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The incorporation of metal–organic frameworks (MOFs) into polymers would be a very promising strategy for overcoming the disadvantage of MOF brittleness and for extending the application of MOFs in proton-conducting materials. Here, we prepare a series of hybrid membranes composed of MOFs and chitosan (CS, very cheap polymer), and systemically study the effect of the incorporation of pure MIL-101 ([Cr3O(H2O)3(bdc)3], bdc = terephthalic acid), the ligand-modified MIL-101, namely S-MIL-101 ([Cr3O(H2O)3(STA)3]·nH2O, STA = 2-sulfoterephthalic acid), and the non-volatile acid-loaded MIL-101, namely acids@MIL-101 (acids = H2SO4, H3PO4 or CF3SO3H), on the interface compatibility and proton conduction of the hybrid membrane. The experimental results revealed the well compatible interfaces between MOF-based materials and the CS matrix because of the hydrogen bond interaction between them, which greatly improved the proton conductivity, activation energy, thermal and mechanical stability, and swelling property of the hybrid membranes. The functionality of MIL-101 is less than that of S-MIL-101 and acids@MIL-101 because of the presence of more hydrogen-bonding sites, proton hopping sites and proton carriers in the latter two types of materials. All MOF-based materials tested (MIL-101, S-MIL-101, and acids@MIL-101) and their hybrid membranes with CS are characterized using field emission scanning electron microscopy (FE-SEM), TEM, EDS, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and DSC. Fuel cell performances based on these hybrid membranes have been measured. The investigation provides important information for the design of hybrid membranes containing MOFs and polymers. [ABSTRACT FROM AUTHOR]

A series of transition metal coordination complexes, {[Cu(3-Sptta)2] ·1/2H2O} n ( 1), {[Cd(3-Sptta)2] ·1/2H2O} n ( 2), [Zn(3-Sptta)2(H2O)4] ( 3), and [Co(3-Sptta)2(H2O)4] ( 4) were synthesized under solvothermal and solvent evaporation conditions using the newly designed heterocyclic N/NS carboxylate ligand [2-(3-pyridyl)-1,3,4-thiadiazole-5-]-thio-acetate (3-Sptta) as a main building block. Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses and IR spectroscopy. The four complexes exhibit structural diversity: complexes 1 and 2 exhibit similar 2D 'wave-like' double-layer framework with two shares of mutually parallel left-handed and right-handed helical chains, whereas 3 and 4 present mononuclear structures. Moreover, the thermal stabilities of complexes 1- 4 were investigated. The luminescent properties of complexes 2, 3 and the free ligand were also studied. [ABSTRACT FROM AUTHOR]

Hydroxyapatite-silica (HA-SiO 2 ) scaffolds with different SiO 2 content (0, 2, 5 and 10 wt% SiO 2 ) were fabricated by freeze casting. After sintering, the scaffolds maintained the interconnected unidirectional pore channels by removing the frozen ice crystals via sublimation. X-ray diffraction (XRD) analysis indicated that SiO 2 promoted the decomposition of HA to tricalcium phosphate (TCP), comprised of α-TCP and β-TCP, which became more apparent with the increase of SiO 2 content. The microstructure observation of scanning electron microscope (SEM) showed that the scaffolds surface feature had great changes in terms of grain size and grain boundary with the addition of SiO 2 . Moreover, the addition of SiO 2 could increase the porosity and pore size of the scaffolds, even allowing it to reach a maximum as the SiO 2 content increased to 5 wt%. Compression tests investigated the variation in the compressive strength of the scaffolds with the increase in the SiO 2 content, which showed first decreasing and then increasing behavior. In vitro evaluation results in simulated body fluid (1.5×SBF) revealed that the introduction of SiO 2 enhanced the growth rate of bone-like layer, especially the scaffold with 5 wt% SiO 2 , which exhibited faster growth rate of bone-like layer than the other scaffolds. The XRD and fourier transformed infrared spectroscopy (FT-IR) characterization confirmed that the bone-like layer formed on the scaffold surface was a carbonate-containing hydroxyapatite bone-like layer. [ABSTRACT FROM AUTHOR]

The transfer matrix method has been widely used to calculate the scattering of electromagnetic waves. In this paper, we develop the conventional transfer matrix method to analyze the problem of second harmonic generation in a one-dimensional multilayer nonlinear optical structure. In the designed nonlinear photonic crystal structure, the linear and nonlinear optical parameters are both periodically modulated. We have taken into account the multiple reflection and interference effects of both the linear and nonlinear optical waves during the construction of the transfer matrix for each composite layer. Application of this method to multilayer nonlinear photonic crystal structures with different refractive indices indicates that the proposed method is an exact approach and can simulate the generation of the second harmonic field precisely. In an optimum structure, the second harmonic generation efficiency can be several orders of magnitude larger than in a conventional quasi-phase-matched nonlinear structure with the same sample length. The reason is that, due to the presence of photonic band gap edges, the density of states of the electromagnetic fields is large, the group velocity is small, and the local field is enhanced. All three factors contribute to significant enhancement of the nonlinear optical interactions.