Studies into Laser Ignition of Unconfined Propellants

Prior to laser ignition tests, spectral absorption properties of three different solid motor propellants were analysed. The extruded double base (EDB) propellant exhibited >95 % absorption over the 250–550 nm wavelength band whereas, the cast double base (CDB) showed similar absorption over a wider band extending between 375–800 nm. The composite sample (CP) showed a uniform spectral absorption at about 90 % over 250–800 nm band. Ignition tests using an average of 500 nm output from an Ar‐ion laser showed that the double base propellants undergo deflagration prior to ignition due to the presence of carbon black material. Within the laser power density range of 24–125 Wċcm⁻², the threshold laser energy densities for deflagration and ignition in the double base propellant were found to␣be between 2–2.5 Jċcm⁻², and 40–215 Jċcm⁻², respectively. No deflagration was observed for the composite propellant, and the threshold ignition energy was found to be within the range, 11–18 Jċcm⁻² for the same range of laser power densities. From the ignition map for this propellant, the threshold energy for ignition at this wavelength was found to be approximately 18 Jċcm⁻² and was practically independent of laser power density. In the near infrared wavelength (780 nm) the EDB propellant was not readily ignitable due to its comparatively much higher reflectance at this wavelength. The ignition threshold values were found to be between 19–23 Jċcm⁻² for a similar power density level. The results indicate that the ignitability of propellants is enhanced through the promotion of deflagration.     

Radiation modelling and performance evaluations of fixed,single- and double-axis tracking surfaces: a case study for Dhahran city,Saudi Arabia

This work overviews the solar radiation basics and insolation of different surfaces is presented. A complete solar radiation modelling and investigation on the effect of horizontal plate, yearly tilt, monthly tilt, and single-axis and double-axis tracking surface on the insolation are carried out to conduct performance evaluation using the case study in Dhahran city of Saudi Arabia. The increments received by insolation for the yearly tilt, monthly tilt, and single-axis and dual-axis tracking surface with respect to traditional flat-plate collector is estimated. The results show that the yearly optimal tilt angle due to the south is close to the 0.913 time latitude of Dhahran. It is found that the yearly irradiation gains using yearly and monthly optimal tilts relative to flat panel installation are 7% and 14%, respectively. The yearly insulation gains made by single-axis and dual-axis continuous tracking surfaces are 33% and 48%, respectively.     

Assessment of immobilized cell reactor and microbial fuel cell for simultaneous cheese whey treatment and lactic acid/electricity production

Two biological methods for treatment of cheese whey and concentrated cheese whey were investigated in this research. As the first method, fermentation of cheese whey for production of lactic acid, in an immobilized cell reactor (ICR) was successfully carried out. The immobilisation of Lactobacillus bulgaricus was performed by the enriched cells cultured media harvested at exponential growth phase. Furthermore, the FTIR analysis has been done to prove the production of lactic acid. The COD removal during the continuous process for both whey and concentrated whey was above 70% which showed the capability of reaction for wastewater treatment. The cells were immobilised by sodium alginate as a perfect polymer in this regard. The maximum produced lactic acid from whey was 10.7 g l^?1 at 0.125 h^?1 and 19.5 g l^?1 from concentrated whey at 0.063 h^?1. Finally it can be concluded that the process is efficient for lactic acid production and COD removal simultaneously. As the second studied method, whey and concentrated cheese whey were used as the sources of carbon in a microbial fuel cell. The power densities of 188.8 and 288.12 mW m^?2 were recorded for whey-fed and concentrated whey-fed MFCs while the COD removal were 95% and 86% respectively. Biological wastewater treatment can be a very efficient alternative for traditional wastewater treatment which selecting any and or integrating of them depends on specific applications needed to be achieved.     

