Propagation Of Strain Research Articles

Distribution and propagation of stress and strain in cube honeycombs as trabecular bone substitutes: Finite element model analysis

For designing trabecular (Tb) bone substitutes suffering from osteoporosis, finite element model (FEM) simulations were conducted on honeycombs (HCs) of 8 × 8 × 1 (2D) and 8 × 8 × 8 (3D) assemblies of cube cellular units consisting of 0.9 mm long Nylon® 66 (PA, Young's modulus E: 2.83 GPa) and polyethylene (PE, E: 1.1 GPa) right square prisms. Osteoporotic damage to the Tb bone was simulated by removing the inner vertical struts (pillars; the number of removed pillars: Δn ≤ 300) and by thinning the strut (thickness, d: 0.4–0.1 mm), while the six facade lattices were kept flawless. Uniform and uniaxial compressive loads on the HCs induced elastic deformation of the struts. The pillars held almost all the load, while the horizontal struts (beams) shared little. E for PA 3D HCs of all d smoothly decreased with Δn. PA 3D HCs of 0.2 mm struts deserved to be the substitutes for Tb bone, while PE 3D HCs of 0.05 mm struts were only for the Tb bone of the poorest bone quality. For the PA 3D HCs, the maximum von Mises stress (σM) first rapidly increased with Δn and showed a break at Δñ50, then gradually approached the yield stress of PA (50 MPa). Moreover, small portions of the stress were transferred from the façade pillars to the adjacent inner beams, especially those near the lost-pillar sites, denoted as X defects. The floor beams of thinner struts associated with the X-defects were lifted, and similar lifting effects in smaller amounts were propagated to the other floors. The 3DHCs of the thicker struts showed no such flexural deformations. The concept of force percolation through the remaining struts was proposed to interpret those mechanical behaviors of the HCs.

Effects of cutting tool geometry on material removal of a gradient nanograined CoCrNi medium entropy alloy.

CoCrNi medium-entropy alloys (MEAs) have attracted extensive attention and research because of their superior mechanical properties, such as higher ductility, strength, and toughness. This study uses molecular dynamics (MD) simulations to investigate the cutting behavior of a gradient nanograined (GNG) CoCrNi MEA. Moreover, it explores the influence of relative tool sharpness and rake angle on the cutting process. The results show that an increase in the average grain size of the GNG samples leads to a decrease in the average resultant cutting force, as predicted by the Hall-Petch relationship. The deformation behavior shows that grain boundaries are crucial in inhibiting the propagation of strain and stress. As the average grain size of the GNG sample increases, the range of shear strain distribution and average von Mises stress decreases. Moreover, the cutting chips become thinner and longer. The subsurface damage is limited to a shallow layer at the surface. Since thermal energy is generated in the high grain boundary density, the temperature of the contact zone between the substrate and the cutting tool increases as the GNG size decreases. The cutting chips removed from the GNG CoCrNi MEA substrates will transform into a mixed structure of face-centered cubic and hexagonally close-packed phases. The sliding and twisting of grain boundaries and the merging of grains are essential mechanisms for polycrystalline deformation. Regarding the cutting parameters, the average resultant force, the material accumulation, and the chip volume increase significantly with the increase in cutting depth. In contrast to sharp tools, which mainly use shear deformation, blunt tools remove material by plowing, and the cutting force increases with the increase in cutting-edge radius and negative rake angle.

Optimization of the replication of hepatitis E virus genotype 3 in vitro.

