Heterogeneity induced strain localization in block-in-matrix-soils subjected to uniaxial loading using real-time CT scanning

Block-in-matrix-soils(bimsoils)are geological mixtures that have distinct structures consisting of relatively strong rock blocks and weak matrix soils.It is still a challenge to evaluate the mechanical behaviors of bimsoils because of the heterogeneity,chaotic structure,and lithological variability.As a result,only very limited laboratory studies have been reported on the evolution of their internal deformation.In this study,the deformation evolution of bimsoils under uniaxial loading is investigated using real-time X-ray computed tomography(CT)and image correlation algorithm(with a rock block percentage(RBP)of 40%).Three parameters,i.e.heterogeneity coefficient(K),correlation coefficient(CC),and standard deviation(STD)of displacement fields,are proposed to quantify the heterogeneity of the motion of the rock blocks and the progressive deformation of the bimsoils.Experimental results show that the rock blocks in bimsoils are prone to forming clusters with increasing loading,and the sliding surface goes around only one side of a cluster.Based on the movement of the rock blocks recorded by STD and CC,the progressive deformation of the bimsoils is quantitatively divided into three stages:initialization of the rotation of rock blocks,formation of rock block clusters,and formation of a shear band by rock blocks with significant rotation.Moreover,the experimental results demonstrate that the meso-motion of rock blocks controls the macroscopic mechanical properties of the samples.

LIM1863 is useful to explore collective cancer cell migration,and the group of heterogeneous cells undergoing collective migration behaves like a supracellular unit

Collective cancer cell migration(CCCM)and epithelial-to-mesenchymal transition(EMT)play key roles in metastasis.This study reports that the colorectal carcinoma cell line LIM1863 is useful for the study of CCCM and EMT.Methods:Hematoxylin and eosin staining,scanning electron microscopy,transmission electron microscopy,and western blot analysis were performed.Results:LIM1863 automatically grew as spheroids in suspension and had important typical epithelial properties,including several layers of cells arranged around a central lumen,apical-basal polarity,and types of cell-cell junctions.Treatment with a combination of both TGF beta 1 and TNF alpha induced definite and distinct EMT,a spheroid changing phenotype to form a monolayer high-confluent patch without lumen,without polarity.Spontaneous CCCM occurred in spheroids.Flat EMT cells adhered to the base of a dish,exhibited persistent movement as a cluster of cells,and then shed,resulting in a cluster.All cells from one cluster undergoing CCCM died.Otherwise,all cells undergoing EMT disappeared and almost all cells located in the cell reservoir survived and proliferated.Conclusion:LIM1863 is an excellent cell line to study CCCM and EMT.The group of heterogeneous cells undergoing CCCM behaves like a supracellular unit.

Influence of layer orientation and interlayer bonding force on the mechanical behavior of shale under Brazilian test conditions

The mechanical behavior of inherently anisotropic shale rocks under Brazilian test conditions are investigated in this study based on experimental studies and numerical simulations. The effects of the weak lamination planes and interlayer bonding force of these layers on the failure strength and fracture patterns are studied systematically. Numerical simulations using particle flow code in two dimensions based on the discrete element method showed a good agreement with the experimental results in the failure strength and fracture patterns. The shale revealed strong anisotropic behavior with the failure strength perpendicular to the lamination plane greater than failure strength parallel to lamination plane. The failure strength of the different interlayer bonding force against the layer orientations changed significantly. Four types of fracture patterns were observed: curved fracture, broken-linear fracture, layeractivated fracture, and central-linear fracture. The observed fracture patterns are either or a combination of tensile and/or shear fractures. Increase in interlayer bonding strength decreased the quantity of micro cracks and this directly led to reduction in the anisotropic behavior. Overall the layer orientation and interlayer bonding force of the shale thus play a very important role in the anisotropic behavior of the shale.