Co-extruded dual-layer hollow fiber with different electrolyte structure for a high temperature micro-tubular solid oxide fuel cell

In this study, the phase inversion-based co-extrusion method was employed to fabricate a structural-improved electrolyte/anode dual-layer hollow fiber (HF) precursor, which was then co-sintered at 1450 °C. The electrolyte structures were thoroughly investigated by varying the loading of electrolyte material (i.e. Yttria-stabilized zirconia, YSZ) with differing particle sizes (i.e. micron, sub-micron, and nano-sized) during suspension preparation. The results showed that the most promising electrolyte layer with thin, dense, gas-tight, and defect-free properties was obtained by mixing 70% submicron-YSZ and 30% nano-YSZ in electrolyte suspension (E-0.7sub0.3nano). This electrolyte formulation co-extruded with a thick nickel-oxide-YSZ (NiO-YSZ) anode layer yielded the highest bending strength of 85 MPa, providing major mechanical strength to the HF. Besides that, the nitrogen permeability value at 2.87 × 10^?6 mol m^?2 s^?1 Pa^?1 suggested that the electrolyte was gas-tight, preventing fuel and oxidant transport. The fiber was then reduced to nickel (Ni)-cermet anode. It was developed to be a complete micro-tubular solid oxide fuel cell (MT-SOFC) by depositing the lanthanum strontium cobalt ferrite (LSCF)/YSZ cathode via brush painting on the dual-layer HF. The cell was fed with hydrogen gas and yielded an open-circuit voltage (OCV) as high as 1.06 V with maximum power density of 0.243 W cm^?2, at 875 °C. Based on this test, it was found that the electrolyte structural-modified dual-layer hollow fiber-based MT-SOFC using mixed particle sizes may result in a promising OCV. However, the relatively low value for power density may be due to a less porous anode; thus, improvements in the anode's structure are required in future research.     

Biohydrogen production from Imperata cylindrica bio-oil using non-stoichiometric and thermodynamic model

This paper presents a non-stoichiometric and thermodynamic model for steam reforming of Imperata cylindrica bio-oil for biohydrogen production. Thermodynamic analyses of major bio-oil components such as formic acid, propanoic acid, oleic acid, hexadecanoic acid and octanol produced from fast pyrolysis of I. cylindrica was examined. Sensitivity analyses of the operating conditions; temperature (100–1000 °C), pressure (1–10 atm) and steam to fuel ratio (1–10) were determined. The results showed an increase in biohydrogen yield with increasing temperature although the effect of pressure was negligible. Furthermore, increase in steam to fuel ratio favoured biohydrogen production. Maximum yield of 60 ± 10% at 500–810 °C temperature range and steam to fuel ratio 5–9 was obtained for formic acid, propanoic acid and octanol. The heavier components hexadecanoic and oleic acid maximum hydrogen yield are 40% (740 °C and S/F = 9) and 43% (810 °C and S/F = 8) respectively. However, the effect of pressure on biohydrogen yield at the selected reforming temperatures was negligible. Overall, the results of the study demonstrate that the non-stoichiometry and thermodynamic model can successfully predict biohydrogen yield as well as the composition of gas mixtures from the gasification and steam reforming of bio-oil from biomass resources. This will serve as a useful guide for further experimental works and process development.     

Modelling and simulation of Proton Exchange Membrane fuel cell with serpentine bipolar plate using MATLAB

This report presents experimental results derived from a Proton Exchange Membrane fuel cell with a serpentine flow plate design. The investigation seeks to explore the effects of some parameters like cell operational temperature, humidification and atmospheric pressure on the general performance and efficiency of PEM fuel cell using MATLAB. A number of codes were written to generate the polarization curve for a single stack and five (5) cell stack fuel cell at various operating conditions. Detailed information of hydrogen and oxygen consumption and the effect they have on the fuel cell performance were critically analysed. The investigation concluded that the open circuit voltage generated was less than the theoretical voltage predicted in the literature. It was also noticed that an increase in current or current density reduced the voltage derived from the fuel cell stack. The experiment also clearly confirmed that when more current is being drawn from the fuel cell, more water will also be generated at the cathode section of the cell hence the need for an effective water management to improve the performance of the fuel cell. Other parameters like the stack efficiency and power density were also analysed using the experimental results obtained.     