Hepatitis E virus (HEV) is responsible for ∼20 million human infections worldwide every year. The genotypes HEV-3 and HEV-4 are zoonotic and are responsible for most of the autochthonous HEV cases in high-income countries. There are several cell culture systems that allow for propagation of different HEV genotypes in vitro. One of these systems uses human lung carcinoma cells (A549), and was further optimized for propagation of HEV-3 47832c strain. In this study, we investigated the effect of different media supplements as well as microRNA-122 (miR-122) on improving the replication of HEV-3 47832c in A549 cells. We observed that supplementation of maintenance media with 5% fetal bovine serum was sufficient for efficient replication of HEV-3, and verified the positive effect of media supplementation with Amphotericin B, MgCl2, and dimethyl sulfoxide on replication of HEV-3. We have also demonstrated that adding miR-122 mimics to the culture media does not have any significant effect on the replication of HEV-3 47832c. Herein, we detected over a 6-fold increase in HEV-3 replication in A549/D3 cells by adding all three supplements: Amphotericin B, MgCl2, and dimethyl sulfoxide to the culture media, while demonstrating that miR-122 might not play a key role in replication of HEV-3 47832c.

The Full-Genome Analysis and Generation of an Infectious cDNA Clone of a Genotype 6 Hepatitis E Virus Variant Obtained from a Japanese Wild Boar: In Vitro Cultivation in Human Cell Lines.

Hepatitis E virus (HEV) can cause self-limiting acute and chronic hepatitis infections, particularly in immunocompromised individuals. In developing countries, HEV is mainly transmitted via drinking contaminated water, whereas zoonotic transmission dominates the route of infection in developed countries, including Japan. Pigs are an important reservoir for HEV infection. Wild boars, which share the same genus and species as domestic pigs, are also an HEV reservoir. During our nationwide study of HEV infection in wild boar populations in Japan, a genotype 6 (HEV-6) strain, wbJHG_23, was isolated in Hyogo Prefecture in 2023. The genomic length was 7244 nucleotides, excluding the poly(A) tract. The wbJHG_23 strain exhibited the highest nucleotide identity throughout its genome with two previously reported HEV-6 strains (80.3-80.9%). Conversely, it displayed lower similarity (73.3-78.1%) with the HEV-1-5, HEV-7, and HEV-8 strains, indicating that, although closely related, the wbJHG_23 strain differs significantly from the reported HEV-6 strains and might represent a novel subtype. The wbJHG_23 strain successfully infected the human-derived cancer cell lines, PLC/PRF/5 and A549 1-1H8 cells, suggesting that HEV-6 has the potential for zoonotic infection. An infectious cDNA clone was constructed using a reverse genetics system, and a cell culture system supporting the efficient propagation of the HEV-6 strain was established, providing important tools for further studies on this genotype. Using this cell culture system, we evaluated the sensitivity of the wbJHG_23 strain to ribavirin treatment. Its good response to this treatment suggested that it could be used to treat human infections caused by HEV-6.

Insights into Newcastle disease: Isolation and propagation of non-virulent strain for antigen production

Insights into Newcastle disease: Isolation and propagation of non-virulent strain for antigen production

