We report on a process for fabricating self-aligned tungsten (W) nanowires with polycrystalline silicon core. Tungsten nanowires as thin as 10 nm were formed by utilizing polysilicon sidewall transfer technology followed by selective deposition of tungsten by chemical vapor deposition (CVD) using WF6 as the precursor. With selective CVD, the process is self-limiting whereby the tungsten formation is confined to the polysilicon regions; hence, the nanowires are formed without the need for lithography or for additional processing. The fabricated tungsten nanowires were observed to be perfectly aligned, showing 100% selectivity to polysilicon and can be made to be electrically isolated from one another. The electrical conductivity of the nanowires was characterized to determine the effect of its physical dimensions. The conductivity for the tungsten nanowires were found to be 40% higher when compared to doped polysilicon nanowires of similar dimensions.
The electrical resistivity and flexural strength of plastic composites reinforced with pineapple leaf particles (PCPLP) is presented. PCPLP were produced using different plastic materials; Polyethylene (PE) and Polypropylene (PP), and different plastic pineapple leaf particle ratios; 50:50 and 70:30. The PCPLP were tested and evaluated with respect to electrical resistivity and flexural strength according to ASTM D257 and D790, respectively. The results indicate that PCPLP made from PP exhibits better electrical resistance than PE, which may be attributed to the better frequency insulation behaviour ofPP. PCPLP using the higher ratio of 70:30 also exhibited better electrical resistance than the lower 50:50 ratio. Cellulose materials inherently influence the electrical resistance of plastic composites, due to their natural propensity to absorb moisture. The PCPLP produced using a ratio of 50:50 for both PP and PE composites exhibited better MOE results than the 70:30 composites, however the converse is true with respect to the MOR. MOE of PCPLP was increased with increasing pineapple leaf particles content due to the greater matrix stiffness of this natural particle with respect to plastic matrix. However, high percentage offiller particles in the matrix (70:30 ratio) has reduced the toughness in the composite structure due to the lost ofphysical contact between high accumulated particles.
Vegetable oil has become more attractive recently because of its environmental benefits and better
quality exhaust emission. A well-known transesterification process made biodiesel, pungam seed oil was selected for biodiesel production. Pungam seed oil is non-edible oil, thus, food versus fuel conflict will not arise if this is used for biodiesel production. A maximum of 75% biodiesel was produced with 20% methanol in the presence of 0.5% sodium hydroxide. The experimental investigations were carried out in an engine that is coupled with an eddy current dynamometer. The engine is a single cylinder water-cooled, direct injection diesel engine developing a power output of 3.7 kW at 1500 rev/min. The crank angle encoder measured the engine speed, whereas the piezo electric sensors measured the cylinder pressure and the fuel injection pressure. The experimental investigations were carried out for bio-diesel and diesel and the results were compared. From the experimental results, it is concluded that the use of bio-diesel as an alternative fuel leads to significant reduction in emissions and improved performance of diesel engines. This paper discusses the production process of biodiesel from Pungam seed oil and its performance in the compression ignition engine.
A steady two-dimensional magnetohydrodynamic (MHD) stagnation-point flow of a viscous and electrically conducting fluid over a permeable shrinking sheet has been studied. The governing partial differential equations are reduced to the nonlinear ordinary differential equations by a similarity transformation. The resulting differential equations are then solved numerically using an implicit finite difference method. It is found that the solutions are non-unique for weak magnetic field, strong suction and large velocity ratio between free stream velocity and wall shrinking velocity.
In this research we investigated the effect of composition on the fabrication and morphological characteristics of a hybrid polymeric solar cell which consists of an electron donating conjugated polymer, namely is poly(3-hexylthiophene) (P3HT) combined with an electron-accepting component, which is a type of inorganic compound of TiO2 nanocrystals. The composition of TiO2 in the blends is varied and the optimum performance of the devices are studied. The optical and morphological characterizations are carried out via UV-Visible absorption spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The electrical characteristics of the devices are measured by using Keithley 2400 SMU and solar simulator with light intensity of 100 mW/cm2.
