Stable reference gene selection for quantitative real-time PCR normalization in passion fruit (Passiflora edulis Sims.).

BACKGROUND: Passiflora edulis is a tropical fruit with high nutrient and medicinal values that is widely planted in southern China. However, the molecular biology of P. edulis has not been well studied. There are few reports regarding the choice of reference genes for gene expression studies of passion fruit. METHODS AND RESULTS: By using three algorithms, implemented in geNorm, NormFinder and BestKeeper, we have selected ten candidate reference genes to explore their transcriptional expression stability in various tissues and under cold stress conditions. EF1 and HIS were stably expressed in five tissues. Ts and OTU were stably in vegetative organs. 50 S and Liom were stably in reproductive organs. The transcriptional abundance of EF1 and UBQ was stable in cold-treated and recovery treated leaf samples of P. edulis. In all samples, EF1 and Ts exhibited the highest expression stability. Evaluation of selected genes using simple statistical methods (ANOVA and post hoc analysis). Overall, EF1 emerged as the optimum reference gene for qRT-PCR normalize in P. edulis. In addition, the qRT-PCR analysis revealed that expression of ICE1 increases with the duration of cold treatment. CONCLUSIONS: In this study, we successfully screened stable reference genes from 10 candidates in P. edulis and verified the results by analyzing the expression level of ICE1. The results provide reliable and effective reference genes for future research on gene expression analysis in P. edulis, and lay a foundation for follow-up research on functional genes in P. edulis.

Effect of Particle Size and Constraint Conditions on Single Particle Strength of Carbonate Sand.

Carbonate sand is often encountered and utilized as construction material in offshore engineering projects. Carbonate sand particles, which are porous and angular, are found to be highly crushable under high stress conditions, whereas the mechanisms and controlling factors for the crushing of carbonate sand particles are not well developed. The crushability and particle strength of around 400 particles from three fractions (5-10 mm, 2-5 mm, and 1-2 mm) of carbonate sand from the South China Sea were investigated via grain-scale single particle crushing tests. Special emphasis was placed on the effect of external constraint conditions (i.e., coordination number) and intrinsic particle morphology characteristics on the particle strength of carbonate soil. The particle strength of carbonate sand was found to be around half of quartz sand in terms of characteristic stress. Negative correlations, which could be depicted by an exponential equation, were found between the particle size and particle strength. Due to elongated particle shape and tensile stress concentration, a higher coordination number may lower the particle strength, which contradicts what was reported for quartz sands. A series of seven fundamental particle dimensions and five particle shape descriptors was characterized, and the aspect ratio was found to be one of the more influential shape descriptors for particle strength. The results enriched the database for the analysis of highly irregular geomaterial and provided insights into controlling factors of particle strength and crushing mechanisms of the carbonate sand.

Experimental Study on the Mechanical Properties and Microstructure of Metakaolin-Based Geopolymer Modified Clay.

Clay is found in some countries all over the world. It usually has low compressive strength and cannot be used as a bearing material for subgrade soil. In this paper, the influence of basicity on a metakaolin-based polymer binder to improve clay was studied. The effects of the molar concentration of the alkali activator, different concentration of the metakaolin-based geopolymer and curing time on unconfined compressive strength were studied. The alkali activator-to-ash ratio was maintained at 0.7. The percentage of metakaolin added to the soil relative to metakaolin and soil mixture was 6%, 8%, 10% and 12%. The sodium hydroxide concentrations are 2M, 4M, 6M and 8M. Unconfined compressive strength (UCS) was tested on days 3, 7, 14 and 28, respectively. Compared with original clay, the results show that the unconfined compressive strength increases with the increase in metakaolin content and molar concentration of NaOH. The maximum compressive strength of the sample with NaOH concentration of 8M and percentage of 12% was 4109 kN on the 28th day, which is about 112% higher than that of the original clay. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that the cementing compound covered the clay particles due to the reaction of the geopolymer with the clay, resulting in the formation of adhesive particles. The main purpose of this study is to verify the effectiveness and stability of metakaolin-based geopolymer binder polymerization under normal temperature and a strong alkali environment. The results can provide parameters for the application and promotion of metakaolin-based geopolymers in soil improvement engineering.

Antinociceptive activity of astragaloside IV in the animal model of chronic constriction injury.