Study of a tick-borne encephalitis vaccine

Scientific relevance. Tick-borne encephalitis is one of the most significant anthropozoonoses for public health in the Russian Federation. Wide vaccination coverage is required to control this zoonotic infection. However, large-scale immunisation is not feasible without developing novel vaccines with improved safety and efficacy profiles, such as vaccines based on the continuous Vero cell line.Aim. This extended study aimed to investigate the key quality attributes of VeroKSEN, a new tick-borne encephalitis vaccine that was obtained using Vero cells.Materials and methods. The authors implemented current approaches to vaccine development, including propagation of tick-borne encephalitis strain 205 (Far Eastern subtype) in Vero cells, fine purification of the viral antigen by size-exclusion chromatography on polymeric resins, and introduction of additional quality control methods. For VeroKSEN production, the authors used the method protected by utility patent No. 2678431. Quality control of the finished product was performed according to the State Pharmacopoeia of the Russian Federation. The laboratory study of the vaccine and its intermediates in Balb/с mice used novel control methods developed by the authors. Additional methods included polyacrylamide gel electrophoresis, enzyme immunoassay, immunoblotting with total antibodies to tick-borne encephalitis virus and monoclonal antibodies to glycoprotein E, reverse transcription–polymerase chain reaction, and high-performance liquid chromatography. The extended potency study used test strains of different subtypes, including Absettarov (Western), Sofjin (Far Eastern), and Korzukhin (Siberian). The authors studied the infectious activity of tick-borne encephalitis virus in outbred mice using the pharmacopoeial titration method. Statistical analysis of the study results involved calculating the arithmetic mean and the root-mean-square deviation.Results. The authors studied the key quality attributes of VeroKSEN and its intermediates. Selected inactivation conditions reduced the infectious activity of the viral harvest to an undetectable level within 24 h, while its antigenic activity remained approximately 100% of the baseline. The fine purification stages and the methods and techniques developed by the authors provided a whole-virion fraction with a purity of up to 98.2% and removed process-related impurities (residual host-cell DNA, bovine serum albumin, formaldehyde, and bacterial endotoxins) to the levels required by national legislation. The stability study demonstrated that the vaccine met the requirements for up to 36 months.Conclusions. The study showed the high potency of the new vaccine in terms of protection against the Western, Siberian, and Far Eastern subtypes of tick-borne encephalitis, with minimum immunising doses (MID50) of 0.007, 0.00125, and 0.00093 mL, respectively.

Hypocenter‐Based 3D Imaging of Active Faults: Method and Applications in the Southwestern Swiss Alps

AbstractDespite the fact that earthquake occurrence can be strongly influenced by the architecture of pre‐existing faults, it remains challenging to obtain information about the detailed subsurface geometries of active fault systems. Current geophysical methods for studying such systems often fail to resolve geometrical complexities at sufficiently high spatial resolutions. In this work, we present a novel method for imaging the detailed 3D architectures of seismically active faults based on high‐precision hypocenter catalogs, using nearest neighbor learning and principal component analysis. The proposed approach enables to assess variations in fault instabilities and kinematics. We apply the method to the relatively relocated St. Léonard (max.ML = 3.2) and Anzère (max.ML = 3.3) microearthquake sequences in the Southwestern Swiss Alps, revealing strike‐slip fault systems with interconnecting stepovers at depths of 3–7 km and lengths ranging from 0.5 to 2 km. In combination with additional information about fault instabilities and kinematics, we observe significantly reduced earthquake migration velocities and fault locking processes within the stepovers. Understanding such processes and their role in the propagation of strain across stepovers is of great relevance, as these structures can potentially limit earthquake ruptures but also represent possible locations for the nucleation of larger ruptures. Our proposed method is expected to be broadly useful for further applications such as monitoring hydraulic fracture stimulations or geothermal exploration of natural, fluid‐bearing faults. Conducting similar high‐resolution spatiotemporal analyses of microseismic sequences has the potential to greatly enhance our comprehension of how the 3D fault architecture impacts seismogenic fault reactivation.

Achieving high ductility in a 1.4 GPa grade medium Mn lightweight TRIP/TWIP steel with hierarchical lamellar structure

The present work reports a tri–phase hierarchical lamellar structure to tailor the ultra–high yield strength and high ductility balance in a novel Si–Al added medium Mn lightweight TRIP/TWIP steel. The warm–rolled sample was subjected to small cold rolling and low–temperature tempering to obtain the nano–scale twins and martensitic laths in the austenitic matrix, together with the hard δ–ferrite with nano–precipitates. The yield strength of 1403 MPa was obtained in the tempered sample, which is 370 MPa higher than the warm–rolled counterpart. Interestingly, the hard zone (δ–ferrite) confined the propagation of the plastic strain, leading to an intrinsic hetero–deformation induced (HDI) strengthening effect. The large ductility of 30% was ascribed to the large yield point elongation and the enhanced strain hardening after the Lüders strain, which is closely associated with HDI hardening and extra TRIP/TWIP effects.

