Valley depolarization in monolayer WSe2

We have systematically examined the circular polarization of monolayer WSe2 at different temperature, excitation energy and exciton density. The valley depolarization in WSe2 is experimentally confirmed to be governed by the intervalley electron-hole exchange interaction. More importantly, a non-monotonic dependence of valley circular polarization on the excitation power density has been observed, providing the experimental evidence for the non-monotonic dependence of exciton intervalley scattering rate on the excited exciton density. The physical origination of our experimental observations has been proposed, which is in analogy to the D'yakonov-Perel' mechanism that is operative in conventional GaAs quantum well systems. Our experimental results are fundamentally important for well understanding the valley psudospin relaxation in atomically thin transition metal dichalcogenides

Strong enhancement of photoresponsivity with shrinking the electrodes spacing in few layer GaSe photodetectors

A critical challenge for the integration of the optoelectronics is that photodetectors have relatively poor sensitivities at the nanometer scale. It is generally believed that a large electrodes spacing in photodetectors is required to absorb sufficient light to maintain high photoresponsivity and reduce the dark current. However, this will limit the optoelectronic integration density. Through spatially resolved photocurrent investigation, we find that the photocurrent in metal-semiconductor-metal (MSM) photodetectors based on layered GaSe is mainly generated from the photoexcited carriers close to the metal-GaSe interface and the photocurrent active region is always close to the Schottky barrier with higher electrical potential. The photoresponsivity monotonically increases with shrinking the spacing distance before the direct tunneling happen, which was significantly enhanced up to 5,000 AW-1 for the bottom contacted device at bias voltage 8 V and wavelength of 410 nm. It is more than 1,700-fold improvement over the previously reported results. Besides the systematically experimental investigation of the dependence of the photoresponsivity on the spacing distance for both the bottom and top contacted MSM photodetectors, a theoretical model has also been developed to well explain the photoresponsivity for these two types of device configurations. Our findings realize shrinking the spacing distance and improving the performance of 2D semiconductor based MSM photodetectors simultaneously, which could pave the way for future high density integration of 2D semiconductor optoelectronics with high performances.Comment: 25 pages, 4 figure

Effectiveness of adjuvant traditional Chinese medicine on macrovascular invasion in patients with hepatocellular carcinoma: a real-world propensity score-matched study

The study aimed to investigate the potential of traditional Chinese medicine (TCM) in reducing the risk of macrovascular invasion (MVI) in Chinese patients with hepatocellular carcinoma (HCC). This retrospective analysis involved 2,267 HCC patients treated at our hospital. Propensity score (PS) matching was used to compare TCM users (n = 485) with non-users (n = 485) in terms of age, Barcelona Clinic Liver Cancer (BCLC) staging, type of treatment, and AFP. The impact of TCM on the hazard ratio (HR) of MVI was evaluated using a Cox multivariate regression model. The efficacy of TCM therapy on MVI was further examined using the log-rank test. The analysis revealed that TCM medication was a significant protective factor for MVI in HCC patients, as evidenced by the Cox analysis (adjusted HR = 0.496, 95% CI: 0.387–0.635, p < 0.001). After PS matching, the Kaplan-Meier curve demonstrated a lower occurrence rate of MVI in TCM users compared to non-users. The study findings suggest that TCM treatment has the potential to decrease the incidence of MVI in HCC patients, irrespective of etiology, BCLC staging, liver function, or treatment type. Notably, as the use of TCM increased, the percentage of MVI in patients showed a gradual decrease, indicating the potential of TCM therapy as a successful strategy for preventing MVI

Architecture, Voltage, and Components for a Turboelectric Distributed Propulsion Electric Grid (AVC-TeDP)

The purpose of this effort was to advance the selection, characterization, and modeling of a propulsion electric grid for a Turboelectric Distributed Propulsion (TeDP) system for transport aircraft. The TeDP aircraft would constitute a miniature electric grid with 50 MW or more of total power, two or more generators, redundant transmission lines, and multiple electric motors driving propulsion fans. The study proposed power system architectures, investigated electromechanical and solid state circuit breakers, estimated the impact of the system voltage on system mass, and recommended DC bus voltage range. The study assumed an all cryogenic power system. Detailed assumptions within the study include hybrid circuit breakers, a two cryogen system, and supercritical cyrogens. A dynamic model was developed to investigate control and parameter selection

Effective microorganisms input efficiently improves the vegetation and microbial community of degraded alpine grassland

Soil beneficial microorganism deficiency in the degraded grasslands have emerged as the major factors negatively impacting soil quality and vegetation productivity. EM (effective microorganisms) has been regarded as a good ameliorant in improving microbial communities and restoring degraded soil of agricultural systems. However, knowledge was inadequate regarding the effects of adding EM on the degraded alpine grassland. Four levels of EM addition (0, 150, 200, 250 mL m–2) were conducted to investigate the effects of EM addition on soil properties and microorganisms of degraded alpine grassland. The addition of EM increased aboveground biomass, soil organic carbon, total nitrogen, available phosphorus, and microbial biomass, but decreased soil electric conductivity. Meanwhile, the relative biomasses of gram-negative bacteria decreased, while the ectomycorrhizal fungi and arbuscular mycorrhizal fungi increased after EM addition. The relationship between microbial communities and environmental factors has been changed. The restore effect of EM increased with the increase of addition time. These results indicated that EM addition could be a good practice to restore the health of the degraded alpine grassland ecosystem