Effects of Silk Fibroin Moisturizing Cream on Acetone/Ether-Induced Dry Skin Pruritus in Mice

Objectives: The morbidity of dry and itchy skin was high during a person’s lifetime and it had a significant negative impact. This study aimed to investigate the positive effect of silk fibroin moisturizing cream on dry skin pruritus induced by acetone/ether-water (AEW) method in mice. Method: We established a dry skin model in mice with AEW treatment, and the control group was treated with ultrapure water. The mice in AEW model group were locally administrated with silk fibroin moisturizing cream (SilkArmor)&reg;. The transepidermal water loss (TEWL), scratching behavior, condition of skin erythema, skin histology (by hematoxylin-eosin staining) and the results of electron microscopy were measured to evaluate the positive effect of SilkArmor on dry and itchy skin in mice. Results: The TEWL value, spontaneous scratching behavior and erythema score were significantly increased after AEW modeling compared with the control group. There was no significant difference in the TEWL value, scratching behavior and erythema score between the SilkArmor group and the control group (P > 0.05). Compared with the AEW group, the value of TEWL, scratching behavior and the erythema score of mice in the AEW + SilkArmor group were improved, with statistically significant differences (P < 0.05). Skin histopathology and electron microscopy also showed that SilkArmor had certain improvement and repairment on AEW-induced skin pathological changes. Conclusions: A dry skin model was successfully established in this experiment, showing that SilkArmor brought an obvious alleviation to AEW-induced dry and itchy skin in mice.

Experimental study on cracking behaviour of moulded gypsum containing two non-parallel overlapping flaws under uniaxial compression

Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence process in a brittle material with two non-parallel overlapping flaws using a high-speed camera. The coalescence tensile crack and tensile wing cracks were the first cracks to occur from the preexisting flaws. The initiation stresses of the primary cracks at the two tips of each flaw were simultaneous and decreased with reduced flaw inclination angle. The following types of coalescence cracks were identified between the flaws: primary tensile coalescence crack, tensile crack linkage, shear crack linkage, mixed tensile-shear crack, and indirect crack coalescence. Coalescence through tensile linkage occurred mostly at pre-peak stress. In contrast, coalescence through shear or mixed tensile-shear cracks occurred at higher stress. Overall, this study indicates that the geometry of preexisting flaws affect crack initiation and coalescence behaviour.

PCHD-Based Passivity Control of VSC-HVDC Connected Large Wind Farm

Concentrated integration of large scale wind power demands stronger robustness of VSC-HVDC transmission. Based on PCHD (Port Controled Hamiltonian with Dissipation) equation, the PCHD model of voltage source converter (VSC) in abc frame and d-q rotating frame are built and the strict passivity of VSC is proved. Desired energy function is constructed and used as Lyapunov function by assigning link matrix and damping matrix. Impact from VSC equivalent dc resistance is eliminated by additional damping matrix. The IDA-PB (Interconnection and Damping Assignment Passivity-based) controller is designed based on desired equilibrium point and state variable. With different operation conditions, VSC-HVDC and its control system are simulated by software PSCAD/EMTDC, the results show the proposed control strategy has good performance and strong robustness.

Classification of partial discharge severities of ceramic insulators based on texture analysis of UV pulses

Inspection of partial discharge before contamination flashover is of great importance for preventing exterior insulation accidents.In this study,a new method for identification of discharge severities is proposed.Specifically,a low‐cost ultraviolet(UV)sensor detection system was combined with time-frequency method,texture analysis and support vector machine(SVM)classifier to classify partial discharge severities for ceramic insulators.The visible images and the root‐mean‐square value of leakage currents detected simulta-neously are used to classify the UV signals into different discharge faults.The frequency and amplitude integration of UV pulses are minimum in corona discharge and larger in arc discharge.The images of UV signal spectrograms differ significantly at different discharge stages.The density and brightness of image textures are minimal in corona discharge and larger in arc discharge.Valid and reliable features selected by two texture feature extraction methods with SVM classifier have a reliable classification accuracy of 90.6%for ceramic insulators,and outperform a single time feature or other texture features.SVM outperforms k‐Nearest Neighbour,Naive Bayes and Decision Tree.Our new method with computational effectiveness and high practicality can solve the problem of high randomness and low accuracy of UV sensor detection.It can be further applied to the deterioration diagnosis of power facilities.

