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The synthesis of bimetallic nanostructures using galvanic replacement displays a versatile route toward efficient catalysts for fuel cell reactions. We show that electrolessly plated Ag nanotubes (NTs) are a unique template for the synthesis of double-walled Ag–Pt NTs. After replacement reaction, different dealloying protocols are applied to adjust the residual Ag content. The structures were thoroughly characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, providing evidence of a hollow tube structure composed of Ag–Pt alloy. Experiments under harsh conditions reveal, that a significant amount of Ag remain in the NTs, which strongly affects the methanol oxidation performance. With optimized Ag–Pt ratio, the specific activity of Pt/C catalysts can be outperformed. From the obtained results, we emphasize that each effort using galvanic replacement should be accompanied by detailed compositional analysis.

Fe₃O₄ nanoparticles have been widely used as drug carriers, but their toxicity is rarely reported. Herein, we compared the toxicity of novel Fe₃O₄ nanorings, nanotubes and conventional Fe₃O₄ nanospheres. The structure, morphology and magnetic properties of Fe₃O₄ nanoparticles were characterized via X-ray diffraction, scanning electron microscope and vibrating sample magnetometer. Scanning electron microscope images revealed that the morphologies of Fe₃O₄ particles were annular, tubular or spherical. The magnetic property measurements demonstrated that saturation magnetization values of nanorings, nanotubes and nanospheres were 85.3, 90.1 and 74.8emu/g, respectively. In addition, the cytotoxic effects on the 264.7 mouse macrophages cells of Fe₃O₄ nanorings, nanotubes and nanospheres were determined by cck-8 test and TUNEL staining assay. Cell viability was slightly decreased on spherical Fe₃O₄ nanoparticles compared to annular and tubular Fe₃O₄ nanoparticles.

The electrode materials for highly efficient glucose oxidation reaction (GOR) are vital for nonenzymatic glucose sensors (NEGS) and direct glucose fuel cells. The Pd-decorated NiCo₂O₄ nanotubes (Pd/NiCo₂O₄ NTs) were prepared through the template-free process. Pd/NiCo₂O₄ NTs presented highly improved electrocatalytic activity for glucose oxidation. When applied to glucose detection, Pd/NiCo₂O₄ NTs displayed superior sensing performance with a wide detection range of 5 $\mu$M–9 mM. The sensitivity and detection limit are 214.2 $\mu \mathrm{\text{A}}\cdot {\mathrm{\text{mM}}}^{-1}\cdot {\mathrm{\text{cm}}}^{-2}$ and 1.6 $\mu$M, respectively. Moreover, the Pd/NiCo₂O₄ NTs sensors also demonstrated excellent selectivity and feasibility for glucose detection for serum sample analysis.

Scheelite-related monoclinic BiVO₄ is one of the most promising metal oxide photoanode materials. It is therefore highly desirable to explore its new nanostructured morphologies in order to achieve higher performance. We present a new method for the fabrication of porous BiVO₄ nanotubes. Powder XRD experiments show that the electrodeposited BiVO₄ nanotubes crystallize in the scheelite-related monoclinic phase. The produced BiVO₄ nanotubes are highly hierarchically ordered and aligned perpendicular to the electrically conductive substrate. The nanostructures were produced by template-assisted electrochemical deposition inside porous anodized alumina oxide. Our method may be extended to other semiconductor materials used in photoelectrochemical systems, such as Bi₂WO₆ and $\gamma$-Bi₂MoO₆.

Bi_0.85La_0.15FeO₃ (BLFO) nanotubes with an average diameter of about 200 nm and wall thickness of about 20 nm are fabricated by sol–gel alumina template technique, and their room-temperature multiferroic properties are studied. Piezoelectricity and ferroelectricity in the BLFO nanotubes are revealed by piezoresponse force microscopy study of individual nanotube. Doping the BiFeO₃ nanotubes with La reduces the crystallization temperature and results in a reduced lose of Bi and therefore improved multiferroic properties of the nanotubes. Enhanced weak ferromagnetism is also observed, and it is attributed to the nano-crystalline structure of the nanotubes.

