Compact Zone Research Articles

Microstructure evolution and high-temperature oxidation behavior of low-carbon MgO-C refractories with TiB2 addition

Combining the advantages of both containing-B compounds and containing-Ti compounds, a new TiB2 addition is proposed in MgO-C refractories. In this paper, the high-temperature oxidation behavior of low-carbon MgO-C refractories with TiB2 addition was investigated, especially the effect of microstructure and phase evolution on the high-temperature oxidation behavior was discussed. The results show that in the materials, TiB2 preferentially reacts with oxygen, forming TiCxN1-x, Mg3(BO3)2 and Mg2TiO4 ceramic phases, and catalyzing the decomposition of phenolic resin to form bamboo-like nanotubes and carbon nanospheres to bond aggregates and fill pores. Meanwhile, TiB2 also promotes the formation of regenerated MgO compact zone, hindering the diffusion of oxygen into the materials to improve the oxidation resistance. Compared with the blank control specimen and the specimen with B4C addition, the oxidation resistance increased by 243.4 % and 79.2 %, respectively.

Dynamic crushing responses of enhanced auxetic re-entrant honeycomb based on additive manufacturing

Recently, auxetic re-entrant honeycombs have gained a significant deal of attention due to their superior mechanical qualities. In this work, a star-enhanced auxetic re-entrant honeycomb (S-ARH) is proposed by combining a star-shaped re-entrant honeycomb (SRH) with an auxetic re-entrant honeycomb (ARH). Experimentally validated finite element models are used to investigate the deformation modes, horizontal shrinkage strains, and stress-response relationships of the S-ARH at various crushing velocities. The deformation modes of S-ARH are essentially identical to the ARH. The integration of star-shaped structures causes S-ARH to form a compact zone earlier but with a lower horizontal shrinkage capacity. Additionally, the plateau crushing stress σp and specific energy absorption of S-ARH are also calculated to illustrate the ability to absorb energy and the resistance to impact. A methodical equation for the dynamic compressive strength is derived based on the collapse mechanism of the S-ARH, and the finite element confirms the applicability of the derived equation. Finally, an evaluation is conducted to examine how various structural parameters influence the dynamic performance of S-ARH.

New compact micro-hole zone catheter enables women to achieve effective bladder emptying without flow-stops.

Clean intermittent self-catheterisation (CISC) with conventional eyelet catheters (CECs) is associated with urine flow-stops, which require the catheter to be repositioned so flow can resume. Flow-stops often occur because bladder mucosa is sucked into the eyelets. This investigation aimed to compare the bladder-emptying performance of the micro-hole zone catheter (MHZC) with the CEC. This was a multi-centre, randomised, open-label, controlled cross-over study with 82 women comparing the MHZC to the CEC. The endpoints relating to bladder-emptying performance included the residual volume at first flow-stop, the number of flow-stops and the proportion of successful treatment responses. The women's perception of the catheters was assessed as well as device discomfort. Catheterisations with MHZC significantly reduced the risk of flow-stops, with relative risk results showing a 2.74 times lower risk of flow-stops with a health professional-led catheterisation and a 2.52 times lower risk during self-catheterisation. There was no statistical difference in residual urine volume at first flow-stop between the two catheters. Catheterisations with the MHZC were significantly more likely to achieve zero flow-stops and a residual urine volume of <10 ml at first flow-stop. The women had a significantly more positive perception of the MHZC than the CEC in areas including handling, confidence, sensation and satisfaction. The MHZC enabled effective bladder emptying without catheters needing to be repositioned, supporting the women by simplifying the procedure and making them feel confident that their bladders were empty.

Sensitivity of Local Climate Zones and Urban Functional Zones to Multi-Scenario Surface Urban Heat Islands

