Multimodal charting of molecular and functional cell states via in situ electro-sequencing.

Paired mapping of single-cell gene expression and electrophysiology is essential to understand gene-to-function relationships in electrogenic tissues. Here, we developed in situ electro-sequencing (electro-seq) that combines flexible bioelectronics with in situ RNA sequencing to stably map millisecond-timescale electrical activity and profile single-cell gene expression from the same cells across intact biological networks, including cardiac and neural patches. When applied to human-induced pluripotent stem-cell-derived cardiomyocyte patches, in situ electro-seq enabled multimodal in situ analysis of cardiomyocyte electrophysiology and gene expression at the cellular level, jointly defining cell states and developmental trajectories. Using machine-learning-based cross-modal analysis, in situ electro-seq identified gene-to-electrophysiology relationships throughout cardiomyocyte development and accurately reconstructed the evolution of gene expression profiles based on long-term stable electrical measurements. In situ electro-seq could be applicable to create spatiotemporal multimodal maps in electrogenic tissues, potentiating the discovery of cell types and gene programs responsible for electrophysiological function and dysfunction.

Synergistic binding of actinomycin D and echinomycin to DNA mismatch sites and their combined anti-tumour effects.

Combination cancer chemotherapy is one of the most useful treatment methods to achieve a synergistic effect and reduce the toxicity of dosing with a single drug. Here, we use a combination of two well-established anticancer DNA intercalators, actinomycin D (ActD) and echinomycin (Echi), to screen their binding capabilities with DNA duplexes containing different mismatches embedded within Watson-Crick base-pairs. We have found that combining ActD and Echi preferentially stabilised thymine-related T:T mismatches. The enhanced stability of the DNA duplex-drug complexes is mainly due to the cooperative binding of the two drugs to the mismatch duplex, with many stacking interactions between the two different drug molecules. Since the repair of thymine-related mismatches is less efficient in mismatch repair (MMR)-deficient cancer cells, we have also demonstrated that the combination of ActD and Echi exhibits enhanced synergistic effects against MMR-deficient HCT116 cells and synergy is maintained in a MMR-related MLH1 gene knockdown in SW620 cells. We further accessed the clinical potential of the two-drug combination approach with a xenograft mouse model of a colorectal MMR-deficient cancer, which has resulted in a significant synergistic anti-tumour effect. The current study provides a novel approach for the development of combination chemotherapy for the treatment of cancers related to DNA-mismatches.

circ_PPAPDC1A promotes Osimertinib resistance by sponging the miR-30a-3p/ IGF1R pathway in non-small cell lung cancer (NSCLC).

BACKGROUND: Recent evidence has demonstrated that abnormal expression and regulation of circular RNA (circRNAs) are involved in the occurrence and development of a variety of tumors. The aim of this study was to investigate the effects of circ_PPAPDC1A in Osimertinib resistance in NSCLC. METHODS: Human circRNAs microarray analysis was conducted to identify differentially expressed (DE) circRNAs in Osimertinib-acquired resistance tissues of NSCLC. The effect of circ_PPAPDC1A on cell proliferation, invasion, migration, and apoptosis was assessed in both in vitro and in vivo. Dual-luciferase reporter assay, RT-qPCR, Western-blot, and rescue assay were employed to confirm the interaction between circ_PPAPDC1A/miR-30a-3p/IGF1R axis. RESULTS: The results revealed that circ_PPAPDC1A was significantly upregulated in Osimertinib acquired resistance tissues of NSCLC. circ_PPAPDC1A reduced the sensitivity of PC9 and HCC827 cells to Osimertinib and promoted cell proliferation, invasion, migration, while inhibiting apoptosis in Osimertinib-resistant PC9/OR and HCC829/OR cells, both in vitro and in vivo. Silencing circ_PPAPDC1A partially reversed Osimertinib resistance. Additionally, circ_PPAPDC1A acted as a competing endogenous RNA (ceRNA) by targeting miR-30a-3p, and Insulin-like Growth Factor 1 Receptor (IGF1R) was identified as a functional gene for miR-30a-3p in NSCLC. Furthermore, the results confirmed that circ_PPAPDC1A/miR-30a-3p/IGF1R axis plays a role in activating the PI3K/AKT/mTOR signaling pathway in NSCLC with Osimertinib resistance. CONCLUSIONS: Therefore, for the first time we identified that circ_PPAPDC1A was significantly upregulated and exerts an oncogenic role in NSCLC with Osimertinib resistance by sponging miR-30a-3p to active IGF1R/PI3K/AKT/mTOR pathway. circ_PPAPDC1A may serve as a novel diagnostic biomarker and therapeutic target for NSCLC patients with Osimertinib resistance.

