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Geoderma ◽  
2022 ◽  
Vol 406 ◽  
pp. 115513
Author(s):  
Livia Urbanski ◽  
Peter Schad ◽  
Karsten Kalbitz ◽  
Jan van Mourik† ◽  
Ernst Gehrt ◽  
...  

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 58
Author(s):  
Adrian Jarzyna ◽  
Maciej Bąbel ◽  
Damian Ługowski ◽  
Firouz Vladi

In the Dingwall gypsum quarry in Nova Scotia, Canada, operating in 1933–1955, the bedrock anhydrite deposits of the Carboniferous Windsor Group have been uncovered from beneath the secondary gypsum beds of the extracted raw material. The anhydrite has been subjected to weathering undergoing hydration (gypsification), transforming into secondary gypsum due to contact with water of meteoric derivation. The ongoing gypsification is associated with a volume increase and deformation of the quarry bottom. The surface layer of the rocks is locally split from the substrate and raised, forming spectacular hydration relief. It shows numerous domes, ridges and tepee structures with empty internal chambers, some of which represent unique hydration caves (swelling caves, Quellungshöhlen). The petrographic structure of the weathering zone has been revealed by macro- and microscopic observations. It was recognized that gypsification commonly starts from a developing network of tiny fractures penetrating massive anhydrite. The gypsification advances from the fractures towards the interior of the anhydrite rocks, which are subdivided into blocks or nodules similar to corestones. Characteristic zones can be recognized at the contact of the anhydrite and the secondary gypsum: (1) massive and/or microporous anhydrite, (2) anhydrite penetrated by tiny gypsum veinlets separating the disturbed crystals and their fragments (commonly along cleavage planes), (3) gypsum with scattered anhydrite relics, and (4) secondary gypsum. The secondary gypsum crystals grow both by replacement and displacement, and also as cement. Displacive growth, evidenced by abundant deformation of the fragmented anhydrite crystals, is the direct cause of the volume increase. Crystallization pressure exerted by gypsum growth is thought to be the main factor generating volume increase and, consequently, also the formation of new fractures allowing water access to “fresh” massive anhydrite and thus accelerating its further hydration. The expansive hydration is taking place within temperature range from 0 to ~30 °C in which the solubility of gypsum is lower than that of anhydrite. In such conditions, dissolving anhydrite yields a solution supersaturated with gypsum and the dissolution of anhydrite is simultaneous with in situ replacive gypsum crystallization. Accompanying displacive growth leads to volume increase in the poorly confined environment of the weathering zone that is susceptible to upward expansion.


2021 ◽  
Vol 11 (1) ◽  
pp. 19
Author(s):  
Christophe Beyls ◽  
Yohann Bohbot ◽  
Matthieu Caboche ◽  
Pierre Huette ◽  
Guillaume Haye ◽  
...  

(1) Background: Right ventricular (RV) strain parameters derived from the analysis of the tricuspid annular displacement (TAD) are emergent two-dimensional speckle tracking echocardiography (2D-STE) parameter used for the quantitative assessment of RV systolic function. Few data are available regarding 2D-STE parameters and their dependency on RV preload. Our aim was to evaluate the effect of an acute change in RV preload on 2D-STE parameters in healthy volunteers. (2) Methods: Acute modification of RV preload was performed by a fluid challenge (FC): an infusion of 500 mL of 0.9% sodium chloride was given over 5 min in supine position. Preload dependency (responder group) was confirmed by a stroke volume increase of at least 10% measured by echocardiography. (3) Results: Among 32 healthy volunteers, 19 (59%) subjects were classified as non-responders and 13 (41%) as responders. In the responder group, the tricuspid annular plane systolic excursion (TAPSE) significantly increased (20 (20–23.5) mm to 24 (20.5–26.5) mm; p = 0.018), while RV strain parameters significantly decreased after FC: −23.5 ((−22.3)–(−27.3))% to −25 ((−24)–(29.6))%; p = 0.03) for RV free wall longitudinal strain and −22.8 ((−20.4)–(−30.7))% to −23.7 ((−21.2)–(−27))%; p = 0.02) for RV four-chamber longitudinal strain. 2D-STE parameters derived from the TAD analysis were not influenced by the FC (all p > 0.05). (4) Conclusions: In young, healthy volunteers, RV strain parameters and TAPSE are preload dependent, while TAD parameters were not. The loading conditions must be accounted for when evaluating RV systolic function by 2D-STE parameters.