To investigate the applicability of astragaloside IV (AG) for the treatment of refractory neuropathic pain, we systemically evaluated the antinociceptive activity of AG in the animal model of chronic constriction injury. We studied behaviors, electrophysiology, and biochemistry from day 2 to day 23 after the surgery. We found that when administered intraperitoneally at the dose of 60 mg/kg, AG caused significant inhibition of allodynia and hyperalgesia induced by mechanic and thermal stimuli as well as downregulation of the expressions of a series of proteins involved in mediating neuropathic pain in the dorsal root ganglia, such as P2X purinoceptor 3, glial cell-derived neurotrophic factor, glial cell-derived neurotrophic factor family receptor α1, and transient receptor potential cation channel subtypes A1 and V1. Further investigation showed that AG restored the nerve conduction velocity and the histological structure of the damaged sciatic nerve on day 23 after the surgery. Moreover, results from immunoelectron microscope showed that glial cell-derived neurotrophic factor family receptor α1 induced by AG could form a circular band in the myelin debris between the injured axons and Schwann cells, contributing toward restoration of the damaged nerve. In conclusion, in our animal model, AG effectively inhibited the neuropathic pain induced by chronic constriction injury.

Pharmacokinetics and bioavailability study of polydatin in rat plasma by using a LC-MS/MS method.

To investigate the pharmacokinetic and bioavailability of polydatin (PD) in rats after oral and intravenous administration, a simple, rapid and sensitive liquid chromatography-tandem mass spectroscopy (LC-MS/MS) method was developed and validated for the determination of polydation. After precipitating the plasma proteins with methanol, the analytes were separated on a C18 column (3.5µm, 2.1×100 mm) with an isocratic mobile phase consisting of methanol-acetonitrile-0.1% formic acid (18: 15: 67, v/v/v) at a flow rate of 0.3mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple reaction monitoring (MRM) mode and the electrospray ionization technique was in negative mode. Linear responses were obtained for PD ranging from 1.0-5000.0 ng/mL (r= 0.9984) and the LLOQ was 1.0ng/ml and was sufficient for the pharmacokinetic studies. The intra-day and inter-day accuracy and precision of the assay were less than 8.0%. The method is capable of quantifying PD. The pharmacokinetic parameters of polydatin after intragastric administration of PD with different doses (50, 100 and 300 mg/kg) and intravenous administration at the dose of 20 mg/kg, were obtained, with t1/2 of 200.30 min, 210.30 min, 272.26 min, and 112.5 min, and AUC0-∞ of 125626.41 µg/L· min, 250433.47 µg/L·min, 693722.60 µg/L· min and 1723509.57µg/L· min, respectively. The absolute bioavailability of PD was somewhat low to 2.9%. The results were firsly reported, as far as we know, about bioavailability of PD and seem important for linking PD and other phenolic glycosides-related drugs administration to their medicinal effects.

Sodium hydroxide/magnesium chloride multistage activated sludge biochar: interfacial chemical behavior and Cd(II) adsorption performance.

To enhance the adsorption performance of municipal sludge biochar on Cd(II), modified sludge biochar was prepared by sodium hydroxide/magnesium chloride (NaOH/MgCl2) graded activation, and the Cd(II) adsorption performance on sludge biochar (BC), NaOH-activated sludge biochar (NBC) and NaOH/MgCl2 activated sludge biochar (NBC-Mg) was investigated. The results showed that NaOH/MgCl2 graded activation upgraded the surface structure and enhanced the graphitization of sludge biochar. The adsorption experiments indicated that the adsorption kinetic and adsorption isotherm for Cd(II) were in accordance with the pseudo second-order kinetic and Langmuir model. The adsorption capacity of NBC-Mg (143.49 mg/g) for Cd(II) was higher than that of BC (50.40 mg/g) and NBC (85.20 mg/g). The mechanism of Cd(II) adsorption included ion exchange, complexation, cation-π interaction, and mineral precipitation. After five regeneration, the removal efficiency of Cd(II) by NBC-Mg remained above 90%. This work indicated that sludge biochar prepared by multistage activation could be an effective material for Cd-containing wastewater treatment.

Fine Structure Characterization of Representative Coal-Bearing Rocks of the Late Carboniferous Taiyuan Formation in Huainan Coalfield: Combined SEM, FESEM, and µCT Techniques.

