In this study, the effect of different additives on the compressive strength of clay-based concrete admixtures was evaluated using standard test methods such as slump test, concrete cube test, curing etc. It was observed that for control samples with no clay and high clay content at 7, 14, and 28 days, compressive strength were 21.05, 22.13, 30.62 and 13.57,14.26 21.49 N/mm2 respectively. For superplasticizer (conplast SP430), Hydrated Lime, Periwinkle shell ash and Rice husk ash at 7, 14 and 28 days at 10% each it compressive strength were (30.78, 33.48, 35.72), (23.36, 28.08,31.82), (22.11, 28.13, 29.30) and (25.47, 27.96, 29.46) N/mm2 respectively. From the results, superplasticizer (conplastSP430) at 10% yielded the highest amount of compressive strength of 30.78, 33.48, and 35.72 at 7, 14, and 28 days curing respectively. These suggest that additives can be utilized in concrete with high clay content to improved compressive strength within satisfactory levels.

The magnetic properties of MnB 2 has been the subject of controversies between the experimenter and the theoretical investigations. In this paper we have rediscovered the structural, electronic and magnetic properties of MnB 2 by means of density functional theory (DFT) within the plane wave (PW) method in combination with the green function to extract the exchange coupling energy. The exchange coupling is the key input parameter to study the magnetic properties under both of the excitation of thermal energy and magnetic field in the Monte Carlo simulation. The structural optimization was performed by using Broyden-Fletcher-Goldfarb-Shanno ( BFGS ) approximation. The electronic and magnetic properties were determined by the analysis of density of states (DOS). The obtained results indicate that MnB 2 is a metallic material with antiferromagnetic (AFM) behavior in the ground state with Neel temperature T N= 810K. The obtained results are in good agreement with the experimental studies.

The metformin electrochemical detection, assisted by cobalt (III) oxyhydroxide has been evaluated from the theoretical point of view. The correspondent mathematical model has been developed and analyzed by means of linear stability theory and bifurcation analysis. It was shown that CoO(OH) may be applied as an efficient electrode modifier in the detection of metformin in neutral and lightly alkaline media. The electrochemical response has to be clear and easy to interpret. The possibility of the oscillatory and monotonic instabilities has also been verified.

There are many methods in quantum chemistry such as semi-empirical methods, ab initio methods, and density functional methods. All of these methods can determine the atomic molecular properties. In this work, we chose the density functional method (DFT) to determine electrostatic potential, frontier molecular orbitals (FMO), and optimization of molecules such as p-nitrophenol, p-methylphenol, and p-aminophenol. The determination of interatomic distances, nonlinear optical descriptors (NLO) such as dipole moment (μ), polarizability (α), first hyperpolarizability (β) and second hyperpolarizability (γ). The analysis of the potential energy surface was carried out by the density functional theory (DFT) method using the Becke, Lee, Yang, and Parr Gradient Corrected Functional (B3LYP) exchange and correlation with the standard base 6-311G (d, p). This method is implemented in the program Gaussian 09. The results of the energy gap, chemical hardness, dipole moment, and hyperpolarizability show that p-nitrophenol is the reactive molecule, and p-aminophenol is the stable molecule. The electrophilic attack occurs at the O7, O10, and O9 sites for p-nitrophenol, O7 for p-methylphenol, and O7, N13 for p-aminophenol.

The simultaneous electrochemical determination of two insecticides thiaclopride and imidaclopride by an electrode, modified by a squaraine dye – VO(OH) hybrid composite, has been evaluated from the mathematical point of view. The correspondent model has been developed and analyzed by means of linear stability theory and bifurcation analysis. It was shown that the squaraine dye – VO(OH) composite may be an efficient electrode modifier for thiaclopride and imidaclopride determination, despite of the hybridity of the reduction mechanism in the last case. On the other hand, the oscillatory behavior for this system will be caused only by DEL influences of the electrochemical stage.

ZnSe bilayer thin films of thickness 343 A were deposited onto soda-lime glass substrates by thermal vacuum evaporation technique using NANO 36 thermal evaporator, under vacuum pressure of 2.9 1 x10 -5 torr. The optical characteristics of the film were done by using AVANTEX UV spectrophotometer in the wavelength range from 239.534 nm to 999.495 nm. The surface morphology studies were also observed by ASPEX 2030 Scanning Electron Microscopy (SEM) operated at accelerating 16 KV potential. Also the electrical characteristics of the thin films were investigated using a KEITHLEY four-point probe technique. The investigation of the optical properties of the thin films as deposited and annealed at different temperatures showed high transmission in the NIR region with good absorption in the visible and UV region. The extrapolated band gap energies were high between 3.60 eV and 4.15 eV and electrical resistivities were low between 0.475 Ωm and 9.070 Ωm.