Postoperative Bisphosphonates Use is Associated with Reduced Adverse Outcomes After Primary Total Joint Arthroplasty of Hip and Knee: A Nationwide Population-Based Cohort Study.

Bisphosphonates have been associated with a decreased risk of revision surgery after total joint arthroplasty of the hip or knee (TJA) because of their effects on decreased periprosthetic bone loss and prosthetic migration. However, the results in the early literature are inconsistent, and the influence of bisphosphonates on associated complications and subsequent TJA remains unknown. This study investigated the association between the use of bisphosphonates and the risk of adverse outcomes after primary TJA. This matched cohort study utilized the National Health Insurance Research Database in Taiwan to identify patients who underwent primary TJA over a 15-year period (January 2000-December 2015 inclusive). Study participants were further categorized into two groups, bisphosphonate users and nonusers, using propensity score matching. The Kaplan-Meier curve analysis and adjusted hazard ratios (aHRs) of revision surgery, adverse outcomes of primary surgery and subsequent TJA were calculated using Cox regression analysis. This study analyzed data from 6485 patients who underwent total hip arthroplasty (THA) and 20,920 patients who underwent total knee arthroplasty (TKA). The risk of revision hip and knee arthroplasty was significantly lower in the bisphosphonate users than in the nonusers (aHR, 0.54 and 0.53, respectively). Furthermore, the risk of a subsequent total joint arthroplasty, adverse events and all-cause mortality were also significantly reduced in the bisphosphonate users. This study, involving a large cohort of patients who underwent primary arthroplasties, revealed that bisphosphonate treatment may potentially reduce the risk of revision surgery and associated adverse outcomes. Furthermore, the use of bisphosphonates after TJA is also associated with a reduced need for subsequent arthroplasty.Research Registration Unique Identifying Number (UIN): ClinicalTrials.gov Identifier-NCT05623540 ( https://clinicaltrials.gov/show/NCT05623540 ).

NOTCH pathway mutation contributes to inferior prognosis in HBV-infected chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) patients with hepatitis B virus (HBV) infection have a poor prognosis, underlying mechanism remains unclear. NOTCH mutations are frequent in CLL and associated with disease progression and drug resistance. It is also reported to be associated with hepatitis infection in lymphoid malignancies. In order to investigate the relation between the NOTCH pathway and HBV-associated CLL, we studied 98 previously untreated HBV-positive CLL patients and 244 HBV-negative CLL. NOTCH mutations were more frequent in HBV-positive CLL subgroup (p = 0.033). By survival analysis, HBV infection was associated with disease progression and poor survival (p = 0.0099 for overall survival (OS) and p = 0.0446 for time-to-treatment (TTT)). Any lesions of the NOTCH pathway (NOTCH1, NOTCH2, and SPEN) aggravated prognosis. In multivariate analysis, NOTCH mutation retained an independent significance for HBV-infected patients (p = 0.016 for OS and p = 0.023 for TTT). However, HBV positive with NOTCH unmutated had no statistical difference in prognosis compared with HBV-negative patients (p = 0.1706 for OS and p = 0.2387 for TTT), which indicated that NOTCH pathway mutation contributed to inferior prognosis in HBV-infected CLL. In conclusion, a cohort of CLL patients with HBV positive displayed a worse clinical outcome and the status of the NOTCH signaling pathway might play a crucial role.

