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Point cloud modeling of rock slopes using LIDAR and Structure-from-Motion digital stereophotogrammetry provides,at a minimum, thousands of facets and facet normals that can be used to identify the densities of orientations of rock massdiscontinuities, the geometries of potentially removable blocks, and the character of the excavation face. As part of the EngineeringGeology graduate curriculum at the Civil and Environmental Engineering program at the University of California, Berkeley we teachgraduate students an integrated methodology for [a] gathering point cloud information be laser or camera; [b] computing facets andfacet normals form point clouds for stereonet presentation and geometric analysis of block dimension; [c] extract rock massdiscontinuities from stereonet data to analyze key blocks, assess discontinuous deformation analysis (DDA) behavior, and modelrock slope stability. These new methods require a suite of different software tools discussed in the paper to move through the workflowprocess. Computational rock mechanics provides data sets that are orders of magnitude richer in detail and result in betterunderstanding of rock slope and tunnel key block behavior. Full application of computational rock mechanics methods should reducethe cost of bolting by identifying critical support orientations and design loads.

The connection between the Late Bronze Age (LBA) Aegean costumes and social, cultural and political changes is a rather unexplored topic. Probably the only exception are kilts, the connection of which to such changes on Crete during the 15th century BCE remains a commonly discussed topic in studies focusing on the LBA Aegean iconography and other data sets. However, many questions remain open and the topic is far from exhausted. In this paper I build on the work of various scholars who have studied LBA Aegean kilts in the context of social, political and cultural changes. I diachronically study the changes in the representations of kilts since the beginning of the LBA in the Aegean until the end of the Palatial period on the Greek Mainland (ca. 1700/1600–1200 BCE). Moreover, I examine the spatial distribution of specific kilt types in different periods. In cases of several different kilt types appearing in contemporary contexts in the same region, I explore whether similar costumes might have had different social connotations within the same communities. Moreover, I examine the influence of elite power structures and socio-political changes on the perception of kilts. However, I do not observe kilts as passive reflections of specific social, cultural and political contexts, but rather as material forms actively used in the creation of social realities. [ABSTRACT FROM AUTHOR]

A complete inventory of 16 mineral type localities and 1 rock type locality in Romania, as well as their assessed geoheritage characteristics and values are presented for the first time. Thirty-nine mineral species, one chemical element and one common rock type were discovered, described and named in Romania. Most of these are closely linked to traditional mining areas: the Baia Mare region, the Apuseni Mts. and the Banat region. Three mineral type localities are outstandingly rich: Săcărâmb/Nagyág in the southern Apuseni Mts. (8 new minerals), Baia Sprie/Felsőbánya in the Baia Mare region (6 new minerals), and Băița Bihor/Rézbánya in the Northern Apuseni Mts. (6 new minerals). The scientific, educational and touristic value and significance of the type localities regarded as „geosites” and „geodiversity sites” are discussed. Based on the quantitative assessment of the scientific, educational and touristic values, the type localities were hierarchically classified, Baia Sprie, Săcărâmb and Măgura Uroiului being the highest ranked. From the geoconservation perspective, site protection and valuation strategies at local and/or regional scales are envisaged. [ABSTRACT FROM AUTHOR]

Inflammation is implicated in the etiology of obesity-related diseases. Thromboxane-prostanoid receptor (TPR) is known to play a role in mediating an inflammatory response in a variety of cells. Gut-derived lipopolysaccharide (LPS), a TLR4 agonist, is elevated in obesity. Moreover, free fatty acids (FFAs) are important mediators of obesity-related inflammation. However, the role and mechanisms by which TPR regulates the inflammatory response in human immune cells remain unclear. We sought to determine the link between TPR and obesity and the role/mechanisms by which TPR alters LPS- or stearic acid (SA)-induced inflammatory responses in PBMCs. Cells were pre-treated with agents blocking TPR signaling, followed by treatment with LPS or stearic acid (SA). Our findings showed that TPR mRNA levels are higher in PBMCs from individuals with obesity. Blockade of TPR as well as ROCK, which acts downstream of TPR, attenuated LPS- and/or SA-induced pro-inflammatory responses. On the other hand, TPR activation using its agonist enhanced the pro-inflammatory effects of LPS and/or SA. Of note, the TPR agonist by itself elicits an inflammatory response, which was attenuated by blocking TPR or ROCK. Our data suggest that TPR plays a key role in promoting an inflammatory response in human PBMCs, and this effect is mediated via TLR4 and/or ROCK signaling. [ABSTRACT FROM AUTHOR]

This study proposes a fractal damage calculation method that understands the blasting damage laws at the macroscopic, mesoscopic, and microscopic scales of rock. The findings indicated that the binary graph derived from the Moments algorithm can represent minute cracks and exhibit less noise within the image. This makes the algorithm suitable for identifying and extracting macroscopic damage. A three-dimensional (3D) reconstruction technique offers visualization of the macroscopic rock damage following an explosion. The extent of this damage is quantitatively assessed using the box dimension. In addition, a multifractal method is introduced to comprehensively evaluate the macroscopic and mesoscopic damage to rock post-blasting. The multifractal dimension calculations analysis reveals that the mesoscopic damage to rock following blasting is a significant factor in the overall blasting damage. The box dimension presents a straightforward, macroscopic evaluation method for assessing 3D macroscopic fractures. On the other hand, the multifractal dimension can more accurately evaluate the macroscopic cracks and mesoscopic damage resulting from blasting. Both methods emphasize different aspects and are equally effective for assessing blasting damage. Highlights: This study proposes a fractal damage calculation method that understands the blasting damage laws at the macroscopic, mesoscopic, and microscopic scales of rock. The box dimension is a straightforward macroscopic evaluation method for assessing 3D macroscopic fractures. The multifractal dimension more accurately evaluates the macroscopic cracks and mesoscopic damage from blasting. After ordinary charge initiations, blasting damage exhibited a bimodal distribution along the borehole's axis, peaking in the charging section. [ABSTRACT FROM AUTHOR]

Creep tests under constant stress are among the most important tests for investigating the time-dependent behavior of rock. In previous studies, creep tests were conducted under various loading and environmental conditions; however, it was very difficult to demonstrate accelerating creep at failure at stresses less than 50% of strength in conventional creep tests. In this study, a new test method is proposed that combines an alternating loading-rate test and a creep test in the post-failure region. The accelerating creep as well as the loading-rate dependence of strength were successfully obtained simultaneously from a single specimen. This test method was applied to three rock types under dry and wet conditions. The results of Sanjome andesite under both dry and wet conditions, Kimachi sandstone under dry conditions, and Tage tuff under dry conditions showed a similar relationship between creep strain, creep strain rate, and residual time (i.e., creep lifetime minus elapsed time), from high to low creep stress levels, and a close relationship between accelerating creep and the loading-rate dependence of strength. Further, the mechanism responsible for the time dependence was found not to change significantly from high to low stress levels. In contrast, different results were obtained when high and low creep stress levels were compared in Kimachi sandstone and Tage tuff under wet conditions. The larger increase in creep strain with increasing creep strain rate at lower creep stress levels was related to the shape of the stress–strain curve in the post-failure region. Highlights: A new test method was proposed that combined an alternating loading-rate test and a creep test in the post-failure region. Accelerating creep at failure was discussed in detail based on the test results from high to low creep stress levels. Test results showed a close relationship between accelerating creep and the loading-rate dependence of strength. [ABSTRACT FROM AUTHOR]

