Abstract: Titania nanotubes (TiO2 NTs) photoanodes were synthesized by anodization method. The electrolytes were the mixtures of ethylene glycol (EG), ammonium fluoride (0.3 wt % NH4F) and deionized water (2 Vol % H2O) with different concentrations of dopant Fe (NO3)3∙9H2O. A constant dc power supply at 50 V was used as anodic voltage. The samples were annealed at 450 °C for 2 hours. The resultant products were characterized by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) to determine their microstructure when TiO2 NTs were doped with different amounts of Fe atoms. The diameters of TiO2 NTs were about60-120 nm. The highest density of TiO2 NTs was obtained when the nanotubes were doped with 0.01 M of Fe.
Abstract: Silver nanoparticles was successfully synthesized by the exposure of silver nitrate solution to the high intensity ultraviolet source with an addition of poly (acrylic acid, sodium salt), (PAA) as the stabilizing agent. The silver nanoparticles were displayed a dark blue color which a maximum absorbance at 784 nm. The average size and surface charges of PAA stabilized silver nanoparticles at pH5 were 81.62 nm and-14.32 mV, respectively. Upon the addition of ammonia solution, the dark blue color of silver nanoparticles were changed to light green and yellow. The detection of ammonia concentration using PAA stabilized silver nanoparticles has been responded to 1-80 ppm. The PAA stabilized silver nanoparticles, blue solution are promising to be an alternative method for colorimetric detection of ammonia in environmental or industrial section.
-3-phenyl-propanoic acid (PDMS-BCPA) is a newly developed stereo-specific membrane that interacts with S configuration of enantiomers as chiral recognition sites. In this study, realization of PDMS-BCPA nanomembrane was achieved via anodized aluminum oxide (AAO) template synthesis approach followed by the attachment of synthesized chiral selector (BCPA) using simple immersion method. The effect of surface modification and the attachment with chiral selector were investigated and characterized using Fourier Transform Infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscopic (FE-SEM) and Atomic Force Microscopic (AFM) methods. The characterization via these methods indicates the synthesized BCPA as chiral selector was successfully attached onto the PDMS surface. The enantioselectivity of PDMS-BCPA nanomembrane was verified by the separation of alpha cypermethrin enantiomer.
Abstract: The coupled Finite Fracture Mechanics (FFM) criterion is applied to investigate brittle fracture in rounded V-notched samples under mode I loading. The approach is based on the contemporaneous fulfilment of a stress requirement and the energy balance, the latter being implemented on the basis of a recently proposed analytical expression for the stress intensity factor. Results are presented in terms of the critical crack advance and the apparent generalized fracture toughness, i.e. the unknowns related to the system of two equations describing the FFM criterion. A validation of the theory is performed by employing varying root radius notched, as-quenched, AISI 4340 steel specimens fracture results.
Abstract: In this paper, the evaluation of the SIFof a macrocrack in interaction with one or several microcracks in a material containing a geometrical defect was investigated. Several configurations were considered in order to apprehend the mechanisms induced by the interaction effect and in particular the effects of reduction and/or amplification of the stress field between macro and single or multiple microcracks. The obtained results show that, macro–microcrack spacing is an important parameter if the microscopic crack is relatively close to the macrocrack-tip. The macrocrack has the tendency to accelerate as it propagates towards the microcrack. When the relative distance characterizing this spacing is higher than 0.3, the interaction effect can be neglected and the SIF remains unchanged for both defect types. When this ratio is lower than 0.3, the interaction between the two defects becomes significant and the stress intensity factor at the macrocrack tip strongly increases.
Abstract: This research presents an experimental investigation on the heat transfer performance and pressure drop characteristics of a heat sink with miniature square pin fin structure using nanofluids as coolant. ZnO-water nanofluids with particle concentrations of 0.2, 0.4 and 0.6 vol.% are used as working fluid and then compared with the data for water-cooled heat sink. Heat sink made from aluminum material with dimension around 28 x 33 x 25 mm (width x length x thickness). The heat transfer area and hydraulic diameter of the each flow channel is designed at 1,565 mm2 and 1.2 mm respectively. Uniform heat flux at the bottom of heat sink is achieved using an electric heater. The experimental data illustrate that the thermal performance of heat sink using nanofluids as coolant is average 14% higher than that of the water-cooled heat sink. For pressure drop, the data show that the pressure drop of nanofluids is a few percent larger than that of the water-cooled heat sink.
