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The efficiency of utilising an alkaline-surfactant-polymer (ASP) flooding technique for enhanced oil recovery is primarily reliant on the middle-phase microemulsion that forms between the ASP solution and oil. This microemulsion phase exhibits ultralow interfacial tensions, contributing to increased oil recovery. In this study, an optimal experimental design and response surface methodology were employed to predict the ideal concentration of chemicals in the ASP solution for achieving maximum microemulsion quality. Subsequently, the optimised ASP formulation was tested on 10 core flooding experiments to determine the most effective injection volume. The findings revealed that the optimal concentration of surfactants in the ASP solution was 0.57 wt%, while the effective injection volume reached 19.47% of the pore volume. [Received: July 14, 2022; Accepted: July 14, 2023]

This study modelled a petroleum system to analyse the history of basin evolution, maturity, and hydrocarbon generation in the deepwater of the Phu Khanh Basin, offshore Vietnam. The paleo-heat flow, surface-water interface temperatures, and paleo water-depth were modelled using existing wells occurring in shallow to deep marine environments. Based on the geochemical analysis, the Oligocene and Lower-Middle Miocene source rocks are predominantly a mixture of type II and type III kerogens, with differences in distribution and maturation level. In the Phu Khanh Basin, hydrocarbon generation started during the Early Miocene. Petroleum migrated to a trap and accumulated in an uplift structure in the sandstone and carbonate reservoirs of the Lower Miocene formation. The results of this study can assist in defining the distribution of reservoir locations for future field development planning in the Phu Khanh Basin. [Received: March 28, 2020; Accepted: August 7, 2020]

This study aims to develop a biocompatible and bioactive food-packaging composite film material. The material is based on bacterial cellulose (BC) microfibers from coconut jelly biomass combined with olive oil as a carrier of antibacterial properties. A composite membrane was fabricated with 20%, 30%, and 40 wt % glycerol and separately impregnated with 1%, 2%, and 3 wt % olive oil in the presence of BC. The results of SEM image structure and morphology show that the membrane was successfully fabricated with uniform distribution of BC, without losing its natural structure. The film was initially applied to preserve apples, and the research results showed that the mass index did not change significantly (ranging from 1.13 to 5.1 g); the hardness through the bearing test results showed a decrease. The preservation time of the composite membranes, which are based on bacterial cellulose combined with glycerol and vegetable residues, extends up to 20 days. The membrane with the highest concentration of vitamin C is soaked in BC/glycerol 30%/olive oil 2% membrane and the lowest is soaked in BC membrane.

This study estimates the shear friction coefficient from shear friction angles for the prediction of slip tendencies in the Tuy Hoa–Vung Tau region of Southern Vietnam. A dataset consisting of measured data of 355 fractured planes, striations, and unconformities in coastal areas as well as 239 offshore faults was analyzed based on the principles of statistical probability. As a result, 138 friction angles for the onshore and offshore faults were calculated based on shear fracture conjugate pairs. The goodness-of-fit test was used to define the probability distribution of the friction angles, which had a normal distribution. The acceptable average of friction angles for the onshore region with a reliability of more than 95% were in the range of 25.8–31.5°, which corresponds to frictional coefficients of 0.48–0.61. The acceptable average friction angles for the offshore region were relatively low at 23–31°, which corresponds to a frictional coefficient of 0.42–0.60. Owing to the heterogeneity of the fault system, the median value (19.12°) should be used as the lowest threshold value for slipping faults at all conditions. The recommended applicable average friction angles are 28.65° and 27° for the onshore and offshore regions, respectively. The estimation of the frictional coefficients is highly reliable, and it can be applied to other subsurface resource exploitation projects within the study area.

Plant-based vaccines have been produced in transgenic plants including tobacco, potatoes, corn, and rice. However, these plants are not suitable for administration without cooking. To overcome this obstacle, a fusion gene encoding the synthetic enterotoxigenic Escherichia coliheat-labile enterotoxin B subunit genetically fused with a synthetic neutralizing epitope of porcine epidemic diarrhea virus (sLTB-sCOE) was introduced into lettuce cells (Lactuca sativa) by Agrobacterium-mediated transformation methods. The integration and expression of the sLTB-sCOE fusion gene was confirmed in transgenic lettuce by genomic DNA PCR amplification and Northern blot analysis, respectively. Synthesis and assembly of the LTB-COE fusion protein into oligomeric structures with pentamer size were observed in transgenic plant extracts by Western blot analysis with anti-LTB or anti-COE antibodies. The binding of plantproduced LTB-COE to intestinal epithelial cell membrane glycolipid receptors was confirmed by GM1-ganglioside enzyme-linked immunosorbent assay (GM1-ELISA). Based on the ELISA results, LTB-COE fusion protein made up about 0.026∼0.048% of the total soluble protein in the transgenic lettuce leaf tissues. The synthesis and assembly of LTB-COE monomers into biologically active oligomers in transgenic lettuce leaf tissues demonstrates the feasibility of using uncooked edible plant-based vaccines for mucosal immunization.

Translations of relational schemas are extended to the set of functional and join dependencies. A basic theorem on the representation of the closure of an attribute subset is proved.