A novel positively charged nanofiltration membrane has been prepared by the reaction of carboxylic acids on the surface of a polyamide thin film composite with poly­(amidoamine) dendrimer in the presence of 2-chloro-1-methylpyridinium iodide as an activating agent. The membrane was prepared with excellent grafting efficiency and showed a high isoelectric point of pH 9.9. Because of the high density of free protonated amino groups, the membrane showed excellent rejections toward various toxic elements including Cu2+, Ni2+ and Pb2+. The rejection order also followed the size of the ions in terms of their hydrated radius. Furthermore, the membrane obtained by the surface grafting method exhibited outstanding alkaline stability compared to the membrane prepared by the conventional coating process. These results clearly indicate that grafting the poly­(amidoamine) dendrimer onto the surface of the polyamide thin film composite membrane is a promising approach to improve the rejection of toxic containments.

Novel high-flux thin film composite (TFC) nanofiltration (NF) membranes were fabricated via interfacial polymerization (IP) on a polysulfone substrate using 2,2'-benzidinedisulfonic acid (BDSA) as the amine monomer in aqueous solution. The intrinsic resistance of the resulting membranes (Rm) was found to be as low as 2.37 x 10 13 m-1 , indicating a considerably low tolerance against hydraulic resistance. The optimized membrane TFC-1.0 showed excellent rejection towards different inorganic electrolyte solutions in the following order: Na2SO4 > NaCl > MgCl2 > CuSO4 > MgSO4, indicating the negatively charged nature of the membrane. Surface properties were evaluated by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and contact angle measurements, and the results indicated a smooth and moderately hydrophobic surface. Using dissipative particle dynamics (DPD), the coarse-grained model molecules at the mesoscale level were used to establish an oil-water interface model with regard to the current IP process. The orientation of BDSA monomers was studied and it was found that most of the sulfonic acid groups were facing towards the aqueous solution, while the outer faces were covered by the nanoaggregates of the rigid polymer backbones. This finding is

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A polarimetric study of random laser (RL) emitted from dye-doped nematic liquid crystals (NLCs) is presented. We observed linearly polarized light, the orientation of which is in proximity to the bisection between the polarization direction at the maximal scattering in NLCs and the nematic director. Any arbitrary linear polarization of RLs can be obtained by rotating the NLC sample. The efficiency and output uniformity over the complete direction angle of 2π can be optimized by choosing a proper pump polarization.

A new sulfonated aromatic diamine monomer, potassium 2,5-bis­(4-amino­phenoxy)­benzene­sulfonate (BAPBS), was synthesized and employed to develop a series of thin-film composite (TFC) nanofiltration membranes with trimesoyl chloride (TMC) on a polysulfone (PSF) substrate by an interfacial polymerization (IP) technique. The TFC membrane performed a high water flux of 72.8 L m–2 h–1 and a rejection of 92.5% to Na2SO4 at 0.6 MPa. The surface hydrophilicity of the as-prepared sulfonated polyamide (SPA) membrane was greatly improved by the introduction of sulfonic acid groups, as confirmed by the much reduced contact angle value. Moreover, the membrane also exhibited good antifouling ability with water flux recovery ratio (FRR) and total flux decline ratio (DRt) of about 88% and 18%, respectively. Molecular dynamics simulation was investigated to obtain an in-depth understanding of the transport behaviors of water molecules through the SPA polymers. The results clearly illustrated that the diffusion coefficient of water molecules in the sulfonated membrane matrix was about 21% greater than that in the nonsulfonated one. Overall, the combined results suggest that this type of SPA nanofiltration membrane is a promising candidate for water softening and purification applications.

Boron nitride (BN) nanosheets are prepared using an ultrasonic decomposition method and demonstrated nonlinear absorption characteristics that saturated at near 2 µm. A passively mode‐locked Tm:YAP laser was perfectly implemented with the BN nanosheets as a saturable absorber (SA). In the passively Q‐switched mode‐locked mode, an average output power of 880 mW with a pulse duration of 478.83 ps was achieved using an incident pump power of 26.46 W, corresponding to an optical–optical conversion efficiency of 3.33%. A pulse peak power of 19.03 W was acquired at 1937.0 nm from the mode‐locked Tm:YAP laser.