Microalgae are novel organisms that host a number of high-value products (HVPs). Finding an efficient extraction technique to recover selected HVP is of interest to many scientists and industries. In our study, the possible use of supercritical CO2 (scCO2) and ionic liquid (IL) were investigated as a potential greener solvent, compared to conventional solvent used, to determine the extraction capability for carotenoids, namely ?-carotene, from dried Dunaliella Salina biomass. Possibility of combining ethanol with IL or scCO2 with ethanol or ILs as cosolvents has also been examined and compared with individual solvent use. It was concluded that the combined use of ethanol with IL resulted in 6 folds yield increase in extract extraction when compared to the use of pure IL and the addition of a cosolvent in supercritical extraction increased the yield by 2 folds that of pure scCO2, with IL use being preferred due to insolubility in scCO2.
This paper investigated the regeneration of a deep eutectic solvent (DES), namely MethylTriphenylPhosphonium Bromide: Triethylene Glycol at a molar ratio of 1:4, (MTPB: TEG (1:4)). Single-stage LLE was conducted with an oil model containing 76wt% n-heptane (diesel representative), 20 wt% toluene (aromatics representative), 2wt% thiophene (S-containing-aromatics representative) and 2wt% quinoline (N-containing-aromatics representative). Then, the used DES was regenerated via two methods: back-extraction with n-heptane, and washing with anti-solvent (distilled water or diethylether). Diethylether was excluded as it reacted with the DES. n-heptane and water removed all of toluene and thiophene. However, water was substantially better at removing quinoline compared to n-heptane. This paper found that three water washes reduced the quinoline content in MTPB: TEG (1:4) from 20.68wt% to 0.88wt%. Nonetheless, three back-extraction cycles reduced the quinoline to 16.78wt%. The extraction efficiency of the DES regenerated by water was slightly lower than the extraction efficiency of its fresh counterpart.
In recent years, novel algorithms for gradient descent optimization have found success in deep machine learning applications. However, these algorithms can also be used for geophysical inversion. In this paper, we survey and compare between four first-order algorithms when applied to 2D anisotropic seismic tomography. These algorithms include Momentum, NAG, AdaGrad and AMSGrad. Our method keeps all input model parameters and hyperparameters constant and only tunes the learning rate. The results revealed that the algorithms NAG, Momentum and AdaGrad exhibit a stable convergency while AMSGrad is not stable. Moreover, each algorithm has a limited range of learning rates for which it performs best. Overall, NAG algorithm was found to be the most promising.
The Lower Cretaceous oceanic anoxic event (OAE1a) on the Arabian Peninsula has been extensively studied. The negative carbon isotope excursion hosted by the Hawar Member reflects the perturbation in the carbon cycle that lid to global environmental changes and is considered the cause of ocean acidification. The global environmental perturbation has generated different feedback among carbonate calcifiers, leading to turnover, extinctions, and demise of most platforms. The Arabian platform represents an exception, keeping growing during the OAE. The high-resolution chemostratigraphy study of Wadi Mu'aydin outcrop, using oxygen and carbon isotopes and multi-element X-ray fluorescence (XRF), has produced a dataset that helps in define the environmental change at the Barremian -Lower Aptian boundary in the shallow water domain in northern Oman.
This study provides sedimentological, geochemical, and sequence stratigraphic analyses of a Lower Cretaceous sedimentary section in Wadi Rahabah, Ras Al-Khaimah. Outcrop analogues for the Kharaib and Shuaiba formations in Wadi Rahabah assist in studying reservoir continuity and distribution in Abu Dhabi subsurface as well as improving and revising sequence stratigraphic and facies models. New data were acquired from geochemical methods to understand the formation, evolution, and chronostratigraphy of reservoir facies. The outcrops in Wadi Rahabah expose a carbonate platform setting. The depositional environment ranges from brackish lagoon to middle ramp. The carbon isotope values fall in the Barremian-Aptian range and show a strong correlation with the Cismon core (northern Italy). Two sequence boundaries were interpreted: The Lekhwair-Kharaib boundary and the Barremian-Aptian boundary. The Hawar litho-stratigraphical unit is not developed in Wadi Rahabah and its time-equivalent is a very thin, high energy grainstone unit.
