•N-induced p release was most pronounced in summer and from sediment rich in organic matter.•Sediment acidification by long-term n application partly explained the p release.•A positive feedback loop ...of “P-algae-fish” was found.•In this loop, algae-stimulated fish-biomass increased disturbance, promoting p release.
The unprecedented global increase in the anthropogenic-derived nitrogen (N) input may have profound effects on phosphorus (P) dynamics and may potentially lead to enhanced eutrophication as demonstrated in short-term mesocosm experiments. However, the role of N-influenced P release is less well studied in large-scale ecosystems. To gain more insight into ecosystem effects, we conducted a five-year large-scale experiment in ten ponds (700–1000 m2 each) with two types of sediments and five targeted total N concentrations (TN) by adding NH4Cl fertilizer (0.5, 1, 5, 10, and 25 mg N L−1). The results showed that: (ⅰ) The sediment P release increased significantly when TN exceeded 10–25 mg N L−1. (ⅱ) The most pronounced sediment P release increase occurred in summer and from sediments rich in organic matter (OMSed). (ⅲ) TN, algal biomass, fish biomass, non-algal turbidity, sediment pH, and OMSed were the dominant factors explaining the sediment P release, as suggested by piecewise structural equation modeling. We propose several mechanisms that may have stimulated P release, i.e. high ammonium input causes a stoichiometric N:P imbalance and induce alkaline phosphatase production and dissolved P uptake by phytoplankton, leading to enhanced inorganic P diffusion gradient between sediment and water; higher pelagic fish production induced by the higher phytoplankton production may have led increased sediment P resuspension through disturbance; low oxygen level in the upper sediment caused by nitrification and organic decomposition of the settled phytoplankton and, finally, long-term N application-induced sediment acidification as a net effect of ammonium hydrolysis, nitrification, denitrification; The mechanisms revealed by this study shed new light on the complex processes underlying the N-stimulated sediment P release, with implications also for the strategies used for restoring eutrophicated lakes.
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Large dynamic stress off the fault incurs an inelastic response and energy loss, which contributes to the fracture energy, limiting the rupture and slip velocity. Using an explicit finite element ...method, we model three‐dimensional dynamic ruptures on a vertical strike‐slip fault in a homogeneous half‐space. The material is subjected to a pressure‐dependent Drucker‐Prager yield criterion. Initial stresses in the medium increase linearly with depth. Our simulations show that the inelastic response is confined narrowly to the fault at depth. There the inelastic strain is induced by large dynamic stresses associated with the rupture front that overcome the effect of the high confining pressure. The inelastic zone increases in size as it nears the surface. For material with low cohesion (∼5 MPa) the inelastic zone broadens dramatically near the surface, forming a “flowerlike” structure. The near‐surface inelastic strain occurs in both the extensional and the compressional regimes of the fault, induced by seismic waves ahead of the rupture front under a low confining pressure. When cohesion is large (∼10 MPa), the inelastic strain is significantly reduced near the surface and confined mostly to depth. Cohesion, however, affects the inelastic zone at depth less significantly. The induced shear microcracks show diverse orientations near the surface, owing to the low confining pressure, but exhibit mostly horizontal slip at depth. The inferred rupture‐induced anisotropy at depth has the fast wave direction along the direction of the maximum compressive stress.
Summary
Objective
MicroRNAs (miRNAs) are noncoding small RNAs that control gene expression at the posttranscriptional level. Some dysregulated miRNAs have been shown to play important roles in ...epileptogenesis. The aim of this study was to determine if miR‐199a‐5p regulates seizures and seizure damage by targeting the antiapoptotic protein silent information regulator 1 (SIRT1).
Methods
Hippocampal expression levels of miR‐199a‐5p, SIRT1, and acetylated p53 were quantified by quantitative real‐time polymerase chain reaction (RT‐PCR) and Western blotting in the acute, latent, and chronic stages of epilepsy in a rat lithium‐pilocarpine epilepsy model. Silencing of miR‐199a‐5p expression in vivo was achieved by intracerebroventricular injection of antagomirs. The effects of targeting miR‐199a‐5p and SIRT1 protein on seizure and epileptic damage post‐status epilepticus were assessed by electroencephalography (EEG) and immunohistochemistry, respectively.
