Advanced Materials Research Vol. 832

Abstract: The plant disease such as Cucumber Mosaic Virus (CMV) and Papaya Ring Spot Virus (PRSV) is a most dangerous disease that can decrease productivity and quality of the vegetable and fruit. Besides that, its also can destroy and kill those plant in long term when infected and to tackle this problem at early stages, the nanowire based biosensor application is a most reliable sensor nowadays because of advantages towards detecting biological molecule especially plant diseases.In order to dealing with tiny form of molecules such as virus is very difficult and due to the nanostructure uniqueness such as nanowire, it can be done by undergo formation of nanowire process.Result will be elaborated about how nanowire working environment in order to detecting those virus.

Abstract: There is a growing interest in unique-sized nanomaterials in numerous engineering applications due to their properties such as a very high surface area to volume ratio and effect of quantum confinement. The aim of this paper is to investigate the fluid flow profile at various levels reaction time in the mixing stage during the process of production nanosized materials using an effective numerical approach. Therefore, virtual modelling techniques were employed to model the internal flow in the mixing stage. Pre-processor software, GAMBIT 2.4 was used to create the mixer model and generate the meshes. Then, the model was exported to FLUENT 6.3.26 for further fluid flow analysis. A maximum pressure of 300 bars was applied to produce nanosized material in the mixer. The simulation results revealed that the inlet pressure yielded the great impacts on the production of nanosized material. The effects of inlet pressure on different reaction time significantly influence the flow behaviour as clearly showed in the simulation result. Thus, this study is expected to provide valuable guidelines to any nanoscale industries during production process and further analysis were needed in this field of study.

Abstract: This paper studies the Capacitance-Frequency of titanium dioxide (TiO₂) thin film-based interdigitated electrodes (IDEs) for ss-DNA immobilization. TiO₂ thin film was deposited on P-type silicon dioxide (SiO₂) (1 0 0) substrates using monoethanolamine (MEA) sol-gel route by spin-coating method. Titanium butoxide was used as a precursor source while ethanol and MEA were used as a disperser and stabilizer respectively. Metal IDEs of aluminium (Al) was deposited on the synthesized films for the electrical characterization. From the electrical data, it proves that the synthesized TiO₂ thin film is effective and can be used for the synthesis of TiO₂ thin films with biomedical application.

Abstract: Titania or titanium dioxide (TiO₂) thin film has been synthesized via sol-gel method with monoethanolamine (MEA) as a catalyst. The mixing of titanium butoxide as a precursor, ethanol as a solvent and MEA were stirred using magnetic stirrer under ambient temperature [. The TiO₂ solution prepared then was deposited on SiO₂ substrates using spin-coater and the coated films were annealed at 600°C. Finally, both before and after annealed TiO₂ thin films were characterized using Field Emission Scanning Electron Microscopy (FESEM). The obtained results show the different TiO₂ particles formation before and after annealed.

Abstract: The preparation of activated carbon from wood-based industrys residue is one of the most environmental friendly solutions of transforming negative-valued wastes to valuable materials. Wood sawdust was first chemically activated using potassium hydroxide, KOH and characterized by nitrogen adsorption-desorption isotherms measured in Micrometrices ASAP 2020 and Field Emission Scanning Electron Microscope (FESEM). By manipulating three different parameters, the optimal activation conditions were found at temperature of 500°C, activation time of 60 min and impregnation ratio of 1:3. Results showed that the BET surface area, total pore volume and diameter of activated carbon were 1876.16 m² g^-1, 0.88 cm³ g^-1 and 6.93 nm, respectively. Nitrogen adsorption desorption isotherm analysis proved the existence of mesopores in activated carbon produced, suggesting that it can be effectively used as an adsorption material.

Abstract: High quality cuprous oxide thin films with large grain size were grown by thermal oxidation of copper foil in water vapor with N₂ gas. It was found that in water vapor (111) oriented Cu₂O is preferentially formed, whereas mixtures of random oriented CuO and Cu₂O are formed when oxidized in air. The effects of the film oxidation method and heating temperature are investigated. In addition, the optical band gaps of cuprous oxide thin films have been determined by measuring the transmittance and reflectance spectra.

