Differential Stress Research Articles

Genesis of Antibiotic Resistance (AR) LXXXI: Turbulence Modeling of Simplified Severe Sepsis Protocol‐2 (SSSP‐2), NCT01663701: ERP Induced Fluid Volume Expansion Confer Transition from Laminar to Turbulence by Discontinuity

NCT01663701(PMID:28973227) observed that a primary outcome of in‐hospital mortality (ihm) occurred in 51 of 106 patients (48.1%) in the sepsis protocol group vs 34 of 103 patients (33.0%) in the usual care group while the vital status after hospital discharge at day 28 reported for 97 patients in each study group; 28‐day mortality was 67.0% with the sepsis protocol vs 45.3% with usual care. Hypothesis: Based on the data on risk of ihm by subgroup for patients treated with the sepsis protocol vs usual care (Fig3), compared to elements of sepsis resuscitation (Table 2), and baseline characteristics of the patients (Table 1), we hypothesize that the discontinuity in fluid volume due to ERP is the pivotal determining factor for an exacerbated mortality rate in NCT0166370. Relevance of Central Venous Pressure(CVP) or Jugular Venous Pressure (JVP) for the Determination of Fluid Overload(PMID: 23774337, PMID: 24132054):NCT01663701, p1237, Table 1: The JVP data indicate that the baseline: by proximity to the sternal angle, ≥4cm below: sepsis protocol cohort: 32.1% vs usual care: 40.8%; 1‐3cm below:sepsis protocol cohort: 28.3% vs usual care 21.4%; At the sternal angle, 20.8% vs 27.2%; ≥1 cm above: sepsis protocol 20.8% vsusual care 10.7%. Cause(s) of elevated CVP or JVP:A plausible cause would be RV failure (pulmonary edema!) due to fluid volume overload by excessive fluid administration. Geometry, Governing Eq. & Analysis: The mass continuity eq: 2.17, (p14‐ISBN‐13:978‐0521598866); where V1= fluid velocity, ρ1= fluid density, at terminal arteriole (cross‐sectional area) = A1and tis time interval dt, prior to ERP, length dl1=V1dt mass that enters the A1in the time interval is: dm1=ρ1dV1= ρ1A1dl1=ρ1A1v1dt. After the ERP, the expanded fluid volume passing through metarteriole (cross‐sectional area) =A2and length dl2=V2dt in the time interval dt is=dm2=ρ2dV2=ρ2A2dl2=ρ2A2v2dt. As per the mass continuity equation, (flow at any given point in a closed hydraulic system will be equal to flow at any other points) an equal amount of mass that enters the area A1in the time interval dt, must pass through area A2,therefore, dm1=dm2or ρ1A1v1dt=ρ2A2v2dt.Dividing by dt, will result ρ1A1v1=ρ2A2v2for a steady flow pattern referred to as mass continuity equation for steady flow. Our simulation analysis implicates that for the ERP induced fluid volume overload fluid flow is A1v1≠A2v2 . The rationale is that, the laminar fluid flow is in streamlines with equal space but ERP induced will not be in streamline but widely spaced, ⬆viscosity, ⬆ rate of LPE aggregation and ⬇velocity, ⬆torque & drag with an unknown angular momentum, on endothelial layer in terminal arteriole. Prospects: It is suggested that the total mass of expanded fluid vol. within 6 hrs, entering/exiting the terminal arteriole (Cerebral BBB) elicit CCP rupturing the pre‐capillary vessels due to an adverse pressure gradient (APG). Differential shear stress due to APG, induce temporal regulation of ARGR expression in clinical persisters in vivo w/ orw/o vasoplegia may have been the cause for an exacerbated mortality in NCT01663701.

P644. Preliminary Results on the Combined Role of Endocannabinoids and Cortisol in the Development of Post-Traumatic Stress and Dysphoria

Trauma survivors experience varied psychiatric outcomes (e.g., posttraumatic stress disorder [PTSD], depression). Research suggests that differential biological stress responding acutely after trauma may influence heterogeneity in outcomes. Specifically, individuals who develop dysphoria vs. post-traumatic stress (PTS) six months after trauma show higher post-injury cortisol.

