Advanced Materials Research Vols. 403-408

Abstract: Urban Rain-Flood disasters become more ordinary and serious recently under global warming and unreasonable exploitation. Summed up the characters of urban rain-floods, the mechanism of urban rain-flood disasters is analyzed. More ever, the main countermeasures to utilize urban rain-flood based on Nano technology comprehensively and effectively are put forward.

Abstract: The adsorption capability of porous nano-barium-strontium titanate by sorghum straw template method (SBST) for nickel in water was studied. The optimum experimental parameters for the adsorption and preconcentration of the nickel, such as pH, time, eluent and coexisting ion, have been investigated. The results showed that the nickel in water could be adsorbed on the SBST. The adsorbed quantitively was affected by the pH value of medium and time. In the medium of pH 5-8, the adsorption time was 20 min, and capacity of adsorption was 13.27 mg•g-1. The adsorbed nickel could be completely eluated using 2 mol•L-1 HNO3. The pre-concentration factor for nickel was more than 100. The method has been applied to the preconcentration and flame atomic absorption spectrometry determination of nickel in water samples. The recoveries were 92.0%-104.0%.

Abstract: In this study, carbon nanotubes (CNTs) are anticipated as nano/micro structured reaction field for micro Bio-Analysis. CNTs reaction field were made on quartz glass substrate using chemical vapor deposition and Self-Organization of CNTs. To evaluate and reveal the optimal structure of CNTs structure, protein adsorption characteristics were evaluated by fluorescence and transmitting spectroscopy analysis. By fluorescence analysis, it is revealed that proteins tend to adsorb to tip of CNTs structure and finer structure. Finally, protein adsorption was detected as a change of transmissivity of CNTs reaction field, and its detection limit was about 100 nmol/l. Time for analysis was greatly shortened by using transmitting spectroscopy.

Abstract: We made the open well biochemical analysis system using piled up CNTs as the reaction fields on a porous glass substrate. The effects of the structures of CNTs and the surface activation using O2 plasma to the sensitivity are evaluated. Reaction fields of CNTs layer of 0.2 [mg] showed twice higher sensitivity than that of 0.1 [mg], and three times higher sensitivity than Si wafer. O2 plasma irradiation also increased the sensitivity of this open well system of biochemical analysis.These increases can be described as the results of the larger sorbable surface area of the reaction fields.

Abstract: ^{Superscript text}_{Subscript text}Our study is to develop a general design of biosensors based on vertically aligned Carbon Nanotube (CNT) arrays. Glucose biosensor is selected as the model system to verify the design of biosensors. In the preliminary design, glucose oxidase (GOx) is attached to the walls of the porous alumina membrane by adsorption. Porous highly ordered anodized aluminum oxide (AAO) are used as templates. Deposited gold on both sides of template surfaces serve as a contact and prevent non-specific adhesion of GOx on the surface. In order to find out optimized thickness of gold coating, the redox reaction in([Fe(CN)₆]^3-/[Fe(CN)6]4-system is monitored by CV. Subsequently, enzymatic redox reaction in glucose solutions is also attempted by CV. We expect protein layers with GOx from a conductive network. To take advantage of the attractive properties of CNTs, the design of enzyme electrodes is modified by attaching CNT onto the sidewalls of AAO template nanopores and then immobilizing GOx to the sidewalls and tips of CNTs. Cobalt is used as a catalyst to fabricate CNTs. As a result, MWCNTs are fabricated inside the AAO templates by CCVD.

Abstract: In this paper, nonlocal Euler-Bernoulli beam theory is applied to investigate the dynamical behavior of a single-walled carbon nanotube (SWCNT) with an extra added nanoparticle. The SWCNT is assumed to be embedded on a Winkler-type elastic foundation with cantilever boundary condition. This configuration can be used as a nano-mass sensor which works on the basis of the changing the natural frequencies. The results show that the added mass causes an obvious increase in sensitivity of SWCNT-based nano-mass sensor, especially for stiff mediums, small nonlocal parameters, and stocky SWCNTs.