Local climate zones (LCZs) and urban functional zones (UFZs) can intricately depict the multidimensional spatial elements of cities, offering a comprehensive perspective for understanding the surface urban heat island (SUHI) effect. In this study, we retrieved two types of land surface temperature (LST) data and constructed 12 SUHI scenarios over the Guangdong–Hong Kong–Macao Greater Bay Area Central region using six SUHI identification methods. It compared the SUHI sensitivity differences among different types of LCZ and UFZ to analyze the global and local sensitivity differences of influencing factors in the 12 SUHI scenarios by utilizing the spatial gradient boosting trees, geographically weighted regression, and the coefficient of variation model. Results showed the following: (1) The sensitivity of different LCZ and UFZ types to multi-scenario SUHI was significantly affected by differences in SUHI identification methods and non-urban references. (2) In the morning, the shading effect of building clusters reduced the surface urban heat island intensity (SUHII) of some built environment types (such as LCZ 1 (compact high-rise zone) to LCZ 5 (open midrise zone)). The SUHIIs of LCZ E (bare rock or paved zone) and LCZ 10 (industry zone) were 4.22 °C and 3.87 °C, respectively, and both are classified as highly sensitive to SUHI. (3) The sensitivity of SUHI influencing factors exhibited regional variability, with importance differences in the sensitivity of importance for factors such as the impervious surface ratio, elevation, average building height, vegetation coverage, and average building volume between LCZs and UFZs. Amongst the 12 SUHI scenarios, an average of 87.43% and 89.97% of areas in LCZs and UFZs, respectively, were found to have low spatial sensitivity types. Overall, this study helps urban planners and managers gain a more comprehensive understanding of the complexity of the SUHI effect in high-density cities, providing a scientific basis for future urban climate adaptability planning.

Characterization of Wear Resistance and Corrosion Resistance of Plasma Paste Borided Layers Produced on Pure Titanium.

Commercially pure titanium was plasma paste borided using various temperatures of the process. An increase in the boriding temperature resulted in an increase in the thickness of the borided layer. All the layers produced consisted of an outer compact TiB2 zone and an inner TiB zone in the form of whiskers penetrating into the substrate. The presence of hard titanium borides resulted in a significant increase in wear resistance compared to non-borided pure titanium. However, the thickness of the layer produced strongly influenced the wear behavior, in respect of the time required for complete destruction of the layer. Higher wear resistance was characteristic of the TiB2 layer due to its compact nature, whereas the specific morphology of TiB whiskers resulted in their lower wear resistance compared to the outer TiB2 layer. Plasma paste boriding of pure titanium also had an advantageous effect on corrosion resistance compared to non-borided pure titanium. Simultaneously, due to the higher thickness of TiB2 layer, the specimen borided at a higher temperature showed higher corrosion resistance.

Abstract We081: β1 integrins regulate cellular behavior and cardiomyocyte organization during ventricular wall formation

Introduction: Cardiomyocytes are surrounded by extracellular matrix (ECM) and interact with ECM via integrins. However, the mechanisms through which these cells organize themselves to establish the tissue architecture of trabeculae and the ventricular wall remain inadequately elucidated. Integrins are the primary cell surface receptors for adhesion to the ECM and mediate both inside-out and outside-in signal transduction pathways that control various cell functions, including proliferation, survival, migration, and gene expression. We found that the β1 integrin subunit (β1), encoded by Itgb1 , is highly expressed in all cardiac cell types. Hypothesis: β1 integrins play a crucial role in regulating cardiomyocyte behavior and organization during ventricular wall morphogenesis in mice. Methods and Results: We applied mRNA deep sequencing and immunostaining to determine the expression repertoires of α/β integrins and their ligands in the embryonic heart. β1 and some of its ECM ligands are asymmetrically distributed and enriched in the luminal side of cardiomyocytes, and fibronectin surrounds cardiomyocytes, creating a network for them. Itgb1 , which encodes the β1, was deleted via Nkx2.5 Cre/+ to generate myocardial-specific Itgb1 knockout (B1KO) mice. B1KO hearts lack a trabecular zone but a thicker compact zone. The levels of hyaluronic acid and versican, essential for trabecular initiation, were not significantly different between control and B1KO. Instead, fibronectin, a ligand of β1, was absent in the myocardium of B1KO hearts. Furthermore, B1KO cardiomyocytes display a random cellular orientation and fail to undergo perpendicular cell division, be organized properly, and establish the proper tissue architecture to form trabeculae. Mosaic clonal lineage tracing showed that Itgb1 regulates cardiomyocyte transmural migration and proliferation autonomously. Conclusions: β1 is asymmetrically localized in the cardiomyocytes, and some of its ECM ligands are enriched along the luminal side of the myocardium, and fibronectin surrounds cardiomyocytes. β1 integrins are required for cardiomyocytes to attach to the ECM network. This engagement provides structural support for cardiomyocytes to maintain shape, undergo perpendicular division, and establish cellular organization. Deletion of Itgb1 leads to loss of β1 and fibronectin and prevents cardiomyocytes from engaging the ECM network, resulting in failure to establish tissue architecture to form trabeculae.