Molecular Mechanisms Underlying Caveolin-1 Mediated Membrane Curvature.

Caveolin-1 is one of the main protein components of caveolae that acts as a mechanosensor at the cell membrane. The interactions of caveolin-1 with membranes have been shown to lead to complex effects such as curvature and the clustering of specific lipids. Here, we review the emerging concepts on the molecular interactions of caveolin-1, with a focus on insights from coarse-grain molecular dynamics simulations. Consensus structural models of caveolin-1 report a helix-turn-helix core motif with flanking domains of higher disorder that could be membrane composition dependent. Caveolin-1 appears to be mainly surface-bound and does not embed very deep in the membrane to which it is bound. The most interesting aspect of caveolin-1 membrane binding is the interplay of cholesterol clustering and membrane curvature. Although cholesterol has been reported to cluster in the vicinity of caveolin-1 by several approaches, simulations show that the clustering is maximal in membrane leaflet opposing the surface-bound caveolin-1. The intrinsic negative curvature of cholesterol appears to stabilize the negative curvature in the opposing leaflet. In fact, the simulations show that blocking cholesterol clustering (through artificial position restraints) blocks membrane curvature, and vice versa. Concomitant with cholesterol clustering is sphingomyelin clustering, again in the opposing leaflet, but in a concentration-dependent manner. The differential stress due to caveolin-1 binding and the inherent asymmetry of the membrane leaflets could be the determinant for membrane curvature and needs to be further probed. The review is an important step to reconcile the molecular level details emerging from simulations with the mesoscopic details provided by state of the art experimental approaches.

Relation between finite strain geometry and quartz petrofabrics in a folded conglomerate in the Norwegian Caledonides

A relationship between crystallographic preferred orientation (CPO) and strain geometry (strain-ellipsoid shape) is often assumed, but not well documented. In this work, we use the EBSD method to study quartz CPO and microstructure in relation to strain geometry in a folded conglomerate in the SW Scandinavian Caledonides, where strain varies from strongly flattening (long limbs) to constrictional (hinges and inverted short limb). Our work shows that strain was accommodated by dynamic recrystallisation through subgrain rotation, bulging and Dauphine twinning. Differential stress during deformation is estimated at ∼125 MPa from recrystallised grain size. Deformed and recrystallised grains show similar patterns of crystallographic orientation, despite a significant difference in grain size. We find no correlation between strain geometry and CPO, which we explain by means of a flow perturbation fold model. In this model, the variation in strain geometry is a result of progressive layer rotation during shearing. A correlation may be expected for steady-state deformations with no folding of layers with strain markers. However, flow perturbation may be a common cause of complex 3D strain patterns in sheared rocks. Hence, estimating strain geometry from CPO alone is inherently difficult and should be avoided unless a simple and steady deformation history can be assumed.

The Dependence on the Moho Depth of the b-Value of the Gutenberg–Richter Law

ABSTRACT We investigate the dependence of the Gutenberg–Richter b parameter on the crustal thickness quantified by the Moho depth, for nine different regional catalogs. We find that, for all the catalogs considered in our study, the b-value is larger in areas presenting a thicker crust. This result appears in apparent contradiction with previous findings of a b decreasing with the focal depth. However, both the results are consistent with acoustic emission experiments, indicating a b-value inversely proportion to the applied differential stress. Our results can be indeed interpreted as the signature of a larger stress concentration in areas presenting a thinner crust. This is compatible with the scenario where postseismic deformation plays a central role in stress concentration and in aftershock triggering.

Hydrogels as Corneal Stroma Substitutes for In Vitro Evaluation of Drug Ocular Permeation.

