Optimization of extracts and constituents from alpinia galanga as corrosion inhibtor for mild steel in acidic medium

In terms of environmental impacts and cost considerations, the use of green additives particularly from plant origin have been found as a viable alternative approach to synthetic organic inhibitors in combatting the menace of corrosion. However, owing to the composition matrix complexity of plant extracts, efforts are seldom made to engage their isolated constituents for corrosion inhibition; hence their optimal utilization is hindered. In this research, corrosion inhibition properties of the rhizomes of Alpinia galanga and its constituents were investigated experimentally and theoretically on mild steel in hydrochloric acid solution using weight loss and electrochemical methods, and surface characterization techniques namely attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX). Explorations using response surface methodology (RSM) as the optimization tool and quantitative structure-activity relationship (QSAR) modelling of the plant’s major phenylpropanoids were carried out. At room temperature, efficiencies were highest at the uppermost concentrations of all the inhibitors in the following order: hexane extract (90.2%), essential oils (87.9%), and methanol extract (74.2%) while for the phenylpropanoid constituents; 1'-acetoxychavicol acetate (84.6%), methyl eugenol (83.6%), eugenol acetate (82.1%), eugenol (76.3%) and p-hydroxycinnamic acid (30.4%). Optimal efficiencies of 90.3% and 91.17% were attained for hexane extract and essential oil components, respectively, at optimized concentration, temperature, and time. Investigations revealed that mixed mode interactions for all the inhibitors and their effectiveness were supported by the surface characterization techniques. Inhibition efficiencies decreased with increasing temperature for all inhibitors except for the essential oil fraction which increased steadily. The Langmuir isotherm model showed the best fit, giving negative values of adsorption energies with thermodynamics and kinetics parameters supporting the principles of electrostatic interaction. The structural requirements of the phenylpropanoids for effective inhibition were clarified while electrostatic interaction-related descriptors were selected by penalization methods in the constructed QSAR models

Optimization of extracts and constituents from Alpinia galanga as corrosion inhibitor for mild steel in acidic medium

In terms of environmental impacts and cost considerations, the use of green additives particularly from plant origin have been found as a viable alternative approach to synthetic organic inhibitors in combatting the menace of corrosion. However, owing to the composition matrix complexity of plant extracts, efforts are seldom made to engage their isolated constituents for corrosion inhibition; hence their optimal utilization is hindered. In this research, corrosion inhibition properties of the rhizomes of Alpinia galanga and its constituents were investigated experimentally and theoretically on mild steel in hydrochloric acid solution using weight loss and electrochemical methods, and surface characterization techniques namely attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX). Explorations using response surface methodology (RSM) as the optimization tool and quantitative structure-activity relationship (QSAR) modelling of the plant’s major phenylpropanoids were carried out. At room temperature, efficiencies were highest at the uppermost concentrations of all the inhibitors in the following order: hexane extract (90.2%), essential oils (87.9%), and methanol extract (74.2%) while for the phenylpropanoid constituents; 1'-acetoxychavicol acetate (84.6%), methyl eugenol (83.6%), eugenol acetate (82.1%), eugenol (76.3%) and p-hydroxycinnamic acid (30.4%). Optimal efficiencies of 90.3% and 91.17% were attained for hexane extract and essential oil components, respectively, at optimized concentration, temperature, and time. Investigations revealed that mixed mode interactions for all the inhibitors and their effectiveness were supported by the surface characterization techniques. Inhibition efficiencies decreased with increasing temperature for all inhibitors except for the essential oil fraction which increased steadily. The Langmuir isotherm model showed the best fit, giving negative values of adsorption energies with thermodynamics and kinetics parameters supporting the principles of electrostatic interaction. The structural requirements of the phenylpropanoids for effective inhibition were clarified while electrostatic interaction-related descriptors were selected by penalization methods in the constructed QSAR models

Re-usable low density polyethylene arm glove for puerperal intrauterine exploration

Objective: To design a long arm glove that can be used within a puerperal uterus to prevent the health-care worker contracting HIV from an infected patient. The designed long arm glove should be cheap (affordable) and readily available in low resource centres and must have proven sterility assurance and tensile strength to confer protection for the health worker. Design: Prospective study. Setting: Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria from 1st December 2006 to 31st May, 2007. Subjects: Fifty medical students of both sexes were selected randomly and the average length from the styloid process to the mid upper-arm of each was measured and the average length was later determined. This was to determine the length of the low density polyethylene long arm gloves to be made from virgin polyethylene material. Consecutive cases of patients with retained placentae in the puerperium who were scheduled for manual removal of the placenta within the period. Results: Packs of low density polyethylene (LDPE ) long arm gloves were made from virgin polyethylene material. When subjected to bacteriological analysis, three out of four glove packs were contaminated with Staphylococcus, Bacillus and Klebsiella species of bacteria. Gamma irradiation ranging from 28.133 to 83.35 kiloGray of gamma-irradiation (kGy) sterilised all the gloves as postirradiation glove specimens showed no bacterial contamination. However, at doses up to 50 kGy gamma irradiation caused “strengthening” of the polyethylene gloves. While at doses greater than 50 kGy, gamma irradiation caused “embrittlement” of the material. Thus, 50 kGy of gamma irradiation was found to be an ideal dose to strengthen and to sterilise the glove for usage. The sterilized gloves were found to be effective when used in consecutive cases of retained placenta in protecting the health care workers (HCW) from contamination by possibly HIV contaminated blood. Conclusion: There is a risk of contracting HIV for the health-care worker while carrying out a procedure within the puerperal uterus. The low density polyethylene arm glove was designed to prevent this in low resource centres as it would be affordable, available, with proven sterility assurance and mechanical properties to confer protection for the healthcare worker. East African Medical Journal Vol. 85 (7) 2008: pp. 355-36

