Misfit layered compounds (MLCs) have generated significant interest in recent years as potential thermoelectric materials. MLC nanotubes could reveal behavior that is entirely different from the bulk material. Recently, new chemical strategies were exploited for the synthesis of nanotubular forms of chalcogenide-based MLCs, which are promising candidates for thermoelectric materials. However, analogous synthesis of oxide-based MLC nanotubes has not been demonstrated until now. Here, we report a chemical strategy for synthesis of cobalt-oxide-based misfit nanotubes. A combination of high-resolution (scanning) transmission electron microscopy (including image simulations), spatially resolved electron energy-loss spectroscopy, electron diffraction, and density functional theory (DFT) calculations is used to discover the formation of a phase within these nanotubes that differs significantly from bulk calcium cobaltite MLCs. Furthermore, DFT calculations show that this phase is semiconducting with a band gap in excess of 1 eV, unlike bulk calcium cobaltite MLCs, which are known to be metallic. Through systematic experiments, we propose a formation mechanism for these nanotubes that could also apply more generally to realizing other oxide-based MLC nanotubes.

Development of new materials for different applications especially as bio-composites has received great attention. This study concentrates on development of a biopolymer based on chitosan (CT) and halloysite nanotubes (HNT) and evaluates the copper removal intake as a potential application of this bio-composite. In this study, CT/HNT beads were prepared by ultrasonic-assisted extrusion-dripping method for the first time. Two sources of HNTs (i.e. Dragonite and Matauri Bay) were added into a chitosan solution (2wt.%) at various loading fractions (25, 50, 75wt.%). The effect of ultrasound as a mixing device was also studied by varying the amplitude at constant frequency of 25%, 50% and 75%. Characteristics and physical properties of the prepared CT/HNT beads were also analyzed by SEM, FTIR, TGA and BET the results show that introducing HNT to chitosan increases the adsorption capacity toward copper ions; however HNT loading fraction above 50wt.% resulted in a decrease in adsorption capacity attributed to limited accessibility of the amino groups. The adsorption capacity of the CT/HNT beads prepared from Dragonite source had a larger adsorption capacity of 14.2mg/g as compared to that of Matauri Bay, 10.55mg/g. It was observed that the adsorption capacity of the beads toward copper ions decreased when the loading fraction of HNT is increased at constant ultrasound amplitude. The result of this study helps to understand the links between the characteristics and adsorption abilities of CT/HNT beads.

The incorporation of nanostructures into nanoelectronic and nanoelectromechanical systems is a long sought-after goal. In the present article, we report the first torsional electromechanical measurements of pure inorganic nanotubes. The WS2 nanotubes exhibited a complex and reproducible electrical response to mechanical deformation. We combined these measurements with density-functional-tight-binding calculations to understand the interplay between mechanical deformation, specifically torsion and tension, and electrical properties of WS2 nanotubes. This yielded the understanding that the electrical response to mechanical deformation may span several orders of magnitude on one hand and detect several modes of mechanical deformation simultaneously on the other. These results demonstrate that inorganic nanotubes could thus be attractive building blocks for nanoelectromechanical systems such as highly sensitive nanometric motion sensors.

Despite controversies on the potential of hematopoietic stem cells (HSCs) to promote tissue repair, we previously showed that HSC transplantation could correct cystinosis, a multisystemic lysosomal storage disease, caused by a defective lysosomal membrane cystine transporter, cystinosin (CTNS gene). Addressing the cellular mechanisms, we here report vesicular cross-correction after HSC differentiation into macrophages. Upon coculture with cystinotic fibroblasts, macrophages produced tunneling nanotubes (TNTs) allowing transfer of cystinosin-bearing lysosomes into Ctns-deficient cells, which exploited the same route to retrogradely transfer cystine-loaded lysosomes to macrophages, providing a bidirectional correction mechanism. TNT formation was enhanced by contact with diseased cells. In vivo, HSCs grafted to cystinotic kidneys also generated nanotubular extensions resembling invadopodia that crossed the dense basement membranes and delivered cystinosin into diseased proximal tubular cells. This is the first report of correction of a genetic lysosomal defect by bidirectional vesicular exchange via TNTs and suggests broader potential for HSC transplantation for other disorders due to defective vesicular proteins.

Implementing the solution chemistry, herein, we report the sealing of both ends of Sb2 S3 semiconductor nanotubes following the diffusion-controlled deposition of the sealing material, AgSbS2 . As a consequence, unique dumbbell-shaped hollow nanocapsules having a binary-ternary epitaxial heterojunction were formed in solution. Whereas these capsule-shaped nanostructures were obtained by the introduction of Ag(0) nanocrystals just after the formation of Sb2 S3 nanotubes, the addition of Ag(0) at the beginning of the process, prior to the formation of nanotubes, changed the growth pattern, and solid nanorods of Sb2 S3 were formed. The details of the chemistry involved in the formation of these nanostructures were investigated and are discussed herein.

Metal-organic frameworks (MOFs) and related material classes are attracting considerable attention for their applications in gas storage/separation as well as catalysis. In contrast, research concerning potential uses in electronic devices (such as sensors) is in its infancy, which might be due to a great challenge in the fabrication of MOFs and semiconductor composites with well-designed structures. In this paper, we proposed a simple self-template strategy to fabricate metal oxide semiconductor@MOF core-shell heterostructures, and successfully obtained freestanding ZnO@ZIF-8 nanorods as well as vertically standing arrays (including nanorod arrays and nanotube arrays). In this synthetic process, ZnO nanorods not only act as the template but also provide Zn(2+) ions for the formation of ZIF-8. In addition, we have demonstrated that solvent composition and reaction temperature are two crucial factors for successfully fabricating well-defined ZnO@ZIF-8 heterostructures. As we expect, the as-prepared ZnO@ZIF-8 nanorod arrays display distinct photoelectrochemical response to hole scavengers with different molecule sizes (e.g., H(2)O(2) and ascorbic acid) owing to the limitation of the aperture of the ZIF-8 shell. Excitingly, such ZnO@ZIF-8 nanorod arrays were successfully applied to the detection of H(2)O(2) in the presence of serous buffer solution. Therefore, it is reasonable to believe that the semiconductor@MOFs heterostructure potentially has promising applications in many electronic devices including sensors.

In nature there are numerous layered compounds, some of which could be curved so as to form fascinating nanoshapes with novel properties. Graphite is at present the main example of a very flexible layered structure, which is able to form cylinders (nanotubes) and cages (fullerenes), but there are others. While fullerenes possess positive curvature due to pentagonal rings of carbon, there are other structures which could include heptagonal or higher membered rings. In fact, fullerenes and nanotubes could display negative curvature, thus forming nanomaterials possessing unexpected electronic and mechanical properties. The effect of curvature in other nano-architectures, such as in boron nitride and metal dichalcogenides, is also discussed in this account. Electron irradiation is a tool able to increase the structural complexity of layered materials. In this context, we describe the coalescence of carbon nanotubes and C(60) molecules. The latter results now open up an alternative approach to producing and manipulating novel nanomaterials in the twenty-first century.