Pores and fractures are important channels for coalbed methane (CBM) storage, seepage, and production, and accurate characterization of the microstructure of coal-bearing rock strata is of great significance for CBM exploration and development. Taking the coal-bearing rocks of the Late Carboniferous Taiyuan Formation in the Huainan coalfield as the research object, accurate characterization of the organic macerals, microstructure, and mineral distribution of sandstone, coal, and sandy mudstone was achieved using a multiscale combination of polarization microscopy (POM), X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and X-ray computed tomography (µCT). The thin section identification results indicated that the organic matter in the coal measures rocks of the Taiyuan Formation was well developed and mainly composed of vitrinite, followed by fusinite and exinite, and in addition, there was a distribution of bituminite and sapropelite. The mineral composition of the rocks was dominated by quartz, calcite, siderite, and clay minerals, in addition to plagioclase and ankerite in the fine sandstone. In terms of pore and fracture development, all types of rocks were highly developed with nanoscale and micrometer-scale pores and of mostly irregular shapes, and all types of rocks had fracture development except for medium sandstone. The above-mentioned results show that the Late Carboniferous Taiyuan Formation in the Huainan coalfield has good space for CBM storage and transportation and has certain potential for CBM development. This study provides theoretical guidance for unconventional oil and gas exploration and development in the Huainan coalfield.

Theoretical assessment of influential factors and application in chlorinated hydrocarbon detection with membrane interface probe.

The membrane interface probe (MIP) is an efficient and economical in-situ tool for chlorinated hydrocarbon (CH) contaminated site investigation. Given that the interpretation of MIP test is currently limited to a qualitative level, a theoretical model considering multiphase flow and multifield coupling is firstly proposed to simulate MIP test process. This model can consider phase change, membrane effect, adsorption and dissolution of the CH liquid, gas diffusion, and evaporation. Then, the model is used to study the changes in soil temperature and soil CH concentration during MIP test, as well as the influences of soil CH concentration and soil properties (initial water saturation, soil intrinsic permeability, and thermal properties) on MIP response. Finally, a simplified MIP interpretation model is developed based on parametric analysis results and verified against field and laboratory test data. It is found that the soil CH concentration, rather than soil properties, dominates the MIP response. The simplified interpretation model can deliver practical prediction of the CH concentration through the detected results by MIP, which may improve the applicability of MIP.

Re-oligotrophication and warming stabilize phytoplankton networks.

Phytoplankton taxa are strongly interconnected as a network, which could show temporal dynamics and non-linear responses to changes in drivers at both seasonal and long-term scale. Using a high quality dataset of 20 Danish lakes (1989-2008), we applied extended Local Similarity Analysis to construct temporal network of phytoplankton communities for each lake, obtained sub-network for each sampling month, and then measured indices of network complexity and stability for each sub-network. We assessed how lake re-oligotrophication, climate warming and grazers influenced the temporal dynamics on network complexity and stability of phytoplankton community covering three aspects: seasonal trends, long-term trends and detrended variability. We found strong seasonality for the complexity and stability of phytoplankton network, an increasing trend for the average degree, modularity, nestedness, persistence and robustness, and a decreasing trend for connectance, negative:positive interactions and vulnerability. Our study revealed a cascading effect of lake re-oligotrophication, climate warming and zooplankton grazers on phytoplankton network stability through changes in network complexity characterizing diversity, interactions and topography. Network stability of phytoplankton increased with average degree, modularity, nestedness and decreased with connectance and negative:positive interactions. Oligotrophication and warming stabilized the phytoplankton network (enhanced robustness, persistence and decreased vulnerability) by enhancing its average degree, modularity, nestedness and by reducing its connectance, while zooplankton richness promoted stability of phytoplankton network through increases in average degree and decreases in negative interactions. Our results further indicate that the stabilization effects might lead to more closed, compartmentalized and nested interconnections especially in the deeper lakes, in the warmer seasons and during bloom periods. From a temporal dynamic network view, our findings highlight stabilization of the phytoplankton community as an adaptive response to lake re-oligotrophication, climate warming and grazers.

Weakened casual feedback loops following intensive restoration efforts and climate changes in a large shallow freshwater lake.

