International Journal of Nano Dimension
Volume:3 Issue: 1, Summer 2012

Fabrication, characterization and application of micro-/nano-rods/wires are among the hottest topics in materials science and applied physics. Micro-/nano-rod-based structures and devices are developed for a wide-ranging use in various fields of micro-/nanoscience (e.g. biology, electronics, medicine, optics, optoelectronics, photonics and sensors). It is well known that the structure and properties of micro/nano rods depend greatly on their environment of application. Therefore, in this paper, torsional vibration of microbars is formulated based on the strain gradient theory to study the vibrational behavior at micro/nano scale. The strain gradient theory is a non-classical theory capable of capturing the size-effects. The governing equation and both the classical and the non-classical boundary conditions are derived employing the Hamilton’s principle. In the free-vibration case, the characteristic equation is derived and solved analytically. The torsional free-vibration behavior of a fixed-fixed strain gradient microbar is investigated and the results are compared to those evaluated by the classical and modified couple stress theories noted that the two latter theories are special cases of the strain gradient theory. The effects of the length and the radius of the micro rods on the various modes of torsional natural frequencies are investigated in detail. The results of this study can be useful in the design and analysis of the next generation micro-electro-mechanical-systems and nano-electro-mechanical-systems which uses the torsional vibration properties of the micro-/nano-rods.

A novel computational fluid dynamics and molecular kinetic theory (CFD-MK) method was developed to simulate the impingement of a nanodroplet onto a solid surface. A numerical solution of the Navier–Stokes equation using a volume-of-fluid (VOF) technique was used to model nanodroplet deformation. Dynamic contact angle during droplet impact was obtained by molecular kinetic theory. This dynamic contact angle was then implemented in the numerical model used to simulate the process. The spreading behavior was analyzed for the wettable, partially wettable and nonwettable surfaces. The consistency between the two results was good both qualitatively and quantitatively.

Synthesis, characterization, spectral and theoretical calculations of sodium tetrafluoroborate (III) (STFB) has been studied in this research. Sodium tetrafluoroborate (III) was synthesized by a sonochemical method and characterized by IR, UV/VIS, 11B-NMR and Mass spectrometer techniques. The nano compound was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and IR spectroscopy. The structure of synthesized compound was optimized at the B3LYP/LANL2DZ level of theory and theoretical parameters such as structural data, molecular specifications, and infrared spectra were extracted by using Gaussian 03 program. Theoretical data show good agreement with the experimental results. Biological properties of this compound such as antitumor and antibacterial properties studied. This new complex showed excellent antitumor activity against one kind of cancer cells that is K742 (human chronic myeloid leukemia) cells. Also the compound was tested against the bacterial species Staphylococcus aureus, Escherichia coli, Staphylococcus Epidermidis, Estreptococo B and Shigella.

Interaction and correlation effects in quantum dots play a fundamental role in defining both their equilibrium and transport properties. Numerical methods are commonly employed to study such systems. In this paper we investigate the numerical calculation of quantum transport of electrons in spherical centered defect InGaAs/AlGaAs quantum dot (SCDQD). The simulation is based on the imaginary time solution of time-dependent Schrödinger equation, under effective mass approximation by using finite difference method. The self-consistent properties of the system solution of the time-dependent Schrödinger coupled with poisson equations have been self-consistently solved and the Hartree and exchange-correlation potentials as well as the penetration of wave function in the barrier regions have been calculated. Electron density and potential energy are calculated in SCDQD. The interaction between the charge carriers and corresponding barriers causes the more drastic repulsion of charge carriers from the infinite wall than the barriers within the structure. The oscillatory structures in the active region are caused by the quantum effect of tunneling and depletion near the barriers.

In this paper, the electronic eigenstates and energy spectra of single and two-interacting electrons confined in a concentric double quantum rings with a perpendicular magnetic field in the presence of on-center donor and acceptor impurities are calculated using the exact diagonalization method. For a single electron case, the binding energy of on-center donor and acceptor impurities are also calculated. The effects of centrifugal, confinement and diamagnetic potentials on the binding energy are investigated. It is found that the binding energy decreases by increasing the centrifugal or confinement potential. Also, it is shown that the binding energy increases by increasing the magnetic field. The effects of on-center impurity on the energy spectrum and angular momentum transition of the lowest states are investigated for the both single and two-interacting electrons. It is found that the on-center donor impurity increases the fractional Aharonov-Bohm oscillation period while the acceptor impurity acts inversely and decreases the fractional Aharonov-Bohm oscillation period.

