Abstract: Nanotechnology focuses on special properties of a material which emerge from nanometer size—is becoming one of the most promising scientific fields of research in decades. The realisation that the nano-scale has certain properties needed to solve important biomedical challenges and cater to unmet biomedical needs is driving nano-biosystem research. Proper nutrition and a clean environment promote human health. Nanotechnologies are only used to a limited extent at the moment for achieving these aims although it has the potential to revolutionize agriculture and food systems. We will see increasing uses of tools and techniques developed by nanotechnology to detect carcinogenic pathogens and biosensors for improved and contamination free food and agricultural products. This article will review some of the current nanotechnology research that is applicable to agriculture and food technology and project what the future will bring to the newly emerging field of Agrifood Nanotechnology.
Abstract: A solid-state reaction of TiOSO4.xH2SO4.yH2OTiO2 + (x+y)H2O + (x+1)SO3 was induced during milling to synthesis the titanium dioxide nanoparticles. Titanyl sulphate (TiOSO4.xH2O.yH2SO4) and NaCl powders were used as the reactant and diluent phases, respectively. Annealing the as-milled powder at 700°C along with diluent phase and the removal of the NaCl through washing resulted in fairly equiaxed anatase and rutile TiO2 nanoparticles with the mean size in the range of 15-55 nm. The effect of volume fraction of diluent phase (NaCl) and milling time on the particle size distribution, agglomeration and anatase to rutile phase transformation (AR) of TiO2 nanoparticles were investigated by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Investigations showed that increasing the NaCl: TiOSO4 weight ratio (NTR) leads to the formation of nanocrystalline anatase and rutile particles with more uniform size distribution, lower weight ratio of rutile phase and lower agglomeration of particles. Also, it was found that increasing the milling time can effectively decrease the nanocrystalline size of TiO2 down to 16nm and impede A R transformation
Abstract: The standard Local Oxidation of Silicon (LOCOS) technique uses different oxidation rates of silicon and Low Pressure Chemical Vapour Deposited (LPCVD) silicon nitride in steam ambient to structure the field oxide. Due to different coefficients of thermal expansion a pad oxide is needed at the boundary layer to prevent stress from the substrate. This leads to a lateral diffusion of oxygen, also known as “birds beak”, which limits the minimum structure size to a few 100 nm . When scaling down to this dimension, the Shallow Trench Isolation (STI) has become the standard isolation technique for fabrication of high-performance semiconductors to allow a high package density. Unfortunately the STI-process uses Chemical Mechanical Polishing (CMP) which increases the process complexity and leads to high costs. Therefore a new method which uses a low stress Plasma Enhanced Chemical Vapour Deposited (PECVD) silicon nitride without a pad oxide at the boundary layer will be presented in this paper.
Abstract: We have investigated the growth and characteristics of nanoscaled thin films of carbon, nickel, and platinum. The nanoscaled thin films were deposited on Si and quartz substrates with or without a surface layer of carbon, nickel, or platinum using a DC magnetron sputter deposition technique. The thicknesses, which were determined using ellipsometry, are all less than 10 nm. The film structures were examined using glazing angle incident x-ray diffractometry and Raman spectroscopy. The electrical and optical properties were determined using a four point probe technique and UV-VIS-IR spectrometry, respectively.
Abstract: Powder precursors of the Al2O3-ZrO2 system were synthesized by the sol-gel method. Dispersity of the powders depended on synthesis and drying conditions. Differential Scanning Calorimetry, X-Ray diffraction, and method of adsorption–desorption isotherms were used to characterize the interrelations between particle size and phase transition in the Al2O3-ZrO2 system. It was revealed that azeotropic drying under overpressure is quite effective for obtaining well-dispersed powder precursors synthesized by the sol-gel method. In contrast to bulk materials, tetragonal, cubic, and monoclinic phases were found to exist in a wider temperature-composition range. It was shown that the existing phase symmetry in the well-dispersed powders correlates with the crystallite size.
