Anal fistula is one of the three greatest anorectal diseases with a high prevalence.The traditional treatments(e.g.,surgery) for fistula have limitations due to damage to the internal anal sphincter of patients.With recent advances in biomaterials,treatments based on biomaterial filling (e.g.,scleraprotein injection,fistula plug) have emerged as novel therapies for fistula.The anal fistula plug(e.g.,based on small intestinal submucosa(SIS)) has attracted increasing attention because of short term healing rate and biocompatibility.However,challenges remain for this method such as plug falling as observed in clinics.To address this,this paper analyzes the case of SIS falling under physiological condition from mechanical point of view using ANSYS simulation.It then proposes three new geometrical structures for fistula plug and compares their mechanical behavior(e.g.,axial stress,reaction of constraint) with that of clinically used structure(cone shape).Based on the simulation,it optimizes the geometric parameters of fistula plug.The approach developed here can help to improve the design of fistula plug for better clinical treatments.
Shunli YangBin JiangFeng XuMin LinGuiping ZhaoTianjian Lu
The natural convective heat transfer performance and thermo-fluidic characteristics of honeycombs with/without chimney extensions are numerically investigated.The present numerical simulations are validated by the purposely-designed experimental measurements on honeycombs with/without chimney.Good agreement between numerical simulation and experimental measurement is obtained.The influences of inclination angle and geometric parameters such as cell shape,streamwise and spanwise length are also numerically quantified.With the increment in inclination angle,the overall heat transfer rate decreases for the honeycombs with/without chimney.For honeycombs with the same void volume fraction but different cell shapes,there is little difference on the overall heat transfer rate.To enhance the natural convective heat transfer of honeycombs,these techniques including increasing the length of honeycomb in the streamwise/spanwise direction,increasing the thermal conductivity of hon-eycomb structure or adding a chimney extension may be helpful.
YANG XiaoHuYAN HongBinWANG WenBinJIN LiWenLU TianJianICHIMIYA Koichi
The solidification behavior of two-phase heterogeneous materials such as close-celled aluminum foams was analytically studied.The proposed analytical model can precisely predict the location of solidification front as well as the full solidification time for a two-phase heterogeneous material composed of aluminum melt and non-conducting air pores.Experiments using distilled water simulating the aluminum melt to be solidified(frozen)were subsequently conducted to validate the analytical model for two selected porosities(ε),ε=0 and 0.5.Full numerical simulations with the method of finite difference were also performed to examine the influence of pore shape on solidification.The remarkable agreement between theory and experiment suggests that the delay of solidification in the two-phase heterogeneous material is mainly caused by the reduction of bulk thermal conductivity due to the presence of pores,as this is the sole mechanism accounted for by the analytical model for solidification in a porous medium.
Recent development of ultralightweight lattice-cored sandwiches is reviewed,with focus placed on various novel fabrication methods introduced to strengthen these structures,covering not only research results published in the Science China Series E-Tech Sci,but also those in other domestic and overseas scientific journals.
LU TianJian 1 &ZHANG QianCheng 2 1 MOE Key Laboratory for Strength and Vibration,School of Aerospace,Xi’an Jiaotong University,Xi’an 710049,China
Self-oscillating polymer gels driven by Belousov-Zhabotinsky (BZ) chemical reaction are a new class of functional gels that have a wide range of potential applications (e.g., autonomously functioning membranes, actuate artificial muscles). However, the precise control of these gels has been an issue due to limited investigations of the influences of key system parameters on the characteristics of BZ gels. To address this deficiency, we studied the self-oscillating behavior of BZ gels using the nonline-ar dynamics theory and an Oregonator-like model, with focus placed upon the influences of various system parameters. The analysis of the oscillation phase indicated that the dynamic response of BZ gels represents the classical limit cycle oscillation. We then investigated the characteristics of the limit cycle oscillation and quantified the influences of key parameters (i.e., ini-tial reactant concentration, oxidation and reduction rate of catalyst, and response coefficient) on the self-oscillating behavior of BZ gels. The results demonstrated that sustained limit cycle oscillation of BZ gels can be achieved only when these key pa-rameters meet certain requirements, and that the pattern, period and amplitude of the oscillation are significantly influenced by these parameters. The results obtained in this study could enable the controlled self-oscillation of BZ gels system. This has several potential applications such as controlled drug delivery, miniature peristaltic pumps and microactuators.
WANG PengFei1, ZHOU JinXiong1, LI MeiE2, XU Feng1,3 & LU TianJian1 1 Biomedical Engineering and Biomechanics Center, SV Laboratory, Xi’an Jiaotong University, Xi’an 710049, China
