scholarly journals High-magnitude stresses induced by mineral-hydration reactions

2021 ◽  
Author(s):  
Oliver Plümper ◽  
David Wallis ◽  
Evangelos Moulas ◽  
Stefan Schmalholz ◽  
Hamed Amiri ◽  
...  
Keyword(s):  
Structural Damage ◽  
Critical Role ◽  
Hydration Reaction ◽  
Volume Increase ◽  
Natural Systems ◽  
Fluid Permeability ◽  
Bulk Stress ◽  
Dislocation Densities ◽  
Local Stresses ◽  
Deformation Processes

Fluid-rock interactions play a critical role in Earth’s lithosphere and in engineered subsurface systems. In the absence of chemical mass transport, mineral-hydration reactions will be accompanied by a solid-volume increase that may induce differential stresses and associated reaction-induced deformation processes, such as dilatant fracturing to increase fluid permeability. However, the magnitudes of stresses that manifest in natural systems remain poorly constrained. Here we show that the simplest hydration reaction in nature MgO + H2O⇔ Mg(OH)2 can induce stresses of several hundred megapascals, with local stresses up to ∼1.5 GPa. We demonstrate that these stresses are dissipated not only by fracturing but also induce plastic deformationwith dislocation densities (10^15m−2) exceeding those typical of tectonically deformedrocks. If these reaction-induced stresses can be transmitted across larger length scales they may influence the bulk stress state of reacting regions. Moreover, the structural damage induced may be the first step towards catastrophic rock failure, triggering crustal seismicity.

scholarly journals The sixth R: Revitalizing the natural phosphorus pump

2020 ◽  
Author(s):  
Christopher E. Doughty ◽  
Andrew J. Abraham ◽  
Joe Roman
Keyword(s):  
Food Systems ◽  
Critical Role ◽  
Large Animal ◽  
Natural Systems ◽  
Agricultural Revolution ◽  
Animal Populations ◽  
P Recycling ◽  
Phosphorus Recycling ◽  
Trading Scheme ◽  
P Budget

Humans and natural systems face three pressing concerns: the loss of large animal biodiversity, eutrophication of many aquatic systems, and the need to better recycle phosphorus. Here we propose a mechanism to help alleviate these problems. Some have hypothesized that we are approaching “peak phosphorus,” where phosphorus may become more expensive as it becomes rarer, thus endangering the green agricultural revolution and the ability to feed ourselves. Animals play a key role in the recycling of phosphorus (P) from the ocean depths to the continental interiors, but this movement has declined by >90% over the past 10,000 years. Prior to this decline, animals played a critical role in the global P budget and the pre-Anthropocene P budget was in steady state only after accounting for animal P inputs. Recently a 5R strategy was developed by Withers et al (2015) to Realign P inputs, Reduce P losses, Recycle P in bio-resources, Recover P in wastes, and Redefine P in food systems. Here we suggest a sixth R, to Revitalize the natural phosphorus pump. Countries are starting to mandate P recycling, and here we propose a P-trading scheme based on REDD+, where a country could partially achieve its recycling goals through revitalizing the natural P pump. Accrued money from this scheme could be used to restore or conserve wild animal populations while increasing natural phosphorus recycling.

scholarly journals Baicalin mitigated Mycoplasma gallisepticum-induced structural damage and attenuated oxidative stress and apoptosis in chicken thymus through the Nrf2/HO-1 defence pathway

2019 ◽  
Vol 50 (1) ◽  
Author(s):  
Jichang Li ◽  
Zujian Qiao ◽  
Wanying Hu ◽  
Wei Zhang ◽  
Syed Waqas Ali Shah ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Structural Damage ◽  
Critical Role ◽  
Mycoplasma Gallisepticum ◽  
Infected Group ◽  
Signalling Pathway ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Control Group ◽  
Related Factor ◽  
Chicken Thymus