Effects of crystal orientation and twin boundary distance on mechanical properties of FeNiCrCoCu high-entropy alloy under nanoindentation

The effect of crystal orientation and twinning on the mechanical characteristics and microstructure development of the equiatomic FeNiCrCoCu high-entropy alloy is explored and quantified by nanoindentation using molecular dynamics. The substrate hardness and discontinuity in the loading curves are strongly influenced by various crystal orientations due to differences in microstructural evolution and dissimilar dislocation events. The Hall-Petch aspect representing the correlation between the twinning distance and the material strength is found with decreasing the twin boundary distance. The plastic deformation exposes that the propagation of local stress and shear strain into the substrate bulk is dependent on crystal orientation, characterized through the various directions of the slipping bands. Meanwhile, the growth of shear bands into the substrate is easier with the great twin boundary distance, which can enhance the ductility of the alloy. The microstructural evolution suggests that the sliding prismatic dislocation loops in the substrate play a significant role in deformation. The displacement of the dislocation loops into the substrate depends on the crystal orientation, and their propagation is inhibited by the twin boundary. The various surface morphologies of the substrate are dominated by the sliding mechanism of the atoms following the symmetry of <11‾0 >{111} primary sliding system. Besides, the pile-up height tends to increase with the decrease of the twinning distance because the interaction between the sliding system and the twinning occurs more for the small twin boundary distance.

Dynamical limits for the molecular switching in a photoexcited material revealed by X-ray diffraction

Time-resolved studies with temporal resolution that separate molecular level dynamics from macroscopic changes, allow clear distinction between the time scales of the different degrees of freedom involved. Cooperative molecular switching in the solid state is exemplified by spin crossover phenomenon in crystals of transition metal complexes. Here we show the existence of a delay between the crystalline volume increase, and the cooperative macroscopic switching of molecular state. Using 100 ps X-ray diffraction, we track the molecular spin state and the structure of the lattice during the photoinduced low spin to high spin transition in microcrystals of [FeIII(3-MeO-SalEen)2]PF6. Model simulations explain the phenomenon with thermally activated kinetics governed by local energy barriers separating the molecular states. Such behaviour is different from that encountered in materials with no local energy barriers, where phase transformation can occur simultaneously with propagation of strain. Broadly, this motivates an optimised material design, scalable with size and intrinsic energetics.

Inertial artifact in viscoelastic measurements of striated muscle: Modeling and experimental results

Viscoelastic properties of striated muscle are often measured using length perturbation analysis and quantified as a complex modulus, whose elastic and viscous components reflect the energy-storage and energy-absorbing properties of the tissue, respectively. The energy stored as inertia is commonly ignored due to the small size of samples examined, typically <1 mm. Considering recent advances in tissue engineering to generate muscle tissues of larger sizes, we questioned whether ignoring the inertial artifact was still reasonable in these samples. To answer this question, we derived and solved the one-dimensional wave equation that describes the propagation of strain along the length of a sample. The inertial artifact was predicted to contaminate the elastic modulus with (2πf)2L02ρ/6, where f is perturbation frequency, L0 is muscle length, and ρ is muscle density. We then measured viscoelastic properties up to 500 Hz in mouse skeletal muscle fibers at long (4.8 mm) and short (<1 mm) lengths and up to 100 Hz in rat cardiac slices at long (10–12 mm) and short (<2 mm) lengths. We found the elastic modulus of long preparations was elevated as frequency increased and was about half the magnitude of that predicted by the model. While the prediction tended to overestimate the measured inertial artifact, these results provided some validity to the model. We used the predicted artifact as an overly conservative estimate of error that might arise in a mechanics assay of mammalian striated muscle, whose nominal resting stiffness is on the order 100 kN m−2. We found that muscle lengths of <1 mm resulted in negligible inertial artifact (<0.5% error) for perturbation frequencies under 250 Hz. Muscle samples longer than 5 mm, on the other hand, would result in >5% error at frequencies of 200 Hz and higher.