NUMERICAL SIMULATION OF OUTER DIE ANGLE OF EQUAL CHANNEL ANGULAR EXTRUSION PROCESS

The study of the simulation of effect of outer die angle in Equal Channel Angular Extrusion (ECAE) process was investigated. The simulation was carried out on 6063 aluminium alloy with a view to achieve ultra-fine grain structures. ADINA user interphase Version 8.6 (900 modes) was used for the simulation. The unextruded parameters of the 6063 aluminium alloy were used as input codes and some basic assumptions were made in designing the model on 2-Dimensional scale. The billet was meshed by dividing the vertical and horizontal geometry into 30 and 4 elements respectively. The die angle was varied from 0o to 90o and the simulation results were displayed. The results showed that the force of 27.5X106 N, 27.5X106 N, 27.6X106 N and 31.2 X106 N was required to deform when the outer die angle was 0o, 22.5o, 45o and 90o respectively. Also, the strains achieved were 0.61, 0.62, 0.66 and 0.69 respectively. Thus, highest force is required at 90o and the strain achieved at 0o is the lowest. Based on the results, it was recommended that it is more economical to extrude at an outer angle between 22.5o and 45o as a relatively higher effective strain will be induced

NUMERICAL SIMULATION OF OUTER DIE ANGLE OF EQUAL CHANNEL ANGULAR EXTRUSION PROCESS

The study of the simulation of effect of outer die angle in Equal Channel Angular Extrusion (ECAE) process was investigated. The simulation was carried out on 6063 aluminium alloy with a view to achieve ultra-fine grain structures. ADINA user interphase Version 8.6 (900 modes) was used for the simulation. The unextruded parameters of the 6063 aluminium alloy were used as input codes and some basic assumptions were made in designing the model on 2-Dimensional scale. The billet was meshed by dividing the vertical and horizontal geometry into 30 and 4 elements respectively. The die angle was varied from 0o to 90o and the simulation results were displayed. The results showed that the force of 27.5X106 N, 27.5X106 N, 27.6X106 N and 31.2 X106 N was required to deform when the outer die angle was 0o , 22.5o , 45o and 90o respectively. Also, the strains achieved were 0.61, 0.62, 0.66 and 0.69 respectively. Thus, highest force is required at 90o and the strain achieved at 0o is the lowest. Based on the results, it was recommended that it is more economical to extrude at an outer angle between 22.5o and 45o as a relatively higher effective strain will be induced

Fatigue Crack Growth Mechanisms At the Microstructure Scale in Al-Si-Mg Cast Alloys: Mechanisms in Regions II and III

The fatigue crack growth behavior in Regions 11 and III of crack growth was investigated for hypoeutectic and eutectic Al-Si-Mg cast alloys. To isolate and establish the mechanistic contributions of characteristic microstructural features (dendritic α-Al matrix, eutectic phases, Mg-Si strengthening precipitates), alloys with various Si content/morphology, grain size level, and matrix strength were studied; the effect of secondary dendrite arm spacing (SDAS) was also assessed. In Regions 11 and III of crack growth, the observed changes in the fracture surface appearance were associated with changes in crack growth mechanisms at the microstructural scale (from a linear advance predominantly through primary α-Al to a tortuous advance exclusively through AI-Si eutectic Regions). The extent of the plastic zone ahead of the crack tip was successfully used to explain the changes in growth mechanisms. The fatigue crack growth tests were conducted on compact tension specimens under constant stress ratio, R = 0.1, in ambient conditions

Mathematical Modelling of Aluminiun Surface when Dipped in Molten Metal

A mathematical model is presented to describe the undulating surface of aluminium casting during an industrial process involving the dipping of the mould, at a particular velocity, into the molten metal. The problem of air gap formation between the mould and the casting was also considered. Below certain value of the mould velocity the shape of the casting as well as its thickness remain practically unchanged with changes in mould velocities. The undulating surface disappears when the mould temperature is in excess of 120oC. (Nigeria Journal of Pure and Applied Physics: 2003 2 (1): 36-39

Finite Element Modelling Of Solidification Of Zinc Alloy

The solidification process of Zinc alloy is modelled by solving heat transfer equations with the aid of finite element method (FEM) using appropriate boundary conditions at the mould walls. The commercial software, Matlab, has been used to model the solidification process. The temperature profiles for each casting condition were determined. The model demonstrated capability in predicting accurately the location as well as the shapes of heat centres in any casting. The calculated shapes of the heat centers are in good agreement with experimental results for the various casting conditions. The FEM modelling also serves as useful tool for designing feeders for the heat centres. Key words: finite element, modelling, zinc alloy, heat transfer process Nig. J. of Pure & Appl. Physics Vol.3 2004: 21-2

Corrosion inhibition of crude extracts of alpinia galanga on mild steel in acidic medium

The topics of interests include Inorganic and Organic Chemistry, Material and Polymer Chemistry, Analytical and Forensic Chemistry, Environmental and Green Chemistry, Optics and Photonics, Solid State Physics, Nuclear and Radiation Physics, Pure and Applied Mathematics, Statistics and Probability and any other science related fields. In brief, the ISPC2015 is the platform for the presentation of technological advances and scientific research that provides good opportunities for the participants to exchange new ideas and to present their latest research results