Soy polysaccharide maintains colonic homeostasis to protect from dextran sulphate sodium-induced colitis by modulating gut microbiota and intestinal epithelial regeneration

Soy polysaccharide(SP)has been reported to possess the properties of modulating gut microbiome diversity.Here,we aimed to explore the protective effects of SP against dextran sulphate sodium(DSS)-induced colitis.Pre-treatment with SP at a dosage of 400 mg/kg·day alleviated colitis symptoms,preventing the weight loss and colon shorten.SP suppressed DSS-induced inflammatory response and enhanced M1 to M2 macrophage polarization.Further investigation showed that SP significantly promoted the regeneration of crypt and the expansion of goblet cell production.In addition,bacterial 16S rRNA sequencing analysis showed that SP modulated the composition of fecal microbiota,including selectively increasing Lactobacillus relative abundance.Notably,SP treatment enriched the production of Lactobacillus-derived lactic acid,which was sensed by its specific G-protein-coupled receptor 81(Gpr81)/Wnt3/β-catenin signaling,and promoted the regeneration of intestinal stem cells.Fecal microbiome transplantation demonstrated that intestinal flora partially contributed to the beneficial effects of SP on preventing against colitis.In conclusion,SP exhibited the protective effects against colitis,which could be partly associated with modulating the composition of gut microbiota and enrichment of lactic acid.This study suggests that SP has potential to be developed as nutritional intervention to prevent colitis.

Quasi-static simulation of droplet morphologies using a smoothed particle hydrodynamics multiphase model

Numerical simulation of the morphology of a droplet deposited on a solid surface requires an efficient description of the three-phase contact line. In this study, a simple method of implementing the contact angle is proposed, combined with a robust smoothed particle hydrodynamics multiphase algorithm (Zhang 2015). The first step of the method is the creation of the virtual liquid-gas interface across the solid surface by means of dummy particles, thus the calculated surface tension near the triple point serves to automatically modulate the dynarnic contact line towards the equilibrium state. We simulate the evolution process of initially square liquid lumps on fiat and curved surfaces. The predictions of droplet profiles are in good agreement with the analytical solutions provided that the macroscopic contact angle is accurately implemented. Compared to the normal correction method, the present method is straightforward without the need to manually alter the normal vectors. This study presents a robust algorithm capable of capturing the physics of the static welling. It may hold great potentials in bio-inspired superhydrophobic surfaces, oil displacement, microfluidics, ore floatation, etc.

Enhanced Photocatalytic Activity of Nanoparticle-Aggregated Ag–AgX(X=Cl, Br)@TiO_2 Microspheres Under Visible Light

Ag–AgX(X = Cl, Br)@TiO_2 nanoparticle-aggregated spheres with different mass ratio of R = TiO2/Ag(X) from 35:1 to 5:1 were synthesized by a facile sol–gel technique with post-photoreduction. The photocatalytic activities of both Ag–Ag Cl@TiO_2 and Ag–Ag Br@TiO_2 under visible light are effectively improved by ~3 times relative to TiO_2 NPAS under the simulated sunlight for the decomposition of methyl orange(MO). Ag–AgBr@TiO_2 showed 30% improvement and less stable in photocatalytic activity than that of AgCl@TiO_2. The role of Ag and Ag X nanoparticles on the surface of Ag–Ag X(X = Cl,Br)@TiO_2 was discussed. Ag on these samples not onlycan efficiently harvest visible light especially for Ag Cl, but also efficiently separate excited electrons and holes via the fast electron transfer from Ag X(X = Cl, Br) to metal Ag nanoparticles and then to TiO_2-aggregated spheres on the surface of heterostructure. On the basis of their efficient and stable photocatalytic activities under visible-light irradiation, these photocatalysts could be widely used for degradation of organic pollutants in aqueous solution.

Stability and local bifurcation of parameter-excited vibration of pipes conveying pulsating fluid under thermal loading

The parametric excited vibration of a pipe under thermal loading may occur because the fluid is often transported heatedly. The effects of thermal loading on the pipe stability and local bifurcations have rarely been studied. The stability and the local bifurcations of the lateral parametric resonance of the pipe induced by the pulsating fluid velocity and the thermal loading are studied. A mathematical model for a simply supported pipe is developed according to the Hamilton principle. Two partial differential equations describing the lateral and longitudinal vibration are obtained. The singularity theory is utilized to anMyze the stability and the bifurcation of the system solutions. The transition sets and the bifurcation diagrams are obtained both in the unfolding parameter space and the physical parameter space, which can reveal the relationship between the thermal field parameter and the dynamic behaviors of the pipe. The frequency response and the relationship between the critical thermal rate and the pulsating fluid velocity are obtained. The numerical results demonstrate the accuracy of the single-mode expansion of the solution and the stability and local bifurcation analyses. It also confirms the existence of the chaos. The presented work can provide valuable information for the design of the pipeline and the controllers to prevent the structural instability.