2021 ◽  
Author(s):  
Oliver Plümper ◽  
David Wallis ◽  
Evangelos Moulas ◽  
Stefan Schmalholz ◽  
Hamed Amiri ◽  
...  

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.


2021 ◽  
Vol 118 (47) ◽  
pp. e2103228118
Author(s):  
Chloé Roffay ◽  
Guillaume Molinard ◽  
Kyoohyun Kim ◽  
Marta Urbanska ◽  
Virginia Andrade ◽  
...  

During osmotic changes of their environment, cells actively regulate their volume and plasma membrane tension that can passively change through osmosis. How tension and volume are coupled during osmotic adaptation remains unknown, as their quantitative characterization is lacking. Here, we performed dynamic membrane tension and cell volume measurements during osmotic shocks. During the first few seconds following the shock, cell volume varied to equilibrate osmotic pressures inside and outside the cell, and membrane tension dynamically followed these changes. A theoretical model based on the passive, reversible unfolding of the membrane as it detaches from the actin cortex during volume increase quantitatively describes our data. After the initial response, tension and volume recovered from hypoosmotic shocks but not from hyperosmotic shocks. Using a fluorescent membrane tension probe (fluorescent lipid tension reporter [Flipper-TR]), we investigated the coupling between tension and volume during these asymmetric recoveries. Caveolae depletion and pharmacological inhibition of ion transporters and channels, mTORCs, and the cytoskeleton all affected tension and volume responses. Treatments targeting mTORC2 and specific downstream effectors caused identical changes to both tension and volume responses, their coupling remaining the same. This supports that the coupling of tension and volume responses to osmotic shocks is primarily regulated by mTORC2.


2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi129-vi130
Author(s):  
Margot Lazow ◽  
Martijn Nievelstein ◽  
Adam Lane ◽  
Pratiti Bandopadhayay ◽  
Mariko DeWire-Schottmiller ◽  
...  

Abstract INTRODUCTION Cross-sectional tumor measures are used as endpoints in clinical trials of DIPG, but may not capture meaningful changes in disease burden. Volumetric measures may provide a more accurate assessment of tumor growth. We measured the correlation between cross-sectional and volumetric measures and compared their prognostic impact to better understand response evaluation in DIPG. METHODS Patients from the International DIPG Registry with diagnostic and post-radiation MRIs were included. Utilizing mint LesionTM software, tumors were manually contoured by an experienced pediatric neuro-radiologist to extrapolate cross-sectional product (CP) and volume measures. Correlation between CP and volume was assessed by linear regression. Landmark analyses were performed to determine differences in overall survival (OS) (via log-rank) between patients classified as progressive disease (PD) versus non-PD according to CP and volumetric measurements at one-, three-, and five-months post-radiation. Imaging consistent with pseudoprogression was designated non-PD. Hazard ratios (HR) for survival after these timepoints were calculated by Cox regression. RESULTS A total of 317 MRIs from 46 patients were analyzed. When comparing change from smallest previous tumor size, CP increase of 25% (PD by RAPNO) correlated with volume increase of 28% (R2=0.685). There was no difference in OS between patients classified as PD versus non-PD by CP at one-month, three-months, or five-months post-radiation (p >0.05). However, significant differences in OS were observed between patients classified as PD versus non-PD by volume (28% increase) at one-month (2.7 vs. 12.8 months, p=0.005), three-months (1.9 vs. 10.7 months, p=0.036), and five-months post-radiation (3.7 vs. 9.1 months, p=0.023). PD by volume, but not by CP, was predictive of survival at all timepoints (HR: 5.0, 2.4, 2.4). CONCLUSIONS Volumetric assessments of PD correlated better with survival than CP at all post-radiation timepoints. Tumor volume likely represents a more accurate, prognostically-relevant measure of disease burden that deserves investigation in future DIPG trials.


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xinyang Wang ◽  
Kim L. Bennell ◽  
Yuanyuan Wang ◽  
Karine Fortin ◽  
David J. Saxby ◽  
...  

