Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice.

Studies of two-dimensional electron systems in a strong magnetic field revealed the quantum Hall effect1, a topological state of matter featuring a finite Chern number C and chiral edge states2,3. Haldane4 later theorized that Chern insulators with integer quantum Hall effects could appear in lattice models with complex hopping parameters even at zero magnetic field. The ABC-trilayer graphene/hexagonal boron nitride (ABC-TLG/hBN) moiré superlattice provides an attractive platform with which to explore Chern insulators because it features nearly flat moiré minibands with a valley-dependent, electrically tunable Chern number5,6. Here we report the experimental observation of a correlated Chern insulator in an ABC-TLG/hBN moiré superlattice. We show that reversing the direction of the applied vertical electric field switches the moiré minibands of ABC-TLG/hBN between zero and finite Chern numbers, as revealed by large changes in magneto-transport behaviour. For topological hole minibands tuned to have a finite Chern number, we focus on quarter filling, corresponding to one hole per moiré unit cell. The Hall resistance is well quantized at h/2e2 (where h is Planck's constant and e is the charge on the electron), which implies C = 2, for a magnetic field exceeding 0.4 tesla. The correlated Chern insulator is ferromagnetic, exhibiting substantial magnetic hysteresis and a large anomalous Hall signal at zero magnetic field. Our discovery of a C = 2 Chern insulator at zero magnetic field should open up opportunities for discovering correlated topological states, possibly with topological excitations7, in nearly flat and topologically nontrivial moiré minibands.

Publisher Correction: Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A model of d-wave superconductivity, antiferromagnetism, and charge order on the square lattice.

We describe the confining instabilities of a proposed quantum spin liquid underlying the pseudogap metal state of the hole-doped cuprates. The spin liquid can be described by a SU(2) gauge theory of Nf = 2 massless Dirac fermions carrying fundamental gauge charges-this is the low-energy theory of a mean-field state of fermionic spinons moving on the square lattice with π-flux per plaquette in the ℤ2 center of SU(2). This theory has an emergent SO(5)f global symmetry and is presumed to confine at low energies to the Néel state. At nonzero doping (or smaller Hubbard repulsion U at half-filling), we argue that confinement occurs via the Higgs condensation of bosonic chargons carrying fundamental SU(2) gauge charges also moving in π ℤ2-flux. At half-filling, the low-energy theory of the Higgs sector has Nb = 2 relativistic bosons with a possible emergent SO(5)b global symmetry describing rotations between a d-wave superconductor, period-2 charge stripes, and the time-reversal breaking "d-density wave" state. We propose a conformal SU(2) gauge theory with Nf = 2 fundamental fermions, Nb = 2 fundamental bosons, and a SO(5)f×SO(5)b global symmetry, which describes a deconfined quantum critical point between a confining state which breaks SO(5)f and a confining state which breaks SO(5)b. The pattern of symmetry breaking within both SO(5)s is determined by terms likely irrelevant at the critical point, which can be chosen to obtain a transition between Néel order and d-wave superconductivity. A similar theory applies at nonzero doping and large U, with longer-range couplings of the chargons leading to charge order with longer periods.

FCRL3 expression is upregulated and closely correlates with TIGIT expression in regulatory T cells of patients with systemic lupus erythematosus.

Using data from single-cell RNA sequencing and flow cytometry, we initially examined the expression of FCRL3, finding it to be elevated and positively associated with TIGIT expression in the regulatory T cells of patients with systemic lupus erythematosus. This also suggests that the co-expression of FCRL3 and TIGIT warrants further attention.

Maize actin depolymerizing factor 1 (ZmADF1) negatively regulates pollen development.

The normal development of pollen grains and the completion of double fertilization in embryos are crucial for both the sexual reproduction of angiosperms and grain production. Actin depolymerizing factor (ADF) regulates growth, development, and responses to biotic and abiotic stress by binding to actin in plants. In this study, the function of the ZmADF1 gene was validated through bioinformatic analysis, subcellular localization, overexpression in maize and Arabidopsis, and knockout via CRISPR/Cas9. The amino acid sequence of ZmADF1 exhibited high conservation and a similar tertiary structure to that of ADF homologs. Subcellular localization analysis revealed that ZmADF1 is localized mainly to the nucleus and cytoplasm. The ZmADF1 gene was specifically expressed in maize pollen, and overexpression of the ZmADF1 gene decreased the number of pollen grains in the anthers of transgenic Arabidopsis plants. The germination rate of pollen and the empty seed shell rate in the fruit pods of the overexpressing plants were significantly greater than those in the wild-type (WT) plants. In maize, the pollen viability of the knockout lines was significantly greater than that of both the WT and the overexpressing lines. Our results confirmed that the ZmADF1 gene was specifically expressed in pollen and negatively regulated pollen quantity, vigor, germination rate, and seed setting rate. This study provides insights into ADF gene function and possible pathways for improving high-yield maize breeding.