Cholesterol suppresses AMFR-mediated PDL1 ubiquitination and degradation in HCC.

The degradation of proteasomes or lysosomes is emerging as a principal determinant of programmed death ligand 1 (PDL1) expression, which affects the efficacy of immunotherapy in various malignancies. Intracellular cholesterol plays a central role in maintaining the expression of membrane receptors; however, the specific effect of cholesterol on PDL1 expression in cancer cells remains poorly understood. Cholesterol starvation and stimulation were used to modulate the cellular cholesterol levels. Immunohistochemistry and western blotting were used to analyze the protein levels in the samples and cells. Quantitative real-time PCR, co-immunoprecipitation, and confocal co-localization assays were used for mechanistic investigation. A xenograft tumor model was constructed to verify these results in vivo. Our results showed that cholesterol suppressed the ubiquitination and degradation of PDL1 in hepatocellular carcinoma (HCC) cells. Further mechanistic studies revealed that the autocrine motility factor receptor (AMFR) is an E3 ligase that mediated the ubiquitination and degradation of PDL1, which was regulated by the cholesterol/p38 mitogenic activated protein kinase axis. Moreover, lowering cholesterol levels using statins improved the efficacy of programmed death 1 (PD1) inhibition in vivo. Our findings indicate that cholesterol serves as a signal to inhibit AMFR-mediated ubiquitination and degradation of PDL1 and suggest that lowering cholesterol by statins may be a promising combination strategy to improve the efficiency of PD1 inhibition in HCC.

An automatic system for recognizing fly courtship patterns via an image processing method.

Fruit fly courtship behaviors composed of a series of actions have always been an important model for behavioral research. While most related studies have focused only on total courtship behaviors, specific courtship elements have often been underestimated. Identifying these courtship element details is extremely labor intensive and would largely benefit from an automatic recognition system. To address this issue, in this study, we established a vision-based fly courtship behavior recognition system. The system based on the proposed image processing methods can precisely distinguish body parts such as the head, thorax, and abdomen and automatically recognize specific courtship elements, including orientation, singing, attempted copulation, copulation and tapping, which was not detectable in previous studies. This system, which has high identity tracking accuracy (99.99%) and high behavioral element recognition rates (> 97.35%), can ensure correct identification even when flies completely overlap. Using this newly developed system, we investigated the total courtship time, and proportion, and transition of courtship elements in flies across different ages and found that male flies adjusted their courtship strategy in response to their physical condition. We also identified differences in courtship patterns between males with and without successful copulation. Our study therefore demonstrated how image processing methods can be applied to automatically recognize complex animal behaviors. The newly developed system will largely help us investigate the details of fly courtship in future research.

Molecular cloning and functional characterization of eight galectin genes from Takifugu obscurus.

Galectins are a family of animal lectins involved in the immune response against pathogens. However, the roles of fish galectins during pathogen infection require comprehensive studies. In the present research, eight different galectin genes from Takifugu obscurus (named ToGalec1-8) were identified and characterized. ToGalec1-8 encoded proteins of 240, 182, 373, 145, 452, 135, 359 and 346 amino acids, respectively. All predicted ToGalec1-8 proteins possessed one or more conserved carbohydrate recognition domains (CRDs). Phylogenetic analysis revealed that ToGalec1-8 were evolutionarily closely related to their counterparts in other selected vertebrates, hinting their genetic relationship. Tissue distribution analysis showed that most ToGalec genes were distributed ubiquitously in all detected tissues, with relatively high expression in immune tissues. After stimulation by Vibrio harveyi and Staphylococcus aureus, the mRNA transcripts of ToGalec1-8 in liver and kidney were significantly upregulated. In addition, RNA interference experiments indicated that knockdown of ToGalec1 and ToGalec7 inhibited the clearance of bacteria in vivo. Taken together, these obtained results suggested that ToGalec1-8 play an important role in innate immunity and defense against bacterial infection in T. obscurus.