Thoracic endovascular aortic repair with left subclavian artery reconstruction for blunt traumatic aortic injury in elderly patients

Introduction:Blunt thoracic aortic injury(BTAI)is rare in elderly patients.As the population ages and life expectancy increases,the frequency of this injury will increase,while the treatment and outcomes remain unclear.Methods:We retrospectively analyzed the collected data of patients>60 years old with BTAI to investigate the mechanism of trauma;time interval from injury to diagnosis;type and timing of surgical intervention;aortic arch pattern;choice of left subclavian artery reconstruction;endograft to treat BTAI;length of the endovascular procedure;endoleaks;complications including stroke,paraplegia,and renal failure;length of hospital stay(LOS)and intensive care unit stay(L.ICUS);and 30-day mortality.Results:Five elderly trauma patients were found to have BTAI.Four(80%)were males,the cohort mean age was68 years,the major mechanism of trauma was fall injury,and the associated injury was thoracic trauma.All patients were transferred to our hospital,and emergency computed tomography angiography showed BTAI in each patient.The average time interval from injury to diagnosis was 2.7 days.Two patients suddenly showed signs of instability in their vital signs and underwent immediate endovascular repair,while 3 patients underwent delayed endovascular repair.The injury site was located in the aortic isthmus just distal to the origin of the left subclavian artery;the aortic arch pattern was II(80.0%)in 4 cases and III in 1 case(20.0%).The choice of left subclavian artery reconstruction included chimney,double chimney,prefenestration,and chimney combined with in situ fenestration.Endografts to treat BTAI included the Ankura(Lifetech Scientific,Shenzhen,China)and the C-TAG(W.L.Gore&Associates,Flagstaff,AZ USA).The length of the endovascular procedure was 75.4 min;there were no endoleaks and no complications including stroke,paraplegia,or renal failure.The average LOS was25 days,and the average L.ICUS of 2 patients was 15 days,with no 30-day mortality.Conclusion:Elderly patients with fall injury should promptly exclude BTAI.Thoracic endovascular aortic repair(TEVAR)with a left subclavian artery reconstruction technique provided good results without procedure-related or neurological complications.Because of the low incidence of this type of injury,we are unable to provide any evidence to guide the treatment option for this life-threatening condition.

Size-dependent thermoelasticity of a finite bi-layered nanoscale plate based on nonlocal dual-phase-lag heat conduction and Eringen's nonlocal elasticity

The size effects on heat conduction and elastic deformation are becoming significant along with the miniaturization of the device and wide application of ultrafast lasers.In this work,to better describe the transient responses of nanostructures,a size-dependent thermoelastic model is established based on nonlocal dual-phase-lag(N-DPL)heat conduction and Eringen's nonlocal elasticity,which is applied to the one-dimensional analysis of a finite bi-layered nanoscale plate under a sudden thermal shock.In the numerical part,a semi-analytical solution is obtained by using the Laplace transform method,upon which the effects of size-dependent characteristic lengths and material properties of each layer on the transient responses are discussed systematically.The results show that the introduction of the elastic nonlocal parameter of Medium 1 reduces the displacement and compressive stress,while the thermal nonlocal parameter of Medium 1 increases the deformation and compressive stress.These findings may be beneficial to the design of nano-sized and multi-layered devices.

Nonlinear dynamic analysis of dielectric elastomer membrane with electrostriction

The dielectric elastomer(DE)is an important intelligent soft material widely used in soft actuators,and the dynamic response of the DE is highly nonlinear due to the material properties.In the DE,electrostriction denotes the deformation-dependent permittivity.In the present study,we formulate the nonlinear dynamic governing equations of the DE membrane considering the electrostriction effect.The free vibration and parametric excitation of the DE membrane with different geometric sizes are calculated.The free vibration bifurcations induced by the initial location and the voltage are both discussed according to an energy-based approach.The amplitude-frequency characteristics and bifurcation diagrams of parametric excitation are also given.The results show that electrostriction decreases the free vibration amplitude and increases the frequency,but it has less influence on the parametric excitation oscillation frequency and decreases the parametric excitation amplitude except when the membrane resonates.The initial location and the applied voltage can induce the snap-through instability of the free vibration.A large geometric size will lead to a much lower resonance frequency.The resonance amplitudes increase while the resonance frequencies decrease with the increase in the applied voltage.The critical voltage of snap-through instability for the parametric excitation is larger than that for the free vibration one.