β1 integrins regulate cellular behaviour and cardiomyocyte organization during ventricular wall formation.

The mechanisms regulating the cellular behaviour and cardiomyocyte organization during ventricular wall morphogenesis are poorly understood. Cardiomyocytes are surrounded by extracellular matrix (ECM) and interact with ECM via integrins. This study aims to determine whether and how β1 integrins regulate cardiomyocyte behaviour and organization during ventricular wall morphogenesis in the mouse. We applied mRNA deep sequencing and immunostaining to determine the expression repertoires of α/β integrins and their ligands in the embryonic heart. Integrin β1 subunit (β1) and some of its ECM ligands are asymmetrically distributed and enriched in the luminal side of cardiomyocytes, and fibronectin surrounds cardiomyocytes, creating a network for them. Itgb1, which encodes the β1, was deleted via Nkx2.5Cre/+ to generate myocardial-specific Itgb1 knockout (B1KO) mice. B1KO hearts display an absence of a trabecular zone but a thicker compact zone. The levels of hyaluronic acid and versican, essential for trabecular initiation, were not significantly different between control and B1KO. Instead, fibronectin, a ligand of β1, was absent in the myocardium of B1KO hearts. Furthermore, B1KO cardiomyocytes display a random cellular orientation and fail to undergo perpendicular cell division, be organized properly, and establish the proper tissue architecture to form trabeculae. Mosaic clonal lineage tracing showed that Itgb1 regulates cardiomyocyte transmural migration and proliferation autonomously. β1 is asymmetrically localized in the cardiomyocytes, and some of its ECM ligands are enriched along the luminal side of the myocardium, and fibronectin surrounds cardiomyocytes. β1 integrins are required for cardiomyocytes to attach to the ECM network. This engagement provides structural support for cardiomyocytes to maintain shape, undergo perpendicular division, and establish cellular organization. Deletion of Itgb1 leads to loss of β1 and fibronectin and prevents cardiomyocytes from engaging the ECM network, resulting in failure to establish tissue architecture to form trabeculae.

Dynamic simulation of immiscible displacement in fractured porous media

Investigating immiscible displacement in fractured porous media is essential for understanding the two-phase flow behavior within pores and fractures. In this work, a three-dimensional pore-fracture network model was developed to address the influence of fracture on flow patterns and to characterize fracture-matrix crossflow under different flow conditions. Sensitivity studies at a wide range of viscosity ratios and capillary numbers underscored that fracture significantly influenced flow patterns in the capillary fingering zone. Fracture with an advantageous path effect in the displacement direction caused a shift in the boundary of capillary fingering zone toward an increase in capillary numbers. As fracture aperture decreased and aspect ratio increased, there was a discernible decline in the crossflow rate. When fracture aperture equaled average matrix throat diameter, fracture lose advantageous path effect in compact displacement zone but retained it in viscous fingering and capillary fingering zones. Distinct matrix-fracture crossflow development processes were observed in different zones: in cross zone, following displacement breakthrough, the crossflow underwent a “long-term” process to attain stability. Viscous fingering zone promptly achieved stability post-breakthrough, whereas both capillary fingering and compact displacement zones had already reached a stable state before breakthrough. Nonlinear variations in breakthrough saturation were observed in the cross zone between compact displacement and capillary fingering zones. The control process of immiscible displacement exhibited variability under different flow conditions: compact displacement zone was characterized by matrix dominance, viscous fingering zone was jointly controlled by matrix displacement and fracture-matrix crossflow, and capillary fingering zone was primarily governed by fracture-matrix crossflow. These findings enhance scholarly comprehension of immiscible displacement behavior in fractured porous media.

