Journal of Modern Materials
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Removal of Heavy Metals from Stormwater Using Porous Concrete Pavement
No full textThis study aimed to investigate the heavy metals, i.e. Cu, Pb, Ni, and Zn removal efficiency from stormwater runoff of a porous concrete pavement (PCP). A model of PCP was designed with the porosity and co-efficient of permeability of the pavement were 27.2% and 1.83 cm/sec, respectively. Artificial stormwater containing heavy metals are passed through the pavement at a constant rainfall rate to mimic the stormwater rainfall-runoff condition. The artificial stormwater infiltrated through the pavement were then collected at two different pavement layers at different time instances. From the experimental investigations, it is observed that Cu, Pb, Ni and Zn concentrations are significantly reduced in the treated stormwater. At the first collection point which is located below the sub-base layer and coarse sand layer of the pavement, the concentrations of Cu, Pb and Zn reduced 56%, 67% and 93% respectively compared to their initial concentration, Ni concentration reduced only 20%. At the second collection point which is located below the coarse and fine sand layers beneath the pavement, the concentrations of Cu, Pb, Zn, and Ni are reduced 92%, 89%, 100%, 100%, respectively
Investigation of Failure Criteria and Experimental Process of the Composite Specimen with Mechanical Joints under Tensile Loading
No full textGenerally, composite materials are used to obtain better engineering properties, including higher hardness, greater strength, lower weight, heat resistance, moisture and corrosion, which are not present in homogeneous materials such as metals, which are more commonly used in composite design. In this article, experimental study of the composite specimen with mechanical joints under tensile loading, joints of composite material structures, failure criteria in composite materials, tensile impact test is investigated. The results of research work it shows that maximum strength, the hand lay-up can be designed with [0º, 45º, 90º, -45º] s and layers with 45º fibers is very important, because these fibers in these layers have a significant role in increasing the resistance of the piecework under shear stresses due to the passage of stress lines along the hole; In other words, the maximum cut occurs at a 45º angle, and these layers resist this shear stress
Effect of Gamma- Irradiation on Structure, Morphology and Thermal Properties of Novel Polyamide Based Thermoset Obtained by Double Cycloaddition
No full textCycloaddition reactions gained prominence in macromolecular chemistry for generating macromolecules because of high yields of these reactions, which is a key tool that drives polyaddition reactions. Cycloaddition reaction plays major role in extension of polymerisation or in other words high conversions of monomers to macromolecules of high molecular weights. Until the late 1990s, the major studies regarding cycloadditions in novel polymer synthesis were related to polyaddition reactions. Since then in the field of polymer synthesis the affirmative strengths of these cycloaddition reactions have been exhibited in multi fold polymer design and headway material architecture. Future demand exists in unlatching the capacity of these novel synthetic routes for advanced applications in catalysis, separation, optoelectronics, and analytical media. Thus, we have developed an able and productive synthetic podium for the preparation of a new class of polyimide based on the double 1, 3-dipolar cycloaddition of thiasydnone with bis-maleimide. This paper reports the effect of gamma irradiation on the changes in physico-chemical properties of the polyamide based thermoset synthesised by double cycloaddition approach. The thermoset synthesized by this exclusive approach were irradiated with gamma doses in the range 10- 300 kGy. The substantial effect of gamma radiation and the structural modifications induced on the thermoset have been studied as a function of dose using different characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry- thermo gravimetric analysis (DSC-TGA), Field Emission Scanning Electron Microscope (FESEM) and UV-Vis Spectroscopy
A Review of Alternative Building Materials for Sustainable Construction Towards Sustainable Development
