Utilizing of Elemental Sulfur from Oil and Gas Industry for Soil Treatment

The United Arab Emirates produces a large quantity of elemental sulfur from oil and gas industry. Elemental sulfur is widely used as soil treatment technique for reducing pH of alkaline soils than other techniques because it is cheaper and safer during treatment. In this study, different designs mixes were prepared based on its content of sulfur and calcium carbonate. Different application rates of elemental sulfur (0, 1, 2, and 3%S) were added to soils having different amounts of calcium carbonates (i.e., 16.2, 21.2, 26.2, 36.2, 46.2, and 56.2% for basic mix design, and mix designs types I, II, III, IV, and V, respectively. The changes in soil pH, electrical conductivity (EC) and sulfate concentration were measured at different time intervals (0, 5, 10, 20, 40 and 80 days) and statistically analyzed. Furthermore, mineral transformations were quantified via scanning electron microscope, x-ray diffraction analysis and energy depressive x-ray techniques. Mineral transformations were further analyzed in view of possible chemical reactions and thermodynamic modeling. The study concluded that sulfur addition for all treatments of basic mix design, mix design types I, III, IV, and V has no significant influence on pH changes but has high significance on pH changes for mix design type II as determined via statistical analysis. In this mix design, pH decreased by 1.14, 1.22, 1.27, 1.24 and 1.28 units after 5, 10, 20, 40, 80 days, respectively. For all treatment cases, sulfur addition has high influence on EC changes except for mix design type III that indicates no significance. For sulfur oxidation, similar conclusion to EC changes was reached. Furthermore, available water-soluble sulfate was highly correlated with EC. As sulfate increases, EC increases and vice versa

Neutronics Assessment of Accident-Tolerant Fuel in Advanced Power Reactor 1400 (APR1400)

Safety and reliability are the most desirable conditions that each nuclear power plant should improve. Since the Fukushima Daiichi accident, Accident-Tolerant Fuel (ATF) has been extensively researched to improve the performance of the nuclear fuel system. This paper presents the investigation of the ATF system from a neutronics perspective, which positively reflects on the performance of the APR-1400 nuclear power plant. Several advanced fuel candidates such as UC, U3Si2, and UN, which have better thermophysical properties than current UO2 nuclear fuel, have been considered. Meanwhile, advanced cladding candidates such as FeCrAl, Zr-alloy with coating, and SiC which can reduce or even eliminate the oxidation rate of current Zr-alloy cladding have been adopted in this study. The Monte Carlo Serpent code, in conjunction with ENDF/B-VII.1 nuclear data library, has been used to calculate and evaluate the important neutronics parameters at the assembly level such as the fuel residence time, discharge burnup, kinetics parameters, pin power distribution, temperature reactivity feedbacks, and fissile evolution. The advanced fuels show better neutronics performance than the current UO2 fuel. In addition, SiC provides optimum neutronic performance as cladding

Strategic distribution of seeds to support diffusion in complex networks

© 2018 Jankowski et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Usually, the launch of the diffusion process is triggered by a few early adopters–i.e., seeds of diffusion. Many studies have assumed that all seeds are activated once to initiate the diffusion process in social networks and therefore are focused on finding optimal ways of choosing these nodes according to a limited budget. Despite the advances in identifying influencing spreaders, the strategy of activating all seeds at the beginning might not be sufficient in accelerating and maximising the coverage of diffusion. Also, it does not capture real scenarios in which marketing campaigns continuously monitor and support the diffusion process by seeding more nodes. More recent studies investigate the possibility of activating additional seeds as the diffusion process goes forward. In this work, we further examine this approach and search for optimal ways of distributing seeds during the diffusion process according to a pre-allocated seeding budget. Theoretically, we show that a universally best solution does not exist, and we prove that finding an optimal distribution of supporting seeds over time for a particular network is an NP-hard problem. Numerically, we evaluate several seeding strategies on different networks regarding maximising the coverage and minimising the spreading time. We find that each network topology has a best strategy given some spreading parameters. Our findings can be crucial in identifying the best strategies for budget allocation in different scenarios such as marketing or political campaigns

Phytochemical analysis and antioxidant activity of Haloxylon salicarnicum, Ochradenus arabicus and Tamarix nilotica

In the present investigation, the preliminary phytochemical analysis and antioxidant potential of hexane, chloroform, acetone and methanol extracts of Haloxylon salicarnicum, Ochradenus arabicus and Tamarix nilotica were reported. The presence of flavonoid, alkaloid, phenols, terpenoids, carbohydrate, tannin, protein, steroids, saponin, phlobatannin, cardiacglycoside, anthraquinines and volatile oils were determined and for antioxidant activity, DPPH, ABTS, superoxide anion radical and hydroxyl radical scavenging potential were studied. Strong presence of alkaloid, tannin, steroids in H. salicarnicum, flavonoid and phenols in O. arabicus and saponin T. nilotica were observed. In the present investigation, all the extracts inhibited the free radicals the methanol extract of O. arabicus was identified as potential crude extract compared to all other extracts with the IC50 values of 91.65 (DPPH), 94.62 (ABTS), 95.82 (O2) and 96.02 (OH) µg/mL. Whereas, the IC50 value of the standard, Gallic acid were 125.25 (DPPH), 142.32 (ABTS), 130.78 (O2) and 139.93 µg/mL (OH). Whereas, the IC50 value of the standard, Gallic acid were 125.25 (DPPH), 142.32 (ABTS), 130.78 (O2) and 139.93 µg/mL (OH)The present study suggests that methanol extract of O. arabicus can be used for the isolation potential natural antioxidant

Computational aspects of optimal strategic network diffusion

Waniek, M., Elbassioni, K., Pinheiro, F. L., Hidalgo, C. A., & Alshamsi, A. (2020). Computational aspects of optimal strategic network diffusion. Theoretical Computer Science, 814, 153-168. https://doi.org/10.1016/j.tcs.2020.01.027Diffusion on complex networks is often modeled as a stochastic process. Yet, recent work on strategic diffusion emphasizes the decision power of agents [1] and treats diffusion as a strategic problem. Here we study the computational aspects of strategic diffusion, i.e., finding the optimal sequence of nodes to activate a network in the minimum time. We prove that finding an optimal solution to this problem is NP-complete in a general case. To overcome this computational difficulty, we present an algorithm to compute an optimal solution based on a dynamic programming technique. We also show that the problem is fixed parameter-tractable when parametrized by the product of the treewidth and maximum degree. We analyze the possibility of developing an efficient approximation algorithm and show that two heuristic algorithms proposed so far cannot have better than a logarithmic approximation guarantee. Finally, we prove that the problem does not admit better than a logarithmic approximation, unless P=NP.authorsversionpublishe