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A novel type of hybrid graphene oxide/laponite (GO/L) layered membrane is developed with stable two-dimensional (2D) nanochannels for efficient separations in aqueous environments. The electrostati...

The electronic and optical properties of graphane, silicane and MoS2 bilayers, as well as the graphane/MoS2 and silicane/MoS2 hetero-bilayers, are calculated by the first-principles method. The interlayer interactions of all the bilayer systems are shown to be mainly van der Waals. Both the graphane/MoS2 and silicane/MoS2 hetero-bilayers belong to the type-II heterostructure, which can be utilized in photo-voltaic devices due to the efficient spatial separation of electrons and holes. For optical properties, the distinctions for the imaginary parts of the dielectric function e 2 ( ω ) between the monolayer and bilayer systems for both the graphane and silicane are more evident in electric vector E||z. However, the differences between e 2 ( ω ) of the monolayer and bilayer MoS2 materials are more significant in E||x. Broader light absorption ranges of the hetero-bilayers are reached, which can also improve the charge separation of the electron-hole pairs.

Organic compounds are widely used in both industry and daily life, and composite bilayer films with organic compound-triggered bending properties are promising for applications of transducers, soft robotics, and so on. Here, a universal and straightforward strategy to generate composite bilayer films with organic compound-triggered bending properties is demonstrated. The composite bilayer films with organic compound-triggered bending properties are designed with bilayer structures, in which one layer is a porous polymeric membrane with appropriate solubility parameter that matches the value of organic solvents in order to produce prominent affinity to the solvent molecules, and the other layer is reduced graphene oxide membrane stacked on the porous polymeric membrane as an inert layer for restraining the swelling of the polymeric membrane on one side. Guided by matching the solubility parameters between solvent and polymer, a significant bending curvature of 27.3 cm−1 is obtained in acetone vapor. The results in this study will provide valuable guidance for designing and developing functional composite materials with significant organic compound-triggered bending properties.

The hydrophilicity of smart additives thermodynamically and kinetically affects the degree and velocity of the phase separation of casting solution, together with their distribution on the membranes, which ultimately affects the microstructure and properties of smart membrane. However, the reasonable design and successful preparation of additives with different hydrophilicity, as well as the observation of their migration during membrane formation process and final distribution on/in the membranes remain challenges. The three kinds of thermo-responsive submicrogels with similar chemical structures and different hydrophilicity were successfully fabricated and blended into poly(ether sulfone) (PES) as functional gates to prepare smart membranes via vapor-induced phase separation (VIPS). The hydrophilicity of poly(N-n-propylacrylamide) (PNN), poly(N-isopropylacrylamide) (PNI) and poly(N-isopropylmethacrylamide) (PNM) submicrogels were quantitively measured; their diameters and thermo-responsive factors in water were similar. Moreover, the effects of the hydrophilicity of submicrogels on the microstructures and properties of as-prepared smart membranes were systematically investigated and the results were elucidated in principle. The results showed the velocity of phase separation of casting solution, the pore size of membranes and the number of submicrogels distributed on membranes increased whereas the stability of submicrogels on membranes decreased with the enhancement of hydrophilicity of submicrogels. The membrane blended with PNI submicrogels with optimal hydrophilicity, which was provided with both a large number of submicrogels stably distributed on the membrane pores as smart gates and appropriate pore size, exhibited excellent permeability and thermo-responsiveness. The maximum water flux through this membrane was 26271 kg m−2 h−1 bar−1, and its maximum normalized thermo-responsive coefficient N value reached to 28.7. The results will provide valuable guidance for understanding the mechanism of phase separation and further development of smart membranes with satisfactory performances.

The preparation of microparticles with non-spherical shapes has attracted increasing interest because the special physical properties of non-spherical microparticles can increase their performance in a wide variety of industrial applications and clinical pathologies. Here a simple and flexible approach is developed to fabricate monodisperse bullet-shaped microparticles with controlled structures from microfluidic droplet templates, which are deformed by both shear stress from outer fluid and spatial confinement from microchannel. The deformation of droplet templates can be simply controlled by varying the flow rate of outer fluid and the inner diameter of collection tube. By multiplying the microfluidic device, bullet-shaped microcapsules with different internal structures can be easily fabricated from deformed double emulsion droplets. The results of flow characteristics show that, the bullet-shaped microparticles have a higher velocity than the spherical microparticles with the same volume if they flow in the microchannel with smaller diameter than the length of the bullet-shaped microparticles; whereas their flowing velocity is slightly lower than that of spherical microparticles in the microchannel if the channel diameter is larger than the length of bullet-shaped microparticles. In microchannels of a model device, bullet-shaped microparticles show better embolization performance than spherical ones. The bullet-shaped microparticles and microcapsules are promising as materials candidates in the fields of embolization therapy, substance transfer and drug release systems. The proposed strategy in this study provides a facile route for fabricating bullet-shaped microparticles with controlled structures and presents intriguing possibilities for growing researches including non-spherical microparticles and micromachine systems.

