A New Formula For Rate Of Swelling Of Expansive Clay Soils

The study of engineered expansive soils attracts the attention of researchers since this soil is mixed and increasingly used in many geotechnical and geoenvironmental application. This paper attempts to the study of swelling properties i.e. swell and swelling pressure, rate of swell, and water adsorption during swell. The kaolin-bentonite mix and sand-bentonite mix specimens are statically compacted and tested in conventional oedometer apparatus for swelling determination. The results of the study show that the mechanism of swell follows three distinct stages: intervoid, primary, and secondary swelling. The swell occurs since the soils adsorb water during water uptake. The rate of swell and maximum swelling are successfully determined using hyperbolic equation

Engineering properties of cemented peat bricks

Housing is a great problem in today’s world and the world future. The most basic building material for infrastructure construction and housing is the usual brick or blocks. Conventional bricks, which are burnt clay, create environmental problems. The purpose for this study was undertaken on the production of peat; siliceous sand, composite cement and lime solid bricks to solve the economic problems of housing and construction building by utilizing local materials. The compressive strength, water absorption and density of these bricks were investigated. It was observed that these bricks had sufficient strength for their use in low cost housing development. Tests were also conducted to study the influence of curing type on the increase in strength and hardening of the bricks with time

A study of nanoparticles as a drug carrier on the wall of Stenosed Arteries

The influences of nanoparticles as drug carriers on the walls of stenosed arteries are presented. In this study, three nanoparticles namely Fe3O4 , TiO2 and Cu were used. It is observed that the addition of Fe3O4 nanoparticles tends to reduce the resistance impedance of blood temperature in bell shaped stenosed arteries. The blood temperature increases slightly in the streamwise direction before the throat region. Thereafter, the blood temperature increases at a higher rate and reaches its maximum value at the stenosis throat. It is found that the temperature distribution is heavily dependent on parameters such as periodic body acceleration and Prandtl number

First-principles investigation of graphitic carbon nitride monolayer with embedded Fe atom

Density-functional theory calculations with spin-polarized generalized gradient approximation and Hubbard $U$ correction is carried out to investigate the mechanical, structural, electronic and magnetic properties of graphitic heptazine with embedded $\mathrm{Fe}$ atom under bi-axial tensile strain and applied perpendicular electric field. It was found that the binding energy of heptazine with embedded $\mathrm{Fe}$ atom system decreases as more tensile strain is applied and increases as more electric field strength is applied. Our calculations also predict a band gap at a peak value of 5 tensile strain but at expense of the structural stability of the system. The band gap opening at 5 tensile strain is due to distortion in the structure caused by the repulsive effect in the cavity between the lone pairs of edge nitrogen atoms and $\mathrm{d}_{{xy}}/\mathrm{d}_{x^2-y^2}$ orbital of Fe atom, hence the unoccupied $\mathrm{p}_z$-orbital is forced to shift towards higher energy. The electronic and magnetic properties of the heptazine with embedded $\mathrm{Fe}$ system under perpendicular electric field up to a peak value of 10 $\mathrm{V/nm}$ is also well preserved despite obvious buckled structure. Such properties may be desirable for diluted magnetic semiconductors, spintronics, and sensing devices

Mangrove restoration without planting

Mangrove forests are disappearing at an alarming rate. Mangrove planting is the most common method of restoring these forests. However, this approach is not often successful, especially when the reasons for mangrove degradation were not removed prior to planting new seedlings or propagules. A successful mangrove restoration project may not necessarily include a planting phase. When the stressors are removed and suitable environmental conditions such as correct hydrology and calm area, particularly on exposed coasts, are provided, natural regeneration processes could recover mangroves from degradation. This paper describes an approach to mangrove restoration applied to an exposed shoreline on the west coast of Peninsular Malaysia. In this method a detached breakwater was erected seaward at the shoreline to shelter the restoration area from wave action, prevent the ongoing erosion and promote sediment deposition raising the elevation of the substrate to the target elevation. Survival of Avicennia marina seedlings transplanted in the sheltered area was significantly affected by sediment burial (P< 0.05). However, about eight months after construction of the breakwater, the sedimentation rate decreased and the substrate became stable. Subsequently, natural recruits appeared on the site. We postulate that waterborne seeds or propagules were available from adjacent stands in the study area but wave exposure reduced the possibility of natural recruitment. Thus the breakwater presence provided favourable conditions which could attract mangrove recruits, facilitating reestablishment and natural recovery of the mangrove ecosystem without planting