Abstract The thymus is a primary lymphoid organ and plays a critical role in the immune response against infectious agents. Baicalin is a naturally derived flavonoid famous for its pharmacological properties, but the preventive effects of baicalin against immune impairment remain unclear. We examined this effect in the context of Mycoplasma gallisepticum (MG) infection-induced structural damage in the chicken thymus. Histopathological examination showed that the compact arrangement of cells in the thymus was lost in the MG-infected group. Inflammatory cell infiltration and nuclear debris accumulated, and the boundary between the cortex and medulla was not clearly visible. The mRNA and protein expression of apoptosis-related genes were significantly increased in the MG-infected group compared to the control group and the baicalin group. The number of positively stained nuclei in the terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay were increased in the MG-infected group. In addition, electron microscopic examination showed chromatin condensation, mitochondrial swelling and apoptotic vesicles in the MG-infected group. However, baicalin treatment significantly alleviated the oxidative stress and apoptosis induced by MG infection. Importantly, the abnormal morphology was partially ameliorated by baicalin treatment. Compared to the MG-infected group, the baicalin-treated group showed significantly reduced expression of apoptosis-related genes at both the mRNA and protein levels. Meanwhile, the nuclear factor erythroid 2-related factor 2 (Nrf2) signalling pathway and downstream genes were significantly upregulated by baicalin to counteract MG-induced oxidative stress and apoptosis in the thymocytes of chickens. In summary, these findings suggest that baicalin treatment efficiently attenuated oxidative stress and apoptosis by activating the Nrf2 signalling pathway and could protect the thymus from MG infection-mediated structural and functional damage.

Damage Detection Using Multiphysics Guided Wave Propagation

2020 ◽  
Author(s):  
J. Dana ◽  
Y. H. Park ◽  
C. Gonzales
Keyword(s):  
Wave Propagation ◽  
Damage Detection ◽  
Structural Damage ◽  
Lamb Waves ◽  
Critical Role ◽  
Guided Wave ◽  
Transient Wave ◽  
Pzt Actuator ◽  
Detection Techniques ◽  
Structural Health

Abstract In order to improve the safety, reliability, and life of diverse structures, the development of effective methodologies for structural health monitoring is critical. Among damage detection techniques, guided ultrasonic Lamb waves are particularly suitable for damage detection applications for plate-like and shell-like structures, such as aircraft wing-box structures, heat exchanger tubing, stiffened panels, and nuclear steam generator tubing, due to their sensitivity to damage. Computational models can play a critical role to study wave propagation for monitoring structural health and develop a technique to detect structural damage. Due to complexity of guided wave behavior, efficient and accurate computation tools are essential to study the mechanisms that account for coupling, dispersion, and interaction with damage. In this study, a numerical technique is presented for guided waves propagation in metallic structure by employing co-simulation using ABAQUS Standard module and ABAQUS Explicit module simultaneously to simulate transient wave propagation from an PZT actuator into a metallic plate. The present co-simulation analysis couples multiphysics (piezoelectric) analysis with transient dynamics (wave propagation) analysis. A numerical test is conducted using a PZT actuator for exciting planar Lamb waves and a sensor for acquiring wave signals. The signals achieved from defected and pristine models by FEA are then compared to identify and detect damage in the structure.

scholarly journals LOXL2 attenuates osteoarthritis through inactivating Integrin/FAK signaling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Caixia Zhang ◽  
Mengjiao Zhu ◽  
Huijuan Wang ◽  
Juan Wen ◽  
Ziwei Huang ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Structural Damage ◽  
Critical Role ◽  
Joint Disease ◽  
In Vivo Model ◽  
Matrix Degradation ◽  
Loss Of Function ◽  
In Vivo Models

AbstractTemporomandibular joint OA (TMJOA) is a common degenerative joint disease, leads to structural damage and ultimately loss of function. Matrix degradation is one of the first pathogenesis during the progression of OA, it was effective to inhibit matrix degradation to block the development of OA. In this study, an in vivo model (compressive mechanical force) and an in vitro model (IL-1β) were used to induce OA-like changes in TMJ cartilage and chondrocytes. We revealed lysyl oxidase like-2 (LOXL2) play a critical role in TMJOA. LOXL2 expression decreased in mechanical stress/IL-β induced TMJOA-like lesions in both in vivo models and in vitro models. Furthermore, recombinant LOXL2 (rhLOXL2) treatment ameliorated the degenerative changes induced by mechanical stress in vivo, including the thinning cartilage, down-expression of collagen II and proteoglycan, and over-expression of TNF-a, while LOXL2 antibody (anti-LOXL2) treatment exacerbated these changes. Mechanistically, the protection of LOXL2 in chondrocytes was induced partly through activation of the Integrin/FAK pathway. The inhibition of the Integrin/FAK pathway could neutralized the effects caused by rhLOXL2. Collectively, our study suggests that the LOXL2 plays a protective role in mechanical stress induced TMJOA-like changes, and the Integrin/FAK pathway may be a key downstream pathway in this process.