Fossil fuels (petroleum, natural gas and coal) are the main resources for generating electricity. However, they have been major contributors to environmental problems. One potential alternative to explore is the use of microbial fuel cells (MFCs), which generate electricity using microorganisms. MFCs uses catalytic reactions activated by microorganisms to convert energy preserved in the chemical bonds between organic molecules into electrical energy. MFC has the ability to generate electricity during the wastewater treatment process while simultaneously treating the pollutants. This study investigated the potential of using different types of mixed cultures (raw sewage, mixed liquor from the aeration tank & return waste activated sludge) from an activated sludge treatment plant in MFCs for electricity generation and pollutant removals (COD & total kjeldahl nitrogen, TKN). The MFC in this study was designed as a dual-chambered system, in which the chambers were separated by a NafionTM membrane using a mixed culture of wastewater as a biocatalyst. The maximum power density generated using activated sludge was 9.053 mW/cm2, with 26.8% COD removal and 40% TKN removal. It is demonstrated that MFC offers great potential to optimize power generation using mixed cultures of wastewater.
To reduce undesirable charging effects in scanning electron microscope images, Rayleigh contrast stretching is developed and employed. First, re-scaling is performed on the input image histograms with Rayleigh algorithm. Then, contrast stretching or contrast adjustment is implemented to improve the images while reducing the contrast charging artifacts. This technique has been compared to some existing histogram equalization (HE) extension techniques: recursive sub-image HE, contrast stretching dynamic HE, multipeak HE and recursive mean separate HE. Other post processing methods, such as wavelet approach, spatial filtering, and exponential contrast stretching, are compared as well. Overall, the proposed method produces better image compensation in reducing charging artifacts.
Inactivation constant for V79 cells has been extracted from radiobiology experiments that utilize charged particles to irradiate mammal cells in vitro. Physical parameters such as effective charge, radiation mean free path and linear ionization which characterized protons and heluim-4 particles are determined using of standard values. The relationship between inactivation constant α and physical quality parameters have been determined, in this research, for protons and heluim-4 particles. This approach allows getting the characteristic biological response of inactivation of V79 cells in terms of each selected physical quality parameter. The best regression models are formulated for each obtained relationship.
Porous silicon (PSi) layers were formed on a p-type Si wafer. Six samples were anodised electrically with a 30 mA/cm² fixed current density for different etching times. The samples were coated with a 50-60 nm gold layer and annealed at different temperatures under Ar flow. The morphology of the layers, before and after annealing, formed by this method was investigated by scanning electron microscopy (SEM). Photoacoustic spectroscopy (PAS) measurements were carried out to measure the thermal diffusivity (TD) of the PSi and Au/PSi samples. For the Au/PSi samples, the thermal diffusivity was measured before and after annealing to study the effect of annealing. Also to study the aging effect, a comparison was made between freshly annealed samples and samples 30 days after annealing.
The feasibility of preparing activated carbon (JPAC) from jackfruit peel, an industrial residue abundantly available from food manufacturing plants via microwave-assisted NaOH activation was explored. The influences of chemical impregnation ratio, microwave power and radiation time on the properties of activated carbon were investigated. JPAC was examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption isotherm, elemental analysis, surface acidity/basicity and zeta potential measurements. The adsorptive behavior of JPAC was quantified using methylene blue as model dye compound. The best conditions resulted in JPAC with a monolayer adsorption capacity of 400.06 mg/g and carbon yield of 80.82%. The adsorption data was best fitted to the pseudo-second-order equation, while the adsorption mechanism was well described by the intraparticle diffusion model. The findings revealed the versatility of jackfruit peels as good precursor for preparation of high quality activated carbon.
Different biological methods are gaining recognition for the production of silver nanoparticles (Ag-NPs) due to their multiple applications. The use of plants in the green synthesis of nanoparticles emerges as a cost effective and eco-friendly approach. In this study the green biosynthesis of silver nanoparticles using Callicarpa maingayi stem bark extract has been reported. Characterizations of nanoparticles were done using different methods, which include; ultraviolet-visible spectroscopy (UV-Vis), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence (EDXF) spectrometry, zeta potential measurements and Fourier transform infrared (FT-IR) spectroscopy. UV-visible spectrum of the aqueous medium containing silver nanoparticles showed absorption peak at around 456 nm. The TEM study showed that mean diameter and standard deviation for the formation of silver nanoparticles were 12.40 ± 3.27 nm. The XRD study showed that the particles are crystalline in nature, with a face centered cubic (fcc) structure. The most needed outcome of this work will be the development of value added products from Callicarpa maingayi for biomedical and nanotechnology based industries.
