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The structural, mechanical and thermodynamics properties of cubic zirconium oxide (cZrO 2) were investigated in this study using ab initio or first-principles calculations. Density functional theory was used to optimize the crystal structure of cZrO 2 and thereafter, simulations were conducted to predict the lattice parameters and elastic constants. The Zr-O bond distance was calculated as 2.1763 Å with unit cell density of 6.4179 g/cm 3. The data obtained were used to determine Young's modulus, bulk modulus, Poisson's ratio and hardness of cZrO 2 as 545.12 GPa, 136.464 GPa, 0.1898 and 12.663(H v) respectively. The result indicates that cZrO 2 is mechanically stable with thermodynamics properties of a refractory material having potential for structural and catalytic applications in various forms as a nanomaterial.

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This work presents the conceptual design of a gas distribution pipeline network for estates in Nigeria using the University of Abuja Staff Quarters as a case study. The problem statement was the aggressive consumption of cooking gas, referred to as liquefied petroleum gas (LPG), without gas pipeline networks infrastructures to homes and estates across Nigeria but relies on cylinders with its attendant danger. The methodology includes the determination of the gas demand from the average monthly gas consumption in each of the households, the elevation head, diameter of the pipelines, gas velocity, gas mass flow rate, head losses and the pressure drop analysis of series (option 1), parallel (option 2) and grid (option 3) options. The results obtained indicate that the best gas distribution design option for the trunk, reticulation and service pipelines was the grid connections to minimize investment costs with equitable pressures at service outlets. In the selected design option, the total length of the 50.8 mm diameter trunk pipelines was 19.52 m, while the total length of the 12.7 mm diameter reticulation and service pipelines were 3,223.34 m and 1,648.46 m respectively. The quantities of fittings required for the pipeline network layout were determined for an estate of 124 houses. The mass flow rates of the LPG in the 3 pipeline sections were found to be 0.39 kg/s and total head loss based on local resistance coefficients was found to be lowest in option 3 (1,568.33 m), which also has the least pressure drop of 67.84 kPa in the trunk and reticulation pipelines. It can be concluded that the optimized design could be adopted for the gas distribution pipeline network of University of Abuja staff quarters and other estates in Nigeria, with similar elevation and buildings layout.

The single-walled zirconia nanotube is structurally modeled and its Young’s modulus is valued by using the finite element approach. The nanotube was assumed to be a frame-like structure with bonds between atoms regarded as beam elements. The properties of the beam required for input into the finite element analysis were computed by connecting energy equivalence between molecular and continuum mechanics. Simulation was conducted by applying axial tensile strain on one end of the nanotube while the other end was fixed and the corresponding reaction force recorded to compute Young’s modulus. It was found out that Young’s modulus of zirconia nanotubes is significantly affected by some geometrical parameters such as chirality, diameter, thickness, and length. The obtained values of Young’s modulus for a certain range of diameters are in agreement with what was obtained in the few experiments that have been conducted so far. This study was conducted on the cubic phase of zirconia having armchair and zigzag configuration. The optimal diameter and thickness were obtained, which will assist in designing and fabricating bulk nanostructured components containing zirconia nanotubes for various applications.

Harvested fruit have high metabolic and moisture content which leads to an active biochemical reaction that contributes to decrement of nutritional value such as vitamin, proteins and lipids. The application of low temperature as a single-effective management to prolong shelf-life of fruits is a common practice which applied to keep agriculture commodities at high quality. A matured stage pineapple is very perishable and cold storage chain is crucial in maintaining the chemical and physical quality attributes in order to assure its commercial value for market. The main objective of this study is to evaluate the effect of sub-optimum cold storage scenario on changes of pineapple fruits physical quality attributes, the activity of browning enzyme and antioxidant related enzyme in 2 pineapple cultivars (cv.), Morris (Queen-type) and Josapine (hybrid of Spanish and Smooth Cayeen). Malaysian pineapple fruit cv. with different sensitivity toward CI, Morris (Queen-type) and Josapine (Smooth-Cayenne-type) were stored at sub-optimal storage temperatures (4±2°C) for 28 days to investigate the effects of CI towards physical quality attributes and antioxidant enzyme activity. The result indicated both cv. was affected with CI towards the 28 days of sub-optimum cold storage. Overall physical quality attributes indicated CI was found positively correlated with the increase of EL and TTA and on the contrary decrease its firmness, weight (% w/w), brightness (L*) and redness (A*). Similarly, a positive correlation was also deduced between CI symptoms and the activities of PPO and APX which reflect the incident of oxidative stress. The results derived from this study may serve as a basis for evaluation of better postharvest strategies to control CI during cold chain storage of pineapple fruits and thus assure the quality and nutritional value till it reaches to consumer.

Molecular modelling methods were used to investigate the structural and interatomic potential of bulk cubic zirconia. To widen the scope of the expected outcome, GULP and CASTEP software were used based on the concept of minimizing the energy of the crystal structure with respect to atomic coordinates. The crystal structure of cubic zirconia was modelled and optimized; the lattice parameter of 5.10 Å obtained is similar to available calculated and experimental values. The developed interatomic potential is based on Born model for ionic solids without defects. The calculated interatomic potential of 109.67eV per atom is also within acceptable range, but variation was observed depending on the relative position of individual atoms. The modelling gave a better understanding of the bulk crystal structure of cubic zirconia due to detailed parameters that were obtained. Also, the determined parameters were used to estimate the Young’s Modulusof bulk zirconia as 397GPa.

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