Green Synthesis of Silver Nanoparticles Using Olea europaea Leaf Extract for Their Enhanced Antibacterial,Antioxidant, Cytotoxic and Biocompatibility Applications

Herein, we report the green synthesis of silver nanoparticles (OE-Ag NPs) by ecofriendly green processes using biological molecules of Olea europaea leaf extract. Green synthesized OE-Ag NPs were successfully characterized using different spectroscopic techniques. Antibacterial activity of OE-Ag NPs was assessed against four different bacteriological strains using the dilution serial method. The cytotoxic potential was determined against MCF-7 carcinoma cells using MTT assay in terms of cell viability percentage. Antioxidant properties were evaluated in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging. Biocompatibility was further examined by incubating the synthesized NPs with hMSC cells for 24 h. The results were demonstrated that synthesized OE-Ag NPs presented excellent log₁₀ reduction in the growth of all the tested bacterial strains, which as statistically equivalent (p > 0.05) to the standard antibiotic drug. Moreover, they also demonstrated excellent cytotoxic efficacy against the MCF-7 carcinoma cells compared to plant lead extract and Com-Ag NPs. Green synthesized OE-Ag NPs appeared more biocompatible to hMSC and 293T cells compared to Com-Ag NPs. Excellent biological results of the OE-Ag NPs might be attributed to the synergetic effect of NPs’ properties and the adsorbed secondary metabolites of plant leaf extract. Hence, this study suggests that synthesized OE-Ag NPs can be a potential contender for their various biological and nutraceutical applications. Moreover, this study will open a new avenue to produce biocompatible nanoparticles with additional biological functionalities from the plants.     

Embedding Pyramids into 3D Meshes

The pyramid architecture is a powerful topology in the area of computer vision. On the other hand, the 3D mesh architecture possesses rich topological features which make it suitable for building scalable parallel processor systems. The usefulness of these two architectures has led us to consider the problem of embedding pyramids into 3D meshes, for which we present two solutions. The first solution, termednatural embedding,maps a pyramid into a 3D mesh such that each level of the pyramid is mapped to a single level of the 3D mesh. The second solution, termedmultiple embedding,allows simultaneous embedding of multiple pyramids into a single 3D mesh. The quality of both solutions is evaluated using dilation and expansion measures. Using the multiple embedding, we are able to obtain an average dilation of 1.26 and a near-optimal expansion of 1.12.     

Development and Evaluation of Repurposed Etoricoxib Loaded Nanoemulsion for Improving Anticancer Activities against Lung Cancer Cells

In the present work, novel modality for lung cancer intervention has been explored. Primary literature has established the potential role of cyclooxygenase-2 (COX-2) inhibitor in regression of multiple forms of carcinomas. To overcome its poor water solubility and boost anticancer activity, etoricoxib (ETO) was chosen as a therapeutic candidate for repurposing and formulated into a nanoemulsion (NE). The prepared ETO loaded NE was characterized for the surface charge, droplet size, surface morphology, and in vitro release. The optimized ETO loaded NE was then investigated for its anticancer potential employing A549 lung cancer cell line via cytotoxicity, apoptotic activity, mitochondrial membrane potential activity, cell migration assay, cell cycle analysis, Caspase-3, 9, and p53 activity by ELISA and molecular biomarker analysis through RT-PCR test. The developed ETO-NE formulation showed adequate homogeneity in the droplet size distribution with polydispersity index (PDI) of (0.2 ± 0.03) and had the lowest possible droplet size (124 ± 2.91 nm) and optimal negative surface charge (−8.19 ± 1.51 mV) indicative of colloidal stability. The MTT assay results demonstrated that ETO-NE exhibited substantial anticancer activity compared to the free drug. The ETO-NE showed a substantially potent cytotoxic effect against lung cancer cells, as was evident from the commencement of apoptosis/necrotic cell death and S-phase cell cycle arrests in A549 cells. The study on these molecules through RT-PCR confirmed that ETO-NE is significantly efficacious in mitigating the abundance of IL-B, IL-6, TNF, COX-2, and NF-kB as compared to the free ETO and control group. The current study demonstrates that ETO-NE represents a feasible approach that could provide clinical benefits for lung cancer patients in the future.     

A comprehensive review of renewable energy resources for electricity generation in Australia

Recently, renewable energy resources and their impacts have sparked a heated debate to resolve the Australian energy crisis. There are many projects launched throughout the country to improve network security and reliability. This paper aims to review the current status of different renewable energy resources along with their impacts on society and the environment. Besides, it provides for the first time the statistics of the documents published in the field of renewable energy in Australia. The statistics include information such as the rate of papers published, possible journals for finding relative paper, types of documents published, top authors, and the most prevalent keywords in the field of renewable energy in Australia. It will focus on solar, wind, biomass, geothermal and hydropower technologies and will investigate the social and environmental impacts of these technologies.