This study aimed at utilizing electroporation to further enhance the growth of lactobacilli and their isoflavone bioconversion activities in biotin-supplemented soymilk. Strains of lactobacilli were treated with different pulsed electric field strength (2.5, 5.0 and 7.5 kV/cm) for 3, 3.5 and 4 ms prior to inoculation and fermentation in biotin-soymilk at 37°C for 24 h. Electroporation triggered structural changes within the cellular membrane of lactobacilli that caused lipid peroxidation (p 9 log CFU/ml after fermentation in biotin-soymilk (p
This paper addresses the growth of nano-structured MgZnO thin films by sol-gel spin coating method which will be used as a template layer to grow carbon nanotubes. The nano-structured MgZnO films were deposited on platinized (100) silicon substrates. In this work, we focused on the effect of aging and Mg content on the film structure and resistivity. Sols with Mg content of 10, 30 and 50 at.% were subjected to aging times of between 3 to 240 hours. Results from scanning (SEM) and field emission scanning electron (FESEM) microscopes and surface profiler (SP) showed that the sol aging increased the thickness, grain size and surface roughness for aging up to 240 hours. The energy dispersive analysis by X-ray (EDAX) confirmed the element of Mg in the ZnO films. The electrical resistivity also increased with aging time as confirmed by four point probe method. The results suggest that appropriate aging of the sol is important for improving physical quality and electrical performance of MgZnO thin films derived from sol-gel technique.
Electromagnetic (EM) waves transmitted by Horizontal Electric Dipole (HED) source to detect contrasts in subsurface resistivity termed Seabed Logging (SBL) is now an established method for hydrocarbon exploration. However, currently used EM wave detectors for SBL have several challenges including the sensitivity and its bulk size. This work exploits the benefit of superconductor technology in developing a magnetometer termed Superconducting Quantum Interference Device (SQUID) which can potentially be used for SBL. A SQUID magnetometer was fabricated using hexagon shape-niobium wire with YBa2Cu37O, (YBCO) as a barrier. The YBa2Cu37O, samples were synthesized by sol-gel method and were sintered using a furnace and conventional microwave oven. The YBCO gel was dried at 120 degrees C in air for 72 hours. It was then ground and divided into 12 parts. Four samples were sintered at 750 degrees C, 850 degrees C, 900 degrees C, and 950 degrees C for 12 hours in a furnace to find the optimum temperature. The other eight samples were sintered in a microwave with 1100 Watt (W) with a different sintering time, 5, 15, 45 minutes, 1 hour, 1 hour 15 minutes, 1 hour 30 minutes, 1 hour 45 minutes and 2 hours. A DEWAR container was designed and fabricated using fiberglass material. It was filled with liquid nitrogen (LN2) to ensure the superconducting state of the magnetometer. XRD results showed that the optimum sintering temperature for the formation of orthorhombic Y-123 phase was at 950 degrees C with the crystallite size of 67 nm. The morphology results from Field Emission Scanning Electron Microscopy (FESEM) showed that the grains had formed a rod shape with an average diameter of 60 nm. The fabricated SQUID magnetometer was able to show an increment of approximately 249% in the intensity of the EM waves when the source receiver offset was one meter apart.
Transparent nanostructured ZnO thin films were successfully deposited using sol-gel spin coating method on a quartz substrate. The 0.4 M ZnO solution gel was prepared using zinc acetate dihydrate (Zn(CH3COO)22H2O) as the precursor, 2-methoxyethanol as the solvent and monoethanolamine (MEA) as the stabilizer. The electrical and optical properties dependencies on the annealing temperature of the nanostructured ZnO thin films were investigated. It was found that as the annealing temperature increased, the particle size, conductivity and the peak of the UV emission also increased.