Fatigue damage can occur in surface rock engineering due to various factors, including earthquakes, blasting, and impacts. The underlying cause for the variations in physical and mechanical properties of the rock resulting from impact loading is the alteration in the internal pore structure. To investigate the evolution characteristics of the pore structure under impact fatigue damage, red sandstone subjected to cyclic impact compression by split Hopkinson pressure bar (SHPB) was analyzed using nuclear magnetic resonance (NMR) technology. The parameters describing the evolution of pore structure were obtained and quantified using fractal methods. The development of the pore structure in rocks subjected to cyclic impact was quantitatively analyzed, and two fractal evolution models based on pore size and pore connectivity were constructed. The results indicate that with an increasing number of impact loading cycles, the porosity of the red sandstone gradually increases, the T2 cutoff (T2c) value decreases, the most probable gray value of magnetic resonance imaging (MRI) increases, the pores' connectivity is enhanced, and the fractal dimension decreases gradually. Moreover, the pore distribution space tends to transition from three-dimensional to two-dimensional, suggesting the expansion of dominant pores into clusters, forming microfractures or even macroscopic fissures. The findings provide valuable insights into the impact fatigue characteristics of rocks from a microscopic perspective and contribute to the evaluation of time-varying stability and the assessment of progressive damage in rock engineering. [ABSTRACT FROM AUTHOR]

Background: Rho kinase (ROCK) pathway plays a critical role in post‐COVID‐19 pulmonary fibrosis (PCPF) and its intervention with angiotensin‐converting enzyme 2 (ACE2) and vascular endothelial growth factor (VEGF) will be a potential therapeutic target. Objectives: The present study was conducted to investigate the efficacy of zoledronate (ZA) on carbon tetrachloride (CCl4) induced pulmonary fibrosis (PF) in rats through targeting ACE2, ROCK, and VEGF signaling pathways. Methods: Fifty male Wistar rats were divided into five groups: control, vehicle‐treated, PF, PF‐ZA 50, and PF‐ZA 100 groups. ZA was given in two different doses 100 and 50 μg/kg/week intraperitoneally. After anesthesia, mean arterial blood pressure (MBP) was measured. After scarification, lung coefficient was calculated. Lung levels of ACE 2, interleukin‐1β (IL‐1β), transforming growth factor‐β (TGF‐β), VEGF, glutathione (GSH), and superoxide dismutase (SOD) were measured. Expression of ROCK, phosphorylated myosin phosphatase target subunit 1 (P‐MYPT1), and matrix metalloproteinase (MMP‐1), along with histopathological changes and immune‐histochemical staining for lung α‐smooth muscle actin (α‐SMA), tumor necrosis factor‐alpha (TNFα), and caspase‐3, were evaluated. Results: ZA significantly prevented the decrease in MBP. ZA significantly increased ACE2, GSH, and SOD and significantly decreased IL‐1β, TGF‐β, and VEGF in lung in comparison to PF group. ZA prevented the histopathological changes induced by CCl4. ZA inhibited lung expression of ROCK, P‐MYPT1, MMP‐1, α‐SMA, TNFα, and caspase‐3 with significant differences favoring the high dose intervention. Conclusion: ZA in a dose‐dependent manner prevented the pathological effect of CCl4 in the lung by targeting mevalonate pathway. It could be promising therapy against PCPF. [ABSTRACT FROM AUTHOR]

Under compressive loading, rocks emit electromagnetic waves, and monitoring electromagnetic signals has become a key means of predicting dynamic rock disasters. To understand how dynamic potential is generated in rocks under compressive loading, the relationship between the compressive loading (P) and the stimulated potential (E) is seen as a circuit system (H(t)). A circuit analysis model has been established to study how rock particles restructure under compressive loading. Experimental tests were conducted to measure the input excitation (E) and output response (Uσ(t)) or (Iσ(t)) of the rock specimens, with four types of rocks being tested. The experiments revealed that voltage, current, frequency, and impedance changed during the particle reorganization process under compressive loading, showing that the electromagnetic radiation of the rock specimens mainly came from the current generated by the internal particle reorganization. The intensity of electromagnetic radiation was found to depend on the load size and dynamic impedance (Zσ), with the dynamic impedance (Zσ) consisting of the microelement total resistance (Rσ), capacitance (Cσ), and inductance (Lσ). The variation of dynamic impedance (Zσ) is related to the rock type. The research findings have contributed to elucidating the mechanism of electromagnetic radiation generated by rocks under load. [ABSTRACT FROM AUTHOR]

The introduction of thousands of wind turbines along the North American Atlantic continental shelf over the next decade will constitute the largest regional change in marine substrates since the retreat of the Laurentide Ice Sheet over 14,000 years ago. Here, two large data sets, SMAST drop camera survey (242,949 samples, 2003 to 2019) and the US Geological Survey databases (27,784 samples, 1966 to 2011), are combined to derive sea floor surficial substrate probability maps for the Northeastern US continental shelf from Virginia Beach to the Gulf of Maine to 300 m depth (218,571 km2). Geostatistical models were used to estimate the probability of five geologic and one biogenic substrate types being present at a 250 m resolution, and the proportional contribution of each substrate type to the seabed composition at a 500 m resolution. By providing the first synoptic maps depicting the probability of a particular substrate or combination of substrates occurring at any location on the Northeastern US continental shelf, including planned wind energy sites, we aim to (1) provide insights regarding how substrates in the areas selected for wind energy development compare with other locations, (2) motivate the development of a priori expectations for ecosystem changes to inform monitoring and research efforts going forward, and (3) to provide a baseline characterization of the Northeastern US continental shelf surficial substrates to support robust examination of the future changes observed in areas impacted by wind energy installations. [ABSTRACT FROM AUTHOR]

More than 650 reversible and irreversible post-translational modifications (PTMs) of proteins have been listed so far. Canonical PTMs of proteins consist of the covalent addition of functional or chemical groups on target backbone aminoacids or the cleavage of the protein itself, giving rise to modified proteins with specific properties in terms of stability, solubility, cell distribution, activity, or interactions with other biomolecules. PTMs of protein contribute to cell homeostatic processes, enabling basal cell functions, allowing the cell to respond and adapt to variations of its environment, and globally maintaining the constancy of the milieu interieur (the body's inner environment) to sustain human health. Abnormal protein PTMs are, however, associated with several disease states, such as cancers, metabolic disorders, or neurodegenerative diseases. Abnormal PTMs alter the functional properties of the protein or even cause a loss of protein function. One example of dramatic PTMs concerns the cellular prion protein (PrPC), a GPI-anchored signaling molecule at the plasma membrane, whose irreversible post-translational conformational conversion (PTCC) into pathogenic prions (PrPSc) provokes neurodegeneration. PrPC PTCC into PrPSc is an additional type of PTM that affects the tridimensional structure and physiological function of PrPC and generates a protein conformer with neurotoxic properties. PrPC PTCC into PrPSc in neurons is the first step of a deleterious sequence of events at the root of a group of neurodegenerative disorders affecting both humans (Creutzfeldt-Jakob diseases for the most representative diseases) and animals (scrapie in sheep, bovine spongiform encephalopathy in cow, and chronic wasting disease in elk and deer). There are currently no therapies to block PrPC PTCC into PrPSc and stop neurodegeneration in prion diseases. Here, we review known PrPC PTMs that influence PrPC conversion into PrPSc. We summarized how PrPC PTCC into PrPSc impacts the PrPC interactome at the plasma membrane and the downstream intracellular controlled protein effectors, whose abnormal activation or trafficking caused by altered PTMs promotes neurodegeneration. We discussed these effectors as candidate drug targets for prion diseases and possibly other neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