The magnetic properties and phase diagrams of a ferrimagnetic cylindrical Ising nanotube with spin-1/2 core and spin-3/2 shell are studied using mean-field approximation and Monte Carlo simulation. The effects of shell and core-shell interface exchange couplings and crystal field on the magnetic properties of the system are examined. For some physical parameters, the critical and compensation behaviors are highlighted and first-order phase transitions are observed in the ferrimagnetic ordered region at low temperatures. A comparison between the two methods was performed.

A ferrimagnetic hexagonal Ising nanotube with spin-1/2 core and spin-5/2 shell is investigated using the mean field approximation (MFA) and the Monte Carlo simulation (MCS). More exactly, we have examined the effects of the exchange interactions and crystal field on the magnetic properties of the system. Our phase diagrams show the appearance of critical and compensation behaviors, as well as first-order phase transitions terminating at isolated critical end-points in the ferrimagnetic phase region at low temperatures. Furthermore, we have made a comparison with other studies of similar nanosystems.

Graphene has been reported with record-breaking properties which have opened up huge potential applications. A considerable research has been devoted to manipulate or modify the properties of graphene to target a more smart nanoscale device. Graphene and carbon nanotube hybrid structure (GNHS) is one of the promising graphene derivative, whose mechanical properties have been rarely discussed in literature. Therefore, the mechanical properties of GNHS is studied in this paper based on the large-scale molecular dynamics simulation. The target GNHS is constructed by considering two separate graphene layers that are being connected by single-wall carbon nanotubes (SWCNTs) according to the experimental observations. It is found that the GNHSs exhibit much lower yield strength, Young's modulus, and earlier yielding compared to bilayer graphene sheet. Fracture of GNHSs is found to initiate at the connecting region between carbon nanotubes (CNTs) and graphene. After failure, monatomic chains are normally observed at the front of the failure region, and the two graphene layers at the failure region without connecting CNTs will adhere to each other, generating a bilayer graphene sheet scheme (with a layer distance about 3.4 Å). This study will enrich the current understanding of the mechanical performance of GNHS, which will guide the design of GNHS and shed light on its various applications.

Plasma-based accelerator technology enables compact particle accelerators. In Laser Wakefield Acceleration, with an ultrafast high-intensity optical laser driver, energy gain of electrons is greater if the electron density is reduced. This is because the energy gain of electrons is proportional to the ratio of laser’s critical density to electron density. However, an alternative path for higher energy electrons is increasing the critical density via going to shorter wavelengths. With the advent of Thin Film Compression, we now see a path to a single cycle coherent X-ray beam. Using this X-ray pulse allows us to increase the plasma density to solid density nanotube (carbon or porous alumina) regime and still be under-dense for a Laser Wakefield Acceleration technique. We will discuss some implications of this below.

In this paper, we review the potential applications of single-walled carbon nanotubes in three areas: passives (interconnects), actives (transistors), and antennas. In the area of actives, potential applications include transistors for RF and microwave amplifiers, mixers, detectors, and filters. We review the experimental state of the art, and present the theoretical predictions (where available) for ultimate device performance. In addition, we discuss fundamental parameters such as dc resistance as a function of length for individual, single-walled carbon nanotubes.

Recent searches on carbon nanotubes lead in within INFN (GINT experiment) demonstrate enunciated characteristic of fotoconductivity of such material if illuminated from radiation, in particular from UV. Moreover the material can be easily managed to cover wide sensitive areas and finely structured through nanolitography. Therefore the way is open to a great number of applications in which UV, visible and near IR (150-1100 nm) radiation detectors cover particular importance. The applications would go from space physics (IR and UV detectors) to the high energies physics (Cerenkov detectors) to the UHECR physics (fluorescence light detectors) and to the medical instrumentation (not ionizing radiations).

TiO₂ nanotube arrays were fabricated by anodic oxidation method at different applied voltages and electrochemical properties of the TiO₂ nanotube arrays were investigated. At higher applied voltage, the average pore size and the length of the tubes were increased due to an increase in the rate of TiO₂ formation and dissolution during the anodic oxidation. TiO₂ nanotube electrode fabricated at applied voltage of 30V delivered the 1st discharge capacity of about 235μAh/cm². Although the electrode showed a large irreversible capacity during the initial charge/discharge process, it exhibited excellent cycle performance until the 40th cycle because the larger pore size allowed homogeneous contact between the tubes and liquid electrolyte by easy penetration of liquid electrolyte into the tubes.