Fabrication and properties of nanocapacitors and nanostructures prepared by nanosphere lithography

University of Technology Sydney. Faculty of Science.Nanosphere lithography was used to synthesise nanoscale capacitors as well as arrays of zinc oxide nanostructures. Close-packed polystyrene nanospheres were used as masks and periodic arrays of metals / metal oxides were deposited through the inter-sphere voids onto substrates. The technique was optimised to produce hexagonally close-packed arrays of polystyrene spheres for a range of sphere sizes (200-1500 nm). Nanoscale capacitors were synthesised via evaporative and sputter deposition to produce structures consisting of gold / metal oxide / gold layers on a silicon substrate. A range of metal oxides were investigated including alumina, silica, zinc oxide, titania and hafnia. A significant development reported here involves the charging of these devices and their characterisation using scanning electron microscopy techniques. These methods enable the measurement of the charging time constants of materials in a non-destructive fashion without the requirement to connect wires or contacts. Nanostructures fabricated using zinc oxide as a dielectric material produced rings of zinc oxide nanostructures on the silicon substrate and a mechanism for the ring formation is proposed here. The resultant structures were used as templates to seed the hydrothermal growth of zinc oxide nanostructures. Arrays of zinc oxide nanostructures were also produced using techniques that enable control over the position and amount of growth

The effect of different industrialized building system (IBS) construction methods compared to the conventional method on occupational safety and health (OSH) industry risks in construction

The construction industry is known for the hazardous physical working conditions and high risk of accidents because of the nature of the workplace activities. It is one of the most dangerous business sectors compared to the other industries. The accident cases in construction industry contribute to the rises statistics of accidents in Malaysia. Therefore, IBS construction has been suggested to replace the many initiatives that could be implemented to improve OSH performance due to frequent accidents as a substitute for the traditional construction methods. Improving the performance of the construction industry has pushed forward the need for innovation and adopting new construction methods and technologies in the industry. This study aims to analyze and validate the impact of major activities of the IBS construction method which are prefabricated steel framing system, prefabricated timber framing system and formwork system. This study involved a field observation to on-site that use these 3 types of IBS as a residential building construction method. The data was collected through interviews with the safety and health officers, other than observed the operations involved in each type of IBS method to determine the major activities and OSH risks associated throughout the construction process of the IBS. Next, the activities and the risks involved in each activity were tabulated before it was analyzed and validated with the competent professionals. The findings revealed that the major activities in the prefabricated timber framing system and formwork system have low risk compared to the conventional method. Meanwhile, majority of the activities involved in the prefabricated steel framing system has high risk compared to the conventional method. Moreover, 2 methods have introduced new activities which are prefabricated steel framing system (2 new activities) and prefabricated timber framing system (4 new activities). Therefore, this study offered a better understanding of the risk/hazard of IBS construction method and the effect the IBS towards safety and health

Growth of ZnO nanostructures on Si by means of plasma immersion ion implantation and deposition

Crystalline zinc oxide (ZnO) nanostructures have been grown on Si substrates by means of Plasma Based Ion Implantation and Deposition (PIII&D) at temperature of about 300 0C and in the presence of an argon glow discharge. In the process a crucible filled with small pieces of metallic zinc plays the role of the anode of the discharge itself, being polarized by positive DC voltage of about 400V. Electrons produced by thermionic emission by an oxide cathode (Ba, Sr, Ca)O impact this crucible, causing its heating and vaporization of Zn. Partial ionization of Zn atoms takes place due to collisions with plasma particles. High negative voltage pulses (7 kv/40μs/250Hz) applied to the sample holder cause the implantation of metallic zinc into Si surface, while Zn deposition happens between pulses. After annealing at 700 0C, strong UV and various visible photoluminescence bands are observed at room temperature, as well as the presence of ZnO nanoparticles. The coated surface was characterized in detail using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence (PL) spectroscopy. XRD indicated the presence of only ZnO peaks after annealing. The composition analysis by EDS revealed distinct Zn/O stoichiometry relation depending on the conditions of the process. AFM images showed the formation of columns in the nanoscale range. Topography viewed by SEM showed the formation of structures similar to cactus with nanothorns. Depth analysis performed by XPS indicated an increase of concentration of metallic Zn with increasing depth and the exclusive presence of ZnO for outer regions. PIII&D allowed to growing nanostructures of ZnO on Si without the need of a buffer layer

