Nano

One-dimensional (1D) chain-like structures are of special significance because of their interparticle magnetic interactions and potential applications in various fields, such as micromechanical sensors. This paper attempts to review the field of research into magnetic chains including monatomic chains and nanoparticle chains. The synthesis methods used mostly belong to one of the following categories: magnetosome chains in magnetotactic bacteria, zero-field self-assembly, magnetic field induced (MFI) assembly, template-directed synthesis, and gas phase synthesis. The potential applications of nanoparticle chains, mainly in the field of magnetic recording media, sensor, biomedicine and magnetic-field tunable photonic crystal are discussed.

Using classical all-atom molecular dynamics simulation, we investigated the molecular dynamics of palmitoyloleoylphosphatidylcholine and palmitoyloleoylphosphatidylethanolamine membrane bilayers enforced by a single-wall carbon nanotube. We postulated that an insertion of a single-wall carbon nanotube in the center of lipid membrane "strengthens" ambient lipids and prevents the whole system from further destabilization by high temperatures. We implemented root mean square deviation and root mean square fluctuation analyses of simulated structures from their initial states in order to emphasize the molecular dynamics behavior of these structures during 1000 ps simulation time at different temperatures. The data suggest that an intercalated carbon nanotube restrains the conformational freedom of adjacent lipids and hence has an impact on the membrane stabilization dynamics. On the other hand, different lipid membranes may have dissimilarities due to the differing abilities to create a bridge formation between the adherent lipid molecules. The results derived from this work may be of importance in developing stable nanosystems for construction of novel biomaterials and delivery of various biomolecules in the fields of biosensors, biomaterials, and biophysics.

Dopant redistribution in a multilayer structure during annealing by laser pulses for production of implanted-junction rectifiers has been analyzed. The analysis shows that heating the surface region of the multilayer structure leads to increasing of previously described effect of simultaneously increasing of sharpness of implanted-junction rectifier and homogeneity of dopant distribution in doped area. It was found that the theoretical spatial distribution of dopant agrees with the experimental one. Annealing time has been optimized for laser pulse annealing.

The catalyst-free synthesis of silicon carbide (SiC) nanowires was carried out from polyvinyl alcohol (PVA)/silica electrospun nanofibers at high temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and thermogravimetery analysis (TGA) were employed to study morphology and formation of SiC nanowires. Based on the TGA analysis, the carbon yield was increased when inert gas flow rate and heating rate decreased and polymeric nanofibers has been stabilized. The XRD and TEM results showed that the produced nanowires were crystalline β-SiC and rather homogeneous in thickness with an average diameter around 50 to 70 nm and a length of more than 10 μm. Finally, a possible growth mechanism of β-SiC nanowire based on a vapor–solid (VS) mechanism was proposed.

Branched self-assembling peptides bearing epitopes with free N-termini were designed. A lysine residue was used as branch point to present more than one epitopes in a single peptide. Atomic force microscope, circular dichroism and Fourier transform infrared spectroscopy data indicate that the N-terminus attached epitope sequences do not prevent the formation of the β-sheets and the self-assembling of these peptides into stable nanofibers in aqueous solutions. Rheology experiments show that these peptides could form self-supporting scaffolds once electrostatic repulsions were screened by electrolytes. Fluorescence spectra measurements upon binding of FITC-avidin to surfaces of nanofibers were performed to investigate the effect of charged aspartic acid residues in RGD epitopes at the lysine branching on packing and accessibility of the epitopes. Results show that the electrostatic interaction between hydrophilic side chains at branching and nanofiber surfaces may significantly affect the conformational freedom and accessibility of the epitopes at the periphery of the nanofibers. Cell entrapment experiments reveal that the attached RGD epitopes with free N-termini are biological active.

One-step roll-to-roll lamination transfer of graphene was achieved by poly(ethylene co-vinyl acetate) as a binding material which has thermoplastic property and wide rubbery-plateau region between T_g~T_m. The transferred graphene film has a transmittance of 96.7% at 550 nm and 1.96 kΩ/sq of sheet resistance measured by simple 4-probe method. Standard deviation was found to be 0.198 kΩ/sq.

NiO nanoparticles were prepared on the silica surface by adsorption phase synthesis. The adsorption and preparation experiments of different reactants were designed to select suitable reactants for the synthesis of NiO particles. Using X-ray Diffraction (XRD) and transmission electron microscopy (TEM) analyses the differences in morphology and grain size of NiO particles prepared under various conditions were characterized. When the quantity of Ni(NO₃)₂ exceeded 2.0 mmol, the conglomeration of NiO particles became obvious. While the temperature increased from 0 to 40°C, the elevation of reaction rate and supersaturation in the adsorption layer resulted in appearance of NiO particles with smaller size. When the temperature exceeded 40°C, the attenuation of the adsorption layer led to the appearance of the blank silica without NiO particles.

We report the synthesis of luminescent-doped core/shell quantum dots (QDs) of water-soluble manganese-doped zinc sulfide (ZnS:Mn²⁺/ZnS). QDs of ZnS:Mn²⁺/ZnS were prepared by nucleation doping strategy, with thioglycolic acid (TGA) as stabilizer in aqueous solution. Structure and optical properties of the ZnS:Mn²⁺/ZnS core/shell quantum dots were characterized by X-ray diffraction and photoluminescence emission spectroscopy. The influence of the synthesis conditions on the luminescent properties of ZnS:Mn²⁺/ZnS QDs is discussed. Different Mn²⁺ concentrations, ratios of the TGA/(Zn+Mn) and thickness of the ZnS shell were used. Results showed that the ZnS:Mn²⁺/ZnS QDs are water-soluble and have improved fluorescence properties. Therefore, Mn²⁺-doped ZnS quantum dots could be potential candidates as fluorescent labeling agents in biology.

This paper reports the synthesis and characterization of ternary nanocomposites consisting of polyaniline (PANI), multiwalled carbon nanotubes (MWCNTs) and manganese dioxide (MnO₂) at different MWCNT–MnO₂ loadings. The composite electrical percolation threshold is investigated as well. The in situ nanocomposites were characterized by UV-visible, Fourier transform and Raman spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, and electrical conductivity measurements. The conductivity of the nanocomposite reached up to 78.79 Scm^-1 with 50 wt.% addition of MWCNT–MnO₂ with good conduction stability and reversibility. The percolation threshold of this nanocomposite was achieved at 0.5 wt.%. Using the scaling law of the percolation theory, it was found that the theoretical conductivity of the nanocomposite exhibited an exponential factor, (t) of 1.38 instead of the universal t value of 2.

We report the preparation and thermal annealing of SnO₂-core/TiO₂-shell nanorods using a two-step process comprising the thermal evaporation of Snpowders and the sputter-deposition of TiO₂. X-ray diffraction analysis revealed that the shells were crystallized by annealing. Photoluminescence measurements showed that the major yellow emission of the SnO₂ nanorods was enhanced in intensity by sheathing them with TiO₂ and was further enhanced by annealing. A reducing atmosphere was found to be more efficient in enhancing the yellow emission by annealing than an oxidative atmosphere. The origin of the emission enhancement by coating and annealing is also discussed.