The Ferrar Large Igneous Province is thought to have been emplaced around ~182 Ma forming a linear belt for 3500 km, covering highly vegetated parts of Antarctica, Australia, and Tasmania. Bulk chemical analysis, petrographic analysis, and literature-based palaeobotanical collection were accomplished to study the influence of the Ferrar volcanism on these areas. Graphic illustration of the Central Transantarctic Mountains was constructed using all gathered information and obtained data to visualize the effect of the Ferrar Magmatism on these areas (Pre-, syn-, and post-Ferrar magmatism).
The deep subsurface structural geometries of the frontal fold belt of UAE-Oman Mountains and foreland basin are not well understood. Accordingly, the present study used seismic sections and well logs aiming at outlining the different stratigraphic units and their structural setting. The study was initiated by tying the wells to seismic, then interpreting the faults/horizons. The study area is dissected by thrust and backthrust faults. The main thrust fault has a fault-propagation fold, trending NW-SE. It dissects the whole succession. Rapid Cenozoic subsidence is noticed from east to west across the Khusub thrust and its southerly extension. Most of the subsidence is within the Fars Group, where it shows great thickness variation along the sides of the thrust, whereas the Pabdeh Group exhibits less subsidence. The Sumeini sheet is present across the north eastern edge of the area, whereas Hawasina nappe covers the eastern central and southern parts.
The Red Sea is the closest active analog to the rifting and rupturing of continental lithosphere and provides an ideal natural setting to study the continental-oceanic rift transition. Currently, the Egyptian margin is one of the most potential regions for hydrocarbon exploration. The presence of thick evaporites and halite strongly affects the quality of seismic sections and cause challenges for successful exploration. Hence, a greater knowledge of sediments distribution of the morpho-structural setting of the margin and evolution of the Egyptian margin is therefore necessary. Accordingly, the main aim of the current study is to interpret a 3D seismic survey in order to analyse the tectonic evolution of the Red Sea, construct thicknesses and depth maps of the sedimentary units. Picking and interpolation the base of evaporites will allow to recognize any possible closures favorable to the hydrocarbons accumulation and to predict the location of pre-rift reservoirs below the salt.
Australia, in addition to South America, South Africa, and Antarctica, was impacted by the Karoo-Ferrar Large Igneous Province (LIP), a massive volcanic event that occurred ~182 millions years ago (Myrs). This event led to major environmental changes and out gassed copious amounts of CO2 similar to climate-change-driven increases today. Cores from Tasmania, Australia (Bicheno 3A and Bicheno 4) provide a window to the past and have the potential to examine the influence(s) of the Karoo-Ferrar LIP event by using sedimentological, mineralogical, and other special feature analyses. These cores span from 298.9 to 145 Myrs and include the Permian, Triassic, and Jurassic sections. Bicheno cores are important as they contain various deposits that can reveal the evolution of the regional paleoenvironment and a better understanding of the time and space constraints of the Karoo-Ferrar LIP event globally and its associated perturbations to life and their associated environments and ecological niches.
Upper Jurassic outcrops in Wadi Haqil in the northern Emirate of Ras Al Khaimah offer a continuous sedimentological record of carbonate rocks in contrast with time equivalent sequences from the Emirate of Abu Dhabi characterized by intercalations of carbonates and evaporites. Belonging to the Musandam Formation, these outcrops have a huge potential for high impact paleoenvironmental studies during key Mesozoic intervals such as the not so well defined J-K boundary. This paper summarizes the sedimentology of an Upper Jurassic-Lower Cretaceous carbonate rock sequence at high resolution coupled with X-Ray fluorescence elemental analysis in order to accurately understand the temporal evolution of the local sedimentary system and the changes in the environmental conditions of deposition based on evidences of rise and falls in sea levels and the rock's siliciclastic influx.
