Negative Differential Resistance with Ultralow Peak-to-Valley Voltage Difference in Td-WTe2/2H-MoS2 Heterostructure.

Negative differential resistance (NDR) devices with a low peak-to-valley voltage difference (ΔV) exhibit a high cut off frequency and low power consumption efficiency, which is significant for fabricating high-performance oscillators. However, achieving an ultralow ΔV is challenging. In this work, we report the first construction of an NDR device utilizing a van der Waals heterostructure composed of semimetallic Td-WTe2 and semiconducting 2H-MoS2. Our findings reveal that the narrow energy region of the decreasing density of states (DOS) above the Fermi level of WTe2 acts as a narrow band gap, facilitating type-III band alignment with MoS2 and enabling band-to-band tunneling-based NDR transport. Notably, the NDR device exhibits an ultralow ΔV of approximately 0.01 V, which is at least an order of magnitude lower than previously reported values. This work not only introduces a new approach for NDR device fabrication but also provides new insights into the pivotal role of Td-WTe2 in NDR transport.

The Mass-Balancing between Positive and Negative Electrodes for Optimizing Energy Density of Supercapacitors.

Supercapacitors (SCs) are some of the most promising energy storage devices, but their low energy density is one main weakness. Over the decades, superior electrode materials and suitable electrolytes have been widely developed to enhance the energy storage ability of SCs. Particularly, constructing asymmetric supercapacitors (ASCs) can extend their electrochemical stable voltage windows (ESVWs) and thus achieve high energy density. However, only full utilization of the electrochemical stable potential windows (ESPWs) of both positive and negative electrodes can endow the ASC devices with a maximum ESVW by using a suitable mass-ratio between two electrodes (the mass-balancing). Nevertheless, insufficient attention is directed to mass-balancing, and even numerous misunderstandings and misuses have appeared. Therefore, in this Perspective, we focus on the mass-balancing: summarize theoretic basis of the mass-balancing, derive relevant relation equations, analyze and discuss the change trends of the specific capacitance and energy density of ASCs with mass-ratios, and finally recommend some guidelines for the normative implementation of the mass-balancing. Especially, the issues related to pseudocapacitive materials, hybrid devices, and different open circuit potentials (OCPs) of the positive and negative electrodes in the mass-balancing are included and emphasized. These analyses and guidelines can be conducive to understanding and performing mass-balancing for developing high-performance SCs.

The role of vitamin D receptor in predentin mineralization and dental repair after injury.

Dentin is a permeable and complex tubular composite formed by the mineralization of predentin that mineralization and repair are of considerable clinical interest during dentin homeostasis. The role of Vdr, a receptor of vitamin D, in dentin homeostasis remains unexplored. The aim of the present study was to assess the impact of Vdr on predentin mineralization and dental repair. Vdr-knockout (Vdr-/-) mice models were constructed; histology and immunohistochemistry analyses were conducted for both WT and Vdr-/- mice. The finding revealed a thicker predentin in Vdr-/- mice, characterized by higher expression of biglycan and decorin. A dental injury model was employed to observe tertiary dentin formation in Vdr-/- mice with dental injuries. Results showed that tertiary dentin was harder to form in Vdr-/- mice with dental injury. Over time, heightened pulp invasion was observed at the injury site in Vdr-/- mice. Expression of biglycan and decorin was reduced in the predentin at the injury site in the Vdr-/- mice by immunohistochemistry. Taken together, our results imply that Vdr plays a regulatory role in predentin mineralization and tertiary dentin formation during dentin homeostasis.

High accuracy ranging for space debris with spaceborne single photon Lidar.

The increasing risk posed by space debris highlights the need for accurate localization techniques. Spaceborne single photon Lidar (SSPL) offers a promising solution, overcoming the limitations of traditional ground-based systems by providing expansive coverage and superior maneuverability without being hindered by weather, time, or geographic constraints. This study introduces a novel approach leveraging non-parametric Bayesian inference and the Dirichlet process mixture model (DPMM) to accurately determine the distance of space debris in low Earth orbit (LEO), where debris exhibits nonlinear, high dynamic motion characteristics. By integrating extended Kalman filtering (EKF) for range gating, our method captures the temporal distribution of reflected photons, employing Markov chain Monte Carlo (MCMC) for iterative solutions. Experimental outcomes demonstrate our method's superior accuracy over conventional statistical techniques, establishing a clear correlation between radial absolute velocity and ranging error, thus significantly enhancing monostatic space debris localization.