Understanding how phytoplankton interacts with local and regional drivers as well as their feedbacks is a great challenge, and quantitative analyses of the regulating role of human activities and climate changes on these feedback loops are also limited. By using monthly monitoring dataset (2000-2017) from Lake Taihu and empirical dynamic modelling to construct causal networks, we quantified the strengths of causal feedbacks among phytoplankton, local environments, zooplankton, meteorology as well as global climate oscillation. Prevalent bidirectional causal linkages between phytoplankton biomass (chlorophyll a) and the tested drivers were found, providing holistic and quantitative evidence of the ubiquitous feedback loops. Phytoplankton biomass exhibited the highest feedbacks with total inorganic nitrogen and ammonia and the lowest with nitrate. The feedbacks between phytoplankton biomass and environmental factors from 2000 to 2017 could be classified into two groups: the local environments (e.g., nutrients, pH, transparency, zooplankton biomass)-driven enhancement loops promoting the response of the phytoplankton biomass, and the climate (e.g., wind speed)-driven regulatory loops suppressing it. The two counterbalanced groups modified the emergent macroecological patterns. Our findings revealed that the causal feedback networks loosened significantly after 2007 following nutrient loading reduction and unsuccessful biomanipulation restoration attempts by stocking carp. The strength of enhancement loops underwent marked decreases leading to reduced phytoplankton responses to the tested drivers, while the climate (decreasing wind speed, warming winter)-driven regulatory loops increased- like a tug-of-war. To counteract the self-amplifying feedback loops, the present eutrophication mitigation efforts, especially nutrient reduction, should be continued, and introduction of alternative measures to indirectly regulate the critical components (e.g., pH, Secchi depth, zooplankton biomass) of the loops would be beneficial.

Ketanserin improves cardiac performance after myocardial infarction in spontaneously hypertensive rats partially through restoration of baroreflex function.

AIM: Baroreflex dysfunction is associated with a higher rate of sudden death after myocardial infarction (MI). Ketanserin enhances baroreflex function in rats. The present work was designed to examine whether ketanserin improves the post-MI cardiac function and to explore the possible mechanism involved. METHODS: Spontaneously hypertensive rats (SHR) were treated with ketanserin (0.3 mg·kg(-1)·d(-1)). Two weeks later, blood pressure and baroreflex function were measured, followed by a ligation of the left coronary artery. The expressions of vesicular acetylcholine transporter (VAChT) and α7 nicotinic acetylcholine receptor (α7-nAChR) in ischemic myocardium, angiogenesis, cardiac function, and left ventricular (LV) remodeling were evaluated subsequently. RESULTS: Ketanserin significantly improved baroreflex sensitivity (0.62±0.21 vs 0.34±0.12 ms/mmHg, P<0.01) and vagal tonic activity (heart rate changes in response to atropine, 54.8±16.2 vs 37.6±13.4 bpm, P<0.01) without affecting the blood pressure or basic heart rate in SHR. Treatment of SHR with ketanserin prominently improved cardiac function and alleviated LV remodeling, as reflected by increases in the ejection fraction, fractional shortening, and LV systolic pressure as well as decreases in LV internal diameter and LV relative weight. The capillary density, vascular endothelial growth factor expression, and blood flow in the ischemic myocardium were significantly higher in the ketanserin-treated group. In addition, ketanserin markedly increased the expression of VAChT and α7-nAChR in ischemic myocardium. CONCLUSION: Ketanserin improved post-MI cardiac function and angiogenesis in ischemic myocardium. The findings provide a mechanistic basis for restoring baroreflex function using ketanserin in the treatment of MI.

Towards sustainable integrated watershed ecosystem management: a case study in Dingxi on the loess plateau, China.

The Chinese government initiated a massive conservation program called "Grain-for-Green" in 1999 to reduce soil erosion and improve ecosystem function. Implementing practical sustainable development in the loess plateau still remains problematic, particularly in its eco-fragile areas. Here we discussed an approach for sustainable development at the watershed scale by integrating land use suitability, ecosystem services and public participation in the loess hilly area. We linked land use scenario analysis and economic modeling to compare the outcomes of three scenarios, CLU (Current Land Use), GOLU (Grain-production Oriented Land Use) and PSLU (Potential Sustainable Land Use). The results indicated that compared to PSLU, GOLU may provide a higher economic productivity in the short-term, but not in the long-term. CLU ranked lowest in terms of economic benefits and did not meet the daily needs of the local farmers. To reconcile the land use adjustments with farmers' basic needs, a labor-saving land use strategy is necessary. Since the PSLU scenario assumes that slope cropland should be converted to pastures or orchards, more time may be available for off-farm work and for more public participation in integrated ecosystem management. Financial support to the local farmers for environmental conservation should be modulated in function of their positive contribution to ecosystem management.