No full textThe study reviewed Alternative Building Materials for sustainable construction towards sustainable development. The study was able to identify some Alternative Building Materials, their features, classes (types), and importance for sustainable construction toward sustainable development. The study uses a systematic literature review and content analysis. Some of the Alternative Building Materials include laterite soil, brick wastes, rice husk ash burnt refuse ash, fly ash, periwinkle shell powder, earthworm cast, pulverized burned clay, periwinkle shell aggregate, tubali, earth/mud blocks or bricks, laterite blocks, bamboo for roofing & ceiling, palm front roofing, clay/mud plaster. The classes of the Alternative Building Materials include: modified conventional industrial materials, unconventional/ indigenous/ traditional materials, and modified unconventional/traditional indigenous materials. The features of sustainable construction materials include recyclability, insulation and thermal conductivity and deconstruct ability, availability, manufacturing and price, flexibility and high life time expectancy. The importance of Alternative Building Materials includes: the protection of the environment through reduce energy use and also cutting down CO2 emission, provision of affordable housing, energy conservation, meeting increasing demands for housing stock, provision of employment opportunities, the development and propagation of indigenous technological ingenuity and skills of our local people. The study advocates for the integration of the entire stakeholders in the construction industry towards utilisation of Alternative Building Materials for sustainable construction towards sustainable development. The study also advocates for the cataloguing of all Alternative Building Materials so as to create awareness to all the potential clients and stakeholders of the industry regarding their availability and importance
Analysis of Solar PV Energy Systems for Rural Villages of Nekemte Area, Oromiya Region, Ethiopia
No full textCurrently, the main energy source used in rural areas of Ethiopia for cooking and heating is unprocessed biomass and fossil fuel such as kerosene, paraffin and petrol/diesel. These energy sources generate large volume of indoor air pollution that increases the risk of chronic diseases. Solar energy is the most practical and economical way of bringing power to poor and remote communities in the long-term and Ethiopia is strategically located in a maximum sun shines hours zone. This study assessed the potential of a solar PV power system to provide the required electricity for a rural community near Nekemte city in Oromiya regions of Ethiopia. The sunshine hour’s data was obtained from the National Meteorological Service Agency (NMA). Results showed an abundant (average) solar energy potential of 5.52 KWh/m2/day. Electric load for a single household, school and clinic was estimated at 313, 2064 and 2040 Wh/day respectively. The cost of energy from solar PV system was estimated at about 0.92/kWh and $0.87/KWh for household, school and clinic respectively. The findings encourage the use of the PV systems to electrify the remote sites of Ethiopia considering it long-term benefits and less cost of installation compared to national grid extension to the remote sites
Influence of Strontium on the Physical, Mechanical and In-Vitro Bioactivity of Glass Ionomer Cements
No full textIn this work, we investigated the effects of strontium incorporation in the glass phase of glass ionomer cements (GIC). Three different glass compositions were synthesized with 0, 5, and 10 mol% of SrO addition. GICs were prepared by the addition of 50 wt% polyacrylic acid (PAA) at powder to liquid ratio of 1:1.5. Initial characterization on the cement series was to study their rheological behavior. Cements represented working times between 50-64 seconds and setting times of 356-452 seconds. Rheological results indicated that the addition of strontium decreases the working and setting times of the cements. To analyze the mechanical properties, compressive and flexural strength studies were performed after 1, 10, and 30 days incubation in simulated body fluid (SBF). The compressive strength of the cements increased as a function of incubation time, with the strontium containing compositions showing the highest strength at 34 megapascal (MPa) and after 30 days of incubation. Biaxial flexural strength of the cements was not significantly affected by the composition and maturation time and ranged between 13.4 to 16.3 MPa. In-vitro bioactivity of the cements was analyzed using SBF trials and after 1, 10, and 30 days incubation periods. Strontium containing cements, showed higher solubility with higher amounts of calcium phosphate surface depositions only after 10 days incubation. The elemental identifications of the surface depositions indicated high amounts of Ca, P and Zn are present on the surface of SBF incubated samples
Pulsed Laser Annealing Effect on Optical and Structural Properties of ZnS/ZnSe Heterostructures
No full textStudies of pulsed laser annealing (PLA) on semiconductor thin films were performed to examine changes of the optical and structural parameters due to the laser heat. Thin films of ZnS/ZnSe were deposited on quartz substrates at a pressure of 8.2*10-6 mbar using PVD technique. These thin films were annealed at different laser powers using CO2 pulsed laser. Transmission and reflection spectra were recorded before and after the annealing process. A decrease in the transmission and reflection spectra after annealing is observed. The absorption coefficient, refractive index, damping coefficient and dielectric constant were calculated before and after the annealing process. Changes in the optical parameters are found after the annealing process. The energy band gaps of ZnS and ZnSe have been determined. Upon annealing, an increase in the absorption coefficient is observed which is due to an improvement in the granular nanostructure of the ZnS/ZnSe thin films. XRD patterns of the prepared samples were obtained before and after the annealing procedure and revealed an enhancement in the crystallite structure upon annealing
