Hydrogen-bond organized 2D metal–organic microsheets:direct ultralong phosphorescence and color-tunable optical waveguides

Ultralong phosphorescent materials have numerous applications across biological imaging, lightemitting devices, X-ray detection and anti-counterfeiting. Triplet-state molecular phosphorescence typically accompanies the singlet-state fluorescence during photoluminescence, and it is still difficult to achieve direct triplet photoemission as ultralong room temperature phosphorescence(RTP). Here, we have designed Zn-IMDC(IMDC, 4,5-imidazoledicarboxylic acid) and Cd-IMDC, two-dimensional(2D)hydrogen-bond organized metal–organic crystalline microsheets that exhibit rarely direct ultralong RTP upon UV excitation, benefiting from the appropriate heavy-atom effect and multiple triplet energy levels. The excitation-dependent and thermally stimulated ultralong phosphorescence endow the metal–organic systems great opportunities for information safety application and temperature-gated afterglow emission. The well-defined 2D microsheets present color-tunable and anisotropic optical waveguides under different excitation and temperature conditions, providing an effective way to obtain intelligent RTP-based photonic systems at the micro-and nano-scales.

2D spinel ZnCo_(2)O_(4) microsheet-coated functional separator for promoted redox kinetics and inhibited polysulfide dissolution

Lithium-sulfur(Li-S)batteries are receiving increasing attention as one of the potential next-generation batteries,owing to their high energy densities and low cost.However,practical Li-S batteries with high energy densities are extremely hindered by the sulfur loss,low Coulombic efficiency,and short cycling life originating from the polysulfide(LiPS)shuttle.In this study,two-dimensional(2D)ZnCo_(2)O_(4) microsheets fabricated by a facile hydrothermal process are employed to modify the separator,for improving the electrochemical performances of Li-S cells.The resulting 2D Zn Co_(2)O_(4)-coated separator features a coating thickness of approximately 10 lm,high ionic conductivity of 1.8 m S/cm,and low mass loading of 0.2 mg/cm^(2).This 2D ZnCo_(2)O_(4)-coated separator effectively inhibits Li PS shuttle by a strong chemical interaction with Li PS as well as promotes the redox kinetics by Zn CO2O4-coated layers,as determined by X-ray photoelectron spectroscopy analysis,self-discharge,time-dependent permeation test,Li symmetric cell test,and Li2S nucleation analyses.Consequently,the Li-S batteries based on the 2D Zn Co_(2)O_(4)-coated separator exhibit a high initial discharge capacity of 1292.2 m Ah/g at 0.1 C.Moreover,they exhibit excellent long cycle stability at 1 and 2 C with capacity retention of 84%and 86%even after800 cycles,corresponding to a capacity fading rate of 0.020%and 0.016%per cycle,respectively.Effectively,these Li-S cells with a high sulfur loading at 5.3 mg/cm^(2) and low electrolyte concentration of 9 l L/mg deliver a high discharge capacity of 4.99 m Ah/cm^(2) after 200 cycles at 0.1 C.

Synthesis,properties,and self-assembly of 2,3-bis(n-octyl)hexaazatriphenylene

A hexaazatriphenylene（HAT） derivative that bears two n-octyl chains was designed and synthesized.Its photophysical and electrochemical properties have been investigated.SEM study revealed that it could self-assemble into well-ordered 1D nanoribbons or 2D microsheets,which depends on the polarity of the solvents used.

Material and regenerative properties of an osteon-mimetic cortical bone-like scaffold

The objective of this work was to fabricate a rigid,resorbable and osteoconductive scaffold by mimicking the hierarchical structure of the cortical bone.Aligned peptide-functionalize nanofiber microsheets were generated with calcium phosphate(CaP)content similar to that of the natural cortical bone.Next,the CaP-rich fibrous microsheets were wrapped around a microneedle to form a laminated microtube mimicking the structure of an osteon.Then,a set of the osteon-mimetic microtubes were assembled around a solid rod and the assembly was annealed to fuse the microtubes and form a shell.Next,an array of circular microholes were drilled on the outer surface of the shell to generate a cortical bone-like scaffold with an interconnected network of Haversian-and Volkmann-like microcanals.The CaP content,porosity and density of the bone-mimetic microsheets were 240 wt%,8%and 1.9 g/ml,respectively,which were close to that of natural cortical bone.The interconnected network of microcanals in the fused microtubes increased permeability of a model protein in the scaffold.The cortical scaffold induced osteogenesis and vasculogenesis in the absence of bone morphogenetic proteins upon seeding with human mesenchymal stem cells and endothelial colony-forming cells.The localized and timed-release of morphogenetic factors significantly increased the extent of osteogenic and vasculogenic differentiation of human mesenchymal stem cells and endothelial colony-forming cells in the cortical scaffold.The cortical bonemimetic nature of the cellular construct provided balanced rigidity,resorption rate,osteoconductivity and nutrient diffusivity to support vascularization and osteogenesis.

Nonlinear Dynamics of Composite Microsheet with Graphene Skins in Non-uniform Thermal Field

The effects of different parameters on the nonlinear dynamic characteristics of macrofiber composite(MFC)microsheet with graphene(GP)skin under non-uniform thermal field are investigated.Firstly,the physical parameters of the MFC–GP structure are calculated by the mixing rule,and the constitutive equations of the structure are set up by employing the Eringen theory.The nonlinear dynamic equations of the microsheet are obtained by using Hamilton’s principle.Then,the heat conduction equations of the microsheet are considered,adopting Green and Naghdi’s generalized thermoelasticity theory.According to the Galerkin weighted residual method,the thermoelasticity coupling equations of the structure are obtained.Meanwhile,the influence of the positive piezoelectric effect of GP and MFC on the vibration response of the structure is also investigated.The nonlinear dynamic governing equations including displacement,coupled thermoelasticity,and electricity field are discretized by the Galerkin method.The effects of non-local parameter,volume fraction of GP,and thermal and electricity coupling coefficients on structural dynamic behavior are discussed in the numerical simulation.