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A facile and versatile microwave‐assisted and shell‐confined Kirkendall diffusion strategy is used to fabricate ultrasmall hollow nanoparticles by modulating the growth and thermal conversion of metal–organic framework (MOF) nanocrystals on graphene. This method involves that the adsorption of microwave by graphene creates a high‐energy environment in a short time to decompose the in situ grown MOF nanocrystals into well‐dispersed uniform core–shell nanoparticles with ultrasmall size. Upon a shell‐confined Kirkendall diffusion process, hollow nanoparticles of multi‐metal oxides, phosphides, and sulfides with the diameter below 20 nm and shell thickness below 3 nm can be obtained for the first time. Ultrasmall hollow nanostructures such as Fe2O3 can promote much faster charge transport and expose more active sites as well as migrate the volume change stress more efficiently than the solid and large hollow counterparts, thus demonstrating remarkable lithium‐ion storage performance.

Cellulose acetate butyrate (CAB) and cellulose acetate propionate (CAP) were prepared homogeneously in a 1-allyl-3-methylimidazolium chloride (AmimCl) ionic liquid system from sugarcane bagasse (SB). The reaction temperature, reaction time, and molar ratio of butyric (propionic) anhydride/anhydroglucose units in the cellulose affect the butyryl (B) or propionyl (P) content of CAB or CAP samples. The (13)C NMR data revealed the distribution of the substituents of CAB and CAP. The thermal stability of sugar cane bagasse cellulose was found by thermogravimetric analysis to have decreased after chemical modification. After reaction, the ionic liquid was effectively recycled and reused. This study provides a new way for high-value-added utilization of SB and realizing the objective of turning waste into wealth.

BackgroundLow concentration NaHCO3 (ca. 12 mM) had been demonstrated to be an excellent carbon source for industrially important green alga Chlorella vulgaris and high concentration NaHCO3 (e.g. 160 mM) had been shown to be capable of controlling protozoa and stimulating lipid accumulation of another green alga, i.e., Neochloris oleoabundans. Furthermore, little was known about the mechanisms of the effects of NaHCO3 on microalgae. Thorough studies on the effects of high NaHCO3 on C. vulgaris and their mechanisms were therefore warranted.MethodsWe systematically compared the cell growth, lipid production, and cell morphology of the industrially important C. vulgaris in 160 mM NaHCO3 or 160 mM NaCl media at different pH levels. These data allowed us to analyze the effects of total dissolved inorganic carbon (DIC) and individual DIC species on C. vulgaris. Cell growth of C. vulgaris at a range of concentrations at 160 mM or lower was also studied.ResultsCellular lipid cell content of 494 mg g−1 and lipid productivity of 44.5 mg L−1 day−1 were obtained at 160 mM NaHCO3 and pH 9.5. High concentration NaHCO3 (e.g. 160 mM) was inhibitive to cell growth but stimulating to lipid accumulation and caused unicellular C. vulgaris to transfer to colonial cells. Increasing pH in the range of 7.5–9.5 caused increasing inhibition to cell growth in 160 mM NaCl. Whereas the optimal pH for cell growth was 8.5 for 160 mM NaHCO3 cultures. Comparative experiments with 0–160 mM NaHCO3 indicate that 10 mM was the optimal concentration and increasing NaHCO3 from 10 to 160 mM caused increasing inhibition to cell growth.ConclusionsHigh concentration DIC was inhibitor to cell growth but stimulator to lipid accumulation of C. vulgaris. It caused unicellular C. vulgaris to transform to colonial cells. Results suggest that high concentration of a particular DIC species, i.e., dCO2, was the primary stress responsible for cell growth inhibition. Where CO32− was likely the DIC species responsible for lipid stimulation of C. vulgaris. Furthermore, we propose that the colony formation at high DIC conditions was employed by C. vulgaris to mitigate the stress by minimizing cell exposure to unfavorable environment.