Insights into the broadband emission of the TeV blazar Mrk 501 during the first X-ray polarization measurements

Aims. We present the first multiwavelength study of Mrk 501 that contains simultaneous very-high-energy (VHE) γ-ray observations and X-ray polarization measurements from the Imaging X-ray Polarimetry Explorer (IXPE). Methods. We used radio-to-VHE data from a multiwavelength campaign carried out between March 1, 2022, and July 19, 2022 (MJD 59639 to MJD 59779). The observations were performed by MAGIC, Fermi-LAT, NuSTAR, Swift (XRT and UVOT), and several other instruments that cover the optical and radio bands to complement the IXPE pointings. We characterized the dynamics of the broadband emission around the X-ray polarization measurements through its multiband fractional variability and correlations, and compared changes observed in the polarization degree to changes seen in the broadband emission using a multi-zone leptonic scenario. Results. During the IXPE pointings, the VHE state is close to the average behavior, with a 0.2–1 TeV flux of 20%–50% of the emission of the Crab Nebula. Additionally, it shows low variability and a hint of correlation between VHE γ-rays and X-rays. Despite the average VHE activity, an extreme X-ray behavior is measured for the first two IXPE pointings, taken in March 2022 (MJD 59646 to 59648 and MJD 59665 to 59667), with a synchrotron peak frequency &gt; 1 keV. For the third IXPE pointing, in July 2022 (MJD 59769 to 59772), the synchrotron peak shifts toward lower energies and the optical/X-ray polarization degrees drop. All three IXPE epochs show an atypically low Compton dominance in the γ-rays. The X-ray polarization is systematically higher than at lower energies, suggesting an energy stratification of the jet. While during the IXPE epochs the polarization angles in the X-ray, optical, and radio bands align well, we find a clear discrepancy in the optical and radio polarization angles in the middle of the campaign. Such results further support the hypothesis of an energy-stratified jet. We modeled broadband spectra taken simultaneous to the IXPE pointings, assuming a compact zone that dominates in the X-rays and the VHE band, and an extended zone stretching farther downstream in the jet that dominates the emission at lower energies. NuSTAR data allow us to precisely constrain the synchrotron peak and therefore the underlying electron distribution. The change between the different states observed in the three IXPE pointings can be explained by a change in the magnetization and/or the emission region size, which directly connects the shift in the synchrotron peak to lower energies with the drop in the polarization degree.

Layered structure of sialoliths compared with tonsilloliths and antroliths.

The aim of this study was to perform a comparative analysis of the ultrastructural and chemical composition of sialoliths, tonsilloliths, and antroliths and to describe their growth pattern. We obtained 19 specimens from 18 patients and classified the specimens into three groups: sialolith (A), tonsillolith (B), and antrolith (C). The peripheral, middle, and core regions of the specimens were examined in detail by histology, micro-computed tomography (micro- CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and transmission electron microscopy (TEM). In the micro-CT, group A showed alternating radiodense and radiolucent layers, while group B had a homogeneous structure. Group C specimens revealed a compact homogeneous structure. Histopathologically, group A showed a laminated, teardrop-shaped, globular structure. Group B demonstrated degrees of immature calcification of organic and inorganic materials. In group C, the lesion was not encapsulated and showed a homogeneous lamellar bone structure. SEM revealed that group A showed distinct three layers: a peripheral multilayer zone, intermediate compact zone, and the central nidus area; groups B and C did not show these layers. The main elemental components of sialoliths were O, C, Ca, N, Cu, P, Zn, Si, Zr, F, Na, and Mg. In group B, a small amount of Fe was found in the peripheral region. Group C had a shorter component list: Ca, C, O, P, F, N, Si, Na, and Mg. TEM analysis of group A showed globular structures undergoing intra-vesicular calcification. In group B, bacteria were present in the middle layer. In the outer layer of the group C antrolith, an osteoblastic rimming was observed. Sialoliths had distinct three layers: a peripheral multilayer zone, an intermediate compact zone and the central nidus area, while the tonsillolith and antrolith specimens lacked distinct layers and a core.

Behavioral studies on sorptivity of the concrete blended with nano silica

This study compares the sorptivity of quaternary blended concrete with that of control concrete by utilizing several SCMs, including fly ash (FA), nano silica (NS), and metakaolin (MK). Owing to its compact structural and improved particle refinement, the quaternary blended concrete outperforms the control concrete in terms of water resistance. The increased performance was due to the addition of Supplementary Cementitious Materials (SCMs), which led to a dense and uniform microstructure, and also due to the compact interfacial transition zone. The addition of these SCMs, like flyash, decreases emissions of greenhouse gases and also solves the problem of disposal.

