Background and aims
This study explores trends in soil fungal patterns, potential functions and their responses to carbon and nitrogen applications over alpine grassland succession in the Qilian ...Mountain area of China.
Methods
The soil fungal community was characterized via Illumina sequencing of ITS genes. The FUNGuild database was used to predict functional groups in alpine grassland succession from swamp meadow to alpine meadow and steppe meadow. The levels of soil carbon and nitrogen, vegetation carbon and nitrogen, and soil enzyme activity were also assessed.
Results
Soil fungal operational taxonomic units increased from swamp meadow to alpine meadow stage and then reached a relatively stable state in steppe meadow successional stage. This result is consistent with the changing trend of sobs and Chao1 index. Moreover, the soil fungal community differed significantly between different succession stages. During succession, while most phyla of soil fungi followed linear decreasing trends,
Ascomycota
was the dominant fungal phylum. Its abundance increased significantly, from 60.00% in swamp meadow to 72.26% in steppe meadow. The relative abundances of
Pathotroph
and
Saprotroph
fungal functions increased with successional stages, while
Symbiotroph
did not change significantly. Soil ammonium nitrogen and organic carbon levels dominated the effect on the soil fungal microbial community and functional groups.
Conclusion
These findings indicate that the fungal community shifted dramatically in the first stage(swamp to alpine meadow) of succession but then reached a relatively stable state in the second(alpine to steppe meadow) successional stage. The soil fungal function group did not follow the same successional trajectory. Soil ammonium nitrogen and soil organic carbon levels imposed the strongest influence on the fungal community and its function, respectively.
A self-healing dielectric elastomer actuator (DEA) composed with sandwich structure using silicone rubber as an encapsulating thin shell layer and a piece of open-cell silicone foam filled with ...hydroxyl silicone oil as an interpenetrating core layer was designed and developed. The novel DEA showed an improved actuated out-of-plane displacement of 10.2 mm and an area strain of 52 % at an electric field of 22.7 kV mm−1 without pre-stretching, which was over 6 times higher than that of raw silicone rubber. Moreover, the DEA provided a blocking force of 499.1 Pa when displaced out-of-plane by 3.0 mm and was used to grasp a balloon. In addition, such actuator presented excellent self-healing ability after an electrical breakdown, which is crucial for improving reliability and lifetime of the DEA device. Therefore, the above DEA provides new understanding of the concept of high-performance actuators for promising applications in artificial muscles and soft robots.
•Kinetic model on Thermal Dissociation and Oligomerization of DCPD is proposed.•Complete kinetic parameters were obtained in a microreactor with high temperature and pressure.•High temperature and ...short residence time should be effective for obtaining more CPD.
Dicyclopentadiene(DCPD) is an important 10-carbon olefin mostly derived from the pyrolysis of total petroleum hydrocarbons to ethylene. DCPD has two isomers, endo-dicyclopentadiene(endo-DCPD) and exo-dicyclopentadiene(exo-DCPD), and can be thermally decomposed into cyclopentadiene (CPD). This reaction is also reversible. A further addition reaction of CPD with endo-DCPD or exo-DCPD can produce tricyclopentadiene(TCPD). Using a microreactor, the kinetics of the decomposition and condensation of DCPD were investigated systematically at 5 MPa, 180–240 °C. The complete reaction rate and kinetic parameters of the reaction system were obtained in this work. The kinetic results showed that high temperature and short residence time were effective for obtaining more of the product, CPD.
Clarifying the response of soil microbial communities to the change of different vegetation types on a small regional scale is of great significance for understanding the sustainability of grassland ...development. However, the distribution patterns and driving factors of the microbial community are not well understood in the Qilian Mountains. Therefore, we characterized and compared the soil microbial communities underlying the four vegetation types in a national natural reserve (reseeded grassland, swamp meadow, steppe meadow, and cultivated grassland) using high-throughput sequencing of the 16S rRNA and ITS. Meanwhile, the plant community and soil physicochemical characteristics were also determined. The results showed that bacterial and fungal communities in all vegetation types had the same dominant species, but the relative abundance differed substantially, which caused significant spatial heterogeneities on the small regional scale. Specifically, bacteria showed higher variability among different vegetation types than fungi, among which the bacterial and fungal communities were more sensitive to the changes in soil than to plant characteristics. Furthermore, soil organic carbon affected the widest portion of the microbial community, nitrate-nitrogen was the main factor affecting bacteria, and aboveground plant biomass was the main factor affecting fungi. Collectively, these results demonstrate the value of considering multiple small regional spatial scales when studying the relationship between the soil microbial community and environmental characteristics. Our study may have important implications for grassland management following natural disturbances or human alterations.