Hydrogels are complex hydrophilic structures, consisting of crosslinked homopolymers or copolymers insoluble in water. Due to their controllable bio-physicochemical properties mimicking the morphology of the native extracellular matrix, they are a key part of a lot of research fields, including medicine, pharmaceutics, and tissue engineering. This paper was focused on the preparation and characterization of hydrogels from different blends of polyvinyl alcohol (PVA) with microcrystalline cellulose (MCC) and gelatin (GEL) at various ratios, and from gelatin and chitosan alone to understand their feasibility of utilizing as corneal stroma substitutes in permeability tests for drug candidate molecules in early stages of their development. The characterization was carried out by differential scanning calorimetry, electron microscopy (SEM), water content, mass loss, water permeability, wettability, and tensile stress–strain tests. After the physicochemical characterization, PVA/MCC blend and chitosan proved to be the most promising constructs, showing negligible mass loss after immersion in aqueous medium for two weeks and low hydrodynamic permeability. They were then employed in drug molecules permeation studies and these data were compared to that obtained through excised tissues. The results obtained showed that PVA/MCC hydrogels have similar mechanical and permeability properties to corneal stroma.

Enhancement of polarization and magnetization in polycrystalline magnetoelectric composite

Electrical control of magnetization or magnetic control of polarization offers an extra degree of freedom in materials possessing both electric and magnetic dipole moments, viz., magnetoelectric (ME) multiferroics. A microstructure with polycrystalline configurations that enhances the overall polarization/magnetization and that outperforms single crystalline configurations is identified in a 1–3 CoFe2O4–BaTiO3 (or CFO–BTO) composite. The characterization of local fields corresponding to the polycrystal configuration underlines a nontrivial role played by randomness in better cross coupling mediated by anisotropic and asymmetric strains. The microscopic field (local field) profile of the composite provides rich information regarding the distribution of key parameters central to the magnetoelectric effect. The differential contractual stress level observed in the local stress profile of CFO–BTO composite upon applying an external magnetic field conforms with the previous experimental magnetostriction observed in CFO. The role played by residual stresses stemming from misalignment of the polarization in the neighboring grains in enhancing the ME coupling is briefly discussed.

Fluid inclusion evidence for extreme overpressure induced by gas generation in sedimentary basins

Abstract Formation and preservation of extremely high-pressure fluid in sedimentary basins is critical to understanding petroleum accumulation and basin evolution; however, this issue remains poorly understood due to a lack of key evidence. We present fluid inclusion evidence from the Paleozoic black shales in the eastern Sichuan Basin (South China block) that suggest that gas generation can form methane-saturated fluids with pressures significantly exceeding the lithostatic pressure. The fluid inclusion internal pressure is so high (e.g., ~77 MPa) that gas hydrate formed at ambient temperature, aqueous-vapor homogenization could not be achieved under ambient pressure, and the homogenization pressure was beyond the scope of the current equation of state for the NaCl-H2O-CH4 system. We infer that the formation of high-pressure (e.g., >230 MPa), methane-saturated fluids induces hydrofracture under weak compressional tectonic regimes, where the excess lithostatic fluids can be accumulated and sustained. Fluid inclusion records with an abnormally high magnitude of overpressure indicate small differential stress and thus can serve as a microscale indicator for tectonic quiescence.

Experimental and Computational Studies of Compression and Deformation Behavior of Hafnium Diboride to 208 GPa.

The compression behavior of the hexagonal AlB2 phase of Hafnium Diboride (HfB2) was studied in a diamond anvil cell to a pressure of 208 GPa by axial X-ray diffraction employing platinum as an internal pressure standard. The deformation behavior of HfB2 was studied by radial X-ray diffraction technique to 50 GPa, which allows for measurement of maximum differential stress or compressive yield strength at high pressures. The hydrostatic compression curve deduced from radial X-ray diffraction measurements yielded an ambient-pressure volume V0 = 29.73 Å3/atom and a bulk modulus K0 = 282 GPa. Density functional theory calculations showed ambient-pressure volume V0 = 29.84 Å3/atom and bulk modulus K0 = 262 GPa, which are in good agreement with the hydrostatic experimental values. The measured compressive yield strength approaches 3% of the shear modulus at a pressure of 50 GPa. The theoretical strain-stress calculation shows a maximum shear stress τmax~39 GPa along the (1−10) [110] direction of the hexagonal lattice of HfB2, which thereby can be an incompressible high strength material for extreme-environment applications.