Experimental Study on Post-Grouting Pile Vertical Bearing Performance Considering Different Grouting Methods and Parameters in Cohesive Soil

The selection of grouting methods and parameters significantly affects the improvement in the pile-bearing capacity of cast-in-place bored piles. This study proposes a comprehensive set of test methods for constructing model piles, performing grouting at the pile tip and pile side. A series of single-pile grouting and static load tests were conducted using these test methods. The results reveal that pile-side grouting is more effective in controlling pile settlement compared to tip grouting. Furthermore, tip-side-combined grouting exhibits superior reinforcement effects compared to the other two grouting methods. After grouting, a grout bubble is formed at the outlet, consisting of a compact diffusion zone internally and a split diffusion zone externally. Additionally, a vertical diffusion of grout occurs along the pile body, establishing a lateral friction resistance enhancement region. Within this region, the lateral friction resistance of the pile shows a negative correlation with the distance from the grouting outlet. The test results emphasize the significance of grouting volume and its impact on the bearing capacity, settlement control, lateral friction resistance, and grout bubble size in grouted piles, while the influence of variation in grouting pressure in a small range on bearing characteristics is not significantly apparent.

Effects of the combination of NH4H2PO4 and KH2PO4 on the interfacial bond between magnesium phosphate cement and steel fiber

In this paper, a double-side pullout testing method was used to characterize the bond strength and pullout energy of steel fiber in magnesium phosphate cement (MPC). The effects of phosphates on flowability, setting time, hydration heat, and phase composition of MPC were evaluated as well. The results indicate that ammonium dihydrogen phosphate (ADP) and potassium dihydrogen phosphate (PDP) show significant effects on the bond properties between MPC and steel fiber. Magnesium ammonium phosphate cement (MAPC) can generate ammonia during hydration, which is easy to form pores and voids in the interfacial zone. However, the calculated total volume shrinkage produced by the hydration of MAPC is greater than that of magnesium potassium phosphate cement (MPPC), which is conducive to greater friction at the interface. There is no gas generated during the hydration of MPPC, but the elastic modulus of K-struvite is lower than that of struvite. The combined use of ADP and PDP is conducive to reducing the porosity and increasing the hardness of the interface zone and improving the bond properties of MPC and steel fibers. The hydration products of MPC paste around the steel fiber form a highly compact interfacial zone with few defects, leading to mechanical interlock and strong friction. Moreover, the etching of the surface of mild steel fiber in MPC and penetration of soluble phosphates promote the interfacial bonds.

Preoperative planning of compact zone trajectory is necessary in treating osteoporotic vertebral compression fracture with endplate involvement: A prospective randomized controlled study.

This prospective randomized controlled study compares the clinical and radiological outcomes between reduction methods with or without compact trabecular bone during percutaneous kyphoplasty in osteoporotic vertebral fractures. The cohort of 100 patients who underwent percutaneous kyphoplasty was randomly divided into groups A (guide pin and balloon introduced directly into fracture site) and B (guide pin and balloon inserted away fracture site). The surgery duration, clinical and radiological outcomes postoperatively and at follow-up, and complications of cement leakage and adjacent fracture were recorded. Patients were followed up for an average of 20.18 months. The clinical outcomes were assessed using the Oswestry disability index and visual analogue scale. The 2 groups had similar patient demographics, surgery times, and volume of cement injected. The method using elevation of the collapsed endplate indirectly had no significant influence on radiological outcomes but significantly decreased the occurrence of intradiscal cement leakage and improved 1- and 12-month postoperative functional outcomes. Elevating and reinforcing the collapsed endplate rather than just filling the defect during percutaneous kyphoplasty is safe and effective. This technique decreased pain and improved function with lower rates of further collapse of the osteoporotic vertebrae compared to defect-filling alone.

The effects of particle sizes of expanded perlite on the mechanical properties and chloride penetration resistance of ECCs

This study presents the development of engineered cementitious composites (ECCs) incorporating expanded perlite particles (EPPs) with varying sizes, namely 150 mesh, 50–70 mesh, and 5–15 mesh, as well as an equivalent combination of these three sizes. The primary focus of the investigation was to evaluate the microstructures at different ages, mechanical properties, and chloride penetration resistance of ECCs incorporating EPPs. The results showed the presence of a compact interfacial transition zone (ITZ) between the matrix and EPPs, attributable to the internal curing effect. The incorporation of EPPs effectively mitigated fiber damage during fiber-matrix separation, thereby preventing premature fiber rupture. Specifically, the inclusion of 150 mesh EPP demonstrated improved mechanical properties compared to the control group. Furthermore, the addition of 5–15 mesh or mixed EPP enhanced the chloride penetration resistance of ECC, while contrasting results were observed for 150 mesh and 50–70 mesh EPPs. Additionally, this study explored the use of 150 mesh recycled rubber (RR) as an additional defect. ECCs with simultaneous incorporation of RR and EPPs (at a 2% content) exhibited excellent ductility, with an overall tensile strain ranging from 4.3% to 4.7%. The results for the combined addition of RR and EPPs aligned with those observed for the singular addition of EPPs in terms of chloride penetration resistance.