Peeling of Magneto-responsive Beams with Large Deformation Mediated by the Parallel Magnetic Field

Elasto-capillarity phenomena are prevalent in various industrial fields such as mechanical engineering,material science,aerospace,soft robotics,and biomedicine.In this study,two typical peeling processes of slender beams driven by the parallel magnetic field are investigated based on experimental and theoretical analysis.The first is the adhesion of two parallel beams,and the second is the self-folding of a long beam.In these two cases,the energy variation method on the elastica is used,and then,the governing equations and transversality boundary conditions are derived.It is shown that the analytical solutions are in excellent agreement with the experimental data.The effects of magnetic induction intensity,distance,and surface tension on the deflection curve and peeling length of the elastica are fully discussed.The results are instrumental in accurately regulating elasto-capillarity in structures and provide insights for the engineering design of programmable microstructures on surfaces,microsensors,and bionic robots.

Exploring the effects of mask wearing on outdoor thermal comfort at different walking speeds—A thermal manikin-based experiment

Face masks’wearing for a long duration brings thermal discomfort,especially in hot climate cities.The face masks’thermal insulation and its effect on outdoor thermal comfort have been rarely investigated.In this study,five types of face masks and their thermal insulations have been tested by using a thermal manikin in the climate chamber.Experimental results are assessed by using physiological equivalent temperature(PET)and standard effective temperature(SET^(*))for thermal comfort with masks at three walking speeds both in summer and winter.Slight differences in thermal insulation are observed among the different masks,the values of PET and SET^(*)rise with increasing mask thermal insulation,and they are generally higher in summer than in winter.Moreover,the variation of SET*is more obvious than PET with same masks at different walking speeds.And the differences of SET^(*)with and without masks appear to rise significantly for fast walking.Results further indicate that the individuals’physical discomfort caused by wearing masks cannot simply be assumed as an additional effect of the clothing thermal insulation.The findings enrich the clothing thermal insulation database,explore the differences in thermal indices if the face mask is used,and provide advice on heat mitigation with masks outdoors.

Influencing assessment of different heating modes on thermal comfort in electric vehicle cabin

Electric vehicle(EV)is more environmental-friendly than gasoline vehicle because the main power is not petrol.For the heating system,the waste heat generated by engines is recycled to heat the cabin of gasoline ones,while the EV need extra electric energy consumption for heating the cabin which decreases the driving range.Personal comfort system(PCS)has been reported that it is an alternative technique to improve occupant thermal comfort and indirectly save building heating energy.This study aims to investigate the occupants’thermal sensation under four heating modes in the EV cabin in winter,including no heating,only PCS,only air conditioning,and both air conditioning and PCS.The field survey is conducted in a parked EV with 12 subjects.Three thermal comfort indexes(PMV,SET^(*),and operative temperature Top)are used and assessed for their applicability in the thermal environment of the EV.Results show that the thermal environment in the cabin is non-uniform and dynamic with the air conditioning mode,while the PCS mode just slightly affects the temperature differences inside.Meanwhile,the subjects’thermal sensations cannot maintain neutral or warmer under the PCS mode only.The results of PMV are lower than the subjects’actual thermal sensation votes(TSV),while the results of SET^(*)and Top show significant linear relationships with the TSV for the correlation coefficients above 0.80.Compare to the air conditioning mode,the neutral SET^(*)and neutral Top are decreased by 2.7℃ and 1.6℃ under the mode with PCS and air conditioning,respectively.The findings indicate that PCS not only has a positive effect on improving the cabin environment and occupant’s thermal sensation but also has the potential to lower the setting temperature of air conditioner of EVs in winter.

Elastic wave propagation and scattering in prestressed porous rocks

Poro-acoustoelastic theory has made a great progress in both theoretical and experimental aspects,but with no publications on the joint research from theoretical analyses,experimental measurements,and numerical validations.Several key issues challenge the joint research with comparisons of experimental and numerical results,such as digital imaging of heterogeneous poroelastic properties,estimation of acoustoelastic constants,numerical dispersion at high frequencies and strong heterogeneities,elastic nonlinearity due to compliant pores,and contamination by boundary reflections.Conventional poroacoustoelastic theory,valid for the linear elastic deformation of rock grains and stiff pores,is modified by incorporating a dualporosity model to account for elastic nonlinearity due to compliant pores subject to high-magnitude loading stresses.A modified finite-element method is employed to simulate the subtle effect of microstructures on wave propagation in prestressed digital cores.We measure the heterogeneity of samples by extracting the autocorrelation length of digital cores for a rough estimation of scattering intensity.We conductexperimental measurements with a fluid-saturated sandstone sample under a constant confining pressure of 65 MPa and increasing pore pressures from 5 to 60 MPa.Numerical simulations for ultrasound propagation in the prestressed fluid-saturated digital core of the sample are followed based on the proposed poro-acoustoelastic model with compliant pores.The results demonstrate a general agreement between experimental and numerical waveforms for different stresses,validating the performance of the presented modeling scheme.The excellent agreement between experimental and numerical coda quality factors demonstrates the applicability for the numerical investigation of the stress-associated scattering attenuation in prestressed porous rocks.