scholarly journals Conditional ablation of macrophages disrupts ovarian vasculature

Reproduction ◽  
2011 ◽  
Vol 141 (6) ◽  
pp. 821-831 ◽  
Author(s):  
Emily C Turner ◽  
Jeremy Hughes ◽  
Helen Wilson ◽  
Michael Clay ◽  
Katie J Mylonas ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Diphtheria Toxin ◽  
Structural Damage ◽  
Immune Cell ◽  
Morphological Changes ◽  
Critical Role ◽  
Promoter Sequence ◽  
Corpora Lutea ◽  
Vascular Integrity ◽  
Toxin Receptor

Macrophages are the most abundant immune cell within the ovary. Their dynamic distribution throughout the ovarian cycle and heterogenic array of functions suggest the involvement in various ovarian processes, but their functional role has yet to be fully established. The aim was to induce conditional macrophage ablation to elucidate the putative role of macrophages in maintaining the integrity of ovarian vasculature. Using the CD11b-diphtheria toxin receptor (DTR) mouse, in which expression of human DTR is under the control of the macrophage-specific promoter sequence CD11b, ovarian macrophages were specifically ablated in adult females by injections of diphtheria toxin (DT). CD11b-DTR mice were given DT treatment or vehicle and ovaries collected at 2, 8, 16, 24 and 48 h. Histochemical stains were employed to characterise morphological changes, immunohistochemistry for F4/80 to identify macrophages and the endothelial cell marker CD31 used to quantify vascular changes. In normal ovaries, macrophages were detected in corpora lutea and in the theca layer of healthy and atretic follicles. As macrophage ablation progressed, increasing amounts of ovarian haemorrhage were observed affecting both luteal and thecal tissue associated with significant endothelial cell depletion, increased erythrocyte accumulation and increased follicular atresia by 16 h. These events were followed by necrosis and profound structural damage. Changes were limited to the ovary, as DT treatment does not disrupt the vasculature of other tissues likely reflecting the unique cyclical nature of the ovarian vasculature and heterogeneity between macrophages within different tissues. These results show that macrophages play a critical role in maintaining ovarian vascular integrity.

scholarly journals Characterization of Cyanophages in Lake Erie: Interaction Mechanisms and Structural Damage of Toxic Cyanobacteria

Toxins ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 444 ◽  
Author(s):  
Xuewen Jiang ◽  
Chanhee Ha ◽  
Seungjun Lee ◽  
Jinha Kwon ◽  
Hanna Cho ◽  
...  
Keyword(s):  
Host Cell ◽  
Chlorophyll A ◽  
Structural Damage ◽  
Lake Erie ◽  
Critical Role ◽  
Significant Inhibition ◽  
Mechanical Stiffness ◽  
Dynamic Interactions ◽  
Optical Absorbance ◽  
Western Lake

Cyanophages are abundant in aquatic environments and play a critical role in bloom dynamics, including regulation of cyanobacteria growth and photosynthesis. In this study, cyanophages from western Lake Erie water samples were screened for lytic activity against the host cell (Microcystis aeruginosa), which also originated from Lake Erie, and identified with real-time sequencing (Nanopore sequencing). M. aeruginosa was mixed with the cyanophages and their dynamic interactions were examined over two weeks using atomic force microscopy (AFM) as well as transmission electron microscopy (TEM), qPCR, phycocyanin and chlorophyll-a production, and optical absorbance measurements. The TEM images revealed a short-tailed virus (Podoviridae) in 300 nm size with unique capsid, knob-like proteins. The psbA gene and one knob-like protein gene, gp58, were identified by PCR. The AFM showed a reduction of mechanical stiffness in the host cell membranes over time after infection, before structural damage became visible. Significant inhibition of the host growth and photosynthesis was observed from the measurements of phycocyanin and chlorophyll-a concentrations. The results provide an insight into cyanobacteria–cyanophage interactions in bloom dynamics and a potential application of cyanophages for bloom control in specific situations.