Spatial Association Rules and Thermal Environment Differentiation Evaluation of Local Climate Zone and Urban Functional Zone

Urban heat islands (UHIs) caused by urbanization have become a major issue affecting the sustainable development of the ecological environment. The distribution of UHIs is mainly affected by the reflection and transmission of heat radiation caused by differences in urban spaces, and the anthropogenic heat emissions caused by social activities. At present, the research on the urban thermal environment involves two spatial classification systems: local climate zone (LCZ), based on urban morphology and spatial patterns; and urban functional zone (UFZ), based on socio-economic activities. It is not clear whether there are association rules between these two systems in different cities. Against this background, this study explores the association rules between the UFZ and LCZ classification systems using the selected Chinese cities in different regions as typical examples. Our results confirm that there are common association rules from UFZ to LCZ, as the form of buildings is greatly influenced by the types of functional areas in urban construction. Specifically, the medical zone corresponds to the compact mid-rise zone (LCZ2); the business service area and the office area also correspond to the compact zone (LCZ1-LCZ3); and the industrial area corresponds to the compact low-rise zone (LCZ3). These functional zones have the same association rules in different cities. The cross-regional mining of the relationship between different urban functional systems will help to coordinate different planning departments and carry out the integration of multiple spatial plans. Furthermore, we found that LCZ has a better differentiation effect on the surface temperature through our comparison research, which makes it more suitable as a reference for research on the thermal environment and the heat island effect.

Integrated composite wall with geopolymer permanent insulation formwork: Interface bonding behavior and mechanism

Traditional external insulation engineering and formwork engineering in buildings are unable to meet the development needs of the construction industry under the current situation due to their complex construction processes, high environmental pollution, and insulation layers is prone to fire, peeling, and other diseases. Therefore, improving the technology of building external insulation engineering and formwork engineering scientifically and economically has become an urgent practical problem to be solved. This study developed an integrated composite wall with geopolymer insulation formwork based on alkali activation technology. The interface bonding performance between alkali-activated mortar (AAM) and building insulation materials (BIM), as well as between AAM and the post-cast normal concrete (NC) were examined by push-out test and single shear test, respectively. Among them, BIM includesd alkali-activated insulation materials (AAI) and traditional extruded polystyrene foam (XPS). Studied the enhancement effect and mechanism of interface treatment methods on two types of interfaces. The simplified models were proposed for the shear strength of AAM-NC interfaces with grooved treatment and crushed stone studs. The results showed that the interfacial bond strength of AAM-AAI was better than that of AAM-XPS, which was due to the more compact interface transition zone of AAM-AAI. The grooved treatment had a positive improvement effect on the shear strength of AAM-AAI and AAM-NC interfaces, increasing by 16.59%∼167.32% and 21.03%∼42.06%, respectively. Adding crushed stone studs and installing connectors can improve the bonding performance of AAM-NC interface by 19.63%∼42.99%. In addition, the proposed simplified models have high consistency between the predicted results and test results, which can provide good reference value for engineering design.

Plastic deformation mechanism and defect patterning under nanoindentation in medium entropy alloy CoCrNi

In this work, molecular dynamics simulations are employed to study the mechanical response and plastic deformation evolution of single-crystal medium entropy alloy (MEA) CoCrNi under nanoindentation. The effects of lattice distortion (LD) and chemical short-range order (CSRO) on plasticity initiation and defect evolution including the patterning of dislocations, planar faults and prismatic dislocation loops (PDLs) are discussed with respect to anisotropy. The results show that CSRO increases Young’s modulus and critical nucleation stress of Shockley partial (SP), while LD and thermal vibration have the opposite effect. In MEAs, a preference of SP nucleation at CoCr clusters is observed, and the SP bundles develop into a compact plastic zone with dense dislocation networks due to frequent dislocation interactions and large slip resistance by LD and CSRO. Twin boundaries (TBs) and geometrically necessary dislocations (GNDs) play the dominant role in the accommodation of local plasticity, while the propagation of PDLs, dependent on the slip propensity of loading orientation and the degree of slip resistance, assist in the relief of local stress. Once the PDL nucleation is suppressed, dislocation pileup is triggered by dense dislocation networks with limited dislocation propagation tendency, leading to a higher strength of the material. The above results elaborate the relation between local plasticity and defect patterning, which sheds light on the design of MPEAs with heterogeneous deformation behavior.