Interplay between obesity and aging on myocardial geometry and function: Role of leptin-STAT3-stress signaling.

BACKGROUND: Uncorrected obesity facilitates premature aging and cardiovascular anomalies. This study examined the interaction between obesity and aging on cardiac remodeling and contractile function. METHODS: Cardiac echocardiographic geometry, function, morphology, intracellular Ca2+ handling, oxidative stress (DHE fluorescence), STAT3 and stress signaling were evaluated in young (3-mo) and old (12- and 18-mo) lean and leptin deficient ob/ob obese mice. Cardiomyocytes from young and old lean and ob/ob mice were treated with leptin (1 nM) for 4 h in vitro prior to assessment of mechanical and biochemical properties. High fat diet (45% calorie from fat) and the leptin receptor mutant db/db obese mice at young and old age were evaluated for comparison. RESULTS: Our results displayed reduced survival in ob/ob mice. Obesity but less likely older age dampened echocardiographic, geometric, cardiomyocyte function and intracellular Ca2+ properties, elevated O2- and p47phox NADPH oxidase levels with a more pronounced geometric change at older age. Immunoblot analysis revealed elevated p47phox NADPH oxidase and dampened phosphorylation of STAT3, with a more pronounced response in old ob/ob mice, the effects were restored by leptin. Obesity and aging inhibited phosphorylation of Akt, eNOS, AMPK, and p38 while promoting phosphorylation of JNK and IκB. Leptin reconciled cardiomyocyte dysfunction, O2- yield, p47phox upregulation, STAT3 dephosphorylation and stress signaling in ob/ob mice although its action on stress signaling cascades were lost at old age. High fat diet-induced and db/db obesity displayed aging-associated cardiomyocyte anomalies reminiscent of ob/ob model albeit lost leptin response. CONCLUSIONS: Our data suggest disparate age-associated obesity response in cardiac remodeling and contractile dysfunction due to phosphorylation of Akt, eNOS and stress signaling-related oxidative stress.

Design and Implementation of a Chain-Type Direct Push Drilling Rig for Contaminated Sites.

For sites where volatile organic compounds are present, the direct push method, in combination with other sensors for investigation, is a powerful method. The investigation process is an integrated drilling and sensing process, but the trajectory of the probe carrying the sensor is ambiguous. This paper explores and introduces the application of a chain-type direct push drilling rig by designing and building a chain-type direct push miniature drilling rig. This rig allows for indoor experimental studies of direct push trajectories. The chain-type direct push drilling model is proposed based on the mechanism of chain transmission. The drilling rig provides a steady direct thrust through the chain, which is driven by a hydraulic motor. In addition, the drilling tests and results described prove that the chain could be applied to direct push drilling. The chain-type direct push drilling rig can drill to a depth of 1940 mm in single-pass and up to 20,000 mm in multiple passes. The test results also indicate that it drills a total length of 462.461 mm and stops after 87.545 s of operation. The machine can provide a drilling angle of 0-90° and keep the borehole angle fluctuating within 0.6° with the characteristics of strong adjustability, flexibility, continuity, stability, and low disturbance, which is of great value and significance for studying the drilling trajectory of direct push tools and obtaining more accurate investigation data.

Rapid determination and comparative pharmacokinetics of tetrahydropalmatine in spontaneously hypertensive rats and normotensive rats.