Theoretical studies on mechanical and electronic properties of ss-triazine sheet

Mechanical and electronic properties of $s$-triazine are studied using first-principles calculations based on density functional theory. The in-plane stiffness and bulk modulus for $s$-triazine sheet are found to be less than that of heptazine. The reduction can be related to the nature of the covalent bonds connecting the adjacent sheets and the number of atoms per unit cell. The Poisson's ratio of $s$-triazine is half the value to that of graphene. Additionally, the calculated values of the two critical strains (elastic and yielding points) of $s$-triazine sheet are in the same order of magnitude to that for heptazine which was calculated using MD simulations in the literature. It is also demonstrated that $s$-triazine sheet can withstand larger tension in the plastic region. These results established a stable mechanical property for $s$-triazine sheet. We found a linear relationship of bandgap as a function of bi-axial tensile strain within the harmonic elastic region. The reduced steric repulse of the lone pairs ($\mathrm{p}_x$-, $\mathrm {p}_y$-) causes the $\mathrm {p}_z$-like orbital to shift to high energy, and consequently an increase in the bandgap. We find no electronic properties modulation of the $s$-triazine sheet under electric field up to a peak value of 10 V/nm. Such noble properties may be useful in future nanomaterial applications.Comment: Manuscript submitted to Philosophical Magazine Journa

Traditional Islamic education in Asia and Africa: a comparative study of Malaysia’s Pondok, Indonesia’s Pesantren and Nigeria’s traditional madrasah

The Muslim world has witnessed the emergence of several Islamic-based institutes and universities in the last three decades, in keeping with some of the recommendations of World Conferences on Muslim Education. Such a development has greatly improved the quality of higher Islamic education especially with regards to the contribution to Islamic scholarship of some of the graduates of such Islamic institutes and universities. However, the traditional system of Islamic education at the pre-university level has not been greatly influenced by such a development. There has not been a comprehensive study of the system as operated in various contemporary Muslim settings, with a view to assessing the degree of its efficacy. Therefore, there is a long-felt need for such a research endeavour. The purpose of this paper is to carry out a comparative study of Malaysia’s pondok, Indonesia’s pesantren and Nigeria’s traditional madrasah system. The choice of the three educational settings was informed by the growing impression that Malaysia and Indonesia, both Asian countries, offer some of the best practices in traditional Islamic education, which may be used as standards in improving upon what operates in Nigeria, an African country with the largest Muslim population and largest number of madaaris (pl.). The paper traces the origins of the traditional Islamic education system, discusses the evolution of each of the three systems and addresses such salient issues as ownership of the school, the structure of the school, the curriculum, teachers’ requirements and qualifications, teaching methods, evaluation procedures, teachers’ welfare and salaries, the socio-economic status of the teacher, the schools and the challenges of higher education in the face of urbanization, as well as practical recommendations for reforms. The paper, which is both historical and analytical in nature, employs the philosophical method, in its critical perspectives and practical suggestions. The significance of such a comparative study lies in its potentiality to expose the strengths and deficiencies of each of the educational settings, as well as highlight their commonalities and differences

Adsorption of atoms and molecules on s-triazine sheet with embedded manganese atom: First-principles calculations