FU Orionis disk outburst: Evidence for a gravitational instability scenario triggered in a magnetically dead zone

Context. FUors outbursts are a crucial stage of accretion in young stars. However, a complete mechanism at the origin of the outburst still remains missing. Aims. We aim to constrain the instability mechanism in the star FU Orionis itself by directly probing the size and evolution in time of the outburst region with near-infrared (NIR) interferometry, and to confront it with physical models of this region. Methods. As the prototype of the FUors class of objects, FU Orionis has been a regular target of NIR interferometry. In this paper, we analyze more than 20 years of NIR interferometric observations to perform a temporal monitoring of the region of the outburst, and compare it to the spatial structure deduced from 1D magneto-hydrodynamic (MHD) simulations. Results. We measure from the interferometric observations that the size variation of the outburst region is compatible with a constant or slightly decreasing size over time: -0.56-0.36+0.14 AU/100 yr and -0.30-0.19+0.19 AU/100 yr in the H and K bands, respectively. The temporal variation and the mean size probed by NIR interferometry are consistently reproduced by our 1D MHD simulations. We find that the most compatible scenario is a model of an outburst occurring in a magnetically layered disk, where a magneto-rotational instability (MRI) is triggered by a gravitational instability (GI) at the outer edge of a dead zone. The scenario of a pure thermal instability (TI) fails to reproduce our interferometric sizes because it can only be sustained in a very compact zone of the disk &lt;0.1 AU. The comparison between the data and the MRI-GI models favors MHD parameters of αMRI = 10−2, TMRI = 800 K, and Σcrit = 10 g cm−2, with more work needed in terms of observations and modeling in order to improve the precision of these values. Locally, in the very inner part of the disk, TI can be triggered in addition to MRI-GI, which qualitatively better matches our observation but is not strongly constrained by the currently available data. The scenario of MRI-GI could be compatible with an external perturbation that enhances the GI, such as tidal interaction with a stellar companion, or a planet at the outer edge of the dead zone. Conclusions. We favor a layered-disk model driven by MRI turbulence in order to explain the spatial structure and temporal evolution of the outburst region on FU Orionis. Understanding this phase will provide a crucial link between the early phase of disk evolution and the process of planet formation in the first inner astronomical units.

Identification of biological components for sialolith formation organized in circular multi-layers

According to the previous studies of sialolithiasis reported so far, this study is aimed to identify the biological components of sialolith, which show different ultrastructures and chemical compositions from other stones, cholelith and urolith. Twenty-two specimens obtained from 20 patients were examined histologically, and analyzed with micro-CT, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). All sialoliths (n = 22) observed in this study showed a central nidus, which was filled with organoid matrix admixed with exosome vesicles, loose calcium apatite crystals, and many bacteria. The micro-CT and SEM observation clearly defined a single or multiple central nidus(es) encircled by highly calcified compact zone. The circular compact zone showed a band-like calcification, about 1–3 mm in thickness, and usually located between the central nidus and the peripheral multilayer zone. But some sialoliths (n = 5) showed severe erosion of compact zone by expanding multilayered zone depending on the level of calcification and inflammation in sialolith. By observing TEM images, many exosome vesicles and degraded cytoplasmic organelles were found in the central nidus, and some epithelial cells were also found in the calcified matrix of peripheral multilayer zone. Particularly, EDS analysis indicated the highest Ca/P ratio in the intermediate compact zone (1.77), and followed by the central nidus area (1.39) and the peripheral multilayer zone (0.87). Taken together, these data suggest that the central nidus containing many inflammatory exosomes and degraded cytoplasmic organelles has a potential to induce a band-like calcification of compact zone, and followed by the additional multilayer deposition of exfoliated salivary epithelial cells as well as salivary materials. Thereby, the calcium apatite-based sialolith is gradually growing in its volume size, and eventually obstructs the salivary flow and provides a site for the bacterial infection.