In this article, ZnO microtube was prepared using mixed powder of Zn, ZnO, and carbon as source via chemical vapor deposition method. The growth process was discussed in detail, and the high Zn vapor pressure and high growth temperature were considered as two crucial factors determining the formation of tubular structure. A two-step growth model was proposed, namely initial deficient-oxidation and followed by second-volatilization. Four another experiments were further conducted to analyze the growth behavior of reagent species under different Zn vapor pressure and growth temperature, respectively. These experimental results indicated that the formation of Zn-rich structure under enough high Zn vapor pressure and second-volatilization of these abundant interstitial Zn under high growth temperature were important to form tubular structure. Our experimental method provided a feasible route to prepare other hollow structures, such as oxide, sulfide, etc. Furthermore, these synthesized ZnO microtube might have potential application as functional blocks in nanodevices.

Data from the literature and our laboratory have been reviewed regarding the maximum homologous temperatures that can be attained by the addition of solute elements that may induce thermodynamic or kinetic (Zener pinning) stabilization of a nanocrystalline grain size (<100 nm) to elevated temperatures. The results of this review suggest that kinetic stabilization by Zener pinning by nanoscale second phases may be the more effective strategy for keeping a nanoscale grain microstructure at the highest homologous temperatures. More research is necessary to confirm this suggestion and to determine the influence of nanoscale grain boundary second phases on the mechanical behavior of the nanocrystalline matrix.

We describe the synthesis and fabrication of a graphene oxide (GO) and single-walled carbon nanotube (SWCNT) composite ink (GO–SWCNT ink) for electrochemically stable supercapacitors. Atomic force microscopy and scanning electron microscopy studies demonstrate that the obtained GO flakes are single layer with size distribution from 100 nm to 20 μm. SWCNTs are dispersed using a GO aqueous solution (2 mg/mL) with sonication support to achieve a SWCNT concentration of 12 mg/mL, the highest reported value so far without surfactant assistance. Raman spectroscopy studies indicate that the full-width at half-maximum of the G band increases with the mixing of SWCNT and GO indicating that electronic structure changes via π–π interactions of GO sheets and SWCNTs. Paper-based electrodes of supercapacitor were conveniently fabricated with GO–SWCNT composite ink via a dip casting method. By using different concentrations of SWCNT in the ink, the paper electrodes provide different capacitance values. The highest value of specific capacitance reaches 295 F/g at a current density of 0.5 A/g with a GO/SWCNT weight ratio of 1:5. The cycling stability for the GO–SWCNT paper electrode supercapacitors indicates capacitance retention of 85% over 60,000 cycles.

Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis and surface modification strategy that protects Si NPs and preserves red photoluminescence (PL) in water for more than 6 mo. The Si NPs were synthesized via high temperature reaction, liberated from an oxide matrix, and functionalized via hydrosilylation to yield hydrophobic particles. The hydrophobic Si NPs were phase transferred to water using the surfactant cetyltrimethylammonium bromide (CTAB) with retention of red PL. CTAB apparently serves a double role in providing stable, aqueous, red-emitting Si NPs by (i) forming a hydrophobic barrier between the Si NPs and water and (ii) providing aqueous colloidal stability via the polar head group. We demonstrate preservation of the aqueous red emission of these Si NPs in biological media and examine the effects of pH on emission color.

Due to its excellent physical properties, graphene acting as reinforcing fillers has attracted intense interests. To achieve a controlled distribution, the formation of a conductive network composed of graphene sheets within polymer matrix is of critical importance. In this work, polystyrene (PS) microspheres wrapped by graphene oxide (GO) sheets were prepared via layer-by-layer (LBL) assembly of oppositely charged GO sheets onto PS microspheres. The deposited GO was then reduced, and the composite films with a graphene conductive network were prepared by hot pressing. The morphology of graphene conductive network was studied, and the thermal and electrical properties of the composite films were measured. The as-prepared composites showed an improved thermal stability as well as electrical conductivity with a percolation threshold as low as 0.2 vol%. The combination of latex technology and LBL self-assembly method thus demonstrated an efficient and facile approach to fabricate electrically conductive graphene/polymer composites.

