International Journal of Nanoscience

Among several aspects concerning the growth of thin films on solid surfaces, we focus our discussion on the physical observable known as the island size distribution function (SDF). Since this is a subject large enough to require a full review, even a whole book, we have limited our survey to the scaling properties of the distribution function and to some of its possible shapes. In particular, we discuss the fast and slow nucleation processes in diffusional growth and the KJMA (Kolmogorov–Johnson–Mehl–Avrami) distributions. Space has been given to the mathematical demonstration of the principal equations, in order to render the paper usable also to neophytes of thin film growth. Experimental particle (SDFs) are also reported and discussed.

Zn_1-xMn_xO (x = 0, 0.02, 0.06, 0.10, 0.15) nanopowders were synthesized by the sol–gel technique calcinated at low temperatures. By decreasing the grain size in ZnO, the solubility of magnetic impurity has been increased and no detectable secondary phases were observed even in the high Mn-doping samples. The phase formation, size and morphology of nanoparticles were investigated using X-ray diffraction and SEM observations. The samples were ferromagnetic and the Curie point was found in the range 150–170 K for Zn_0.94Mn_0.06O and 135–150 K for Zn_0.98Mn_0.02O. Optical characterization and the effect of doping were carried out by means of Fourier transform infrared (FTIR) spectroscopy. Kramers–Kronig analysis was employed to evaluate the optical constants of pure ZnO and ZnO:Mn nanopowders.

We demonstrate Co, Fe, and Ni encapsulated polyaniline (PAni) nanotubes using a three-step anodization and electrodeposition process. The electrodeposition process is used to create the tubes, as well as the wires, in a highly reliable manner. The metal-filled PAni structures embedded inside nanoporous alumina templates are fabricated in the form of an array. The magnetic properties of these structures are investigated as a function of temperature. These results are compared with the magnetic properties of nanowires embedded inside nanoporous alumina templates.

With the progress of localized treatment procedures such as unicompartmental knee replacement, chondrocyte implantation and osteochondral grafting, it has become important to develop a means of assessing early stage cartilage and bone degradation. This review outlines the recent advances in arthroscopic tools, and discusses the major problems and issues faced in developing effective assessment methods. The central problem in joint tissue assessment is to discriminate degradation from the wide variation in normal tissue. This discrimination, however, is far from being realized by current methodologies, and is compounded by the difficulty in correlating structural features with pain and mobility in the joint. In response to these findings, an argument is provided for a new direction in quantitative tissue evaluation using an integrated chemical, structural, and functional approach, and the importance of structure–function–pain relationships.

The stability and size effect analysis of different isomeric structures of Mg_n(n = 1–5) nanowires have been investigated by employing ab-initio approach. We have considered various geometrical structures up to five atoms to explore the minimum energy configuration. In the present study, we have calculated various physical properties in large energy interval for all structures. In particular, we have analyzed the effect of shape and size on these calculated values and investigated density of states (DOS) in four different ways to see the microscopic changes in their nature of peaks. We predict that five atom tetrahedral structure is stable having highest binding energy and DOS. The band structure calculations of all wires reflect the possibility of sufficient number of channels for quantum conduction and are metallic in character. In addition, we have also analyzed the effect of hydrogen adsorption on most stabilized geometrical structure of magnesium (Mg) nanowire which shows no evidence of better stability in comparison to pure Mg nanowires.

We analyze and propose an all-optical switch working over the C-band of the International Telecommunication Union (ITU), which is based on nonlinear switching cells made of photonic crystal (PhC). Indeed, the nonlinear switching cells are directional couplers (DCs) embedded in PhC, which can work over the C-band of the ITU (wavelength from 1530 to 1565 nm). The nonlinear switching method uses a relatively low-power external command signal for obtaining nonlinear effects. This external command signal is inserted in the central coupling region of the DC, which acts as another waveguide. The switching process is based on the change from the cross state to the bar state owing to the external command signal. In our simulations we used the plane-wave expansion (PWE), finite-difference time-domain (FDTD), and our own binary propagation method (BiPM).

Carbon nanotube (CNT) yarns were drawn from the web found on the CVD furnace wall. The yarns were twisted and their tensile behavior was investigated through in-situ SEM and regular tensile tests. The mechanisms involved in the CNT yarn deformation were identified. The twisted CNT yarns were found to have a good ability to stretch and deform and featured a diameter-dependent strength.

Hollow germanium tubular nanostructures have been obtained by a hydrothermal process at a temperature of 400°C and pressure of 7 MPa with quick cooling to room temperature. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) show that the germanium tubular nanostructures are polycrystalline and have open-end structures at the tips. The diameter of germanium tubular nanostructures is about 40–70 nm and the inner pore size is about 10 nm in average. We propose the rolling mechanism for the formation of tubular nanostructures from lamellar nanostructures to explain the possible formation process of germanium tubular nanostructures.

In our earlier works, the effective mass theory (EMT) was critically examined for a hydrogenic donor in a quantum well (QW) and in a quantum dot (QD) after introducing position dependent effective masses (PDEMs). Our results showed that the use of constant effective mass was justified for all well dimensions a*, the effective Bohr radius which is 100 Å in GaAs. Here the validity of EMT in the presence of an electric field is examined. The electric field dependent donor ionization energies in both the systems with finite and infinite barriers for different well dimensions have been calculated. It is shown that the electric field affects donor binding energies appreciably, the variation being larger in the case of finite barrier systems when PDEM is used. The donor polarizability has also been estimated in both the systems and the results are compared with other works in the literature. The use of EMT is justified if constant effective mass is used in general, even though large variation in the ionization energies occur in the finite barrier cases when position dependent mass is included correctly.

Microreactor technology is a new concept of chemical synthesis for nanoparticle production. The "state of the art" in microreactor fabrication and its application to the synthesis of nanoparticles is reviewed. The microfluidic concepts, the materials and technologies for microreactor manufacture, with particular emphasis on polymers and microreplication techniques, and their application to the synthesis of various nanomaterials in microreactors are presented. The unique synthesis properties of various nanoparticles using a microfluidic process as well as broader impact in term of nanomaterials engineering, i.e., selectivity and monodispersity, reduced amount of chemicals, fast reaction, minimum cost, a better control of the process, minimum waste and reduced amounts of reaction byproducts and improved safety, are discussed in comparison with the traditional wet-chemical batch synthesis approach.