In engineering construction, rocks broken by mining and tunnel excavation are often used as concrete aggregates, and rock fragmentation influences the elastic modulus of concrete. To improve the efficiency of rock breaking and the application effects of rock aggregates, this work proposed a method for evaluating rock breakability and the impact of the produced aggregate on the elastic modulus of concrete. The breakability of rock and its impact on concrete performance were studied based on fractal theory. A physical parameter characterization method was proposed to quickly compare the difficulty of rock fragmentation, characterizing the breakability of rocks and the processability of aggregates. The relationship between the relative specific surface area of aggregates and their main physical properties was established. The influence of rock breakability on the elastic modulus of concrete was analyzed through laboratory tests of uniaxial compression on concrete. Results demonstrate that the content of firm components in the rock mineral composition is significant, and the particle content of the main mineral components is positively correlated with the relative specific surface area of the fragmented aggregates. The relative specific surface area of the aggregates is negatively correlated with the fineness modulus and apparent density of the aggregates and positively correlated with the stone powder content and crushing index. The relative specific surface area of the aggregates shows a linear decreasing relationship with the water-to-binder ratio and elastic modulus. For C30 (C40) concrete, the water-to-binder ratio increased by 19.4% (21.4%), and the static compressive elastic modulus increased by 22.5% (25.0%). This study provides a particular guiding significance for the rapid and effective breaking of rock bodies and the resource utilization of aggregates. [ABSTRACT FROM AUTHOR]

The Niger Delta, a cornerstone of Nigeria's oil and gas sector, plays a significant role in the Nation's energy landscape. This research concentrates on enhancing reservoir characterization, specifically emphasizing advancing rock facies classification. Employing advanced machine-learning methodologies and a dataset from 12 wells containing crucial well log parameters, such as Gamma Ray, Resistivity Micro-Spherical, Volume of Shale, Resistivity Deep, Resistivity Medium, Density, and Porosity, we conducted a rigorous evaluation of various classification models. The Random Forest algorithm emerged as the optimal choice, achieving an impressive F1 score of 0.93 and an accuracy of 0.93 on the cross-validation set. A meticulous analysis of identified facies classes, including Shale, Lower Shoreface, Middle Shoreface, Upper Shoreface, Transition Shoreface, Over Bank, and Channel, through confusion matrices, offered profound insights into the Model's efficiency. Feature importance analysis underscored the critical role of variables such as volume of shale, gamma ray, porosity, and bulk density in driving accurate predictions. This research significantly advances subsurface exploration in the Niger Delta, highlighting the effectiveness of machine learning for geologic characterization within the region's intricate geological landscape. [ABSTRACT FROM AUTHOR]

Purpose. Development of highly effective composite diamond-containing materials based on WC‒Co matrices with CrB2 additives with improved mechanical and performance properties for creating matrices of rock-cutting tools for drilling oil and gas wells. Methodology. The assigned tasks were solved using a comprehensive research method, which includes a review and synthesis of literary sources; conducting analytical studies of existing composite diamond-containing materials; scanning electron microscopy (SEM) methods; X-ray phase analysis methods; calculation of experimental data by the Rietveld method, developed for the characterization of crystalline materials by powder X-ray diffraction; the Williamson-Hall technique. Findings. It has been established that the structure of the initial 94 %WC–6 %Co composite consists of WC phases with crystal lattice parameters a = 0.2906, c = 0.2837 nm and graphite with lattice parameters a = 0.2461, c = 0.6708 nm. The addition of chromium diboride to the composition of the 94 %WC–6 %Co sample leads to the decomposition of the CrB2 phase and the formation of the final phase composition: WC + B2CoW2 + Cgraphite + solid solution of tungsten and carbon in cobalt. Originality. It was shown for the first time that if the WC–6Co system is characterized by insignificant solubility of the components in each other, then in the WC–Co–CrB2 system there is a significant mutual dissolution of the components, which leads to a decrease in their sizes during the sintering process. When the threshold concentration (~4 %) of chromium diboride in the charge is reached, phases of the hexagonal WC group and new phases of the orthorhombic group B2CoW2 and amorphous carbon inclusions begin to form in the structure of the composite. Practical value. A highly effective composite diamond-containing material based on WC‒Co matrices with CrB2 additives with increased mechanical (hardness, crack resistance, compressive and bending strength) and operational (wear resistance, productivity) properties has been developed to create a highly effective rock-cutting tool for drilling oil and gas wells. [ABSTRACT FROM AUTHOR]

Historicamente a arte esteve em vários momentos atrelada aos movimentos que se mostravam de resistência a algum tipo de opressão imposta. Dentre as mais diversas manifestações artísticas, certamente a música é a que consegue alcançar mais pessoas, principalmente após o advento dos meios de comunicação de massa. A partir dessas questões iniciais pretende-se investigar as relações que a música-gênero Rock, sobretudo a de autoria feminina, estabelece com a arte-educação desenvolvida em ambientes escolares e em coletivos culturais, tornando-se uma atividade criadora onde educadores e educandos trocam experiências, conseguem transmitir sua realidade social, seus anseios, sonhos e buscam resistir a tantas formas de coerção por parte da sociedade atual. Assim, o presente texto expõe os passos iniciais da pesquisa a ser desenvolvida no biênio 2023-2024 no curso de Mestrado em Educação e Cultura (PPGEDUC/ UFPA Cametá/Pará). Dessa forma, o texto traz os referenciais teóricos e autores/as estudados, bem como as colaborações destes na construção, desconstrução e reconstrução de conceitos, práticas e saberes da arte rock.