3D-printed polycaprolactone scaffolds coated with beta tricalcium phosphate for bone regeneration.

BACKGROUND/PURPOSE: 3D-printing technology is an important tool for the bone tissue engineering (BTE). The aim of this study was to investigate the interaction of polycaprolactone (PCL) scaffolds and modified mesh PCL coated with beta TCP (PCL/ß-TCP) scaffolds with MG-63. METHODS: This study used the fused deposition modeling (FDM) technique with the 3D printing technique to fabricate the thermoplastic polymer and composite scaffolds. Scaffold structure and coating quality were observed under a scanning electron microscope (SEM). MG-63 cells were injected and attached to the mesh-manufactured PCL scaffolds. The biocompatibility of mesh structured PCL and PCL/ß-TCP scaffolds could be examined by measuring the viability of MG-63 cells of MTT assay. Bone cell differentiation was evaluated ALP activity by mineralization assay. RESULTS: The results showed that both mesh PCL scaffolds and PCL/ß-TCP scaffolds were non-toxic to the cells. The ALP activities of cells in PCL/ß-TCP scaffolds groups were significant differences and better than PCL groups in all groups at all experimental dates. The mineralization process was time-dependent, and significantly higher mineralization of osteosarcoma cells was observed on PCL/ß-TCP scaffolds at experimental dates. CONCLUSION: We concluded that both meshes structured PCL and PCL/ß-TCP scaffolds could promote the MG-63 cell growth, and PCL/ß-TCP was better than the PCL scaffolds for the outcome of MG63 cell differentiation and mineralization.

Tracking household carbon inequality in China: Composition effect or coefficient effect?

Reasonable allocation of carbon emission reduction tasks requires addressing household carbon inequality. This study aims to track characteristics of household carbon inequality in China using the recentered influence function (RIF) based on the Household Tracking Survey data in 2018 and the multi-regional input-output table. The Oaxaca-Binder decomposition based on RIF further decomposes household carbon inequality based on spatial heterogeneity into composition and coefficient effects. The results indicate that (1) household carbon inequality is widespread in China, generally close to the 60/30 distribution, favouring high-income families. Furthermore, (2) increases in income, wealth and economic burden and declining marriage rate promote household carbon inequality, which is suppressed by the development of education and the Internet and the increase in car ownership. Additionally, (3) the carbon inequality of urban households is smaller than that of rural households, which is contributed by the composition effects of family size, education, car ownership, Internet development and the coefficient effect of income and housing. Finally, (4) under the composition effect of family size and the coefficient effect of income, the household carbon inequality in the eastern region is smaller than in the central and western regions.

Environmental risks and sphingolipid signatures in adult asthma and its phenotypic clusters: a multicentre study.

BACKGROUND: Adult asthma is phenotypically heterogeneous with unclear aetiology. We aimed to evaluate the potential contribution of environmental exposure and its ensuing response to asthma and its heterogeneity. METHODS: Environmental risk was evaluated by assessing the records of National Health Insurance Research Database (NHIRD) and residence-based air pollution (particulate matter with diameter less than 2.5 micrometers (PM2.5) and PM2.5-bound polycyclic aromatic hydrocarbons (PAHs)), integrating biomonitoring analysis of environmental pollutants, inflammatory markers and sphingolipid metabolites in case-control populations with mass spectrometry and ELISA. Phenotypic clustering was evaluated by t-distributed stochastic neighbor embedding (t-SNE) integrating 18 clinical and demographic variables. FINDINGS: In the NHIRD dataset, modest increase in the relative risk with time-lag effect for emergency (N=209 837) and outpatient visits (N=638 538) was observed with increasing levels of PM2.5 and PAHs. Biomonitoring analysis revealed a panel of metals and organic pollutants, particularly metal Ni and PAH, posing a significant risk for current asthma (ORs=1.28-3.48) and its severity, correlating with the level of oxidative stress markers, notably Nε-(hexanoyl)-lysine (r=0.108-0.311, p<0.05), but not with the accumulated levels of PM2.5 exposure. Further, levels of circulating sphingosine-1-phosphate and ceramide-1-phosphate were found to discriminate asthma (p<0.001 and p<0.05, respectively), correlating with the levels of PAH (r=0.196, p<0.01) and metal exposure (r=0.202-0.323, p<0.05), respectively, and both correlating with circulating inflammatory markers (r=0.186-0.427, p<0.01). Analysis of six phenotypic clusters and those cases with comorbid type 2 diabetes mellitus (T2DM) revealed cluster-selective environmental risks and biosignatures. INTERPRETATION: These results suggest the potential contribution of environmental factors from multiple sources, their ensuing oxidative stress and sphingolipid remodeling to adult asthma and its phenotypic heterogeneity.