Evolution of laser-induced strain in a Ge crystal for the [111] and [100] directions probed by time-resolved X-ray diffraction

Ultra-short laser-pulse-induced strain propagation in a Ge crystal is studied in the [111] and [100] directions using time-resolved X-ray diffraction (TXRD). The strain propagation velocity is derived by analysis of the TXRD signal from the strained crystal planes. Numerical integration of the Takagi–Taupin equations is performed using open source code, which provides a very simple approach to estimate the strain propagation velocity. The present method will be particularly useful for relatively broad spectral bandwidths and weak X-ray sources, where temporal oscillations in the diffracted X-ray intensity at the relevant phonon frequencies would not be visible. The two Bragg reflections of the Ge sample, viz. 111 and 400, give information on the propagation of strain for two different depths, as the X-ray extinction depths are different for these two reflections. The strain induced by femtosecond laser excitation has a propagation velocity comparable to the longitudinal acoustic velocity. The strain propagation velocity increases with increasing laser excitation fluence. This fluence dependence of the strain propagation velocity can be attributed to crystal heating by ambipolar carrier diffusion. Ge is a promising candidate for silicon-based optoelectronics, and this study will enhance the understanding of heat transport by carrier diffusion in Ge induced by ultra-fast laser pulses, which will assist in the design of optoelectronic devices.

Evaluation of In(Ga)As capping in a multilayer coupled InAs quantum dot system: Growth strategy involving the same overgrowth percentage

Strain-coupled multilayer Quantum Dot (QD) structures draw a great attention these days because of their superior optical and device performance. However, these coupled multilayer QD structures have limitations such as non-uniform QD size distribution, defects, and dislocations due to the propagation of strain in QD layers. Furthermore, the carrier relaxation lifetime must be improved in these coupled QD structures for sought-after device performance. This study serves for three main purposes. Firstly, we have utilized a growth strategy to maintain the overgrowth percentage such that the Stranski-Krastanov (SK) QD dimensions in every layer is same for all the multilayer structures. Secondly, these multilayer SK QDs are made to electronically couple with the Sub-monolayer (SML) QDs in such a way that the carrier relaxation lifetime can be increased, that could ameliorate the photoconductive gain and the responsivity. Lastly, the amount of cumulative strain generated inside QDs can be reduced by the incorporation of In0.15Ga0.85As strain reducing layer (capping layer) in a multilayer structure. Five different multilayer structures with single (x1), bi (x2), penta (x5), hepta (x7), and ten-layers (x10) of SK QDs electronically coupled to six stacks of SML QDs are used in this study. Photoluminescence (PL) studies reveal that the SK QD dimensions is maintained to be the same in all multilayer structures due to the proposed growth strategy, which is also observed through transmission electron microscopy (TEM) images. Photoluminescence excitation (PLE) analysis shows the match of excited states of SK QDs to the ground state of the SML QDs, aiding the carrier tunnel phenomena. The ω/2Ө measurements from high resolution X-ray diffraction (HRXRD) is carried out to calculate the overall strain in the grown heterostructures. The optical properties and the strain components obtained from the nextnano simulation tool are in good agreement with the experimental results. Thus, coupled multilayer QD structures with a growth strategy in the current study would be more suitable for the realization of quantum dot infrared photodetectors and intermediate band solar cell applications accommodated with high device efficiency.