Abstract: The effect of chemical composition on the bonding environment of Cu, in a series of Ti1-x Cux and TiN/Cu films, is studied using X-Ray Absorption Spectroscopies (XAFS) at the Cu-K-edge. The EXAFS analysis reveals that in all studied samples Cu is amorphous. However, its bonding environment depends on the chemical composition. More specifically, in the Ti1-xCux films, Cu is coordinated with Ti and Cu and belongs both to intermetallic TiCu and to an amorphous Cu matrix. The coordination number of Cu, i.e., the sum of Ti and Cu first neighbours, increases systematically from 6.3 ± 0.7 to 10.6 ± 0.9 when the Cu content increases from 24.1 to 52.7 at%. On the contrary, in the TiN/Cu films, the type of atoms that consists the 1st nearest neighbour shell of Cu varies as a function of the Cu concentration. More specifically, in the TiN/Cu film with the lowest Cu content (27.3 at%), intermetallic TiCu is detected. At intermediate Cu concentration (37.8 at%), Cu is bonded to both Ti and Cu atoms. Finally, in the TiN/Cu film with the highest Cu content (67.7 at%), Cu is metallic.
Abstract: Nanostructure composites of Copper-Alumina were successfully produced by new mechanochemical method using two different routes. First, route A was carried out by addition of coarse copper to aqueous solution of aluminum nitrate, and second, route B was also carried out by addition of coarse copper to aqueous solution of aluminum nitrate and ammonium hydroxide. In both routes, the mixtures were heated in air and milled mechanically to get the oxides powders of CuO and Al2O3. The CuO was reduced in preferential hydrogen atmosphere into fine copper. The composite powders have been cold pressed into briquettes and sintered in hydrogen atmosphere. The structure and characteristics of powders as well as sintered composites produced from both routes were examined by XRD, SEM, EDS, TEM and metallographic techniques. The results showed that, in both routes, nano-sized particles of alumina were formed and dispersed within the copper matrix. The structure revealed the formation of CuAlO2 spinel structure at copper alumina interface. Nanocomposites produced by route-B showed finer alumina particles of 30 nm compared to 50 nm produced by route-A resulting in improved properties in terms of relative density, macro and microhardness values.
Abstract: High surface area TiO2 layers are particularly attractive for photocatalytic applications; suitable anodising processes can be used to produce the oxides and to tune their morphology and structure. In the presented research, an alternative technique to enhance the surface area of anodic oxides was identified. This was achieved with the implementation of an anodising treatment performed by supplying alternating current in diluted hydrochloric acid (feeding voltage ranging from 5 V to 10 V). Alternating current anodising caused the formation of a double texture of pits on the oxide surface, the bigger ones being some micrometres wide and formed by smaller pits hundreds of nanometres large; these holes distribution and dimensions can be modulated by varying electrolyte concentration, feeding voltage and anodising time.
Abstract: A process for nanowire fabrication from gold nanoparticles is described. In this process, we have combined the ink-jet delivery of a nanoparticle colloid with the dielectrophoresis technique. Ink-jet printing is used for the accurate delivery of gold nanoparticle colloid in an exact position and quantity. The nanoparticles dropped to a two electrode gap are ordered into nanowires by the dielectrophoresis force which is induced by the applied AC voltage. The nanowire structures are characterized by microscopy techniques and I-V measurements.
Abstract: Yield of carbon nanotubes (CNTs) depends on numerous process parameters such as temperature of synthesis, type of catalyst, type of precursor, time of precursor flow and partial pressure of precursor gas as well as carrier gas, etc. Experiments were performed in order to find the optimum temperature of synthesis for varying time of precursor flow. The yield was evaluated in terms of mass of crystalline CNTs per gram of substrate and/or catalyst. The CNTs were grown on a calcium carbonate (CaCO3) substrate, with iron-cobalt (Fe-Co) as a catalyst, using acetylene (C2H2) as a precursor gas and argon (Ar) as a carrier gas. A three-stage purification process, incorporating two acid treatment steps and one annealing step, was used for purification which ensures high grade purity of CNTs. The highest yield of 21.4 g of CNTs per g of catalyst was achieved at 700oC for 60 min of synthesis. The CNTs were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Raman, Thermo-gravimetric analysis (TGA), and Gas chromatography (GC).