YEATS2 regulates the activation of TAK1/NF-κB pathway and is critical for pancreatic ductal adenocarcinoma cell survival.

The prognosis of pancreatic ductal adenocarcinoma (PDAC) is poor despite diagnostic progress and new chemotherapeutic regimens. Constitutive activation of NF-κB is frequently observed in PDAC. In this study, we found that YEATS2, a scaffolding protein of ATAC complex, was highly expressed in human PDAC. Depletion of YEATS2 reduced the growth, survival, and tumorigenesis of PDAC cells. The binding of YEATS2 is crucial for maintaining TAK1 activation and NF-κB transcriptional activity. Of importance, our results reveal that YEATS2 promotes NF-κB transcriptional activity through modulating TAK1 abundance and directly interacting with NF-κB as a co-transcriptional factor.

Physical mechanism on the linear spectrum and nonlinear spectrum in a twist bilayer graphdiyne nanodisk.

The one-photon absorption properties (OPA), two-photon absorption properties (TPA), electronic circular dichroism (ECD) spectra and partial DOS (PDOS) of a twist bilayer graphdiyne nanodisk (TwBLGDY-ND) were investigated by using a variety of quantum chemistry and wave function analyses. The physical mechanism of the twist bilayer graphdiyne nanodisk (TwBLGDY) with optical properties regulated by twisting angles was revealed. The results show that the twist angle makes the TwBLGDY form a moiré superlattice structure, and electron excitation mainly occurs in the first ring of the moiré superlattice structure. The contribution of atomic orbitals in these fragments to transition dipole moments is greater and electronic transitions are more likely to occur. When the twist angle increases from 0° to 15°, the absorption spectrum of the system is red shifted, which is mainly due to the enhancement of electron excitation characteristics. When the twist angle increases from 15° to 27.5°, the absorption spectrum of the system is blue shifted, due to the enhanced charge transfer within the layer. On the other hand, the twist angle can regulate the TPA absorption cross section of the system to enhance the intensity of the absorption spectrum. The twist angle can also regulate chirality by adjusting the spatial distribution of electric dipole transition and magnetic dipole transition. This study can provide theoretical guidance for constructing chiral optical devices based on the TwBLGDY structure.

The Hyoid Bone Kinematics in Dysphagic Stroke Patients: Instantaneous Velocity, Acceleration and Temporal Sequence Matters.