Photonic implementation of the input and reservoir layers for a reservoir computing system based on a single VCSEL with two Mach-Zehnder modulators.

Hardware implementation of reservoir computing (RC), which could reduce the power consumption of machine learning and significantly enhance data processing speed, holds the potential to develop the next generation of machine learning hardware devices and chips. Due to the existing solution only implementing reservoir layers, the information processing speed of photonics RC system are limited. In this paper, a photonic implementation of a VMM-RC system based on single Vertical Cavity Surface Emitting Laser (VCSEL) with two Mach Zehnder modulators (MZMs) has been proposed. Unlike previous work, both the input and reservoir layers are realized in the optical domain. Additionally, the impact of various mask signals, such as Two-level mask, Six-level mask, and chaos mask signal, employed in system, has been investigated. The system's performance improves with the use of more complex mask(t). The minimum Normalized mean square error (NMSE) can reach 0.0020 (0.0456) for Santa-Fe chaotic time series prediction in simulation (experiment), while the minimum Word Error Rate (WER) can 0.0677 for handwritten digits recognition numerically. The VMM-RC proposed is instrumental in advancing the development of photonic RC by overcoming the long-standing limitations of photonic RC systems in reservoir implementation. Linear matrix computing units (the input layer) and nonlinear computing units (the reservoir layer) are simultaneously implemented in the optical domain, significantly enhancing the information processing speed of photonic RC systems.

Green Late-Stage Functionalization of Tryptamines.

An efficient and rapid protocol for the oxidative halogenation of tryptamines with 10% aqueous NaClO has been developed. This reaction is featured by its operational simplicity, metal-free conditions, no purification, and high yield. Notably, the resulting key intermediates are suitable for further functionalization with various nucleophiles, including amines, N-aromatic heterocycles, indoles and phenols. The overall transformation exhibits broad functional-group tolerance and is applicable to the late-stage functionalization of complex biorelevant molecules.

Boosting the Photocatalytic Performance of g-C3N4 through MoS2 Nanotubes with the Cavity Enhancement Effect.

The development of catalysts with high photon utilization efficiency is crucial for enhancing the catalytic performance of photocatalysts. Graphitic carbon nitride (g-C3N4) is a prominent material in the field of photocatalysis. However, it still exhibits drawbacks such as low utilization of visible light and severe recombination of photogenerated carriers. To address these issues, this study employs MoS2 nanotubes (NTs) as cocatalysts and constructs MoS2 NTs/g-C3N4. The MoS2 NTs/g-C3N4 exhibits a significant cavity enhancement effect through multiple light reflections. This results in a broad spectral absorption range and high photon utilization efficiency, while also reducing the recombination of photogenerated carriers. The photocatalyst demonstrates outstanding performance in both photocatalytic hydrogen production and photodegradation of organic pollutants. Specifically, the hydrogen production rate is 1921 µmol·g-1·h-1, which is approximately 2.4 times that of g-C3N4. Furthermore, the photodegradation rate of Rhodamine B reaches 98.6% within 30 min, which is approximately three times higher than that of g-C3N4. Free radical capture experiments confirm that holes (h+) are the primary active species in photodegradation. A plausible photocatalytic mechanism for the catalyst is proposed. This study provides valuable insights into the development of heterojunction photocatalysts with high photon utilization efficiency.

Enhancement of vitamin B6 production driven by omics analysis combined with fermentation optimization.

BACKGROUND: Microbial engineering aims to enhance the ability of bacteria to produce valuable products, including vitamin B6 for various applications. Numerous microorganisms naturally produce vitamin B6, yet the metabolic pathways involved are rigorously controlled. This regulation by the accumulation of vitamin B6 poses a challenge in constructing an efficient cell factory. RESULTS: In this study, we conducted transcriptome and metabolome analyses to investigate the effects of the accumulation of pyridoxine, which is the major commercial form of vitamin B6, on cellular processes in Escherichia coli. Our omics analysis revealed associations between pyridoxine and amino acids, as well as the tricarboxylic acid (TCA) cycle. Based on these findings, we identified potential targets for fermentation optimization, including succinate, amino acids, and the carbon-to-nitrogen (C/N) ratio. Through targeted modifications, we achieved pyridoxine titers of approximately 514 mg/L in shake flasks and 1.95 g/L in fed-batch fermentation. CONCLUSION: Our results provide insights into pyridoxine biosynthesis within the cellular metabolic network for the first time. Our comprehensive analysis revealed that the fermentation process resulted in a remarkable final yield of 1.95 g/L pyridoxine, the highest reported yield to date. This work lays a foundation for the green industrial production of vitamin B6 in the future.