Multiple Beneficial Effects of Using Biochar (as a Great Organic Material) on Tolerance and Productivity of Rice under Abiotic Stress
No full textRice as a sensitive crop that usually affected by many harmful environmental stresses. Numerous policies are followed to increase plant growth-tolerance under abiotic-stresses in various plant species. The attempts to improve crop tolerance against abiotic stresses via common breeding method are needed to follow a long-term, and may also be non-affordable, these are due to the existing genetic variability of the plant. Current review analysis existing knowledge gaps, challenges, and opportunities in the biochar application as a beneficial and pyrogenic-C, material. Consequently, a review of the literature with a high focusing on the multiple beneficial effects of using biochar on tolerance and productivity of rice in abiotic stresses is needed. This review provides a summary of those efforts that would be beneficial in reducing inconvenienced abiotic-stresses, and also how using biochar could increase rice tolerance and production through the supporting of plant growth regulator's roles. Accordantly, present review findings showed that biochar is a great amendment and consisting of principally organic rich-C matter, which has multiple benefits on improving soil physicochemical and biological properties as well as increasing rice tolerance and its productivity through enhancing plant hormones roles under abiotic stressed conditions (heat/cold temperature, drought, salinity, heavy metal, and climate change stresses). Nevertheless, it is anticipated that further researches on the benefits of biochar will increase the comprehension of interactions between biochar and plant growth hormones, to accelerate our attempts for improving rice tolerance and productivity, under abiotic-stress conditions
Investigating the Utilization of Ground Palm Kernel Shells for Partial Replacement of Cement in Concrete Using Nondestructive Method
No full textThe objective of this research is to investigate the utilization of palm kernel shells in ground form (GPK) for partial replacement of ordinary Portland cement (OPC) in concrete by investigating its optimal strength using nondestructive ultrasonic pulse velocity method for both cubic and cylindrical concrete test specimen. In all a total of 135 cubes and 66 cylinders of concrete were prepared. The dimension of the cubic concrete specimens was 150 × 150 × 150 mm and that of the cylindrical specimens were 110 mm and 500 mm diameter and length respectively. The mix design of the GPK shells used as a partial replacement for OPC ranged between 0% and 50% by weight of cement using mix ratio of 1:2:4 with water to cement ratio of 0.8. The concrete specimens were test at curing periods of 7 days, 28 days and 60 days for the cubes and 7 days and 28 days for the cylinders. Based on the results and the analysis done, it was generally observed in all cases that, as the mix ratio is increased, the ultrasonic pulse velocity, modulus of elasticity and the density decreased and as the curing period increased, these values increased across all the mix ratios. The ultrasonic pulse velocity and the density of the specimens shows that concretes containing GPK “fuel” shells has higher values than those containing GPK ordinary shells. Generally, the density, ultrasonic pulse velocity and the modulus of elasticity of concrete containing GPK shells decrease as the replacement percentage increase
Epitaxial Lattice Matching and the Growth Techniques of Compound Semiconductors for their Potential Photovoltaic Applications
No full textThis paper presents the recent advances in semiconductor alloys for photovoltaic applications. The two main growth techniques involved in these compounds are metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE), that has also been discussed. With these techniques, hetero-structures can be grown with a high efficiency. A combination of more than one semiconductor like GaAs, InGaAs and CuInGaAs increases the range of their electrical and optical properties. A large range of direct band gap, high optical absorption and emission coefficients make these materials optimally suitable for converting the light to electrical energy. Their electronic structures reveal that they are highly suitable for photovoltaic applications also because they exhibit spin orbit resonance and metal/semiconductor transitions. The dissociation energy has also been discussed in reference to the increased stability of these compounds