A label-free biomarkers detection platform relied on a bilayer long-wave infrared metamaterials BioNEMS sensor

A novel approach based on optical Biological-Nano-Electro-Mechanical-Systems (BioNEMS) sensor is presented in this paper to provide highly sensitive and precise detection of biomolecules. The proposed BioNEMS sensor is relied on a bi-layer metamaterials structure, tuned by its wavelength. The presented biosensor consists of a BioNEMS membrane coated by Complementary Split Ring Resonators and an array of Split Ring Resonators cells on the substrate. While the immobilized bioreceptors adsorb the biomarkers (i.e. mRNA or protein), it causes a bending of the suspended membrane. This is due to the differential surface stress which is induced on the Nano-Electro-Mechanical-Systems structure. As a consequence, the coupling strength of two complementary metamaterial layers and thus the electromagnetic response of the biosensor are changed. Furthermore, the proposed device is designed and analyzed by numerical and analytical approaches in order to obtain its functional characteristics as follows: detection sensitivity of 21 967 nm/RIU, figure of merit of 327.8 RIU−1", mechanical sensitivity of 2.6 μm/Nm−1" and resonant frequency of 4.92 kHz. According to the obtained results, the functional characteristics of the proposed label-free biosensor show its high potential for highly sensitive and accurate molecule detections, disease diagnosis as well as drug delivery tests for Lab-On-Chip systems.

Parameter Studies on Hydraulic Fracturing in Brittle Rocks Based on a Modified Hydromechanical Coupling Model

In this paper, we present a numerical study of hydraulic fracturing in brittle rock by using particle flow simulation. The emphasis is put on the influence of in situ stress, differential stress, fluid injection rate, fluid viscosity and borehole size on hydraulic fracturing behavior. To this end, an improved hydromechanical coupling model is first introduced to better describe fluid flow and local deformation of particle-based rocks. A series of parameter sensitivity studies are then conducted under the framework of particle flow simulation. Modelling results suggest that the breakdown pressure and time to fracture both linearly increase with confining stress, and hydraulic fracturing patterns present a distinct transition from brittle to ductile. Fluid injection rate and fluid viscosity have similar influences on hydraulic fracturing propagation, their value decrease leads to borehole pressure decrement and time to fracture prolongation. However, the former mainly controls the time to initial cracking, while the latter largely decides the duration of fracturing propagation. As for borehole radius, its increases can directly enhance the fluid diffusion zone, which further intensifies the nonlinear property of borehole pressure, leads to breakdown pressure decrease, prolongs time to fracture and forms more complex hydraulic fractures.

The quantitative characterization of hydraulic fracture connectivity from a postmortem investigation

AbstractTwo bio-siliceous Onnagawa (ONG I and ONG II) shale samples have been hydraulically fractured under two constant differential stresses (60 and 85 MPa, respectively) to investigate the fracture network's connectivity evolution by a postmortem analysis. The pressure inside the drilled borehole in a cylindrical core sample is increased above the confining pressure (10 MPa) until failure by hydraulic fracture. The two samples failed at two different borehole pressures (ONG I: 42 MPa, ONG II: 16 MPa). Fractured samples were scanned in an industrial X-ray CT machine and the tomographic images of the fracture network were extracted for a postmortem investigation. From the fracture volume segments, obtained by thresholding the frequency distribution of the fracture network's voxel values, a quantitative estimation of fracture connectivity was carried out. The connectivity was quantified based on the relative entropy of size distribution of fractures (${H_r}$), a method adapted from information theory. Fracture connectivity estimation shows that ${H_r}$ is at a maximum value when the fractures show a significant distribution with very limited connectivity. The value of ${H_r}$ is at a minimum and close to 0 when a well-linked fracture network is formed. In both samples, this minimum was attained at the threshold of 43k indicating the highest connectivity and the best representation of the fracture network. The extracted fracture network of ONG I showed a multi-winged hydraulic fracture network while a planar conventional two-winged hydraulic fracture network had been generated in ONG II with a lower fracture volume.

Novel GxE effects and resilience: A case:control longitudinal study of psychosocial stress with war-affected youth.