Abstract: Palladium (Pd) nanoparticles offer excellent hydrogen affinity in mixed matrix membrane for gas separation. In order to avoid aggregation, Pd nanoparticles have to be stabilized before blending into polymer matrix. Pd nanoparticles can be thermodynamically stabilized and dispersed using electrostatic and/ or steric forces of a stabilizer which is typically introduced during the formation of Pd nanoparticles in the inversed microemulsion. Polyvinylpyrrolidone, polyethylene glycol (PEG) and sodium hydroxide in ethylene glycol exhibited good effect on particles passivation. However, the effects of these stabilizers on membrane morphology and separation performance were unknown. The aim of this work is to incorporate polymer-stabilized Pd nanoparticles into Polysulfone (PSf) membranes for hydrogen separation. The microstructure of Pd nanoparticles was first analyzed by TEM. Phase inversion method was then adopted for the preparation of asymmetric PSf/nanoPd MMMs. The separation performance of MMMs was investigated by using nitrogen and hydrogen as test gases and the membrane characteristics were further studied using SEM and FTIR. The highest permeability for H₂ was 255.82 GPU with selectivity of 6.89. The results suggested that PEG provides good contact between nanoparticles and the polymer. TEM and FTIR results revealed that these stabilizers have significant effects on the synthesized Pd nanoparticles size. Also, SEM results showed that the MMMs incorporated with thermodynamically nanoPd in PEG achieved satisfactory asymmetric structure which explains the good performance in gas separation.

Abstract: The source of fossil fuel is decreasing. The price increased rapidly. Population and demand of energy increased significantly over the years. Carbon pollution and global warming are becoming major issues. The best way to overcome this problem is by changing to renewable source of energy. One of it is solar thermal energy. However, a solar technology is currently still expensive, low in efficiency and takes up a lot of space. Nanofluid is recognized as a solution to overcome this problem. Due to the high thermal conductivity of nanofluids, the thermal efficiency of a solar collector can be increased and thus decreasing the size of the system. This paper analyzes the efficiency of using the Al₂O₃ nanofluid as absorbing medium in flat-plate solar collector and estimated the potential of size reduction. When applying the same output temperature of Al₂O₃ nanofluid as with water, it can be observed that the collectors size can be reduced up to 24% of its original size.

Abstract: Global warming and other problems can be reduced by effectively using the available materials and facilities. Heat exchangers play an important part of the field of energy conservation, conversion and recovery. Shell & tube heat exchangers are widely using in industrial processes and power plants. Suspension of small amounts of nanoparticles into the base fluid called nanofluid can reduce the global energy losses. Thermal conductivity of Multi Walled Carbon Nanotube (MWCNT) is highest among the different nano materials [1]. Therefore, in this paper, the overall performance of a shell & tube heat exchanger has been analytically investigated by using MWCNT-W nanofluid with 0.02-0.1 vol. fractions of MWCNT and compared with water. Mathematical formula, specifications of heat exchanger and nanofluid properties were taken from the literatures to analyze the energy performance and other effects within the system. It is found that for certain mass flow rates of nanofluid and base fluid, the convective heat transfer coefficient increased around 4% to 17% compared to pure water, respectively for 0.02-0.1 vol. fractions of MWCNT in water. However, for constant vol. fractions of MWCNT, convective heat transfer coefficient of the above nanofluid negligibly changed for different mass flow rates. Furthermore, energy effectiveness of the heat exchanger also improved approximately by 3% to 14%, respectively. This energy effectiveness again improved with the decrease of the mass flow rates of nanofluids (tube side) and increase of the mass flow rates of base fluid (shell side). As energy effectiveness is increased by using MWCNT-W nanofluid, therefore, a significant amount of heat losses will be reduced. As a result, with the reduced heat emissions, global warming and greenhouse effects can be reduced by using MWCNT-W nanofluid as working fluid in shell & tube heat exchanger system.

Abstract: Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al₂O₃/water, SiO₂/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al₂O₃/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO₂/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO₂/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.