Purification and characterization of anti-phytopathogenic fungi angucyclinone from soil-derived Streptomyces cellulosae.

Actinomycete strain YIM PH20352, isolated from the rhizosphere soil sample of Panax notoginseng collected in WenShang, Yunnan Province, China, exhibited antifungal activity against some phytopathogenic fungi. The structures of bioactive molecules, isolated from the ethyl acetate extract of the fermentation broth of the strain, were identified as rabelomycin (1) and dehydrorabelomycin (2) based on extensive spectroscopic analyses. Compound 1 exhibited antifungal activity against four tested root-rot pathogens of the Panax notoginseng including Plectosphaerella cucumerina, Alternaria panax, Fusarium oxysporum, and Fusarium solani with the MIC values at 32, 64, 128, and 128 μg/mL, respectively.

Design and Remarkable Efficiency of the Robust Sandwich Cluster Composite Nanocatalysts ZIF-8@Au@ZIF-67.

Heterogeneous catalysts with precise surface and interface structures are of great interest to decipher the structure-property relationships and maintain remarkable stability while achieving high activity. Here, we report the design and fabrication of the new sandwich composites ZIF-8@Au@ZIF-67[tkn] and ZIF-8@Au@ZIF-8[tkn] [tkn = thickness of shell] by coordination-assisted self-assembly with well-defined structures and interfaces. The composites ZIF-8@Au@ZIF-67 efficiently catalyzed both 4-nitrophenol reduction and terminal alkyne carboxylation with CO under ambient conditions with remarkably improved activity and stability, compared to the simple components Au/ZIF-8 and Au@ZIF-8, highlighting the highly useful function of the ultrathin shell.

A model of HBV infection with intervention strategies: dynamics analysis and numerical simulations.

In this paper, we analyze the effect of environment noise on the transmission dynamics of a stochastic hepatitis B virus (HBV) infection model with intervention strategies. By using the Markov semigroups theory, we define the stochastic basic reproduction number and find it can be used to govern disease extinction or persistence. When it is less than one, under a mild extra condition, the stochastic system has a disease-free equilibrium and the disease is predicted to die out with probability one.