Nanosized metal oxides dispersed polymer composites constitute a fascinating class of polymer composite materials. Synthesis of such composite materials through solvent casting enhances the polymer synthetic technology. Solvent casting method was used to prepare Cobalt oxide (Co3O4) dispersed Poly (methyl methacrylate) (PMMA) nano composite. X-ray diffraction tool is used to know the structural behavior composite Development of the crystallinity in the composite film is observed. Scanning Electron Micrograph (SEM) tool is used for morphololical study of the sample. The fine dispersion of the cobalt oxide particles is observed in the composite image. Bonding nature in the pure PMMA and composite materials are studied by FT-IR tool. This study shows the shift in some peaks and disappearance of some peaks reveals the formation of composite between PMMA and cobalt oxide. Thermal behavior of the composite is also well studied.

In recent years, using Sol-gel procedure for the purpose of laboratory and industrial synthesis of Nano-structures, and especially silica Nano-particles, has been significantly increased. In this research, silica particles were synthesized by Sol-gel procedure and their physical and chemical properties were studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA). The effect of structural modifiers on the morphology and diameter of Nano-particles was also investigated. In addition, the reaction was carried out in the presence of ultrasonic waves in periods of 10, 30 and 60 minutes and the effect of these waves on the different stages of reaction was studied by means of SEM. Moreover, spherical particles of 50 to 80 nanometer sizes were synthesized and characterized that can be very useful hosts for lanthanide complexes which can be used in drug delivery systems, radiotherapy, photo luminescence (PL), applications and manufacturing of special lasers. Different amounts of Lanthanum nitrate hexahydrate were also added to the mixture during the creation of nanoparticles. Then simulated body fluid (SBF) was produced to study both, the capability of these Nano-structures in regulated delivery of drugs such as lanthanides, and releasing of lanthanides in 10 minute periods for 80 hours. Finally, lanthanide concentration in SBF was studied by means of inductively coupled plasma (ICP). According to the obtained results from ICP analysis, loaded lanthanide does not release from silica network. These loaded lanthanides to mesoporous silica can be used in radiotherapy and particularly in liver cancer.

In the past decades, many methods have been developed to synthesize zero- dimensional nanoparticles, quasi–one–dimensional (1D) CuO nanostructures, such as metal organic deposition technique, microwave irradiation, sol-gel-like dip technique, reverse micelle-assisted route, chemical method, and simple template free solution route. Among those synthesis methods, hydrothermal and chemical reaction methods are of particular interest because they are safe and environmental-friendly synthesis. By use of nonionic surfactant polyethylene glycol (PEG), the clew CuO nanostructure with the diameter of about 4 μm was prepared at 150˚C for 11 hr. As the temperature increased to 160C for 11 hr, the gear wheel CuO nanostructure with the diameter of about 70 nm was made. Furthermore, two other temperatures (180 and 200) are utilized for 20 hr to produce nanowire. The product was characterized by powder X-Ray diffraction, and scanning electron microscopy SEM showed the various shapes of CuO nanostructures, including clew, gearwheel, and nanowire bundles.

Well faceted CuO nanoparticles, were synthesized by thermal-assisted dissociation method at reflux temperature in a short period of time. A possible mechanism for synthesis of such highly pure and stable nanoparticles is tentatively proposed by FT-IR study. The large surface area and rich exposed active sites are expected to endow such nanoparticles with excellent performances in catalysis as demonstrated here for the remarkable catalytic activity with respect to the oxidation of alcohol. This interesting result highlights the advantage of such a CuO nanostructure over the bulk counterpart, i.e. the high density of active sites and large surface area, which places a solid foundation for the feasible and promising application of such highly faceted nanomaterials in catalysis. It is the first report on the nanometer-sized faceted CuO acting as a catalyst for an oxidation reaction and simultaneously a good example for the combination of green chemistry and functional materials.

The Mössbauer spectra of nanoferrite materials such as Ni0.25Mn0.75Fe2O4, Co0.5Mn0.5Fe2O4 and Ni0.4Co0.6Fe2O4 have been reported and the above materials were prepared by sol-gel combustion method using metal nitrates as source material and Polyvinyl alcohol(PVA) as agglomeration reducing agent. As the structural, thermal and magnetic properties (VSM) of the above ferrites have been published already, hence, the present paper reports the Mössbauer studies of the nanoferrites. Based on the observed values of hyperfine parameter such as Isomer shift (IS), Quadrupole splitting (QS) and hyperfine field values, the distribution of ion and structure of the ferrites has been reported.

In this paper electrical conductivity measurements and optical investigations takes place in AOT/ heptane/ (water or aqueous) systems. The water in oil system prepared with adding water in 50% by weight of AOT/ heptane solution. In other systems instead of water, aqueous solutions of 1) zinc acetate and water 2) Potassium Hydroxide and water were used. In each phase, the trend of the electrical conductivity values changes at a proper water or aqueous solution concentration. The optical properties investigated through two crossed Polaroid. The different phases can be distinguished from each other; the phases characterized are as isotropic, anisotropic or mixed phase