Tectono-Thermal Evolution of the Red Sea Rift

The Oligocene-Recent Red Sea rift is one of the preeminent examples of lithospheric rupture in the recent geological past, forming the basis for many models of how continental breakup occurs and progresses to the formation of new oceanic crust. Utilisation of low-temperature thermochronology in the Red Sea Rift since the 1980s has been key to constraining its spatio-temporal evolution, providing constraints for the propagation of strain and geomorphological development of its margins where datable syn-tectonic strata and/or markers are absent. We review the wealth of published apatite fission track and (U-Th-Sm)/He data from along the Red Sea, affording insights into the Oligocene-Recent thermo-tectonic evolution of the Nubian and Arabian margins. A regional interpolation protocol was employed to synthesise time-temperature reconstructions generated from the mined thermochronology data and burial histories produced from vitrinite reflectance and well data. These cooling-heating maps record a series of pronounced episodes of upper crustal thermal flux related to the development of the Oligocene-Recent Red Sea Rift. Assimilation of these regional thermal history maps with paleogeographic reconstructions and regional magmatic and strain histories provide regional perspectives on the roles of tectonism and geodynamic activity in Red Sea formation and their effects on rift margin development.

Mechanical, magnetic and magnetostrictive properties of porous Fe-Ga films prepared by electrodeposition

Magnetostriction, known as the ability of magnetic materials to expand or contract in response to magnetic field, is a key property of Fe-Ga alloys exploited in various types of transducers. Usually, thin films of Fe-Ga deposited on rigid substrates suffer from a clamping effect that hinders the propagation of strain. Herein, Fe-Ga films with macroporous, not fully constrained, geometry are prepared by electrodeposition on metallized silicon substrates templated with sub-micrometer-sized polystyrene spheres. For comparison, fully-dense and inherently nanoporous films are prepared by sputtering and electrodeposition, respectively. The electrodeposition mechanism is discussed in terms of electrochemically active species distribution and partial current densities. The composition of the Fe-Ga films has been tuned (2–40 at.% Ga) by varying the electrodeposition parameters. A complete assessment of the nanomechanical and magnetic properties of the films with variable composition and porosity has been performed for an optimized performance. The magnetostriction has been studied by X-ray diffraction applying an in-situ magnetic field. The results demonstrate a larger magnetic-field-induced crystal deformation in templated (macroporous) films compared to the non-templated and fully-dense counterparts. The observed effects in porous Fe-Ga films are very appealing for the design of various strain-engineered nanomaterials, e.g., energy transducers or magnetoelectric composites.

Adaptation and characterization of Anatid herpesvirus 1 in different permissible cell lines

Duck viral enteritis is an acute, contagious infection of Anatidae family members. The disease is caused by Anatid herpesvirus 1 (AnHV-1). The infection of AnHV-1 is controlled by vaccination to the flock with chick embryo adapted attenuated vaccine in developed countries. However, its economic impact in developing countries is substantial and there is a need to understand the cell culture spectrum of the virus to produce its vaccine on a mass scale. In the present study, the permissivity of AnHV-1 for different cells was analyzed. The AnHV-1 showed enhanced replication following its serial passage in CEF, DF-1, Vero, MDCK, and QT-35 cells. The characteristic cytopathic effect (CPE) of rounding and clumping of cells were observed in CEF, DF-1, Vero, and QT-35 cell lines. The infectivity and viral replication were highest in CEF, DF-1, Vero, and QT-35 cells. In contrast, the results suggested that MDCK cells are less permissive for AnHV-1 infection with negligible CPE and reduced viral replication. Heterologous cell culture systems other than chicken embryo fibroblasts to adapted live vaccine viruses will provide a system devoid of other avian infectious agents. Moreover, it can be used for the propagation and cultivation of AnHV-1 vaccine strain for developing cell culture-based vaccines with high titer and could be an economical alternative for the existing options.

