Modeling Uranium Transport in Koongarra, Australia: The Effect of a Moving Weathering Zone

Natural analogues are an important source of long-term data and may be viewed as naturally occurring experiments that often include processes, phenomena, and scenarios that are important to nuclear waste disposal safety assessment studies. The Koongarra uranium deposit in the Alligator Rivers region of Australia is one of the best-studied natural analogue sites. The deposit has been subjected to chemical weathering over several million years, during which many climatological, hydrological, and geological changes have taken place, resulting in the mobilization and spreading of uranium. Secondary uranium mineralization and dispersed uranium are present from the surface down to the base of the weathering zone, some 25 m deep. In this work, a simple uranium transport model is presented and sensitivity analyses are conducted for key model parameters. Analyses of field and laboratory data show that three layers can be distinguished in the Koongarra area: (1) a top layer that is fully weathered, (2) an intermediate layer that is partially weathered (the weathering zone), and (3) a lower layer that is unweathered. The weathering zone has been moving downward as the weathering process proceeds. Groundwater velocities are found to be largest in the weathering zone. Transport of uranium is believed to take place primarily in this zone. It appears that changes in the direction of groundwater flow have not had a significant effect on the uranium dispersion pattern. The solid-phase uranium data show that the uranium concentration does not significantly change with depth within the fully weathered zone. This implies that uranium transport has stopped in these layers. A two-dimensional vertically integrated model for transport of uranium in the weathering zone has been developed. Simulations with a velocity field constant in time and space have been carried out, taking into account the downward movement of this zone and the dissolution of uranium in the orebody. The latter has been modelled by a nonequilibrium relationship. In these simulations, pseudo-steady state uranium distributions are computed. The main conclusion drawn from this study is that the movement of the weathering zone and the nonequilibrium dissolution of uranium in the orebody play an important role in the transport of uranium. Despite the fact that the model is a gross simplification of what has actually happened in the past two million years, a reasonable fit of calculated and observed uranium distributions was obtained with acceptable values for the model parameters

Народне лікування деякими видами грибів

У статті зроблено спробу дослідити засоби народного лікування грибами, зокрема білими грибами й мухоморами, та лексику, яка їх репрезентує, що є джерелом не лише діалектологічних пошуків, але й етнолінгвістичних.В статье сделана попытка исследовать способы народного лечения грибами, в частности белыми грибами и мухоморами, и лексику, которая их представляет, что есть источником не только диалектологических поисков, но и этнолингвистических.In the article «Folk Treatment with Some Fungus Species» the author endeavoured to research into the means of folk treatment with funguses, edible boletuses and fly agarics in particular as well as the vocabulary which represents them and serves as a source of not only dialectological search but also ethnolinguistic one

High-concentration-gradient dispersion in porous media : experiments, analysis and approximations

Various experimental and theoretical studies have shown that Fick's law, based on the assumption of a linear relation between solute dispersive mass flux and concentration gradient, is not valid when high concentration gradients are encountered in a porous medium. The value of the macrodispersivity is found to decrease as the magnitude of the concentration gradient increases. The classical, linear theory does not provide an explanation for this phenomenon. A recently developed theory suggests a nonlinear relation between concentration gradient and dispersive mass flux, introducing a new parameter in addition to the longitudinal and transversal dispersivities. Once a unique set of relevant parameters has been determined (experimentally), the nonlinear theory provides satisfactory results, matching experimental data of column tests, over a wide range of density differences between resident and invading fluids. The lower limit of the nonlinear theory, i.e. very low (tracer) density differences, recovers the linear formulation of Fick's law. The equations describing high concentration brine transport are a fluid mass balance, a salt mass balance in combination with a nonlinear dispersive mass flux equation, Darcy's law and an equation of state. We study the resulting set of nonlinear partial differential equations and derive explicit (exact) and semi-explicit solutions, under various assumptions. A comparison is made between mathematical solutions, numerical solutions and experimental data. The results indicate that the simple explicit solution can be used to simulate experiments in a wide range of density differences, given a unique set of experimentally determined parameters. The analysis shows that enhanced flow due to the compressibility effect, which is caused by local fluid density variations, is neglectable in all cases considered. The linear formulation of Fick's law appears to give an upperbound for magnitude of the compressibility effect

Зимовий бал Тетяни Клименко

Висвітлено трудовий шлях директора Державного архіву Черкаської області Тетяни Анатоліївни Клименко, яка понад двадцять років працює в архіві.Освещён трудовой путь директора Государственного архива Черкасской области Татьяны Анатольевны Клименко, которая более двадцати лет своей жизни посвятила архивному делу.The article was written on the occasion of fiftieth birthday of the director of The State Archives of Cherkassy region Klymenko Tetyana, whose twenty years seniority is connected with Cherkassy Archives