Large-scale Lateral Nanowire Arrays Nanogenerators

In a method of making a generating device, a plurality of spaced apart elongated seed members are deposited onto a surface of a flexible non-conductive substrate. An elongated conductive layer is applied to a top surface and a first side of each seed member, thereby leaving an exposed second side opposite the first side. A plurality of elongated piezoelectric nanostructures is grown laterally from the second side of each seed layer. A second conductive material is deposited onto the substrate adjacent each elongated first conductive layer so as to be coupled the distal end of each of the plurality of elongated piezoelectric nanostructures. The second conductive material is selected so as to form a Schottky barrier between the second conductive material and the distal end of each of the plurality of elongated piezoelectric nanostructures and so as to form an electrical contact with the first conductive layer.Georgia Tech Research Corporatio

Carbon nanotube and nanofiber growth on Zn based catalysts

In this study, acetylene gas was delivered to a catalyst network consists of NaCl-support and Zn nanoparticles in a temperature range of 500-700°C by means of a chemical vapor deposition (CVD). A principle feature that delineated this CVD study from prior studies lay, first in the method used to support the catalyst and secondly the choice of the catalyst metal. In particular, NaCl was deliberately retained and exploited in subsequent manipulations for the reason that it performed remarkably well as a support medium. The catalytic activity of Zn towards production of CNT/CNFs appeared to be promoted as a result of using molten ionic substrate

Experimental and theoretical investigation of ligand effects on the synthesis of ZnO nanoparticles

ZnO nanoparticles with highly controllable particle sizes(less than 10 nm) were synthesized using organic capping ligands in Zn(Ac)2 ethanolic solution. The molecular structure of the ligands was found to have significant influence on the particle size. The multi-functional molecule tris(hydroxymethyl)-aminomethane (THMA) favoured smaller particle distributions compared with ligands possessing long hydrocarbon chains that are more frequently employed. The adsorption of capping ligands on ZnnOn crystal nuclei (where n = 4 or 18 molecular clusters of(0001) ZnO surfaces) was modelled by ab initio methods at the density functional theory (DFT) level. For the molecules examined, chemisorption proceeded via the formation of Zn...O, Zn...N, or Zn...S chemical bonds between the ligands and active Zn2+ sites on ZnO surfaces. The DFT results indicated that THMA binds more strongly to the ZnO surface than other ligands, suggesting that this molecule is very effective at stabilizing ZnO nanoparticle surfaces. This study, therefore, provides new insight into the correlation between the molecular structure of capping ligands and the morphology of metal oxide nanostructures formed in their presence

Surface disinfections: present and future

The propagation of antibiotic resistance increases the chances of major infections for patients during hospitalization and the spread of health related diseases. Therefore finding new and effective solutions to prevent the proliferation of pathogenic microorganisms is critical, in order to protect hospital environment, such as the surfaces of biomedical devices. Modern nanotechnology has proven to be an effective countermeasure to tackle the threat of infections. On this note, recent scientific breakthroughs have demonstrated that antimicrobial nanomaterials are effective in preventing pathogens from developing resistance. Despite the ability to destroy a great deal of bacteria and control the outbreak of infections, nanomaterials present many other advantages. Moreover, it is unlikely for nanomaterials to develop resistance due to their multiple and simultaneous bactericidal mechanisms. In recent years, science has explored more complex antimicrobial coatings and nanomaterials based on graphene have shown great potential in antibacterial treatment. The purpose of this article is to deepen the discussion on the threat of infections related to surface disinfection and to assess the state of the art and potential solutions, with specific focus on disinfection procedures using nanomaterials