Results
miR‐199a‐5p expression was up‐regulated, SIRT1 levels were decreased, and neuron loss and apoptosis were induced in epilepsy model rats compared with normal controls, as determined by up‐regulation of acetylated p53 and cleaved caspase‐3 expression. In vivo knockdown of miR‐199a‐5p by an antagomir alleviated the seizure‐like EEG findings and protected against neuron damage, in accordance with up‐regulation of SIRT1 and subsequent deacetylation of p53. Furthermore, the seizure‐suppressing effect of the antagomir was partly SIRT1 dependent.
Significance
The results of this study suggest that silencing of miR‐199a‐5p exerts a seizure‐suppressing effect in rats, and that SIRT1 is a direct target of miR‐199a‐5p in the hippocampus. The effect of miR‐199a‐5p on seizures and seizure damage is mediated via down‐regulation of SIRT1. The miR‐199a‐5p/SIRT1 pathway may thus represent a potential target for the prevention and treatment of epilepsy and epileptic damage.
Cloud base height (CBH) is crucial for parameterizing the cloud vertical structure (CVS), but knowledge concerning the temporal and spatial distribution of CBH is still poor owing to the lack of ...large-scale and continuous CBH observations. Taking advantage of high temporal and spatial resolution observations from the Advanced Himawari Imager (AHI) on board the geostationary Himawari-8 satellite, this study investigated the climatology of CBH by applying a novel CBH retrieval algorithm to AHI observations. We first evaluated the accuracy of the AHI-derived CBH retrievals using the active measurements of CVS from the CloudSat and CALIPSO satellites, and the results indicated that our CBH retrievals for single-layer clouds perform well, with a mean bias of 0.3 ± 1.9 km. Therefore, the CBH climatology was compiled based on AHI-derived CBH retrievals for single-layer clouds for the time period between September 2015 and August 2018. Overall, the distribution of CBH is tightly associated with cloud phase, cloud type, and cloud top height and also exhibits significant geographical distribution and temporal variation. Clouds at low latitudes are generally higher than those at middle and high latitudes, with CBHs peaking in summer and lowest in winter. In addition, the surface type affects the distribution of CBH. The proportion of low clouds over the ocean is larger than that over the land, while high cloud occurs most frequently over the coastal area. Due to periodic changes in environmental conditions, cloud types also undergo significant diurnal changes, resulting in periodic changes in the vertical structure of clouds.
Hydrogen purification is an important part of hydrogen energy utilization. This study aimed to perform hydrogen purification of multi-component gas (H2/CO2/CH4/CO/N2 = 0.79/0.17/0.021/0.012/0.007) by ...one-column vacuum pressure swing adsorption (VPSA) and pressure swing adsorption (PSA). AC5-KS was selected as the adsorbent for hydrogen purification due to its greater adsorption capacity compared to R2030. Furthermore, VPSA and PSA 10-step cycle models were established to simulate the hydrogen purification process using the Aspen Adsorption platform. The simulation results showed that the hydrogen purification performance of VPSA is better than that of PSA on AC5-KS adsorbent. The effects of feeding time and purging time on hydrogen purity and recovery were also discussed. Results showed that feeding time has a negative effect on hydrogen purity and a positive effect on hydrogen recovery, while purging time has a positive effect on hydrogen purity and a negative effect on hydrogen recovery. By using an artificial neural network (ANN), the relationship between the inputs (feeding time and purging time) and outputs (hydrogen purity and recovery) was established. Based on the ANN, the interior point method was applied to optimize hydrogen purification performance. Considering two optimization cases, the optimized feeding time and purging time were obtained. The optimization results showed that the maximum hydrogen recovery reached 88.65% when the feeding time was 223 s and the purging time was 96 s. The maximum hydrogen purity reached 99.33% when the feeding time was 100 s and the purging time was 45 s.
