-1 was significantly inhibited following the inhibition of PI3K-AKT-mTOR. The activation of phosphorylation of PI3K-AKT-mTOR by PEDF was blocked after silencing 67LR, as were the protective effects of PEDF on ZO-1. Therefore, we have reason to believe that PEDF increased ZO-1 expression through the 67LR-dependent PI3K-AKT-mTOR signaling pathway, thus maintaining tight junction stability and protecting cardiac function.

Inspiratory hyperoxia suppresses lung cancer metastasis through a MYC/SLC1A5-dependent metabolic pathway.

The lack of knowledge about the effect of inspiratory hyperoxia on the lung-specific tumour microenvironment and progression of lung cancer has attracted considerable attention. This study proposes that inspiratory hyperoxia has special significance for the malignant phenotype of lung cancer cells. The effects of different oxygenation parameters on the proliferation, apoptosis, invasion and migration of lung cancer cells were systematically evaluated in vitro and in vivo Our results reveal that inspiratory hyperoxia treatment (60% oxygen, 6 h·day-1) not only has no tumour progression-promoting effects, but also suppresses lung cancer metastasis and promotes long-term survival. In addition, we combined transcriptome, proteome and metabolome analysis and found that hyperoxia treatment induced significant intracellular metabolic changes in lung cancer cells. Overall, we established that MYC/SLC1A5-induced metabolic reprogramming and glutamine addiction is a new mechanism that drives lung cancer metastasis, which can be significantly suppressed by inspiratory hyperoxia treatment. These findings are relevant to the debate on the perils, promises and antitumour effect of inspiratory hyperoxia, especially for patients with lung cancer.