The air temperature and sunshine duration data were obtained from Kombolcha Meteorological Agency to predict daily global solar radiation at Lalibela, Ethiopia. The mean daily clearness index and mean daily global solar radiation was calculated based on sunshine and air temperature model for the study sites. The validation of the models for predicting mean daily global solar radiation was done using statistical tests such as: MBE, RMSE, MPE and R. The result of these statistical tests for temperature based model: (MBE tem =. -0.50, RMSE tem =0.67, MPE tem =-2.9 and R tem =0.06) and for sunshine based model: (MBE sun =. 0.08, RMSE sun = 0.49, MPE sun = 1.50 and R sun = 0.05). From overall, it was concluded that the better value of the mean daily global solar radiation was observed with sunshine based model (Angstrom-Prescott) than the temperature based model (Hargreaves and Semani) in almost all of the days of the study and be applied to locations with comparable weather condition with Lalibela sites. The maximum average daily global solar radiation that predicted from sunshine hours was 5.86 KWh/m 2 and the maximum average daily global solar radiation that predicted from air temperature was 5.28 KWh/m 2 over a period of 3 years (2014-2016). The result of this study was between the minimum and maximum value of [14] and therefore, the region has high potential for solar energy application.

Theme : Heat transfers, fluid mechanics. Abstract: In this current work, the heat transfer analysis for the unsteady squeezing flow of a viscous nanofluid between two parallel plates considering Fourier heat flux model have been explored. The partial differential equations representing flow model are reduced to nonlinear ordinary differential equations by introducing a similarity transformation. The dimensionless and nonlinear ordinary differential equations of the velocity and temperatures functions obtained are solved by employing The Homotopy Perturbation Method (HPM). The results found in this peper are verified by comparing it with the results obtained using the numerical method RK4, The results obtained are agree with this numerical solution. The effects of different parameters on the velocity and temperature profiles are examined graphically, and numerical calculations for the skin friction coefficient and local Nusselt number are tabulated. It is found an excellent agreement in the comparative study with literature results.

Objectives of this study are to carry out an environmental impact assessment of drilling fluid with emphasis on a case study of Oben Oil field, RIG 201.This field is located in Niger Delta of Nigeria. In carrying out this study, soil samples and water from Oben oil field were analysed to determine concentrations of heavy metals Physio-chemical characteristics were also examined and the results were compared with the Department of Petroleum Resources (D.P.R) guidelines and World Health Organization (W.H.O) standard. The results of the test showed that the values of the wastewater were greater than the values of the treated water because it has undergone treatment and can be discharged into the environment. Therefore, the waste water was above the acceptable recommended limit. Also, the values of the soil sample around the drill site had a very high concentration of heavy metals compared to that of the control sample. The study showed that the existence of high concentration of contaminants in the spent drilling fluid from the reserve pit and as a result of the analysis carried out it is then recommended that the waste resulting from drilling operations should be properly treated before disposal into the environment.Objectives of this study are to carry out an environmental impact assessment of drilling fluid with emphasis on a case study of Oben Oil field, RIG 201.This field is located in Niger Delta of Nigeria .

Reactivation of spent FCC catalyst for its application in the adsorption of heavy metals from wastewater was investigated in this research. The most effective reactivation route of spent FCC catalyst was oxidation of spent FCC catalyst using H 2 O 2 at oxidant-to-catalyst ratio of 16 ml/g, contact time of 60 minutes and a temperature of 90 o C, followed by treatment with CH 3 COOH solution at acid-to-catalyst ratio of 20 ml/g, 75 minutes contact time and at a temperature of 50 o C. The reactivation process was monitored using the Scanning Electron Microscope Energy Dispersive X-ray (SEM-EDX), X-ray fluorescence (XRF) and X-ray diffraction (XRD). The result showed significant decreases in impurities of coke and metal, and the crystallinity of the treated spent FCC catalyst was much greater than that of the spent FCC catalyst.