Hyoid bone excursion (HBE) is one of the most critical events in the pharyngeal phase of swallowing. Most previous studies focused on the total displacement and average velocity of HBE. However, HBE during swallowing is not one-dimensional, and the change of velocity and acceleration is not linear. This study aims to elucidate the relationship between the instantaneous kinematics parameters of HBE and the severity of penetration/aspiration and pharyngeal residue in patients with stroke. A total of 132 sets of video-fluoroscopic swallowing study images collected from 72 dysphagic stroke patients were analyzed. The maximal instantaneous velocity, acceleration, displacement, and the time required to reach these values in the horizontal and vertical axes were measured. Patients were grouped according to the severity of the Penetration-Aspiration Scale and the Modified Barium Swallow Impairment Profile- Pharyngeal Residue. The outcome was then stratified according to the consistencies of swallowing materials. Stroke patients with aspiration were associated with a lower maximal horizontal instantaneous velocity and acceleration of HBE, a shorter horizontal displacement, and prolonged time to maximal vertical instantaneous velocity compared to the non-aspirators. In patients with pharyngeal residue, the maximal horizontal displacement of HBE was decreased. After stratification according to bolus consistencies, the temporal parameters of HBE were more significantly associated with aspiration severity when swallowing thin bolus. Meanwhile spatial parameters such as displacement had a bigger influence on aspiration severity when swallowing viscous bolus. These novel kinematic parameters of HBE could provide important reference for estimating swallowing function and outcomes in dysphagic stroke patients.

Deep Learning for Automatic Hyoid Tracking in Videofluoroscopic Swallow Studies.

The hyoid bone excursion is one of the most important gauges of larynx elevation in swallowing, contributing to airway protection and bolus passage into the esophagus. However, the implications of various parameters of hyoid bone excursion, such as the horizontal or vertical displacement and velocity, remain elusive and raise the need for a tool providing automatic kinematics analysis. Several conventional and deep learning-based models have been applied automatically to track the hyoid bone, but previous methods either require partial manual localization or do not transform the trajectory by anatomic axis. This work describes a convolutional neural network-based algorithm featuring fully automatic hyoid bone localization and tracking and spine axis determination. The algorithm automatically estimates the hyoid bone trajectory and calculates several physical quantities, including the average velocity and displacement in horizontal or vertical anatomic axis. The model was trained in a dataset of 365 videos of videofluoroscopic swallowing from 189 patients in a tertiary medical center and tested using 44 videos from 44 patients with different dysphagia etiologies. The algorithm showed high detection rates for the hyoid bone. The results showed excellent inter-rater reliability for hyoid bone detection, good-to-excellent inter-rater reliability for calculating the maximal displacement and the average velocity of the hyoid bone in horizontal or vertical directions, and moderate-to-good reliability in calculating the average velocity in horizontal direction. The proposed algorithm allows for complete automatic kinematic analysis of hyoid bone excursion, providing a versatile tool with high potential for clinical applications.

The influence on surface characteristic and biocompatibility of nano-SnO2-modified titanium implant material using atomic layer deposition technique.

BACKGROUND/PURPOSE: To investigate the surface characteristics of titanium (Ti) implant materials, which were coated with different thicknesses of nanoscale tin oxide (SnO2) using the atomic layer deposition technique, and evaluated its biological performance on human embryonic palatal mesenchyme (HEPM) cells. METHODS: The thickness of the coating layer on Ti was 0 (Ti0), 20 nm (Ti20), 50 nm (Ti50), and 100 nm (Ti100), respectively. The surface morphology was observed with an SEM and AFM. The root mean square roughness of micron-scale (mRq) and nanoroughness (nRq) of Ti discs' surface were measured. The Alamar blue (AB) assay and F-actin fluorescence staining were used to evaluate the biocompatibility, and the osteocalcin (OCN) was measured to clarify the differentiation of HEPM cells on materials. RESULTS: In the coating groups, the mRq was decreased, but the nRq was increased. The spreading and polygonal morphology of HEPMs was apparent in coating groups. On Day 4, the survival rate of HEPM cells on Ti0 was higher than on Ti20 and Ti50. There was no significant difference on Day 7, Day 10, and Day 14. The OCN was significantly higher on Day 14 in all the coating groups than Ti0. CONCLUSION: The results showed that the cell growth was intensified with rough surfaces. However, the OCN and morphology change was prominent when the nanoroughness was increased, which meant the increased nanoroughness might enhance OCN production and improve the tendency of osseointegration. The nanoscale SnO2 coating could increase the ability of bone formation but not cell growth.

Fusion of Multi-Modal Features to Enhance Dense Video Caption.