Ce Single-Atom Incorporation Enhances the Oxygen Evolution Reaction of Co3O4 in Acid.

Oxygen evolution reaction (OER) plays an important role in energy conversion processes such as water electrolysis and metal-air batteries. At present, finding a high-performance and low-cost catalyst for the OER in acidic media remains a great challenge. It is therefore important to develop efficient, robust, and inexpensive electrocatalysts by replacing noble metal-based catalysts with transition-metal electrocatalysts. Herein, we propose a facile method for incorporating Ce-metal single atoms into Co3O4 nanosheets to boost their OER activity and stability. Owing to the enhanced charge transfer and improved electronic structure resulting from Ce incorporation, the obtained Ce single-atom-doped Co3O4 nanosheet exhibits greatly enhanced OER performance. It achieves a 10 mA cm-2 current density under a low overpotential of 348 mV in a 0.5 M H2SO4 solution with excellent stability, outperforming the state-of-the-art non-noble electrocatalysts recently reported in acid.

Anisotropic sensing based on single ReS2flake for VOCs discrimination.

Selective and sensitive detection of volatile organic compounds (VOCs) holds paramount importance in real-world applications. This study proposes an innovative approach utilizing a single ReS2field-effect transistor (FET) characterized by distinct in-plane anisotropy, specifically tailored for VOC recognition. The unique responses of ReS2, endowed with robust in-plane anisotropic properties, demonstrate significant difference along thea-axis andb-axis directions when exposed to four kinds of VOCs: acetone, methanol, ethanol, and IPA. Remarkably, the responses of ReS2were significantly magnified under ultraviolet (UV) illumination, particularly in the case of acetone, where the response amplified by 10-15 times and the detection limit decreasing from 70 to 4 ppm compared to the dark conditions. Exploiting the discernible variances in responses along thea-axis andb-axis under both UV and dark conditions, the data points of acetone, ethanol, methanol and IPA gases were clearly separated in the principal component space without any overlap through principal component analysis, indicating that the single ReS2FET has a high ability to distinguish various gas species. The exploration of anisotropic sensing materials and light excitation strategies can be applied to a broad range of sensing platforms based on two-dimensional materials for practical applications.

Design and tribological performance of graphene nanofluids dispersed by dragging effect of bicomponent gelator.

Nanofluids have excellent lubrication and high thermal conductivity. However, the agglomeration and sedimentation produced by the large surface energy of nanoparticles in base liquid threaten the long-term dispersion stability and impact the wide application of nanofluid. In this work, based on the self-assemble behavior and continuous network structure formed by low molecular weight organic gelator, the uniform clusters were formed through regulating the kinetics behavior in the gelling process. The dragging effect was demonstrated by oleic acid - sodium dodecyl sulfate (OA-SDS) bicomponent gelator and graphene oxide (GO) nanosheets. The results showed that GO nanofluids dispersed by OA-SDS were stable for more than 12 months. The well-dispersed GO nanofluid exhibited better anti-friction and anti-wear properties under both immersion and electrostatic minimum quantity lubrication conditions. Moreover, the lower contact angle, surface tension and droplet size of nanofluids after charging improved the wettability on the frictional interface. The GO adsorption film formed on the friction interface protected the tribochemical reaction film of iron oxide and prevented the occurrence of sintering of base oil.

Fruit but not vegetable consumption is beneficial for low prevalence of colorectal polyps in a high-risk population: findings from a Chinese Lanxi Pre-colorectal Cancer Cohort study.

PURPOSE: The available evidence regarding the role of fruit and vegetable consumption in the development of colorectal polyps remains inconclusive, and there is a lack of data on different histopathologic features of polyps. We aimed to evaluate the associations of fruit and vegetable consumption with the prevalence of colorectal polyps and its subtypes in a high-risk population in China. METHODS: We included 6783 Chinese participants aged 40-80 years who were at high risk of colorectal cancer (CRC) in the Lanxi Pre-colorectal Cancer Cohort (LP3C). Dietary information was obtained through a validated food-frequency questionnaire (FFQ), and colonoscopy screening was used to detect colorectal polyps. Dose-response associations of fruit and vegetable intake with the prevalence of polyps were calculated using multivariate-adjusted regression models, which was reported as odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: 2064 cases of colorectal polyps were ascertained in the LP3C during 2018-2019. Upon multivariable adjustments, including the diet quality, fruit consumption was inversely associated with the prevalence of polyps (P trend = 0.02). Participants in the highest tertile of fruit intake had a 25% lower risk (OR: 0.75; 95% CI 0.62‒0.92) compared to non-consumers, while vegetable consumption had no significant association with polyp prevalence (P trend = 0.86). In terms of colorectal histopathology and multiplicity, higher fruit intake was correlated with 24, 23, and 33% lower prevalence of small polyps (OR: 0.76; 95% CI 0.62‒0.94; P trend = 0.05), single polyp (OR: 0.77; 95% CI 0.62‒0.96; P trend = 0.04), and distal colon polyps (OR: 0.67; 95% CI 0.51‒0.87; P trend = 0.003), respectively. CONCLUSIONS: Fresh fruit is suggested as a protective factor to prevent colorectal polyps in individuals at high risk of CRC, and should be underscored in dietary recommendations, particularly for high-risk populations.

