Cyanobacteria possess many adaptations to develop population maxima or "blooms" in lakes and reservoirs. A potential consequence of freshwater blooms of many cyanobacterial species is the production of potent toxins, including the cyclic hepatotoxins, microcystins (MCs). Approximately 70 MC variants have been isolated. Their toxicity to humans and other animals is well studied, because of public health concerns. This review focuses instead on the production and degradation of MCs in freshwater environments and their effects on aquatic organisms. Genetic research has revealed the existence of MC-related genes, yet the expression of these genes seems to be regulated by complex mechanisms and is influenced by environmental factors. In natural water bodies, the species composition of cyanobacterial communities and the ratio of toxic to nontoxic species and strains are largely responsible for total toxin production. Cyanobacteria play vital roles in aquatic food webs, yet production, accumulation, and toxicity patterns of MCs within aquatic food webs remain obscure.

Emerging clean energy technologies such as regenerative fuel cells and rechargeable metal–air batteries have attracted increasing global interest because of their high efficiency and environmental benignity, but the lack of highly active bifunctional electrocatalysts at low cost for both oxygen reduction and evolution reactions (ORR and OER) greatly hinders their commercial applications. Here, we report the multilevel architecture optimization of Co-based nanoparticles (NPs) embedded in hollow N-doped carbon polyhedra for boosting the ORR and OER, which are fabricated by a two-step pyrolysis–oxidation strategy with a Co-based MOF (ZIF-67) as precursor. The key for this strategy lies in the precise and effective control of the oxidation processes of Co NPs, which enables the synthesis of a series of Co–Co3O4-based nanoarchitectures that are embedded in hollow nitrogen-doped carbon polyhedra (HNCP), including core–shell Co/Co3O4, yolk@shell Co@Co3O4, and hollow Co3O4 NPs. Benefiting from its abundant oxygen vacancies and tetrahedral Co2+ and the potential synergies of CoO x species and nitrogen-doped carbon as well as the efficient mass transfer of hollow and yolk–shell structures, the optimal yolk@shell Co3O4/HNCP-40 exhibits high activity for the OER with a low overpotential of 333 mV at 10 mA cm–2 and a small Tafel slope of 69 mV dec–1, which is better than those of commercial IrO2 (its overpotential and Tafel slope are 409 mV at 10 mA cm–2 and 104 mV dec–1, respectively). Meanwhile, the catalyst also exhibits comparable ORR catalytic activity with a half-wave potential of 0.834 V but better stability and methanol tolerance relative to commercial Pt/C (20 wt %), making it a potential bifunctional electrocatalyst for both the OER and ORR. This MOF-templated strategy for multilevel nanostructures provides insights into the development of highly efficient and low-cost bifunctional electrocatalysts for the OER/ORR.

Hollow yolk−shell nanoreactors are of great interest in heterogeneous catalysis owing to their improved mass transfer ability and stability. Here, we report a facile and straight route to synthesize a highly efficient and recyclable yolk−shell Co@C−N nanoreactor with controllable properties by the direct thermolysis of a hollow Zn/Co-ZIF precursor. Based on systematical optimization of the pyrolysis temperature and the shell-thickness of Zn/Co-ZIFs, we could completely anchor and stabilize uniform Co nanoparticles (NPs) in the hollow yolk, accommodated by the Co-ZIF derived N-doped carbon nanosheets. This nanosheet-assembled yolk was further confined by a permeable and robust N-doped carbon (C−N) shell to protect the Co NPs against leaching and also enabled the reaction to take place in the hollow void. Consequently, the optimal yolk−shell Co@C−N nanoreactor showed a significantly enhanced catalytic activity for the aqueous oxidation of alcohols, yielding >99% conversion under atmospheric air and base-free conditions, which was much higher than that of the solid counterparts derived from pure ZIF-67 and solid core−shell ZIF-67@ZIF-8 precursors (with 14% and 59% conversion under the same reaction condition, respectively). The enhanced catalytic activity should be attributed to the yolk−shell structure that could facilitate the transport of reactant/ product and the strong interaction between the Co NPs and N-doped carbon nanosheet to afford positive synergistic effects. Moreover, this catalyst also showed good recyclability, magnetically reusability, and general applicability for a broad substrate scope, further highlighting the structure superiority of our yolk−shell nanoreactor. This strategy might open an avenue to synthesize various hollow yolk−shell nanoreactors with controllable structures and enhanced catalytic performances.

Palladium precursors were encapsulated through ligand design prior to the MOF assembly, achieving uniformly distributed Pd NPs inside the cavities of MOFs. The embedded Pd NPs exhibited significantly improved catalytic efficiencies as compared to those synthesized by traditional impregnation method, due to the nano-confinement and electron-donation effects offered by MOFs.

Multishell hollow nanoarchitectures are one of the most important branches in the nanomaterial field due to their enormous potential in many fields, but synthesizing them in a well-controlled manner remains challenging. Herein, we present a general strategy for the construction of multishell hollow metal/nitrogen/carbon dodecahedrons (metal@NC) with well-defined and precisely controlled architectures. This strategy is based on the pyrolysis of multilayer solid ZIFs prepared by a step-by-step crystal growth approach, which enables precise control over the shell number and composition of the resultant hollow metal@NC. Impressively, our strategy can be further extended to the synthesis of yolk@multishell hollow structures or multishell hollow structures that are assembled by carbon nanotubes. The multishell hollow structures can efficiently facilitate the mass diffusion, which together with the high dispersity and increased surface area are responsible for their significantly enhanced catalytic performances for the selective hydrogenation of biomass-derived furfural to cyclopentanol when compared with their solid and single-shell counterparts. We anticipate that our general strategy would shed light on the rational design and accurate construction of other complex multishell hollow materials for various important yet challenging applications.

A novel ZnO@C–N–Co core–shell nanostructure was successfully prepared by the direct pyrolysis of a hollow Zn/Co–ZIF matrix, which showed a significantly improved performance for the model pollutant photodegradation due to the highly synergistic effects from C–N–Co shell and ZnO core.

Glioblastoma multiforme (GBM) has a high recurrence and mortality rate. Because of a poor understanding of the mechanism for this disease, treatment regimens have remained limited. Vimentin, one of the major cytoskeletal proteins, is associated with cellular structure. However, the function of vimentin in GBM is still undefined. In the present study, we investigated the expression level of vimentin in 179 GBM tissues using immunohistochemistry. We found that the vimentin expression level was associated with the time to progression (P=0.029). A Kaplan-Meier analysis revealed that patients with high vimentin expression had a significantly shorter overall survival (P=0.0002) and progression-free survival (P=0.0001) compared with those with low expression. Furthermore, in vitro experiments showed that withaferin-A, a chemical inhibitor of vimentin, could inhibit GBM cell migration and invasion activity when its concentrations were <0.5 μM, and higher concentrations of withaferin-A could decrease the viability of U251and U87 cells significantly. In conclusion, our results indicated that vimentin may play an important role in the progression of GBM.

In this work, the first example of a facile one-pot route for the synthesis of Pd@MOF composites without additional stabilizing agents is developed. The as-synthesized MOF composite shows high activity and chemoselectivity in the hydrogenation of cinnamaldehyde even under atmosphere pressure of H2 and at room temperature.