At present, selective and efficient removal of cesium ions (Cs+) from nuclear waste is of significant importance but still challenging. In this study, an easy-to-get and low-cost hydrogel adsorbent has been developed for effective adsorption and removal of Cs+ from aqueous environment. The novel Cs+-recognizable poly(acrylic acid-co-benzo-18-crown-6-acrylamide) (poly(AAc-co-B18C6Am)) hydrogel is specifically designed with a synergistic effect, in which the AAc units are designed to attract Cs+ via electrostatic attraction and the B18C6Am units are designed to capture the attracted Cs+ by forming stable 2:1 "sandwich" complexes. The poly(AAc-co-B18C6Am) hydrogels are simply synthesized by thermally initiated free-radical copolymerization and display excellent Cs+ adsorption from commonly coexisting metal ions. Important parameters affecting the adsorption are investigated comprehensively, and the adsorption kinetics and adsorption isotherms are also discussed systematically. The poly(AAc-co-B18C6Am) hydrogels exhibit rapid Cs+ adsorption within 30min and the adsorption process is governed by the pseudo-second order model. Adsorption isotherm results demonstrate that the equilibrium data are well fitted by the Langmuir isotherm model, indicating that the Cs+ adsorption is probably a monolayer adsorption process. Such Cs+-recognizable hydrogel materials based on the host-guest complexation are promising as efficient and feasible candidates for adsorption and removal of radioactive Cs+ from nuclear contaminants.

Microhelices with unique three-dimensional (3D) helical structures have attracted great attention due to applications in various fields, especially magnetic microhelices can be applied as microrobots for removal of clogging substance in microchannels, cargo transport, cell manipulation, and so on. Here, a facile and flexible strategy is developed to controllably fabricate microhelices with droplet microfluidics. On-flow fabrication of microhelices is simply achieved by generating monodisperse droplets first, transforming the spherical droplets into helical templates subsequently due to the liquid rope coiling effect, followed by polymerizing monomers in the templates via on-line UV irradiation and then degrading the shells of helical fibers. Benefitting from the flexible controllability of microfluidics, the morphologies of microhelices can be precisely controlled by adjusting the flow rates of fluids and the structures of microfluidic devices. Functional microhelices can be easily prepared by introducing functional components or elements into inner fluids. By introducing magnetic nanoparticles into inner fluids, magnetic microhelices are easily fabricated as microrobots that featured with magnetic-field-driven corkscrew-like motion for efficient cargo transport and removal of clogging substance in microchannels. This novel microfabrication method allows a precise morphological control and easy functionalization of microhelices, providing a flexible and versatile strategy for fabricating designer functional microhelices for diverse applications.

Graphene oxide (GO) membranes become emerging efficient filters for molecular or ionic separation due to their well-defined two-dimensional nanochannels formed by closely spaced GO sheets and tunable physicochemical properties. The stability of GO membranes in aqueous solutions is a prerequisite for their applications. Here we show a novel and easy strategy for fabricating GO membranes with strong stability in aqueous solutions and controllable lamellar spacing by simply doping with partially reduced graphene oxide (prGO) sheets. With our prGO-doping strategy, the interlayer stabilizing force in GO membranes is enhanced due to the weakened repulsive hydration and enhanced π-π attraction between GO sheets; as a result, the fabricated GO membranes are featured with controllable lamellar spacing and extraordinary stability in water or even strong acid and base solutions as well as strong mechanical properties, which will expand the application scope of GO membranes and provide ever better performances in their applications with aqueous solution environments.