Construction of an artificial neural network diagnostic model and investigation of immune cell infiltration characteristics for idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a severe lung condition, and finding better ways to diagnose and treat the disease is crucial for improving patient outcomes. Our study sought to develop an artificial neural network (ANN) model for IPF and determine the immune cell types that differed between the IPF and control groups. METHODS: From the Gene Expression Omnibus (GEO) database, we first obtained IPF microarray datasets. To conduct protein-protein interaction (PPI) networks and enrichment analyses, differentially expressed genes (DEGs) were screened between tissues of patients with IPF and tissues of controls. Afterward, we identified the important feature genes associated with IPF using random forest (RF) analysis, and then constructed and validated a prediction ANN mode. In addition, the proportions of immune cells were quantified using cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT) analysis, which was performed on microarray datasets based on gene expression profiling. RESULTS: A total of 11 downregulated and 36 upregulated DEGs were identified. PPI networks and enrichment analyses were carried out; the immune system and extracellular matrix were the subjects of the enrichments. Using RF analysis, the significant feature genes LRRC17, COMP, ASPN, CRTAC1, POSTN, COL3A1, PEBP4, IL13RA2, and CA4 were identified. The nine feature gene scores were integrated into the ANN to develop a diagnostic prediction model. The receiver operating characteristic (ROC) curves demonstrated the strong diagnostic ability of the ANN in predicting IPF in the training and testing sets. An analysis of IPF tissues in comparison to normal tissues revealed a reduction in the infiltration of natural killer cells resting, monocytes, macrophages M0, and neutrophils; conversely, the infiltration of T cells CD4 memory resting, mast cells, and macrophages M0 increased. CONCLUSION: LRRC17, COMP, ASPN, CRTAC1, POSTN, COL3A1, PEBP4, IL13RA2, and CA4 were determined as key feature genes for IPF. The nine feature genes in the ANN model will be extremely important for diagnosing IPF. It may be possible to use differentiated immune cells from IPF samples in comparison to normal samples as targets for immunotherapy in patients with IPF.

Elucidating the intricacies of the H2S signaling pathway in gasotransmitters: Highlighting the regulation of plant thiocyanate detoxification pathways.

In recent decades, there has been increasing interest in elucidating the role of sulfur-containing compounds in plant metabolism, particularly emphasizing their function as signaling molecules. Among these, thiocyanate (SCN-), a compound imbued with sulfur and nitrogen, has emerged as a significant environmental contaminant frequently detected in irrigation water. This compound is known for its potential to adversely impact plant growth and agricultural yield. Although adopting exogenous SCN- as a nitrogen source in plant cells has been the subject of thorough investigation, the fate of sulfur resulting from the assimilation of exogenous SCN- has not been fully explored. There is burgeoning curiosity in probing the fate of SCN- within plant systems, especially considering the possible generation of the gaseous signaling molecule, hydrogen sulfide (H2S) during the metabolism of SCN-. Notably, the endogenous synthesis of H2S occurs predominantly within chloroplasts, the cytosol, and mitochondria. In contrast, the production of H2S following the assimilation of exogenous SCN- is explicitly confined to chloroplasts and mitochondria. This phenomenon indicates complex interplay and communication among various subcellular organelles, influencing signal transduction and other vital physiological processes. This review, augmented by a small-scale experimental study, endeavors to provide insights into the functional characteristics of H2S signaling in plants subjected to SCN--stress. Furthermore, a comparative analysis of the occurrence and trajectory of endogenous H2S and H2S derived from SCN--assimilation within plant organisms was performed, providing a focused lens for a comprehensive examination of the multifaceted roles of H2S in rice plants. By delving into these dimensions, our objective is to enhance the understanding of the regulatory mechanisms employed by the gasotransmitter H2S in plant adaptations and responses to SCN--stress, yielding invaluable insights into strategies for plant resilience and adaptive capabilities.

