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Introduction. In the current process of climate change, the phenomenon of unusual rainfall and flooding is causing widespread flooding and causing great loss of life and property. In addition, the most vulnerable structures are dams and reservoirs. A dam failure causes a disaster that can threaten human lives and entire socio-economic activities. There are many causes of dam failure, of which hydraulic fracturing is considered one of the most likely causes as it causes concentrated seepage leading to the risk of dam failure. Hydraulic fracturing is a process in which cracks form in soil or rock and then propagate under water pressure. Hydraulic fracturing is not a new topic, nor is it an old one, receiving a lot of attention from scientists, but it is still a controversial issue. Many opinions are given. This paper aims to summarize the mechanism of hydraulic fracturing based on previous studies and at the same time proposes some methods to prevent hydraulic fracturing in an earthen dam.Materials and methods. Literature analysis of sources related to the phenomenon of hydraulic fracturing.Results. Hydraulic fracturing is closely related to the phenomena of differential settlement of dam soils and building structures. In earth-fill dams, the phenomenon of differential settlement often occurs in the areas between the fill soil of the dam and the side masses of the dam site, fill soil and concrete structures such as culverts and spillways, foundation structural elements, the impermeable core of the dam and adjacent soil zones. Based on an analysis of the causes of hydraulic fracturing, a number of measures were proposed to reduce the risk of hydraulic fracturing.Conclusions. Hydraulic fracturing, that is, the formation of cracks and cavities in the soil mass, which contribute to the formation of concentrated seepage paths. The occurrence of hydraulic fracturing increases the likelihood of seepage instability in the dam, which affects the safety of the dam and can lead to serious damage. Implementing hydraulic fracturing prevention techniques is critical to ensuring safe dam operating conditions.

Introduction. In the current climate change conditions, the protection of irrigation structures, especially dams, is a very important task. Seepage is one of the main causes of dam failure, so it is very important to investigate the seepage regimes and find solutions to prevent dam failures as a result of the seepage processes in earth dams. In this paper, the analysis of the seepage regimes in the body of earth dams is performed by means of mathematical modelling using numerical finite element models. A homogeneous earth dam with an imperfect diaphragm on an impermeable foundation is taken as the object of study. The purpose of the study is to determine the influence of relative parameters: diaphragm height, diaphragm location in the dam body, their number. In addition, the influence of diaphragm parameters on the seepage flow through the dam body and its velocity is analyzed.Materials and methods. The study was carried out with the help of numerical modelling using PLAXIS 2D software. The model of the dam is based on typical design solutions used in practice.Results. The results of the study show that the placement of the diaphragm in the dam body reduces the seepage flow through the dam and the height of the diaphragm is inversely proportional to the seepage rate. The maximum seepage rate was recorded at the upper end of the diaphragm and its magnitude is directly proportional to the height of the diaphragm. When the diaphragm is displaced towards the downstream side, the filtration rate slightly decreases. The value of maximum velocity increases when the diaphragm is displaced towards the downstream end.Conclusions. Dam failure due to seepage can result in serious property damage and loss of life. Implementing methods that reduce seepage discharge and seepage velocities is important to ensure safe dam operating conditions

Introduction. There are many destructions of earth dams in the world due to the loss of seepage strength of soils of the dam body or foundation. The seepage stability of soils is directly related to the phenomenon of hydraulic fracturing (HF), so prevention of conditions causing hydraulic fracturing is a very important task in the design and operation of earth dams. Hydraulic fracturing is closely related to uneven settlement of the dam soils and building structures. In earth dams, the phenomenon of uneven settlement often occurs in the areas between the dam soil and the side masses of the dam site, the dam soil and concrete structures, such as culverts and spillways, foundation structural elements, the impervious core of the dam and adjacent soil zones. The article is devoted to the study of the seepage stability of soil dams in the area of round-shaped culvert spillway.Materials and methods. The study was carried out with the help of numerical modelling using Plaxis software package. The Bung Bung earth dam (Vietnam) was taken as an object of study.Results. The results of the studies showed that the normal stress around the culvert was reduced to a level much lower than the water pressure in the seepage flow with a high probability of hydraulic fracturing in the volume of soil below the spillway. Thus, hydraulic fracturing can occur in these areas. The article proposes two structural approaches to prevent hydraulic fracturing: to change the cross-sectional shape of the culvert and to install a clay jacket around the spillway. Both approaches were tested numerically. The calculations demostrated that the application of both methods reduces the conditions for the occurrence of hydraulic fracturing near the culvert.Conclusions. Dam failure due to hydraulic fracturing can cause serious damage. The implementation of methods to prevent hydraulic fracturing is important to ensure the safe dam conditions.