Abstract To gain insights into the spatial distribution of non-penetrating cracks during the rock fracture process, a comprehensive uniaxial compression test is conducted on cubic gypsum specimens (100 mm × 100 mm × 100 mm) containing two non-penetrating cracks. The two pre-formed cracks are rectangular, with dimensions of 25 mm length, 2 mm width, and depths of 80 mm and 35 mm on adjacent sides of the specimen. The depth of the 80 mm crack can be adjusted from 0° to 150° in increments of 30°, while the other is fixed at a 45° angle. The results show that the spatial distribution of non-penetrating cracks can significantly influence the strength of the specimen. Initially, the strength of the specimen exhibits an upward trend and subsequently declines as the pre-crack inclination angle of the main rupture plane increases, ultimately reaching its pinnacle at 90°. The total percentage of tensile cracks in specimens with different inclinations are found to be 57%, 57%, 63%, 77%, 68%, and 61%, respectively. This change aligns seamlessly with the fluctuation in specimen strength as influenced by the angle of inclination. Non-penetrating cracks can also induce spalling on the specimen surface and give rise to anti-wing cracks, thereby exacerbating the spalling on the specimen surface. The inclinations of non-penetrating cracks can inevitably exert a certain influence on the propagation of neighboring non-penetrating cracks. Additionally, the macro-scale shear fracture of the specimen often occurs on the side of the non-penetrating crack that is deeper. The curved tensile fracture surface formed by the extension of the non-penetrating crack bears resemblance to the non-penetrating region in its ability to somewhat restrain the propagation of new cracks. Even under uniaxial compression, the spalling surface of the specimen containing spatial non-penetrating cracks frequently exhibits fracture characteristics belonging to I-III mode fracture, while its interior may display characteristics belonging to I-II-III mode fracture. These findings hold significant implications for comprehending and elucidating the genuine fracture process and three-dimensional fracture theory of rocks.

Since the classical element model cannot describe the nonlinear characteristics of rock during the entire compressive creep process, nonlinear elements and creep damage are generally introduced in the model to resolve this issue. However, several previous studies have reckoned that creep damage in rock only occurs in the accelerated creep stage and is only described by the Weibull distribution. Nevertheless, the creep damage mechanism of rocks is still not clearly understood. In this study, a reasonable representation of the damage variables of solid materials is presented. Specifically, based on the Gurson damage model, the damage state functions reflecting the constant creep stage and accelerated creep stage of rock are established. Further, the one-dimensional and three-dimensional creep damage constitutive equations of rock are derived by modifying the Nishihara model. Finally, the creep-acoustic emission tests of phyllite under different confining pressures are conducted to examine the creep damage characteristics of phyllite. And the proposed constitutive model is verified by analyzing the results of creep tests performed on saturated phyllite. Overall, this study reveals the relationship between the creep characteristics of rocks and the corresponding damage evolution pattern, which bridges the gap between the traditional theory and the quantitative analysis of rock creep and its damage pattern.

Purpose. The main purpose of the study is to systematize and analyse in-depth current trends in the field of landslide prevention and development in different countries of the world, especially in Ukraine, as well as to consider and highlight the main factors that cause landslides, and to study in detail the methods of their prediction and minimization of relevant risks. Methodology. Landslides are a serious geological hazard. Currently, there is a tendency to increase the frequency of landslides due to anthropogenic impact worldwide. The natural processes of the geological environment, together with the development of mineral deposits, massive and large-scale land development, lead to the intensification of landslide processes. The cause of landslide formation is an imbalance between the shear force of gravity and the retaining forces. Findings. The number of landslides in recent years has been analysed and their distribution on different continents has been considered in detail. The causes of landslides in Ukraine and other countries of the world are identified and systematized. The urgency of the problem of landslide phenomena in Ukraine is considered, and the need for progressive study of landslide formation processes in order to prevent them is emphasized. The importance of continuous monitoring of slope stability is emphasized to reduce risks and improve safety. Originality. A comprehensive study of current trends in the occurrence and development of landslides in different countries of the world and Ukraine in particular was carried out, taking into account the latest advances in the field of geology, geomechanics and construction. Based on the analysis, conclusions were drawn about the need for progressive study of landslide processes in order to prevent them. Practical value. The results of the review of landslide prevention trends can be effectively used to improve natural risk management strategies, as well as to develop new and improve existing engineering measures aimed at preventing landslides. This, in turn, will help to improve the safety of both the population and critical infrastructure.

In order to improve the Hoek-Brown strength criterion not considering the influence of intermediate principal stress on rock strength, the evolutions of rock strength were investigated according to the results of the rock true triaxial compression test. The intermediate principal stress coefficient was introduced to quantify the effect on rock strength. Considering the relationships between the parameter of the Hoek-Brown strength criterion and the rock stress levels, the modified Hoek-Brown strength criterion for the true triaxial stress was then established with the Lagrange interpolation method. The spatial envelope characteristics of the modified strength criterion were analyzed. The best-fitting errors of seven rocks with true triaxial test results were finally compared with the three other three-dimensional strength criteria to verify the rationality of the modified strength criterion. The research results indicate that the rock strength increases gradually with the increase of minimum principal stress, and increases first and then decreases with the increase of intermediate principal stress, which presents a significant interval effect. The modified strength criterion not only has the advantage of the Hoek-Brown strength criterion in the nonlinear characteristics of the meridian plane but also describes the basic characteristics of rock strength in stress space. The spatial envelope surfaces for the modified strength criteria with the linear and quadratic interpolation are the non-equilateral hexagonal pyramidal surfaces and conical surfaces, which can meet the requirement of continuous smoothness in the tension-compression meridian plane interval. The modified strength criterion can better predict the true triaxial strength of rocks and reasonably reflect the influence of intermediate principal stress on the rock strength. The modified strength criterion with the quadratic interpolation improves the prediction accuracy of rock strength by about 1.2 to 2.0 times compared to the criterion with linear interpolation. The modified strength criterion has good agreement with the true triaxial test results of different hard and brittle rocks compared with other true triaxial strength criteria, which shows the applicability and reliability of the modified strength criterion.

Earthquakes are natural events and it is quite easy and beneficial to convert them to wealth (national asset) rather than catastrophe. The earthquakes exert their catastrophe on the buildings/structures founded in soil grounds. There is not even a single case study of an earthquake that caused a catastrophe where structures/buildings are founded on/in a rocky ground that is not proper for agriculture. However, almost all inland earthquakes, particularly strike-slip and normal fault zones ultimately create larger and thicker soil mantle, which is heated by (a) kinetic energy created by particle movements and (b) higher geothermal gradient peculiar to active fault zones. So, people should use fertile soil plains for agriculture and surrounding rocky lands for settlement in accordance with the recommendations of Mother Nature and State Laws and in accordance with the maxim "Love the nature, never challenge it”.

The Ras homology (Rho) family of GTPases serves various functions, including promotion of cell migration, adhesion, and transcription, through activation of effector molecule targets. One such pair of effectors, the Rho‐associated coiled‐coil kinases (ROCK1 and ROCK2), induce reorganization of actin cytoskeleton and focal adhesion through substrate phosphorylation. Studies on ROCK knockout mice have confirmed that ROCK proteins are essential for embryonic development, but their physiological functions in adult mice remain unknown. In this study, we aimed to examine the roles of ROCK1 and ROCK2 proteins in normal adult mice. Tamoxifen (TAM)‐inducible ROCK1 and ROCK2 single and double knockout mice (ROCK1flox/flox and/or ROCK2flox/flox;Ubc‐CreERT2) were generated and administered a 5‐day course of TAM. No deaths occurred in either of the single knockout strains, whereas all of the ROCK1/ROCK2 double conditional knockout mice (DcKO) had died by Day 11 following the TAM course. DcKO mice exhibited increased lung tissue vascular permeability, thickening of alveolar walls, and a decrease in percutaneous oxygen saturation compared with noninducible ROCK1/ROCK2 double‐floxed control mice. On Day 3 post‐TAM, there was a decrease in phalloidin staining in the lungs in DcKO mice. On Day 5 post‐TAM, immunohistochemical analysis also revealed reduced staining for vascular endothelial (VE)‐cadherin, β‐catenin, and p120‐catenin at cell–cell contact sites in vascular endothelial cells in DcKO mice. Additionally, VE‐cadherin/β‐catenin complexes were decreased in DcKO mice, indicating that ROCK proteins play a crucial role in maintaining lung function by regulating cell–cell adhesion.

