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The emergence of Steiner minimal tree is of fundamental importance, and designing such geometric structure and developing its application have practical effect in material engineering and biomedicine. We used a cutting-edge nanotechnology, electrospinning/netting, to generate a Steiner geometrical poly­(vinylidene fluoride) (PVDF) nanofiber/nanonet filter for removing airborne particulate matter (PM). Manipulation of surface morphologies by precise control of charged situation enabled the creation of two-dimensional nanonets with Steiner geometry. A significant crystalline phase transition of PVDF from α-phase to β-phase was triggered by the dipole orientation and the intermolecular interactions derived from the electrostatic potential analysis. Particularly, the synergy of electrical interaction (ion–dipole and dipole–dipole) and hydrophobic interaction facilitated the formation of Steiner geometric structure during the evolution process of nanonets. The resultant PVDF nanofiber/nanonet air filter exhibited high filtration efficiency of 99.985% and low pressure drop of 66.7 Pa under the airflow velocity of 32 L/min for PM0.26 removal by the safest physical sieving mechanism. Furthermore, such filter possessed robust structure integrity for reusability, comparable optical transmittance, superior thermal stability, and prominent purification capacity for smoke PM2.5. The successful construction of such fascinating Steiner geometrical PVDF nanonets will provide new insights into the design and exploitation of novel filter media for air cleaning and haze treatment.

The effects of dietary probiotics on growth performance, innate immunity and digestive enzymes of silver pomfret were investigated. Compared to the control, diets supplemented with Bacillus subtilis, Lactobacillus plantarum and Clostridium butyricum caused significant improvements of growth performance, including final weight, weight gain, specific growth rate and feed conversion rate. A better growth performance among probiotic treatments was obtained in fish fed B. subtilis. To reveal the effects of these three probiotics on innate immunity of silver pomfret, lysozyme activity, SOD activity and IgM concentrations were examined. Results showed that silver pomfret fed diets containing C. butyricum, L. plantarum and B. subtilis had led to an enhanced innate response, notably higher lysozyme activity, SOD activity and IgM concentrations, as recorded after 30 and 60 days of feeding. In addition, study of different digestive enzymes viz lipase, protease and amylase activities showed significant higher values in fish fed the probiotic diets in comparison to the untreated group. These findings demonstrated that administration of C. butyricum, L. plantarum and B. subtilis can improve growth performance through enhanced immune response and digestive enzyme activity in silver pomfret. Furthermore, the B. subtilis is highly recommended as dietary probiotics in silver pomfret.

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Silver (Ag) nanoparticles were synthesized by a facile route in the presence of oleic acid and n-propylamine. It was shown that the average primary size of the as-synthesized Ag nanoparticles was approximately 10 nm and the surface of as-synthesized Ag nanoparticles was capped with monolayer surfactants with the content of 19.6%. Based on as-synthesized Ag nanoparticles, polyoxymethylene (POM)/Ag nanocomposites were prepared. The influence of Ag nanoparticles on non-isothermal crystallization behavior of POM was investigated by differential scanning calorimetry (DSC). The Jeziorny, Jeziorny-modified Avrami, Ozawa, Liu and Mo, Ziabicki and Kissinger models were applied to analyze the non-isothermal melt crystallization data of POM/Ag nanocomposites. Results of half time (t1/2), crystallization rate parameter (CRP), crystallization rate function (K(T)), kinetic parameter (F(T)), the kinetic crystallizability at unit cooling rate (GZ) and the crystallization activation energy (∆E) were determined. Small amounts of Ag nanoparticles dispersed into POM matrix were shown to act as heterogeneous nuclei, which could enhance the crystallization rate of POM, increase the number of POM spherulites and reduce POM spherulites size. However, the higher loading of Ag nanoparticles were easily aggregated, which restrained POM crystallization to some degree. Furthermore, the POM/Ag nanocomposites showed robust antibacterial activity against Escherichia coli and Staphylococcus aureus.