The mechanical, structural, electronic and magnetic properties of s-triazine sheet (C6N6) with embedded Mn atom (Mn-C6N6) is investigated under the influence of external environment using density functional theory. Our results show that Mn-C6N6 system is structurally and mechanically stable. The binding energy of Mn embedded in C6N6 sheet can be modulated under the influence of symmetric deformation and perpendicular electric field respectively. The semiconducting property of pure C6N6 sheet is maintained upon embedment of Mn atom in the porous site. It is also found that small increment in bi-axial tensile strain enhances the band gap (from 0.630 eV at zero strain to 0.802 eV at 5% strain) while the magnetic moment of the embedded Mn atom is preserved. The electronic and magnetic properties of the Mn-C6N6 systems are maintained up to 10 V/nm in electric field strength. We also explore the geometries, electronic and magnetic properties of Mn-C6N6 with adsorbed atoms and molecules. The Mn-C6N6 with adsorbed O atom and O2 molecule systems shows half-metallic character whereas the remaining systems preserve their semiconducting property. The total magnetic moment per unit cell in most of the systems is found to reduce as compared to that of the Mn-C6N6 sheet. The reduction in magnetic moment can be related to the strong interactions among the Mn atom and the surrounding atoms which lead to the formation of low-spin configurations. Overall, our results indicate that the Mn-C6N6 systems with and without adsorbed atoms and molecules can serve as potential candidates for future spintronics and catalysis applications.Comment: 14 pages, 6 figure

Dynamics of sediment transport and erosion-deposition patterns in the locality of a detached low-crested breakwater on a cohesive coast

Understanding the dynamics of sediment transport and erosion-deposition patterns in the locality of a coastal structure is vital to evaluating the performance of coastal structures and predicting the changes in coastal dynamics caused by a specific structure. The nearshore hydro-morphodynamic responses to coastal structures vary widely, as these responses are complex functions with numerous parameters, including structural design, sediment and wave dynamics, angle of approach, slope of the coast and the materials making up the beach and structures. This study investigated the sediment transport and erosion-deposition patterns in the locality of a detached low-crested breakwater protecting the cohesive shore of Carey Island, Malaysia. The data used for this study were collected from field measurements and secondary sources from 2014 to 2015. Sea-bed elevations were monitored every two months starting from December 2014 to October 2015, in order to quantify the sea-bed changes and investigate the erosion-deposition patterns of the cohesive sediment due to the existence of the breakwater. In addition, numerical modelling was also performed to understand the impacts of the breakwater on the nearshore hydrodynamics and investigate the dynamics of fine sediment transport around the breakwater structure. A coupled two-dimensional hydrodynamics-sediment transport model based on Reynolds averaged Navier-Stokes (RANS) equations and cell-centered finite volume method with flexible meshing approach was adopted for this study. Analysis of the results showed that the detached breakwater reduced both current speed and wave height behind the structure by an average of 0.12 m/s and 0.1 m, respectively. Also, the breakwater made it possible for trapped suspended sediment to settle in a sheltered area by approximately 8 cm in height near to the first main segment of the breakwater, from 1 year after its construction. The numerical results were in line with the field measurements, where sediment accumulations were concentrated in the landward area behind the breakwater. In particular, sediment accumulations were concentrated along the main segments of the breakwater structure during the Northeast (NE) season, while concentration near the first main segment of the breakwater were recorded during the Southwest (SW) season. The assessment illustrated that the depositional patterns were influenced strongly by the variations in seasonal hydrodynamic conditions, sediment type, sediment supply and the structural design. Detached breakwaters are rarely considered for cohesive shores; hence, this study provides new, significant benefits for engineers, scientists and coastal management authorities with regard to seasonal dynamic changes affected by a detached breakwater and its performance on a cohesive coast

Steady Flow About A Sphere In A Porous Medium Subject To An Oscillating Temperature

The study of free convection about a sphere in a porous medium, when the temperature of the sphere is oscillating harmonically is considered for Rayleigh number, Ra=100. By using the matched asymptotic expansion, the flow field is divided into an inner region and an outer region, where the inner region is adjacent to the sphere and the outer region is far from the sphere. In the inner region, the separation technique is used to divide the second-order temperature and stream function into steady and unsteady parts. The analytical solution is obtained up to second-order steady term. For outer region, the numerical result up to first order is obtained by using a finite difference scheme. It is found that, a steady flow is induced at the outer edge of the inner region. The temperature and flow patterns are discussed and compared for some frequencies of oscillation, &omega; and dimensionless parameter &epsilon;. It is found that both the magnitudes of temperature and stream functions decreases as &omega; increases or decreases but the effect of &epsilon; is not significant in the outer region. In the inner region, the magnitude of steady flow is also determined by frequency