AbstractFor rock structures exposed in the natural condition, water-induced weakening (including water softening and chemical weathering) is thought to be the main reason for its’ stiffness and strength degradation, thus it is of great significance to study the mechanical properties of rocks under the influence of water. In this study, a hexagonal close-packed particle assembly (2D) composed of bonded circular particles with same diameter is considered to approximate a typical soft rock, where the composite contact model for rock materials considering the water-induced wakening is adopted to define the microscopic mechanical reactions between particles. Based on homogenisation theory and lattice model, the stress-strain relationship and strength criteria for rock considering water-induced weakening, as well as the quantitative correlation between macroscopic elastic and strength parameters with microscopic parameters are obtained. The effects of water softening and chemical weathering respectively characterised by saturation and mass loss ratio on macroscopic mechanical behaviours of rock are analysed in detail. The long-term ageing effects of water-induced weakening are also analysed. All results are in good agreement with the laboratory test results, verifying the applicability of the theoretical solution for analysing the effect of water-induced weakening on mechanical behaviours of rock. [ABSTRACT FROM AUTHOR]

Earthquakes are natural events and it is quite easy and beneficial to convert them to wealth (national asset) rather than catastrophe. The earthquakes exert their catastrophe on the buildings/structures founded in soil grounds. There is not even a single case study of an earthquake that caused a catastrophe where structures/buildings are founded on/in a rocky ground that is not proper for agriculture. However, almost all inland earthquakes, particularly strike-slip and normal fault zones ultimately create larger and thicker soil mantle, which is heated by (a) kinetic energy created by particle movements and (b) higher geothermal gradient peculiar to active fault zones. So, people should use fertile soil plains for agriculture and surrounding rocky lands for settlement in accordance with the recommendations of Mother Nature and State Laws and in accordance with the maxim "Love the nature, never challenge it”. [ABSTRACT FROM AUTHOR]

A thorough understanding of the evolution of strain and damage accumulation is a prerequisite for effective control of the surrounding rock to ensure good stability and better maintenance of underground structures. In this work, we have proposed a new way of adjusting the fractional order to obtain a new variable fractional order rheological model to describe the evolution of mechanical properties and to model the stress-strain response of the rock during plastic flow. It is proved that the function law of our variable order fractional model is defined by five parameters a , b , m , n , α 0. An analysis of the different parameters of the fractional model confirms that the mechanical behavior of the rock hardens and softens faster when the confining pressure is high. Moreover, the definition of our fractional model by a continuous function of the plastic strain allows us to explore in more detail the hardening/softening duality of the mechanical behavior of the rock. This fractional model not only allows us to model the stress-strain relationship of the rock more accurately and with a relatively short calculation time, it also allows us to model the stress-strain relationship of the rock more accurately and with a relatively short calculation time, but also to accurately capture the contraction-dilation volume transition of quasi-fragile rocks. We believe that the results of this work will help in the decision making process for the construction of underground structures. • A new fractional model is established by a continuous function of plastic strain. • Its continuous form is necessary to evaluate the influence of confining pressure. • The new model more accurately describes the stress-strain relationship of the rock. • This model also reflects the rock's compression-dilation volume transition. [ABSTRACT FROM AUTHOR]

Glaucoma is a chronic neurodegenerative disease that poses a significant threat of irreversible blindness worldwide. Current treatments for glaucoma focus on reducing intraocular pressure (IOP), which is the only modifiable risk factor. Traditional anti-glaucomatous agents, including carbonic anhydrase inhibitors, beta-blockers, alpha-2 agonists, and prostaglandin analogs, work by either improving uveoscleral outflow or reducing aqueous humor production. Rho kinase (ROCK) inhibitors represent a novel class of anti-glaucomatous drugs that have emerged from bench to bedside in the past decade, offering multifunctional characteristics. Unlike conventional medications, ROCK inhibitors directly target the trabecular meshwork outflow pathway. This review aims to discuss the mechanism of ROCK inhibitors in reducing IOP, providing neuroprotection, and preventing fibrosis. We also highlight recent studies and clinical trials evaluating the efficacy and safety of ROCK inhibitors, compare them with other clinical anti-glaucomatous medications, and outline future prospects for ROCK inhibitors in glaucoma treatment. [ABSTRACT FROM AUTHOR]

The classical Mohr–Coulomb criterion has an extremely wide range of applications in the field of engineering geology, while it cannot accurately characterize rock failure under high confining stresses. Therefore, a nonlinear modification is implemented based on the Mohr–Coulomb criterion for achieving wider usage in all stress environments. The cohesion and internal friction angle are firstly calculated by regression based on the triaxial experiments of diorite and other typical rocks in different confining stress ranges, and the variation modes of cohesion and internal friction angle are then formalized and integrated into the classical Mohr–Coulomb criterion. Using the experimental results of 435 triaxial compression tests in existing publications, the predictions of the modified criterion are compared with those of the previous nonlinear criteria, which show that the predicted values of the modified criterion are in good agreement with the measured strength. Compared with the previous nonlinear criteria, the modified criterion has a wider application range and always maintains a higher accuracy. Highlights: A modified nonlinear Mohr–Coulomb criterion is proposedThe accuracy of the proposed criterion is verified by 435 triaxial tests.The proposed criterion shows a higher accuracy than previous nonlinear criteria [ABSTRACT FROM AUTHOR]

The Ras homology (Rho) family of GTPases serves various functions, including promotion of cell migration, adhesion, and transcription, through activation of effector molecule targets. One such pair of effectors, the Rho‐associated coiled‐coil kinases (ROCK1 and ROCK2), induce reorganization of actin cytoskeleton and focal adhesion through substrate phosphorylation. Studies on ROCK knockout mice have confirmed that ROCK proteins are essential for embryonic development, but their physiological functions in adult mice remain unknown. In this study, we aimed to examine the roles of ROCK1 and ROCK2 proteins in normal adult mice. Tamoxifen (TAM)‐inducible ROCK1 and ROCK2 single and double knockout mice (ROCK1flox/flox and/or ROCK2flox/flox;Ubc‐CreERT2) were generated and administered a 5‐day course of TAM. No deaths occurred in either of the single knockout strains, whereas all of the ROCK1/ROCK2 double conditional knockout mice (DcKO) had died by Day 11 following the TAM course. DcKO mice exhibited increased lung tissue vascular permeability, thickening of alveolar walls, and a decrease in percutaneous oxygen saturation compared with noninducible ROCK1/ROCK2 double‐floxed control mice. On Day 3 post‐TAM, there was a decrease in phalloidin staining in the lungs in DcKO mice. On Day 5 post‐TAM, immunohistochemical analysis also revealed reduced staining for vascular endothelial (VE)‐cadherin, β‐catenin, and p120‐catenin at cell–cell contact sites in vascular endothelial cells in DcKO mice. Additionally, VE‐cadherin/β‐catenin complexes were decreased in DcKO mice, indicating that ROCK proteins play a crucial role in maintaining lung function by regulating cell–cell adhesion. [ABSTRACT FROM AUTHOR]