Study on Hydration Mechanism of Slag Activated by Alkaline

2011 ◽  
Vol 374-377 ◽  
pp. 1582-1588 ◽  
Author(s):  
Jia Ying Sun ◽  
Xin Gu
Keyword(s):  
Structural Damage ◽  
Film Theory ◽  
Heat Of Hydration ◽  
Stable Phase ◽  
Hydration Reaction ◽  
Protective Film ◽  
Early Hydration ◽  
Boiler Water ◽  
Hydration Mechanism ◽  
Potential Activity

By measuring the heat of hydration during the hydration of water quenched slag produced by molten iron boiler water, combined with water quenching measurements, infrared spectroscopy, X-ray diffraction, differential thermal analysis and electron microscopy observation and analysis, the authors argued that the type of water quenched slag is a kind of potential activity of the vitreous structure. Protective film theory (the surface layer of silicon-oxygen network) is put forward. Therefore, the slag hydration must be excited in the activator destruction of this layer of film, and this hydration process can be divided into three stages. They are: the early hydration of sodium silicate hardening; slag’s surface structural damage and the network structure dissolution and disperse in the early hydration reaction phase; the acceleration of hydration reactions and stable phase in the late.

Conservation Introductions for Biodiversity Adaptation under Climate Change

2018 ◽  
Vol 7 (2) ◽  
pp. 323-345 ◽  
Author(s):  
Phillipa C. McCormack
Keyword(s):  
Climate Change ◽  
Climate Changes ◽  
Critical Role ◽  
Wicked Problem ◽  
Ecological Change ◽  
Human Intervention ◽  
Natural Systems ◽  
Law And Policy ◽  
Legal Frameworks

AbstractAnthropogenic climate change represents a wicked problem, both for the Earth’s natural systems and for biodiversity conservation law and policy. Legal frameworks for conservation have a critical role to play in helping species and ecosystems to adapt as the climate changes. However, they are currently poorly equipped to regulate adaptation strategies that demand high levels of human intervention. This article investigates law and policy for conservation introductions, which involve relocating species outside their historical habitat. It takes as a case study Australian law on conservation introductions, demonstrating theoretical and practical legal hurdles to these strategies at international, national and subnational levels. The article argues that existing legal mechanisms may be repurposed, in some cases, to better regulate conservation introduction projects. However, new legal mechanisms are also needed, and soon, to effectively conserve species and ecosystems in a period of unprecedented ecological change.

scholarly journals Dislocation structure of deformed olivine single crystals from conventional EBSD maps

2021 ◽  
Vol 48 (9) ◽  
Author(s):  
Ulrich Faul
Keyword(s):  
Single Crystals ◽  
Crystalline Lattice ◽  
Slip Systems ◽  
Linear Defects ◽  
San Carlos Olivine ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Deformation Processes ◽  
Internal Deformation ◽  
San Carlos

AbstractDislocations, linear defects in a crystalline lattice characterized by their slip systems, can provide a record of grain internal deformation. Comprehensive examination of this record has been limited by intrinsic limitations of the observational methods. Transmission electron microscopy reveals individual dislocations, but images only a few square $$\upmu$$ μ m of sample. Oxidative decoration requires involved sample preparation and has uncertainties in detection of all dislocations and their types. The possibility of mapping dislocation density and slip systems by conventional (Hough-transform based) EBSD is investigated here with naturally and experimentally deformed San Carlos olivine single crystals. Geometry and dislocation structures of crystals deformed in orientations designed to activate particular slip systems were previously analyzed by TEM and oxidative decoration. A curvature tensor is calculated from changes in orientation of the crystal lattice, which is inverted to calculate density of geometrically necessary dislocations with the Matlab Toolbox MTEX. Densities of individual dislocation types along with misorientation axes are compared to orientation change measured on the deformed crystals. After filtering (denoising), noise floor and calculated dislocation densities are comparable to those reported from high resolution EBSD mapping. For samples deformed in [110]c and [011]c orientations EBSD mapping confirms [100](010) and [001](010), respectively, as the dominant slip systems. EBSD mapping thus enables relatively efficient observation of dislocation structures associated with intracrystalline deformation, both distributed, and localized at sub-boundaries, over substantially larger areas than has previously been possible. This will enable mapping of dislocation structures in both naturally and experimentally deformed polycrystals, with potentially new insights into deformation processes in Earth’s upper mantle.

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