Simultaneous determination of eight bioactive bakkenolides of Petasites tatewakianus Kitam by HPLC–UV

A high-performance liquid chromatography coupled with variable wavelength detection(HPLC–UV)was developed to evaluate the quality of Petasites tatewakianus Kitam through a simultaneous determination of eight bakkenolides:bakkenolide-L,bakkenolide-D,bakkenolide-B,bakkenolide-Ⅰa,bakkenolide-Ⅶa,bakkenolide-Ⅳa,bakkenolide-Ⅲa and homofukinolide.With a C18 analytical column,the eight analytes were efficiently separated using tetrahydrofuran–acetonitrile–water as the mobile phase in a constant program.The limits of detection and limits of quantitation of the method ranged 0.42–2.56μg/mL and 1.22–8.40μg/mL,respectively.The intra-and inter-day precisions of the method were all less than 1.83%.All the recoveries for the spiked analytes ranged 97.8%–102.4%.There were statistically significant differences among the contents of the eight bakkenolides in different parts and origins of P.tatewakianus(Po0.01).The content of total bakkenolides in rhizome was higher than that in other parts of the plant.The content of total bakkenolides in rhizome from Baishan was higher than those in other localities.The result suggested that rhizome may be the most valuable part of P.tatewakianus,and P.tatewakianus from Baishan may be the best plant resource.Our results might serve as a sound foundation for further study and application of this plant.

Actin polymerization inhibition by targeting ARPC2 affects intestinal stem cell homeostasis

Background:The rapid turnover of the intestinal epithelium is driven by the proliferation and differentiation of intestinal stem cells(ISCs).The dynamics of the F-actin cytoskeleton are critical for maintaining intercellular force and the signal transduction network.However,it remains unclear how direct interference with actin polymerization impacts ISC homeostasis.This study aims to reveal the regulatory effects of the F-actin cytoskeleton on the homeostasis of intestinal epithelium,as well as the potential risks of benproperine(BPP)as an anti-tumor drug.Methods:Phalloidin fluorescence staining was utilized to test F-actin polymerization.Flow cytom-etry and IHC staining were employed to discriminate different types of intestinal epithelial cells.Cell proliferation was assessed through bromo-deoxyuridine(BrdU)and 5-ethynyl-2-deoxyuridine(EdU)incorporation assays.The proliferation and differentiation of intestinal stem cells were replicated in vitro through organoid culture.Epithelial migrationwas evaluated through BrdU pulse labeling and chasing in mice.Results:The F-actin content was observed to significantly increase as crypt cells migrated into the villus region.Additionally,actin polymerization in secretory cells,especially in Paneth cells(PCs),was much higher than that in neighboring ISCs.Treatment with the newly identified actin-related protein 2/3 complex subunit 2(ARPC2)inhibitor BPP led to a dose-dependent increase or inhibition of intestinal organoid growth in vitro and crypt cell proliferation in vivo.Compared with the vehicle group,BPP treatment decreased the expression of Lgr5 ISC feature genes in vivo and in organoid culture.Meanwhile,PC differentiation derived from ISCs and progenitors was decreased by inhibition of F-actin polymerization.Mechanistically,BPP-induced actin polymerization inhibition may activate the Yes1-associated transcriptional regulator pathway,which affects ISC proliferation and differentiation.Accordingly,BPP treatment affected intestinal epithelial cell migration in a dose-dependent manner.Conclusion:Our findings indicate that the regulation of cytoskeleton reorganization can affect ISC homeostasis.In addition,inhibiting ARPC2 with the Food and Drug Administration-approved drug BPP represents a novel approach to influencing the turnover of intestinal epithelial cells.