A rapid high-performance liquid chromatographic method was developed and validated for determination of tetrahydropalmatine (THP), an active component of Rhizoma Corydalis, in rat plasma. The samples were prepared using protein precipitation and separated on an Agilent XDB-C(18) column (150 × 4.6 mm, 5 µm) with the mobile phase consisting of methanol­0.1% phosphate acid solution, adjusted with triethylamine to pH 5.5 (65:35). Good linearity was found within 0.10­10.00 µg/mL of THP in rat plasma sample. The intra- and inter-day precision values were less than 10%. The developed method was successfully applied to assess the pharmacokinetics of THP in spontaneously hypertensive rats (SHR) and normotensive rats. After oral administration of a single dose of THP (60 mg/kg), the maximum plasma concentrations were 6.15 ± 2.1 and 7.54 ± 2.9 µg/mL for normotensive rats and SHR, respectively. The mean values of AUC(0­∞) of THP in SHR were 81.44 ± 45.0 µg h/mL, significantly higher (p < 0.05) than in normotensive rats (44.06 ± 19.6 µg h/mL). The t(1/2) and MRT in SHR were much longer than that in healthy Sprague­Dawley rats, indicating slow elimination of THP in SHR. The results indicated that there are some differences in pharmacokinetics of THP in SHR and Sprague­Dawley rats and it is very important to investigate the pharmacokinetic properties of drugs in pathological conditions.

Effects of ketanserin on endotoxic shock and baroreflex function in rodents.

BACKGROUND: Ketanserin, a 5-hydroxytryptamine receptor antagonist, is clinically used as an antihypertensive agent and could enhance baroreflex function. The present work tested the hypothesis that restoration of baroreflex function is an effective treatment for lipopolysaccharide (LPS)-induced shock. METHODS: Kunming mice were injected with LPS (30 mg/kg; intraperitoneal) to induce endotoxic shock. Ketanserin (0.3, 1, 3, or 10 mg/kg; intraperitoneal) was administered immediately after LPS injection. Survival time was monitored, and serum cytokines were analyzed after the onset of LPS. Effects of ketanserin were also examined in IL-10-deficient mice and mice with sinoaortic denervation. Finally, effects of ketanserin on blood pressure, heart rate, and baroreflex sensitivity were examined in Wistar-Kyoto (WKY) rats with endotoxic shock. RESULTS: Ketanserin significantly increased survival time and decreased serum levels of tumor necrosis factor α and interleukin (IL) 1ß in mice with endotoxic shock. At a dose of 10 mg/kg, ketanserin also significantly increased serum IL-10 concentration. The antishock effect of ketanserin was also apparent in IL-10-knockout mice. In mice with sinoaortic denervation, however, ketanserin had little antishock effects. In WKY rats, ketanserin significantly prevented the baroreflex impairment induced by LPS and prolonged the survival time. CONCLUSIONS: Ketanserin could ameliorate endotoxic shock by restoring baroreflex function.

Elevated CEA and CA 19-9 Levels within the Normal Ranges Increase the Likelihood of CRC Recurrence in the Chinese Han Population.

Objective: This study aimed to determine if variations in the expression profiles of CA 19-9 and carcinoembryonic antigen (CEA) within the reference range could serve as possible biomarkers for postoperative CRC recurrence. Method: This retrospective cohort investigation enrolled 2,596 cases of CRC that received curative surgery. Serum CEA/CA 19-9 were measured through chemiluminescence immunoassay (CLIA). Results: During follow-up (median follow-up = 5.2 years), in total, 837 patients experienced recurrence. The fully adjusted hazard ratios (HRs) were significantly higher, ≥1 standard deviation (±SD), in patients with upregulated CEA/CA 19-9 levels (HRCEA = 7.06; HRCA 19 - 9 = 3.98) than in those with downregulated CEA/CA 19-9 levels. The likelihood of recurrence remained consistently greater in cases of elevated CEA/CA 19-9 levels during sensitivity analyses. Conclusions: The findings of this analysis showed that variations in CEA/CA 19-9 expression profiles within the reference range impact CRC recurrence.

Synchronization of a Passive Oscillator and a Liquid Crystal Elastomer Self-Oscillator Powered by Steady Illumination.

Self-oscillators have the advantages of actively harvesting energy from external steady environment, autonomy, and portability, and can be adopted as an engine to drive additional working equipment. The synchronous behavior of self-oscillators and passive oscillators may have an important impact on their functions. In this paper, we construct a self-oscillating system composed of a passive oscillator and an active liquid crystal elastomer self-oscillator powered by steady illumination, and theoretically investigate the synchronization of two coupled oscillators. There exist three synchronous regimes of the two coupled oscillators: static, in-phase, and anti-phase. The mechanisms of self-oscillations in in-phase and anti-phase synchronous regimes are elucidated in detail by calculating several key physical parameters. In addition, the effects of spring constant, initial velocity, contraction coefficient, light intensity, and damping coefficient on the self-oscillations of two coupled oscillators are further investigated, and the critical conditions for triggering self-oscillations are obtained. Numerical calculations show that the synchronous regime of self-oscillations is mainly determined by the spring constant, and the amplitudes of self-oscillations of two oscillators increase with increasing contraction coefficient, light intensity, and spring constant, while decrease with increasing damping coefficient. This study deepens the understanding of synchronization between coupled oscillators and may provide new design ideas for energy harvesters, soft robotics, signal detection, active motors, and self-sustained machinery.