Fluctuations in resting motor threshold during electroconvulsive and magnetic seizure therapy.

OBJECTIVES: Magnetic seizure therapy (MST) is more benign than electroconvulsive therapy (ECT) in terms of cognitive impairment. However, whether these two 'artificial seizures' facilitate the central motor neural pathway and the motor cortical effects have not been investigated. The study aimed to compare the effects of ECT and MST on motor-evoked potential (MEP) in patients with mental disorders. METHODS: Forty-nine patients with mental disorders (major depressive disorder, bipolar disorder type II and schizophrenia [SCZ]) received 6 treatment sessions of vertex MST versus 6 bifrontal ECT treatments in a nonrandomized comparative clinical design. Data on the duration of motor seizures were collected for each treatment. MEP latency and the resting motor threshold (rMT) were measured at baseline and after every two treatments. Comparisons were performed between or within the groups. RESULTS: Seizure durations were significantly longer in the ECT group compared to the MST group across multiple sessions. Both MST and ECT demonstrated a significant reduction in rMT in the left and right hemispheres after the fourth (T3) and sixth treatments (T4) compared to baseline (T1). However, there were no significant changes in MEP latency within or between the groups throughout the treatment sessions. The only difference was that the rMT in the left cerebral hemisphere was significantly lower after T4 than after the second treatment (T2). There was no difference in rMT between the ECT and MST groups. CONCLUSIONS: Both ECT and MST facilitate the central motor pathway, with a shared mechanism of increased motor cortex excitability.

Improving the Signal-to-Noise Ratio of Axial Displacement Measurements of Microspheres Based on Compound Digital Holography Microscopy Combined with the Reconstruction Centering Method.

In 3D microsphere tracking, unlike in-plane motion that can be measured directly by a microscope, axial displacements are resolved by optical interference or a diffraction model. As a result, the axial results are affected by the environmental noise. The immunity to environmental noise increases with measurement accuracy and the signal-to-noise ratio (SNR). In compound digital holography microscopy (CDHM)-based measurements, precise identification of the tracking marker is critical to ensuring measurement precision. The reconstruction centering method (RCM) was proposed to suppress the drawbacks caused by installation errors and, at the same time, improve the correct identification of the tracking marker. The reconstructed center is considered to be the center of the microsphere, rather than the center of imaging in conventional digital holographic microscopy. This method was verified by simulation of rays tracing through microspheres and axial moving experiments. The axial displacements of silica microspheres with diameters of 5 µm and 10 µm were tested by CDHM in combination with the RCM. As a result, the SNR of the proposed method was improved by around 30%. In addition, the method was successfully applied to axial displacement measurements of overlapped microspheres with a resolution of 2 nm.

Analysis of treatment-related adverse events and wound complications of surgical resection after neoadjuvant chemoimmunotherapy for non-small cell lung cancer.

Neoadjuvant chemoimmunotherapy is becoming an increasingly important part of the management of lung cancer to facilitate surgical resection. This study aimed to summarize the treatment-related adverse events (TRAEs) and wound complications of neoadjuvant chemoimmunotherapy in non-small cell lung cancer (NSCLC). Eligible studies of neoadjuvant chemoimmunotherapy for NSCLC were identified from PubMed, Embase and Web of Science. The endpoints mainly included TRAEs and wound complications. Stata18 software was used for statistical analysis with p < 0.05 considered statistically significant. Twenty studies including a total of 1072 patients were eligible for this study. Among the patients who received neoadjuvant chemoimmunotherapy, the pooled prevalence of any grade TRAEs was 77% (95% confidence interval [CI] [0.64-0.86]), grade 1-2 TRAEs was 77% (95% CI [0.58-0.89]) and grade ≥3 TRAEs was 26% (95% CI [0.16-0.38]). Surgery-related complications rate was 22% (95% CI [0.14-0.33]). Among the wound complications, the pooled rate of air leakage was 10% (95% CI [0.04-0.23]), pulmonary/wound infection was 8% (95% CI [0.05-0.13]), bronchopleural fistula was 8% (95% CI [0.02-0.27]), bronchopulmonary haemorrhage was 3% (95% CI [0.01-0.05]), pneumonia was 5% (95% CI [0.02-0.10]), pulmonary embolism was 1% (95% CI [0.01-0.03]), pleural effusion was 7% (95% CI [0.03-0.14]) and chylothorax was 4% (95% CI [0.02-0.09]). Overall, neoadjuvant chemoimmunotherapy in NSCLC results a high incidence of grade 1-2 TRAEs but a low risk of increasing the incidence of ≥3 grade TRAEs and wound complications. These results need to be confirmed by more large-scale prospective randomized controlled trials and studies.

