The collapse and stability of carbon nanotubes (CNTs) functionalized by corrosion inhibitor molecules on the Fe (1 0 0) surface were studied using molecular mechanics and molecular dynamics simulations. The results show that the pristine CNTs can approach and even collapse spontaneously onto the Fe surface due to the van der Waals force between them when the CNT diameter exceeds a certain threshold. To avoid collapse of the CNTs, they are randomly side-functionalized by three corrosion inhibitors. When the modification coverage exceeds 4.33%, these modified CNTs can basically maintain their cylindrical structures on the Fe surface. The CNTs, randomly modified by appropriate inhibitor groups, can maintain their cylindrical structure stably, giving them the potential to be used as nanocontainers for maintaining or transporting molecules, etc. Moreover, our findings have great practical significance, and CNTs modified by the organic inhibitor groups can be considered to be environmentally-friendly corrosion inhibitors, which can provide some guidance towards understanding corrosion resistance of CNT-inhibitor composites.
Manipulating graphene to controllably design three-dimensional (3D) architectures of graphene would be an intriguing approach to prevent two-dimensional (2D) aggregation. Herein, 2D graphene nanoribbons (GNRs) have been controllably folded into 3D graphene nanocages (GNCs) by introducing platinum nanoclusters (Pt NCs) forming composite nanoclusters. The van der Waals interaction between the GNR and Pt NC plays a critical role in the self-folding process. The nanocluster shape influences the outer cage of the composite nanocluster largely, in which the spherical Pt NCs could initiate the formation of tetrahedron GNC or graphene nanoscroll, while the other shaped Pt NCs conduct the GNC folding contour the nanocluster geometry. In addition, the sizes of Pt NCs and GNRs also significantly influenced the self-folding process. The controlled folding of 2D GNRs into 3D architectures opens up new avenues for the exploration and fabrication of unique graphene-based nanomaterials and nanodevices toward energy and drug delivery applications.
We studied the radial collapse of single-walled carbon nanotubes (CNTs) on the Cu2O surface using molecular dynamic simulations. When the diameter of CNTs exceeds a threshold, the CNTs approach the Cu2O surface and collapse spontaneously by the van der Waals force between the CNTs and the Cu2O surface. Because the collapsed CNTs are much more like graphenes, this collapse process of CNTs seems the reverse process of folding graphene nanoribbons to form CNTs. The collapsed CNTs exhibit as linked graphene ribbons and have the largest area to contact with the Cu2O surface, which greatly enhances adhesion between the CNTs and the Cu2O surface and keeps the system much more stable. Due to the hydrophobic properties of CNTs, the collapsed CNTs on the oxide surface can isolate the metal oxide from water solution, which suggests that the collapsed CNTs on the metal oxide surfaces have potential applications in corrosion protection and scale inhibition fields.
Abstract Flightless I (Fli I) is an evolutionarily conserved member of the gelsolin family, containing actin-binding and severing activity in vitro. The physiological function of Fli I during animal development remains largely undefined. In this study, we reveal a key role of the Caenorhabditis elegans Fli I homolog, fli-1, in specifying asymmetric cell division and in establishing anterior–posterior polarity in the zygote. The fli-1 gene also regulates the cytokinesis of somatic cells and the development of germline and interacts with the phosphoinositol-signaling pathway in the regulation of ovulation. The fli-1 reporter gene shows that the localization of FLI-1 coincides with actin-rich regions and that the actin cytoskeleton is impaired in many tissues in the fli-1 mutants. Furthermore, the function of fli-1 in C. elegans can be functionally substituted by the Drosophila Fli I. Our studies demonstrate that fli-1 plays an important role in regulating the actin-dependent events during C. elegans development.
Self-assembled structures from aromatic dipeptides have attracted a lot of attention. It is highly desirable to produce dipeptide assemblies which undergo structural transitions in response to external stimuli. In this paper, solid nanospheres were successful produced from the self-assembly of chemically modified diphenylalanine in hexafluoroisopropanol (HFIP), a highly polar solvent. Interestingly, after treatment with water, the nanospheres were transformed into nanofibers. The intermediate transition state of nanospheres embedded along the nanofibers was captured by atomic force microscopy (AFM) imaging. In addition, AFM-based nanomechanical measurement revealed the increased stiffness after the transition, suggesting enhanced molecular packing due to favoured intermolecular interactions in water. This study presents a new method to fabricate novel dipeptide structures and provides new information for understanding the mechanism of dipeptide self-assembly driving by intermolecular interactions.
The rational design and facile synthesis of highly activated and stable electrocatalysts toward the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR) are extremely demanded but remain challenging. Herein, a highly efficient bifunctional electrocatalyst composed of rhodium (Rh), cobalt (Co), and iron (Fe) alloy nanoparticles embedded in nitrogen-doped graphene (RhFeCo@NG) is prepared through sequential annealing and the substitution reaction. The as-prepared Rh2.6Fe3Co2.6@NG electrocatalyst achieves an overpotential as low as 25 mV for reaching a current density of 10 mA cm–2 and an ultralow Tafel slope of 29.8 mV dec–1 in 1 M KOH solution for HER, which is even superior to the state-of-the-art platinum (Pt) catalyst. With regard to ORR, for the Rh2.6Fe3Co2.6@NG electrocatalyst, a half-wave potential (E1/2) of 0.82 V versus reversible hydrogen electrode and excellent long-term stability are achieved. The experimental results illustrate that alloying the Rh atom with the FeCo nanoalloy is mainly responsible for the excellent HER and ORR performances. This study not only provides a robust and promising electrocatalyst for HER and ORR in alkaline media but also sheds light on the devising of efficient and multifunctional catalysts.
Electrospun composite nanofibrous scaffolds have been regarded as a potential carrier for local drug delivery to prevent tumor recurrence. Herein, a model drug (paclitaxel) was creatively loaded into lignin nanoparticles (PLNPs) and then encapsulated into the polymer of poly (vinyl alcohol)/polyvinyl pyrrolidone which has been fabricated into a composite nanofibrous membrane (PVA/PVP-PLNPs) for use as a drug carrier using the electrospinning technique. The fabricated PVA/PVP-PLNPs membranes exhibited good particle distribution, mechanical properties, thermal stability and biocompatibility. In vitro experiments showed that combining lignin nanoparticles by electrospinning not only improved the drug release profile, but also enhanced the hydrophilicity of nanofibrous membranes which was beneficial to cell adhesion and proliferation. Cellular experiments demonstrated that PVA/PVP-2%PLNPs membrane showed good cell inhibition ability, and the cell survival rate was only 21% at day 7. It indicates that the as-prepared PVA/PVP-PLNPs composite nanofibers are promising candidates for local anticancer therapy.
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