Responses to early life adversity differ greatly across individuals. Elucidating which factors underlie this variation can help us better understand how to improve health trajectories. Here we used a case:control study of refugee and non-refugee youth, differentially exposed to war-related trauma, to investigate the effects of genetics and psychosocial environment on response to trauma. We investigated genetic variants in two genes (serotonin transporter, 5-HTT, and catechol-O-methyltransferase, COMT) that have been implicated in response to trauma. We collected buccal samples and survey data from 417 Syrian refugee and 306 Jordanian non-refugee youth who were enrolled in a randomized controlled trial to evaluate a mental health-focused intervention. Measures of lifetime trauma exposure, resilience, and six mental health and psychosocial stress outcomes were collected at three time points: baseline, ~13 weeks, and ~48 weeks. We used multilevel models to identify gene x environment (GxE) interactions and direct effects of the genetic variants in association with the six outcome measures over time. We did not identify any interactions with trauma exposure, but we did identify GxE interactions with both genes and resilience; 1) individuals with high expression (HE) variants of 5-HTTLPR and high levels of resilience had the lowest levels of perceived stress and 2) individuals homozygous for the Val variant of COMT with high levels of resilience showed stable levels of post-traumatic stress symptoms. We also identified a direct protective effect of 5-HTTLPR HE homozygotes on perceived insecurity. Our results point to novel interactions between the protective effects of genetic variants and resilience, lending support to ideas of differential susceptibility and altered stress reactivity in a cohort of war-affected adolescents.

Regional‐Scale Low‐Angle Normal Fault Friction and Cohesion Constrained From Mohr‐Coulomb Models of Active and Abandoned Range‐Front Faults in Papua New Guinea

AbstractLow‐angle normal faults (LANFs) are poorly understood, as their slip at <30° dips appears inconsistent with Byerlee friction and Andersonian stresses. Rider blocks are fault slices formed when the uppermost part of a LANF is abandoned in favor of a new, steeper fault. Mohr‐Coulomb modeling of rider blocks can constrain fault frictional and cohesive strength provided known fault geometries. Analytical modeling shows that LANF viability depends on fault geometry and on the frictional and cohesive strength of the fault relative to that of the surrounding crust. Modeling of the Gwoira rider block, located atop the Mai'iu LANF, southeastern Papua New Guinea, indicates that this fault segment is frictionally weak (0.04 ≤ µf ≤ 0.17) in the shallow crust, with neither non‐Andersonian stresses nor supra‐hydrostatic fluid pressures required. Such weakness favors slip localization onto a single fault, enabling rapid slip rates at shallow dips. We show that slip at a second site, which lacks a rider block, does not require a weak fault because of a large fault/crust cohesion contrast and a rapid steepening of dip on the convex‐upward fault from only 21° at the surface to >30° down‐dip. From our results, we characterize four possible styles of faulting on convex‐up normal faults: (a) total fault slip, (b) footwall damage, (c) fault partial abandonment, and (d) total fault abandonment. Our results reveal that LANF faulting style depends on the strength of the fault compared to the surrounding crust, fault geometry, and the distribution of differential stress required for slip as a function of depth.

Effect of confining pressures on transverse isotropy of Maha Sarakham salt

Uniaxial and triaxial compression tests have been performed on prismatic specimens of rock salt under confining pressures (σ3) up to 40 MPa. The specimens contain different bedding plane orientations with respect to the major axis. Results indicate that transverse isotropic effects occur under low confinement where the salt strength is lowest when the normal to bedding planes makes an angle (β) of 60° with the major principal axis. The lowest intrinsic elastic modulus is obtained at β = 0°, and the highest is at β = 90°. The apparent elastic parameters measured for 0° < β < 90° agree well with those predicted by Amadei's solutions. The confining pressures rapidly increase the elastic and shear moduli normal to bedding plane strike, and eventually they reach those parallel to the bedding planes under σ3 about 30 MPa. Loading the salt under high confinement induces some plastic deformation, as evidenced by the evolution of Ramberg and Osgood's parameters with the confining pressures. The confining pressures gradually tighten the inter-crystalline boundaries along bedding planes, and hence the applied differential stress can no longer recognize their transverse isotropic textures. The salt strengths for all bedding orientations become equal under σ3 above 30 MPa. The proposed exponential equation is capable of describing the salt dilations and strengths under unconfined to highly confined conditions. Distortional strain energy (Wd) induced at dilation linearly increases with mean strain energy (Wm). The Wd-Wm relation for β = 60° can represent the dilation of the salt from low to high confinements where the mechanical responses of the rock transitionally change from transverse isotropic to isotropic behavior. The Wd-Wm relations for β ≠ 60° are applicable only for confining pressures less than 30 MPa.