Mechanisms Underlying the Biological WetAdhesion:Coupled Effects of Interstitial Liquid and Contact Geometry

Wet adhesion is widely adopted in biological adhesion systems in nature,and it is beneficial to design new materials with desired properties based on the underlying physics of wet adhesion.The aim of this work is to develop a design criterion to regulate the wet adhesion.The effects of different contact shapes(flat and sphere)and morphologies of the substrate(smooth,microstructure and nanostructure)on the adhesion force are investigated.Combining with the theoretical models,the dominated factors in the separation process and isolating the viscous contributions from the capillary interactions are evaluated.The results demonstrate that the adhesion mechanisms depend significantly on the capillary numbers of the interstitial liquid and the contact geometry,and the ratio of capillary force to viscous force is a key to regulate the wet adhesion mechanism.These findings can not only explain some phenomena of wet adhesion to organisms,but also provide some inspirations to design new adhesion technology for robotic fingers that can grasp objects in wet environments.

A Bioinspired Adhesive Sucker with Both Suction and Adhesion Mechanisms for Three-Dimensional Surfaces

There are significant advantages to investigate underwater attachments,which would be valuable in providing inspirations and design strategies for multi-functional surfaces and underwater robots.Here,an abalone-inspired sucker integrating an elastic body and a membrane structure is proposed and fabricated filled with rigid quartz particles to adjust the backing stiffness of the contact like abalone.The membrane is used to conform and contact surfaces well,the center area of which can be pulled in exposed to a negative pressure differential,to create a suction cavity.The pulling experiments indicate that the sucker can adhere to three-dimensional surfaces with both suction and adhesion mechanisms in both dry and liquid environments.The switching between soft/hard contact states leads to the change of adhesive strength over 30 times.Furthermore,we provide theoretical analysis on how the sucker work well in both dry and liquid environments.Finally,the developed sucker can easily lift up smooth planar objects and 3D objects,and can grip objects both smaller and larger than the size of the sucker,which have a difficulty for conventional suckers or friction-based grippers.The potential application of the sucker in flexible transfer robot is demonstrated on various surfaces and environments,paving the way for further bio-inspired adhesive designs for both dry and wet scenarios.

Adhesion and peeling of a Fugu coal molecule on a graphene substrate: molecular dynamics simulations

Controlling coal dust produced in the process of underground coal mining is imperative because it can cause serious health problems,such as pneumoconiosis.In the present work,we have conducted a comprehensive investigation of the adhesion and peeling process of a coal molecule on graphene using molecular dynamics(MD)simulation.First,we simulate the adhesion of a coal molecule on a graphene substrate,where the critical adhesion distance and adhesion force are analyzed.Next,the process of a coal molecule peeled from the substrate is simulated,the equilibrium configurations,loading position,peeling force,and peeling angle of which are discussed.After comparing the MD simulation results with those of continuum models,we conclude that they are in excellent agreement.These analyses have deepened our understanding of the interplay between coal molecules and solid surfaces,which may prove beneficial when creating scientific methods of dust control.

A Visco-hyperelastic Constitutive Model for Rubber Considering the Strain Level and One Case Study in the Sealing Packer

The rubber cylinder is a key component for maintaining the sealing pressure of the packer,particularly in deep underground wells.The stress relaxation of materials,as a typical feature of viscoelasticity,has become one of the main factors causing the failure of rubber cylinders in service.In the present study,a visco-hyperelastic model for the sealing rubber considering different strain levels is proposed based on the Prony series.Subsequently,the uniaxial compression stress relaxation experiments are conducted on the sealing rubber under different temperatures and strain levels,and the model parameters are thereby identified.As a case study,the proposed model is incorporated into the ABAQUS software via the UM AT subroutine,and the finite element simulation of the sealing packer is carried out.The results show that the sealing performance of the packer improves with a decrease in temperature or an increase in strain level.It is also noted that a large strain level can lead to the protrusion of the shoulder of the rubber cylinder.