The East Australian Current (EAC) exhibits significant variability across a wide range of spatial and temporal scales, from mesoscale eddies and meanders to seasonal, interannual, and decadal fluctuations in its intensity, pathway, and influence on the continental shelf circulation. Understanding and monitoring this variability is crucial because the EAC plays an important role in controlling shelf dynamics, regional circulation, coastal weather and global climate patterns. As such, two high-frequency (HF) coastal radar systems have been deployed on the east coast of Australia to measure surface currents upstream and downstream of the East Australian Current (EAC) separation point. The multi-year radar dataset (spanning 4–8 years) is presented here and its use is demonstrated to assess the spatial and temporal variability of the EAC and the adjacent continental shelf circulation, ranging from seasonal to interannual scales. The dataset is gap-filled using a 2dVar approach (after rigorous comparison with the traditional unweighted Least-squares fit (LS) method). Additionally, we explore the representation depth variability of the observations by comparing the data with surface Lagrangian drifter velocities (with and without depth drogues). The multi-year radar-derived surface current dataset, which was validated using short-term drifter and long-term current meter observations, revealed that the local upstream circulation is strongly dominated by the EAC's annual cycle, peaking in the austral summer. The analysis using 8 years of upstream data revealed the period of the EAC intensification at around 3–5 years. The interannual variability of the poleward transport downstream was driven by the intrinsic variability of the jet. This dataset which continues to be collected, complemented by numerical simulations and in-situ measurements, will provide a comprehensive view of the EAC's variability and its impact on the broader regional circulation dynamics which can be used for a range of dynamical investigations. [ABSTRACT FROM AUTHOR]

Objective: S100A4 is a DAMP protein. S100A4 is overexpressed in patients with systemic sclerosis (SSc), and levels correlate with organ involvement and disease activity. S100A4−/− mice are protected from fibrosis. The aim of this study was to assess the antifibrotic effects of anti‐S100A4 monoclonal antibody (mAb) in murine models of SSc and in precision cut skin slices of patients with SSc. Methods: The effects of anti‐S100A4 mAbs were evaluated in a bleomycin‐induced skin fibrosis model and in Tsk‐1 mice with a therapeutic dosing regimen. In addition, the effects of anti‐S100A4 mAbs on precision cut SSc skin slices were analyzed by RNA sequencing. Results: Inhibition of S100A4 was effective in the treatment of pre‐established bleomycin‐induced skin fibrosis and in regression of pre‐established fibrosis with reduced dermal thickening, myofibroblast counts, and collagen accumulation. Transcriptional profiling demonstrated targeting of multiple profibrotic and proinflammatory processes relevant to the pathogenesis of SSc on targeted S100A4 inhibition in a bleomycin‐induced skin fibrosis model. Moreover, targeted S100A4 inhibition also modulated inflammation‐ and fibrosis‐relevant gene sets in precision cut SSc skin slices in an ex vivo trial approach. Selected downstream targets of S100A4, such as AMP‐activated protein kinase, calsequestrin‐1, and phosphorylated STAT3, were validated on the protein level, and STAT3 inhibition was shown to prevent the profibrotic effects of S100A4 on fibroblasts in human skin. Conclusion: Inhibition of S100A4 confers dual targeting of inflammatory and fibrotic pathways in complementary mouse models of fibrosis and in SSc skin. These effects support the further development of anti‐S100A4 mAbs as disease‐modifying targeted therapies for SSc. [ABSTRACT FROM AUTHOR]

Objectives Our previous studies have demonstrated that the Damage Associated Molecular Pattern (DAMP) protein, S100A4, is overexpressed in the involved skin and peripheral blood of patients with SSc. It is associated with skin and lung involvement, and disease activity. By contrast, lack of S100A4 prevented the development of experimental dermal fibrosis. Herein we aimed to evaluate the effect of murine anti-S100A4 mAb 6B12 in the treatment of preestablished experimental dermal fibrosis. Methods The effects of 6B12 were assessed at therapeutic dosages in a modified bleomycin-induced dermal fibrosis mouse model by evaluating fibrotic (dermal thickness, proliferation of myofibroblasts, hydroxyproline content, phosphorylated Smad3-positive cell count) and inflammatory (leukocytes infiltrating the lesional skin, systemic levels of selected cytokines and chemokines) outcomes, and transcriptional profiling (RNA sequencing). Results Treatment with 7.5 mg/kg 6B12 attenuated and might even reduce pre-existing dermal fibrosis induced by bleomycin as evidenced by reduction in dermal thickness, myofibroblast count and collagen content. These antifibrotic effects were mediated by the downregulation of TGF-β/Smad signalling and partially by reducing the number of leukocytes infiltrating the lesional skin and decrease in the systemic levels of IL-1α, eotaxin, CCL2 and CCL5. Moreover, transcriptional profiling demonstrated that 7.5 mg/kg 6B12 also modulated several profibrotic and proinflammatory processes relevant to the pathogenesis of SSc. Conclusion Targeting S100A4 by the 6B12 mAb demonstrated potent antifibrotic and anti-inflammatory effects on bleomycin-induced dermal fibrosis and provided further evidence for the vital role of S100A4 in the pathophysiology of SSc. [ABSTRACT FROM AUTHOR]