К вопросу применения комплексных систем контроля производственного процесса на урановых шахтах

Викладено технічні, технологічні й соціальні передумови застосування комплексних систем контролю виробничого процесу на уранових шахтах.Sets out technical, technological and social conditions of application of complex process control systems in the uranium mines

Dynamic Effect in Capillary Pressure- Saturation Relationship and its Impact on Unsaturated Flow

Recent theories indicate that capillary pressure is perhaps not only a function of saturation but also rate of change. This is known as the dynamic effect. A comprehensive review of experiments reported in the literature is presented. The experiments provide ample evidence that a dynamic effect is observable and even quantifiable. The reported data are used to estimate the coefficient that arises in the theory. It was found that range of values of the dynamic coefficients spans about four orders of magnitude. To examine whether these coefficients have any practical effects on larger-scale problems, a continuum-scale simulator was constructed in which the dynamic effects are included. Results of our simulations indicated that the dynamic effect may be important for some field situations. Numerical simulators for unsaturated flow should generally include the additional term(s) associated with dynamic capillary pressure

Морфогенез структуры клеток и сосудов миокарда у экспериментальных животных с моделированным ЮРА

В статье проанализированы морфологические изменения сердечно-сосудистой системы при моделировании ювенильного ревматоидного артрита на 24 белых чистопородных крысах «Wistar». Проведено морфологическое исследование миокарда у животных с экспериментально вызванным ЮРА в зависимости от методов лечения - гормональная терапия и метаболическая коррекция. Дистрофические и деструктивные процессы миокарда в условиях данного эксперимента свидетельствуют о необходимости метаболической коррекции.In the article morphological cardiovascular system analyzed the experimentally caused juvinal rheumatoid arthritis on the 24 white breed «Wistar» rats. It was carried out morphological research of hearts of animals with rheumatoid arthritis depending on the methods of treatments – hormonal therapy and metabolic correction. Dystrophy and disturbance of cardiovascular system of this experiment testifies to necessity of metabolic correction

Characterizing the hydraulic properties of paper coating layer using FIB-SEM tomography and 3D pore-scale modeling

AbstractPaper used in the printing industry generally contains a relatively thin porous coating covering a thicker fibrous base layer. The three-dimensional pore structure of coatings has a major effect on fluid flow patterns inside the paper medium. Understanding and quantifying the flow properties of thin coating layers is hence crucial. Pore spaces within the coating have an average size of about 180nm. We used scanning electron microscopy combined with focused ion beam (FIB-SEM) to visualize the nano-scale pore structure of the paper coating layer. Post-processing of the FIB-SEM images allowed us to reconstruct the three-dimensional pore space of the coating. The 3D FIB-SEM images were analyzed in detail to obtain pore size distribution and porosity value. The permeability was estimated using the GeoDict software, based on solutions of the Stokes equation. By determining the porosity and permeability of increasingly larger domain sizes, we estimated the size of a representative elementary volume (REV) for the coating layer to be 60µm3, which is well within the volume analyzed using FIB-SEM. The estimated porosity and permeability of the REV domain were 0.34 and 0.09 mDarcy, respectively. Using the pore morphology method, capillary pressure-saturation (Pc-S) and relative permeability curves of the REV domain could be constructed next. The Pc-S curves showed that the coating had a high air entry suction, which is very favorable for printing in that ink will invade the coating as soon as it is applied to the coating. Our results are essential for macroscale modelling of ink penetration into a coating layer during inkjet printing. Macroscopic models can be valuable tools for optimization of the penetration depth and the spreading of ink on and within paper substrates

З книги "Дзеркало від писання божественного", Чернігів 1705 р. (Підготовка до друку, переклад з польської та церковно-слов'янської, коментарі Валерія Шевчука)

In recent years, the effective stress approach has received much attention in the constitutive modeling of unsaturated soils. In this approach, the effective stress parameter is very important. This parameter needs a correct definition and has to be determined properly. In this paper, a thermodynamic approach is used to develop a physically-based formula for the effective stress tensor in unsaturated soils. This approach accounts for the hydro-mechanical coupling, which is quite important when dealing with hydraulic hysteresis in unsaturated soils. The resulting formula takes into account the role of interfacial energy and the contribution of air-water specific interfacial area to the effective stress tensor. Moreover, a bi-quadratic surface is proposed to represent the contribution of the so-called suction stress in the effective stress tensor. It is shown that the proposed relationship for suction stress is in agreement with available experimental data in the full hydraulic cycle (drying, scanning, and wetting)

Новые клинические и диагностические стратегии при раке почки

Представлен анализ изменившейся клиники опухолей почки. Описаны динамика и последовательность использования новых визуализирующих методов диагностики.The analysis of the changed clinical picture of renal tumors is done. The dynamics and sequence of the new imaging techniques are described