Exploring deep carbonate reservoir samples: Anisotropy and correlation of static and dynamic Young’s moduli

In total, 14 limestone samples, drilled in the vertical and horizontal directions from a depth &gt;3 km, are analyzed to understand the correlation between static (operating at in-situ strain levels) and dynamic (at a sound wave strain level) Young’s moduli, [Formula: see text] and [Formula: see text], and also to investigate their directional dependence. Young’s moduli are measured simultaneously under a confining pressure of 30 MPa to a differential axial stress of 50 MPa using a triaxial frame with linear variable differential transformers: two axial and one radial calibrated with a standard aluminum slug. Static and dynamic moduli decrease with increasing porosity whereas the static moduli are typically less than the dynamic moduli. The static measurements exhibit significant hysteresis indicating a nonlinear (irreversible) regime, whereas the dynamic moduli, measured with low-strain amplitude, indicate a linear (reversible) regime. The static Poisson’s ratio increases with porosity, but the dynamic ratio remains unchanged over the whole range of porosity, which seems to not be sensitive enough to the heterogeneity in the pore structure. The induced microfractures, naturally developed under tensile stress after these deep samples were brought to the surface, are imaged in computer microtomography (micro-CT) scan experiments. The mineralogical composition is determined as higher than 95% calcite CaCO3and mapped out using quantitative evaluation of minerals by scanning electron microscopy. Elastic anisotropy is observed with increasing porosity, where the ratio [Formula: see text]/[Formula: see text] increases for the vertical but decreases for the horizontal samples. Likewise, a permeability anisotropy also is observed as porosity increases, where the ratio of the vertical to horizontal permeability [Formula: see text]/[Formula: see text] is higher than one, indicating a preferred vertical structure for fluid flow. Two linear correlations between [Formula: see text] and [Formula: see text] are developed for the studied calcite samples, and for samples composed of up to 30% dolomite CaMg(CO3)2reported in the literature.

Peritectic and phenocrystic garnet accumulation and the origin of strongly peraluminous granitic rocks: The Flagstaff Lake Igneous Complex, Maine

The Flagstaff Lake Igneous Complex of Maine contains a metaluminous phase that ranges from diorite to granite, and three phases of strongly peraluminous, garnet-bearing rocks with silica contents that range between 43 and 59 wt%. These peraluminous rocks have increasing amounts of normative corundum with increasing maficity, indicating that they do not represent liquid compositions, rather garnet accumulation accounts for their bulk-rock A/CNK compositions. Garnet in these rocks displays a variety of textures, inclusion patterns, and trace element compositions. The Loon Lake phase is characterized by garnet with abundant, randomly distributed apatite inclusions. Some grains have spiral inclusion patterns that are peritictic grains formed during partial melting of source rocks while they were undergoing differential stress. In contrast, the Quarry Phases A and B contain inclusion-free garnet with euhedral grain boundaries. These grains have trace element profiles indicative of crystal fractionation processes and are interpreted to be phenocrysts. Some of these phenocrysts have inclusion poor, resorbed cores that are mantled by inclusion-free overgrowths. The cores have lower concentrations of compatible trace elements and higher concentrations of incompatible elements than the mantles. These cores are resorbed phenocrysts from an evolved magma that were mingled in a more primitive, garnet crystallizing magma. Also present in Quarry Phase B rocks are a minor population of inclusion-rich garnets with random inclusion distributions. These are also interpreted as peritectic garnet, entrained from the source, or from dehydration melting of country rock biotite. They are mantled by inclusion-free garnet with the same composition as the phenocrysts and are phenocrystic overgrowths. Thus, the original Flagstaff Lake anatectic melts were mildly peraluminous with the current bulk-rock compositions of the garnet tonalites dominated by the accumulation of variable portions of phenocrystic garnet or the entrainment of peritictic garnet, both of which generated the increasing peraluminosity with increasing maficity of the complex. Magmatic, mafic enclaves present in the peraluminous rocks are similar to the metaluminous, main phase rocks of the complex, suggesting that the coeval basaltic magmas provided the heat for anataxis to generate the peraluminous magmas.