Litter eco-hydrological function characteristics of three typical plant communities in the area of Karst peak-cluster depressions from Guizhou, China.

Litter is an important component of forest ecosystems and plays an important eco-hydrological function. Many studies have been carried out on litter at present, but less research has been carried out on the eco-hydrological service functions of litter in different plant communities in Karst, especially in the area of Karst peak-cluster depressions in southwest China. To reveal the characteristics of the hydrological function of the litter layer of the plant community in the area of Karst peak-cluster depressions around FAST (Five-hundred-meter Aperture Spherical Radio Telescope), three typical plant community litter layers of the broad-leaved forest, coniferous forest, and shrub were selected as research objects, and the hydrological function of the litter layer of different plant community types was studied using the immersion method. The results indicated: 1) The litter layer of the broad-leaved forest plant community has the strongest function of intercepting and regulating precipitation (Mlmax = 24.17±0.33 t/ha, Msv = 19.93±0.21 t/ha), and its hydrological service function is the best. 2) The higher the decomposition degree of litter, the stronger the interception function. 3) The fitted equations for both the litter water-absorption capacity (Qct) and time (t) for plant communities were Qct = b + alnt, and the fitted equations for both the litter water-release capacity (Qst) and time (t) were Qst = a t b. 4) The fitted equations for both the water absorption and release rates (vc and vs) and time (t) of the litter were v = a t -b. The water absorption rates of litter were the fastest within 5 min (15529.01~22634.43 g/kg·h), with the greatest interception and storage function for short-term rainfall.

Bi-Directional Pollution Characteristics and Ecological Health Risk Assessment of Heavy Metals in Soil and Crops in Wanjiang Economic Zone, Anhui Province, China.

Understanding the extent of contamination, sources and various carcinogenic and non-carcinogenic risks associated with different heavy metals in soil-crop systems is crucial for the prevention of heavy metal pollution. A survey was undertaken to determine heavy metal concentrations and degree of pollution in soil-crop systems (rice, wheat, and corn) using various indices such as pollution factor (CF), geo-accumulation index (Igeo), enrichment coefficients and transfer coefficient, and to determine the source of heavy metals pollution in the Wanjiang Economic Zone, Anhui Province, China. A total of 308 pairs of soil-crop samples were collected in this study, comprising 245 pairs of soil-rice samples, 53 pairs of soil-wheat samples, and 10 pairs of soil-corn samples. The concentrations of cadmium (Cd) and nickel (Ni) in the soil of the study area exceeded the national limitation of heavy metals in the soil of China (GB 15618-2018, Soil Environmental Quality: Risk Control Standard for Soil Contamination of Agricultural Land. Ministry of Environmental Protection of China. Beijing. China). The concentrations of copper (Cu), zinc (Zn) and lead (Pb) were also above the national limits to a lesser extent. All eight heavy metals (Cd, Cu, Ni, Pb Zn, arsenic (As), chromium (Cr), and mercury (Hg)) exceeded the background values in the study area. The enrichment coefficients of rice, wheat and maize to Cd, Cu and Zn were higher than those to other elements. On the basis of Igeo, it can be indicated that the rhizosphere soil of rice was slightly polluted by Cd and Hg, while the concentrations of the other heavy metals were below the safety limits. The CF and pollution load index (PLI) indicated that the soil in the study area was heavily contaminated with heavy metals. A principal component analysis identified different sources of soil heavy metal pollution, that is, Cu, Pb, Zn and Cd from industrial sources, Cr and Ni from natural sources, and As and Hg from agricultural sources. The carcinogenic risk of heavy metals was related to the intake of crops. Residents in the study area ingest rice, wheat, and corn on a daily basis. On the basis this study, it is suggested that local governments should pay attention to the carcinogenic risk of heavy metals in rice.