Background: Rho-kinase (ROCK) regulates actomyosin contraction, coronary vasospasm, and cytoskeleton dynamics. ROCK and of NADPH oxidase (NOX) play an essential role in cardiovascular disease and proteoglycan synthesis, which promotes atherosclerosis by trapping low density lipoprotein. ROCK is activated by endothelin-1 (ET1) and transactivates the transforming growth factor beta receptor (TGFβR1), intensifying Smad signaling and proteoglycan production. This study aimed to identify the role of myosin light chain phosphatase (MLCP) as a downstream target of ROCK in TβR1 transactivation. Methods: Vascular smooth muscle cells were treated with ET1 and inhibitors of ROCK and MLCP were added. The phosphorylation levels of Smad2C, myosin light chain (MLC), and MLCP were monitored by western blot, and the mRNA expression of chondroitin 4-O-sulfotransferase 1 (C4ST1) was assessed by quantitative real-time PCR. Results: We examined ROCK's role in ET1-induced TGFβR1 activation. ROCK phosphorylated MLCP at the MYPT1 T853 residue, blocked by the ROCK inhibitor Y27632. ROCK also increased MLC phosphorylation and actomyosin contraction in response to ET1, enhanced by the phosphatase inhibitor Calyculin A. Calyculin A also increased C4ST1 expression, GAG-chain synthesizing enzymes. Conclusions: This work suggests that ROCK is involved in ET1-mediated TβR1 activation through increased MLCP phosphorylation, which leads to Smad2C phosphorylation and stimulates C4ST1 expression. [ABSTRACT FROM AUTHOR]

Rho kinase (ROCK) inhibitors (RKIs) have been available commercially as topical ocular hypotensive agents for approximately a decade. RKIs have promise as their presumed mechanism of action is increased trabecular meshwork (TM) outflow, the presumed primary site of pathology in open-angle glaucoma. We reviewed recent literature on netarsudil, ripasudil, H-1337, and VVN539 as monotherapy and in combination with other topical ocular hypotensive agents. With a unique primary mechanism of increase in trabecular outflow, these agents target the glaucomatous pathology in aqueous humor dynamics. The ocular hypotensive efficacy of netarsudil, once-daily (q.d.), is in the range of non-cardioselective beta-adrenoceptor antagonists. Ripasudil, given twice-daily (b.i.d.), is somewhat less effective. H-1337 and VVN539, at an early development stage, both seem to have efficacy in the range of netarsudil. Conjunctival hyperemia is an adverse event common to all RKIs tested to date. The greater adoption of RKIs in therapy may be limited by financial considerations, at least in the U.S. We searched PubMed for the keywords netarsudil (AR13324), ripasudil (K-115), H-1337, and VVN539 as of November 2023. We found 349 citations which we reviewed for consideration in this review. Herein we summarize primary research reports, excluding news stories or meeting abstracts. We also searched to find new trials of interest. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Freeze–thaw effect is one of the most important environmental conditions that rocks may be subjected to. Through laboratory model tests, the damage characteristics of rocks under the FTC were studied. Based on assuming that the strength of rocks subject to the FTC follows the Weibull distribution, the cumulative damage variable of the number of FTCs was introduced. A cumulative damage constitutive model of shear strength attenuation of rock that meets the Mohr–Coulomb criterion is established. The rationality and applicability of the proposed damage constitutive model are verified by comparing the results of rock shear strength parameters under cyclic freeze–thaw loads. [ABSTRACT FROM AUTHOR]

Lung epithelial development relies on the proper balance of cell proliferation and differentiation to maintain homeostasis. When this balance is disturbed, it can lead to diseases like cancer, where cells undergo hyperproliferation and then can undergo migration and metastasis. Lung cancer is one of the deadliest cancers, and even though there are a variety of therapeutic approaches, there are cases where treatment remains elusive. The rho-associated protein kinase (ROCK) has been thought to be an ideal molecular target due to its role in activating oncogenic signaling pathways. However, in a variety of cases, inhibition of ROCK has been shown to have the opposite outcome. Here, we show that ROCK inhibition with y-27632 causes abnormal epithelial tissue development in Xenopus laevis embryonic skin, which is an ideal model for studying lung cancer development. We found that treatment with y-27632 caused an increase in proliferation and the formation of ciliated epithelial outgrowths along the tail edge. Our results suggest that, in certain cases, ROCK inhibition can disturb tissue homeostasis. We anticipate that these findings could provide insight into possible mechanisms to overcome instances when ROCK inhibition results in heightened proliferation. Also, these findings are significant because y-27632 is a common pharmacological inhibitor used to study ROCK signaling, so it is important to know that in certain in vivo developmental models and conditions, this treatment can enhance proliferation rather than lead to cell cycle suppression. [ABSTRACT FROM AUTHOR]

This paper demonstrates the importance of a proper contact algorithm selection when a constitutive model is correlated and validated, especially in the case of brittle materials. A parametric study is carried out to study the influence of contact parameters on the outcomes of the numerical simulations of a dynamic compression test. The split Hopkinson pressure bar (SHPB) model is developed, and sandstone rock is considered as a representative material having considerably different properties compared to SHPB bars. The finite element method (FEM) and smoothed particle hydrodynamics (SPH) were used to simulate specimen behaviour using a LS-Dyna solver. Two contact types based on the penalty method are analysed: nodes to surface (FEM and SPH) and surface to surface (FEM only). Furthermore, three approaches of contact stiffness calculation are used for each contact type. The waveform data and failure patterns are then compared among all simulated cases and the corresponding experimental outcomes. It is found that the soft constraint stiffness (SOFT = 1) provides the best outcomes, especially in the case of one-way contact, and is nearly insensitive to stiffness scaling parameters. By contrast, standard (SOFT = 0) and segment-based (SOFT =2) approaches require a substantial effort in adjusting the stiffness scaling parameters to obtain satisfactory results. This paper provides valuable guidance for correlating and validating parameters of constitutive models for rock and other brittle materials in the SHPB test. [ABSTRACT FROM AUTHOR]

Small GTPases are monomeric (approximately 21 kDa) proteins that regulate a number of biological processes, such as vesicle transport, cell division cycle, cell migration, invasion, adhesion, proliferation, and DNA repair. They are also involved in carcinogenesis and neurodegenerative diseases. Some of these proteins, such as the Rho family proteins, are essential regulators of actin cytoskeleton, controlling cell adhesion and motility. This review examines both normal and pathological processes in human cells that are regulated by small GTPases of the Rho family. Particular attention is paid to small GTPase inhibitors and their use in the treatment of various diseases. [ABSTRACT FROM AUTHOR]