Abstract: Nano-MgO thin films were grown on the cleaned glass substrate via sol-gel spin coating techniques using magnesium acetate tetrahydrate, ethanol and nitric acid. For the thin films deposition, the solutions were prepared at six different molar concentrations (0.1M, 0.2M, 0.4M, 0.6M, 0.8M and 1M). The thickness and roughness of nano-MgO films was found to be increased with an increase of molar concentration. The increment in particle size and agglomerated particles were observed from FESEM (JEOL JSM-J600F) images as the molar concentration increased from 0.1M to 1.0M. The results showed 0.4M nano-MgO films have the best properties for example it has a uniform film, non-porous structure and has nanometer dimension size which around 42.8nm.

Abstract: The aim of this research was to calculate Yong modulus, Bulk modulus and the elastic constants of Rh-20at%Pd (atom percent) nanowire. The molecular dynamics simulation technique was used to calculate the mechanical properties at constant temperature, constant pressure ensemble. The cohesive energy of the model nanowire systems was calculated by Quantum Sutton-Chen many body potential. The temperature and the pressure of the system were controlled by Nose-Hoover thermostat and Berendsen barostat, respectivly. In addition effects of the diameter of nanowire on the mechanical properties were studied. The obtained results show that, when the diameter of Rh-Pd nanowire increase, elastic constants, bulk modulus and Young modulus all increase, and when the diameter reaches about 5.5 nm, the properties began to level off and remain constant.

Abstract: Nanoparticles ZnO thin films have been deposited using sol-gel spin coating technique. A 0.4M sol of ZnO had been prepared by dissolving zinc acetate dihydrate in monoethanolamine (MEA), and 2-methoxyethanol as a stabilizer. Thin films are then spin coated onto quartz substrate with rotation speed of 3000rpm. After each layer, the samples were heated at 150 oC and annealed at 550 oC; which are defined as layer-by-layer process. The aim of this paper is to study the effect of annealing time to the structural, electrical and optical properties of the films. XRD result shows highest peak observed from sample annealed for 1 hour at (102) and (002) orientation. Calculation shows that the film annealed for 1 hour gives lower resistivity at 92.29Ω.cm which is due to the oxygen adsorption and good crystalline quality. Photoluminescence measurements exhibit UV emission centred at 380 nm and yellow-orange emission centred at 580 nm. Optical transmittance of the films show transparency above 70% for sample annealed for 30 minutes.

Abstract: Surface acoustic wave (SAW) sensors form an important class of micro sensors in the microelecto mechanical systems (MEMS) family. Mass loading effect of a sensing medium is one of the prime sensing principles in SAW sensors. Recently we reported mass loading effect of high aspect ratio nano-pillars attached to a SAW resonator. We observed increase in resonance frequency of the SAW resonator in addition to the general mass loading characteristics. We concluded that when the resonance frequency of the pillar is equal to the SAW resonator frequency, the resonance frequency shift caused by mass loading of pillar tends to a negligible value. When such resonating pillars are used as sensing medium in SAW sensors, even a very small change in the dimension of the pillar will offer significant resonance frequency shift. Accordingly, high sensitive SAW sensors can be developed. However in practice it’s quite difficult to manufacture nano-pillars with accurate dimensions such that they resonate with SAW resonator. There is more probability that the pillars may closely resonate with SAW device and offer mass loading. In the present work we have extended our earlier work and performed finite element method (FEM) simulation to study the insight physics of the closely resonating pillars and their effects on acoustic wave propagating on SAW substrate. In this paper we present the discussion on the resonance effects of typical closely resonating pillars on resonance frequency spectrum of the SAW resonator and observations in the pressure wave at the contact surface of the pillar and SAW resonator substrate. It is observed that when the nano-pillars closely resonate with SAW resonator, the pillar oscillations combine with waves propagating in the substrate and introduce beat frequencies. The results and discussion of this paper adds additional information in designing SAW based coupled resonating systems.