Abstract: Double-layer heterogeneous photoresist method will be used firstly to obtain the round photoresist column with two layers of different photoresists. Since both photoresists are the positive-type, the exposure is only required once. During the thermal reflow processing, the upper photoresist layer (AZ-4620 and nanomagnetic powder mixture) reaches the glass transition temperature, which is transformed from a glassy state into a rubbery state. Since the glass transition temperature of the lower photoresist layer (AZ-5214E) is higher than the temperature of thermal reflow, the lower photoresist layer is still able to maintain its solid state. The lower layer creates a round base during the thermal reflow process, and then subjected to an appropriate magnetic field. The base can not only restrict the bottom shape of the liquid photoresist to a round shape but also prevent the sliding of liquid photoresist during the thermal reflow process, so the tilted microlens array can be obtained. We can vary the strength of magnetic field to control the oblique angle of the tilted microlens.
Abstract: Water-in-oil emulsions are formed during crude oil production. Some natural surfactants (asphaltenes) aggregates are known to form viscoelastic film preventing coalescence of emulsified water droplets. The present research work investigates the interfacial properties and demulsifying capacity of Janus type magnetic nanoparticles. poly (methylmethacrylate-acrylicacid-divinylbenzene) iron oxide Janus nanoparticles with Interfacially active P(MMA-AA-DVB) block copolymer and iron oxide (magnetic) shows excellent interfacial and magnetic properties. Experiments performed at the oil-water interface indicates that Janus particles adsorb at the oil - water interface and separate the emulsified water from the external magnetic field. The external magnetic play important role demulsification of magnetically tagged emulsified water droplets, producing smaller volumes of sludge and decrease the hydrocarbon loss to waste aqueous phase. The chemical bonding of interfacially active P(MMA-AA-DVB) grafted with magnetic nanoparticles and the magnetic property of P(MMA-AA-DVB)/Fe3O4 allowed the used Janus nanoparticles to be readily recycled by magnetic separation and regenerated by solvent washing.
Abstract: The main aim of this study was to investigate size-dependent effect on the photoelectrochemical properties of nanostructured tungsten trioxide (WO3) thin films synthesized via electrochemical method. Firstly, the nanostructured WO3 thin films of different crystalline sizes were synthesized on fluorine-doped tin oxide (FTO) glass working electrodes followed by controlled annealing treatment at temperature of 100-600°C. The resultant nanostructured WO3 thin films were further characterized using field emission-scanning electron microscopy (FE-SEM) and photocurrent density measurements. Through FE-SEM analysis, it was found that the WO3 crystalline size increases with increasing annealing temperature that resulted in elevated photocurrent per unit area of the synthesized nanostructured WO3 thin films. Finally, it was observed that the highest photocurrent density of up to 35μA/cm2 was attained for WO3 crystallines size of 86nm that formed at the annealing temperature of 600°C.
Abstract: Nitrogenated ultrananocrystalline diamond/hydrogenated amorphous carbon composite films were prepared in hydrogen and nitrogen mixed-gas atmospheres by pulsed laser deposition using graphite targets. The electrical conductivity in n-type conduction remarkably increase at room temperature with an increase in the nitrogen content. In the nitrogen content range from 7.9 to 10.4 at.%, the electrical conductivity is dramatically decreased and this accompanied by the disappearance of diamond grains in the films. Grain boundaries owing to the existence of diamond grains embedded in UNCD/a-C:H films, which is structural specific to UNCD/a-C:H, should play a significant role in the large electrical conductivity enhancement by nitrogen doping. The X-ray photoemission and near-edge X-ray fine-absorption spectroscopic measurements could not detect an evident difference in the spectra that explain the sudden irregular change in the electrical conductivity