Abstract Background Anterior cruciate ligament reconstruction (ACLR) together with concomitant meniscal injury are risk factors for the development of tibiofemoral (TF) osteoarthritis (OA), but the potential effect on the patellofemoral (PF) joint is unclear. The aim of this study was to: (i) investigate change in patellar cartilage morphology in individuals 2.5 to 4.5 years after ACLR with or without concomitant meniscal pathology and in healthy controls, and (ii) examine the association between baseline patellar cartilage defects and patellar cartilage volume change. Methods Thirty two isolated ACLR participants, 25 ACLR participants with combined meniscal pathology and nine healthy controls underwent knee magnetic resonance imaging (MRI) with 2-year intervals (baseline = 2.5 years post-ACLR). Patellar cartilage volume and cartilage defects were assessed from MRI using validated methods. Results Both ACLR groups showed patellar cartilage volume increased over 2 years (p < 0.05), and isolated ACLR group had greater annual percentage cartilage volume increase compared with controls (mean difference 3.6, 95% confidence interval (CI) 1.0, 6.3%, p = 0.008) and combined ACLR group (mean difference 2.2, 95% CI 0.2, 4.2%, p = 0.028). Patellar cartilage defects regressed in the isolated ACLR group over 2 years (p = 0.02; Z = − 2.33; r = 0.3). Baseline patellar cartilage defect score was positively associated with annual percentage cartilage volume increase (Regression coefficient B = 0.014; 95% CI 0.001, 0.027; p = 0.03) in the pooled ACLR participants. Conclusions Hypertrophic response was evident in the patellar cartilage of ACLR participants with and without meniscal pathology. Surprisingly, the increase in patellar cartilage volume was more pronounced in those with isolated ACLR. Although cartilage defects stabilised in the majority of ACLR participants, the severity of patellar cartilage defects at baseline influenced the magnitude of the cartilage hypertrophic response over the subsequent ~ 2 years.


IUCrJ ◽  
2021 ◽  
Vol 8 (6) ◽  
Author(s):  
Liberato De Caro ◽  
Alberta Terzi ◽  
Luca Fusaro ◽  
Davide Altamura ◽  
Francesca Boccafoschi ◽  
...  

Glycosylation is the process of combining one or more glucose molecules (or other monosaccharides) with molecules of a different nature (which are therefore glycosylated). In biochemistry, glycosylation is catalyzed by several specific enzymes, and assumes considerable importance since it occurs mainly at the expense of proteins and phospholipids which are thus transformed into glycoproteins and glycolipids. Conversely, in diabetes and aging, glycation of proteins is a phenomenon of non-enzymatic nature and thus not easily controlled. Glycation of collagen distorts its structure, renders the extracellular matrix stiff and brittle and at the same time lowers the degradation susceptibility thereby preventing renewal. Based on models detailed in this paper and with parameters determined from experimental data, we describe the glycation of type 1 collagen in bovine pericardium derived bio-tissues, upon incubation in glucose and ribose. With arginine and lysine/hydroxylysine amino acids as the primary sites of glycation and assuming that the topological polar surface area of the sugar molecules determines the glycation rates, we modelled the glycation as a function of time and determined the glycation rate and thus the progression of glycation as well as the resulting volume increase.


2021 ◽  
Vol 9 (10) ◽  
pp. 1112
Author(s):  
Diogo Mendes ◽  
Joaquim Pais-Barbosa ◽  
Paulo Baptista ◽  
Paulo A. Silva ◽  
Cristina Bernardes ◽  
...  

In Aveiro (NW coast of Portugal), a coastal monitoring programme was carried out in sequence of a shoreface nourishment intervention (over than 2 M m3) performed in 2020. In this programme, almost one year of biweekly subaerial topographies and quarterly bathymetric surveys have been collected along a 10 km coastal stretch between June 2020 and June 2021. In this study, topographic and bathymetric surveys were analysed to assess the expectation that if the shoreface nourishment is located in sufficiently shallow water depths, its landward movement will feed adjacent beaches and, consequently, increase the subaerial beach volume. Results show that the subaerial beach volume is well correlated with the 1.05 m (above MSL) isoline displacement through time. While the seaward limit of the shoreface nourishment moved landwards about 200 m, the shoreline proxy (isoline of 1.05 m) displayed a maximum seaward displacement of 60 m. The displacement of the shoreline proxy was highly variable in space, along the 10 km coastal stretch, and also in time, during storm events. During such events, both landward and seawards displacement of the shoreline proxy took place, depending on the spatial position. Moreover, while beaches close to the initial shoreface nourishment intervention displayed faster accretion patterns than those located farther away, the well-defined onshore movement of the shoreface nourishment did not result in a considerable beach volume increase. The achieved results were also compared against case studies of shoreface nourishments with similar volumes performed worldwide.


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