This paper develops a weak-label-based global and local multi-view multi-label learning with three-way clustering (WL-GLMVML-ATC) to solve multi-view multi-label data sets and exploit more authentic ...global and local label correlations of both the whole data set and each view simultaneously. Different from the traditional learning methods, WL-GLMVML-ATC pays more attention to the solutions of weak-label cases and uncertain relationships of clusters with the usage of Universum and active three-way clustering. According to Universum notion, even though the size of labeled instances is much more smaller than the unlabeled ones, the useful sample information can still be enhanced. Through the active three-way clustering strategy, the belongingness of instances to a cluster depend on the probabilities of uncertain instances belonging to core regions. This strategy brings a more authentic local label correlation since many traditional methods suppose that instances and the corresponding clusters always exhibit certain relationships such as belong-to definitely and not belong-to definitely. This hypothesis is not ubiquitous in real-world applications. According to the experiments, we can see WL-GLMVML-ATC (1) achieves a better performance, be superior to the classical multi-view learning methods and multi-label learning methods in statistical, advances the development of these learning methods in final; (2) won’t add too much running time; (3) has a good convergence and ability to process multi-view multi-label data sets.
Let \(D=(V,A)\) be a digraph of order \(n\), \(S\) a subset of \(V\) of size \(k\) and \(2\le k\leq n\). A strong subgraph \(H\) of \(D\) is called an \(S\)-strong subgraph if \(S\subseteq V(H)\). A ...pair of \(S\)-strong subgraphs \(D_1\) and \(D_2\) are said to be arc-disjoint if \(A(D_1)\cap A(D_2)=\emptyset\). Let \(\lambda_S(D)\) be the maximum number of arc-disjoint \(S\)-strong subgraphs in \(D\). The strong subgraph \(k\)-arc-connectivity is defined as $$\lambda_k(D)=\min\{\lambda_S(D)\mid S\subseteq V(D), |S|=k\}.$$ The parameter \(\lambda_k(D)\) can be seen as a generalization of classical edge-connectivity of undirected graphs. In this paper, we first obtain a formula for the arc-connectivity of Cartesian product \(\lambda(G\Box H)\) of two digraphs \(G\) and \(H\) generalizing a formula for edge-connectivity of Cartesian product of two undirected graphs obtained by Xu and Yang (2006). Then we study the strong subgraph 2-arc-connectivity of Cartesian product \(\lambda_2(G\Box H)\) and prove that \( \min\left \{ \lambda \left ( G \right ) \left | H \right | , \lambda \left ( H \right ) \left |G \right |,\delta ^{+ } \left ( G \right )+ \delta ^{+ } \left ( H \right ),\delta ^{- } \left ( G \right )+ \delta ^{- } \left ( H \right ) \right \}\ge\lambda_2(G\Box H)\ge \lambda_2(G)+\lambda_2(H)-1.\) The upper bound for \(\lambda_2(G\Box H)\) is sharp and is a simple corollary of the formula for \(\lambda(G\Box H)\). The lower bound for \(\lambda_2(G\Box H)\) is either sharp or almost sharp i.e. differs by 1 from the sharp bound. We also obtain exact values for \(\lambda_2(G\Box H)\), where \(G\) and \(H\) are digraphs from some digraph families.
The increased proliferation and migration of vascular smooth muscle cells （VSMCs） are key events in the development of atherosclerotic lesions. Baicalin, an herb-derived flavonoid compound, has been ...previously shown to induce apoptosis and growth inhibition in cancer cells through multiple pathways. However, the potential role of baicalin in regulation of VSMC proliferation and prevention of cardiovascular diseases remains unexplored. In this study, we show that pretreatment with baicalin has a dose-dependent inhibitory effect on PDGF-BB-stimulated VSMC pro- liferation, accompanied with the reduction of proliferating cell nuclear antigen （PCNA） expression. We also show that baicalin-induced growth inhibition is associated with a decrease in cyclin E-CDK2 activation and increase in p27 level in PDGF-stimulated VSMCs, which appears to be at least partly mediated by blockade of PDGF recep- tor ~ （PDGFR~）-extracellular signal-regulated kinase 1/2 （ERK1/2） signaling. In addition, baicalin was also found to inhibit adhesion molecule expression and cell migration induced by PDGF-BB in VSMCs. Furthermore, using an animal carotid arterial balloon-injury model, we found that baicalin significantly inhibited neointimal hyperplasia. Taken together, our results reveal a novel function of baicalin in inducing growth arrest of PDGF-stimulated VSMCs and suppressing neointimal hyperplasia after balloon injury, and suggest that the underlying mechanism involves the inhibition of cyclin E-CDK2 activation and the increase in p27 accumulation via blockade of the PDGFR~-ERK1/2 signaling cascade.
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