This article focuses on the archaeological site known as Presa de la Luz (600 AD - 1000 AD), located in Jalisco, Mexico. The site is distinguished by the presence of a variety of graphic-rock manifestations (GRMs), both on the surface and beneath it. Human activities have been continuous and evident, resulting in significant alterations to the archaeological remains. This environment offers a rich setting for archaeological studies aimed at understanding the social and cultural dynamics of the region. While previous research has primarily focused on documentation and description, there has been little in-depth exploration into the interpretation of the use and functionality of these manifestations in the past. Therefore, the research objective was to analyze the GRMs at the site as indicators of spatial appropriation and to determine their use and functionality through a multidisciplinary methodology. This approach incorporated data from material records, natural elements, and chemical analyses. As a result, starch granules were identified in grinding stones and pocitos (which exhibit characteristics of permanence), particularly those of corn and beans. [ABSTRACT FROM AUTHOR]

Rock specimens of the reservoir's core material from the Chayanda oil and gas condensate field (OGCF) were tested using the Triaxial Independent Load Test System of the Ishlinsky Institute for Problems in Mechanics, Russian Academy of Sciences (TILTS) in order to experimentally study the effect exerted by desalinization of reservoir rocks on their strain, strength, and filtration characteristics. According to the study data, desalinization considerably increases a rock permeability. Strain and strength properties of the studied rocks change toward softening (except for an internal friction angle), nevertheless remaining relatively high. Based on the experimental physical modeling of the pressure reducing process at the bottom of a horizontal well using TILTS, a slight decrease in elastic and strength properties of the Chayanda OGCF reservoir rocks after their desalinization should not affect the stability of the well's walls. The results obtained make it possible to draw the important practical conclusion: when operating the field at the stage of salt washing out due to water filtration under the operation process, a dramatic increase in the risks related to reservoir destruction and higher sand production should not be expected. [ABSTRACT FROM AUTHOR]

Pancreatic cancer is characterized by a densely fibrotic stroma. The fibrotic stroma hinders the intratumoral penetration of nanomedicine and diminishes therapeutic efficacy. Fibrosis is characterized by an abnormal organization of extracellular matrix (ECM) components, namely the abnormal deposition and/or orientation of collagen and fibronectin. Abnormal ECM organization is chiefly driven by pathological signaling in pancreatic stellate cells (PSCs), the main cell type involved in fibrogenesis. However, whether targeting signaling pathways involved in abnormal ECM organization improves the intratumoral penetration of nanomedicines is unknown. Here, we show that targeting transforming growth factor-β (TGFβ)/Rho-associated kinase (ROCK) 1/2 signaling in PSCs normalizes ECM organization and concomitantly improves macromolecular permeability of the fibrotic stroma. Using a 3-dimensional cell culture model of the fibrotic pancreatic cancer microenvironment, we found that pharmacological inhibition of TGFβ or ROCK1/2 improves the permeation of various macromolecules. By using an isoform-specific pharmacological inhibitor and siRNAs, we show that targeting ROCK2, but not ROCK1, alone is sufficient to normalize ECM organization and improve macromolecular permeability. Moreover, we found that ROCK2 inhibition/knockdown attenuates Yes-associated protein (YAP) nuclear localization in fibroblasts co-cultured with pancreatic cancer cells in 3D. Finally, pharmacological inhibition or siRNA-mediated knockdown of YAP normalized ECM organization and improved macromolecular permeability. Our results together suggest that the TGFβ/ROCK2/YAP signaling axis may be therapeutically targeted to normalize ECM organization and improve macromolecular permeability to augment therapeutic efficacy of nanomedicines in pancreatic cancer. [Display omitted] • Fibrosis is a hallmark of pancreatic cancer and impedes intratumoral drug delivery. • Pancreatic stellate cells (PSCs) abnormally remodel the extracellular matrix (ECM). • Macromolecular delivery through fibrotic tissue assessed in a 3D in vitro model. • Targeting TGFβ/ROCK/YAP in PSCs attenuated ECM remodeling and improved delivery. • Targeting ROCK2, rather than ROCK1, was more effective. [ABSTRACT FROM AUTHOR]

The elastic modulus of rocks is a measure of the ability of rocks to resist elastic deformation. It is related to the size of rocks and can effectively measure the internal physical and mechanical strength of rocks. The development of joint fractures is the main reason for the size effect of rocks. Therefore, exploring the influence of joint roughness on the elastic modulus of rocks of different sizes is of great significance in mining rock mechanics. The article investigates the size effect of joint roughness on elastic modulus of rocks by establishing simulation schemes for 30 working conditions. By analyzing the stress-strain curves of rocks with different roughness and sizes, the deformation and failure patterns of rocks with different sizes were obtained. Research has found that the elastic modulus of rocks is in a power function relationship with joint roughness, while the elastic modulus of rocks is negatively exponentially related to rock size; The characteristic elastic modulus of rocks is in a power function relationship with joint roughness. The above relationships not only reveal the variation of rock elastic modulus with size, but also reveal the influence of joint roughness on elastic modulus, providing important basis for understanding the stability of mining rock engineering. [ABSTRACT FROM AUTHOR]

The shear performance of the binary interface formed by mortar and rock cementation is a key factor influencing the stability and safety of basic engineering projects related to livelihood and economy since concrete has become one of the most widely used materials in engineering. Therefore, it is an urgent practical problem to further explore and clarify the shear failure mechanism of the mortar–rock binary interface. In response to the current research objective focused on fully bonded interfaces, this paper constructed binary interface models with different bonded conditions to perform direct shear experiments using numerical simulation methods, and the effect of bonded conditions on the shear behavior of the mortar–rock binary interface was analyzed. The results indicate that the bonded conditions have a significant influence on the shear mechanical behavior of the mortar–rock binary interface, which is mainly reflected in the stress-displacement curve characteristics, the shear strength, the fracture development and the stress distribution state. The research findings are of great theoretical significance for the further study of shear mechanics at the mortar–rock binary interface and of great practical significance for safe construction, resource conservation and disaster warning. [ABSTRACT FROM AUTHOR]