POST-BUCKLING BEHAVIOR OF A DOUBLE-HINGED ROD UNDER SELF-WEIGHT

Post-buckling phenomena of slender rods have attracted great attention for both theoretical and engineering aspects. In this study, we explored the post-buckling behavior of a slender rod with two hinged ends under its self-weight. We first established the potential energy functional of the system, and then derived the governing differential equations according to the principle of least potential energy. We further addressed the physical meaning of the Lagrange multiplier by analyzing the force equilibrium. A computer code of shooting method was developed by using the commercial software MathCAD, which has proved efficient in computing the post- buckling configurations of the rod. We finally discussed the buckling of an oil sucker rod adopting our numerical results, which will be beneficial to the engineering design.

Fracture Prediction for an Advanced High-Strength Steel Sheet Using the Fully Coupled Elastoplastic Damage Model with Stress-State Dependence

In this study,the numerical simulations of sheet metal forming processes are performed based on a fully coupled elastoplastic damage model.The effects of stress triaxiality and Lode angle are introduced into the damage evolution law to capture the loading-path-dependent failure.The proposed constitutive model is implemented into the finite element(FE)code ABAQUS/Explicit via the user-defined subroutine(VUMAT).Next,the identification procedure for DP780 based on the hybrid experimental-numerical method is presented in detail.The numerical results of simple tests are compared with the experiments,and obvious improvement is observed for the proposed model under various loading paths.Finally,the model is applied to predict the edge fracture during sheet blanking process.The predicted global load–displacement responses and crack paths have a good agreement with the experimental results,indicating that the model holds great potentials in simulation of metal forming processes.

喷雾冷却的瞬态传热特性

本文搭建旋流式喷雾冷却实验系统,研究喷雾冷却的随喷雾流态演化的瞬态传热效率.实验观测初始温度为300°C的高热壁面的喷雾冷却过程.冷却工质为水,冷却试件为铝合金方块,面积为20 mm×20 mm.利用5根高精度热电偶测量冷却试件竖直方向均布5个测点的温度变化,并结合有限差分法求解一维非稳态热传导方程,反演获得表面热流曲线.实验通过改变喷雾高度和喷雾流量,得到不同工况下瞬态热流密度的演化曲线.结果表明,喷雾冷却过程可分为4个阶段:I.Leidenfrost效应阶段(缓慢上升),II.液膜形成阶段(急剧上升),III.沸腾阶段(逐步下降),IV.对流蒸发阶段(趋于平衡).冷却过程由液膜形成阶段(第II阶段)向沸腾阶段(第III阶段)转变时,热流密度达到峰值;与工质压力影响相比,喷雾高度对液膜影响作用更为显著,5 mm喷雾高度下的换热能力要远高于10 mm及15 mm的工况,合适的喷雾高度是促进喷雾冷却散热的重要因素.

Graphene/ZnO single-mode lasing

Zinc oxide(ZnO)is a traditional Ⅱ–Ⅵ semiconductor material.Owing to its direct wide band gap and high exciton binding energy,ZnO has been considered as one of the most promising ultraviolet(UV)lasing materials.Its lasing performance has been widely explored for two decades[1–4].To realize high-quality high-performance lasers,excellent optical cavities are needed.Among various methods to synthesize ZnO microstructure

Effects of mask wearing duration and relative humidity on thermal perception in the summer outdoor built environment

During the pandemic,face masks are one of the most significant self-protection necessities,but they also cause heat stress.By using the ERA5(ECMWF Reanalysis 5th Generation)database and the local weather bureau data,the effect of mask wearing on outdoor thermal sensation has been investigated by a survey conducted in the hot summer and cold winter region of eastern China in the summer of 2020.Results show that wearing a face mask for a longer period result in a higher level of discomfort,and the primary source of discomfort is hot and stuffy feelings.The effect of relative humidity is crucial for mask wearers in warm-biased thermal environments,as mean thermal sensation vote(TSV)peaks when environmental relative humidity reaches the range of 70%to 80%and decreases after this range due to the evaporation within the microclimate created by a face mask.Meanwhile,prolonged mask wearing increases participants’hot feelings,especially in warm environments.Specifically,participants wearing face masks for less than 30 min feel hot at a physiological equivalent temperature(PET)value of 34.4℃,but those who wear them for over 60 min express hot feelings even at a PET value of 24.7℃.The participants who wear a face mask while walking slowly outdoors have similar thermal sensations to those who do not wear a mask,but are in a higher activity level.The findings demonstrate that mask wearing has a crucial impact on outdoor thermal comfort assessment in a warm-biased outdoor thermal environment.