Electrochemiluminescence of an iridium complex doped with SiO2 nanoparticles to detect 2-adamantanamine based on the host-guest interaction of cucurbit[7]uril.

The poor solubility of iridium complexes severely hampers its application in the electrochemiluminescence (ECL) sensing field. The doping of an iridium complex with silica (SiO2) nanospheres provides feasible solution for this problem. Herein, one kind of water insoluble iridium complex ([Ir(dFppy)2(d(CF3)bpy)](PF6)) was doped with SiO2 nanoparticles to obtain a luminescent nanocomposite (SiO2@Ir) which could generate strong ECL signals to act as a beacon molecule. An "off-on-off" mode ECL sensor was proposed based on the competitive host-guest interactions between 2-adamantanamine (2-ADA), ferrocene (Fc) and cucurbit[7]uril (Q[7]). Fc could be used as an inhibitor to decrease the ECL signal, while Q[7] could wrap Fc to recover the ECL signal. Q[7] has a stronger binding ability with 2-ADA than Fc. As a result, 2-ADA could replace Fc from the cavity of Q[7], and the ECL signal was inhibited again. Under the optimal conditions, the ECL intensity varied linearly with 2-ADA concentration in the range of 1.0 × 10-8 to 1.0 × 10-6 mol L-1 with a detection limit of 2.5 × 10-10 mol L-1. The results not only provided a new avenue for the application of water insoluble iridium complexes in ECL sensing, but also revealed the attractive potential of host-guest interactions in the fabrication of biosensors.

Comparison of Pocock and Simon's covariate-adaptive randomization procedures in clinical trials.

When multiple influential covariates need to be balanced during a clinical trial, stratified blocked randomization and covariate-adaptive randomization procedures are frequently used in trials to prevent bias and enhance the validity of data analysis results. The latter approach is increasingly used in practice for a study with multiple covariates and limited sample sizes. Among a group of these approaches, the covariate-adaptive procedures proposed by Pocock and Simon are straightforward to be utilized in practice. We aim to investigate the optimal design parameters for the patient treatment assignment probability of their developed three methods. In addition, we seek to answer the question related to the randomization performance when additional covariates are added to the existing randomization procedure. We conducted extensive simulation studies to address these practically important questions.

Sensitive detection of uric acid based on low-triggering-potential cathodic luminol electrochemiluminescence achieved by ReS2 nanosheets.

The majority of previously reported cathodic electrochemiluminescence (ECL) systems often required very negative potential to be carried out, which has greatly limited their applications in the sensing field. Screening high-performance cathodic ECL systems with low triggering potential is a promising way to broaden their applications. In this work, rhenium disulfide nanosheets (ReS2 NS) have been revealed as an efficient co-promoter to realize low-triggering-potential cathodic luminol ECL. One strong cathodic ECL signal appeared at a potential of -0.3 V and one anodic ECL peak was obtained at -0.15 V under the reverse potential scan, which were caused by electrogenerated reactive oxygen species (ROS) from hydrogen peroxide. The generation of strong luminol ECL at low potential was the result of the electrocatalytic effect of ReS2 NS on the reduction of H2O2. The scavenging effect of uric acid (UA) on the ROS could significantly inhibit the cathodic ECL. As a result, an ECL sensor was proposed, which showed outstanding performance for the detection of UA in the range of 10 nM to 0.1 mM with a low detection limit of 1.53 nM. Moreover, the ECL sensor was successfully applied in the sensitive detection of UA in real samples. This work provides a new avenue to establish a low-potential cathodic ECL system, which will sufficiently expand the potential application of cathodic ECL in the sensing field.

Novel anti-inflammatory diketopiperazine alkaloids from the marine-derived fungus Penicillium brasilianum.