Occurrence and risk assessment of azole fungicides during the urban water cycle: A year-long study along the Yangtze River, China.

Azole fungicides (AFs) play an important role in the prevention and treatment of fungal diseases in agricultural crops. However, limited studies are addressing the fate and ecological risk of AFs in the urban water cycle at a large watershed scale. To address this gap, we investigated the spatiotemporal distribution and ecological risk of twenty AFs in the lower reaches of the Yangtze River across four seasons. Carbendazim (CBA), tebuconazole (TBA), tricyclazole (TCA), and propiconazole (PPA) were found to be the dominant compounds. Their highest concentrations were measured in January (188.3 ng/L), and November (2197.1 ng/L), July (162.0 ng/L), and November (1801.9 ng/L), respectively. The comparison between wastewater treatment plants (WWTPs) effluents and surface water suggested that industrial WWTPs are major sources of AFs in the Yangtze River. In particular, TBA and PPA were found to be the most recalcitrant AFs in industrial WWTPs, while difenoconazole (DFA) was found to be the most potent pollutant in municipal WWTPs, with an average removal rate of less than 60%. The average risk quotient (RQ) for the entire AFs was 6.45 in the fall, which was higher than in January (0.98), April (0.61), and July (0.40). This indicates that AFs in surface water posed higher environmental risks during the dry season. Additionally, the exposure risk of AFs via drinking water for sensitive populations deserves more attention. This study provides benchmark data on the occurrence of AFs in the lower reaches of the Yangtze River, and offers suggestions for better reduction of AFs.

Microsphere probe: combining microsphere-assisted microscopy with AFM.

In recent years, microsphere-assisted microscopy (MAM) and atomic force microscope (AFM) have been rapidly developed to meet the measurement needs of microstructures. However, the positioning of microspheres, the inability of AFM to touch the underlying sample through the transparent insulating layer, and the challenge of AFM fast positioning limit their use in practical measurements. In this paper, we propose a method that combines MAM with AFM by adhering the microsphere to the cantilever. This method allows MAM and AFM to work in parallel, and their imaging positions can correspond with each other. We use this method to measure memory devices, and the results show that MAM and AFM yield complementary advantages. This approach provides a new tool for analyzing complex structures in devices and has potential for wide application.

Palladium-Catalyzed Multicomponent Cascade Reaction of 3-Hydroxypropionitrile: Synthesis of Substituted Dihydrochalcones.

Direct access to substituted dihydrochalcones from the easily available starting materials 3-hydroxypropionitrile derivatives and arylboronic acids is described. The procedure involves a multicomponent aryl addition/hydroxyl elimination/reduction Heck approach in the presence of a Pd catalyst with excellent functional group tolerance and a wide range of substrates. In addition, mixed 1,3-diarylation of 3-hydroxypropanenitrile using two arylboronic acids with different electronic properties was also achieved.

Inter-basin water diversion homogenizes microbial communities mainly through stochastic assembly processes.

Inter-basin water transfer is an effective manner to achieve the optimal allocation of water resources, while accompanied by some ecological effects. The responses of microorganisms to water diversion and the ecological processes in regulating the community assembly are still unclear. Taking the eastern route of South-to-North Water Diversion Project as the study area, we investigated the microbial community patterns and the underlying assemblage processes in habitats with different hydrological connectivity, including isolated lakes, connected lakes and man-made canal. The results showed that microbial communities in the canal had higher diversity, lower dissimilarity, weaker compositional variation, and stronger co-occurrence patterns compared with that in the connected and isolated lakes. These findings suggested that the increase of connectivity among natural aquatic habitats due to water diversion can homogenize microbial communities and reduce microbial heterogeneity. The neutral and null models demonstrated the importance of stochastic processes in shaping microbial community assembly. Dispersal limitation and variable selection were the predominant mechanisms structuring microbial communities in the isolated lakes. Due to the homogenized environmental condition and the enhanced hydrologic connectivity in the canal and the connected lakes, microbial communities had higher dispersal capability and ecological drift occurred more frequently in these lotic habitats. The variations in microbial community structure were mainly driven by biotic ecological succession than abiotic factors, with positive and negative cohesion explained 63% and 25% of variability, respectively. Six taxa were considered as the potential introduced microorganisms, which may favor the nutrient biogeochemical cycling and the organic matter degradation, but may also bring ecological risks. Overall, this study provides a deeper understanding of the ecological consequences of inter-basin water diversion, and helps the regulation and management of these projects.