Previous studies have shown that CCL2 may cause chronic pain, but the exact mechanism of central sensitization is unclear. In this article, we further explore the presynaptic role of CCL2. Behavioral ...experiments show that intervertebral foramen injection CCR2 antagonists into dorsal root ganglion (DRG) can inhibit the inflammatory pain caused by CCL2 in spinal cord. We raised the question of the role of presynaptic CCR2 in the spinal dorsal horn. Subsequent electron microscopy experiments showed that CCR2 was expressed in the presynaptic CGRP terminal in the spinal dorsal horn. CCL2 can enhance presynaptic calcium signal. Whole-cell patch-clamp recordings showed that CCL2 can enhance NMDAR-eEPSCs through presynaptic effects, and further application of glutamate sensor method proved that CCL2 can act on presynaptic CCR2 to increase the release of presynaptic glutamate. In conclusion, we suggest that CCL2 can directly act on the CCR2 on presynaptic terminals of sensory neurons in the spinal dorsal horn, leading to an increase in the release of presynaptic glutamate and participate in the formation of central sensitization.
Layered cloud cover (LCC), that is, cloud cover at different levels, is crucial for estimating cloud radiative effects and modeling climate change. However, accurate LCC characterization using ...passive satellite measurements is challenging because of the difficulties in resolving cloud vertical structures. In this study, we developed a novel method to estimate LCC from geostationary satellite radiometric measurements. The proposed method resolves cloud vertical structures by retrieving cloud-top and cloud-base heights for both single- and multi-layer clouds; thus, better estimating LCC. Our results agreed well with active satellite measurements, showing identification accuracies of 86%, 90%, and 91% for high, medium, and low clouds, respectively. Additionally, our LCC estimates derived from satellite measurements were used to evaluate those from atmospheric reanalysis. The annual averaged total, high, medium, and low cloud covers given by our methods were 0.681, 0.393, 0.356, and 0.455, respectively, while those from ERA-5 were 0.623, 0.415, 0.274, and 0.392, respectively. These results indicate that the total cloud cover determined by ERA-5 was lower than that derived from satellite measurements, potentially as a result of medium and low-level clouds.
Hydrothermal synthesis was used to synthesize SnCNx photocatalysts with different SnO2 content. The SnCN4 photocatalyst has a well photocatalytic degradation efficiency for pollutants under visible ...light irradiation. Rising photoactivity may be related to the synergistic effect between SnO2 and g-C3N4, which leads to an increase in visible light absorption. The interface interaction between the two components promotes effective charge transfer, thereby increasing visible light absorption. The ·O2¯ and ·OH are the main reaction species in the degradation reaction and we also discussed the possible mechanism of this process.
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•Cubic SnO2 (ca. 50–100 nm) are successfully constructed by an incineration method.•An effective interfacial charge transfer between SnO2 and g-C3N4 is observed.•MDZ and RhB are quickly photodegraded completely by visible light, respectively.•SnO2/g-C3N4 shows better photocatalytic activity than SnO2 or g-C3N4.
Saffron is a medicinally important species of the Iridaceae family. Saffron’s quality depends on the concentration of secondary metabolites. In this study, GC–MS and LC–MS were utilized to dissect ...the different metabolites profile of two saffron produced in Iran and China. As a result, a total of 325 differential metabolites (237 from LC–MS, 88 from GC–MS) were identified. These differential metabolites were grouped into the following categories such as lipids, alkaloids, amino acids, terpenoids, organic acids, and flavonoids in saffron from the LC–MS analysis. The differential metabolites mainly concentrated on metabolic pathways, nucleotide metabolism, purine metabolism, and flavonoid biosynthesis. In Iran vs. China, the category of flavonoids includes Styrene, Apigenin-7-O-(6''-p-Coumaryl)glucoside, Houpulin F, Apigenin-5-O-glucoside, Tiglic acid; 2-Methyl-2-Butenoic Acid, p-Cymene, and 2,4-Nonadienal, (E,E)-. The terpenoids including downregulated Cafestol, rhodomollein XI, inumakiol G, D-Limonene, Bicyclo3.1.0hexane, 4-methylene-1-(1-methylethyl)- and upregulated rhodomollein XI were significantly different identified in Iran vs. China. In conclusion, the saffron from different cultivation areas possess many metabolites that are beneficial for health, including lipids, alkaloids, amino acids, terpenoids, organic acids, and flavonoids. Thus, compared with Iran, saffron from China have a higher medicinal value. This study provides a direction for the subsequent development and utilization of saffron.
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