Diketopiperazine alkaloids have proven the most abundant heterocyclic alkaloids up to now, which usually process diverse scaffolds and rich biological activities. In our search for bioactive diketopiperazine alkaloids from marine-derived fungi, two novel diketopiperazine alkaloids, penipiperazine A (1) and its biogenetically related new metabolite (2), together with a known analogue neofipiperzine C (3), were obtained from the strain Penicillium brasilianum. Their planar structures and absolute configurations were elucidated by extensive spectroscopic analyses, 13C NMR calculation, Marfey's, ECD, and ORD methods. Compound 1 featured a unique 6/5/6/6/5 indole-pyrazino-pyrazino-pyrrolo system, and its plausible biogenetic pathway was also proposed. Additionally, compounds 1-3 have been tested for their inflammatory activities. 1 and 2 significantly inhibited the release of NO and the expression of related pro-inflammatory cytokines on LPS-stimulated RAW264.7 cells, suggesting they could be attracting candidate for further development as anti-inflammatory agent. KEY POINTS: • A novel diketopiperazine alkaloid featuring a unique 6/5/6/6/5 indole-pyrazino-pyrazino-pyrrolo system was isolated from the marine fungus Penicillium brasilianum. • The structure of 1 was elucidated by detailed analysis of 2D NMR data, 13C NMR calculation, Marfey's, ECD, and ORD methods. • Compounds 1 and 2 significantly inhibited the release of NO and the expression of related pro-inflammatory cytokines on LPS-stimulated RAW264.7 cells.

Clinical phenotypes of comorbidities in end-stage knee osteoarthritis: a cluster analysis.

OBJECTIVES: Comorbidities, as components of these heterogeneous features, often coexist with knee osteoarthritis, and are particularly prevalent in end-stage knee osteoarthritis. Here, we attempted to identify the different clinical phenotypes of comorbidities in patients with end-stage knee osteoarthritis by cluster analysis. METHODS: A total of 421 inpatients diagnosed with end-stage knee osteoarthritis who underwent inpatient surgery were included in this cross-sectional study. 23 demographic, comorbidity, inflammatory immune and evaluation scale variables were collected. Systematic clustering after factor analysis and separate two-step cluster analysis were performed for individual comorbidity variables and all variables, respectively, to objectively identify the different clinical phenotypes of the study patients. RESULTS: Four clusters were finally identified. Cluster 1 had the largest proportion of obese patients (93.8%) and hypertension was common (71.2%). Almost all patients in cluster 2 were depressed (95.8%) and anxiety disorders (94.7%). Cluster 3 combined patients with isolated end-stage knee osteoarthritis and a few comorbidities. Cluster 4 had the highest proportion of patients with rheumatoid arthritis (58.8%). CONCLUSIONS: Patients with end-stage knee osteoarthritis may be classified into four different clinical phenotypes: "isolated end-stage knee osteoarthritis"; "obesity + hypertension"; "depression + anxiety"; and "rheumatoid arthritis", which may help guide individualized patient care and treatment strategies.

Cooperative Safe Trajectory Planning for Quadrotor Swarms.

In this paper, we propose a novel distributed algorithm based on model predictive control and alternating direction multiplier method (DMPC-ADMM) for cooperative trajectory planning of quadrotor swarms. First, a receding horizon trajectory planning optimization problem is constructed, in which the differential flatness property is used to deal with the nonlinear dynamics of quadrotors while we design a relaxed form of the discrete-time control barrier function (DCBF) constraint to balance feasibility and safety. Then, we decompose the original trajectory planning problem by ADMM and solve it in a fully distributed manner with peer-to-peer communication, which induces the quadrotors within the communication range to reach a consensus on their future trajectories to enhance safety. In addition, an event-triggered mechanism is designed to reduce the communication overhead. The simulation results verify that the trajectories generated by our method are real-time, safe, and smooth. A comprehensive comparison with the centralized strategy and several other distributed strategies in terms of real-time, safety, and feasibility verifies that our method is more suitable for the trajectory planning of large-scale quadrotor swarms.

A High-Performance System for Weak ECG Real-Time Detection.

Wearable devices have been widely used for the home monitoring of physical activities and healthcare conditions, among which ambulatory electrocardiogram (ECG) stands out for the diagnostic cardiovascular information it contains. Continuous and unobtrusive sensing often requires the integration of wearable sensors to existing devices such as watches, armband, headphones, etc.; nonetheless, it is difficult to detect high-quality ECG due to the nature of low signal amplitude at these areas. In this paper, a high-performance system with multi-channel signal superposition for weak ECG real-time detection is proposed. Firstly, theoretical analysis and simulation is performed to demonstrate the effectiveness of this system design. The detection system, including electrode array, acquisition board, and the application (APP), is then developed and the electrical characteristics are measured. A common mode rejection ratio (CMRR) of up to 100 dB and input inferred voltage noise below 1 µV are realized. Finally, the technique is implemented in form of ear-worn and armband devices, achieving an SNR over 20 dB. Results are also compared with the simultaneous recording of standard lead I ECG. The correlation between the heart rates derived from experimental and standard signals is higher than 0.99, showing the feasibility of the proposed technique.