Role of Hemodialysis in Acute Severe Alcohol Intoxication: A Meta-Analysis.

BACKGROUND: Hemodialysis therapy has been used in the treatment of acute alcohol intoxication for many years, especially acute severe alcohol intoxication. OBJECTIVES: This study aimed to evaluate whether the combination of conventional treatment and naloxone with hemodialysis has advantages over conventional treatment and naloxone alone in patients with acute severe alcohol intoxication. METHODS: After searching 12 databases and 2 clinical trial centers. According to the established inclusion and exclusion criteria, the qualified literatures were screened. The outcome indicators were length of hospital stay, coma time, time of symptom disappearance, the overall complication rate, the incidence of pancreatitis, the incidence of aspiration pneumonia, the incidence of hepatic and renal dysfunction. Analysis was performed using Revman 5.3. RESULTS: This meta-analysis included 13 studies, including 932 subjects. In the treatment of acute severe alcohol intoxication, the use of hemodialysis on the basis of conventional treatment and naloxone could reduce the length of hospital stay (WMD = -15.16, 95% CI: -17.45 to -12.86, p < 0.001) in hours and (WMD = -4.89, 95% CI: -5.53 to -4.25, p < 0.001) in days; coma time (WMD = -5.43, 95% CI: -6.43 to -4.43, p < 0.001); time of symptom disappearance (WMD = -3.92, 95% CI: -5.37 to -2.47, p < 0.001); the overall complication rate (RR = 0.39, 95% CI: 0.28-0.55, p < 0.001); the incidence of pancreatitis (RR = 0.14, 95% CI: 0.05-0.43, p = 0.0006); the incidence of aspiration pneumonia (RR = 0.15, 95% CI: 0.04-0.66, p = 0.01), and the incidence of hepatic and renal dysfunction (RR = 0.21, 95% CI: 0.06-0.72, p = 0.01). CONCLUSIONS: It can be concluded that compared with the use of conventional treatment and naloxone alone, the use of hemodialysis on the basis of conventional treatment and naloxone for acute severe alcohol intoxication can reduce the length of hospital stay, coma time, time of symptom disappearance, and the incidence of some complications rate. Large scale, multicenter, and well-designed RCTs are needed in the future to prove our conclusions.

Room-temperature polariton lasing in GaN microrods with large Rabi splitting.

Room-temperature polariton lasing is achieved in GaN microrods grown by metal-organic vapor phase epitaxy. We demonstrate a large Rabi splitting (Ω = 2g0) up to 162 meV, exceeding the results from both the state-of-the-art nitride-based planar microcavities and previously reported GaN microrods. An ultra-low threshold of 1.8 kW/cm2 is observed by power-dependent photoluminescence spectra, with the linewidth down to 1.31 meV and the blue shift up to 17.8 meV. This large Rabi splitting distinguishes our coherent light emission from a conventional photon lasing, which strongly supports the preparation of coherent light sources in integrated optical circuits and the study of exciting phenomena in macroscopic quantum states.

Analytical models of electron leakage currents in gallium nitride-based laser diodes and light-emitting diodes.

The electrical-to-optical power conversion efficiencies of the light-emitting devices based on gallium nitride (GaN) are seriously limited by electron leakage currents due to the relatively low mobility and activation ratio of holes. However, there have been few theoretical models on the behavior of the leakage current with an increasing total current. We develop an Ohmic-law-like method to describe the transport behaviors of the systems with electron and hole currents simultaneously. Based on reasonable assumptions, the ratio of the leakage current to the total current is related to the differential resistances of the devices. Through the method, we develop analytical models of the leakage currents in GaN-based laser diodes (LDs) and light-emitting diodes (LEDs). The ratios of the leakage currents with total currents in LDs and LEDs are shown to increase, which explains the sublinear behaviors of the luminescence-current (LI) curves of the devices. The theory agrees well with the numerical simulation and experimental results in larger current ranges in comparison to the traditional ABC model. The above analytical model can be used to fast evaluate the leakage currents in GaN-based LDs and LEDs.