In this work, we have studied the superhydrophobicity and buoyancy of two types of nanostructured surfaces: the cabbage leaf and a vertically aligned carbon nanotubes (VACNTs) carpet. The wettability of these surfaces were characterized by contact angle, tilting angle, sliding volume and sliding speed measurements. The results were correlated to the related surface topologies, which were investigated by scanning electron microscopy. Buoyancy of different surfaces has been investigated through measurements of the forces acting on the surface. Finally, we demonstrate that cabbage leaves and VACNT carpets have some common features with the water strider’s leg, better understanding the mechanisms of buoyancy related to the structural shape and size of natural or artificial nanostructures.

Patterned porous films prepared by the breath figure method have received considerable interests because of the potential applications. This paper reports a top–down method to fabricate functional patterned films. Cross-linked polystyrene microspheres were synthesized by a two-stage dispersion polymerization using divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDMA) as cross-linkers, which provide free vinyl groups on the microspheres surface. The amounts of residual vinyl groups were determined by potentiometric titration. Glucose was then bound to the microspheres via thiol–ene reaction, which was confirmed by x-ray photoelectron spectroscopy and water contact angle measurements. Results indicate that vinyl groups of EGDMA show relatively higher reactivity than that of DVB. Microspheres with glucose were assembled into the pores of honeycomb films prepared by the breath figure method, forming functional arrays for recognizing a lectin, Con A. This top–down method is useful in preparing patterned films with various functional moieties, which may act as a platform, such as, for investigating carbohydrate–lectin interactions and for sensing.

The paper established a model to investigate the interaction between the special rotational deformation and a semielliptical blunt crack in deformed nanocrystalline materials. By using the complex variable method, the effect of a disclination quadrupole produced by the special rotational deformation on the emission of lattice dislocation from a semielliptical blunt crack tip was explored theoretically. The complex form expression of the dislocation force was derived, and the critical stress intensity factors (SIFs) for the first edge dislocation emission were calculated. Then, the influence of the disclination strength, the disclination location and orientation, the special rotational deformation orientation, the grain size, and the curvature radius of blunt crack tip on the critical SIFs were discussed in detail, and a comparison with the sharp crack behavior was presented. The results show that the special rotational deformation and the curvature radius of blunt crack have great effects on the lattice dislocation emission form blunt crack tip. Some influence laws are also different with those of the edge dislocation emission from a sharp crack tip.

We present results of a molecular dynamics study using adaptive intermolecular reactive empirical bond order interatomic potential to analyze thermal transport in three-dimensional pillared single-walled carbon nanotube (SWCNT)–graphene superstructures comprised of unit cells with graphene floors and SWCNT pillars. The results indicate that in-plane as well as out-of-plane thermal conductivity in these superstructures can be tuned by varying the interpillar distance and/or the pillar height. The simulations also provide information on thermal interfacial resistance at the graphene–SWCNT junctions in both the in-plane and out-of-plane directions. Among the superstructures analyzed, the highest effective (based on the unit cell cross-sectional area) in-plane thermal conductivity was 40 W/(m K) with an out-of-plane thermal conductivity of 1.0 W/(m K) for unit cells with an interpillar distance Dx = 3.3 nm and pillar height Dz = 1.2 nm, while the highest out-of-plane thermal conductivity was 6.8 W/(m K) with an in-plane thermal conductivity of 6.4 W/(m K) with Dx = 2.1 nm and Dz= 4.2 nm.

To explore the relationships between microstructure and growth direction, metallic A-type antiferromagnetic and anisotropic magnetoresistant Nd0.45Sr0.55MnO3 (NSMO) thin films were grown on SrTiO3(110) by pulsed laser deposition method and characterized by (scanning) transmission electron microscopy. The interface between NSMO and SrTiO3 (110) is flat and sharp. The NSMO thin films exhibit a two-layered structure: a continuous perovskite layer epitaxially grown on the substrate followed by an epitaxially grown columnar nanostructure [Fig. 1(a)]. High-density stacking faults were found in the nanostructured layer with an in-plane translational displacement of 1/2a<111>, accompanied by 1/2a[001] partial dislocations or (110) antiphase boundaries (APBs). These stacking faults terminate either at pores or in the grain matrix to eliminate (1$\bar 1$0) APBs. The formation mechanisms of the nanostructured NSMO films and the relevant stacking faults are discussed from the viewpoint of both film growth and specific substrate direction.