The Young’s Modulus and Poisson’s Ratio of Hard Coals in Laboratory Tests

The Young’s modulus and Poisson’s ratio, parameters reflecting the elastic response of a rock to stress, are the key parameters used in many engineering activities, such as hard coal mining and natural gas extraction. The objective of this paper was to present the results of complex laboratory measurements of the static and dynamic Young’s modulus and Poisson’s ratio for Upper Carboniferous hard coals from the Upper Silesian Coal Basin. The coals differed in geologic age (Mudstone Series—younger coals; Upper Silesian Sandstone Series—older coals) and petrographic structure (vitrain, clarain, and durain lithotype). Elastic parameters of the coals were determined following compression tests under a complex state of stress, as well as using the ultrasonic method in reservoir conditions. On this basis, linear functional dependences between parameters such as UCS, differential stress, confining pressure, strain rate, P- and S-wave velocities, and the static and dynamic Young’s modulus and Poisson’s ratio were determined. These dependences turned out to be linear, with strong and very strong correlation, as indicated by the high coefficients of determination, R2. These new results significantly broaden the knowledge of elastic properties of Carboniferous hard coals, especially in the field of geoengineering, underground coal gasification, and reservoir stimulation for coal bed methane extraction.

Varied Simulation-based Stress Analyses on Zirconia All-ceramic Crowns

The development of high-strength ceramics and its use in posterior areas has been a field of constant investigation. The performance of all-ceramic molar crowns fabricated with new CAD/CAM techniques is a subject of interest. The studies available in literature focused on the analysis of all-ceramic restorations failures, investigating several parameters involved on the tooth structure. The goal of this study was to investigate the stress distributions of zirconia - all ceramic crowns, under loads using varied stress distribution analyses. A static structural analysis was performed to calculate the stress distribution using the computer-aided engineering software. Equivalent stresses were recorded in the tooth structures and in the restoration for all these designs. Since ceramic materials exhibit brittle behavior, the first principal stress criterion was adopted to compare the stress values and distribution with those obtained for the first simulations. Under the same loading conditions, the stress distribution patterns for the zirconia all-ceramic crown using differential stress analyses exhibited similarities. Only the values are lower for the maximal principal stresses. The present study suggests that varied simulation methods are promising to assess the biomechanical behaviour of all-ceramic systems.

Multi-stage evolution of the South Tibetan Detachment System in central Himalaya: Insights from carbonate-bearing rocks

Low-angle normal faults (LANFs) are increasingly described in collisional orogens and are getting attention in modelling in regard to mass distributions, exhumation history, and the rheology of the continental crust during plate collision. Their kinematic evolution, however, is still not fully understood. We present a microstructural study of a key example of a LANF in a syn-collisional setting, i.e., the ductile portion of the South Tibetan Detachment System (STDS) in the Lower Dolpo region (central Himalaya). New data are provided on microstructural characteristics, crystallographic preferred orientations of calcite and quartz as well as of paleopiezometric and kinematic vorticity analyses. Two main stages of non-coaxial shearing from lower to higher crustal levels, here referred as D2early and D2late, are recognized. D2early developed higher temperatures (c. 600–400 °C traced up-section within the STDS) and at low differential stress (<15 MPa). D2late occurred at lower temperatures (T < 350 °C) and differential stress larger than 100 MPa at comparable strain rates with D2early. Cooling and differential stress increased from D2early to D2late, indicating progressive exhumation following typical lithospheric strength profiles. Vorticity data highlight a pure shear component that can account for the up-section telescoping of the paleo-isotherms. Our findings support a strain hardening of the STDS, where ductile shearing persisted to shallower levels, without necessarily localizing a prominent upper brittle fault.