This paper describes how to employ distributed clock gating to achieve an overall low power design of a programmable waveform generator intended for a neural stimulator. The power efficiency is enabled using global timing control combined with local amplitude distribution over a bus to the local stimulator frontends. This allows the combination of local and global clock gating for complete sub-blocks of the design. A counter and a shifter employed at the local digital stimulator reduce the design complexity for the waveform generation and thus the overall power consumptions. The average power results indicate that 63% power can be saved for the global stimulator control unit and 89-96% power can be saved for the local digital stimulator by using the proposed approach. The circuit has been implemented and successfully tested in a 0.35 µm AMS HVCMOS technology.
In industrial plants such as electricity generating, petroleum, chemical and petrochemical plants, pipelines are used extensively to transport liquid from one location to another. In radiation vulcanization of natural rubber latex (RVNRL) plants, pipelines are also used to transport latex to storage tank. During one of its maintenance activities, a pipeline intelligent gauge (PIG) that was used to monitor pipe integrity jammed inside the pipe causing interruption to its operation or loading activities. Sealed source technology was utilized to determine the location of jammed PIG in the pipeline. Fast neutrons from a 50 mCi Americium Beryllium (AmBe241), with energy range between 0.5 to11 MeV, were used for the study. Helium 3 (He3) detector was used to detect slow neutrons having a range of energy of 30 eV- 0.5 MeV. The investigation was carried out using neutron backscatter technique scanner. By adopting back-scattered technique, the location of jammed PIG in the pipeline has been successfully determined.
In this study, the rice husk flour-plastic waste composites (RPC) was produced from polypropylene (PP) and high density polyethylene (HDPE) wastes with 30 and 50% rice husk flour (RHF) contents. RPC was made by melt compounding and compression moulding processes. The electrical resistivity, thermal stability and tensile strength of RPC were determined. The RPC was tested in electrical resistivity and tensile strength according to the ASTM D-257 and ASTM D-638 respectively, while thermal stability was tested using thermogravimetric analysis (TGA) method. From the results, high content of RHF reduces all properties, except for tensile modulus of elasticity (TMOE) in tensile strength test. The ability of moisture absorption and the presence of hemicelluloses, cellulose and silica in RHF reduce the electrical resistivity and thermal stability behaviour of RPC from 50% RHF. The good binding elements and filler agglomeration in RPC from 50% RHF improve only TMOE. Insufficient stress transfer and rigid interphase occurred between RHF and plastics during tensile maximum load and elongation at break (Eb) in tensile strength test. In general, RPC from HDPE indicates better thermal stability, tensile modulus of rupture and Eb (in tensile strength test) compared to PP, based on the good behaviour of thermal conductivity, low water absorption, high molecular weight and good elongation properties of HDPE. However, RPC from PP shows good electrical resistance due to the low thermal expansion coefficient of PP.
Industrial heat pumps are heat-recovery systems that allow the temperature of waste-heat stream to be increased to a higher, more efficient temperature. Consequently, heat pumps can improve energy efficiency in industrial processes as well as energy savings when conventional passive-heat recovery is not possible. In this paper, possible ways of saving energy in the chemical industry are considered, the objective is to reduce the primary energy (such as coal) consumption of power plant. Particularly the thermodynamic analyses of integrating backpressure turbine of a power plant with distillation units have been considered. Some practical examples such as conventional distillation unit and heat pump are used as a means of reducing primary energy consumption with tangible indications of energy savings. The heat pump distillation is operated via electrical power from the power plant. The exergy efficiency of the primary fuel is calculated for different operating range of the heat pump distillation. This is then compared with a conventional distillation unit that depends on saturated steam from a power plant as the source of energy. The results obtained show that heat pump distillation is an economic way to save energy if the temperature difference between the overhead and the bottom is small. Based on the result, the energy saved by the application of a heat pump distillation is improved compared to conventional distillation unit.
The paper focused on the examination and testing of local exhaust ventilation (LEV) systems at one of Electrical Company to check the transport velocity whether it meet the recommended American Governmental Industrial Hygienist (ACGIH) Standard. The industrial hygiene approaches, AREC (Anticipating, Recognize, Evaluate and Control) were adopted in this study. This is to ensure that the LEV system installed has the optimum efficiency to extract out the contaminants from the workstation. Objective of this study is to make comparison with previous and current monitoring data. The efficiency and the other parameter measured will be the main source to analyze for the particular applications. The differential of data was discussed and several recommendations are proposed to make sure the LEV system performance is excellent.