While a rechargeable battery based on Na/CFx has been proposed, its reversible mechanism has remained unclear. Here, a new fluorinated carbon fiber material with the formula CF0.75 is used as a cathode material for rechargeable sodium batteries, delivering an initial discharge capacity of 705 mA·h g–1 with a high discharge plateau of 2.75 V and a reversible high discharge capacity of 350 mA·h g–1 at 20 mA g–1. The first discharge plateau of 2.75 V is the highest value reported in this family of materials so far, even slightly higher than that of commercial fluorinated graphite tested in a lithium battery (2.7 V). The origins of the observed high voltage of the material are explored by a combination of theoretical calculations and galvanostatic intermittent titration technique data and determined to be related to the disordered structure of the carbon fiber. Soft X-ray absorption spectroscopy and 19F magic angle spinning nuclear magnetic resonance characterization results disclose a full view of the conver...

Improving both nitrogen utilization and peanut kernel quality (after removing peanuts shell) through water management is a growing concern for farmers. To explore the role of supplemental irrigation in nitrogen transformation between ‘source’ and ‘sink’, a split-plot experiment was conducted to evaluate the effects of water (rain-fed irrigation as IRI; supplemental irrigation as ISI) and nitrogen (0 kg∙ha―1 as N0; 40 kg∙ha―1 as N1; 60 kg∙ha―1 as N2 and 80 kg∙ha―1 as N3) coupling on soil nitrate nitrogen content, nitrogen accumulation and kernel quality of peanuts. We determined the dry matter weight per plant at peanut maturity as 64.66—74.92 g and 71.65—92.81 g for IRIN0 and ISIN3, respectively. ISIN2 significantly increased nitrogen accumulation, yield and water productivity. Furthermore, the ISI treatment prolonged the nitrogen uptake accumulation time of leaves, thus enhancing the nitrogen transfer from the leaves to the pods. Thus, the ISI treatment significantly increased the nitrogen harvest index by 2.13% and the nitrogen agronomic efficiency by 78.57% compared to the IRI treatment. In addition, the essential amino acid content in the fruits was within the range of 5.57—6.08%, while the content of non-essential amino acids was 16.43 to 17.46%. N1 was able to significantly increase the content of non-essential and essential amino acids, while ISI reduced the content of essential amino acids. Post-harvest soil nitrate nitrogen was principally distributed in the 0—40 cm soil layer, accounting for 77.75% of the 0—60 cm soil layer. Although the supplemental irrigation is associated with an increased risk of the nitrogen moving deeper into the soil, it greatly enhances nitrogen transfer from leaves to the pods at nitrogen application rates of 40—60 kg ha―1.

Facilitated transport of K+ ions through membranes is of great significance in both science and technology for the efficient and selective separation of potassium ions. Here, a novel membrane with ion-recognizable copolymers in graphene-based nanochannels is developed for facilitated transport of potassium ions. The poly(N-isopropylacrylamide-co-benzo-15-crown-5-acrylamide) (PNB) copolymers are fixed in the lamellate spacings between the partially reduced graphene oxide (prGO) nanosheets. The K+ permeability of the fabricated prGO-PNB membrane remarkably increases at around the lower critical solution temperature (LCST) of the PNB copolymer, because of the dynamic complexation between B15C5 units and K+ ions at around the LCST. The selectivity of K+/Na+ increases with increasing the content of PNB copolymers in the membrane. The proposed membrane shows good stability in water and K+ separation performance. Due to the uniform channels and facilitated transport mechanism of the prGO-PNB membrane, the comprehensive performance of selectivity and permeability of the K+ ions is better than that of previously reported polymer-based nanofiltration membranes, polymer-based facilitated transport membranes and graphene-based membranes. The proposed strategy of this prGO-PNB membrane that combining graphene-based sheets as “skeleton” and substance-recognizable copolymers as “facilitators” is also applicable to fabricate membranes for facilitated transport of other ions or molecules.

Spasers can serve as a pure surface plasmon generator with a coupling efficiency to plasmonic modes approaching 100%., Spasers are a new class of laser devices with cavity sizes free from optical diffraction limit. They are an emergent tool for various applications, including biochemical sensing, superresolution imaging, and on-chip optical communication. According to its original definition, a spaser is a coherent surface plasmon amplifier that does not necessarily generate a radiative photon output. However, to date, spasers have only been studied with scattered photons, and their intrinsic surface plasmon emission is a “dark” emission that is yet to be revealed because of its evanescent nature. We directly image the surface plasmon emission of spasers in spatial, momentum, and frequency spaces simultaneously. We demonstrate a nanowire spaser with a coupling efficiency to plasmonic modes of 74%. This coupling efficiency can approach 100% in theory when the diameter of the nanowire becomes smaller than 50 nm. Our results provide clear evidence of the surface plasmon amplifier nature of spasers and will pave the way for their various applications.