Precise estimation of sediment transport capacity (Tc) is critical to the development of physically based erosion models. Few data are available for estimating Tc on steep slopes. The objectives of this study were to evaluate the effects of unit flow discharge (q), slope gradient (S), and mean flow velocity on Tc in shallow flows and to investigate the relationship between Tc and shear stress, stream power, and unit stream power on steep slopes using a 5‐m‐long and 0.4‐m‐wide nonerodible flume bed. Unit flow discharge ranged from 0.625 × 10−3 to 5 × 10−3 m2 s−1 and slope gradient from 8.8 to 46.6%. The diameter of the test riverbed sediment varied from 20 to 2000 μm, with a median diameter of 280 μm. The results showed that Tc increased as a power function with discharge and slope gradient with a coefficient of Nash–Sutcliffe model efficiency (NSE) of 0.95. The influences of S on Tc increased as S increased, with Tc being slightly more sensitive to q than to S The Tc was well predicted by shear stress (NSE = 0.97) and stream power (NSE = 0.98) but less satisfactorily by unit stream power (NSE = 0.92) for the slope range of 8.8 to 46.6%. Mean flow velocity was also a good predictor of Tc (NSE = 0.95). Mean flow velocity increased as q and S increased in this study. Overall, stream power seems to be the preferred predictor for estimating Tc for steep slopes; however, the predictive relationships derived in this study need to be evaluated further in eroding beds using a range of soil materials under various slopes.
The genus Thielavia is morphologically defined by having non-ostiolate ascomata with a thin peridium composed of textura epidermoidea, and smooth, single-celled, pigmented ascospores with one germ pore. Thielavia is typified with Th. basicola that grows in close association with a hyphomycete which was traditionally identified as Thielaviopsis basicola. Besides Th. basicola exhibiting the mycoparasitic nature, the majority of the described Thielavia species are from soil, and some have economic and ecological importance. Unfortunately, no living type material of Th. basicola exists, hindering a proper understanding of the classification of Thielavia. Therefore, Thielavia basicola was neotypified by material of a mycoparasite presenting the same ecology and morphology as described in the original description. We subsequently performed a multi-gene phylogenetic analyses (rpb2, tub2, ITS and LSU) to resolve the phylogenetic relationships of the species currently recognised in Thielavia. Our results demonstrate that Thielavia is highly polyphyletic, being related to three family-level lineages in two orders. The redefined genus Thielavia is restricted to its type species, Th. basicola, which belongs to the Ceratostomataceae (Melanosporales) and its host is demonstrated to be Berkeleyomyces rouxiae, one of the two species in the “Thielaviopsis basicola” species complex. The new family Podosporaceae is sister to the Chaetomiaceae in the Sordariales and accommodates the re-defined genera Podospora, Trangularia and Cladorrhinum, with the last genus including two former Thielavia species (Th. hyalocarpa and Th. intermedia). This family also includes the genetic model species Podospora anserina, which was combined in Triangularia (as Triangularia anserina). The remaining Thielavia species fall in ten unrelated clades in the Chaetomiaceae, leading to the proposal of nine new genera (Carteria, Chrysanthotrichum, Condenascus, Hyalosphaerella, Microthielavia, Parathielavia, Pseudothielavia, Stolonocarpus and Thermothielavioides). The genus Canariomyces is transferred from Microascaceae (Microascales) to Chaetomiaceae based on its type species Can. notabilis. Canariomyces is closely related to the human-pathogenic genus Madurella, and includes three thielavia-like species and one novel species. Three monotypic genera with a chaetomium-like morph (Brachychaeta, Chrysocorona and Floropilus) are introduced to better resolve the Chaetomiaceae and the thielavia-like species in the family. Chrysocorona lucknowensis and Brachychaeta variospora are closely related to Acrophialophora and three newly introduced genera containing thielavia-like species; Floropilus chiversii is closely related to the industrially important and thermophilic species Thermothielavioides terrestris (syn. Th. terrestris). This study shows that the thielavia-like morph is a homoplastic form that originates from several separate evolutionary events. Furthermore, our results provide new insights into the taxonomy of Sordariales and the polyphyletic Lasiosphaeriaceae.
This work reported a green method of synthesizing silver nanoparticles (AgNPs) with glucose acting as reducing agents to improve the conductivity of conductive ink. Silver nitrate, glucose, and polyvinylpyrrolidone (PVP), were used as silver precursor, reducing agent, and capping agent, respectively. The optimal condition of synthesizing AgNPs was obtained by varying the reactant ratio and temperature. The AgNPs were characterized by X-ray diffraction (XRD), UV-visible spectroscopy (UV-Vis), and scanning electron microscope (SEM). The obtained AgNPs with diameters of 80 to 100 nm were almost spherical and they were redispersed well in polyurethane acrylate (PUA). Compared with traditional hydrazine hydrate, the prepared AgNPs were better with respect to uniform size, dispersion, stability, and the absence residual solvent. After UV sintering, the conductivity (2.3×10 5 S/m) and mechanical properties of prepared conductive ink were good. Therefore, using glucose as a reducing agent to prepare AgNPs conductive ink is feasible and noteworthy because it is an extremely common material.
The antibacterial activity and acting mechanism of hypocrellin A (HA) were conducted regarding in vitro activity of HA on Staphylococcus aureus GZ86 by analyzing the growth, permeability, and morphology of the bacterial cells following treatment with HA. The experimental results indicated 1.5 mg/l HA could completely inhibit the growth of 10⁷ CFU/ml S. aureus cells in liquid beef extract-peptone medium under a halogen-tungsten lamp for 120 min. Meanwhile, HA resulted in the leakage of reducing sugars and proteins and induced the respiratory chain dehydrogenases into inactive state, suggesting that HA were able to destroy the permeability of the bacterial membranes. When the cells of S. aureus were exposed to 2.5 mg/l HA under a halogen-tungsten lamp for 120 min, many pits and gaps were observed in bacterial cells by scanning electron microscopy, and the cell wall was fragmentary, indicating the bacterial cells were damaged severely. The experiments strongly confirmed the contribution of multiform reactive oxygen species (ROS) to bactericidal effect. In conclusion, the combined results suggested that ROS may damage the structure of bacterial cell wall and depress the activity of some membranous enzymes, which cause S. aureus bacteria to die eventually.
The family Thelebolaceae belongs to the order Thelebolales, class Leotiomycetes, and contains 22 genera. In this study, we introduce a new genus Solomyces gen. nov. in the family Thelebolaceae, which is supported by morphological observation and multilocusbased [internal transcribed spacers (ITS) + LSU and ITS + LSU+ MCM7+ EF1A+ RPB2] phylogenetic analysis. Maximum-likelihood and Bayesian phylogenetic inference analyses indicated that Solomyces is a distinct genus within this family. The new genus is compared against related Thelebolaceae genera, and its description and illustration are provided. This genus comprises one new species and one unnamed species (including two strains). We also report the addition of four new species -Pseudogymnoascus shaanxiensis, Pseudogymnoascus guizhouensis, Pseudogymnoascus sinensis, and Geomyces obovatus -in the family Thelebolaceae and present their morphological and phylogenetic characterizations.
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