Durability of Cement and Ash Mortars with Fluidized and Siliceous Fly Ashes Exposed to HCl Acid Environment over a Period of 2 Years

The paper presents results of research on the impact of fly ash from fluidized bed combustion (FBC) of lignite, used in quantities of 30 and 45% by mass, and the mixture of FBC and silicious fly ash in amount of 45% by mass, on properties of cement–ash mortars. Mortars were exposed to aggressive environment of 1, 3, and 5% HCl solutions for 2 years. Mortars containing 45% FBC exposed to 1% HCl solution (pH = 2) showed the highest durability from among other mortars. The growth of their strength observed after 90 days of testing in 1% HCl environment, as well as the lowest drop of strength after 730 days of exposure to this environment, resulted from the reduced amount of large pores from 20 to 200 nm in mortars containing fly ash, with simultaneous growth of smaller pores of <20 nm during testing. A beneficial effect has been demonstrated of FBC addition to cement on properties of cement–ash mortars exposed to the aggressive impact of the HCl. Mortars with FBC fly-ash content increased to 45% by mass showed higher strength values, smaller differences in linear and mass changes, and increased durability in an aggressive environment observed during 730 days of testing.

NUMERICAL AND EXPERIMENTAL MODELING OF PROPAGATION OF LONGITUDINAL FRACTURES IN MULTI-STAGE HYDRAULIC FRACTURING WITH VISCOUS FLUID

The experimental and numerical modeling of curvilinear propagation of hydraulic fractures driven by viscous fluid is implemented. The trajectories of simultaneous growth of 2-5 fractures from the boundary of a circular opening are presented in plane elasticity. The influence of the fluid viscosity on the fracture trajectory is analyzes. The causes of initiation of main fracture and shut-down of other fractures are revealed. The attempts are made to find such conditions that simultaneous growth of a few main fractures is possible by varying lengths and orientation angles of initiation fractures in the external nonuniform field of compression. The experimental modeling of hydraulic fractures was carried out using blocks made of concrete and organic glass. There were 3 to 5 initiation fractures. The influence of the breakdown fluid viscosity on the number of the main fractures is illustrated. Hydraulic fracturing with a plastic material allowed simultaneous growth of 3 and 4 fractures within a block. The experimental modeling data and the calculation results are compared.

Seed Quality of Paddy Variety (Oryza sativa L.) Resistant to Vegetative Phase Drought Stress

Drought is an abiotic stress that can affect paddy yields by inhibiting growth, thereby reducing the quality of the seeds produced. This study aimed to find out the best seed quality of several paddy varieties produced from the plants experiencing drought stress in the vegetative phase. The varieties used in the study were Inpago 12, Unsoed 1, Inpago 4, Inpago 5, Inpago 9, Inpago 8, Inpago 10, Inpara 8, Inpara 9, Rindang 1, Rindang 2, Situ Patenggang, Towuti, and Batu Tegi. The drought stress was applied to the vegetative phase of the plant by reducing the intensity of water supply (63.5% moisture content), then the resulting seeds were tested in the laboratory. The results of the study showed that the highest seed quality value in the drought stress treatment of the vegetative phase were the Inpara 8 variety, followed by the Towuti variety with 93.33% and 88% germination values, 82.67% and 70% simultaneous growth, 12.11% and 8.44% germination rate, 64% and 64% germination strength, and 18.99 and 16.83 vigor indexes. Meanwhile, the lowest seed quality was the Inpago 8 variety with 26% germination value, 21.33% simultaneous growth, 1.33% germination speed, 3.33% germination strength, and 2.71 vigor index. Among all the varieties tested, the Inpara 8 and Towuti are those with the best seed quality values ​​after experiencing drought stress during the vegetative phase.

Nativism

Although the focus of this chapter is a particular recent photographer, its broader concern is with how performative African identities have been and continue to be imagined as anatomically and culturally generalized bodies. Several writers have identified the simultaneous growth of photography, ethnography, and colonizing projects from the nineteenth century. The photographed subject was frozen as an object for others’ scrutiny, with photography reinforcing the huge divide between the meanings attached to the surfaces of the bodies of African people and ideas about whiteness and the West. The chapter focuses on how anthropological constructs and codes perist in ostensibly postcolonial and counterhegemonic representations. It analyzes the contemporary photographs of the internationally acclaimed South African photographer Zanele Muholi, especially images from her “Faces and Phases” photographs of black lesbians and transmen. On one hand, the portraits are powerful political statements: they portray the dignity and courage of certain lesbians and transmen, make a marginalized community visible in a heterosexist and racist public sphere, and gesture toward meanings of African identities that are radically at odds with both colonial and (patriarchal) nationalist identities. On the other hand, viewers are invited to recognize the agency and public visibility of the subject in ways similar to how viewers of colonial and nationalist performances have been encouraged to recognize and categorize the bodies of authentic African women and men.

Is it possible to replenish oil in abandoned fields due to the interaction of hydrothermal solutions with enclosing bituminous and carbonous rocks? (Experiment with the participation of fluid inclusions)

The article considers the possibilities of oil and gas replenishment in previously worked out fields on the basis of experimental data on the interaction of bituminous and carbonaceous rocks with hydrothermal solutions and the simultaneous growth of quartz with fluid inclusions in them. These solutions can generate and transport oil and gas in pre-critical, sub- and supercritical states. The data obtained confirm the ideas of a number of petroleum geochemists about the migration of liquid hydrocarbons in the Earth’s interior in the form of high-temperature homogeneous, including supercritical fluids, and also explains the possibility of deep metamorphism of oil and the formation of the deepest fields of dry gas and graphite. It is especially important that the results of experimental studies using synthetic water-hydrocarbon inclusions make it possible to state that depleted oil fields can replenish lost oil and gas due to the interaction of hydrothermal solutions with the surrounding host bituminous and carbonaceous rocks.