Symmetry-Broken Chern Insulators in Twisted Double Bilayer Graphene.

Twisted double bilayer graphene (tDBG) has emerged as a rich platform for studying strongly correlated and topological states, as its flat bands can be continuously tuned by both a perpendicular displacement field and a twist angle. Here, we construct a phase diagram representing the correlated and topological states as a function of these parameters, based on measurements of over a dozen tDBG devices encompassing two distinct stacking configurations. We find a hierarchy of symmetry-broken states that emerge sequentially as the twist angle approaches an apparent optimal value of θ ≈ 1.34°. Nearby this angle, we discover a symmetry-broken Chern insulator (SBCI) state associated with a band filling of 7/2 as well as an incipient SBCI state associated with 11/3 filling. We further observe an anomalous Hall effect at zero field in all samples supporting SBCI states, indicating spontaneous time-reversal symmetry breaking and possible moiré unit cell enlargement at zero magnetic field.

Magnetic Field-Stabilized Wigner Crystal States in a Graphene Moiré Superlattice.

ABC-stacked trilayer graphene on boron nitride (ABC-TLG/hBN) moiré superlattices provides a tunable platform for exploring Wigner crystal states in which the electron correlation can be controlled by electric and magnetic fields. Here we report the observation of magnetic field-stabilized Wigner crystal states in a ABC-TLG/hBN. We show that correlated insulating states emerge at multiple fractional and integer fillings corresponding to ν = 1/3, 2/3, 1, 4/3, 5/3, and 2 electrons per moiré lattice site under a magnetic field. These correlated insulating states can be attributed to generalized Mott states for the integer fillings and generalized Wigner crystal states for the fractional fillings. The generalized Wigner crystal states are stabilized by a vertical magnetic field and are strongest at one magnetic flux quantum per three moiré superlattices. The ν = 2 insulating state persists up to 30 T, which can be described by a Mott-Hofstadter transition at a high magnetic field.

Hydration and properties of hydrogen-based mineral phase transformation iron ore tailings as supplementary cementitious material.

Almost all iron ore tailings (IOTs) required activation prior to use as SCMs, which limited their application in building materials. This study investigated HMPT-IOTs and discovered that they possess latent hydraulic and pozzolanic properties. In order to better utilize as SCM, mechanical properties, hydration reactions, hydration products, microstructure, and pores were comprehensively studied through mechanical tests, hydration heat tests, XRD, SEM, TG, and MIP. The results show that when HMPT-IOTs replace cement at 10 wt%, 20 wt% and 30 wt%, the compressive strength at 28 days is 41.9 MPa, 47.9 MPa and 37.5 MPa, respectively. When the substitution amount reaches 30 wt%, it will reduce the cumulative heat of hydration and promote early hydration reactions. The main hydration products are ettringite and Ca(OH)2. As the nucleation site of C-S-H, hydration products are interconnected, making the microstructure denser. At this substitution level, Ca(OH)2 consumption was about 2% at 28 days of age. Simultaneously, the total pore volume was only 0.01 mL/g greater than that of the control group, and the number of micropores and transition pores decreased by approximately 3%.

Enhanced anaerobic digestion of waste-activated sludge by thermal-alkali pretreatment: a pilot-scale study.

The composition of waste-activated sludge (WAS) is complex, containing a large amount of harmful substances, which pose a threat to the environment and human health. The reduction and resource utilization of sludge has become a development demand in sludge treatment and disposal. Based on the technical bottlenecks in the practical application of direct anaerobic digestion technology, this study adopted two different thermal and thermal-alkali hydrolysis technologies to pretreat sludge. A pilot-scale experiment was conducted to investigate the experimental conditions, parameters, and effects of two hydrolysis technologies. This study showed that the optimal hydrolysis temperature was 70 °C, the hydrolysis effect and pH can reach equilibrium with the hydrolysis retention time was 4-8 h, and the optimal alkali concentration range was 0.0125-0.015 kg NaOH/kg dry-sludge. Thermal-alkali combination treatment greatly improved the performance of methane production, the addition of NaOH increased methane yield by 31.2% than that of 70 °C thermal hydrolysis. The average energy consumption is 75 kWh/m3 80% water-content sludge during the experiment. This study provides a better pretreatment strategy for exploring efficient anaerobic digestion treatment technologies suitable for southern characteristic sewage sludge.