Propagating material instabilities in planar architectured materials

Under tension low carbon steel exhibits inhomogeneous plastic deformation. This instability called Piobert-Lüders banding creates fronts of localized strain that propagate in the structure. To date, Lüders banding has been studied experimentally and numerically only in simple geometries like sheets, tubes and normalized fracture mechanics specimens. This paper focuses on architectured materials and specifically lattice structures which can be defined as a tessellation of unit-cells periodically distributed in space. This class of advanced materials draws new mechanical properties from its inner architecture.We investigate the effect of the architecture on the global behavior of the structure. Especially, how bands interact with the lattice and how to control initiation and propagation of localized strain using the architecture. An elastoplastic material model is used in order to simulate the Piobert-Lüders band formation and propagation. The model also considers a large deformation framework for elastoplasticity with periodic boundary conditions in order to represent the architectured material. Initiation and propagation of material instabilities depend on the geometry as well as its on the relative orientation with respect to the loading direction. Propagating and non-propagating behaviors are identified for the Piobert-Lüders bands and related to the different types of geometry. Material instabilities affect the mechanical behavior of the structure as far as they are governed by the architecture. These conclusions are compared to experimental results from tensile tests on laser-architectured specimens made of ARMCO steel.

The Multi-objective Optimization Design Approach for Carbon Fiber Hybrid Nanocomposites Containing NanoClay and NanoZnO Particles by Using OptiComp

This paper presents the multi-objective design optimization of Carbon Fiber-Reinforced Polymer hybrid nanocomposites by OptiComp. The use of nanoparticles not only improves the interface strength but also significantly improves stress and hence the propagation of strain in composite laminates, which ultimately improves the stiffness of the composite laminate. The OptiComp is the comprehensive generic procedure for design optimization of the composites. With the utilization of OptiComp, the discrete form Variable thickness approach (VTA) used in this study can discover the minimum laminate thickness, and for maximum stiffness in one step instead of two-step method. The Max stress theory and Tsai-Wu theory as constraints for the current study in optimization are performed using a direct value coding genetic algorithm. It is found that the CFRP nanocomposites up to 2 to 3 wt% range of nanoparticles can be designed for max. stiffness and min. weight.

Does classical immunity acquired by the subcontinent population become advantageous to manage COVID-19 due to the low rate of mortality?

The global pandemic due to the COVID-19 has severely affected the entire world risking human life and economy. Every possible attempt becomes inadequate in controlling the disease as the number rising each passing day. Indeed, a highly populated country like India has so far successful in mitigating the outbreak within the country. Meanwhile, the strategy based on a preliminary model of assumption with massive awareness program on social (physical) distancing, compulsory wearing of a mask and nationwide lockdown might have contributed immensely to controlling such an emergency. However, the influence of the immune-competent genetic architecture of the Indian racing population and comparatively a dominant young age group population cannot be ruled out completely. Moreover, a suitable environment for viral propagation and characteristics of viral strain are other such factors that simultaneously could add a real scientific justification. However, the current global scenario indicating the countries with higher median age are severely affected compared to the Indian and African subcontinent thereby survived an outbreak with a low mortality rate. At the same time, we never claimed for complete immunity for the COVID-19 depending on age or immunity. The increased incidence of positive cases might slowly also increase the death rate within India, but so far recorded low compared to other parts of the globe.

The role of pre-existing weak zones in the formation of the Himalaya and Tibetan plateau: 3-D thermomechanical modelling

SUMMARY The Tibetan crust is sliced by several east–west trending suture zones. The role of these suture zones in the evolution of the Himalayan range and Tibetan plateau remains unclear. Here we use 3-D thermomechanical simulations to investigate the role of pre-existing weak zones within the Asian Plate in the formation of orogen and plateau growth during continental collision. Our results show that partitioning of deformation along the convergent margin leads to scraping off of crustal material into an orogenic wedge above the margin and crustal thickening in the retro-continent, eventually forming a large orogenic plateau in front of the indenter. Pre-existing weak zone(s) within the retro-continent is reactivated at the early stage of convergence, and facilitates the northward propagation of strain and widening of the orogenic plateau. The northernmost weak zone sets the northern limit of the Tibetan plateau. Our models also show rheological weakening of the congested buoyant crust within the collisional zone drives wedge-type exhumation of deeply buried crust at the southern flank of the plateau, which may explain the formation of the Greater Himalayan Sequence.