Effects of different soil water holding capacities on vegetable residue return and its microbiological mechanism

With the gradual expansion of the protected vegetable planting area, dense planting stubbles and increasing labor cost, the treatment of vegetable residues has become an urgent problem to be solved. Soil bacterial community structure plays an important role in vegetable residue return and is susceptible to environmental changes. Therefore, understanding the influences of different soil water holding capacities on plant residue decomposition and soil bacterial communities is important for biodegradation. During the whole incubation period, the weight loss ratio of plant residue with 100% water holding capacity was 69.60 to 75.27%, which was significantly higher than that with 60% water holding capacity in clay and sandy soil, indicating that high water holding capacity promoted the decomposition of plant residue. The degradation of lignin and cellulose was also promoted within 14 days. Furthermore, with the increase in soil water holding capacity, the contents of NH4+ increased to 5.36 and 4.54 times the initial value in the clay and sandy soil, respectively. The increase in napA and nrfA resulted in the conversion of NO3– into NH4+. The increase in water holding capacity made the bacterial network structure more compact and changed the keystone bacteria. The increase in water holding capacity also increased the relative abundance of Firmicutes at the phylum level and Symbiobacterium, Clostridium at the genus level, which are all involved in lignin and cellulose degradation and might promote their degradation. Overall, these findings provide new insight into the effects of different soil water holding capacities on the degradation of plant residues in situ and the corresponding bacterial mechanisms

Shenxian-Shengmai Oral Liquid Reduces Myocardial Oxidative Stress and Protects Myocardium from Ischemia-Reperfusion Injury

Background/Aims: Shenxian-shengmai (SXSM) oral liquid, a Chinese patent compound medicine, has been used to treat sinus bradyarrhythmias induced by mild sick sinus syndrome in clinical practice. Myocardial ischemia, in particular in serious or right coronary-related heart diseases, can cause bradyarrhythmias and cardiac dysfunction. Moreover, reperfusion of ischemic myocardium is associated with additional myocardial damage known as myocardial ischemia-reperfusion (I/R) injury. This study was designed to evaluate the effects of SXSM on bradyarrhythmias and cardiac dysfunction induced by myocardial I/R injury, and to explore the underlying mechanisms. Methods: Administration of SXSM to adult male Sprague Dawley (SD) rats was achieved orally by gavage and control rats were given equivalent deionized water every day for 14 days. After the last administration, the heart was connected with the Langendorff perfusion apparatus and both groups were subjected to ischemia for 20 min followed by reperfusion for 40 min to induce myocardial I/R injury. Heart rate (HR), left ventricular developed pressure (LVDP), the maximal increase rate of left ventricular pressure (+dp/dtmax) and the maximal decrease rate of left ventricular pressure (-dp/dtmax) were recorded by a physiological signal acquisition system. The heart treated with ischemic preconditioning (IPC) for 3 times at a range of 5 min/time before ischemia served as a positive control group. The hearts without I/R injury served as control group. After reperfusion, superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GSH-Px) activities in the myocardium were determined by appropriate assay kits. Myocardial SOD1 and glutamate cysteine ligase catalytic subunit (GCLC) expression were assessed by western blot analysis. For the in vitro study, SXSM serum was prepared according to the serum pharmacological method and neonatal rat cardiomyocytes were isolated from the heart of new born SD rats. Neonatal rat cardiomyocytes were pretreated with SXSM serum and subjected to H2O2 or anoxia/ reoxygenation (A/R) treatment to induce oxidative damage. Cell viability was evaluated using a Cell Counting Kit-8 (CCK8) assay. Levels of reactive oxygen species (ROS), SOD, GSH and GSH-Px in cardiomyocytes were determined by appropriate assay kits. SOD1 and GCLC expression were assessed by western blot analysis. Buthionine-[S, R]-sulfoximine (BSO), a GCLC inhibitor, and SOD1 siRNA were also used for identifying the cardiac protective targets of SXSM. Results: SXSM and ischemic preconditioning (IPC) significantly increased heart rate during myocardial reperfusion and protected cardiac function against myocardial I/R injury, including an increase in left ventricular diastolic pressure (LVDP), the maximal increase rate of left ventricular pressure (+dp/dtmax) and the maximal decrease rate of left ventricular pressure (-dp/dtmax). We also found that SXSM and IPC improved the expansion of myocardial interstitium, the structural abnormality and morphological changes of cardiomyocytes induced by I/R injury. Meanwhile, SXSM protected cardiomyocytes against the oxidative damage induced by H2O2 and A/R injury through reducing intracellular ROS levels. Moreover, SXSM increased SOD activity through enhancing SOD1 expression and increased GSH content through promoting GCLC expression as well as GSH-Px activity. BSO and SOD1 siRNA counteracted anti-arrhythmic and cardiac protective effect of SXSM, suggesting that the therapeutic targets of SXSM might be SOD1 and GCLC. Conclusion: SXSM is effective in protecting the myocardium from I/R injury, with myocardial SOD1 and GCLC being the potential therapeutic targets