Dense video caption is a task that aims to help computers analyze the content of a video by generating abstract captions for a sequence of video frames. However, most of the existing methods only use visual features in the video and ignore the audio features that are also essential for understanding the video. In this paper, we propose a fusion model that combines the Transformer framework to integrate both visual and audio features in the video for captioning. We use multi-head attention to deal with the variations in sequence lengths between the models involved in our approach. We also introduce a Common Pool to store the generated features and align them with the time steps, thus filtering the information and eliminating redundancy based on the confidence scores. Moreover, we use LSTM as a decoder to generate the description sentences, which reduces the memory size of the entire network. Experiments show that our method is competitive on the ActivityNet Captions dataset.

Orbital Polarization-Dependent Fragment Twist-Induced Intramolecular Electric-Field-Driven Charge Transfer.

Defects, such as twisting, in fused aromatic hydrocarbons disrupt the plane of the π orbital. The twisted structure induces an electric field in the system and affects the spectra. In this work, theoretical studies show that the intramolecular electric field within a distinctly twisted structure is larger than that of other molecules. In addition, the spectral study shows that the degree of charge transfer and the magnetic transition dipole in the electrostatic potential extremum region of the molecular electric field were significantly improved, which affected the optical absorption and chiral optical behavior of the molecule. The discovery of this theoretical regulation law will provide a solid foundation for the electric-field-induced regulation of optical properties and will promote the precise design and synthesis of optoelectronic molecules with inner electric fields.

Vertical Stress Induced Anomalous Spectral Shift of 13.17° Moiré Superlattice in Twist Bilayer Graphene.

The electronic states of the twist bilayer graphene (TBG) moiré superlattice are usually regulated by the rotation angle, applied electric field, applied magnetic field, carrier concentration and applied stress, and thus exhibit novel physical properties. Squeezing, that is, applying vertical compressive stress to the graphene layers, has profound significance in regulating the photoelectric properties of the moiré superlattice and constructing optical nanodevices. This paper presents the photoelectric properties of a TBG moiré superlattice with a twist angle of 13.17° and tunability under vertical stress. Interlayer distance decreases nonlinearly with compressive stress from 0 to 10 GPa, giving rise to weakened interlayer coupling compared to a Bernal-stacked graphene bilayer and an enhanced repulsive effect between the layers. The calculated Bloch wave functions show a strong dependence on stress. With the increase in stress, the band gaps of the system present a nonlinear increase, which induces and enhances the interlayer charge transfer and leads to the redshift of the absorption spectrum of the moiré superlattice system. By analyzing the differences in the Bloch wave function and charge density differences, we explain the nature of the physical mechanism of photoelectric property change in a stress-regulated twist superlattice system. This study provides a theoretical basis for the identification of piezoelectric properties and the stress regulation of photoelectric devices based on TBG, and also provides a feasible method for regulating the performance of TBG.

Physical Mechanism of Nonlinear Spectra in Triangene.

In this work, we theoretically investigate the linear and nonlinear optical absorption properties of open triangulene spin chains and cyclic triangulene spin chains in relation to their lengths and shapes. The physical mechanism of local excitation within the triangular alkene unit and the weak charge transfer between the units are discussed. The uniformly distributed electrostatic potential allows the system to have a small permanent dipole moment that blocks the electronic transition in the light excitation such that the electronic transition can only be carried out between adjacent carbon atoms. The one-photon absorption (OPA) spectra and two-photon absorption (TPA) spectra are red-shifted with the addition of triangulene units compared to N = 3TSCs (triangulene spin chains, TSCs). Here, TPA is mainly caused by the first step of the transition. The length of the spin chain has a significant adjustment effect on the photon cross-section. TSCs of different lengths and shapes can control chirality by adjusting the distribution of the electric dipole moment and transition magnetic dipole moment. These analyses reveal the photophysical properties of triangulene and provide a theoretical basis for studying the photophysical properties of triangulene and its derivatives.