Septic cardiomyopathy (SCM) is one of the most serious complications of sepsis. The present study investigated the role and mechanism of upstream stimulatory factor 2 (USF2) in SCM. Serum samples were extracted from SCM patients and healthy individuals. A murine model of sepsis was induced by caecal ligation and puncture (CLP) surgery. Myocardial injury was examined by echocardiography and HE staining. ELISA assay evaluated myocardial markers (CK-MB, cTnI) and inflammatory cytokines (TNF-α, IL-1β, IL-18). Primary mouse cardiomyocytes were treated with lipopolysaccharide (LPS) to simulate sepsis in vitro. RT-qPCR and Western blot were used for analyzing gene and protein levels. CCK-8 assay assessed cell viability. NLRP3 was detected by immunofluorescence. ChIP, RIP and dual luciferase reporter assays were conducted to validate the molecular associations. USF2 was increased in serum from SCM patients, septic mice and primary cardiomyocytes. USF2 silencing improved the survival of septic mice and attenuated sepsis-induced myocardial pyroptosis and inflammation in vitro and in vivo. Mechanistically, USF2 could directly bind to the promoter of miR-206 to transcriptionally inhibit its expression. Moreover, RhoB was confirmed as a target of miR-206 and could promote ROCK activation and NLRP3 inflammasome formation. Moreover, overexpression of RhoB remarkably reversed the protection against LPS-induced inflammation and pyroptosis mediated by USF2 deletion or miR-206 overexpression in cardiomyocytes. The above findings elucidated that USF2 knockdown exerted a cardioprotective effect on sepsis by decreasing pyroptosis and inflammation via miR-206/RhoB/ROCK pathway, suggesting that USF2 may be a novel drug target in SCM. [ABSTRACT FROM AUTHOR]

Rock naturally contains numerous defects, and both loading rate and defect geometry affect the loading capacity of rock structures when subjected to dynamic impact loads. Understanding the rate-dependent mechanical response and characterizing geometry-related fracture parameter of defected rocks are crucial to safety assessment of rock engineering. In this paper, the effects of loading rate and notch parameter on dynamic brittle fracture behavior of Fangshan granite weakened by a blunt V-notch are experimentally studied. First, the dynamic fracture experiments on blunt V-notched semi-circular bend (BVNSCB) specimen of Fangshan granite with different notch geometries are performed using the split Hopkinson pressure bar (SHPB) system. Second, the dynamic fracture processes of blunt V-notched rocks are recorded using an ultrahigh-speed camera, and the mechanical responses to different impact loading conditions are obtained via digital image correlation (DIC) method. Third, the effects of loading rate and notch parameter on the dynamic fracture parameters including notch fracture toughness, crack propagation toughness, and crack velocity are discussed to reveal the fracture mechanism of blunt V-notched rocks subjected to impact loads. It is found that dynamic notch fracture toughness obtained from DIC method is usually larger than that measured directly from conventional maximum impact load method. The maximum tangential stress (MTS) criterion eliminating the effect of the fracture process zone (FPZ) at blunt V-notch tip is used to correct the apparent notch fracture toughness value measured from the maximum load method. The results show that corrected notch fracture toughness values are in good agreements with those obtained from the DIC method. This study is significant for dynamic fracture analyses and strength assessments of rock masses containing notches or other defects with complex geometry. Highlights: Effects of loading rate and notch geometry on dynamic fracture behavior of blunt V-notched rocks are studied. Dynamic notch fracture toughness and crack propagation toughness are simultaneously determined. DIC method is used to track the development of FPZ at blunt V-notch tip and quantify the FPZ length. [ABSTRACT FROM AUTHOR]

It is of great significance to study the flexural properties and behaviour of rock in rock mechanics and engineering applications, such as tunneling, mining and underground space development. However, there are few studies related to the flexural properties of rock considering different elastic parameters in tension and in compression. This study focuses on rock flexural strength subjected to bending loading. A series of four-point bending tests (FPBTs) on prismatic beams of granite were carried out. The flexural strength of rock was theoretically determined under different assumptions based on the elastic and elastic‒plastic theory considering different elastic properties of rock in tension and in compression. Then, a comparison was made between the indirect tensile strength measured by the Brazilian test and the flexural strength acquired from the FPBT. The effects of specimen shape and heterogeneity on the flexural behaviour of rock were analysed by FEM-based numerical simulation. The results show that the calculated flexural strengths considering the elastoplastic and bimodulus properties of rock are lower than those without considering the properties and are closer to the Brazilian tensile strength of rock. The flexural strengths of rock increase with increasing ratios of height to thickness. Heterogeneity plays a crucial role in the flexural properties of rock. The more homogeneous the rock is, the higher its flexural strength. The findings in this paper facilitate a better understanding of the flexural properties of rock. [ABSTRACT FROM AUTHOR]

In many geological conditions, obtaining the static elastic moduli of crustal rocks is an essential subject for accurate mechanical analyses of crust. The elastic wave method may be the best choice if rock specimens cannot be taken since elastic wave propagation can be applied to in-situ environments. Although many signs of progress have been made in the elastic wave method, some issues still restrict the accurate extraction of static moduli and its applications. A review of this method and its further research prospect is urgently needed. With this purpose, this paper summarized and analyzed the published experimental data about the relationship between the static and dynamic Young's moduli of rock, and the frequency dependence of wave velocities and dynamic elastic moduli. P- and S-wave velocities, Young's, and bulk moduli of rock, especially the saturated rock, have strong frequency dependence in a wide frequency range of 10–6–106 Hz. Different rocks or conditions (such as water content, amplitude, and pressure), have different frequency-dependent characteristics. The current elastic wave method can be classified into two methods: the empirical correlation method and the multifrequency ultrasonic method. The basic principle, advantages, and disadvantages of both methods are analyzed. Especially, the reasonability of the multifrequency ultrasonic method was elaborated given the nonlinear elasticity, strain level/rate, and pores/cracks in rock materials. Existing problems and prospects on the two methods are also pointed out, such as the choice of a proper empirical correlation, accurate determination of the critical P- and S-wave velocities, the prediction of Young's modulus at each strain level, and the reasonability of the method under various water contents and fracture structures. [ABSTRACT FROM AUTHOR]

Copyright of Acibadem Saglik Bilimleri Dergisi is the property of Acibadem University Medical School and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the dynamic response of fractured rock under cyclic loading and unloading, a WHY-300/10 microcomputer-controlled electro-hydraulic servo universal testing machine was used to conduct uniaxial cyclic loading and unloading tests. Simultaneously, acoustic emission (AE) and a CCD high-speed camera were employed to monitor the fracturing characteristics of sandstone. The mechanical properties, energy evolution, AE characteristics, and deformation of 45° sandstone were analyzed. The results indicate that as the load cycle level increases, both the elastic modulus and deformation modulus exhibit a "parabolic" increase, with a rapid rise initially and a slower rate of increase later. The damping ratio generally shows a decreasing trend but tends to rise near the peak load. The total energy, elastic energy, dissipated energy, damping energy, and damage energy all follow exponential function increases with the load level. The b-value fluctuates significantly during the stable crack propagation phase, unstable crack propagation phase, and peak phase. When the FR (Felicity ratio > 1), the rock is relatively stable; when the FR (Felicity ratio < 1), the rock gradually extends towards an unstable state. The Felicity ratio can be used as a predictive tool for the precursors of rock failure. Shear fractures dominate during the compaction and peak phases, while tensile fractures dominate during the crack propagation phase, ultimately leading to a failure characterized by tensile fracture. High-speed camera observations revealed that deformation first occurs at the tips of the prefabricated cracks and gradually spreads and deflects toward the ends of the sandstone. This study provides theoretical support for exploring the mechanical behavior and mechanisms of fractured rock under cyclic loading and unloading, and it has significant practical implications. [ABSTRACT FROM AUTHOR]